An Optimization Model for 3D Pipe Routing with Flexibility Constraints

Optimizing the layout of the equipment and connecting pipes that form a chemical plant is an important problem, where the aim is to minimize the total cost of the plant while ensuring its safety and correct operation. The complexity of this problem is such that it is still solved manually, taking multiple engineers several years to complete. Most research in this area focuses on the simpler subproblem of placing the equipment, while the approaches that take pipe routing into account are either based on heuristics or do not consider sufficiently realistic scenarios. Our work presents a new model of the pipe routing subproblem that integrates realistic requirements, such as flexibility constraints, and aims for optimality while solving the largest problem instance considered in the literature. The model is being developed in collaboration with Woodside Energy Ltd. for their Liquefied Natural Gas plants, and is implemented in the high-level modeling language MiniZinc. The use of MiniZinc has both reduced the amount of time required to develop the model, and allowed us to easily experiment with different solvers.