Study On Separation And Purification Of Electronic Special Gas From Desorption Gas Of Ammonia Synthesis In Coal Chemical Industry

Coal chemical synthetic ammonia is a process for producing ammonia with coal as raw material.The desorption gas is the tail gas discharged by the pressure swing adsorption device in the process of gas purification.Its main components are methane,hydrogen,carbon monoxide,carbon dioxide,etc.Because of its variable components and low calorific value,the desorption gas is usually discharged into the atmosphere or put into the boiler for combustion.The current utilization method is not only inefficient,but also causes a certain degree of pollution to the environment.With the increasing shortage of global resources,it is of great significance to study how to turn fuel into raw materials to achieve high-value clean utilization of cheap industrial exhaust gas.Electronic special gas is an indispensable raw material for semiconductor,integrated circuit,microelectronics,liquid crystal display,solar cell,optical fiber and other electronic industrial production.The general production process of electronic special gas is to use chemical reaction to produce industrial grade gas with low purity and more impurities,and then use adsorption,catalytic reaction,distillation and other methods to separate the impurities in the gas,and finally obtain high purity electronic special gas to meet the needs of the electronic industry.The production process is complex and the cost is high.It is urgent to explore a new process for preparing low-cost electronic special gas.In this paper,the tail gas(desorption gas)of synthetic ammonia in coal chemical industry is taken as the research object.Based on the principle of low temperature distillation,chemical absorption principle and solid adsorption principle,the process route of purification of electronic special gas by desorption gas is designed.Then the core process of low temperature distillation is modeled and calculated,and the process of separation and purification of electronic special gas by desorption gas is optimized.Finally,the process device is used to debug and produce qualified high purity carbon monoxide and high purity methane.The main research contents and conclusions are as follows :(1)According to the characteristics of desorption gas components and the requirements of electronic special gas,the cryogenic separation principle with more thorough separation and higher purity was selected as the core technology.Combined with molecular sieve adsorption dehydration and MDEA decarburization,the process of separation and purification of electronic special gas by desorption gas was innovatively designed.(2)Based on the PR physical equation and cryogenic distillation mechanism,Aspen Hysys software was used to model and calculate the cryogenic distillation purification process.The distillation process was optimized to reduce the energy consumption of the distillation process.(3)The results show that the flow change can be solved by adjusting the heat load of the distillation column in an equal proportion.The most important influence on the process is the change of the composition of the feed gas.The appropriate liquid nitrogen reflux can solve the influence of the change of the composition of the feed gas.(4)In this paper,combined with the actual situation of industrial production,an efficient comprehensive utilization method of desorption gas separation and purification is proposed.The hydrogen and nitrogen in the desorption gas are separated and purified as raw materials for ammonia synthesis.The carbon monoxide in the desorption gas is partially extracted as high-purity carbon monoxide of the electronic special gas.After partial separation and purification,it is returned to the changing section to participate in hydrogen production.After separation and purification,part of the methane in the desorption gas is used as industrial methane,and part of the distillation purification is used as high-purity methane of the electronic special gas.(5)In this paper,through the analysis of gas purification electronic special gas design process and device construction,successfully produced high purity methane with 99.9994 %purity and high purity carbon monoxide with 99.9995 % purity.