基于Aspen Tech的分馏塔用能优化及换热网络夹点分析

Aspen Tech-based Energy Efficiency Improvement and Heat Exchanger Network Pinch Point Analysis for Fractionators

炼油工艺过程中,分馏系统的用能优化是换热网络能量优化的必然要求。以荆门石化3.5Mt/a常减压蒸馏装置为例,利用Aspen Plus和Aspen Energy Analyzer软件,对常压塔以及换热网络的用能情况进行分析,提出能量优化利用思路:变工况条件下,首先优化分馏系统操作参数,再以此为条件,优化换热网络结构,才能实现整个网络的能量优化。利用Aspen Plus软件的模型分析功能,确定了常压塔底汽提蒸汽、常压炉出口温度、中段回流以及侧线的最佳操作参数,为换热网络的夹点分析提供基础数据;在分馏塔操作优化基础上,对现有换热网络进行夹点分析,找出最优夹点温差,求得现有换热网络最高理论换热终温(317.7℃),为进一步优化换热网络提出了目标;通过建立现有换热网络的网格图,找出跨夹点换热的换热器(总共有5台),为换热网络的改进提供了方向。

For a refining process ,the improvement of energy efficiency of the fractionating system is crucial to optimizing the energy efficiency of the heat exchanger network.Technicians analyzed the energy consumption in the atmospheric column and the heat exchanger network of Sinopec Jingmen Company＇s 3.SMt/a atmospheric and vacuum crude distillation unit using the Aspen Plus and Aspen Energy Analyzer software and proposed a method for improving the energy efficiencies of these components of the distillation unit--under variable work- ing conditions ,first optimizing the operational parameters of the fractionating system and then optimizing the structure of the heat exchanger network in order to optimize the energy efficiency of the entire network.By u- tilizing the model analysis function of the Aspen Plus software ,these technicians determined the optimum op- erational parameters for the stripping steam at the bottom of the atmospheric column,the temperature at the outlet of the atmospheric fumace,mid-pumparound and side streams to provide basic data for pinch point analysis for the heat exchanger network.Based on optimized operation of the fractionating column,they conduct- ed pinch point analysis for the existing heat exchanger network,found out the optimum pinch-point tempera- ture difference ,obtained the highest theoretical final heat exchange temperature for the existing heat exchanger network （317.7℃）,and set objectives for further optimizing the heat exchanger network.By establishing a grid chart for the existing heat exchanger network,they identified the heat exchangers exchanging heat across pinch points （totaling five units）, showing the way forward for the improvement of the heat exchanger network.