CO2 Capture via Oxyfuel Firing: Optimisation of a Retrofit Design Concept for a Refinery Power Station Boiler

A previous study by the present authors demonstrated that the capture of carbon dioxide (CO2) from an existing large refinery power station boiler by conversion to oxygen firing with flue gas recycle is feasible and could be based on proven, available equipment. The study covered the systems for air separation, firing, boiler operation and CO2 separation and compression, and predicted the overall performance of the plant, the requirements for major new items of equipment and budget capital and operating costs. Further work has now been carried out to resolve key remaining uncertainties and to optimise the design. The new work reported here has considered in more detail the sensitivity of the plant performance and costs of conversion to such critical factors as the purity of the oxygen supply and the extent to which the boiler plant can be sealed against air ingress (tramp air). The effect of different levels of furnace modelling and the potential for plant integration have been reviewed. Significant opportunities for cost reduction compared with the previous study have been identified and the results will allow more cost effective oxyfuel plant designs and more reliable comparisons with alternative CO2 capture technologies.