CO2 emission abatement in IGCC power plants by semiclosed cycles: Part B -With air-blown combustion and CO2 physical absorption

This paper analyzes the fundamentals of IGCC power plants with carbon dioxi de removal systems, by? a cycle configuration alternative to the one discus sed in Part A (with oxygen-blown combustion). The idea behind this proposal is to overcome the major drawbacks of the previous solution (large oxygen consumption and re-design of the gas turbine unit), by means of a semiclose d cycle ruing air as the oxidizer. Consequently, combustion gases are large ly diluted by nitrogen and cannot be simply compressed to produce liquefied CO2 for storage or disposal. However; CO2 concentration remains high enoug h to make separation possible by a physical absorption process. It requires a re-pressurization of the flow subtracted from the cycle, with relevant c onsequences an the plant energy balance. The configuration and the thermody namic performance of this plant concept are extensively addressed in the pa per. As in the first part, the influence of the pressure ratio is discussed , but values similar to the ones adopted in commercial heavy-duty machines provide here acceptable performance. Proper attention was paid to the impac t of the absorption process on the energy consumption. The resulting net ov erall efficiency is again in the 38-39 percent range, with assumptions full y comparable to the ones of part A. Finally, I-ve demonstrated that the pre sent scheme enables the use of unmodified machines, but large additional eq uipment is required for exhausts treatment and CO2 separation. A final comp arison between the hva semiclosed cycle concepts was therefore addressed.