Flue gas-dust two-phase heat transfer characteristics and corrosion behavior in industrial-scale waste heat boilers

Abstract

Waste heat boiler (WHB) has been extensively utilized across various industries due to the high efficiency in heat recovery and robust adaptability. This study employs the multiphase particle-in-cell approach to investigate the heat transfer behavior between flue gas and dust, as well as the in-furnace corrosion behavior in an industrial-scale WHB. Upon validation of the model, the flow dynamics of flue gas, the distribution characteristics of dust particles, corrosion behavior together with the effect of structure are examined. The findings reveal that excessive vortex formation significantly disrupts the flow uniformity of flue gas, with 0.87 % of the particles backflowing into the rising flue, and 51.6 % of the particles settling in the WHB. The heat transfer coefficient of dust particles reaches its peak at velocities ranging from 2 to 4 m/s, with a maximum value of 204 W/(m2K). Increasing the baffle spacing diminishes the vortex intensity in the radiation chamber and improves the flow uniformity of flue gas. Expanding the radiation chamber size not only enhances the heat exchange efficiency of flue gas, resulting in a temperature decrease of 24 K at the chamber exit, but also increases the particle sedimentation rate by 3.1 %.