Employing optimization method to determine the production plan in the plan environmental impact assessment of a petrochemical development district

During implementing plan environmental impact assessment to control the potential pollution of a petrochemical development district, a problem of dealing with a complicated supply chain should be solved. By taking the factories as “points” and supply relations as “lines”, the supply chain can be reduced to “points” and “lines”. Then by defining one key product for one factory, the production amount of any non-key product or raw material can be linearly expressed by that of the key product of the same “point”. And the relation between the supply amount of an upstream factory and the need amount of its downstream factory can be expressed by inequation of the production amounts of their respective key products, called “line” constraint. After all the steps, an optimization model can be established, and an example of determining the production plan of Daya Bay District is taken. The results show that the model can well help the decision maker to get a largest profit without serious pollution.