EP0653514B1 - Verfahren und Vorrichtung zur Trocknung von bahnförmigem Material - Google Patents

Verfahren und Vorrichtung zur Trocknung von bahnförmigem Material Download PDF

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Publication number
EP0653514B1
EP0653514B1 EP19940308397 EP94308397A EP0653514B1 EP 0653514 B1 EP0653514 B1 EP 0653514B1 EP 19940308397 EP19940308397 EP 19940308397 EP 94308397 A EP94308397 A EP 94308397A EP 0653514 B1 EP0653514 B1 EP 0653514B1
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EP
European Patent Office
Prior art keywords
dryer
sheet material
drying
fabric
suction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19940308397
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English (en)
French (fr)
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EP0653514A3 (de
EP0653514A2 (de
Inventor
Morimasa Hanaya
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Tokushu Paper Manufacturing Co Ltd
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Tokushu Paper Manufacturing Co Ltd
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Filing date
Publication date
Priority claimed from JP6147060A external-priority patent/JP3007529B2/ja
Priority claimed from JP27850894A external-priority patent/JP2907266B2/ja
Priority claimed from JP27847394A external-priority patent/JP2907265B2/ja
Priority claimed from JP6287469A external-priority patent/JP3007542B2/ja
Application filed by Tokushu Paper Manufacturing Co Ltd filed Critical Tokushu Paper Manufacturing Co Ltd
Publication of EP0653514A2 publication Critical patent/EP0653514A2/de
Publication of EP0653514A3 publication Critical patent/EP0653514A3/de
Application granted granted Critical
Publication of EP0653514B1 publication Critical patent/EP0653514B1/de
Anticipated expiration legal-status Critical
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    • 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
    • D21F5/02—Drying on cylinders
    • D21F5/04—Drying on cylinders on two or more drying cylinders
    • D21F5/042—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices
    • 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
    • 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
    • D21F5/02—Drying on cylinders
    • D21F5/04—Drying on cylinders on two or more drying cylinders
    • D21F5/042—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices
    • D21F5/044—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices using air hoods over the cylinders

Definitions

  • the present invention relates in general to a novel process and apparatus for drying sheet materials, such as paper and some of wet process-nonwoven fabric, which are susceptible to breakage in the wet conditions as opposed to woven fabric, and which are subjected to intra-fibre contraction due to the formation of inter-fibre hydro-bonding caused by vaporization of moisture during drying process.
  • a typical method for drying a paper web on a paper-making machine generally involves steam-heated dryer cylinders.
  • a closed dryer hood insulated by suitable insulating materials is installed so as to surround dryer cylinders in series.
  • a large volume of high temperature, low humidity air (heated with exhaust steam and fresh stream) is blown into the dryer hood, and the moisture released from the paper web is removed in a moving air stream kept at no greater than 70-80% saturation curve to prevent condensation inside the hood.
  • the technique is energy-intensive because of the blowers needed to handle a large amount of process air, and is wasteful of energy also because the moisture-laden air is largely exhausted to the atmosphere except for a minor use as reheating of fresh air supply.
  • Another technique developed in recent years involves the use of two heated and cooled endless steel belts holding a wet paper web therebetween.
  • the moisture vaporized by the heated belt is immediately condensed on the cooled belt, and the condensate is drained onto an endless fabric belt.
  • the wet paper web is dried at a temperature in excess of 100°C while restraining the expansion/contraction thereof.
  • the paper dried by this technique is of high quality, but the technique requires a large quantity of cooling water, which can only be recycled as warm water. Therefore, the process economy is quite inferior.
  • a wet web of paper is dried on a single large-diameter dryer cylinder, called a Yankee dryer, which has a canopy hood disposed so as to surround a top half portion of the cylinder.
  • Fresh air and recycled moisture-laden air are heated to a high-temperature gas at about 300-450°C, and are blown towards the exposed side of the wet paper web at a high speed of 70-120 m/s.
  • the product has a Yankee glazed surface on one side only, and the other side remains rough. The use of manufactured product is therefore limited somewhat to such uses as a wrapping paper with one glazed side and a tissue paper.
  • Yet another drying technique proposed is based on not supplying air to the closed hood but recycling the saturated steam produced by vaporized moisture as a part of the heat supplied to drier cylinders, which are pressurized vessels.
  • Another problem of air entry into the hood occurs when the paper inside the hood breaks due to shrinkage, and it is necessary to open the closed hood. After the interior of the hood has been cleared of brokes, the hood is closed and is re-started. Under these circumstances, it is impossible to keep air entry into the hood below 4% as is generally recommended.
  • the saturated steam inside the hood becomes condensed when cooled by the wet paper load as well as external air entering the hood. Then, condensation occurs on the metal surfaces of the hood and dryer frames, and the condensates may drip onto the dried paper creating staining defects and low yield. Because of such inherent problems, this proposed technique has not been commercialized yet.
  • US-A-4,242,808 discloses a paper web drying system and process in which the paper web contacts directly superheated steam.
  • a direct contact dryer is used for porous grade paper and an impingement dryer is used for denser grade paper, the paper not being restrained during passage through the direct contact dryer.
  • US-A-4,064,637 discloses a cylindrical dryer for drying wet paper in which the paper is supported by a wire in the form of an endless belt.
  • the paper web in US-A-3,576,078 is disposed between open mesh fabric endless belting in passing over dryer drums, and the web is scrubbed by air circulated through the meshes of the fabric belting while moving beneath hoods over the dryer drums.
  • the current effort to dry a wet paper web on a production scale is generally based on causing the wet paper web to pass on dryer cylinders in series, while letting both sides of the wet paper web come into contact alternately with the dryer cylinders so as to produce smooth surfaces on both sides of the paper to avoid curling or cockling. Furthermore, the dimensional stability is provided by interposing the wet paper web between the cylinder and the endless fabric belt so as to restrict the free shrinkage of the wet paper web. However, inasmuch as most of the drying action is performed during a free running zone between the adjacent dryer cylinders, where the paper web shrinkage is not restrained, such attempt is not sufficient.
  • the increased size of the dryer cylinders presents performance problems also.
  • the dryer cylinders have reached a diameter size of 1.2 to 1.5 m and even 2 m, and the cylinder width has also been increased to a size in excess of 10 m.
  • the steam pressure in the dryer cylinders, which are formed of castings, has reached 2-4 kg/m 2 G.
  • problems have emerged that it is difficult to collect the condensate inside the dryer cylinder because the condensate rotates with the interior surface of the dryer cylinder (rimming condition) due to centrifugal force by the increased rotational speeds.
  • With high speeds of operation draining of the condensates does not take place smoothly, and presents a problem of uneven condensate layer resulting in uneven moisture across the paper width.
  • a further important problem associated with the conventional drying process is the dew point of the carrier gaseous stream. So long as moist air is used as the carrier stream for the vaporized steam, the upper limit of dew point is around 65-70°C. When the volume of dry air is low relative to the volume of the vaporized steam to be carried, saturation of the carrier air can occur easily, and condensates are produced inside the closed hood. The condensates dripping on the dried paper will produce rejects, and poor yield will be the result.
  • Another processing problem related to the method of drying is inherent in the conventional drying system. Specifically, the temperature of the side of the wet paper web in contact with the dryer cylinder reaches about near 100°C, but the side contacting the fabric belt can only reach a temperature of about 90°C, because the fabric belt is wetted with the moisture removed from the paper evaporated by the cylinder. Furthermore, because the fabric interior is wetted with moisture, there is a high temperature gradient between the outside layer of the fabric in equilibrium with moist air (65-70°C) -and the inside layer in contact with the paper web (about 85°C), thus greatly impeding rapid evaporation of water from the paper web.
  • the present invention presents a process and apparatus to overcome the problems described above by achieving high rate of moisture removal from wet sheet material resulting in a highly efficient and energy saving drying process.
  • a process for drying a wet sheet material comprising the steps of:
  • the removing step (d) may include recirculating the evaporated steam at least partly to the dryer cylinders to heat the same, or may include heating a part of the recirculated steam to blow against the wet sheet material restrained by the dryer cylinders and the fabric belt.
  • the traveling step (c) may include blowing the drying medium against the wet sheet material restrained by the dryer cylinders and the fabric belt at a high impingement speed.
  • the curved continuous evaporating surface is defined by a plurality of horseshoe-shaped surfaces connected to one another when viewed axially of the dryer cylinders.
  • the traveling step (c) may include passing the wet sheet material over the heated dryer cylinders in series with one side thereof being held in contact with an outer peripheral surface of each dryer cylinder and with the other side thereof being pressed by the fabric belt; or may include passing the wet sheet material between adjacent dryer cylinders using suction fabric rolls, in such a manner that the sheet material passes on the suction fabric roll through the gas permeable fabric belt interposed therebetween; and the removing step (d) may include sucking the steam evaporated from the wet sheet material through the suction fabric rolls.
  • the traveling step (c) may include passing the wet sheet material between adjacent dryer cylinders in such a manner that the sheet material is restrained on the gas permeable fabric belt by suction force.
  • the traveling step (c) may include restraining the wet sheet material, released from one dryer cylinder, on one gas permeable fabric belt passing over the one dryer cylinder; subsequently sandwiching the wet sheet material between the one gas permeable fabric belt and another gas permeable fabric belt passing over the other dryer cylinder; and subsequently keeping the wet sheet material restrained on the above-mentioned another gas permeable fabric belt.
  • the removing step (d) may include sucking the steam evaporated from the wet sheet material through the gas permeable fabric belt.
  • the traveling step (c) may include passing the wet sheet material over the heated dryer cylinders in series while sandwiching the sheet material between a pair of the gas permeable fabric belts.
  • the traveling step (c) may include blowing the drying medium against the wet sheet material sandwiched between the gas permeable fabric belts
  • the removing step (d) may include sucking the steam evaporated from the wet sheet material through the gas permeable fabric belts.
  • the drying medium is the heated moist air
  • the moist air have a dew point close to 100°C at a contacting interface between the outer peripheral surface of the dryer cylinder and the sheet material, and at least 80°C at a position where the sheet material is spaced apart from the dryer cylinder.
  • the heated moist air may preferably be of a dry bulb temperature of at least 150°C containing at least about 50% by volume of superheated steam.
  • an apparatus for drying a wet sheet material comprising:
  • the dryer cylinders may be disposed in a double row arrangement including an upper row of dryer cylinders and a lower row of dryer cylinders, or may be disposed in a single row arrangement including a single row of dryer cylinders.
  • the heat-insulated hood assembly may include an upper hood, a lower hood and a middle hood interposed between the upper hood and the lower hood, at least one of the upper hood, the lower hood and the middle hood being movable between the open position and the closed position.
  • a pair of elevating devices each attached to a respective one of the upper hood and the lower hood, for moving the respective hood towards and away from the dryer cylinders.
  • the transferring device may include a plurality of suction fabric rolls each disposed adjacent to a respective associated one of the dryer cylinders for guiding the sheet material onto or away from the associated dryer cylinder.
  • a pair of the endless gas-permeable fabric belts may be provided, one of the endless gas-permeable fabric belts being looped around an associated one of the dryer cylinders while the other endless gas-permeable fabric belt is looped around the dryer cylinder disposed adjacent to the associated dryer cylinder, the pair of fabric belts substantially extending to an intermediate position between the one dryer cylinder and the other dryer, whereby the pair of fabric belts serve as the transferring device.
  • a pair of the endless gas-permeable fabric belts may be provided to sandwich the sheet material therebetween, the pair of fabric belts being looped around a respective dryer cylinder and extending from a respective dryer cylinder to the dryer cylinder adjacent thereto, whereby the pair of fabric belts serve as the transferring device.
  • the drying medium-circulating device may include a suction device having a plurality of suction ports arranged along the path of the sheet material for sucking the steam evaporated from the sheet material.
  • the drying medium-circulating device may further include a blow device having a plurality of blow outlets arranged along a path of the sheet material for blowing out the drying medium against the sheet material.
  • the drying medium-circulating device may further include a plurality of circulating conduits connected to the suction device for reuse of the recovered steam. The circulating conduits are connected to the blow device, or are further connected to the dryer cylinders to heat the same.
  • an entrance sealing device attached to the heat-insulated hood assembly for admitting the sheet material into the hood assembly in sealing relation thereto, as well as an exit sealing device attached to the hood assembly for exiting the sheet material from the hood assembly in sealing relation thereto.
  • Each of the entrance sealing device and the exit sealing device may include at least two sealing rolls disposed inside and outside the hood assembly, respectively; and a sealing blanket looped around the at least two sealing rolls so as to pass through the hood assembly; a feeding roll disposed in association with one of the sealing rolls to guide the sheet material therebetween; and a sealing member disposed between the feeding roll and the hood assembly and having a pair of convexly arcuate portions held in resilient contact with the feeding roll and the sealing roll associated therewith.
  • the sealing device may further comprise a pair of opposite sealing plates attached to the hood assembly so as to be held in sealing contact with opposite ends of the feeding roll and the sealing roll associated therewith.
  • the drying apparatus may further comprise a plurality of gas supply boxes disposed adjacent to the suction fabric rolls, each gas supply box including a surface facing a part of an outer peripheral surface of a respective suction fabric roll and having a plurality of blow ports formed in the surface for blowing the drying medium towards the respective suction fabric roll.
  • a pair of the suction fabric rolls may be preferably disposed adjacent to a respective dryer cylinder, and the gas supply box is disposed between the pair of suction fabric rolls with the blow ports being directed towards both of the pair of suction fabric rolls.
  • the drying apparatus may further comprise a plurality of blow and suction devices disposed adjacent to a respective suction fabric roll, each of the blow and suction devices including a plurality of gas-blow ports for blowing the drying medium towards the respective suction fabric roll and a plurality of suction ports for sucking the steam evaporated from the sheet material passing on the respective suction fabric roll.
  • the dryer frame assembly which includes a front dryer frame disposed at an operational side of the drying apparatus, may be modified so that the front dryer frame includes a lower frame portion for supporting the lower row of dryer cylinders, an upper frame portion disposed above the lower frame portion for supporting the upper row of dryer cylinders, and an intermediate portion connecting the lower frame portion and the upper frame portion and being shifted from the upper and lower frame portions in a direction away from the cylinders.
  • Figure 1 depicts temperature distribution occurring when superheated steam in excess of 100°C is used to dry a paper web in comparison with that of the conventional paper drying process
  • Figure 2 shows the same diagrammatical representation when employing an atmosphere of a prescribed heated moist air.
  • the results of measurements of the contact interface temperatures of the paper web are shown by S' 1 designating the temperature on the fabric side, S' 2 designating the temperature on the cylinder side, respectively.
  • the fabric temperatures are designated by, F' 1 , F' 2 and F' 3 , at the paper side, in the middle and at the outside of the endless fabric belt. It can be seen that although there is temperature difference of about 5°C from about 110°C to about 105°C, the atmosphere is of superheated steam exceeding 105°C throughout the entire range of drying. The results indicate therefore that the paper web is subjected to high temperatures while being tightly pressed against the dryer cylinder by the high tension force of the endless fabric belt. The pressure at the vaporization surface reaches 1.47 atm which is close to saturation vapor pressure at 110°C, and it can be understood that drying proceeds rapidly under such operating conditions.
  • Zones 1 and 3 there are no stages to correspond with Zones 1 and 3 in the conventional drying process. Almost all the drying occurs while the paper web is being held tightly by the fabric belt against the dryer cylinder as in Zone 2. It is only during the period between the cylinders, leaving one cylinder to reach another cylinder, that the paper web leaves the surface of the dryer cylinder 1. However, the paper web is kept restrained by the fabric belt or the like even during this period, and drying takes place in an atmosphere of superheated steam in excess of 100°C. Therefore, there is effective drying throughout the process.
  • Another feature is that there is no free running Stage 4 in the process of the present invention, and the sheet material is constantly being held by the processing devices, and even if the sheet material is broken, the sheet material can be carried forth through the exit of the closed hood.
  • Still another feature is that it is possible to quickly vaporize a large amount of moisture to dry the sheet material in a super-heated steam atmosphere in excess of 105 °C, because super-heated steam (in excess of about 110 °C) is directed to the sheet material 35 at a high speed through the blast ports 19 and the porous fabric belt 36.
  • This arrangement permits delivery of a large amount of heat rapidly to the sheet material 35 by condensing the super-heated steam in the sheet material 35 to release the latent heat of condensation in the sheet material 35, thereby aiding the process of vaporization.
  • softening points (temperature) of lignin and hemicellulose reduce when they contain water. Specifically, the softening point of dried lignin is 134 to 250°C, whereas that of water saturated lignin is 72°C. Therefore, flexibility of fibres is increased, and dried sheet strength is substantially increased due to the covalent bonding (ether linkage, ester linkage) of the hydroxyl group in cellulose with other substances contained in the wood.
  • the drying atmosphere may be that of a heated moist air of dew point of no less than 80°C, preferably a moist air having a dew point of close to 100°C at a contacting interface between the outer peripheral surface of the dryer cylinder and the sheet material, and at least 80°C at a position where the sheet material is spaced apart from the dryer cylinder.
  • the moist air containing no less than 50% by volume of superheated steam of a temperature of at least about 110°C, preferably of no less than 150°C be employed for the impingement drying.
  • Figure 2 depicts a temperature distribution when drying is effected under such conditions.
  • the results of measurements of the contact interface temperatures of the paper web are shown by S" 1 designating the temperature on the fabric side, S" 2 designating the temperature on the cylinder side, respectively.
  • the fabric temperatures are designated by, F" 1 , F" 2 and F" 3 , at the paper side, in the middle and at the outside of the endless fabric belt. It can be seen that although there is temperature difference of about 2°C from about 101°C to about 103°C, the atmosphere is of at least 50% by volume of superheated steam exceeding 100°C. The results indicate therefore that the paper web is subjected to high temperatures while being tightly pressed against the dryer cylinder by the high tension force of the endless fabric belt. The pressure at the vaporization surface reaches 1.47 atm which is close to saturation steam pressure at 110°C, and it can be understood that drying proceeds rapidly under such operating conditions.
  • Zone 1 there is a temperature difference of about 16°C from 85°C to 87°C in Zone 1" in which the paper web begins to contact the dryer cylinder and the fabric belt.
  • Zone 3 in which the blowing of the heated gas is completed, the temperature ranges from 101°C to 103°C, resulting in the same temperature difference of 16°C.
  • Zone 4" in which the heated gas is blown against the paper web while keeping the paper web restrained by fabric, it is preferable that high temperature gas of no less than 150°C is blown against the both sides of the wet paper web while sucking the steam evaporated from the paper web.
  • a drying apparatus in accordance with a first embodiment of the present invention which is suitably adapted to perform the drying process of the invention, will be first explained with reference to Figures 3 to 5.
  • the drying apparatus includes dryer frames 4 which are supported on foundations 13 via sole plates 14 anchored thereto.
  • each group of cylinders should be placed such that the web entrances/exits of respective groups are directed alternatively upwards or downwards to prevent curling of the paper web.
  • cylinders may be arranged such that a half of cylinders rotate to the left while the remaining half to the right.
  • the two types of arrangement can also be mixed to suit the requirements of the drying facility designed.
  • Disposed adjacent to each dryer cylinder 1 are a pair of suction fabric rolls 8 which are installed on the dryer frames 4 through suitable fabric roll bearings 9.
  • upper canopy hoods 15 made of a conventional insulating panelling material are provided so as to cover those portions of the dryer cylinders 1 in the upper row which are positioned above the plane including the axes of the shafts 2 of the upper row cylinders 1, whereas lower canopy hoods 15 also made of the same insulating panelling material are provided so as to cover those portions of the dryer cylinders 1 in the lower row which are situated below the plane including the axes of the shafts 2 of the lower row cylinders 1.
  • Each canopy hood 15 is attached to the dryer frames 4 for vertical movement, and an elevating device, comprised of one or more drive cylinder units mounted on the dryer frames 4 are operably connected to a respective canopy hood 15 to raise or lower the same.
  • each of the dryer cylinders 1 is provided at a driving side thereof with a rotary joint 5 having a vapor injection port and a condensate drain port, and the vapor injection port is connected to a pressurized steam pipe 30, whereas the drain port is connected to a drain pipe 6.
  • a middle hood 17 Disposed between the upper and lower canopy hoods 15 are a middle hood 17 made of a similar insulation panelling material and an opening device 18 comprised of an openable door attached to the middle hood 17 for accessing the interior of the middle hood for inspection/cleaning purposes.
  • the upper and lower canopy hoods 15 and the middle hood 17 are arranged so as to cooperate with one another to define a closed drying chamber therein with the exception of the entry and exit openings formed through the middle hood 17 for entering/exiting of the paper web 35 (sheet material).
  • a blast unit comprised of a plurality of elongated tubular members of a rectangular-shaped cross-section arranged around the cylinder 1 in circumferentially spaced relation, and each having a great number of blast or blow ports 19 formed in the surface opposed to the dryer cylinder 1.
  • suction units each of which comprises a plurality of elongated suction ports 22 defined by the spacings between adjacent blast ports 19.
  • the blast ports 19 and the suction ports 22 may be of either slit or circle shape, and it is preferable that the spacing between the blast ports and the cylinder be about 10-25 mm.
  • the blast units and the suction units are connected separately to the suitable canopy hoods 15 and middle hood 17.
  • a plurality of connecting ducts 21 are connected to the supply boxes 20, and are connected at the driving side of the dryer to drying medium-supply ducts 27 through suitable flexible joints.
  • the interfaces where the dryer cylinders 1 and the suction fabric rolls 8 come into contact with the canopy hoods 15 and the middle hood 17 are made as a labyrinth structure so as to prevent the outside air from entering the closed hood or to prevent a large volume of the vaporized steam from escaping to the outside.
  • a variation of the first embodiment is to have fixed canopy hoods 15 and the drying medium-supply boxes 20, the blast ports 19 and the suction ports 22 are provided on base frames which are disposed inside the hoods so as to be adjacent to the operational and drive sides of the dryer. Suitable bridging frame members are secured to the base frames so as to extend out through the hoods, so that the bridging frame members can be moved up and down from outside the closed hood by the elevating devices 16 mounted on the dryer frames 4.
  • Another method would be to place the elevating devices 16 on both inside ends of the fixed canopy hoods 15, and raise or lower the bridging frames.
  • Door devices for the inspection ports are provided on both sides of the canopy hoods 15.
  • Fabric rolls 10 are provided on the corners of the hoods, and pinch fabric rolls 12 are provided at the entrance/exit of the hoods covering each group of dryer cylinders 1.
  • Fabric tension rolls 11 are also provided at suitable locations so that upper and lower gas-permeable endless fabric belts 36 can travel inside the sealed hoods.
  • a suction box 23, to which the suction unit is connected, is disposed adjacent the supply box at a position generally diametrically opposite to the fabric suction rolls 8 with respect to a respective cylinder 1, and is connected at the driving side to a suction duct 24 through a flexible joint.
  • the steam circulation circuit is completed by providing, preferably on the driving side of the dryer cylinder group, exhaust emission screens 33 for removing mist, paper dust and other foreign matters in the exhaust gas; an exhaust gas heater 34 heated by suitable fuel or thermal medium; a steam circulation fan 25; an adiabatic expansion nozzle 26; supply ducts 27; a steam scrubber 28; a steam compressor 29; pressurized steam pipes 30; a steam adjusting valve 31; a make-up steam pipe 32, and suitably connecting them to suction duct 24, connecting duct 21 and the steam header pipe 7.
  • a wet paper web 35 having 50-60% of moisture which is obtained by passing wire and press parts is fed into the upper and lower pinch fabric rolls 12 at the entrance to the closed hood sealed with insulation panels.
  • the paper web 35 is then sandwiched between the upper and lower endless fabric belts 36 travelling inside the closed hood to reach the first lower dryer cylinder 1 located at the entrance of the hood.
  • the paper web 35 is then pulled downwards by the suction action of the suction fabric roll 8, and passes on the dryer cylinder 1 with the top surface being held in intimate contact with the outer peripheral surface of the cylinder 1.
  • the bottom surface of the paper web 35 is strongly pressed by the endless fabric belt 36 which is tensed by the fabric tension rolls 11.
  • the paper web 35 is dried while restrained by the cylinder 1 and the fabric belt 36.
  • the paper web 35 passes over the first dryer cylinder 1, the paper web 35 is released from the first dryer cylinder 1 at the exit by being pulled by the second suction fabric roll 8. The paper web 35 is again sandwiched between the two endless fabric belts 36, and reaches the entrance to the second dryer cylinder 1 disposed in the upper row, and the drying process is repeated over again as described above.
  • the paper web 35 can be selectively passed through either the upper row of dryer cylinders or the lower row of dryer cylinders 1, thereby enabling to control the difference in the degree of curl or flatness of the front surface and the back surface of the paper web 35.
  • the steam evaporated from the wet paper web 35 takes the following path.
  • the steam is sucked in through the suction ports 22 and the suction fabric rolls 8 to reach the emission screen 33 via the suction ports 23 and the suction ducts 24 of the canopy hoods 15.
  • the steam pressure is increased by the steam circulation fan 25.
  • the steam is then heated at the exit by the superheated steam from the adiabatic expansion nozzle 26, and most of this steam is directed to the paper web 35 after passing through the ducts 27, the supply boxes 20, the blast ports 19 and through the endless fabric belts 36.
  • the blasting or impinging action drives out the stagnant moisture from the voids within the endless fabric belts 36. This action not only heats the paper web 35 directly but also disturbs the boundary layer containing the saturated steam above the paper web 35 to promote evaporation of the moisture in the paper web 35, and produces an atmosphere of super-heated steam in excess of 100°C.
  • the exhaust heater 34 operated by fuel or thermal medium can be used to indirectly heat the steam. In this case, the adiabatic expansion nozzle 26 is closed.
  • a part of the steam pressurized by the circulation fan 25 is sent to the steam scrubber 28 to remove foreign particulate matters and non-condensable gases.
  • the steam is then adiabatically compressed by means of the steam compressor 29 to increase temperature and pressure, and most of this steam is sent to the dryer cylinders 1 via the pressurized pipes 30 to heat the cylinders 1.
  • a part of this steam is used to heat the recirculated steam via the adiabatic expansion nozzle 26.
  • the make-up pipe 32 is used to compensate for a deficient amount of steam.
  • the flow rates of the circulating steam are regulated by adjusting the steam valve 31 to control the moisture percent of the paper web 35 to control the curling of the paper web 35 or by adjusting the amount of steam supplied to the upper and lower dryer cylinders 1.
  • the elongated blast ports 19 may be each divided into a plurality of longitudinally separated zones so that the amount of steam blast differs from zone to zone, and it is thus possible to regulate the amount of steam blast in the width direction of the dryer cylinder 1, to thereby control the uniformity of moisture content in the paper web 35 in the width direction thereof.
  • Figure 6 depicts a second embodiment of the drying apparatus in accordance with the invention, in which each group of dryer cylinders 1 are provided in a single row arrangement.
  • adjacent groups of dryer cylinders 1 are arranged such that the web entrance/exit direction of one group of cylinders 1 is alternately upwards or downwards from the other group of cylinders 1.
  • Figure 6 shows a group of dryer cylinders 1 with the entrance/exit facing downwards.
  • Each dryer cylinder 1 is installed on the dryer frames 4 with the shafts 2 being rotatably supported thereon through the bearings 3.
  • a single suction fabric roll 8 is disposed at a position slightly lower than and between the adjacent two cylinders 1 with its journal portions being rotatably supported on the dryer frames 4 through the bearings 9. Furthermore, an upper canopy hood 15 is provided so as to cover those portions of the cylinders 1 which are positioned above the line including the axes of the shafts 2, whereas a lower canopy hood 15 is provided below the upper canopy hood 15.
  • These canopy hoods are constructed so that they can be raised or lowered by means of the elevating device 16 comprised of plural drive cylinder devices.
  • a middle hood 17 and an opening device 18 comprised of a plurality of openable doors for accessing the middle hood interior for the purpose of inspection or cleaning.
  • the hoods are sealed tightly during a drying operation except for the openings for entry and exit of the paper web 35.
  • a lower endless fabric 36 which is driven by fabric rolls 10 is only provided for feeding/discharging of the paper web 35.
  • the lower endless fabric 36 in the lower hood can be eliminated.
  • a plurality of blow ports 19 as well as a plurality of suction ports 22 are arranged so as to surround the lower part of the outer peripheral surface of a respective suction fabric roll 8 with spacings of about 10 to 25 mm formed therebetween.
  • the blow ports 19 are connected to the supply boxes 20 which are further connected to the connecting ducts 21. The steam to be sucked by the suction fabric roll 8 is little, and most of the steam is sucked through these suction ports 22.
  • the paper web 35 is dried in basically the same manner as in the first embodiment. More specifically, the paper web 35 is guided by a pair of top and bottom pinch rolls 12 at the entrance to the hoods and is held between the two endless fabric belts 36 to go around the inside of the closed hood. When the paper web 35 reaches the dryer cylinder 1, it passes over the cylinder 1 with the bottom surface being held in contact with the outer peripheral surface of the cylinder 1 and with the top surface being held tightly against the endless fabric belt 36 which is tensed by the action of the fabric tension rolls 11. When the paper web 35 passes over the first dryer cylinder 1, the paper web 35 is released from the cylinder 1 at the exit by being pulled by the suction fabric roll 8, and the paper web is further guided onto the second cylinder 1. After the repetition of the above movement, the paper web 35 is led out of the hood by being pinched by the pinch fabric rolls 12 at the exit. Other operations are the same as those in the first embodiment, and their explanations will be omitted.
  • a double row multi-cylinder arrangement is adopted, and, in each group of cylinders, the lower row of drying cylinders 1 are installed on the lower dryer frames 4 with the shafts 2 being rotatably supported thereon through suitable bearings 3.
  • upper dryer frames 4' are constructed separately from the lower dryer frames 4. Specifically, the machine foundations 13 for the lower dryer frames are extended forwardly at the operational side of the machine, and additional sole plates are anchored thereto. Then, bridging frames are built on the sole plates on the extended foundations, and the upper dryer frames 4', which are arranged immediately above the lower dryer frames 4, are fixedly secured to the bridging frames through horizontal frames.
  • each of the upper row cylinders 1 is installed on the upper dryer frames 4' with the shafts 2 being rotatably supported thereon through the bearings 3.
  • the middle hood 17 disposed between the upper and lower canopy hoods 15 can be accessed more readily; and cleaning or maintenance operations, such as replacing of the endless fabric belts 36, can be carried out more quickly.
  • a pair of suction fabric rolls 8 and a pocket gas supply box 37 are arranged at the entry/exit pocket portion for each dryer cylinder 1.
  • the pocket supply box 37 which is located between the pair of suction fabric rolls 8, is fixed in place by attaching the opposite ends to the side panels of the middle hood 17, and is provided with doctor blades both at the entry and exit sides so as to come into contact with the outer peripheral surface of the associated dryer cylinder 1.
  • Those surfaces of the pocket supply box 37 which face the suction fabric rolls 8 with appropriate spacings formed therebetween are formed in an arcuate shape when viewed in a side direction, and a plurality of blast openings (slits or circular holes) are provided in a respective arcuate surface.
  • the upper suction fabric rolls 8 are rotatably supported on the upper dryer frames 4', whereas the lower suction fabric rolls 8 are rotatably supported on the lower dryer frames 4.
  • the wet paper web 35 enters the entrance of the first lower cylinder 1 by being sandwiched between the two endless fabric belts 36. Then, the paper web 35 is pulled by the suction fabric roll 8 downwards, and is heated by the super-heated steam, having a temperature in excess of 100°C, blown through the entry side of the pocket supply box 37 against the wet paper web 35. The paper web 35 then travels by being separated from the upper endless fabric belt 36, and the super-heated steam, which passes through the paper web 35 and the endless fabric belt 36, is withdrawn by the suction fabric rolls 8 and is recirculated together with the steam evaporated from the paper web 35.
  • the moist paper web 35 is going to be dried at the entrance under the restrained condition by the pressure of the superheated steam in excess of 100°C coming from the pocket supply box 37, in cooperation with the suction effects provided by the suction fabric roll 8. Then, the paper web 35 is further dried with its top surface being in contact with the dryer cylinder 1 and with its bottom surface being strongly pressed by the endless fabric belt 36 aided by the action of the fabric tension rolls 11. Thus, a restrained drying is effected. When the paper web 35 reaches the exit of the first lower dryer cylinder 1, it is pulled upward by the second suction fabric roll 8, and is pulled away from the dryer cylinder 1 by the superheated steam (in excess of 100°C) blown through the exit side of the pocket supply box 37.
  • the paper web 35 then goes upwards around the suction fabric roll 8 to come into contact with the upper endless fabric belt 36, and is held between the two endless fabric belts 36, and reaches the entry side of the upper dryer cylinder 1.
  • the paper web 35 is pulled by the third suction fabric roll 8, and by the superheated steam (in excess of 100°C) blown from the entry side of the upper pocket supply box 37 against the paper web 35.
  • the paper web 35 then travels by being separated from the bottom endless belt 36. The process described above is repeated to dry the paper web 35.
  • the doctor blades provided on each pocket supply box 37 are used to clean the surface of the associated dryer cylinder 1, and also prevent the paper web 35 to be held up in the pocket section by debris or by sagging of the paper web 35. They are also useful when scraping sticking paper web 35 away from the surface of the dryer cylinder 1.
  • the dryer frames are separated into upper frames 4' and lower frames 4, those frame portions acting as obstacles to interfere with opening and closing of the door to the middle hood 17 have been eliminated.
  • the middle hood 17 it is possible to construct the middle hood 17 so that it can be withdrawable in every section, or openable, or doors may be provided. Additionally, the handling of the pocket supply boxes 37 has become easier.
  • an atmosphere of superheated steam having a temperature in excess of 100°C is used as a drying atmosphere.
  • an atmosphere of heated moist air having a dew point of at least 80°C may be instead employed as the drying atmosphere without any significant modifications to the construction of the drying apparatus.
  • the use of the aforesaid heated moist air atmosphere to the first embodiment will be hereinafter described.
  • a wet paper web 35 having 50-60% of moisture is fed into the closed hood and sandwiched between the upper and lower endless fabric belts 36 to reach the first lower dryer cylinder 1.
  • the paper web 35 is then pulled downwards by the suction action of the suction fabric roll 8, and passes on the dryer cylinder 1 while restrained by the cylinder 1 and the fabric belt 36.
  • the paper web 35 passes over the first dryer cylinder 1 and is released from the first dryer cylinder 1 at the exit by being pulled by the second suction fabric roll 8, it is again sandwiched between the two endless fabric belts 36 to reach the entrance to the second dryer cylinder 1, and the drying process is repeated over again as described above.
  • the steam evaporated from the wet paper web 35 is sucked in through the suction ports 22 and the suction fabric rolls 8 to reach the emission screen 33 via the suction ports 23 and the suction ducts 24.
  • the steam pressure is increased by the steam circulation fan 25.
  • the steam is then heated at the exit by the superheated steam from the adiabatic expansion nozzle 26 preferably to a dry bulb temperature of no less than 150°C, and most of this steam is directed to the paper web 35 after passing through the ducts 27, the supply boxes 20, the blast ports 19 and through the endless fabric belts 36.
  • the blasting or impinging action drives out the stagnant moisture from the voids within the endless fabric belts 36.
  • This action not only heats the paper web 35 directly but also disturbs the boundary layer containing the saturated steam above the paper web 35 to promote evaporation of the moisture in the paper web 35, and produces an atmosphere of heated moist air having a dew point temperature in excess of 80°C.
  • the drying atmosphere be regulated such that the interfaces between the dryer cylinder 1 and the wet paper web 35 have a dew point temperature of close to 100°C while the other portions have a dew point temperature in excess of 80°C.
  • a part of the steam pressurized by the circulation fan 25 is circulated in the same manner as in the first embodiment.
  • the atmosphere of heated moist air can be produced to achieve advantages as described before in conjunction with Figure 2.
  • the drying apparatus in accordance with this embodiment has a double row multi-cylinder arrangement basically similar to that of the first embodiment.
  • the entry and exit openings formed through the middle hood 17 for entering/exiting of the paper web 35 are closed by means of suitable sealing devices (described later) to provide a completely closed drying chamber in the hoods.
  • first steam-supply boxes 20 of an annular shape associated with a respective dryer cylinder 1 so as to substantially surround the outer peripheral surface thereof, and a plurality of second steam-supply boxes 48 of a generally triangular shape connecting the adjacent supply boxes 20, these supply boxes being spaced axially of the dryer cylinder 1.
  • a blast unit comprised of a plurality of elongated tubular members of a rectangular-shaped cross-section arranged arranged around the cylinder 1 in circumferentially spaced relation and each having a great number of blast or blow ports (first blow ports) 19 formed in the surface facing the dryer cylinder 1.
  • a further blast unit which comprises a plurality of elongated tubular members of a rectangular-shaped cross-section arranged along the path, extending between adjacent upper and lower cylinders 1 tangentially and diagonally, in longitudinally spaced relation, and each having second blast ports 47 formed in the surface facing the above-mentioned path.
  • suction units each of which comprises a plurality of elongated suction ports 22 and 50 defined by the spacings between adjacent blast ports 19 and 47, respectively.
  • the blast ports 19 and 47 and the suction ports 22 and 50 are arranged on a continuous curved plane comprised of a plurality of horse-shoe shaped planes connected in series.
  • the blast ports and the suction ports may be of either slit or circle shape, and it is preferable that the spacing between the blast ports and the paper web be about 10 ⁇ 25 mm.
  • the blast units and the suction units are connected separately to the suitable canopy hoods 15 and middle hood 17.
  • a plurality of connecting ducts 21 and 49 which are connected to the supply boxes 20 and 48, are connected at the driving side of the dryer to drying medium-supply ducts 27 through suitable flexible joints.
  • the blast ports 47 and the supply boxes 48 may be attached to base frames arranged inside the hood 17 so as to be adjacent to the drive and operational sides thereof. And, one or more connecting bases extending from the base frames through the middle hood panelling outwards may be connected to right and left escape devices 46 disposed outside the hood, the escape devices being capable of pivoting or moving forwards and backwards.
  • the through holes in the insulating panelling are closed by a flexible sheet to shut off the hood from outside.
  • the numeral 49' denotes connecting ducts for the suction boxes 48'.
  • the arrangements of the hoods may be modified in the same manner as in the first embodiment.
  • Fabric rolls 10 are provided on the corners of the hoods, and a suitable sealing device is provided at each of the entrance and exit of the hoods covering each group of dryer cylinders 1.
  • Fabric tension rolls 11 are also provided at suitable locations so that upper and lower gas-permeable endless fabric belts 36 can travel inside the totally sealed hoods.
  • suction boxes 23, to which the suction unit is connected, are disposed adjacent the supply boxes at upper parts of the upper canopy hoods 15 and at lower parts of the lower canopy hoods 15, and are connected at the driving side to suction ducts 24 through flexible joints.
  • Figures 14 to 16 show sealing devices which are located at the entrance and the exit of the middle hood.
  • Figure 14 is an enlarged view depicting a basic construction of the device, while Figures 15 and 16 depict an entrance side-sealing device and an exit-side sealing device, respectively.
  • the exit-side sealing device differs from the entrance-side sealing device only in that it is in a reverse and upside-down relationship to the entrance-side sealing device shown in Figure 15 or 16.
  • the sealing device includes one or more (two in the illustrated embodiment) inner sealing rolls 60 arranged inside the hood, one or more (two in the illustrated embodiment) outer sealing rolls 61 located outside the hood 17, a blanket 62 formed for example of a heat-resistant rubber and looped around the inner and outer sealing rolls, a suitable drive means (not shown) for causing the blanket to travel around, and a suitable tension device (not shown) for keeping the tension of the blanket as appropriate.
  • the blanket is solid because it brings air into the closed hood if it has voids in it.
  • a sealing pinch roll 63 for accommodating linear load of 5 kg/cm width is arranged in opposed relation to the outer sealing roll 61, and another conveyor roll 64 is coupled to the sealing pinch roll, and a conveyer belt 65 is looped therearound to define a conveyer device 66 for facilitating the feeding of the paper web 35.
  • a suction box 67 is provided between the rolls.
  • a suitable belt material which has voids (mesh, slits or circular holes) for enabling sucking is used as the conveyor belt 65.
  • a sealing frame 68 having an opening formed therethrough is mounted on the outer surface of the hood 17 with the opening in alignment with the entry opening of the hood, and a half-divided sealing pipe 69 is attached to the sealing frame 68 with one end of each half piece being fastened to the frame by suitable fastening means and with those portions adjacent to the other ends being held in sealing contact, at an appropriate linear load, with the outer blanket roll 61 and the pinch roll 63, respectively.
  • a pair of sealing plate members 70 are fastened by suitable fastening means to the both sides of the sealing frame 68 with the inner surfaces being held in sealing contact with the opposite ends of each of the blanket roll 61 and the pinch roll 63. It is more preferable that the plate members 70 be held in contact with the ends of the rolls by using springs or cylinder devices for enabling resilient and smooth contact.
  • Figures 17 and 18 depict modifications of an entrance side-sealing device.
  • the corresponding exit-side sealing devices are not illustrated since each exit-side sealing device differs from the entrance-side sealing device only in that it is in a reverse and upside-down relationship to the entrance-side sealing device shown in Figure 17 or 18.
  • another sealing blanket 71, sealing frame 72, additional roll 73 and so on are employed to omit the paper web supply conveyer and to ensure a restrained feeding during passing of the paper web through the entrance opening.
  • the upper blanket-roll assembly is omitted by providing a single sealing pinch roll 63, and the lower sealing blanket 71 is provided so as to travel and receive the paper web thereon, thereby omitting the supply conveyer.
  • the operation of the device of Figure 18 is described as an example.
  • the wet paper web 35 is fed on the sealing blanket 71, and introduced through the opening by the feeding action of the sealing pinch roll 63 and the sealing blanket roll 61 while shutting off the hood from the outside air into the hood, following which the paper web 35 is sucked in by the suction fabric roll 8 through the gas permeable endless fabric belts 36 to reach the first cylinder 1.
  • a wet paper web 35 which is led into the hood by the sealing device and sucked in by the suction fabric roll 8, is sandwiched between the upper and lower endless fabric belts 36 travelling inside the closed hood to reach the first lower dryer cylinder 1 located at the entrance of the hood.
  • the paper web 35 then begins to pass on the dryer cylinder 1 while sandwiched between the two end less fabric belts 36.
  • the paper web 35 passes over the first dryer cylinder 1, the paper web 35 is still sandwiched between the two endless fabric belts 36, and reaches the entrance to the second dryer cylinder 1 disposed in the upper row, and the drying process is repeated over again as described above.
  • the steam evaporated from the wet paper web 35 by the dryer cylinders 1 and the impingement flow of superheated steam, is sucked in through the suction ports 22 and 50 and the suction fabric rolls 8 to reach the emission screen 33 via the suction ports 23 and the suction ducts 24 of the canopy hoods 5.
  • the steam pressure is increased by the steam circulation fan 25.'
  • the steam is then heated at the exit by the superheated steam from the adiabatic expansion nozzle 26, and most of this steam is directed to the paper web 35 after passing through the ducts 27, the supply boxes 20, the blast ports 19 and through the endless fabric belts 36.
  • the blasting or impinging action drives out the stagnant moisture from the voids within the endless fabric belts 36.
  • This action not only heats the paper web 35 directly but also disturbs the boundary layer containing the saturated steam above the paper web 35 to promote evaporation of the moisture in the paper web 35, and produces an atmosphere of superheated steam in excess of 100°C, preferably about 150°C.
  • the exhaust heater 34 operated by fuel or thermal medium can be used to indirectly heat the steam.
  • a part of the steam pressurized by the circulation fan 25 is sent to the steam scrubber 28 to remove foreign particulate matters and non-condensable gases.
  • The. steam is then adiabatically compressed by means of the steam compressor 29 to increase temperature and pressure, and most of this steam is sent to the dryer cylinders 1 via the pressurized pipes 30 to heat the cylinders 1.
  • a part of this steam is used to heat the recirculated steam via the adiabatic expansion nozzle 26.
  • the make-up pipe 32 is used to compensate for a deficient amount of steam.
  • the flow rates of the circulating steam are regulated by adjusting the steam valve 31 to control the moisture percent of the paper web 35 to control the curling of the paper web 35 or adjusting the amount of steam supplied to the upper and lower dryer cylinders 1.
  • the elongated blast ports 19 may be each divided into a plurality of longitudinally separated zones so that the amount of steam blast differs from zone to zone, and it is thus possible to regulate the amount of steam blast in the cross direction of the dryer cylinder 1, to thereby control the uniformity of moisture percent of the paper web 35 in the cross direction thereof.
  • Figures 19 to 21 depict a drying apparatus in accordance with a fifth embodiment of the invention, which differs from the fourth embodiment in that the paper web 35 is passed on each dryer cylinder 1 with the surface being held in intimate contact with the outer peripheral surface of the cylinder 1, and with the opposite surface being strongly pressed by the endless fabric belt 36 which is tensed by the fabric tension rolls 11.
  • sealing devices are provided at the entrance and the exit of the hood 17, respectively.
  • the sealing devices to be used in the present embodiment are shown from Figures 22 to 25, and are basically similar to those of Figures 15 to 18.
  • the upper endless fabric belt 36 is caused to travel around the upper row cylinders 1 and when released from the upper cylinder 1, it is guided by a suitable fabric roll to turn away from the path of the paper web towards the next cylinder 1, and returns and caused to run toward the adjacent upper cylinder.
  • the lower endless fabric belt 36 is also caused to travel around the lower cylinders 1 and guided to turn towards the next lower cylinder 1.
  • one of the two endless fabric belts 36 is not used to sandwich the paper web when the paper web 35 sucked by the suction fabric roll 8 is caused to pass around the cylinder 1, and the paper web 35 is caused to pass around the cylinder 1 with one of the surfaces being directly contact with the outer peripheral surface of the cylinder 1 and with the other surface being pressed the other endless fabric belt 36.
  • a wet paper web 35 fed into the closed hood is sandwiched between the upper and lower endless fabric belts 36 travelling inside the closed hood to reach the first dryer cylinder 1 located at the entrance of the hood.
  • the paper web 35 then passes on the dryer cylinder 1 with the top surface being held in intimate contact with the outer peripheral surface of the cylinder 1.
  • the bottom surface of the paper web 35 is strongly pressed by the endless fabric belt 36 which is tensed by the fabric tension rolls 11.
  • the paper web 35 is dried while restrained by the cylinder 1 and the fabric belt 36.
  • the paper web 35 passes over the first dryer cylinder 1, the paper web 35 is released from the first dryer cylinder 1 at the exit by being sucked through the suction ports 50 arranged at the side of the fabric belt 36, and travels on a straight plane while kept restrained by the suction ports 50 through the fabric belt 36 (lower fabric belt in the illustrated example).
  • the paper web 35 then reaches the intermediate position between the adjacent lower and upper dryer cylinders 1, and is sandwiched for a while between the lower and upper fabric belts 26. Subsequently, the paper web 35 is released from the first (lower) fabric belt 36, and kept restrained on the other (upper) fabric belt 36 by the suction force of the suction ports 50 disposed adjacent thereto.
  • the paper web 35 reaches the entrance of the next dryer cylinder 1 while kept restrained, and the drying process is repeated over again as described above.
  • suction ports 50 and the suction boxes 48' which is connected with suction ducts 49' may be connected to escape devices 46 mounted on the dryer frames.
  • both the blow ports and the suction ports are arranged along the path of the paper web at a zone between the adjacent dryer cylinders, only the suction ports 50 are arranged between the adjacent dryer cylinders 1 in this embodiment. This is because, if the blow ports should also be provided, the paper web traveling between the adjacent dryer cylinders 1 may float away from the fabric belt by the blown drying medium, so that the restrained drying cannot be ensured. Thus, as clearly seen in Figure 21, the blow ports are not provided between the adjacent dryer cylinders 1.
  • sealing devices may be added to the second embodiment of the invention as shown in Figure 6.
  • a drying atmosphere of heated moist air may be produced in the sealed hood.

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Claims (35)

  1. Verfahren zum Trocknen eines nassen Lagen- bzw. Bahnmaterials, gekennzeichnet durch folgende Schritte:
    (a) Einführen eines Trocknungsmediums in eine geschlossene Kammer (15), die mehrere beheizte, in Reihe angeordnete Trocknerzylinder (1) und ein gasdurchlässiges Gewebeband (36) umgibt, um in der geschlossenen Kammer eine Trocknungsatmosphäre zu erzeugen, wobei das Trocknungsmedium aus der Gruppe, bestehend aus überhitztem Dampf von nicht weniger als 100°C und erwärmter feuchter Luft eines Taupunkts von nicht weniger als 80°C, ausgewählt wird,
    (b) Einleiten des nassen Lagen- bzw. Bahnmaterials (35) in die geschlossene Kammer,
    (c) Transportieren des nassen Lagenmaterials in der Trocknungsatmosphäre in der geschlossenen Kammer, während das Lagenmaterial von seinen beiden Seiten her mittels der Trocknerzylinder (1) und des Gewebebands (36) festgehalten wird, um dadurch eine "restringierte" (restrained) Trocknung zum Verdampfen von Feuchtigkeit des Lagenmaterials von einer gekrümmten kontinuierlichen Verdampfungsfläche zu bewirken um das Lagenmaterial zu trocknen,
    (d) Entfernen des aus dem nassen Lagenmaterial verdampften Dampfes durch das gasdurchlässige Gewebeband hindurch, um den Dampf für eine Wiederverwendung zu rezirkulieren, und
    (e) Herausführen des getrockneten Lagenmaterials aus der geschlossenen Kammer.
  2. Trocknungsverfahren nach Anspruch 1, wobei der Entfernungsschritt (d) ein zumindest teilweises Rezirkulieren oder Rückführen des verdampften Dampfes zu den Trocknerzylindern zum Erwärmen oder Beheizen derselben umfaßt.
  3. Trocknungsverfahren nach Anspruch 1, wobei der Entfernungsschritt (d) ein Erwärmen eines Teils des rezirkulierten Dampfes, der gegen das durch die Trocknerzylinder und das Gewebeband gehaltene bzw. geführte nasse Lagenmaterial (35) bläst, umfaßt.
  4. Trocknungsverfahren nach Anspruch 1, wobei der Transportschritt (c) ein Blasen des Trocknungsmediums gegen das durch die Trocknerzylinder und das Gewebeband gehaltene bzw. geführte nasse Lagenmaterial mit hoher Auftreffgeschwindigkeit umfaßt.
  5. Trocknungsverfahren nach Anspruch 1, wobei im Transportschritt (c) die gekrümmte kontinuierliche Verdampfungsfläche durch mehrere hufeisenförmige Flächen, die - in Axialrichtung der Trocknerzylinder gesehen - miteinander verbunden sind, festgelegt ist.
  6. Trocknungsverfahren nach Anspruch 1, wobei der Transportschritt (c) ein Führen des nassen Lagenmaterials über die beheizten, in Reihe angeordneten Trocknerzylinder umfaßt, wobei seine eine Seite mit einer Außenumfangs- bzw. Mantelfläche jedes Trocknerzylinders in Berührung gehalten und dessen andere Seite durch das Gewebeband gehalten bzw. geführt wird.
  7. Trocknungsverfahren nach Anspruch 6, wobei der Transportschritt (c) ein Führen des nassen Lagenmaterials zwischen benachbarten Trocknerzylindern unter Verwendung von Sauggewebewalzen (8) in der Weise, daß das Lagenmaterial auf der Sauggewebewalze bei dazwischen eingefügtem gasdurchlässigem Gewebeband (36) vorbeiläuft, und wobei der Entfernungsschritt (d) das Absaugen des aus dem nassen Lagenmaterial verdampften Dampfes über die Sauggewebewalzen (8) umfaßt.
  8. Trocknungsverfahren nach Anspruch 6, wobei der Transportschritt (c) ein Führen des nassen Lagenmaterials zwischen benachbarten Trocknerzylindern in der Weise, daß das Lagenmaterial auf dem gasdurchlässigen Gewebeband mittels einer Saugkraft festgehalten wird, umfaßt.
  9. Trocknungsverfahren nach Anspruch 8, wobei der Transportschritt (c) umfaßt:
    Halten bzw. Führen des von einem Trocknerzylinder (1) freigegebenen nassen Lagenmaterials (35) auf einem über den einen Trocknerzylinder hinweglaufenden gasdurchlässigen Gewebeband (36),
    anschließendes sandwichartiges Führen des nassen Lagenmaterials zwischen dem einen gasdurchlässigen Gewebeband (36) und einem anderen gasdurchlässigen Gewebeband, das über den anderen Trocknerzylinder hinwegläuft;
    und sodann weiteres Halten bzw. Führen des nassen Lagenmaterials auf dem anderen gasdurchlässigen Gewebeband.
  10. Trocknungsverfahren nach Anspruch 8, wobei der Entfernungsschritt (d) ein Absaugen des aus dem nassen Lagenmaterial (35) verdampften Dampfes durch das gasdurchlässige Gewebeband (36) hindurch umfaßt.
  11. Trocknungsverfahren nach Anspruch 3, wobei der Transportschritt (c) ein Führen des nassen Lagenmaterials über die beheizten, in Reihe angeordneten Trocknerzylinder, während das Lagenmaterial zwischen einem Paar der gasdurchlässigen Gewebebänder (36) sandwichartig gehalten ist, umfaßt.
  12. Trocknungsverfahren nach Anspruch 11, wobei der Transportschritt (c) ein Blasen des Trocknungsmediums gegen das zwischen den gasdurchlässigen Gewebebändern (36) sandwichartig gehaltene nasse Lagenmaterial umfaßt und wobei der Entfernungsschritt (d) ein Absaugen des aus dem nassen Lagenmaterial verdampften Dampfes durch die gasdurchlässigen Gewebebänder hindurch umfaßt.
  13. Trocknungsverfahren nach Anspruch 1, wobei das Trocknungsmedium die erwärmte feuchte Luft ist, (und) das Trocknungsmedium einen Taupunkt von annähernd 100°C an einer Kontakt-Grenzfläche zwischen der Mantelfläche des Trocknerzylinders und dem Lagenmaterial sowie von mindestens 80°C an einer Position, an welcher das Lagenmaterial vom Trocknerzylinder beabstandet ist, aufweist.
  14. Trocknungsverfahren nach Anspruch 1, wobei das Trocknungsmedium die erwärmte feuchte Luft ist, die eine Trockentemperatur von mindestens 150°C aufweist und mindestens etwa 50 Vol.-% überhitzten Dampf enthält.
  15. Vorrichtung zum Trocknen eines nassen Lagenmaterials, gekennzeichnet durch:
    eine Trocknerrahmenanordnung (4),
    an der Trocknerrahmenanordnung angebrachte Lagervorrichtungen (3),
    mehrere Trocknerzylinder (1) zum Erwärmen des Lagenmaterials, wobei jeder der Trocknerzylinder einen Zylinderkörper mit einer Außenumfangs- oder Mantelfläche und gegenüberliegende Stirnflächen desselben sowie ein Paar an den gegenüberliegenden Stirnflächen angeformte Wellen- bzw. Achsabschnitte (2) aufweist, (und) jeder Trocknerzylinder an der Trocknerrahmenanordnung drehbar angeordnet ist, wobei die Wellen- bzw. Achsabschnitte (2) durch die Lagervorrichtungen (3) gelagert sind,
    ein den Trocknerzylindern zugeordnetes endloses, gasdurchlässiges Gewebeband (36), das zum Zusammenwirken mit den Trocknerzylindern zum Transportieren des Lagenmaterials angeordnet ist, wobei das Gewebeband (36) um einen betreffenden Trocknerzylinder herumgeschlungen ist, um das Lagenmaterial gegen die Mantelfläche des Trocknerzylinders zu pressen und das Lagenmaterial zu halten bzw. zu führen,
    eine den Trocknerzylindern zugeordnete Transportiervorrichtung zum Transportieren des Lagenmaterials von einem jeweiligen Trocknerzylinder zu diesem ihm benachbarten Trocknerzylinder, während das Lagenmaterial weiter gehalten wird,
    eine neben den Trocknerzylindern angeordnete, wärmeisolierte Haubenanordnung (15), welche die Mantelflächen der Trocknerzylinder (1) im wesentlichen umschließt, während die Lagervorrichtungen (3) außenseitig angeordnet sind, um eine enge, abgedichtete Trocknerkammer festzulegen, wobei die wärmeisolierte Haubenanordnung (15) zumindest teilweise zwischen einer geschlossenen Stellung, in welcher die Trocknerkammer im wesentlichen verschlossen ist, und einer geöffneten Stellung, in welcher die Trocknerkammer geöffnet ist, bewegbar ist, und
    eine an der wärmeisolierten Haubenanordnung angebrachte Trocknungsmedium-Umwälzvorrichtung zum Zuführen eines Trocknungsmediums in diese zur Erzeugung einer Trocknungsatmosphäre in der Trocknerkammer und zum Entfernen des aus dem Lagenmaterial verdampften Dampfes durch das gasdurchlässige Gewebeband hindurch, um den Dampf für eine Wiederverwendung rückzugewinnen, wobei das Trocknungsmedium aus der Gruppe aus überhitztem Dampf von nicht weniger als 100°C und erwärmter feuchter Luft eines Taupunkts von nicht weniger als 80°C ausgewählt ist.
  16. Trocknungsvorrichtung nach Anspruch 15, wobei die Trocknerzylinder (1) in einer Doppelreihenanordnung mit einer oberen Reihe von Trocknerzylindern und einer unteren Reihe von Trocknerzylindern angeordnet sind.
  17. Trocknungsvorrichtung nach Anspruch 15, wobei die Trocknerzylinder (1) in einer Einzelreihenanordnung mit einer einzigen Reihe von Trocknerzylindern angeordnet sind.
  18. Trocknungsvorrichtung nach Anspruch 15, wobei die wärmeisolierte Haubenanordnung (15) eine obere Haube, eine untere Haube und eine zwischen oberer und unterer Haube angeordnete mittlere Haube aufweist, wobei mindestens eine der oberen, unteren und mittleren Hauben zwischen der offenen Stellung und der geschlossenen Stellung bewegbar ist.
  19. Trocknungsvorrichtung nach Anspruch 18, ferner mit einem Paar jeweils an einer betreffenden der oberen und unteren Hauben angebrachter Hebevorrichtungen (16) zum Bewegen der betreffenden Haube zu den Zylindern hin und von diesen weg.
  20. Trocknungsvorrichtung nach Anspruch 15, wobei die Transportvorrichtung mehrere jeweils neben einem betreffenden zugeordneten der Trocknerzylinder (1) angeordneten Sauggewebewalzen (8) zum Führen des Lagenmaterials auf den zugeordneten Trocknerzylinder oder von diesem weg aufweist.
  21. Trocknungsvorrichtung nach Anspruch 15, wobei ein Paar der endlosen gasdurchlässigen Gewebebänder (36) vorgesehen sind, eines der endlosen gasdurchlässigen Gewebebänder um einen zugeordneten der Trocknerzylinder (1) herumgeschlungen ist, während das andere endlose gasdurchlässige Gewebeband um den neben dem zugeordneten Trocknerzylinder angeordneten Trocknerzylinder herumgeschlungen ist, und das Paar Gewebebänder (36) sich im wesentlichen zu einer mittleren Position zwischen dem einen Trocknerzylinder und dem anderen Trockner erstreckt, wobei das Paar Gewebebänder als die Transportvorrichtung dienen.
  22. Trocknungsvorrichtung nach Anspruch 15, wobei ein Paar der endlosen gasdurchlässigen Gewebebänder (36) vorgesehen ist, welche das Lagenmaterial zwischen sich sandwichartig halten, (und) das Paar Gewebebänder um einen betreffenden Trocknerzylinder geschlungen ist und sich von einem betreffenden Trocknerzylinder zu dem diesem benachbarten Trocknerzylinder erstreckt, wobei das Paar Gewebebänder als die Transportvorrichtung dient.
  23. Trocknungsvorrichtung nach Anspruch 15, wobei die Trocknungsmedium-Umwälzvorrichtung eine Saugvorrichtung mit mehreren längs dem Weg des Lagenmaterials angeordneten Saugöffnungen (23) zum Absaugen des aus dem Lagenmaterial verdampften Dampfes aufweist.
  24. Trocknungsvorrichtung nach Anspruch 15, wobei die Trocknungsmedium-Umwälzvorrichtung eine Blasvorrichtung mit mehreren längs einem Weg des Lagenmaterials angeordneten Blasauslässen (19) zum Ausblasen des Trocknungsmediums gegen das Lagenmaterial aufweist.
  25. Trocknungsvorrichtung nach Anspruch 23, wobei die Trocknungsmedium-Umwälzvorrichtung ferner mehrere Umwälzleitungen aufweist, die zur Wiederverwendung des rückgewonnenen Dampfes an die Saugvorrichtung angeschlossen sind.
  26. Trocknungsvorrichtung nach Anspruch 23, wobei die Umwälzleitungen an die Blasvorrichtung angeschlossen sind.
  27. Trocknungsvorrichtung nach Anspruch 25, wobei die Umwälzleitungen ferner an die Trocknerzylinder angeschlossen sind, um diese zu beheizen.
  28. Trocknungsvorrichtung nach Anspruch 15, ferner mit einer an der wärmeisolierten Haubenanordnung angebrachten Einlass-Abdichtvorrichtung zum Einlassen des Lagenmaterials in die Haubenanordnung in abdichtender Beziehung zu diesem und einer an der Haubenanordnung angebrachten Auslassabdichtvorrichtung zum Herauslassen des Lagenmaterials aus der Haubenanordnung in abdichtender Beziehung zu diesem.
  29. Trocknungsvorrichtung nach Anspruch 28, wobei jede der Einlaß- und Auslaß-Abdichtvorrichtungen mindestens zwei innerhalb bzw. außerhalb der Haubenanordnung angeordnete Abdichtwalzen, und eine um mindestens zwei Abdichtwalzen zum Durchlauf durch die Haubenanordnung herumgeschlungene Abdichtdecke, eine in Zuordnung zu einer der Abdichtwalzen angeordnete Förderwalze zum Führen des Lagenmaterials dazwischen und ein Abdichtelement, das zwischen der Förderwalze und der Haubenanordnung angeordnet ist und ein Paar konvex gekrümmte, mit der Förderwalze und der zugeordneten Abdichtwalze elastisch in Berührung gehaltene Abschnitte aufweist, umfaßt.
  30. Trocknungsvorrichtung nach Anspruch 29, wobei die Abdichtvorrichtung ferner ein Paar gegenüberliegender Abdichtplatten aufweist, die an der Haubenanordnung so angebracht sind, daß sie mit gegenüberliegenden Enden der Förderwalze und der (dieser) zugeordneten Abdichtwalze in abdichtendem Kontakt gehalten sind.
  31. Trocknungsvorrichtung nach Anspruch 20, ferner mit mehreren neben den Sauggewebewalzen angeordneten Gaszuführkästen, von denen jeder eine einem Teil einer Außenumfangs- bzw. Mantelfläche einer jeweiligen Sauggewebewalze zugewandte Oberfläche aufweist mehrere in der Oberfläche geformte Blasöffnungen zum Ausblasen des Trocknungsmediums gegen die betreffende Sauggewebewalze versehen sind.
  32. Trocknungsvorrichtung nach Anspruch 31, wobei das Paar Sauggewebewalzen neben einem betreffenden Trocknerzylinder angeordnet ist, (und) der Gaszuführkasten zwischen dem Paar Sauggewebewalzen mit zu beiden des Paars Sauggewebewalzen hin gerichteten Blasöffnungen angeordnet ist.
  33. Trocknungsvorrichtung nach Anspruch 20, ferner mit mehreren Blas- und Saugvorrichtungen, die neben einer jeweiligen Sauggewebewalze angeordnet sind, wobei jede der Blas- und Saugvorrichtungen mehrere Gas(aus)blasöffnungen zum Blasen des Trocknungsmediums gegen die jeweilige Sauggewebewalze und mehrere Saugöffnungen zum Absaugen des aus dem Lagenmaterial, das auf der betreffenden Gewebewalze läuft, verdampften Dampfes aufweist.
  34. Trocknungsvorrichtung nach Anspruch 17, ferner mit mehreren Saugwalzen zum Führen des Lagenmaterials zwischen benachbarten Trocknerzylindern und mehreren neben einer betreffenden Sauggewebewalzen angeordneten Blas- und Saugvorrichtungen, wobei jede der Blas- und Saugvorrichtungen mehrere Gas(aus)blasöffnungen zum Blasen des Trocknungsmediums gegen die jeweilige Sauggewebewalze und mehrere Saugöffnungen zum Absaugen des aus dem Lagenmaterial, das auf der betreffenden Gewebewalze läuft, verdampften Dampfes aufweist.
  35. Trocknungsvorrichtung nach Anspruch 16, wobei die Trocknerrahmenanordnung einen an einer Bedienseite der Trocknungsvorrichtung angeordneten vorderen Trocknerrahmen aufweist, der einen unteren Rahmenabschnitt zum Haltern oder Lagern der unteren Reihe von Trocknerzylindern, einen über dem unteren Rohrabschnitt angeordneten oberen Rahmenabschnitt zum Haltern oder Lagern der oberen Reihe von Trocknerzylindern und einen mittleren Abschnitt umfaßt, welcher den unteren Rahmenabschnitt und den oberen Rahmenabschnitt verbindet und in einer Richtung von den Zylindern weg gegenüber den oberen und unteren Rahmenabschnitten verschoben bzw. versetzt ist.
EP19940308397 1993-11-15 1994-11-14 Verfahren und Vorrichtung zur Trocknung von bahnförmigem Material Expired - Lifetime EP0653514B1 (de)

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JP30977493 1993-11-15
JP30977493 1993-11-15
JP309774/93 1993-11-15
JP6147060A JP3007529B2 (ja) 1993-11-15 1994-06-06 シート状物質の乾燥方法及び装置
JP14706094 1994-06-06
JP147059/94 1994-06-06
JP14705994 1994-06-06
JP147060/94 1994-06-06
JP14705994 1994-06-06
JP278508/94 1994-10-17
JP27850894 1994-10-17
JP27850894A JP2907266B2 (ja) 1994-10-17 1994-10-17 シート状物質の乾燥方法及び装置
JP27847394 1994-10-18
JP278473/94 1994-10-18
JP27847394A JP2907265B2 (ja) 1994-10-18 1994-10-18 シート状物質の乾燥方法及び装置
JP287469/94 1994-10-27
JP28746994 1994-10-27
JP6287469A JP3007542B2 (ja) 1994-06-06 1994-10-27 シート状物質の乾燥方法及び装置

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US5933977A (en) * 1995-09-12 1999-08-10 Beloit Technologies, Inc. Curl control with dryer aircaps
US5921000A (en) * 1997-01-27 1999-07-13 Beloit Technologies, Inc. Alternating top and bottom felted dryers connected without open draw
CN105544273A (zh) * 2016-01-29 2016-05-04 苏州华尔美特装饰材料股份有限公司 墙纸冷却装置
DE102021204304A1 (de) 2021-04-29 2022-11-03 Valeo Eautomotive Germany Gmbh Verbesserte Möglichkeit zum Biegen von Leiterstäben einer Statorwicklung
CN114808528B (zh) * 2022-04-27 2023-05-26 赣州龙邦材料科技有限公司 一种可防止气泡和褶皱的芳纶纸成型装置及其使用方法

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US3576078A (en) * 1970-02-02 1971-04-27 Cons Paper Inc Paper drying process and apparatus
US3696522A (en) * 1970-10-30 1972-10-10 Hi Flux Corp Drier for paper webs
US3751822A (en) * 1971-12-17 1973-08-14 Beloit Corp Web dryer
SE396627B (sv) * 1975-03-19 1977-09-26 Svenska Flaektfabriken Ab Cylindertork for pappersframstellningsmaskin
US4242808A (en) * 1978-11-22 1981-01-06 Ingersoll-Rand Company Paper web drying system and process
US4523390A (en) * 1982-12-13 1985-06-18 Aer-Overly Corporation Peripheral exhaust system for high velocity dryer
DE3922361A1 (de) * 1989-07-07 1991-01-17 Voith Gmbh J M Verfahren und vorrichtung zum trocknen einer materialbahn
US5210958A (en) * 1991-07-15 1993-05-18 Mcgill University Paper web drying apparatus and process
JPH0598590A (ja) * 1991-10-03 1993-04-20 Mitsubishi Heavy Ind Ltd 抄紙機用ドライヤのフード給排気装置

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DE653514T1 (de) 1995-12-14
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EP0653514A2 (de) 1995-05-17
DE69429850T2 (de) 2002-09-19

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