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对二甲苯(PX)是石油化工生产中的重要基本原料,来源于混合二甲苯。高纯度对二甲苯的分离方法主要有深冷结晶法、络合分离法、吸附分离法、共晶、磺化等,工业上采用的大多为吸附分离法。中国石化共有10套生产对二甲苯的装置,均设有吸附分离单元,大部分采用UOP公司的PAREX工艺技术。通常,为保证产品质量,装置操作往往偏于保守,操作方法以及操作参数设置不甚合理,过分离现象普遍存在,导致装置能耗增加。模拟移动床吸附分离设备的操作尚存在解吸剂用量大、公用工程消耗高、对二甲苯收率低等问题。采用Aspen Chromatography和Aspen Plus流程模拟软件,对芳烃联合装置中芳烃吸附分离单元,主要包括吸附塔、抽余液塔、抽出液塔和产品塔进行模拟,通过模型对过程关键参数如回流比、塔底热负荷、塔顶采出量等进行综合分析,在各塔产品控制指标达标前提下,选择最优的操作参数,以降低装置能耗,提升装置经济效益。
Paraxylene (PX) is an important basic raw material in petrochemical production, derived from mixed xylene. High purity p-xylene separation methods are mainly cryogenic crystallization, complex separation, adsorption separation, eutectic, sulfonation, etc., mostly used in the industry for adsorption separation. Sinopec has 10 sets of facilities for the production of para-xylene. Both units are equipped with adsorption separation units, most of which use the PAREX technology of UOP Company. Usually, in order to ensure the quality of the products, the operation of the apparatus is often conservative, and the operation method and operation parameters are not set properly. The over-separation phenomenon is ubiquitous, resulting in the increase of the energy consumption of the apparatus. Simulated moving bed adsorption separation equipment operation there is still a large amount of desorbent, utilities, high consumption, low p-xylene yield and other issues. Adopting Aspen Chromatography and Aspen Plus process simulation software, aromatics adsorption separation unit in aromatics complex unit, including adsorption tower, raffinate tower, extraction liquid tower and product tower were simulated. Through the model, the key parameters such as reflux ratio, Bottom heat load, top of the tower and so on a comprehensive analysis of production, control standards in the tower under the premise of product quality control, select the optimal operating parameters to reduce energy consumption devices and improve the economic efficiency of the device.