Process simulation of catalytic cracking of C5+mixed olefins by-product of MTO to produce ethene and propene
Methanol to olefin(MTO)is one of the important ways to produce ethene and propene,and mixed olefins are the main by-products of MTO process.C5+mixed olefins by-product of MTO is currently sold at a low value in CHN Energy Xinjiang Chemical Company Limited,and has not been effectively utilized.In order to explore the high-value utilization way of C5+mixed olefins by-product of MTO,its composition and physical properties were tested.It was found that the content of C5～C8 olefins in mixed olefins by-product of MTO was more than 80wt％,in addition,a small amount of alkanes,aromatics and oxygen compounds were contained.The catalytic cracking experiments of mixed olefins were carried out on a fixed-bed experimental device.Under the conditions of 0.1 MPa,620℃,and mass space velocity of 3.53 h-1,the yields of ethene and propene were 15.3 1wt％and 26.94wt％,respectively.Combined with the process of MTO industrial plant,this study designed the process of mixed olefins catalytic cracking to produce ethene and propene,simulated the process based on Aspen Plus software,and optimized the operation parameters of the distillation column with high energy consumption.It was found that the optimal number of theoretical stages,feed stage and reflux ratio of the condensate stripping tower were 24,12,and 1.2,respectively;those of the depropane tower were 20,10,and 0.4,respectively;those of the deethane tower were 28,9,and 3.4,respectively;those of ethene refining tower were 50,21,and 7.5,respectively;those of propene refining tower were 54,29,and 5.7,respectively;and those of light hydrocarbon separation tower were 12,7,and 0.8,respectively.Finally,the product purity of ethene and propene reached 99.9wt％and 99.6wt％,respectively.The economic potential analysis results showed that compared with direct low value sales,the product income of mixed olefins catalytic cracking was 1.3 times of the original income.
MTOmixed olefinshigh value utilizationcatalytic crackingsimulation optimization
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