Segregated problem table algorithm for simultaneous targeting and design of integrated energy networks

Abstract

Pinch analysis is an established methodology for process design and optimization to achieve the minimum utility consumption. The Problem Table Algorithm (PTA) is one of the most popular numerical methods to determine the energy targets. However, the PTA is unable to show the individual hot and cold stream heat cascade profile. This work presents a new numerical tool for simultaneous targeting and design of heat exchanger networks called the Segregated Problem Table Algorithm (SePTA). SePTA, which shows individual hot and cold streams heat cascade profiles across temperature intervals, allows a designer to simultaneously determine the energy targets, locate the pinch points and perform the SePTA Heat Allocation (SHA). This work also extends the use of SePTA for process integration of a trigeneration system. Using SePTA, appropriate matching of heat engines and heat pumps with process streams can be made. Process integration with trigeneration has been implemented in a case study involving edible palm oil plant to reduce demands for heating, cooling as well as power consumptions. The results have been compared to a system without trigeneration, and those with a heat engine as well as a heat pump. The trigeneration system is able to fulfill 3990kW of hot utility for the process and 1241kW of driving energy required by an absorption heat pumps’s generator. At the same time, 238kW electricity is produced by the turbine and 185kW is saved from the shut down of one unit chiller for a compressor. Trigeneration integration with process led to an annual savings of RM 1.1 mil with an investment payback period of 1.9 years.