基于启发式方法的弹性换热网络的合成

Synthesis of flexible heat exchanger network based on Heuristic Approach

换热网络设计一般是在固定的工况下进行的,然而系统运行时物流进口温度,流量等参数受各种因素的影响不可避免会在一定范围内波动。因此,要求合成的换热网络必须具有一定的弹性。针对工业实际换热网络优化改造的同时需要考虑其弹性的问题,本文在启发式方法的基础上,根据物流特性,提出了合成弹性换热网络的具体步骤。在换热面积足够的条件下,物流温度可以通过调节公用工程物流流量或设置旁路进行控制。本文提出了旁路设置的启发式规则。以某石化厂蜡油加氢装置作为案例分析,根据启发式规则和具体步骤提出了使其换热网络弹性化的优化改造方案。优化后可节约加热公用工程4954 kW,节约操作费用562万元·年^(-1),投资回收期为1.3年。

Heat exchanger network design is normally based on nominal operating conditions.However,stream parameters such as supply temperature and flow rate may vary within a certain range.Therefore,it is necessary to synthesize a flexible heat exchanger network.According to streams characteristics,in this paper,a procedure to synthesize a flexible heat exchanger network is proposed based on Heuristic Approach.Under enough heat exchange areas,the target temperatures are controlled by manipulating utility flow rate or setting some bypasses.Moreover,some heuristic rules to place bypass are also given in the paper.According to heuristic approach and procedure,a wax oils hydrocracking unit of a petrochemical plant is used as a case study.The proposed retrofit scheme can save 4954 kW heating utility and operation cost of 21.42 million yuan per year,while the payback period of the investment is 1.3 years.