JPH03206196A - Paper making method - Google Patents

Abstract

PURPOSE: To efficiently carry out papermaking without breaking paper by mounting a press felt for travel in an endless path, heating the felt, supporting wet rolled paper on a surface of the felt, passing the heated felt and supported paper between a pair of press rolls, passing them through drying roller, reheating the rolled paper and separating and drying the rolled paper. CONSTITUTION: A press felt 6 for travel is mounted in an endless path and the felt 6 is heated and wet paper web 5 is supported on the surface of heated felt 6 and the heated felt 6 and supported web 5 are passed through a nip between a pair of cooperating press rollers 3 and 4 to extract water from the web and led from the nip to a first upper dried roller 9 of a series of heated dried rollers to dry the felt 6 and the rolled paper web 5 and the felt 6 is separated from the rolled paper web 5 and the rolled web 5 is dried by a second drying roller 10 and the felt is brought into contact with a drying fiber 12 so as to promote drying of rolled web 5 to provide the rolled web.

Description

[Detailed description of the invention] The present invention relates to a paper manufacturing method.

Conventional papermaking machines include a press section having one or more cooperating press rollers, in which the wet paper web is supported on papermaking felt as it passes through a nip between the cooperating rollers, thereby transferring water to the paper. Extract from. After leaving the press section, the paper is sent to a drying section, which may consist of a plurality of heated drying rollers.

The paper then passes around drying rollers to further remove moisture from the paper.

In such equipment there is a substantial draw or spacing between the pressing section and the drying section. Since the paper is quite wet and heavy, it may sag and tear in this draw. Paper machines operate at speeds of approximately 2000 feet per minute, and if the paper tears, the paper must be re-fed through the entire press and drying section, which not only results in loss of production but also This also causes substantial downtime.

Draw sag between the press and drying sections can be minimized by increasing the paper tension, or increasing tension will correspondingly increase the paper's tendency to stretch and tear.

The drying section of a conventional papermaking machine usually consists of about 10 cans.
12 of the above heated drying rollers or cylinders;
The first or upstream roller where the wet paper is fed from the press section of the machine is at a lower temperature than the other downstream rollers. In fact, the upstream drying roller has a surface temperature of approximately 140° F. to 150° F., and the surface temperature of the next several downstream rollers increases sequentially to values of approximately 280' F. to 325° F.
This high surface temperature is maintained on all other rollers in the series. By keeping the temperature of the first drying roller at a low value, possible blistering and glabellar peeling of the paper wrapper is prevented, and the lower temperature reduces the tendency of the paper wrapper to stick to the roll.

The present invention relates to a paper making machine in which the wet paper web is supported by the press section felt as it is fed from the press section of the machine to the drying section, thereby preventing possible sagging and tearing of the paper. The press section includes a pair of cooperating press rollers and an endless papermaking felt that supports the paper as it passes between the press rolls to extract water from the wet paper.

The paper machine also includes a drying section consisting of a group of heated drying rollers, the press section felt moving from the press rollers of the press section and passing around at least one drying roller, whereby the felt transfers the wet paper to the press section and drying section. It acts to support the interpart spacing or draw and separates the paper from the drying roller.

Since the wet paper is supported in the draw, possible sagging and tearing of the paper is prevented in this area.

Since the tendency to tear is minimized, production losses are minimized and machine downtime is correspondingly reduced.

Because the press felt is interposed between the heated drying roller and the paper, the web is separated from the heated roller, so that the drying roller is operated at a substantially higher temperature than normal. By increasing the surface temperature of the upstream drying rollers, the number of drying rollers in the drying section can be reduced, thereby providing substantial cost savings.

Another advantage is that after passing in contact with heated drying rollers,
The press felt possesses a heating part during its endless transfer,
This exposes the felt to high temperatures as it passes through the nip between the press rollers. As the temperature of the felt at the nip increases, the viscosity of the water in the paper decreases, thereby increasing the effectiveness of water extraction at the nip and thus reducing steam consumption in the drying section.

Other objects and advantages will become apparent from the description below.

The figures show the best presently contemplated example of implementing the invention.

The example diagram shows a schematic system diagram of a part of a paper making machine including a press section 1 and a drying section 2. The press section 1 includes a pair of cooperating press rollers 3 and 4, and the wet web 5 is supported by a papermaking felt 6 as it passes through the nip between the press rollers 3 and 4. The paper may be any type of paper, preferably a heavy paper such as corrugated cardboard, newsprint, writing paper, etc.

The papermaking felt 6 has an endless shape and is made of natural fibers,
Vine made of synthetic fibers or a combination thereof.

The particular composition or composition of the felt is not important to the invention.

Felt 6 is shown in Figures 7a-71. The endless feed path is supported by a plurality of idle rollers. Furthermore, the felt 6 passes around a tensioning or stretching roller 8 located between rollers 7f and 7g.

Roller 8 operates in a conventional manner to provide the desired tension on felt 6.

The drying section 2 has a plurality of conventional heated drying rollers, three of which are designated 9, IO and AE in the figure. actually,
The drying section includes ten or more dryers that are steam heated to temperatures ranging from 150'F to 280F. The temperature of the group of rollers varies with the highest temperature at the downstream end of the drying section.

In one installation, there is a large spacing or draw between the press section 1 and the dryer section 2, with this draw being nearly 15 feet from the IO. When handling heavy papers such as corrugated cardboard, the paper has a tendency to sag in the draw between the press section 1 and the drying section 2, as a result of which the paper leaves the press section quite wet and heavy.

If the paper tears, the paper from the forming section must fall to a waste location and is re-supplied via the press section to the drying section. Refeeding the paper takes 30 to 40 minutes, and this downtime causes a certain reduction in the production rate of the paper machine.

The felt 6 from the pressing section passes around at least one drying roller or cylinder in the drying section in order to reduce sagging of the paper in the draw between the pressing section and the drying section, thereby preventing possible tearing of the paper. . As shown, the felt passes around the drying roller 9 and thus supports the paper in the draw between the press roller 3.4 and the drying roller 9.

As shown, the paper 5 is located outside the felt 6 as it passes around the drying roller 9, and the paper moves around the rollers 10 and 1l. Conventional drying fibers 12 are attached to an endless path in the drying section and move around a pair of idle rollers l3 as shown. The drying fibers I2 operate in a conventional manner to support the paper against the heated drying roller to aid in removing moisture from the paper.

In some devices, the first or upstream heated drying roller in the drying section has a smaller diameter than the drying roller in the drying section and is therefore referred to as a "baby" roller or can.

As shown, the press felt 6 is heated by a heated upstream drying roller 9
and paper 5, thus isolating the wrapping paper from the heating roller. Because of isolation effects, drying roller 9 is typically about 240' as opposed to conventional devices where upstream drying rollers such as roller 9 operate at temperatures of about 140°F to 150°F.
Vine operates at higher than normal temperatures ranging from 280'F to 280'F. This also allows subsequent downstream drying rollers such as 10 or 11 to be operated at higher temperatures than previously. for example,
The drying roller 10 in direct contact with the paper 5 has a surface temperature of 140 DEG F. to 160 DEG F., which is higher than that used in conventional methods. Therefore, the final high temperature of about 280'F is reached early in the drying section, thus greatly improving the effectiveness of the drying operation and allowing fewer drying rollers to be used in the drying section.

As a further advantage, the press felt 6 passing over the heated drying roller 9 is heated and retains a sufficient portion of heating during its endless travel, so that the felt returning to the nip between the press rollers 3 and 4 reaches 120' F. or above, generally in the range of about 140°F to 180°F. This increased temperature causes a decrease in the viscosity of the water, thus causing more effective water extraction at the nip. Temperature at each nip is 180°F
It was found that for every increase in water removal, water removal increases by 1%. In a conventional paper making machine, the paper passes through the press roller 3
and 4, typically at a temperature of about 100°F. This temperature ranges from 140°F to 1°C in the present invention.
As the temperature rises to the 80° F. range, an increase in water removal of 2% or more is achieved, resulting in substantial energy savings in overall operation.

The position and number of idle rollers 7 in the press are not critical; different paths of movement for the felt are conceivable depending on the requirements of the paper machine.

[Brief explanation of drawings]

The figure is a diagram of a portion of a papermaking machine incorporating the present invention. DESCRIPTION OF SYMBOLS 1...Press part, 2...Drying part, 3.4...Press roller, 5...Wrapping paper, 6...Felt, 7a-7
1, l3... Idle roller, 8... Enlarger roller,
9,10.11... Drying roller, 12... Drying fiber.

Claims (10)

[Claims] (1) Attach a moving press felt to an endless track, heat the felt, support a wet wrapping paper on the surface of the heated felt, and a nip between a pair of cooperating press rollers to extract water from the paper. passing the heated felt and supported paper through an interval the distance from the nip to the first upstream drying roller of a series of heated drying rollers; A drying roller and the felt are placed in direct contact with the paper spaced from the drying roller, thereby reheating the felt and heating the paper wrapper, separating the paper wrapper from the heated felt, and removing the paper. A method of papermaking comprising the step of passing the paper wrapper around other downstream rollers in the series for drying. 2. The method of claim 1, wherein said felt is heated to a temperature in the range of 140°F to 180°F. (3) the first upstream drying roller from 240°F to 280°F;
Claim 1 comprising the step of heating to a surface temperature in the range of °F.
Method described. (4) A series of heated drying rollers including a first upstream drying roller is provided, the first drying roller is heated to a temperature equal to or higher than the temperature of a second downstream drying roller in the series, and the press felt is transported through an endless path. passing the press felt and wet wrapping paper through a nip between a pair of press rollers;
The felt and the paper are passed around the first drying roller with the felt disposed between the paper and the drying roller, thereby heating the felt and paper, separating the paper from the felt, and passing the paper through the first drying roller. A method of papermaking comprising the steps of: passing the heated felt around another downstream drying roller and returning the heated felt to the nip in position supporting the wet web. 5. The method of claim 4 including the step of: (5) maintaining the heated felt at a temperature of about 120 degrees Fahrenheit as it is returned to the nip. (6) The first drying roller is 240°F to 280°F.
5. The method of claim 4, wherein the method is heated to a temperature in the range up to . 7. The method of claim 6, including the step of: (7) heating the second drying roller to a temperature in the range of 180°F to 200°F. 8. The step of bringing the felt into direct contact with the first drying roller comprises wrapping the felt around the first drying roller over an arc of at least 90 degrees. Method. 9. The method of claim 1, wherein the step of directly contacting the felt with the first drying roller comprises the step of wrapping the felt around the first drying roller through an arc of approximately 180 degrees. . (10) installing a moving press felt in the endless path, positioning a first upstream drying roller of a series of drying rollers in the endless path so that the felt passes in direct contact with the first drying roller; A first drying roller is heated to a high temperature, a wet paper wrapper is supported on the felt, the felt and supported paper are passed through a push nip, thereby extracting water from the paper, and then the felt and Passing the supported paper around the first heated drying roller, the felt moves the paper away from the heated drying roller, thereby heating the felt and the paper, separating the paper from the felt, and drying the paper. passing the heated felt around the other downstream drying rollers in the series and returning the heated felt to a push nip at a position supporting the paper wrapper.