热一次风掺混调整送粉温度系统热力特性数值模拟

Numerical simulation on thermal performance of feed coal system increasing the pulverized coal temperature by mixing with hot primary air

针对某中速磨煤机入口调温冷风流量大且磨煤机出口风温受轴承许用温度限制无法提高的问题,提出了采用热一次风掺混调整送粉温度的解决方案。利用商用EBSILON软件对该系统投运后掺混热风比例对磨煤机入口风温、调温冷风流量、锅炉排烟温度、磨煤机风环风速、磨煤机出口风速和掺混后粉管风速的影响规律进行了模拟。结果表明,在不影响磨煤机正常运行的情况下,热一次风掺混调整送粉温度方案可大幅减少磨煤机入口调温冷风流量,从而降低锅炉排烟温度,提高粉管温度和风速,具有一定的节能效果。该模拟结果可为同类系统改造提供理论依据。

For a mid-speed coal mill system,the cold air flow is very high while the temperature at the mill exit can＇t be increased clue to the bearing temperature＇s limiting. Therefore, a hot primary air mixing with air-coal mixture system is presented. Thermal simulation is conducted for this system using the commercial EBSILON software. The air temperature at the mill entrance, cold air flow, flu gas exit temperature, mill vane velocity, mill exit velocity, and air-coal velocity after mixing with hot primary air are all simulated. By using the system presented in this paper,the cold air flow decreases,the flue gas exhaust temperature decreases, and the air-coal mixture＇s velocity and temperature after mixing with hot primary air increase as the mill almost running under the original condition. Based on the simulation results, the hot primary air mixing with air-coal mixture system is technical practicable.