FI106135B - A drier assembly/a drier section, a drying module section in a papermaking machine and a process for drying a paper web - Google Patents

Description

106135

Paper Machine Drying Group / Drying Unit, Drying Module Unit and Method for Drying a Paper Web

The present invention relates to a drying machine / dryer section of a papermaking machine comprising a drying module comprising an over-blow drying unit and a large diameter cylinder / roll arranged in connection therewith so that at least the blowing zone of The drying section is formed substantially entirely of said drying modules disposed in two 15 rows such that the paper web to be dried is adapted to travel on its knees from one drying module of the rows to a closed export.

The invention further relates to a drying module / dryer group drying unit of a papermaking machine, wherein the drying module has a large diameter cylinder or roll with an overflow drying unit arranged thereon, a drying wire for conveying the web and guide rolls for guiding the drying wire.

The invention also relates to a method of drying a paper web in a dryer section / dryer group of a papermaking machine, wherein the paper web is transported supported by a drying wire, wherein the web is evaporated wherein the web is dried in substantially all of the drying section or substantially all of the drying group by over-blow drying modules with two rows of drying modules placed above the cylinder and a bottom row over-drying unit being placed below the top of the cylinder and drying module dry t usviiralle.

As is known in the art, paper is dried in a multi-cylinder dryer having a plurality of drying cylinders in one or two overlapping rows. In the drying of tissue paper there are known so-called "tufts". Yankee dryers comprising a large diameter heated cylinder on which may be arranged so-called. impingement. A plurality of nozzle tubes are disposed within this hood, through which air jets of high-speed drying are applied to the free web surface 10. The jacket of the Yankee cylinder is solid and unpunched and is usually a steam heated pressure vessel. In a conventional overflow hood, evaporation occurs in one direction because water cannot evaporate towards the smooth surface of the Yankee cylinder.

15 The water evaporation efficiency of the prior art cylinder dryer is approximately 15-30 kg / h / m 2 per cylinder surface area. The Yankee dryer equipped with an overflow hood has an equivalent evaporation capacity of 100-150 kg / h / m2.

Disadvantages of the prior art multi-cylinder dryers include the high cost of the structure 20 and the large space occupied by the structure, particularly in the machine direction, as well as the literally complicated and interfering export of the web through the dryer.

Reference may be made in the prior art to U.S. Patent No. 3,816,941, which discloses a drying section for drying a web of material having two rows of cylinders and wherein the web of material passes from one row to another, partially wrapping around the cylinders. An air supply hood is provided adjacent to each cylinder for improved drying efficiency and may further be provided with an infrared or microwave dryer. The purpose of the solution disclosed in the publication is to provide a drying section which enables higher speeds without fluttering the web, and this is accomplished by ensuring a smooth passage of 30 papers by transferring the paper web from one cylinder to another as a sandwich arrangement. The solution according to the publication employs flow-through drying, in which the drying air introduced by the hood near the web passes through the web to the cylinder from which it is sucked. This arrangement is particularly suitable for tissue drying.

U.S. Patent No. 3,956,832 discloses a dryer section employing a twin-wire spreader wherein the web to be dried is conveyed between the wires and guided onto a drying roll, where it is subjected to hot air blowing, sucked into a vacuum inside the roll to enhance web stability and drying. The solution according to the patent uses two wires to move the web to avoid runnability problems and the drying is enhanced by flow-through drying combined with a partial overlay 10 board.

It is an object of the present invention to provide a new dryer for paper, especially fine or newsprint, which achieves the greater drying power required for e.g. as paper machine speeds keep rising.

15th The object of the present invention is to increase the drying efficiency of the paper dryer with a new solution so that the space required for the dryer section in the machine direction can be substantially reduced, thereby significantly reducing the investment costs for both buildings and machinery.

20

Thus, it is previously known to use various on-blow / blow-through units for evaporative drying of the paper web, which have been used especially for drying of paper tissue. In the prior art blowing applications, the drying groups are covered with a hood or the like. It is a further object of the invention to provide an arrangement whereby the dryer section does not require a closed hood around the drying groups, and whereby simpler exhaust and supply air arrangements may be used than in prior art solutions.

Ψ

In order to achieve the foregoing and later objects, the paper machine dryer section / dryer group of the present invention is essentially characterized by what is set forth in the characterizing part of claim 1.

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The drying module unit according to the invention, in turn, is essentially characterized by what is stated in the characterizing part of claim 4.

Furthermore, the method according to the invention is in turn essentially characterized by what is set forth in the characterizing part of claim 11.

In the arrangement according to the invention, the dryer group / dryer section is based on over-purification and the dryer section / dryer group consists of modules having a suction roll or cylinder above and below, preferably 10 suction rolls / cylinders (Vac rolls) marketed by the applicant under the trademark "VacRoll" Vac blasting unit arranged in connection with the Vac roller. The drying groups are formed as compact geometry module units with a separate drying wire or equivalent and wire guiding and / or guide rolls attached to each module unit, and preferably also having a suction box, preferably a suction box marketed by the applicant under the trademark "UnoRun".

An advantage of the arrangement according to the invention is e.g. the fact that the drying section is significantly shortened because, compared to a multi-cylinder dryer, the drying power / unit length is higher when using blow-drying. The cost-effective geometry of the drying mode-20 bridges adds to the length savings.

Since, in the arrangement of the invention, substantially all of the moisture is evaporated from the web in the blowing units, substantially all of the evaporated water is removed through the exhaust air systems of the overflow control devices, thereby significantly reducing the need for enclosure drying. The enclosure can be completely eliminated by placing suction boxes at critical points to remove damp hot air. If the enclosure is to be used, it can be very lightweight.

* There is some evaporation outside the blower systems (in the order of 30% of the pair), for which it is possible to arrange small exhaust air devices to remove damp air and supply air devices to bring hot, dry air to critical areas.

Since the arrangement according to the invention does not use a hood closed according to prior art solutions, all exhaust air is very moist, which in turn enhances heat recovery.

By not using steam heated cylinders in the drying groups, the cost of the steam drying cylinder required by the steam and condensate system is saved.

According to a preferred embodiment of the invention, the air systems of the blow-off hoods are based on the use of recirculated air to maintain a high level of moisture in the drying and exhaust air, which has been found to be advantageous in terms of energy costs. The on-15 blowing hoods may be connected such that they have separate circulating air systems or multiple hoods may be connected to the same circulating air system. In an overhead shower hood, the evaporated water is removed with the exhaust air, and the combustion air required by the ponderers and the replacement air needed to maintain the air balance are introduced preheated to the recirculation systems. The energy content of the blowing exhaust air is high due to the high temperature and humidity, so it is used for heat recovery, which can be several or one uniform for the whole machine. The first step is to heat the combustion and replacement air required by the blowing systems to achieve the highest possible temperature. Thereafter, the exhaust air is used to heat the replacement air of the drying section, and possibly also the air required by the runner system. 25 The heat recovery itself achieves the desired temperature, but steam starters can be added to the system for start-up and interruptions. After this step, the exhaust air still has a high energy content, so it can be used, for example, to heat the air in the hall, either via a circulating air circuit or directly in the air / air heat exchangers. Lastly, heat recovery can include, for example, heating of fresh water, 30 jets of water or 0-water. According to a further preferred embodiment of the invention, dry, preheated air is supplied to the drying section, e.g. to the following locations, so that the water evaporated outside the overflow hoods and any recirculated air from the runner system does not present a risk of condensation. Blowing boxes across the machine are used to ventilate areas where water outside the overflow hoods mainly evaporates. The space between the top hoods is ventilated by blowing boxes across the machine 5 to reduce the risk of condensation. The dryer section is also deaerated because air conditioning and runnability systems bring air into the dryer section. This exhaust air can be used, for example, to heat the water in a separate heat recovery. The water evaporated mainly outside the overflow hoods can be removed by means of suction boxes 10 across the machine and by suction boxes inside the wire loop, across the machine or at the side of the machine. Vac rolls are sucked with exhaust air to maintain the vacuum in the rolls. Depending on the optimum driving mode required for the production situation, this air may be wholly or partially recovered for heat recovery of the dryer section exhaust air, recirculated in the vicinity of the suction rollers, or used in the runnability system 15, in whole or in part. The runner system can use dry, preheated τ 'air for heat recovery, in whole or in part, or Vac roller exhaust air, in part or in full. Because the proper operation of Vac rollers and runnability systems is based on certain amounts of air, which may vary under certain circumstances, systems can be balanced when coupled.

20

In the following, the invention will be described in more detail with reference to the accompanying drawings, in which Figure 1 is a schematic representation of a drying module / drying unit consisting of three modules, Figure 2 is a schematic sub-view of a module drying unit / drying unit;

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Figure 1 is a partial view of a drying group / dryer section formed of three drying modules R1, R2. Two drying modules R1, R2 one in the top row and one in the bottom row form a drying module unit R. Each drying module R1, R2 has a suction roll or suction cylinder 10,20, preferably a Vac roll and an overhead fan unit 11,21 located thereon. The drying modules R1, R2 are arranged in two rows; drying modules R1 to the top row and drying modules R2 to the bottom row. Each of the drying module types R1, R2 has its own drying wire 14,31 and the overflow zones of the blowing unit 11,21 are indicated by the arrow arrows 16,26 and the direction of rotation of the rolls 10,20 by the arrows S10.S20.

The drying wire 14 of the drying module R1 runs about the Vac roll 10, being against the surface of the Vac roll 10 at least in the region of the overflow zone 16 and guided by the inside guide rolls 12,13 of the wire loop 14. The retention of the web W in the drying fabric 14 is secured in the immediate vicinity of the entry point to the web W blowing unit 11 by means of a suction box 15, preferably a UnoRun box, arranged inside the wire loop 14. 15th The drying fabric 31 of the drying module R2 extends around the surface of the suction roll 20, at least in the region of the overflow zone 26, guided by the guide rolls 27,28,29 and 30, the guide rolls 27,29 being disposed outside the wire loop 31 and the lead rolls 28 and 30. Inside the wire loop 31 is also provided a small diameter suction roll 20, preferably a Vac roll 26, the direction of rotation of which is indicated by the arrow S26. In order to ensure the adherence of the web W, suction boxes 24.25 are provided in connection with the drying-wire loop 31.

As shown in Figure 1, the top row drying module R1 has a top blower unit 11 on top of the Vac roll 10 and the paper web W passes over a short wire loop 14 on the Vac roll 10. This,. afterwards, the paper web W moves to the wire loop 31 of the next lower row dryer module and therein a Vac roll 20, preferably of the same diameter as the previous Vac roll 10, whereby the UnoRun box 24 ensures that the paper web W stays attached to the wire 31. after the roll 30 20 and the blow blowing 21, the paper web W passes below the wire 31 to the Vac roll 8 106135 26, which also has an UnoRun box 25 for holding the web W in the wire 31. The web W is then led to the next top row drying module R1.

The suction roll / -5 cylinder 10.20 of the suction roll / dryer 5 of the drying module R1, R2 has a diameter of 1 m to 10 m, preferably 2 m to 4 m and the suction roll 26 of the lower row of drying module R2 has a diameter of 0.5 m to 3. m, preferably 0.5 m - 2 m.

Fig. 2 is a partial view of a drying unit / drying unit formed of drying modules. The drying modules according to the invention can be formed into the desired number of drying groups of the drying section or the entire drying section.

The drying modules R1, R2 of Fig. 2 correspond to the drying modules R1, R2 and similar parts described in connection with Fig. 1, with the same reference numerals. In the drying section according to Fig. 2, three upper-row drying modules R1 and ..... are arranged in the upper row and 4 lower-row drying modules R2. The blowing units 11,21 are formed of 'two blocks ΙΙΑ, ΙΙΒ respectively. 21A.21B.

At appropriate intervals between the lower row drying modules R2, a wreck conveyor 40 20 can be provided with which the paper web W or the wreck can be removed from the drying section if necessary. At these points, the paper web W is located on the wire 31, respectively. 14, whereby wreck removal is easily arranged. If necessary, a blow is provided in connection with the blowing box 25,24 to remove the web from the wire 31,14 and transport the wreck between the modules R2 by means of a wreck conveyor 40. The wreck conveyor 40 consists of two belts 41,42 traveling at a certain speed 25 which form a funnel.

•

Figure 3 schematically shows an air arrangement 50 associated with the drying arrangement shown in Figure 2. The dryer section is enclosed by a casing structure 51 and parts of the drying arrangement are referenced to those of FIG. Reference numeral 52 denotes 30 dryer section exhaust air systems, reference numeral 53 denotes a runner system circulating air system, reference numeral 54 denotes a dryer section ventilation air system and reference numeral 106135 9 la 55 Vac roller exhaust system and reference numeral 56 denotes a runner system ventilation system. Exhaust air 52 of the drying section is taken, for example, by separate outlet boxes 52A and 52B. The drying air 54 of the drying section is led along the air passages to the venting devices 54A located near the rollers, or to the venting boxes 54B, 5 which are located in the area between the blowing hoods. The exhaust air of the Vac rollers 10,20 passes through the exhaust air connections 52C through the exhaust air ducts to the Vac roll exhaust system 55. The circulating air devices of the runner system 53 are denoted by reference numeral 53A and the devices associated with the runner system blowing air system 56.

10

The invention has been described above with reference only to some preferred embodiments thereof, the details of which, however, are not to be construed in any way narrowly limited.

Many modifications and variations are possible within the scope of the inventive idea defined in the following claims.

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Claims (13)

A papermaking machine drying unit / dryer unit comprising a drying module (R1, R2) comprising an overflow drying unit (11,21) and 5 large diameter cylinders / rolls (10,20) fitted therewith positioned within the drying wire (14,31) , that at least in the blowing zone (16,26) of the blowing unit (11,21), the drying fabric (14,31) is located against the surface of the cylinder / roll (10,20), the drying machine / drying section of the paper machine being substantially entirely formed of said drying modules (R1, R2) disposed in two rows such that the paper web to be dried (W) is adapted to travel on its knees from one row drying module (R1, R2) to a closed export, characterized in that at least two adjacent bottom row drying modules (R2) are disposed. A drying group / dryer according to claim 1, characterized in that the large diameter cylinder / roll (10,20) of the drying module (R1, R2) is a suction cylinder / roll without an inner suction box. « Drying group / dryer according to Claim 1 or 2, characterized in that in the drying section / drying group, the removal of moisture evaporating from the web (W) is arranged through the exhaust air system of the blowing unit (11,21) and / or by suction boxes (52A, 52C) and / or through suction cylinders / rollers (10,20) through an exhaust air system (55). A drying module unit of a paper machine dryer section / dryer group, wherein the dryer module (R1, R2) has a large diameter cylinder or roll (10,20) connected thereto. an overflow drying unit (11,21) provided, a dryer fabric (14,31) for conveying the web (W) and guide rolls (12,13; 27,28,29,30) for guiding the dryer fabric (14,31) in which the paper web (W) to be dried is arranged passage from one row to another as a closed export, characterized in that the drying module unit (R) comprises two drying modules (R1, R2), that the drying modules (R1, R2) of the drying module unit (R) are arranged in two rows are located between the horizontal centrelines of the cylinder / rolls (10,20) of the drying modules (R1, R2). and that a wreck conveyor (40) is provided between at least two adjacent bottom row drying modules (R2). Drying module unit according to claim 4, characterized in that the large diameter cylinder or roll (10,20) of the drying module (R) of the drying module unit (R) is a suction cylinder or roll without an internal suction box. Drying module assembly according to claim 4 or 5, characterized in that the guide rolls (12,13) of the drying wire loop (14) of the top row drying module (R1) are located inside the wire loop. Drying module assembly according to one of claims 4 to 6, characterized in that the top row drying module (R1) comprises two guide rolls (12,13) located below the blowing unit (11) and the cylinder / roll (10). Drying module assembly according to claim 4 or 5, characterized in that two guide rolls (28,29) and a suction roll (26) are placed inside the dryer wire loop (31) of the bottom row drying module (R2) and two guide rolls (27,30) are placed outside. 20 Drying module unit according to one of Claims 4.5 or 7, characterized in that the lower row drying module comprises four guide rolls disposed above the blowing unit (21) and the cylinder / roll (20). A drying module according to any one of claims 4 to 9, characterized in that. . a suction box (15; 25,26) is provided in connection with the drying module (R1, R2) to ensure that the web (W) remains attached. 10 106135 A method of drying a web of paper in a dryer section / dryer of a papermaking machine, wherein the paper web (W) is transported supported by a drying fabric (14,31), wherein the web (W) is evaporated-drying a belt (11,21) within which the web (W) passes, supported by a drying wire (14,31), on the surface of a large-diameter cylinder or the like (10,20) with the web (W) facing the outer curve, wherein the web (W) is dried substantially throughout in the drying section, or substantially 5 of the entire drying group, by blow-drying with drying modules (R1, R2) arranged in two rows, wherein the top row of the blowing unit (11) is located above the cylinder (10) and the bottom row the blowing unit (21) ) is led from one drying module (R1, R2) to another closed to export characterized in that the wreck is removed on at least two adjacent bottom row drying modules (R2) disposed on the wreck conveyor (40). Method according to Claim 11, characterized in that in the drying module (R1, R2) the web (W) is conveyed on the surface of a large-diameter air suction cylinder or suction roll (10,20) via a drying wire (14,31). Method according to Claim 11 or 12, characterized in that in the drying section / drying group, the volatile moisture from the web (W) is removed through the exhaust air system of the blowing unit (11,21) and / or by suction boxes (52A, 52C) and / or the rolls (10,20) through the exhaust air system (55). # 13 106135