Basic functions and requirements of pulp equipment

Pulp equipment (or refining equipment) is to make the fibrous raw materials to be processed displace the primary and secondary walls of the fibers that are moving relative to each other, and then rupture, and then the fibers absorb water and swell and are cut, and finally fine fibers Change, that is, the splitting, raising and so on of the surface of the fiber. As a result of beating making the fibers finely fibrillated, the fibers have good softness and plasticity, which are not only easy to be closely intertwined with each other on the paper machine network, but also the specific surface and free surface of the fibers are increased due to the mechanical action of the beating. After squeezing more hydroxyl groups, the bonding force of the fibers is greatly enhanced due to the effect of hydrogen bonds during drying, making them more solidly bonded, and improving the strength of the paper.

Therefore, the function of pulp equipment is to make the fibers have good softness, plasticity and reasonable size after the pulp is beaten, and greatly improve the chance of hydrogen bonding and bonding force between fine fibers. In addition, the beating equipment can evenly mix various raw materials, auxiliary materials, and additives.

The most commonly used method of beating (refining) is to use the hydraulic compaction of metal teeth.

First, the fiber bundle is guided to the edge of the tooth. In this fiber introduction stage, the concentration is generally 3%-5% (sometimes 2%-6%), and the fiber bundle contains more water.

When the edge of the rotor teeth approaches the stator teeth, the fiber bundle is compressed and gets a strong impact. The fruit is that most of the water in the fiber is squeezed out. From time to time, for weakly bonded short fibers, the peeled surface flows into the interdental groove; for the slurry that is still fiber bundles, the fiber bundles are pressed by the edges of the molars and milled. Immediately afterwards, the edges of the molars both slide along the fiber bundles and squeeze the fibers against the surface of the molars. In low-concentration refining, the average molar gap is 100um, which is equivalent to the width of 2-5 thick fibers or 10-20 crushed fibers.

Most of the beating is done at the stage of molar edge to molar surface. At this time, the molar edge is mechanically treated, and the friction between the dimensions produces fiber-to-fiber treatment inside the fiber bundle. This stage continues until the edge of the dominant molar reaches the trailing edge of the passive molar. After that, the fiber bundle continues to be crushed between the surfaces of the two molars until the end of the molars is rotated and moved out of the edge of the stator. When the rotor molar rotates over the stator molar, a strong vortex is generated in the tip of the interdental groove; this vortex makes the fibers easy to be pulled by the edge of the molar. If the grooves are too narrow, the fibers or fiber bundles cannot be turned over in the grooves and cannot hang on the surface of the molars, so no refining can be obtained.

Beating plays an important role in paper production, so the basic requirements for pulp equipment are:

1. The state of refining is good, and the fiber shape of the pulp meets the requirements of paper bonding after mechanical finishing.

2. Grinding teeth and tooth groove shapes vary with the different requirements of the beating process, and the grinding teeth can be adjusted intermittently.

3. The grinding mechanism and the grinding chamber are wear-resistant.

4. The structure of the refining mechanism and the refining chamber are symmetrical, which is advantageous for the uniformity of the force under high-speed operation and ensures the stability of the mechanism.

5. Energy saving, low consumption, small size, simple structure, easy maintenance and operation.