• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
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    • 专利摘要:

    公开号:SE534058C2
    申请号:SE0802039
    申请日:1997-10-07
    公开日:2011-04-12
    发明作者:Stroemberg Bertil；J Wayne Chamblee；Bruno S Marcoccia；Rolf Ryham；Erwin D Funk
    申请人:Andritz Inc；
    IPC主号:
    专利说明:

    Pressure vessels under an overpressure of at least about 10 bar (about 150 psig). In order to maintain this pressure, especially when performing a continuous cooking process, special measures must be taken so that the pressure does not disappear when the material is fed into the pressure vessel. According to the prior art, a so-called High- Pressure Feeder. This feeder is a purpose-built device containing a rotor provided with fi ckor which serves as a means of transferring a material suspension from a low pressure to a high pressure and at the same time acts as a valve which prevents loss of pressure. This complicated and expensive device has long been considered a necessary component for feeding suspensions of distributed cellulosic material into pressurized vessels, typically at an elevated temperature, especially in continuous boilers.
    According to the invention, a system is provided which replaces High-Pressure Feeder - which for over forty years has been considered necessary for continuous cooking - which greatly simplifies the construction of a pulp mill.
    The present invention relates to a system for feeding finely divided cellulosic fibrous material, such as wood ice, in the production of chemical pulp, comprising: a basing vessel in which non-distributed cellulosic fibrous material is based to remove air therefrom; and a pressurized vertical treatment vessel having an inlet for a suspension of distributed cellulosic bone material in its upper part and an outlet in its lower part; characterized in that it further comprises a pressure generating supply device for pressurizing a suspension of material from the basing vessel and transferring it to the inlet of the treatment vessel, which pressure generating supply device consists of one or more high pressure suspension pumps located below the upper part of the treatment vessel; and a liquid return line from the upper part of the treatment vessel, which return line is operatively connected to an outlet in one of the suspension pumps.
    The one or more pumps preferably comprise a first and a second high-pressure suspension pump arranged in series, each having a pressure value, an inlet and an outlet, the inlet of the first pump being operatively connected to the base vessel, the outlet of the first pump being functional. Connection with the inlet of the second pump and the second pump has a higher pressure value than the first pump. The suspension pumps can consist of spiral screw-type centrifugal pumps, which are capable of pressurizing a suspension with a relatively high content of solid material (in one or more steps) to a pressure of at least about 5 bar overpressure.
    A typical unit of measurement which indicates the relative amount of solid material in a suspension containing solid material and liquid is the so-called liquid / solids ratio. In this application, this relationship refers to the relationship between the quantity, ie. the volume, liquid and quantity, i.e. the volume, mass or wood material being transported. Typical conventional centrifugal type liquid pumps are limited to pumping liquids with a solids content of not more than 3%. This solids content corresponds to a liquid / solids ratio of about 33. In the suspension pump used in the invention, the liquid / solids ratio of the suspension being pumped is typically 2 - 10, preferably 3 - 7 and most preferably 3 - 6. The suspension pumps used in the invention transport suspensions with a much higher solids content than a conventional pump can handle.
    A liquid return line is connected to the upper part of the treatment vessel, which contains liquid separated from the suspension at the upper end of the treatment vessel (preferably a continuous boiler). The return line is operatively connected to an outlet in one of the suspension pumps, either directly or indirectly. The liquid return line is preferably connected to a pressure reducing device for reducing the pressure of the liquid in the return line before the liquid is led to the outlet of the suspension pump. The pressure reducing device may be of various kinds, such as a pressure regulating valve in the return line or other conventional construction for effectively reducing the pressure in a line without adversely affecting the liquid.
    Alternatively, the pressure reduction can be accomplished or even avoided by using a jet pump that utilizes the pressurized return line as its source of pressurized fluid. A jet pump can be used together with one or more of the suspension pumps to transport suspension to the digester. A conventional ice shaft as well as other alternative components are preferably arranged between the basing vessel and the at least one suspension pump, the basing vessel being located above the ice shaft and the ice shaft above the suspension pump (s). The suspension pump (s) are typically located at a distance of at least about 10 meters (30 feet) below the upper end of the digester and typically more than about 15 meters (about 50 feet) below.
    When the high pressure feeder device is abandoned, it is desirable to use other devices to maintain one of the functions of the high pressure feeder, namely to prevent pressure relief in the event of an abnormal operating condition.
    Namely, the high pressure feeder device typically prevents backflow of liquid from the digester to the feeder system. The device which prevents pressure relief according to the present invention is preferably separated from the at least one suspension pump, although in some cases the inlet or outlet of the suspension pumps may be designed so as to prevent pressure relief. The pressure relief devices may automatically include a separation valve in the suspension lines which directs suspension from the pumps to the upper end of the treatment vessel and the return line from the treatment vessel, a conventional control means being connected to the separation valves controlling them by the pressure shielded by a detector connected to the suspension line. feeding suspension to the upper end of the treatment vessel. The devices which prevent pressure relief may also comprise a non-return valve in the suspension line and / or other valves, containers, detectors, control devices or similar hydraulic, mechanical or electrical components which are capable of preventing pressure relief.
    A heating system may also include means for increasing the flow of liquid to the inlet of the second suspension pump or to another pump or feeder, such as a liquid line containing liquid having a lower pressure than the pressure in the inlet of the second suspension pump, a line between the liquid line and the inlet a fluid pump in the line. The liquid line may consist of the return line from the treatment vessel and the line may be directly connected to the return line. The liquid return line may be connected to a shut-off vessel as described above and the line may be connected to the liquid outlet of the shut-off vessel.
    A method of feeding finely divided cellulosic fibrous material to the upper end of a treatment vessel may comprise the following steps: (a) the material is based to remove air therefrom and wind up the material. (b) the material is suspended in a cooking liquor to effect a suspension of liquid and material; and (c) the suspension is pressurized to a pressure of at least 5 bar overpressure below the upper end of the treatment vessel (eg at least 9 meters or 30 feet, preferably at least 15 meters or 50 feet, below it) and pressurized material is transferred to the upper end of the treatment vessel, wherein the pressurizing step consists in that the suspension is influenced by one or more high-pressure suspension pumps, at least one of which is a spiral screw-type centrifugal pump.
    Such a method may comprise further steps wherein: (d) liquid separated from the suspension at the upper end of the treatment vessel is returned to the at least one pump; and (e) the pressure in the suspension is sensed while being transferred to the upper end of the treatment vessel and the suspension flow to the upper end of the treatment vessel and the return of suspension from the upper end of the treatment vessel is switched off if the sensed pressure is less than a predetermined value. There may also be an additional step (f) in which the liquid is capped off as it is returned in the execution of step (d) to produce steam, and the steam is used in the execution of step (a).
    In conventional pulp mills, the cellulosic material, typically softwood or hardwood, but also cellulosic material of another kind can be added in various forms. It can e.g. added as sawdust, as fl ice, as logs, as long pruned trees (ie longwood) or even as whole trees (ie whole trees). Depending on the source of cellulose in the wood supply, the wood is typically transformed into fl ice so that it can be handled and treated in a cooking process. S.k. Ice choppers convert longwood or logs into chips that are typically stored in open ice piles or ice silos. This reception, handling and storage of the ice is carried out in a department of the pulp mill called the wood farm. From the wood farm, the ice is typically transported to the actual pulp mill to begin the pulp production process. In conventional wood yards, the ice is stored in silos from which the ice is discharged, typically by means of a rotating or vibrating silo dispenser, to a conveyor.
    The conveyor typically consists of a belt conveyor that receives the ice and takes them to the cooker's treatment vessel. Since the woodshed is typically located at a distance from the boiler vessels, the conveyor is typically long. Such a conveyor may have a length of the Lo-Level feeding system, which is marketed by Andritz and is described in the aforementioned U.S. up to about 800 m. a height of at least 30 m (100 ft), to feed the ice to the inlet of the first pulp production vessel. These conveyors and their support structures are very expensive and make up a significant part of the cost of the boiler's feed system.
    Here, the concept of transporting a suspension of ice to the wood yard is described. Transport of non-distributed cellulosic fibrous material to a cooking process may consist of the following steps: (a) Untreated ice is fed into a first vessel. (b) Suspension liquid is fed into the first vessel to form a suspension of material and liquid. (c) The suspension is discharged from the vessel to the inlet of at least one pressure generating and transporting device. (d) The suspension is pressurized in a pressure generating and transporting device and transferred to a treatment vessel.
    The first vessel is typically an fl issilo or binge. This binge preferably has an outlet with one-dimensional convergence without agitation or vibration, such as the DlAMONDBACK® bin described in U.S. Patent 5,000,083, although agitation or vibration may be used. The bin can also have two or fl your outlets that feed two or fl your transport devices. The vessel can operate at a higher than atmospheric pressure, e.g. 0.1 - 5 bar. If the vessel operates at a higher than atmospheric pressure, a pressure separating device of some kind at the inlet of the vessel is needed to prevent relief of the pressure. This device may be a star-type separator, such as a Low-Pressure Feeder or Air-Lock Feeder marketed by Andritz, or a screw-type screw-type feeder as described in U.S. Patent 5,766,418. 7 The suspension liquid may consist of a liquid available in the pulp mill, such as fresh water, steam condensate, cranberry white liquor, black liquor, green liquor or sulfur liquor or any other liquid derived from the boiling process. The liquid may consist of a heated liquid, e.g. hot water or steam with a temperature of 50 - 100 ° C. If the vessel is a pressurized vessel, liquid temperatures above 100 ° C can be used. The liquid may, although not necessarily, contain at least one active cooking chemical, Lex sodium hydroxide (NaOH), sodium sul fi d (NAZS), polysul fi d, anthraquinone or their equivalents or derivatives.
    The pressure generating and transporting device in steps (c) and (d) is preferably one or more suspension pumps. The transport system may also contain one or fl your storage or ironing containers as well as transport devices.
    The one or more transport devices may include at least one device with degassing capacity so that undesirable air or gas can be removed from the suspension. During transport, the chips may be subjected to a treatment of some kind, e.g. deaeration or impregnation with a liquid, preferably a liquid containing cooking chemicals, such as those described above. The suspension can also be subjected to at least one pressure variation during transport, such as the pressure changing from a first pressure to a second, higher pressure and then to a third pressure which is lower than the second pressure. As described in U.S. Patents 4,057,461 and 4,743,338, the pressure variation in a suspension of ice and lye improves the impregnation of the chips with this lye. The pressure pulsations can be achieved by varying the outlet pressure in a series of transport devices or by controlled pressure relief in the suspension between the pumps.
    The material does not have to come into contact with liquid in the vessel, but the liquid can be fed into this first in or below the outlet of the vessel by means of a jet pump arranged there. This liquid is preferably pressurized so that the material and the liquid form a pressurized suspension of material and liquid.
    The treatment vessel in step (d) may typically be a basin vessel as described above, preferably a DlAMONDBAClÖD basin vessel. The vessel can also consist of a storage or leveling container in which the material is stored before the treatment. Since the transport process may require extra lye which is not needed during the treatment or storage, a dewatering device of some kind may be arranged between the transport device and the treatment vessel. A preferred dewatering device is a Top Separator marketed by Andritz. This Top Separator can be of standard type or a "reverse" Top Separator. The device can be a separate unit or be mounted directly on the treatment vessel. The liquid removed from the suspension by the dewatering device is returned to the first vessel or to the transport device to serve as a suspension liquid.
    The liquid can also be used elsewhere where it is needed in the pulp mill.
    The liquid can be heated or cooled as desired. The liquid can e.g. heated by bringing it into indirect heat exchange contact with any hot liquid stream, e.g. a wastewater stream with a temperature higher than S0 ° C. The liquid is also typically pressurized by using one or more conventional centrifugal type liquid pumps.
    The treatment vessel in step (d) may be a basing vessel which feeds one or more of the transport devices of the type described above.
    Feeding of chips for a cooking process is not limited to a chemical pulping process, but can be used in any other cooking process where för distributed cellulosic bone material is moved from one place to another. The pulping processes to which the invention can be applied include all chemical pulping processes, all mechanical pulping processes and all chemical mechanical or thermomechanical pulping processes for batch or continuous treatment.
    Not only does the invention reduce the size of the system for transporting non-distributed cellulosic support material and its costs, but if the non-distributed cellulosic support material is treated during transport, the number and size of the actual treatment vessels can be reduced. The system can e.g. eliminate the need for conventional pre-treatment or impregnation vessels before the boiler. The system also has the potential to improve the pulp mill's overall energy economy. This and other aspects of the invention will become apparent from the detailed description and drawings below.
    The main object of the present invention is to provide a simple and efficient system for feeding suspension of cellulosic material to a treatment vessel such as a continuous boiler, and at the same time to provide improved operating and maintenance properties. This and other objects of the invention will become apparent upon reading the detailed description of the invention and of the appended claims.
    BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a typical prior art system for feeding a suspension of atomized cellulosic material to a continuous digester; FIG. 2 shows another prior art system for feeding a suspension of atomized cellulosic material to a continuous digester; FIG. 3 shows a typical embodiment of a system for feeding a suspension of distributed cellulosic material to a continuous boiler according to the invention; and FIG. 4 shows another embodiment of the invention.
    DETAILED DESCRIPTION OF THE DRAWINGS Although the systems shown and described in FIG. 1 - 3 is the continuous boiler sister, it is understood that the method and apparatus of the present invention may also be used to feed one or more batch boilers or an impregnation vessel connected to a continuous boiler. The continuous boilers shown and which can be used in connection with the invention are preferably continuous boilers of the KAMYR® type and can be used for kraft (ie sulphate) cooking, salt cooking, soda cooking or similar processes. Specific cooking processes and equipment that may be utilized include the MCC®, EMCC® and Lo-Solidsw processes and cookers marketed by Andritz Inc. Strength and exchange enhancers such as anthraquinone, polysul fi d or their equivalents or derivatives may be used in cooking processes utilizing the present invention.
    FIG. 1 shows a typical system 10 according to the prior art for feeding a suspension of distributed cellulosic material, e.g. softwood chips to the upper end of a continuous boiler 11. The boiler 11 typically contains a liquor extraction strainer 12 at the boiler inlet 13 for removing overflow endings from the suspension and returning to the feed system 10. The boiler 11 also contains at least one liquor extraction strainer 14 for draining effluent during or after the cooking process. The cooker ll typically contains one or more additional strainer screens (not shown) which may be connected to the coccyx cifulcation, such as a Mcc®, Emcc kok ococafe cooker or a Lo-Solids® cooker's circulation with a liquor extraction line and a dilution end supply line. Koklut, e.g. kraft white liquor, black liquor or green liquor can be added in these circulations. The boiler 11 also contains an outlet 15 for discharging the chemical mass produced which can be passed on to subsequent treatment such as washing and bleaching.
    In the prior art feeder system 10 shown in FIG. 1 Distributed cellulosic base material 20 is fed into the ice bin 21. The material 20 typically consists of softwood or deciduous ice, but other distributed cellulosic base material of other types, such as sawdust, grass, straw, bagasse, kenaf or agricultural waste of these types can be used or Although the term "wood chips" in the following description is used to refer to the non-distributed cellulosic material, it is understood that the tin is not limited to wood chips but refers to any form of non-distributed cellulosic material listed above or the like.
    The chip bin 21 may be a conventional vibrating discharge ice bin or a DlAMONDßACKgi base vessel described in U.S. Patent 5,500,083 and marketed by Andritz Inc., which does not have a vibrating discharge but an outlet which exhibits one-dimensional convergence and lateral release. The bin 21 contains an air locking device at its inlet and devices for monitoring and regulating the ice level in the bin and a small valve with control means for regulating the pressure in the bin.
    Fresh steam or steam generated by evaporation of effluent (ie relaxation steam) is typically supplied to the bin 21 via one or more of the conduits 22.
    The bin 21 typically dispenses into a dispenser 23, e.g. a Chip Meter marketed by Andritz, but other devices, such as a screw-type dispenser, can also be used. The dispenser 23 dispenses into a pressure relief device 24, such as a Low-Pressure Feeder marketed by Andritz. The pressure relief device 24 separates the pressurized horizontal treatment vessel 25 from the substantially atmospheric pressure prevailing above the device 24.
    The vessel 25 is used to treat the material with pressurized steam, e.g. steam with a pressure of about 0.7 - 1.4 bar (10 - 20 psig). The vessel 25 can, like the Steaming Vessel marketed by Andritz, screw type. Fresh curing steam is supplied to the vessel 25 via one or more lines 28. containing a conveyor of or After treatment in the vessel 25, the material is fed to a high pressure feeder 27, such as a High-Pressure Feeder marketed by Andritz. The base material is typically transferred to the feeder 27 by a conduit or shaft 26, such as a Chip Chute marketed by Andritz. Heated cooking cloth, e.g. a mixture of strong liquor and white liquor is typically supplied to the shaft 26 via the conduit 29 so that a suspension of material and liquor is formed in the shaft 26.
    If the prior art system of FIGJ utilizes a DlAMONDBACKal basing vessel described in U.S. Patent 5,000,083, which provides improved basing under atmospheric pressure, the pressure treatment vessel 25 and the pressure separation device 24 may be dispensed.
    The conventional High-Pressure Feeder 27 has a low-pressure inlet connected to the shaft 26, a low-pressure outlet connected to the line 30, a high-pressure inlet connected to the line 33, a high-pressure outlet connected to the line 34 and a rotor provided with a shaft driven by an electric motor with speed control and a gear (not shown).
    The low pressure inlet leads the heated ice suspension from the shaft 26 into an additional 10 15 20 25 30 534 058 12 in the rotor. A strainer in the outlet 30 of the feeder 27 holds the ice in the rotor, but allows the liquor in the suspension to flow through the rotor to be removed via the line 30 and the pump 31. As the rotor rotates, the ice retained in the rotor is subjected to high pressure discharge from the pump 32 This high-pressure sludge entrains the ice from the feeder and carries it to the upper end of the digester 11 via line 34. When the stream of ice and liquor reaches the inlet of the digester 11, some of the liquor used to transport the ice is removed from the suspension via the strainer 12. in the line 34.
    The overflow closure drawn off via the strainer 12 is returned to the inlet of the pump 32 via the line 35. The liquor in the line 35, in which fresh cooking liquor can be added, is pressurized in the pump 32 and passed in the line 33 to the feeder 27 to flush the ice out thereof.
    The chips held by the strainer 12 move downwards in the digester 11 for further treatment.
    The liquor removed from the feeder 27 via the line 30 and the pump 31 is recycled to the shaft 26 above the feeder 27 through the line 36, the sand separator 37, the line 38, the filter 39 and the line 29. The sand separator 37 is a cyclone type separator for removing sand and other particles from luten. The filter 39 is a static screen device which removes overflow end from line 38 and passes it through line 39 'to a level container 40 for storage there. Lye stored in the container 40 is returned to the upper end of the digester via line 41, pump 42 (ie the replacement end pump) and line 43. Fresh cooking liquor can also be added to lines 41 and 43.
    FIG. 2 shows another prior art system 110 for feeding ice to a digester. The system uses processes and equipment described in U.S. Patents 5,476,572, 5,635,025 and 5,622,598. This equipment and processes which they utilize are marketed under the trademark Lo-Levelm by Andritz. The components of FIG. 2 which are identical to those shown in FIG. 1 has been denoted by the same reference series. The components that are similar or perform similar functions to those shown in FIG. 1 has been denoted by the same reference numerals as in FIG. 1 but provided with the prefix "1".
    As in the system of FIG. 1, chips 20 are fed into the basing vessel 121 where it is exposed to steam which is fed via line 22. The vessel 121 discharges to the dispenser 123 and then to line 126, which is preferably a Chip Tube marketed by Andritz. Boiling cloth is typically fed into the pipe 126 via line 55, which is similar to line 29 in FIG. 1. Since the vessel 121 is preferably a DIAMONDBACKQ basing vessel according to U.S. Patent 5,000,083, no pressure separating device 24 or pressurized basing vessel 25 as in FIG. 1 of this prior art system.
    As shown in U.S. Patent 5,476,572, a high pressure suspension pump 51 fed by line 50 is used to transport the ice to the feeder 27 via line 52, instead of discharging the suspension of ice and lye directly to the feeder 27. The chips are passed via the pump 51 to the digester 11 by the feeder 27 in a manner similar to that described and shown in connection with FIG. 1.
    The system of FIG. 2, in addition to the pump 51, the pump 31 in FIG. In order to bring the suspension to the feeder 27. The pump 51 provides the driving force needed to pass the liquor through the feeder 27, the line 30, the sand separator 37, the filter 39 and the line 129 to the level container 53 for the liquor.
    The operation of the level container 53 is described in U.S. Patent 5,622,598. The container 53 ensures a sufficient supply of liquor to the inlet of the pump 51, via the line 54.
    The container can also supply liquor to the tube 126 via line 55. The liquor container 53 also allows the operator to change the liquor level in the feed system so that the liquor level, if desired, can be raised to the level of the dispenser 123 or even to the level of the bin 121.
    This possibility is also described in U.S. Patent 5,635,025.
    FIG. 3 shows a preferred embodiment of a feed system 210 according to the present invention which further simplifies those of FIG. 1 and 2 show the feed systems according to the prior art. In the preferred embodiment shown in FIG. 3 has the high pressure feeder, component 27 of FIG. 1 and 2, eliminated. Instead of feeding fl ice to the feeder 27 by means of gravity in the shaft 26 in FIG. 1 or via the pump 52 in FIG. 2, at least two high pressure suspension pumps 251, 251 'are used to transport suspension to the inlet of the digester 11. The components of FIG. 3 which are substantially identical to those shown in FIG. 1 and 2 have been denoted by the same reference numerals. The components which are similar or perform similar functions 534 (158 l 4 as those shown in Figs. 1 and 2 have been denoted by the same reference numerals as in Figs. 1 and 2 but provided with the prefix "2".
    As in the process of FIG. 1 and 2, the ice 20 of the present invention is fed into the basing vessel 221. The chips are preferably fed by a sealed horizontal conveyor as shown in U.S. Patent 5,766,418. one or more lines 22. The basing vessel 221 is typically provided with conventional monitoring and control devices as well as a pressure relief valve (not shown). The vessel 221 dispenses base ice to the dispenser 223 which, as described above, may be a rotor-type device with a core, such as a chip meter, or a screw-type device.
    In one embodiment of the invention, the dispenser 223 extends directly to the conduit or shaft 226. In an alternative embodiment, a pressure separation device, such as a rotor-type separation device with corners, shown in dotted lines at 224, e.g. a conventional Low-Pressure Feeder, be arranged between the dispenser 223 and the shaft 226. If the pressure in the shaft 226 without the pressure separating device 224 is substantially atmospheric, the pressure in the shaft 226 with a pressure separating device 224 may be between 0.07 - 3.5 bar (1 and 50 psig), but is preferably 0.3 - 1.7 bar (5 - 25 psig) and most preferably 0.7 - 1.4 bar (10 - 20 psig). Boiling cloth is added as described above in the shaft 226 (see line 226 'in FIG. 3) so that a suspension of chips and lye is formed in the shaft 226 with a detectable level (not shown). The suspension in the shaft 226 is discharged via a curved outlet 250 to also the inlet of the pump 251. The feed of suspension into the inlet of the purge 251 is typically increased by a lye flow from the container 253 via the conduit 254 as described in U.S. Patent 5,622,598.
    The pump 251 is a centrifugal high pressure centrifugal suspension pump, such as a "Hydrostal" pump from Wemco, Salt Lake City, Utah. The pump may alternatively consist of a suspension pump from Lawrence Company. The pressure at the inlet of the pump 251 can vary from atmospheric pressure to 3.5 bar (50 psig) depending on whether a pressure separating device 224 is used or not. In the preferred embodiment shown in FIG. 3 discharges the pump 251 to the inlet of the pump 251 '. The pump 251 'is preferably of the same type as the pump 251 with the same or a higher pressure value. If two pumps are used, the pressure generated in the outlet of the pump 251 'is typically 10 - 27.5 bar (150 - 400 psig) (ie 105 - 280 meters or 345 - 920 feet of water column) but preferably about 14 - 21 bar (200 - 300 psig) (140 - 210 meters or 460 - 690 feet). If necessary, the amount of lye in the suspension can be increased with lye from the container 253 via line 56 and the liquid pump 57. Although the embodiments shown in FIG. 3 contains two pumps, alternatively a single or three or two pumps in series or in parallel can be used. In that case, the outlet pressure from this one pump or from the last pump is preferably the same as the outlet pressure from the pump 251 'above.
    The pressurized, typically heated, suspension is discharged from the pump 251 'to line 234. Line 234 for the suspension to the inlet of the continuous boiler 11. Overflow end in the suspension is drained via the screen 12 in a conventional manner. The overflow liquid is returned to the feed system 210 via line 235, preferably to the liquor container 253 to be used for suspension in line 250 via line 254. The liquor in line 235 can be passed through a sand separator 237 if desired.
    This sand separator can be designed for pressurized or pressureless operation depending on the desired mode of operation.
    Unlike the prior art systems, which use a High-Pressure Feeder (27 in FIGS. 1 and 2) which uses the pressure of the liquor returned via the line 35 as an essential part of the method of transferring the ice from the High-Pressure Feeder to the boiler 11 is liquid-borne, it is not essential for the practice of the present invention that the pressurized recirculation liquid 235 be returned to the inlet of the pumps 251, 251 '. The compressive energy in the flow in line 235 can be used anywhere in the factory where it is needed. In a preferred embodiment, however, the present invention utilizes the pressure in line 235 to minimize the energy requirements of pumps 251 and 251 'as far as possible. 10 15 20 25 30 534 058 16 How the pressure in the return line 235, typically about 10 - 27.5 bar (150 - 400 psig), is used depends on how the supply system 210 works. If the vessel 226 operates without pressure - at substantially atmospheric pressure - the pressurized liquor returned in line 235 must be returned to a substantially atmospheric pressure before being fed into line 250. One way to do this is to use a pressure control valve 58 and a pressure gauge 59 in the line 235. The opening in the valve 58 is controlled so that a predetermined pressure prevails in the conduit 235 downstream of the valve 58. In addition, the liquor container 253 must be designed so as to act as a relaxation vessel so that the hot pressurized liquor in the conduit 235 quickly evaporates to form a steam source. in the vessel 253. The steam can b1.a. be used in the vessel 221 via line 60. In a preferred embodiment, however, the pressurized liquor in line 235 is used to extend the flow from the pump 251 ', e.g. via line 61 and pump 62. The pressure in line 235 can also be used to increase the flow between the pumps 251 and 251 'in line 252 via line 63, with or without pump 64 (a non-return valve can in some cases be used instead of pumps 62, 64 or more). By reusing some of the pressure in the line 235, the energy requirements of the pumps 251 and 251 'can be reduced.
    The heat of the liquor in line 235 can also be brought into friendly exchange contact with one or more other liquids in the pulp mill which need to be heated.
    The pumps 251, 251 'can be used together with a jet pump to increase the pressure in the inlet or outlet of the pumps. A jet pump can also be used as a means of feeding liquid into the ice. A jet pump can e.g. be arranged in the outlet of or under the vessel 226 and liquid is first fed into the ice by means of this jet pump.
    The jet pump may include a venturi type opening in one or more of the lines 250, 252 and 234 into which a pressurized liquid stream is fed. The pressurized liquid can be obtained from any available source, but is preferably taken from line 235 upstream of valve 58. An exemplary jet pump is shown schematically at 70 in FIG. 3.
    One of the data of High-Pressure Feedem 27 in FIG. 1 and 2 is to function as a shut-off valve to prevent the pressure from disappearing in the equipment and the transport lines, e.g. wires 34 and 35 in FIG. 1, if any of the feeder components should malfunction or strike. In the feed system according to the present invention, there are alternative means for preventing loss of pressure due to errors or malfunctions. FIG. 3 shows e.g. a one-way (check) valve 65 in line 234 to prevent a pressurized flow from flowing back to pump 251 or 251 ”. Conventional automatic (eg, solenoid-controlled) shut-off valves 66 and 67 are further provided in respective lines 234 and 235 to separate the pressurized lines 234, 235 from the rest of the supply system 210. In a preferred mode of operation, a conventional pressure switch 68 is provided downstream of the pump. 251 'in line 234. The function of the switch 68 is to monitor the pressure in line 234 so that the conventional control means 69 automatically isolates the digester 11 from the supply system 210 by closing valves 66 and 67 if the pressure deviates from a predetermined value. The valves may also be arranged to close automatically when a flow direction detector screens a reversal of the direction of fate in line 234. Although the above-described devices for preventing pressure relief are preferred, other arrangements of valves, detectors, indicators, alarms or the like may be used to prevent significant lowering the pressure in the boiler ll. Although the system 210 is preferably used in conjunction with a continuous boiler 11, it may also be used in conjunction with other vertical treatment vessels having a higher than atmospheric pressure (typically a pressure of at least about 10 bar overpressure) with an upper inlet, such as an impregnation vessel or a batch boiler.
    FIG. 4 shows a further embodiment of the invention where the ice transport concept has been extended from the feed system for a boiler to feed from a pulp mill's wood yard. FIG. 4 shows a system 510 for feeding finely divided cellulosic material to a pulp manufacturing process. The system consists of a subsystem 410 for feeding chips from the wood yard into the system 510 and a subsystem 310 for treating and feeding ice to the digester 11. The subsystem 310 is substantially identical to the system 210 shown in FIG. 3. 10 15 20 25 30 534 G58 18 The components of FIG. 4 which are substantially identical to those shown in FIG. 1 - 3 have been denoted by the same reference numerals. The components that are similar or perform similar functions to those shown in FIG. 1 ~ 3 have been denoted by the same reference numerals as in FIG. 1 but provided with the prefix "3". The wood yard in conventional pulp mills can be supplied with wood of various shapes as described above. Wood or other cellulosic bone material is typically converted to ice and stored in open ice piles or ice storage silos. In FIG. 4 shows an ice storage consisting of an ice pile 80. In a preferred embodiment, the ice is transported from the pile 80 or some other storage by conventional means, e.g. a conveyor or a front loader (not shown) and fed into the vessel 81. This vessel may be a DlAMONDBACKqb vessel or a conventional storage vessel. The vessel 81 can operate at a higher than atmospheric pressure, e.g. 0.1 - 5 bar. If the vessel operates at a higher than atmospheric pressure, a pressure separating device (not shown) of some kind may be provided at the inlet of the vessel to prevent relief of the pressure. The device may be a stem-type separator, such as a Low-Pressure Feeder or Air-Lock Feeder marketed by Andritz, or a screw-type screw-type feeder as described in U.S. Patent 5,766,418.
    Liquid, e.g. fresh water, steam, liquid containing cooking chemicals, is fed into the vessel 81 via one or more conduits 82 to form a suspension of liquid and fl ice and to provide a detectable liquid level in the vessel 81. Devices for monitoring and regulating the liquid level and fl ice level in the vessel 81 may be arranged. The liquid may consist of a heated liquid, e.g. hot water or steam with a temperature of 50 - 100 ° C. If vessel 81 is a pressurized vessel, liquid temperatures above 100 ° C may be used. The liquid preferably but not necessarily contains at least one active cooking chemical, e.g. sodium hydroxide (NaOH), sodium sulden (NazS), polysulden, anthraquinone or its equivalents or derivatives.
    From the vessel 81 the suspension flows out to the inlet of the suspension pump 85 via the line 84. The outflow from the vessel 81 can be made more efficient by means of a release device 83. The suspension flow in the line 84 can also be made more efficient by supplying liquid via the line 82 '. The pump 85 may be a suspension pump of the type described above. for example a Wemco or Lawrence purnp or the like or a suspension conveyor of another type. Although only a single pump 85 is shown, any pump or similar device may be used to transport the suspension via line 86 to vessel 321. The suspension transport via line 86 may contain one or more storage or equalization containers (not shown). The one or more pumps 85 contain at least one device with degassing capacity so that undesired air or gas can be removed from the suspension. The pressure in line 86 depends on the number of pumps and other transport devices used and how high and how far the suspension is to be transported. The pressure in line 86 can range from about 0.3 to over 35 bar (about 5 to over 500 psig).
    During transport, the ice can also be subjected to a treatment of some kind, e.g. precipitation or impregnation with a bag, preferably a liquid containing chemicals such as those described above. The suspension may also be subjected to at least one pressure variation during transport, such as changing the pressure from a first pressure to a second, higher pressure and then to a third pressure lower than the first pressure. As described in U.S. Patents 4,057,461 and 4,743,338, the pressure variation in a suspension of fl ice and lye improves the impregnation of fl ice with this lye. The pressure pulsations can be achieved by varying the outlet pressure in a series of transport devices or by controlled pressure relief in the suspension between the pumps.
    The suspension in line 86 is fed into the inlet of vessel 321. Even if the vessel shown is a treatment vessel, ie. a base vessel, it can also be a storage vessel, an impregnation vessel or even a digester. Since the transport in the line 86 typically requires overflow liquid at least to some extent, which is not needed during the treatment or storage, a dewatering device of some kind must be arranged between the transport device and the treatment vessel. A preferred dewatering device is a Top Separator marketed by Andritz. This Top Separator can be of standard type or a "reverse" Top Separator. The device may be an external separate unit or one mounted directly on the treatment vessel as shown. The liquid removed by means of the suspension dewatering device 87 is returned to the vessel 81 or to the inlet of the pump or pumps 85 via the line 88 to serve as a suspension liquid for the ice. The liquid removed via the device 87 can also be used elsewhere where it is needed in the pulp mill. The liquid in line 88 can be heated or cooled as desired in a heat exchanger 90 and can be pressurized using one or more conventional centrifugal type liquid pumps 89. The liquid in line 88 can be fed into the vessel 81 via line 82 and into line 84 via line 82 '.
    The treatment vessel 321 shown is a basing vessel similar to the vessel 221 shown in FIG. s, Lex. a DIAMONDBACKQbaSmngSkän. Marafsysreme: 310 is otherwise: similar to system 210 in FIG. 3. The chip feeding system 410 feeds e.g. the feed system 310 which feeds the digester ll. Note that subsystem 310 of FIG. 4 is a subsystem of the total system which feeds fl ice from fl ice pile 80 to the digester ll.
    The system may include one or more subsystems 310 for feeding to the digester 11.
    The invention enables, to the widest extent, transport and treatment in steg your steps of celluldistributed cellulosic ñber material with economical recovery and reuse of energy, i.a. heat energy. Although the invention has been described above in connection with what is currently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the embodiments described above and shown in the drawing, but may be modified within the scope of the appended claims.
    权利要求:
    Claims (3)
    [1]
    A system (210, 310) for feeding disintegrated cellulosic material in the production of chemical pulp, comprising: a basing vessel (221, 321) in which disintegrated cellulosic material is based to remove air therefrom; and a pressurized vertical treatment vessel (11) having an inlet for a suspension of fi divided cellulosic material in its upper part and an outlet in its lower part; characterized in that it further comprises a pressure generating feed device for pressurizing a suspension of material from the basing vessel and transferring it to the inlet of the treatment vessel, which pressure generating feeding device consists of one or more high pressure suspension pumps (251, 251 ', 351, 351') below the upper part of the treatment vessel; and a liquid return line (235) from the upper part of the treatment vessel, which return line is operatively connected to an outlet in one of the suspension pumps.
    [2]
    A system according to claim 1, wherein the liquid return line (23 5) is connected to a pressure reducing device for reducing the pressure of the liquid in the return line before the liquid is conveyed to the outlet of the suspension pump.
    [3]
    The system of claim 2, wherein the pressure reducing device comprises a pressure regulating valve (58) in the return line.
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    同族专利:
    公开号 | 公开日
    SE0500751L|2005-04-06|
    SE526024C2|2005-06-14|
    AU4665097A|1998-05-22|
    FI990889A|1999-06-24|
    SE0802039L|2008-09-29|
    JP3524558B2|2004-05-10|
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    SE9901362L|1999-06-18|
    FI990889A0|1999-04-19|
    ES2197719A1|2004-01-01|
    SE9901362D0|1999-04-16|
    SE0402204D0|2004-09-15|
    US5753075A|1998-05-19|
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    SE0402204L|2004-09-15|
    FI122896B|2012-08-31|
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    WO1998019000A1|1998-05-07|
    JP2001503112A|2001-03-06|
    BR9712631A|1999-10-26|
    CA2265649A1|1998-05-07|
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    法律状态:
    优先权:
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    PCT/US1997/017780|WO1998019000A1|1996-10-25|1997-10-07|Method and system for feeding comminuted fibrous material|
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