| Acetic acid is a volatile organic monoacid,and it is an important chemical raw material.In the production process of industrial and mining enterprises,because of the poor equipment sealing,backward technology,no organization emissions,etc.,exhaust emissions are not up to the national standard which will cause a certain degree of pollution to the environment.It leads to atmospheric pollution,water pollution,it also poses a certain threat to the health of residents.Furthermore,it also has some adverse effects on microorganisms.The industrial cost of acetic acid is not cheap,and it is also a waste if which is discharged directly with the tail gas.If the emission concentration is too high,there will be not only environmental problems,which is not conducive to occupational health,but also some safety risks.At present,there are few studies on the treatment of acetic acid in tail gas in domestic literature,especially on the treatment of acetic acid in tail gas by chemical simulation.In this thesis,Aspen Plus is used to check the pall ring packing absorber which is used to absorb the acetic acid emissions.The sensitivity of feed parameters such as flow rate,temperature and operating pressure in the absorber was analyzed respectively.It is concluded that the design capacity of the current pall ring filled absorber is insufficient to meet the national standard of 120 mg/m~3 emission.By means of QC,the causes of acetic acid content in the exhaust gas of absorption tower exceeding the standard were analyzed and found from five aspects of man,machine,material,method and environment,and several important factors were finally determined.The pall ring bulk packing is not suitable for the design,and the high temperature of the mixed gas in the tower is another main reason.In this study,countermeasures were developed for the key factors.By comparison of selection,the absorption effect of BX500 type wire mesh packing was simulated with Aspen Plus.The number of theoretical plates per meter of BX500 type packing was 4,and the height of effective packing layer was 6 m.The inlet gas pressure is 100.625k Pa(absolute pressure),the pressure drop is 1.2 k Pa,and the operating pressure is99.425 k Pa(absolute pressure).Parameters were entered for simulation,and the simulation results show that the exhaust acetic acid content can meet the requirements of the national standard.After the bulk packing replaced by BX500 type wire mesh packing,the measured acetic acid content in tail gas can be controlled at about 75mg/m~3.With the attitude of being responsible to the society,the team self-pressurized and proactively comply with the pollutant emission standard of Shanghai at 80 mg/m~3.The team improved the number of liquid distribution points in the liquid distributor in the absorption tower.At the same time,the team considered the spraying requirement for the BX500 packing,at least 200 points/m~2.After two times of improvements,the modified packing absorber achieved the emission level of 60±2.8 mg/m~3 containing acetic acid.Combined with a three-compartment RTO device,the total hydrocarbon content of non-methane in tail gas oxidized by 3-compartment RTO can be controlled at the level of 5 mg/m~3.The acetic acid recovery rate was increased.It can produce the economic benefit of 50 thousand RMB every year.It can be seen from the simulation results and the actual operation that structured packing has better absorption effect than that of bulk packing in absorption tower,and Aspen Plus chemical process simulation software has certain reference value for simulation calculation of absorption tower,and can be used to guide engineers to improve and optimize the process. |
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