Regeneration Fixed Bed Dynamics Of Cerium Oxide High-Temerature Coal Gas Desulfurization Sorbent

Coal occupies an important position in China’s primary energy source. However, the utilization rate of coal is very low, and there are serious pollution problems, so the clean utiliaztion of coal has become important. Integrated gasification fuel cell power generation (IG-FC) technology is the advanced and efficient coal conversion technology, and the removal of sulfur compounds is a very important issue in this processe. High temperature gas desulfurization technology can take advantage of gas sensible heat, so it is widely used. This technology on the desulfurization agent has a relatively high standard. The sorbents are not only efficient desulfurization, but also can be regenerated, which can suffer multiple times on recycling. Therefore, the study of the regeneration of high temperature gas desulfurization sorbent is very important.This study researched the fixed bed dynamic behavior of cerium oxide high temperature gas desulfurization sorbent under the atmosphere of O2, SO2 and O2-SO2 respectively. Gas concentration during the reaction can be detected by an oxygen analyzer and iodometry. Using sulfur analyzer tests the sulfur content of sorbent in the bed. The effects of gas concentration, regeneration temperature on the fixed bed dynamic behavior of sorbent are studied. According to the experimental results, the height and movement speed of regeneration zone are calculated. And a mathematical model simulation was used to analyze the experiment results, and then the model was corrected.The results showed that regeneration conversion curve of cerium oxide sorbent at different locations can be considered as an inverted S-type curve, and it maintains a substantially constant speed to move toward the exit under O2 atmosphere. With the increase of O2 concentration, movement speed of regeneration zone increased and length of the regeneration zone reduced slightly. Cerium oxide sorbent regenerated under the atmosphere of O2, which controlled by the chemical reaction at first, and then it converted to diffusion control. The formula of chemical reaction control stage is as follows:The formula of diffusion control stage is as follows:Movement speed of regeneration zone increased and length of the regeneration zone becomes remarkably shorter with increasing regeneration temperature. The reaction is controlled by the chemical reaction at first, and then it converted to internal diffusion control-oriented. Reaction is shifted from chemical reaction control to diffusion control, and the formula is as follows:The results showed that regeneration conversion curve of cerium oxide sorbent at different locations can be considered as an inverted S-type curve, and it maintains a substantially constant speed to move toward the exit under SO2 atmosphere. With the increase of SO2 concentration, movement speed of regeneration zone increased and length of the regeneration zone reduced. While the SO2 concentration is very low, the regeneration conversion curve changes slowly at the end of regeneration zone. The reaction is controlled by the chemical reaction at first, and then it converted to diffusion control. The formula of chemical reaction control stage is as follows:The formula of diffusion control stage is as follows: Movement speed of regeneration zone increased and length of the regeneration zone becomes remarkably shorter with increasing regeneration temperature. And the reaction is controlled by the chemical reaction at first, and then it converted to internal diffusion control-oriented. Reaction is shifted from chemical reaction control to diffusion control, and the formula is as follows:The regeneration conversion curve of cerium oxide sorbent can be considered as an irregular inverted S-type curve under O2-SO2 mixed atmosphere. With the extension of reaction time, small platform appears on the curve. Movement speed of regeneration zone increased and length of the regeneration zone becomes shorter with increasing import gas concentration and regeneration temperature. The platform on the curve moves down as the temperature rises, and the platform disappeared at 750℃.