Abstract:

Adjusting operation conditions of a distillation column is one of the effective ways to save energy consumption of the column. However, operation conditions of a distillation column will affect the energy consumption of both the column and the heat exchanger network. Based on the cold and hot composite curves with all streams including the reboiler, condenser, and process streams, this paper analyzes the influence of the pressure variation of an across pinch distillation column on the utility consumption of the whole process. The stripper column in a continuous reforming process is taken as a case study. The results show that the reduction of the column pressure can increase the heat duty of condenser and decrease the heat duty of reboiler. However, for the streams from the top or bottom of the column, the reduction of the column pressure can save cooling utilities but increase heating utilities. The overall energy saving effect of the unit is the comprehensive effect of the condenser, reboiler and streams from the top or bottom of the column. Analysis of the stripper of a continuous reformer shows that when the tower pressure is reduced by 200.0 kPa, the heating utility usage will be reduced by 577.5 kW.

Key words: systems engineering, heat exchanger network, distillation column, pressure, integration, optimization, cold and hot composite curves

摘要：

调整精馏塔的操作条件是节省塔能耗的有效途径之一，然而在对已有装置进行用能优化时，需同时考虑精馏塔操作条件对塔能耗和换热网络能耗的影响。基于装置所有流股的冷热复合曲线，针对跨夹点的精馏塔，同时考虑了精馏塔的再沸、冷凝以及过程流股，分析了塔压变化对装置公用工程消耗的影响，并对某连续重整装置汽提塔进行了案例分析。结果显示，塔压降低可使冷凝器能耗增加，再沸器能耗减小，而对于塔顶塔底出装置流股，塔压降低可节省冷却公用工程但增加加热公用工程。装置总体的节能效果为塔顶冷凝器、塔底再沸器和塔顶塔底出装置流股节能效果的综合作用。对某连续重整装置汽提塔分析表明，塔压降低200.0 kPa时，其加热公用工程用量将减少577.5 kW。

关键词: 系统工程, 换热网络, 精馏塔, 压力, 集成, 优化, 冷热复合曲线