Abstract: An axial air movement fan having a plurality of variable pitch fan blades (2), extending radially from a hub (4) rotatable about a main axis (3), each blade (2) further being pivotable about its radial axis to vary the blade pitch. The blades (2) each are mounted on an associated bearing (5) mounted on said hub, the bearing comprising a ball bearing having a first radially inner race (25) fast the blade (2) and a second radially outer race (26) rotationally fast to the hub (4). The balls (14) in the bearing are separated by separators (15), each separator being generally cylindrical and having its cylindrical axis coaxial with the orbital axis (22) of the orbit of the balls (14) and being adapted to rotate about the said orbital axis (22), the side faces of the separator each having a part spherical recess (16) adapted to receive a ball (14).

Abstract: Ventilation system (10) comprising resistive heating means (12) for heating gas flowing through the ventilation system (10) and means that are arranged to provide a 5 controlled, continuously variable AC voltage/current to at least part of the resistive heating means (12) of the ventilation system (10) to modulate the power (24) being supplied thereto and to enable continuous regulation of the temperature of gas flowing through the ventilation system (10).

Abstract: Methods and apparatus are provided, which separate out at least a portion of fine dust, including fluoride, from recycled alumina. The difference in natural drop velocity and flow properties of fine and coarse particles is used to effect the separation.

Abstract: A filtering apparatus for an air treatment apparatus (5), a superior purity of the filtered air being required. The apparatus has a plurality of filter cartridges (3), provided with filters (2) and inserted into one cassette (4) each. The cassettes are fastened in the air treatment apparatus and the filter cartridges (3) have, on their side, which is turned towards the incoming air stream, a seal (6), which extends in an axial direction and around the periphery and axially abuts a surface, which is oriented radially in relation to the air stream and the apparatus or the like respectively and which surrounds an outlet opening (9), defined by each filter cartridge.

Abstract: A method and an apparatus for cleaning flue gases with particulate slaked lime are described. In the method, burnt lime is dry-slaked with water to a moisture content of at least 5% by weight, and the slaked lime is contacted with the flue gases within 1 minute of the slaking. Preferably, the slaked lime is mixed with recirculated powdered lime from the flue gas cleaning before contacting it with the flue gases.

Abstract: A decentralized cleaning plant for dry cleaning by removing fluorine containing waste gases from a reduction process in several electrolytic cells for aluminum, comprising: a storing place for aluminum oxide; a transportation system to distribute aluminum oxide from the storing place to the decentralized cleaning plant, a filter portion to store aluminum oxide before and after use in the decentralized cleaning plant; and an exhaust fan integrated with a top filter part of the plant, wherein a chimney and a separate silo are not required.

Abstract: The invention relates to an electric filter which comprises emission and separation systems, which are intended for separating particles from a gaseous, particle-containing medium passing through the electric filter, and a filter chamber (1) which surrounds the emission and separation systems and their peripheral devices, the filter chamber (1) comprising a top structure (2), a base structure (3), and a wall structure (4) provided with thermal insulation and sheet metal cladding. The base structure (3) is made of concrete or the like and comprises at least one trough or hopper bottomed tank (5) for separated particles, the wall structure (4) is made of steel and attached to the base structure (3) with a substantially rigid joint (6). The wall structure (4), except for the rigid joint (6), is provided to allow thermal expansion and contraction.

Abstract: A process and an apparatus in black-liquor evaporation for the selective removal, by liquid absorption, of hydrogen sulphide from the generated gas (3) containing hydrogen sulphide as well as carbon dioxide, an disclosed. In the process, the gas is counter-currently brought into multistage contact, preferably comprising three stages (6, 7, 8), with circulating carbonate-containing alkaline solutions, preferably sodium carbonate solutions (25), the pH of which is adjusted during the absorption to about 9-12 by the addition of a hydroxide, preferably a sodium hydroxide solution (26, 27, 28). It is preferred that the gas flow is turbulent and the liquid flow is laminar when contacted with one another. The apparatus comprises a container (1) having a gas inlet (2), a gas outlet (4), and a packing (9) arranged in several successive stages (6, 7, 8).

Abstract: A filter unit for airtight attachment to a framework of a cleanroom ceiling includes a filter, a circumferential wall surrounding the filter, and a downwardly projecting sealing knife to be received in a sealant containing groove formed in said framework. The sealing knife includes vertical weldable wall elements interconnected by welding and mounted on the circumferential wall by airtight mounting means.

Abstract: A device for mixing particulate material and liquid includes a container, an inlet for the introduction of particulate material into the container, a liquid spraying device for spraying liquid over the particulate material in the container, a disc agitator arranged in the container, and an outlet for discharging material mixed with liquid from the container. A fluidization device is provided to fluidize the particulate material in the container during the mixing operation. The inlet is arranged at one lengthwise side wall of the container, so as to extend along that wall. The outlet is arranged in the other lengthwise side wall, so as to extend along the wall.

Abstract: A fan module for clean room applications, comprising outer, vertical restriction walls (5) with a lower edge part (6) having a planar lower surface (7) as well as an element (9) protruding from the outer edge of the planar lower surface for cooperation with a filter docking module (2) provided in a roof filter frame (4) having a substantially planar upper surface (8) with an extension corresponding to said planar lower surface, whereby said protruding element (9) is designed to overlap part of said filter docking module (2).

Abstract: A device and a method for achieving sound reduction within a frequency band in a transport system for gaseous medium, the transport system being arranged between an inlet, which is connected to a sound source, and an outlet. The transport system comprises with a plurality of interconnected channel parts (1-7) and exhibits at least one module (8, 9) comprising at least one reflection attenuator (4) with a resistive length (a2, b2) and at least one reactive attenuator (3) with a reactive length (a1, a3, b1, b3). The resistive length is brought to constitute a quarter of a wavelength of the center frequency of the frequency band and the reactive length is brought to constitute a quarter of a wavelength of a frequency between, respectively, the lower and upper limit frequencies of the frequency band.

Abstract: A beam construction for ceilings in clean rooms, comprising first (1) and second (2) beams. The first and second beams are arranged essentially horizontally and perpendicularly to each other and have longitudinal ducts (7) for receiving a liquid or viscous sealant. In order to facilitate mounting and increase the flexibility of the beam construction, a transition piece (12) is arranged between two beam elements (1a, 1b) which are arranged successively in the longitudinal direction, thereby forming an opening (14) in at least one side-limiting duct wall (6) of the first beam (1). A second beam (2) is arranged sealingly against the transition piece (12) and the first beam elements (1a, 1b) arranged on each side thereof, such that the ends of the duct walls (6) of the second beam encompass the thus-formed opening (14).

Abstract: A blowbox for use in a plant for drying a material web includes an essentially horizontal box wall having formed therein circular orifices and eyelid perforations each of which includes a slit extending in parallel with the center line of the upper box wall. A depression is formed m the upper box wall adjacent one side of the slit. The eyelid perforations are arranged in two rows and parallel with the center line and together they form a zigzag pattern about the center line that intersects the depressions of the eyelid perforations in both rows. The orifices are disposed in a first and second pair of rows with both rows in each pair positioned on either side of and spaced equally from the center line. The upper box wall has a shallow continuous arcuate shape across its entire width.

Abstract: A method and apparatus for separating dust from hot process gases. The process gases are passed via a gas inlet duct through a dust separator, in which dust is separated from the process gases, part of the separated dust being conducted to a device for agglomeration of the dust. Subsequently, part of the separated dust is recirculated by being introduced into the process gases in the gas inlet duct. Liquid is added to the dust in the agglomeration device in such an amount that the relative humidity in the process gases cleaned in the dust separator is higher than 30%, preferably 40-60%.

Abstract: A method for cleaning process gases is provided, in which a sorbent is supplied to the process gases for reaction with gaseous pollutants that are present therein, thereby forming particulate reaction products which are separated in a subsequent particulate separator, and in which the moisture content and temperature of the cleaned process gases are measured to determine the relative humidity of the process gases and the concentration of at least one of the gaseous pollutants in the cleaned process gases is measured, wherein the relative humidity of the process gases is increased from a substantially constant basic level (BL) to an increased level (IL) and the amount of sorbent supplied to the process gases is increased when the concentration of at least one gaseous pollutant in the cleaned process gases exceeds an upper limit value (UL), and wherein the relative humidity is decreased back to said basic level, after a period of time and/or when the concentration of at least one gaseous pollutant in the cleane

Abstract: A device for cleaning filter elements, such as filter bags, having upper open ends, in a filter installation for filtering polluted gas. The gas passing, during operation, from the outside and through said filter elements, in which installation filter elements are juxtaposed in a plurality of essentially parallel rows. The device includes an essentially horizontal distribution pipe, which extends essentially in parallel with the rows of filters elements and is adapted to be connected to a pressure medium source via a valve. The device further includes a plurality of nozzle elements, which are connected to the distribution pipe. The nozzle elements are adapted to direct pressure medium pulses into the upper open ends of the filter elements in at least two juxtaposed rows of filter elements.

Abstract: The device relates to a wood drying plant comprising a wood drying device and a purifying device which is arranged to receive a drying gas from the wood drying device, the drying gas comprising water steam and volatilized organic components such as terpenes, and to purify the drying gas from organic components and to recover the latter. The purifying device comprises at least one condenser which is arranged to separate relatively difficultly volatilized components containing organic components and relatively easily volatilized components. The purifying device also comprises a separating device which is arranged to separate said organic components and a rest material from the relatively difficultly volatilized components. The purifying device also comprises a transferring device which is arranged to transfer organic components present in the rest material to the drying gas introduced in the purifying device.

Abstract: A device in an electrostatic precipitator for suspending, controlling and rapping one or more collecting electrodes arranged essentially vertically in one or more substantially parallel rows includes, for each row, a substantially horizontally oriented carrier element, to which the upper ends of the collecting electrodes are attached, connecting elements which connect the carrier element to the casing of the electrostatic precipitator, a control arrangement for controlling the motion of each row of collecting electrodes in the transverse and/or longitudinal direction of the electrostatic precipitator, and a rapping mechanism for rapping the collecting electrodes of each row. The rapping mechanism includes a rapping device, such as a rapping hammer, and an anvil connected to the carrier element.

Abstract: A cyclone for treating a gas flow (F) containing dust comprises a cyclone chamber (1) of circular cross section and having a vertical axis, and a central tube (7) of circular cross section, which is coaxially arranged in the upper portion of the cyclone chamber (1). An elongated insert element (10), which is vertically inserted in the central tube (7), is so designed and extends in such a manner downwards in the central tube (7) from the upper end thereof that a circumferential gap (17) exists between the insert element (10) and the central tube (7). This gap (17) has a preferably constant cross-sectional area which does not increase in the direction of the gas flow.