基于逻辑与启发性知识的MINLP过程综合方法

提出了一种系统化的基于逻辑与启发性知识的MINLP过程优化综合方法 .该方法将超结构图的拓扑结构分解成特定的几种设备连接类型 ,通过组合形成基于逻辑的混合整数规划模型 ,克服了数学规划法在建模方面所存在的不直观、难于系统化地实现、复杂的超结构模型难于建立等缺点 .模型中还以硬逻辑或启发的形式引入工程经验 ,减小了搜索空间 ,加快了求解速度 .通过化工厂公用工程系统综合的实例 ,将本方法与传统的层次分解法、数学规划法进行了比较 ,证明了其实用性和优越性

NEW LOGIC AND HEURISTIC KNOWLEDGE BASED MINLP APPROACH TO PROCESS SYNTHESIS

Mathematical programming approach has been widely used for the systematic synthesis of process flowsheets. In this paper, a new logic and heuristic knowledge based MINLP approach to process synthesis is presented, which makes modeling more easily and systematically. In a typical superstructure, there are three types of unit: equipment, inlet/outlet stream and mixer/splitter. Each equipment is associated with a binary variable y i ( i =1,2,..., N ), and each inlet/outlet stream is also associated with a binary variable z i ( i =1,2,..., M ). The topology of the superstructure can be divided into 4 connection types as follows: 1-1 connection relations, 1- n connection relations, exclusive 1- n connection relations and m-n connection relations. With the logical representations of each relation, the superstructure can be converted to a logic-based MINLP model, which will be solved directly or through its algebraic forms. Operating experiences are expressed in logical forms, so that they can be integrated into the MINLP model as hard-logic or heuristic knowledge. This approach was used in a sample of utility system synthesis, which supplied three types of steam, several types of mechanical energy, electricity and water for a petroleum refinery. The synthesis result was compared with the hierarchical decomposition approach and the traditional mathematical programming approach, which showed that this approach could get better results than hierarchical decomposition. In comparison with the mathematical programming approach, this technique reduced the number of variables and the solving space, so the model size and computing time were decreased.