降膜结晶分离提纯对二甲苯  

Separation and Purification of p-Xylene by Falling Film Crystallization

作　　者：王瑞[1] 许妍霞[1] 宋兴福[1] 吴非克 于建国[1] WANG Rui;XU Yanxia;SONG Xingfu;WU Feike;YU Jianguo(National Engineering Research Center for Integrated Utilization of Salt Lake Resources, East China University of Science and Technology, Shanghai 200237, China;Changzhou Ruihua Chemical Eng & Tech Co. Ltd, Changzhou 213000, Jiangsu, China)

机构地区：[1]华东理工大学国家盐湖资源综合利用工程技术研究中心,上海200237 [2]常州瑞华化工工程技术有限公司,江苏常州213000

出　　处：《华东理工大学学报（自然科学版）》2019年第4期528-533,共6页Journal of East China University of Science and Technology

基　　金：上海市优秀学术/技术带头人计划资助(18XD1424600)

摘　　要：降膜结晶是一种重要的对二甲苯提纯方式.以含有75%(质量分数)对二甲苯的混二甲苯为原料,研究降膜结晶分离提纯对二甲苯过程,考察挂膜、进料速率、预冷温度、结晶温度、降温速率等工艺条件对结晶过程的影响,以及发汗终温、升温速率对发汗过程的影响.研究结果表明:当结晶条件为挂膜、进料线性喷淋密度360.53 mL/(m·min)、预冷温度25℃、结晶温度15℃、降温速率0.15℃/min时,以及发汗条件为升温速率1℃/min、发汗终温10℃时,可获得纯度高于99.50%的对二甲苯产品.Falling film crystallization is an important way to separate and purify p-xylene. Presently, p-xylene is mainly produced by toluene disproportionation technology, toluene methanol alkylation technology, benzyl alcohol alkylation technology and so on. However, all the products produced by these processes are a mixture containing o-xylene, m-xylene and p-xylene, with a mass fraction of p-xylene of more than 70%. It is difficult to separate and get high purity p-xylene by distillation because of their comparable melting points. Therefore, it is necessary to develop a low-cost and high-efficiency approach for p-xylene separation. In this paper, falling film crystallization was used to separate and purify p-xylene from mixed xylenes with high concentration of p-xylene (mass fraction 75%). Based on the growth rate, recovery rate and purity of p-xylene crystal layer, the effects of the hanging film, feed rate, precooling temperature of raw material, and crystallization temperature and cooling rate on the crystallization process were studied. Moreover, the effects of heating rate and terminal temperature of sweating on the sweating process were investigated as well. The key parameters of the falling film crystallization were provided for the industrial optimization. The experimental results suggested that the optimal crystallization conditions were hanging film, spray density of feed rate of 360.53 mL/(m·min), precooling temperature of raw material of 25 ℃, crystallization temperature of 15 ℃ and cooling rate of 0.15 ℃/min. And the optimal sweating conditions were heating rate of 1 ℃/min and end temperature of 10 ℃. As a result, the p-xylene product with purity of higher than 99.50% was obtained. The results can be benefit for the fundamental studies of industrial scale-up and process design.

关 键 词：对二甲苯 降膜结晶 分离提纯 工艺优化 

分 类 号：TQ026.7[化学工程] TQ241.1