AU612349B2

AU612349B2 - Apparatus for sequentially drying both sides of a paper web

Info

Publication number: AU612349B2
Application number: AU12439/88A
Authority: AU
Inventors: Isao Ohnishi; Osamu Sankoda
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1986-12-02
Filing date: 1987-11-12
Publication date: 1991-07-11
Anticipated expiration: 2007-11-12
Also published as: FI892657A; CN87107232A; AU1243988A; IN168979B; FI960348A0; FI892657A0; JPS6389996U; BR8707946A; CN1013598B; DE334899T1; KR890700180A; PL269182A1; WO1988004206A3; ZA879009B; ATE70868T1; FI960348A; KR940005201B1; EP0334899B1; CA1340582C; DE3775567D1

Description

side of this form for guidance in completing this part *r 4 .1 i= cAj.- ll;c-T 1t-r. s'a-fr- entitled to make this application are as follows:spplicant is assignee of inventors and has the consent of the basic applicant Toclaim priority DECLARED at 7ts ?thiss 19"j

PCT

INTERNATIONAL APPLICAT (51) International Patent Classificatic B21F 5/04 AU-AI-12439/88 WORLD INTELLECTUAL PROPERTY ORGANIZATION International Bureau ION PU SH Ur bER E TE' 3COOPERATION TREATY (PCT) ,n 4 D E R E47TE (11) International Publication Number: A2 (43) International Publication Date: WO 88/04206 16 June 1988 (16.06.88) .21) International Application Number: PCT/US87/03087 (22) International Filing Date: 12 November 1987 (12.11.87) (31) Priority Application Number: 61/185019 (32) Priority Date: (33) Priority Country: 2 December 1986 (02.12.86) (71) Applicant (for all designated States except US): BELOIT CORPORATION [US/US]; I St. Lawrence Avenue, Beloit, WI 53511 (US).

(72) Inventors; and Inventors/Applicants (for US only) :SANKODA, Osamu [JP/JP]; OHNISHI, Isao [JP/JP]; Mihara Works, Mitsubishi Heavy Industries Co., Ltd., 5007, Itozaki-cho, Mihara-shi, Hiroshima-ken (JP).

(74) Agent: ARCHER, David, 1 St. Lawrence Avenue, Beloit, WI 53511 (US).

(81) Designated States: AT (European patent), AU, BE (European patent), BR, CH (European patent), DE (European patent), FI, FR (European patent), GB (European patent), IT (European patent), KR, LU (European patent), NL (European patent), SE (European patent), US.

Published Without international search report and to be republished upon receipt of that report.

AO.J.P, 1 AUG 1988

AUSTRALIAN

3 0 JUN 1988 PATENT

OFFICE

(54) Title: APPARATUS FOR SEQUENTIALLY DRYING BOTH SIDES OF A PAPER WEB (57' Abstract An apparatus (10) for sequentially drying both sides (8A, 9) of a paper web The apparatus includes a first drying roller and a first felt (4A) extends around the first drying roller for heating a first side (8A) of the web (1A).

The first felt (4A) and the web (IA) extend around a first downstream suction roller A first guide roll (5A) guides the first felt (4A) away from the first suction roller and a second suction roller (7A) is disposed adjacent to the first suction roller A second felt extends around the second suction roller (7A) and a second guide roll (12) guides the second felt towards the second suction roller (7A) such that the first and second felts (4A, 4A') define therebetween a web transfer section (14) so that the web (IA) is sandwiched between the felts (4A, 4A') during passage through the transfer section A downstream second drying roller (6A) is disposed such that the web (1A) is sandwiched between the second felt and the second drying roller (6A) for heating a second side of the web (IA).

i WO 88/04206 PCT/US87/03087 1- Apparatus For Sequentially Drying Both Sides Of A Paper Web BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to an apparatus for sequentially drying both sides of a paper web. More particularly, this invention relates to a BEL RUN type drying section in which a first drying section dries one side of the web and then a subsequent drying section dries the opposite side of the web.

INFORMATION DISCLOSURE STATEMENT In a conventional drying section of a BEL RUN type configuration, the single felt section may be.made up of four groups of rollers. Typically, these groups include drying rollers and suction rollers which provide no open draw in their configuration because the paper web is always supported by a dryer felt. As the web pougresses from one group of dryers to the next, the same side of the web is always presented to the successive drying rollers.

However, in order to present the opposite side of the web to a successive drying roller, it has been necessary in the past to transfer an unsupported web to a subsequent dryer felt.

So-called single-felted dryer sections were subsequently utilized in which a joint run of the web and felt WO 88/04206 PCT/US87/03087 -2successively passed around upper and lower dryer drums in a sinusoidal configuration. Although this arrangement provided felt support for the web between successive upper and lower dryer Arums, the lower dryer drums were virtually redundant in that the felt was sandwiched between the web and the drying roller thereby greatly reducing any drying of the web during passage around the lower drying rollers. Furthermore, such single felted sections still did not dry from both sides.

In the aforementioned BEL RUN configurations and single-felted dryers, problems exist in that only one side of the web is dried during passage of the web through the first few groups of dryers. Consequently, such arrangement results in differences in surface strength and properties. Additionally, the smoothness of the respective surfaces of the web differ which is a problem when sheet paper is required in which both sides of the sheet must have similar characteristics. Also, curl and non-uniform response to change in humidity have been problems with the aforementioned dryer sections.

The present invention seeks to overcome the aforementioned problems associated with the BEL RUN and other single-felted dryer section configurations by providing a web transfer section defined by a first and second felt such that the web is sandwiched between the felts during passage through the transfer section so that during movement of the web around a subsequent drying roller, the I ~;*rr:rx yia~S~:~yZ~T~ I r 3 '2 6 *0*e* 155

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opposite side of the web comes into physical contact with the heating surface of the subsequent drying roller.

Therefore, it is a primary object of the present invention to provide an apparatus and a method that overcomes one or more of the aforementioned inadequacies of the prior art proposals and which makes a significant and non-obvious contribution to the paper drying art.

Accordingly the invention provides an apparatus for drying a web, said apparatus comprising a first single tier dryer section having a first plurality of dryer drums rotating in a first direction for drying a first side of the web, said first dryer section including a first plurality of suction rolls rotating in a second direction opposite to said first direction, said suction rolls being disposed between adjacent dryer drums of said first plurality of dryer drums, first dryer felt means for conveying the web in a serpentine path along said dryer drums and said suction rolls, a second single tier dryer section disposed downstream relative to said first dryer section and having a second plurality of dryer drums rotating in said second direction for drying a second side of the web, said second dryer section including a second plurality of suction rolls rotating in Faid first direction and disposed between adjacent dryer drums of said second pluralitiy of dryer drums, second dryer felt means for conveying the web in a serpentine path along said second plurality o. dryer drums, and said second plurality of suction rolls, and means for guiding said first and second felt means in close proximity to each mwspe018/beloit 91 4 12

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C. C :j 4 other between said first and said second dryer sections so as to sandwich the web between said first and said second felt means, said means for guiding include vacuum means operable to apply a vacuum to said web so as to effect a controlled transfer of the web from said first felt means to said second felt means.

The invention also provides a method of drying a web, said method including the steps of: guiding the web through a first single tier dryer section having a first plurality of dryer drums rotating in a first direction for drying a first side of the web, said first dryer section including a first plurality of suction rolls which rotate in a second direction opposite to said first direction, said suction rolls being disposed between adjacent dryer drums of said first plurality of dryer drums; conveying the web contiguously with a first dryer felt means such that the web and said first dryer felt means follow a serpentine path along said dryer drums and said suction rolls; guiding the web through a second single tier dryer section disposed downstream relative to said first dryer section and having a second plurality of dryer drums rotating in said second direction for drying a second side of the web, said second dryer section including a second plurality of suction rolls rotating in said first direction and disposed between adjacent dryer drums of said second plurality of dryer drums; mwspe0l8/beloit 91 4 12

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I I 5 0 a a a conveying the web contiguously with a second dryer felt means such that the web and said second dryer felt means follow a serpentine path along said second plurality of dryer drums and said second plurality of suction rolls; guiding said first and second felt means in close proximity to each other between said first and second dryer sections so as to sandwich the web between said first and second felt means; and drawing a vacuum through said second felt means to effect a controlled transfer of the web from said first felt means to said second felt means.

Although the present invention is described with a certain degree of particularity in the detailed description contained hereinafter, it will be apparent to those skilled in the art that many modifications and variations of the concept of the present invention can be carried out without departing the spirit and scope of the present invention as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side-elevational view of a prior art BEL RUN type drying section showing the first four groups of drying rollers drying a first side of a paper web.

Figure 2 is a side-elevational view of a BEL RUN type drying configuration according to the present invention showing the means for transfering the web without open draw from a first to a second felt, and Figure 3 is an enlarged side-elevational view of figure 2 particularly showing, in detail, the web transfer mwspeOl8/beloit 91 4 12 -6section enabling the opposite side of the web to come into physical contact with a subsequent group of drying rollers.

Similar reference characters refer to similar parts throughout the various figures of the drawings.

son 4 0*0&0: V. mwpS8bli 141 WO 88/04206 PCT/US87/03087 -7 DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a side-elevational view of a conventional BEL RUN type drying section including groups A,B,C and D.

for drying a web of paper 1. As shown in figure 1, the web 1 is guided in sinusoidal configuration around a plurality of drying rollers 2, 2' and 2" and suction transfer rollers 3, 3' and A first felt 4 loops around a plurality of guide rolls 5, and and supports the web 1 as the web moves alternately past drying and suction rollers 3, 2, 3" and A second group B of drying rollers 6, and 6" have suction rollers 7, 7' and 7" disposed alternately therebetween such that a second felt 4' loops around the suction and drying rollers 7, 6, 7" and 6" in sinusoidal configuration. The web 1 is unsupported by the felt 4 as the web 1 supported by the drying roller 2" rotates adjacent to the second felt 4' so that the web 1 is transferred to the second felt 4' and around the suction roller 7. However, as seen in figure 1, the same side 8 of the web 1 is brought into contact with the heating surfaces of the drying rollers 2, 6, 6' and 6" so that the same side 8 is dried.

The present invention, as shown in figure 2, enables the web 1A to be reversed from a first section Al to a second section Bl so that during passage of the web 1A through the first section Al, a first side 8A of the web y

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AA

:-ri WO 88/04206 PCT/US87/03087 1A comes into physical contact with the drying rollers 2A, 2A' and 2A". In the second group, BI, a second side 9 of the web 1A comes into physical contact with the heating surface of drying rollers 6A, 6A' and 6A".

Figure 3 is an enlarged, fragmentary view of the transfer section shown in figure 2 to show how the web 1A is reversed. More particularly, with reference to figure 3, the apparatus generally designated 10 for sequentially drying both sides 8A and 9 of a paper web 1A includes a first drying roller with the web extending around a portion of the circumference of the first drying roller 2A". A first felt 4A extends around a portion of the first drying roller 2A" such that the web 1A is sandwiched between the first felt 4A and the first drying roller 2A" for heating a first side 8A of the web 1A. A first suction roller 3A"' is disposed downstream relative to the first drying roller 2A". The first suction roller 3A"' has an axis of rotation which is disposed parallel and spaced relative to the rotational axis of the first drying roller 2A". The first felt 4A and the web 1A extend around a portion of the circumference of the first suction roller 3A"' such that the first felt 4A is sandwiched between the web 1A and the first suction roller First guiding means 5A, as shown in figure 2, guide the first felt 4A away from the first suction roller A second suction roller 7A is disposed adjacent to the first suction roller the second suction roller 4 p i< il vWO 88/04206 PCT/US87/03087 7A having an axis of rotation parallel and spaced relative to the axis of rotation of the first suction roller 3A"'.

A second felt 4A' extends around the second suction roller 7A and a second guiding means 12 shown in figure 2 guides the second felt 4A' towards the second suction roller 7A such that the first and second felts 4A and 4A' respectively define therebetween a web transfer section generally designated 14 so that the web 1A is sandwiched between the felts 4A and 4A' during passage through the transfer section 14. A second drying roller 6A is disposed downstream relative to the second suction roller 7A with the second drying roller 6A having an axis of rotation parallel to the axis of rotation of the second suction roller 7A such that the web 1A is sandwiched between the second felt 4A' and the second drying roller 6A for heating the second side 9 of the web 1A.

As shown in figure 2, the first felt 4A is a continuous loop which extends in sinusoidal configuration past alternate drying and suction rollers 3A, 2A, 3A', 2A' 3A", 2A" and 3A"' such that the drying rollers physically contact the first side 8A of the web 1A and the secor plurality of drying rollers 6A, 6A' and 6A" physically contact the second side 9 of the web 1A so that alternate sides of the web 1A are sequentially dried.

More specifically, the first guiding means includes a first guide roll 5A for guiding the first felt 4A and the RA~7~ o' WO 88/04206 PCT/US87/03087 \0 second guiding means includes the second guide roll 12 for guiding the second felt 4A'.

In operation of the present invention, alternate sides 8A and 9 of the paper web 1A are sequentially dried by the following process steps: 1. The joint run of the web 1A and the first felt 4A are guided around the first drying roller 2A" as shown in figure 3 such that the web 1A is sandwiched between the first felt 4A and the first drying roller 2A" for heating the first side 8A of the web 1A.

2. Thereafter, the joint run of the web 1A and the first felt 4A are guided around a first suction roller 3A"' such that the first felt 4A is sandwiched between the web 1A and the first suction roller 3A"'.

3. The first felt 4A is guided around a first guide roll and a second felt 4A' is guided from a second guide roll 12 around a second suction roll 7A such that the first and second felts 4A and 4A' respectively define therebetween a web transfer section 14 so that the web 1A supported by the first felt 4A is guided into the web transfer section 14 with the web 1A being disposed between the first and second felts 4A and 4A' respectively.

4. The web LA emerging from the web transfer section 14 is drawn around the second suction roller 7A such that the second felt 4A' is disposed between the web 1A and the second suction roller 7A.

0i ;J/P ry 1 -"111 2 r 1 i SWO 88/04206 PCT/US87/03087 Thereafter, the joint run of the web !A and second felt 4A' is directed around a second drying roller 6A such that the web 1A is sandwiched between the second felt 4A' and the second drying roller 6A for heating the second side 9 of the web 1A.

The present invention provides a simple means for positively transferring the web between successive groups of dryers in a BEL RUN configuration such that alternate sides of the web may be dried thereby providing a paper product having uniform surface characteristics, surface strength and smoothness, and no tendency to curl.

In the first dryer group, the suction rollers are disposed below the drying rollers whereas in the second group of dryers, the suction rollers are disposed above the drying rollers. This configuration enables the provision of the aforementioned simple web transfer section such that the web may be transferred from the first to the second felt.

)AJLV L.h

Claims

1. An apparatus for drying a web, said apparatus comprising a first single tier dryer section having a first plurality of dryer drums rotating in a first direction for drying a first side of the web, said first dryer section including a first plurality of suction rolls rotating in a second direction opposite to said first direction, said suction rolls being disposed between adjacent dryer drums of said first plurality of dryer drums, first dryer felt means for conveying the web in a serpentine path along said dryer drums and said suction rolls, a second single tier dryer section disposed downstream relative to said first dryer section and having a second plurality of dryer drums rotating in said second direction for drying a second side of the web, said second dryer section including a second plurality of suction rolls rotating in said first direction and disposed between adjacent dryer drums of said second plurality of dryer drums, second dryer felt means for conveying the web in a serpentine path along said second plurality of dryer drums, and said second plurality of suction rolls, and means for guiding said first and second felt means in close proximity to each other between said first and said second dryer sections so as to sandwich the web between said first and said second felt means, said means for guiding include vacuum means operable to apply a vacuum to said web so as to effect a controlled transfer of the web from said first felt means to said second felt means. R.1 2. An apparatus as set forth in claim 1 wherein said 7 mwspe01l8/beloit 91 4 12 ,rI transter section A oownstream secona arying roller (oA) is aisposea sucn mnatr ne weu itJ J a,,unlu the second felt and the second drying roller (6A) for heating a second side of the web (IA). I k 13 '$9 A'rcj vacuum means includes a first suction roll disposed downstream relative to said first plurality of dryer drums, and a second suction roll disposed downstream relative to said first suction roll, said first suction roll being operable to apply a vacuum to said web through said first felt means to hold said web against said first felt means while said web and said first felt means pass jointly around said first suction roll, said second suction roll being operable to apply a vacuum to said web through said second felt means to hold said web against said second felt means when said first felt means separates from the web, so that the web is transfered without open draw from said first felt means to said second felt means, and when said second felt means and said web pass jointly around said second suction roll.

3. An apparatus as set forth in claim 2, said apparatus including a third single tier dryer section disposed downstream relative to said second dryer section and having a third plurality of dryer drums rotating in said first direction for further drying said first side of the web, said third dryer section including a third plurality of suction rolls rotating in said second direction and disposed between adjacent dryer drums of said third plurality of dryer drums, third dryer felt means for conveying the web in a serpentine path along said third plurality of dryer drums and said third plurality of suction rolls, a fourth single tier dryer section disposed downstream relative to said third dryer section and having a fourth plurality of dryer drums rotating in said second I mwspeOl8/beloit 91 4 12 -rC cl r I I L Is'. S. S* S 0

59.. I. VAI 7 14 direction for further drying said second side of the web, said fourth single tier dryer section including a fourth plurality of suction rolls rotating in said first direction and disposed between adjacent dryer drums of said fourth plurality of dryer drums, fourth dryer felt means for conveying the web in a serpentine path along said fourth plurality of dryer drums and said fourth plurality of suction rolls, further means for guiding said second and third felt means in close proximity to each other between said second and third dryer section so as to sandwich the web between said second and said third felt means, said further means for guiding include further vacuum means operable to apply a vacuum to said web so as to effect a further controlled transfer of the web from said second felt means to said third felt means, and additional means for guiding said third and fourth felt means in close proximity to each ocher between said third and fourth dryer sections so as to sandwich the web between said third and said fourth felt means, said additional means for guiding include additional vacuum means operable to apply a vacuum to said web so as to effect yet another controlled transfer of the web from said third felt means to said fourth felt means. 4. An apparatus as set forth in claim 3 wherein each of said further vacuum means and said additional vacuum means include a respective pair of suction rolls disposed adjacent to each other. An apparatus as set forth in any one of claims 2 to 4 wherein said first felt means and the web extend around mwspe018/beloit 91 4 12 r II L i r~, 15 a portion of each dryer drum of said first plurality of dryer drums such that the web is sandwiched between said first felt means and each dryer drum of said first plurality of dryer drums for heating said first side of the web; said means for guiding said first and second felt means in close proximity to each other include first guiding means for guiding said first felt means away from said first suction roll, and second guiding means for guiding said second felt means towards said second suction roll such that said first and second felt means define o g Stherebetween a web transfer section with the web being 4**S disposed between said first and second felt means during Se passage through said transfer section; said first felt means and the web extend around a portion of the circumference of said first suction roll such that said first felt means is sandwiched between the web and said CS:. first suction roll; said second felt means and the web extend around said second suction roll such that said second felt means is sandwiched between the web and said second suction roll; and said second plurality of dryer drums is disposed downstream relative to said second suction roll, each dryer drum of said second plurality of dryer drums having a respective axis of rotation parallel to the axis of rotation of said second suction roll such that the web is sandwiched between said second felt means and each dryer drum of said second plurality of dryer drums for heating said second side of the web. 6. An apparatus as set forth in any of the preceding /7 claims wherein said first felt means comprise a single mwspe0l8/beloit 91 4 12 ir -V '..J4~IIII4Ll4 CLU t;UC ll mwspe018/beloit 91 4 12 C~ r 1t C. CC C 0 0 C.. CC. C C Cc.. 00;. 0 CC.4 C; 16 felt defining a continuous loop which extends in sinusoidal configuration past alternate dryer drums of said first plurality of dryer drums and suction rolls of said first plurality of suction rolls such that each dryer drum of said first plurality of dryer drums physically contacts said first side of the web, and said second felt means comprise a single felt defining a continuos loop which extends in sinusoidal configuration past alternate dryer drums of said second plurality of dryer drums and suction rolls of said second plurality of suction rolls such that each dryer drum of said second plurality of dryer drums physically contacts said second side of the web so that alternate sides of the web are sequentially dried. 7. An apparatus as set forth in claim 5, or claim 6 when dependent on claim 5, wherein said first guiding means includes a first guide roll for guiding said first felt means; and said second guiding means includes a second guide roll for guiding said second felt means. 8. An apparatus as set forth in any one of the preceding claims wherein said pluralities of suction rolls are disposed alternately below and above said pluralities of dryer drums. 9. A method of drying a web, said method including the steps of: guiding the web through a first single tier dryer section having a first plurality of dryer drums rotating in a first direction for drying a first side of the web, said first dryer section including mwspeOl8/beloit 91 4 12 SmwspeOl8/beloit 91 4 12 I 17 a first plurality of suction rolls which rotate in a second direction opposite to said first direction, said suction rolls being disposed between adjacent dryer drums of said first plurality of dryer drums; conveying the web contiguously with a first dryer felt means such that the web and said first dryer felt means follow a serpentine path along said dryer drums and said suction rolls; guiding the web through a second single tier dryer XT0: section disposed downstream relative to said first dryer section and having a second plurality of dryer drums rotating in said second direction for drying a second side of the web, said second dryer section including a second plurality of suction rolls rotating in said first direction and disposed between adjacent dryer drums of said second plurality of dryer drums; conveying the web contiguously with a second dryer felt means such that the web and said second dryer felt means follow a serpentine path along said second plurality of dryer drums and said second plurality of suction rolls; guiding said first and second felt means in close proximity to each other between said first and 27 second dryer sections so as to sandwich the web between said first and second felt means; and drawing a vacuum through said second felt means to effect a controlled transfer of the web from said first felt means to said second felt means. mwspeOl8/beloit 91 4 12 mwspe018/beloit 91 42 I h 18 A method of drying a web as set forth in claim 9, said method including the steps of: guiding a joint run of the web and said first felt means around each dryer drum of said first plurality of dryer drums such that the web is sandwiched between said first felt means and each dryer drum of said first plurality of dryer drums for heating a first side of the web; guiding the joint run of the web and said first felt f0:" means around a first suction roll such that said *0 first felt means is sandwiched between the web and said first suction roll; *guiding said first felt means around a first guide •roll; guiding said second felt means from a second guide roll around a second suction roll such that said first felt means and said second felt means define therebetween a web transfer section so that the web .oo supported by said first felt means is guided into the web transfer section with the web being disposed between said first and second felt means; drawing the web emerging from the web transfer section around the second suction roll such that said second felt means is sandwiched between the web and the second suction roll; and thereafter directing a joint run of the web and said second felt means around each dryer drum of said second plurality of dryer drums, such that the web is sandwiched between said second felt means and MN mwspe18/beloit 91 4 12 Smwspe018/beloit 91 4 12 i i l I I I l L .I Lil..n_ 19 each dryer drum of said second plurality of dryer drums for heating the second side of the web. 11. A method of drying a web as set forth in claim 9 or claim 10, said method including the step of guiding the web through additional single tier dryer sections for further drying the first and second sides of the web respectively. 12. An apparatus for drying a web substantially as hereinbefore described with reference to Figures 2 and 3 f' of the accompanying drawings. 13. A method of drying a web substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings. DATED this 12 April 1991 15 SMITH SHELSTON BEADLE t*9.99 Sp Fellows Institute of Patent Attorneys of Australia Patent Attorneys for the Applicant: ,BELOIT CORPORATION 1 i mwspe018/beloit 91 4 12