O.3.7.2 Integration of Heat Pumps in Industrial Processes with Pinch Analysis
The industrial sector consumes a considerable amount of energy. In many countries it is 20% or more of the total energy use of which a major proportion is used solely for heating leading to the need to improve thermal energy efficiency. Process integration methods involving thermal systems such as pinch analysis provide ways to reduce energy use and environmental emissions in the process industry. Using pinch analysis it can be systematically shown how the heating and cooling demands of a process should be matched in order to improve heat recovery based on an economic optimum between investment and operating costs. An additional measure to help reduce energy needs is to use a heat pump. However, the integration of heat pumps in industrial processes is a challenge as it is difficult to choose which parts of the process should be connected to the heat pump. Pinch analysis provides a convenient rule to help meet this challenge: A properly integrated heat pump works across the pinch point, i.e. a heat pump takes heat from below the pinch point, where there is an excess, converts it to a higher quality and transfers it across the pinch point where there is a heat deficit. The aim of this paper is to present the methodology of how to properly integrate a heat pump using pinch analysis and to apply the methodology to an industrial case study. With the correct integration of the heat pump it is shown how the overall process energy efficiency can be significantly increased though the reduction in the hot and cold utilities resulting in lower energy COSTs.