Abstract: A process for recovering sodium citrate from a solution utilized in an absorption/stripping process for SO.sub.2 recovery, which involves cooling a portion of the stripping solution to precipitate sodium sulfate, which is separated from the mother liquor. Thereafter, the mother liquor portion is subjected to an evaporative crystallization to precipitate sodium citrate, which is reintroduced along with fresh absorbent solution into the SO.sub.2 absorption/stripping process.

Abstract: In a plant of making a blanket from fibres which are thrown or set together with polymerizable binder particles or droplets onto a perforated conveying belt, a method of cleansing consisting in: associating means for sucking air loaded with fibre dust and binder particles or droplets with means for spraying a washing liquid to be processed afterwards, providing, below said conveying belt, series of Venturi nozzles with throats of adjustable cross-section, opening into a duct connected to suction means, and distributor manifolds for spraying said washing liquid at low pressure, positioned on the one hand at the inlets of said Venturi nozzles and on the other hand downstream of the outlets thereof to provide a streaming of liquid onto all the walls of the dust removing ducts or means on which dusts and binder are likely to settle down.

Abstract: A method of controlling the cleaning process for the cleaning of textile barrier filters, for example bag filters, subsequent to dust precipitation on the filter material. The cleaning is carried out with a cleaning system (14) comprising means (16,17,18) for distributing compressed air pulses to the filter bags (4). The gas flow often shows great variations in flow, temperature and dust content, thereby giving rise to problems in the control of the cleaning process in such a manner, that neither over-cleaning nor under-cleaning occurs. For the control, the filter load v.sub.f is measured which is the ratio of the gas flow (m.sup.3 /s) and the filter area (m.sup.2), as well as the pressure drop p.sub.f over the filter material. In applications with great temperature variations of the gas, also the absolute temperature T is measured. The measuring results are processed in an electronic unit (26) for calculating the filter resistance S, which is the ratio p.sub.f /v.sub.

Abstract: A web is formed from particulate material, for example, wood fibers, by depositing the fibers on a conveyor surface in a distribution chamber. The particulate material is introduced into the distribution chamber at its top by a carrier air stream which is caused to oscillate across the surface by impulses from separate control blow boxes on the opposite sides of the stream. The particulate material is thoroughly dispersed in the air stream by passage through a transition zone where the carrier air stream is deflected into a zigzag path and its flow velocity is reduced. The effect of static electricity on the particles in the carrier stream is reduced by lining the transition zone with nonconductive material and providing ionizing devices in the blow boxes for the air flow passing through the control boxes, or in the chamber adjacent the boxes.

Abstract: For cleaning a flow of used air from a spray booth wherein articles are lacquered, a duct is provided with a first constriction where the flow of used air is brought into contact with washing fluid so as to wet lacquer particles in the used air. Downstream of the first constriction a guide conduit, which has a bend therein deflects the flow of used air and the washing fluid. The guide conduit is provided with a second constriction and after the flow of used air and the washing fluid have been deflected they pass through the second constriction, which is narrower than the first. Turbulence is thus created and the washing fluid is atomized and intimately mixed with the used air.

Abstract: In an axial fan having an impeller with settable blades and wherein the root end of each blade connects, via a bearing permitting rotation of the blade, to the outer end of a blade-attachment shaft extending substantially radially relative to the impeller, the blade-attachment shaft is rigidly connected at its inner end to an impeller hub. The blade-attachment shaft is abutted against the radial outer side of the hub and is pre-tensioned by compressing said shaft in the longitudinal direction thereof against said hub.

Abstract: A web is formed from particulate material, for example, wood fibers, by depositing the fibers on a conveyor surface in a distribution chamber. The particulate material is introduced into the distribution chamber at its top by a carrier air stream which is caused to oscillate across the surface by impulses from separate control blow boxes on the opposite sides of the stream. The particulate material is thoroughly dispersed in the air stream by passage through a transition zone where the carrier air stream is deflected into a zigzag path and its flow velocity is reduced. The effect of static electricity on the particles in the carrier stream is reduced by lining the transition zone with nonconductive material and providing ionizing devices in the blow boxes for the air flow passing through the control boxes, or in the chamber adjacent the boxes.

Abstract: Improved efficiency in recovering SO.sub.2 from waste gases is obtained in a system where the SO.sub.2 is absorbed into a solution which is then distilled. The method of this application entails compressing the steam-SO.sub.2 mixture issuing from the still before condensing out the steam, so that the heat from the compressed steam-SO.sub.2 mixture may be used in generating the steam for the still, and the condensate may be recycled through the still, preferably after reheating the same.

Abstract: A device for clamping a filter cassette in a filter housing. The filter cassette comprises a frame which releasably mounts a sleeve-type filter element having a common clean-gas opening at the top. The filter cassette slides into the filter housing to underlie a connecting frame and the clamping means operates to press the filter cassette upwardly against the clamping frame. The clamping member includes a pivoted actuator operable, when pivoted, to longitudinally displace rods on the opposite sides of the filter cassette. The rods have a V-shape recess which cooperates with support members so that when the rods are displaced longitudinally the support members rise out of the recess and elevate the rods to effect clamping of the filter element in place.

Abstract: In a device for causing contact between horizontally-flowing gas and vertically-flowing liquid, a stack of corrugated contact plates in face-to-face contact and having their corrugations inclined to the horizontal plane. Alternate plates of the stack are inclined upwardly in the direction of gas flow and the intermediate plates are inclined downwardly at the same angle of inclination. The upwardly-inclined corrugations have a smaller radius of curvature than the downwardly inclined corrugations. The heights of the respective corrugations are preferably equal and the radius of curvature in the upwardly-inclined corrugations is less than the height of said corrugations.

Abstract: Web material is carried on air to advance the material in a fixed stable floating position through one or more decks of a treating plant, preferably a drier. The air is supplied through pairs of apertures arranged in the upper surface of blow-boxes distributed in the conveying path of the material which apertures eject the air in pairs of streams facing away from each other. To reduce deflection of the material between said pair of apertures the space between said apertures is supplied separately with a great volume of secondary air of the same static pressure as that prevailing on the upper surface of the material, which secondary air is taken along by ejector effect by the primary air streams ejected from the apertures of the blow-boxes.

Abstract: In an electrostatic precipitator, the emitting electrodes consist of helically wound wire, and are extended and attached in the space between the collecting plates, and have a non-round cross-section. In each of the electrodes has a long axis approximately twice the short transverse axis in order to increase the mechanical strength against electric erosion and simultaneously maintain an optimum of current distribution (corona) from the electrodes.

Abstract: A web is formed from particulate material, for example wood fibres, by depositing the fibres on a movable deposition surface in a chamber. The particulate material is carried to the surface in an air stream to form a composite material flow which is caused to oscillate across the surface by impulses from separate control means preferably disposed on opposite sides of the stream. The control means is preferably opposed control flows which are caused to vary alternatingly between a minimum and a maximum impulse by use of one or more fluidistors. The fluidistors may be controlled by self-oscillation or by measuring the evenness of the particulate material deposited on the deposition surface. The control may also be effected by adjusting the walls of the chamber to utilize the coanda-effect. The particulate material may be admixed with additives from the control flow and may be charged electrostatically.

Abstract: A treatment plant for web material which, when bent, exhibits stiffness transverse to the direction of bending. The treatment plant comprises a series of blow boxes arranged in sections with the boxes in each section having parallel plane perforated surfaces on opposite sides of the web path. The perforations are graduated in degree with a high degree of perforation on one side of the web path being opposed by a low degree of perforation on the other side of the web path, and vice versa, so that the web assumes a wave shape between the first and second planes, the wave staying with its nodes in definite positions closer to the one plane opposite the highly perforated group in the second plane and closer to the second plane opposite the highly perforated group in the one plane.

Abstract: A ventilation element for example a valve is anchored in an opening in a ceiling or wall of limited thickness by means of a connecting piece in form of a cylindric pipe with a stop flange and equipped with a plurality of elongated, narrow wings of a resilient material and tangentially projecting from the shell surface and arranged to be pressed towards said surface momentarily during the insertion by a screwing motion of said pipe and then -- after final insertion -- said wings extending radially along one border line against the rear side of said ceiling or wall.

Abstract: The transfer elements of the rotor of a regenerative heat and humidity exchanger are made of a non-hygroscopic material, such as aluminum, the surface of which is treated to form a hygroscopic layer thereon. This provides the benefits in humidity transfer previously obtained with all-hygroscopic transfer elements such as paper, cardboard or asbestos, without the danger of fire in the use of paper or cardboard or the danger to health in the use of asbestos. Preferably the transfer element is of metal on which a hygroscopic surface layer is formed by oxidizing the surface by pickling and/or heat treatment, and preferably the oxide layer is impregnated with a substance, e.g. lithium chloride, to render it more hygroscopic. Preferably also, the layer is made more porous by acid treatment prior to oxide formation, and acid treatment may be used after the pickling process to arrest the pickling reaction promptly.

Abstract: A surface layer is formed on transfer elements of the rotor of a humidity and heat exchanger rotor, the layer not only being hygroscopic to provide the desired humidity transfer, but also serving as a bonding agent or cement for holding the transfer elements together in the desired rotor configuration. A preferred layer uses as a bonding agent a solution of cellulose acetate or nitrate in acetone, and with lithium chloride dissolved therein to produce the hygroscopic effect.

Abstract: In a method and apparatus for cleaning fabric filters of bag type or the like with a reverse flow of a gaseous medium improved cleaning action is achieved by applying the gaseous medium to the surface of the fabric opposite the dust-collecting surface in pulses which reach a high maximum value in as short a time as possible.