Analysis of sensitivity and optimization potential for oxy-fuel plant system

Abstract

A sensitivity analysis of net electric efficiency has been conducted to assess the performance of a purpose-designed 600 MWe supercritical oxy-fuel bituminous coal-fired power plant system with three recirculation models of flue gas using commercial software THERMOFLEX 23. To compare in a direct way, a new definition of “efficiency sensitivity” was introduced. The assessment was performed for 7 major operating parameters. It is suggested that air leakage acts as the most important impact factor on the performance of oxy-fuel system. The other factors are also influential including oxygen concentration from ASU, oxygen excess ratio, and gas leakage in gas preheater. Optimization, i.e., thermal integration, was also considered to minimize the energy loss of the oxy-fuel process. For the purpose of optimizing, the improvement of turbine system which utilizes the thermal energy of hot flue gas through heating feed water is also very important for oxy-fuel process. By heating the feed water at the outlet of the secondary feed water heater upstream of the deaerator, the rise of net efficiency of an oxy-fuel process can narrow the energy penalty relative to the air-firing system. With the proposed optimization potential ratio, (Formula presented) it was concluded that the power plant system of 600 MWe has lower optimization potential ratio than that of 300 MWe, which means that the power plant with higher capacity has lower improvement potential of net electric efficiency.