化工过程系统多目标夹点分析的模型框架与步骤

减少水、能源和资源利用是化工生产过程中面临的最重要的挑战.通过对化工过程系统进行分析,本文将过程集成技术中的水夹点、热夹点和碳夹点技术相结合,提出多目标夹点分析方法.分析了在化工过程中用水、热公用工程以及碳排放的关系,提出洋葱头修改概念图,增加二氧化碳排放和能源规划环节.在同时考虑化工生产过程中的水、热和能源多方面因素的情况下,提出基于贯序的多目标夹点分析与设计方法,建立了详细的模型框架以及设计步骤.具体步骤如下:(1)基础数据提取；(2)无水回用情况下的新鲜水用量；(3)基于累积流量-累积负荷图,确定最小新鲜水用量和最小废水排放量以及夹点的位置；(4)确定新鲜水节约效率；(5)进行水网络设计:(6)运用累积负荷-累积流量-温度图,确定最大公用工程用量,绘制能量匹配图；(7)从水网络设计图中提取热集成数据,计算最小公用工程数据；(8)计算节能效率；(9)基于累积能源-累积二氧化碳排放组合图,确定最终的能源资源分配.按以上步骤可确定最小新鲜水用量、最小废水排放量、最小公用工程、最小清洁能源使用量.

Framework and procedure of multi-objective pinch analysis for chemical processes

With the shortage and price increases of the water and energy and the limits of pollution(e.g.wastewater,carbon dioxide,etc.), improving resource efficiency and reducing environmental pollution become the present and future major challenges for the process industries. To solve such challenge,this paper proposes Multi-Objective Pinch Analysis techniques(MOPA) based on the pinch analysis technique,which combined water,heat and carbon pinch analysis together.According to the relations among water,utility and carbon emission,the Onion diagram is modified.The new one contains carbon emission and energy planning stage in the process design and synthesis.With the considerations of water,heat and energy resources,The MOPA proposes a sequential method to determine the consumption of water and energy targets to achieve optimal system.The detailed framework and procedure are presented.(1) Extracting the stream data from the process flowsheet;(2) Determining the freshwater usage without water recycling;(3) Determining the minimum freshwater usage,wastewater discharge and the pinch point based on cumulative flowrate-cumulative load diagram;(4) Calculating the water saving efficiency;(5) Designing the water using network according the nearest neighbor algorithm;(6) Determining the maximum utility usage and drawing the energy matching diagram according to cumulative load- cumulative flowrate-temperature diagram;(7) Determining the minimum utility usage according the heat integration of water using network;(8) Calculating the energy saving efficiency;(9) Determining the energy resource allocations based on the cumulative energy consumption- cumulative carbon emission.The minimum freshwater usage,the minimum wastewater discharge,the minimum utility consumption,and the energy resource allocations are determined.