基于热损失的换热网络夹点设计法

现行的换热网络目标方法,在进行换热网络价格估算时,未考虑热物流的热损失。在真实的设计中,换热器壳体保温后仍与环境温度相差较大,则其热损失不可忽略。文章提出了一个新的基于热损失的换热网络夹点设计法,该方法首先以综合费用最小为目标确定出最小温差,然后建立问题表格确定出夹点位置及最小公用工程消耗,最后再进行换热网络设计。文中采用某石油常减压换热网络系统为典型算例对该方法的前两步进行了分析研究,论证了该方法的必要性及可行性。结果表明:该方法与基本Linnhoff夹点技术法估算的投资费用有较大的差距之外,在一定的最小温差下,其与基本Linnhoff夹点技术法确定的夹点位置不同,公用工程消耗也有较大的差距。

Pinch design method for heat exchanger networks based on heat loss

Current heat exchanger network targeting methods do not consider the heat loss of a hot stream during the network cost estimation.In real design case,however the temperature of heat exchanger shell is greatly different from that of environment,the heat loss of a hot stream can not be neglected.A new pinch design method for the design of heat exchanger networks based on heat loss was introduced.Firstly,Δtmin(the minimum allowed temperature approach in an exchanger,heater or cooler) was calculated based on the targeting of comprehensive cost-minimum heat exchanger networks.Secondly,the pinch was located and the minimum utility usage was calculated by the problem table algorithm.Finally,heat exchanger networks were designed.The typical examples of atmospheric-vacuum distillation unit were used to verify the necessity and feasibility of the method through analyzing and researching the former two steps.The results show that there exists great difference for the network cost estimation between this new method and the pinch design method which is first introduced by Linnhoff.In addition,the pinch location and utility usage are also greatly different in a certain Δtmin.