The combination of Advanced Supercritical (ASC) steam boiler plant with oxyfuel is a feasible option for CO_2 capture: the basic components - oxygen production, operation of an Advanced Supercritical power plant, CO_2 compression/purification - all use existing demonstrated technology but at a very large size and in an integrated system. The overall plant performance for CO_2 capture at 110 bar pipeline delivery pressure from an Advanced Supercritical Pulverised Fuel (ASC PF) power plant, using a system based on capability for boiler operation using air or oxygen and using existing design of coal mills and electrostatic precipitation results in a plant net efficiency (LHV) of 35.4% compared to the state-of-the-art ASC PF air fired power plant without CO_2 capture net efficiency of 44.2% (IEA study). This study looked at the costs of a new-build oxyfuel-fired ASC PF boiler but was conservative in its design, maintaining current air-fired design philosophies. Oxyfuel-fired ASC PF boilers are likely to be first introduced as a retro-fit of an existing air-fired subcritical boiler. In this case, as opposed to a new-build, capital cost will be reduced by re-using as much balance of power plant equipment as possible. However, where a new-build plant is required efficiency can be increased and capital cost reduced by designing the boiler purely for oxyfuel-firing, with no provision for reverting to air-firing, based on the very high availability of a cryogenic oxygen plant and the possibility to start-up the plant without a separate air circuit. A design for a new-build oxyfuel-fired ASC PF boiler that has no provision for air-firing is discussed in this paper. The modifications would increase the plant net efficiency for a new-build oxyfuel-fired ASC PF boiler by a further percentage point and also result in a capital cost saving. The system offers an alternative to IGCC with similar efficiency and capital cost and the ability to retrofit existing power stations at half the capital cost of a new build.
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