数值模拟方法测量和标定中速磨煤机直吹式制粉系统一次风量

建立了中速磨煤机直吹式制粉系统一次风管道的数值模型,利用FLUENT软件模拟了其内部湍流流场.结果显示,国内许多电厂由于系统布置过于紧凑,一次风量测量元件前后的直管段长度太短且冷一次风从侧面吹入,造成测量元件位置处的流场处于紊乱、无规律的状态,单点测量不具有整个截面的代表性,从而使得一次风量的测量极不准确且线性度较差....

Measurement and Calibration of Primary Air for Pulverizing System with Medium Speed Mills by Employing Numerical Simulation Method

The numerical model is built for the primary air duct of the pulverizing system with medium speed mills,and the inner flow fields are simulated by employing the commercial code of FLUENT.The simulated results show that the lengths of the straight duct infront and behind the measuring element are too short to meet the requirement of the flow rate measurement of the primary air due to the compact design in many domestic power plants.The actual flow at the cross section where the measuring element installed is irregular and disorder and the air velocity obtained by the single measuring element is not the area-weighted average value.The blowing of cool primary air also aggravates the disorder of the flow fields.It is concluded that the flow rate of the primary air can not be measured precisely.The numerical simulation method could be adopted to measure and calibrate the flow rate of the primary air,which can avoid the limitations of the existing method.This solution could improve the precision and reduce the cost of the measurement,which will be a good alternative for the domestic power plants.