1 Steam Cars : Phorum
General Steam Car topics
Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 23, 2002 09:07PM
<HTML> Thanks to John Woodson this tremendously creative website discussion board keeps growing tentacles from original discussion titles into ever increasing other subjects.
As we have had several boiler discussions/pro and con/ on other threads that relate to other subjects than boilers maybe we could have a separate "Boiler" topic to share our individual thoughts/knowledge and experiences on this one important subject.
Comparisons of weight/output/controlability/stability/specific outputs etc. can be all thrown into one thread. Stanley, Doble, Velox, White, Lamont, Sulzer, B&W, Vorkauf,
Schmidt, revolving boilers---lets have a good go at it.
As you have all figured out by now I am a Lamont freaky as it is(I believe) the simplest solution to all of a monotubes problems and virtually eliminates carbon problems from oil contaminated feedwater as anyone can surmise from my input in the "papers" section. Recently, on another thread topic, I gave some numbers for our small Lamont. The figures were for a 4 GPH firing rate, not its maximum design firing rate of 8 GPH, then the pounds of steam per pounds of total boiler weight would be 2#steam/# boiler weight. This is for a boat/ship boiler designed to always perform at maximum output unlike a car where that condition is rarely approached---the Teel made Lamont boiler of 300# weight is very conservatively rated with large factors of safety as it is for a hopefully 20mph 25 foot boat. For an automobile it would be top fired, the boat Lamont is bottom fired.
George</HTML>
As we have had several boiler discussions/pro and con/ on other threads that relate to other subjects than boilers maybe we could have a separate "Boiler" topic to share our individual thoughts/knowledge and experiences on this one important subject.
Comparisons of weight/output/controlability/stability/specific outputs etc. can be all thrown into one thread. Stanley, Doble, Velox, White, Lamont, Sulzer, B&W, Vorkauf,
Schmidt, revolving boilers---lets have a good go at it.
As you have all figured out by now I am a Lamont freaky as it is(I believe) the simplest solution to all of a monotubes problems and virtually eliminates carbon problems from oil contaminated feedwater as anyone can surmise from my input in the "papers" section. Recently, on another thread topic, I gave some numbers for our small Lamont. The figures were for a 4 GPH firing rate, not its maximum design firing rate of 8 GPH, then the pounds of steam per pounds of total boiler weight would be 2#steam/# boiler weight. This is for a boat/ship boiler designed to always perform at maximum output unlike a car where that condition is rarely approached---the Teel made Lamont boiler of 300# weight is very conservatively rated with large factors of safety as it is for a hopefully 20mph 25 foot boat. For an automobile it would be top fired, the boat Lamont is bottom fired.
George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 24, 2002 10:56AM
<HTML>Hi George,
The steam generator I am designing is highly experimental and not recommended. It is an idea I want to try, and see if/how it works. If it works, I think its light weight and low cost will be worth the effort.
I don't have the notebook with the full rundown handy (it went missing after a recent office cleanup), but the specs I recall are approximately 22" OD x 22" high, 120 lbs weight, 75 square feet gas-side area. Once-through water flow is planned. The tube stack is a combination of 8 parallel paths in water heating/evaporating section with monotube in final evaporating/superheater section. Per advice of Jim Crank, carbon buildup is expected, and the relatively short monotube section is to be made easily removeable for cleaning or replacement with unions for this purpose. The very compact tube stack should weigh approximately 80 lbs..
This light weight will make control system development very difficult. I have a unique control system design, with several subsystem options, which I am currently keeping under wraps for possible patent reasons. I will say that firing rate and water feed are continuously-variable rather than staged or on/off, and that demand-anticipating and fast-reacting overheat fuel trim/shutoff features are essential. I have plans for an all-mechanical control system which I think will work, though possible electronic control for part of the system is now being investigated with help from new electronics adviser Peter Heid.
If SES could make their ultralight tube stack work reliably, my experimental concept boiler should be easy in comparison. SES got 3-4x the steam rate from the same weight and square footage of tubing.
1/4" steel tubing is planned for the multi-path section, and 1/2" ID chromoly(?) in the hot-end monotube section. The 1/4" tubing is very inexpensive per square foot of heating area and easily bent. Water flows downward through the tube stack, which is bottom-fired, and the multipath elements have water traps similar in concept to the White boiler. The identical multipath elements will have radial symmetry and will be made individually removeable for inspection, repair, or replacement. The monotube section is 2-3 conventional pancake coils and these shield the small tubing above from radiant heat; nested multipath elements are of an odd shape which would be very difficult to describe and will require unusual jigs & bending methods (though not great difficulty) to fabricate.
Planned firing rate 8 gph, steam rate (@500 psi & 700°F max, but variable in operation) ~700 lbs/hr. That would give 5.83 lbs/hr steam per lb of boiler weight -- if it works. I think the relatively conservative engine I am designing will be able to get about 40 hp at the wheels out of this. Scaled-up 80 and 120 hp systems, and a possible 240 hp version, are in preliminary planning in case this concept works out. Many of these specs will probably change during/after construction and testing. Nothing is written in stone here.
If it flops, next boiler will be a Lamont!
Peter</HTML>
The steam generator I am designing is highly experimental and not recommended. It is an idea I want to try, and see if/how it works. If it works, I think its light weight and low cost will be worth the effort.
I don't have the notebook with the full rundown handy (it went missing after a recent office cleanup), but the specs I recall are approximately 22" OD x 22" high, 120 lbs weight, 75 square feet gas-side area. Once-through water flow is planned. The tube stack is a combination of 8 parallel paths in water heating/evaporating section with monotube in final evaporating/superheater section. Per advice of Jim Crank, carbon buildup is expected, and the relatively short monotube section is to be made easily removeable for cleaning or replacement with unions for this purpose. The very compact tube stack should weigh approximately 80 lbs..
This light weight will make control system development very difficult. I have a unique control system design, with several subsystem options, which I am currently keeping under wraps for possible patent reasons. I will say that firing rate and water feed are continuously-variable rather than staged or on/off, and that demand-anticipating and fast-reacting overheat fuel trim/shutoff features are essential. I have plans for an all-mechanical control system which I think will work, though possible electronic control for part of the system is now being investigated with help from new electronics adviser Peter Heid.
If SES could make their ultralight tube stack work reliably, my experimental concept boiler should be easy in comparison. SES got 3-4x the steam rate from the same weight and square footage of tubing.
1/4" steel tubing is planned for the multi-path section, and 1/2" ID chromoly(?) in the hot-end monotube section. The 1/4" tubing is very inexpensive per square foot of heating area and easily bent. Water flows downward through the tube stack, which is bottom-fired, and the multipath elements have water traps similar in concept to the White boiler. The identical multipath elements will have radial symmetry and will be made individually removeable for inspection, repair, or replacement. The monotube section is 2-3 conventional pancake coils and these shield the small tubing above from radiant heat; nested multipath elements are of an odd shape which would be very difficult to describe and will require unusual jigs & bending methods (though not great difficulty) to fabricate.
Planned firing rate 8 gph, steam rate (@500 psi & 700°F max, but variable in operation) ~700 lbs/hr. That would give 5.83 lbs/hr steam per lb of boiler weight -- if it works. I think the relatively conservative engine I am designing will be able to get about 40 hp at the wheels out of this. Scaled-up 80 and 120 hp systems, and a possible 240 hp version, are in preliminary planning in case this concept works out. Many of these specs will probably change during/after construction and testing. Nothing is written in stone here.
If it flops, next boiler will be a Lamont!
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 24, 2002 12:36PM
<HTML>Peter,
Good luck on your lightweight boiler, a big disadvantage of the Lamont is the drum weight and space for it(8" diameter). Yes SES made a super small and lightweight boiler but it never ran on the road---it had a few hundred wires and thermocouples coming out of it plugged into several electronics racks. Back then it would have been impossible to make a car installed computer for it.
It was really hairy edge stuff, of course on the dyno one can slowly change output conditions to keep the finned tubing from burning out. Remember, it took a huge amount of hydraulic horsepower to get the combustion gases thru it. I prefer the KISS method and boiler reserve. Didn't Richard Smith use a mixture of GUNK engine degreaser and water to keep his monotube boilers clean???
George</HTML>
Good luck on your lightweight boiler, a big disadvantage of the Lamont is the drum weight and space for it(8" diameter). Yes SES made a super small and lightweight boiler but it never ran on the road---it had a few hundred wires and thermocouples coming out of it plugged into several electronics racks. Back then it would have been impossible to make a car installed computer for it.
It was really hairy edge stuff, of course on the dyno one can slowly change output conditions to keep the finned tubing from burning out. Remember, it took a huge amount of hydraulic horsepower to get the combustion gases thru it. I prefer the KISS method and boiler reserve. Didn't Richard Smith use a mixture of GUNK engine degreaser and water to keep his monotube boilers clean???
George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: tom ward (IP Logged)
Date: July 24, 2002 10:17PM
<HTML>I plan to experiment with what I call the BB boiler. It is essentially 3 concentric metal pipes with boiler plate at each end. The interior of the two inner sections would be filled with small metal spheres like BB's. The innermost section is like the water tubes. The section around that is like the fire tubes. The outermost section would be a thermal storage section a la Lamont. My math says it would have an effective exchange area 10 to 100 times per unit volume of any tube boiler concept and would be less expensive to construct and easier to service. But then again I'm not one of those college trained minds. Neither were the Wright Brothers or Tom Edison.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 25, 2002 04:11AM
<HTML>Hi Tom,
Yes, BBs and other types of small elements (wire, metal wool, thin plates, etc) give many times the heat-transfer surface area for a given volume. Relative to conventional tubes that is. You might have to sinter or braze the BBs to each other and to the wall between the hot gas and steam sections, as heat transfers very poorly between two pieces of metal which are merely touching with loose contact and small area of contact. That is to avoid melted BB's. Dip brazing would be pretty simple for something like this. Interesting boiler concept!
Peter</HTML>
Yes, BBs and other types of small elements (wire, metal wool, thin plates, etc) give many times the heat-transfer surface area for a given volume. Relative to conventional tubes that is. You might have to sinter or braze the BBs to each other and to the wall between the hot gas and steam sections, as heat transfers very poorly between two pieces of metal which are merely touching with loose contact and small area of contact. That is to avoid melted BB's. Dip brazing would be pretty simple for something like this. Interesting boiler concept!
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 25, 2002 05:13AM
<HTML>Hi George,
SES really pushed things to the ragged edge! I would not want to try their weight/steam output ratio. The cabinets of electronics which they used could probably be replaced with a small "black box" today -- probably with simpler hardware and software than what is found in the control units of today's gas cars.
My boiler design is a lot tamer and should be easier to control. In another steam forum, one of the SES engineers said that if the SES controls konked out, they could run the engine for about 30 seconds before the boiler ran out of steam. With a fraction of the steam coming from the same type/weight of tube stack (however different the actual design), I should have more reserve power than that. Still not much, but better than the reserve power of a gas car after something stops working.
The ~300-lb Scott-Newcomb once-thru tube stack would run the car over a mile with fire off; assuming same pressure/temp and similar heat distribution, mine would go perhaps 1/3 of a mile with no fire, installed in a much lighter car. So there is some stored energy; even with this very light weight, it is not a true "instantaneous steam generator".
RJ Smith, I recall reading, also used 1/4" tubing in some of his steam generators, and yes, I have read of his Gunkoleum mix. At this point, I don't think this will be necessary in my system. However, I do wonder if some of that Gunk would solve the carbon problem with once-through steam generators.
One feature of my design is that the gas flowpath area is quite large -- calculated to be about the same "square inches per GPH firing rate" as in Stanley boilers and others using vaporizing burners. So the combustion pressure should be very low, and if a fan burner were used (as I am investigating for a solid-fueled version) the fan hp would also be quite low. The tradeoff is that the combustion chamber, tube stack, and exhaust flue take up a lot more volume than is theoretically possible with a high burner pressure. The smaller tubing makes up for some of this, but it is still a much larger boiler than is theoretically possible.
I too prefer KISS and stored energy, but I also like cheap and lightweight, and finding a certified welder for a Lamont drum, and working out the circulating pump, would probably be more difficult for me than finishing the control system for the light boiler. I have the (surprisingly simple) control system concept worked out, and the components sketched and largely dimensioned, leaving only the problems of building, testing, and calibration. For others, the Lamont is an easier way to go. Everybody has his own budget, areas of expertise, and fabrication skills level. I think this is part of the reason why there have always been a lot of different systems used in steam cars. One guy's "cheap and easy" is another guy's wallet-busting nightmare.
The Lamont's weight and size are only "disadvantages" compared to unproven experimental designs like the SES and mine. Relative to most proven monotube systems, the Lamont's size and weight are quite acceptable for automotive use, and that is the real standard to go by. Your boiler has an actual advantage; wilder experimental boilers have only potential future advantages. A bird in the hand is worth two in the bush.
That is why the Lamont is currently my "backup design". I do have some ideas for making a Lamont lighter, cheaper and easier to build, but those are on the back burner for now.
Peter</HTML>
SES really pushed things to the ragged edge! I would not want to try their weight/steam output ratio. The cabinets of electronics which they used could probably be replaced with a small "black box" today -- probably with simpler hardware and software than what is found in the control units of today's gas cars.
My boiler design is a lot tamer and should be easier to control. In another steam forum, one of the SES engineers said that if the SES controls konked out, they could run the engine for about 30 seconds before the boiler ran out of steam. With a fraction of the steam coming from the same type/weight of tube stack (however different the actual design), I should have more reserve power than that. Still not much, but better than the reserve power of a gas car after something stops working.
The ~300-lb Scott-Newcomb once-thru tube stack would run the car over a mile with fire off; assuming same pressure/temp and similar heat distribution, mine would go perhaps 1/3 of a mile with no fire, installed in a much lighter car. So there is some stored energy; even with this very light weight, it is not a true "instantaneous steam generator".
RJ Smith, I recall reading, also used 1/4" tubing in some of his steam generators, and yes, I have read of his Gunkoleum mix. At this point, I don't think this will be necessary in my system. However, I do wonder if some of that Gunk would solve the carbon problem with once-through steam generators.
One feature of my design is that the gas flowpath area is quite large -- calculated to be about the same "square inches per GPH firing rate" as in Stanley boilers and others using vaporizing burners. So the combustion pressure should be very low, and if a fan burner were used (as I am investigating for a solid-fueled version) the fan hp would also be quite low. The tradeoff is that the combustion chamber, tube stack, and exhaust flue take up a lot more volume than is theoretically possible with a high burner pressure. The smaller tubing makes up for some of this, but it is still a much larger boiler than is theoretically possible.
I too prefer KISS and stored energy, but I also like cheap and lightweight, and finding a certified welder for a Lamont drum, and working out the circulating pump, would probably be more difficult for me than finishing the control system for the light boiler. I have the (surprisingly simple) control system concept worked out, and the components sketched and largely dimensioned, leaving only the problems of building, testing, and calibration. For others, the Lamont is an easier way to go. Everybody has his own budget, areas of expertise, and fabrication skills level. I think this is part of the reason why there have always been a lot of different systems used in steam cars. One guy's "cheap and easy" is another guy's wallet-busting nightmare.
The Lamont's weight and size are only "disadvantages" compared to unproven experimental designs like the SES and mine. Relative to most proven monotube systems, the Lamont's size and weight are quite acceptable for automotive use, and that is the real standard to go by. Your boiler has an actual advantage; wilder experimental boilers have only potential future advantages. A bird in the hand is worth two in the bush.
That is why the Lamont is currently my "backup design". I do have some ideas for making a Lamont lighter, cheaper and easier to build, but those are on the back burner for now.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 25, 2002 10:34AM
<HTML>Peter,
Thanks for the great post. It is too bad that my old MIT friend Hal Fuller does not have a computer, he did much of the work and testing on the SES car and owns it, he was(or is) the last steam engineer at Skinner Engine Company that went into chapter 11 last year due to asbestos lawsuits---they are closing down their steam engine division :>( . Hal could fill us in on that stuff and had on occassion written to the SACA bulletin. The Scott Newcomb design was very nice, John Wetz built one years ago and wrote it up in SACA. It actually would be easy to make and the inner truncated coil could be "Lamontized" to protect it.
As far as your boiler and large gas pass area have you applied the info on crossflow gases in that B&W book?? Being as crazy as my last name always theoretically calculate the heat transfer of each coil stack, the tube wall temperature differentials, each gas mass flow number,
using all their formulas plus inclue radiation and intertube radiation. If you don't have adequate gas velocity(and Reynolds number) you may find out that your stack temperature is going to be very high. The poor 23" Stanley had virtually no gas velocity at all, purely laminar flow without turbulence. It would only evaporate 300-400#/hr with a 4-6GPH firing rate or about 3 to 4#/hr/square foot(having about 100 square feet of total heating area. What a waste of 1000 feet of boiler tubing, its only saving graces were great thermal storage and a long time constant that made controls easy.
I also like "cheap and easy" and can't affor a boiler of my own right now, thats why I get others like Rod to pursue my follies!! Thank God it works very well. We plan a no-holds-barred test soon where we will try and force the boiler to go unstable by literally dumping the boiler and then slamming the throttle closed--see if we can get the water in the drum to go unstable. Find out how little and how much water can be in the Lamont drum, it could be that the drum could be half its present size.
Best, George</HTML>
Thanks for the great post. It is too bad that my old MIT friend Hal Fuller does not have a computer, he did much of the work and testing on the SES car and owns it, he was(or is) the last steam engineer at Skinner Engine Company that went into chapter 11 last year due to asbestos lawsuits---they are closing down their steam engine division :>( . Hal could fill us in on that stuff and had on occassion written to the SACA bulletin. The Scott Newcomb design was very nice, John Wetz built one years ago and wrote it up in SACA. It actually would be easy to make and the inner truncated coil could be "Lamontized" to protect it.
As far as your boiler and large gas pass area have you applied the info on crossflow gases in that B&W book?? Being as crazy as my last name always theoretically calculate the heat transfer of each coil stack, the tube wall temperature differentials, each gas mass flow number,
using all their formulas plus inclue radiation and intertube radiation. If you don't have adequate gas velocity(and Reynolds number) you may find out that your stack temperature is going to be very high. The poor 23" Stanley had virtually no gas velocity at all, purely laminar flow without turbulence. It would only evaporate 300-400#/hr with a 4-6GPH firing rate or about 3 to 4#/hr/square foot(having about 100 square feet of total heating area. What a waste of 1000 feet of boiler tubing, its only saving graces were great thermal storage and a long time constant that made controls easy.
I also like "cheap and easy" and can't affor a boiler of my own right now, thats why I get others like Rod to pursue my follies!! Thank God it works very well. We plan a no-holds-barred test soon where we will try and force the boiler to go unstable by literally dumping the boiler and then slamming the throttle closed--see if we can get the water in the drum to go unstable. Find out how little and how much water can be in the Lamont drum, it could be that the drum could be half its present size.
Best, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 26, 2002 08:08AM
<HTML>Hi George,
Hardly anyone in the world of steam experimentation is as thorough as you when it comes to mathematically analyzing original boiler designs. I certainly am not. I am still trying to digest the info in the B&W book, so that I can fill notebooks with heat transfer calculations as you do.
The general layout & characteristics of my current boiler concept, despite the odd tube size and some other differences, are very similar to the White steam generators, which made about 10 lbs/hr of steam per square foot of heat-transfer surface, if memory serves. These used vaporizing burners with lower fuel pressure than Stanleys (and lower than I plan), and had secondary air inlets in the burner grate too if I recall correctly, which also cuts gas pressure. On the basis of this & other simplified reasoning, I think that I should be able to duplicate the White lbs/sq ft evaporation rate.
Unfortunately, I have not been able to find info on the gas flowpath area of White tube stacks (I use a square inches/gph ratio). That is why I used the Stanley figure. If anything I may need to open up the flowpath. Due to the peculiar shape of the tube elements (not coils, strictly speaking) in the multipath zone, changing gas flowpath area should not be difficult, though it would require changing the case diameter and some other sheetmetal, insulation, etc rework. This steam generator's gas velocity should be lower than in a Stanley, but higher than in a White.
Gas velocity and aerodynamics, of course, are not the only factors in heat transfer; radiant heat, steam/water velocity (negligible in Stanley boilers), etc are also factors. My steam/water velocity should be about the same as White, and gas velocity (or at least pressure) higher than White. Radiant heating area about the same as a White of same output. Same modified counterflow regime. Smaller tubes in upper section should give more gas turbulence, but gas flow should be about the same due to higher pressure hopefully compensating for turbulence. I can always change fuel/gas pressure (and/or tube spacing) as needed to achieve design goal.
My current approach is to get in the ballpark with simple calculations, and then cut & try as needed to fine tune results. Hopefully I will not have to go thru 8 different tube stacks as SES did! The advantage of your calculation-intensive approach is that you end up far closer to the final working boiler on your first try, with a great reduction in trial & error work. I'm working toward that goal! A few successful monotube builders have told me that they used simplified-analysis "starting design" approaches very similar to mine, and that their subsequent modifications were not too daunting, which I find reassuring.
Does anybody know, offhand, the spacing between the tubes in a White tube stack? Often this is expressed as a ratio of tube diameter to distance between adjacent turns of tubing. In some monotubes with powerful fan burners, the space is reportedly 1/3 the tube diameter or so, but it varies according to a number of factors. I have never been able to locate the White gas-flowpath area information in print. Size of White exhaust flue would also be helpful in estimates; total gas flowpath in tube stack would have roughly 4x the exhaust flue cross-section area, I estimate. I have some of Prof. Carpenter's famous test result tables and other info to extrapolate from.
Getting to the first-time building stage with your own car-sized system is pricey and difficult; sounds like you found a great shortcut! I may yet convince one of my local friends to build my design. Currently, they seem convinced that I am a kook who will never build anything. Too many years of designing, learning more, then redesigning, I guess. Fortunately, the desire to demonstrate sanity can be a strong motivator. :)
Peter</HTML>
Hardly anyone in the world of steam experimentation is as thorough as you when it comes to mathematically analyzing original boiler designs. I certainly am not. I am still trying to digest the info in the B&W book, so that I can fill notebooks with heat transfer calculations as you do.
The general layout & characteristics of my current boiler concept, despite the odd tube size and some other differences, are very similar to the White steam generators, which made about 10 lbs/hr of steam per square foot of heat-transfer surface, if memory serves. These used vaporizing burners with lower fuel pressure than Stanleys (and lower than I plan), and had secondary air inlets in the burner grate too if I recall correctly, which also cuts gas pressure. On the basis of this & other simplified reasoning, I think that I should be able to duplicate the White lbs/sq ft evaporation rate.
Unfortunately, I have not been able to find info on the gas flowpath area of White tube stacks (I use a square inches/gph ratio). That is why I used the Stanley figure. If anything I may need to open up the flowpath. Due to the peculiar shape of the tube elements (not coils, strictly speaking) in the multipath zone, changing gas flowpath area should not be difficult, though it would require changing the case diameter and some other sheetmetal, insulation, etc rework. This steam generator's gas velocity should be lower than in a Stanley, but higher than in a White.
Gas velocity and aerodynamics, of course, are not the only factors in heat transfer; radiant heat, steam/water velocity (negligible in Stanley boilers), etc are also factors. My steam/water velocity should be about the same as White, and gas velocity (or at least pressure) higher than White. Radiant heating area about the same as a White of same output. Same modified counterflow regime. Smaller tubes in upper section should give more gas turbulence, but gas flow should be about the same due to higher pressure hopefully compensating for turbulence. I can always change fuel/gas pressure (and/or tube spacing) as needed to achieve design goal.
My current approach is to get in the ballpark with simple calculations, and then cut & try as needed to fine tune results. Hopefully I will not have to go thru 8 different tube stacks as SES did! The advantage of your calculation-intensive approach is that you end up far closer to the final working boiler on your first try, with a great reduction in trial & error work. I'm working toward that goal! A few successful monotube builders have told me that they used simplified-analysis "starting design" approaches very similar to mine, and that their subsequent modifications were not too daunting, which I find reassuring.
Does anybody know, offhand, the spacing between the tubes in a White tube stack? Often this is expressed as a ratio of tube diameter to distance between adjacent turns of tubing. In some monotubes with powerful fan burners, the space is reportedly 1/3 the tube diameter or so, but it varies according to a number of factors. I have never been able to locate the White gas-flowpath area information in print. Size of White exhaust flue would also be helpful in estimates; total gas flowpath in tube stack would have roughly 4x the exhaust flue cross-section area, I estimate. I have some of Prof. Carpenter's famous test result tables and other info to extrapolate from.
Getting to the first-time building stage with your own car-sized system is pricey and difficult; sounds like you found a great shortcut! I may yet convince one of my local friends to build my design. Currently, they seem convinced that I am a kook who will never build anything. Too many years of designing, learning more, then redesigning, I guess. Fortunately, the desire to demonstrate sanity can be a strong motivator. :)
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 26, 2002 09:02AM
<HTML>Hi George,
Hope you can cut the size of the Lamont drum; that would certainly make it more attractive to others considering what type of boiler to build. One idea I have been toying with (haven't done any calcs yet) is using a reserve coil instead of a drum, with a tiny steam/water cyclone separator at the Lamont coil outlet. Thus, water goes from reserve coil to pump, then to lamont coil, then to cyclone separator, then water returns to reserve coil while steam departs to engine via the superheater & throttle.
Reserve coil could be same tubing diameter as lamont coil, and same length or somewhat longer as needed. Not sure if coil would be heavier or lighter than drum, but would be easier to build, and could be wound around rest of boiler and insulated (?) from hot gas. Or it could be heated also, by convection.
Perhaps a radial-flow barrel coil layout with Lamont coil surrounding central burner, then superheater surrounding the Lamont, then the convection-heated reserve coil, then the economizer coils surrounding the whole thing. Downside is higher circulating pump hp requirement.
I remember reading John Wetz' Scott-Newcomb article; as I recall his version was solid-fueled. With a stoker burner, this tube stack would be idea for solid fuel.
If a Scott-Newcomb system could somehow be built to dispense with the electric water pump motor (perhaps with an auxiliary steam engine?), I think it would be a worthy project for experimenters, and perhaps refineable into a commercial design. The control system was incredibly simple. Fuel & water pumps on at 500 psig, and off at 600 psig. One firing rate, and a fixed fuel/water pumping ratio, which is possible with a single firing rate.
Problem: steam pressure fluctuated by 100 psi (no biggie), and temperature by about 150°F.. It is the temperature fluctuations that are troublesome, as steam engine performance can change quite a bit between 600 and 750°F -- from sluggish to wildly frisky.
And that nested conical barrel coil stack is a piece of cake to wind. Its 307 lbs or so of stainless steel smooth out the energy pulses from the on/off burner & water pump.
I once wondered about the idea of running a Scott-Newcomb's output through a small tube stack immersed in an insulated can of asphalt or other heat-storage medium. Or maybe running the steam through a small drum full of BBs or thin metal plates. This "heat capacitor" would absorb heat from steam during the hot part of the cycle, and release heat to steam during the cold part, thus further leveling out the steam temperature. Extra weight, but still simple controls and more stable temperature.
Then perhaps add a simple "leveling throttle" to give constant steam pressure at the control throttle. The heat capacitor would do some of this. Otherwise, the car's speed & power output could perceptibly fluctuate with a constant throttle setting, an annoyance.
Does Hal have any plans to get the SES car running on the road? That would be a challenging project!
Good luck with the Lamont dump test. Any new design should work well even when severely jerked around. We expect a full report, of course.
Peter</HTML>
Hope you can cut the size of the Lamont drum; that would certainly make it more attractive to others considering what type of boiler to build. One idea I have been toying with (haven't done any calcs yet) is using a reserve coil instead of a drum, with a tiny steam/water cyclone separator at the Lamont coil outlet. Thus, water goes from reserve coil to pump, then to lamont coil, then to cyclone separator, then water returns to reserve coil while steam departs to engine via the superheater & throttle.
Reserve coil could be same tubing diameter as lamont coil, and same length or somewhat longer as needed. Not sure if coil would be heavier or lighter than drum, but would be easier to build, and could be wound around rest of boiler and insulated (?) from hot gas. Or it could be heated also, by convection.
Perhaps a radial-flow barrel coil layout with Lamont coil surrounding central burner, then superheater surrounding the Lamont, then the convection-heated reserve coil, then the economizer coils surrounding the whole thing. Downside is higher circulating pump hp requirement.
I remember reading John Wetz' Scott-Newcomb article; as I recall his version was solid-fueled. With a stoker burner, this tube stack would be idea for solid fuel.
If a Scott-Newcomb system could somehow be built to dispense with the electric water pump motor (perhaps with an auxiliary steam engine?), I think it would be a worthy project for experimenters, and perhaps refineable into a commercial design. The control system was incredibly simple. Fuel & water pumps on at 500 psig, and off at 600 psig. One firing rate, and a fixed fuel/water pumping ratio, which is possible with a single firing rate.
Problem: steam pressure fluctuated by 100 psi (no biggie), and temperature by about 150°F.. It is the temperature fluctuations that are troublesome, as steam engine performance can change quite a bit between 600 and 750°F -- from sluggish to wildly frisky.
And that nested conical barrel coil stack is a piece of cake to wind. Its 307 lbs or so of stainless steel smooth out the energy pulses from the on/off burner & water pump.
I once wondered about the idea of running a Scott-Newcomb's output through a small tube stack immersed in an insulated can of asphalt or other heat-storage medium. Or maybe running the steam through a small drum full of BBs or thin metal plates. This "heat capacitor" would absorb heat from steam during the hot part of the cycle, and release heat to steam during the cold part, thus further leveling out the steam temperature. Extra weight, but still simple controls and more stable temperature.
Then perhaps add a simple "leveling throttle" to give constant steam pressure at the control throttle. The heat capacitor would do some of this. Otherwise, the car's speed & power output could perceptibly fluctuate with a constant throttle setting, an annoyance.
Does Hal have any plans to get the SES car running on the road? That would be a challenging project!
Good luck with the Lamont dump test. Any new design should work well even when severely jerked around. We expect a full report, of course.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 26, 2002 11:32AM
<HTML>Peter,
>>And that nested conical barrel coil stack is a piece of cake to wind. Its 307 lbs or so of stainless steel smooth out the energy pulses from the on/off burner & water pump.<<
Do you think the pulses are a problem? Some yeara ago, I built a lightweight steam generator (R. J. Smith design) and ran step inputs for both burner and for feedwater. Also sine wave inputs and graphed it all on a 6 or 8 channel HP chart recorder. As I recall the time constant was about 11 seconds for this boiler. I'll have to dig out the original charts.</HTML>
>>And that nested conical barrel coil stack is a piece of cake to wind. Its 307 lbs or so of stainless steel smooth out the energy pulses from the on/off burner & water pump.<<
Do you think the pulses are a problem? Some yeara ago, I built a lightweight steam generator (R. J. Smith design) and ran step inputs for both burner and for feedwater. Also sine wave inputs and graphed it all on a 6 or 8 channel HP chart recorder. As I recall the time constant was about 11 seconds for this boiler. I'll have to dig out the original charts.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 26, 2002 06:08PM
<HTML>Peter,
Good luck with the White style boiler, it was a marvelous system for its time. Glad you have the Carpenter data, check for yourself on the maximum 40HP test the amount of heat added to the feedwater to steam and divide by the heat input of the gallons of gasoline burned---think you will find the boiler about 65% efficient at that rate. Measuring actual flue gas temperature back then seemed to have lots of error, Doble in his "F" boiler runs had the same problem and lists corrected temperatures in the second table. A White owner told me "that the seat gets rather toasty" when really running hard, guess sitting on top of the boiler gives an indication of flue gas temperature. Another member of our club is building a White boiler but using additional coil stacks to get the flue gas temperature down to a reasonable value, believe he is going to use 12 coils. The last additional ones can be wound 1.25 ratio as several of this ratio have worked well on Stanleys as an added economiser.
Good luck, George</HTML>
Good luck with the White style boiler, it was a marvelous system for its time. Glad you have the Carpenter data, check for yourself on the maximum 40HP test the amount of heat added to the feedwater to steam and divide by the heat input of the gallons of gasoline burned---think you will find the boiler about 65% efficient at that rate. Measuring actual flue gas temperature back then seemed to have lots of error, Doble in his "F" boiler runs had the same problem and lists corrected temperatures in the second table. A White owner told me "that the seat gets rather toasty" when really running hard, guess sitting on top of the boiler gives an indication of flue gas temperature. Another member of our club is building a White boiler but using additional coil stacks to get the flue gas temperature down to a reasonable value, believe he is going to use 12 coils. The last additional ones can be wound 1.25 ratio as several of this ratio have worked well on Stanleys as an added economiser.
Good luck, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 26, 2002 07:26PM
<HTML>Hi George,
Thanks for the heads-up; I will check the data and do the math. 65% is too low. I may end up adding extra tubing on the top. Then again, the low output is where it counts most, and efficiency should be higher there.
Problem is, some time back I increased the steam rate design goal without increasing the square footage, thinking the White was closer to 80% -- oops. I probably heard efficiency figures for low firing rate, and didn't realize it would drop that low at full blast. One change often demands a dozen others, and only doing 11 is a goof. Current ratio is 1:1 -- need lots of space to get the gas thru.
I have to study up on the detailed heat transfer calcs so I have a better idea of what is going on in the boiler, and how much tubing to add.
Planning on 1" Fiberfrax all around, so hopefully the hood (in this case) won't get too toasty. Maybe SES could get a 700 lb/hr steam generator under a modern bucket seat, but not me. Guess I'll have to add a heater.
Peter</HTML>
Thanks for the heads-up; I will check the data and do the math. 65% is too low. I may end up adding extra tubing on the top. Then again, the low output is where it counts most, and efficiency should be higher there.
Problem is, some time back I increased the steam rate design goal without increasing the square footage, thinking the White was closer to 80% -- oops. I probably heard efficiency figures for low firing rate, and didn't realize it would drop that low at full blast. One change often demands a dozen others, and only doing 11 is a goof. Current ratio is 1:1 -- need lots of space to get the gas thru.
I have to study up on the detailed heat transfer calcs so I have a better idea of what is going on in the boiler, and how much tubing to add.
Planning on 1" Fiberfrax all around, so hopefully the hood (in this case) won't get too toasty. Maybe SES could get a 700 lb/hr steam generator under a modern bucket seat, but not me. Guess I'll have to add a heater.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Jim Crank (IP Logged)
Date: July 27, 2002 02:41PM
<HTML>Peter and George,
The White generator had very large gas passages between the turns of the coils because the burner was atmospheric and no blower.
Yes the stack was hot as hell!! I wanted to put two finned coils in my 1910 White; but couldn't. It would mean dropping the whole generator some 3" and then it sure would have hit the driveshaft. Whites often had a nice wide groove hammered into the bottom of the burner when the driveshaft banged into it going over rough roads. Mine did.
Jim</HTML>
The White generator had very large gas passages between the turns of the coils because the burner was atmospheric and no blower.
Yes the stack was hot as hell!! I wanted to put two finned coils in my 1910 White; but couldn't. It would mean dropping the whole generator some 3" and then it sure would have hit the driveshaft. Whites often had a nice wide groove hammered into the bottom of the burner when the driveshaft banged into it going over rough roads. Mine did.
Jim</HTML>
Re: Boilers only- Bonecourt
Posted by: Peter Heid (IP Logged)
Date: July 29, 2002 12:53AM
<HTML>The concept of the bonecourt boiler has plagued my mind lately with all this boiler only discussion. The boiler was designed as a fire tube design in which catylitic combustion was used to provide the heat. Combustable gasses are drawn in with the correct amount of air by an exhaust fan and burned as a flame until the temperature is high enough, at which point the fuel is briefly shut off and turned on again to provide catylitic firing. All accounts of the bonecourt indicate efficiencies over 90% after subtracting the exhaust fan consumption. The water is preheated in a economiser built of the same design as the boiler, passing the exhaust gasses through and exiting at the exhaust fan. Yes, I know, I am talking about a fire tube boiler and its associtated hazards but what if the boiler drum were its self, a tube containing the inner fire tube. These tube assemblies could be made in modular form for easy sizing to the vehicle and for replacement. Water can be circulated around the fire tube in Lamont fashion and stored in a drum. It would seem most advantagous to keep the fire inside the water for any heat leaving the fire would have to pass through the water or exit with the exhaust. It is interesting to note that the bonecourt boiler was designed to drain condensate from the economiser gas passages, as exhaust gas temperatures were below 300 degrees F.. The problem then becomes condensation of corrosive products of combustion and the destruction they can cause. With proper firing conditions and the correct fuel it would seem acid condensation could be held to a level low enough to prevent corrosion and still allow very low stack temperatures.
Peter Heid</HTML>
Peter Heid</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 29, 2002 08:05AM
<HTML>Hi George & Jim,
Did some math and figure this boiler needs about 50% more heating area for acceptable economy. The hot-end monotube section is too heavy & bulky, so am considering either eliminating the quick-change hot-end coil or making it multipath. Maybe some of that Dick Smith Gunkoleum would eliminate the carbon problem & need for quick-change hot tubes; nasty solution though. As I recall, he successfully (?) used 1/4" tubing in the superheat zone.
The multipath quick-change hot end unit I sketched up can be removed from above with a wrench, then dropped and slid out from under car; no crawling under the (low-slung modern) vehicle with tools. It weighs 11 lbs instead of 42 lbs for the monotube section, and reduces tube stack height enough to allow the extra cold-end tubing on top w/o increased unit height. A boiler for a modern car cannot be taller than about 24" unless one digs groovy hood bulges.
Even without oil problems, though, an E-Z-change hot-end section is nice in case of control system failures, which are likely during development work.
I also have some ideas for keeping the hot end tubing below oil-carbonizing temperature at all times. The control system will not be a White or Doble type. I want to monitor hottest tube temp rather than just steam temp. Closing the throttle after a high firing rate seems to be "problem time". The anticipating fire-control feature should help, and perhaps hot-end water injection (problematic) and venting some steam off hot end to feedwater heater (via vented engine cylinders?) during throttle-closed/burner on conditions. I think that very brief venting would waste little steam, and the vented steam's heat goes into water heater and right back into boiler anyway (entropic, though).
Feedwater heater has a built-in oil separating feature, so there should be much less oil in the boiler to begin with. I think that some trace oil is desireable, though.
I have an updated preliminary design with 112.5 sf area, still ~24" tall x 22" diameter, now approx. 150 lbs weight. Amazing how some ideas make the size and weight soar. I have some finned tubing on hand but would like to avoid using it to cut post-prototype cost and possible fin-clogging problems. I now plan to master & apply the "Nutzian Total Analysis Method" :) before building. A more complete analysis will probably lead to more redesign.
The basic concept here is definitely low-tech oldtime stuff, at least by today's standards. As long as I can get it working acceptably ...
Peter</HTML>
Did some math and figure this boiler needs about 50% more heating area for acceptable economy. The hot-end monotube section is too heavy & bulky, so am considering either eliminating the quick-change hot-end coil or making it multipath. Maybe some of that Dick Smith Gunkoleum would eliminate the carbon problem & need for quick-change hot tubes; nasty solution though. As I recall, he successfully (?) used 1/4" tubing in the superheat zone.
The multipath quick-change hot end unit I sketched up can be removed from above with a wrench, then dropped and slid out from under car; no crawling under the (low-slung modern) vehicle with tools. It weighs 11 lbs instead of 42 lbs for the monotube section, and reduces tube stack height enough to allow the extra cold-end tubing on top w/o increased unit height. A boiler for a modern car cannot be taller than about 24" unless one digs groovy hood bulges.
Even without oil problems, though, an E-Z-change hot-end section is nice in case of control system failures, which are likely during development work.
I also have some ideas for keeping the hot end tubing below oil-carbonizing temperature at all times. The control system will not be a White or Doble type. I want to monitor hottest tube temp rather than just steam temp. Closing the throttle after a high firing rate seems to be "problem time". The anticipating fire-control feature should help, and perhaps hot-end water injection (problematic) and venting some steam off hot end to feedwater heater (via vented engine cylinders?) during throttle-closed/burner on conditions. I think that very brief venting would waste little steam, and the vented steam's heat goes into water heater and right back into boiler anyway (entropic, though).
Feedwater heater has a built-in oil separating feature, so there should be much less oil in the boiler to begin with. I think that some trace oil is desireable, though.
I have an updated preliminary design with 112.5 sf area, still ~24" tall x 22" diameter, now approx. 150 lbs weight. Amazing how some ideas make the size and weight soar. I have some finned tubing on hand but would like to avoid using it to cut post-prototype cost and possible fin-clogging problems. I now plan to master & apply the "Nutzian Total Analysis Method" :) before building. A more complete analysis will probably lead to more redesign.
The basic concept here is definitely low-tech oldtime stuff, at least by today's standards. As long as I can get it working acceptably ...
Peter</HTML>
Re: Boilers only- Bonecourt
Posted by: Peter Brow (IP Logged)
Date: July 29, 2002 08:14AM
<HTML>Hi Peter,
The Bonecourt boiler is definitely an intriguing idea. Wrangling with extra tubing myself, I like its high efficiency. But I wonder about variable firing rates and light-off. Seems like when it shuts off at a stop, or ramps down below a certain firing rate, the catalyst will quickly drop below light-off temperature, and will take a good bit of heat/fuel to heat it up again, esp with water/steam/metal pulling heat out of the catalyst at a rapid rate. The Bonecourt boiler may only be (extremely) good for steady-state operation.
Other Peter</HTML>
The Bonecourt boiler is definitely an intriguing idea. Wrangling with extra tubing myself, I like its high efficiency. But I wonder about variable firing rates and light-off. Seems like when it shuts off at a stop, or ramps down below a certain firing rate, the catalyst will quickly drop below light-off temperature, and will take a good bit of heat/fuel to heat it up again, esp with water/steam/metal pulling heat out of the catalyst at a rapid rate. The Bonecourt boiler may only be (extremely) good for steady-state operation.
Other Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 29, 2002 08:22AM
<HTML>Hi Terry,
A certain degree of pulsing isn't a problem. How steady were your temp/pressure results with the Smith boiler? I am especially interested in what size tubing you used, and whether you had any problems with corrosion or oil carbon buildup. Of course these might only show up after extensive operation with oily feedwater and/or no Smith-style "Gunk" treatment.
Peter</HTML>
A certain degree of pulsing isn't a problem. How steady were your temp/pressure results with the Smith boiler? I am especially interested in what size tubing you used, and whether you had any problems with corrosion or oil carbon buildup. Of course these might only show up after extensive operation with oily feedwater and/or no Smith-style "Gunk" treatment.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 29, 2002 10:22AM
<HTML>PeterH>, Peter B. and Terry,
Lots of good input and stuff I have never dealt with.
Peter H.,
I have never touched upon the Bonecourt boiler, where can i find out more about this efficient device? Anything to make a boiler of higher heat transfer efficiency and simpler construction.
Peter B.,
Sma;; tubing does buy some heat transfer advantage and weight savings but at a great cost of boiler pressure drop due to the greater tubing length and extremely high water/steam velocities. According to Jim many of the beautiful Doble water pumps were busted due to running increased boiler pressure and increased boiler output, I think the pressure drop accross the 500+ feet of "F" tubing could approach 500 psi at very high outputs---how much water pumping horsepower are you willing to expend to use this. Again, the B&W book will enable you to calculate the pressure drop for every coil or tube section, something worth checking before starting.
Terry,
Which of the Smith boilers did you have?? The earlier lightweight Doble type or his last "shopheater" looking design. There was one of the Smith "Doble" types in a car at MIT when the great MIT-CalTech clean air car race was held in 1970, all the cars were piled in the MIT parking garage. Unfortunately the Smith boiler had a huge firebox explosion that put the boiler out of commission before it could get on the Ford Motor Company dyno drive thru trailer. Road and Track had a great article on it with a very funny two page cartoon of the start showing Daves massive big Stanley and all these wierd looking contraptions all beeing outdrages by two kids in a little red wagon named Alices Day School, very funny. The boiler had some control problems, if I recall correctly, using small and thin wall tubing doesn't give must time constant for safety.
Thanks all, George</HTML>
Lots of good input and stuff I have never dealt with.
Peter H.,
I have never touched upon the Bonecourt boiler, where can i find out more about this efficient device? Anything to make a boiler of higher heat transfer efficiency and simpler construction.
Peter B.,
Sma;; tubing does buy some heat transfer advantage and weight savings but at a great cost of boiler pressure drop due to the greater tubing length and extremely high water/steam velocities. According to Jim many of the beautiful Doble water pumps were busted due to running increased boiler pressure and increased boiler output, I think the pressure drop accross the 500+ feet of "F" tubing could approach 500 psi at very high outputs---how much water pumping horsepower are you willing to expend to use this. Again, the B&W book will enable you to calculate the pressure drop for every coil or tube section, something worth checking before starting.
Terry,
Which of the Smith boilers did you have?? The earlier lightweight Doble type or his last "shopheater" looking design. There was one of the Smith "Doble" types in a car at MIT when the great MIT-CalTech clean air car race was held in 1970, all the cars were piled in the MIT parking garage. Unfortunately the Smith boiler had a huge firebox explosion that put the boiler out of commission before it could get on the Ford Motor Company dyno drive thru trailer. Road and Track had a great article on it with a very funny two page cartoon of the start showing Daves massive big Stanley and all these wierd looking contraptions all beeing outdrages by two kids in a little red wagon named Alices Day School, very funny. The boiler had some control problems, if I recall correctly, using small and thin wall tubing doesn't give must time constant for safety.
Thanks all, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 29, 2002 01:49PM
<HTML>George,
I built the early Doble type Smith boiler (about 40 SF heating surface). I could maybe submit a photo of the boiler on the test stand, if the photo section of the site is working. Or I could e-mail if you like.</HTML>
I built the early Doble type Smith boiler (about 40 SF heating surface). I could maybe submit a photo of the boiler on the test stand, if the photo section of the site is working. Or I could e-mail if you like.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 29, 2002 02:18PM
<HTML>Peter,
Actually, the steadines suprised the heck out of me, I was expecting it to be more "jumpy" than it was. As stated before, the time constant I recall was 11 seconds (I've got to find the actual data) which means that it took that long for a step input to change output to within 1/e of the final steady state. I ran steady state runs, then used step functions for both heat input and feed input. Graphed outputs. Also ran sine inputs into the boiler and measured phase shifts. You can get into the situation with control systems where they become unstable due to the phase shifts between input and output parameters.
I didn't run it in a vehicle, only on the test stand. I never ran it with any oil in the feedwater and didn't run it long enough to get corrosion informatiion. the tubing size was as Dick Smith had suggested, 3/8" for most of it, going to 1/2" for the last 40 feet or so. I used somewhat thinner wall thickness than Smith recommended in the final section, because that is what I could get easily.
I cut corners on material costs, using 304 SS in the firebox rather than 309 or 310 SS so had to keep my fire temp. down. At the end of testing I let the temp go up to where one would normally run such a boiler and destroyed the firebox in a few minutes. Have photos if you'd like to see'um.</HTML>
Actually, the steadines suprised the heck out of me, I was expecting it to be more "jumpy" than it was. As stated before, the time constant I recall was 11 seconds (I've got to find the actual data) which means that it took that long for a step input to change output to within 1/e of the final steady state. I ran steady state runs, then used step functions for both heat input and feed input. Graphed outputs. Also ran sine inputs into the boiler and measured phase shifts. You can get into the situation with control systems where they become unstable due to the phase shifts between input and output parameters.
I didn't run it in a vehicle, only on the test stand. I never ran it with any oil in the feedwater and didn't run it long enough to get corrosion informatiion. the tubing size was as Dick Smith had suggested, 3/8" for most of it, going to 1/2" for the last 40 feet or so. I used somewhat thinner wall thickness than Smith recommended in the final section, because that is what I could get easily.
I cut corners on material costs, using 304 SS in the firebox rather than 309 or 310 SS so had to keep my fire temp. down. At the end of testing I let the temp go up to where one would normally run such a boiler and destroyed the firebox in a few minutes. Have photos if you'd like to see'um.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 29, 2002 02:20PM
<HTML>Terry,
That would be great if you could e-mail me a photo, you probably have seen pictures of the boat Lamont in the papers section---a design to be very rugged and secondary was smallest size etc. . So the one you built was much like the one in that ill-fated car at the MIT-CalTech race, it looked very professional.
I think John Woodson would appreciate a copy but few on this phorum realize the great and tremendous difficulty he has had the last several weeks with a huge computer crash of both hardrives and he works all night for us to continue website functioning and try and get things back up to snuff, so his picture posting has been disabled for a few weeks. It would be nice eventually to have a good picture of it in that section.
Thanks, George</HTML>
That would be great if you could e-mail me a photo, you probably have seen pictures of the boat Lamont in the papers section---a design to be very rugged and secondary was smallest size etc. . So the one you built was much like the one in that ill-fated car at the MIT-CalTech race, it looked very professional.
I think John Woodson would appreciate a copy but few on this phorum realize the great and tremendous difficulty he has had the last several weeks with a huge computer crash of both hardrives and he works all night for us to continue website functioning and try and get things back up to snuff, so his picture posting has been disabled for a few weeks. It would be nice eventually to have a good picture of it in that section.
Thanks, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: peter heid (IP Logged)
Date: July 29, 2002 02:21PM
<HTML>Peter,</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: peter heid (IP Logged)
Date: July 29, 2002 02:52PM
<HTML>Peter,
As I tried to say before posting a blank response:
A bonecourt design could be easily run in varying stages with the individual combustion tubes being shut down and restarted as needed. The fuel and air would need to be shut off individually but each tube when running would get the perfect air fuel ratio and burn in the appropiate sized combustion chamber. A few types of materials have been tried for the material to provide the heat for catylitic combustion but plain old iron strips seemed to work the best back then. The iron heated quickly and allowed a fast changeover to catylitic combustion and easier replacement than refractory material. The ignitor material touches the tube wall in as few places as possable to prevent the conduction of heat from it. With todays modern controls, firing each tube individually would be no problem and if one failed you would still be driving.
George,
I will try to find some references for you, I forget which books it is shown in. The size seemed quite reasonable and I will try to get more specs also.
Peter Heid</HTML>
As I tried to say before posting a blank response:
A bonecourt design could be easily run in varying stages with the individual combustion tubes being shut down and restarted as needed. The fuel and air would need to be shut off individually but each tube when running would get the perfect air fuel ratio and burn in the appropiate sized combustion chamber. A few types of materials have been tried for the material to provide the heat for catylitic combustion but plain old iron strips seemed to work the best back then. The iron heated quickly and allowed a fast changeover to catylitic combustion and easier replacement than refractory material. The ignitor material touches the tube wall in as few places as possable to prevent the conduction of heat from it. With todays modern controls, firing each tube individually would be no problem and if one failed you would still be driving.
George,
I will try to find some references for you, I forget which books it is shown in. The size seemed quite reasonable and I will try to get more specs also.
Peter Heid</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: tom ward (IP Logged)
Date: July 29, 2002 09:35PM
<HTML>All the monotube designs I've seen so far are the water tube type. Is there any good reason a fire tube type monotube with forced draft would be a reasonable way to go?</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 30, 2002 09:41AM
<HTML>Hi George,
Yes, long high-output monotubes have high pumping resistance. Parallel multipath once-through design is an attempt to reduce the tube length/pumping losses with smaller diameter tubing having a fraction of the tube weight per square foot of heat-transfer area. I think(?) the flow resistance in an 8-path 112 sf boiler with 1/4"OD, 3/16"ID tubing would be equivalent to an approximately 214' monotube with 0.53" ID.
I think(?) a boiler designed to Doble parameters would put a lot more water/steam through a (much longer) 1/2" tube than I am planning. Also, as I recall, Doble tube diameter increased from one section to the next.
For comparison, the Scott-Newcomb boiler produced 500 lbs/hr at about the same pressure/temperature with a 1/2" ID monotube 367 feet long. Pumping losses must not have been excessive, as they reported average-conditions fuel mileage of 12-15 mpg in a tall, airdraggy 1920 vehicle of over 5200 lbs loaded weight.
I am trying to locate your estimate of the pressure drop in my previous 143' path (3/16" ID) concept at 5x (700lbs/hr x 5 = 3500 lbs/hr; 3500/8 paths = 437.5 lbs/hr per path) circulation. As I recall, pressure drop was way too high to be practical for Lamont circulation, but acceptable for a once-through. With only 1-2x flow rate (87.5-175 lbs/hr per path, once-through), the pressure drop would be much lower.
An equivalent Lamont would have much lower pumping losses, however. Another plus for the Lamont.
I have read that Dick Smith built a successful(?) small monotube with 1/4" tubing. I seem to recall a photo of him with the small tube stack in his lap; it looked like a loose coil of large-diameter wire. Does anybody know more about this design?
As noted, once-through multipath design is an untested & purely experimental approach which I am not recommending. It is just something I am personally considering trying, to see if/how it works. I hope that relatively tame parameters will increase the chances of success.
Peter</HTML>
Yes, long high-output monotubes have high pumping resistance. Parallel multipath once-through design is an attempt to reduce the tube length/pumping losses with smaller diameter tubing having a fraction of the tube weight per square foot of heat-transfer area. I think(?) the flow resistance in an 8-path 112 sf boiler with 1/4"OD, 3/16"ID tubing would be equivalent to an approximately 214' monotube with 0.53" ID.
I think(?) a boiler designed to Doble parameters would put a lot more water/steam through a (much longer) 1/2" tube than I am planning. Also, as I recall, Doble tube diameter increased from one section to the next.
For comparison, the Scott-Newcomb boiler produced 500 lbs/hr at about the same pressure/temperature with a 1/2" ID monotube 367 feet long. Pumping losses must not have been excessive, as they reported average-conditions fuel mileage of 12-15 mpg in a tall, airdraggy 1920 vehicle of over 5200 lbs loaded weight.
I am trying to locate your estimate of the pressure drop in my previous 143' path (3/16" ID) concept at 5x (700lbs/hr x 5 = 3500 lbs/hr; 3500/8 paths = 437.5 lbs/hr per path) circulation. As I recall, pressure drop was way too high to be practical for Lamont circulation, but acceptable for a once-through. With only 1-2x flow rate (87.5-175 lbs/hr per path, once-through), the pressure drop would be much lower.
An equivalent Lamont would have much lower pumping losses, however. Another plus for the Lamont.
I have read that Dick Smith built a successful(?) small monotube with 1/4" tubing. I seem to recall a photo of him with the small tube stack in his lap; it looked like a loose coil of large-diameter wire. Does anybody know more about this design?
As noted, once-through multipath design is an untested & purely experimental approach which I am not recommending. It is just something I am personally considering trying, to see if/how it works. I hope that relatively tame parameters will increase the chances of success.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 30, 2002 10:15AM
<HTML>Peter,
The boiler in William Brobecks very successful California (DOT supported) bus was a two parallel pass and believe Besler also made a few two parallel pass boilers. Big Lamonts, to cut down circulating pressure, would use many paths with flow restrictors in them to equalize each different path to have the same relative 5/1 flow ratio per pound of steam evaporated per path. A standard watertube boiler is a huge bunch of parallel paths but as each tube is relatively very short adequate circulation is available. Look at Chapter 8 in the B&W book and look at the flow equations, the need to know the absolute viscosity and changing conditions going on in the tube---this means you need to know the amount of heat transfer along the length of each tube---it can be done. Don't forget to include all the flow losses due to bends and find the longer equivalent tube length. If a multi-path "monotube looking" boiler had all identical paths with each one receiving the same heat input then the problem of a section not getting water would be minimized(but not totally eliminated). A multiple piston feedwater pump could have a piston feeding each parallel circuit and as long as the pump behaved properly each coil would have equal water, or a thermocouple on the end of each coil could be used to signal more water into a tube that was getting hotter. Lots of stuff to play around with!
The 60 foot 7/8ths ID Lamont coil in Rod's boiler has about a 5psi pressure drop with about 3000# of water per hour circulated, circulating pump requires 6 amperes@ 12 volts.
Thanks for the detailed info on the Scott-Newcomb, will run some numbers on it with some assumptions to get a rough idea of its pressure drop at 500#/hr steam rate.
If making a "monotube" looking boiler would certainly consider the multiple path approach as smaller tubing of lesser weight with higher gas pass heat transfer would make a smaller package.
Best, George</HTML>
The boiler in William Brobecks very successful California (DOT supported) bus was a two parallel pass and believe Besler also made a few two parallel pass boilers. Big Lamonts, to cut down circulating pressure, would use many paths with flow restrictors in them to equalize each different path to have the same relative 5/1 flow ratio per pound of steam evaporated per path. A standard watertube boiler is a huge bunch of parallel paths but as each tube is relatively very short adequate circulation is available. Look at Chapter 8 in the B&W book and look at the flow equations, the need to know the absolute viscosity and changing conditions going on in the tube---this means you need to know the amount of heat transfer along the length of each tube---it can be done. Don't forget to include all the flow losses due to bends and find the longer equivalent tube length. If a multi-path "monotube looking" boiler had all identical paths with each one receiving the same heat input then the problem of a section not getting water would be minimized(but not totally eliminated). A multiple piston feedwater pump could have a piston feeding each parallel circuit and as long as the pump behaved properly each coil would have equal water, or a thermocouple on the end of each coil could be used to signal more water into a tube that was getting hotter. Lots of stuff to play around with!
The 60 foot 7/8ths ID Lamont coil in Rod's boiler has about a 5psi pressure drop with about 3000# of water per hour circulated, circulating pump requires 6 amperes@ 12 volts.
Thanks for the detailed info on the Scott-Newcomb, will run some numbers on it with some assumptions to get a rough idea of its pressure drop at 500#/hr steam rate.
If making a "monotube" looking boiler would certainly consider the multiple path approach as smaller tubing of lesser weight with higher gas pass heat transfer would make a smaller package.
Best, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 30, 2002 10:19AM
<HTML>Hi Terry,
Thanks for the info on your experience with the Dick Smith boiler design. The control tuning sounds similar to procedures I am planning for my control system. I think/hope that the controls I have designed will avoid unstable oscillation. I do plan tests to find out the time constant with whatever I end up building, and program controls accordingly. In my system, that would mainly be handled by the fire-control anticipating routine/subsystem. The planned water control is non-thermostatic to avoid thermal lag and has a unique design. Oops, need to keep quiet about that. :)
Pix would be great! Until John's gallery is up & running again, I could drop a few pix temporarily on one of my web pages for folks to look at, if that is OK. Limited space, but I can publish it quick. Do you know anything about the smaller Dick Smith boiler design I mentioned in my last post to George?
Peter</HTML>
Thanks for the info on your experience with the Dick Smith boiler design. The control tuning sounds similar to procedures I am planning for my control system. I think/hope that the controls I have designed will avoid unstable oscillation. I do plan tests to find out the time constant with whatever I end up building, and program controls accordingly. In my system, that would mainly be handled by the fire-control anticipating routine/subsystem. The planned water control is non-thermostatic to avoid thermal lag and has a unique design. Oops, need to keep quiet about that. :)
Pix would be great! Until John's gallery is up & running again, I could drop a few pix temporarily on one of my web pages for folks to look at, if that is OK. Limited space, but I can publish it quick. Do you know anything about the smaller Dick Smith boiler design I mentioned in my last post to George?
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 30, 2002 10:56AM
<HTML>Hi George,
Thanks for the tips; always much appreciated. I have sketched multi-piston pumps, but whew. There are some fabrication advantages, though. As is, the paths are all identical, with curious radial symmetry, and steam/water flow resistance should be identical. Flameholder burner was selected to give even radiant heat & gas distribution. One possible bug, besides scale & tube dents, is uneven gas flow due to exhaust flue location; may have to go with annular flue & deal with larger boiler diameter. Don't want to duplicate the Doble-Detroit "fun" ("thermal shorts" per Jerry Peoples).
Wish I knew the coil diameters in Scott-Newcomb; maybe I'll break out the dividers and do some scaling of picture, pref with a xerox enlargement. Probably around 20-22" dia.. Coils are so similar in diameter that it should be easy to estimate equivalent length. Might be in that Wetz article.
Multipath Lamont speculations: 22 circuits of that 1/4" tubing would give same internal flowpath area as Rod's 7/8" ID. Each 60' long, about the same pump hp. Weight maybe 1/3 to 1/4 that of bigger tubing. Easier to bend, more compact, and cheaper/sqft too. 8 is fine for economizer. Extra radiant heating = smaller/lighter than my design, even with drum? Nested helix barrel coils? Size drum as needed for stored energy; doesn't have to be minimized. Tube ends expanded into flanged/bolted drum heads? Or tie rods -- good for 2000 psi+ hydraulic cylinders? Pump impeller inside bottom of drum with multiple outputs around it & blowable scale trap above? Hmm...
Great thread!
Peter</HTML>
Thanks for the tips; always much appreciated. I have sketched multi-piston pumps, but whew. There are some fabrication advantages, though. As is, the paths are all identical, with curious radial symmetry, and steam/water flow resistance should be identical. Flameholder burner was selected to give even radiant heat & gas distribution. One possible bug, besides scale & tube dents, is uneven gas flow due to exhaust flue location; may have to go with annular flue & deal with larger boiler diameter. Don't want to duplicate the Doble-Detroit "fun" ("thermal shorts" per Jerry Peoples).
Wish I knew the coil diameters in Scott-Newcomb; maybe I'll break out the dividers and do some scaling of picture, pref with a xerox enlargement. Probably around 20-22" dia.. Coils are so similar in diameter that it should be easy to estimate equivalent length. Might be in that Wetz article.
Multipath Lamont speculations: 22 circuits of that 1/4" tubing would give same internal flowpath area as Rod's 7/8" ID. Each 60' long, about the same pump hp. Weight maybe 1/3 to 1/4 that of bigger tubing. Easier to bend, more compact, and cheaper/sqft too. 8 is fine for economizer. Extra radiant heating = smaller/lighter than my design, even with drum? Nested helix barrel coils? Size drum as needed for stored energy; doesn't have to be minimized. Tube ends expanded into flanged/bolted drum heads? Or tie rods -- good for 2000 psi+ hydraulic cylinders? Pump impeller inside bottom of drum with multiple outputs around it & blowable scale trap above? Hmm...
Great thread!
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 30, 2002 12:26PM
<HTML>Peter Brow said:
"I have read that Dick Smith built a successful(?) small monotube with 1/4" tubing. I seem to recall a photo of him with the small tube stack in his lap; it looked like a loose coil of large-diameter wire. Does anybody know more about this design?"
It sounds llike Richard Smith's version of the model steam airplane boiler designed and built by H. H. Grove, I believe, around 1912. This is described in the Book "Experimental Flash Steam" By Benson and Rayman.</HTML>
"I have read that Dick Smith built a successful(?) small monotube with 1/4" tubing. I seem to recall a photo of him with the small tube stack in his lap; it looked like a loose coil of large-diameter wire. Does anybody know more about this design?"
It sounds llike Richard Smith's version of the model steam airplane boiler designed and built by H. H. Grove, I believe, around 1912. This is described in the Book "Experimental Flash Steam" By Benson and Rayman.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 30, 2002 12:31PM
<HTML>George,
I couldn't find photos of the boiler in my computer so rounded up the original photos and scanned them. Tried to send them to you but I don't have a good e-mail address for you, the daemon mailer kicked them back. If you could get me your address, I'll get thim off to you. tw</HTML>
I couldn't find photos of the boiler in my computer so rounded up the original photos and scanned them. Tried to send them to you but I don't have a good e-mail address for you, the daemon mailer kicked them back. If you could get me your address, I'll get thim off to you. tw</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Jim Crank (IP Logged)
Date: July 30, 2002 02:06PM
<HTML>Peter, George, Terry,
Multipath is certainly a well proven design. Besler did a few, the Yuba tractor had a five path in the wet zone with each pump cylinder feeding only one circuit. Lear, my race car boiler, had 18 finned tubes in parallel in the economizer zone, square layout with headers, down to one in the superheater. No problems at all. They wanted variable velocity as it went from water to steam.
Broebeck use several in the economizer.
Doble used 5/8 in the economizer, then to 3/4 and on to 1-1/4 for the superheater. If you want more water capacity, then start with 3/4.
The Smith boiler using 1/4" tubing was for a bicycle engine. The car one I had went from 1/4 pipe to 1/2 pipe, concentric design.
Saab used dozens in parallel for their car generator design; but almost hypodermic tubing, fatal with any crud in one circuit.
Multipath and finned in the economizer and wet steam zones, two for the Lamont coil, then into the Lamont drum and one for the superheater. It has to be optimized for the flow rate and output of the specific use.
Jim</HTML>
Multipath is certainly a well proven design. Besler did a few, the Yuba tractor had a five path in the wet zone with each pump cylinder feeding only one circuit. Lear, my race car boiler, had 18 finned tubes in parallel in the economizer zone, square layout with headers, down to one in the superheater. No problems at all. They wanted variable velocity as it went from water to steam.
Broebeck use several in the economizer.
Doble used 5/8 in the economizer, then to 3/4 and on to 1-1/4 for the superheater. If you want more water capacity, then start with 3/4.
The Smith boiler using 1/4" tubing was for a bicycle engine. The car one I had went from 1/4 pipe to 1/2 pipe, concentric design.
Saab used dozens in parallel for their car generator design; but almost hypodermic tubing, fatal with any crud in one circuit.
Multipath and finned in the economizer and wet steam zones, two for the Lamont coil, then into the Lamont drum and one for the superheater. It has to be optimized for the flow rate and output of the specific use.
Jim</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 30, 2002 02:10PM
<HTML>Terry,
Thanks for the pictures, they came thru the second time. Beautiful job. Also thanks for your e-mail address, sent you an e-mail this AM with my e-mail address but it appears you already have it!!
Best, George</HTML>
Thanks for the pictures, they came thru the second time. Beautiful job. Also thanks for your e-mail address, sent you an e-mail this AM with my e-mail address but it appears you already have it!!
Best, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: peter heid (IP Logged)
Date: July 30, 2002 06:47PM
<HTML>In the thin little Brittish spy book from around WW2 about the state of the development of steam transportation in Germany, there is a brief discussion of a multi-path steam generator using a pump for each circulation leg. I forget the name of the "Kirk Michael" book and the manufacturer but it can be looked up easily. Sounds a bit complex to me, I like the single or dual pump with flow restrictors to provide the correct circulation for each leg. Dual pumps were often used with one being electric and the other steam powered. If the electric failed with no steam pressure the boiler was shut down for pump repairs and if no troubles occured, pressure allowed the switch over to the steam powered pump. If that were to fail under pressure, the electric could be switched back on. Quite often though, Lamont installations included only one pump and failures, quite rare.
Can't believe we have kept a continous boiler only thread for this long.
Peter Heid</HTML>
Can't believe we have kept a continous boiler only thread for this long.
Peter Heid</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 30, 2002 07:04PM
<HTML>Peter,
Concerning flow restrictors. I like flow dividers better, that way if you get incresed backpressure in a path due to more boiling, you don't get decreased flow in that leg.</HTML>
Concerning flow restrictors. I like flow dividers better, that way if you get incresed backpressure in a path due to more boiling, you don't get decreased flow in that leg.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Pat Farrell (IP Logged)
Date: July 31, 2002 12:37AM
<HTML>Dear Terry, Could you please describe a flow divider and how it differs from a flow restrictor? SSsssteamer</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Terry Williams (IP Logged)
Date: July 31, 2002 12:58AM
<HTML>I think there are several ways to make a flow divider, but the one I designed for a project was like 2 gear pumps with the shafts connected so they both turn together. Put the input fluid into both and direct each output to a different path. This can be all made in a single casing and can be made with more than 2 outlets. If the rotors are the same length, the flows in each path will be the same. Could be made to direct more to one of the paths too. Those more familiar with hydraulics can probably come up with more ways to do this.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: July 31, 2002 05:43AM
<HTML>Correction. I wrote:
"As noted, once-through multipath design is an untested & purely experimental approach which I am not recommending. It is just something I am personally considering trying, to see if/how it works."
Should read: "... MY once-through multipath design ..."
Typo.
Thanks, George, Jim, and all for the notes on previous successful multipath once-thru boilers. Their success, and the possibilities with this design approach, are what keep me working in this direction.
Jim: good ideas for the multipath Lamont.
Peter</HTML>
"As noted, once-through multipath design is an untested & purely experimental approach which I am not recommending. It is just something I am personally considering trying, to see if/how it works."
Should read: "... MY once-through multipath design ..."
Typo.
Thanks, George, Jim, and all for the notes on previous successful multipath once-thru boilers. Their success, and the possibilities with this design approach, are what keep me working in this direction.
Jim: good ideas for the multipath Lamont.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: peter heid (IP Logged)
Date: July 31, 2002 12:59PM
<HTML>The flow restrictors I have seen on lamont installations also act to filter the water so no larger particles can travel through the coils and possably lodge there. They are also designed so the particles will fall from the restrictor and each restrictor is sized for the fluid friction that must be overcome to provide the correct flow rate for the optimum performance of that circuit. More complex with a flow divider.
Peter Heid</HTML>
Peter Heid</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: July 31, 2002 02:23PM
<HTML> Remember in a Lamont you do not want necessarilly equal flow in each parallel circuit, you want 5-6 times the evaporation rate of each tube to protect it, Lamont had many boilers that had vastly different path lengths and or heat transfer input.. The same thing would apply to a "multimonotube", the amount of water for each tube is dependent upon its evaporation rate---pretty hard to do when your circulation ratio is zero to 2 or 3 with an on/off pump. Restrictors or any impedance in the Lamont coil(s) create a larger circulating pump pressure and horsepower and should be avoided if possible. Also remember that in the purely radiant section the amount of head absorbed has nothing to do with tube diameter so small tubing has no benefit over larger tubing in BTU's/Sq. Ft/hour.
Off topic I talked to our great Coburn Benson/Ben who has not posted in a long time and was concerned that things were alright with him, really miss his Maine humor and spelling witicisms(make words as short as possible and stuff) plus his depth of knowledge. He is fine, said to tell you all that as soon as he can get his computer past the DOS black and white page will be back, he hasn't had it running in over a month. So Hi" from Ben!!</HTML>
Off topic I talked to our great Coburn Benson/Ben who has not posted in a long time and was concerned that things were alright with him, really miss his Maine humor and spelling witicisms(make words as short as possible and stuff) plus his depth of knowledge. He is fine, said to tell you all that as soon as he can get his computer past the DOS black and white page will be back, he hasn't had it running in over a month. So Hi" from Ben!!</HTML>
More Bonecourt
Posted by: Peter Heid (IP Logged)
Date: August 04, 2002 10:43PM
<HTML>George et al,
I have found only 3 references to the Bonecourt boiler in the books I have collected. The first 2 only barely skim the surface. The books indicate the design is the work of two individuals and the name is a compound word derived from the inventors names. First being introduced around 1909 and fired on gas. The manufacture of Bonecourt boilers continued until at least 1948 by Messrs. Town Gas Boilers (Bonecourt) Ltd. of London. Bonecourt boilers are compact in size and can be fired in the vertical or horizontal positions. If sufficient draft is not available from stack height, a exhaust fan is included. Each boiler tube contains a spiraled iron core which acts as the refractory and causes a spiral flow of the combustion gasses and intensifying the heat scrubbing action. It is said that the iron cores do not break down like refractory packings used in earlier versions. Each tube has its own gas feed and pilot light with a snap action regulator to provide full or no gas flow for proper combustion. The gas regulator for the burners had a patented "pressurestat control" that maintained the steam pressure to within +/-1.5 PSI and to meet the demand for a steady output steam generator, special modified burner was supplied.
The Steam Boiler Yearbook and Manual IV, Paul Elek Publishers Ltd, London, 1948, had this to say about the Bonecourt:
"The simplicity of design and operation renders both the vertical and horizontal types of Bonecourt boilers and heaters eminently suitable for all purposes where steam at a constant pressure and water at an even temperature is required, especially as the makers state that no supervision is wanted and no labor entailed other than lighting-up or extinguishing, and maintainance is reduced to a minimum." also "... fired by means of a seperate jet into each boiler tube. This provides a large heating surface, giving a high evaporative capacity and quick steaming from cold, for boilers which are very compact in size."
It would seem a horizontal version of the bonecourt could be assembled in modular fashion using the circulation and drum design of a Lamont, and make steam power an easier proposition for designs of limited vertical space.
Peter Heid</HTML>
I have found only 3 references to the Bonecourt boiler in the books I have collected. The first 2 only barely skim the surface. The books indicate the design is the work of two individuals and the name is a compound word derived from the inventors names. First being introduced around 1909 and fired on gas. The manufacture of Bonecourt boilers continued until at least 1948 by Messrs. Town Gas Boilers (Bonecourt) Ltd. of London. Bonecourt boilers are compact in size and can be fired in the vertical or horizontal positions. If sufficient draft is not available from stack height, a exhaust fan is included. Each boiler tube contains a spiraled iron core which acts as the refractory and causes a spiral flow of the combustion gasses and intensifying the heat scrubbing action. It is said that the iron cores do not break down like refractory packings used in earlier versions. Each tube has its own gas feed and pilot light with a snap action regulator to provide full or no gas flow for proper combustion. The gas regulator for the burners had a patented "pressurestat control" that maintained the steam pressure to within +/-1.5 PSI and to meet the demand for a steady output steam generator, special modified burner was supplied.
The Steam Boiler Yearbook and Manual IV, Paul Elek Publishers Ltd, London, 1948, had this to say about the Bonecourt:
"The simplicity of design and operation renders both the vertical and horizontal types of Bonecourt boilers and heaters eminently suitable for all purposes where steam at a constant pressure and water at an even temperature is required, especially as the makers state that no supervision is wanted and no labor entailed other than lighting-up or extinguishing, and maintainance is reduced to a minimum." also "... fired by means of a seperate jet into each boiler tube. This provides a large heating surface, giving a high evaporative capacity and quick steaming from cold, for boilers which are very compact in size."
It would seem a horizontal version of the bonecourt could be assembled in modular fashion using the circulation and drum design of a Lamont, and make steam power an easier proposition for designs of limited vertical space.
Peter Heid</HTML>
Re: More Bonecourt
Posted by: Peter Brow (IP Logged)
Date: August 05, 2002 04:34AM
<HTML>Hi Peter,
Any info on square footage, temp/pressure, steaming rates, or what the catalytic elements were made of, in Bonecourt boilers?
Perhaps a search of UK or US patent records would turn up more info.
Peter</HTML>
Any info on square footage, temp/pressure, steaming rates, or what the catalytic elements were made of, in Bonecourt boilers?
Perhaps a search of UK or US patent records would turn up more info.
Peter</HTML>
Re: More Bonecourt
Posted by: George Nutz (IP Logged)
Date: August 05, 2002 04:11PM
<HTML>Peter H.,
Thanks for the info on the Bonecourt boilers. I was wondering how they could get a "fire tube" boiler to have high heat transfer rates as generally the heat transfer in a longflow firetube is only about 1/5th the rate of crossflow with the same gas mass flow per hour. I wonder how they make the inside spiral in the tubes??? That would greatly increase the heat transfer on the gas side. How ingenious people were the last 100 years---the glory days of mechanical engineering!!
Best and thanks, George</HTML>
Thanks for the info on the Bonecourt boilers. I was wondering how they could get a "fire tube" boiler to have high heat transfer rates as generally the heat transfer in a longflow firetube is only about 1/5th the rate of crossflow with the same gas mass flow per hour. I wonder how they make the inside spiral in the tubes??? That would greatly increase the heat transfer on the gas side. How ingenious people were the last 100 years---the glory days of mechanical engineering!!
Best and thanks, George</HTML>
Re: More Bonecourt
Posted by: Peter Heid (IP Logged)
Date: August 05, 2002 04:45PM
<HTML>George / Peter
The inner spiral of soft iron is the catalytic refractory material and it is just a strip of iron twisted and inserted into the pipe. The original design used broken chunks of refractory material for the catalyst but these broke down with use and made crumbled dust in the exhaust. I will sift through for more technical specs, patent numbers, diagrams ect. The boiler was first designed as a fire tube which means it was a low pressure boiler and many were used for heating buildings. I keep picturing a tube in a tube, fire in the inner and water between with circulation provided in Lamont fashion but I dream a lot.
The original: Other Peter</HTML>
The inner spiral of soft iron is the catalytic refractory material and it is just a strip of iron twisted and inserted into the pipe. The original design used broken chunks of refractory material for the catalyst but these broke down with use and made crumbled dust in the exhaust. I will sift through for more technical specs, patent numbers, diagrams ect. The boiler was first designed as a fire tube which means it was a low pressure boiler and many were used for heating buildings. I keep picturing a tube in a tube, fire in the inner and water between with circulation provided in Lamont fashion but I dream a lot.
The original: Other Peter</HTML>
Re: More Bonecourt
Posted by: Peter Brow (IP Logged)
Date: August 06, 2002 05:45AM
<HTML>Hi Peter,
The iron itself was the catalyst? Interesting. I know that steel wool will burn with forced air, but that has some carbon content and is also not cooled by a surrounding heat exchanger. Still, I wonder how long the soft iron element would last, and if the fuel/air ratio has to be spot-on, with no excess air. Concentric tubes with circulated water does sound like the best way to go with this. Should be possible to design for a little less efficiency, so that acids don't condense out of the exhaust. Small experimental rigs shouldn't be too hard to fabricate ... find out how much steam one tube unit will make, then gang together enough to run a car, boat, etc ...
Wonder if ordinary wrought iron strap stock would do the trick?
George: The Bonecourt is definitely ingenious! I think we can learn a lot from the designers of the past, then improve on their designs with modern tools, materials & knowledge.
Peter</HTML>
The iron itself was the catalyst? Interesting. I know that steel wool will burn with forced air, but that has some carbon content and is also not cooled by a surrounding heat exchanger. Still, I wonder how long the soft iron element would last, and if the fuel/air ratio has to be spot-on, with no excess air. Concentric tubes with circulated water does sound like the best way to go with this. Should be possible to design for a little less efficiency, so that acids don't condense out of the exhaust. Small experimental rigs shouldn't be too hard to fabricate ... find out how much steam one tube unit will make, then gang together enough to run a car, boat, etc ...
Wonder if ordinary wrought iron strap stock would do the trick?
George: The Bonecourt is definitely ingenious! I think we can learn a lot from the designers of the past, then improve on their designs with modern tools, materials & knowledge.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Mike Bennett (IP Logged)
Date: August 06, 2002 10:25PM
<HTML>Any idea how much pounds per hour / square feet tubing surface, that a well designed lamont should produce. (forced draft)?
GREAT STUFF
thanks,
MB</HTML>
GREAT STUFF
thanks,
MB</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: August 07, 2002 10:13AM
<HTML>Mike,
15 to 20#/hr-sqft is rather easy even if designed for full load purposes as in steamboat use. Much higher rates have been accomplished and obtainable, 40 is not out of the question with complete safety.
Depends on how much power you will put into the circulating pump and how big a firebox volume is allowable. As an example of the importance of firebox volume with radiant heat transfer, if one had a one cubic foot forebox and fired 600K BTU per cubic foot there would be 6 sq.ft. of firebox(Lamont) wall exposed and the heat generated per sq.ft. is 100K BTU's/ sq.ft. Large industrial boilers can have one million BTU's/sq.ft. available. In the case of the described boat Lamont about 40-45K per sq.ft. is absorbed or 40-45% of total heat available. if one had a two foot cube there would be 600K X 8 cubic feet or 4.8 million BTU's released in the firebox and 24 sq.ft. of surface for radiant absorption purposes= 200K BTU available per sq. ft. The radiant part is very useful as it requires no draft pressure loss. Of course several rows of convective coils could be added for more Lamont coil heat absorption.
Hope this helps, George</HTML>
15 to 20#/hr-sqft is rather easy even if designed for full load purposes as in steamboat use. Much higher rates have been accomplished and obtainable, 40 is not out of the question with complete safety.
Depends on how much power you will put into the circulating pump and how big a firebox volume is allowable. As an example of the importance of firebox volume with radiant heat transfer, if one had a one cubic foot forebox and fired 600K BTU per cubic foot there would be 6 sq.ft. of firebox(Lamont) wall exposed and the heat generated per sq.ft. is 100K BTU's/ sq.ft. Large industrial boilers can have one million BTU's/sq.ft. available. In the case of the described boat Lamont about 40-45K per sq.ft. is absorbed or 40-45% of total heat available. if one had a two foot cube there would be 600K X 8 cubic feet or 4.8 million BTU's released in the firebox and 24 sq.ft. of surface for radiant absorption purposes= 200K BTU available per sq. ft. The radiant part is very useful as it requires no draft pressure loss. Of course several rows of convective coils could be added for more Lamont coil heat absorption.
Hope this helps, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Mike Bennett (IP Logged)
Date: August 07, 2002 08:46PM
<HTML>George, et al,
Could ebullient powered coils be made to work on a lamont (besides the 5X pumped circuit)? Has anyone tried ultrasonic etc. to liberate the steam bubbles from the tubes?
Thanks,
I've learned a lot here!
Mike</HTML>
Could ebullient powered coils be made to work on a lamont (besides the 5X pumped circuit)? Has anyone tried ultrasonic etc. to liberate the steam bubbles from the tubes?
Thanks,
I've learned a lot here!
Mike</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 07, 2002 09:30PM
<HTML>Hi George,
I second Mike B's thanks for the radiant heat figures, and for the ongoing boiler design tutorial. I am back to working on a Lamont design. A few more flip-flops on boiler type, and I'll never get it built. However, the deeper I get into the B&W Book calculations, the better the Lamont looks. This wouldn't be the first time I worked out several different designs in detail before deciding what to build.
Jim's "subject to instant change" approach to powerplant concepts is the best way to go, considering all the design options available in every part of a light steam powerplant, and all the previously unknown things which pop up.
Peter</HTML>
I second Mike B's thanks for the radiant heat figures, and for the ongoing boiler design tutorial. I am back to working on a Lamont design. A few more flip-flops on boiler type, and I'll never get it built. However, the deeper I get into the B&W Book calculations, the better the Lamont looks. This wouldn't be the first time I worked out several different designs in detail before deciding what to build.
Jim's "subject to instant change" approach to powerplant concepts is the best way to go, considering all the design options available in every part of a light steam powerplant, and all the previously unknown things which pop up.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Mike Bennett (IP Logged)
Date: August 08, 2002 06:20PM
<HTML>Has anyone tried a binary boiler in an auto? I was thinking liquid metal / water.
Thanks,
Mike</HTML>
Thanks,
Mike</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: August 08, 2002 10:11PM
<HTML>Peter and Mike,
Peter-as you and I have the same edition of the B&W book and you are studying it carefully look at the chapter on the smaller and higher performance marine boilers in chapter 29 and the graphs on page 29-14. These can be interpolated from their much larger size(although much smaller than stationary plants) to much smaller boilers like we are interested in. You may want to study chapter 11 with careful thought on partial pressures of the gases of combustion that are very powerful radiation gases---even if the gas is invisible to the naked eye, look at 11-24 and 11-28. Other books will get you into calculating beam lengths and stuff, it s all rather complicated but is very necessary to get the right amount of heat transfer to your tubing design in the very hot boiler sections. In the Lamont the goal is to get the short Lamont recirculating section to do 90-100% of all the evaporation. Also remember even if the forced circulation is 5X steam output by weight the mixture leaving is over 90% steam by volume depending upon pressure and the delta enthalpy of the water/steam. Lamont works much better at higher pressures!!
Mike, the binary boilers were popular in the 1950's, my father was a boilermaker and he lost many friends who died of mercury poisoning--their hair and teeth fell out and they died. At the time the dangers were not well understood. In the 70's Dr.? received grants in persueing binary freon-water boilers. Guess that was before understanding the effects of freon in the ozone layer. We leak enough freon form air conditioners without going to leaking from boilers---how much we have all learned. Binary approach is very complicated for a variable load boiler and would probably be heavier, why complicate the boiler so much?? Instead of trying to get 10% more boiler efficiency(at that time the metal tube temperatures were most limiting factor) it may be better to get 10% more efficiency out of the engine. Just rambling thoughts, thought I would post to get this topic up to 49 posts(bg) ;0) . This weekend our local steam club is having a tour and 1/8th mile time trials on a runway. It is absolutely astonishing to watch a 1902 Stanley leap from zero to 30mph in maybe 30-50 feet and average 30 going up hill, imagine the astonisment in 1902!! Many of the cars there are in John Woodson's picture section. Always stirs the blood and interest to see these old cars perform. Guess who is doing the time trials?
Best, George</HTML>
Peter-as you and I have the same edition of the B&W book and you are studying it carefully look at the chapter on the smaller and higher performance marine boilers in chapter 29 and the graphs on page 29-14. These can be interpolated from their much larger size(although much smaller than stationary plants) to much smaller boilers like we are interested in. You may want to study chapter 11 with careful thought on partial pressures of the gases of combustion that are very powerful radiation gases---even if the gas is invisible to the naked eye, look at 11-24 and 11-28. Other books will get you into calculating beam lengths and stuff, it s all rather complicated but is very necessary to get the right amount of heat transfer to your tubing design in the very hot boiler sections. In the Lamont the goal is to get the short Lamont recirculating section to do 90-100% of all the evaporation. Also remember even if the forced circulation is 5X steam output by weight the mixture leaving is over 90% steam by volume depending upon pressure and the delta enthalpy of the water/steam. Lamont works much better at higher pressures!!
Mike, the binary boilers were popular in the 1950's, my father was a boilermaker and he lost many friends who died of mercury poisoning--their hair and teeth fell out and they died. At the time the dangers were not well understood. In the 70's Dr.? received grants in persueing binary freon-water boilers. Guess that was before understanding the effects of freon in the ozone layer. We leak enough freon form air conditioners without going to leaking from boilers---how much we have all learned. Binary approach is very complicated for a variable load boiler and would probably be heavier, why complicate the boiler so much?? Instead of trying to get 10% more boiler efficiency(at that time the metal tube temperatures were most limiting factor) it may be better to get 10% more efficiency out of the engine. Just rambling thoughts, thought I would post to get this topic up to 49 posts(bg) ;0) . This weekend our local steam club is having a tour and 1/8th mile time trials on a runway. It is absolutely astonishing to watch a 1902 Stanley leap from zero to 30mph in maybe 30-50 feet and average 30 going up hill, imagine the astonisment in 1902!! Many of the cars there are in John Woodson's picture section. Always stirs the blood and interest to see these old cars perform. Guess who is doing the time trials?
Best, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Mike Bennett (IP Logged)
Date: August 09, 2002 04:26PM
<HTML>THANKS. What is the complete title, date, edition. etc for this B & W book? I would like to find one!
Great stuff!
Mike</HTML>
Great stuff!
Mike</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 10, 2002 07:41AM
<HTML>Hi George,
Thanks. I am considering a naughty little trick for making sure that 100% of the evaporation would take place in the circulated section, no matter what. The trick is, circulate the whole tube stack. Flowpath length in current multipath concept would be about 34 feet & equivalent to ~1" ID single flowpath, so I think I could circulate everything with reasonable pump hp.. What I don't know yet is how this would impact efficiency. Feedwater would be mixed into the recirc water at pump inlet, and then the mix (cooler than saturated) would downflow thru tubes from top to the tall tube-lined firebox at the bottom (up firing).
Not able to do the full heat-transfer calcs yet (still in estimate/cut&try mode), but I figure that this would do better than a Stanley, in which the gas exit end of the heat exchanger is at (or even slightly above) saturated temperature. In my current concept, gas-exit end of tubestack would be at lower than saturated temp, IE, scrubbing the gases down to a lower outlet temp, IE, better efficiency.
The small-dia, all-crossflow, all-circulated tubing should give several times the heat transfer per sq ft of a Stanley, but the lower gas pressure in firebox and lower gas speed thru tube stack means less per sf than a similar Lamont with a fan burner, esp if other Lamont also ran at higher steam pressure. So I think this could be acceptably efficient, but the question is at what firing/steaming rate. Might only run economically at outputs lower than design goal. But should be enough to run a car nicely. And, an uncirculated economizer can always be added later.
You're right, it all gets very complicated -- even in pre-math estimates. Every statement above has several unstated "then agains", and probably plenty of others I haven't discovered yet.
I am now looking at circulating pump. Considering an off-the-shelf 12vdc auto radiator fan motor; available cheap & everywhere in 13 amp ratings and designed to run 2000 hrs/100,000 miles in harsh hi-temp underhood environment (right behind the radiator). Also considering homebuilt Roots-type positive displacement pump with straight 2-lobe rotors & small stuffing box seal. More mechanical friction, but (leaky) positive displacement design gives better volumetric efficiency than a typical (esp homebuilt) centrifugal or Tesla pump. Also easier to design & more compact, though harder to build. Cavitation ahoy? Also have next-generation ideas for cheap steam drive for pump, with air starter for brief cold-fireup. The pump really ought to have its own thread.
Thanks again for the "food for thought"; seems to be working! :)
Peter</HTML>
Thanks. I am considering a naughty little trick for making sure that 100% of the evaporation would take place in the circulated section, no matter what. The trick is, circulate the whole tube stack. Flowpath length in current multipath concept would be about 34 feet & equivalent to ~1" ID single flowpath, so I think I could circulate everything with reasonable pump hp.. What I don't know yet is how this would impact efficiency. Feedwater would be mixed into the recirc water at pump inlet, and then the mix (cooler than saturated) would downflow thru tubes from top to the tall tube-lined firebox at the bottom (up firing).
Not able to do the full heat-transfer calcs yet (still in estimate/cut&try mode), but I figure that this would do better than a Stanley, in which the gas exit end of the heat exchanger is at (or even slightly above) saturated temperature. In my current concept, gas-exit end of tubestack would be at lower than saturated temp, IE, scrubbing the gases down to a lower outlet temp, IE, better efficiency.
The small-dia, all-crossflow, all-circulated tubing should give several times the heat transfer per sq ft of a Stanley, but the lower gas pressure in firebox and lower gas speed thru tube stack means less per sf than a similar Lamont with a fan burner, esp if other Lamont also ran at higher steam pressure. So I think this could be acceptably efficient, but the question is at what firing/steaming rate. Might only run economically at outputs lower than design goal. But should be enough to run a car nicely. And, an uncirculated economizer can always be added later.
You're right, it all gets very complicated -- even in pre-math estimates. Every statement above has several unstated "then agains", and probably plenty of others I haven't discovered yet.
I am now looking at circulating pump. Considering an off-the-shelf 12vdc auto radiator fan motor; available cheap & everywhere in 13 amp ratings and designed to run 2000 hrs/100,000 miles in harsh hi-temp underhood environment (right behind the radiator). Also considering homebuilt Roots-type positive displacement pump with straight 2-lobe rotors & small stuffing box seal. More mechanical friction, but (leaky) positive displacement design gives better volumetric efficiency than a typical (esp homebuilt) centrifugal or Tesla pump. Also easier to design & more compact, though harder to build. Cavitation ahoy? Also have next-generation ideas for cheap steam drive for pump, with air starter for brief cold-fireup. The pump really ought to have its own thread.
Thanks again for the "food for thought"; seems to be working! :)
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: August 21, 2002 09:14PM
<HTML>Peter,
One of the problems of circulating the whole "tube stack" is that we no longer end up with a counterflow boiler where the inlet feedwater is at its lowest temperature to absorb heat form the lower temperature gases---this is where the Doble counterflow approach has great success plus it removes some of the tubing from being a burden on the circulating pump. Even Doble finally increased its economiser tube diameter as smaller tubing may have a slight but diminishing return as to BTU/sqft but then to achieve it the tube lengths and closer tube spacings start to present other problems. 1/2" OD seems to work out very well.
The multiple path lengths you talk about are not dependent upon having the same internal flow area of a larger tube, that is if the mass flow is equal in each the pressure drop will be much higher in the smaller tube I believe. Again it is just not a direct function of flow velocity but more of Reynolds number. It is a very wearysome project to calculate this as you are getting to be aware of.
It would be good to calculate the flow resistances under several ranges of boiler output to be assured that it will work.
The car fan motor is ideally suited for this purpose as it is very efficient and of high enough rpm to get the circulating pressure up in a smaller pump and housing, just keep it away from the thermal heat. Others have proposed positive displacement pumps but my own(ever enlarging) gut feel is that the boiler/Lamont boiler has a natural circulation ratio and the pump should allow natural circulation if the pump stops---enough to limp home!! An old fashioned packing gland approach would and did work perfectly well but its frictional resistance may well require more horsepower than the pumping of water--been there a few times. Go from 8-10 amperes@12VDC to 16-20 and Stanley owners blanche!!!
Sorry for not responding sooner, busy with the SACA/NE runway time trials,
Best and good luck, George</HTML>
One of the problems of circulating the whole "tube stack" is that we no longer end up with a counterflow boiler where the inlet feedwater is at its lowest temperature to absorb heat form the lower temperature gases---this is where the Doble counterflow approach has great success plus it removes some of the tubing from being a burden on the circulating pump. Even Doble finally increased its economiser tube diameter as smaller tubing may have a slight but diminishing return as to BTU/sqft but then to achieve it the tube lengths and closer tube spacings start to present other problems. 1/2" OD seems to work out very well.
The multiple path lengths you talk about are not dependent upon having the same internal flow area of a larger tube, that is if the mass flow is equal in each the pressure drop will be much higher in the smaller tube I believe. Again it is just not a direct function of flow velocity but more of Reynolds number. It is a very wearysome project to calculate this as you are getting to be aware of.
It would be good to calculate the flow resistances under several ranges of boiler output to be assured that it will work.
The car fan motor is ideally suited for this purpose as it is very efficient and of high enough rpm to get the circulating pressure up in a smaller pump and housing, just keep it away from the thermal heat. Others have proposed positive displacement pumps but my own(ever enlarging) gut feel is that the boiler/Lamont boiler has a natural circulation ratio and the pump should allow natural circulation if the pump stops---enough to limp home!! An old fashioned packing gland approach would and did work perfectly well but its frictional resistance may well require more horsepower than the pumping of water--been there a few times. Go from 8-10 amperes@12VDC to 16-20 and Stanley owners blanche!!!
Sorry for not responding sooner, busy with the SACA/NE runway time trials,
Best and good luck, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 24, 2002 10:24AM
<HTML>Hi George,
Thanks; no problem on the delayed reply. I tend to look at several options at once, and recently have been looking into a very different boiler (easier design/control, but more fabrication work) until I get a better handle on the wearysome calculations. I think just about everyone would hate my current boiler idea, so I'll keep it under my hat until I get some fabrication/running tests done on a miniature version.
One thing that has hit me recently is the severely diminishing returns with economizers & counterflow. Adding a few extra percentage points to boiler efficiency can require a 40-50% increase in square footage/weight/cost. That's fine for a big stationary unit, but maybe ~80% efficiency is good enough for a practical, affordable automotive boiler. And why tempt the Fates by flirting with acidic stack condensation during warmup, cold weather, and low fire conditions?
Peter</HTML>
Thanks; no problem on the delayed reply. I tend to look at several options at once, and recently have been looking into a very different boiler (easier design/control, but more fabrication work) until I get a better handle on the wearysome calculations. I think just about everyone would hate my current boiler idea, so I'll keep it under my hat until I get some fabrication/running tests done on a miniature version.
One thing that has hit me recently is the severely diminishing returns with economizers & counterflow. Adding a few extra percentage points to boiler efficiency can require a 40-50% increase in square footage/weight/cost. That's fine for a big stationary unit, but maybe ~80% efficiency is good enough for a practical, affordable automotive boiler. And why tempt the Fates by flirting with acidic stack condensation during warmup, cold weather, and low fire conditions?
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: August 24, 2002 05:42PM
<HTML>Peter,
Agree wholeheartedly!! 80-83% boiler efficiencies at high output are about as low as practical without adding many more tube stacks with such diminishing returns. Better to have the engine use 1/2#/hp-hr less to achieve the same overall plant efficiency.
Best, George</HTML>
Agree wholeheartedly!! 80-83% boiler efficiencies at high output are about as low as practical without adding many more tube stacks with such diminishing returns. Better to have the engine use 1/2#/hp-hr less to achieve the same overall plant efficiency.
Best, George</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 24, 2002 11:54PM
<HTML>Hi George,
Exactly! And there are all sorts of engine modifications -- some relatively minor -- which can cut water rate by 0.5 lb/hp/hr or more without negatively affecting driveability, durability, etc..
Peter</HTML>
Exactly! And there are all sorts of engine modifications -- some relatively minor -- which can cut water rate by 0.5 lb/hp/hr or more without negatively affecting driveability, durability, etc..
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: David K. Nergaard (IP Logged)
Date: August 25, 2002 09:58PM
<HTML>There is a cheap way to add an effective economiser to a Stanley. I bought a junk condenser coil from an air conditioner repair shop. I gives me about 7% improvement and has worked for thirty years so far. Feed water enters at 200-210 deg. and leaves at 270-300 deg. Flue gas enters at about 550 deg and exits at 250 -300 deg. F. Try to get one with copper tube. Many new ones use aluminum which probably won't last as well. If I remember rightly the thing cost me $2.</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 26, 2002 08:48AM
<HTML>Hi David,
That is a great retrofit to a Stanley, or to a new one-off project. I actually have some copper finned tubing that somebody gave to me, probably from an a/c condenser (?). It is in an odd-shaped coil about 8" diameter by maybe 18' tall. Three finned tubes, about 1/2" ID, are twisted into one braided length, and that triple-tube is then barrel-coiled. (Even my salvaged materials are multipath!) Darned odd looking. With some work, I could probably unravel it and rewind as needed, and I think it could handle 500-600 psig in economizer use. Don't know the square footage, but it is probably considerable, and I should do some measurements and calculations.
Anyway, the thing is, if I get a boiler running decently I will want to build one or more additional units, and then material supply/cost becomes a problem if I've designed around finned tubing. I'd probably end up buying new finned tubing for subsequent boilers. The new finned tubing I've seen so far generally costs at least 20% more than unfinned tubing, per square foot, and the extra square footage for a good economizer (with new tubing) is costly enough already with unfinned tubing.
The weight and volume of finned tubing is much lower per square foot, of course. At least compared to unfinned tube in typical sizes (1/2", 3/8" OD & the like). 1/4" OD tubing compares very favorably in volume/weight per sq. ft. to larger finned stuff, though 1/4" tube requires multipath (or multi-boiler a la Andy Patterson) design in automobile-sized boilers.
Your finned economizer is the best thing since sliced bread for Stanleys and one-off projects, and I think others can easily duplicate it with a little scrounging for similar low-cost recycled tubing. Really impressive results. Alas, I am currently aiming for a low-cost compact boiler which can be exactly & reliably reproduced in (at least limited) quantity with new tubing.
Peter</HTML>
That is a great retrofit to a Stanley, or to a new one-off project. I actually have some copper finned tubing that somebody gave to me, probably from an a/c condenser (?). It is in an odd-shaped coil about 8" diameter by maybe 18' tall. Three finned tubes, about 1/2" ID, are twisted into one braided length, and that triple-tube is then barrel-coiled. (Even my salvaged materials are multipath!) Darned odd looking. With some work, I could probably unravel it and rewind as needed, and I think it could handle 500-600 psig in economizer use. Don't know the square footage, but it is probably considerable, and I should do some measurements and calculations.
Anyway, the thing is, if I get a boiler running decently I will want to build one or more additional units, and then material supply/cost becomes a problem if I've designed around finned tubing. I'd probably end up buying new finned tubing for subsequent boilers. The new finned tubing I've seen so far generally costs at least 20% more than unfinned tubing, per square foot, and the extra square footage for a good economizer (with new tubing) is costly enough already with unfinned tubing.
The weight and volume of finned tubing is much lower per square foot, of course. At least compared to unfinned tube in typical sizes (1/2", 3/8" OD & the like). 1/4" OD tubing compares very favorably in volume/weight per sq. ft. to larger finned stuff, though 1/4" tube requires multipath (or multi-boiler a la Andy Patterson) design in automobile-sized boilers.
Your finned economizer is the best thing since sliced bread for Stanleys and one-off projects, and I think others can easily duplicate it with a little scrounging for similar low-cost recycled tubing. Really impressive results. Alas, I am currently aiming for a low-cost compact boiler which can be exactly & reliably reproduced in (at least limited) quantity with new tubing.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: Peter Brow (IP Logged)
Date: August 26, 2002 09:03AM
<HTML>Erratum: Looks like I typed 8" diameter x 18' tall for the dimensions of the odd finned "tritube" barrel coil I have. Make that 8 inches diameter by maybe 18 INCHES tall. If I had an 18 FOOT tall coil of this tubing, I could probably build economizers for a dozen boilers! Typo.
Anybody have any idea what a weird coil like this would have been used for? A/C is my guess.
Peter</HTML>
Anybody have any idea what a weird coil like this would have been used for? A/C is my guess.
Peter</HTML>
Re: Boiler Discussion Thread/Boilers only-
Posted by: George Nutz (IP Logged)
Date: August 26, 2002 10:25AM
<HTML>Peter,
I would not recommend the small air conditioner unit, as in Daves car, for high output boilers as the fins are so close together and gas pass area restrictive that any soot from the fire would shortly clog the fins and create more gas flow restriction. It works very well on Daves car as he is meticulous about NEVER forcing his burner or create any carbon in his exhaust. Many of the Stanley owners that force their burners a-howling to exceed the 4GPH burn rate do have soot/incomplete combustion at times and fins spaced farther apart would be more ideal. A heat exchanger paper I mentioned above with 6 fins per inch would be very efficient with sufficient fin spacing to not clog or offer too much gas flow resistance, especially with much higher gas mass flow rates and Doble type combustion systems. Remember the original Stanley 20HP only burned 4GPH with 100 square feet of heat transfer area and was lucky to produce 3-3.5#steam/ft.sq.-hr and had virtually non-existent gas velocites sorta-like one candle under each tube and flue gas in laminar flow. From your discussions think you are looking for much higher performance and much higher gas flow rates, keep an eye on how much burner back pressure you build into it!!
Best, George</HTML>
I would not recommend the small air conditioner unit, as in Daves car, for high output boilers as the fins are so close together and gas pass area restrictive that any soot from the fire would shortly clog the fins and create more gas flow restriction. It works very well on Daves car as he is meticulous about NEVER forcing his burner or create any carbon in his exhaust. Many of the Stanley owners that force their burners a-howling to exceed the 4GPH burn rate do have soot/incomplete combustion at times and fins spaced farther apart would be more ideal. A heat exchanger paper I mentioned above with 6 fins per inch would be very efficient with sufficient fin spacing to not clog or offer too much gas flow resistance, especially with much higher gas mass flow rates and Doble type combustion systems. Remember the original Stanley 20HP only burned 4GPH with 100 square feet of heat transfer area and was lucky to produce 3-3.5#steam/ft.sq.-hr and had virtually non-existent gas velocites sorta-like one candle under each tube and flue gas in laminar flow. From your discussions think you are looking for much higher performance and much higher gas flow rates, keep an eye on how much burner back pressure you build into it!!
Best, George</HTML>
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