Heating and cooling networks design algorithm for site wide energy integration
Résumé
Heat integration is a widely used methodology to reduce industrial plants energy consumption, utility targeting and optimal configuration for heat recovery. Heat integration was extended to target several aspects such as heat exchangers synthesis or thermodynamic systems integration for heat recovery and valorisation. The total site heat integration (TSHI) method was introduced to recover post heat integration surplus heat in one or more plants plant by transporting it through tertiary steam mains to other plants, and reduce the overall energy consumption. Liquids represent as alternatives to steam, since they can emulate certain process fluids behaviour by changing temperature, which increases the heat recovery potential. In this paper, a first linear programming model based on the coupling of the TSHI method and exergy analysis is presented, this coupling helps specifying the networks and thermodynamic conversion systems that will enhance the overall exergy efficiency. Thermodynamic systems include heat pumps, absorption refrigeration cycles, organic Rankine cycles and cogeneration systems. A second model evaluates the proposed solutions economically. It considers energy transportation and conversion costs. It takes into consideration geographical positioning of plants to specify the type of networks (steam or liquid) routing, sizes of pipes and heat exchangers’ surface area. The two models can be used in a two steps approach; meaning systems are specified then evaluated economically, or in a simultaneous approach. To illustrate the capabilities of this approach a case from the literature is studied.