Abstract: A centrifugal cleaner with a reject chamber (1) having a center dilution arrangement (3) with a dilution nozzle (4) to deliver dilution fluid to the reject chamber (1), and a reject outlet (7) at the bottom of the reject chamber (1). The dilution nozzle (4) points outwards to create a crossing outward flow of dilution fluid across an annular space (5) around the dilution arrangement (3) to slow circulating fluid flowing down from a cone (2) of the centrifugal cleaner to the reject chamber (1). The dilution arrangement (3) may have a clearing nozzle (6), directed against the reject outlet (7). The dilution nozzle (4) may be pointed below the bottom end (9) of the cone (2) and the dilution arrangement (3) may not extend higher than the bottom end of the cone.

Abstract: A system for automatic monitoring of smelt flow exiting a recovery boiler based on optical information. A processor is used to read at least one stationarily imaged video sequence, comprising digital image frames, including an area under examination representing at least part of the smelt flow exiting the recovery boiler. The processor is used to identify, in the area under examination, an area distinguishable based on colour and/or intensity information. The processor is used to determine, based on the identified distinguishable area, a monitored flow property of the smelt flow.

Abstract: A sealing arrangement for detecting thickness (t) of a sealing element (2) of a seal (1) wherein the sealing surface (3) at frontside of the sealing element (2) is arranged to be in sliding contact with sealed surface (4), wherein at least one sensor (5) measures the thickness of the sealing element (2) and is mounted to the surrounding component (10) of the sealed surface (4). The sensor (5) is positioned opposite the sealing element (2). The sensor (5) receives a response from a transverse border of the sealing element (2) or from an electrically conductive insert (6) or from an insert (6) of magnetic material, which insert (6) is embedded within the sealing element (2) or is connected to the backside of the sealing element (2). The thickness (t) is detected and/or measured along the length of the sealing element (2).

Abstract: An arrangement and a method for controlling a gas flow separated from a suspension of medium consistency pulp. The pulp is treated in a pulp treatment apparatus including a first pump and a second pump, wherein the second pump is a degassing centrifugal pump provided with a degassing system including a degassing conduit in which a degassing valve is arranged for regulating a pressure difference between an inlet of the second pump and the degassing conduit. The degassing system further includes a pressurized degassing vessel working under overpressure and having an inlet and an outlet, wherein the outlet of the vessel is connected to a pressure control valve for maintaining a desired overpressure in the vessel.

Abstract: A method to determine a reduction rate of a recovery boiler using optical information from a chemical smelt sample. A processor is used to read a digital frame at least part of which represents the chemical smelt sample of the recovery boiler. An area of interest is determined from the digital frame read comprising at least part of the area in the digital frame representing the chemical smelt sample. Of the pixel values of the area of interest, one or more spectral characteristic values correlating with the change of reduction rate are determined. The reduction rate of the recovery boiler is determined using a reduction rate function of one or more of the determined spectral characteristic values weighted at predetermined weights.

Abstract: An arrangement for installations of monitoring sensors of a vessel for treatment of lignocellulosic material, which vessel (1) has a central pipe (2) including at least one concentric pipe (3), mounted coaxially within the vessel (1). At least one sensor channel (4) is arranged along the outermost wall of the concentric pipe (3) of the central pipe (2) and that the at least one sensor channel (4) is connected to a cable conduit (5), which cable conduit (5) connects the exterior of the vessel (1) to the at least one sensor channel (4)) and the sensor channel (4) is several meters long and has plurality of holders (13) for sensors (11) and/or is configured to contain plurality of thermal sensors (11) with their cables (8).

Abstract: According to an example aspect of the present invention, there is provided a method for producing an oxidised lignin based high performance surface active agent in techno-economically feasible manner within kraft pulp mill without interfering the main process.

Abstract: A method for feeding a slurry of chips and liquid to a prehydrolysis reactor in the production of dissolving pulp. The slurry is pumped by using at least one pump to the reactor, and alkali is fed into the at least one pump 5 for adjusting the pH of the slurry to a range of 7-10.

Abstract: A method of treating fly ash containing sodium sulfate from a recovery boiler of a chemical pulp mill. This method includes at least the following steps: a) ash is dissolved in an aqueous solution and the pH of the solution is adjusted with alkali for precipitating impurities, b) the solution is filtered for removing the impurities containing precipitate, c) sodium sulfate is crystallized from the solution and the crystals are separated from the solution by filtering or by centrifugation, and d) the crystallized sodium sulfate is used as initial material for producing sodium and sulfur containing chemicals or as process chemical.

Abstract: A method for controlling discharges of nitrogen compounds in the production of cellulose carbamate (CCA). Microcrystalline cellulose is produced from chemical pulp produced at a pulp mill, such that the chemical pulp is subjected to acid hydrolysis at an elevated temperature to form microcrystalline cellulose (MCC) and hydrolysate, and the MCC is reacted with urea to produce cellulose carbamate whereby ammonia is released. The microcrystalline cellulose production and the cellulose carbamate production are integrated into the pulp mill having a flue gas system such that carbon dioxide from the flue gases is reacted with released ammonia to produce urea, which is used in the carbamate production.

Abstract: A transmission wheel assembled of at least two segments (1) on a shaft (12), the inner arc surface (3) of which and the shaft (12) have essentially the same radius (R), and which segments' (1) outer surfaces (9) have profiled surfaces that transmit the power of the transmission wheel. Between the segments' (1) welded-together end faces (4) there are gaps on those sections of the end faces (4) that are not welded, which creates a press fit between the shaft (12) and the inner arc surface (3) of the transmission wheel. The weld connecting the transmission wheel segments' (1) end faces (4) may be incomplete, meaning that it does not reach the shaft (12).

Abstract: A method of producing chemical pulp including at least the following steps: a) wood chips or other comminuted ligno-cellulosic fibrous material is treated with a polysulfide-containing cooking liquor in an impregnation stage at a temperature of 90-145° C., and b) slurry of fibrous material from step a) is heated into cooking temperature and cooked for producing pulp having a desired kappa number. After step a) mercaptide ions are added into the slurry of fibrous material and the fibrous material is treated at cooking temperature in step b).

Abstract: A separation device having a housing (10) with a feed conduit (1) and a reject conduit (2), between which conduits (1, 2) and an accept conduit (3) of the housing (10) is a rotor unit (13) having a shaft (4) transverse to the through-flow direction of the separation device, which shaft rotates discs (5) attached to the shaft (4), the outer surface and/or side surfaces of which discs are jagged, i.e. they have protrusions (6) and/or notches and/or these surfaces are substantially rough and the teeth (9) of at least two sieves (7, 8) attached to the housing (10), extend between the discs (5), the first sieve (7) being between the reject conduit (2) and the accept conduit (3) and the second sieve (8) being between the feed conduit (1) and the accept conduit (3).

Abstract: A screen assembly for a digester, impregnation vessel or other treatment vessel for separation of cooking liquor or treatment liquor from lignocellulosic material, typically in a form of chips, in the production of chemical cellulose pulp, which screen assembly includes a plurality of screen panels (17) of woven wire mesh cloth and attachment device configured to attach the screen panels to a support frame of the digester or vessel.

Abstract: A method of regenerating an activated carbon catalyst which is used in the production of polysulphide liquor. In the method, the catalyst is washed with a washing liquid in order to remove the sediment accumulated in the catalyst. According to the present invention, in this case, the activated carbon catalyst is regenerated most suitably by bringing it to a multi-stage washing which comprises at least one washing step in which the washing liquid used comprises sodium sulphide, and one washing step in which acidic washing liquid is used. The sulphur precipitate is peeled off using sodium sulphide, and the iron and other metals can be effectively removed by using an acidic washing, without damaging the catalyst.

Abstract: An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct comprising vertical flue gas channels, at least part of which is provided with heat recovery units for recovering heat from flue gases. The heat recovery units have a width of substantially the width of the flue gas duct, whereby downstream of the furnace the first flue gas channel is provided with a superheater. In addition to the superheater, the first flue gas channel is provided with one of following heat recovery units: an economizer, a boiler bank, or a reheater. The superheater and a second heat recovery unit are located one after the other in horizontal introduction direction of the flue gas, so that in a flue gas channel the flue gas flows in the vertical direction downwards and heats the superheater and the second heat recovery unit simultaneously.

Abstract: A method and an arrangement for generating process steam at a chemical pulp mill. Water is heated by subjecting it to an indirect heat exchange contact with steam in a heat exchanger. The water is heated with live steam produced in a steam boiler for generating process steam, whereby the live steam is condensed and the generated condensate is recovered. The process steam is subjected to a direct heat exchange contact with a material for heating the material. The water used for process steam production is obtained from secondary condensates, purified waste water and/or raw water. Process steam can be used in the treatment of cellulosic fibrous material, such as chips.

Abstract: An arrangement for burning lime mud into lime in a lime kiln. The lime mud flows counter-currently to flue gases from a feed end to a firing end and the fuel used is flue gas that is produced by gasifying a fuel in the presence of combustion air in a gasifier. The combustion air for gasification is preheated with heat generated in lime mud combustion. The arrangement is provided with a conduit between the lime kiln and the gasifier for leading air from the lime kiln into the gasifier as combustion air. At least a portion of the combustion air for gasification is preheated with heat generated in the lime mud combustion so that air is led into cooling of lime obtained in the combustion and further into the kiln, from or through the firing end of which air is taken into the gasification.

Abstract: An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct including vertical flue gas channels, at least some of which are provided with heat recovery units for recovering heat from flue gases. The first flue gas channel downstream of the furnace is provided with a reheater and one of the following heat recovery units: an economizer or a boiler bank. The reheater and the second heat recovery unit are located one after the other in the horizontal incoming direction of the flue gas, so that in a flue gas channel the flue gas flows in a vertical direction from above downwards and heats the reheater and the second heat recovery unit simultaneously. The heat recovery elements of the reheater and the second heat recovery unit may be positioned side by side in a direction that is crosswise with respect to the horizontal incoming direction of the flue gas.

Abstract: A method and a boiler for decreasing the amount of nitrogen oxides in flue gases of a boiler, which flue gases are generated in the combustion of fuels and air. The boiler has a water circulation system comprising superheaters and a furnace for combustion of fuel and for generating flue gases that contain nitrogen oxides, which flue gases mainly flow upwards in the furnace and further to the superheater zone and via other heat recovery surfaces of the boiler out of the boiler, and a nitrogen oxides reducing agent is introduced into the flue gases. The nitrogen oxides reducing agent is introduced into the flue gases prior to the superheater zone, after the temperature of the flue gases is decreased by at least one heat exchanger that is located upstream of the nose of the boiler and upstream of the introduction of the nitrogen oxides reducing agent.