Process control

In a process for the removal and treatment of SO.sub.2 from a gas stream containing SO.sub.2, wherein the gas stream is contacted in an absorption zone with a liquid absorbent that is selective for SO.sub.2 to produce a SO.sub.2 -containing absorbent and a purified gas stream;

• the SO.sub.2 -containing absorbent is passed to a stripping zone and stripped to produce a regenerated absorbent and an SO.sub.2 -containing gas flow;
• and the regenerated absorbent is returned to the absorption zone, the improvement comprising, uniformizing the amount of SO.sub.2 in the SO.sub.2 gas flow by adjusting the flow of the SO.sub.2 -containing absorbent to the stripping zone in response to the output signal from a flow controller which compares the measured value of the rate of the SO.sub.2 -containing gas flow with a set value, the set value in turn being the output signal from an SO.sub.2 -concentration controller which compares a signal corresponding to the SO.sub.2 -concentration in the SO.sub.2 -containing absorbent with a set value for that concentration.