Total site utility system structural design using P-graph

Abstract

This paper explores the macro optimisation decisions of energy sources selection and the structural design of the utility system within the framework of Total Site Heat Integration (TSHI). Most TSHI research on utility systems focuses on optimisation of conventional Combined Heat and Power systems. To build a new Utility Systems Planner (USP) tool, P-graph has been selected as the optimisation tool. A critical element of USP is the inclusion of low-grade heat utilisation technologies within the considered superstructure. The USP outputs include the optimal structure of the utility system including the arrangement and size of each component and estimates for Greenhouse Gas and Water Footprints. The successful application of the USP to a representative industrial case study with district energy integration shows an optimal solution with a natural gas boiler, reciprocating gas engine, condensing economiser, steam turbine, thermocompressor, organic Rankine cycle, cooling tower, and electric chiller with a total cost of 14.893 M€/y. The new tool is a platform for launching further research including site-specific application, multi-period optimisation, and sensitivity analysis.