Abstract: The utilization of heat of reaction and energy optimization within ethoxylation reactive distillation(ERD)column,which involves reactions with highly thermal effect,was studied by using the mathematical model and simulation method.A typical ethoxylation system,the synthesis of ethylene glycol monobutyl ether(EGMBE)from ethylene oxide(EO)and n-butanol was employed as example. Firstly,the conventional column design,into which a reactive section was superimposed onto a stripping section,was used as a base case for analysis,and detailed simulations were carried out to investigate the influence of heat of reaction on the process performance.The results obtained showed that,by the adoption of the conventional design of ERD column,the heat of reaction was finally removed from condenser by cooling medium,i.e.,the heat of reaction could not be directly utilized in ERD column for improving the separation operation or reducing the heat duty of reboiler.Based on this,the approaches to utilizing heat of reaction was analyzed,and an internally heat-integrated ethoxylation reactive distillation structure,IHIERD,was proposed to maximize the energy efficiency of system,into which the reactive section and stripping section was partitioned into two parts with different operating pressures.In such arrangement,the heat of reaction can be allowed as heat resource to be drawn from reactive section to supply stripping section,and therefore the heat duty of reboiler in IHIERD can be reduced.The saving effectiveness of different designs was analyzed and compared by using simulations.The results obtained demonstrated that the IHIERD leads to a reduction of the reboiler temperature from 462.5 K to 420.0 K,a reduction of the heat duties of condenser and the total energy input by 11% and 14%,respectively,which indicated that the energy saving was obvious.

Key words: ethoxylation, reactive distillation, ethylene glycol monobutyl ether, reaction heat, internal heat integration

摘要： 以正丁醇和环氧乙烷为原料合成乙二醇正丁醚(EGMBE)为例,利用数学模型和模拟分析方法,研究了包含大量反应热效应的乙氧基化反应精馏(ERD)塔中反应热的利用及系统能量优化问题。研究表明,当采用常规的、将反应段直接叠加于提馏段之上的塔设计时,反应热并没有贡献于分离操作或减小再沸器的热负荷,而只是被冷凝器中的冷却介质移走。分析了反应热的可利用途径,提出一种将反应段和提馏段分割、从反应段移出反应热供提馏段加热的内部热集成乙氧基化反应精馏结构——IHIERD。模拟结果表明,IHIERD 将使再沸器的温度从462.5 K降低到420.0 K,冷凝器负荷降低11%,外部能量输入降低14%,节能效果显著。

关键词: 乙氧基化, 反应精馏, 乙二醇单丁醚, 反应热, 内部热集成