Multiphase flow simulation and industrial application of an in-line gasifier for NOx emissions control from cement kiln

Abstract

Following the power and steel industries, nitrogen oxides (NO) in the cement industry have become an important part of the next stage of air pollutant control. Consequently, the multiphase flow simulation of an in-line coal gasification denitration system was carried out using the computational fluid dynamics (CFD) approach. Among them, the solid phase is simulated by the Multiphase Particle-In-Cell (MP-PIC) method, and the gas phase turbulence is accurately captured by the large eddy simulation (LES) method. The flow field characteristics distribution and the reaction kinetic of NO under different parameters (coal, raw meal, tertiary air) in the gasifier were investigated, and the operating condition values for guiding industrial applications are obtained. The simulation results show that the gasifier can completely remove NO from the rotary kiln at 2.8 kg/s for coal, 30 kg/s for raw meal and 2.5 kg/s for tertiary air. The application results show that under 1.6 kg/t.cl of ammonia water combined with SNCR, NO emission and ammonia slip can be controlled below 50 mg/Nm and 5 mg/Nm, respectively. Compared to similar denitrification technologies, this technology shows the potential to achieve ultra-low NO emission levels in the cement industry.