Analysis of supercritical coal fired oxy combustion power plant with cryogenic oxygen unit and turbo-compressor

This paper reports the results of thermal, energy, exergy and economic analysis involving a hard coal fired power plant with a two-column cryogenic oxygen unit and operating in an oxy combustion process. As a novelty it was assumed that the auxiliary steam turbine drives the oxygen unit compressor and the bleeding steam for this purpose is extracted between intermediate- and low-pressure stage (ILS) of the main turbine. Calculations were performed to consider a number of alternative designs, in which the principal issue was to consider capacity and efficiency loss of the power plant resulting from the drive of the compressor from a cryogenic oxygen unit. The results showed that steam from ILS of the main turbine could be used for driving air separation unit (ASU) compressor. However, smaller loss of power and efficiency may be achieved with electrical supply of ASU. An application of oxy-fuel process to power plant will cause a decrease of gross efficiency in power unit by 12% points by using steam from ILS and 11% points by using electric motor for driving ASU. Profitability of oxy combustion technology will be achieved when the CO2 emissions price reaches a minimum of 52 Euro/EUAs.