AN APPROACH FOR SOLVING A SCHEDULING PROBLEM FOR MULTIPURPOSE BATCH CHEMICAL-PLANTS

An approach for solving a scheduling problem relevant to a multipurpos e batch chemical plant with multiple production routes is proposed in the article. A mixed campaign operation mode is regarded. One mixed ca mpaign may include both different routes of different products and mor e than one route for the single product. By selecting a suitable class of schedules, i.e. schedules involving consecutively carried out camp aigns of compatible production routes and minimisation of the schedule duration as a criteria for an estimation, a scheduling problem is for mulated as a covering problem in terms of binary linear programming. A n approximation method for solution of a scheduling problem which is i ntended to cope with two basic problems: (i) to avoid the large dimens ion of the initial task, and (ii) to obtain rapidly the optimal or nea r to optimal schedules of the desired class is presented. The first ta sk of avoiding the high dimension of the initial problem is achieved b y determination of the superstructure of the schedules of the desired class. The optimal or near to optimal schedules are determined by usin g the solution method based on the search tree applied to the superstr ucture obtained. The theoretical bounds of the desired schedules and t he branching function are formulated. An algorithm is proposed to find the solutions. The procedure under consideration is illustrated by so lving a simple example.