Paper machine classification and working principle


According to the structure of the paper machine net sec […]

According to the structure of the paper machine net section, the paper machine can be divided into: long net type, round net type, net type, stack type and with decorative rolls.

A paper machine can be seen as a combination of multiple devices. Usually divided into two parts: wet part and dry part. The wet end includes a slurry flow device, a wire portion, and a press portion: the dry portion includes a drying portion, a calender, and a winder.

After being formulated, sized, filled and purified, the slurry having properties suitable for papermaking enters the slurry flow device of the paper machine at a concentration of 0.3% to 1.3%. Further, after the paper material is distributed and leveled by the slurry flow distributor and the headbox, it is uniformly and stably flowed to the mesh surface of the moving mesh. After the pulp flow is online near the center line of the chest roll on the net case, it is gradually filtered and dehydrated to form a continuous wet paper web. Forming-dewatering elements such as case rolls, vacuum suction boxes, and roll rolls are usually provided on the net case. When the wet paper web is dewatered to a certain dryness (usually about 20%), it can be peeled off from the mesh surface and sent to the press section for dewatering.

The press section of a paper machine consists of several sets of roll presses. The wet paper web is pulled by the press felt and dehydrated by mechanical pressing between the press rolls. In order to maintain good dewatering performance of the press felt, the upper roll of the press is provided with a felt washing device. After the press section, the dryness of the wet paper web is generally about 40%.

The wet paper web is further dewatered on a paper machine, usually by evaporation by heating. The dryer section of a paper machine is typically composed of a number of dryers that are internally heated by steam. The dryer is covered with a dry blanket (or canvas, dry mesh) in order to press the web onto the cylinder surface to improve heat transfer efficiency and improve the surface quality of the web.

After drying, a calender consisting of 6-8 rolls is typically used to improve the surface quality of the web.

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