Waste heat transportation system, using phase change material (PCM) from steelworks to chemical plant

This paper describes the feasibility of a latent heat transportation (LHT) system that uses phase change material (PCM) to recover waste heat at temperatures over 300 degrees C in steelworks and supplies it to a distillation tower of benzene, toluene, and xylene (BTX). The operating data in the proposed system as well as in a conventional heat supply system and a sensible heat transportation (SHT) system - were calculated based on heat and material balances in order to evaluate energy requirements, exergy loss, and CO(2) emissions. The results showed that an LHT system using NaOH with a solid-solid transformation temperature of 293 degrees C and a melting point of 320 degrees C as PCM has 2.76 times the amount of heat-storage density of an SHT system; additionally, it has only 8.6% of the energy requirements, 37.9% of the exergy loss, and 17.5% of the CO(2) emissions of a conventional system that lack heat-recovery capabilities. The results suggest the possibility of transporting heat via high-temperature PCM from steelworks to chemical plants. Such infrastructure would offer many benefits such as energy savings, reductions in exergy loss and CO(2) emissions, and the benefits associated with coproduction. (C) 2010 Elsevier B.V. All rights reserved.