CN113737559A - Thin-sheet long-net paper-making equipment - Google Patents
Thin-sheet long-net paper-making equipment Download PDFInfo
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- CN113737559A CN113737559A CN202110902580.3A CN202110902580A CN113737559A CN 113737559 A CN113737559 A CN 113737559A CN 202110902580 A CN202110902580 A CN 202110902580A CN 113737559 A CN113737559 A CN 113737559A
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
- D21F9/02—Complete machines for making continuous webs of paper of the Fourdrinier type
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Abstract
The application relates to the technical field of papermaking, specifically discloses a tissue fourdrinier papermaking equipment includes at least: a fourdrinier wire forming assembly and a sheet pressing assembly disposed downstream of the fourdrinier wire forming assembly; the fourdrinier wire forming assembly comprises: the device comprises a forming net, and a breast roll, a forming plate, a dewatering plate, a low vacuum suction box, a high vacuum suction box, a non-vacuum couch roll, a net driving roll, a net guide roll, a correcting roll, a tensioning roll, a forming net state adjusting device and a white water tank which are sequentially arranged along the lower surface of the forming net; the sheet press assembly includes: a three-roller two-pressing area unit, a blanket belt transferring unit and a vacuum carrier roller pressing unit; the three-roller two-pressing area unit is used for carrying out secondary pressing on the paper sheet before open paper guiding; the transfer blanket belt unit is used for supporting the paper sheet and transferring the paper sheet from the three-roller two-press area unit to the vacuum carrier roller pressing unit; the vacuum carrier roller pressing unit is used for dewatering paper sheets. By the method, the smoothness of the single-sided glossy paper with high index can be manufactured.
Description
Technical Field
The application relates to the technical field of papermaking machinery, in particular to a tissue fourdrinier papermaking device.
Background
Fourdrinier paper machines, also called fourdrinier machines, are mainly characterized by a forming section of the type having a conveyor belt formed by an endless wire.
In the long-term research and development process, the inventor of the application finds that the vacuum couch roll is selected at the tail end of the net table of the net part of the existing paper machine, and the vacuum couch roll can dehydrate paper sheets by utilizing high vacuum degree, but can cause the loss of fine fibers, fillers and the like in the paper sheets under the high vacuum state, so that the fiber structure of one surface (which can be called as a net surface or a reverse surface) of the paper sheets, which is in contact with a forming net, is not compact enough, and the initial basis for improving the smoothness of the single-sided smooth paper subsequently by the net surface of the paper sheets is poor. In addition, the present inventors have found that in the prior art, a sheet is pressed before entering the yankee cylinder by a two-roll twin-felt press unit, wherein the web, which has been brought into contact with the smooth roll surface and initially glossy, is brought into contact with the felt fabric again in the nip, and is affected by the felt fabric marking, so that the existing smoothness is weakened, and the sheet dryness is low, which is likely to cause sheet breakage. In addition, the inventor of the present application has also found that in the prior art single-strand paper machine, the sheet is generally reversely fed into the yankee dryer from bottom to top, and the sheet is adsorbed only by the moisture content in the felt, and is easily separated from the felt by the air flow formed at a speed, which hinders the increase of the running speed of the paper machine.
Disclosure of Invention
Based on this, the present application provides a new device comprising a forming press and a tissue fourdrinier papermaking plant implementing a new method of operation, in order to solve the problems of the prior art mentioned above.
In order to solve the technical problem, the application adopts a technical scheme that: there is provided a tissue fourdrinier papermaking plant comprising at least: a fourdrinier wire forming assembly and a sheet pressing assembly disposed downstream of the fourdrinier wire forming assembly; the fourdrinier wire forming assembly comprises: the device comprises a forming net, and a breast roll, a forming plate, a dewatering plate, a low vacuum suction box, a high vacuum suction box, a non-vacuum couch roll, a net driving roll, a net guide roll, a correcting roll, a tensioning roll, a forming net state adjusting device and a white water tank which are sequentially arranged along the lower surface of the forming net; the sheet press assembly includes: a three-roller two-pressing area unit, a blanket belt transferring unit and a vacuum carrier roller pressing unit; the three-roller two-pressing area unit is used for carrying out secondary pressing on the paper sheet before open paper guiding; the transfer blanket belt unit is used for supporting the paper sheet and transferring the paper sheet from the three-roller two-press area unit to the vacuum carrier roller pressing unit; the vacuum carrier roller pressing unit is used for dewatering paper sheets.
Wherein, the roll surface of the non-vacuum couch roll is not provided with a through hole for forming a vacuum environment, so that no vacuum pressure difference exists between the forming net and the roll surface of the non-vacuum couch roll.
Wherein, three-roller two nip unit includes: the composite vacuum pressing roll, the central pressing roll, the upper pressing roll, the first pressure pump and the second pressure pump form a first pressure area, and the upper pressing roll, the central pressing roll and the second pressure pump form a second pressure area; wherein, the paper sheet enters the first press area and the second press area in sequence and is in secondary contact with the smooth roll surface of the central press roll so as to realize secondary pressing of the paper sheet.
Wherein, transfer blanket area unit includes: the carpet transferring device comprises a carpet transferring belt, a correcting roller, a tensioning roller, a carpet guiding roller, a driving roller and an associated carpet adjusting device; the transfer blanket belt is wrapped around the correcting roller, the tensioning roller, the blanket guiding roller and the driving roller.
Wherein, vacuum bearing roller squeezes unit includes: the paper sheet dewatering device comprises a vacuum carrier roller, a carrier roller blanket belt and a Yankee drying cylinder, wherein the carrier roller blanket belt is wrapped on the vacuum carrier roller and is matched with the vacuum carrier roller so as to transfer paper sheets to the Yankee drying cylinder, and a pressing area formed by the vacuum carrier roller and the Yankee drying cylinder is used for dewatering the paper sheets.
The composite vacuum press roller comprises a first vacuum chamber, a second vacuum chamber and a third vacuum chamber which are sequentially arranged inside the composite vacuum press roller; the first vacuum chamber is used for sucking paper sheets from the forming net of the fourdrinier forming assembly, and the vacuum degree of the first vacuum chamber is 45-55 kPa; the second vacuum chamber is used for keeping the paper on the blanket belt, and the vacuum degree of the second vacuum chamber is 45-55 kPa; the third vacuum chamber is used for dehydrating the paper sheets, and the vacuum degree of the third vacuum chamber is 55-65 kPa.
Wherein, the transfer blanket belt is connected with the three-roller two-pressure area unit and the vacuum carrier roller pressing unit;
the transfer blanket belt is a light blanket belt or a dry net with the weight of 800-1000 grams per square meter; the tension of the transfer blanket belt is 3.5 to 5.5 kN/m.
The vacuum carrier roller comprises a fourth vacuum chamber and a fifth vacuum chamber which are sequentially arranged inside the vacuum carrier roller; the fourth vacuum chamber is used for sucking the paper sheets from the transfer blanket belt unit and keeping the paper sheets on the carrier roller blanket belt, and the vacuum degree of the fourth vacuum chamber is 50-60 kPa; the fifth vacuum chamber is used for dehydrating the paper sheets, and the vacuum degree of the fifth vacuum chamber is 55-65 kPa.
Wherein, the vacuum carrier roller and the Yankee drying cylinder form hot pressing.
Wherein the steam working pressure of the Yankee dryer is 0.65Kpa, and the design steam pressure of the Yankee dryer is 0.8 MPa; and is provided with a hot air exhaust hood; the roughness of the cylinder surface of the Yankee drying cylinder is 0.2 mu m, and the cylinder surface of the Yankee drying cylinder is manufactured by high-precision grinding of an outer circle.
Unlike the vacuum couch roll used in the prior art, the non-vacuum couch roll originally designed in this application does not press the sheet (i.e., the sheet is not dewatered at the non-vacuum couch roll), and the forming wire passes around the non-vacuum couch roll to form a return stroke back to the breast roll, while the non-vacuum couch roll transmits power to the forming wire, and the sheet is peeled from the forming wire at a point after the non-vacuum couch roll. Because the paper sheet is subjected to plane dehydration only by virtue of the horizontal dehydration section from the breast roll to the non-vacuum couch roll and the high-vacuum negative pressure dehydration is not carried out at the non-vacuum couch roll, the loss of fine fibers, fillers and the like in the paper sheet can be effectively reduced, the fiber structure of the net surface is more compact, and a good foundation is created for obtaining the high-index smoothness of the single-sided glossy paper in the subsequent production;
different from the prior art, the three-roller two-press area unit is originally designed, the three-roller two-press area unit can carry out secondary pressing on the net surface of a paper sheet on the smooth surface of a central roller, the net surface of the paper sheet continuously improves the smoothness, and meanwhile, the paper sheet opens the paper leading when reaching proper dryness, so that the wet strength of low-weight tissue paper at the first opening paper leading position can be enhanced, and the paper breaking rate of the low-weight tissue paper during operation is reduced;
different from the prior art, the transfer blanket belt unit is originally designed, and paper sheets stripped from a central pressing roll of a three-roll secondary pressing area unit are transferred to the transfer blanket belt wrapped on a blanket guide roll through a paper guide roll; the transfer blanket unit is not provided with a press roll (i.e. a non-press area), the transfer blanket is only used for supporting and transferring paper sheets, and the paper sheets supported by the transfer blanket do not pass through the press area, so that the paper sheets with smoothness formed on the net surfaces of the paper sheets are naturally transferred to the next position by the transfer blanket without weakening the existing smoothness, i.e. the transfer blanket unit protects and maintains the smoothness formed on the net surfaces of the paper sheets in the three-roll two-press area unit; the paper web surface is transferred to the vacuum carrier roller pressing unit to move in the whole process, the web surface with a compact surface is only contacted with the smooth roller surface under the pressurizing condition, the influence of pressing blanket belts on the paper web surface with smoothness caused by the impression of the blanket belts is avoided, and the smoothness and the glossiness of the paper are kept;
different from the prior art, this application has creatively designed with the vacuum bearing roller and the bearing roller blanket area of yankee dryer cooperation, adsorbs and keeps the paper sheet on bearing roller blanket area from transmitting blanket area with the help of the vacuum negative pressure of the fourth real empty room in this vacuum bearing roller, and then transmits the paper sheet to the nip of yankee dryer through bearing roller blanket area, simultaneously, carries out dewatering treatment to the paper sheet with the help of the vacuum negative pressure of the fifth real empty room in this vacuum bearing roller. Because this application passes through the vacuum adsorption effect of the vacuum chamber in the vacuum bearing roller, its vacuum pressure difference and by the centrifugal force balance that produces when the paper moves, make the paper can not break away from with blanket area, can realize leading paper safely under the high-speed operation of paper machine. Thus, the operation of reverse bottom-up opening threading of the sheet to the Yankee dryer in the existing single-strand paper machine, which prevents an increase in the machine speed, is essentially eliminated.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. Wherein:
fig. 1 is a schematic structural view of a tissue fourdrinier papermaking apparatus of the present application.
FIG. 2 is a schematic structural view of a first embodiment of a tissue fourdrinier papermaking apparatus of the present application;
FIG. 3 is a schematic view of a portion of a second embodiment of a tissue fourdrinier papermaking apparatus according to the present application;
FIG. 4 is a schematic view of a portion of a third embodiment of a tissue fourdrinier papermaking apparatus according to the present application;
FIG. 5 is a schematic view of a partial structure of a fourth embodiment of a tissue fourdrinier papermaking apparatus of the present application;
FIG. 6 is a schematic view of a portion of a prior art two roll, two felt press unit
FIG. 7 is a schematic representation of a prior art Yankee nip pick-up direction;
FIG. 8 is a schematic representation of the direction of the Yankee nip draw of the fourdrinier papermaking apparatus of the present application;
FIG. 9 is a schematic representation of the web of the present application in compression at the transfer belt assembly;
fig. 10 is a schematic representation of the nip of a two roll, two pile blanket of a prior art paper web.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the above-described drawings (if any) are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical solution of the present application will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
As shown in fig. 1, the present application provides a tissue fourdrinier papermaking apparatus comprising at least: a fourdrinier wire forming assembly 10 and a sheet press assembly 20 disposed downstream of the fourdrinier wire forming assembly. The tissue fourdrinier papermaking apparatus provided herein can be used to make single-sided glossy tissue.
The application provides a tissue fourdrinier papermaking equipment still includes: an associated back end dryer assembly 30, calender roll assembly 40, is disposed downstream of sheet press assembly 20.
As shown in fig. 2, the fourdrinier wire forming assembly 10 comprises: forming a net; a breast roll 102, a forming plate 103, a dewatering plate 104, a low vacuum suction box 105, a high vacuum suction box 106, a non-vacuum couch roll 107, a wire driving roll 108, a wire guiding roll 109 and a white water tank 110 are sequentially arranged along the lower surface of the forming wire.
The side of the paper sheet contacting the forming wire is called the wire side (or called the reverse side), and the side of the paper sheet not contacting the forming wire is called the top side (or called the obverse side and the blanket side). Wherein, the roll surface of the non-vacuum couch roll 107 is not provided with through holes for forming a vacuum environment, so that no vacuum pressure difference exists between the forming net and the roll surface of the non-vacuum couch roll 107.
Unlike the prior art vacuum couch roll, the non-vacuum couch roll 107 does not press the sheet (i.e., the sheet is not dewatered at the non-vacuum couch roll 107) and the forming wire passes around the non-vacuum couch roll 107 to make a return pass back to the breast roll 102, while the non-vacuum couch roll 107 imparts power to the forming wire and the sheet is stripped from the forming wire at a point after the non-vacuum couch roll 107. Because the paper sheet is subjected to plane dehydration only by the plane dehydration forming section from the breast roll 102 to the non-vacuum couch roll 107, the loss of fine fibers, fillers and the like can be effectively reduced, the fiber structure of the net surface is more compact, and a good foundation is created for the high-index smoothness of the subsequent production of single-sided smooth paper.
In one embodiment, the horizontal dewatering section of the fourdrinier wire forming assembly 10 can be increased in length to accommodate more planar dewatering elements to enhance the dewatering capacity of the fourdrinier wire forming assembly 10, for example, the number of dewatering plates 104 and rough vacuum boxes 105 can be increased to increase the planar dewatering area in the rough vacuum state to achieve the same dewatering level as the vacuum couch rolls used in the prior art, and to obtain 17-19% dry paper.
As shown in FIGS. 3-4, in one embodiment, sheet press assembly 20 includes: a three-roller two-press area unit 21, a blanket belt transferring unit 22 and a vacuum carrier roller pressing unit 23; the three-roller two-pressing area unit 21 is used for performing secondary pressing on a paper sheet; the transfer blanket belt unit 22 is used for supporting a paper sheet and transferring the paper sheet from the three-roller two-press area unit 21 to the vacuum carrier roller pressing unit 23; the vacuum idler press unit 23 is used to dewater the paper sheet.
Different from the prior art, this application has creatively designed three-roller two-nip unit 21, and three-roller space height is compact, and three-roller two-nip unit 21 can carry out the secondary to the paper web on the smooth surface of center roll squeezes, opens the paper guide again when the paper reaches suitable dryness fraction, can continuously generate smoothness degree and can strengthen the wet strength of low ration tissue at the first opening paper guide position again, reduces the paper breakage rate of low ration tissue when the operation.
Wherein the three-roll two-nip unit 21 is located between the fourdrinier wire forming assembly 10 and the transfer belt unit 22.
Wherein, three-roller two-nip unit 21 includes: a composite vacuum press roller 211, a center press roller 212, a press roller 213, a first pressure pump 214, and a second pressure pump 215, the center press roller 212 being equipped with an open feed blade and a cleaning blade.
The composite vacuum press roll 211, the center press roll 212 and the first pressure pump 214 constitute a first nip P1, and the press roll 213, the center press roll 212 and the second pressure pump 215 constitute a second nip P2. The paper sheet enters the first press nip P1 and the second press nip P2 in sequence and is in secondary contact with the smooth roll surface of the central press roll 212, so that secondary pressing of the paper sheet (namely, double back pressure of the first press nip P1 and the second press nip P2) is realized, the mesh surface is smooth, dryness of the paper sheet in the open paper guiding process can be improved, and paper guiding is facilitated.
Specifically, in the first nip P1, the composite vacuum pressing roll 211 is used as a lower pressing roll, the central pressing roll 212 is used as an upper pressing roll, the paper sheet is pressed for the first time, and the linear pressure of the first nip P1 is 70-110 kN/m. In the second nip P2, the press roll 213 is used as an upper press roll, the center press roll 212 is used as a lower press roll, the paper sheet is pressed for the second time, and the linear pressure of the second nip P2 is 110-150 kN/m.
The composite vacuum press roll 211 comprises a first vacuum chamber, a second vacuum chamber and a third vacuum chamber which are sequentially arranged inside the composite vacuum press roll 211; the first vacuum chamber is used for vacuum suction of paper sheets from the fourdrinier wire forming assembly 10, and the vacuum degree of the first vacuum chamber is 45-55 kPa; the second vacuum chamber is used for keeping the paper on the blanket belt, and the vacuum degree of the second vacuum chamber is 45-55 kPa; the third vacuum chamber is used for dehydrating the paper sheets, and the vacuum degree of the third vacuum chamber is 55-65 kPa.
Wherein, the composite vacuum pressure roller 211 includes: the roller surface hardness of the composite vacuum pressing roller 211 is 15-19P & J, blind holes are formed in the surface of the composite vacuum pressing roller 211 besides through holes used for forming a vacuum environment, and the water holding rate can reach 41-43%.
Wherein, the center press roller 212 includes: the surface roughness of the central pressing roll 212 is 0.4-0.8 mu m.
Wherein the press roller 213 includes: the carbon steel roller body and the polyurethane layer coating the carbon steel roller body, the hardness of the pressing roller 213 is 19-21P & J, and the surface of the pressing roller 213 is provided with blind holes with the water-containing rate of 16-20%.
Compared with the prior art, the paper web surface continuously bears secondary pressing on the smooth roll surface of the central stone roll, and the smoothness of the paper can be further improved on the basis of higher fiber compactness of the web surface; after vacuum pressing of the paper sheet by the first press nip P1 and blind hole pressing of the paper sheet by the second press nip P2, the dryness of the paper sheet reaches 35 percent, so that the wet strength of the low basis weight tissue at the first open paper leading position can be enhanced, and the paper breaking rate of the low basis weight tissue in operation is reduced; because the secondary pressing of the paper sheet is completed by concentrating on the position of the central stone roller, the three rollers have compact space, and are beneficial to the straight falling treatment of broke and the operation of the press roller.
In one embodiment, transfer blanket unit 22 comprises: transfer blanket 221, correction roll, tension roll, blanket guide roll, drive roll, associated blanket adjusting device and transfer blanket washer; the transfer blanket belt 221 is wrapped on the correcting roller, the tensioning roller and the driving roller; associated carpet adjusting means to correct the transfer carpet 221; the tensioning roller keeps the running states of tension and the like for adjustment; the transfer blanket washer is arranged in the circulation path of the transfer blanket 221 to wash the transfer blanket 221.
Wherein, the transfer blanket belt 221 connects the three-roll two-nip unit 21 and the vacuum carrier roller press unit 23.
Wherein the transfer blanket belt 221 is a light blanket belt with low gram weight (800-1000 gram weight/square meter) or a high air permeable dry net, and the tension of the transfer blanket belt 221 is 3.5-5.5 kN/m.
As shown in fig. 5 and 6, prior art paper sheets are pressed prior to entering the yankee nip using a two-roll, two-felt press unit, wherein the smooth sheet web, having been in contact with the smooth roll surface, is again in contact with the felt fabric in the two-roll, two-felt nip, and is affected by the felt fabric marking, resulting in a loss of existing smoothness and a low sheet dryness, which is likely to result in paper breaks.
In distinction to the prior art, the present application originally designed transfer blanket unit 22 (shown in fig. 8 and 9) to transfer the paper sheet peeled off from center press roll 212 of three-roll two-nip unit 21 to transfer blanket 221 by means of a paper guide roll; no press roll (i.e., no nip) is provided in transfer blanket unit 22, transfer blanket 221 is only used to support and transfer the sheet, and the supported sheet no longer passes through the nip, allowing the sheet with its wire side already formed smoothness to be transferred to the next location by transfer blanket 221 in a natural state without impairing the existing smoothness, i.e., transfer blanket unit 22 protects and maintains the smoothness of the wire side already formed in three-roll two-nip unit 21; the paper sheet is made to run from the fourdrinier wire forming unit to the vacuum roller pressing unit 23 in the whole process, the net surface with the dense surface is only contacted with the smooth roller surface under the pressurizing condition, the influence of pressing blanket belts on paper surfaces with smoothness is avoided, and the smoothness and the glossiness of the paper sheet are maintained.
As shown in fig. 3, in one embodiment, the vacuum roll press unit 23 includes: a vacuum idler 231, an idler blanket belt 232, and a yankee dryer 233. A carrier roller blanket 232 wraps around the vacuum carrier roller 231 and cooperates with the vacuum carrier roller 231 to transfer the sheet to the yankee dryer 233. The yankee drying cylinder 233 and the vacuum carrier roller 231 form a hot press.
The vacuum idler 231 includes a fourth vacuum chamber and a fifth vacuum chamber sequentially disposed inside the vacuum idler 231. The fourth vacuum chamber is used for sucking the paper sheets from the transfer blanket belt unit 22 and keeping the paper sheets on the carrier roller blanket belt 232, and the vacuum degree of the fourth vacuum chamber is 50-60 kPa; the fifth vacuum chamber is used for dehydrating the paper sheets, and the vacuum degree of the fifth vacuum chamber is 55-65 kPa.
The vacuum carrier roller 231 comprises a stainless steel roller body and a polyurethane adhesive layer coating the stainless steel roller body, the wall thickness of the stainless steel roller body is larger than or equal to 50mm, the thickness of the polyurethane adhesive layer is larger than or equal to 20mm, the hardness of the vacuum carrier roller 231 is 15-20P & J, through holes and blind holes used for forming a vacuum environment are formed in the outer surface of the vacuum carrier roller 231, and the through holes and the blind holes used for forming the vacuum environment account for 30-32% of the outer surface area.
Wherein, the cylinder body material of the Yankee dryer 233 is HT300 alloy cast iron, the cylinder body diameter is 3660mm or 4500Mmm, the cylinder body wall thickness is 65mm, and the cylinder body surface width is 4200 mm. The cylinder cover of the Yankee drying cylinder 233 is made of HT300 alloy cast iron, and the material of the in-cylinder pull rod is ZG 4. The bearing seat of the Yankee dryer 233 is made of HT300 alloy cast iron. The bearing device of the Yankee dryer 233 is an SKF bearing, and the surface hardness of the Yankee dryer 233 is HB 220-240.
Wherein the steam working pressure of the Yankee dryer 233 is 0.65Kpa, and the design steam pressure of the Yankee dryer 233 is 0.8 MPa.
Wherein, the roughness of the cylinder surface of the Yankee drying cylinder 233 is 0.2 μm, and the Yankee drying cylinder is manufactured by high-precision grinding processing of an excircle.
As shown in fig. 7, the prior art two-roll, two-felt press unit has a nip formed by an upper press roll and a lower press roll, each of which wraps the felt. In the existing single-paper machine, paper sheets are usually reversely fed into a Yankee dryer from bottom to top, the paper sheets are adsorbed only by the water content in a blanket, and the paper sheets are separated from the blanket by air flow formed at a speed, so that the improvement of the running speed of the paper machine is hindered.
Different from the prior art, the application originally designs the vacuum carrier roller 231 and the carrier roller blanket belt 232 which are matched with the Yankee drying cylinder 233, the paper sheet is adsorbed from the transfer blanket belt and is kept on the carrier roller blanket belt 232 by means of the vacuum negative pressure of the fourth vacuum chamber inside the vacuum carrier roller 231, the paper sheet is transferred to the nip of the Yankee drying cylinder 233 through the carrier roller blanket belt 232, and meanwhile, the paper sheet is dewatered by means of the vacuum negative pressure of the fifth vacuum chamber inside the vacuum carrier roller 231.
Because the paper is safely drawn by the vacuum adsorption effect of the vacuum chamber in the vacuum carrier roller 231 (as shown in fig. 8), the vacuum pressure difference is balanced with the centrifugal force generated by the paper during moving, so that the paper cannot be separated from the blanket belt, and the paper can be safely drawn under the high-speed operation of the paper machine. Thus, the operation of opening the draw from bottom to top to the Yankee cylinder 233, which prevents an increase in the machine speed in the prior art single-strand machines, is eliminated.
Applicants have studied the compression of the paper sheet in the present paper sheet press assembly 20 and the prior art two roll, two felt press unit, as shown in fig. 5-6, 9-10, and tables 1-2.
Table 1 web under compression in the sheet press assembly of the present application
Table 2 sheet web under pressure in a prior art two roll, two felt press unit
The applicant finds that the papermaking speed of the tissue fourdrinier papermaking equipment can reach 450-500 m/min and the guarantee smoothness value of the tissue fourdrinier papermaking equipment can reach more than 500-600 s for single-sided smooth paper sheets of the same variety and the same fixed quantity of 30gsm after experimental verification. The paper making speed of the paper machine in the prior art is less than or equal to 400m/min, and the guarantee smoothness value of the paper machine in the prior art is less than or equal to 300 s.
The applicants have studied the fiber distribution of the paper sheet in the fourdrinier wire forming section, and believe that the degree of fiber densification of the wire side in contact with the fabric web is the initial basis for the smoothness improvement of the subsequent sheet.
Different from the vacuum couch roll adopted in the prior art, the non-vacuum couch roll does not extrude paper (namely, the paper is not dewatered at the position of the non-vacuum couch roll), so that the loss of fine fibers, fillers and the like can be effectively reduced, the fiber structure of the net surface is more compact, and an initial foundation is laid for improving the smoothness of single-sided smooth paper in subsequent production.
Applicants have also studied the effect of press unit structure on sheet surface properties, and believe that a smooth surface of the press roll will develop and improve smoothness when the web is under compression.
Different from the prior art, this application has creatively designed three-roller two-nip unit 21, and three-roller space height is highly compact, and three-roller two-nip unit 21 can carry out secondary pressing to the paper continuously, opens the paper guide again when the paper reaches suitable quality.
Compared with the prior art, the paper web surface continuously bears secondary pressing on the smooth roll surface of the central stone roll, and the smoothness of the paper can be further improved on the basis of higher fiber compactness of the web surface; meanwhile, the wet strength of the low-basis-weight tissue at the first-time open paper-leading position can be enhanced, and the paper breaking rate of the low-basis-weight tissue in operation is reduced.
Applicants have studied the effect of the fabric surface structure of the press belt on the surface characteristics of the paper sheet and believe that in the prior art, the woven face of the press belt, in which the paper sheet web is in contact with the belt under compression, weakens and reduces the smoothness to which the paper sheet web has been formed. As shown in FIGS. 5 to 6 and 9 to 10.
Different from the prior art, the transfer blanket unit of the original design of the present application, as shown in fig. 9, has no press roll (i.e. no press nip) in the transfer blanket unit, and the transfer blanket is only used for supporting and transferring paper sheets, and the supported paper sheets do not pass through the press nip, so that the paper sheets with the net surface formed with smoothness are naturally transferred to the next position by the transfer blanket; the influence of the pressing blanket belt on the press surface with smoothness is avoided, the existing smoothness is not weakened, and the smoothness and the glossiness of the paper sheet are maintained.
The above embodiments are merely examples and are not intended to limit the scope of the present disclosure, and all modifications, equivalents, and flow charts using the contents of the specification and drawings of the present disclosure or those directly or indirectly applied to other related technical fields are intended to be included in the scope of the present disclosure.
Claims (10)
1. A tissue fourdrinier papermaking plant, characterized in that it comprises at least: a fourdrinier wire forming assembly and a sheet pressing assembly disposed downstream of the fourdrinier wire forming assembly;
the fourdrinier wire forming assembly comprises: the device comprises a forming net, and a breast roll, a forming plate, a dewatering plate, a low vacuum suction box, a high vacuum suction box, a non-vacuum couch roll, a net driving roll, a net guide roll, a correcting roll, a tensioning roll, a forming net state adjusting device and a white water tank which are sequentially arranged along the lower surface of the forming net;
the sheet press assembly includes: a three-roller two-pressing area unit, a blanket belt transferring unit and a vacuum carrier roller pressing unit;
the three-roller two-pressure area unit is used for carrying out secondary pressing on a paper sheet before open paper guiding;
the transfer blanket belt unit is used for supporting a paper sheet and transferring the paper sheet from the three-roller two-press area unit to the vacuum carrier roller pressing unit;
the vacuum carrier roller pressing unit is used for dewatering paper sheets.
2. The apparatus of claim 1, wherein the roll surface of the non-vacuum couch roll is free of through holes for creating a vacuum environment such that no vacuum pressure differential exists between the forming wire and the roll surface of the non-vacuum couch roll.
3. The apparatus of claim 1, wherein the three-roll secondary nip unit comprises: the composite vacuum pressing roll, the central pressing roll, the upper pressing roll, the first pressurizing pump and the second pressurizing pump form a first pressing area, and the upper pressing roll, the central pressing roll and the second pressurizing pump form a second pressing area;
and the paper sheet enters the first press nip and the second press nip in sequence and is in secondary contact with the smooth roll surface of the central press roll so as to realize secondary pressing of the paper sheet.
4. The apparatus of claim 1, wherein the transfer blanket unit comprises: the carpet transferring device comprises a carpet transferring belt, a correcting roller, a tensioning roller, a carpet guiding roller, a driving roller and an associated carpet adjusting device;
the transfer blanket belt is wrapped around the correcting roller, the tensioning roller, the blanket guiding roller and the driving roller.
5. The apparatus of claim 1, wherein the vacuum idler press unit comprises: the paper sheet dewatering device comprises a vacuum carrier roller, a carrier roller blanket belt and a Yankee drying cylinder, wherein the carrier roller blanket belt is wrapped on the vacuum carrier roller and is matched with the vacuum carrier roller so as to transfer paper sheets to the Yankee drying cylinder, and the vacuum carrier roller and the Yankee drying cylinder form a pressing area to dewater the paper sheets.
6. The apparatus of claim 3,
the composite vacuum press roller comprises a first vacuum chamber, a second vacuum chamber and a third vacuum chamber which are arranged in the composite vacuum press roller in sequence;
the first vacuum chamber is used for sucking paper sheets from the forming net of the fourdrinier wire forming assembly, and the vacuum degree of the first vacuum chamber is 45-55 kPa;
the second vacuum chamber is used for keeping the paper on the blanket belt, and the vacuum degree of the second vacuum chamber is 45-55 kPa;
the third vacuum chamber is used for dewatering paper sheets, and the vacuum degree of the third vacuum chamber is 55-65 kPa.
7. The apparatus of claim 4, wherein the transfer blanket belt connects the three-roll two-nip unit with the vacuum idler press unit;
the transfer blanket belt is a light blanket belt or a dry net with the weight of 800-1000 grams per square meter;
the tension of the transfer blanket belt is 3.5-5.5 kN/m.
8. The apparatus of claim 5,
the vacuum carrier roller comprises a fourth vacuum chamber and a fifth vacuum chamber which are sequentially arranged inside the vacuum carrier roller;
the fourth vacuum chamber is used for sucking paper sheets from the transfer blanket belt unit and keeping the paper sheets on the carrier roller blanket belt, and the vacuum degree of the fourth vacuum chamber is 50-60 kPa;
the fifth vacuum chamber is used for dewatering paper sheets, and the vacuum degree of the fifth vacuum chamber is 55-65 kPa.
9. The apparatus of claim 5,
the vacuum carrier roller and the Yankee drying cylinder form hot pressing.
10. The apparatus of claim 9,
the steam working pressure of the Yankee dryer is 0.65Kpa, and the design steam pressure of the Yankee dryer is 0.8 MPa; and is provided with a hot air exhaust hood;
the roughness of the cylinder surface of the Yankee drying cylinder is 0.2 mu m, and the cylinder surface of the Yankee drying cylinder is manufactured by high-precision grinding of an outer circle.
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| CN202110902580.3A CN113737559B (en) | 2021-08-06 | 2021-08-06 | Thin sheet fourdrinier papermaking equipment |
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| CN202110902580.3A CN113737559B (en) | 2021-08-06 | 2021-08-06 | Thin sheet fourdrinier papermaking equipment |
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| CN113737559B (en) | 2023-07-18 |
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