CA1059810A - Procedure and apparatus for preparing hot groundwood - Google Patents
Procedure and apparatus for preparing hot groundwoodInfo
- Publication number
- CA1059810A CA1059810A CA271,643A CA271643A CA1059810A CA 1059810 A CA1059810 A CA 1059810A CA 271643 A CA271643 A CA 271643A CA 1059810 A CA1059810 A CA 1059810A
- Authority
- CA
- Canada
- Prior art keywords
- grinder
- stage
- groundwood
- steam
- hot
- 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.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims description 24
- 238000010025 steaming Methods 0.000 claims abstract description 18
- 238000010276 construction Methods 0.000 claims abstract description 16
- 239000002023 wood Substances 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 238000004064 recycling Methods 0.000 claims description 2
- 229920001131 Pulp (paper) Polymers 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 230000004224 protection Effects 0.000 description 2
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 1
- 241000018646 Pinus brutia Species 0.000 description 1
- 235000011613 Pinus brutia Nutrition 0.000 description 1
- 241000183024 Populus tremula Species 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 241000894007 species Species 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Disintegrating Or Milling (AREA)
- Debarking, Splitting, And Disintegration Of Timber (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for preparing hot groundwood from wood chips, wherein a chip stream is conducted into a pressurized steaming chamber, where the chips reside for a new minutes and are heated to a temperature higher than 100°C, and are passed from the steaming chamber through a sluice feeder into a hot stage I
grinder of closed construction, the pre-ground groundwook being conducted through a separating cyclone to a stage II grinder, the groundwood produced in the stage II grinder being passed to further treatment steps. The pre-ground groundwood is passed from the steam separating cyclone through a sluice feeder into the stage II grinder. The stage II grinding is carried out in a hot grinder of closed construction.
A process for preparing hot groundwood from wood chips, wherein a chip stream is conducted into a pressurized steaming chamber, where the chips reside for a new minutes and are heated to a temperature higher than 100°C, and are passed from the steaming chamber through a sluice feeder into a hot stage I
grinder of closed construction, the pre-ground groundwook being conducted through a separating cyclone to a stage II grinder, the groundwood produced in the stage II grinder being passed to further treatment steps. The pre-ground groundwood is passed from the steam separating cyclone through a sluice feeder into the stage II grinder. The stage II grinding is carried out in a hot grinder of closed construction.
Description
~0598~
The present invention relates to a process for prepar-ing hot groundwood from wood chips, wherein a chip stream is passed into a pressurized steaming chamber, where the chips res-ide fora few minutes and are heated to a temperature higher than lQ0C, and are passed from the steaming chamber through a sluice ~, .~
feeder into a hot grinder of closed construction, i.e., stage I
grinder, the pre-ground groundwood so obtained is then conducted through a separating cyclone into a stage II grinder and the groundwood produced there is passed to further treatment steps.
~` 10 In particular the present invention relates to such a process in which the pre-ground groundwood is passed from the steam separ- ~`
~` ating cyclone through a sluice feeder into the stage II grinder r and the stage II grinding is carried out in a hot grinder of ;~
closed construction.
Hot groundwood is made from wood chips by a continuous ,, ~
process in which the chips are first passed into a steaming ~ ¦
chamber, where they are heated to a temperature higher than 100C, preferably a temperature between 120 and 135C. From the steaming chamber the chips stream is conducted through a sluicei feeder into a hot grinder, at which stage the dry solids content of the chips is about 20 to 30%. The hot groundwood obtained from the grinder is passed into a steam separating cyclone and thereafter usually further into a second grinder, which consists of a grinder of the ~- open type operating under atmospheric pressure and at ambient temperature.
., , . .
A hot groundwood process of this type has a number of j advantages. The heating of the chips prior to grinding promotes j the detachment of the fibres so that the energy required in the , grinding process is reduced. Due to the heating of the chips even ~-wood species can be processed, such as pine and aspen, which can~
not otherwise possibly be ground. Deciduous wood produced in short r rotation cultivation may also be used as raw material. The ' l ;
,, , , . ~ . . , ............................................. _ :, , , , ~ ,- ., ~
~L~5~
saving in grinding energy is about 20 to 30%. The strength characteristics of the groundwood are improved. The procedure is favourable in view of environment protection since the use of water is minimal. The process is a so-called semi-dry method.
The conventional hot groundwood processes however still have drawbacks. It is true that the energy requirements are less than in earlier grinder methods, but they are still higher, so far, than in the normal grinding method ~or instance. Part of the energy is dissipa-ted with the steam. It is also a drawback that wood slivers remain in the groundwood. If attempts are made to increase the degree of grinding, the proportion of the long fibre fraction decreases substantially.
According to the present invention there is provided a process for preparing hot groundwood from wood chips, wherein a stream of said chips is passed into a pressurized steaming chamber in which chamber the chips are heated to a temperature higher than 100C over a period of a few minutes, from the steaming chamber the chips are passed through a sluice feeder into a hot stage I grinder of closed construction where said chips are pre-ground into groundwood, the pre-ground groundwood ~ ~
is conducted from said grinder through a separating cyclone into ~ `
a stage II grinder where said pre-ground groundwood is further ground to form said hot groundwood and the groundwood produced in said stage II grinder is passed to further treatment steps, the improvement in which the pre-ground groundwood is conducted from the steam separating cyclone through a sluice feeder into the stage II grinder and the stage II grinder is a hot grinder of closed construction.
The present invention provides a process for preparing hot groundwood from wood chips in which the chip stream is con-ducted into a pressurized steaming chamber, where the chips dweil -a few minutes and are heated to a temperature higher than 100C,
The present invention relates to a process for prepar-ing hot groundwood from wood chips, wherein a chip stream is passed into a pressurized steaming chamber, where the chips res-ide fora few minutes and are heated to a temperature higher than lQ0C, and are passed from the steaming chamber through a sluice ~, .~
feeder into a hot grinder of closed construction, i.e., stage I
grinder, the pre-ground groundwood so obtained is then conducted through a separating cyclone into a stage II grinder and the groundwood produced there is passed to further treatment steps.
~` 10 In particular the present invention relates to such a process in which the pre-ground groundwood is passed from the steam separ- ~`
~` ating cyclone through a sluice feeder into the stage II grinder r and the stage II grinding is carried out in a hot grinder of ;~
closed construction.
Hot groundwood is made from wood chips by a continuous ,, ~
process in which the chips are first passed into a steaming ~ ¦
chamber, where they are heated to a temperature higher than 100C, preferably a temperature between 120 and 135C. From the steaming chamber the chips stream is conducted through a sluicei feeder into a hot grinder, at which stage the dry solids content of the chips is about 20 to 30%. The hot groundwood obtained from the grinder is passed into a steam separating cyclone and thereafter usually further into a second grinder, which consists of a grinder of the ~- open type operating under atmospheric pressure and at ambient temperature.
., , . .
A hot groundwood process of this type has a number of j advantages. The heating of the chips prior to grinding promotes j the detachment of the fibres so that the energy required in the , grinding process is reduced. Due to the heating of the chips even ~-wood species can be processed, such as pine and aspen, which can~
not otherwise possibly be ground. Deciduous wood produced in short r rotation cultivation may also be used as raw material. The ' l ;
,, , , . ~ . . , ............................................. _ :, , , , ~ ,- ., ~
~L~5~
saving in grinding energy is about 20 to 30%. The strength characteristics of the groundwood are improved. The procedure is favourable in view of environment protection since the use of water is minimal. The process is a so-called semi-dry method.
The conventional hot groundwood processes however still have drawbacks. It is true that the energy requirements are less than in earlier grinder methods, but they are still higher, so far, than in the normal grinding method ~or instance. Part of the energy is dissipa-ted with the steam. It is also a drawback that wood slivers remain in the groundwood. If attempts are made to increase the degree of grinding, the proportion of the long fibre fraction decreases substantially.
According to the present invention there is provided a process for preparing hot groundwood from wood chips, wherein a stream of said chips is passed into a pressurized steaming chamber in which chamber the chips are heated to a temperature higher than 100C over a period of a few minutes, from the steaming chamber the chips are passed through a sluice feeder into a hot stage I grinder of closed construction where said chips are pre-ground into groundwood, the pre-ground groundwood ~ ~
is conducted from said grinder through a separating cyclone into ~ `
a stage II grinder where said pre-ground groundwood is further ground to form said hot groundwood and the groundwood produced in said stage II grinder is passed to further treatment steps, the improvement in which the pre-ground groundwood is conducted from the steam separating cyclone through a sluice feeder into the stage II grinder and the stage II grinder is a hot grinder of closed construction.
The present invention provides a process for preparing hot groundwood from wood chips in which the chip stream is con-ducted into a pressurized steaming chamber, where the chips dweil -a few minutes and are heated to a temperature higher than 100C,
- 2 - .
~: : ' r ~L~5g~
and from the steamin~J chamber through a sluice feeder int~ a ~ot grinder of closed construction, i.e., the stage I grinder, whence the pre-ground groundwood is passed through a steam separating cyclone into a stage Il grinder, the groundwood obtained therefrom being carried towards furt:her treatment steps. The process of the invention-is characterized in that the pre-ground groundwood is conducted fro~i the steam separating cyclone through a sluice feeder into the stage II grinder and that the stage II grinding is carr-ied out in a hot grinder of closed construction.
. ~ . .
In the process of the invention the energy requirement of the stage II grinding is reduced because the grinding takes place under hot condition and the wood splinters therefore are softer. Since the stage II grinding is effected in a hot grinder, ~j the quality of the resulting groundwood is improved. For instance, ,. `) ~ .
' the long fibre fraction is retained because the grinding is not -1 violent.
In an advantageous embodiment of the process of the invention the steam generated by the stage II grinder is conducted into a steam separating cyclone. It is thus understood that all ~ 20 the excess steam both from the stage I grinder and from the stage :- II grinder ls collected at one point, whence the energy contained in the steam can be withdrawn for use in controlled manner at other consumption points, such as the prewashing of the wood chips. ~ ~
i~ ~ favourable energy efficiency is thus attained. Energy is only ~ ;~
introduced into the process as rotational energy for the grlnders, ,:~3 and is removed from the process in the form of steam energy only.
`;1 Thus, the energy introduced into the process is also used, in -, addition to the grinding, for chip washiny, chip heating and the transporting of chips or groundwood in the process. The trans- ~
3n port is by means of pressure through pipelines. No separate ~ ~ -. . ,, , ~:
; screw conveyors or equivalent are needed. Recovery of solid residues from the steam of the steam separating cyclone is .. . ~
~ 3 : .
., .
~0598~) ?ossible, and thereEore the process also meets high re~uirementS
as regards environment pro-tection.
In another advantageous embodiment of the invention part of the groundwood produced by the stage II grinder is passed ,~
back to the steam separating cyclone. From here the groundwood passes once more into the stage II grinder. In this manner the stage II grinder will always operate under full load. No equival-ent recycling is applied in the stage I grinding because the ~-material would be highly unhomogeneous and because it is possible to dimension the stage I grinder for the process in such manner - that it will always operate under optimum load.
- L
~: The invention also provides an apparatus for carrying r -out the methodj comprising a steaming chamber, a sluice feeder, ~
a hot grinder of closed construction, i.e., a stage I grinder, a steam separating cyclone, and a st~ge II grinder and means for passing a chip stream consecutively therethrough for being ground into groundwood. In the apparatus between the steam separating ~;
cyclone and the stage II grinder there is a sluice feeder, and the stage II grinder is a hot grinder of closed construction.
The present invention will be further illustrated by 1' -, ~
way of the accompanying drawing, wherein~
Fig. 1 is a diagrammatic illustration of an apparatus for use in the groundwood preparing process according to one '-~ embodiment of the present invention; and ;~j Fig. 2 is a block diagram illustrating the process of Fig. 1.
In Fig. 1, prewashed wood chips are supplied in a L:
continuous stream through the pipeline 1 into the sluice feeder 2 and thence into the steaming chamber 3. In this chamber 3 a pressure about 2 kg/cm2 gauge prevails, the temperature being between 120 and 135C. The dry solids content of the chips is about 20~. From the steaming chamber 3 the chip stream is i :~
' _ 4 _ ,,, , ~L0598gL!iD
; conducted through the sluice feeder 4 via the duct 5 into the - hot grinder 6 of closed construction, which is the stage I
grinder. The grinder generates steam, the main portion thereof . : -; discharging in the direction against the chip stream into the - duct 5. A portion of the steam passes through the sluice feeder 4 via the conduit 7 into the steaming chamber 3. The quality ~ -of steam arriving in the chamber 3 is regulated so that the "~
-` chips attain the required temperature within 2 to 4 minutes, ., -~ ~.. . .
~i which is the time which the chips stay in the steaming chamber 3. - "
Part of the steam entering the duct 5 is conducted back to the grinder 6 and to the outer periphery thereof, through the conduit ~`
8. In the duct S and on the outer periphery of the grinder 6 ,1 ` pressure transmitters are provided, which give information to the ; ~
pressure controller 9, which in its turn controls the quantity ~ -, of steam flowing in the line 8. Part of the steam generated by ~ `
, the stage I grinder 6 escapes by the pipeline 10 along with the ~ ~`
groundwood to the steam separating cyclone 11. Hence, the steam F~
escapes into the pipeline 12, and the groundwood settles Form the lower end of the steam separating cyclone 11 o~ ~ the groundwood passes through the sluice feeder 13 via the duct 14 to the hot grinder 15 of closed design, which is the stage II h~
: 1 IL~
, grinder. The stage II grinder 15 with its associated apparatus `', is identical in operation with the stage I grinder 6. It has as additionaL equipment the pipeline 16, which starts on the outer periphery of the stage II grinder 15 and terminates at the steam ~, separating cyclone 11 and which conducts off any excess steam.
~`~ Thus the excess steam is all collected in the steam separating : ~ . .
~i cyclone 11. The hot groundwood leaves the stage II grinder lS, pushed by steam pressure, through the pipeline 17, towards further . ., _ treatment steps. This line 17 has branch line 18 connected thereto through which part of the hot groundwood is recycled to the steam ' .:
. .. .
:, _ 5 _ ^
,:
~L05gl!~
separating cyclone ll, whence the groundwood passes once more through the stage II grinder 15. As a result, the stage II
grinder is continuously opera-ting under full load.
In Fig. 2, the process has been shown in the form of a block diagram. As in Fig. l, the steaming chamber 3, the stage I grinder 6, the steam separating cyclone ll and the stage II
grinder 15. Furthermore a condensate separator 19 is present, the condensate accruing therefrom being used in the washer 20 to ;` wash the wood chips. The chip flow and the groundwood flow are -lO represented with double lines, the steam flow with single lines, and the energy flow required for rotation of the grinders 6 and 15 with dashed lines. The design and construction of the r-various pieces of equipment, such as the sluice feeders and the grinders may be varied as desired. ~;
.'~'' ~
~ !
~'1 ' .
. '` . ~
t ~:
:, . ' ~,: :
~ ~
~.!, ' '' : '- ' ~.. ' ~
f~:
.... .
~ 30 .
.' ~ ' .~, . . .
'',;~ ~ ' ,,,, . ~ :
~: : ' r ~L~5g~
and from the steamin~J chamber through a sluice feeder int~ a ~ot grinder of closed construction, i.e., the stage I grinder, whence the pre-ground groundwood is passed through a steam separating cyclone into a stage Il grinder, the groundwood obtained therefrom being carried towards furt:her treatment steps. The process of the invention-is characterized in that the pre-ground groundwood is conducted fro~i the steam separating cyclone through a sluice feeder into the stage II grinder and that the stage II grinding is carr-ied out in a hot grinder of closed construction.
. ~ . .
In the process of the invention the energy requirement of the stage II grinding is reduced because the grinding takes place under hot condition and the wood splinters therefore are softer. Since the stage II grinding is effected in a hot grinder, ~j the quality of the resulting groundwood is improved. For instance, ,. `) ~ .
' the long fibre fraction is retained because the grinding is not -1 violent.
In an advantageous embodiment of the process of the invention the steam generated by the stage II grinder is conducted into a steam separating cyclone. It is thus understood that all ~ 20 the excess steam both from the stage I grinder and from the stage :- II grinder ls collected at one point, whence the energy contained in the steam can be withdrawn for use in controlled manner at other consumption points, such as the prewashing of the wood chips. ~ ~
i~ ~ favourable energy efficiency is thus attained. Energy is only ~ ;~
introduced into the process as rotational energy for the grlnders, ,:~3 and is removed from the process in the form of steam energy only.
`;1 Thus, the energy introduced into the process is also used, in -, addition to the grinding, for chip washiny, chip heating and the transporting of chips or groundwood in the process. The trans- ~
3n port is by means of pressure through pipelines. No separate ~ ~ -. . ,, , ~:
; screw conveyors or equivalent are needed. Recovery of solid residues from the steam of the steam separating cyclone is .. . ~
~ 3 : .
., .
~0598~) ?ossible, and thereEore the process also meets high re~uirementS
as regards environment pro-tection.
In another advantageous embodiment of the invention part of the groundwood produced by the stage II grinder is passed ,~
back to the steam separating cyclone. From here the groundwood passes once more into the stage II grinder. In this manner the stage II grinder will always operate under full load. No equival-ent recycling is applied in the stage I grinding because the ~-material would be highly unhomogeneous and because it is possible to dimension the stage I grinder for the process in such manner - that it will always operate under optimum load.
- L
~: The invention also provides an apparatus for carrying r -out the methodj comprising a steaming chamber, a sluice feeder, ~
a hot grinder of closed construction, i.e., a stage I grinder, a steam separating cyclone, and a st~ge II grinder and means for passing a chip stream consecutively therethrough for being ground into groundwood. In the apparatus between the steam separating ~;
cyclone and the stage II grinder there is a sluice feeder, and the stage II grinder is a hot grinder of closed construction.
The present invention will be further illustrated by 1' -, ~
way of the accompanying drawing, wherein~
Fig. 1 is a diagrammatic illustration of an apparatus for use in the groundwood preparing process according to one '-~ embodiment of the present invention; and ;~j Fig. 2 is a block diagram illustrating the process of Fig. 1.
In Fig. 1, prewashed wood chips are supplied in a L:
continuous stream through the pipeline 1 into the sluice feeder 2 and thence into the steaming chamber 3. In this chamber 3 a pressure about 2 kg/cm2 gauge prevails, the temperature being between 120 and 135C. The dry solids content of the chips is about 20~. From the steaming chamber 3 the chip stream is i :~
' _ 4 _ ,,, , ~L0598gL!iD
; conducted through the sluice feeder 4 via the duct 5 into the - hot grinder 6 of closed construction, which is the stage I
grinder. The grinder generates steam, the main portion thereof . : -; discharging in the direction against the chip stream into the - duct 5. A portion of the steam passes through the sluice feeder 4 via the conduit 7 into the steaming chamber 3. The quality ~ -of steam arriving in the chamber 3 is regulated so that the "~
-` chips attain the required temperature within 2 to 4 minutes, ., -~ ~.. . .
~i which is the time which the chips stay in the steaming chamber 3. - "
Part of the steam entering the duct 5 is conducted back to the grinder 6 and to the outer periphery thereof, through the conduit ~`
8. In the duct S and on the outer periphery of the grinder 6 ,1 ` pressure transmitters are provided, which give information to the ; ~
pressure controller 9, which in its turn controls the quantity ~ -, of steam flowing in the line 8. Part of the steam generated by ~ `
, the stage I grinder 6 escapes by the pipeline 10 along with the ~ ~`
groundwood to the steam separating cyclone 11. Hence, the steam F~
escapes into the pipeline 12, and the groundwood settles Form the lower end of the steam separating cyclone 11 o~ ~ the groundwood passes through the sluice feeder 13 via the duct 14 to the hot grinder 15 of closed design, which is the stage II h~
: 1 IL~
, grinder. The stage II grinder 15 with its associated apparatus `', is identical in operation with the stage I grinder 6. It has as additionaL equipment the pipeline 16, which starts on the outer periphery of the stage II grinder 15 and terminates at the steam ~, separating cyclone 11 and which conducts off any excess steam.
~`~ Thus the excess steam is all collected in the steam separating : ~ . .
~i cyclone 11. The hot groundwood leaves the stage II grinder lS, pushed by steam pressure, through the pipeline 17, towards further . ., _ treatment steps. This line 17 has branch line 18 connected thereto through which part of the hot groundwood is recycled to the steam ' .:
. .. .
:, _ 5 _ ^
,:
~L05gl!~
separating cyclone ll, whence the groundwood passes once more through the stage II grinder 15. As a result, the stage II
grinder is continuously opera-ting under full load.
In Fig. 2, the process has been shown in the form of a block diagram. As in Fig. l, the steaming chamber 3, the stage I grinder 6, the steam separating cyclone ll and the stage II
grinder 15. Furthermore a condensate separator 19 is present, the condensate accruing therefrom being used in the washer 20 to ;` wash the wood chips. The chip flow and the groundwood flow are -lO represented with double lines, the steam flow with single lines, and the energy flow required for rotation of the grinders 6 and 15 with dashed lines. The design and construction of the r-various pieces of equipment, such as the sluice feeders and the grinders may be varied as desired. ~;
.'~'' ~
~ !
~'1 ' .
. '` . ~
t ~:
:, . ' ~,: :
~ ~
~.!, ' '' : '- ' ~.. ' ~
f~:
.... .
~ 30 .
.' ~ ' .~, . . .
'',;~ ~ ' ,,,, . ~ :
Claims (6)
PROPERTY OR PRIVILGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for preparing hot groundwood from wood chips, wherein a stream of said chips is passed into a pressurized steaming chamber in which chamber the chips are heated to a temp-erature higher than 100°C over a period of a few minutes, from the steaming chamber the chips are passed through a sluice feeder into a hot stage I grinder of closed construction wherein said chips are pre-ground into groundwood, the pre-ground groundwood is con-ducted from said grinder through a steam separating cyclone into a stage II grinder where said preground groundwood is further ground to form said hot groundwood and the groundwood produced in said stage II grinder is passed to further treatment steps, the improvement in which the preground groundwood is conducted from the steam separating cyclone through a sluice feeder into the stage II grinder, the stage II grinder is a hot grinder of closed construction, part of the groundwood produced by the stage II
grinder is passed back to the steam separating cyclone, from where the groundwood passes once more into the stage II grinder and the excess steam both from the stage I grinder and from the stage II
grinder is collected at one point, whence the energy container in the steam can be withdrawn for use in a controlled manner at other consumption points.
grinder is passed back to the steam separating cyclone, from where the groundwood passes once more into the stage II grinder and the excess steam both from the stage I grinder and from the stage II
grinder is collected at one point, whence the energy container in the steam can be withdrawn for use in a controlled manner at other consumption points.
2. A process according to claim 1, in which steam generated by the stage II grinder is passed into the steam separ-ating cyclone.
3. In an apparatus for preparing hot groundwood from wood chips comprising a steaming chamber, a sluice feeder, a hot stage I grinder of closed construction, a steam separating cyc-lone and a stage II grinder and means for passing a chip stream consecutively therethrough the improvement in which a sluice feeder is located between the steam separating cyclone and the stage II grinder and the stage II grinder is a hot grinder of closed construction, recycling means are provided for passing part of the wood pulp produced by that stage II grinder to the steam separating cyclone for which it passes back to the stage II grinder and means are provided for collecting excess steam for the stage I
and stage II grinder at one point for withdrawal for use at other consumption points in a controlled manner.
and stage II grinder at one point for withdrawal for use at other consumption points in a controlled manner.
4. An apparatus according to claim 3, in which the stage II grinder is connected by a steam pipeline to the steam separating cyclone.
5. An apparatus according to claim 3, in which a hot groundwood output line departing from the stage II hot grinder is connected by a branch line to the steam separating cyclone.
6. An apparatus according to claim 3, 4 or 5 in which the input side and output side of the stage II grinder as well of the stage I grinder are connected with each other by an exter-nal steam pipeline to control the pressure difference therebetween.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA271,643A CA1059810A (en) | 1977-02-11 | 1977-02-11 | Procedure and apparatus for preparing hot groundwood |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA271,643A CA1059810A (en) | 1977-02-11 | 1977-02-11 | Procedure and apparatus for preparing hot groundwood |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1059810A true CA1059810A (en) | 1979-08-07 |
Family
ID=4107919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA271,643A Expired CA1059810A (en) | 1977-02-11 | 1977-02-11 | Procedure and apparatus for preparing hot groundwood |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1059810A (en) |
-
1977
- 1977-02-11 CA CA271,643A patent/CA1059810A/en not_active Expired
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