Abstract: An intermittently operated apparatus for cleaning dust laden gases has a gas-tight housing, a pair of spaced gas-permeable walls holding a filter bed consisting of granular filter material. A centrally located conveying pipe is mounted to the housing for regenerating the filter bed after a predetermined amount of operating time. A high electric potential is applied in the region of the filter bed for removing dust particles from the dust laden gas which is flowing through the permeable walls and the filter bed. From time to time, the gas cleaning mode is interrupted and the granular filter material of the filter bed is regenerated by fluidizing the same in the conveying pipe. A system comprising a plurality of such filtering apparatus always maintains one of the apparatus in a regenerating mode while the remaining filter devices are in gas cleaning mode. Thus, the simultaneous operation of cleaning and regenerating is accomplished. The use of a filter bed having a thickness of about 25 to 100 mm.

Abstract: A granular bed filter device comprising two gas-permeable walls bounding an annular filter bed disposed in a housing. The walls extend downwardly in a taper together and are inclined upwardly toward the central axis of the filter bed. A nozzle tube projects from above into the housing and has nozzles which are directed against the inner wall of the filter bed. In order to regenerate the dust-laden filter bed, compressed air is blown intermittently through the nozzle tube while at the same time the nozzle tube is set in motion by a motor. The accumulations of dust contained in the filter bed are ejected in agglomerated form through the outer wall and fall down into the region of a discharging conveyor.

Abstract: A shell and two perforated cylindrical walls are radially spaced about a common vertical axis so as to define three coaxial spaces. A gas to be purified of suspended particles is admitted to the annular first space between the shell and a filter bed of granular material in the second space between the two perforated walls, and a purified gas is withdrawn from the third space. To clean the filter bed, granular material is conveyed from the lowermost portion of the second space through a conduit to a separating device above the topmost portion of the filter bed by a stream of conveying gas, and the gas entrains most of the particles from the granular material while the latter returns to the second space by gravity. The particle-laden conveying gas is introduced tangentially into the top portion of the annular first space where it is mixed with a scavenging gas passed through the filter bed from the third to the first space.

Abstract: The invention concerns the cleaning of the granulate filter bed material of a gas filter. The granulate material is contained in the spaces between two or more gas-permeable walls. The walls are designed as vertical tubes which may be cylindrical or consist of two cones with their bases together. The crude gas passes transversely through these walls from an outer chamber into an inner chamber from where it is led away as purified gas. A transfer pipe runs from the bottom of the filter bed to the top. A current of conveyor air is forced through the transfer pipe so that it carries the granulate material from the bottom to the top of the filter bed. At the top of the filter bed the conveyor air escapes through a gas-permeable hood while the granulate material falls into the space(s) between the gas-permeable walls, passes down between the walls and eventually reaches the bottom of the filter bed again.