基于Aspen Plus的气分装置建模与优化

Modeling and Optimization of Gas Fractionation Unit based on Aspen Plus

为将某气分装置丙烯纯度由95.2%提高至98%以上,采用Aspen Plus流程模拟软件建立了气分装置三塔流程模型,模拟结果可知,装置在当前工况下丙烷/丙烯分离塔板效率仅为54%,水力学计算表明该塔中下部塔盘液泛因子大于1,存在液泛可能。针对存在问题利用模型模拟了丙烷/丙烯分离塔的操作优化方案和停车改造方案,操作优化方案将丙烷/丙烯分离塔的进料板位置由第162块调整至第142块,回流比调整至15.7,最终产品丙烯的物质的量含量由95.2%升高至98.7%;停车改造方案模拟结果显示,将丙烷/丙烯分离塔板间距增大到550mm,塔内最高液泛因子低于0.85,丙烯物质的量含量将提高至99.1%。此外,企业尚有一套低负荷运行的两塔流程气分装置,模拟计算表明,将三塔流程中脱乙烷塔的塔底馏出物抽出20%至两塔流程的丙烯精制塔,降低三塔流程中丙烷/丙烯分离塔负荷,可在保证丙烯总产出不变的情况下将丙烯产品的物质的量含量提高到99.9%。

In order to increase the propylene purity of a gas fractionation unit from 95.2%to above 98%,a three-tower process model was established for the gas fractionation unit by using Aspen Plus process simula-tion software.The simulation results showed that the tray efficiencyof propane/propylene separation tower in the unit was only 54%under the current workingconditions,and the hydrauliccalculation showed that the flooding factor of the trays in the middle and lower part of the tower was greater than 1,indicating the pos-sibility of flooding.To solve these problems,the model was used to simulate the operation optimization scheme and modification scheme for propane/propylene separation tower.In the operation optimization scheme,the posi-tion of the feed tray in propane/propylene separation tower was adjusted from the 162^(nd) to the 142^(nd),the re-flux ratio was adjusted to 15.7,and the molar content of final propylene product was increased from 95.2%to 98.7%.The simulation results of the modification scheme showed that the maximum flooding factor in the tower will be lower than 0.85 and the molar content of propylene will be increased to 99.1%by increasing the tray spacing in propane/propylene separation tower to 550mm.The company also has a two-tower gas fractionation unit operating at low load.The simulation calculation showed that the molar content of propylene product can be increased to 99.9% without changing the total propylene output by pumping 20%of the bot-tom distillate from the deethanizer in three-tower process to the propylene refining tower in two-tower pro-cess and reducing the load of propane/propylene separation tower in three-tower process.