Paper machine speed is good, measures are indispensable

Paper machine speed is good, measures are indispensable

A paper machine wants to run at high speed, without these features in the dryer section!

The increase in the speed of the paper machine means that the paper web must be dried quickly in the dryer section, which implicitly puts forward higher requirements for the dryer section of the paper machine.

Compared with the drying section of the old paper machine, the drying section of the modern high-speed paper machine has made a lot of improvements in terms of technology and equipment, but no matter what improvements are made, the press section generally must meet the following performance requirements.

stable operation

After the wet paper leaves the press section, it is stably adsorbed to the drying wire, and the paper web is safely and reliably transferred through the combination of the paper web stabilizer and the vacuum roll in the entire drying section, which greatly reduces the damage of the paper web in the drying section. End breakage caused by instability, fluttering, and folding, thus improving the running performance of the paper machine.

High evaporation rate

Due to the equipment characteristics of the drying section, the wet paper sheet can effectively obtain heat from the surface of the dryer, and remove or dissipate the water vapor evaporated from the paper sheet, and in this process, the energy is well controlled.

Control paper shrinkage

At the initial stage of paper web drying, due to the increase of the temperature of the paper web, the strength of the wet paper sheet decreases, and the elongation of the paper web increases. When the paper web is stretched, it will elongate in the longitudinal direction and shrink in the transverse direction.

In modern high-speed paper machines, however, web stabilizers reduce the force required to peel the web from the dryer surface, thereby reducing the longitudinal elongation and transverse shrinkage of the web.

Due to the short dryer group, the elongation of the paper web in the wet end can be compensated by adjusting the speed difference, thus preventing the paper sheet from running into folds.

The paper web is closely attached to the dryer wire in the entire dryer section, which also prevents the shrinkage and deformation of the paper sheet, but the stress on the paper web caused by this will cause the paper web to tear, resulting in end breaks, affecting the normal production of the paper machine. .

The solution is to moderate the shrinkage of the web by adjusting the speed difference between the dryer groups.

Prevent paper from curling

A single-side-dried web is prone to curl, which is caused by uneven distribution of moisture between the front and back sides of the web in the dryer section, with the web curling toward the side that is last dried.

This problem can be controlled by adjusting the moisture distribution on both sides of the web, which can be dealt with either pre-drying or later in the process.

Of course, if you want to increase the speed, it is obviously not enough to improve the press section.

As a system, the paper machine must be rationally optimized in all aspects in order to give full play to the best performance of the paper machine.