Effect of particle size on exhaust characteristics during the combustion of high-grade bituminous coal available in barapukuria coal mine

This paper represents a novel design for a coal combustion chamber and utilizes computational fluid dynamics (CFD) to analyze the primary impact of the size of the particle on ignition characteristics of pulverized high-grade bituminous coal from the Barapukuria Coal Mine. The influence of particle size on exhaust gas composition, pressure, temperature profiles within the furnace, and overall combustion performance is investigated. The study employs CFD software (ANSYS FLUENT) to simulate thermal and fluid flow processes within a 3D furnace model. The results are validated against experimental data. The research focuses on the impact of volatile matter freeing and reactions from coal particleswith a partial co-flow on the development and emission of CO, CO2, and NOx. A unique vertical furnace with a length of 594 mm and a square cross-section of 344 mm x 344 mm is used for performance evaluation. High-grade bituminous coal with particle sizes ranging from 0.001-0.005 mm and 0.01-0.05 mm is injected at a constant mass flow rate of 0.001 kg/sec using CO2 as a transporter gas through an insulated, water-cooled central jet. The furnace and pipes are insulated with high-temperature fiber wool. The study reveals that combustion efficiency increases significantly with decreasing particle size for the same mass flow rate. Furthermore, exhaust gas recirculation is implemented to preheat the primary air, promoting improved combustion efficiency and reduced heat losses.