RE: GAS-L: Gas "topping" turbines

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

Peter Singfield replies:

> Yes -- and check out the gas cleaning required to do all this when
> gasifying biomasses! Truly awesome!
> 
Correct, that is why it is so much easier to at first (co-)fire product gas
from biomass gasification in a regular boiler. Only if all gasification
issues are solved (and depending on the type of biomass, the gas cleaning
issues as well), start looking at a gas turbine! 
I presume that holds true for both small and large turbines, i.e. for all
systems when maintenance costs and life time expectancy are factored in.

If one would elect to tackle those three problems all at once (i.e.
continuous stable gasification, gas cleaning and low CV CT-firing) it
requires parallel inputs from three quite different technical diciplines. To
succeed, that requires a solid joint venture or a large single organisation.

> The binary system is all about "topping" the thermodynamic reaction. I
> will eventually put an explanation of why that increases over all
> efficiencies in that "treatise" I am working on.
> 
Do that, Peter!

> I think they have lost touch with reality to use a gas turbine as the
> topping device. For that scale of project -- they could be using high
> quality steam boilers -- "topping" with a steam turbine -- and then binary
> cycling with a refrigerant.
> 
Not exactly sure what development you are referring to here. For some gases
a gas turbine works just fine in making use of that attractive thermo
dynamically quality called: high temperature. Advanced superheated steam
cycles reach only about half of that temperature.
So it is not so much in the gas turbine per se, as it is in the fuel gas
quality, where the problem is.

A binary cycle on a regular boiler is another route to arrive at the same
goal: a high conversion rate to electricity (heat extraction and delivery
generally not being the problem).
Perhaps the complications of a binary cycle can make up for the
complications of a combustion turbine fired on dirty, low CV product gas, or
for the complications of gas cleaning.
That comparison is worthwhile investigating, both for small and large
systems.
For existing large boilers an additional important question is: is a
retrofit possible and realistic.

> In fact -- in another corner of this world they are doing just that -- but
> in a most interesting way. It is called the Kalina Cycle -- water and
> ammonia. Search "Kalina Cycle"
> Now the exhaust from this turbine is fed to a refrigerant boiler -- where
> we can recover another good amount of btu's -- get the drift??
> Using a dual refrigerant cycle -- one to extract from 400 to 212 -- and
> the other (much lower boiling point -- say propane rather than butane) --
> to extract the latent heat from condensing at 212.
> Then yes -- you break the 50% barrier.
> And alos get rid of those huge condensers to blow the heat to the skies!
> 
Yes, that is what it is all about: how to minimize that heat loss (and not
limited to biomass gasification!)
How efficient one can be greatly depends on the availibility of cold cooling
water, though.
Those air cooler banks or cooling towers blowing hot air into the sky in the
middle of the desert can't help it, but are a far cry from (cold) ocean
water cooled condensers.

> Andries, at the plant you are working at -- do they use Gas Turbines??
>  And if so -- as sole device or as a "topping" device??
> 
Our gasturbine plants are both CC (Combined Cycle i.e.gasturbines+steam
turbine) and CHP (Combined Heat and Power i.e. delivering both kWh's+process
heat). In fact, at one of these plants, steam is both imported (from a
MSW-incinerator) as well as exported (to a chemical complex). 
That works like this: 
*	First: the imported steam (high pressure/medium temperature) is
thermally upgraded to high pressure/high temperature conditions by
superheating in waste heat boilers. 
*	Secondly: the upgraded steam is co-expanded together with the
balance of the steam in the HP turbine, to generate elec.power at a higher
rate of efficiency than would be possible in the MSW plant itself (since the
MSW boilers are limited in max temperature due to the chemicals in the flue
gases, like chlorine from plastics etc)
*	Thirdly, part of the exhaust steam from this HP turbine (cold reheat
steam) is exported as process heat. 

With the options of both thermal upgrading and process heat delivery readily
available, this makes for "the best of both worlds". We could potentially
even couple a biomass gasifier to feed into the natl gas main fuel flow!

My personal view is that for large biomass conversion scheme's to be
successfull, multi-industry integration will be at least as important as
efficiency improvements in stand-alone plants. Another example of
multi-industry integration can be seen in the US biomass initiative,
proposing to link power extraction with "chemical building blocs"
extraction.


Andries Weststeijn

> At 09:50 PM 1/26/2001 +0100, you wrote:
> >Joseph, and List,
> >
> >If you want to learn about large scale producer gas fired large
> combustion
> >turbines (CT), check out:
> >http://www.gasification.org/98GTC/Gtc00190.pdf
> >http://www.gasification.org/98GTC/Gtc00220.pdf
> >http://www.gasification.org/gtc99150.pdf
> >This is syngas from coal and oil.
> > 
> >These links might be of interested as well if you are looking for smaller
> >scale turbines for biomass producer gas. The principles remain.
> >
> >In any case, what you need to look for are turbines fit to burn Low
> Caloric
> >Value gas. In case of gasturbines burning low CV gas is not quite as easy
> as
> >it may sound. It is specialized work to arrive at stable flame
> conditions.
> >
> >Apart from GE in the US, in Europe Siemens is among the suppliers for
> larger
> >low CV gas fired CT's, in Japan Mitsubishi.
> >
> >A general list of manufacturers is:
> >http://gas-turbines.com/manufa/index.htm
> >but is doesn't seem complete.
> >
> >
> >Andries Weststeijn
> >
> >> ----------
> >> Van: 	Joseph FONIO[SMTP:joseph.fonio@oser.net]
> >> Antwoord naar: 	gasification@crest.org
> >> Verzonden: 	vrijdag 26 januari 2001 11:57
> >> Aan: 	gasification@crest.org
> >> Onderwerp: 	GAS-L: Gas turbines
> >> 
> >> Hello everybody at the gasification list,
> >> 
> >> I have heard about gas turbines used with gasification units, but I do
> not
> >> know any reference of it. Could someone give me examples of
> gasification
> >> plants using the producer gas in gas turbines ? Are there companies
> that
> >> develop (or sell) this kind of technologies ?
> >> 
> >> Thank you.
> >> 
> >> Joseph Fonio
> >> 
> >> ----------------------------------------
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