中心给粉旋流燃烧器气固两相流动的数值模拟

Numerical Simulation of Gas-particle Two Phase Flow Field for Swirl Burner

电厂采用的煤粉燃烧技术应达到稳燃、低污染、防结渣及防高温腐蚀的要求。中国电厂燃用煤的煤质偏差,煤种多变。在燃用这些煤的时候,锅炉的稳燃能力较低。针对这些问题,提出中心给粉旋流煤粉燃烧技术。由于燃烧器的气固流动特性对燃烧器的性能有很大的影响,利用可实现的k-ε和Lagrangian随机轨道模型对中心给粉旋流燃烧器的气固两相流动进行数值模拟,并将计算结果和三维相位多普勒测速技术(Phase-Doppler ane mometry,PDA)试验结果进行详细比较,计算值和试验值速度分布的趋势基本相同。计算和试验结果表明,在轴向方向产生了回流区,切向速度分布出现典型的Rankine涡结构,中心线附近区域的径向速度小。当颗粒的轴向速度衰减为0之后,颗粒的运动方向发生偏转,开始向后上方运动。颗粒迂回型运动轨迹延长了煤粉在回流区中的停留时间。

The power industry requires coal combustion techniques that show flame stability, no slagging propensity and high combustion efficiency that also meet pollution control standards. The quality of coal provided to Chinese power plants often fluctuates and is usually on the low side. Generally the flame from these coals is not stable. In view of these problems, the centrally fuel rich swirl coal combustion burner is proposed. Gas/particle flow of burner has great impact on the performance of the burner. By using realizable k-ε model and Lagrangian stochastic trajectory model, the characteristics of gas-particle flows near the new burner are obtained. The numerical results and experiment data are compared. The velocity distribution tendency of numerical results and experiment data are almost the same. The results of calculation and 3D phase-Doppler anemometry experiment indicate that there is a central recirculation zone near the burner. The distribution of the tangential velocities is a Rankine-type vortex. The radial velocities are low near the chamber axis. When the axial velocities of particles become 0 m/s, the direction of particles movement deflects radially. The trajectory is advantageous to increase the particle residence time in the burner central recirculation zone.