Abstract: The present invention provides a process and a device for transport of gas in a main duct with more than two branch ducts wherein the gas is guided through the branch ducts (1, 2, 3, 4, 5, 6, 7, 8) and into the main duct (A) with a direction which is parallel to the direction of the flow in the main duct, while the gas in the branch duct at the inlet to the main duct is kept at a higher velocity than the gas in the main duct and the gas in the main duct is given an impulse, by utilisation of excess energy from the gas in the branch duct, for acceleration of the gas prior to introduction into the main duct.

Abstract: When cleaning a barrier filter, comprising a plurality of filter elements, of woven fabric of felt, arranged to separate particles out of a polluted gas, the filter elements are cleaned, separately or in groups, by pressurized air pulses, the frequency, the maximum pressure and the duration of which are varied in order to minimize, by an adjustment, the total emission of dust. The frequency and/or the maximum pressure and/or the duration of the cleaning pulses are varied for a group or a plurality of groups of filter elements. After each cleaning pulse, the maximum value for the instantaneous emission of dust, the emission peak, is determined and the emission peak is used, after cleaning a certain group of filter elements, for selecting the frequency and/or the maximum pressure and/or the duration of the cleaning pulses for this group of filter elements during continued operation.