Title: Exergy destruction analysis of heat exchanger in waste heat recovery system in Kroll process

Authors: Wenhao Wang; Fuzhong Wu

Addresses: School of Metallurgy, Northeastern University, NO.3-11, Wenhua Road, Heping District, Shenyang 110189, China ' The Key Laboratory of Metallurgy and Energy Conservation of Guizhou, Guiyang 550025, China

Abstract: In pilot-scale tests of a waste heat recovery system designed for Kroll process, energy and exergy efficiency were only 30% and 10%, and there is no judgement about this system. In present work, the exergy destruction analysis is used to investigate heat transfer and effectiveness of the system. The water with the flow rate of 0.12 kg/s, 0.14 kg/s and 0.16 kg/s is forced across a shell-tube heat exchanger, while the air flow rate is 22 m3/min with a temperature range of 350∼380°C. The results show that higher air inlet temperature is good for all indicators, while greater water mass flow rate is only good for heat transfer rate, irreversible heat transfer rate and water side irreversibility ratio. The energy and exergy effectiveness have a similar trend. From the viewpoint of energy quality and quantity, the tested shell-and-tube heat exchanger system can still be used to recover waste heat in Kroll process.

Keywords: exergy destruction; waste heat recovery; irreversible heat transfer rate; energy effectiveness; exergy effectiveness; exergy analysis; heat exchange; Kroll process; air inlet temperature; water mass flow rate.

DOI: 10.1504/IJEX.2017.081204

International Journal of Exergy, 2017 Vol.22 No.1, pp.89 - 101

Available online: 26 Dec 2016 *

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