Patent ID: 8808434

Claim:
A gas cleaning system for removing, at least partly, mercury from a process gas, comprising: a control unit to control when a filtering surface of a filter of said gas cleaning system is to be cleaned of material collected thereon, said control unit further to receive a first signal of a measurement from upstream of the filter of at least one first parameter indicative of an amount of mercury to be removed in said filter and a second signal of a measurement of at least one second parameter indicative of an amount of material collected on said filtering surface, utilized for determining when the filtering surface should be cleaned, the control unit still further to compare a measured value of said first parameter to a mercury set point, to delay, when said measured value of said first parameter indicates an amount of mercury higher than an amount of mercury indicated by said mercury set point, the cleaning of said filtering surface as compared to a point in time suggested by a measured value of said second parameter, and to clean the filtering surface at a selected intensity when the measured value of the second parameter exceeds a first pressure drop set point when the measured value of the first parameter indicates an amount of mercury equal to or lower than the amount of mercury indicated by the mercury set point, and when the second parameter exceeds a second pressure drop set point with a higher pressure drop than the first pressure drop set point when the measured value of the first parameter indicates an amount of mercury higher than an amount of mercury indicated by the mercury set point, for increased mercury removal.