Study On The Boiling Chlorination Process Of Chlorobenzene

Coking benzene and chlorine which is used as raw materials in the20000tons/aboiling chlorination process of Tianjin Botian Chemical Co.,Ltd. are reacted in thechlorination reactor to produce chlorine solution which contains chlorobenzene,dichlorobenzene and remained benzene. The product chlorobenzene is obtained afterchlorine solution is neutralized and distilled. Byproducts o-dichlorobenzene,p-dichlorobenzene are obtained at the same time. Tail gas of chlorination reaction isabsorbed by fresh water or washing wastewater to form31wt%hydrochloric acidsolution. The process is mature both at home and abroad, but further saving energyand decreasing consumption is still possible. Based on the analysis the presentprocess, the safety and environmental issues have been solved by optimizing theprocess, the economy profit and the technology of the production unit have beenimproved.By discussing the process calculation and process, the actual problems of thedevice operation were analysed, and compared with the actual working conditions.This thesis discussed the changes of main parameters of the process, laid thefoundation for process optimization.The reactant ratio, driving operation and process control, chlorination reactor’sstructure and supporting facilities have been optimized in the chlorination process.The π shaped liquid seal optimized washing neutralization process and improved theseparation effect. Distillation steam and exhaust water preheating chloride solutionand recycling the circulating cooling water, reducd the unit steam consumption andwater consumption. Absorbent replacement, cooling temperature decrease and heatexchange area increases, the three methods have improved the falling filmabsorption process. To control the combustible gas with two series liquid seal,adiabatic absorption tower and the falling film absorber combination to fully absorbHCl, adding buffer tank, adding dilute acid cooler, lower desorption tower, recyclinghydrochloric acid, the six methods have optimized the hydrochloric acidabsorption-desorption process.Practice has proved that Botian’s chlorobenzene process device had reached thedomestic advanced level. By finished process optimization, benzene consumptiondecreased from728kg/t to718kg/t, steam consumption decreased from1.7t/t to1.2t/t,water consumption decreased from2t/t to1.3t/t. Chlorobenzene’s by-product hydrochloric acid yield increased by10%,and desorption rate reached90%.Thesafety risk of the process has been reduced, both the number of air pollutants andbenzene and acid containing wastewater were all decreased. And costs of equipmentmaintenance was saved.