GAS-L: Oh!! -- that small steam power plant ---

[Peter Singfield <snkm@btl.net>]

OK folks -- this is a long one -- Gonjo math modeling from one end to the
other. How to make that 29% plus over all efficiency; small, simple,
economical; 3rd world combustion power plant.

************************

Hi Skip;

At 08:50 AM 3/18/00 -0600, you wrote:
>built a tesla 20 years ago.....it drank too much
>last year's iowa energy fair, jeff hays(tesla pres) brought the turbine that
>"they" had worked on for so long
>at my challenge, ran it on my boiler.  made a lot of noise and barely
>turned.
>i stopped it with my foot.  i was giving it 20hp worth of steam.  poor guy
>was an emotional wreck and the crowd was amused.
>if there is a lot of 'were gonnas', 'yest but', 'they', 'conspiracy this',
>one detail or another in the speel, it is crap.
>
>you are going to lose legitimacy and credibility if u push the tesla thing.
>
>skp


Not pushing the Tesla thingy at all -- simply re-investigating it. Found
this out.

In his original model -- it took 24 lbs steam to produce 1 hp -- this steam
of 125 psi with 250 F superheat.

125 psi saturates = 344F - with 250F superheat = 594 - say 600F

This is steam of 1327 btu per pound

24 lbs * 1327 btu/lb = 31,848

One HP/hr = 2546 btu/hr -- so:

31,848/2546 = 12.5 HP in to get 1 HP out

1/12.5 = 8% efficiency.


But -- needing a speed reducer and no torque. Big problem handling
variations in load demand.

I have always been pushing one thing "only" -- making Unaflows again. I see
great potential there for a moderately high efficiency device for small
steam power plants.

I am interested in designing the "better" small combustion power station
for 3rd world. I know there is a simply incredible demand out there for such.

I keep checking "other" designs just to make sure that my original goal is
valid. Hate to get blind sided by tunnel vision -- 

To show you just one example of what a unaflow can do:

(From: Kent's Mechanical Engineer's Handbook -- 12th edition -- 1950 --
"Power" Volume -- page 8-110)

Title: Condensing operation with saturated steam at 150 psi (Gauge) 

Variation of Steam Consumption with load on Engine

(Taking this from a graph -- so numbers are relative -- "close" -- but not
exact!)

(Load is % of rated HP)
("Steam" consumption = lbs/hr)

500HP Uniflow (Spelled Uniflow -- not Unaflow -- in this example)

Load   --  Steam 

10%         17.3
20%         15.2
30%         14.2
40%         13.8
50%         13.4
60%         13.2
70%         13.6
80%         13.7
90%         13.8
100%        13.9
110%        14.0
120%        14.3
130%        14.7
140%        15.0
150%        15.4

Only the unaflow design can give economic efficiency ratings over such a
load variation. This is of prime importance in a variable demand situation
-- which is what we get a lot of when generating powder in 3rd world. The
standard method with steam turbine plants is to balance load using
secondary diesel gen sets!! The Unaflow eliminates that expense!

To give some perspective -- real efficiency ranges of the above.

150 psi saturated = 348.42F = 1194.1 btu/lb

(One HP/hr = 2546 btu/hr

17.3 lbs of that steam = 20,657.93 btu/2546 = 8.11 hp "in" 

1/7.65 = 12.3% efficiency (worst case!!)

13.2 lbs/hp = 15,762.12  btu = 6.19 hp "in" 

1/5.84 = 16.2% efficiency. (Best Case)


Taking your present engine example -- where I guesstimate (reasonably I
feel) 5.25% engine efficiency.

You are presently producing 25 kwh. If you changed over to that unaflow
engine you would be producing:

16.2/5.25 = 3.08 times more power or:

25 * 3.08 = 77 kwh instead of just 25.


I am quite sure your customers will appreciate the difference!

And remember -- all this with 150 psi "wet" steam!! Give it the same steam
conditions as you are presently using:

"i have addressed that problem and the new 
engine uses less than 20lbs steam per hp hour 
on less than 400 psi, 250 nominal and 600
superheat.  same with the boiler."

And you could expect efficiencies well over 20%!!! 

Also -- you stated:

"The most important thing to know is that when 
pressures exceed 250psi and temps get over 400 
degrees, everything gets real expensive.  No 
threaded pipe, special valves, seamless tubing 
with lots of alloy, jig bends everywhere and on 
and on........also, when you want nice efficiency 
figures, you need expensive material handling, 
and engines need expensive materials and on and 
on.......  i have addressed that problem and the 
new engine uses less than 20lbs steam per hp hour 
on less than 400 psi, 250 nominal and 600 superheat.  
same with the boiler.  I am at 8 lbs wood per hp/hr 
and will hit 5 on ideal conditions."

I could not agree with you more!! But I have just shown how you can more
than triple your present output using a unaflow piston steam engine and at
pressure of just 150 psi saturated -- no super heater!! With the quality of
steam you describe above -- the unaflow would do 20+% easily!

Actually -- the condensing on exhaust serves the same function as
superheating. You simply have to decide if it is easier and more economic
to super heat rather than run a condenser.

You also stated:

"I would be happy if a turbine in the under 
500hp got 10%, and didn't cost a
million dollars plus millwrighting."

Why bother when you can build a Unaflow?

But there is one fly in the ointment -- here is it:


WEAR OF CYLINDER AND OF PISTON RINGS. 

Under average conditions, a set of piston rings travels over 
300 million feet before renewal becomes necessary. Steam 
cylinders last for about 1500 million feet of piston travel 
before reboring becomes necessary. Cylinder walls are usually 
made thick enough for two reborings. For 24-hour-per-day 
operation, this means that a set of rings lasts approximately 
14 months, that the cylinder must be rebored every 8 years, and 
that it must be replaced after 25 years. Both figures are 
influenced by the quality of rings and cylinder, by solids 
carried in the steam, and by effectiveness of lubrication. 
Piston rings of incorrect shape exert concentrated localized 
pressure, producing local wear and even glass-hard spots in the 
cylinder. These spots can be removed by grinding only. A set of 
rings is sometimes worn out in 2 months while another set will 
last 2 years. If cylinders are made of ordinary soft cast iron, 
the wear may be five times as rapid as indicated by the above 
figures, which apply to castings of hard cylinder iron. After a 
short period of use, cylinders made of the right kind of iron 
acquire a semiglazed and reasonably hard surface. From then on, the 
wear is slight.

************************

The turbine is much more maintenance free -- but if you can live with the
above (and I can!!) -- the Unaflow is just great. By the way -- the above
applies to any steam piston engine -- including the one you are using now.

You also mention:

"who knows?  If I sell enough of these dinosaur 
engines, then I can produce a fancy engine at 
a cheap price....but....I just paid a bunch of 
taxes this year.....someone has to pay for the 
'grant crowd'."

You could easily set up here in Belize -- in an "Industrial Free Zone" --
and get a 20 year tax free "bonus". This also includes no import or export
duties.

OK Skip -- any reasons not to do all this??

One last point --

If one put a second unaflow system running a refrigerant working fluid as
the condenser for the first -- one greatly increases over all plant
efficiency -- putting it right up there with the most exotic, expensive and
huge -- present state of the art -- turbine power plants.

I see a simple setup -- nothing "exotic" -- producing 25% engine
efficiencies on steam and picking up another 20% on the second
refrigeration cycle.

This give over all engine efficiencies of 45%!!

Using the standard, low number, boiler efficiency of 65%

65% * 45% = 29.25% over all plant efficiency!

and this is a "conservative" estimate based on examples of what has
presently existed for 100 years!! (OK -- but not the Gasifier furnace/boiler)

This is what I am truly interested in pursuing -- not Tesla Turbines.
Whether I ever get into the right position to experiment in this direction
- well that is the question. And when I have finished that -- I'll move on
to building the ultimate gasifier!

Peter in Belize


Peter Singfield
COROGEN
Executive Director
Xaibe Village
Corozal District
Belize, Central America
Tel 501-4-35213
E-mail: snkm@btl.net



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