通风输送过程高浓度粉尘沉积特性

Deposition characteristic of high concentration dust in ventilation conveyer process

粉尘沉积是通风输送过程的常见现象,严重时常堵塞管路,本文以实验研究为手段,探讨高浓度粉尘在通风输送过程的沉积特性。得出水平直管内粉尘的沉积受风速主导,较大风速湍流强度大,边界层厚度薄,有利于外流区粉尘的悬浮和边界层内粉尘的再次悬浮;水平90°弯管内粉尘沉积具有区域性,弯头上游以有序沉积为主,弯头下游由于气流边界层分离产生了漩涡区使沉积量急剧减少,弯头外侧由于流动偏移对壁面的冲刷使粉尘沉积几率降低,而弯管内侧由于边界层分离和部分粉尘随气流的偏移使沉积量最小;水平三通管内粉尘沉积主要受支管角度与流速影响。通风输送高浓度粉尘的合适取值为：水平直管和90°弯管风速应不低于17 m/s,水平三通角度30°~45°,支管风速不超过主管。

Dust deposition, which blocks the pipeline in sometimes, is a very common phenomenon in ventilation conveyer process. The deposition characteristic of high concentration dust in ventilation conveyer process was discussed and studied in the present paper. The primary conclusions are as follows： In horizontal straight pipe the dust deposition are leading by airflow velocity. The greater airflow velocity the greater turbulence intensity and the thinner boundary layer thickness are. It contributes to the dust suspension in the external flow area and the secondary suspension of dust in the boundary layer. It has the regional characteristics of the dust deposition in 90~ bend. The orderly deposition of dust is the mainly action in upstream of bent. In downstream of bent, the deposition mass reduces sharply because of the whirlpool zone generated due to airflow boundary layer separation. In the outside of bent, the deposition ratio reduces relatively because of the airflow skewing which intensifies the airflow washing the wall of pipeline. However, in the inner side of bent, the deposition mass is the least because of the airflow boundary layer separation and the dust particles skewing along with the airflow. In the T bend, the dust deposition is influenced by the branch pipe angle and the airflow velocity. The suitable parameters of high concentration dust in ventilation conveyer are as follows： the airflow velocity of horizontal straight pipe and 90° bend pipe should be not lower than 17 m/s; and the angle of T bend pipe should be 300-45°, and the airflow velocity of branch pipe should be not exceeding main pipeline.