Energy Conservation by Waste Heat Recovery in Industry Using Thermosyphon Heat Exchangers

摘要

Conservation of energy by waste heat recovery is important, not only for cost reasons but also for reducing primary energy consumption as well as reducing carbon dioxide production. This paper explains and discusses the design, performance, and successful applications of Thermosyphon Heat Exchangers (THE's) for recovering heat from exhaust gases in industrial plants. Heat exchangers made of two-phase closed thermosyphons are one of the most effective equipment for waste heat recovery. The advantages of this system are compactness, flexibility of system size, ease of operation, and minimum maintenance requirement. Thermosyphon Heat exchanger can satisfactorily act as pre-heater of air in boilers and furnaces using the heat recovered from the exhaust. One successful industrial practice is explained using Thermosyphon Heat Exchanger. The Thermosyphon Heat Exchanger was used to recover waste heat from the exhaust of a boiler in SAMEN Company. The energy recovered from the flue gas was used to preheating the incoming air to the boiler. In this work a thermosyphon heat exchanger was designed to recover waste heat from exhaust of a 7 ton boiler. By using the thermosyphon heat exchanger 126672 m~3 natural gas will be saved and 248820 kg production of CO_2 will be reduced per year. The average rate of heat recovery from the flue gases by the thermosyphon heat exchanger was 100 kW. The payback period was less than two years. In this study, the evaluation of the thermal performance of the Thermosyphon Heat Exchanger was based on the effectiveness-NTU method to obtain the heat transfer characteristics.