Research And Engineering Application Of Organic Waste Gas Treatment Technology In Polypropylene Production

Volatile organic compounds(VOCs)in the tail gas of traditional polypropylene production process pollute the environment seriously in some areas and pose a great threat to human health.Therefore,this paper aims to study and improve the tail gas treatment technology in polypropylene production.Firstly,using 1-butene as the probe molecule,the process routes of washing absorption method to remove the soluble organic components in the front section and adsorption method to treat the olefin waste gas were selected.ZSM-5 was selected as the best adsorbent for small olefin adsorption by experimental screening and evaluation,its morphology and chemical composition with different Si-Al ratios were investigated.Secondly,the optimum conditions for adsorption of 1-butene on ZSM-5 zeolite were determined as follows:Si/Al ratio of 40,relative humidity of 70%,temperature of 50?,space velocity of 6000 h-1.The desorption stage showed that at 160?,hot nitrogen desorption and desorption cycles for 5 times,still maintained a good adsorption performance of 1-butene.On the basis of laboratory experiments,zoom in to the side line device.As a result,in the side line experiment,the adsorbent was magnified 1000 times,the adsorption wind speed was controlled between 3000-9000 h-1,the side line equipment was operated safely up to the standard for 3000 hours,and the exhaust gas outlet concentration was always lower than 5ppm.It is further proved that molecular sieve adsorbent has excellent adsorption performance for small olefin,which provides reliable experimental and theoretical data for industrial treatment of waste gas in polypropylene production.Finally,according to the small test and side line data and on-site process parameters,the complete process flow in the actual engineering application is determined,and the scrubber column,fan,circulating water pump,mist eliminator,nitrogen heater,nitrogen storage tank and other equipment are successfully selected.The water-soluble alcohols and ketones in the exhaust gas are removed by washing process,and the insoluble olefin is adsorbed in the adsorption section.Using the method of two suction,one removal and one waiting,the amount of adsorbent in each tank is 7 cubic meters.The organic matter discharged from the multi-component polypropylene unit is successfully treated,which makes the total non-methane hydrocarbon discharge meet the standard,and greatly reduces the pollution of organic matter to the environment.The tail gas treatment facility in the downstream of the polypropylene unit of a large refinery has high safety,high automation degree and certain demonstration effect.