电站锅炉冷热一次风道改进及一次风流场均匀性分析

Improvement of Primary Air Duct and Uniformity Analysis of Primary Air Flow Field for a Power Plant Boiler

为了解决安徽淮南某电厂中速磨煤机前一次风道动压、静压和温度分布不均造成一次风量测量不准的问题,对冷一次风道加装混流器和在混合段弯头加装导流叶片,利用数值模拟软件FLUENT,采用Realizable k-ε湍流模型对该厂4种工况(40%THA、50%THA、75%THA和100%THA)下一次风道内流动进行模拟,根据传递误差公式分析动压和温度均匀性对风量测量的影响。结果表明:一次风道经过改进,4种工况下动压相对标准差在40%THA时最大降低5.1%,在50%THA和100%THA最小降低3.1%;温度相对标准差在40%THA时最大降低3.8%,在100%THA时最小降低1%;4种工况下测量面的动压和温度均匀性都有所提升;流量的传递误差在50%THA时最大降低0.902 kg/s,在40%THA时最小降低0.377 kg/s,检测点处流量偏差除40%THA减小不明显外,其他3种工况减小显著。

In order to solve the problem of inaccurate measurement of primary airflow of the primary air duct of the medium speed coal mills in a power plant of Huainan,Anhui Province,caused by the nonuniform distribution of dynamic pressure,static pressure and temperature,a mixer is added to the cold primary air duct and guide vanes are installed at the elbow of the mixing section.Numerical simulation software Fluent and Realizable k-ε turbulence model are used to simulate the primary air duct of the power plant under four working conditions and the distribution of the flow in the primary air duct is analyzed.The four common working conditions are 40%THA,50%THA,75%THA,and 100%THA.The simulation results show that the dynamic pressure and temperature uniformity of the measuring surface have been improved under four working conditions after the primary air duct been improved.The relative standard deviation of dynamic pressure is reduced by a maximum of 5.1% at 40%THA and a minimum of 3.1% at 50%THA.The relative standard deviation of temperature is reduced by a maximum of 3.8% at 40%THA and a minimum of 1% at 100%THA.The flow transfer error is reduced by a maximum of 0.902 kg/s at 50%THA and a minimum of 0.377 kg/s at 40%THA.The flow deviation at the detection point is significantly reduced under the four working conditions except for the 40%THA.