Process and device for cleaning furnace gas includes flowing in a main flow direction (A) the furnace gas passes an array of bag filters. Filtered furnace gas having passed the filter bags, is partly returned via one or more nozzles which are moved along downstream ends of the bag filters. Each bag filter is passed at least once by at least one nozzle during a cycle. A nozzle passing a bag filter blows filtered furnace gas in a backflow direction (B) through said bag filter. The backflow direction is opposite to the main flow direction.