Friday, July 22, 2011

Texas Moves Forward With Clean Coal IGCC and Much More

Pulverized coal feedstock will be introduced into the two Siemens gasifiers along with limited amounts of nearly pure O2 gas and converted into syngas comprising H2 and CO, varying amounts of CO2, nitrogen (N2), sulfur species, methane, volatilized metals, and PM. The syngas will be cooled and cleaned of PM.

Next, the syngas flows through a water-gas shift reactor, in which steam is injected in the syngas over a catalyst bed, initiating a reaction where the CO in the syngas would be converted to CO2 and the steam would be converted to additional H2 in the syngas stream. This provides a syngas stream that is concentrated in both CO2 and H2.

Subsequently, the syngas would pass through a mercury removal system and then an acid gas removal system where first the sulfur species would be removed, then the CO2, creating a clean, H2-rich concentration syngas upon exiting the acid gas removal unit.

Captured CO2 will be further cleaned and compressed, and then transported by pipeline to an existing regional CO2 pipeline or, potentially, to a nearby EOR field. A portion of the captured CO2 will also be used to produce urea. The H2-rich syngas stream will be split, with part used to produce electricity via the turbine and the other part be used to produce urea for fertilizer. _GCC

Texas is home to some of the largest producing oil and gas fields in the continental US, including the Permian Basin. Whiting Petroleum needs lots of CO2 for EOR (enhanced oil recovery) in its Permian Basin wells, and coal plants make a lot of CO2 -- so the Texas Clean Energy Project (TCEP) is combining a clean coal IGCC power plant with CO2 recovery for Whiting's EOR. TCEP is even throwing in a urea from H2-rich syngas production process for fertiliser, using the Haber process.

Here is how it will work, after the coal is gasified to syngas:
The H2-rich, low-CO2 syngas will be combusted in a [gas] turbine generator to produce electricity. Combustion of the H2-rich fuel gas will produce water vapor and a low-CO2 exhaust gas with significantly lower CO2 emissions than would occur if the coal itself, or the raw syngas, had been combusted.

The exhaust gas would be ducted through an HRSG (heat recovery steam generator), which would generate high-temperature, high-pressure steam. This steam would be piped into a steam turbine-generator, which would generate additional electricity. This integration of the combustion turbine-generator, HRSG, and steam turbine-generator is known as a combined-cycle power plant.

The combined power generation from the combustion turbine-generator and the steam turbine generator would be approximately 400 MW (gross) with 213 MW sent to the grid, on average, and the remainder being used to run the plant’s equipment. The electricity sold would be transmitted to the regional electrical grid by a high voltage transmission line system. Natural gas would be used to start up the polygen plant and as a backup fuel (natural gas would also be used during operations to heat drying gases, supply an auxiliary boiler, and provide burner pilot flames such as for flares).

With two Siemens gasifiers, the TCEP will produce more syngas than can be used for electricity production. The additional syngas produced will be converted to NH3 using the Haber process. In that process, the H2 in the syngas is reacted with N2 from the air separation unit, forming NH3. Downstream, the NH3 is reacted with a portion of the CO2 from a syngas cleanup system, thereby forming urea in a Bosch-Meiser process. The urea is produced as a granular product common in the fertilizer industry.

...Argon and H2SO4 are by-products of the gasification process and would be made available for commercial sale. Inert slag, another by-product of the gasification process, would be sold for manufacturing and construction uses or disposed of off-site. _GCC
The plant could also utilise heat recovery processes to increase overall efficiency further.

This rather comprehensive approach to clean coal is capital intensive in terms of equipment required, design, and construction. Bureaucratic red tape adds a great deal more to overall costs. But once built, such a plant is far more reliable than wind or solar, and will last much longer if maintained properly.

This is not an approach that would be conceived by the lefty-Luddite dieoff.orgiasts who occupy government offices or by those regressive Greens who have so much clout with the Obama administration and EU governments.

But such an approach is a bona fide bridge to a cleaner energy future which will make good use of the abundant coal resource which exists. With only slight modification, "green coal" (torrified biomass) can be substituted for a portion of the coal to extend the resource even further.



Blogger Greg said...

What are the prospects for this approach- that is, with respect to the Obama administration: Good, Bad, or Ugly?

8:14 AM  
Blogger al fin said...

The US EPA will probably try to find a way to either shut it down or to delay it long enough to hurt the investors.

In today's political climate, regressive anti-energy policies by government agencies is just one part of the price of doing business.

8:54 AM  

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