Abstract: 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 15.31wt% 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.

Key words: MTO, mixed olefins, high value utilization, catalytic cracking, simulation optimization

摘要： 甲醇制烯烃(MTO)是生产乙烯和丙烯的重要方式之一，混合烯烃是MTO工艺的主要副产物。MTO副产C5+混合烯烃在国能新疆化工有限公司目前仅低值售卖，未得到有效利用。为探寻MTO副产C5+混合烯烃的高值利用途径，本工作对混合烯烃进行组成和物性测试，发现混合烯烃中C5~C8烯烃的含量在80wt%以上，此外还含有少量烷烃、芳烃和含氧化合物。利用固定床实验装置开展混合烯烃催化裂解实验，在0.1 MPa、620℃、质量空速3.53 h-1的条件下，乙烯和丙烯收率分别为15.31wt%和26.94wt%。结合MTO工业装置流程，本工作设计了混合烯烃催化裂解制乙丙烯的工艺流程，基于Aspen Plus软件进行流程模拟，并对能耗较高的精馏塔进行操作参数优化。发现凝液汽提塔最佳塔板数、进料位置和回流比分别为24, 12, 1.2，脱丙烷塔最佳塔板数、进料位置和回流比分别为20, 10, 0.4，脱乙烷塔最佳塔板数、进料位置和回流比分别为28, 9, 3.4，乙烯精制塔最佳塔板数、进料位置和回流比分别为50, 21, 7.5，丙烯精制塔最佳塔板数、进料位置和回流比分别为54, 29, 5.7，轻烃分离塔最佳塔板数、进料位置和回流比分别为12, 7, 0.8，最终得到产品纯度为99.9wt%的乙烯和产品纯度为99.6wt%的丙烯。经济潜力分析结果表明，与直接低值售卖相比，混合烯烃进行催化裂解所得产品收入为初始收入的1.3倍。

关键词: MTO, 混合烯烃, 高值利用, 催化裂解, 模拟优化