IGCC Technology
Integrated gasification plants offer environmental benefits but at greatly increased capital cost when compared to more conventional combustion technology. The operational experience of these plants is also relatively limited.There are a number of different gasification technologies available which have been proven on large scale plants. The type considered within this report would involve an oxygen blown gasifier into which a coal/water slurry is sprayed at high pressure. The partial combustion which occurs would yield a synthetic gas (syngas) which is predominantly carbon monoxide and hydrogen. This syngas would be cleaned prior to it being combusted within a high efficiency gas turbine combined cycle power plant. Sulphur would be removed from the syngas producing elemental sulphur which could either be stored or used in the chemical industry.
Coal gasification offers the following benefits:-
• Cleaning of the syngas can result in very low stack emissions, comparable with natural gas firing.
• High combined cycle efficiencies can be obtained of the order of 48 per cent by utilising the most advanced gas turbine technologies available.
• Can be designed to handle fuels with very high sulphur content.
• Produces a sintered glassy ash which locks-in most chemical components present in the fuel ash.
• Offers the potential to remove carbon dioxide from the syngas for carbon dioxide sequestration, producing essentially a hydrogen syngas.
Appropriate treatment of the by-product streams from the gasification process and ensuring a safe design, means that the capital cost of such plants is high. It is envisaged that IGCC plants would comprise sites with a power generation in excess of 400 MW, with multiple oxygen separation plants and gasifier modules so as to achieve a high overall availability of the power generation plant.
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