Study On Dry Removal Of Acidic Components In Blast Furnace Gas By Al₂O₃-loaded Deacidification Agent

Due to many advantages of saving water,making full use of sensible heat and high power generation under residual pressure,dry dust removal technology of blast furnace top gas has become the first choice of gas purification technology.However,the corrosion problem caused by acid components in dry dedusting gas limits the application of this technology.Adhering to the advantages of dry dust removal,how to remove acidic corrosive components such as HCl,H₂S,COS in gas is a key issue to be solved.In this paper,the deacidification agent was prepared by impregnation method with activated Al₂O₃ as the matrix material to load the active components.The loaded active components have the dual functions of removing HCl,H₂S and hydrolyzing COS to H₂S.The dachlorination and desulfurization reaction rules of different active components supported by Al₂O₃ were studied systematically,and the synergistic reaction mechanism and effect of simultaneous dachlorination and desulfurization were further discussed.The purpose of this study is to explore a feasible technical path for dry deacidification of blast furnace gas,and to lay a theoretical and technical foundation for thoroughly solving the corrosion problem caused by acidic components in dry dedusting gas and promoting the popularization and application of dry dedusting technology.The main conclusions of this paper are as follows:(1)According to thermodynamic analysis,Na₂CO₃ and CaO were selected as active components to prepare deacidification agent.Activated Al₂O₃ as a carrier of deacidification agent is a mesoporous material and has a complex pore structure.After550?roasting pretreatment,the specific surface area decreased and the average pore diameter increased.The load forms of Na₂CO₃ and CaO on the surface of activated Al₂O₃ were uniformly distributed in an amorphous form without forming a crystal structure.(2)Separate dechlorination experiments on Al₂O₃ loaded with different active components obtained the following results.The dechlorination efficiency of Na₂CO₃and CaO were more than 99%,and the dechlorination breakthrough time and penetration chlorine capacity of Na₂CO₃ were better than CaO.Pretreatment of activated Al₂O₃ improved the dechlorination performance of the deacidification agent,and the best dechlorination effect was obtained when the pretreatment temperature was550?.The dechlorination performance of deacidification agent gradually became stronger with the increase of Na₂CO₃ load,and the growth trend tended to be gentle when Na₂CO₃ load was 15 wt%.The breakthrough time of the deacidification agent gradually decreased with the increase of the temperature,and the maximum penetration chlorine capacity was obtained at 150?.The breakthrough time of the deacidification agent decreased sharply with the increase of space velocity,and the maximum penetration chlorine capacity was obtained at 6000 h^-1.The dechlorination efficiency of the deacidification agent above 99%after regeneration for 2 times,and the dechlorination performance gradually decreased with the increase of regeneration times.(3)The study of the separate desulfurization reaction of Al₂O₃ loaded with different active components obtained the following results.The highest H₂S and COS removal efficiency of Na₂CO₃ and CaO in blast furnace gas were more than 99%.The H₂S removal performance of CaO was better than Na₂CO₃,but the COS hydrolysis performance was worse than Na₂CO₃.With the increase of the Na₂CO₃ load,the H₂S removal performance of the deacidification agent gradually became stronger,and the COS hydrolysis performance was firstly enhanced and then weakened,and the best Na₂CO₃ load was 15 wt%.The desulfurization performance of deacidification agent gradually improved with the increase of temperature and decreased with the increase of humidity.(4)The research on simultaneous dechlorination and desulfurization by Al₂O₃supported active component obtained the following results.The best removal efficiency of the deacidification agent for HCl,H₂S and COS were more than 99%,which has the industrial feasibility of synergistic deacidification of blast furnace gas.The breakthrough time of H₂S and COS of deacidification agent was 240 min and 220 min,the penetration sulfur capacity was 0.51%.The deacidification agent had a breakthrough time of 24 h for HCl,and the penetration chlorine capacity was 6.4%.H₂S affected the forward progress of the COS hydrolysis reaction,resulting in a serious decrease in the hydrolysis performance of the deacidification agent.The hydrolysis of COS at the alkaline center on the surface of the deacidification agent affected the formation of Na₂S,which leads to a decrease in the removal performance of the deacidification agent.The dechlorination product Na Cl preferentially occupied the pore structure on the surface of the deacidification agent in the form of blocks,so as not to affect the hydrolysis and removal of COS and H₂S on the surface other than the pores of the deacidification agent.Therefore,HCl did not affect the desulfurization performance of the deacidification agent.The Na₂S product layer formed by the hydrolysis and removal of COS and H₂S on the surface of the deacidification agent affected the continuous growth of the bulk dechlorination product Na Cl,so the dechlorination performance of the deacidification agent was seriously reduced by the influence of sulfur gas components.