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

[BronzeoakC@aol.com]

Dear list members,

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), 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.

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?

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