水夹点分析与数学规划法相结合的用水网络优化设计

OPTIMAL DESIGN OF WATER UTILIZATION NETWORKS BY COMBINATION OF WATER PINCH ANALYSIS AND MATHEMATICAL PROGRAMMING

提出了水夹点分析和数学规划法相结合的用水网络最优设计法。水夹点分析基于对过程用水的理解 ,获得新鲜水用量目标并给出用水网络设计的基本规则。在此基础上建立过程使用新鲜水、排放废水和回用的各种可能匹配方案的用水网络超结构及其MINLP模型。既避免了用水夹点综合设计用水网络得不到真正意义上的最优解 ,又在一定程度上防止超结构规模过大 ,MINLP维数太高 ,求解困难。采用通用代数建模系统GAMS得到用水网络最优设计方案。文献中的应用实例表明 ,本文所提方法可充分发挥水夹点分析确定新鲜水用量或回用结构的简洁实用性和超结构MINLP寻求最佳方案的优点。

This paper presents an approach of water utilization networks design by the combination of water pinch analysis and mathematical programming. Water pinch analysis can discover the operational bottlenecks so as to identify the minimum freshwater consumption and determine the elementary rules for water utilization networks design based on the understanding for water using process. Based on the water pinch analysis, a superstructure of water utilization networks can be built which involves only feasible and better retrofit options. Then an improved mixed integer nonlinear programming (MINLP) model for the network superstructure is proposed which considers the freshwater usage, wastewater discharge and reuse of process. The approach overcomes the defect that water pinch synthesis designs the water utilization networks with loop and prevents the case that the superstructure is too large to solve. At last, the problem can be solved with the general algebraic modeling system (GAMS) to acquire the optimal design scheme of water utilization networks. Case study illustrates that the combined method could identify the minimum freshwater consumption and determine the reuse structure concisely and practically by water pinch analysis and reach global optimum of water utilization networks by mathematical programming.