| In the FCC(catalytic cracking)catalyst production process,in order to adjust the pH of the reaction and improve the wear resistance of the catalyst particles,a double aluminum binder,namely an aluminum stone and an aluminum sol(aluminum chloride solution),is added during the gelation process.Among them,the aluminum stone needs to be acidified with hydrochloric acid,and then the molecular sieve slurry,kaolin and other raw materials are added for production.In the original production process,hydrogen chloride cannot participate in the reaction in the subsequent production of FCC catalyst.Hydrogen chloride is volatilized under high temperature roasting conditions,causing a large amount of hydrogen chloride gas to be entrained in the exhaust gas discharged from the FCC catalyst roasting process.The discharge temperature is high,the hydrogen chloride content is large,and the hydrogen chloride is directly The efflux will have a major impact on the environment.For this part of the hydrogen chloride emissions,most of the catalyst companies' existing treatment method is to treat the produced hydrogen chloride gas by alkaline washing.After washing with sodium hydroxide,sodium chloride wastewater will be produced.This part of sodium chloride The wastewater will go directly into the integrated wastewater treatment system.The content of sodium chloride in the wastewater is 15000mg/L~20000mg/L,which is one of the reasons for the excessive salt content in the discharged sewage.With the increasingly strict national environmental protection testing and environmental protection legislation,the discharge standards for salty wastewater will be introduced soon.How to deal with high-salt wastewater has become an important issue that enterprises urgently need to solve.In this paper,the source treatment and resource recycling process are innovatively proposed.First,the hydrogen chloride gas in the source can be directly recovered by the water absorption and absorption method to avoid the chloride ions entering the subsequent process and reducing the efflux of the salty wastewater.Second,the produced hydrogen chloride gas is dissolved in water to form hydrochloric acid,which can be recycled.In this paper,the engineering technology of chloride ion reuse in FCC roasting tail gas is studied.On the basis of the current first-stage quenching + secondary absorption of most catalyst manufacturers,the exhaust gas treatment technology of first-stage quenching + third-stage absorption is innovatively proposed,and the hydrogen chloride in the exhaust gas is discharged while the exhaust gas treatment reaches the standard discharge.Absorbing and thickening,making industrial hydrochloric acid with a concentration greater than 25% and returning it to the catalyst forming process,thereby achieving the purpose of reducing environmental pollution,recycling of chlorine ions,and improving product yield.In this paper,the current processing status of hydrogen chloride gas in the catalytic cracking catalyst roasting tail gas is determined.The process flow is determined and the key equipment is calculated.The mathematical model of the tower is established,and the exhaust gas composition is tested and analyzed.The absorption tower is the most important in the system.The equipment simulates the structure of the gas inlet of the absorption tower,simulates the flow field of the inlet structure,optimizes it,and compares and selects the most uniform gas inlet structure.Secondly,the strength ability of the absorption tower under the combined action of thermal load and mechanical load is studied,and compared with the actual experimental data.The simulated values agree well with the experimental values.This paper provides a theoretical basis for the industrial application of the recovery of hydrogen chloride in the catalytic cracking catalyst roasting tail gas,and provides new methods and new technologies for enterprises to achieve energy conservation,emission reduction and environmental protection. |
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