Sequential decision-making for the application of a site-wide energy analysis based on the BBridge method

Heat integration is a practical approach that helps industries to increase their profitability through the optimization of energy usage, and the associated reduction of greenhouse gas (GHG) emissions. In past decades, several methods have been developed for the analysis of heat exchanger networks, but most of the developed methods are complex for their application to retrofit situations. In the last few years, a novel method called Bridge Analysis has been developed for the case of Heat Exchanger Network (HEN) retrofit. More effective than traditional approaches, this new method permits analysis of retrofit cases and furthermore, the analysis of the total site energy usage when coupling two industrial processes such as the case of the forest biorefinery.

The Bridge Analysis method is a novel method for site-wide energy analytics that is distinct in approach to classical pinch analysis, with a well-defined procedure that lends itself well to resolution using computer algorithms and a graphical user interface. In this method, energy-related process data is used to characterize the existing process configuration, and then modifications to reconfigure the energy-use profile of an industrial mill.

The objective of this paper is to describe the Bridge method, and the sequential decision-making framework to make Bridge analysis practical for industry application. The model of an energy-efficient “average” Scandinavian pulp mill has been analysed as a case study using Bridge Analysis to identify the short-term and long-term energy strategies of a bleached pulp mill.