弯管偏流导向浓淡燃烧器分离特性的数值模拟

Numerical Simulation on Separation Characteristic of an Elbow Bias-Oriented Rich-Lean Burner

针对电站锅炉低负荷时炉内稳燃效果不佳的情况,采用浓淡燃烧方式将煤粉气流分离以改善着火特性。采用RNG(重新标准化)k-ε模型和随机轨道模型模拟弯管偏流导向浓淡燃烧器内煤粉流动特性,以"浓度比"和"速度差"作为评价燃烧器分离特性的指标,考虑了分隔板长度、偏流挡块高度以及风速对煤粉分离效果的影响。计算结果表明:在燃烧器内加装距离弯头为D的分隔板、高度为D/4的偏流挡块并保证风速在23 m/s时,对提高燃烧器的稳燃性能达到最佳。将模拟结果与试验数据进行对比,结果基本一致,可为电厂浓淡燃烧器的改造提供技术支持。

Aiming at the situation that poor quality-ignition occurs occasionally in coal-burning power station, it was thought that the application of rich-lean burner was to change the igniting character through the control of pulverized coal stream direction. By the numerical simulation of the pulverized coal flow characteristics in an elbow bias-oriented rich-lean burner, adopting the RNG k-e and the stochastic track model, regarding the ＂concentration ratio＂ and ＂speed difference＂ as the standard of evaluating the separation characteristic of the burner,and at the same time considering the influence of the partition plate length,bias current stopper height and primary wind velocity on the separation effect of pulverized coal. The calculation results show that：Within the burner equipped with the partition plate distanced from elbow for partition of D and bias current stopper height of D/4 and meanwhile ensuring the primary wind velocity 23 m/s, it achieves the best combustion per- formance to improve the stability of the burner. The numerical simulation and experimental results were com- pared,the results were basically identical, so as to provide technical assistances for the practical application and improvement of the elbow bias-oriented rich-lean burner.