CA2026045A1 - Method for contact-free drying of a paper or board web - Google Patents
Method for contact-free drying of a paper or board webInfo
- Publication number
- CA2026045A1 CA2026045A1 CA002026045A CA2026045A CA2026045A1 CA 2026045 A1 CA2026045 A1 CA 2026045A1 CA 002026045 A CA002026045 A CA 002026045A CA 2026045 A CA2026045 A CA 2026045A CA 2026045 A1 CA2026045 A1 CA 2026045A1
- Authority
- CA
- Canada
- Prior art keywords
- web
- dryer
- drying
- airborne
- infrared
- 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.)
- Abandoned
Links
- 238000001035 drying Methods 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 31
- 238000007603 infrared drying Methods 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 230000005855 radiation Effects 0.000 abstract description 15
- 238000007664 blowing Methods 0.000 abstract description 9
- 239000000123 paper Substances 0.000 description 16
- 239000011248 coating agent Substances 0.000 description 13
- 238000000576 coating method Methods 0.000 description 12
- 238000001704 evaporation Methods 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 238000010276 construction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000007605 air drying Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000011087 paperboard Substances 0.000 description 1
- 230000000191 radiation effect Effects 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- D21F5/001—Drying webs by radiant heating
- D21F5/002—Drying webs by radiant heating from infrared-emitting elements
-
- 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
-
- 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
- D21F5/20—Waste heat recovery
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
- D21H25/04—Physical treatment, e.g. heating, irradiating
- D21H25/06—Physical treatment, e.g. heating, irradiating of impregnated or coated paper
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
- F26B3/283—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun in combination with convection
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Textile Engineering (AREA)
- Drying Of Solid Materials (AREA)
- Paper (AREA)
Abstract
METHOD FOR CONTACT-FREE DRYING
OF A PAPER OR BOARD WEB
ABSTRACT OF THE DISCLOSURE
A method for contact-free drying of a paper or board web (W). In the method both infrared radiation and drying air jets are used for drying, the web (W) moving through the dryer (10, 20) being, at the same time, supported free of contact with the dryer by means of the drying air jets. In the method the web (W) is first passed into an infrared drying gap or gaps (10VA, 10VB) and thereupon into an airborne web drying gap (20V). In the method the infrared radiators 105 in the infrared drying unit or units (10A, 10B) are cooled by means of air flows (FAin, FBin). In the method, before the airborne web dryer (20), an infrared dryer unit or units (10A, 10B) is/are used that are closed in such a way that cooling air is not, at least not to a substantial extent, passed into the infrared drying gap (10VA, 10VB). The drying cooling air which has been heated in the closed air circulation in the infrared drying unit or units (10A, 10B) is conducted through the nozzles (251, 252) of the airborne web dryer (20) following after the infrared dryer to constitute drying and supporting air blowings in the drying gap (20V) in the airborne web dryer, The thermal energy (Q) recovered in the cooling air of the infrared dryer (10) is substantially completely conducted to the airborne web dryer (20) to constitute heating energy at the side (302) of the airborne web dryer (20) which side (302) is placed at the dry side opposite to the coated wet side (P) of the web (W) to be dried.
OF A PAPER OR BOARD WEB
ABSTRACT OF THE DISCLOSURE
A method for contact-free drying of a paper or board web (W). In the method both infrared radiation and drying air jets are used for drying, the web (W) moving through the dryer (10, 20) being, at the same time, supported free of contact with the dryer by means of the drying air jets. In the method the web (W) is first passed into an infrared drying gap or gaps (10VA, 10VB) and thereupon into an airborne web drying gap (20V). In the method the infrared radiators 105 in the infrared drying unit or units (10A, 10B) are cooled by means of air flows (FAin, FBin). In the method, before the airborne web dryer (20), an infrared dryer unit or units (10A, 10B) is/are used that are closed in such a way that cooling air is not, at least not to a substantial extent, passed into the infrared drying gap (10VA, 10VB). The drying cooling air which has been heated in the closed air circulation in the infrared drying unit or units (10A, 10B) is conducted through the nozzles (251, 252) of the airborne web dryer (20) following after the infrared dryer to constitute drying and supporting air blowings in the drying gap (20V) in the airborne web dryer, The thermal energy (Q) recovered in the cooling air of the infrared dryer (10) is substantially completely conducted to the airborne web dryer (20) to constitute heating energy at the side (302) of the airborne web dryer (20) which side (302) is placed at the dry side opposite to the coated wet side (P) of the web (W) to be dried.
Description
2~
..
gO-~50 N~T~OD ~OR oONTACT-YR~R DRYING
OF A PAP~R OR BOARD ~B
BACKGRCUND OF T~ IXV~NTIO~
The invention concerns a method for contact-free drying of a paper or board web, in which method both infrared radiation and drying air jets are used for drying, the web moving through the dryer being, at the same time, supported free of contact with the dryer, most appropriately from two sides, by means of these drying air jets, in which method the web is first passed into an infrared drying gap of gaps and thereupon into an airborne web drying gap and in which method the infrared radiators in the infrared drying unit or units are cooled by means of air flows, in which method, before the airborne web dryer, an infrared dryer unit or units is/are used that are closed in such a way that cooling air is not, at least not to a substantial extent, passed into the infrared drying gap, and wherein the dry cooling air which has been heated in ~he closed air - - -circulation in the infrared drying unit or units is passed through --the nozzles of the airborne or floating web dryer following after the infrared dryer to constitute drying and supporting air blowings in the drying gap in the airborne web dryer.
The present invention~relates to the drying of a paper web, paperboard web, or of any other, corresponding moving web. A typical application of the invention is the drying of the paper web in connection with its coating or surface sizing.
` In the prior art, so-called airborne web dryers are known, wherein a paper web, board web or equivalent is dried free of contact. Airborne web dryers are used, e.g., in paper coating devices after a blade, or roll or spread coater to support and todry the web that is wet with the coating agent, free of contact. In .. . .
-1- , ~ 3 ~.3 ~
airborne web dryers, different blow nozzles for the drying and supporting air as well as arrangements of the nozzles are applied.
These blow nozzles can be divided into two groups, i.e. positive pressure or float nozzles and negative pressure or foil nozzles, both of which types of nozzles can be applied in the method of the invention.
The prior art airborne web dryers that are used most commonly are based exclusively on air blows. It is partly for this reason that the airborne web dryer becomes quite large because the drying distance of the airborne web dryer must be relatively long in order that a sufficiently high drying capacity can be obtained. This is a partial reason for the drawbacX that in air drying the depth of penetration of the drying remains relatively low.
In the prior art, various dryers are known which are based on the effect of radiation~ in particular of infrared radiation. The use of infrared radiation provides the advantage that the radiation has a relatively high depth of penetration, which is increased when the wavelength becomes shorter. The use of infrared dryers in the drying of paper webs has been hampered, however, by the risk of fire, ,;",~
because the temperatures in infrared radiators become quite high, for example 2000C, in order to obtain a drying radiation with a sufficiently short wavelength.
Electric infrared dryers when used by themselves are also relatively expensive due to the relatively high cost of electric energy, as compared, e.g., with natural gas.
In paper coating stations, including on-machine coating stations, separate infrared dryers have been used whose drying is based exclusively on the radiation effect. However, insufficient 2~2~
adjustability of paper quality and evaporation has been obtainable with these infrared dryers. Moreover, the drying process becomes highly dependent on the operative quality of the infrared dryer.
With respect to the prior art most closely related to the present invention, reference is made to the Applicant's FI Patent No.
77,707, wherein a combined infrared-airborne web dryer, hereinafter to be referred to as "turbo-infra", is described, wherein it is considered novel that in the method, before the airborne web dryer, an infrared dryer unit or units is/are used that are closed in such a way that cooling air is not, at least not to a substantial extend, conducted into the infrared drying gap, and wherein the dry cooling air which has been heated in the closed air circulation in the infrared drying unit or units is passed through the nozzles of the airborne web dryer following after the infrared dryer to constitute drying and/or supporting air blowings in the drying gap in the airborne web dryer.
In the "turbo-infra" described in the aforementioned FI
Patent, the warm drying air passed into the airborne dryer has been heated to about 120C by blowing it through the infra dryer. The drying energy of the airborne dryer is derived from the wasted cooling energy of the infra unit, which can be recovered by utilizing it in the airborne unit. In this way it has been possible to improve the low efficiency of the infra unit, and the evaporation energy of the airborne unit does not have to be produced, at least not exclusively, by means of a separate steam or gas heater. By means of the low pressure steam available at paper mills, approximately the ;
same air temperature is achieved in the airborne unit as by using the cooling air from the infra unit. By means of high pressure steam and a gas burner, a temperature of 200 to 300C is reached. By means of separate burners or by means of heat exchangers, it is possible to -2 . ~ 2 ~ r 3 regulate the blow rate of air within quite a wide range. The "turbo-infra" itself does not permit a corresponding freedom to regulate the blow rate, but the construction of the infra imposes certain limitations on an increase of the blow rate or, more accurately, of the volumetric flow rate (m3/sec). In the radiator module the cooling air passes between an infra lamp and a shield glass. The glass does not tolerate a difference in pressure beyond a certain value between the inside and the outside and, since the pressure must be limited, the blow rate (volumetric flow) is also limited.
8UNHARY OF TH~ INVENTION
An object of the invention is to provide such a method for contact free drying of paper or board webs by utilizing infra-airborne dryers in such a manner that the flow rate of air is ~ r adjustable over a wide range without the need for separate burners or heat exchangers.
Another object of the invention it to provide such a method whereby the rate of production of a coating machine can be increased without costly investments in separate burners or heat exchangers.
A further object is to reduce the consumption of energy, i.e. to increase the efficiency of the infra-airborne dryer.
With a view to achieving the objects stated above and those that will become apparent hereinafter, the in~ention has as a primary ~ -feature the thermal energy recovered in the cooling air of the infrared dryer being substantially completely conducted to the ~
airborne web dryer to constitute heating energy at the side of the -airborne web dryer which side is placed facing the dry side opposite to the coated wet side of the web.
In the present invention the infrared drying unit or units is/are connected with an airborne web dryer, wherein, as the drying ,-~
. ' - 2~2~ .3;~
and supporting air, the cooling air from infra radiators and from other components placed at their proximity is utilized, which air being both dry and hot is particularly suitable for drying webs. In the present invention, an advantageous combination of an infra unit and an airborne dryer unit is carried into effect, being advantageous in particular with respect to energy economy.
BRIF~_DE8CRIPTION OF T~ DRA~IN~8 In the following, the invention will be described in detail with reference to a preferred embodiment of the invention illustrated in the Figures in the accompanying drawing, the invention not being confined to the details of this embodiment.
Figures lA and lB are schematical illustrations of airborne web dryers which constitute a starting point of the invention.
Figure 2A illustrates an infra-airborne dryer provided with a prior-art circulation of air and constituting a starting point of the invention.
Figure 2B is a schematical illustration of an infra-airborne dryer provided with an air circulation in accordance with the method of the invention.
Figure 3 is a more detailed illustration of a preferred embodiment of the invention.
D~8CRIPTION OF T~F PR~FFRR8D ~BODI~ENTS
Referring to Figs. lA, lB, 2A, and 2B, the principal fetures of the construction and operation of various airborne web dryers and infra-airborne dryers, which are partly known in the prior art and which constitute a starting point of the invention, will be described.
Figs. lA and lB show an airborne web dryer 20, in which the web W, whose side which is denoted by the arrow P is coated and wet, passes through the drying gap 20V defined by two opposite halves. In 2~2~al~
Figs. lA and lB the overall heating energy indicated for the airborne web dryer 20 is denoted with Q.
Figs. 2A and 2B illustrate the principle of the construction of an integrated infra-airborne dryer. The airborne web dryer 20 is connected with an infra dryer, through whose contact-free treatment gap lOV the web runs into the treatment gap 20V in the airborne web dryer 20. The infra unit lo comprises a radiation unit loS, in which an infrared radiation power is formed electrically, this radiation power being applied to the web W, which passes through the treatment . ~ . .. ,,,. . ,"~
gap lOV, as a relatively high energy impulse. In the infra unit 10, at the side of the web opposite to the radiation unit 10S, there is a reflector unit lOR, which returns the radiation to the web W. Fig.
2A shows a prior art air circulation arrangement for an infra-airborne dryer, and with respect to the details of said air circulation arrangement reference is made to the Applicant's said FI
Patent 77,707. Fig. 2B illustrates an air circulation arrangement in accordance with the present invention. In Figs. 2A and 2B, the -~
thermal energy recovered in the cooling air of the infra unit 10 is denoted with Q. The denotation QIR represents the electric power supplied to the infra unit 10. -In tests carried out by the Applicant with an airborne web dryer it has been noticed that the water present in the coating paste on the paper W surface attempts to escape from heat. First, with an airborne web dryer 20 in accordance with Fig. lA, the web W was ~
heated so that the same conditions prevailed in each half of the ~ .
airborne unit, i.e. the same thermal energy l/2 Q was blown onto the coated wet side P of the paper W and onto the opposite dry side. In this way, for the airborne web dryer, an evaporation output was obtained which is denoted with 100%. In accordance with Fig. lB, when unheated air was blown (Lin) into the half of the airborne web / ::
h ~ 3 dryer 20 placed at the coated wet side P of the web W and when the conditions at the other side were kept unchanged (Fig. lA), the heating capacity was lowered by one half, i.e. to 50%, but the evaporation capacity to 70% only. In the former case of Fig. lA, the ratio of evaporation capacity to heating energy is 100/100 = 1, and in the latter case of Fig. lB 70/50 = 1.4, i.e. 40% higher.
In the invention, the observation described above is applied to the turbo-infra, whereby the efficiency of its airborne unit can be improved by about 40%. To permit this, in the invention, instead of the arrangement of Fig. 2A, the heated cooling air coming from the infra unit 10 is blown, as is shown in Fig. 2B, substantially exclusively into the half of the airborne web dryer 20 that is placed at the dry side of the paper W. The part of the airborne unit placed at the wet side P of the paper is provided with a separate cold -~
circulation Lin-LoUt~ In this way the volumetric flow (m3/sec) in the hot half becomes about double whereas the temperature remains -unchanged. Thus, the thermal energy of the air in the hot half corresponds to an airborne capacity of 200% and to an evaporation capacity of 70%. i.e. 0.7 x 2 = 1.4.
By means of the present invention the production rate of the coating machine can be increased without investments in expensive drying equipment. It is necessary to pay for a separate air circulation for the cold airborne web dryer half, but considerable economies are obtained in operating costs.
Fig. 3 is a more detailed illustration of an infra-airborne dryer in accordance with the invention.
As background it should be stated initially that the ~nvention is suitable for use in connection with the coating of papers of which only one side P of the web is coated. The invention is also suitable for two sided coating in connection with drying, but 2 ~ fJ ~
in such a case the coating of the different sides must be carried out at different stages, and in such a case the coating e~uipment may include two infra-airborne dryers in accordance with Fig. 3 placed one after the other, a coating station for the other side, that is for the lower side of the web in the case of Fig. 3, being placed between the dryers.
The combined infra-airborne dryer illustrated in Fig. 3 comprises an infra dryer 10, which has two infra dryer units lOA and lOB, through whose treatment gaps lOVA and lOVB the paper web W
sequentially runs. The infra units lOA,lOB are, substantially directly or after a short distance E, followed by an airborne web dryer 20, through whose treatment gap 20V the web W, which is supported free of contact and which is dried at the same time, runs.
The run of the web W through the infra-airborne dryer is illustrated in Fig. 3 by the dotted-dashed line Win-WOUt.
In Fig. 3, the infra units lOA and lOB are electrically operating units known per se wherein there is an upper radiation unit lOS and an opposite counter-reflector unit lOR, which returns the radiation that has passed through the web W into the treatment gap lOVA and lOVB. The electrically operating infra radiators lOS in the infra units 101 must be cooled so that their temperature does not become excessively high in view of their strength. The cooling air is introduced through the duct 17, which includes, in the direction of intake Fin of the air, first a filter unit 11, a regulator grating 12, and a blower 13. The air inlet duct 17 communicates through the ducts 16A and 16B with the nozzle unîts 14A and 14B, : .
through which, when necessary, the follow up flows FSA and F
are blown into the treatment gaps lOVA and lOVB at both sides of the web W. In the nozzle units 14A and 14B that precede the infra units lOA and lOB there are Coanda nozzles as blow nozzles, which are ~ ~h ~
followed by carrier faces, between which the web W runs under stable support by the follow up blowings FSA and FSB.
In the manner shown in Figs. 2A, 2B and 3, the run of the web W is horizontal as it runs first through the treatment gaps lOVA and lOVB in the infra units lOA and lOB and thereupon through the treatment gap 20V in the airborne web dryer 20. The run of the web W may also be vertical or inclined.
As is shown in Fig. 3, the cooling air blown into the radiation units lOS is not blown into the treatment gaps lOVA and lOVB, but the circulation of the cooling air is closed in this respect. The cooling air which has become warm in connection with the radiators (not shown) in the units lOC is taken out of the units lOS through the air ducts 18A and 18B as flows FA and FB. The air system includes regulator dampers and gratings 19, by whose means the air quantities can be set and adjusted. The flows FA and FB
are connected to the duct 18 and, being sucked by the blower 21, are ~;
passed to the duct 22, wherein there is a branch part 22a, through which any air that is excessive for the airborne web unit 20 can, when necessary, be blown out of the infra-airborne dryer as the ;~
output flow FoUt~
As is shown in Fig. 3, the duct 22 is connected to the intake side of the gas burner 23. The gas burner 23 is not generally ~;
necessary, since, as a rule, the cooling air from the infra dryer 10 ~
is sufficient for the intake air of the airborne web dryer 20. From -the outlet side of the gas burner 23, a duct 242 is connected to -~
the lower box 32 of the air-borne web dryer 20 so that the thermal energy Q recovered from the cooling air of the infra dryer is utilized completely for the drying energy of the dry side of the web W, opposite to the wet and coated side P of the web W. If there is no gas burner 23, the duct 22 communicates directly with the duct h f~ 5 "r 242. Cold circulation air Lin is conducted as the flow FCl into the upper space 301 in the airborne web dryer 20 through the duct 241 and through the related nozzles 251. Through the duct 242 the flows FC2 are conducted into the lower nozzles 252 in the nozzle box 302 and through them into the treatment gap 20V to both sides of the web W to constitute drying and supporting air for the airborne web dryer 20. Out of the treatment gap 20V the cooled and moistened air is conducted through the ducts 261 and 262 as the flows FDl and FD2, and the exhaust air is collected into the duct 27.
The airborne web dryer 20 shown in Fig. 3 consists of boxes 301 placed at opposite sides of the web W. The nozzle boxes 301, 32 are pro~ided with planar carrier faces, which operate as carrier faces with positive pressure or with negative pressure, the drying and/or supporting blowings FCl and FC2 being conducted to these faces through nozzles, most appropriately Coanda nozzles 2 and 252. Out of the gaps between the nozzle boxes 301 and 32 the flows FDl and FD2 are conducted, which are collected from the interior of the boxes 301 and 32 into the duct 27.
The moist and cooled air is conducted as the flow Fo through the regulator grating 29 to the intake side of the exhaust air blower 28, and from the pressure side of the blower 28 the air is -blown out as the flow FoUt~
The length E of the distance between the infra dryer lo and the airborne web dryer 20 is not critical in the invention, but the dryers 10 and 20 are preferably placed as close to each other as possible so that at least part of the follow up blowings FSA and FSB, which have become warm in the treatment gaps lOVA and lOVB
in the units lOA and lOB, follow along with the web W on its run WO
and enter along with the web W into the treatment gap 20V in the - 2~ a~
airborne web dryer 20. These flows are illustrated by the arrows Fo~
As is shown in Fig. 3, cold air, which has been introduced through the intake duct 17, is passed through the ducts 16A and 16B ;
to constitute follow up blowings FSA and FSB for the web Win.
Another, alternative possibility is to take the air flows from these follow up blowings out of the air duct 18 or ducts 18A and/or 18B, in which the dry air flows that has been heated in the infra units 10A
and 10B.
In the infra units 10A and 10B a drying energy pulse of relatively short duration is applied to the web W, whose drying -capa~ity per unit of air is preferably substantially higher ~han the average drying capacity of the dryer. The water vaporized by this energy pulse in the web W is liberated from the web W substantially only in the drying gap 20V in the airborne web dryer 20, where the web W is flushed at the same time as it is supported by means of dry `~ air jets.
`~ Fig. 3 shows two infra units 10A and 10B placed one after ~ -the other. It is understood that within the scope of the invention there may be only one infra unit, or it is also possible to employ more than two units placed one after the other.
The scope of the invention also includes applications in which ~ome minor amount of the cooling energy ~ recovered from the infra dryer is also passed into the airborne box at the coated side P
of the web W to constitute supporting and drying air for the web. In such a case, in Fig. 3, out of the ducts 22 or 242 a connecting duct provided with a throttle may be conducted into the duct 241.
Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings.
h ~2 ~ 3 It is therefore to be understood that, within the scope of the claims :
appended hereto, the invention may be practiced otherwise than as specifically disclosed herein.
, ~ ~ ' , . ', , ~ .
..
gO-~50 N~T~OD ~OR oONTACT-YR~R DRYING
OF A PAP~R OR BOARD ~B
BACKGRCUND OF T~ IXV~NTIO~
The invention concerns a method for contact-free drying of a paper or board web, in which method both infrared radiation and drying air jets are used for drying, the web moving through the dryer being, at the same time, supported free of contact with the dryer, most appropriately from two sides, by means of these drying air jets, in which method the web is first passed into an infrared drying gap of gaps and thereupon into an airborne web drying gap and in which method the infrared radiators in the infrared drying unit or units are cooled by means of air flows, in which method, before the airborne web dryer, an infrared dryer unit or units is/are used that are closed in such a way that cooling air is not, at least not to a substantial extent, passed into the infrared drying gap, and wherein the dry cooling air which has been heated in ~he closed air - - -circulation in the infrared drying unit or units is passed through --the nozzles of the airborne or floating web dryer following after the infrared dryer to constitute drying and supporting air blowings in the drying gap in the airborne web dryer.
The present invention~relates to the drying of a paper web, paperboard web, or of any other, corresponding moving web. A typical application of the invention is the drying of the paper web in connection with its coating or surface sizing.
` In the prior art, so-called airborne web dryers are known, wherein a paper web, board web or equivalent is dried free of contact. Airborne web dryers are used, e.g., in paper coating devices after a blade, or roll or spread coater to support and todry the web that is wet with the coating agent, free of contact. In .. . .
-1- , ~ 3 ~.3 ~
airborne web dryers, different blow nozzles for the drying and supporting air as well as arrangements of the nozzles are applied.
These blow nozzles can be divided into two groups, i.e. positive pressure or float nozzles and negative pressure or foil nozzles, both of which types of nozzles can be applied in the method of the invention.
The prior art airborne web dryers that are used most commonly are based exclusively on air blows. It is partly for this reason that the airborne web dryer becomes quite large because the drying distance of the airborne web dryer must be relatively long in order that a sufficiently high drying capacity can be obtained. This is a partial reason for the drawbacX that in air drying the depth of penetration of the drying remains relatively low.
In the prior art, various dryers are known which are based on the effect of radiation~ in particular of infrared radiation. The use of infrared radiation provides the advantage that the radiation has a relatively high depth of penetration, which is increased when the wavelength becomes shorter. The use of infrared dryers in the drying of paper webs has been hampered, however, by the risk of fire, ,;",~
because the temperatures in infrared radiators become quite high, for example 2000C, in order to obtain a drying radiation with a sufficiently short wavelength.
Electric infrared dryers when used by themselves are also relatively expensive due to the relatively high cost of electric energy, as compared, e.g., with natural gas.
In paper coating stations, including on-machine coating stations, separate infrared dryers have been used whose drying is based exclusively on the radiation effect. However, insufficient 2~2~
adjustability of paper quality and evaporation has been obtainable with these infrared dryers. Moreover, the drying process becomes highly dependent on the operative quality of the infrared dryer.
With respect to the prior art most closely related to the present invention, reference is made to the Applicant's FI Patent No.
77,707, wherein a combined infrared-airborne web dryer, hereinafter to be referred to as "turbo-infra", is described, wherein it is considered novel that in the method, before the airborne web dryer, an infrared dryer unit or units is/are used that are closed in such a way that cooling air is not, at least not to a substantial extend, conducted into the infrared drying gap, and wherein the dry cooling air which has been heated in the closed air circulation in the infrared drying unit or units is passed through the nozzles of the airborne web dryer following after the infrared dryer to constitute drying and/or supporting air blowings in the drying gap in the airborne web dryer.
In the "turbo-infra" described in the aforementioned FI
Patent, the warm drying air passed into the airborne dryer has been heated to about 120C by blowing it through the infra dryer. The drying energy of the airborne dryer is derived from the wasted cooling energy of the infra unit, which can be recovered by utilizing it in the airborne unit. In this way it has been possible to improve the low efficiency of the infra unit, and the evaporation energy of the airborne unit does not have to be produced, at least not exclusively, by means of a separate steam or gas heater. By means of the low pressure steam available at paper mills, approximately the ;
same air temperature is achieved in the airborne unit as by using the cooling air from the infra unit. By means of high pressure steam and a gas burner, a temperature of 200 to 300C is reached. By means of separate burners or by means of heat exchangers, it is possible to -2 . ~ 2 ~ r 3 regulate the blow rate of air within quite a wide range. The "turbo-infra" itself does not permit a corresponding freedom to regulate the blow rate, but the construction of the infra imposes certain limitations on an increase of the blow rate or, more accurately, of the volumetric flow rate (m3/sec). In the radiator module the cooling air passes between an infra lamp and a shield glass. The glass does not tolerate a difference in pressure beyond a certain value between the inside and the outside and, since the pressure must be limited, the blow rate (volumetric flow) is also limited.
8UNHARY OF TH~ INVENTION
An object of the invention is to provide such a method for contact free drying of paper or board webs by utilizing infra-airborne dryers in such a manner that the flow rate of air is ~ r adjustable over a wide range without the need for separate burners or heat exchangers.
Another object of the invention it to provide such a method whereby the rate of production of a coating machine can be increased without costly investments in separate burners or heat exchangers.
A further object is to reduce the consumption of energy, i.e. to increase the efficiency of the infra-airborne dryer.
With a view to achieving the objects stated above and those that will become apparent hereinafter, the in~ention has as a primary ~ -feature the thermal energy recovered in the cooling air of the infrared dryer being substantially completely conducted to the ~
airborne web dryer to constitute heating energy at the side of the -airborne web dryer which side is placed facing the dry side opposite to the coated wet side of the web.
In the present invention the infrared drying unit or units is/are connected with an airborne web dryer, wherein, as the drying ,-~
. ' - 2~2~ .3;~
and supporting air, the cooling air from infra radiators and from other components placed at their proximity is utilized, which air being both dry and hot is particularly suitable for drying webs. In the present invention, an advantageous combination of an infra unit and an airborne dryer unit is carried into effect, being advantageous in particular with respect to energy economy.
BRIF~_DE8CRIPTION OF T~ DRA~IN~8 In the following, the invention will be described in detail with reference to a preferred embodiment of the invention illustrated in the Figures in the accompanying drawing, the invention not being confined to the details of this embodiment.
Figures lA and lB are schematical illustrations of airborne web dryers which constitute a starting point of the invention.
Figure 2A illustrates an infra-airborne dryer provided with a prior-art circulation of air and constituting a starting point of the invention.
Figure 2B is a schematical illustration of an infra-airborne dryer provided with an air circulation in accordance with the method of the invention.
Figure 3 is a more detailed illustration of a preferred embodiment of the invention.
D~8CRIPTION OF T~F PR~FFRR8D ~BODI~ENTS
Referring to Figs. lA, lB, 2A, and 2B, the principal fetures of the construction and operation of various airborne web dryers and infra-airborne dryers, which are partly known in the prior art and which constitute a starting point of the invention, will be described.
Figs. lA and lB show an airborne web dryer 20, in which the web W, whose side which is denoted by the arrow P is coated and wet, passes through the drying gap 20V defined by two opposite halves. In 2~2~al~
Figs. lA and lB the overall heating energy indicated for the airborne web dryer 20 is denoted with Q.
Figs. 2A and 2B illustrate the principle of the construction of an integrated infra-airborne dryer. The airborne web dryer 20 is connected with an infra dryer, through whose contact-free treatment gap lOV the web runs into the treatment gap 20V in the airborne web dryer 20. The infra unit lo comprises a radiation unit loS, in which an infrared radiation power is formed electrically, this radiation power being applied to the web W, which passes through the treatment . ~ . .. ,,,. . ,"~
gap lOV, as a relatively high energy impulse. In the infra unit 10, at the side of the web opposite to the radiation unit 10S, there is a reflector unit lOR, which returns the radiation to the web W. Fig.
2A shows a prior art air circulation arrangement for an infra-airborne dryer, and with respect to the details of said air circulation arrangement reference is made to the Applicant's said FI
Patent 77,707. Fig. 2B illustrates an air circulation arrangement in accordance with the present invention. In Figs. 2A and 2B, the -~
thermal energy recovered in the cooling air of the infra unit 10 is denoted with Q. The denotation QIR represents the electric power supplied to the infra unit 10. -In tests carried out by the Applicant with an airborne web dryer it has been noticed that the water present in the coating paste on the paper W surface attempts to escape from heat. First, with an airborne web dryer 20 in accordance with Fig. lA, the web W was ~
heated so that the same conditions prevailed in each half of the ~ .
airborne unit, i.e. the same thermal energy l/2 Q was blown onto the coated wet side P of the paper W and onto the opposite dry side. In this way, for the airborne web dryer, an evaporation output was obtained which is denoted with 100%. In accordance with Fig. lB, when unheated air was blown (Lin) into the half of the airborne web / ::
h ~ 3 dryer 20 placed at the coated wet side P of the web W and when the conditions at the other side were kept unchanged (Fig. lA), the heating capacity was lowered by one half, i.e. to 50%, but the evaporation capacity to 70% only. In the former case of Fig. lA, the ratio of evaporation capacity to heating energy is 100/100 = 1, and in the latter case of Fig. lB 70/50 = 1.4, i.e. 40% higher.
In the invention, the observation described above is applied to the turbo-infra, whereby the efficiency of its airborne unit can be improved by about 40%. To permit this, in the invention, instead of the arrangement of Fig. 2A, the heated cooling air coming from the infra unit 10 is blown, as is shown in Fig. 2B, substantially exclusively into the half of the airborne web dryer 20 that is placed at the dry side of the paper W. The part of the airborne unit placed at the wet side P of the paper is provided with a separate cold -~
circulation Lin-LoUt~ In this way the volumetric flow (m3/sec) in the hot half becomes about double whereas the temperature remains -unchanged. Thus, the thermal energy of the air in the hot half corresponds to an airborne capacity of 200% and to an evaporation capacity of 70%. i.e. 0.7 x 2 = 1.4.
By means of the present invention the production rate of the coating machine can be increased without investments in expensive drying equipment. It is necessary to pay for a separate air circulation for the cold airborne web dryer half, but considerable economies are obtained in operating costs.
Fig. 3 is a more detailed illustration of an infra-airborne dryer in accordance with the invention.
As background it should be stated initially that the ~nvention is suitable for use in connection with the coating of papers of which only one side P of the web is coated. The invention is also suitable for two sided coating in connection with drying, but 2 ~ fJ ~
in such a case the coating of the different sides must be carried out at different stages, and in such a case the coating e~uipment may include two infra-airborne dryers in accordance with Fig. 3 placed one after the other, a coating station for the other side, that is for the lower side of the web in the case of Fig. 3, being placed between the dryers.
The combined infra-airborne dryer illustrated in Fig. 3 comprises an infra dryer 10, which has two infra dryer units lOA and lOB, through whose treatment gaps lOVA and lOVB the paper web W
sequentially runs. The infra units lOA,lOB are, substantially directly or after a short distance E, followed by an airborne web dryer 20, through whose treatment gap 20V the web W, which is supported free of contact and which is dried at the same time, runs.
The run of the web W through the infra-airborne dryer is illustrated in Fig. 3 by the dotted-dashed line Win-WOUt.
In Fig. 3, the infra units lOA and lOB are electrically operating units known per se wherein there is an upper radiation unit lOS and an opposite counter-reflector unit lOR, which returns the radiation that has passed through the web W into the treatment gap lOVA and lOVB. The electrically operating infra radiators lOS in the infra units 101 must be cooled so that their temperature does not become excessively high in view of their strength. The cooling air is introduced through the duct 17, which includes, in the direction of intake Fin of the air, first a filter unit 11, a regulator grating 12, and a blower 13. The air inlet duct 17 communicates through the ducts 16A and 16B with the nozzle unîts 14A and 14B, : .
through which, when necessary, the follow up flows FSA and F
are blown into the treatment gaps lOVA and lOVB at both sides of the web W. In the nozzle units 14A and 14B that precede the infra units lOA and lOB there are Coanda nozzles as blow nozzles, which are ~ ~h ~
followed by carrier faces, between which the web W runs under stable support by the follow up blowings FSA and FSB.
In the manner shown in Figs. 2A, 2B and 3, the run of the web W is horizontal as it runs first through the treatment gaps lOVA and lOVB in the infra units lOA and lOB and thereupon through the treatment gap 20V in the airborne web dryer 20. The run of the web W may also be vertical or inclined.
As is shown in Fig. 3, the cooling air blown into the radiation units lOS is not blown into the treatment gaps lOVA and lOVB, but the circulation of the cooling air is closed in this respect. The cooling air which has become warm in connection with the radiators (not shown) in the units lOC is taken out of the units lOS through the air ducts 18A and 18B as flows FA and FB. The air system includes regulator dampers and gratings 19, by whose means the air quantities can be set and adjusted. The flows FA and FB
are connected to the duct 18 and, being sucked by the blower 21, are ~;
passed to the duct 22, wherein there is a branch part 22a, through which any air that is excessive for the airborne web unit 20 can, when necessary, be blown out of the infra-airborne dryer as the ;~
output flow FoUt~
As is shown in Fig. 3, the duct 22 is connected to the intake side of the gas burner 23. The gas burner 23 is not generally ~;
necessary, since, as a rule, the cooling air from the infra dryer 10 ~
is sufficient for the intake air of the airborne web dryer 20. From -the outlet side of the gas burner 23, a duct 242 is connected to -~
the lower box 32 of the air-borne web dryer 20 so that the thermal energy Q recovered from the cooling air of the infra dryer is utilized completely for the drying energy of the dry side of the web W, opposite to the wet and coated side P of the web W. If there is no gas burner 23, the duct 22 communicates directly with the duct h f~ 5 "r 242. Cold circulation air Lin is conducted as the flow FCl into the upper space 301 in the airborne web dryer 20 through the duct 241 and through the related nozzles 251. Through the duct 242 the flows FC2 are conducted into the lower nozzles 252 in the nozzle box 302 and through them into the treatment gap 20V to both sides of the web W to constitute drying and supporting air for the airborne web dryer 20. Out of the treatment gap 20V the cooled and moistened air is conducted through the ducts 261 and 262 as the flows FDl and FD2, and the exhaust air is collected into the duct 27.
The airborne web dryer 20 shown in Fig. 3 consists of boxes 301 placed at opposite sides of the web W. The nozzle boxes 301, 32 are pro~ided with planar carrier faces, which operate as carrier faces with positive pressure or with negative pressure, the drying and/or supporting blowings FCl and FC2 being conducted to these faces through nozzles, most appropriately Coanda nozzles 2 and 252. Out of the gaps between the nozzle boxes 301 and 32 the flows FDl and FD2 are conducted, which are collected from the interior of the boxes 301 and 32 into the duct 27.
The moist and cooled air is conducted as the flow Fo through the regulator grating 29 to the intake side of the exhaust air blower 28, and from the pressure side of the blower 28 the air is -blown out as the flow FoUt~
The length E of the distance between the infra dryer lo and the airborne web dryer 20 is not critical in the invention, but the dryers 10 and 20 are preferably placed as close to each other as possible so that at least part of the follow up blowings FSA and FSB, which have become warm in the treatment gaps lOVA and lOVB
in the units lOA and lOB, follow along with the web W on its run WO
and enter along with the web W into the treatment gap 20V in the - 2~ a~
airborne web dryer 20. These flows are illustrated by the arrows Fo~
As is shown in Fig. 3, cold air, which has been introduced through the intake duct 17, is passed through the ducts 16A and 16B ;
to constitute follow up blowings FSA and FSB for the web Win.
Another, alternative possibility is to take the air flows from these follow up blowings out of the air duct 18 or ducts 18A and/or 18B, in which the dry air flows that has been heated in the infra units 10A
and 10B.
In the infra units 10A and 10B a drying energy pulse of relatively short duration is applied to the web W, whose drying -capa~ity per unit of air is preferably substantially higher ~han the average drying capacity of the dryer. The water vaporized by this energy pulse in the web W is liberated from the web W substantially only in the drying gap 20V in the airborne web dryer 20, where the web W is flushed at the same time as it is supported by means of dry `~ air jets.
`~ Fig. 3 shows two infra units 10A and 10B placed one after ~ -the other. It is understood that within the scope of the invention there may be only one infra unit, or it is also possible to employ more than two units placed one after the other.
The scope of the invention also includes applications in which ~ome minor amount of the cooling energy ~ recovered from the infra dryer is also passed into the airborne box at the coated side P
of the web W to constitute supporting and drying air for the web. In such a case, in Fig. 3, out of the ducts 22 or 242 a connecting duct provided with a throttle may be conducted into the duct 241.
Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings.
h ~2 ~ 3 It is therefore to be understood that, within the scope of the claims :
appended hereto, the invention may be practiced otherwise than as specifically disclosed herein.
, ~ ~ ' , . ', , ~ .
Claims (7)
1. A method for contact-free drying of a paper or board web having a coated wet side and an uncoated dry side, said method comprising the steps of:
first passing said web into an infrared drying gap defined by an infrared drying unit;
then passing said web into an airborne web drying gap defined by an airborne web dryer;
conducting cooling air which has been heated by infrared radiators within said infrared heating unit to a portion of said airborne web dryer which faces said uncoated dry side of said web;
and conducting said heated cooling air from said portion of said airborne web dryer to said uncoated dry side of said web.
first passing said web into an infrared drying gap defined by an infrared drying unit;
then passing said web into an airborne web drying gap defined by an airborne web dryer;
conducting cooling air which has been heated by infrared radiators within said infrared heating unit to a portion of said airborne web dryer which faces said uncoated dry side of said web;
and conducting said heated cooling air from said portion of said airborne web dryer to said uncoated dry side of said web.
2. The method of claim 1, further comprising using a separate heating means to further heat said heated cooling air while conducting said heated cooling air from said infrared heating unit to said portion of said airborne web dryer.
3. The method of claim 2, wherein said step of conducting cooling air comprises conducting cooling air which has been heated by said infrared radiators into a first duct in which duct said heated cooling air is conducted to said separate heating means and then conducting said cooling air through a second duct to said portion of said airborne web dryer.
4. The method of claim 2, comprising using a gas burner as said separate heating means.
5. The method of claim 2, comprising using a heat exchanger as said separate heating means.
6. The method of claim 1, further comprising inputting cool air to another portion of said airborne web dryer which faces said coated wet side of said web and then conducting said cool air from said another portion of said airborne web dryer to said coated wet side of said web.
7. The method of claim 1, further comprising passing said web into another infrared drying gap defined by another infrared drying unit, conducting other cooling air which has been heated by infrared radiators within said another infrared heating unit to said portion of said airborne web dryer which faces said uncoated dry side of said web, and conducting said other heated cooling air from said portion of said airborne web dryer to said uncoated dry side of said web.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI894516 | 1989-09-25 | ||
| FI894516A FI82848C (en) | 1989-09-25 | 1989-09-25 | FOERFARANDE FOER KONTAKTFRI TORKNING AV EN PAPPERS- ELLER KARTONGBANA. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026045A1 true CA2026045A1 (en) | 1991-03-26 |
Family
ID=8529045
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026045A Abandoned CA2026045A1 (en) | 1989-09-25 | 1990-09-24 | Method for contact-free drying of a paper or board web |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA2026045A1 (en) |
| DE (1) | DE4029488A1 (en) |
| FI (1) | FI82848C (en) |
| SE (1) | SE9003032L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5771602A (en) * | 1995-10-25 | 1998-06-30 | Valmet Corporation | Method and device for drying a coating on a paper web or equivalent |
| CN103703185A (en) * | 2011-06-21 | 2014-04-02 | 美卓造纸机械公司 | Method and arrangement for improving energy efficiency of drying section of paper machine or like |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2078290A1 (en) * | 1991-10-24 | 1993-04-25 | W.R. Grace & Co.-Conn. | Combination infrared and air flotation dryer |
| FR2775065B1 (en) * | 1998-02-19 | 2000-05-26 | Infra Rouge System | DEVICE FOR THE HEAT TREATMENT OF CONTINUOUSLY MOVING SHEET MATERIALS |
| DE10146032A1 (en) * | 2001-09-18 | 2003-04-03 | Krieger Gmbh & Co Kg | Method and device for drying a running material web, in particular a coated paper or cardboard web |
| FI120983B (en) * | 2006-10-03 | 2010-05-31 | Metso Paper Inc | Method and Arrangement for Improving Drying and Improving Printing Properties of Coated Fiber Web |
| CN103184705B (en) * | 2011-12-31 | 2015-12-09 | 广东侨盛防伪材料有限公司 | A kind of aging machine |
-
1989
- 1989-09-25 FI FI894516A patent/FI82848C/en not_active IP Right Cessation
-
1990
- 1990-09-18 DE DE4029488A patent/DE4029488A1/en not_active Withdrawn
- 1990-09-24 CA CA002026045A patent/CA2026045A1/en not_active Abandoned
- 1990-09-25 SE SE9003032A patent/SE9003032L/en not_active Application Discontinuation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5771602A (en) * | 1995-10-25 | 1998-06-30 | Valmet Corporation | Method and device for drying a coating on a paper web or equivalent |
| CN103703185A (en) * | 2011-06-21 | 2014-04-02 | 美卓造纸机械公司 | Method and arrangement for improving energy efficiency of drying section of paper machine or like |
Also Published As
| Publication number | Publication date |
|---|---|
| SE9003032L (en) | 1991-03-26 |
| DE4029488A1 (en) | 1991-04-04 |
| FI82848C (en) | 1991-04-25 |
| SE9003032D0 (en) | 1990-09-25 |
| FI894516A0 (en) | 1989-09-25 |
| FI82848B (en) | 1991-01-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4936025A (en) | Combination infrared and airborne drying of a web | |
| US4942674A (en) | Method in the drying of a paper web or equivalent | |
| US5009016A (en) | Method for on-machine coating-drying of a paper web or the like | |
| US4854052A (en) | Floater radiation dryer | |
| US4942675A (en) | Apparatus and method for regulating the profile of a paper web passing over a Yankee cylinder in an integrated IR-dryer/Yankee hood | |
| US4882852A (en) | Procedure and means for drying moving web material | |
| US6119362A (en) | Arrangements for impingement drying and/or through-drying of a paper or material web | |
| CA2256615C (en) | Method and device in connection with impingement drying and/or through-drying of a paper web or of an equivalent web-like material | |
| EP0574366B1 (en) | Method and device for intensification of the operation of a Yankee press in a soft-tissue machine | |
| FI78525B (en) | INFRATORK. | |
| CA2026045A1 (en) | Method for contact-free drying of a paper or board web | |
| KR19980703814A (en) | Drying concept and drying method of paper / carton web | |
| EP0870086A1 (en) | Apparatus for drying a fibre web | |
| EP1102889B1 (en) | Method and device for drying of a coated web | |
| WO2000047814A1 (en) | Method and device for drying a fibre web | |
| CA1287092C (en) | Method in the drying of a paper web or equivalent | |
| US3452446A (en) | Apparatus for the ventilation of a paper machine | |
| FI79157C (en) | GASINFRA-SVAEVTORK. | |
| FI75009C (en) | Method and apparatus for contactless drying of a paper web or similar | |
| KR20000005439A (en) | Energy utilizing method and device of drying machine for fiber web |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |