Process for controlling the dosing of a sorbent

In a gas cleaning process a quantity of sorbent agent is dosed into a non-stoichiometric process. In the process, emission concentrations are measured at short, regular intervals. The difference between the measured median value over the period of observations and the emission concentration target value, is used as a regulating parameter for further introduction of sorbent agent. In a process in which several different emissions are simultaneously monitored, the median value used is that which has been obtained over the longest period of observations.