| 摘要 |
The invention relates to a device and to a method for controlling the fuel-air ratio in the combustion of ground coal in a firing system of a coal-fired power station, which comprises means for pneumatically conveying the ground coal to the burners of the firing system of a coal-fired power station and means for supplying air for combustion to the burners or into the furnace of the firing system of a coal-fired power station, and in which the quantity of air for combustion and the quantity of carrier air are controlled. Provided is a measuring device for measuring the quantity of air, said device comprising a correlation measurement device that evaluates signals generated by electrostatic induction on two sensors arranged one after the other in the air stream, in the airflow direction. An electrode having an electrode contour, which has an average radius (r m) with 0.1 mm<=T m<= 1.2 mm, is arranged in the flow direction of the air in front of the sensors at a distance that is larger than 1 x the inner width of the flow cross-section of the conduit conveying the air and smaller than 10 x the inner width of the flow cross-section of the conduit conveying the air in the region of the sensors in the flow cross-section of the conduit conveying the air. The counter-electrode, which acts electrically with respect to the electrode, is arranged in the flow direction of the air between the electrode and the sensors, and the electrode and the counter-electrode are connected to the poles of a high voltage source having a voltage (U) of 12 kV<= 5 U <= 20 kV. The electrode and the counter-electrode are connected to the high voltage source in particular only during the starting phase of the firing system of a coal-fired power station or at airflow velocities < 10 m/s or for checking purposes. |
