考虑热力学目标的进料分流预热精馏塔分析优化

Analysis and optimization of distillation columns with feed splitting and preheating by considering a thermodynamic target

系统地提出了一种进料分流预热精馏塔的节能优化与水力学校核优化方案。基于热力学工具固定精馏线-提馏线,可定量计算精馏塔获得100%理想预热效率(精馏塔再沸器负荷的减小量与进料预热量之比)时的操作参数,并利用气液分布曲线来确定效率最低的塔板;同时,基于C++和MATLAB中的GUIDE,进一步开发了具有可视化窗口的水力学验算软件,对效率最低的塔板进行水力学分析。以石油化工行业中稳定塔(简化为正丁烷-正己烷塔)为例,热力学研究结果表明,当预热量、分流率及进料位置分别设为1000MJ/h、0.7与9/20时,稳定塔可获得100%的理想预热效率;水力学核算发现,适当设置塔板结构可保证精馏塔在正常操作下实现节能的目的。本研究对实际精馏塔节能改造具有一定的指导意义。

The work systematically addresses an optimization approach of the energy-saving and hydraulic checking for distillation columns with feed splitting and preheating. To maximize the feed preheating efficiency （ratio of the reboiler duty reduction to the feed preheating duty）, the key influencing parameters （e.g. amount of preheating, splitting fraction and feed locations） were adjusted by using invariant rectifying-stripping curves. Then, vapor-liquid distributing curve was employed to identify the tray with the lowest tray efficiency. Additionally, with the help of C＋＋ programing and GUIDE tool in MATLAB, a professional hydraulic software, namely SYSU-DISTILL, with visualization window was developed. This software was used to analyze hydraulics of any tray with the lowest tray efficiency. A stabilization tower （ it was assumed as an n-butane-n-hexane column） from the petroleum and chemical industry was used as an illustrative example. The thermodynamics results showed that an ideal feed preheating efficiency （100%） of this column can be reached when amount of preheating, splitting fraction and feed locations were 1000MJ/h, 0.7 and 9/20, respectively. Meanwhile, the appropriate setting tray structure can achieve the goal of energy saving under guaranteeing normal operation of the distillation column from hydraulic checking. This work provided an insight into analysis and guidance in determining the optimal schemes for energy saving of actual distillation columns.