EP4146861A1 - A system and method for defibrating wood chips, and a return steam pipe - Google Patents

A system and method for defibrating wood chips, and a return steam pipe

Info

Publication number
EP4146861A1
EP4146861A1 EP21800699.7A EP21800699A EP4146861A1 EP 4146861 A1 EP4146861 A1 EP 4146861A1 EP 21800699 A EP21800699 A EP 21800699A EP 4146861 A1 EP4146861 A1 EP 4146861A1
Authority
EP
European Patent Office
Prior art keywords
steam pipe
return steam
preheater
arrangement
defibrator
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.)
Pending
Application number
EP21800699.7A
Other languages
German (de)
French (fr)
Other versions
EP4146861A4 (en
Inventor
Thommy LINDBLOM
Örjan AHLGREN
Jan Laredius
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet Technologies Oy
Valmet AB
Original Assignee
Valmet Oy
Valmet AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Valmet Oy, Valmet AB filed Critical Valmet Oy
Publication of EP4146861A1 publication Critical patent/EP4146861A1/en
Publication of EP4146861A4 publication Critical patent/EP4146861A4/en
Pending legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
    • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
    • D21B1/14—Disintegrating in mills
    • 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
    • D21D1/30—Disc mills

Definitions

  • the present invention relates to a defibrator system and to a return steam pipe arrangement in a defibrator system and to a method for defibrating wood chips.
  • a defibrator system comprises a preheater for preheating wood chips before they are defibrated in a defibrator.
  • the preheated wood chips are transferred out from the preheater by for example a plug feed screw into another feed screw which is a ribbon feed screw which transfers the preheated wood chips into the defibrator.
  • the ribbon feed screw is hollow whereby a return flow of steam is allowed from the defibrator through the ribbon feed screw.
  • a return steam pipe is further provided in the defibrator system for balancing the pressure between the ribbon feed screw and the preheater. The return steam pipe will transfer steam from the ribbon feed screw back to the preheater.
  • the return steam pipe is connected in one end to the ribbon feed screw and in the other end to a top part of the preheater.
  • An object of the invention is to provide a more stable and reliable defibration process in the defibrator system.
  • a further object of the invention is to improve the process of returning steam from the defibrator to the preheater. This is achieved by a defibrator system, by a method for defibrating wood chips and by a return steam pipe arrangement according to the independent claims. According to one aspect of the invention a defibrator system for defibrating wood chips is provided.
  • Said defibrator system comprises: a preheater comprising a preheater wood chips inlet and a preheater wood chips outlet; a defibrator comprising a defibrator wood chips inlet and a defibrator wood fibre outlet; a feed screw arrangement which is connected to said preheater wood chips outlet and to said defibrator wood chips inlet and configured for feeding wood chips from the preheater wood chips outlet to the defibrator wood chips inlet; and a return steam pipe arrangement comprising a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is connected in the return steam pipe first end to the feed screw arrangement and in the return steam pipe second end to the preheater, wherein said return steam pipe is configured for transferring steam from the feed screw arrangement to the preheater, wherein the return steam pipe arrangement comprises a first sensor arrangement provided in connection with the return steam pipe at a position which is closer to the return steam
  • a method for defibrating wood chips comprising the steps of: providing wood chips into a preheater through a preheater wood chips inlet; preheating said wood ships in the preheater; feeding said preheated wood chips from a preheater wood chips outlet of the preheater to a defibrator wood chips inlet of a connected defibrator by a feed screw arrangement which is connecting said preheater wood chips outlet with said defibrator wood chips inlet; defibrating said wood chips in said defibrator; and returning steam from the defibrator via the feed screw arrangement to the preheater via a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is connecting the feed screw arrangement and the preheater, wherein the method further comprises the step of measuring a feature in the return steam pipe with a first sensor arrangement at a position which is closer to the return steam
  • a return steam pipe arrangement comprising a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is configured for being connectable in the return steam pipe first end to a feed screw arrangement provided for feeding wood chips between a preheater and a defibrator in a defibrator system and in the return steam pipe second end to the preheater of the defibrator system, wherein said return steam pipe is configured for returning steam from the defibrator and the feed screw arrangement to the preheater and wherein the return steam pipe arrangement comprises a first sensor arrangement provided in connection with the return steam pipe at a position which is closer to the return steam pipe first end than the return steam pipe second end.
  • a defibrator system in which a feature of the steam which is passing the return steam pipe can be measured closer to the connection of the return steam pipe to the feed screw arrangement than to the preheater.
  • This measured feature can be used for evaluating if there is for example a stop or a reduced possibility for the steam to pass through the return steam pipe.
  • a defibration process efficiency can be improved and the process will be more reliable and predictable.
  • a return steam pipe arrangement is provided according to the invention which can be connected to an already existing defibrator system which return steam pipe arrangement provides the possibility to measure a feature of the steam passing the return steam pipe at a position which is closer to the feed screw arrangement than the preheater.
  • the first sensor arrangement is provided in connection with the return steam pipe within a distance from the return steam pipe first end which is less than 1/4 of a total length (L) of the return steam pipe.
  • the defibrator system further comprises a second sensor arrangement which is provided either in connection with the return steam pipe within a distance from the return steam pipe second end which is less than 1/4 of a total length (L) of the return steam pipe or in a top portion of the preheater.
  • the first sensor arrangement is provided in connection with the return steam pipe first end and the second sensor arrangement is provided in connection with the return steam pipe second end.
  • the first and second sensor arrangements comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends.
  • said preheater wood chips inlet is arranged in a top portion of said preheaterand said preheaterwood chips outlet is arranged in a bottom portion of said preheater.
  • said return steam pipe second end is connected to a top portion of the preheater.
  • the feed screw arrangement comprises a ribbon feed screw.
  • the feed screw arrangement comprises a plug feed screw and a ribbon feed screw connected to each other, wherein the plug feed screw is connected to the preheater woodchips outlet and is configured for feeding wood chips into the ribbon feed screw, which is connected to the defibrator wood chips inlet and is configured for transferring the wood chips from the plug feed screw to the defibrator, wherein said ribbon feed screw comprises a hollow centre allowing steam to travel through the ribbon feed screw in the opposite direction to a material feeding direction of the ribbon feed screw.
  • the first and a possible second sensor arrangement can comprise one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor.
  • Figure 1 shows schematically a perspective view, partly in cross section, of a defibrator system according to one embodiment of the invention.
  • Figure 2a is a cross section of the defibrator system as shown in Figure 1.
  • Figure 2b is a cross section of a defibrator system according to another embodiment of the invention.
  • Figure 3 shows schematically a return steam pipe arrangement according to one embodiment of the invention.
  • Figure 4 is a flow chart describing some of the steps of a method for defibrating wood chips according to the invention.
  • Figure 1 shows schematically a perspective view, partly in cross section, of a defibrator system 1 according to one embodiment of the invention.
  • Figure 2a shows schematically a cross section of the same defibrator system 1 as shown in Figure 1.
  • Figure 2b is a cross section of a defibrator system 1' according to another embodiment of the invention.
  • Figure 3 shows schematically a return steam pipe arrangement 21 according to one embodiment of the invention.
  • the defibrator system 1; 1' comprises a preheater 3 comprising a preheater wood chips inlet 5a and a preheater wood chips outlet 5b.
  • the preheater wood chips inlet 5a is arranged in a top portion 6a of said preheater 3 and said preheater wood chips outlet 5b is arranged in a bottom portion 6b of said preheater 3.
  • Wood chips are fed into the preheater 3 via the preheater wood chips inlet 5a for being treated in the preheater before they are transferred out through the preheater wood chips outlet 5b for being defibrated.
  • the defibrator system 1; 1' comprises further a defibrator 7 configured for defibrating the wood chips after they have been treated in the preheater 3.
  • the defibrator 7 comprises a defibrator wood chips inlet 9a and a defibrator wood fibre outlet 9b.
  • the defibrator system 1; 1' comprises furthermore a feed screw arrangement 11 which is connecting said preheater 3 with the defibrator 7.
  • the feed screw arrangement 11 is connected to said preheater wood chips outlet 5b and to said defibrator wood chips inlet 9a and is configured for feeding wood chips from the preheater wood chips outlet 5b to the defibrator wood chips inlet 9a.
  • the feed screw arrangement 11 comprises in this embodiment one plug feed screw 13 and one ribbon feed screw 15 connected to each other, wherein the plug feed screw 13 is connected to the preheater woodchips outlet 5b and is configured for feeding wood chips into the ribbon feed screw 15, which is connected to the defibrator wood chips inlet 9a and is configured for transferring the wood chips from the plug feed screw 13 to the defibrator 7.
  • the plug feed screw could be exchanged to another feeding arrangement between the preheater wood chips outlet 5b and the ribbon feed screw.
  • the ribbon feed screw 15 comprises a hollow centre allowing steam to travel through the ribbon feed screw in the opposite direction to the wood chips feeding direction through the ribbon feed screw 15.
  • the defibrator system 1; 1' comprises furthermore a return steam pipe arrangement 21 comprising a return steam pipe 23 which is extending between a return steam pipe first end 25a and a return steam pipe second end 25b and which is connected in the return steam pipe first end 25a to the feed screw arrangement 11 and in the return steam pipe second end 25b to the preheater 3.
  • Said return steam pipe second end 25b is connected to the top portion 6a of the preheater 3.
  • the return steam pipe 23 is configured for transferring steam from the feed screw arrangement 11 to the preheater 3.
  • the steam which is released during defibration travels back through the ribbon feed screw and will raise the pressure within the feed screw arrangement.
  • the return steam pipe 23 is provided for transferring the steam to the preheater 3.
  • the return steam pipe arrangement 21 comprises a first sensor arrangement 31a provided in connection with the return steam pipe 23 at a position which is closer to the return steam pipe first end 25a than the return steam pipe second end 25b.
  • a first sensor arrangement 31a a feature can be measured in the return steam pipe 23 and by measuring this feature closer to the return steam pipe first end 25a than the return steam pipe second end 25b this measurement can be compared to a measurement performed for example in a top portion 6a of the preheater 3 where another sensor may be provided.
  • a second sensor arrangement 31b is provided in the top portion 6a of the preheater 3. This is shown in Figure 1 and in Figure 2a.
  • a second sensor arrangement 31b is provided in connection with the return steam pipe 23 instead.
  • the second sensor arrangement 31b is in this embodiment positioned closer to the return steam pipe second end 25b than the return steam pipe first end 25a.
  • the first sensor arrangement 31a can be positioned within a distance from the return steam pipe first end 25a which is less than 1/4 or less than 1/6 of a total length L of the return steam pipe.
  • the second sensor arrangement 31b can be positioned within a distance from the return steam pipe second end 25b which is less than 1/4 or less than 1/6 of a total length L of the return steam pipe.
  • the first sensor arrangement 31a can be positioned in connection with or in vicinity of the return steam pipe first end 25a and the second sensor arrangement 31b can be positioned in connection with or in vicinity of the return steam pipe second end 25a.
  • a return steam pipe arrangement 21 is shown schematically, wherein the return steam pipe arrangement 21 comprises a return steam pipe 23, a first sensor arrangement 31a and a second sensor arrangement 31b.
  • the return steam pipe arrangement 21 comprises only the first sensor arrangement 31a and the second sensor arrangement 31b can be provided in a top portion 6a of the preheater 3 itself or an already provided sensor, for example an already provided pressure sensor in the preheater, can be used for performing measurements to be compared with measurements of the first sensor arrangement 31a.
  • a return steam pipe arrangement 21 which can be connected to an already existing defibrator system is provided.
  • the return steam pipe arrangement 21 is configured for being connectable in the return steam pipe first end 25a to a feed screw arrangement 11 provided for feeding wood chips between a preheater 3 and a defibrator 7 in a defibrator system 1; 1' and in the return steam pipe second end 25b to the preheater 3 of the defibrator system 1; 1'.
  • the first and the possible second sensor arrangements 31s, 31b can be provided within a distance from the return steam pipe first and second ends 25a, 25b respectively which is for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23 as described above.
  • the return steam pipe arrangement 21 can comprise in the return steam pipe first end 25a a first connection device 41a configured for connection to a feed screw arrangement 11 in a defibrator system 1; 1' and in the return steam pipe second end 25b a second connection device 41b configured for connection to the preheater 3 of the defibrator system 1; 1'.
  • the first and second sensor arrangements 31a, 31b comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends 25a, 25b.
  • the first sensor arrangement 31a and the second sensor arrangement 31b can comprise for example one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor.
  • the first sensor arrangement 31a can be provided in connection with the return steam pipe 23 such that a feature inside the return steam pipe 23 can be measured by the first sensor arrangement 31a.
  • the first sensor arrangement 31a can also be positioned directly inside the return steam pipe 23. If a second sensor arrangement 31b is provided in connection with the return steam pipe 23 this can also be provided in connection with the return steam pipe or directly inside the return steam pipe 23.
  • the feature measured by the first and second sensor arrangements 31, 31b can be used for assessing a condition of the return steam pipe 23, for example if the return steam pipe has been clogged and needs to be cleaned this can be seen as a difference in the measured feature between the first and second sensor arrangements 31a, 31b or a difference in the measured feature between the first sensor arrangement 31a and another sensor provided in a top portion 6a of the preheater 3. For example, if pressure is measured a clogged return steam pipe 23 would show up as different pressure values measured by the first and second sensor arrangements 31a, 31b.
  • a method for defibrating wood chips is also provided.
  • the method steps are illustrated in a flow chart in Figure 4.
  • the method comprises the following steps described in order below:
  • SI Providing wood chips into a preheater 3 through a preheater wood chips inlet 5a.
  • S3 Feeding said preheated wood chips from a preheater wood chips outlet 5b of the preheater 3 to a defibrator wood chips inlet 9a of a connected defibrator 7 by a feed screw arrangement 11 which is connecting said preheater wood chips outlet 5b with said defibrator wood chips inlet 9a.
  • S4 Defibrating said wood chips in said defibrator 7.
  • S6 Measuring a feature in the return steam pipe 23 with a first sensor arrangement 31a at a position which is closer to the return steam pipe first end 25a than the return steam pipe second end 25b. Measuring a feature in the return steam pipe with a first sensor arrangement 31a can be performed within a distance from the return steam pipe first end 25a which can be for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23.
  • S7 Measuring a feature in the defibrator system 1; 1' with a second sensor arrangement 31b which is provided either in a top portion 6a of said preheater 3 or at a position in connection with the return steam pipe 23 within a distance from the return steam pipe second end 25b which can be for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23.
  • the method further comprises the step of cleaning the return steam pipe if a measured feature indicates that the return steam pipe may be clogged.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Disintegrating Or Milling (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

A defibrator system comprising: a preheater (3), a defibrator (7), a feed screw arrangement (11) and a return steam pipe (23) configured for transferring steam from the feed screw arrangement to the preheater, wherein the return steam pipe comprises a sensor arrangement (31a) which can measure a feature that can be used for evaluating if there is a stop or reduced possibility for the steam to pass through the return steam pipe. A return steam pipe arrangement and a method for defibrating wood chips are also disclosed.

Description

A SYSTEM AND METHOD FOR DEFIBRATING WOOD CHIPS, AND A RETURN STEAM PIPE
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a defibrator system and to a return steam pipe arrangement in a defibrator system and to a method for defibrating wood chips.
BACKGROUND
A defibrator system comprises a preheater for preheating wood chips before they are defibrated in a defibrator. The preheated wood chips are transferred out from the preheater by for example a plug feed screw into another feed screw which is a ribbon feed screw which transfers the preheated wood chips into the defibrator. The ribbon feed screw is hollow whereby a return flow of steam is allowed from the defibrator through the ribbon feed screw. A return steam pipe is further provided in the defibrator system for balancing the pressure between the ribbon feed screw and the preheater. The return steam pipe will transfer steam from the ribbon feed screw back to the preheater. The return steam pipe is connected in one end to the ribbon feed screw and in the other end to a top part of the preheater.
There may be problems with clogging in the return steam pipe and the return steam pipe may have to be cleaned repeatedly. SUMMARY
An object of the invention is to provide a more stable and reliable defibration process in the defibrator system.
A further object of the invention is to improve the process of returning steam from the defibrator to the preheater. This is achieved by a defibrator system, by a method for defibrating wood chips and by a return steam pipe arrangement according to the independent claims. According to one aspect of the invention a defibrator system for defibrating wood chips is provided. Said defibrator system comprises: a preheater comprising a preheater wood chips inlet and a preheater wood chips outlet; a defibrator comprising a defibrator wood chips inlet and a defibrator wood fibre outlet; a feed screw arrangement which is connected to said preheater wood chips outlet and to said defibrator wood chips inlet and configured for feeding wood chips from the preheater wood chips outlet to the defibrator wood chips inlet; and a return steam pipe arrangement comprising a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is connected in the return steam pipe first end to the feed screw arrangement and in the return steam pipe second end to the preheater, wherein said return steam pipe is configured for transferring steam from the feed screw arrangement to the preheater, wherein the return steam pipe arrangement comprises a first sensor arrangement provided in connection with the return steam pipe at a position which is closer to the return steam pipe first end than the return steam pipe second end.
According to another aspect of the invention a method for defibrating wood chips is provided, said method comprising the steps of: providing wood chips into a preheater through a preheater wood chips inlet; preheating said wood ships in the preheater; feeding said preheated wood chips from a preheater wood chips outlet of the preheater to a defibrator wood chips inlet of a connected defibrator by a feed screw arrangement which is connecting said preheater wood chips outlet with said defibrator wood chips inlet; defibrating said wood chips in said defibrator; and returning steam from the defibrator via the feed screw arrangement to the preheater via a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is connecting the feed screw arrangement and the preheater, wherein the method further comprises the step of measuring a feature in the return steam pipe with a first sensor arrangement at a position which is closer to the return steam pipe first end than the return steam pipe second end.
According to another aspect of the invention a return steam pipe arrangement is provided comprising a return steam pipe which is extending between a return steam pipe first end and a return steam pipe second end and which is configured for being connectable in the return steam pipe first end to a feed screw arrangement provided for feeding wood chips between a preheater and a defibrator in a defibrator system and in the return steam pipe second end to the preheater of the defibrator system, wherein said return steam pipe is configured for returning steam from the defibrator and the feed screw arrangement to the preheater and wherein the return steam pipe arrangement comprises a first sensor arrangement provided in connection with the return steam pipe at a position which is closer to the return steam pipe first end than the return steam pipe second end.
Hereby a defibrator system is provided in which a feature of the steam which is passing the return steam pipe can be measured closer to the connection of the return steam pipe to the feed screw arrangement than to the preheater. This measured feature can be used for evaluating if there is for example a stop or a reduced possibility for the steam to pass through the return steam pipe. Hereby such a problem can be taken care of by for example cleaning the pipe in good time. Hereby a defibration process efficiency can be improved and the process will be more reliable and predictable.
Furthermore, a return steam pipe arrangement is provided according to the invention which can be connected to an already existing defibrator system which return steam pipe arrangement provides the possibility to measure a feature of the steam passing the return steam pipe at a position which is closer to the feed screw arrangement than the preheater.
In one embodiment of the invention the first sensor arrangement is provided in connection with the return steam pipe within a distance from the return steam pipe first end which is less than 1/4 of a total length (L) of the return steam pipe. In one embodiment of the invention the defibrator system further comprises a second sensor arrangement which is provided either in connection with the return steam pipe within a distance from the return steam pipe second end which is less than 1/4 of a total length (L) of the return steam pipe or in a top portion of the preheater.
In one embodiment of the invention the first sensor arrangement is provided in connection with the return steam pipe first end and the second sensor arrangement is provided in connection with the return steam pipe second end.
In one embodiment of the invention the first and second sensor arrangements comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends.
In one embodiment of the invention said preheater wood chips inlet is arranged in a top portion of said preheaterand said preheaterwood chips outlet is arranged in a bottom portion of said preheater.
In one embodiment of the invention said return steam pipe second end is connected to a top portion of the preheater.
In one embodiment of the invention the feed screw arrangement comprises a ribbon feed screw.
In one embodiment of the invention the feed screw arrangement comprises a plug feed screw and a ribbon feed screw connected to each other, wherein the plug feed screw is connected to the preheater woodchips outlet and is configured for feeding wood chips into the ribbon feed screw, which is connected to the defibrator wood chips inlet and is configured for transferring the wood chips from the plug feed screw to the defibrator, wherein said ribbon feed screw comprises a hollow centre allowing steam to travel through the ribbon feed screw in the opposite direction to a material feeding direction of the ribbon feed screw.
In one embodiment of the invention the first and a possible second sensor arrangement can comprise one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor.
Further embodiments are described in the detailed description and in the patent claims. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows schematically a perspective view, partly in cross section, of a defibrator system according to one embodiment of the invention.
Figure 2a is a cross section of the defibrator system as shown in Figure 1. Figure 2b is a cross section of a defibrator system according to another embodiment of the invention.
Figure 3 shows schematically a return steam pipe arrangement according to one embodiment of the invention.
Figure 4 is a flow chart describing some of the steps of a method for defibrating wood chips according to the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
Figure 1 shows schematically a perspective view, partly in cross section, of a defibrator system 1 according to one embodiment of the invention. Figure 2a shows schematically a cross section of the same defibrator system 1 as shown in Figure 1. Figure 2b is a cross section of a defibrator system 1' according to another embodiment of the invention. Figure 3 shows schematically a return steam pipe arrangement 21 according to one embodiment of the invention. The invention is now described with reference to all drawings 1-3. Most of the details are the same for all embodiments and these details are given the same reference numbers.
The defibrator system 1; 1' comprises a preheater 3 comprising a preheater wood chips inlet 5a and a preheater wood chips outlet 5b. The preheater wood chips inlet 5a is arranged in a top portion 6a of said preheater 3 and said preheater wood chips outlet 5b is arranged in a bottom portion 6b of said preheater 3. Wood chips are fed into the preheater 3 via the preheater wood chips inlet 5a for being treated in the preheater before they are transferred out through the preheater wood chips outlet 5b for being defibrated. The defibrator system 1; 1' comprises further a defibrator 7 configured for defibrating the wood chips after they have been treated in the preheater 3. The defibrator 7 comprises a defibrator wood chips inlet 9a and a defibrator wood fibre outlet 9b. The defibrator system 1; 1' comprises furthermore a feed screw arrangement 11 which is connecting said preheater 3 with the defibrator 7. The feed screw arrangement 11 is connected to said preheater wood chips outlet 5b and to said defibrator wood chips inlet 9a and is configured for feeding wood chips from the preheater wood chips outlet 5b to the defibrator wood chips inlet 9a. The feed screw arrangement 11 comprises in this embodiment one plug feed screw 13 and one ribbon feed screw 15 connected to each other, wherein the plug feed screw 13 is connected to the preheater woodchips outlet 5b and is configured for feeding wood chips into the ribbon feed screw 15, which is connected to the defibrator wood chips inlet 9a and is configured for transferring the wood chips from the plug feed screw 13 to the defibrator 7. In other embodiments the plug feed screw could be exchanged to another feeding arrangement between the preheater wood chips outlet 5b and the ribbon feed screw. The ribbon feed screw 15 comprises a hollow centre allowing steam to travel through the ribbon feed screw in the opposite direction to the wood chips feeding direction through the ribbon feed screw 15. The defibrator system 1; 1' comprises furthermore a return steam pipe arrangement 21 comprising a return steam pipe 23 which is extending between a return steam pipe first end 25a and a return steam pipe second end 25b and which is connected in the return steam pipe first end 25a to the feed screw arrangement 11 and in the return steam pipe second end 25b to the preheater 3. Said return steam pipe second end 25b is connected to the top portion 6a of the preheater 3. The return steam pipe 23 is configured for transferring steam from the feed screw arrangement 11 to the preheater 3. The steam which is released during defibration travels back through the ribbon feed screw and will raise the pressure within the feed screw arrangement. For balancing the pressure between the feed screw arrangement and the preheater the return steam pipe 23 is provided for transferring the steam to the preheater 3.
According to the invention the return steam pipe arrangement 21 comprises a first sensor arrangement 31a provided in connection with the return steam pipe 23 at a position which is closer to the return steam pipe first end 25a than the return steam pipe second end 25b. With such a first sensor arrangement 31a a feature can be measured in the return steam pipe 23 and by measuring this feature closer to the return steam pipe first end 25a than the return steam pipe second end 25b this measurement can be compared to a measurement performed for example in a top portion 6a of the preheater 3 where another sensor may be provided. In one embodiment of the invention a second sensor arrangement 31b is provided in the top portion 6a of the preheater 3. This is shown in Figure 1 and in Figure 2a. In Figure 2b and in Figure 3 another embodiment is shown where a second sensor arrangement 31b is provided in connection with the return steam pipe 23 instead. The second sensor arrangement 31b is in this embodiment positioned closer to the return steam pipe second end 25b than the return steam pipe first end 25a. In some embodiments the first sensor arrangement 31a can be positioned within a distance from the return steam pipe first end 25a which is less than 1/4 or less than 1/6 of a total length L of the return steam pipe. The second sensor arrangement 31b can be positioned within a distance from the return steam pipe second end 25b which is less than 1/4 or less than 1/6 of a total length L of the return steam pipe. In some embodiments of the invention the first sensor arrangement 31a can be positioned in connection with or in vicinity of the return steam pipe first end 25a and the second sensor arrangement 31b can be positioned in connection with or in vicinity of the return steam pipe second end 25a. In Figure 3 a return steam pipe arrangement 21 is shown schematically, wherein the return steam pipe arrangement 21 comprises a return steam pipe 23, a first sensor arrangement 31a and a second sensor arrangement 31b. In another embodiment the return steam pipe arrangement 21 comprises only the first sensor arrangement 31a and the second sensor arrangement 31b can be provided in a top portion 6a of the preheater 3 itself or an already provided sensor, for example an already provided pressure sensor in the preheater, can be used for performing measurements to be compared with measurements of the first sensor arrangement 31a. According to one aspect of the invention a return steam pipe arrangement 21 which can be connected to an already existing defibrator system is provided. The return steam pipe arrangement 21 is configured for being connectable in the return steam pipe first end 25a to a feed screw arrangement 11 provided for feeding wood chips between a preheater 3 and a defibrator 7 in a defibrator system 1; 1' and in the return steam pipe second end 25b to the preheater 3 of the defibrator system 1; 1'. The first and the possible second sensor arrangements 31s, 31b can be provided within a distance from the return steam pipe first and second ends 25a, 25b respectively which is for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23 as described above. The return steam pipe arrangement 21 can comprise in the return steam pipe first end 25a a first connection device 41a configured for connection to a feed screw arrangement 11 in a defibrator system 1; 1' and in the return steam pipe second end 25b a second connection device 41b configured for connection to the preheater 3 of the defibrator system 1; 1'.
Suitably the first and second sensor arrangements 31a, 31b comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends 25a, 25b. The first sensor arrangement 31a and the second sensor arrangement 31b can comprise for example one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor. The first sensor arrangement 31a can be provided in connection with the return steam pipe 23 such that a feature inside the return steam pipe 23 can be measured by the first sensor arrangement 31a. The first sensor arrangement 31a can also be positioned directly inside the return steam pipe 23. If a second sensor arrangement 31b is provided in connection with the return steam pipe 23 this can also be provided in connection with the return steam pipe or directly inside the return steam pipe 23.
The feature measured by the first and second sensor arrangements 31, 31b can be used for assessing a condition of the return steam pipe 23, for example if the return steam pipe has been clogged and needs to be cleaned this can be seen as a difference in the measured feature between the first and second sensor arrangements 31a, 31b or a difference in the measured feature between the first sensor arrangement 31a and another sensor provided in a top portion 6a of the preheater 3. For example, if pressure is measured a clogged return steam pipe 23 would show up as different pressure values measured by the first and second sensor arrangements 31a, 31b.
According to the invention a method for defibrating wood chips is also provided. The method steps are illustrated in a flow chart in Figure 4. The method comprises the following steps described in order below:
SI: Providing wood chips into a preheater 3 through a preheater wood chips inlet 5a.
S2: Preheating said wood ships in the preheater 3.
S3: Feeding said preheated wood chips from a preheater wood chips outlet 5b of the preheater 3 to a defibrator wood chips inlet 9a of a connected defibrator 7 by a feed screw arrangement 11 which is connecting said preheater wood chips outlet 5b with said defibrator wood chips inlet 9a. S4: Defibrating said wood chips in said defibrator 7.
S5: Returning steam from the defibrator 7 via the feed screw arrangement 11 to the preheater 3 via a return steam pipe 23 which is extending between a return steam pipe first end 25a and a return steam pipe second end 25b and which is connecting the feed screw arrangement 11 and the preheater 3.
S6: Measuring a feature in the return steam pipe 23 with a first sensor arrangement 31a at a position which is closer to the return steam pipe first end 25a than the return steam pipe second end 25b. Measuring a feature in the return steam pipe with a first sensor arrangement 31a can be performed within a distance from the return steam pipe first end 25a which can be for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23.
S7: Measuring a feature in the defibrator system 1; 1' with a second sensor arrangement 31b which is provided either in a top portion 6a of said preheater 3 or at a position in connection with the return steam pipe 23 within a distance from the return steam pipe second end 25b which can be for example less than 1/4 or less than 1/6 of a total length (L) of the return steam pipe 23.
Possibly the method further comprises the step of cleaning the return steam pipe if a measured feature indicates that the return steam pipe may be clogged.

Claims

1. A defibrator system for defibrating wood chips, said defibrator system (1;1') comprising: a preheater (3) comprising a preheater wood chips inlet (5a) and a preheater wood chips outlet (5b); a defibrator (7) comprising a defibrator wood chips inlet (9a) and a defibrator wood fibre outlet (9b); a feed screw arrangement (11) which is connected to said preheater wood chips outlet (5b) and to said defibrator wood chips inlet (9a) and configured for feeding wood chips from the preheater wood chips outlet (5b) to the defibrator wood chips inlet (9a); and a return steam pipe arrangement (21) comprising a return steam pipe (23) which is extending between a return steam pipe first end (25a) and a return steam pipe second end (25b) and which is connected in the return steam pipe first end (25a) to the feed screw arrangement (11) and in the return steam pipe second end (25b) to the preheater (3), wherein said return steam pipe (23) is configured for transferring steam from the feed screw arrangement (11) to the preheater (3), wherein the return steam pipe arrangement (21) comprises a first sensor arrangement (31a) provided in connection with the return steam pipe (23) at a position which is closer to the return steam pipe first end (25a) than the return steam pipe second end (25b), wherein a feature can be measured by the first sensor arrangement, which feature can be used for evaluating if there is a stop or reduced possibility for the steam to pass through the return steam pipe.
2. Defibrator system according to claim 1, wherein the first sensor arrangement (31a) is provided in connection with the return steam pipe (23) within a distance from the return steam pipe first end (25a) which is less than 1/4 of a total length (L) of the return steam pipe (23).
3. Defibrator system according to claim 1 or 2, wherein the defibrator system (1; 1') further comprises a second sensor arrangement (31b) which is provided either in connection with the return steam pipe (23) within a distance from the return steam pipe second end (25b) which is less than 1/4 of a total length (L) of the return steam pipe (23) or in a top portion (6a) of the preheater (3).
4. Defibrator system according to claim 3, wherein the first sensor arrangement (31a) is provided in connection with the return steam pipe first end (25a) and wherein the second sensor arrangement (31b) is provided in connection with the return steam pipe second end (25b).
5. Defibrator system according to claim 3 or 4, wherein the first and second sensor arrangements (31a, 31b) comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends (25a, 25b).
6. Defibrator system according to any one of the preceding claims, wherein said preheater wood chips inlet (5a) is arranged in a top portion (6a) of said preheater (3) and said preheater wood chips outlet (5b) is arranged in a bottom portion (6b) of said preheater (3).
7. Defibrator system according to any one of the preceding claims, wherein said return steam pipe second end (25b) is connected to a top portion (6a) of the preheater (3).
8. Defibrator system according to any one of the preceding claims, wherein the feed screw arrangement (11) comprises a ribbon feed screw (15).
9. Defibrator system according to any one of the preceding claims, wherein the feed screw arrangement (11) comprises a plug feed screw (13) and a ribbon feed screw (15) connected to each other, wherein the plug feed screw (13) is connected to the preheater woodchips outlet (5b) and is configured for feeding wood chips into the ribbon feed screw (15), which is connected to the defibrator wood chips inlet (9a) and is configured for transferring the wood chips from the plug feed screw (13) to the defibrator (7), wherein said ribbon feed screw (15) comprises a hollow centre allowing steam to travel through the ribbon feed screw (15) in the opposite direction to a material feeding direction of the ribbon feed screw (15).
10. Defibrator system according to any one of the preceding claims, wherein the first and a possible second sensor arrangement (31a, 31b) can comprise one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor.
11. A method for defibrating wood chips, said method comprising the steps of: providing (SI) wood chips into a preheater (3) through a preheater wood chips inlet (5a); preheating (S2) said wood ships in the preheater (3); feeding (S3) said preheated wood chips from a preheater wood chips outlet (5b) of the preheater (3) to a defibrator wood chips inlet (9a) of a connected defibrator (7) by a feed screw arrangement (11) which is connecting said preheater wood chips outlet (5b) with said defibrator wood chips inlet (9a); defibrating (S4) aid wood chips in said defibrator (7); and returning steam (S5) from the defibrator (7) via the feed screw arrangement (11) to the preheater (3) via a return steam pipe (23) which is extending between a return steam pipe first end (25a) and a return steam pipe second end (25b) and which is connecting the feed screw arrangement (11) and the preheater (3); wherein the method further comprises the step of measuring (S6) a feature in the return steam pipe (23) with a first sensor arrangement (31a) at a position which is closer to the return steam pipe first end (25a) than the return steam pipe second end (25b), which feature can be used for evaluating if there is a stop or reduced possibility for the steam to pass through the return steam pipe.
12. Method according to claim 11, wherein the step of measuring (S6) a feature in the return steam pipe (23) with a first sensor arrangement (31a) is performed within a distance from the return steam pipe first end (25a) which is less than 1/4 of a total length (L) of the return steam pipe (23).
13. Method according to claim 11 or 12, wherein the method further comprises the step of measuring (S7) a feature in the defibrator system (1; 1') with a second sensor arrangement (31b) which is provided either in a top portion (6a) of said preheater (3) or at a position in connection with the return steam pipe (23) within a distance from the return steam pipe second end (25b) which is less than 1/4 of a total length (L) of the return steam pipe (23).
14. Method according to claim 13, wherein the step of measuring (S6) a feature in the return steam pipe (23) with a first sensor arrangement (31a) is performed in vicinity of the return steam pipe first end (25a) and the step of measuring (S7) a feature with a second sensor arrangement (31b) is performed in vicinity of the return steam pipe second end (25b).
15. Method according to claim 13 or 14, wherein the step of measuring (S6) a feature by a first sensor arrangement (31a) and measuring (S7) a feature by a second sensor arrangement (31b) comprises measuring at least one same feature by the first and second sensor arrangements (31a, 31b) for comparative measurements between the return steam pipe first and second ends (25a, 25b).
16. Method according to any one of the claims 11-15, further comprising the step of cleaning the return steam pipe (23) if a measured feature indicates that the return steam pipe may be clogged.
17. Method according to any one of the claims 11-16, wherein the step of returning steam (S5) from the defibrator (7) via the feed screw arrangement (11) to the preheater (3) via a return steam pipe (23) is performed by returning steam to a top part (6a) of the preheater (3).
18. Method according to any one of the claims 11-17, wherein the step of feeding (S3) said preheated wood chips from a preheater wood chips outlet (5b) to a defibrator wood chips inlet (9a) by a feed screw arrangement (11) comprises feeding the wood chips at least partly by a ribbon feed screw (15).
19. Method according to any one of the claims 11-18, wherein the step of measuring (S6, S7) a feature by the first and second sensor arrangements (31a, 31b) comprises measuring one or more of: a pressure, a temperature, a flow and a speed.
20. A return steam pipe arrangement (21) comprising a return steam pipe (23) which is extending between a return steam pipe first end (25a) and a return steam pipe second end (25b) and which is configured for being connectable in the return steam pipe first end (25a) to a feed screw arrangement (11) provided for feeding wood chips between a preheater (3) and a defibrator (7) in a defibrator system (1; 1') and in the return steam pipe second end (25b) to the preheater (3) of the defibrator system (1; 1'), wherein said return steam pipe (23) is configured for returning steam from the defibrator (7) and the feed screw arrangement (11) to the preheater (3) and wherein the return steam pipe arrangement (21) comprises a first sensor arrangement (31a) provided in connection with the return steam pipe (23) at a position which is closer to the return steam pipe first end (25a) than the return steam pipe second end (25b) ), wherein a feature can be measured by the first sensor arrangement, which feature can be used for evaluating if there is a stop or reduced possibility for the steam to pass through the return steam pipe.
21. Return steam pipe arrangement according to claim 20, wherein the first sensor arrangement (31a) is provided in connection with the return steam pipe (23) within a distance from the return steam pipe first end (25a) which is less than 1/4 of a total length (L) of the return steam pipe (23).
22. Return steam pipe arrangement according to claim 20 or 21, wherein the return steam pipe arrangement (21) further comprises a second sensor arrangement (31b) which is provided in connection with the return steam pipe (23) within a distance from the return steam pipe second end (25b) which is less than 1/4 of a total length (L) of the return steam pipe (23).
23. Return steam pipe arrangement according to claim 22, wherein the first sensor arrangement (31a) is provided in connection with the return steam pipe first end (25a) and wherein the second sensor arrangement (31b) is provided in connection with the return steam pipe second end (25b).
24. Return steam pipe arrangement according to claim 22 or 23, wherein the first and second sensor arrangements (31a, 31b) comprises at least one same type of sensor for comparative measurements between the return steam pipe first and second ends (25a, 25b).
25. Return steam pipe arrangement according to any one of the claims 20-24, wherein the return steam pipe arrangement (21) comprises in the return steam pipe first end (25a) a first connection device (41a) configured for connection to a feed screw arrangement (11) in a defibrator system (1; 1') and in the return steam pipe second end (25b) a second connection device (41b) configured for connection to the preheater (3) of the defibrator system (1; 1').
26. Return steam pipe arrangement according to any one of the claims 20-25, wherein the first and second sensor arrangements (31a, 31b) can comprise one or more of: a pressure sensor, a temperature sensor, a flow sensor and a speed sensor.
EP21800699.7A 2020-05-07 2021-03-29 A system and method for defibrating wood chips, and a return steam pipe Pending EP4146861A4 (en)

Applications Claiming Priority (2)

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SE2050527A SE543739C2 (en) 2020-05-07 2020-05-07 A defibrator system and a return steam pipe
PCT/SE2021/050276 WO2021225491A1 (en) 2020-05-07 2021-03-29 A system and method for defibrating wood chips, and a return steam pipe

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EP4146861A1 true EP4146861A1 (en) 2023-03-15
EP4146861A4 EP4146861A4 (en) 2024-06-26

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GB515944A (en) * 1937-06-12 1939-12-19 Hermann Basler Apparatus for disintegrating vegetable fibrous materials
SE386694B (en) * 1973-09-06 1976-08-16 Sca Development Ab KIT FOR TREATMENT OF FIBER MATERIAL WHEN THE FIBER MATERIAL IS FIRST PREHEATED WITH ANGA IN A PRE-MAKER
SE403916B (en) * 1975-06-04 1978-09-11 Rolf Bertil Reinhall DEVICE FOR MILLING APPARATUS FOR LIGNOCELLULOSE-MATERIAL
SE419659B (en) * 1976-03-19 1981-08-17 Rolf Bertil Reinhall SET AND DEVICE FOR MANUFACTURING FIBER MASS OF FIBER LIGNOCELLULOSALLY MATERIAL
CA1074606A (en) * 1977-06-08 1980-04-01 Llewellyn E. Clark Method and apparatus for thermo-mechanical pulping
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EP4146861A4 (en) 2024-06-26
SE543739C2 (en) 2021-07-06
WO2021225491A1 (en) 2021-11-11

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