Force circulation steam generator design

I have a question about code requirements for the forced boiler. At what point is certification required. Is there currently a minimum volume or is any amount ?

Steve
It all depends in what state you are using the pressure vessel in and where. States like New York and Road Island all pressure vessel are required to be code stamped by a holder of an S stamp. (A license pressure vessel builder holding a federally issued S stamp) Unless the law has changed in Massachusetts only stationary pressure vessel fall under the boiler laws. Cars boats tractors and cranes do not fall under the law, however if you have liability insurance they may require inspection by a certified boiler inspector

The federal code changed in 1995 to reduce the build pressure under the ASME to 3.5 times operating pressure. All material used have to meet the ASME code as well.

The ASME is a privet group of engineers that design and write codes as they see it and sale codes to States and business’s for there use, not all sections of the codes are used in many State’s the States may only use sections of them.

Insurance companies also get involved as was the electrical codes. The insurance Co changed the code in many States on electrical panels requiring all circuit backers must be the same manufacturer as the panel.

Rolly

Rolly,
I often wondered and perhaps you can clarify that the boilers we make and use on steam cars would be classified as a M boiler (miniture boiler)?

ASME Boiler Code Website

Kind regards,
Rick

Rick
As far as I know they are not.
I believe there was two court cases in NY regarding Stanley boilers.
They do not meet the code as it is written. Min head plate thickness on fire tube boilers by the code twenty years ago was 3/8” most Stanley boilers as built only use ¼ inch plate. The code requires in NY the main stop valve to be ASME approved as well as gate valve and two swing check valves on the feed water. Stanley uses neither. There is a section in the code for wire wrap pressure vessels. I am not sure if it applies to steam fired pressure vessels.
The two cases were found exempt from the code as there antique Motorcars. The late Brent Campbell was an adviser in the cases as he explanted them to me.
Stanley were exempt as being antique motor cars. Both cars were registered and insured.

Rolly

This certainly seems to be a state-by-state situation. As I understand it, Michigan has rules for boilers used in carnival rides, with the inspection standards being different if the ride accepts paying passengers.

Back when steam cars were actually common, the state passed a law (still in force) stating that automobiles were exempt from licensing. That said, when I inspected SE-101 at GM Design Staff about 25 years ago, it had an official inspection plate on the steam generator. That might have been a liability issue since a multi-tube, parallel path, once-through steam generator is even safer than a monotube of equal capacity

In Michigan, all boilers on steam powered vehicles are exempt, except for vehicles that travel on rails. So the steam scale locomotives must still be inspected, but it's only $15.

Thanks Rolly,
One more thought...
Under Power Boilers is PP (pressure piping) stamp approval. My ponder is if this applies to a forced circulation steam generator in the size that would be used for a steam car. In the case of Zimirken, he uses a pipe as his separator drum. I would say this can fall under piping, just a bigger diameter, still a pipe.

On another note, John Baldwich has loaned the ASME boiler code book to me. It's a big green bonded book that I have yet to open. I have to admit my procrastination in not opening it and should just research this query on my own. However, that would be less fun!

Thanks,
Rick

Rick
I designed and had built two boilers to the code. It took me a year to go through all the math required to satisfy the requirements. Hartford boiler insurance no longer has in house PE in pressure vessel design to overlook or except your work. The drawings have to be stamped with a PE stamp. They have a list of engineers they will except for there approval if you hire one. I did for a thousand dollars to review and approve my cad drawings and math.32 two pages of math. The only thing I, we disagreed on was my calculations on the thickness of the bottom drum plates for ligament spacing. Not an easy calculation to understand. I had 3/8 thick plate he wanted ½ ‘ plate. The sides and bottom were OK at 3/8. The builder had to be a registered PE and licensed with the national board and hold liability insurance to use an S stamp, the one that gave me the right price also used Hartford boiler insurance for there insurance.

As a construction estimator and builder I estimated the cost without knowing the added cost to be applied for the liability insurance to be between $5500.00 and $6800.00 the price came in a $6200.00

On the drawings every piece of metal has to be tagged and sized per the code and every welded joint with the weld symbol. All tapped holes have to show five full threads.
I have not kept up with all the changes, I did get a copy of the changes adjusting the boiler code in 1999 reducing the allowable stress values based on material design value be s to reduced to 3.5 rather then the 4 used for over half a century.

Rolly

So even a monotube has to be certified now? The recirculating system I'm working on was trying to stay away from a pressure "vessel " by using pipes or tubes.

It depends entirely on what state you're in. Most states have exceptions for boilers that power a vehicle. This is because stanley boilers aren't up to code because they use wire wrap for strength, and the state boiler regulators aren't going to force their owners to change them.

It's funny, the ASME boiler code is very expensive if you try to buy it. But pretty much every section of it is posted online somewhere on a corporate or government website if you google right. You might have to type in the specific numbers in to google to find them though.

On the forced circulation note, I found that my circulation pump was very economical to produce. It was inspired by someone's story I read online about a circulation pump they found in an industrial boiler. You have a series of check valves that are steam rated. Then you have a long tube from the middle of them to a piston pump. Because the tube is long, the pump itself isn't exposed to the high temperatures, similar to plumbing in a pressure gauge. This means you don't need a high temperature pump, it just needs to handle high pressure water. My pump was double acting, so the forces were mostly balanced (minus the piston rod area) so it required little power to run. You just need to make sure that the volume in the long tube is bigger than the pump displacement volume by about 2x, so the hot boiler water cools down before it makes it to the pump. This makes it WAY easier and cheaper to source the circulation pump.

Zmirkin, sounds like an interesting design for the pump. Right now what I'm looking at is a pump that is internal and uses high temperature magnets with an electrical field to rotate the shaft. This will work around the problem of pressure while the magnets will take the heat or so the company claims. As soon as my brother has corrected drawings we will see about putting them up. It's slow going for him to do the math. We have the radiant heat coils figured and now he is working on the hot air conduction.
SteveW

“Doble never did make a reliable monotube but continually added multiple function thermostats and band-aids to keep from burning the valves or shooting water into the cylinders. Although forced recirculation abounded in historical and contemporary use, he never considered it.”

So, then, what do we call this brain dump (unedited from his notebooks)?

July 16, 1936: How about using Helical as the Boiler & circulate the water?
1: Helical coil; say 1¼” O.D. x 1/8” = 1” I.D. – .7854 sq ins. Connected so that top of Helical normally discharges Saturated-Steam plus say 20% of boiling-water.
2: Inlet to Helical is an Injector, with water and steam flowing thru nozzle from bank of Spiral-Coils; Injector drawing from Vertical-Drum :---
3: Vertical Drum with water-level, receives steam-water, flows to throttle and superheater.
4: Thermostat to guard top-spiral coil in fireing-up with low-water.
5: Injector could be fitted to entrance of top spiral 2 coil section if desired.
6: With throttle shut, water-level in helical about same as water in drum.
7. Superheater could be below the 2 top spirals, and or surrounding Fire-Box; with perhaps a check-valve in pipe from bottom of Drum, so in steaming-up water would be forced to travel up Helical and into Drum.
8: Water could be circulated by an impeller-pump in bottom of drum, driven by a turbine impelled by the steam and water issuing from the top of the helical. The Turbine speed would be greater if only steam were discharged.

Karl Petersen

July 16, 1936: So, then, what do we call this brain dump (unedited from his notebooks)?

I’m guessing An attempt to use forced circulation.
Doble as far as I know never used forced circulation in any of the cars. Unlike Herreshoff. Whom used it long before Doble wet his pants.

The problem with the drawing as you presented it is the injector, I have never had one work pumping hot water. I used them on my boats for feed water and if the Hotwell got two hot they would not work or pickup I would have to rely on the feed pumps and the drawing does not show how he was planning to drive the circulation pump ?

I still have a ¾ Penberthy rated 300 PSI, I have seen some rated as high as 600 PSI not sure how high of pressure they will work. Might depend on the differential.

Rolly

I guess the question would be whether this were actually an injector, or if it was a thermopresser, which is very similar. Thermopressers work because they are fed with cooler feedwater which condenses steam tapped off of the boiler. This condensation produces a low pressure zone into which the steam/water mix is accelerated, reaching high velocities. This high-speed flow then drives a second-stage jet pump. This sort of thing has worked quite well in some nuclear power plants. I don't believe the term "thermopresser" came about until some years later and wonder if this was what Doble was referring to?

Ken

I have never seen one in use but am under the opinion it uses the pressure of the feed water to ingress the velocity of the circulation around or through the core of the reactor. Unlike an injector that uses the heat and pressure of the steam to move the water, mostly for feed water power or I also have used one as a bilge pump.

Rolly

I took the liberty to expand, clean up and identify some of the components.

Karl, no doubt that you have thought about the high pump pressure to get a mono-tube boiler to work. I think this was on Doble's mind also. I included a slide from my 2021 presentation about the comparison between Chuk's LSR boiler and British LSR boiler. Note that Chuk's boiler is a strict mono-tube.

What Rolly says about the injector or inductor as used to fill boilers in the steam locomotive is valid. It requires a temperature differential to function correctly. I often wonder if a simple nozzle will work in a T fitting like a mixing valve in a hydronic heating system.

I find it interesting how Doble saw to use a wound large diameter tubing, i.e. 1" IDIA to act as a drum. Much like Billy Barnes runs the LSR mile on the energy in the fire-tube boiler. Double is trying to store energy in the Tubing-Drum. I equate this in engineering terms:

KE (Kinetic Energy) = what steam is produced in a mono-tube boiler

PE (Potential Energy) = What steam is stored within a fire-tube boiler

E (Total Energy) = KE + PE

This combination in my mind, my opinion, is the next level of boiler to further the LSR record. It would solve the challenge of such high inlet pump pressures on a strict mono-tube. However, I would go with natural circulation in say an Ofeldt style as opposed to Doble's large Dia Mono-tube/Drum concept. My thought is that Rolly might agree. The next question for the optimum ratio of mono-tube to coil/drum, the use of say a hot well and an improved burner (IR) along with the use of super heat after the "Ratio" mono-tube/Drum...stuff to think about.

Large diameter tube to take the place of a drum is certainly a well-established concept. I swiped the idea and it was part of the package that the Canadian steam LSR team voted to adopt for their vehicle. Bonneville would not allow storage tanks, so this seemed like one way to get some reserve into the system. Honestly, the idea was not so much to store a bunch of energy (It would take too much water over that distance); the main purpose was to reduce pressure transients to simplify boiler control issues.

As you can see from the attached drawing, this Baker boiler patent used the idea. Heaven knows, Baker filed a number of boiler patents that seemingly covered every possible variation on the concept -- many of them utterly ignoring the "hot to hot, cold to cold" counterflow thermodynamic principle. I will admit that I got the idea for a storage coil in an LSR car from Jim Crank -- who freely admitted that he also was borrowing from Baker.

Having written a book on Baker, I became more familiar with his boilers than I would have liked. They published a very professional, extensive, test report on its performance. It wasn't bad, but there were better -- kind of undermining some of the mystique. I think maybe he was a little shy on economizer surface area and water and gas flows were not always ideal in relation to one another.

By-the-way I don't recall Jim Crank mentioning anything about this forced circulation concept in his book...am I correct?

Hey Ken, was this a top-down fired boiler?

Nope, all the Bakers were bottom-fired. They developed an atomizing burner, but used vaporizing burners, so they had to fire upwards. Tom has one in his collection, although it may be a reproduction.

I should note that Baker went the same route as Doble-Detroit, Scott-Newcomb, Waterman, International Harvester -- the steam car business never paid off but they did manage to produce some burners that were commercially successful to varying degrees.



Edited 1 time(s). Last edit at 12/07/2022 10:24AM by frustrated.

Backer Boiler

I think the Backer boiler is one of the worst boilers I have ever studied compaired with most of the orher automoble boilers and generators used. The superheater section alone has more tubing then White Generator. It’s high up in the top section of the boiler.
The Backer burner is the only good thing that came out of the design. I just don’t think enough were made to be widely used by others or maybe just two late in the steam car development and much more costly to duplicate for the cars used today.
But very nice workmanship patterns and castings.
I made a model of the generator as I have for a lot of boilers I have built full size but to scale the burner to ¼ size with my ageing eye site the parts are just two small.

Rolly

Please move the licensing and inspection thread to another title.

Karl Petersen

The Clayton Industries steam generator is a forced circulation unit. Sectional views of the pump are readily found online and on this site.

The circulating pump is a plunger pump driven by a reciprocating piston in an oil bath which pushes and releases oil into a chamber with a large stiff diaphragm. The diaphragm massages, on the other side, a volume of water at boiler pressure from which a vertical tube runs up to inlet and outlet check valves. The oil piston and diaphragm are also at boiler pressure. Since only the water up by the check valves is hot, the rest of the mechanism is protected from the heat.

The trick is that the diaphragm comes to rest on the back stroke so the oil plunger can catch a full stroke of oil for each push, but the actual energy consumed is only that to circulate the water.

This has been standard for many decades. The one I had was fifty years old and still working on the original materials and probably is still now after another half century.

Certainly there are other ways to run a relatively low energy circulating pump in a high pressure environment without requiring a reciprocating or rotary seal against boiler pressure with perhaps less complex hardware, but I have not run into them. Please let me know if you find any.

Karl Petersen

I can think of two circulating pumps. One is Charles French design for the Endurance steamer in which the piston circ pump is actuated by feed water pump pulsation. The other is an Alick Clarkson design with an internal turbine. This one has a seal, but it is to permit a power take off from the turbine and can be excluded.

Perhaps a fluidyne pump could be incorporated into the boiler, it is thermally driven and just requires a couple of check valves.

Regards,

Ken

Actually, there is one system that fits the bill nicely. It was used in nuclear reactors, I've found French and Soviet patents covering the same concept. (see attachment)

The thermopresser is a jet pump driven by both feed water and steam already resident in the steam generator.

Cooler feedwater is admitted to a jet pump nozzle so that it will draw hot steam into the flow. Since the feedwater is below saturation, it causes part of the steam to condense, creating a localized region of reduced pressure (in some cases, the region reached subatmospheric). Such a pressure drop caused more steam to expand into the nozzle at trans sonic velocity. This flow was directed to a second jet pump which did the actual circulation. This thermopresser is far more energetic than a typical jet pump because the condensation of steam creates its own thermodynamic cycle to drive the jet pump.

Strangely enough, the design seems to have been independently reinvented and marketed by some Greek restauranteurs as HelioJet Cleaning Technology. See patents 4,580,948 and 4,781,537.

I might as well toss this one in just for the fun of it. This is a rough concept of the circulation system that I am working out. The drawings are certainly not to scale and the pump/separator would have seals, bearings, heavier walls, and so on. On the other hand, trying to put in too much detail while trying to work out the concept leads to one of those "forest for the trees" situations.

The idea is a forced circulation boiler having no drum. Separation will be done in the pump/separator, which does both functions using centrifugal force. Water leaving the circulation coil will already be moving at fairly high speed due to some water expansion and about 15 percent of the water becoming vaporized. This water/steam mix enters the unit tangentially which helps preserve kinetic energy and gives the centrifugal separation a bit of a head start. The mix enters a drum having internal vanes, which is motor driven, though hopefully the entering water velocity will keep the pump load to a minimum -- maybe the motor's biggest function will be at cold startup.

As centrifugal force drives the water outwards in the drum, it passes through the loop seal, which is a fancy term for a set of U bends like those under your bathroom sink -- we used a lot of them in salt water distilling units aboard ship to let water flow between stages but prevent vapor transfer. The steam, being less dense, not only separates from the water, but is prevented from passing through the loop seal. The water passes into a slightly larger diameter impeller which pumps it back towards the generating coils by way of a perijet eductor. This is a form of jet pump where the fluid passes through the center unimpeded and the driving flow is introduced by jets on the periphery. In this case, the driving fluid is preheated feed pump water which has passed through the finned tube economizer coils.

The separated steam passes into the dry box through a piece of perforated metal, or some other type of retainer cap. Inside the dry box is a length of stainless steel screen which has been rolled into a cylinder and locked into place. This introduces rapid changes in the steam flow through the box, knocking some of the water in suspension to the bottom of the dry box. The wet steam then passes through the throttle valve and hence into the superheater coil before heading to the engine and auxiliary loads.

Level control will be handled by one extra coil above the top of the generator coil, which is connected by a T. Midway up into the coil will be a level control sensor which will start and stop the makeup feed water pump. Of course, the coil will be vented to the base of the pump/separator to prevent vapor lock.

All files from this thread

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