TANG Yongzhi ¹, ZHAO Yuandong ¹, FENG Qing ¹, LU Lin ¹, LIU Zhongliang ²
(1. Department of Energy and Power Engineering, Jingdezhen Ceramic University, Jingdezhen, 333403, Jiangxi, China; 2. Key Laboratory of Enhanced Heat Transfer and Energy Conversion, Ministry of Education, Beijing University of Technology, Beijing 100124, China)

Abstract: The existing intermittent kilns are generally lack of a complete waste heat recovery system and the waste heat of high-temperature flue gas generated during the firing process cannot meet the heating demand of the whole-time production process, due to the intermittent production method. Therefore, a molten salt thermal storage technology was proposed in this study, aiming to achieve the recovery, storage and cross-time reuse of the high-temperature flue gas from intermittent kilns. Correspondingly, a mathematical physical model coupling multi physical fields was established for the molten salt regeneration process. The attention was focused on the molten salt thermal storage characteristics of high-temperature flue gas, as well as the influences of flue gas heat exchange tube layout, flue gas flow rate and temperature on thermal storage rate ofthe molten salt. It is found that the thermal storage efficiency is maximized when the heat exchanger tube is of longitudinal layout and the flow direction of flue gas is from bottom to top, followed by the flow direction from top to bottom. In comparison, the horizontal layout is the worst. Thermal storage efficiency of the molten salt increases significantly with increasing flue gas flow rate and temperature. Thermal storage rate decreases at a higher speed, while it tends to be relatively stable as temperature increases. The thermal storage rates increase by 32.11% and 64.77% respectively within the given change ranges of the flue gas flow speed and temperature.
Key words: intermittent kiln; molten salt thermal storage; high temperature flue gas; thermal storage characteristics; heat exchanger tube layout