Research On Compressing Process And Desulfurization And Denitration Of The Flue Gas Of Oxyfuel Coal-fired Boiler

Oxyfuel coal-fired power generation technology is one of the new clean-coal technologies, which can capture vast amounts CO2and control the emission of pollutants. The technology has a wide potential in application. Some research on compressing process and desulfurization and denitration of the flue gas of oxyfuel coal-fired boiler, which are less involved in aspects of the previous research, has been done in this study.The research on compressing process of the flue gas CO2of oxyfuel coal-fired boiler and it’s compressing power consumption has been done. The results show that compressing of the flue gas of a300MW oxyfuel combustion plant under atmospheric pressure consumes a lot of electric energy, and the power consumption is about8%of the plant’s output power. However, the compressing power consumption of the pressurized oxyfuel combustion plant at the pressure of6-8MPa decreases dramatically, which is only0.1%-0.2%of the plant’s output power.Based on the basic principle of reaction kinetics and available experimental data, the calculation results show that NO and SO2transition time are only tens of seconds under the pressure of3MPa and the temperature of30℃, so the water absorption do not become control process and do not need any chemical catalytic additive.Based on the study of the reactions of desulfurization and denitration of the flue gas of oxyfuel coal-fired boiler, experimental study has been done on these reactions under high pressure and low temperature. The experiment results show that NO in oxyfuel flue gas can be converted to nitric acid effectively under high pressure and low temperature. The conversion rate of NO increases quickly under lower pressure (0.5MPa-2MPa), and the speed takes up the slack under higher pressure (2MPa-3MPa). In experiment of removing NO and SO2, nitric oxide reacts as catalyst, two reaction columns are needed to remove NO and SO2. The conversion rate of SO2in flue gas is about20%-40%, and increases with initial SO2concentration.At last, the model for simulation of NO and SO2absorption process is established and calculated using the software ASPEN PLUS. The calculation results are consistent with theoretical analysis and experiment results, the reaction time decreases sharply with the increase of pressure. A300MW oxyfuel combustion coal-fired boiler, when the concentration of SO2and NO of the flue gas are1500ppm and1000ppm, can retrieve4788kg/h sulfuric acid with a concentration of45%and 1044kg/h nitric acid with a concentration of17%, and it can produce48thousand Yuan a day, amount to ten million Yuan when the power plant operating5000hours a year.