The development of the dryer section of the paper machine

The development of the dryer section of the paper machine:

1. Single dry blanket drying device of paper machine

The drying section of a traditional multi-cylinder paper machine is equipped with two upper and lower drying cylinders with double blankets. In order to effectively exhaust the moist air in the drying section and obtain good ventilation effect, a dry blanket with high air permeability should be used. However, this kind of high air permeability dry blanket can effectively exhaust the moist air while also bringing the strong airflow into the bag area, which causes the problem of paper jitter in the production of low-quantity high-speed paper machines, that is, the paper sheets in the upper and lower cylinders without supporting sections. Fluctuations and flapping occur, wrinkles and paper breaks occur at the edges of the paper. The wet paper at the wet end of the drying section is very fragile and easy to break. The higher the speed, the more severe the jitter, and the easier it is to break. A more effective way to solve this problem is to use a single dry blanket configuration. As shown in Figure 6-2, the lower dry blanket is cancelled, and the upper dry blanket takes paper sheets around the upper and lower drying cylinders. Therefore, in the traction part between the upper and lower drying cylinders, the dry blanket also supports the paper sheet, and the paper sheet is not affected by the traction force, thereby reducing the shaking, wrinkling and breaking of the paper sheet. At the same time, air pockets are eliminated, the moisture in the horizontal direction of the paper is even, the drying cylinder can be approached without the need for the blanket roll; the paper is dried without traction, avoiding the longitudinal stretching and the horizontal when being dried by the traction. Excessive shrinkage can improve the quality of the finished paper.

2. Paper machine single-row dryer drying device (SymRun drying)

The above-mentioned single-dry blanket drying device can effectively control the shaking of the paper sheet and reduce the breakage for the medium and low speed paper machine with a vehicle speed of 500m/min or less. However, when the vehicle speed is further increased, its effect is greatly reduced, and the lower row of dryers has little effect on drying, resulting in a SymRun drying device with a single row of dryers and a single blanket configuration.

3. Paper machine opti drying device

The main shortcoming of the single-row drying cylinder drying device is that the drying device is longer. In order to overcome this shortcoming, many R&D workers began to develop a new and reliable drying method many years ago. The main purpose is to improve the drying unit. Length of drying efficiency, running stability and obtaining excellent paper quality. The Opti drying device is a new type of drying device that integrates excellent operational stability, maximum drying capacity and best paper quality. At the same time, the length of the drying section is about 25% shorter than that of a single-row dryer.

4. Opti drying device with pre-drying device for paper machine

In Opticoncept's entire technology, the opti drying device with pre-drying device is an ideal drying form. The goal of Opti drying with pre-drying is to significantly improve the control and running performance of the paper, especially at the beginning of the dryer section. The Opti drying device with pre-drying is an efficient drying method following OptiPress. The paper web is transferred from the press section to the pre-drying section through a fully enclosed dry blanket. Therefore, when the paper enters the first drying cylinder of the drying section , It has obtained a higher temperature and dryness, which greatly improves the running performance of the paper web in the first drying cylinder of the drying section, which is a key part, and also obtains a higher drying capacity.

5. Condebelt drying device for paper machine

The double-steel belt drying device is currently mainly suitable for the drying of cardboard. The vehicle speed can reach 850m/min and the cutting width can reach 4.6m. According to reports, the double-steel belt drying technology not only has high drying efficiency, saves raw materials, and has great potential for heat recovery, but also can be significant Improve the quality of cardboard. This is mainly because it can increase the tightness of the cardboard by 10%-40%, thereby greatly increasing the bonding force between the fibers and increasing the strength; if the strength is maintained, the basis weight can be reduced by 20%-30%, which saves a lot of fiber raw materials. Can use waste paper pulp to produce box board and kraft box board equivalent to virgin fiber pulp.