RU1770499C - Paper-making machine - Google Patents

Abstract

Usage: in the pulp and paper industry for the production of a wide range of papers. SUMMARY OF THE INVENTION: a machine includes a pressure box, a dewatering zone of paper pulp on a wire mesh, a drying zone with a cylinder for drying paper web in an arc of at least 270 ° its circumference, pressing zone and knurling. The dewatering zone has a second mesh, covering together with the first drying zone, and means for providing a mesh speed that is 5-10% lower than the peripheral speed of the cylinder surface. The pressing zone consists of a double press. Before rolling, a drying group was mounted, the first cylinder of which has a common cloth with the second press shaft, 1 ml.

Description

The invention relates to the pulp and paper industry and can be used to produce a wide range of papers. For the production of paper (paperboard), paper machines (PM) are used in various designs. The main processes involved in the production of paper are the forming and dewatering of the paper web in the mesh part of the paper machine, the dewatering and compaction in the press section and the drying of the paper in the drying section of the paper machine.

A known design of a paper machine by Swedish company KMV, including a pressure box, a paper drying cylinder, a press net located around it, a speed drying hood, a paper scraper. At low tide, a mass with a temperature of 70-80 ° C from the pressure box is fed directly into the gap between the hot surface of the cylinder and shogko /. Formed paper positively (PRPR. He goes around the cylinder and

sequentially passes through the press, the zone of high-speed drying and then with the help of a scraper it is separated from the surface of the cylinder and wound into a roll.

The main disadvantage of this machine is the feeding directly to the hot surface of the drying cylinder of a fibrous suspension of low concentration, which leads to a significant heat consumption for evaporation of water and an increase in the temperature of the web in the forming zone, the possibility of burning the side of the paper in contact with the cylinder surface, and the need to shift the paper web along the surface of the cylinder and its partial creasing (creping) for subsequent separation from the surface of the cylinder. This machine can only produce thin (15-20 g / m2) crepe paper.

A prototype of the proposed technical solution is a paper machine containing a dehydration zone and a press in front of the drying cylinder (Л

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nor providing feed to the drying cylinder pre-dehydrated canvas.

The main disadvantage of the prototype is a decrease in the quality of paper when producing paper weighing more than 40 g / m2 as a result of high breakage of the paper web and the possibility of burning paper to the surface of the cylinder due to the increased humidity of the paper web.

The aim of the invention is to improve the quality of paper weighing 40-120 r / m2 due to the development of paper machines, providing optimal conditions for dewatering, drying and pressing of the paper web.

The essence of the proposed technical solution consists in the fact that in a paper machine containing a pressure box, it is hard to de-empt paper pulp on a wire mesh, a drying zone with a cylinder for drying the paper web on an arc not less than 270 ° of its circumference, the pressing and rolling zone, in order to increase quality paper weighing from 40 to 120 g / m2, the dewatering zone has a second mesh, covering together with the first drying zone, and means for ensuring the mesh speed is 5-10% less than the peripheral velocity of the surface of the cylinder, while the pressing zone consists of tandem press, and before coasting mounted dryer group, the first cylinder which has a common shaft with the second press cloth. The use of a second grid allows the formation of a paper web between two grids and the ability to control the ratio of sheet strength in the machine and transverse directions.

The use of a second grid, covering the surface of the cylinder on an arc of at least 270 °, avoids direct contact of the paper web with the hot surface of the cylinder and allows the paper web to be removed from the cylinder without using a fastening process. The presence of a dewatering zone in front of the paper drying cylinder makes it possible to bring the dryness of the paper web fed to the hot surface of the cylinder to 10-12% and to provide optimal drying conditions for paper on the cylinder, and, therefore, its quality when producing paper weighing 40-120 g / m2 . Maintaining the mesh speed by 5-10% lower than the speed of the paper drying cylinder by using individual adjustable drives for the mesh and cylinder, allows the internal mesh to slip on the cylinder surface and to prevent its pollution due to sticking, burning of individual fibers to it or

particles of filler. The use of double presses allows to achieve maximum dewatering of the web, and its high temperature makes it possible

increase the volumetric weight of paper and its strength indicators.

The implementation of the additional drying part of the traditional design allows the use of the main

0 drying cylinder with optimum dimensions, to ensure reliability and ease of regulation of dry paper fed to the reel.

The implementation of the common with the second press roll and the first drying cylinder of the press cloth allows maintaining the required temperature in the pressing zone and simplifying the feeding of the paper web to the drying part.

0

The above set of features in conjunction is necessary and sufficient to achieve the goal, which indicates

5 according to the proposal criterion significant difference.

The drawing shows a longitudinal section B DM.

The proposed paper machine consists of a pilot box 1, nets 2, a preliminary dewatering zone 3, a paper drying cylinder 4, a drying hood 5, a double press 6, a press cloth 7, an additional drying group 8, a knurling 9,

5 The proposed PM works as follows.

Paper pulp with a temperature of 80-90 ° C, due to the use of a closed loop circulation system with heating and

0 by heat recovery, it enters the pressure box 1 from where it is fed into the gap between two grids 2 and dehydrated in the preliminary dehydration zone 3 to a dryness of 10-12%. Then the nets and those between

5 with them, the paper web is wrapped around the paper-drying cylinder 4. By using individual adjustable drives for the nets and the paper-drying cylinder, the speed of the nets is maintained at

0 5-10% lower than cylinder speed. In the upper zone of the cylinder above the cap 5, steam is intensively released from the web and its temperature rises. Then, the paper web with a dryness of 16-18% and a temperature of 80-100 ° C enters the gap of the press rolls 6. After the third capture, the web using common cloth 7 with a dryness of 40-60%, depending on the weight of 1 m, paper (40-120 g / m2) enters the additional drying group 8, where it is dried to the required dryness and wound from roll 9 into rolls.

The use of the proposed technical solution makes it possible to improve the quality of the formed web when producing paper weighing 40-120 g / m2.

Claims (1)

The claims A paper machine comprising a pressure box, a dewatering zone of paper pulp on a wire mesh, a drying zone with a cylinder for drying the paper web on 0 an arc of at least 270 ° of its circumference, a pressing and rolling zone, characterized in that, in order to improve the quality of paper weighing 40-120 r / m2, the dewatering zone has a second mesh, covering together with the first drying zone, and means for providing mesh speed, which is 5-10% less than the circumference of the surface velocity of the cylinder, while the pressing zone consists of a double press, and a drying group is mounted before rolling, the first cylinder of which has a common cloth with the second press shaft. 4