1 Steam Cars : Phorum
General Steam Car topics
Pumps for Boiler Circulation
Posted by: Peter Heid (IP Logged)
Date: January 04, 2005 03:59PM
<HTML>I have been reading about pumps for circulation in boilers used for controlled circulation in modern power plants. It seems most modern pumps, within the last 25 yearsor so, are of most all the same type. They all are vertical mounted with a vertical inlet, single stage centrifigual, overhung impeller. They run at constant speed, with no throttling using polyphase, squirrel cage, induction rotor design. They are zero leakage pumps of the canned (dry stator) or wet stator type and cooling water is circulated through out the pump motor. They use chrome plated shafts with water lubricated, journal bearings. The water circulated around the pump is of equal pressure as that which is circulated for the boiler and no seal is used. The losses from the pump due to heat are absorbed into the cooling (boiler feed) water and the friction of a seal is eliminated. With a polyphase induction motor there are no brushes to worry about and no permanate magnets to lose power in higher heat situtations.
With no multiphase power readily available in most cars, a 3 phase DC motor might be a good choice for the mobile version of the pump motor. Yes, your alternator is polyphase but it has too high a frequency for use with most motors or transformers. Now some are asking how you can have 3 phase DC. It is the same as any other 3 phase motor but the stator windings are pulsed by a solid state controller. Hall effect sensors are used to determine relative rotor position so the pulse is applied at the correct time. Some controllers are bidirectional and the current pulse can be reversed for motor reversal and braking is often available. The controller I am playing with can output 4 amps at 48 volts max and the only external components are the hall sensors. More current and voltage can easily switched by adding MOSFET output stages.
Has anyone had any experience with zero leakage pumps with water circulation in the motor housing ?</HTML>
With no multiphase power readily available in most cars, a 3 phase DC motor might be a good choice for the mobile version of the pump motor. Yes, your alternator is polyphase but it has too high a frequency for use with most motors or transformers. Now some are asking how you can have 3 phase DC. It is the same as any other 3 phase motor but the stator windings are pulsed by a solid state controller. Hall effect sensors are used to determine relative rotor position so the pulse is applied at the correct time. Some controllers are bidirectional and the current pulse can be reversed for motor reversal and braking is often available. The controller I am playing with can output 4 amps at 48 volts max and the only external components are the hall sensors. More current and voltage can easily switched by adding MOSFET output stages.
Has anyone had any experience with zero leakage pumps with water circulation in the motor housing ?</HTML>
Re: Pumps for Boiler Circulation
Posted by: George Nutz (IP Logged)
Date: January 04, 2005 04:29PM
<HTML>Peter,
Good to hear from you! Many years ago when Rod and I were experimenting with various designs for a Lamont circulating pump I had approached two major pump companies that made such pumps. The pumps they designed were not the teensie-weensie type like a miniature Lamont boiler but much bigger. I believe, in talking to the engineers at both companies, that there price quotes for making a prototype to specifications ranged from $22,000 to almost $40,000 for a single pump. Therefore we continued our labourious but inexpensive approach. We even tried and made a few Archenedies screw pumps, that when put into a thin nonmagnetic stainless housing could be driven magnetically without any seals whatsoever.
Although our trials and tribulations did work adequately the time to hog out a screw from a solid piece of stock was too much---and we didn't know who to approach on the magnetic drive question. We even tried two Tesla pump designs that also worked satisfactory but with the intent to keep the 12VDC amperage below 10 amperes for a circulation rate of 4-5000#/hr with a differential pressure of 5psi we went to our present centrifugal pump that has a specially designed impeller. Easy to make and only draws about 6 amperes.
All great ideas usually run into huge prototype expenses as mentioned above with the two pump companies. I believe over 40 pump manufactures were contacted in this unsuccessful search. I don't mind the shaft gland occassionaly dripping and ours takes about as little power to drive as anything I have seen. By the way the two quotes received were for pumps weighing 150-200# and drawing 1/2 horsepower or more. Engineers designing large pumps for stationary applications are thinking way outside our design parameters.
Its the way things go, George</HTML>
Good to hear from you! Many years ago when Rod and I were experimenting with various designs for a Lamont circulating pump I had approached two major pump companies that made such pumps. The pumps they designed were not the teensie-weensie type like a miniature Lamont boiler but much bigger. I believe, in talking to the engineers at both companies, that there price quotes for making a prototype to specifications ranged from $22,000 to almost $40,000 for a single pump. Therefore we continued our labourious but inexpensive approach. We even tried and made a few Archenedies screw pumps, that when put into a thin nonmagnetic stainless housing could be driven magnetically without any seals whatsoever.
Although our trials and tribulations did work adequately the time to hog out a screw from a solid piece of stock was too much---and we didn't know who to approach on the magnetic drive question. We even tried two Tesla pump designs that also worked satisfactory but with the intent to keep the 12VDC amperage below 10 amperes for a circulation rate of 4-5000#/hr with a differential pressure of 5psi we went to our present centrifugal pump that has a specially designed impeller. Easy to make and only draws about 6 amperes.
All great ideas usually run into huge prototype expenses as mentioned above with the two pump companies. I believe over 40 pump manufactures were contacted in this unsuccessful search. I don't mind the shaft gland occassionaly dripping and ours takes about as little power to drive as anything I have seen. By the way the two quotes received were for pumps weighing 150-200# and drawing 1/2 horsepower or more. Engineers designing large pumps for stationary applications are thinking way outside our design parameters.
Its the way things go, George</HTML>
Re: Pumps for Boiler Circulation
Posted by: Dick Vennerbeck (IP Logged)
Date: January 05, 2005 02:02AM
<HTML>Hi,
There are many pumps on the market that are magnetically coupled and do not rely on any seals at all. I used them in 1985 on my domestic solar water heater and they are still running strong for the new owner today. The new advances in ceramic and rare earth magnets make these magnetic couplings unbeatable. They can never leak and can run at quite high temperatures. All kinds and flows are available.
Dick Vennerbeck</HTML>
There are many pumps on the market that are magnetically coupled and do not rely on any seals at all. I used them in 1985 on my domestic solar water heater and they are still running strong for the new owner today. The new advances in ceramic and rare earth magnets make these magnetic couplings unbeatable. They can never leak and can run at quite high temperatures. All kinds and flows are available.
Dick Vennerbeck</HTML>
Re: Pumps for Boiler Circulation
Posted by: George Nutz (IP Logged)
Date: January 05, 2005 11:50AM
<HTML>Dick,
Just call a few of these companies and tell them you have an operating temperature of 600F and a proof test of 2000psi, desire 4000-5000#/hr with 5psi pressure differential circulating saturated waterand let me know how it comes out. As posted above I did this five years ago without success.
Good Luck, George</HTML>
Just call a few of these companies and tell them you have an operating temperature of 600F and a proof test of 2000psi, desire 4000-5000#/hr with 5psi pressure differential circulating saturated waterand let me know how it comes out. As posted above I did this five years ago without success.
Good Luck, George</HTML>
Re: Pumps for Boiler Circulation
Posted by: john f. (IP Logged)
Date: January 06, 2005 12:24PM
<HTML>Hi dick: I’m curious to know how high these temperatures are. Magnets can lose their magnetism at some specific temp then regain it when the temp falls. This effect is used in soldering irons to regulate the tip temp, but I never saw any of these over 500 degrees F.</HTML>
Re: Pumps for Boiler Circulation
Posted by: Andy Patterson (IP Logged)
Date: January 07, 2005 05:22PM
<HTML>How using an alternating curent magnet instead of permant magnets. Alternating curent magnets can induce a magnetic field in nonmegnetoc meterials. Basicly any good electrial conducting meterial. Would the cost to power the lectro magnets be more then leakage loss with seals. Might there be problems inducing the magnetic fieald through probably a metel barier.
Just a crazy thought.
Andy</HTML>
Just a crazy thought.
Andy</HTML>
Re: Pumps for Boiler Circulation
Posted by: peter heid (IP Logged)
Date: January 09, 2005 01:03PM
<HTML>Andy,
These pumps use a metal can around the stator on the dry version and the stator is immersed on the wet type. You will lose some electrical power through induction if there is a can around the stator but this is converted to heat which is practically all absorbed into the water. It is the same with any power converted to heat by the normal motor operation and any leakage in the seal area automatically goes into the feed water, nothing is lost or wasted. The thermal response of the motor is limited by the water temperature and the increase in restistance in the windings is also limited, preventing thermal runaway and the large increase in power consumption seen at elevated temperatures of operation. In a perminate magnet motor you have to energize the stator, just the same as a poly phase induction motor. The permanate magnet motor would be fine in this application and it could be run with a wet or dry stator also. A typical pump motor has a estimated life span of 100,000 hours while a comon DC motor is typically 11,000 hours. With no heat build up, cooled continous fluid for bearing lubrication and no seals to leak, boiler circulation pumps of this varity are by far the most reliable and efficient available when all factors are combined over the service life of the unit.
Dick,
A permanate magnet will lose power as it approches it's critical
temperature and most should be kept under 350 degrees F..
George,
Yes, there is nothing suitable for the size of boiler used in a auto but this type of pump can be built from existing motors. My purpose here was just to point out how the most modern steam systems have gained a bit of a percent in efficiency while reliability has gone up, and maybe a little bit of the info will help the experimenter.
Peter Heid</HTML>
These pumps use a metal can around the stator on the dry version and the stator is immersed on the wet type. You will lose some electrical power through induction if there is a can around the stator but this is converted to heat which is practically all absorbed into the water. It is the same with any power converted to heat by the normal motor operation and any leakage in the seal area automatically goes into the feed water, nothing is lost or wasted. The thermal response of the motor is limited by the water temperature and the increase in restistance in the windings is also limited, preventing thermal runaway and the large increase in power consumption seen at elevated temperatures of operation. In a perminate magnet motor you have to energize the stator, just the same as a poly phase induction motor. The permanate magnet motor would be fine in this application and it could be run with a wet or dry stator also. A typical pump motor has a estimated life span of 100,000 hours while a comon DC motor is typically 11,000 hours. With no heat build up, cooled continous fluid for bearing lubrication and no seals to leak, boiler circulation pumps of this varity are by far the most reliable and efficient available when all factors are combined over the service life of the unit.
Dick,
A permanate magnet will lose power as it approches it's critical
temperature and most should be kept under 350 degrees F..
George,
Yes, there is nothing suitable for the size of boiler used in a auto but this type of pump can be built from existing motors. My purpose here was just to point out how the most modern steam systems have gained a bit of a percent in efficiency while reliability has gone up, and maybe a little bit of the info will help the experimenter.
Peter Heid</HTML>
Re: Pumps for Boiler Circulation
Posted by: Andy Patterson (IP Logged)
Date: January 12, 2005 04:51PM
<HTML>Hi Peter
Thanks for going over the basics for everybody. But I was thinking of using the AC electromagnets in a magnetically coupled type pump. Sorry I wasn't all tha clear. External drive motor magneticly coupled to the pump.
Andy</HTML>
Thanks for going over the basics for everybody. But I was thinking of using the AC electromagnets in a magnetically coupled type pump. Sorry I wasn't all tha clear. External drive motor magneticly coupled to the pump.
Andy</HTML>
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