Study on flow mixing and equalizing technique of primary air  at inlet of medium speed coal mills

Abstract

Abstract:

The measurements of the primary air flow rate and air temperature of medium speed mills in a 600MW unit are usually not accurate.Therefore control systems of boiler load, air flow rate,air temperature and burning load cannot work automatically.By CFD numerical simulations, 3 sets of coldhot primary air flow mixing and equalizing devices are designed.Comparing their currentsharing effects, all the coalhot primary air flow mixing and equalizing devices above can satisfy the measuring requirement on uniformity of flow field and temperature field at the measuring section, can eliminate the vortex, can adjust the deflection of airflow in the rectangle primary air duct, and can make the incoming air direction on the measuring section be vertical to the detecting device. The relative standard deviation of the air velocity and air temperature drop to 6% and 2% respectively.The total pressure losses of primary air are less than 300Pa.The average velocity and temperature at crosssection of scheme 3 is of the smallest relative standard deviation,and its current sharing effect is optimal.

Key words:

medium speed coal mill, primary air, measurement, flow field, temperature flow, numerical simulation, uniformity

WANG Zhoujun1,2，LI Xinghua2，TANG Lijun1，DUAN Quansheng2.

Study on flow mixing and equalizing technique of primary air at inlet of medium speed coal mills

[J]. Huadian Technology, 2019, 41(5): 17-21.

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Study on flow mixing and equalizing technique of primary air at inlet of medium speed coal mills

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