Numerical Study of Waste Heat Recovery from Tunnel Kiln Utilized to Produce Rare Earth Phosphor

Abstract

An indirect heat recovery method is adopted to recover waste heat from tunnel kiln supplied by electricity utilized to produce rare earth phosphor. To ensure the quality of products and the life of tunnel kiln, a water tank is installed surrounding the cooling region of tunnel kiln as a heat exchanger. Meanwhile, a computational fluid dynamics model is developed to estimate and optimize the performance of this waste heat recovery. The predicted temperatures are in good agreement with measured results, and the error is within a reasonable range. In addition, a relationship between the inlet mass flow rate and the inlet water temperature is obtained in terms of desired outlet water temperature. Using water tank as a heat exchanger is an effective and reasonable method to recover waste heat of tunnel kiln utilized to further process of rare earth phosphor. The 4443 kg standard coal would be saved a year when inlet water temperature is 285 K.