Small steam turbine

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zbang said:
If you don't already have a steam source, it's almost a fool's game; the thermal efficiency of reciprocating generation is something like under 10% from fuel to electricity, the sawmills do it because they already have steam. A turbine will be more efficient but the small ones tend to be fast (>10k RPM) so there's a reduction gearbox to the generator or a very high speed DC generator and conversion electronics.

OTOH, if you want to play around with one, sounds good to me :D. You still have the issues of a >100 PSI boiler, fuel and water handling, daily maintenance, etc etc.
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This brain exercise does make me appreciate how amazing PV is, and how difficult (on a small scale) it is to get electricity from combustion/heat. Of course there is also hydro and wind too that get you your rotary motion with relative ease.
 
zbang said:
If you don't already have a steam source, it's almost a fool's game; the thermal efficiency of reciprocating generation is something like under 10% from fuel to electricity, the sawmills do it because they already have steam. A turbine will be more efficient but the small ones tend to be fast (>10k RPM) so there's a reduction gearbox to the generator or a very high speed DC generator and conversion electronics.

OTOH, if you want to play around with one, sounds good to me :D. You still have the issues of a >100 PSI boiler, fuel and water handling, daily maintenance, etc etc.
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At 100% efficiency you can get 9000 BTU per each pound of wood. If you burn the lb in one second you get 9 kw for one second. If I got the numbers and conversions right.
 
drcampbell said:
D'Oh! The turbine doesn't care how the steam was generated.
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He was looking for a design specifically designed to be fired by biomass. I'm sure the turbine doesn't care where the steam comes from, but you're going to be mighty disappointed if the skid arrives and and the firebox is looking for diesel and you've got a mountain of sawn logs!
 
zbang said:
If you don't already have a steam source, it's almost a fool's game; the thermal efficiency of reciprocating generation is something like under 10% from fuel to electricity, the sawmills do it because they already have steam. A turbine will be more efficient but the small ones tend to be fast (>10k RPM) so there's a reduction gearbox to the generator or a very high speed DC generator and conversion electronics.

OTOH, if you want to play around with one, sounds good to me :D. You still have the issues of a >100 PSI boiler, fuel and water handling, daily maintenance, etc etc.
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And perhaps noisy. The turbogenerators on UP4014 (for those who don't know, a BIG steam locomotive) make a very annoying high-pitched whine. And imagine care and feeding of a giant oil-fired boiler-on-wheels.

Here's a close-up of an old locomotive generator: Pyle-National 32V generator
 
WasGSOHM said:
At 100% efficiency you can get 9000 BTU per each pound of [dry] wood. ...
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Assuming the steam pressure is reasonable for a backyard installation, (150 psig?) and at a corresponding steam temperature, you'd be lucky to achieve 5% efficiency.

I think most jurisdictions require a stationary engineer's operating license for boilers exceeding 15 psig. Bad things can happen with steam boilers if you don't know what you're doing.
 
electrofelon said:
Well isn't that the only way to get electricity from a pile of wood or some petroleum that won't work in a ICE? (Other than the wood gas stuff)
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I would guess you can get more energy out of a pile of wood by burning it directly and heating a steam boiler with it than you would trying to make alcohol out of the sugars that are in the wood. You'd possibly use more energy making that alcohol than you get out of the alcohol itself.

My guess is steam production is typically more efficient on somewhat large scale than it is on a small scale. but then efficiency would still do down if driven load isn't all that much.
 
drcampbell said:
Assuming the steam pressure is reasonable for a backyard installation, (150 psig?) and at a corresponding steam temperature, you'd be lucky to achieve 5% efficiency.

I think most jurisdictions require a stationary engineer's operating license for boilers exceeding 15 psig. Bad things can happen with steam boilers if you don't know what you're doing.
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Plant I do work for has a steam boiler. Probably somewhat small scale boiler compared to a lot of them out there today in industrial plants, but likely the largest individual gas burning appliance input wise in the entire town and maybe even the county. (Ethanol plant about 20 miles away probably bigger but is not in same county) I think State Fire Marshal is the AHJ on this, I know there is no other localized authority that would even know anything about what to enforce. I don't think there is much AHJ intervention other than a required annual inspection, fairly detailed inspection where they have to shut it down and open things up for said inspection. It takes most of a day for this thing to cool down enough that it isn't producing any steam at all, (if not using any steam) and even then remaining water is pretty hot for quite some time if you don't introduce fresh cool water to help speed the cooling process down. This one the operating set point is around 90 PSI.
 
kwired said:
. . .more efficient on somewhat large scale than it is on a small scale. but then efficiency would still do down if driven load isn't all that much.
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So called Economy of Scale.
And large batteries should cost less per watt-hour than small batteries.

But then there is supply and demand.

Home Depot tool pricing does not always give you more hp per $.

And, "Diseconomies of scale happen when a company or business grows so large that the costs per unit increase. ... With this principle, rather than experiencing continued decreasing costs and increasing output, a firm sees an increase in costs when output is increased."
 
WasGSOHM said:
So called Economy of Scale.
And large batteries should cost less per watt-hour than small batteries.

But then there is supply and demand.

Home Depot tool pricing does not always give you more hp per $.

And, "Diseconomies of scale happen when a company or business grows so large that the costs per unit increase. ... With this principle, rather than experiencing continued decreasing costs and increasing output, a firm sees an increase in costs when output is increased."
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If you buy a Milwaukee or Dewalt power tool, maybe a couple others there is little to no decline in what you are getting, yet they can sell less than some others because of the volume they purchase. Some their other brands and especially any their private label brands yes you don't necessarily get the same bang for your buck.
 
electrofelon said:
This might be "ideal" for a backyard generation facility. If it's mass produced in India, I would think the cost would be reasonable. One would then need to make or aquire a boiler.

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Hopefully a boiler that is more efficient than what they used.

Notice the kid that was nothing but skin and bones that was feeding more wood to the fire? That one way to keep costs down I guess, he probably paid by giving him a meal.
 
electrofelon said:
This might be "ideal" for a backyard generation facility. If it's mass produced in India, I would think the cost would be reasonable. One would then need to make or aquire a boiler.

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Sounds like fun. Just a word of caution though. Working with steam and boilers can be fairly dangerous especially at pressures above 15 PSI.
 
I live in an agricultural area where peppermint and spearmint are grown. My house has mint fields on three sides of it. The fourth side was potatoes this year. Mint oil is extracted from the plant through steam extraction. The crop is cut once or twice a year. It dries in the field fir a few days then is blown into enclosed trailers to go to the still. Steam in injected into the trailer and the vapors are cooled and the oil is collected. The farmer will get 75-125 lbs of mint oil per acre per cutting. The left over plant material is then dumped, windowed and composted to be spread back into fields in the fall. The boilers used are 500-1000 hp boilers fueled by propane, diesel, or bunker oil. My neighbor has 2 boilers.

another farmer here has 6 boilers at his stall. For a while he was hauling his mint waste to a sawmill in Oregon. They were burning the mint in there boiler to generate electricity. They claimed that the mint slugs have more but’s per pound than wood chips. He was trying to see the efficiency of building his own boiler set up to use his mint biomass to generate the steam for the extraction process.
 
What are electric rates like in India, and/or service reliability?

Might make some more sense there than it does in the US, but that system pictured still is going through a lot of wood for no more output you will get from the generator.
 
kwired said:
What are electric rates like in India, and/or service reliability?

Might make some more sense there than it does in the US, but that system pictured still is going through a lot of wood for no more output you will get from the generator.
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Edit time expired - they could help themselves on efficiency some by returning the condensate back to the boiler.
 
One of the problems with using steam is that you need a high pressure and temperature differential to efficiently get much power out; part of that differential is using a condenser which develops a good vacuum on the exhaust side of the turbine/engine (...cooling water for the condenser... more pumps....place to dump the heat....).

Another problem is that high pressure boilers (over 15psi) do have all kinds of inspection and maintenance rules, need a National Board certificate, etc.

An automatic HP boiler might not need a licensed stationary engineer on duty all the time, but it usually needs one supervising the operation. And it'll usually need a trained fireman on duty which actually firing.

Did I mention controls and maintenance :D?

I'm going to guess the mint farmer is using LP boilers since they're not for power.
 
zbang said:
One of the problems with using steam is that you need a high pressure and temperature differential to efficiently get much power out; part of that differential is using a condenser which develops a good vacuum on the exhaust side of the turbine/engine (...cooling water for the condenser... more pumps....place to dump the heat....).

Another problem is that high pressure boilers (over 15psi) do have all kinds of inspection and maintenance rules, need a National Board certificate, etc.

An automatic HP boiler might not need a licensed stationary engineer on duty all the time, but it usually needs one supervising the operation. And it'll usually need a trained fireman on duty which actually firing.

Did I mention controls and maintenance :D?

I'm going to guess the mint farmer is using LP boilers since they're not for power.
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So you are saying it would be easier and more cost effective to add a few more rows of panels to my existing solar system? 😂
 
at one point the one Farmer was growing about 15-20% of the mint in the USA. About 7,000 acres were in Oregon. His still was at Boardman, OR. They used “waste” steam from a coal fired power plant there. Seems like the steam was still at 200-300 psi when they they got it. I know the stills here run at more than 15 psi, have annual inspections and licensed operators.
 
Dzboyce said:
at one point the one Farmer was growing about 15-20% of the mint in the USA. About 7,000 acres were in Oregon. His still was at Boardman, OR. They used “waste” steam from a coal fired power plant there. Seems like the steam was still at 200-300 psi when they they got it. I know the stills here run at more than 15 psi, have annual inspections and licensed operators.
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Steam is badass. Definitely would be a cool factor over more boring solar panels!
 
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