基于有机朗肯循环的混合二甲苯MVR热泵精馏工艺

MVR heat pump distillation process of mixed xylene based on organic Rankine cycle

常规机械蒸气再压缩(MVR)热泵精馏分离混合二甲苯工艺,存在压缩机电耗较大及塔顶压缩蒸气的显热未被利用等问题。有机朗肯循环(ORC)发电技术则可以将低温余热转化为电能以供压缩机使用,由此提出了ORC发电技术耦合MVR热泵和带乏汽回热循环(EGC)的ORC发电技术耦合MVR热泵两种精馏工艺应用于本体系的分离研究。以年总费用(TAC)和能耗为分离工艺的评价指标,系统净输出功和循环热效率作为ORC系统的评价指标,对以上两种耦合精馏工艺进行模拟与优化,并与常规MVR热泵精馏工艺进行比较与分析。研究结果表明,ORC发电技术耦合MVR热泵精馏工艺和带EGC的ORC发电技术耦合MVR热泵精馏工艺较常规MVR热泵精馏工艺均具有一定的节能和经济优势,可分别减少能耗9.64%和9.89%,节省TAC 3.19%和3.50%。

Conventional mechanical steam compression（MVR） heat pump distillation for separating mixed xylene exists shortcomings of high compressor power consumption and overhead sensible heat unused. Organic Rankine cycle（ORC） power generation technology can transform the low-temperature waste heat into electricity for compressor, in view of the above, the MVR heat pump distillation processes coupled by the ORC power generation technology and combined with exhaust steam regenerative cycle（EGC） were applied to separate the system. Taking total annual cost（TAC） and energy consumption as the evaluation indexes of separation process, net output power and cycle thermal efficiency are used as evaluation indexes of ORC system. Simulations for the above two kinds of distillation process were performed and the results were compared with the conventional MVR heat pump distillation process. The results show that compared with the conventional MVR heat pump distillation process,the MVR heat pump distillation processes coupled by ORC power generation technology and combined with EGC power generation technology both have certain energy saving and economic advantages, can reduce energy consumption by 9.64% and 9.89%, and save TAC by 3.19% and 3.50% respectively.