Investigation on HHO-assisted combustion performance and NOx emissions in pulverized coal boilers under low-load conditions

In order to improve the operational reliability and peak-shaving capabilities of such units under low-load situations, this study examines the co-combustion behavior of Brown's gas (HHO) in a 125 MW tangentially fired coal-fired boiler. The impacts of varied load levels (30%–50%) and HHO injection intensities on NO x production characteristics, burnout performance, and combustion stability are examined by a series of three-dimensional CFD simulations. According to the simulation results, adding HHO significantly improves the boiler's performance at lower loads. For example, at 30% load, the burnout efficiency reaches 96.17% and NO x concentrations fall below 220 ppm. To ascertain the ideal operating parameters, an optimization framework that combines Gaussian Process Regression (GPR) and the Non-dominated Sorting Genetic Algorithm (NSGA-II) is utilized. At 30% load, this framework allows for additional increases of 11.21%, 1.65%, and 5.09% in operational stability, combustion efficiency, and NO x emission management. Overall, this work emphasizes the potential of HHO to reduce pollutant emissions and offers useful recommendations for the dependable low-load operation of big coal-fired boilers using HHO-aided combustion.