(599x) Energy Integration of Batch Processes Using a Robust Scheduling Platform

Utility requirements in many batch plants, such as in the food industry, pharmaceuticals, breweries, dairies, biochemical plants and agrochemical facilities, are a major contributor to overall running costs. Heating and cooling are unavoidable aspects of many chemical processing facilities, with operations where heat is generated and others where heat is required. It is because of this occurrence that heat integration becomes a possibility for reducing utility requirements.

 Heat integration and scheduling have mainly been treated as separate problems in literature. The batch production schedules resulting from these formulations do not guarantee that the plant is operated optimally. Consequently, a formulation is required which integrates the task scheduling and heat recovery problems into a unified framework.

 Presented in this contribution is a formulation that addresses the optimization of heat, while simultaneously optimizing the batch process schedule. In this work the novel scheduling framework of Seid and Majozi (2012) is used as a basis for capturing time. It has been proven that this scheduling framework has better computational efficiency and yields better objective value compared to previous models in literature. Both direct and indirect heat integration are considered as well as optimization of the heat storage size. Application of the proposed method to an agrochemical facility has shown a saving of more than 75% in external utility consumption.

Keywords: heat integration, heat storage, multipurpose batch plant