Experimental study on the mechanism of SO2 emission and calcium-based desulfurization in the coal oxygen-enriched combustion

Full text: The emission of SO2, CO2 brings serious harm to the ecological environment, human health and the global climate change. The largest source of SO2, CO2 is the combustion of fossil fuels for power generation. So developing the new technology for controlling pollutants emissions from coal combustion was imperative. Oxygen-enriched combustion technology is such a new technology which can realize CO2 zero emission, enhance the combustion efficiency and reduce pollutants emission. Due to the high concentration of CO2, it has many different aspects in the SO2 emission and calcium-based desulfurization compare with the conventional combustion. In this article, experiments have been done to investigate the behavior and mechanism of SO2 emissions and removal in oxygen-enriched combustion. First, in TGA and fixed bed reactor, the SO2 emission characteristics were investigated under various bed temperature, particle size and O2/ CO2 concentration. It was observed that SO2 released faster and the emission peak was higher than air atmosphere. SO2 emission concentration increased with the reaction temperature increasing. Simultaneously, the mechanism of SO2 emission was obtained by analyzing the sulfur compounds in the gas products and solid products in different reaction times. Then, the impacts of reaction temperature, particle size, O2/ CO2 concentration and SO2 concentration etc. on the efficiency of SO2 removal were analyzed. The phase analysis, pore diameter distribution and microstructure of the solid product were investigated. The experimental results showed that the sulphur capture takes place by direct sulphation reaction at high CO2 concentration which attributes to light sinter, better porous structure, higher optimal desulfurization temperature and high desulfurization efficiency of calcium-based sorbent. (author)