Integrated conceptual design of a robust and reliable waste-heat district heating system

The various governmental policies aimed at reducing the dependence on fossil fuels for space heating and the reduction in its associated emission of greenhouse gases such as CO2 demands innovative measures. District heating systems using residual industrial waste heats could provide such an efficient method for house and space heating. In such systems, heat is produced and/or thermally upgraded in a central plant and then distributed to the final consumers through a pipeline network. This paper studies the technical, economic, institutional and environmental feasibilities of using low-level residual industrial waste heat for the district heating of Delft, The Netherlands. An integrated conceptual design approach that takes into account both the technical and institutional design of the system has been adopted and has resulted in a feasible and robust system design. The technical part of the integrated conceptual design consisted in the estimation of the heat demands, the design of the heat upgrading system, equipment sizing, the network morphology and/or spatial connectivity and the exergy losses in the needed infrastructure as well as the economic viability of the system. An isopropanol–hydrogen–acetone chemical heat pump was selected for the process and has been modelled in ASPEN plus®. The conventional cost estimation model has been modified to account for uncompensated system downtimes.