DEVICE AND METHOD FOR CONTROLLING THE FUEL-AIR RATIO DURING THE COMBUSTION OF GROUND COAL IN A FIRING SYSTEM OF A COAL-FIRED POWER PLANT

摘要

The invention relates to a device and method for controlling the fuel-airratio during the combustion of ground coalin the firing system of a coal power plant, which comprises means for thepneumatic delivery of ground coal to the burners of thefiring system of the coal power plant and means for feeding combustion air tothe burners or into the firing chamber of the firingsystem of the coal power plant and in which the amount of combustion air andthe amount of carrier air is controlled. The aim ofthe invention is to achieve a high reliability of the control combined withlow maintenance of the air mass measurement devicesfor measuring the amount of combustion air and carrier air. According to theinvention, this aim is achieved by a measurement devicefor measuring the amount of combustion air which, according to the correlationmeasurement method, evaluates the triboelectriceffects on sensors which are arranged in series in the direction of flow ofthe combustion air and thus measures the flow velocityof the combustion air. To this end, between 0.1mg and 10mg of fine-grainedparticles havinga particle diameter of between 20 µm and 200 µm are introduced per m3air into the suctioned fresh air. The introduction of particlesinto the suctioned fresh air is carried out essentially during the startingphase of a firing system of a coal power plant. The measurementof the amount of carrier air is preferably carried out by means of acorrelation measurement device that evaluates the triboelectriceffects on sensors which are arranged in series in the carrier air stream inthe direction of flow of the carrier air.