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Where to feed the water into a monotube

Posted by Big Steamer 
Where to feed the water into a monotube
August 06, 2007 08:47PM
Say I have a monotube boiler which has the fire at the bottom of the coil. Is it better to feed the water at the bottom into the coils that are the hottest first. Or in from the top and let it heat up some before getting to the hottest point?
Re: Where to feed the water into a monotube
August 07, 2007 08:11AM
The only design usable in any monotube is counterflow, the water flow goes opposite to the combustion gas flow. The water is pumped in at the stack end and the steam out at the hottest end.
JC
Re: Where to feed the water into a monotube
August 07, 2007 09:49PM
Jim,

You have brought up the 'waterman' system at some point. Your mention of counterflow to the combustion stream makes alot of cents. I remember when I was about 17 years old, like 1989, I remember this huge buzz about counterflow too thermo-siphon, which(thermo-siphon) was set in motion by Henry Ford. I was in a machine shop discussing removing the thermostat from a Windsor 302(ci) v8 engine. Its pretty dam hard to make a waterpump flow that way without an electric one(waterpump).

Is the waterman system the same(monotube) system that used the quartz rod[for inlet regulation] or was that the White system. I am currently working with a LaMont system for steam generation, but I need no pressures greater than 50 psi. Im just curious since the monotube systems generally can have the best of both worlds, moderate capacity and high pressures.

Also, this brings me back to superheating saturated steam(Im ok with my combustion driven designs , for now). I am still working on the solar central receiver, for my solar project. I can not give a definite weight, for the disk I plant use just yet, but it should be around 100lbs. Its the superheating circuit, that I would like to explore. I'd hate to cast this thing without some basic guidance. Even though I get the aluminum at a discounted rate, the retail value of the alu alone is like 2 grand. Compared to the price of the thick wall copper tube thats involved, is much cheaper to get that wrong, than the weight of the aluminum thats being casted.


Jeremy
Re: Where to feed the water into a monotube
August 08, 2007 09:14AM
Jeremy,
Monotube steam generators are always counterflow, heat flow opposite the water flow.

The Waterman system has nothing to do with how the coils are fired, it is a means of controlling a monotube steam generator mechanically, so to speak.
It depends on an external separator that feeds a special steam water pump from the bottom; but through a controlling needle valve or an orifice. Wet steam and the pump slows down, dry steam and the pump speeds up. The pump exhaust is fed to a feedwater preheater to recover the energy otherwise lost.
Then the steam to the load is taken off the top of the separator, through a buried superheater and then out.
The steam pump was special in that the shuttle valve was designed to work with both water and steam.
A dandy system and I have played with one and seen it work.

The White system uses a copper rod thermostat-water needle valve that cheats the flowmotor by putting the now extra water behind the flowmotor piston, making it think that the engine and car have slowed down, so it modulates the firing rate, by the flowmotor closing the fuel needle valve a bit. Works perfectly as long as the flowmotor piston had the right clearance and the groove in the wall was the right size. It is not an On-Off system, the water valve on the thermostat is constantly in operation, a long tapered needle.

Ford used thermo syphon in the Model T because it was cheaper than putting on a pump. In that car, it usually worked, although all of us that had Model T cars, 23 roadster, put on one of the old accessory water pumps, along with Rocky Mountain brakes and a Ruxtel two speed rear end.
Ford was not the first to use thermosyphon by a long shot, many cars used it.

JC




Edited 1 time(s). Last edit at 08/08/2007 09:17AM by James D. Crank.
Re: Where to feed the water into a monotube
August 08, 2007 09:28AM
Hi Jeremy:

The Waterman system is one where a donkey pump fed steam to the boiler. The donkey pump was specially designed to run on either pressurized hot water from the boiler or steam. A pipe and orifice connected to the boiler at the desired water level powered the donkey pump. If the level was low the pump ran on steam at relatively high speed. If the level was high the pump ran on water at a relatively low speed. I imagine that instead of using a quartz rod thermostat, Waterman probably just used boiler pressure to increase and decrease the burner firing rate. For more information see US Patents 2,355,125 and 2,679,832. A Waterman control system using a standard, off the shelf, float type steam trap to control the pump is described in patent 2,426,909. A Waterman design for a duplex feed pump can be found in US Patent 2,531,094 although from Jim's earlier descriptions this does not seem to be the pump used on the control system.

I have to note, by the way, that while I am sure the control system was effective it probably wasn't efficient. By that I mean it controlled the system very well but the use of a donkey pump probably consumed more energy than other methods would.

Ken

Postscript. I see that Jim posted his reply after I started typing mine and finished before I did,making most of my reply redundant. Darn that trip to the coffeepot! For an alternative view of flow through a monotube consider reading Patent 4,621,592 issued to Vapor Corp.





Edited 1 time(s). Last edit at 08/08/2007 09:32AM by frustrated.
Re: Where to feed the water into a monotube
August 08, 2007 10:32AM
Ken,
The Waterman boiler I saw was at Alec Clarksons in Arizona at a SACA meet.
The basic idea was for a non electric control system that was 100% reliable at all times.
Return the otherwise wasted heat from the pump exhaust to the system was by using a good feedwater heater and that exhaust went into a small condenser with the water going back into the day tank. Actually in operation, very efficient.

He said that they used both simplex and a duplex pumps at first, duplex in unattended field operations, oil fields, to be sure it always ran, although the simplex pump was deadly reliable all the time.

Also, that usually the steam pump feed was off the bottom of the separator, although at some water level in the separator would also work, they prefered the bottom conection. You could see a water level build up in the separator with a sight gauge, then hear the pump slow way down, the water disappeared and the pump sped up. The outlet temperature in Alec's unit was very steady.
There is no proscribed water level in a monotube.
Burner firing was strictly by pressure control.

Alec mentioned that one neat thing happened with this system. When the boiler was shut down automatically, the pump kept working until the pressure dropped to zero, filling all the coils, then they would be full of water for the next startup.

Waterman covered his idea with several patents.
JC
Re: Where to feed the water into a monotube
August 08, 2007 11:35AM
Hi Jim:

Wow....a SACA meet at Alick Clarkson's place with Russell Waterman demonstrating a steam system. Guess I was born too late! Last SACA meet I went to Tom Kimmel said that at age 48 I was dragging the average age of attendees way down.

I might have to take back what I said about efficiency, if the feedwater heater was very effective then losses for the donkey pump should be acceptable. Probably a built-in bias of mine as most feedwater heaters I see appear to be modestly effective, but this certainly need not be the case. By the way, warms my heart to hear someone refer to a 'day tank', some of the old terminology is just nicer on the ears.

I am extremely interested in non-electric control schemes wherever possible, hence the interest in systems like the Waterman. My own plans include an engine driven feed pump that mechanically measures the boiler water level and regulates output accordingly, a simple pressure control of firing rate and a valve operated inline desuperheater to control final output temperature...if needed. Add in the jet recirculator pump and the electrical loads are trivial.

Waterman also patented a jet pump forced recirc. boiler, US Pat 2,404,114. Since he collaborated with Charles French I guess that one is no mystery. He had another forced recirc. system in which feed water operated a gear motor that drove a proportioning gear pump; 1,797,109; more complex than the jet pump but less vexing than an electric for the state of the art at the time, I guess. As another example of nothing new under the sun, my throttle valve is pretty close to one Waterman patented although I suspect basic design elements probably long preceded him.

Interesting note that the feed pump steam line originated in the bottom of the separator, I wouldn't have picked that as my first location. From your description he played around with that a bit, I tend to bow to experimental proofs so that is likely the optimum location.

One thing that I like about engineering is that there is almost never a universally preferred result but instead unique solutions for specific needs. In another Waterman patent I saw that he had developed a system to drain the boiler on shutdown, exactly the opposite of what this boiler system accomplishes. I'm sure both are suited for their niche.

Thanks for the follow on information, it certainly fleshed out the bare facts previously available.

Regards,

Ken

Re: Where to feed the water into a monotube
August 08, 2007 01:03PM
Ken the patent # 2679832 sheet 7 you posted earlier looks to me to be a forced cycle coil the same as C.A. French used with an injector.

Thanks very much for posting these patent # Great enjoyment.

Rolly
Re: Where to feed the water into a monotube
August 08, 2007 02:06PM
Ken,
Yes at Alec's ranch, way down by the Mexican border. We drove there in Ken Maxwell's 1917 Stanley from his place in Tucson.
Alic also showed us a right and left hand screw expander he was building for a VW Karman Ghia conversion. Steam went in in the center. No axial thrust this way.
It fascinated Besler and Becker no end. Bill had never seen such a thing.
Tiny thing, and 30 hp too.

I have no real feeling if the Waterman system is fast enough to be used in a car; but it sure would work in a boat.
As Alec told me, they liked the bottom connection, because it first saw wet steam and water and the pump reacted to this earlier than with the side connection.(?)
Actually, Alec said it sort of modulated the pump speed instead of a more on-off operation. Also, as he said, splashing in the separator would confuse the pump if the connection was on the side, in a car application. Made sense to me.

If you like non electric systems, take a very good look at the flowmotor White version. Now, with all my ranting about never changing a White, they did sometimes get themselves into trouble with overheat, rarely; but it does happen.
Start out when the car has been off by pressure for a while and the pumps have been bypassing, always start with the pumps going, then it doesn't happen.
Must say though, they REALLY get sprightly with 1,000° steam!! Outran a full Rajo equipped T once, made the owner very mad, bragging how fast his Ford was all day. Simply blew his door handles off in front of everyone. Great fun.

There is a way to put in a normalizer on a White. Consider that the pump pressure is higher than the outlet pressure, simple fluid flow friction, run a tiny line from the thermostat's water line going to the flowmotor, put in a check valve and an orifice, then run that line to the top of the steam generator where the superheater connects. Automatic normalizer.
By the way, that White water valve is not on or off; but constantly varies starting around 400°F, I instrumented mine to find out. Also I plugged the inlet to the flowmotor once and let the thermostat simply dump. It sure did modulate.
One would have to play with this so it didn't flood the coils; but that is easy.

There sure are a great number of ways to design a steamer, that is the great fun in working on them.
Jim



Edited 1 time(s). Last edit at 08/08/2007 02:08PM by James D. Crank.
Re: Where to feed the water into a monotube
August 08, 2007 02:32PM
I know of a car that had a monotube with a fire under the coil. Initially the feed was bottom to the top. It worked but couldn't make a lot of steam. So it owrked marginally. With feed from the top to Bottom it didn't work very well. The car stalled every few feet. Now that was with an on off control system.

The White was a top to bottom with the output end of each coil going up over the coil stack and back down to the next lower coil. It allso uses a variable proportioning control system.

Obviously the most efficient heat exchanger is counter flow. But you are fighting gravity with the fire at the bottom of a monotube steam generator. The White worked. But its up and over loops coutered the gravity induced flow. I don't know if it would have worked with out them.

Andy


Re: Where to feed the water into a monotube
August 08, 2007 02:42PM
Andy,
It would, both Besler and Clayton made hundreds of boilers with the fire on the bottom. I posed the same question years ago and was told it made no difference where the fire was as long as the two flows countered each other.
LLoyd Lanterman also made one with the water going the same way as the fire, didn't work at all. If it is a concern, and it shouldn't be, then make the coils slightly conical.
Sounds as if there were a lot more problems with this car than just how the coils were fed.
Jim



Edited 1 time(s). Last edit at 08/08/2007 02:44PM by James D. Crank.
Re: Where to feed the water into a monotube
August 08, 2007 04:04PM
Hi Jim.

The car I saw was a natural convection boiler like the White.

Were the boilers you know to work forced convection or natural.

The one I saw had a Stanley type or simular burner. It was a reproduction of a Loco Mobil.

I can see where if the firing rate is enough lower then the flow due to gravity you could pass liquid.

A water trap could eliminate any problem.

Andy
Re: Where to feed the water into a monotube
August 08, 2007 05:37PM
Andy,
All the White cars are indeed forced circulation.
The Besler and Clayton are all forced circulation monotube.
You are worrying about a situation that does not happen in practice.

My last boat had a Clayton steam generator in it. Flat pancake coils and then to a helical coil around the firebox, with the outlet on the very bottom and the inlet at the top. The burner was up firing. Never had one problem.
Interestingly enough, when pumping it full prior to firing, no water EVER came out of the bottom blowdown by gravity that I put on to clean the coils. I checked for this too; but it did not flow down by itself.
JC



Edited 1 time(s). Last edit at 08/08/2007 06:10PM by James D. Crank.
Re: Where to feed the water into a monotube
August 08, 2007 06:00PM
Hi Jim,

thanks for the reply. Very informative. I will post some drawings to help with the discussion(the solar steam stuff), on a new thread.

I remember Rolly posted a link to a page on the locomobile, several years back. I searched thru the whole list and it seems that thread is gone. It was a fantastic picture of the locomobiles boiler schematic of how the burner control interacted with the waterfeed rate. I think it used a copper-rod that expanded to control some things. I went out on google to try and find the page Rolly had linked too, but could not find it.


Jeremy
Re: Where to feed the water into a monotube
August 08, 2007 06:17PM
Jim. I was talking about forced convection or natural convection of the combustion gases.

Natural convection small boilers usually don't have near as high a steaming rate as forced convection.

"You are worrying about a situation that does not happen in practice."

I believe in appling murfy's law. If it can happen it will happen.

What happens at long stops. Possable for fire to be completely off for some period of time.

Anyway it's simple enough to use a water trap to prevent water slugs geting to the engine. Better to account for it then not and be sorry.

Andy
Re: Where to feed the water into a monotube
August 08, 2007 06:20PM
Jeremy,
Now that I would sure like to see. Of the ten or so Locomobiles I have seen, ridden in and driven, not one has any such a control.
I think you are referring to the White. Temperature controlled by an expansion rod thermostat that modified the water feed and another one that worked the fuel flow to the burner. Or do I have that backwards? It's been a long time since I looked at an early White.

The best and really only source of information on the White is an old pre 1908 edition of Homan's "Motor Vehicles and Motors" and the White catalogs. The later 1912 edition covers the flowmotor control models.

Jim

P.S. I just found a copy of "Steam Propelled Vehicles" a chapter from the Homan book that really describes the White system.
Lindsay Publications has it for sale and it is well worth getting.SACA Stores should carry this.



Edited 1 time(s). Last edit at 08/08/2007 06:31PM by James D. Crank.
Re: Where to feed the water into a monotube
August 08, 2007 08:51PM
Hi Jim:

That right and left hand screw expander sounds about like the LP turbines on a ship, double axial flow so the thrusts cancel. I've seen dummy pistons in single axial flow turbines that were there for the same reason, they did nothing but compensate for the thrust in the turbine staging. Smarter design than just sticking in big thrust bearings and loading them up. I've seen really nice screw air compressors but I admit I have to wonder how sucessful they would be with high temperature steam. Seems to me that thermal expansion would be all over the map as the steam moved outwards and cooled, making sealing a difficult task.

I spent a fair amount of time studying the White controller for another project of mine, a paddle wheel steam outboard motor. Well, EVERYONE has done a steam outboard with propellers. Figured this would not only be more fun to watch in operation but might be really quiet when sneaking up on bass in the shallows at dead slow.

I realize that even a good deal of study is no match for hands on experience, so I figure I'll be lucky if my controller works adequately without major redesign.

I ended up scrapping the entire White mechanism but keeping all the operating principles, or so I think and hope. I gave Tom Kimmel a copy of the drawings and a description for a write up in the Bulletin whenever he runs out of real articles and is desperate for something to print even if a bit crackpot. I admit I dread your critique, I probably made some glaring error in design you'll spot instantly, but fortunately I take feedback well after the intial whining, kicking and sniveling passes by. The following is probably too abreviated for thoughtful discussion but gives a clue as to where I was heading.

I was never fond of pressurized fuel tanks, so I ended up going with a fuel pump driven off the feed water pump. This also eliminated the flow motor while keeping the water/fuel ratio constant. A lost motion mechanism causes both fuel and water pump strokes to shorten as boiler setpoint pressure is reached, a fair trade for the relief valve in the White, I thought. The fuel flow is set high and the thermostat progressively recirculates fuel back to the tank as temperature is reached, about equivalent from an output standpoint to what seems to happen when you bypass the flowmotor. A variable restriction mechanism (works on similar principles to a flow motor) produces enhanced back pressure when total water flow reaches boiler capacity, this causes the lost motion mechanism to further shorten fuel and water pump strokes. Hopefully this is analagous to that 'other' valve in the flow motor.

I was careful to design all components so that they were easily adjustable without any component disassembly. The fuel/water ratio, thermostat, boiler pressure and maximum flow rate can all be adjusted by wrench while the engine is running. If nothing else, it was a fun exercise to try to reinvent the logic behind the White control scheme without using a flow motor.

Thanks for the normalizer tip for the White, seems simple enough in principle. Well worth installing for what little it costs.

I hadn't thought about the White overheating, but I can see it happening in the situation you describe. As you say, the performance with 1,000 degree steam had to be enhanced. Almost sounds worth trying to modify the hardware to get this result every time you stopped, a few seconds of extra boost coming off the line probably isn't a bad thing given modern driving conditions.

As you say, there are almost an infinite number of ways to make a steam system work. Just doing research on what has been tried before has been fun, trying to put a new spin on it has also been fun if probably not terribly productive.

Regards,

Ken
Re: Where to feed the water into a monotube
August 08, 2007 09:03PM
Hi,,For a general description of the White system,,,,Watch for the large Webster's dictionary // 1912 I think,,,I cut it out and saved it,,now cant find it,,lets see,, cut it in 1949 I think,,,It was 2 pages,,one on a 4 cyl Caddy,,other on White,,,,Ben
Re: Where to feed the water into a monotube
August 08, 2007 11:01PM
Ken,
I never laugh at anyone's ideas, you never know when a nugget of real insight appears.

That end thrust was one main reason I abandoned the Lysholm screw idea. Left and right pitch with steam going in the center. The temperature clearance problem was serious enough to quit thinking about one. Barrel grinding the housing, not nice.

I too never liked that pressurized White gas tank. In fact, that is the exact reason why Thomas White ended steam car production, also he saw that steam was ending and it was gas cars from now on, a pure business decision by Thomas.
Also, on one of the Glidden tours, the pathfinder White broke a rear spring which punctured the gas tank, big mess; but only minor burns to the three in the car.

This always puzzled me, because the reason always given was that the Stanleys had the patent on those two little tanks with the air pressure cushion, and would not let the Whites use it under license. I would bet that if White took them to court, the Stanleys would have lost. Such goes back to Roman times for providing wind for pipe organs.
Yes, they had them back then. The first theater organs playing for the games.
Think of the song when the Christians were being chewed up by the lions: "A Cup of Coffee A Sandwich and You". Enough of that, couldn't resist.
Jim
Re: Where to feed the water into a monotube
August 09, 2007 11:31AM
Hi Jim:

The Romans were luckier than those of us in the Detroit Metro area, at least THEIR Lions won more often than they lost. OK, I couldn't resist either.

Truthfully, I don't mind being laughed at, more than used to it by this stage of my life. As Admiral Gallery once noted, "That'll never work and besides, you're crazy!" is the standard US Navy response to any new idea. The only time a negative critique really bothers me is when it is dead on. Not that I hold it against the person offering it but having to go back to the CAD screen and put in extra work HURTS! As they say, "Necessity is a mother."

I suspect that you are right, Thomas White probably pulled the steamer from production as a pure business decision. When you consider the White company was a going concern decades after the vast majority of manufacturers from the same period folded, it is hard to fault his decision. People can always argue that a different course of action would have been even better, but success is rare enough that those advocating a different course are more likely to have been wrong.

Sicne the topic is flow through a monotube, this next will actually be dead on topic. While reading through the old Forum postings this morning I noted that Dave Nergaard had used an air conditioning condenser as an economizer for his Stanley. I had much the same idea after coming across a few steel finned AC condensers myself. Anybody have any thoughts or experiences to share?

Guess I should get back to working on that cylinder head pattern for my steam engine.

Regards,

Ken
Re: Where to feed the water into a monotube
August 09, 2007 07:48AM
Ken
There is a big difference between an economizer in the flue gas area and a condenser using air or water as a coolant.
Flue gases can be dirty and often are. David has had good luck with his fined economizer, he keeps his burner running clean. An oil burner or solid fuel is another story.
I have made many different types of economizer using 3/8 K -- ½ OD .049 wall copper tubing with ¼ tube diameter for spacing. I always pick up 100 to 150 degrees.



Re: Where to feed the water into a monotube
August 10, 2007 09:15AM
Hi Rolly:

Thanks for adding the pictures, as always worth a thousand words, very informative and also good looking workmanship.


I'm planning on burning gasoline, kerosene, diesel, fuel oil or vegetable oil interchangably as supply permits. For the time being solid fuel looks like more hassle than I want in a vehicular application. Not that I am vehemently against solid fuel, I'm the whacko who suggested the SACA time trials be replaced by a road rally on northern Michigan off road vehicle trails. My thought was that each car run only on whatever wood or other fuels the team could scrounge from the forest along the course. If nothing else I thought maybe better press attention would result from a 50 mile race run on fire wood.

Perhaps the wisest course would be to build the burner first and see just how cleanly, or not so cleanly, it handles each fuel. From there the decision as to economizer type might be clear. The only tests I have made with the burner so far have been with gasoline and that burned with zero residue after the first few seconds of warm up, but no guarantee other fuels will be as gracious.

Thanks very much for the input, as always it is greatly appreciated.

Regards,

Ken
Re: Where to feed the water into a monotube
August 10, 2007 10:42AM
Rolly,

With a good ecomomiser, what is a low practical stack temperature using oil as a fuel?

Thanks, ------ Bill G.
Re: Where to feed the water into a monotube
August 10, 2007 11:07AM

Bill
I was getting under 400F, if I remember correctly around 350 to 375 on my Derr boiler in my 1920 Stanley I like gauges. I added an eight position Alnor Pyrometer see attachment.



Re: Where to feed the water into a monotube
August 10, 2007 12:13PM
Bill
The Derr economizer is 100 lin ft of ½ OD copper tube .049 wall. That’s 13 Sq Ft of heating surface. See attachments.



Re: Where to feed the water into a monotube
August 10, 2007 05:03PM
The smoke hood gas temperature on my Model H with no economiser fitted is 480 to 550F, the higher after running a couple of miles uphill with the burner on full. There's a lot of heat to recover.

I ran a pancake coil economiser for a year or two but eventually had trouble with leaks due to chafing of coils. It's like a giant bourdon tube so not surprisng that heat expansion and pump pulses make it move. Rolly do you think the back and forth loops will be less likely to chafe than a spiral coil?

Also - Rolly - what a pain to have to look at the road sometimes!

Mike
Re: Where to feed the water into a monotube
August 10, 2007 05:39PM
Rolly do you think the back and forth loops will be less likely to chafe than a spiral coil?

Mike I don’t think it matters. There really should not be much thermal movement when up to temperature and running. I noticed a pretty constant temperature even with the feed water going on and off.

I make economizers to fit the space available, never had a problem with chafing yet.

I use lots of ties made with # 8 solid copper wire. It’s getting hard to find except from wire distributors. You do have to be aware of the mounting area. Time will tell.

Also - Rolly - what a pain to have to look at the road sometimes! Yes it is.
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