Process Simulation And Performance Analysis For Two Kinds Of Pressurized Oxy-combustion Power Plant For Carbon Capture

Researches have indicated that under current available technologies of Oxy-combustion power plant for carbon capture, low efficiency and prohibitively high cost are still main barriers for achieving its further commercialized development. As a result, pressurized oxy-combustion system has been proposed for increasing efficiency by recovering more and high quality latent heat in the flue gas moisture. Nowadays, there are two major process designs for pressurized oxy-combustion system: pressurized oxy-coal combustion system(POCC) and staged pressurized oxy-combustion system(SPOC). However, current researches on process simulation and performance analysis for pressurized oxy-combustion system weren't undertaken under the uniform standard compared with the first generation oxy-combustion system, which resulted in a less reference result for efficiency improvements.In this work, the processes of a 600 MW supercritical with single reheat power plant using first generation oxy-combustion system without heat integration(Base Case) and with heat integration(Case A) were simulated on Aspen Plus and verified the accuracy of the performance results. The results indicated that the net efficiency of Case A is 9.36 percentage points less than that of a conventional air-fired system without carbon capture. Case A was chosen as a comparative base to evaluate the performance of POCC system and SPOC system later.On condition that parameters which are not intrinsically related to pressurized oxy-combustion concept, such as thermal parameters and equipment efficiency, remain the same as those in Case A, the processes of POCC system and SPOC system were simulated and compared with foreign researches. The results show that the gross efficiency of POCC system is 1.12 percentage points more than Case A while the net efficiency is just 0.47 percentage points more than base, which is limited. Foreign research obtain higher net efficiency for not taking other energy consumptions such as coal milling into consideration. For SPOC system, the gross efficiency is 1.78 percentage points more than Case A while the net efficiency is 2.4 percentage points more than base, which is considerable. Foreign research obtain much higher efficiency improvements due to SPOC concept because it underestimated the efficiency improvements due to parameter settings such as turbine efficiency, oxygen generation energy consumption, and condenser pressure between SPOC process and its base case.