Abstract
Heat Integration is a crucial method for making reasonable and effective utilization of waste heat in industrial enterprises. In a polysilicon production enterprise, some hot streams are cooled to a specified temperature by circulating cooling water followed by the ethylene glycol compression refrigeration. But the temperature of streams is still high after cooling by water, which results in high energy consumption of compression refrigeration. There is low-grade waste heat in the enterprise, so that lithium bromide absorption refrigeration driven by waste heat can be considered to replace some duty of compression refrigeration. In this work, hot water is used as intermediate fluid to recycle waste heat, which drives the lithium bromide absorption refrigeration. Then cascade cooling of the hot streams by circulating water, absorption refrigeration and compression refrigeration can be achieved. In this work, the consumption and temperature of hot water used in waste heat recovery, the temperature of the absorption refrigeration, and the load distribution of water cooling, absorption refrigeration and compression refrigeration are solved through simulation and modelling. The cost of the two cooling processes is calculated and compared. Finally, a case study is given to illustrate the feasibility and economy of the method.
