压降法测弯管煤粉浓度中整流器性能数值模拟

Numerical Simulation of Rectifier Performance in Measuring Pulverized Coal Concentration in Elbow by Pressure Drop Method

煤粉浓度是表征输送管道运行状态的重要参数,电站锅炉输粉系统中弯头很常见。为了分析利用压降法测量弯管煤粉浓度时管道流场、整流器对弯管流速分布不均匀的改善效果及整流器的阻力系数,利用流体计算软件Fluent进行数值模拟研究。结果表明,Zanker整流器、非均匀整流器、AMCA整流器对速度不均匀分布的整流效果明显,不同整流器的整流效果不一样,从整流器后管道内速度达到充分发展管流所需直管段长度、整流器压力损失系数和磨损三方面综合考虑选择非均匀整流器。整流器压力损失系数也有差别并不和流通率呈正相关。整流器壁面形成动压高压区,形成的动压高压区压强与整流器流通率成正相关,高速的煤粉颗粒对整流器的冲击使整流器壁面磨损严重。

Pulverized coal concentration is an important parameter to describe the operation status of the pipeline, and the el- bow is common in coal conveying system of the utility boiler. In order to analyze the pipe flow field, the improvement effect of rectifier on uneven velocity distribution of bend pipe and the resistance coefficient of rectifier when measuring the concentration of pulverized coal in bent pipe by pressure drop method, numerical simulation is carried out by using the fluid calculation soft- ware Fluent. The results show that the rectifying effect of Zanker rectifier, non-uniform rectifier and AMCA rectifier for the uneven distribution is obvious, and the effect of different rectifier is not the same. By considering the factors of the straight pipe length to reach the speed of the full development of the pipe flow, pressure loss coefficient and abrasion, non-uniibrm rectifier is chosen. There is also a difference in the pressure loss coefficient of the rectifiers, which is not positively related to the flow rate. The dynamic pressure region is formed on the wall of the rectifier, and the pressure in the dynamic high-pres- sure region is positively related to the flow rate of the rectifier. The impact of the high-speed pulverized coal particles on the rectifier makes the wall of the rectifier seriouslv wear down.