Minimization of energy use in multipurpose batch plants using heat storage: an aspect of cleaner production

A mathematical technique for optimization of energy use through the exploitation of heat storage in heat integrated multipurpose batch plants is presented in this document. Storage of heat is effected through the use of a heat transfer fluid. The resultant mathematical formulation exhibits a mixed integer linear programming (MILP) structure, which yields a globally optimal solution for a predefined storage size. The concept of heat integration in batch plants with the objective of minimising energy use is indeed an aspect of cleaner production that has received very limited attention in published literature. This is largely because batch plants are perceived to be less energy-intensive compared to their continuous production counterparts which is untrue for some batch operations, like dairy and brewing processes; hence the need for dedicated techniques. Application of the proposed method to an agrochemical facility has shown savings of more than 75% in external utility steam consumption.