CA1063406A - Method and apparatus for producing fiber pulp in a steam-pressurized grinding apparatus - Google Patents
Method and apparatus for producing fiber pulp in a steam-pressurized grinding apparatusInfo
- Publication number
- CA1063406A CA1063406A CA281,626A CA281626A CA1063406A CA 1063406 A CA1063406 A CA 1063406A CA 281626 A CA281626 A CA 281626A CA 1063406 A CA1063406 A CA 1063406A
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- CA
- Canada
- Prior art keywords
- steam
- cyclone
- grinding
- separated
- accompanying
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
METHOD AND APPARATUS FOR PRODUCING FIBER
PULP IN A STEAM-PRESSURIZED GRINDING APPARATUS
ABSTRACT OF THE DISCLOSURE
Method and apparatus for producing pulp from moisture-con-taining lignocellulosic material, such as wood chips, which is ground in a grinding space defined between a pair of grinding discs which rotate relative to one another in an environment of pressurized steam generated during the grinding process, in a clos-ed housing. The grist discharged from the grinding housing is pro-pelled by the accompanying steam into a cyclone, where the grist is separated from the steam for further treatment, while the steam is recycled for further use in the pulping process. The pressure in the cyclone is so controlled that a pressure is maintained therein which is substantially equal to a pressure drop which is sufficient merely to maintain the propellant force of the steam to convey the grist from the grinding housing to the cyclone while discharging the separated steam and recycling it for further use in the pulping process.
PULP IN A STEAM-PRESSURIZED GRINDING APPARATUS
ABSTRACT OF THE DISCLOSURE
Method and apparatus for producing pulp from moisture-con-taining lignocellulosic material, such as wood chips, which is ground in a grinding space defined between a pair of grinding discs which rotate relative to one another in an environment of pressurized steam generated during the grinding process, in a clos-ed housing. The grist discharged from the grinding housing is pro-pelled by the accompanying steam into a cyclone, where the grist is separated from the steam for further treatment, while the steam is recycled for further use in the pulping process. The pressure in the cyclone is so controlled that a pressure is maintained therein which is substantially equal to a pressure drop which is sufficient merely to maintain the propellant force of the steam to convey the grist from the grinding housing to the cyclone while discharging the separated steam and recycling it for further use in the pulping process.
Description
FIELD OF THE INVENTION
_ This invention relates to a method and a de~ice for producing fiber pulp in a steam-pressurized grinding apparatus.
More particularly this invention relates to a method and a device for producing fiber pulp by grinding OL li~nocellulose-con-taining material in a steam-pressurized grinding apparatus, the ground pulp from the grinding apparatus being conveyed together with steam present therein through a pipe duct to a cyclone where fiber and accompanying steam àre separated from one another and the ground fiber conveyed therefrom for further treatment.
BAC~GROUND OF THE INVENTION
In the manufacture of refiner-mechanical or thermomechanical fiber pulps from lignocellulose-containing material, the material treated in the grinding apparatus normally is supplied with so much .. ~
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1(~6;~406 - of energy that moisture accompanying the material is rapidly vaporized, due to temperature above 100C produced by friction.
In order to prevent the material from being dried out during the grinding procedure, with consequent exposure to excessive temper-atures which are undesirable for the process, a quantity of water is added during the grinding operation to replace the amount of - water evaporated from the material.
This results in the generation during the grinding process of great quantities of steam, which steam must be removed from the grinding apparatus so as to avoid interference with the flow of ; material through the apparatus. In order to make full use of the heat content of the steam, the steam removal must be effected un-der the highest possible pressure without use of arrangements which might interfere with the pulping process.
~AIN OBJECTS ~OF THE INVENTION
Thus, one main object of the invention is to provide a method `'t in connection with a steam-pressurized grinding apparatus from ` which the steam is removed at the highest possible pressure.
Another main object of the invention is to provide a method . 20 ensuring that the flow of material through the grinding apparatus . and further pulp production process remain undisturbed despite withdrawal of the steam produced in the grinding apparatus under this high pressure.
Still another object of the invention is to provide an ap-paratus for carrying out the method of the invention in a simple ~ and nevertheless reliable and easily controllable manner.
; SUMMARY OF THE INVENTION
These and other objects of the invention are achieved by discharging the separated fibers in a vapor-proof manner from the receiver cyclone and so as to maintain in the cyclone a steam pressure substantially exceeding atmospheric pressure~ In a pre-ferred embodiment, there is maintained in the receiver cyclone . . .
a steam pressure which is only so much lower than the steam pres--. .
1(3634(~6 sure maintained in the grinding apparatus as to create a pressure drop sufficient to propel the fibers through the duct system. The steam separated off in the receiver cyclone can then at a corres-ponding high pressure be conducted either directly or through simple or series-connected cleaning means to other processes which require steam under superatmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawing is a diagrammatic side view of a plant for carrying out the method of the invention and which forms part of this specification.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing, reference numeral 10 denotes a storage bin for lignocellulose-containing starting material, e.g., wood chips, which are fed by means of a screw feeder 12 driven by a motor 11 and provided with a plug former 13 into a steam-pressurized reaction vessel 14 in which the material is pre-heated. The steam is supplied from a source not shown through a pipe 15 to the vessel 14 for preheating the material. The bottom of the vessel 14 opens into a conduit in which a conveyor screw 16 for advancing the wood material is rotated by a motor 17, which conduit is connected to a grinding apparatus operated under steam pressure, such as a disc refiner 18, which comprises a closed cas-ing 19 within which are disposed a stationary grinding disc 20 and a rotatable grinding disc 23 mounted on a shaft 21 in a frame 22.
The starting material supplied by the conveyor screw 16 is passed through and, during the passage, defibrated in the grinding gap 24 between the ~iscs 20, 23 rotating relatively to one another. The heat produced by friction during the disintegration of the mater-ial evaporates moisture accompanying said material and the steam ~' ~0 generated there~y streams partially back through the screw 16 or --separateIy arranged steam channels (not shown) into the reaction ~-vesseI 14, where the heat content of the steam is utilized for heating the material fed into the reaction vessel 14 to desired :: A -3- ~
~63~6 temperature. A portion of the steam generated in the grinding apparatus streams outwards together with the ground material through the grinding gap 24 between the grinding discs 20, 23 into the casing 19 enclosing said grinding discs.
The defibrated material collected in the grinding disc casing 19 is conveyed therefrom by the steam escaping from the gap 24 be-: tween the grinding discs through a blow valve 25 and a pipe duct 26 to a receiver or separating cyclone 27 for separating of fibers and steam from one another. The cyclone 27 is at its lower end in a vapor-tight manner connected to a discharge means 28 by which the fiber pulp separated off in the cyclone is discharged from the cyclone 27. The discharging means 28 used in this connection is of a type which permits discharge of the fiber pulp in a vapor-tight manner from the separating cyclone 27 and may, for example, comprise a high density pump, a gear pump, a compresser screw feed-er or a cell feeder or other similar conventional discharge means.
; By using a cell feeder as discharge means 28, it is possible to evacuate air in the cells by means of steam and thereby prevent such air from entering the cyclone 27.
i 20 A steam outlet pipe 29 extends from the top portion of the cyclone 27. Said pipe 29 is equipped with a valve 30 for control-ling the steam pressure in the cyclone 27. The valve 30 serves to maintain a steam pressure in the cyclone 27 which substantially is equal to the pressure drop required for propelling the material ;~ 25 from the refiner 18 to the cyclone 27, and is thus only that much lower than the steam pressure maintained in the refiner 18. The *alve 30 is controlled via a conductor wire 31 by a pressure dif-ferential governor 32 which in turn through conductor wires 33 and 34 is coupled to, respectively, the refiner 18 and the cyclone 27 ; 30 and which continuously is actuated by the steam pressures prevail-ing in said refiner and cyclone, respectively. The steam from the ~' outlet tube 29 may, for example, be supplied to an additional steamcleaning cyclone 35 within which fibers accompanying the steam are : A ~4~
.
34~)6 separated off and through a screw feeder 36, which is driven by a motor 37, returned to the cyclone 27, or to an outlet tube 38 from - the discharge means 28, as is indicated by dashed lines at 39.
The surplus steam from the steam-cleaning cyclone is supplied via an outlet tube 40 with valve 41 and pressure governor 42 to some process or plant where the steam under excess pressure is utilized.
The governor 42 controls the valve 41 via a conductor wire 43 and is actuated by the pressure in the tube 49 ahead of the valve 41 and by an external operation source via conductor wires 44, 45.
Supplied to the fiber pulp before the feeding thereof into the cy-clone 27 or within the same via pipes 46, 47 with valves 48, 49 is the quantity of dilution liquid required for the further working or treatment of the material with or without addition of chemicals.
The fiber pulp can be fed from the outlet pipe 38 of the high density pump 38 or the like member by a screw feeder 51 driven by a motor 50 into, for example, a directly connected second grinding ` apparatus such as a disc refiner 52. This second disc refiner 52 - comprises, as does the first mentioned refiner 18, a closed casing - 53 within which are housed a stationary grinding disc 54 a~d:a ro-tatable grinding disc 57 mounted on a shaft 55 on a stand 56. From the second refiner the fiber pulp is discharged through an outlet tube 58 controlled by a valve 59 to additional process steps and further treatment.
It is obvious that the second refining of the fiber pulp in the refiner 52 can be replaced in some cases by some other treat-ment. In such a case, there is inserted behind the high density ~' pump 38 or similar member, a screw feeder (not shown) or other feed-J, er de~ice which conveys the fibex pulp further in the process. It, is understood from the above description, that by the method and device of the inVention, a steam removal is ensured at the highest possible pressure without interfering with the normal pulping pro-cess. The pressure difference between the first refiner 18 and the separating cyclone 27 is in this connection suitably adjusted ,' 1(~6~41~?t;
so that it is substantially only equal to the pressure drop neces-sary for propelling the fiber pulp through the duct 26,:and, to this extent, is below the steam pressure maintained in the refiner 18. In this manner, a considerably improved heat economy in the process is obtained, since the separated steam under corresponding excess pressure can be conducted further to other processes which require or can make use of steam under this high pressure.
As already mentioned, the fiber pulp can be supplied after the separating cyclone 27 by the discharge means 38 to any arbi-trary treating process depending on the intended further utili-zation of the pulp.
While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for the pu~pose of illustration only, and that the invention is not . 15 to be limited thereby, but its scope is to be defined by the ap-:, .
pended claims.
.
..
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., .
., :
'' '.
, ;
~'' : A
_ This invention relates to a method and a de~ice for producing fiber pulp in a steam-pressurized grinding apparatus.
More particularly this invention relates to a method and a device for producing fiber pulp by grinding OL li~nocellulose-con-taining material in a steam-pressurized grinding apparatus, the ground pulp from the grinding apparatus being conveyed together with steam present therein through a pipe duct to a cyclone where fiber and accompanying steam àre separated from one another and the ground fiber conveyed therefrom for further treatment.
BAC~GROUND OF THE INVENTION
In the manufacture of refiner-mechanical or thermomechanical fiber pulps from lignocellulose-containing material, the material treated in the grinding apparatus normally is supplied with so much .. ~
4~ ~ :S,;;.i ~;
- : , , ' , ; . ', ' : . ' -: : . . '.: . . : ' . ' . ' : :-,'~: , ' ` ~: ~ ' ., ' ' .' . ' - .: ' -," ' ' , '"` ' ' . ' ~ ' :' . . . ' ~ ' :: ' ' ' ` : , : ~ ,' : ' ' . ~ '' ':, . . : -: .
1(~6;~406 - of energy that moisture accompanying the material is rapidly vaporized, due to temperature above 100C produced by friction.
In order to prevent the material from being dried out during the grinding procedure, with consequent exposure to excessive temper-atures which are undesirable for the process, a quantity of water is added during the grinding operation to replace the amount of - water evaporated from the material.
This results in the generation during the grinding process of great quantities of steam, which steam must be removed from the grinding apparatus so as to avoid interference with the flow of ; material through the apparatus. In order to make full use of the heat content of the steam, the steam removal must be effected un-der the highest possible pressure without use of arrangements which might interfere with the pulping process.
~AIN OBJECTS ~OF THE INVENTION
Thus, one main object of the invention is to provide a method `'t in connection with a steam-pressurized grinding apparatus from ` which the steam is removed at the highest possible pressure.
Another main object of the invention is to provide a method . 20 ensuring that the flow of material through the grinding apparatus . and further pulp production process remain undisturbed despite withdrawal of the steam produced in the grinding apparatus under this high pressure.
Still another object of the invention is to provide an ap-paratus for carrying out the method of the invention in a simple ~ and nevertheless reliable and easily controllable manner.
; SUMMARY OF THE INVENTION
These and other objects of the invention are achieved by discharging the separated fibers in a vapor-proof manner from the receiver cyclone and so as to maintain in the cyclone a steam pressure substantially exceeding atmospheric pressure~ In a pre-ferred embodiment, there is maintained in the receiver cyclone . . .
a steam pressure which is only so much lower than the steam pres--. .
1(3634(~6 sure maintained in the grinding apparatus as to create a pressure drop sufficient to propel the fibers through the duct system. The steam separated off in the receiver cyclone can then at a corres-ponding high pressure be conducted either directly or through simple or series-connected cleaning means to other processes which require steam under superatmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawing is a diagrammatic side view of a plant for carrying out the method of the invention and which forms part of this specification.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing, reference numeral 10 denotes a storage bin for lignocellulose-containing starting material, e.g., wood chips, which are fed by means of a screw feeder 12 driven by a motor 11 and provided with a plug former 13 into a steam-pressurized reaction vessel 14 in which the material is pre-heated. The steam is supplied from a source not shown through a pipe 15 to the vessel 14 for preheating the material. The bottom of the vessel 14 opens into a conduit in which a conveyor screw 16 for advancing the wood material is rotated by a motor 17, which conduit is connected to a grinding apparatus operated under steam pressure, such as a disc refiner 18, which comprises a closed cas-ing 19 within which are disposed a stationary grinding disc 20 and a rotatable grinding disc 23 mounted on a shaft 21 in a frame 22.
The starting material supplied by the conveyor screw 16 is passed through and, during the passage, defibrated in the grinding gap 24 between the ~iscs 20, 23 rotating relatively to one another. The heat produced by friction during the disintegration of the mater-ial evaporates moisture accompanying said material and the steam ~' ~0 generated there~y streams partially back through the screw 16 or --separateIy arranged steam channels (not shown) into the reaction ~-vesseI 14, where the heat content of the steam is utilized for heating the material fed into the reaction vessel 14 to desired :: A -3- ~
~63~6 temperature. A portion of the steam generated in the grinding apparatus streams outwards together with the ground material through the grinding gap 24 between the grinding discs 20, 23 into the casing 19 enclosing said grinding discs.
The defibrated material collected in the grinding disc casing 19 is conveyed therefrom by the steam escaping from the gap 24 be-: tween the grinding discs through a blow valve 25 and a pipe duct 26 to a receiver or separating cyclone 27 for separating of fibers and steam from one another. The cyclone 27 is at its lower end in a vapor-tight manner connected to a discharge means 28 by which the fiber pulp separated off in the cyclone is discharged from the cyclone 27. The discharging means 28 used in this connection is of a type which permits discharge of the fiber pulp in a vapor-tight manner from the separating cyclone 27 and may, for example, comprise a high density pump, a gear pump, a compresser screw feed-er or a cell feeder or other similar conventional discharge means.
; By using a cell feeder as discharge means 28, it is possible to evacuate air in the cells by means of steam and thereby prevent such air from entering the cyclone 27.
i 20 A steam outlet pipe 29 extends from the top portion of the cyclone 27. Said pipe 29 is equipped with a valve 30 for control-ling the steam pressure in the cyclone 27. The valve 30 serves to maintain a steam pressure in the cyclone 27 which substantially is equal to the pressure drop required for propelling the material ;~ 25 from the refiner 18 to the cyclone 27, and is thus only that much lower than the steam pressure maintained in the refiner 18. The *alve 30 is controlled via a conductor wire 31 by a pressure dif-ferential governor 32 which in turn through conductor wires 33 and 34 is coupled to, respectively, the refiner 18 and the cyclone 27 ; 30 and which continuously is actuated by the steam pressures prevail-ing in said refiner and cyclone, respectively. The steam from the ~' outlet tube 29 may, for example, be supplied to an additional steamcleaning cyclone 35 within which fibers accompanying the steam are : A ~4~
.
34~)6 separated off and through a screw feeder 36, which is driven by a motor 37, returned to the cyclone 27, or to an outlet tube 38 from - the discharge means 28, as is indicated by dashed lines at 39.
The surplus steam from the steam-cleaning cyclone is supplied via an outlet tube 40 with valve 41 and pressure governor 42 to some process or plant where the steam under excess pressure is utilized.
The governor 42 controls the valve 41 via a conductor wire 43 and is actuated by the pressure in the tube 49 ahead of the valve 41 and by an external operation source via conductor wires 44, 45.
Supplied to the fiber pulp before the feeding thereof into the cy-clone 27 or within the same via pipes 46, 47 with valves 48, 49 is the quantity of dilution liquid required for the further working or treatment of the material with or without addition of chemicals.
The fiber pulp can be fed from the outlet pipe 38 of the high density pump 38 or the like member by a screw feeder 51 driven by a motor 50 into, for example, a directly connected second grinding ` apparatus such as a disc refiner 52. This second disc refiner 52 - comprises, as does the first mentioned refiner 18, a closed casing - 53 within which are housed a stationary grinding disc 54 a~d:a ro-tatable grinding disc 57 mounted on a shaft 55 on a stand 56. From the second refiner the fiber pulp is discharged through an outlet tube 58 controlled by a valve 59 to additional process steps and further treatment.
It is obvious that the second refining of the fiber pulp in the refiner 52 can be replaced in some cases by some other treat-ment. In such a case, there is inserted behind the high density ~' pump 38 or similar member, a screw feeder (not shown) or other feed-J, er de~ice which conveys the fibex pulp further in the process. It, is understood from the above description, that by the method and device of the inVention, a steam removal is ensured at the highest possible pressure without interfering with the normal pulping pro-cess. The pressure difference between the first refiner 18 and the separating cyclone 27 is in this connection suitably adjusted ,' 1(~6~41~?t;
so that it is substantially only equal to the pressure drop neces-sary for propelling the fiber pulp through the duct 26,:and, to this extent, is below the steam pressure maintained in the refiner 18. In this manner, a considerably improved heat economy in the process is obtained, since the separated steam under corresponding excess pressure can be conducted further to other processes which require or can make use of steam under this high pressure.
As already mentioned, the fiber pulp can be supplied after the separating cyclone 27 by the discharge means 38 to any arbi-trary treating process depending on the intended further utili-zation of the pulp.
While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for the pu~pose of illustration only, and that the invention is not . 15 to be limited thereby, but its scope is to be defined by the ap-:, .
pended claims.
.
..
~:`
., .
., :
'' '.
, ;
~'' : A
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method in connection with manufacture of fiber pulp from lignocellulose-containing material comprising the steps of grinding the material in a steam-pressurized grinding apparatus, propelling the ground pulp from the grinding apparatus by the accompanying steam through a pipe duct to a receiving cyclone, separating fiber and accompanying steam from each other and conveying the ground fibers away for further treatment, characterized by the step of discharging the separated fibers in a vapor-tight manner from the receiver cy-clone so as to create a pressure drop in the cyclone sufficient only to maintain the propellant force of the steam while discharging and recycling the separated steam for further use in the pulp-manufac-turing process.
2. The method as claimed in Claim 1, characterized by the further step of adding in the receiving cyclone treating agents re-quired for further carrying out the process.
3. The method as claimed in Claim 1, characterized by the further step of cleaning the steam from the receiving cyclone from accompanying fibers prior to continued utilization.
4. In a device for use in the pulping process in which the fibrous raw material is ground in a steam-pressurized grinding ap-paratus from which it is discharged by means of a blow valve and propelled by the accompanying steam through a pipe duct to a re-ceiving cyclone where fiber and accompanying steam are separated from each other and the ground fibers conveyed away for further treatment, the improvement comprising meaas for discharging the sep-arated fiber from the receiver cyclone so as to create a pressure drop in the cyclone sufficient only to maintain the propellant force of the steam; and means for discharging the separated steam and recycling it for further use in the pulpine process.
5. The device as claimed in Claim 4, further comprising a steam outlet tube from the receiving cyclone fitted with an adjust-able control valve, said valve being arranged to be actuated by the pressure drop between the grinding apparatus and the receiving cy-clone via said control device disposed to react to and adjust said pressure drop.
6. The device as claimed in Claim 4, in which said discharge means comprises a high density pump.
7. The device as claimed in Claim 4, in which said discharge means comprises a gear pump.
8. The device as claimed in Claim 4, in which said discharge means comprises a screw feeder with compression effect.
9. The device as claimed in Claim 4, in which said discharge means comprises a cell feeder.
10. The device as claimed in Claim 4, further comprising a supply device connected to the receiving cyclone for addition of treating agents required for the pulping process.
11. The device as claimed in Claim 4, further comprising a cleaning cyclone for separation of fibers accompanying the steam, connected to the steam outlet tube of the receiving cyclone.
12. The device as claimed in Claim 11, further comprising a feeding device coupled to the cleaning cyclone for returning the separated fibers to the fiber pulp.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7607607A SE7607607L (en) | 1975-07-04 | 1976-06-30 | PROCEDURE FOR REDUCING THE WATER SOLUBILITY OF POLYVINYL ALCOHOL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063406A true CA1063406A (en) | 1979-10-02 |
Family
ID=20328373
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA281,626A Expired CA1063406A (en) | 1976-06-30 | 1977-06-29 | Method and apparatus for producing fiber pulp in a steam-pressurized grinding apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1063406A (en) |
-
1977
- 1977-06-29 CA CA281,626A patent/CA1063406A/en not_active Expired
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