Re: FW: GAS-L: Wasted heat retrieval to electrical power

[Peter Singfield <snkm@btl.net>]

At 12:40 PM 2/19/2001 +0100, you wrote:
>
>> Hi Peter,    ********Corrected version********
>> Andries made a comment (probably off list) regarding 1250 F (677 C) being
>> the
>> practical upper limit for super heated steam --
>> Andries -- take a look at:
>> http://www.nedo.go.jp/3color-e/shinene/shoene-4.html
>> 1300 to 1400 "C"
>> 
>> Peter, I commented on superheated steam temperatures in boilers. That's
>> about steel.
>A really quite high, but still realistic present day S/H steam condition is
>1080 F (580 C). There might be an example found of 1110 F (600 C) somewhere,
>but that's it.

That Url refers to a gas turbine. 

>
>> The link is on ceramic materials for GT's. Different ball game.
>Ceramic materials are not really ment for supercritical pressure piping.
>

Exactly! Just pointing out what the upper limits are -- due to temperature
tolerance  problems. Steam has hit the ceiling -- unless going to extremely
exotic lengths. such as using a ceramic pipe -- yet to be designed or
applied -- and then consider the boiler for this.

Mind you -- pressure is not important -- so it could be a low pressure --
high super heat. But the boiler surface area required to pull that off
would be more than incredible.

>> There is an European R&D project going on -including large boiler and
>> turbine manufacturers- with the aim of 700 Centigrade (1290 F) S/H life
>> steam temperature for large boilers to be reached in about 2010-2015! May
>> that tell you something.
>> 

Certainly does -- I'll stick with a working fluid that can achieve better
than even those over all efficiencies -- but at 400 F (oh -- what the "H"
-- say 450 F)

>> The high costs of austinitic boiler tubes and live steam piping may give
>> "cold" cycles (ran on refrigerant) more "financial room" to play with for
>> break even. 

That is my conclusion at this time -- short of a miraculous new tubing
material appearing on the scene. 

>> -Efficiency:
>> But the nett efficiency of these advanced steam-water cycles (thermal
>> energy into electricity) is estimated to be around 50% and that will have
>> to be met by these refrigerant cycles as well.
>> 

Yes -- and with a very simple boiler design -- even an old fire tube boiler
-- that would normally only have a less than scrap metal value due to the
cost of cutting it down into scrap sized parts.

OK -- repeating -- I see the refrigerant cycle being the solution for high
efficiency systems -- yea -- even passing that magical 50% efficiency --
for small and micro systems -- where handling a refrigerant system is not
such a logistical problem.

Of course -- up grading a small system to a large system is always feasible
-- and look at what prior art demonstrates occurring in the steam arena --
where they have "reached" to the very end -- through the introduction of
ever possible complicated device that can be invented by man.

Operating at 450F or less is definitely preferable in my mind. And one
would thing a water tube boiler should be hooked up to a geothermal power
plant -- just to test this theory.

That would involve moving a standard old bagasse burning fire tube boiler
to a presently existing geothermal plant and a little "piping".

One could simply direct fire that boiler -- gasification technology can
easily be applied after the fact.

On the other hand -- I could easily achieve these same goals -- that is a
proto-type test platform -- for under $200,000 -- right here in Belize. Say
a 25 kwh unit.

Instead of "finding" the right micro-turbine for this test -- I would use
the simple uniflow design I have at hand for the test engine.

It would not take much time to discover exactly how a 450F butane working
fluid power plant would be working.

Of course -- until my present business activities can produce an extra
$200,000 -- this will not be occurring.

So I suggest we drop this topic of discussion until such time, if ever,
that bench proto-type is built and some figures are derived.

We are simply wasting all our time otherwise.

Peter Singfield / Belize


>> 
>> best regards,
>> Andries
>> 
>