Robustness Analysis of Heat-Integrated Batch Process Networks

Abstract

Heat integration in batch processes strongly depends on the production schedule due to time-dependent availability of hot and cold process streams. Schedule delays in batch process operation are inevitable and can significantly reduce the practical benefits promised by heat integration. This paper presents a systematic framework to analyze the effect of schedule delays on achievable heat recovery in batch process systems. To this end, a time delay analysis method is proposed to generate heat recovery profile as a function of stream delay. The analysis computes maximum theoretical heat recovery (with a modified heat exchanger network) as well as practically achievable heat recovery (with the same network). The results of time delay analysis are then used to define three robustness measures to assess the sensitivity of a heat-integrated batch process network toward schedule delays. The presented framework allows identification of sensitive process streams as well as provides an operational measure to screen competing design alternatives. Two relevant example systems are considered to illustrate the effectiveness of the proposed framework.