Coal based power plants using oxy-combustion for CO_2 capture: Pressurized coal combustion to reduce capture penalty

摘要

The goal of this paper is to design and study a new variation of an oxy-combustion coal based power plant with CO_2 capture. This variation employs a pressurized coal combustor that burns coal in an oxygen rich environment. The concept is compared with an atmospheric pressure oxy-combustion power plant (baseline case). Such analyses would provide us with information regarding potential heat integration and improvement opportunities of oxy-combustion coal based power plants. Also, this study highlights the efficiency improvement potential of the oxy-combustion technology for coal based power plants. The power cycle presented in this paper is a supercritical cycle that has a gross electric power output of 774 MW for the baseline case and 792 MW for the pressurized case. The auxiliary power consumption is reduced from 224 MW in the baseline case to 214 MW in the pressurized case due to the absence of air leakage into the boiler. The recovery of latent heat from the flue gases is increased due to the elevated dew point in the pressurized case. This results in a net LHV and HHV efficiency improvement of 1.7 percentage points each over the baseline case. In both the cases, over 90% of the produced CO_2 is captured and compressed to 110 bar after removal of volatiles and other pollutants such as SO_x and NO_x.