Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F5/00—Dryer section of machines for making continuous webs of paper
  • D21F5/02—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
  • D21F5/02—Drying on cylinders
  • D21F5/04—Drying on cylinders on two or more drying cylinders

Definitions

• the invention relates to a dryer section of a paper machine with the features specified in the preamble of claim 1.
• a dryer section is known from DE 43 28 554 AI. Dryer sections of this known type are particularly suitable for paper machines which are operated at high working speeds and on which, for example, graphic papers are to be produced.
• An essential feature of the known dryer section is that at least one single-row dryer group is present.
• Such a single-row dryer group has only a single row of cylinders and a deflection roller, which can be a suction roller, between every two cylinders.
• the paper web to be dried is continuously guided through an endless pressure belt (e.g.
• a drying screen which presses the paper web against the drying cylinder on the one hand and leads from a drying cylinder to the next drying cylinder via the following deflection roller. This avoids that the paper web is free, i. H. unsupported, must run from one cylinder to the subsequent cylinder. This significantly reduces the risk of paper web tears.
• the present invention is now concerned with the problem of specifying a dryer section which is primarily suitable for the production of relatively thick paper webs or cardboard webs, whereby - compared to conventional dryer sections - increased strength of the finished web is to be achieved for these web types.
• the formation of the high-pressure dryer group as a single-row dryer group is not primarily necessary in order to avoid web breaks, but, as explained above, in order to interact with the high Pressure band longitudinal tension to achieve a high compression of the web.
• Such compaction of the web needs not to take place over the entire length of the drying section, but may be limited to the so-called main shrinkage zone for reasons of space saving.
• This means that the remaining parts of the dryer section can be designed in a conventional manner, either completely in two rows or mixed in one and two rows.
• the “high pressure group” described above is preceded by at least one conventional two-row drying group; their main task is to heat up the web entering the dryer section.
• their main task is to heat up the web entering the dryer section.
• this conventional single-row dryer group it is ensured that the still relatively moist paper web coming directly from the press section (with still relatively low strength) is heated without the risk of paper web tears.
• a conventional two-row drying group can also be arranged after the "high pressure group". This enables the paper web to be brought completely to the desired final dryness with a relatively small space requirement.
• the invention is preferably applicable in the production of relatively thick types of paper, e.g. B. from Pack ⁇ papers, corrugated base paper and technical papers of various types, for example abrasive and raw paper.
• the compression of the paper web according to the invention can take place in a single “high pressure group”.
• a single endless pressure belt is provided for all drying cylinders of the "high pressure group", which preferably runs over the upper area of the cylinder jackets, so that only the underside of the web comes into contact with the cylinder jackets.
• two or more such "high pressure groups” can also be connected in series, so that the drying cylinders of all "high pressure groups” only come into contact with the underside of the web. This can be advantageous if it is desired that the finished paper web has a higher smoothness on one of its two web sides (ie on the underside) than on the other side.
• a further additional compression of the paper web can be achieved by unusually high cylinder temperatures, e.g. B. in that the cylinders (or part of the cylinders) are not heated with the help of steam, but by burning heating gases.
• hot air blow boxes can also be arranged, preferably in the zones where the web with the pressure belt runs over the deflection rollers.
• the diameters of the heated drying cylinders can be approximately the same size as the diameters of the deflection rolls designed as suction rolls. In other words: Relatively small cylinder diameters are paired with relatively large suction roll diameters.
• FIGS. 1 to 4 shows a drying section in a schematic side view.
• the press section 1 there is a conventional single-row dryer group 2, followed by a likewise conventional two-row dryer group 3, and the high-pressure group 4 according to the invention 8 taken from the press section 1 into the drying section.
• This dryer group 2 is "felted” at the top, ie the pressure belt (eg dryer fabric 9 or dryer felt) wraps around the upper part of the drying cylinder 14 and wraps around the deflection rollers, for example dryer fabric suction rollers 13, attached between and below the dryer cylinder 14.
• the dryer fabric 9 only experiences the usual normal belt tension, symbolically represented by a small arrow 16.
• the upper cylinders 14 ' are “felted” at the top and the lower drying cylinders 14 "" felted "at the bottom.
• the dryer fabric tension corresponds to the values customary hitherto.
• the high-pressure group 4 according to the invention now follows. In terms of its structure, it corresponds to the single-row "felted" drying group 2 at the top, ie the drying cylinders 11 are arranged at the top, while the dryer fabric suction rolls 12 are arranged at the bottom.
• dryer cylinders 11 have a relatively small diameter of, for example, I m or less.
• the diameter of the dryer fabric suction rolls 12 is considerably larger than that of a conventional single-row dryer group. Their diameter corresponds approximately to that of the drying cylinders 11.
• Another essential feature of this high-pressure drying group is the significantly higher longitudinal tension of the pressure belt 9, symbolically represented by a large arrow 17.
• the pressure belt 9 ' can also be a dryer fabric. Because of the greater forces on the dryer fabric guide rollers 7 resulting from the increased belt tension, their diameters are substantially larger than the diameter of the guide rollers 10 of the other dryer groups 2, 3 and 3 '.
• FIG. 1 Another structure of a drying group is shown in FIG. This structure is particularly suitable for heavy paper and cardboard.
• the fibrous web 8 coming from the press section 1 first goes into a two-row dryer group 3 with conventional dryer fabric tension 16. This is followed by a first high-pressure group 4, which is felted at the top.
• the dryer fabric 9 is subjected to an increased belt tension 17.
• This drying group is followed by a second high-pressure group 5, which is felted at the bottom, however.
• a conventional two-row dryer group 3 ' which brings the fibrous web to its final dry content.
• the fibrous web 8 is dried in at least two single-row felted drying groups 2 and 2 '. Only then is the web dried in at least one high-pressure group 4, onto which, as in FIG. 1 or
• FIG. 4 Another variant is shown in FIG. 4.
• the fibrous web is first dried by a single-row felted dryer group 2. After this gentle input drying there is a further intensive drying with a two-row dryer group 3. This is followed in the so-called main shrinkage zone by at least one likewise two-row dryer group 6, in which the upper and lower dryer fabrics are stretched high in the manner according to the invention (thick arrows 17). This makes the larger diameter of the dryer fabric guide rollers 7 necessary (see claim 15).
• the end of the dryer section can again form a conventional two-row dryer group, not shown.

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• Paper (AREA)
• Drying Of Solid Materials (AREA)
• Crushing And Grinding (AREA)

Applications Claiming Priority (3)

Publications (2)

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Country Status (7)

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• 1994
  • 1994-05-11 DE DE4416585A patent/DE4416585C2/de not_active Expired - Fee Related
• 1995
  • 1995-05-10 EP EP95917890A patent/EP0708858B1/fr not_active Expired - Lifetime
  • 1995-05-10 DE DE59501037T patent/DE59501037D1/de not_active Expired - Fee Related
  • 1995-05-10 AT AT95917890T patent/ATE160603T1/de not_active IP Right Cessation
  • 1995-05-10 JP JP7529280A patent/JPH09504843A/ja active Pending
  • 1995-05-10 US US08/583,047 patent/US5770015A/en not_active Expired - Fee Related
  • 1995-05-10 WO PCT/DE1995/000601 patent/WO1995031601A2/fr active IP Right Grant
• 1996
  • 1996-01-10 FI FI960118A patent/FI960118A0/fi not_active IP Right Cessation

Non-Patent Citations (1)

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