多效精餾烷烴混合物的Aspen Plus模擬分離

精餾是石油化工能耗最大的單元操作之一，因此對其過程的節能研究非常重要。本文利用Aspen Plus化工模擬軟件中的RADFRAC模塊和PENG-ROB熱力學計算模型，系統模擬了多效精餾順流(DQF、IQF)、逆流(DQB、IQB)及常規精餾(DQ、IQ)的烴類混合物異丁烷/正丁烷/正己烷的分離。根據各組分的分離要求，通過靈敏度分析優化各工藝參數；同時比較了各精餾構造的有效能損失和熱力學效率，并計算了它們的年度總費用(TAC)。結果表明：與間接精餾方案IQ相比，精餾方案IQF、DQB、DQ分別節能20.6%、16.0%、8.4%；熱力學效率方面，多效精餾IQF為19.6%，DQB22.2%，普遍比常規精餾的DQ10.0%、IQ10.3%要高；至于年度總費用(TAC)，相比于IQ,DQB多耗資12.1%，而IQF、DQ少耗資9.0%和8.7%。綜合節能效果、熱力學效率、年度總費用得知，IQF這種多效精餾方案最優。
Distillation is one of the most energy intensive unit operations in chemical industry and petroleum, so it is very important to study energy-saving of distillation process. In this paper, simulations of multi-effect forward-feed(DQF, IQF), multi-effect backward-feed(DQB, IQB) and conventional distillation configurations(DQ, IQ) has been studied for ternary hydrocarbon mixture(iC₄/nC₄/nC₆) separation on Aspen Plus software, in which RADFRAC block and PENG-ROB physical property set are used. After process parameters were optimized through sensitivity analysis, the energy-saving principles were discussed and thermodynamically analyzed. Meanwhile, exergy loss and thermodynamic efficiency were compared. What’s more, the proposed configurations were compared based on total annual cost(TAC) as the economic objective function. Results indicate that IQF, DQB, DQ of distillation can respectively save energy 20.6%, 16.0% and 8.4%, as compared with conventional distillation(IQ), their thermodynamic efficiencies are separately 19.6% for IQF and 22.2% for DQB, which are much higher than that of DQ(10.0%) or IQ(10.3%). For total annual cost(TAC), compared with IQ, capital outlay of DQB is 12.1% more, but IQF, DQ can save total annual cost(TAC) by 9.0% and 8.7%. Therefore IQF is the best distillation configuration considering the factors of energy-saving, thermodynamic efficiency and total annual cost(TAC). Copyright © 2011 中國科學院過程工程研究所.