Keeping these under control will make the paper machine run better!

Of course, there are many factors for the high-speed operation of the paper machine, but they are all technical and management details and the lack of understanding and use of equipment. The "constraints" can be summarized in the following areas:


Paper is beaten by a pulp beater, that is, pulping is very important, the quality of pulping determines the quality of paper, and pulping is the basic skill. However, the paper machine speed in that period was low, and it did not pay much attention to speed and efficiency, focusing on the main quality indicators of paper.

Now the pulping equipment is advanced, the control level is high, and it is easier to beat the pulping well. Now the quality is more important, and cleaning should be the basic skill of papermaking.

The cleaning mentioned here is in a broad sense, not only the workshop environment, but more importantly, the slurry system (especially the paper machine sizing system), the equipment of the auxiliary material system and the inner wall of the pipeline, the wet part of the frame, rollers, blankets and other parts, are not allowed to accumulate dirt and scale. Of course, the drying part and other non-wet parts are also the same, paper wool and paper pieces are not allowed to fly, and paper dust and oil are accumulated on the surface of the dry net and dryer.

Any flocculation in the wet end (fibers, filler, foreign matter, dry pulp, etc.) can cause paper defects such as holes or broken paper in different parts. It is important to reduce or remove the accumulation of slurry and flocculates in a timely manner. All surfaces in continuous contact with the slurry must be smooth and regular cleaning is necessary.


The ratio of slurry, the quality of beating and the concentration of slurry should be stable. Only a stable slurry can keep the process parameters of the paper machine stable (such as the vacuum degree of the screen part, the dryness of the outlet part, the wet strength of the outlet press part, the speed difference and tension of each part, etc.), and the paper machine can operate stably. The sizing pressure should be stable. The stability of the sizing pressure determines the stability of the spraying pressure of the headbox, that is, the stability of the speed ratio of the pulp network.

The size of the pulp network speed ratio determines the vertical and horizontal tension (strength) of the paper page, and the large fluctuation of the pulp network speed ratio will cause fluctuations in the dewatering rate of the mesh part, and the fiber forming quality is different; The fluctuation of the uniformity and longitudinal and horizontal tensile forces of the paper will cause the peeling angle of the press part to change; The tightness of the paper web in other parts fluctuates, causing paper defects (folds) or paper breaks.

Generally, the instantaneous fluctuation value of the headbox pressure is required to be within 0.6kPa. The factors affecting the pressure fluctuation are roughly as follows: pressure stability before sizing pump, natural pulse of pump, speed control quality of pump, performance of screen before mesh (pulse size), gas content in slurry and exhaust of screen before mesh.

In the matter of pressure, it is very important to choose a pressure sensor with high accuracy and stable performance, which is the first eye of the paper machine and a very important eye. It plays a key role in the normal operation of the paper machine and the quality of the paper.

The mesh transmission should be stable, and the high-frequency fluctuations of the mesh speed (several times per second) mainly come from the encoder and gearbox gear clearance of the transmission control system. When there is a problem with the encoder, the feedback speed is not accurate and fluctuations occur; When the gear gap of the gear frame is large, speed oscillation is generated, and the speed of the net fluctuates at high frequency, which also causes fluctuations in the speed ratio of the pulp network. This fluctuation, the general instrument can not be displayed, it is difficult to detect, only in the paper machine discharge stage, the process of the gradual thickening of the net pulp layer can be seen, in the paper low-speed rewinding, visible light and dark horizontal print.

The slurry flows from the headbox to the net, and the flow state of the entire dewatering process should be stable

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