Study On Removal Of H₂S From Coal Gas With Wet Oxidation Method By High Gravity Technology

As a high heating value of fuel gas, coal gas is widely used in industrial heating furnace. H2 S in coal gas not only affects the quality of the products, but also harms to the equipment and the environment, so the removal of H2 S from the coal gas is a very important process. The wet oxidation method is widely used because of its wide scope and high efficiency in many desulfurization technologies. Desulfurization in packed absorption tower tends to clog equipment and increases operating costs because of its large amount of liquid circulation, long gas-liquid contact time and many side effects that. It is a great significance to seeking a new desulfurization equipment and technology for reduce the cost of coal gas desulfurization. High gravity technology has the advantage of high mass transfer efficiency and short gas-liquid time, it may solve the desulfurization of low selectivity, poor mass transfer effect, more side reactions and other problems for desulfurization of coal gas containing H2 S, CO2.In this paper, we built the wet oxidation desulfurization equipment of coal gas containing H2 S, CO2 and analysis absorption reaction characteristics of H2 S and CO2 in the process. On the basis, it discusses the basic and applied research of process of absorption and regeneration. It studies on the changes relationship between coal gas desulfurization process of desulfurization, selectivity, regeneration rate and all operating parameters which are liquid-gas ration, high gravity factor, gas-liquid residence time and regeneration time. These studies provide a theoretical basis and reference for industrial amplification and optimization.This paper measures the reaction rate constant of Na2CO3 and H2 S, CO2 using conductivity under normal temperature and pressure and studies its chemical activity in the absorption process. Results showed that the reaction rate of Na2CO3 and H2 S is 500 times for CO2. There is an obvious difference about chemical activity of both acid gas in the process where is with weak base reactions.The desulfurization of high gravity experiment which processes the simulated furnace coal gas of N2, H2 S and CO2 proceeds using the chemical characteristics differences of H2 S and CO2 in the 0-8 m3/h scale by wet oxidation. Results showed that the desulfurization rate increases with concentration of Na2CO3, high gravity factor, the ratio of liquid to gas and gas-liquid contact time. The selectivity decreases with concentration of Na2CO3, gas-liquid contact time, liquid-gas ratio. It first increases and then decreases with high-gravity factor. The experiment determines the operating parameters are high gravity factor 94, Na2CO3 concentration 12 g/L, gas-liquid contact time 0.2s, liquid-gas ratio 20 L/m3. The desulfurization rate is 95% and selectivity factor is above 35 under this process. On the same scale, the absorption of CO2 concentration in rotating packed bed is only 1/20 what is in packed column when desulfurization rate is 93%. The experiment shows that rotating packed bed has advantages in selective desulfurization.Based on the wet air oxidation regeneration theory, the experiment builds high gravity method device on the 0-100 L/h scale. Result shows that the suit regeneration process parameters are liquid-gas ratio 8 L/m3, high gravity factor 60, regeneration time 16 min in the experimental range. The recycling rate of a single rotating packed bed regenerates 16 min is up to 70%. On the same scale, the desulfurization solution regeneration of rotating packed bed increases 13% than packed tower.The result of this paper shows that the high gravity wet oxidation desulfurization technology qualifies high efficiency, small liquid circulation, high selective desulfurization, short gas-liquid contact time and high regeneration efficiency. It has good potential for industrial application.