CA1280019C - Method for decreasing the energy consumption during refining of fibre material - Google Patents
Method for decreasing the energy consumption during refining of fibre materialInfo
- Publication number
- CA1280019C CA1280019C CA000529361A CA529361A CA1280019C CA 1280019 C CA1280019 C CA 1280019C CA 000529361 A CA000529361 A CA 000529361A CA 529361 A CA529361 A CA 529361A CA 1280019 C CA1280019 C CA 1280019C
- Authority
- CA
- Canada
- Prior art keywords
- grinding
- fibre material
- steam
- approx
- space
- 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 - Lifetime
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
- D21D1/22—Jordans
Landscapes
- Paper (AREA)
- Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
- Artificial Filaments (AREA)
- Crushing And Pulverization Processes (AREA)
Abstract
Abstract of the Invention The invention relates to refining of fibre material in devices with grinding surfaces moving relatively each other where-by it is possible to drastically decrease the energy consumption through a combination of actions, mainly consisting of decreasing the grinding frequency and increasing the fibre material retention time between the grinding surfaces by making these cylindrical or conical and simultaneously discharge from the grinding space the main part of the steam produced during the refining. As such the invention has great importance for the lowering of the cost during production of pulp, in the first hand of high yield mechanical pulps.
Description
The lnvention relates to refinlng of fibre materlal ln devices with grlnding surfaces moving relatively to each other.
In the first place it is concerned with refining of comminuted fibre material, e.g. chips ~o pulp according to TMP, CTMPj CMP or other methods for production of high yleld pulps, or so-called mechanical pulp. More directly the invention is concerned with a combination o~ steps in order to decrease energy consumption during such refining, since the energy consumption of the present methods is very high. The energy consumption of a single refining stage be of a magnitude of approximately 100 kWh per ton of pulp, and with xefining in two stages can total approximately 2000 kWh per ton of produced pulp. Only a small part o$ this energy quantlty is used for the defibration work as such, while the predominantly greater part is consumed in tran ferring the moisture in the ~ibre material, and any added liquid into steam.
The steam produced in the grinding space occupies a volume which, is not desirable, since the steam at the prevailing pressure in the grlnding space makes the natural passage of the fibre material through the grinding space more d~fficult. The presence of the steam also decreases the retention time of the fibre material in the grinding zone.
According to the present invention there is provided a method of lowering the energy consumption o~ a mixture or suspenslon of fibre material such as molst wood chips in a refiner with inlet and outlet for fibre material in which the material passes through a grinding space between grinding surfaces moving relatively to each other, characterized in a combination of the following steps~
r~3a)()1~3 (a) decreasing the grinding frequency from normally approx. 6,000 - 20,000 Hz down to approx. 300 - 800 Hz by decreasing the number of cutting elements from normally approx.
400 -600 to typically approx. 20 - 30 at maintained normal speed of revolution approx. 1,000 - 1,500 rpm (b) in~reasing the fibre material retention time in the grinding space in order to compensate for the losk grinding pulse number due to the decreased frequency by making the grinding surfaces conical or cylindrical in order to make possible the use of a larger volume in the grinding space without increasing the diameter of the grinding elements and (c) compensating for the lost grinding pulse number due to the decreased grinding frequency by increasing the fibre material retention time in the grinding space hy continuously and radially discharging from the grinding space the steam which i5 libera~ed from the liquid associated with the fibre material during the grinding process.
This invention seeks to lower the energy conversion during pulp refining through a combination of steps which include modlfying the grinding surfaces, and the retention time in the grinder.
Although there are refiners in which both grinding sur-. ~-.
faces are moving in order to obtain a desirable relative movement in the grinding space, the following example will only cover re-finers with a fixed part (which is called the stator) and an adjacent moving part (called the rotor).
The first step of this invention comprises drastically decreasing the grinding frequency by keeping the rotor rpm mainly the same as previously, but drastically decreasing the number of cutting elements on both the rotor and the stator.
In the second step of this invention, partly to compen-sate the lower grinding frequency, the volume of pulp being ground is increased i.e. the retention time between the grinding elements is increased. Since with a disc refiner with only radially direct-ed grinding spaces one is limited with regard to the grinding zone diameter due to the centrifugal forces acting on the fiber material at certain numbers of revolutions, it is possible to increase the grinding zone volume by making the grinding space cylindrical or somewhat conical. In that way the diameter can be kept within reasonable limits while simultaneously increasing the length of the grinding zone.
In the third step of this invention, also in order to partly compensate the lower grinding frequency, with the aim to ;; decrease the energy consumption, as much as possible of the gener-` ated steam in the grinding space is discharged while the steam is still present in the grinding space in order to improve the accessibility of the grinding surfaces on the fibre material and thereby increase the retention time of the fibre material in the 1~3V~3~3 grinding zone as such.
Much research and development work has been done con-cerning the design oE the grinding elements, which in modern machines most commonly are made exchangable since they are exposed to heavy stresses and wear. In Canadian patent 901,857 are shown examples of disc shaped, as well as conical, grinding segments with different patterns as to grooves or bars in order to obtain as effective grinding as possible. Another pattern is shown in United States patent 3,815,834 for a disc refiner, from which is clearly seen that the grooves at the smaller disc diameter are arranged a relatively large distance apart and that the distance ; becomes smaller and smaller further out towards the periphery of the disc. By "grinding frequency" is meant the rotor revolutions ; per second multiplied by the number of grooves at the periphery of the grinding surfaces. Rotor revolutions of 1,500-1,000 revolu-tions per minute can be regarded as normal, which give frequencies in the magnitude of 6,000~20,000 Hz. It has now been found that the energy consumption can be reduced considerably, in favourable cases below the half, if the frequency is lowered to approximately 300-800 Hz, by maintaining the speed of revolution of the rotor and decreasing the rotor and stator number of cutting elements from commonly 400-600 to 20-30.
In order to compensate for this lowered frequency, it is necessary to increase the volume between the grinding elements by building the refiner cylindrical or preferably somewhat conical which also provides a higher pulp retention time. By this means, ,..... .. .
0~3 it is possible to increase the length of the fibre material path through -the refiner, i.e. along the conical surface, to a larger extent than would have been possible in a disc refiner since as mentioned it is not desirable to increase the grinding zone dia-meter too much.
In order to further increase the retention time in the refiner according to the invention generated steam is extracted continuously, and mainly along the hole rotor length. sy this means the steam separation should be carried out as completely as possible, in order to decrease the compressability of the chip-fiber-water-steam mixture, which effectively contributes to the direction of input shear forces to chips and fibres.
To achieve an effective extraction of steam from the grinding zone in refiners has long been a problem within the in-, dustry. An example is however shown in the Canadian patent 1,079,559, where the grinding segments besides leaving grooves are also equipped with openings which lead the steam and entrained fibre material from the grinding space to the back side of the grinding segments proper.
According to the present invention the greater part of the steam produced in the grinding space is led away from the grind-ing zone and is furthermore cleaned from the main part of the entrained fibre material. Thereafter the steam is led away from the refiner separately from the fibre material outlet through one or more steam outlets. The steam quantity is furthermore regulated by keeping a suitable pressure difference between the steam outlet and the fibre material outlet.
.
In the first place it is concerned with refining of comminuted fibre material, e.g. chips ~o pulp according to TMP, CTMPj CMP or other methods for production of high yleld pulps, or so-called mechanical pulp. More directly the invention is concerned with a combination o~ steps in order to decrease energy consumption during such refining, since the energy consumption of the present methods is very high. The energy consumption of a single refining stage be of a magnitude of approximately 100 kWh per ton of pulp, and with xefining in two stages can total approximately 2000 kWh per ton of produced pulp. Only a small part o$ this energy quantlty is used for the defibration work as such, while the predominantly greater part is consumed in tran ferring the moisture in the ~ibre material, and any added liquid into steam.
The steam produced in the grinding space occupies a volume which, is not desirable, since the steam at the prevailing pressure in the grlnding space makes the natural passage of the fibre material through the grinding space more d~fficult. The presence of the steam also decreases the retention time of the fibre material in the grinding zone.
According to the present invention there is provided a method of lowering the energy consumption o~ a mixture or suspenslon of fibre material such as molst wood chips in a refiner with inlet and outlet for fibre material in which the material passes through a grinding space between grinding surfaces moving relatively to each other, characterized in a combination of the following steps~
r~3a)()1~3 (a) decreasing the grinding frequency from normally approx. 6,000 - 20,000 Hz down to approx. 300 - 800 Hz by decreasing the number of cutting elements from normally approx.
400 -600 to typically approx. 20 - 30 at maintained normal speed of revolution approx. 1,000 - 1,500 rpm (b) in~reasing the fibre material retention time in the grinding space in order to compensate for the losk grinding pulse number due to the decreased frequency by making the grinding surfaces conical or cylindrical in order to make possible the use of a larger volume in the grinding space without increasing the diameter of the grinding elements and (c) compensating for the lost grinding pulse number due to the decreased grinding frequency by increasing the fibre material retention time in the grinding space hy continuously and radially discharging from the grinding space the steam which i5 libera~ed from the liquid associated with the fibre material during the grinding process.
This invention seeks to lower the energy conversion during pulp refining through a combination of steps which include modlfying the grinding surfaces, and the retention time in the grinder.
Although there are refiners in which both grinding sur-. ~-.
faces are moving in order to obtain a desirable relative movement in the grinding space, the following example will only cover re-finers with a fixed part (which is called the stator) and an adjacent moving part (called the rotor).
The first step of this invention comprises drastically decreasing the grinding frequency by keeping the rotor rpm mainly the same as previously, but drastically decreasing the number of cutting elements on both the rotor and the stator.
In the second step of this invention, partly to compen-sate the lower grinding frequency, the volume of pulp being ground is increased i.e. the retention time between the grinding elements is increased. Since with a disc refiner with only radially direct-ed grinding spaces one is limited with regard to the grinding zone diameter due to the centrifugal forces acting on the fiber material at certain numbers of revolutions, it is possible to increase the grinding zone volume by making the grinding space cylindrical or somewhat conical. In that way the diameter can be kept within reasonable limits while simultaneously increasing the length of the grinding zone.
In the third step of this invention, also in order to partly compensate the lower grinding frequency, with the aim to ;; decrease the energy consumption, as much as possible of the gener-` ated steam in the grinding space is discharged while the steam is still present in the grinding space in order to improve the accessibility of the grinding surfaces on the fibre material and thereby increase the retention time of the fibre material in the 1~3V~3~3 grinding zone as such.
Much research and development work has been done con-cerning the design oE the grinding elements, which in modern machines most commonly are made exchangable since they are exposed to heavy stresses and wear. In Canadian patent 901,857 are shown examples of disc shaped, as well as conical, grinding segments with different patterns as to grooves or bars in order to obtain as effective grinding as possible. Another pattern is shown in United States patent 3,815,834 for a disc refiner, from which is clearly seen that the grooves at the smaller disc diameter are arranged a relatively large distance apart and that the distance ; becomes smaller and smaller further out towards the periphery of the disc. By "grinding frequency" is meant the rotor revolutions ; per second multiplied by the number of grooves at the periphery of the grinding surfaces. Rotor revolutions of 1,500-1,000 revolu-tions per minute can be regarded as normal, which give frequencies in the magnitude of 6,000~20,000 Hz. It has now been found that the energy consumption can be reduced considerably, in favourable cases below the half, if the frequency is lowered to approximately 300-800 Hz, by maintaining the speed of revolution of the rotor and decreasing the rotor and stator number of cutting elements from commonly 400-600 to 20-30.
In order to compensate for this lowered frequency, it is necessary to increase the volume between the grinding elements by building the refiner cylindrical or preferably somewhat conical which also provides a higher pulp retention time. By this means, ,..... .. .
0~3 it is possible to increase the length of the fibre material path through -the refiner, i.e. along the conical surface, to a larger extent than would have been possible in a disc refiner since as mentioned it is not desirable to increase the grinding zone dia-meter too much.
In order to further increase the retention time in the refiner according to the invention generated steam is extracted continuously, and mainly along the hole rotor length. sy this means the steam separation should be carried out as completely as possible, in order to decrease the compressability of the chip-fiber-water-steam mixture, which effectively contributes to the direction of input shear forces to chips and fibres.
To achieve an effective extraction of steam from the grinding zone in refiners has long been a problem within the in-, dustry. An example is however shown in the Canadian patent 1,079,559, where the grinding segments besides leaving grooves are also equipped with openings which lead the steam and entrained fibre material from the grinding space to the back side of the grinding segments proper.
According to the present invention the greater part of the steam produced in the grinding space is led away from the grind-ing zone and is furthermore cleaned from the main part of the entrained fibre material. Thereafter the steam is led away from the refiner separately from the fibre material outlet through one or more steam outlets. The steam quantity is furthermore regulated by keeping a suitable pressure difference between the steam outlet and the fibre material outlet.
.
Claims (2)
1. A method of lowering the energy consumption of a mixture or suspension of fibre material such as moist wood chips in a refiner with inlet and outlet for fibre material in which the material passes through a grinding space between grinding surfaces moving relatively each other, characterized in a combination of the following steps:
(a) decreasing the grinding frequency from normally approx.
6,000 - 20,000 Hz down to approx. 300 - 800 Hz by decreasing the number of cutting elements from normally approx. 400 - 600 to typically approx. 20 - 30 at maintained normal speed of revolution approx. 1,000 - 1,500 rpm (b) increasing the fibre material retention time in the grinding space in order to compensate for the lost grinding pulse number due to the decreased frequency by making the grinding sur-faces conical or cylindrical in order to make possible the use of a larger volume in the grinding space without increasing the diameter of the grinding elements and (c) compensating for the lost grinding pulse number due to the decreased grinding frequency by increasing the fibre material retention time in the grinding space by continuously and radially discharging from the grinding space the steam which is liberated from the liquid associated with the fibre material during the grinding process.
(a) decreasing the grinding frequency from normally approx.
6,000 - 20,000 Hz down to approx. 300 - 800 Hz by decreasing the number of cutting elements from normally approx. 400 - 600 to typically approx. 20 - 30 at maintained normal speed of revolution approx. 1,000 - 1,500 rpm (b) increasing the fibre material retention time in the grinding space in order to compensate for the lost grinding pulse number due to the decreased frequency by making the grinding sur-faces conical or cylindrical in order to make possible the use of a larger volume in the grinding space without increasing the diameter of the grinding elements and (c) compensating for the lost grinding pulse number due to the decreased grinding frequency by increasing the fibre material retention time in the grinding space by continuously and radially discharging from the grinding space the steam which is liberated from the liquid associated with the fibre material during the grinding process.
2. A method according to claim 1 characterized in that the discharge steam from the grinding space is separated within the refiner substantially from fibre material entrained in the steam, and the steam is led away from the refiner through at least one steam outlet separate from the fibre material outlet; and that the steam quantity which is discharged from the refiner is regulated by keeping a suitable pressure difference between the steam outlet and the fibre material outlet.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE86.00582-4 | 1986-02-11 | ||
| SE8600582A SE463821B (en) | 1986-02-11 | 1986-02-11 | PROCEDURE TO REDUCE ENERGY CONSUMPTION BY REFINING A MIXTURE OR SUSPENSION OF FIBER MATERIAL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1280019C true CA1280019C (en) | 1991-02-12 |
Family
ID=20363417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000529361A Expired - Lifetime CA1280019C (en) | 1986-02-11 | 1987-02-10 | Method for decreasing the energy consumption during refining of fibre material |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS62191590A (en) |
| AT (2) | AT389902B (en) |
| BR (1) | BR8700553A (en) |
| CA (1) | CA1280019C (en) |
| DE (1) | DE3701315A1 (en) |
| FI (1) | FI89514C (en) |
| FR (1) | FR2594151B1 (en) |
| NO (1) | NO170163C (en) |
| SE (1) | SE463821B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19543310C2 (en) * | 1995-11-21 | 2000-03-23 | Herzog Stefan | Process for the preparation of an organic thickening and suspension aid |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA901857A (en) * | 1972-06-06 | Pilao Acos E Refinadores Limitada | Method for producing and recovering conic refiners for wood pulps in the paper industry | |
| SE362671B (en) * | 1972-05-09 | 1973-12-17 | Sca Project Ab | |
| CA1070536A (en) * | 1977-06-08 | 1980-01-29 | John B. Matthew | High temperature low consistency refining of thermo-mechanical pulp |
| SE418309B (en) * | 1977-09-30 | 1981-05-18 | Sca Development Ab | SET AND DEVICE FOR REFINING FIBER MATERIAL IN A DISC REFINER |
| SE420226B (en) * | 1980-02-27 | 1981-09-21 | Sunds Defibrator | SET AND DEVICE FOR SEPARATION OF CELLULOSAMATER MATERIALS TREATED IN A REFINER |
| GB2083375A (en) * | 1980-09-08 | 1982-03-24 | Cell Dev Inc | Disc mills |
| SE427759B (en) * | 1981-10-16 | 1983-05-02 | Sca Development Ab | WANT TO REDUCE ENERGY CONSUMPTION, POSSIBLE HIGH ROTATION SPEEDS AND IMPROVE MASS QUALITY BY MECHANICAL PROCESSING OF CELLULOSIC MATERIAL IN MALA APPLIANCES AND DEVICE IMPLEMENTATION DEVICE |
-
1986
- 1986-02-11 SE SE8600582A patent/SE463821B/en not_active IP Right Cessation
-
1987
- 1987-01-17 DE DE19873701315 patent/DE3701315A1/en active Granted
- 1987-01-20 AT AT0009987A patent/AT389902B/en not_active IP Right Cessation
- 1987-01-21 NO NO870248A patent/NO170163C/en unknown
- 1987-01-28 FI FI870363A patent/FI89514C/en not_active IP Right Cessation
- 1987-01-29 FR FR8701077A patent/FR2594151B1/en not_active Expired - Fee Related
- 1987-02-06 BR BR8700553A patent/BR8700553A/en not_active IP Right Cessation
- 1987-02-10 CA CA000529361A patent/CA1280019C/en not_active Expired - Lifetime
- 1987-02-10 JP JP2745087A patent/JPS62191590A/en active Pending
-
1989
- 1989-07-16 AT AT752/89A patent/AT391154B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| BR8700553A (en) | 1987-12-08 |
| AT391154B (en) | 1990-08-27 |
| JPS62191590A (en) | 1987-08-21 |
| FI870363A (en) | 1987-08-12 |
| FR2594151A1 (en) | 1987-08-14 |
| NO170163B (en) | 1992-06-09 |
| FR2594151B1 (en) | 1992-10-09 |
| FI870363A0 (en) | 1987-01-28 |
| SE463821B (en) | 1991-01-28 |
| NO870248D0 (en) | 1987-01-21 |
| DE3701315A1 (en) | 1987-08-13 |
| NO170163C (en) | 1994-12-08 |
| SE8600582L (en) | 1987-08-12 |
| ATA9987A (en) | 1989-07-15 |
| SE8600582D0 (en) | 1986-02-11 |
| FI89514C (en) | 1993-10-11 |
| NO870248L (en) | 1987-08-12 |
| ATA75289A (en) | 1990-02-15 |
| AT389902B (en) | 1990-02-26 |
| FI89514B (en) | 1993-06-30 |
| DE3701315C2 (en) | 1989-07-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |