糖业典型蔗渣锅炉炉内燃烧组织优化研究

Taking a 65 t / h, 3. 8 MPa sugar bagasse boiler in Guangxi province as the research object, the influence of different-sized model structures on the combustion of the boiler was studied, as well as the influence of changing the primary / secondary / tertiary air volume and the slag nozzle angles of the bagasse boiler on the heat / mass transfer characteristics of combustion in the furnace was investigated. When the slag nozzle angle changed from 30° to - 30°, the Coandâ effect occurred because the ratio of the width of the jet to the radius of curvature of the wall(h/ r value) was less than 0. 5. The secondary air flowed along the wall with the incident angle was consistent with the slag nozzle angle. When the angle of the slag nozzle reached - 40°, the h/ r value was greater than 0. 5 and the Coandâ effect disappeared, and then the secondary air entered the furnace horizontally. By reducing the angle of the slag nozzle(the angle of the slag nozzle was - 40°), decreasing the primary air volume(8. 9% lower compared with the original working condition), increasing the tertiary air volume of the back wall of the grate(95. 1% higher compared with the original working condition), and increasing the tertiary air volume on the lower side of the back wall (66. 7% higher compared with the original working condition), the combustion organization in the furnace of the boiler could be greatly improved. As a result, the boiler efficiency increased by 2. 13 percentage points, and the combustion of bagasse on the grate was reduced, realizing the ‘suspension’ combustion of bagasse. By exploring the intrinsic reaction kinetic characteristics of bagasse boiler combustion, combined with the single-particle rapid fluidization combustion experiment, the mixed combustion characteristics close to the actual semi-suspension state in the furnace are analyzed. It was proved that the layered slow combustion in the bagasse boiler was reduced. Meanwhile, the suspension combustion became the dominant form and the combustion state of ‘semi-suspension + layer combustion’ increased the combustion time in the furnace, promoted the mixing of fuel and air, and helped to achieve the optimal combustion state.