What are the papermaking machinery and equipment?
Material preparation equipment
These are devices used to pretreat and process papermaking raw materials according to the requirements of the cooking or pulping process before cooking or pulping. They are divided into non-wood fiber preparation equipment and wood fiber preparation equipment. The former includes straw cutters, reed cutters, and sugarcane depigmenters, while the latter includes peeling machines and chippers.
Chippers are machines that cut logs into wood chips of a certain size for producing wood pulp, and are divided into disc type and drum type; digesters are devices that dissolve lignin in papermaking raw materials into cooking liquor, so that the papermaking raw materials are separated into fibers, and are divided into batch type and continuous type; grinders are devices for producing ground wood pulp, and can be divided into batch type and continuous type according to the production method, and into hydraulic pressurization type and mechanical pressurization type according to the method of pressurizing logs.
Pulping equipment
It is the equipment used in the process of separating plant raw materials into fibers. Pulping methods can be divided into chemical methods, mechanical methods, and chemimechanical methods. The corresponding pulping equipment includes digesters, wood grinders, thermomills, washing machines, bleaching machines, beaters, and waste liquor recovery equipment, etc.
The pulp produced by preheating wood chips with steam and then grinding them under high pressure is called hot wood chip milled pulp. The machine used to produce hot wood chip milled pulp is called a thermo-refining mill. Thermo-refining mills consume a lot of electricity, so making full use of the heat energy in the grinding process is a key issue for thermo-refining mills. A pulp washing machine is a mechanical device that separates the cooked pulp from the black liquor. According to the black liquor extraction rate, it is divided into two main categories: high concentration and low concentration extraction.
The purpose of pulp bleaching is to remove residual lignin and pigments from the pulp after cooking, thereby increasing its whiteness and giving the pulp a clean white color. A bleaching machine is a commonly used bleaching device, consisting of a bleaching tank, a screw propeller, a washing drum, and other components. The pulp and bleaching agent are placed in the tank, and wash water is continuously added. The bleaching agent circulates the pulp within the tank, completing the mixing and chemical reaction process. The water, containing bleaching products and residual bleaching solution, is discharged through the inner cavity of the washing drum, resulting in clean pulp.
Paper machine
A paper machine is a complete set of interconnected equipment that forms the paper web from pulp. It includes the headbox, wire section, press section, dryer section, calender, winding machine, and drive unit, as well as auxiliary systems such as steam, water, vacuum, lubrication, and heat recovery. The wire section, which forms the wet paper web, is the core of the paper machine. Therefore, paper machines can be classified according to the structure of the wire section into long-wire paper machines, double-wire paper machines, and cylinder paper machines.
The headbox is a device that delivers pulp of appropriate concentration evenly and stably to the wire through components such as a distributor, rectifyer, weir, and weir plate nozzles; it is also called the wire feed box. After the pulp is sprayed from the headbox onto the wire, it forms a wet paper sheet on the wire and undergoes dewatering. Next comes the pressing, which uses mechanical methods to squeeze out the water from the wet paper sheet coming out of the wire, increasing the dryness of the paper sheet, improving its surface properties, eliminating wire marks, and increasing smoothness, density, and strength. Then it enters the drying section, where the wet paper sheet after pressing is further dewatered, causing the paper sheet to shrink, the fibers to bond tightly, and the strength to increase.
After the paper sheets exiting the drying section are calendered, the smoothness, gloss, and density of the paper sheets are improved, resulting in a uniform thickness across the entire sheet and reduced air permeability. Finally, the paper sheets are wound into rolls by a paper reel, completing the main papermaking process. To accommodate different needs later on, supercalenders, rewinders, and paper cutters are also installed after the paper reel in the papermaking workshop.
Lubrication methods for papermaking equipment
Pulp and paper machinery includes two main categories: pulp machinery and papermaking machinery, as well as paper decoration and processing equipment. Specific lubrication methods are as follows:
1. Lubrication of pulp machinery
Pulp machinery includes two types of equipment: material preparation and pulping. The lubrication characteristics of pulp machinery are a humid, high-temperature working environment, coupled with impact loads. Generally, it requires anti-oxidation and anti-rust lubricating oils with a viscosity of 46-100, possessing good heat resistance, oxidation resistance, demulsification resistance, and rust prevention. Some also require No. 2 or No. 3 composite calcium-based, sodium-based, or lithium-based greases with good heat resistance and mechanical stability, and even molybdenum disulfide or graphite greases. Bearings and gears in pulp cooking equipment operate at high temperatures and are often lubricated with industrial gear oils or greases. In summary, the lubricated components of pulp machinery include bearings, worm gears, reducers, closed and open gears, and types previously discussed include L-HL hydraulic oil, L-CkC industrial gear oil; calcium-based grease, composite calcium-based grease, general-purpose lithium-based grease, graphite calcium-based grease, and semi-fluid lithium-based grease, etc.
2. Lubrication of the papermaking machine
In principle, all lubrication points in a paper machine are sealed. Each bearing in the wet section of the paper machine has a sealed bearing housing to prevent water intrusion and cross-contamination caused by grease overflow. Due to the higher operating temperatures in the dry section, a central lubrication station uses pressure to deliver lubricating oil to all bearings for lubrication and heat dissipation. In summary, the lubrication components of a paper machine include the transmission gearbox, worm gearbox, general sliding bearings, rolling bearings, exhaust fans, wet section rolling bearings, wire ropes, and the oil used in the central lubrication station (dry section lubrication). Types of oils and greases previously discussed include hydraulic oil, total loss system oil, calcium-based grease, sodium-based grease, and graphite-calcium-based grease.
3. Lubrication of papermaking machines and their auxiliary equipment
(1) Oil for sectional transmission gearboxes, central lubrication station (dry section lubrication), vibrating gearboxes, worm gear reducers, and general sliding bearings:
All are lubricated with hydraulic oil or total loss system oil, using L-HL46 or L-AN46. The viscosity of the oil at 40℃ is 41.4～50.6mm2/s, flash point (open cup) >180℃, and pour point <-10℃.
(2) Rolling bearings in wet sections:
Calcium-based grease, dropping point >80℃, cone penetration (25℃, 1/10mm) 265～295.
(3) Exhaust fans and rolling bearings in humid and hot places: sodium-based grease, dropping point > 40℃, cone penetration (25℃, 1/10mm) 220～250.
(4) Steel wire rope:
Graphite calcium-based grease, ZG-S, dropping point >80℃
