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Are there any small steam turbines commercially available? | 21 comments (21 topical, editorial)

Re: Are there any small steam .... (3.00 / 0) (#1)
by bob g on Sat Jul 26th, 2008 at 12:10:30 AM MST
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if you find one or a link to one please post it!

i have been wanting to try a gast air motor on steam, might make a hp or so?

bob g

Re: Are there any small steam .... (3.00 / 0) (#10)
by keithO on Sun Jul 27th, 2008 at 10:04:19 AM MST
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How about using a turbo charger ? The turbine end is typically good for at least 600 degree C, it does not require high pressure but works more on flow rate. You would need dry steam to prevent longer term damage to the blades and of course a reduction drive to get the output shaft speed to a sane level. It may be possible to adapt the reduction drive from a junked Solar T32 engine to do the initial speed reduction.

It would also be neccersary to use some sort of condenser to recover the steam for re-circulation else the efficiency will be dismal.

Turbo chargers recover a significant amount of energy from the exhaust in order to compress the intake air. Several horsepower in fact to move 400-1000kg/hr of air through the air filter, compressor, intercooler and then the engine. The compressors, being so small in diameter, are not very efficient which is one of the reasons why so much heat is generated in the intake air.

Some infrastructure is also required, an oil tank for lube oil, an oil pump, which needs to run before the turbo spools up, a control system to stabilize operation, the steam generator and recovery unit. Somewhere to put it all where it won't bother your insurance co...

[ Parent ]

Re: Are there any small steam ..construct. notes (3.00 / 0) (#21)
by primative (kittysteam.turbines@yahoo.com) on Thu Aug 14th, 2008 at 03:56:45 PM MST
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Hello,
From time to time I do a search just to see what is available in small steam turbines.
Not much, if any, New England S T seems to be out of business.
What I have seen a few years ago were not what I was looking for, being expensive, made of castings for housing, single runner, not good efficiency.
Well it would be nice to be able to buy something 'off the shelf' for applications in the 1 to 100 H.P. range.

yrs. ago I was offered a railway locomotive Turbogenerater, used for headlight and work lights, automatic train control/cab signals, and radio. Individual units for each application. The inlet piping was 1 or 1-1/4 inch size as I remember, so it used alot of steam at boiler pressure of ~250 lbs pressure, and probably weighed 200+ lbs, mostly castings. Manufactured by Sunbeam, I think. Perhaps I may be able to find archived documentation somewhere.
yrs. ago I built a small turboalternater, this worked surprisingly well. The disc was ~7" x 1/8" brass, with blades cut from 5/8" O.D. hobby tubing soldered to face for a radial inflow design. I made the expanding nozzle from copper tube, and the shaft from 1/2" diam. Stainless Steel, running in a 3/8" brass pipe nipple. Condensate lubrication was adequate with no signs of wear, surprisingly. The shaft was pinned to the pully bore of a Mopar alternater. I started at about 150 lbs. boiler pressure generating perhaps 7 amps and as I stoked the fire and the pressure went up to ~300 I was getting 45 amps at 15 volts. I think the nozzle orifice was < 3/16", maybe closer to 1/8". So good higher pressure really makes much more power. As the battery charged up the regulator cut in dropping the load on the turbine and I could hear the RPMs climb. The exhaust noise directly out of the can housing was not so loud as to be dis, just a high pitch sing. There was no governor, this was just experimental at the time. I got scared and backed away rather than shutting off the valve, and the pitch increased until there was a TING! sound of the blades stripping and that was all. The blading was so light weight there was no damage to the housing. I don't know what the R's were but not enough to throw the windings on the alt. rotor.

I considered the run a success even with the blade strip as I was very impressed with the amps output and the simplicity of construction and having it work on the first try enough to rebuild the rotor with stainless disk and bladeing and silver solder(which is much stronger and flows better) and fabricated a governor and throttle valve linkage. The greatest challenge was to attach the bladeing to the disk, I heated the disc on a 1 burner canp stove and the fed solder into the pre-positioned blades while also heating from above with a torch, rather a tricky piece of work as there is no stopping. I balanced the rotor and shaft by rolling along the top of the refrigerator and marking and drilling dimples at the heavy spot. There was no noticeable vibration.
I then tried making a 12" diam. rotor for 80 to 100 H.P. design. I was unable to have any but partial success in sweating the blades to this large a disc mostly having trouble with insufficient heat and flux build up and oxidation of metal. So I gave up on the direct soldering method and went about working up a method of fabrication and attachment of individual blades.
As anyone who has tried or wished to design and build a turbine of any kind will soon realize, the whole key to the making is in the ideal blade fabrication method; strong, light weight, inexpensive, repetitive accuracy and quality, simplicity of manufacture, minimal waste of materials, and modest investment in tooling. A browse through the Patents of the last 100 yrs. will attest to the efforts of many creative people in solving this design problem.
Once the bladeing is accomplished, the remainder of the turbine project seems comparatively easier, there are nozzles, governor and throttle, bearings and seals, and in some applications reduction gearing to provide. Most all of this is within the capabilities of a home shop machinist of well rounded experience. There is not much literature available specifically to small turbine design, there is the low pressure experience of Abner Doble (See book Doble Steam Cars) in using an exhaust steam turbine for condenser fan. In short, the nozzles are sized to the mass of steam and the pressure and the velocity, to produce the wanted torque and power, and the diameter and number of runners and blade angles chosen to keep the wheel speed within safe limits. An experienced designer soon learns what works and what is possible. A first time builder should follow a proven design. Work safely with high pressure steam.
Perhaps this post should be as a new thread.
If there is interest I may add to or continue this topic, let me know. In good work.
Primative

[ Parent ]

Are there any small steam turbines commercially available? | 21 comments (21 topical, 0 editorial)

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