WO1989011562A1 - Process for pressing a continuous humid web, in particular a web of paper - Google Patents
Process for pressing a continuous humid web, in particular a web of paper Download PDFInfo
- Publication number
- WO1989011562A1 WO1989011562A1 PCT/EP1989/000557 EP8900557W WO8911562A1 WO 1989011562 A1 WO1989011562 A1 WO 1989011562A1 EP 8900557 W EP8900557 W EP 8900557W WO 8911562 A1 WO8911562 A1 WO 8911562A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- press
- paper web
- roll
- web
- paper
- Prior art date
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0281—Wet presses in combination with a dryer roll
Definitions
- the invention relates to a method according to the generic term of the main claim.
- the moist paper web is generally passed together with an endless felt belt through the press nip formed by two rollers, one of the two paper sides coming into contact with one of the rollers and the other paper side lying against the felt belt.
- double felt presses in which the paper web runs between two felts through the press nip.
- the present invention is concerned exclusively with the pressing method in which only a single felt belt is used.
- the paper web has the tendency to stick to the smooth lateral surface of the roller touching it when leaving the press nip and thus to follow this lateral surface on its circulation.
- Press rolls for paper machines have also been equipped with a metallic roll body which has a roll shell formed from artificial stone, for example made of polymer concrete, see DE-OS 33 24 928.
- a metallic roll body which has a roll shell formed from artificial stone, for example made of polymer concrete.
- the properties of this material have so far not given satisfactory results.
- the same applies to press rolls in which the cylinder jacket is formed from a mixture comprising a metal powder, see DE-OS 35 46 343 ( GB 2 169 ' 381).
- the invention has for its object to design a method according to the generic term such that the pressing process b is very efficient that the outer surface of the press roller directly touched by the web can be made of a different material than granite or artificial stone that in the area d Press nip an elevated temperature can prevail, but that the adhesive force is still as low as possible on the surface of the press roll mentioned.
- the temperature in the area of the press nip is kept within certain limits, for example between 100 and 150 ° C., an outer layer of the paper web that comes into contact with the hot outer surface is dried very rapidly within a very short time. It was surprisingly found that the paper web is easily (ie without or with only low tensile stress) the smooth outer surface of the if
- Press roll can be removed, even if the material of the roll shell is a metal, for example steel. At the same time, the existing danger that individual fibers get caught on the press roll jacket and are somehow torn out of the running paper web is also eliminated.
- the paper web (in contrast to the method known from US Pat. No. 4,738,752) is only exposed to the high temperature and the pressing pressure for a very short time. This should preferably only take a fraction of a second. This ensures that the water between the fibers does not suddenly evaporate, thereby loosening the paper structure.
- the desired extremely short joint action time of the high temperature and the pressing pressure on the paper web is ensured in that the length of the press nip in the web running direction is as short as possible. This is achieved in that two rollers are always used to form the press nip in a known manner, preferably with relatively hard roller shells. The use of a shoe press is therefore out of the question.
- the temperature acting on the paper web in the press nip is not chosen too high. If the temperature is too high, one would strong compression of the outer layer of the paper web occurs. This would hinder the further drying of the paper web (in the subsequent dryer section of the paper machine). In addition, the finished paper web would have an extremely smooth and glossy surface, which is undesirable for many types of paper. It is therefore important to choose the temperature in the press nip just high enough to prevent the paper web from sticking to the surface of the roll and to avoid excessive smoothing of the paper surface. The exact selection of the temperature depends on the circumstances of the individual case, i.e. among other things on the type of paper, the material of the outer surface of the press roll, the speed of the paper web, etc.
- the viscosity of the water contained in the paper is also reduced according to the invention by increasing the paper temperature and thus increasing the dewatering performance of the press.
- a dry content of the web also has a sufficiently high strength so that even if it adheres to the outer surface of the cylinder it can be easily removed from the cylinder without tearing.
- impulse drying is not relevant here; paper webs are dried in the dryer section at temperatures of over 250 and pressed at the same time.
- the roller jacket can be supplied with heat from the inside, using superheated steam, heating oil or using electrical heating elements.
- the supply of heat from the outside is also possible, for example with the aid of heat radiation elements.
- the surface temperature of the paper web contacting 'Preßwalzenmantels is kept constant at a certain value by means of a control system. This value depends on the type of paper (for example the type of fiber and the paper web thick) and the speed of the paper web. In general, you will choose a higher temperature for thicker papers than for thinner papers. The temperature will be made dependent on the web speed in such a way that a higher temperature is selected at higher web speeds (and som a lower temperature at lower web speeds).
- a paper web 1 runs together with a loose felt belt 2 through a press nip which is formed by two rollers 3 and 4.
- the paper web 1 touches the upper press roll 4, which can be heated.
- its roll shell can be manufactured in a simple manner from a corrosion-resistant steel tube. Its surface is preferably ground smooth. Anything is possible also to provide a micro roughness on the roller surface, for example by fine sandblasting.
- Another possibility is to apply a metallic roll cover to a cast roll body. In all cases, a metallic and thus wear-resistant and highly resilient roller surface can be provided thanks to the invention.
- the endless felt belt 2 runs outside of the press nip over felt guide rollers 5.
- the paper web 1 is immediately behind the press nip from the surface of the upper press roll 4. It then runs over a paper guide roll and is lifted off the felt directly behind the press nip. so that re-moistening of the paper web is avoided.
- the paper web 1 then runs to a further treatment station, not shown.
- heating energy source 8 with heating energy (for example in the form of electrical current, heating oil or superheated steam) via ⁇ in ⁇ line 9, ⁇ i ⁇ control unit 10 and ⁇ in ⁇ L ⁇ lung 11 to a supply unit 7 located in the press roll 4.
- a control system is used to set and maintain a certain temperature of the surface of the roll shell of the press roll 4.
- This control system includes a control device 12 which, in the usual way, continuously compares the actual value with a predetermined value and adjusts it accordingly the actual value of the target value supplies the control unit 10 with a manipulated variable so that the actual value approaches the target value.
- the control device 12 therefore has an actual value input 13, which is coupled via a line 14 to a measuring device 1; this measures the surface temperature of the paper web 1 touching the roll sleeve of the press roll 4.
- the control device 12 also has a setpoint input 16, which is coupled to a line 17 to a setpoint. This is fed, for example, by means of a rotary knob 19 (or by remote control) via a line 19a to a setpoint basic signal.
- This basic setpoint signal is made dependent t on the type of paper web 1 (eg on the basis weight of the paper web and / or on the type of fiber).
- the setpoint generator 1 is also connected via a line 20, for example, to a tachometer 21 coupled to the press roll 4; it thereby receives a control signal dependent on the web speed.
- the setpoint generator 18 forms a setpoint from this control signal and from the setpoint basic signal, which is supplied via the line 17 to the control device 12.
- control device 12 has an output 22 for the manipulated variable already mentioned. This is fed to control unit 10 via line 23.
Landscapes
- Paper (AREA)
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT89905681T ATE87044T1 (de) | 1988-05-20 | 1989-05-20 | Verfahren zum pressen einer laufenden feuchten bahn, insbesondere einer papierbahn. |
DE8989905681T DE58903837D1 (de) | 1988-05-20 | 1989-05-20 | Verfahren zum pressen einer laufenden feuchten bahn, insbesondere einer papierbahn. |
FI905122A FI905122A0 (fi) | 1988-05-20 | 1990-10-17 | Foerfarande foer att pressa en loepande, fruktig bana skaersilt en pappersbana. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP3817291.7 | 1988-05-20 | ||
DE3817291 | 1988-05-20 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1989011562A1 true WO1989011562A1 (en) | 1989-11-30 |
Family
ID=6354836
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1989/000557 WO1989011562A1 (en) | 1988-05-20 | 1989-05-20 | Process for pressing a continuous humid web, in particular a web of paper |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0414762B1 (de) |
JP (1) | JPH03504399A (de) |
DE (1) | DE58903837D1 (de) |
WO (1) | WO1989011562A1 (de) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1082857B (de) * | 1954-01-23 | 1960-06-02 | Paul Lippke | Verfahren zur Verbesserung der Entwaesserung und Vergleichmaessigung der Trocknung von endlosen Bahnen aus Faserstoffen |
US4324613A (en) * | 1978-03-31 | 1982-04-13 | Douglas Wahren | Methods and apparatus for the rapid consolidation of moist porous webs |
EP0296730A2 (de) * | 1987-06-15 | 1988-12-28 | Pulp and Paper Research Institute of Canada | Verfahren und Vorrichtung zum schnellen Pressen und/oder Trocknen von porösen Bahnen |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2052586B (en) * | 1979-05-19 | 1984-03-14 | St Annes Board Mill Co Ltd | Drying paper |
US4571798A (en) * | 1983-09-19 | 1986-02-25 | Beloit Corporation | Urethane covered paper machine roll |
-
1989
- 1989-05-20 EP EP89905681A patent/EP0414762B1/de not_active Revoked
- 1989-05-20 DE DE8989905681T patent/DE58903837D1/de not_active Expired - Fee Related
- 1989-05-20 JP JP1505487A patent/JPH03504399A/ja active Pending
- 1989-05-20 WO PCT/EP1989/000557 patent/WO1989011562A1/de not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1082857B (de) * | 1954-01-23 | 1960-06-02 | Paul Lippke | Verfahren zur Verbesserung der Entwaesserung und Vergleichmaessigung der Trocknung von endlosen Bahnen aus Faserstoffen |
US4324613A (en) * | 1978-03-31 | 1982-04-13 | Douglas Wahren | Methods and apparatus for the rapid consolidation of moist porous webs |
EP0296730A2 (de) * | 1987-06-15 | 1988-12-28 | Pulp and Paper Research Institute of Canada | Verfahren und Vorrichtung zum schnellen Pressen und/oder Trocknen von porösen Bahnen |
Also Published As
Publication number | Publication date |
---|---|
DE58903837D1 (de) | 1993-04-22 |
EP0414762B1 (de) | 1993-03-17 |
JPH03504399A (ja) | 1991-09-26 |
EP0414762A1 (de) | 1991-03-06 |
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