高浓度乙烯精馏塔灵敏板选择的动态模拟研究

Study on sensitive tray selection in high-concentration ethylene distillation column through dynamic simulation

合成醋酸乙烯的钯金催化剂易发生CO中毒失活,因此原料乙烯中CO的含量需保持在较低的水平(≤4.5×10^(-6))。通过乙烯脱轻塔可以将高浓度乙烯(>98 wt.%)中的少量轻组分杂质(CO,CH_4,H_2等)进一步脱除,达到所要求的标准。使用Aspen Plus软件对该塔进行严格模拟,在对脱轻塔进行控制方案选择时,由于塔内温度差较小,灵敏板的选择比较困难。根据稳态下的常用方法,初步筛选出3种不同的控制方案,分别选择不同的理论板作为灵敏板。再将流程导入Aspen Dynamics软件中,改变进料组成,对3个方案进行动态操作检验,结果表明第33块理论板更适宜作为乙烯脱轻塔的灵敏板。该方法利用了动态模拟手段对稳态模拟的结果进行优化筛选,模拟结果对其他高浓度精馏塔灵敏板的选择也有所借鉴。

The Pd-Au catalysts used in vinyl acetate synthesis tend inactivated. To avoid that phenomenon, the raw ethylene flow should to be easier to adsorb CO rather than ethylene, and then could get obtain trace CO （〈4.5 x10^-6）. The de-light fractionator was utilized to eliminate light impurities from high concentration raw ethylene flow （〉98 wt. %） to meet the requested target. Aspen Plus was employed to do rigorous simulations on the column due to its complete and powerful functions. Unfortunately, it was difficult to decide which tray was the sensitive tray since the traditional methods which based on steady-state simulation were not quite appropriate for this kind of high-concentration columns. To deal with that situation, first, 3 different control structures were explored from the traditional methods, and then the process was exported to Aspen Dynamics to do more detailed researches. The processing ratings were carried out by changing the feed flow concentration through the dynamic simulation. As shown in the results, No. 33 theoretical tray is more suitable as the sensitive tray in the de-light fractionator. The method applied in this paper introduced the dynamic simulation into the rating of a certain steady-state simulation and might be used for reference to similar processes.