Abstract: The invention provides an installation for injecting a powdery material, particularly an adsorbent material, into a contact column--as a rule vertical--through which flows a stream of gas, more especially gas laden with polluting effluents which it is desired to fix on said material, this installation comprising means opening into the column for injecting fresh material and for injecting recycled material, that is to say material already having served for the same purpose, characterized in that said means comprise a number of nozzles (2) for injecting recycled material, spaced apart about at least one nozzle (1) for injecting fresh material, these nozzles being disposed in the column (3 or 4).

Abstract: A filter bag for a filter system, comprising a number of parallel channels embodied by interconnecting, along parallel assembly lines distributed over pocket length, two opposite side walls of the pockets. The side walls meet at the open end of the pocket; a frame is introduced into each channel, the frame having two substantially parallel members which extend in a plane perpendicular to the main direction of the pocket, such plane being equidistant from the two assembly lines forming the lateral boundaries of the particular channel concerned. At the bottom bag end near the bag end remote from the open end of the bag, the two substantially parallel members meet by way of a bottom member which is substantially perpendicular to the plane of the two substantially parallel members - that is which extends substantially in the main direction of the bag.

Abstract: At the outlet of the duct for the powdery material is provided a movable diaphragm where orifice is adapted to engage a clearing fixed pin when the flow rate of said material reaches a predetermined low threshold. Said diaphragm is controlled by clearance actuating means comprising a pneumatic jack adapted to be supplied with compressed air through an electro-valve whose control input is connected to the output of a flow detector.

Abstract: Flow divider for a powdery material, comprising a vertical duct supplied with said material. A knife with a separating upper edge is provided at the outlet of said duct to divide the inflow of said material into two outflows. At least one straight air passage is provided, lateral with respect to the vertical axis of the knife, between the inlets of two eduction chutes for said outflows. The level of said air passage is notably below that of said separating upper edge of the knife.