Cyruscosmo wrote:I been digging around in the basement reading every post ever posted and am finding answers to questions I had not even thought to ask yet.
One design boiler design I'm quite fascinated with is the LaMont; this is a forced circulation boiler. This design provides even higher specific outputs than a monotube, with NONE of the control issues... but it does require a reliable boiler circulation pump,
and power (steam or electric when starting) to drive it. There are extensive discussions ongoing on the SACA (steam car) forums
http://steamautomobile.com/phorum5214/list.php?1, where I've been known to lurk.
- Bart
I ran across this post from you and found that we share the same interest in the La Mont style boilers. Have you found a source for a pump that would work for a La Mont that would operate under the temperatures and pressure we use?
I know they are made I just have not found anywhere I can get hold of one yet. Since I am still in the "finish my shop" mode I am considering building a boiler that I can experiment with while using it to heat the shop. The highest pressure pump I have found is 200 but it was designed for hot water not steam duty.
Cheers,
Scott
Hi Scott -
I've found a few pumps that would work for a small Lamont but they're likely to be quite expensive as they're industrial units. For industrial service, a 1.5 hp pump is tiny... and we're looking for something a tenth of that. The steam car folks have experimented with Lamont boilers, but in that case the design center is very high output with light weight; the edgy designs they use have little place, I think, in a steam boat unless it's for racing purposes. My goal is a reliable, quiet power plant; I'm sure one could build a Lamont to do this but there's quite a bit of engineering (and trial and error) to do to make something really right. I think a B & W or better yet one of the modifications of that design that offer a more compact structure is a better choice for what I'm looking for in a steamboat. My next boat is planned to be fairly good size (34' feet or so) with a cabin and used in the Pacific Northwest; we don't need to shave every pound for a boat that size. I'm also not interested in high pressure (for me, above 250 or so psi); the difficulty in finding valves, insulation and other components make such designs quite expensive to build, and the gain in efficiency modest; as a result of all a simple welded steel boiler seems rather a sure thing.
Some design comments on the Lamont... you'll need to insure turbulent flow (say Reynold numbers above 10000 or so) to realize the advantages of the pumped circulation. This means about 2 gpm in 1/2" pipe - not a lot, but it needs to happen so long as you have fire. I'd not consider solid fuel suitable for a Lamont boiler w/o redundant pumps & reliable pump power; I'd also consider multiple pumps required (or some other form of aux. power) if in open/dangerous (tides/currents/surf) waters. Remember that the pump only needs to produce a few psi pressure head - but the seals need to take full boiler temperature and pressure, which is what makes finding such pumps difficult. Also, the water you're trying to pump is about to flash into steam, so the design of the pump needs to require a very low NPSH.
From Wikipedia: "Careful design is required to pump high temperature liquids with a centrifugal pump when the liquid is near its boiling point." You can use a positive displacement pump, but gear pumps are probably out since any scale or such in the boiler water would soon trash the pump. A 2" bore, 1" stroke double acting opposed piston pump with lift checks and Viton or Teflon packing running about 100 rpm would do the trick - but it has to run all the time, even when the fire is just lit, so you'll need to use an electric motor.
If I were trying to build a Lamont boiler, I'd focus on the pump... build what appears to be a suitable pump, and test it by pump water in and out the mud drum of a regular boiler being fired, measuring the delivered pressure across a partially closed valve. When you get one that will live in that service, you can start w/ the rest of the project.
- Bart
. Or take a blower like that and drive it off the engine shaft....