Automatic Designing System for Piping and Instruments Arrangement including Branches of Pipes : Multi-objective Optimization of Piping Material Costs and Valve Operability

Automatic designing of piping layout is challenging since it is composed of several numerical and/or combinational optimization problems, e.g., routing problems of pipes including branches, and arrangement problems of equipments. This paper presents a new approach based on a simple idea that the branches of pipes are considered to be a variety of equipment. Accordingly, the pipe routing problems are fairly simplified by removing the branches, and it derives a lot of efficient algorithms to solve the pipe arrangement problems. One is a multi-objective genetic algorithm (MOGA) in which the gene represents both the locations of the equipments and the arrangement of the pipes. And a new simple and efficient crossover operation which appropriately merges two different piping layouts (but of course the PID is the same) is proposed. In order to provide a fairly good initial population for the MOGA, a new heuristics making use of self-organization techniques to arrange equipments is proposed. The efficiency of the proposed approach is demonstrated through two experiments, one is a designing problem including five valves, one pump, and five branches, and the other includes seven valves, one pump, and six branches. The objective of the optimization in the experiments is to minimize the length of the pipes, the number of elbows, and the valve operability cost. The algorithms are programmed using Java language. Although the automatic arrangement system used in the experiments is academic, the concept of the proposed approach will be accepted in practical systems.