Classification of paper machines
According to the different structure of the wire part of the paper machine, the paper machine can be divided into: fourdrinier wire type, cylinder wire type, sandwich wire type, stacked wire type and facing roller type.
paper machine can be regarded as a kind of linkage composed of multiple devices. Usually it can be divided into two parts: wet part and dry part. The wet part includes the slurry flow equipment, the wire part and the press part: the dry part includes the dryer part, calender and reel.
After pulping, sizing, filling and purification, the pulp with properties suitable for papermaking enters the pulp flow equipment of the paper machine at a concentration of 0.3%-1.3%. Furthermore, after the paper material is distributed and evened by the flow distributor and the headbox to the slurry, it flows evenly and stably to the surface of the moving forming wire. After the pulp flows on the net near the center line of the breast roll on the screen, it is gradually filtered and dewatered to form a continuous wet paper web. The screen is usually equipped with forming-dewatering elements such as a table roll, a vacuum suction box, and a flat roll. When the wet paper web is dehydrated to a certain degree of dryness (usually about 20%), it can be peeled from the wire surface and sent to the press section to continue dehydration.
The press section of the paper machine is composed of several sets of roll presses. The wet paper web is dragged by the press felt and dewatered by mechanical squeezing between the press rolls. In order to maintain the good dewatering performance of the press felt, the upper press roll is equipped with a felt washing device. After the press section, the dryness of the wet paper web can generally reach about 40%.
The wet paper web is further dehydrated on the paper machine, usually by heating and evaporation drying. The dryer section of a paper machine usually consists of a number of drying cylinders heated from the inside with steam. The drying cylinder is covered with dry blanket (or canvas, dry net), the purpose is to press the paper web tightly to the cylinder surface to improve the heat transfer efficiency and improve the surface quality of the paper web.