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Practicality of steam power generation

Started by Paul_H, October 19, 2013, 01:19:43 PM

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Paul_H

Steam power has always interested me and I attend any shows in the area when possible.
I asked member magicmikey to give us some facts and figures on steam power and what might be involved in using steam power to generate electricity on a small scale.Mike has worked with steam for years in pulp mills and has agreed to dust off his text books and memory bank and help us out.
He will look in a little later.
There may be others here that have a working knowledge of steam and I sure hope you contribute and of course anybody else that has questions or answers.

Here are a couple questions from another thread that might belong here.


QuoteI'm curious why you wouldn't just make a steam engine to run the generator?

QuoteI'm struggling with this question as well.  The biggest negative to steam would be the need for a boiler... a pressure vessel with the potential to fail catastrophically, especially when constructed by someone who doesn't have a ton of experience welding.  That's part of the intrique and attractiveness of wood gas.  It's scalable and can be constructed by a do-it-yourself-er.  Plus, internal combustion engines are extremely common in ratings from 3 to 300 horsepower.  Steam engines not so much plus they are extremely expensive.  I have the ability to construct a steam engine as I work in a manufacturing facility and have machine tools available, but most don't.


Science isn't meant to be trusted it's to be tested

giant splinter

Steam is alive and well and some of the oldest of equipment around the world is working in various industries to this date, in it's early beginning it was the best alternative for manufacturing, heavy machinery, construction, railroad, shipping and many other energy hungry applications. Your post will be interesting to follow and it will give us a look at steam power from many perspectives ....... this one is going to be fun         GS
roll with it

Al_Smith

Copy of the previous quote:I'm struggling with this question as well.  The biggest negative to steam would be the need for a boiler... a pressure vessel with the potential to fail catastrophically, especially when constructed by someone who doesn't have a ton of experience welding.  That's part of the intrique and attractiveness of wood gas.  It's scalable and can be constructed by a do-it-yourself-er.  Plus, internal combustion engines are extremely common in ratings from 3 to 300 horsepower.  Steam engines not so much plus they are extremely expensive.  I have the ability to construct a steam engine as I work in a manufacturing facility and have machine tools available, but most don't./end quote

Comments yes pressurized steam is nothing for the unlearned to play with .However flammable gas weather bottle gas ,natural gas from a pipeline or self generated syn gas is not totally safe .It is a gas and it could blow up or cause a massive fire just like gasoline .

Even homebrew ethanol being flammable is not to be taken lightly .More than one "still" has exploded .



Fla._Deadheader


The best site I have found, for small operations, is HERE. After having worked around the type of engine he is using, I am sure a lot of you guys might know where one is hiding.

The site is not going anywhere, and, I don't understand why. It's a great idea.
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

magicmikey

  To respond to the topic, for most folks it would not be very practical. To the tinkerer in an area with abundant wood a possibility with the satisfaction of using old technology.

  The reciprocating steam engines efficiency is very low, around 20%. The best fancy quadruple expansion models were close to 30%. Steam engines need a long stroke [ or variable valve gear ] to get their power from the expanding steam. To build such an engine is not beyond a lot of folks.

  Boilers of any size are regulated [Canada ].  The safest are water tube types or the once through [ Stanley Steamer ] style. The cheapest to buy is probably a steam cleaner, about 2gpm @ 150psi which needs a fuel input of 320,000 Btu/hr. A wood fired boiler should deliver 6700 Btu/lb/wood or 50 lbs/wood/hr for the steam cleaner boiler.
   To produce 1KW electricity in a modern wood fired plant requires 3500 Btu/hr. For a reciprocating simple engine the real rate would be close to 50% greater -- my guess. :-\

  The feasability is up to the individual and site specific.
mike
   

Al_Smith

I think if one looks at the transition of the railroads from steam to diesel one of the big factors was the maintainence required to keep a steamer operational .Another factor that GM used in selling the diesel was the savings in fuel costs.

Now all that has nothing to do with home brew steam power but it should be factored in if a totally independant of the grid system is considered .

mometal77

Everytime i think of steam power i think of westinghouse.. the old man thought of a jack hammer used at that time in europe and later applied that to breaks... for air and is still used today.  Anything old lasts longer and is more reliable than certain things you even find in refineries from valves to regulators.
Too many Assholes... not enough bullets..."I might have become a millionaire, but I chose to become a tramp!

r.man

I once saw a steam schematic of the Titanic and it used the waste steam from one process to power the next process with a lower pressure requirement ending with cabin heat. That would greatly increase the efficiency. I have heard of commercial operations that use high pressure boilers to generate electricity and then use the waste steam to heat lumber kilns. Another interesting thing about the Titanic is that the generating unit was not first on the list, I think it was third.
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fishpharmer

I must admit I have a fascination and interest in steam.  Wonder if more efficiency could be achieved with today's technology and materials applied to boilers/steam engines?  That would increase costs, I realize.

Just for comparison, what is the average efficiency of comparable horsepower gas, diesel and electric engines/motors?  That may be comparing apples to oranges, torque may be a better factor for comparison?  I love the fact that steam engines produce tremendous torque. 

Built my own band mill with the help of Forestry Forum. 
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magicmikey

  A little research of modern engines shows the current effiency`s as -- gasoline ~ 40%, diesel ~50% and electric at 95+. These are for large HP and goes down as size decreases.

  For a plant to burn cheap fuel a gasifier, monotube boiler and a uniflow engine look to be the best combo for a 3-5Kw unit IMO. It would also have to have an attendant while running.

  There are several groups working to increase efficiency which means higher pressure and temps. The boiler holds a couple litres of water with 1200 psi steam at 1000*F. The exotic materials to go higher are very costly at the present time.
mike

lowpolyjoe

This thread just made me think of this video I saw the other day.   I think some of the comments said these are steam engines running on coal:

http://www.youtube.com/watch?v=l8nyrP8bclI

Steam power does seem attractive, especially for electricity in emergency situations.  Power was out for almost 2 weeks near me during last year's hurricane and most gas stations were closed, making my portable generator not all that useful :(   

Would have been great if I could have just thrown a few logs in a furnace and generated enough juice to run the fridge and a couple of lights.

Ianab

Stirling cycle engines are another option here. Basically it's external combustion, where the fire (or heat source) is "outside" the engine cylinder.

From a wood fired point of view you can see the advantage here. Basically can have wood stove, with the engine cylinder mounted above the fire box, and the "cold" side out in the cooler air. As long as the fire burns, the engine turns. Could run for hours with no user intervention, and be heating water at the same time. Gets away from the Steam engine needing someone to "tend" it while it's running.

Thing is no one seems to make a mass produced engine / wood burner for a sensible price.  :(

The technology is pretty old, and proven to work. Heck you can make one from tin cans that will run from a candle. Someone needs to develop a simple one that puts out a couple of kW from a small wood burner and mass produce it. Off grid power, emergency backups etc.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

mad murdock

Quote from: magicmikey on October 23, 2013, 09:11:42 PM
  A little research of modern engines shows the current effiency`s as -- gasoline ~ 40%, diesel ~50% and electric at 95+. These are for large HP and goes down as size decreases.

  For a plant to burn cheap fuel a gasifier, monotube boiler and a uniflow engine look to be the best combo for a 3-5Kw unit IMO. It would also have to have an attendant while running.

  There are several groups working to increase efficiency which means higher pressure and temps. The boiler holds a couple litres of water with 1200 psi steam at 1000*F. The exotic materials to go higher are very costly at the present time.
mike
are the thermal efficiency numbers taking into consideration the energy required to convert raw materials to usable fuel? Or just taking potential BTU's of fuel burned or otherwise consumed with each particular engine and measuring usable work on the output shaft of each? An electric motor is efficient at turning electricity into usable work, but it takes power to generate electricity in the first place, before you can consume it, same goes for gas and diesel, so not a true comparison, when you consider that the steam engine is burning a more raw form of fuel. I think if you factored in the energy consumed to produce the fuel each type of engine consumed, numbers would be closer together.
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magicmikey

  You are correct Ian, the Stirling bunch have gone hi tech and their machines cost. They have omitted the simple part. Tiny Tech India has the simple part with a similar cost without the high tech. You might enjoy "Jim Tangeman" on U-tube.

mad murdock, that is kinda tricky to do. A hyro electric power station has no direct fuel costs and can be used to subsidize it`s thermal plants skewing the numbers. I suspect your thoughts are in relation to ethanol or tar sands fuel production?
  The efficiency`s are for the engines only.
mike

Al_Smith

If the discussion is based on small scale production of electrical power steam would obviously not be practical .However larger scale production it could .

An example locally is Hoge lumber in NewKnoxville Ohio .Hoge is the largest producer of bowling alley maple in the world .As a by product of that production is thousands of tons of waste wood ,sawdust etc .They have a cogeneration plant that utilizes that waste and produce their  own power plus sell the excess .Making it very cost effective .

Keep in mind this is a large industrial operation with a full time staff

Paul_H

Magicmikey emailed me some links a few weeks ago and I just got around to looking at them on this lazy Sunday afternoon.There is a whole winters reading in this first link and in it are many more links to steam power,building and practical use.Kimmel Steam and Mike Brown's links are quite interesting.

Steam Power

Thanks Mike.
Science isn't meant to be trusted it's to be tested

GAB

Back in the '70's I worked for CEI an at the time power boiler and auxilary equipment manufacturer.  I was told that the thermal efficiency of a power boiler was from 17 to 22% based on the design, fuel used to power, and many other factors.  So as stated earlier the electric motor may be at 95% of what it receives or what is at the breaker in the building, but I believe that that efficiency needs to be multiplied by the thermal efficiency of the power source and also multiplied by the efficieny of the distribution system, to get to a comparable number.  At that time NSP (in MN) was diverting some of the waste steam going to the cooling tower(s) to heat greenhouses where they were growing tomatoes, peppers, and flowers.  To me this is a better use of the waste heat than putting it into the atmosphere.  The CEI super critical boilers were operating at 3990 PSI +/- and 1000*F +/- a little.  Again this is 30+/- year old info.  Gerald
W-M LT40HDD34, SLR, JD 420, JD 950w/loader and Woods backhoe, V3507 Fransguard winch, Cordwood Saw, 18' flat bed trailer, and other toys.

Dave Shepard

I would think the regulations would be as big a pain as the actual mechanics of making the thing work. I think water expands 1700 times when it goes from liquid to gas. And it's pretty much instantaneous. :o
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Paul_H

I was thinking about that this morning after I poured hot bacon fat into a tin can that had a bit if water hiding in the bottom.  :)
Science isn't meant to be trusted it's to be tested

fishpharmer

Interesting discussion thanks for the info. Thanks for link Paul_H.
Built my own band mill with the help of Forestry Forum. 
Lucas 618 with 50" slabber
WoodmizerLT-40 Super Hydraulic
Deere 5065E mfwd w/553 loader

The reason a lot of people do not recognize opportunity is because it usually goes around wearing overalls looking like hard work. --Tom A. Edison

Gary_C

I have managed a few large steam power plants, one to just supply process steam and another to power turbine generators for electricity with the waste steam used for process heating or drying. And I can tell you that it would be extremely difficult to match efficiencies with large power plants.

With any steam engine system, you have to have an auxillary use for low pressure steam first to even have a chance to achieve any reasonable efficiency. Second you have to capture all your condensate and return it to the system. That's for heat efficiency as well as water treatment costs. And third, you have to have very good heat reclaimers (and scrubbers) on the stack of your boiler or you will be spewing your efficiency up the stack. And the third thing is very expensive as when you cool your exhaust gasses you get some nasty and extremely corrosive gasses, think sulpheric acid.

So if you win the lottery and are looking for a place to burn some money, you can invest in steam power. But be aware, it will be a bottomless pit to do it efficiently.
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