EP2655731B1 - A method of controlling a pulping process in a feed-forward manner - Google Patents
A method of controlling a pulping process in a feed-forward manner Download PDFInfo
- Publication number
- EP2655731B1 EP2655731B1 EP11851854.7A EP11851854A EP2655731B1 EP 2655731 B1 EP2655731 B1 EP 2655731B1 EP 11851854 A EP11851854 A EP 11851854A EP 2655731 B1 EP2655731 B1 EP 2655731B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- digester
- controlling
- mass flow
- wood
- pulping process
- 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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Links
- 238000000034 method Methods 0.000 title claims description 59
- 230000008569 process Effects 0.000 title claims description 39
- 238000004537 pulping Methods 0.000 title claims description 31
- 239000002023 wood Substances 0.000 claims description 52
- 238000005470 impregnation Methods 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 239000000126 substance Substances 0.000 claims description 14
- 238000010411 cooking Methods 0.000 claims description 13
- 239000002994 raw material Substances 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000003513 alkali Substances 0.000 description 10
- 230000001276 controlling effect Effects 0.000 description 9
- 230000008901 benefit Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002655 kraft paper Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004886 process control Methods 0.000 description 2
- 239000011122 softwood Substances 0.000 description 2
- 102100030386 Granzyme A Human genes 0.000 description 1
- 101001009599 Homo sapiens Granzyme A Proteins 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C1/00—Pretreatment of the finely-divided materials before digesting
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/228—Automation of the pulping processes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C7/00—Digesters
- D21C7/12—Devices for regulating or controlling
Definitions
- the invention refers to a method of controlling a pulping process wherein wood chips are conveyed to an impregnation vessel or to a digester where said wood chips are treated with a liquor comprising chemicals.
- wood chips are treated with chemicals in a digester at enhanced pressure and temperature to dissolve the lignin that binds fibres together.
- the predominating pulping process today is the Kraft process, wherein wood chips are treated with a mixture of sodium hydroxide and sodium sulphide, known as white liquor.
- the pulp quality and the consumption of the chemicals used in the pulping process are highly dependent on the raw material, i.e. the wood chips.
- the moisture content and other properties of the chips may vary due to, e.g., seasonal variations, different chip pile arrangements and the wood species used.
- the variation of the properties of the raw material makes it difficult to set an accurate dosing of chemicals to the digester. Oftentimes more chemicals than required are used, which is detrimental from both an economical and an environmental perspective.
- a system for controlling a continuous digester is further disclosed in CA919289 .
- WO9420671 discloses a method to control a manufacturing process for pulp by measuring the bulk density of the chips supplied to the process.
- US2006278353 discloses a method to monitor the variation in wood species composition by using light-reflection-related and density-related properties as input in a model characterizing a relation between such wood chip properties and species information.
- the invention discloses a method of controlling a pulping process wherein wood chips are conveyed to an impregnation vessel and/or to a digester where said wood chips are treated with a liquor comprising chemicals.
- the method of the invention comprises the steps of;
- the method according to the invention makes it, e.g. possible to control the supply of chemicals, such as sodium hydroxide and sodium sulphide, to the impregnation vessel or to the digester, the liquor to wood ratio and/or the pulping temperature on-line, in a feed-forward manner.
- chemicals such as sodium hydroxide and sodium sulphide
- the method is simple and does not require huge investment costs.
- the invention relates to a method of controlling a pulping process wherein wood chips are treated with chemicals in an impregnation vessel and/or in a digester.
- the term "impregnation vessel” as used herein may be any kind of a vessel, pipe or the like suitable for processing of the wood chips.
- the pulping process may, e.g., be a kraft pulping process, a sulphite pulping process or a chemi-thermo mechanical pulping process.
- the pulping process may be a batch or a continuous pulping process.
- the process may, e.g., be a continuous Kraft pulping process, wherein the wood chips are treated with a mixture of sodium hydroxide and sodium sulphide at elevated temperature and pressure.
- a ratio between the actual mass flow of fresh, moisture wood chips conveyed to the impregnation vessel or to the digester and an estimated mass flow of dry wood chips to the impregnation vessel or the digester needed to achieve a desired, pre-set, pulp production is calculated.
- Said ratio below referred to as Wood Material Indicator (WMI)
- WMI Wood Material Indicator
- the WMI may be calculated in accordance with eq. 1.
- WMI Actual mass flow of moisture chips kg / s Estimated mass flow of dry chips kg / s
- the WMI may be calculated by dividing the estimated mass flow of dry wood chips with the actual mass flow of moisture wood chips.
- the Pulp Production is a targeted, pre-set, value.
- the Pulp Production in the equation above is expressed in bone dry weight [kg/s], i.e. the weight of 100 % dry pulp.
- the cooking yield is an estimated value of the cooking yield for the wood species that are being pulped.
- the estimated cooking yield for kraft pulping of soft wood is, e.g., 46%.
- the mass flow of moisture wood chips conveyed to the impregnation vessel or the digester is measured by use of a chip conveyor scale (preferred), a mass flow scanner (by using X-ray) or a radiating wood flow meter.
- the measured mass flow of moisture wood varies depending on the moisture content of the raw material and on other properties, such as the density, of the raw material.
- the Wood Material Indicator may be used to continuously control the pulping process. This may, e.g., be achieved by regulating the chemical charge to the impregnation vessel or the digester and/or the Liquor to wood ratio and/or the pulping temperature.
- the cooking alkali dose may be continuously regulated based on the WMI value.
- the Liquor to wood ratio may be regulated based on WMI by adjusting the internal circulation of spent cooking liquor or washing liquor in the digester.
- the wood material indicator can be used in combination with frequent analysis of the dry content of the chips conveyed to the digester as reflected by the third aspect of the present invention.
- the estimated dry mass flow is calculated by eq.2.
- the production in a continuous digester system is normally controlled by a volumetric measurement such as a chip feeding screw or a chip meter. Based on the known feeding volume per revolution, filling degree and estimated chip density the chip feeding device will rotate with a certain speed in order to maintain the target production (estimated dry mass flow).
- Wet chip density WCF / V ⁇ FD ⁇ rpm
- Measured dry density wet chip density ⁇ dry content .
- WMI Measured dry density / estimated dry density
- WMI as described by the ratio above may then be used in the process control.
- the estimated dry density is dependent on which raw material is used.
- the method according to the invention is used in a feed forward loop (manner) taking into account what is fed into the system (variation in both dry matter and moisture is combined; in the Nordic conditions where variation in chip bulk density is very low this has worked well).
- the response to changes is further relatively fast.
Description
- The invention refers to a method of controlling a pulping process wherein wood chips are conveyed to an impregnation vessel or to a digester where said wood chips are treated with a liquor comprising chemicals.
- In a chemical pulping process, wood chips are treated with chemicals in a digester at enhanced pressure and temperature to dissolve the lignin that binds fibres together. The predominating pulping process today is the Kraft process, wherein wood chips are treated with a mixture of sodium hydroxide and sodium sulphide, known as white liquor.
- The pulp quality and the consumption of the chemicals used in the pulping process are highly dependent on the raw material, i.e. the wood chips. The moisture content and other properties of the chips may vary due to, e.g., seasonal variations, different chip pile arrangements and the wood species used. The variation of the properties of the raw material makes it difficult to set an accurate dosing of chemicals to the digester. Oftentimes more chemicals than required are used, which is detrimental from both an economical and an environmental perspective.
- A system for controlling a continuous digester is further disclosed in
CA919289 . -
WO9420671 -
US2006278353 discloses a method to monitor the variation in wood species composition by using light-reflection-related and density-related properties as input in a model characterizing a relation between such wood chip properties and species information. - In conventional chemical pulping processes, the process is controlled on the basis of information obtained from measurements of the properties of the pulp or of the residual alkali content in spent cooking liquor, i.e. the process is controlled in a feed-back manner. Such an approach fails to comply with short-term or sudden variations of the properties of the chips. In the art, there are commercial measurement systems available for measuring raw material properties. However, these prior art methods usually involve high investment costs, requires long time for analysis and/or are not accurate enough and are thus not typically used to control the process.
- Thus, there remains a need for a simple, on-line feed forward control of the pulping process.
- It is an object of the invention to provide a simple, on-line method for controlling a pulping process. This, and other advantages, is achieved with the method according to the invention.
- The invention discloses a method of controlling a pulping process wherein wood chips are conveyed to an impregnation vessel and/or to a digester where said wood chips are treated with a liquor comprising chemicals. The method of the invention comprises the steps of;
- a. estimating a mass flow of dry wood chips to the impregnation vessel or the digester needed to achieve a desired pulp production, which estimated mass flow is achieved by dividing the desired pulp production with an estimated cooking yield,
- b. measuring the actual mass flow of moisture wood chips conveyed to the impregnation vessel or the digester, by use of a chip conveyor scale, a mass flow scanner or a radiating wood flow meter,
- c. calculating a ratio between the measured actual mass flow of moisture wood chips and the estimated mass flow of dry wood chips,
- d. controlling the pulping process based on said calculated ratio.
- The method according to the invention makes it, e.g. possible to control the supply of chemicals, such as sodium hydroxide and sodium sulphide, to the impregnation vessel or to the digester, the liquor to wood ratio and/or the pulping temperature on-line, in a feed-forward manner. It has been shown, that by controlling the pulping process in accordance with the invention, the stability of the process is improved and a reduction in the variation of the kappa number and the quality of the pulp is achieved. The method is simple and does not require huge investment costs. Further we are using the estimation in a) to calculate the pre-set process parameters. The ratio is then used for fine tuning the process parameters. Thus you create first a set-point which later is used in the regulation of the process.
- The invention relates to a method of controlling a pulping process wherein wood chips are treated with chemicals in an impregnation vessel and/or in a digester. The term "impregnation vessel" as used herein may be any kind of a vessel, pipe or the like suitable for processing of the wood chips. The pulping process may, e.g., be a kraft pulping process, a sulphite pulping process or a chemi-thermo mechanical pulping process. The pulping process may be a batch or a continuous pulping process. The process may, e.g., be a continuous Kraft pulping process, wherein the wood chips are treated with a mixture of sodium hydroxide and sodium sulphide at elevated temperature and pressure.
- In accordance with the method of the invention, a ratio between the actual mass flow of fresh, moisture wood chips conveyed to the impregnation vessel or to the digester and an estimated mass flow of dry wood chips to the impregnation vessel or the digester needed to achieve a desired, pre-set, pulp production, is calculated. Said ratio, below referred to as Wood Material Indicator (WMI), may, e.g., be used to control the amount of chemicals, such as sodium hydroxide and sodium sulphide, supplied to the impregnation vessel or the digester and/or to control the liquor to wood ratio in the digester and/or to control the pulping temperature. The WMI may be calculated in accordance with eq. 1.
- Alternatively, the WMI may be calculated by dividing the estimated mass flow of dry wood chips with the actual mass flow of moisture wood chips.
-
- The Pulp Production is a targeted, pre-set, value. The Pulp Production in the equation above is expressed in bone dry weight [kg/s], i.e. the weight of 100 % dry pulp. The cooking yield is an estimated value of the cooking yield for the wood species that are being pulped. The estimated cooking yield for kraft pulping of soft wood is, e.g., 46%.
- The mass flow of moisture wood chips conveyed to the impregnation vessel or the digester is measured by use of a chip conveyor scale (preferred), a mass flow scanner (by using X-ray) or a radiating wood flow meter. The measured mass flow of moisture wood varies depending on the moisture content of the raw material and on other properties, such as the density, of the raw material.
- The Wood Material Indicator (WMI) may be used to continuously control the pulping process. This may, e.g., be achieved by regulating the chemical charge to the impregnation vessel or the digester and/or the Liquor to wood ratio and/or the pulping temperature. The cooking alkali dose may be continuously regulated based on the WMI value. The Liquor to wood ratio may be regulated based on WMI by adjusting the internal circulation of spent cooking liquor or washing liquor in the digester.
- When the variation in raw material density is higher the wood material indicator can be used in combination with frequent analysis of the dry content of the chips conveyed to the digester as reflected by the third aspect of the present invention.
- In such a way the possible variation from humidity and raw material density is separated from each other and this will further improve the precision of the process control if the variation in mass flow is dominated by raw material density variation. This is decided case by case on the conditions in the mill and used raw material.
- The estimated dry mass flow is calculated by eq.2. The production in a continuous digester system is normally controlled by a volumetric measurement such as a chip feeding screw or a chip meter. Based on the known feeding volume per revolution, filling degree and estimated chip density the chip feeding device will rotate with a certain speed in order to maintain the target production (estimated dry mass flow). By utilising the measured wet chip flow measured on the chip conveyor to the digester system in combination with an analysed chip dry content and the known volume (given by the rotation speed of the chip metering device) of chips fed to the digester system it is possible to calculate the measured wet chip density:
- Where
- WCF = wet chip mass flow (kg/min)
- V = fed volume per revolution (m3)
- FD = filling degree
- rpm = rotation speed of the chip metering devise (rpm)
-
-
- WMI as described by the ratio above may then be used in the process control. The estimated dry density is dependent on which raw material is used.
- Further the method according to the invention is used in a feed forward loop (manner) taking into account what is fed into the system (variation in both dry matter and moisture is combined; in the Nordic conditions where variation in chip bulk density is very low this has worked well). The response to changes is further relatively fast.
- In the following the invention will be described in more details by way of an example with reference to the drawings.
-
-
Fig. 1 shows a schematic view of the flow of wood raw material from a chip pile to an impregnation vessel or to a digester. Total mass flow is measured preferably by using a chip conveyor scale. The raw material of fresh, moisture wood chips is conveyed on a chip conveyor (1) to a chip silo (2). The material is further conveyed from the chip silo (2) to an impregnation vessel or a digester by use of a chip feed screw (3). The screw rotation of the chip feed screw (3) is controlled based on the calculated estimated dry mass flow, i.e. it depends on the set value of the pulp production. According to one example of the invention, a chip conveyor scale (4), arranged under the chip conveyor (1), measures the actual flow of fresh, moisture chips continuously. Since the mass of chips in the silo is held substantially constant, measuring of the flow on the chip conveyor gives an accurate value of the actual flow of fresh, moisture chips to the impregnation vessel or the digester. The measured fresh flow value is transmitted to a control unit (5) of a control system, (5) shown schematically infig. 3 . The estimated dry wood flow is also entered into the control unit (5). In the control system, a ratio between said flows is calculated (WMI) and used to regulate e.g. the set value for the alkali charge to the impregnation vessel or the digester and the liquid to wood ratio. Preferably, the process is further controlled on the basis of a theoretically calculated flow of wood chips to the impregnation vessel or the digester, i.e. in accordance with the traditional way of controlling a pulping process. Thus, WMI is preferably used to regulate a certain percentage on top of the traditional control of the process. A theoretically calculated set value (set-point) is thus also entered into the system. -
Figure 2 shows an example how the WMI as set out above may be determined. -
Figure 3 shows a control system in accordance with the invention. The control system may comprise one or several sub control systems for regulating the alkali charge, cooking temperature and/or Liquor to wood ratio for long term, e.g. 24 hours, and/or short term, e.g. 2 hours, variations of the WMI. In the control system (5) shown infig. 3 , the regulation is separated into two circuits; one for long term and one for short term variation of WMI. The system (5) may comprise further control units (6, 7) where further variables (v1, v2, ... Vn) or preset values may be entered for controlling the process, such as the upper and lower limits of alkali charge, the current values of the liquor to wood ratio, cooking temperature (H-factor) and alkali charge etc. -
Figure 4 shows more schematic how WMI according to the present invention may be used to control alkali dosage, which is only an example of a parameter which may be controlled by using the WMI according to the present invention. -
Figure 5 shows the WMI control in action (c.f. the example below). - A trial run was performed at the Oulu mill during 4 days where it was shown that WMI control reduces kappa variation. WMI as a soft sensor appears to be usable and accurate enough to reduce the effects of raw material variations. The results are given below in Table 1.
Table 1. Results from the 4-day Oulu trial. Each case is a period of 4d running. The raw material was softwood of Scandinavian origin (t/d=tonnes/day). See also figure 5 which reflects the example. C.f. also figure 2. No WMI control With WMI control Measurement Unit Average Deviati on Maxim um Minim um Average Deviati on Maxim um Minim um Alkali to wood ratio % 19.1 0.10 19.2 19.0 19.0 0.05 19.2 18.8 Residual alkali extraction [g/l] (average 2h) g/l 6.1 0.27 6.8 5.4 5.8 0.21 6.6 5.2 WMI value as % of DC in wood (average 2h) % 47.7 0.47 48.7 46.9 48.0 0.41 49.0 47.3 On-line blow kappa value from analyzer 27.1 1.27 31.5 24.4 26.7 0.74 28.8 25.0 Cooking temperature °C 167.6 0.53 168.6 166.0 169.0 0.72 171.0 167.0 Cookinq production t/d 1123 6.98 1127 1099 1150 0.16 1150 1149 - The benefits are given below in Table 2.
Table 2. The benefits from the 4-day Oulu trial. Benefits of using wood material indicator (WMI) control Change in residual alkali variation (black liquor extraction) -22.1 % Change in kappa variation (after digester blow) - 41.7 % - Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations, which would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains. Thus the invention is therefore intended to cover various modifications and equivalent methods included within the spirit and scope of the appended claims.
- Any illustration and description in the drawings and in the foregoing description are to be considered exemplary and not restrictive.
- Use of the word "comprising" in the claims does not exclude other elements or steps, and use of the article "a" or "an" does not exclude a plurality. Occurrence of features in different dependent claims does not per se exclude a combination of these features. Any reference signs in the claims are for increasing intelligibility and shall not be construed as limiting the scope of the claims.
Claims (4)
- A method of controlling a pulping process wherein wood chips are conveyed to an impregnation vessel and/or to a digester where said wood chips are treated with a liquor comprising chemicals, which method comprises the steps of;a. estimating a mass flow of dry wood chips to the impregnation vessel or to the digester needed to achieve a desired pulp production, which estimated mass flow is achieved by dividing the desired pulp production with an estimated cooking yield,b. measuring the actual mass flow of moisture wood chips conveyed to the impregnation vessel or to the digester by use of a chip conveyor scale, a mass flow scanner or a radiating wood flow meter,c. calculating a ratio between the actual mass flow of moisture wood chips and the estimated mass flow of dry wood chips,d. controlling the pulping process based on said calculated ratio.
- A method according to claim 1, wherein the step (d) of controlling the pulping process comprises controlling the chemicals supplied to the impregnation vessel and/or to the digester based on said calculated ratio.
- A method according to any one of claims 1 - 2, wherein the step (d) of controlling the pulping process comprises controlling the liquor to wood ratio in the digester based on said calculated ratio.
- A method according to anyone of claims 1 - 3, wherein the step (d) of controlling the pulping process comprises controlling the pulping temperature based on said calculated ratio.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE1051361 | 2010-12-22 | ||
PCT/SE2011/051534 WO2012087228A1 (en) | 2010-12-22 | 2011-12-16 | A method of controlling a pulping process in a feed-forward manner |
Publications (3)
Publication Number | Publication Date |
---|---|
EP2655731A1 EP2655731A1 (en) | 2013-10-30 |
EP2655731A4 EP2655731A4 (en) | 2017-05-17 |
EP2655731B1 true EP2655731B1 (en) | 2019-05-08 |
Family
ID=46314243
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP11851854.7A Active EP2655731B1 (en) | 2010-12-22 | 2011-12-16 | A method of controlling a pulping process in a feed-forward manner |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP2655731B1 (en) |
CN (1) | CN103270214B (en) |
BR (1) | BR112013015837A2 (en) |
ES (1) | ES2730759T3 (en) |
PT (1) | PT2655731T (en) |
UY (1) | UY33828A (en) |
WO (1) | WO2012087228A1 (en) |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA919289A (en) * | 1970-06-30 | 1973-01-16 | Westinghouse Electric Corporation | System for controlling the feed end of a continuous papermaking digester |
US4239590A (en) * | 1979-01-11 | 1980-12-16 | Kamyr, Inc. | Method of maintaining uniformity of fibrous material fed to a continuous digester |
US5266159A (en) * | 1991-10-25 | 1993-11-30 | Kamyr, Inc. | Mass flow measurement, preferably for controlling chip feed to a digester |
SE500994C2 (en) * | 1993-03-02 | 1994-10-17 | Iggesund Tools Ab | Method for controlling a defibration process by measuring the bulk density of the added chip |
CN1179188A (en) * | 1995-03-23 | 1998-04-15 | 西门子公司 | Method and device for process control in cellulose and/or paper manufacture |
SE517297C2 (en) * | 1999-09-10 | 2002-05-21 | Stora Kopparbergs Bergslags Ab | Method for producing mechanical pulp from a cellulose-containing material, pulp made according to the method and carton produced from the pulp |
US6447639B1 (en) * | 2001-03-05 | 2002-09-10 | Sita Ruby Warren | Process for controlling a digester using real time measurement of moisture content and species of wood |
WO2004016850A1 (en) * | 2002-08-16 | 2004-02-26 | Amec E & C Services Limited | On-line pulp digester control system |
SE525872C2 (en) * | 2002-09-06 | 2005-05-17 | Stora Enso Ab | Method of producing mechanical pulp with reduced energy consumption |
FI123011B (en) * | 2005-01-05 | 2012-09-28 | Metso Paper Inc | Method for regulating a cellulose cooking process |
US20060278353A1 (en) * | 2005-06-03 | 2006-12-14 | Centre De Recherche Industrielle Du Quebec | Method and apparatus for estimating relative proportion of wood chips species to be fed to a process for producing pulp |
-
2011
- 2011-12-16 WO PCT/SE2011/051534 patent/WO2012087228A1/en unknown
- 2011-12-16 ES ES11851854T patent/ES2730759T3/en active Active
- 2011-12-16 PT PT11851854T patent/PT2655731T/en unknown
- 2011-12-16 BR BR112013015837A patent/BR112013015837A2/en not_active Application Discontinuation
- 2011-12-16 CN CN201180061867.2A patent/CN103270214B/en active Active
- 2011-12-16 EP EP11851854.7A patent/EP2655731B1/en active Active
- 2011-12-21 UY UY0001033828A patent/UY33828A/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
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None * |
Also Published As
Publication number | Publication date |
---|---|
EP2655731A4 (en) | 2017-05-17 |
BR112013015837A2 (en) | 2018-05-15 |
CN103270214B (en) | 2016-11-16 |
PT2655731T (en) | 2019-06-26 |
ES2730759T3 (en) | 2019-11-12 |
CN103270214A (en) | 2013-08-28 |
UY33828A (en) | 2012-06-29 |
EP2655731A1 (en) | 2013-10-30 |
WO2012087228A1 (en) | 2012-06-28 |
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