Iterative approach to the study of optimal production policies for a multipurpose plant

A study of optimum operating conditions for operation of a multi-purpose nitrating plant is carried out by means of a decomposition technique. The plant is multipurpose inasmuch as three products—nitrobenzene, monotrichlorobenzene, nitrotoluene—can be produced with the same configuration of equipment. The decomposition procedure is applied to the analysis of the optimum structure of the plant and the economic environment, which identifies two sub-systems, namely the plant and inventory model. The technique facilitates the solution of the system, while preserving the dimensionality.

An economic global index of performance is taken as the present value, which can be optimised in terms of production rates, running times and number of runs for each individual process. For a particular set of market conditions a global optimum is defined and its sensitivity to some of the costs is assessed. It is found that, although the value of the index is sensitive to the level of unit manufacturing cost and unit selling price, the location of the optimum, and consequently the optimum operating strategy, remains unchanged for changes up to 5% in unit cost and price.