Process Waste Heat Recovery in the Food Industry - A System Analysis

Abstract

An analysis of an industrial waste heat recovery system concept is discussed. For example purposes, a food processing plant operating an ammonia refrigeration system for storage and blast freezing is considered. Heat is withdrawn from the refrigerant vapor by a recovery system composed of a desuperheater, a condenser, and a heat pump. The system is used in this case to preheat process fresh water during the one or two production shifts of each day; surplus hot water is stored in a thermal storage tank, the fourth major component of the system, for later use during third shift cleanup. The system analysis is done parametrically on the refrigerant flow handled by the recovery system and on the refrigerant flow split between the system components. Curves are developed showing annual heat recovery, hot water storage volume, and return on investment as functions of these parameters. In addition, a brief discussion is provided concerning recovery system operation and control. Analyses of this type are effective since they can be performed inexpensively and they provide a substantial amount of information for use in selecting the system and the design point that is best for the particular situation.