Patent ID: 8181451

Claim:
A method of controlling feeding of a reducing agent, such as urea or ammonia, to a selective catalytic reduction reactor which is operative for removing NOx from a process gas of a process plant, such as a combustion plant or an incineration plant, said method of controlling the feeding of the reducing agent comprising the steps of: estimating an estimated present value of at least one predetermined parameter comprising a mass flow of NOx in the process gas at a location upstream of the selective catalytic reduction reactor indicative of an amount of NOx that needs to be removed from said process gas in the selective catalytic reduction reactor, estimating a rate of increase of said at least one predetermined parameter, and increasing, when said estimated rate of increase of said at least one predetermined parameter is positive, an amount being supplied of said reducing agent to a higher value than would be the case if said at least one predetermined parameter were to be kept constant at the estimated present value thereof.