How does the paper machine work?

With the continuous progress of society, people's living standards have been greatly improved. Now paper and paper products are more and more widely used. People's daily life and work are inseparable from paper. Therefore, the demand for paper is very large, and the paper industry has become a long-term development industry.

A Paper machine is a necessary papermaking machine for every paper mill. The emergence of this machine replaces the traditional manual papermaking, which not only improves the quality of the paper but also improves production efficiency. According to the needs of the papermaking process, the structure of the paper machine is diverse, which is generally composed of flow, forming, pressing, drying, finishing It is composed of coiling, transmission, and other components and supporting equipment such as an auxiliary system. The working principle of the paper machine will be introduced in detail below.

The following is a list of contents:

• Structural composition of paper machine

• Classification of paper machines

• Working principle of paper machine

Structural composition of paper machine

A Paper machine can be regarded as a linkage machine composed of multiple types of equipment. It can usually be divided into two parts: the wet part and the cadre. The wet part includes slurry flow equipment, mesh part, and pressing part; the cadres include drying part, calendar, and paper coiler.

The press part of the paper machine is composed of several groups of roller presses. The wet paper web is supported and dragged by the press blanket and dehydrated by mechanical extrusion between the press rollers. To maintain the good dehydration performance of the pressed blanket, the upper roller of the press is equipped with a blanket washing device. After pressing, the dryness of the wet paper web can generally reach about 40%.

The wet web is further dehydrated on the paper machine, usually by heating, evaporation, and drying. The drying section of a paper machine is usually composed of many drying cylinders heated from the inside with steam. The drying cylinder is covered with a dry blanket (or canvas or dry net) To press the paper web tightly onto the cylinder surface, improve heat transfer efficiency and improve the surface quality of the paper web. After drying, a calendar composed of 6-8 rollers is usually used to improve the surface quality of the web.

Classification of paper machines

Traditionally, the paper machine is divided into a long mesh, round mesh, clip mesh, and long round mesh mixed models according to the type of paper shaper used; There are also cultural paper machines (including newsprint), paperboard machines (including packaging paper), toilet paper machines and special paper machines according to their main product varieties; Or according to the thickness of paper production, it can be divided into the thin paper machine, paperboard machine, and conventional paper machine.

Working principle of paper machine

The raw materials are changed into pulp with papermaking performance through pulp preparation, sizing, filling, and purification, and then ensure that the pulp is sent to the pulp flow equipment of the paper machine at the concentration of 0.3% - 1.3%. After the slurry is distributed and leveled by the slurry distributor and headbox, the slurry will be transported to the forming mesh surface in operation evenly and stably. The pulp flow is filtered and dehydrated on the screen to gradually form a continuous wet paper web. The net case parts are mainly provided with dewatering elements such as case roll, vacuum suction tank, couch roll, and so on. When the wet paper web formed on the mesh table is dehydrated to about 20% moisture content, it can be stripped from the mesh surface and sent to the pressing part for further dehydration.

The press part is composed of several groups of roller presses. The wet paper web is supported by the press blanket and dehydrated by mechanical extrusion between the press rollers. To maintain the good dehydration performance of the pressed blanket, the upper roller of the press is equipped with a blanket washing device. After pressing, the dryness of the wet paper web can generally reach about 40%.

The wet paper web dehydrated by the press section needs to be further dehydrated by heating and drying. The drying section of the paper machine is composed of many drying cylinders, which can be heated from the inside by steam. The drying cylinder is covered with a dry blanket to press the paper web tightly on the cylinder surface and improve the heat transfer efficiency. After thorough drying, a calendar composed of 6-8 rollers will be used to improve the surface quality of the overall web.

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