A device (10) is provided for preventing rewetting in a pulp washer (100), with two press rolls (2), arranged to rotate in opposite directions and having permeable outer surfaces (4), inside of which filtrate channels (6) are arranged. The device (10) comprises an anti-rewet beam (12), the cross-section of which forms a closed shape. The anti-rewet beam in turn comprises a filtrate barrier (12a) positioned towards the outer wall (6a) of the filtrate channel to prevent flow of liquid from the trailing part of the filtrate channel to the outer surface of the press roll, a support member (12b) positioned towards the rear side wall (6d) of the filtrate channel, and at least one intermediate beam portion (12c, 12c'), interconnecting the filtrate barrier and the support member, to form the closed beam shape.
B01D 33/067 - Construction of the filtering drums, e.g. mounting or sealing arrangements
B30B 9/20 - Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using rotary pressing members, other than worms or screws, e.g. rollers, rings, discs
A pulp distribution device (10) is provided for distribution of cellulose pulp having a concentration of 2-13% to a rotatable first permeable surface (21) in an apparatus (100) for washing cellulose pulp. The pulp distribution device comprises an inlet (11) for incoming pulp, an outlet (12) for output of pulp to the first permeable surface, a first rotatable distribution means (13") arranged in the pulp distribution device for longitudinal distribution of pulp, and a second permeable surface (14") arranged to allow throughflow of filtrate from pulp in the pulp distribution device, whereby an initial dewatering of the pulp takes place in the pulp distribution device. By means of the invention the initial dewatering in the washing apparatus is increased, which inter alia implies higher capacity of the washing apparatus and higher washing efficiency.
The invention relates to a method of producing a structured fibrous web of paper. The method comprises forming a fibrous web and conveying the formed fibrous web on a water receiving felt (5) to a dewatering nip. An endless belt (11) with a polyurethane surface is passed through the nip together with the fibrous web and the water receiving felt (5). After the dewatering nip, the fibrous web is conveyed by the endless belt (11) to an endless textured fabric (12) which is permeable to air and to which the web is transferred from the endless belt (11) in a transfer nip. The textured fabric (12) rans at a lower speed than the endless belt (11). After the transfer to the textured fabric (12), the fibrous web is carried by the textured fabric (12) to a drying cylinder (17). The transfer nip is formed by two rolls of which one is a suction roll within the loop of the textured fabric. The transfer nip has a length which is 5 mm - 40 mm. The endless polyurethane belt (11) has a width that exceeds the width of the textured fabric (12). The invention also relates to a corresponding machine.
A feed screw (18) for feeding lignocellulose material to a rotary disc grinder (10) comprising two opposed grinding discs (11, 12), the feed screw (18) comprising at least one peripheral thread (23) for feeding lignocellulose material in an axial feeding direction, the peripheral thread (23) having an upstream end from which lignocellulose material are to be fed towards an downstream end that is to be arranged through the centre of one of the grinding discs (11) such that it reaches into a feeding zone (25) between the two opposed grinding discs (11, 12). The downstream end of the peripheral thread (23) comprises an angled end part (22), which is arranged at an angle with respect to the peripheral thread (23) so as to re-direct the lignocellulose material in the radial direction as it leaves the peripheral thread (23).
B30B 9/12 - Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using pressing worms or screws co-operating with a permeable casing
The invention is related to an improved compact process for producing dissolving pulp in a prehydrolysis kraft cooking process. In order to avoid pitch problems with blocked withdrawal screens and to obtain a distinct ending of the prehydrolysis stage, as well as a thorough alkaline impregnation ahead of the kraft cook stage, alkali is charged to the mixture of prehydrolyzed material to such an extent that the residual alkali concentration after neutralization of the acidic hydrolysate is above 20 g/l EA as NaOH and the temperature of the resulting alkaline treatment liquor for the prehydrolyzed material is lowered by at least 10% in comparison to the temperature in the prehydrolysis stage. The alkali charge will avoid redeposition of hemicelluloses dissolved in the prehydrolyse stage and will abruptly swing the wood material mixture to alkaline conditions favourable for a alkali impregnation stage at reduced temperature ahead of the final kraft cooking stage, which impregnation stage will extract the major part of the hemicelluloses content of the cellulose material.
The invention relates to a method and arrangement for adding treatment liquid to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. Said process using a down flow vessel (13) where chips are descending down the vessel in a plug flow and where treated chips are continuously fed out at the bottom of the vessel. By arranging at least one telescopic pipe (7b1/701 or 7b2/702) inside the vessel and extending down into the plug flow could the position for addition of treatment liquid be adjusted depending on current operational parameters.
A sealing arrangement (500) for sealing between a first drum (102) and an end casing member (210) included in an apparatus for processing pulp, the first drum being rotatable about an axis of rotation (107) in relation to the end casing member and the sealing arrangement, and the first drum being provided with a permeable outer surface (106) which axially extends between a first end (503) and a second end of the first drum, and at least at the first end the first drum is provided with an end surface (506), the sealing arrangement comprising a sealing member (510); first pressure means (516) for forcing the sealing member in a direction towards the first drum to bear against a portion of the end surface; a circumferentially extending sealing element (508) held by a holder (512); and second pressure means (522) for forcing at least a first portion (524) of the sealing element in a direction towards the first drum to make the first portion bear against a portion of the end surface, the holder being arranged to hold the second pressure means, and a terminal second portion (528) of the sealing element is in proximity to the sealing member, wherein the sealing arrangement comprises means (545) for forcing the second portion of the sealing element in a direction towards the first drum to make the second portion bear against a portion of the end surface, and wherein the means for forcing the second portion (528) of the sealing element (508) in a direction towards the first drum are separate from the second pressure means (522). An apparatus for processing pulp having such a sealing arrangement (500).
The method and an arrangement are for the improvement of a wash after completed digestion in a continuous digester for the production of cellulose pulp. The softened chips are exposed to a radially directed displacement wash after they have passed the rotating bottom scraper. The displacement wash has been established in the flow of digested softened chips through the outlet tap before the softened chips are defibrated by the fall in pressure across the blow-valve that is arranged after the digester.
A device for adjusting a press nip (126) defined by a first press roll (102) and a second press roll (104), each press roll being rotatable about an axis of rotation (103, 105) and included in an apparatus for dewatering pulp, and the apparatus has a first pair of bearing housings (220) provided with bearings (218) by means of which the first press roll is journalled, each bearing housing of the first pair and the first press roll being movable in relation to the second press roll in a direction substantially transverse to the axial direction of the press nip, the device comprising pressure means (222) for forcing the bearing housings of the first pair in a direction towards the press nip, the first press roll being movable between a first radial end position and a second radial end position. The device is arranged to adjust the press nip during operation of the apparatus and comprises at least one adjusting cylinder (223; 402) for adjusting the first press roll to each of the radial end positions during operation of the apparatus, the adjusting cylinder being arranged to force at least one of the bearing housings of the first pair in a direction away from the press nip to move the first press roll to one of the radial end positions, and the adjusting cylinder has a length of stroke (S) that defines the difference between two different press nips (I, II) for the apparatus, wherein the length of stroke (S) of the adjusting cylinder (223; 402) is adjustable to adjust the difference between the two different press nips (I, II). An apparatus for dewatering pulp comprises such a device for adjusting the press nip.
B30B 9/20 - Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using rotary pressing members, other than worms or screws, e.g. rollers, rings, discs
B01D 33/067 - Construction of the filtering drums, e.g. mounting or sealing arrangements
B21B 29/00 - Counter-pressure devices acting on rolls to inhibit deflection of same under load, e.g. backing rolls
The present invention relates to a press device (1) that comprises an extended nip roll (2) and a counter roll (3). The extended nip roll (2) has a flexible jacket (4) and a support body (5) inside the flexible jacket (4). The extended nip (2) roll also has internal means for causing the support body (5) to move or expand radially towards an inner surface (6) of the flexible jacket (4) to form a nip with the counter roll. The rolls (2, 3) have axial ends (7, 8, 10, 11) that are supported in bearing housings (9, 12). One or several actuators (13) such as hydraulic cylinders connects bearing housings (9, 12) to each other and the actuator or actuators (13) are arranged to act on the bearing housings (9, 12) to cause them to move to each other in a closing movement. A mechanical stop (14) which is separate from the rolls (2,3) is arranged to halt the closing movement. The invention also relates to a machine that uses the press device and to a method of operating the press device.
The invention relates to a continuous digester for producing pulp from comminuted cellulosic material. The digester has a cone diverter on a bottom scraper arranged in the bottom of the digester for assisting in out feed of pulp produced, the cone diverter of the bottom scraper having an upper inclined surface of the cone diverter with an inclination angle in the range 30+10 degrees in relation to the vertical. In order to improve washing performance in the bottom of the digester, especially for overloaded digesters, the upper inclined surface is equipped with draining apertures in fluid communication with a liquid receiving chamber inside the cone diverter, said10 liquid receiving chamber connected via a drainage channel to the exterior of said vessel.
The invention is related to a hydraulic system and a method for reducing the amount of hydraulic fluid that could accumulate by condensation in a high pressure accumulator in the hydraulic system. The hydraulic system incorporates a hydraulic cylinder for vertically moving said body into a reciprocating motion and a high pressure accumulator connected to receive and supply hydraulic fluid to the hydraulic cylinder. The high pressure accumulator (62) includes a piston (70) which divides the high pressure accumulator into an upper gas filled volume (62a) and a lower volume (62b) filled with the hydraulic fluid. According to the invention is the hydraulic system equipped with means (90,91) for increasing the temperature in the upper gas filled volume of the high pressure accumulator,and preferably using a colder condensation device (93) in an external back-up bottle (80) for the gaseous medium in the high pressure accumulator. The invention avoids condensation of hydraulic oil in the high pressure accumulator.
Method and arrangement (1) for processing pulp, including a first endless wire (2) and an opposed endless second wire (3), which wires are conveyed in a same conveying direction (D) to define a web forming space (12) between them, in which space (12) pulp in the form of a web is to be dewatered, wherein both wires are supported by a first and a second perforated dewatering table (4, 5), respectively, for pressing the wires towards the web, both tables having a front end (7, 8) and back end (9, 10) with respect to the conveying direction (D) of the wires (2, 3) and wherein the first dewatering table (4) of the two ends up stream of the second table (5) and that the arrangement includes a press roll (6) downstream of the back end (9) of the first table (4), which press roll (6) is opposed the back end (10) of the second table (5) so as to form a nip (13) between the press roll (6) and the back end (10) of the second table (5). The back end (10) of the second table (5) has a profiled surface that interacts with the press roll (6) so as to prolong the nip (13) between the press roll (6) and the back end (10) of the second table (5).
The present invention relates to an inverted top separator to be used in a steam/liquid phase continuous digester. In a fashion known per se, the chip slurry (CSIN) is fed into the top separator by a centrally located inlet in the bottom of the top separator. According to the invention, the chip slurry is directed towards an annular gap (43) formed between the end of the core shaft (10) and an end connector (40) of the supply pipe (30). Preferably, the end of the core shaft (10) is shaped as a cone (41 ) pointing against the flow direction in the supply pipe (30), and the end connector (40) is preferably made in a congruent cone shape with the narrow end of the cone shape also pointing against the flow direction in the supply pipe (30).
The invention concerns a method, system and a withdrawal screen section for the impregnation of chips during the manufacture of chemical pulp. Chips are both steamed and impregnated in a low pressure impregnation vessel 3, using pressurised hot spent cooking liquor BL as the main part of the impregnation liquid, which hot spent cooking liquor produce most of the steam BLSτ necessary for steaming the chips. In order to improve the process in the impregnation vessel 3 are at least two independent first and second screen rows, SC1 and SC1 b respectively, installed. The first screen row withdraws acidified treatment liquor for disposal which otherwise would be a parasitic acidified waste fluid in the system, and the second screen row recirculates treatment fluid back to centre of treatment vessel in order to even out the pH profile over the cross section of the vessel.
The high pressure sluice feeder has a conical rotor mounted in a housing having a complementary conical interior. The rotor has a plurality of trough-going pockets arranged offset to each other in the rotor. The housing has ports distributed evenly around a circumference of the housing and exposed to the pockets during rotation of the rotor. A conical exterior surface of the rotor or the conical interior surface of the housing is equipped with a flush-out groove. The groove catches any abrasive particles caught between the complementary conical surfaces of the rotor and housing. The abrasive particles are flushed out towards the trough-going pockets of the rotor when one end of the groove is pressurized by either one neighboring trough-going pocket or a sealing liquid supply to a gable end of the rotor/housing.
The invention concerns a method, system and a withdrawal screen section for the impregnation of chips during the manufacture of chemical pulp. Chips are both steamed and impregnated in a low pressure impregnation vessel 3, using pressurised hot spent cooking liquor BL as the main part of the impregnation liquid, which hot spent cooking liquor produce most of the steam BLST necessary for steaming the chips.In order to reduce need for adding fresh steam for chip steaming is a first withdrawal section in the impregnation vessel 3 modified to be used both as a flash tank for warm pressurised wash filtrate as well as an improved wash-out feature for the spent impregnation liquid behind the screen in the withdrawal section. For this purpose is the withdrawal volume 60 arranged with an upper part 60a being located above the liquid level LIQLEV of the impregnation vessel, and an additional pressurised warm wash liquor REC1 is added to the withdrawal volume, and steam flashed off is led in a steam duct 62 to the chip volume above the liquid level.
The feed system is for a continuous digester where at least two pumps are arranged in parallel at the bottom of a pre-treatment vessel. The outlets of the pumps are combined at a merging point before a common transfer line extends to the top of the digester. The system makes it possible to provide a feed system with an improved accessibility and operational reliability, and to operate the main part of the pumps at optimal efficiency even if the production capacity is reduced.
The present invention relates to a method and system for cooking of chemical pulp, and relates in particular to a process for dealing with rejects in conjunction with the cooking of chemical pulp. According to the invention is a chopper pump 12 used for recirculating a flow a rejects in a reject vessel 11, said chopper pump having at least one cutting edge on the impeller and a cooperating anvil in the pump housing. A part flow Q3 is splitted from this recirculation flow and fed to the digester via a high pressure pump 13, said part flow preferably being less than 50% of the total flow Q1 pumped by said chopper pump. The rejects in the reject vessel is also preferably slurried with treatment liquor that is to be added to the cooking process. The invention will obtain a repeated defibration effect on the rejects and prepare them for a complete delignification in next passage of the digester and thus reduce the reject volumes over time.
The present invention concerns an improvement of the heating circulation in a continuous digester for the production of cellulose pulp. The heating circulation withdraws treatment liquor from the vessel via a strainer section 61 arranged in the wall of the digester and after passing the withdrawn treatment liquor trough a heating device 40 is the heated treatment liquor added into the centre of the vessel via a central pipe 21a. According to the inventive arrangement and method is a part flow of the heated treatment liquor also added via nozzles arranged in the wall of the vessel close to the strainer section 61. A more uniform heating over the entire cross section of the vessel is thus possible in especially overloaded digesters.
The invention relates to a system and method for washing and thickening a lime mud slurry. A filter 1 is used wherein the liquid volume in the filter vat is divided by at least one partition wall 19 into at least 2 independent vat parts and that these vat parts are fed with lime mud slurry in parallel, by individual supply lines from at least one lime mud storage tank 30a/30b. When a clean out operation of one independent part is activated, is the lime mud vat flushed out to the preceding lime mud slurry container 30a/30b, while all other independent parts are still in operation. By using this parallel operation could lime mud sedimentation in the filter vat be broken up at regular intervals, and a continuous feed of washed and thickened lime mud be made to the lime kiln, maintaining the structural integrity of the kiln.
D21C 11/04 - Regeneration of pulp liquors of alkali lye
B01D 33/06 - Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
B01D 33/21 - Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with hollow filtering discs transversely mounted on a hollow rotary shaft
22.
METHOD AND ARRANGEMENT FOR IMPROVING A WASHING STEP AFTER COMPLETED COOKING IN A CONTINUOUS DIGESTER
The invention concerns a method and an arrangement for the improvement of a wash after completed digestion in a continuous digester (1) for the production of cellulose pulp. According to the invention, the softened chips are exposed to a radially directed displacement wash after they have passed the rotating bottom scraper (36), and which displacement wash has been established in the flow of digested softened chips through the outlet tap (10) before the softened chips are defibrated by the fall in pressure across the blow-valve that is arranged after the digester.
The invention concerns a system and a method for the pumping of finely divided cellulose material to a continuous digester (6). It is possible by a concentric arrangement of pipes (30, 31) and the addition of fluid (Liq) to a chamber (36) formed between the pipes to establish a cylindrical film of fluid around a rod-shaped flow of cellulose material before the inlet to the pump (12a). It is possible in this way to reduce the pressure drop in the lines, reduce wear in the pump, and ensure a maximal pressure build up in the pump.
F04D 7/04 - Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type the fluids being viscous or non-homogeneous
24.
METHOD AND ARRANGEMENT FOR STEAMING AND IMPREGNATING WOOD CHIPS IN A DOWN FLOW VESSEL
The invention relates to a method and arrangement for steaming and impregnating wood chips in a single down flow vessel. A first upper volume of chips is established above a liquid level (LIQ_LEV) in the vessel, wherein steaming takes place. Said upper volume having a height (H1) of at least 2-5 meter. A second lower volume of chips is established below the liquid level, wherein an impregnation takes place. Said lower volume having a height (H1) of at least 2-5 meter.In order to reduce the torque demand on the bottom scraper are plug holding forces applied against the descending plug flow at a distance (H3) below the liquid level less than 20% of the height (H1) of said lower volume, such that a minimum free and unobstructed plug flow in the first volume is established which unobstructed plug flow is established at a vertical distance in said vessel exceeding 2-5 meter above the liquid level.
The invention is related to a pulp treating apparatus such as a pressure diffuser. The apparatus incorporates a screen having a considerable weight that is moved by a connecting rod 5 in a reciprocating manner between an upper and lower position. The connecting rod 5 is maneuvered by a hydraulic cylinder 61 for vertically moving said screen in first slow stroke concurrent with pulp flow and moving said screen in a second fast stroke counter current to pulp flow. According to the invention is the pressure diffuser having the inlet in the bottom of the vessel but the hydraulic cylinder 61 at the top of the vessel. By this design could an increased active pressure area in the hydraulic cylinder be obtained for the fast stroke of the screen, thus restricting the power rating of the hydraulic system.
The invention relates to a method and arrangement for adding treatment liquor to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. Said process using a down flow vessel where chips are descending down the vessel in a plug flow and where treated chips are continuously fed out at the bottom of the vessel. By arranging more than two parallel pipes 7b offset from the center of the vessel could a better distribution of treatment liquor be obtained, and the disturbance of the chip plug flow descending down the vessel will be reduced to a minimum.
The invention relates to a method for producing mechanical pulp from a cellulose-based raw material by washing it in a chip washer (2). Water is removed from the washed raw material in a pulp thickener (4), and the pulp is refined in at least one refiner (6) comprising at least a first blade and a counter piece, wherein the distance between the first blade and the counter piece determines the blade gap. In the method, the raw material is also pre-defibrated by at least one pre- defibrator (3) before the refining of the pulp in the refiner (6). The invention also relates to a system for producing mechanical pulp from cellulose-based raw material. The system comprises a washer (2), a pulp thickener (4), and at least one refiner (6) comprising a refining space and at least a first blade and a counter piece, wherein the distance between the first blade and the counter piece determines the blade gap. The system comprises a pre-defibrator (3) placed before the refiner (6). The invention also relates to the use of the method and the system in the manufacture of a paper product.
D21B 1/12 - Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods by the use of steam
Apparatus for treating pulp comprising an elongated upright cylindrical hollow vessel (10), which includes an inlet (21) and outlet (22) for pulp in opposite ends of the vessel. A central shaft (25) is arranged inside the vessel and journalled at one end wall of the vessel in bearing means (60a) and the other end in a support structure (30, 31) located at a distance from the other end wall of the vessel including at least 3 radial arms (31), each connected to the inside of the vessel wall in one end and to a shaft bearing (30) located at the centre of the vessel at the other end. According to the invention the radial arms (31) are connected to the shaft bearing (30) via hinges (40) having a pivot axis in the vertical direction, which implement a stiff but yet flexible support at the same time that could avoid weld fractures in the support structure.
The invention relates to a conventional high pressure sluice feeder for transferring a chip slurry from a low pressure level to a high pressure level, using a revolving rotor (10) with conical exterior mounted in a stationary housing with a complementary conical interior at a predetermined minimized play between these complementary conical surfaces. Said rotor having a plurality of trough going pockets (TP11, TP21, TP12, TP22) arranged offset to each other in the rotor, and said housing having 1st to 4th ports distributed evenly around the circumference of the housing, and exposed to the pockets during rotation of the rotor. In order to reduce wear in said high pressure sluice feeder is at least one of the complementary surfaces of the conical exterior surface of the rotor or the conical interio rsurface of the housing equipped with a flushout groove (105a) running in a direction having at least one component in parallel with the generatrix of the conical surfaces. Said groove will catch any abrasive particles being caught between the complementary conical surfaces of the rotor and housing, and said abrasive particles will be flushed out towards the trough going pockets of the rotor when one end of the groove is pressurized by either one neighboring trough going pocket or a sealing liquid supply to a gable end of the rotor/housing.
F16K 11/083 - Multiple-way valves, e.g. mixing valvesPipe fittings incorporating such valvesArrangement of valves and flow lines specially adapted for mixing fluid with all movable sealing faces moving as one unit comprising only taps or cocks with tapered plug
30.
Digester screen for a continuous cellulose pulp digester
The digester screen is for a continuous digester in which cooked cellulose pulp is produced. The digester screen has a number of screen bars arranged vertically in the continuous digester that have withdrawal slots (S) between the fixed screen bars through which withdrawal slots cooking fluid can be withdrawn from the column of pulp (P) of the digester. By having every second screen bar fixedly arranged and recessed a distance (D) relative to the neighboring screen bar an increased withdrawal capacity for the screen is obtained.
The invention is related to a pulp treating apparatus such as a pressure diffuser. The apparatus incorporates a screen having a considerable weight that is moved by a connecting rod 5 in a reciprocating manner between an upper and lower position. The connecting rod 5 is maneuvered by a hydraulic cylinder (61) for vertically moving said screen in first slow stroke concurrent with pulp flow and moving said screen in a second fast stroke countercurrent to pulp flow. According to the invention is a second force actuator means (71) arranged in parallel with the first hydraulic cylinder arrangement (61), and wherein the second force actuator means provides a counterforce balancing the weight of said screen. The second hydraulic cylinders also provides for recovery of energy during the slow stroke. The invention enables a reduction in necessary design pressures of the hydralic system, and reduction in power consumption for operating the hydraulic system.
The invention concerns a system and a method for the regulation of a continuous vapour phase digester (50). The relevant process inflows (CH, ST, WL, DL) are regulated with a process regulator (PC) depending on current process outflows (LIQRET, CHOUT) in order to establish a gas phase (STP) above a level (LIQLEV) of cooking fluid in the digester and a level of chips (CHLEV) in the digester that lies above the level of fluid. The process regulator has a first set of sensors (40, 41, 43) in order to control a first set of regulators (10, 11, 12, 13) in the input with respect to a first set of target values, and that [sic, syntax] the system comprises a load controller that is independent of the process regulator, which load controller has a second set of sensors (42) in order to control a second set of regulators (20, 21, 22, 23) in the input with respect to a second set of threshold values. The load controller closes at least one of the relevant inflows when these threshold values are exceeded. Alternatively, the load controller can open an otherwise closed line in order to reduce the volume of fluid in the digester.
The invention concerns a method and an arrangement for wash after completed digestion in a continuous digester (1) for the production of cellulose pulp. Digested softened chips that have not been defibrated are fed out from the bottom plane of the digester. The non-defibrated chips are fed out under the influence of a bottom scraper arranged at the bottom of the digester and subsequently through a bucket shaped outlet tap (10) at the bottom of the digester, and onwards to an outlet line (12) connected to the outlet tap. This takes place before the softened chips pass through a blow-valve (4) arranged in the outlet line, across which blow-valve a pressure drop of at least 0.5 bar and at most 3-5 bar has been established. What is characteristic for the invention is that the softened chips are exposed to an displacement wash after they have passed the outlet tap (10), and which displacement wash has been established in the flow of digested softened chips through the outlet line (12) before the softened chips are defibrated by the pressure drop across the blow-valve (4).
The invention concerns an arrangement and a method for the steam pre-treatment of chips during the production of cellulose pulp. With the aim of avoiding the blow-through of gases in the steam pre-treatment vessel (1) and in this way preventing foul-smelling gases from being released into the atmosphere, the inlet of the vessel (1) comprises an inclined feeder device (52) in a feeder housing (54). In the event of the initiation of the risk for blow-through of steam, is the feeder housing sprayed with cooling liquid in order to increase condensation capacity of the chips being fed, and ultimately filling the feeder housing with liquid, establishing a liquid lock, and preferably at the same time as the feeder drive (M) is shut off. It is possible in this simple manner to avoid the emission of gases from the chip bin when interruptions in the process occur, whereby the release of odours into the surroundings can be minimised.
The invention concerns a method for influencing the flow from a strainer construction in a continuous digester. In order to avoid clogging of the withdrawal compartment (10a) in the strainer construction, an additive (Ch) that counteracts precipitation processes is added directly to the withdrawal compartment while the cooking fluid is being withdrawn from the withdrawal compartment. The addition of chemicals can take place at the same time as the withdrawn cooking fluid is withdrawn from the digester and the strainer construction, or while the withdrawn cooking fluid is fully or partially recirculated back to the withdrawal compartment.
In a continuous digester system the digester system is greatly simplified by using a single vertical atmospheric vessel, replacing the conventional chip bin, steaming vessel, chip chute, high pressure pumping or sluice feeders, impregnation vessels and top separator. Chips are simply fed to the top of the atmospheric vessel, and a chip level is established in the vessel. Treatment liquids are added to the vessel such that a total liquid volume (Z1+Z2) with a liquid level (LIQ LEV) is established under the chip level (CH LEV). Impregnation stage and subsequent cooking stages are implemented in the atmospheric vessel at successively increasing temperature and depths into the total liquid volume, thus preventing boiling in the stages and preferably reducing steam blow trough of the chip surface in the top of the vessel.
(1) Machinery for storing, impregnation, steaming of cellulose containing material in connection with production of cellulose pulp, including pumps, pipes, valves, extraction screens and treatment vessels in such machinery.
06 - Common metals and ores; objects made of metal
07 - Machines and machine tools
Goods & Services
(1) Machinery for storing, transport and conveying of cellulose material and/or digester or impregnation liquid in connection with digesting and production of cellulose pulp, including pumps, pipes, valves, extraction screens, towers, top separators in digester vessels, impregnation vessels in such machinery.
39.
Method for the continuous steam pre-treatment of chips during the production of cellulose pulp
The arrangement and method are for the steam pre-treatment of chips during the production of cellulose pulp to avoid the blow-through of gases in the steam pre-treatment vessel. This prevents foul-smelling gases from being released into the atmosphere. Spreader nozzles for the injection of cooling fluid are arranged in the gas phase of the steam pre-treatment vessel. In the event of the risk for blow-through of steam, cooling that is proportional to the risk is activated. It is possible to avoid the emission of gases from the chip bin when interruptions in the process occur, whereby the release of odors into the surroundings can be minimized.
The method is for the impregnation of chips during the manufacture of chemical pulp. The chips are continuously fed without preceding steam treatment to the top of an impregnation vessel that maintains atmospheric pressure. Impregnation fluid (BL) is added to the impregnation vessel and establishes a fluid level (LIQ_LEV). The chips that have been added establish a chips level (CH_LEV) that lies at least 3-5 meters over the fluid level. The temperature at the top of the vessel essentially corresponds to ambient temperature.
Impregnation fluid BL is fed in to the impregnation vessel in such an amount and at such a temperature that the temperature that is established at the fluid level (LIQ_LEV) is established within the interval 90-115° C., preferably within the interval 95-105° C.
A method for impregnating chips in a continuous digestion system with an impregnation vessel and a digester. The digestion system has a heat exchanger arranged between a first return line and a black liquor line. The heat exchanger allows a transfer of heat between the two lines. A principal part of the fluid contents of the impregnation vessel is constituted by chips moisture, steam condensate, added white liquor, and the fluid withdrawn from the top separator at the first return line, whereby the impregnation fluid in the impregnation vessel does not contain any substantial amount of black liquor from the digester. An impregnation vessel is established that is hydraulically isolated, in which the flow of fluid and the establishment of its alkali content take place without any influence from the fluid flow in the digester process.
(1) Machines for cooking and washing of fibre material for use in pulp industry; pressure diffusers, wash presses, digesters and thereto belonging facilities for handling of filtrates.
03 - Cosmetics and toiletries; cleaning, bleaching, polishing and abrasive preparations
06 - Common metals and ores; objects made of metal
07 - Machines and machine tools
20 - Furniture and decorative products
Goods & Services
(1) Rotating and stationary filter used in the process of causticizing; lime slakers; causticizers; lime mud storage tanks; sedimentation clarifiers; scrubbers, containers, feeders, mixers and heaters used in the process of causticizing.
