An Optimal Planning Method of Plants Based on Mixed-Discrete Variable Nonlinear Programming

Abstract

An optimal planning method based on a nonlinear programming approach is proposed for the initial design of plants. The optimal constitution and operational policy of equipment are investigated so as to minimize the tota1 annual cost of the plant. This planning problem is formulated as a mixed-discrete variable programming problem, in which discrete and zero-one integer variables are adopted to indicate respectively the scales and on/off status of operation together with continuous variables indicating the operational level. The generalized reduced gradient algorithm is adopted in order to take account of nonlinear equations representing performance characteristics and other properties of each piece of equipment, and is combined effectively with the branch and bound algorithm. The application of the proposed method is illustrated with the planning problem of an energy supply plant of an LNG carrier, and it is shown that this approach is an effective tool for designing plants.