WO2013004915A1 - Method and apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp - Google Patents

Method and apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp Download PDF

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Publication number
WO2013004915A1
WO2013004915A1 PCT/FI2012/050714 FI2012050714W WO2013004915A1 WO 2013004915 A1 WO2013004915 A1 WO 2013004915A1 FI 2012050714 W FI2012050714 W FI 2012050714W WO 2013004915 A1 WO2013004915 A1 WO 2013004915A1
Authority
WO
WIPO (PCT)
Prior art keywords
dryer section
dryer
air
pulp
exhaust air
Prior art date
Application number
PCT/FI2012/050714
Other languages
French (fr)
Inventor
Raimo Rajala
Kalle RIIHIMÄKI
Original Assignee
Balance Engineering Oy
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 Balance Engineering Oy filed Critical Balance Engineering Oy
Publication of WO2013004915A1 publication Critical patent/WO2013004915A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/18—Drying webs by hot air
    • D21F5/185—Supporting webs in hot air dryers
    • D21F5/187—Supporting webs in hot air dryers by air jets
    • D21F5/188—Blowing devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/18—Drying webs by hot air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
    • F26B13/101—Supporting materials without tension, e.g. on or between foraminous belts
    • F26B13/104—Supporting materials without tension, e.g. on or between foraminous belts supported by fluid jets only; Fluid blowing arrangements for flotation dryers, e.g. coanda nozzles

Definitions

  • the invention relates to a method as defined in the preamble of claim 1 and to an apparatus as defined in the preamble of claim 8 for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp.
  • the dryer device used may be e.g. a warm air blowing device, such as a blow box.
  • the dryer devices are arranged into an assembly to constitute a dryer assembly.
  • providing encapsulation around the dryer assembly is known.
  • the dryer section conventionally includes several dryer assemblies.
  • a single dryer assembly includes several dryer devices.
  • the pulp web is conducted through the different dryer assemblies. Warm air is blown against the pulp web from at least one side, preferably from both sides.
  • the function of the dryer section is to remove water and moisture from the pulp web.
  • the objective of the invention is to dis- close a new type of method and apparatus for increasing drying efficiency and energy efficiency in connec ⁇ tion with the manufacture of pulp and particularly in connection with the dryer section thereof.
  • the invention is based on a method for in- creasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, wherein the pulp web is conducted in the dry ⁇ er section through more than one dryer device and warm air. is blown against the web by means of the dryer de- vice to provide removal of moisture by evaporation, and the moisture removed from the pulp web is conducted out from the dryer section with the exhaust air and replacement air is fed to the dryer section to replace the exhaust air that has been removed, in a preferred embodiment in an amount equal to the amount of the exhaust air.
  • the exhaust air including the moisture removed from the pulp web is sucked out from the dryer section, substantially from the high evaporation area and from the first, end of the dryer section, e.g. from the top part of the dryer section, and replacement air is fed to the tail end of the dryer section, e.g. to . the bottom part of the dryer section.
  • the invention is based on an apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, the dryer section including dryer devices and means, e.g. a drawing roll, conveyor line or the like, for conducting the pulp web through more than one dryer device to blow warm air against the web to provide removal of moisture by evaporation, and the apparatus includes removing means for conducting the exhaust air including the moisture removed from the pulp web out from the dryer section and feeding means for feeding replacement air to the dryer section to replace the exhaust air that has been removed.
  • the dryer section including dryer devices and means, e.g. a drawing roll, conveyor line or the like, for conducting the pulp web through more than one dryer device to blow warm air against the web to provide removal of moisture by evaporation
  • the apparatus includes removing means for conducting the exhaust air including the moisture removed from the pulp web out from the dryer section and feeding means for feeding replacement air to the dryer section to replace the exhaust air that has been removed.
  • the apparatus includes at least one exhaust air device for sucking the exhaust air including the moisture removed from the pulp web out from the dryer section substantially in the high evap- oration area and at the first end of the dryer section, and distribution means for distributing replacement air to be fed to the tail end of the dryer section.
  • the invention is specifically based on in- creasing the drying efficiency and energy efficiency in connection with the drying of the pulp web.
  • the basic idea of the invention is to modify the existing devices so as to remove moisture in areas where it is being developed. Preferably, dry air is provided as the replacement.
  • a predetermined ⁇ must exist between the temperatures of the pulp web and the blow from the dryer device.
  • the invention preferably acts on the external balance of the dryer section.
  • replacement air is fed to the tail end of the dryer section, e.g. to the bottom part of the dryer section, and substantially to the high evaporation and/or rising evaporation area of the dryer section.
  • the top part of the dryer section or part of the top part of the dryer section is compartmented to form a compartment and replacement air is fed to that compartment.
  • replacement air is conducted over and/or in front of the exhaust air suction area in the direction of movement of the pulp web to re- place the removed exhaust air.
  • the apparatus includes distribution means for distributing the replacement air to be fed to the tail end of the dryer section and substantially to the high evaporation and/or rising evaporation area of the dryer section.
  • replacement air is fed to the start of the dryer section, in one preferred embodiment close to the area where the pulp web is conducted into the dryer section. This way, condensation and droplet formation of moisture on the surface of the web and/or the structures of the dryer section or inside the web is prevented.
  • the apparatus includes means for con-ducting the replacement air to the start of the dryer section.
  • replacement air an air flow fed to the dryer section to replace exhaust air and to be used in drying of the pulp web.
  • the replacement air circulates as circulation air in the dryer section and becomes exhaust air, including the moisture removed from the pulp web.
  • replacement air is fed to the tail end of the dryer section and in some preferred embodiments additionally to the high evaporation and/or rising evaporation areas.
  • replacement air it is possible to use air from any air system or circulation system in the manufacture of pulp that is suitable for the pur ⁇ pose of use. Alternatively, fresh air can be used.
  • exhaust air is meant the air that conveys away water and moisture evapo- rated from the web, in this invention from the high evaporation area and from the first end of the dryer section.
  • the water evaporated from the pulp web has accumulated into the exhaust air.
  • the pulp web is heated in the rising evapora- tion area. In this area, moisture is conventionally not able to accumulate. Most of the evaporation occurs in the high evaporation area.
  • first end of the dryer section is meant the first part of the dryer section in the direction movement of the pulp web.
  • first end of the dryer section may refer to the top part and/or to the front part of the dryer section over and/or in front of the first dryer device or devices.
  • tail end of the dryer section is meant the tail part of the dryer section in the direction of movement of the pulp web.
  • the tail end of the dryer section may refer to the bottom part or the latter part of the dryer section under and/or after the last dryer device or devices.
  • web any fiber-based pulp web or other type of web-like structure in the manufacture of pulp, such as a sheet, board, wet web or the like.
  • pulp any fi- ber-based product.
  • the pulp may be formed by a chemical method, mechanical method, chemi-mechanical method or other pulp manufacturing method known per se.
  • the pulp may be formed from fibers, such as wood or plant fibers, recycled pulp, other botanical pulp or other suitable raw material or the like or combinations thereof.
  • the pulp may contain suitable additives.
  • the dryer section is based on airborne drying. In this case, the drying takes place without a direct contact surface between the pulp web and the dryer device. In airborne drying, moisture is evaporated throughout the entire travel.
  • a fan dry- , er is used as the dryer device.
  • at least one dryer device is a fan dryer.
  • the pulp web can be dried by a fan dryer without direct contact to the web. Warm blowing air with the temperature preferably in the constant region is blown to the surface of the pulp web by means of the fan dryer.
  • warm air is blown against the pulp web from both sides of the web.
  • a heating device is provided in connection with the dryer device for heating the air .
  • heated replacement air is used for drying the pulp web in connection with the dryer device, e.g. a fan dryer.
  • the dryer section preferably includes several dryer devices provided one on top of the other to form a drying cabinet.
  • the dryer section preferably includes more than one drying cabinet, the drying cabinets being provided side by side. Intermediate spaces are provided between the drying cabinets.
  • the intermediate space may act as a so-called suction chamber.
  • the pulp web is conveyed from the start of the dryer section to the end of the dryer section through several blowing levels from the top to the bottom in the dryer section in such a way as to first convey the pulp web in the direction of the topmost row, i.e. a dryer level, through the different drying cabinets, and then back in the direction of the next row, i.e. a dryer level, through the drying cabinets and so forth to the end of the dryer sec- tion.
  • the dryer section starts at the so-called wet end.
  • one or more cooling rows are provided after the actual dryer section.
  • replace- ment air is circulated inside the dryer section.
  • the apparatus includes at least one circulation air fan for circulating replacement air inside the dryer section.
  • the circulation air fan is part of the dryer device blowing heated replacement air to the pulp web for drying it.
  • the circulation air fan is part of the replacement air distribution means.
  • the circulation air fan preferably produces a force for circulating heated air in the dryer section and blowing air against the pulp web.
  • the circulation of air provides better evaporation efficiency at the dryer section.
  • the topmost circulation air fan or fans of the dryer section_ are provided as a compartment, and replacement air is fed and/or distributed to that compartment.
  • the fan of the topmost level is separated from the fan of a lower level by compartmentation, e.g. by installing a spacer plate or by other suitable manner.
  • the replacement air brought to the topmost level is not mixed with the lower levels.
  • the replacement air distribution means used may be any devices known per se in the art, e.g. distributing channels, manifold devices, air fans, other suitable fans, and their different combinations .
  • the exhaust air device used may be any devices known per se in the art, e.g. an exhaust air device, suction device, other suitable device for removing air and their different combinations.
  • the exhaust air device used is an exhaust air fan.
  • exhaust air can be removed via the openings or hatches of the ceiling in the dryer section.
  • the ratio of exhaust air and replacement air is adjusted. Preferably, the overall balance must tally. In one embodiment the flow of exhaust air is adjusted. In one embodiment the flow of replacement air is adjusted.
  • the ex- haust air is conducted to heat recovery, e.g. to a heat exchanger, after the exhaust air has been conducted out from the dryer section.
  • a heat recovery device is substantially provided in connection with the dryer section.
  • the exhaust air to be conducted to the heat recovery is in this arrangement air that is damper than normally, whereby operation of the heat recovery is enhanced.
  • the exhaust air is conducted to a fan.
  • the exhaust air can be conducted via the heat recovery or circulated in a suitable manner, e.g. in connection with the manufacture of pulp, or alternatively conducted out.
  • At least one exhaust air flow conducted out from the dryer section is conducted, by means of a fan, to be used as part of the air system in the manufacture of pulp.
  • air system is meant, at the simplest, the feeding of an air flow into the dryer section and providing of an exhaust air flow out from the dryer section.
  • the air system preferably includes more than one air flow and air circulation to be used in the manufacture of pulp.
  • the air circulation described in this invention is part of the air system in the manufacture of pulp.
  • the replacement air of this invention to be fed in does not include circulated exhaust air.
  • the invention can be used and utilized in connection with diverse drying solutions in the manu- facture of pulp, preferably in connection with airborne drying.
  • the dryer devices and other devices used can be any devices known per se as different embodiments .
  • the method and apparatus according to the invention provide optimal process conditions in the drying.
  • moisture can be removed in areas where it is being developed.
  • the air flows can be targeted in a more accurate manner, whereby the drying can be enhanced.
  • condensation of the evaporated moisture back to the web can be prevented in the dryer section by means of the invention.
  • the temperature of the web can be maintained at a lower level than in the conventional pulp web drying systems. This way, better efficiency is provided for the drying and energy consumption can be reduced, whereby the energy efficiency of the drying increases.
  • the invention provides an industrially applicable and easy-to-use method and apparatus suitable for many purposes of use for enhancing the drying. By virtue of the invention it is possible to reduce the utilization and investment costs in connection with the drying. In addition, by means of the invention it is possible to improve the technique currently used in the drying of a pulp web. LIST OF FIGURES
  • Fig. 1 illustrates one apparatus according to the invention as a simplified schematic illustration
  • Fig. 2 illustrates a corresponding apparatus known from the prior art
  • Fig. 3 illustrates another apparatus according to the invention as a simplified schematic illustration.
  • Fig. 1 and 3 illustrate an apparatus accord- ing to the invention provided in connection with a pulp web dryer section.
  • the dryer section includes fan dryers used as dryer devices 3 and means for conducting a pulp web through more than one fan dryer to blow heated air against the web from both sides of the web to provide removal of moisture by evaporation.
  • the fan dryers are provided one above the other in a tower- type configuration to constitute a dryer assembly.
  • the fan dryers known per se can be used as the fan dryers.
  • the dryer assembly is encapsulated to constitute a dryer cabinet 12.
  • the dryer section includes several dryer assemblies. The dryer assemblies are provided side by side for constituting the dryer section, and a so-called intermediate space 13 is provided between each two dryer assemblies.
  • the pulp web is arranged to pass in the horizontal direction through several blowing levels from the start 10 of the dryer section, first at a first level via the dryer devices of the different dryer assemblies, and then the pulp web is turned by means of a turner roll to pass at a second level via the dryer devices of the different dryer as- semblies and so forth, until the end 11 of the dryer section is reached.
  • the apparatus includes at least one exhaust air fan 16 for sucking out exhaust air 2 including the moisture removed from the pulp web, substantially in the high evaporation area 5 in the dryer section and at the first end 7 of the dryer section. Furthermore, the apparatus includes feeding means for feeding replacement air 1 to the dryer section to replace the exhaust air 2 that has been removed, and distribution means 14 and 15, e.g. manifolds, for distributing the replacement air 1 fed to the tail end 6 of the dryer section and/or substantially to the high evaporation and rising evaporation areas 4 of the dryer section.
  • the exhaust air 2 is sucked away from the first end 7 of the dryer section and from the intermediate space 13 between the dryer cabinets in the high evaporation area 5. At least part of the suction means can be provided on the doors of the intermediate, spaces 13 between the drying cabinets 12. The moisture rises high in the intermediate spaces between the cabinets .
  • the replacement air 1 is fed to the tail end 6 of the dryer ⁇ section and/or to the intermediate spaces 13 between the dryer cabinets in the rising evaporation 4 and high evaporation areas by means of a replacement air fan (not shown in the figure) .
  • First replacement air feeding and distribution means 15 are provided under the dryer section.
  • Second replacement air feeding and distribution means 14 are provided on the doors of the intermediate spaces 13 between the dryer cabinets 12.
  • Each distribution mean e.g. manifolds, distributes the replacement air to predeter- mined areas of the dryer section with a suitable flow.
  • the apparatus includes circulation air fans provided in connection with the dryer devices 3 for circulating the replacement air heated in the dryer devices inside the dryer section to enhance drying.
  • the apparatus according to the invention may include a heat exchanger (not shown in the figure) as a heat recovery device provided substantially in connection with the dryer section.
  • the exhaust air 2 can be conducted to the heat exchanger after having been conducted out from the dryer section.
  • the apparatuses presented in Fig. 1 and 3 differ from each other in that, in the apparatus of Fig. 3, the topmost row of the circulation air fans is compartmented into compartments 17, such as circulation air fan chambers, by means of a spacer plate, and replacement air 1 can be fed to these compartments 17 by means of the distribution means 14. This way, the air to be fed is not mixed with the air of the lower rows.
  • the replacement air 1 can be fed in such a way as to conduct it directly to the topmost circulation air fan, whereby the circulation air fan acts at the same time as a replacement air fan. In this solution, ' replacement air 1 can either be conducted to the cir- culation air fan compartment 17 or to the intermediate space 13 or both.
  • Fig. 1 and 3 can be utilized for drying pulp webs.
  • Fig. 2 shows a prior art apparatus, basically corresponding to the apparatus of Fig. 1 and 3 in other respects except for the feeding of replacement air 1 and the removal of exhaust air 2.
  • the exhaust air 2 is sucked away from the first end of the dryer section.
  • the replacement air 1 is fed to the tail end of the dryer section.
  • the method and apparatus according to the invention are suitable as different embodiments to be used in connection with the drying of the most different pulp webs .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Paper (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

.The invention relates to a method and apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, wherein a pulp web is conducted in the dryer section through more than one dryer device (3) and warm air is blown against the web to provide removal of moisture by evaporation, and the moisture removed from the pulp web is conducted out from the dryer section with exhaust air (2) and replacement air (1) is fed to the dryer section to replace the exhaust air (2) that has been removed. According to the invention, the exhaust air (2) including the moisture removed from the pulp web is sucked out from the dryer section, substantially from the high evaporation area (5) and from the first end (7) of the dryer section, and replacement air (1) is fed to the tail end (6) of the dryer section.

Description

METHOD AND APPARATUS FOR INCREASING DRYING EFFICIENCY AND ENERGY EFFICIENCY IN CONNECTION WITH THE DRYER SECTION IN THE MANUFACTURE OF PULP FIELD OF THE INVENTION
The invention relates to a method as defined in the preamble of claim 1 and to an apparatus as defined in the preamble of claim 8 for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp.
BACKGROUND OF THE INVENTION
Known from the prior art in the field of manufacturing pulp are different methods and apparatuses to be used for drying the pulp web.
It is known to dry the pulp web in a dryer section e.g. by cylinder drying, fan drying and/or airborne drying. In the dryer section, water is evaporated from the pulp web. The evaporation requires con- duction of heat to the pulp web and conduction of the resulting water vapor away with the ventilation air, i.e. exhaust air.
In fan and airborne drying the pulp web is dried by means of several dryer devices without con- tact to the web. The dryer device used may be e.g. a warm air blowing device, such as a blow box. Usually the dryer devices are arranged into an assembly to constitute a dryer assembly. In addition, providing encapsulation around the dryer assembly is known. The dryer section conventionally includes several dryer assemblies. A single dryer assembly includes several dryer devices. The pulp web is conducted through the different dryer assemblies. Warm air is blown against the pulp web from at least one side, preferably from both sides. The function of the dryer section is to remove water and moisture from the pulp web. The problem in many dryer sections in the manufacture of pulp is that the moisture removed from the pulp web is condensed back to the web, especially if the amount of water accumulating in the air rises to a very high level. This causes decrease in the en¬ ergy economy of drying.
OBJECTIVE OF THE INVENTION
The objective of the invention is to dis- close a new type of method and apparatus for increasing drying efficiency and energy efficiency in connec¬ tion with the manufacture of pulp and particularly in connection with the dryer section thereof. SUMMARY OF THE INVENTION
The method and apparatus according to the in¬ vention are characterized by what has been presented in the claims.
The invention is based on a method for in- creasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, wherein the pulp web is conducted in the dry¬ er section through more than one dryer device and warm air. is blown against the web by means of the dryer de- vice to provide removal of moisture by evaporation, and the moisture removed from the pulp web is conducted out from the dryer section with the exhaust air and replacement air is fed to the dryer section to replace the exhaust air that has been removed, in a preferred embodiment in an amount equal to the amount of the exhaust air. According to the invention the exhaust air including the moisture removed from the pulp web is sucked out from the dryer section, substantially from the high evaporation area and from the first, end of the dryer section, e.g. from the top part of the dryer section, and replacement air is fed to the tail end of the dryer section, e.g. to . the bottom part of the dryer section.
In addition, the invention is based on an apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, the dryer section including dryer devices and means, e.g. a drawing roll, conveyor line or the like, for conducting the pulp web through more than one dryer device to blow warm air against the web to provide removal of moisture by evaporation, and the apparatus includes removing means for conducting the exhaust air including the moisture removed from the pulp web out from the dryer section and feeding means for feeding replacement air to the dryer section to replace the exhaust air that has been removed. According to the invention the apparatus includes at least one exhaust air device for sucking the exhaust air including the moisture removed from the pulp web out from the dryer section substantially in the high evap- oration area and at the first end of the dryer section, and distribution means for distributing replacement air to be fed to the tail end of the dryer section.
The invention is specifically based on in- creasing the drying efficiency and energy efficiency in connection with the drying of the pulp web. The basic idea of the invention is to modify the existing devices so as to remove moisture in areas where it is being developed. Preferably, dry air is provided as the replacement. To provide efficient evaporation, a predetermined ΔΤ must exist between the temperatures of the pulp web and the blow from the dryer device. The invention preferably acts on the external balance of the dryer section.
In one embodiment of the invention, replacement air is fed to the tail end of the dryer section, e.g. to the bottom part of the dryer section, and substantially to the high evaporation and/or rising evaporation area of the dryer section. In one embodiment the top part of the dryer section or part of the top part of the dryer section is compartmented to form a compartment and replacement air is fed to that compartment. Preferably, replacement air is conducted over and/or in front of the exhaust air suction area in the direction of movement of the pulp web to re- place the removed exhaust air.
In one embodiment of the invention the apparatus includes distribution means for distributing the replacement air to be fed to the tail end of the dryer section and substantially to the high evaporation and/or rising evaporation area of the dryer section.
In one embodiment, replacement air is fed to the start of the dryer section, in one preferred embodiment close to the area where the pulp web is conducted into the dryer section. This way, condensation and droplet formation of moisture on the surface of the web and/or the structures of the dryer section or inside the web is prevented. In one embodiment the apparatus includes means for con-ducting the replacement air to the start of the dryer section.
In this connection, by replacement air is meant an air flow fed to the dryer section to replace exhaust air and to be used in drying of the pulp web. The replacement air circulates as circulation air in the dryer section and becomes exhaust air, including the moisture removed from the pulp web. In this invention, replacement air is fed to the tail end of the dryer section and in some preferred embodiments additionally to the high evaporation and/or rising evaporation areas. As replacement air, it is possible to use air from any air system or circulation system in the manufacture of pulp that is suitable for the pur¬ pose of use. Alternatively, fresh air can be used.
In this connection, by exhaust air is meant the air that conveys away water and moisture evapo- rated from the web, in this invention from the high evaporation area and from the first end of the dryer section. The water evaporated from the pulp web has accumulated into the exhaust air.
The pulp web is heated in the rising evapora- tion area. In this area, moisture is conventionally not able to accumulate. Most of the evaporation occurs in the high evaporation area.
By first end of the dryer section is meant the first part of the dryer section in the direction movement of the pulp web. In addition, the first end of the dryer section may refer to the top part and/or to the front part of the dryer section over and/or in front of the first dryer device or devices.
By tail end of the dryer section is meant the tail part of the dryer section in the direction of movement of the pulp web. In addition, the tail end of the dryer section may refer to the bottom part or the latter part of the dryer section under and/or after the last dryer device or devices.
In this connection, by web is meant any fiber-based pulp web or other type of web-like structure in the manufacture of pulp, such as a sheet, board, wet web or the like.
In this connection, by pulp is meant any fi- ber-based product. The pulp may be formed by a chemical method, mechanical method, chemi-mechanical method or other pulp manufacturing method known per se. The pulp may be formed from fibers, such as wood or plant fibers, recycled pulp, other botanical pulp or other suitable raw material or the like or combinations thereof. The pulp may contain suitable additives. In one embodiment the dryer section is based on airborne drying. In this case, the drying takes place without a direct contact surface between the pulp web and the dryer device. In airborne drying, moisture is evaporated throughout the entire travel.
In one embodiment of the invention a fan dry- , er is used as the dryer device. In one embodiment at least one dryer device is a fan dryer. The pulp web can be dried by a fan dryer without direct contact to the web. Warm blowing air with the temperature preferably in the constant region is blown to the surface of the pulp web by means of the fan dryer.
In one embodiment, warm air is blown against the pulp web from both sides of the web.
In one embodiment a heating device is provided in connection with the dryer device for heating the air .
In one preferred embodiment, heated replacement air is used for drying the pulp web in connection with the dryer device, e.g. a fan dryer.
In one embodiment the dryer section preferably includes several dryer devices provided one on top of the other to form a drying cabinet. The dryer section preferably includes more than one drying cabinet, the drying cabinets being provided side by side. Intermediate spaces are provided between the drying cabinets. The intermediate space may act as a so-called suction chamber. Preferably the pulp web is conveyed from the start of the dryer section to the end of the dryer section through several blowing levels from the top to the bottom in the dryer section in such a way as to first convey the pulp web in the direction of the topmost row, i.e. a dryer level, through the different drying cabinets, and then back in the direction of the next row, i.e. a dryer level, through the drying cabinets and so forth to the end of the dryer sec- tion. The dryer section starts at the so-called wet end. In one embodiment, one or more cooling rows are provided after the actual dryer section.
In one embodiment of the invention, replace- ment air is circulated inside the dryer section. In one embodiment the apparatus includes at least one circulation air fan for circulating replacement air inside the dryer section. In one embodiment the circulation air fan is part of the dryer device blowing heated replacement air to the pulp web for drying it. In one embodiment the circulation air fan is part of the replacement air distribution means. The circulation air fan preferably produces a force for circulating heated air in the dryer section and blowing air against the pulp web. In addition, the circulation of air provides better evaporation efficiency at the dryer section.
In one embodiment the topmost circulation air fan or fans of the dryer section_ are provided as a compartment, and replacement air is fed and/or distributed to that compartment. Preferably the fan of the topmost level is separated from the fan of a lower level by compartmentation, e.g. by installing a spacer plate or by other suitable manner. In this case, the replacement air brought to the topmost level is not mixed with the lower levels.
Preferably the replacement air distribution means used may be any devices known per se in the art, e.g. distributing channels, manifold devices, air fans, other suitable fans, and their different combinations .
Preferably the exhaust air device used may be any devices known per se in the art, e.g. an exhaust air device, suction device, other suitable device for removing air and their different combinations. In one embodiment the exhaust air device used is an exhaust air fan. In one embodiment, exhaust air can be removed via the openings or hatches of the ceiling in the dryer section.
In one embodiment the ratio of exhaust air and replacement air is adjusted. Preferably, the overall balance must tally. In one embodiment the flow of exhaust air is adjusted. In one embodiment the flow of replacement air is adjusted.
In one embodiment of the invention the ex- haust air is conducted to heat recovery, e.g. to a heat exchanger, after the exhaust air has been conducted out from the dryer section. In one embodiment a heat recovery device is substantially provided in connection with the dryer section. Preferably the exhaust air to be conducted to the heat recovery is in this arrangement air that is damper than normally, whereby operation of the heat recovery is enhanced.
In one embodiment the exhaust air is conducted to a fan.
The exhaust air can be conducted via the heat recovery or circulated in a suitable manner, e.g. in connection with the manufacture of pulp, or alternatively conducted out.
In one embodiment of the invention, at least one exhaust air flow conducted out from the dryer section is conducted, by means of a fan, to be used as part of the air system in the manufacture of pulp.
In this connection, by air system is meant, at the simplest, the feeding of an air flow into the dryer section and providing of an exhaust air flow out from the dryer section. The air system preferably includes more than one air flow and air circulation to be used in the manufacture of pulp. Preferably the air circulation described in this invention is part of the air system in the manufacture of pulp. Preferably the replacement air of this invention to be fed in does not include circulated exhaust air.
The invention can be used and utilized in connection with diverse drying solutions in the manu- facture of pulp, preferably in connection with airborne drying. The dryer devices and other devices used can be any devices known per se as different embodiments .
The method and apparatus according to the in- vention provide considerable advantages as corn-pared to the prior art.
The method and apparatus according to the invention provide optimal process conditions in the drying. In the method and apparatus according to the in- vention, moisture can be removed in areas where it is being developed. By means of the invention, the air flows can be targeted in a more accurate manner, whereby the drying can be enhanced. In addition, condensation of the evaporated moisture back to the web can be prevented in the dryer section by means of the invention.
By the arrangement according to the invention, the temperature of the web can be maintained at a lower level than in the conventional pulp web drying systems. This way, better efficiency is provided for the drying and energy consumption can be reduced, whereby the energy efficiency of the drying increases.
The invention provides an industrially applicable and easy-to-use method and apparatus suitable for many purposes of use for enhancing the drying. By virtue of the invention it is possible to reduce the utilization and investment costs in connection with the drying. In addition, by means of the invention it is possible to improve the technique currently used in the drying of a pulp web. LIST OF FIGURES
Fig. 1 illustrates one apparatus according to the invention as a simplified schematic illustration,
Fig. 2 illustrates a corresponding apparatus known from the prior art, and
Fig. 3 illustrates another apparatus according to the invention as a simplified schematic illustration. DETAILED DESCRIPTION OF THE INVENTION
In the following section the invention will be described by means of a detailed exemplary embodiment with reference to the accompanying Fig. 1 and 3.
Fig. 1 and 3 illustrate an apparatus accord- ing to the invention provided in connection with a pulp web dryer section. The dryer section includes fan dryers used as dryer devices 3 and means for conducting a pulp web through more than one fan dryer to blow heated air against the web from both sides of the web to provide removal of moisture by evaporation. The fan dryers are provided one above the other in a tower- type configuration to constitute a dryer assembly. The fan dryers known per se can be used as the fan dryers. The dryer assembly is encapsulated to constitute a dryer cabinet 12. The dryer section includes several dryer assemblies. The dryer assemblies are provided side by side for constituting the dryer section, and a so-called intermediate space 13 is provided between each two dryer assemblies. The pulp web is arranged to pass in the horizontal direction through several blowing levels from the start 10 of the dryer section, first at a first level via the dryer devices of the different dryer assemblies, and then the pulp web is turned by means of a turner roll to pass at a second level via the dryer devices of the different dryer as- semblies and so forth, until the end 11 of the dryer section is reached.
The apparatus according to the invention includes at least one exhaust air fan 16 for sucking out exhaust air 2 including the moisture removed from the pulp web, substantially in the high evaporation area 5 in the dryer section and at the first end 7 of the dryer section. Furthermore, the apparatus includes feeding means for feeding replacement air 1 to the dryer section to replace the exhaust air 2 that has been removed, and distribution means 14 and 15, e.g. manifolds, for distributing the replacement air 1 fed to the tail end 6 of the dryer section and/or substantially to the high evaporation and rising evaporation areas 4 of the dryer section.
The exhaust air 2 is sucked away from the first end 7 of the dryer section and from the intermediate space 13 between the dryer cabinets in the high evaporation area 5. At least part of the suction means can be provided on the doors of the intermediate, spaces 13 between the drying cabinets 12. The moisture rises high in the intermediate spaces between the cabinets .
The replacement air 1 is fed to the tail end 6 of the dryer ■ section and/or to the intermediate spaces 13 between the dryer cabinets in the rising evaporation 4 and high evaporation areas by means of a replacement air fan (not shown in the figure) . First replacement air feeding and distribution means 15 are provided under the dryer section. Second replacement air feeding and distribution means 14 are provided on the doors of the intermediate spaces 13 between the dryer cabinets 12. Each distribution mean, e.g. manifolds, distributes the replacement air to predeter- mined areas of the dryer section with a suitable flow. The apparatus includes circulation air fans provided in connection with the dryer devices 3 for circulating the replacement air heated in the dryer devices inside the dryer section to enhance drying.
In addition, the apparatus according to the invention may include a heat exchanger (not shown in the figure) as a heat recovery device provided substantially in connection with the dryer section. The exhaust air 2 can be conducted to the heat exchanger after having been conducted out from the dryer section.
The apparatuses presented in Fig. 1 and 3 differ from each other in that, in the apparatus of Fig. 3, the topmost row of the circulation air fans is compartmented into compartments 17, such as circulation air fan chambers, by means of a spacer plate, and replacement air 1 can be fed to these compartments 17 by means of the distribution means 14. This way, the air to be fed is not mixed with the air of the lower rows. The replacement air 1 can be fed in such a way as to conduct it directly to the topmost circulation air fan, whereby the circulation air fan acts at the same time as a replacement air fan. In this solution,' replacement air 1 can either be conducted to the cir- culation air fan compartment 17 or to the intermediate space 13 or both.
The device components known per se can be used in the apparatuses of Fig. 1 and 3, and these device components are not described in this connection in any more detail.
The apparatus according to Fig. 1 and 3 can be utilized for drying pulp webs. By the apparatus according to the invention, it is possible considerably to raise the pulp web drying efficiency as well as en- ergy efficiency in connection with drying. In comparison, Fig. 2 shows a prior art apparatus, basically corresponding to the apparatus of Fig. 1 and 3 in other respects except for the feeding of replacement air 1 and the removal of exhaust air 2. The exhaust air 2 is sucked away from the first end of the dryer section. The replacement air 1 is fed to the tail end of the dryer section.
The method and apparatus according to the invention are suitable as different embodiments to be used in connection with the drying of the most different pulp webs .
The invention is not limited merely to the example referred to above; instead, many variations are possible within the scope of the inventive idea defined by the claims.

Claims

1. A method for increasing drying efficiency and energy efficiency in connection with the .dryer section in the manufacture of pulp, wherein a pulp web is conducted in the dryer section through more than one dryer device (3) and warm air is blown against the web to provide removal of moisture by evaporation, and the moisture removed from the pulp web is conducted out from the dryer section with exhaust air (2) and replacement air (1) is fed to the dryer section to replace the exhaust air (2) that has been removed, cha ract e r i z ed in that the exhaust air (2) including the moisture removed from the pulp web is sucked out from the dryer section, substantially from the high evaporation area (5) and from the first end (7) of the dryer section, and replacement air (1) is fed to the tail end (6) of the dryer section.
2. The method according to claim 1, cha ract er i z ed in that replacement air (1) is fed to the tail end (6) of the dryer section and substantially to the high evaporation and/or rising evaporation area (4) in the dryer section.
3. The method according to claim 1 or 2, chara ct e r i z ed in that replacement air (1) is circulated inside the dryer section.
4. The method according to any one of claims 1 to 3, charact e r i z ed in that a fan dryer is used as the dryer device (3) .
5. The method according to any one of claims l to 4, charact e r i z ed in that the exhaust air
(2) is. conducted to heat recovery after it has been conducted out from the dryer section.
6. The method according to any one of claims 1 to 5, cha ra ct. e r i z e d in that at least one exhaust air flow (2) conducted out from the dryer sec- tion is conducted by means of the fan to be used as part of the air system in the manufacture of pulp.
7. An apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp, the dryer section including dryer devices (3) and means for conducting the pulp web through more than one dryer device to blow warm air against the web to provide removal of moisture by evaporation, and the apparatus includes removing means for conducting the exhaust air (2) including the moisture removed from the pulp web out from the dryer section and feeding means for feeding replacement air (1) to the dryer section to replace the exhaust air (2) that has been removed, charact e r i z e d in that the apparatus includes at least one exhaust air device (16) for sucking the exhaust air (2) including the moisture removed from the pulp web out from the dryer section, substantially in the high evaporation area (5) and at the first end (7) of the dryer section, and distribution means (15) for distributing replacement air (1) to be fed to the tail end (6) of the dryer section.
8. The apparatus according to claim 7, charac t e r i z ed in that the apparatus includes distribution means (14,15) for distributing the replacement air (1) to be fed to the tail end (6) of the dryer section and substantially to the high evaporation and/or rising evaporation area (4) in the dryer section .
9. The apparatus according to claim 7 or 8, charact e r i z e d in that the dryer device (3) is a fan dryer.
10. The apparatus according to any one of claims 7 to 9, charac t e ri z ed in that the ap- paratus includes at least one circulation air fan for circulating the replacement air (1) inside the dryer section .
11. The apparatus according to any one of claims 7 to 10, charac t e r i z ed in that the ap- paratus includes a heat recovery device to which the exhaust air (2) can be conducted after it has been conducted out from the dryer section.
12. The apparatus according to claim 11, chara ct e r i z ed in that the heat recovery de- vice is a heat exchanger.
PCT/FI2012/050714 2011-07-06 2012-07-06 Method and apparatus for increasing drying efficiency and energy efficiency in connection with the dryer section in the manufacture of pulp WO2013004915A1 (en)

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FI20115718A FI124793B (en) 2011-07-06 2011-07-06 Method and apparatus for increasing drying efficiency and energy efficiency in connection with the drying section of pulp manufacture

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106012645A (en) * 2016-07-31 2016-10-12 王自强 Drying part for papermaking dryer
CN110565429A (en) * 2019-08-31 2019-12-13 曹立伟 papermaking drying device with air hood

Citations (3)

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Publication number Priority date Publication date Assignee Title
US3228114A (en) * 1962-11-14 1966-01-11 Hupp Corp Multiple run drier
EP0561256A1 (en) * 1992-03-19 1993-09-22 Valmet Paper Machinery Inc. Method in contact-free air-drying of a material web as well as a nozzle-blow-box and a pulp dryer that make use of the method
WO2002050370A1 (en) * 2000-11-29 2002-06-27 Metso Paper, Inc. Method and equipment for drying a pulp web using hot air of different temperatures

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3228114A (en) * 1962-11-14 1966-01-11 Hupp Corp Multiple run drier
EP0561256A1 (en) * 1992-03-19 1993-09-22 Valmet Paper Machinery Inc. Method in contact-free air-drying of a material web as well as a nozzle-blow-box and a pulp dryer that make use of the method
WO2002050370A1 (en) * 2000-11-29 2002-06-27 Metso Paper, Inc. Method and equipment for drying a pulp web using hot air of different temperatures

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106012645A (en) * 2016-07-31 2016-10-12 王自强 Drying part for papermaking dryer
CN110565429A (en) * 2019-08-31 2019-12-13 曹立伟 papermaking drying device with air hood
CN110565429B (en) * 2019-08-31 2021-06-04 维达护理用品(广东)有限公司 Papermaking drying device with air hood

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FI20115718A0 (en) 2011-07-06
FI124793B (en) 2015-01-30

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