IGCC questions

[birkATO]

I am looking for anyone with some coal gassification background or knowhow. I am trying to understand how it is very viable. It appears to me that only about half of the resultant gas is combustable (H2 and CH4) and the rest being CO and CO2 + N2. How does this even burn in the gas turbines? I assume oxygen must be fed to the turbine with the gas, but even so, doesn't the gas have a pretty low heating value?

 

[JEB66]

You are correct, the gas turnine is fed CO and pure O2 for combustion. The other part of the system is the combined cycle. The heat in the gassifier, which turns the coal slurry into CO again fed with pure O2, is used to make steam for a steam turbine.

The IGCC is more expensive to build and operate than a conventional coal fired unit. But the selling point is the potential for CO2 capture along with other pollutants. The CO2 coming out of the gas turbine is nearly pure making it cheaper to capture as liquid CO2. Sulfure and other pollutants are taken out ahead of the gas turbine as pure streams as well.

If the IGCC's catch on, there will be a lot of cheap CO2 and Sulfur for sell.

 

[davefitz]

There are air blown gasifiers ( now being developed in Japan and Great Britain) and O2 blown gasifiers, as in US and in parts of europe. Most of the recently built gasifiers are in China, where the main product gas is used to form fertilizers, and not for power generation.

The current cost estimates for an O2 blown gasifier , where the product gas is to power a combined cycle, is about $1300 / KWe , whcih is about 25% higher than a coal fired supercritical unit. The big issue is availability of the gasifier vessels; recent experience indicates each gasifier vessel must be rebuilt ( new refractory ) after 9 mos operation. For a 92% + avaialbility, most vendors now recommend a spare gasifier vessel. But, sinc eht eoverall plant is more compelx than a conventional coalplant, one can show that the expected plant availability will be lower than for a PC fired supercritical unit.

IN 1981, a large EPRI study on advanced cycles, using economic sensitivity models, showed that the single greatest impact on return on investment for a large power plant was plant availabilty. For a typical investment of $1.5 billion USD for a IGCC, that is a lot of money doing nothing if the plant is not working.

There is also a culture amongst power plant operators that they cannot operate a chemical plant , which is what an IGCC is.

In my opinion, the most likely way for an IGCC to take hold is for it to be a multi- client plant. It would be owned by an LLC, whose partners would be a chemical company, a power company, and a fertilizer/ feedstock company. The highest value off-gas would be H2 , for use to mfr fertilizer etc. The low value gas would be transported via pipeline to several combined cycle plants, but a firm nightime gas user must be inlcuded.

 

[MJCronin]

birk,

Two publications (available for free) have been covering this evolution

"Power Engineering" Magazine

"Power" magazine

Good references as well as any ASME papers on the subject....

These plants will not be cheap....however this does not stop gas-bag layers and politicians from extolling thier virtues.

My opinion only

MJC

 

[klem]

Go to the Gasification Technologies Council website, which has recent presentations on current plants in commercial operation. Also search the DOE-NETL website for reports on projects as Tampa Electric and Wabash IGCC projects. These are 250+ MW plants on base load operation. GOOGLE will also give many sites with good data, including European plants.

 

[rmw]

GE has gotten into it in a big way, and from my experience, GE doesn't jack around with stuff they don't think isn't going somewhere.

rmw

 

[davefitz]

rmw:
Maybe so, but you have to admit, they have the power to influence the political decisions that generate an artificial market for their technology; one can fairly state that they are playing with a stacked deck. It wasn't a coincidence that the tax breaks for windpower were renewed after they bought the wind turbine company, and its not a coincidence that the energy bills being proposed are providing mucho incentives for IGCC.

 

[rmw]

Davefitz,

That may well be true, and my cynical nature won't let me dispute it.

But I say more power (pardon the pun) to them. If incentives are what it takes for us to start using our own abundant domestic resources instead of looking over the horizon for our energy needs, then let's give them the incentives.

Maybe they will hire a few US engineers, welders, electricians, etc in the process.

One thing I have always said is that power is one industry that they can't outsource (yet).

rmw

 

[davefitz]

rmw:
au contraire. The recent removal of PUHCA from the legal base will open up the US utilities to purchase by overseas firms. And , for large power plants, the use of foreign steam turbines and boilers is now a fait accompli.

Maybe the linemen will be local persons. But everything else , without exception, can now be outsourced.

 

[rmw]

davefitz,

Point well taken.

But I thought Scottish Power already owned all of the USA power plants. (Visualize tongue in cheek) I also thought that removal of PUHCA only meant that what you owned (whoever owned it-Scottish Power or not) now did not have to touch, as if AEP's holdings in Texas touched Ohio anyway prior to it's removal.

The paper industry has long since used foreign sourced machinery, specialized chemical recovery boilers, digesters, paper machines, etc., but that industry has provided lots of work for americanos to get that roll of paper to your toilet paper holder. Even that product, however, can be shipped in from overseas (and soon will be-IMHO).

But, unlike a roll of toilet paper, I don't see them ever putting a bucket of electricity on a boat for shipment to the USA so that the hamburger flippers can have the power they need to operate our coming 'service economy.'

rmw