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

[Weststeijn A <A.Weststeijn@epz.nl>]

> BronzeoakC@aol.com[SMTP:BronzeoakC@aol.com]
writes 20 februari 2001 17:55

> In light of the interchange between Andries and Peter, it is interesting
> to 
> note that in 1976 in a paper "Failure of Components in the Creep Range"by 
> Findlay (Paisley College) and Goodall CEGB),
> 
> Since this paper was based on units designed and installed in the period 
> approximately mid-60's to early 70's, we appear to have made little
> progress 
> on temperature limits in the last 25 years. 
>  Is this a fair conclusion? 
> 
Dear David Walden,

Yes, I believe your factual conclusion is right.
The reason being that the higher the temperature level you reach, the
costlier it is to add that additional 5 degrees C to your life steam
temperature. Let alone add 100 C from 600 to 700 C!

So, the proper austenitic construction materials must be researched and
commercially available (both for boiler AND HP turbine) and the ratio of
fuel costs over total power generation costs must justify the additional
investment.
So far, coal was cheap and emissions were free.

A few years ago a new stimulance for developing high temperature steam
boilers (and by consequence, high efficiency) was provided by the perceived
competition of Integrated Coal Gasification Combined Cycle units (ICGCC),
then about 43% but promising efficiencies to reach above 50%.

Nowadays an extra stimulance might be in the offing again from the expected
future costs of emisions. Emitting a ton of NOx will soon become a cost
factor just as much as feeding a ton of coal is already. So it will be a
double edged sword: cutting coal and cutting NOx by generating more kWh's
through higher efficiency.

In some places, like the US, trading in SO2 takes place already. But in
Europe the future price of emitting NOx might become the relevant factor,
especially for existing plants.

best regards,
Andries Weststeijn


>  they mention: 
> 
>       - 70% of Midlands (CEGB UK) Region plants have 565 C final outlet
> temp. 
>       "which establishes the upper limit for unfired components" 
>       - two supercritical units have 593 C final outlet temp. 
>       - Final stages of fired superheater and reheater circuits may be 
> designed for 650 
>       C with excursions to 700 C 
>       - Austenitic steels are used above 580 C. 
> 
> 
> Best regards, 
> David Walden 
> 
> 
> In a message dated 2/19/01 9:48:16 AM Eastern Standard Time, snkm@btl.net 
> writes: 
> 
> 
> 
> 
> 	Subj: Re: FW: GAS-L: Wasted heat retrieval to electrical power 
> 	Date: 2/19/01 9:48:16 AM Eastern Standard Time 
> 	From:    snkm@btl.net (Peter Singfield) 
> 	To:    gasification@crest.org (Crest Gasification List) 
> 
> 
> 
> 
> 	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 
> 	>> 
> 	> 
> 
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> 	Subject: Re: FW: GAS-L: Wasted heat retrieval to electrical power 
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