700℃超超临界紧凑型锅炉燃烧特性模拟及优化

Simulation and Optimization of Combustion Characteristics of 700℃ Ultra-Supercritical Compact Boiler

采用计算流体力学(CFD)数值模拟与试验相结合的方法,对700℃超超临界紧凑型锅炉炉内燃烧过程进行研究。分析炉内速度分布、温度分布、组分分布、炉内粒子运动及燃尽特性,模拟及试验结果表明:新型紧凑型锅炉炉内速度及温度场与典型对冲旋流燃烧锅炉存在差异;在中间下降烟道,煤粉粒子燃烧逐渐完全,形成规则的温度梯度,尾部上升烟道左右侧存在一定的温度偏差;O_(2)浓度与燃烧主要气体产物CO、CO_(2)浓度呈现良好的一致性;惯性作用下大部分煤粉粒子在急剧转向时会对炉壁造成冲刷;研究炉型特殊结构加强了煤粉燃烧时的扰动,延长了煤粉粒子在炉内停留时间,锅炉具有较好的燃尽特性。模拟和试验结果可为700℃超超临界紧凑型锅炉技术实施及结构优化提供理论依据。

Computational fluid dynamics numerical simulation method was used to numerically simulate the combustion process in 700℃ ultra-supercritical compact swirl opposed coal-fired boiler.The velocity distribution,temperature distribution,component distribution,trajectory of pulverized coal particles and burnout characteristics of pulverized coal particles in the furnace were obtained through simulation.The results show that the velocity and temperature fields in the ultra-supercritical compact boiler are different from those of a typical hedge-swirling combustion boiler.in the middle of the flue,the combustion of pulverized coal particles is gradually completed,forming a regular temperature gradient.There is a certain temperature deviation on the left and right sides of the rear rising flue.The O_(2) concentration showed good consistency with the main gas products CO and CO_(2) concentration.Due to the existence of inertia,most of the pulverized coal particles are liable to scour the furnace wall when they are turned sharply.The special structure of the new furnace type strengthens the disturbance when the pulverized coal moves in the furnace,prolongs the residence time of the pulverized coal particles in the furnace,and makes the boiler have better burnout characteristics.The simulation and test can provide theoretical basis for the technical implementation and structural optimization of the ultra-supercritical compact boiler at 700℃.