Abstract: A method and apparatus for cooling the exhaust gases from a molten phase furnace, such as a smelting furnace. The exhaust gases are conveyed from the furnace to a vertically extending cooling shaft disposed above the furnace, where the exhaust gases are indirectly cooled by means of a cooling gas in a circulating system. From the cooling shaft, the exhaust gases are conveyed to a waste heat boiler, where heat is recovered from the exhaust gases as saturated or superheated, pressurized steam.

Abstract: A method and an apparatus for separating heavy impurities from a fiber suspension include a centrifugal pump capable of separating heavy impurities towards the periphery of the interior chamber of the pump. The fiber suspension is caused to rotate in the interior chamber so as to urge the suspension downstream as well as separate the impurities towards the periphery of the chamber where they can be collected.

Abstract: Hot flue or process gases are cleaned utilizing an apparatus containing a barrier filter module formed of a monolithic ceramic support structure coated with a thin porous ceramic layer having a pore size of about 0.04-0.5 microns, and a catalyst module formed of a support structure coated with catalyst. The hot flue gases may be associated with a fluidized bed boiler plant, such as a circulating fluidized bed reactor. Gases to be cleaned are passed through the barrier filter module into contact with the thin porous ceramic layer, and then through the catalyst module so that there is a catalytic reaction with the gas.

Abstract: A method which provides purification of waste gases by adding particles of reagent and/or absorbent, which react with the pollutants in the waste gases, to the gases, and by introducing the gases into a wetting reactor for activating the reagent or absorbent contained in the gases. Gases are conveyed to at least two levels in the reactor through inlets so that a first portion of the gases is introduced into a wetting zone and a second portion of the gases below the wetting zone. A high density of particles is maintained in the wetting zone by recycling to the wetting zone particles separated from the gas above the wetting zone.

Abstract: A deaeration vessel has a partition wall dividing the hollow vessel body into first and second portions, and defining a weir with a top surface establishing the level of pulp suspension in the vessel body. Turbulence in the deaerated pulp is minimized by providing the outlet for deaerated pulp immediately adjacent the partition wall, in the bottom of the vessel body first portion (on the same side of the weir as the inlet conduits for the suspension being deaerated). The weir is preferably configured so that the top surface, defining the liquid level within the vessel, overlies the outlet. A partition wall may extend substantially linearly at an angle of about 60.degree. to the bottom of the vessel, or it may have a vertical bottom with a top extending at an angle to the bottom, or it may be continuously curved from the vessel bottom to the top surface, about a horizontal and/or vertical axis.

Abstract: A turbulence roll for a web former. The roll generates high frequency small-scale vibration in the stock on the forming fabric whereby fluidization of the partially formed fiber mat and dispersion of fiber flocs in the stock is brought about. The turbulence roll is formed of a shaft on which a plurality of discs (32) is disposed a distance apart from each other and a plurality of lengthwise extending rods (34) is attached to the rims of the discs and spaced apart from each other.

Abstract: A fluidized bed combustor or gasifier has a combustion chamber(s) with a non-symmetrical horizontal cross section. The chamber may be trapezoidal, hemispherical, or may have five or more side walls of at least two different lengths. The walls of the combustion chamber may be water tube panels. An external pressure vessel surrounds the combustion chamber(s) and associated particle separator(s), and may be spherical or cylindrical.

Abstract: A filter assembly for high temperature gases, such as from a circulating fluidized bed reactor, mounts monolithic ceramic filter elements within an upright vessel so that as the hot gas flows from the top toward the bottom of the vessel the gas passes through the elements with the clean gas discharged through a side wall of the vessel. The particle discharge is provided at the bottom of the vessel. Filter supporting elements within the vessel are cooled by cooling fluid, and pulse cleaning elements are associated with each of the filter elements. Flow directing elements within the vessel typically define a generally conical or pyramidal shaped flow directing surface. The flow directing elements may be refractory material bodies, or funnel shaped thin elements (e.g. of metal capable of withstanding high temperature), and may be mounted so that small amounts of movement are possible to accommodate thermal contraction or expansion.

Abstract: A centrifugal separator for separating particles from gases is a vortex chamber composed of cooling planar plates or panels (i.e. they are distinctly non-cylindrical), having at least one gas inlet, at least one gas outlet and at least one outlet for the separated particles. The cross section of the side walls of the vortex chamber forms a distinctly non-circular gas space (e.g. a polygonal cross section), have a circularity of greater than 1, e.g. .gtoreq.1.1, and preferably .gtoreq.1.15. One or more vertical, parallel gas vortices may be created in the vortex chamber, the gas introduced into vertical narrow slots. The outlets for separated particles are not on the same symmetrical axes as the outlets for purified gas. Two adjacent vortices may be provided in a common rectangular chamber. The separator is preferably in conjunction with a circulating fluidized bed reactor.

Abstract: To decrease the sulfur emissions of a sulfate cellulose mill, black liquor is heated before the last effect of the evaporation at a temperature higher than the cooking temperature of the sulfate cook and the sulfidity of white liquor is adjusted by adjusting the temperature and/or retention time of the heat treatment so that a predetermined amount of sulfur compounds are separated from the gaseous black liquor. Preferably, the sulfur containing gas is thereafter divided into different fractions and separately combusted.

Abstract: Method and apparatus for treating gases issuing from a pressurized gasification or combustion plant of solid fuel prior to leading the gases into a turbine. The hot gases are first cleaned in a particle separator, whereafter they are introduced int a centrifugal separator, which is disposed immediately in front of or in connection with a combustion chamber of the turbine. Cleanliness of the gases is ensured by the centrifugal separator. Air is mixed with the gases for bringing about additional combustion and for raising the temperature of the gases to a level >1000.degree. C.

Abstract: Method and apparatus for treating a gas containing aqueous fiber suspension in a fiber line process of a pulp mill including at least one of pulp screening, washing and bleaching includes (a) transferring the gas containing fiber suspension at a consistency to a treatment station; (b) treating said fiber suspension at the same level by removing a portion of the water from the fiber suspension so as to generate aqueous filtrate and treated fiber suspension having a relatively higher consistency; (c) simultaneously pumping and degassing the filtrate at the same level; and (d) pumping the treated fiber suspension having the relatively higher consistency away from the treatment station at the same level by imparting to the treated fiber suspension sufficient shear force so as to render the fiber suspension pumpable.

Abstract: A hydrocyclone is provided with a wear monitoring element of the type of a tube (24) or the like embedded in the wall section of the shell of the hydrocyclone. When the furrows worn by abrasive fraction of the cyclone are deep enough to reach the monitoring element, the wear causes a visually observed leak or some other signal alerting the operating personnel to the need of replacing the partly worn hydrocyclone.

Abstract: A method and apparatus for fibrous suspensions in the wood processing industry and more specifically to a so-called drum cylinder, the basic construction of which comprises a vessel, into which suspension being thickened is supplied and a wire-surface cylinder rotating in the vessel. The drum filter is characterized in that the closure member of the drum filter has a channel for leading gas from the filtrate tubes through the compartments of the distribution chamber to the outside of the closing member. The method is characterized in that the operation phase of the filter cylinder is divided into five separate stages. In the first stage, when the cylinder descends on to the vessel, air and the initial filtrate are discharged from the filtrate components and the formation of the pulp web on the wire surface begins. In the second stage, filtrate is discharged with vacuum and the formation of the pulp web continues.

Abstract: Apparatus and method for evaporating a liquid includes a casing; a plurality of vertically extending plate-type heating elements within the casing, each heat element having an outer surface and an inner surface and a vertical edge, the heat elements being spaced and forming an open channel along the vertical edge between adjacent elements; a distributor above the heating elements for distributing the liquid over the elements; an inlet connected to the heating elements for introducing a heating medium and for generating vapor from the liquid; and a wall-like device mounted within the casing facing the spaces between the heating elements for collecting and guiding the vapor generated in the evaporator. Preferably, the wall-like element includes a droplet separating device formed by vertically elongated spaced elements having a substantially U-shaped cross-section with inwardly pointing vertical edges.

Abstract: A method for roasting sulphide ores or ore concentrates containing precious metals is practiced in a furnace, typically in a fluidized bed. The ore and a sulphur-binding lime-containing material are supplied to a roasting furnace in which the ore is roasted with the emission of heat and sulphur dioxide. The lime-containing material--such as calcium hydroxide--is mixed into the cooling water for the roasting furnace and sprayed into the furnace as a lime-containing aqueous slurry. Roasting occurs at about 600-850.degree. C. (e.g. 650-750.degree. C.).Roasted material is discharged from the furnace and acted upon to recover gold, silver and copper metal.

Abstract: A falling film evaporator includes a chamber having a top and bottom tube plate; a plurality of vertical tubes each having an interior and exterior surface and extending through the chamber and being supported by the top and bottom tube plates; an inlet at the chamber for feeding heating medium into the chamber; a distributor above the tubes for feeding liquid to be evaporated into the tubes and for causing the liquid to be distributed as a falling film along the interior surface of the tubes so as to evaporate the liquid and generate vapor as the liquid passes in heat exchanging relationship with a heating medium present at the exterior surface of the tubes; a vapor space defined by a circumferential wall below the tubes; a plurality of vertically elongated spaced elements having a substantially U-shaped cross-section with inwardly pointing vertical edges for receiving the evaporated liquid and the vapor, the elements being arranged in a circumferential wall below the tubes within the vapor space spaced from

Abstract: Particulate material is separated from high temperature gas using a number of elongated porous walled tubular filter elements. The dirty sides of the filter elements are operatively connected to a dirty gas inlet to an upright vessel, while the clean side of the filter element is in operative association with a clean gas outlet. A separated particle outlet extends from the bottom of the vessel. Cleaning of the filter elements takes place by a pulse of high pressure cleansing gas which is supplied to the clean side of the filters. In order to prevent thermal shock or mechanical damage to the filters, especially since the cleansing gas is of a lower temperature than the gas being filtered, the volume of cleansing gas is positively controlled. This is accomplished by placing a restrictor (e.g. orifice or nozzle) between the high pressure source of cleansing gas and a reservoir having a volume sufficient to effect cleansing, but insufficient to cause thermal shock.

Abstract: A method of separating an aqueous solids containing suspension includes (a) subjecting a first solids containing suspension to centrifugal forces so as to separate the suspension into a first gas containing flow, a second gas-free flow and a third flow; (b) feeding the third flow into a flotation cell having a bottom; (c) introducing air at the bottom of the flotation cell into the third flow for separating from the third flow a fourth partial flow; (d) withdrawing the air containing third flow after the separation of the fourth partial flow from the flotation cell; and (e) subjecting the third flow to the centrifugal forces of step (a).

Abstract: Nozzles are provided for spraying a wetting medium into the gas flow in an activating reactor. The nozzle comprises a nozzle body having a plurality of nozzles The nozzle body is surrounded by a flexible and/or porous casing and a conduit introduces a gaseous medium into the casing. The gas can be introduced in either pulses or continuously. The gas introduced in pulses causes the casing to change its form and, where a perforated or porous casing is used, the continuous gas flow forms a protective gas film around the casing, thus removing the solid material accumulated on the casing.