Method of operating a coal-fired steam generator

Method of operating a coal-fired steam generator, whereby crushed coal is fed via dust burners of the boiler with the combustion air, the method comprising controlling the combustion air supply, such that due to a knowledge-based computing model, a forecast for the NOx emissions of the steam generator is created, that is carried out a regulation of the supply of combustion air based on the predicted NOx emissions as a reference variable, wherein a fixed distance from a NOx limit value is maintained and the combustion is performed so that the air ratio is in the burner zone of the steam generator λ ≥. 1