固定结构的热交换器网络的非线性规划优化

NONLINEAR PROGRAMMING OPTIMIZATION FOR HEAT EXCHANGER NETWORK OF FIXED STRUCTURE

传热系统的最优组合是当前石油化工过程最优组合的重要研究课题之一.利用运筹学的方法结合计算机寻找换热系统的最优组合是将数学、计算机科学应用于化工系统的有效途径,它能够带来明显的经济效益.固定结构的热交换器网络的优化是在系统的外形结构已确定的情况下,对系统的设计参数和设备进行优化和选型.由于设备的台数为一整数变量,因此,它是一个含有等式与不等式约束的混合整数非线性规划问题。本文用穷举算法解决了设备选型问题,用伸缩保差算法解决约束非线性规划问题,在算法的构造上使两者很好地结合,把一个困难的问题转化为易于解决的问题,从而在解决工程设计问题上取得了十分满意的结果.附计算实例并有优化前后的结果比较。本工作是“石油化工装置节能软件”的一个部分.

The synthesis of heat exchanger network is currently one of the impor- tant research topics in petro-chemical processing.An effective way to find the optimum combination of heat exchange system is to use operational research. The optimization of heat exchanger network with fixed structure is to opti- mize and select design parameters and equipments for the system when its configuration is defined.Since the variables representing the number of equip- ments must be an integer,the problem is a nonlinear mixed-integer pro- gramming with equal and unequal constraints. A method is suggested for solving the problem of selecting equipments by using enumeration algorithm and to use a flexible numerical algorithm for implementing a constrained nonlinear programming problem and then com- bining those two algorithms.The main advantage of this algorithm is that it transforms the difficult problem involving both integer and noninteger varia- bles into a number of simpler subproblems which can be solved easily and give a satisfactory result for engineering design purpose.An example is pre- sented and the data before and after optimization are compared.