Targeting for multiple resources in batch processes

Operating cost of a batch process can be reduced using multiple resources. In this paper, a methodology is proposed to target multiple resources in order to minimize the operating cost of the overall batch process. The proposed methodology is based on the concept of prioritized cost, originally developed for continuous processes. Prioritized cost of a resource depends on the pinch quality, quality of the resource and its cost. The concept of prioritized cost is extended to optimize the operating cost of a batch process. It is proved that to minimize the operating cost a batch process, prioritized cost of a resource in any time interval may not necessarily depends on the pinch quality of that interval. Prioritized cost of a resource in any time interval depends on the highest pinch quality of all the subsequent intervals, including itself. This important result is proved mathematically. The proposed methodology is applicable to fixed-scheduled, fixed-flow batch processes involving single quality.