Basic structure of paper machine (3)
Driven by gears or driven by wool cloth, several drying cylinders form a group, and several groups of drying cylinders constitute the drying section. The linear speed of each group of drying cylinders can be adjusted separately to maintain a slight speed difference between each group of drying cylinders to compensate for the shrinkage of the paper during the drying process. The dryness of the paper leaving the dryer section is generally about 92-94%. At the end of the dryer section, a cold cylinder is generally equipped to allow moisture to condense on the surface of the cold cylinder. Condensed water can moisten the surface of the paper to facilitate better surface smoothness in finishing. The drying cylinder diameter is the best with 1.5m. Single-sided glossy paper can obtain higher single-sided gloss by using a large-diameter dryer with high hardness and high-gloss surface. The diameter of the large-diameter dryer is generally 3~7.5m.
Surface Finishing Department
Use multiple processes to achieve good surface quality. After the paper machine, most paper is calendered by a mechanical calender to make the paper surface smooth and consistent. The mechanical calender is made of several cold cast iron rollers, and the paper is flattened by the weight of each roller or another pressure. If higher surface smoothness is required, use a super calender for calendering. It is generally composed of paper meal rolls and chilled cast iron rolls arranged alternately. According to different requirements, some varieties need surface sizing to improve surface quality; some need surface coating to improve appearance quality or printing quality. Surface sizing and coating can be processed by a sizing machine and a coating machine outside the paper machine, or the sizing machine and coating equipment can be combined in the paper machine for in-machine processing.
All parts of the paper machine are connected and operated synchronously, so that the mechanical and electrical components are integrated. It is composed of mechanical deceleration device, speed regulation and speed stabilization device, sub-transmission device, etc., all using electric power as the power source.
White water system
It is a recovery, treatment and reuse system for the dehydration of the paper machine forming section. Including white water collection, transportation, filtration or sedimentation, air flotation and other equipment to separate and recycle fibers and fillers for reuse, and the entire system for recycling clean white water in the papermaking process.
It is composed of electrical system, vacuum system, lubrication system, workshop steam supply and exhaust system, waste paper treatment, compressed air system, steam supply, water supply and drainage system.