Introduction to the use of vacuum pump in papermaking industry
1、vacuum pump in papermaking industry overview
We are both familiar with and unfamiliar with the paper industry. What we are familiar with is that there are many vacuum pumps used in this industry. What we are unfamiliar with is that we do not know which paper mills can use what type of vacuum pump.
2、papermaking process introduction
Paper in society is mainly divided into two categories: domestic paper and industrial paper. Domestic paper mainly refers to toilet paper, while industrial paper mainly refers to corrugated paper and kraft paper.
The domestic high-grade toilet paper machine is mainly imported from abroad. According to the difference of forming mode, there are mainly two types: crescent type and vacuum round net type. Its advantages and disadvantages are as follows:
The most outstanding advantages of crescent toilet paper machine are high speed, large capacity and good paper quality. Generally suitable for large-scale toilet paper factory. According to the quality indexes such as softness and loose thickness of the product, the crescent shaped toilet paper machine, especially the model with double-layer headbox structure, has advantages over the BF paper machine and is more suitable for the production of high-grade tissue paper. However, due to its high speed and high requirements for the ability of the dry and impetuous part at the back, it needs to use a hot air hood (with gas or fuel oil), which consumes a lot of energy, and also because of a single set The production capacity of paper machine is large, and it is not as flexible as BF toilet paper machine in terms of variety transformation; after the new paper machine is put into production, the market sales pressure of products is also relatively large, especially the logistics cost of domestic paper products is high, which is not suitable for long-distance transportation.
Due to the different types of paper produced, the paper machines for industrial paper use different models. However, due to the large output of industrial paper, the required speed is higher.
3、 Use of vacuum pump
In the paper machine, there are many processes using vacuum pump. The most common processes using our equipment are forming and pressing. The vacuum system of the forming part is set for the dehydration and forming of the paper web; the vacuum system of the pressing part provides a vacuum environment for the vacuum suction roller used for the transfer of the paper web and the vacuum pressing roller used for the dehydration of the paper web, as well as the woolen cloth washing and dehydration transfer, and the vacuum degree of the vacuum system of the pressing part is higher than that of the forming part.
After the mixture of air and water from the vacuum system of the paper machine passes through the air-water separator of the front stage, most of the water is discharged from the lower part of the air-water separator, and the air containing a small amount of water is discharged to the air-water separator of the rear stage through the vacuum pump, and the liquid water is discharged into the collection pool and the air is discharged to the atmosphere. In practice, the vacuum system of the forming part and the pressing part generally share one vacuum pump.
Which paper machine can use roots vacuum pump, which paper machine can use water ring vacuum pump?
When the speed of paper-making locomotive exceeds 1000m / min, water ring vacuum pump is needed; when the speed is less than 1000m / min, roots vacuum pump is used more. In the above introduction, the speed of crescent papermaking machine and industrial papermaking machine for toilet paper production are all over 1000m / min, and more liquid water is required to be pumped out in unit time, which requires higher vacuum degree. Generally, the vacuum degree is above – 60kpa, so most of them use water ring vacuum pump; while the speed of circular mesh papermaking machine is about 1000m / min, which is in dehydration In the process, the required vacuum is low, generally below – 40kpa, so most of them use roots vacuum pump.
In the selection of Roots vacuum pump, it is necessary to select wet vacuum pump, not equipped with imported silencer and sealing water pipe, and not use air-cooled oil tank, so as to minimize the field piping. When the vacuum degree is low, we try to recommend roots wet vacuum pump to users. Compared with water ring vacuum pump, it has low energy consumption, stable operation and long service life.