SU827663A1 - Dewatering arrangement of paper-making machine - Google Patents

Description

one

The invention relates to dewatering devices and is intended for use in the pulp and paper industry.

The dewatering devices are installed in that part of the grid table of papermaking machines where air is not sucked through the pulp layer (until the “bay mirror” disappears).

The known design of the suction box, which includes a suction chamber connected to a vacuum source, and a lid, made in the form of a frame with uniformly placed longitudinal strips along which the grid with dehydrated paper pulp 1 slides.

Under the influence of a vacuum in 1D, water from the paper pulp is filtered through a moving mesh, enters the suction chamber and is removed outside the paper machine.

The advantages of the specified suction box should include smooth dehydration, reducing the versatility of the paper web. However, the longitudinal strips of the drawer lid reduce the intensity of dehydration (since the filter-, water qi through the mesh goes only on the open part of the mesh between the slats) and abrades the mesh, reducing its service life.

The slats are also abraded and need to be replaced periodically.

The closest to the invention is a dewatering device containing

a suction chamber, sealing elements with supporting surfaces for the mesh and a set of bent plates with working edges 2 installed in the chamber. All sealing and dewatering

the elements have horizontal sections located in one plane along which the grid of the paper machine moves with a paper mass on it. Dehydrating elements also have

inclined sections forming an angle with horizontal grid sections up to 5 °.

When the net is moving with a mass in the gap between the net and the inclined sections of the defolders: a vacuum is created, under the influence of which water is filtered from the pulp through the net and removed by sharp leading edges of the dewatering elements into the suction box and further through the outlet nozzle of the papermaking machine. The sealing elements at the ends of the chamber in horizontal sections are adjacent to the grid and prevent air outflow (from the atmosphere) into the chamber. Suction chamber through the branch pipe

connected to a vacuum system that increases the dewatering rate of the paper pulp.

However, this construction has drawbacks. Dehydrating elements create a vacuum only in the gap between the screen and their inclined sections. These areas make up a small fraction of the area occupied by the dewatering elements under the screen. In order for the desalination not to cease in the free parts of the grid between the dewatering elements, a considerable vacuum must be created in the suction chamber, requiring additional energy. In areas of the grid adjacent to the horizontal planes of the dewatering elements, there is no filtration of water through the grid. In addition, a large number of working mesh elements leads to rapid wear of the mesh, reducing its service life. Increases power expended in moving the grid. The suction elements that are continuously in contact with the screen wear out and need to be replaced.

The purpose of the invention is to increase the rate of dewatering of paper pulp by continuously filtering water through a moving screen throughout the entire area occupied by the dewatering device.

This is achieved by the fact that the working edges of the bent plates are installed below the support surfaces of the sealing elements.

The dewatering device touches the screen only with sealing elements limiting the dewatering zone. This creates a continuous vacuum over the entire area of dehydration.

FIG. 1 shows a dewatering device, a general view; in fig. 2 is the same cross section.

Dehydrating device contains dewatering elements 1 in the form of inclined curved plates mounted in the suction chamber 2 with sealing (supporting) elements 3, 4 and 5, suction nozzles 6.

The sealing elements 3, 4 and 5 have horizontal sections 7, elements 3 and 4 have sharp leading edges 8.

The working edges 9 of the dewatering elements 1 are located 2-5 mm below the level of the horizontal sections 7 of the sealing elements.

Elements 1 have a slope relative to the fixed grid from 0 to 6 ° and form a wedge gap 11 with the grid 10.

The element (plate) 1 nearest to the sealing element 3 is flush with the edge 9 against the back wall of the element 3. Each subsequent plate 1 is positioned so that with its working edge 9 it enters the wedge gap 11 formed by the previous plate.

Elements 3, 4 and 5 are fixed on the walls of the suction chamber 2.

The plates 1 are fastened in the slots of the strips 12 fixed inside the chamber 2.

The suction nozzles 6 are connected, for example, to a vacuum system (not shown in the drawing).

The width of the suction chamber (in the direction of the mesh movement) is taken up to 500 mm. The number of plates 1 is selected according to the width of the chamber.

The grid 10 of the papermaking machine contacts the horizontal sections 7 of the elements 3, 4 and 5. The direction of movement of the grid is indicated by an arrow.

Dehydrating device operates as follows.

The grid 10 with a layer of paper pulp on it moves over the suction chamber 2, slipping along the horizontal working sections 7 of the supporting sealing elements 3, 4 and 5.

The water filtered from the paper pulp and forming a layer on the underside of the mesh is removed by the sharp edges 8 of elements 3 and 4. In this case, the horizontal portions 7 in contact with the mesh seal the internal cavity of the suction chamber 2.

Immediately after the end of the horizontal section 7 of the sealing element 3, in the wedge gap 11 increasing along the mesh, formed by the first inclined plate 1, a vacuum occurs, under the influence of which the water from the paper pulp is filtered through the mesh and fills the wedge gap.

The water entrained by the grid 10 moves in a continuous flow in the gap 11 and, meeting with the edge 9 of the next plate 1, is divided into two unequal flows. Most of the water forms the bottom flow, which goes under the edge 9 and enters the suction chamber 2. A thin layer of water passes over the edge 9 and forms the top flow (under the net), which flows into the wedge gap 11 formed by the next plate 1. At the same time, the vacuum is not disturbed and the water filtration is continuous.

The newly formed stream of water approaches the edge 9 of the next plate 1, and the process of separating the posok is repeated.

Thus, there is a continuous process of dewatering the pulp throughout the entire grid area bounded by the sealing elements 3, 4 and 5.

From the suction chamber 2, water through the branch pipes 6 is removed outside the paper machine.

In order to further increase the intensity of dehydration and the ability to control the process, the vacuum chamber 2 is connected, for example, to a vacuum system creating a small vacuum in the chamber.

The inclination angle of the plates 1 with respect to the fixed grid 10 is taken up to 6 °, since a further increase in the angle is inefficient.

Continuous uniform filtering of water through the mesh increases the dehydration rate and improves the quality of forming the paper web.

When moving, the grid 10 slides over the surfaces 7 of the sealing elements placed on the walls of the suction chamber up to 500 mm wide, and under the influence of its own weight, the layer of paper pulp and the vacuum under the grid slightly bends. However, due to the fact that the working edges 9 of the plates are lowered below the horizontal sections 7 of the sealing elements by 2-5 mm, the net does not touch the plates and moves over them with a gap.

The lack of contact between the grid and the dewatering elements during operation increases the service life of the grid and dewatering elements, increases the stability and reliability of the dewatering device.

The power expended is reduced.

to move the mesh.

By improving the quality of the molding, the stability and reliability of the individual elements of the equipment, the scrap on the machine is reduced.

Claims (2)

1. The patent of England No. 1307980, cl. D 2A, 1968. 2. US patent number 2928465, cl. 162-352, 1961 (prototype). 7 1 10 9 i And THEM//   7 10 I I