Vacuum filtration is a widely used process in the paper industry. The water ring vacuum pump is mainly used in the coarse pulp washing machine to remove some chemical substances from the pulp. In the filter, it recovers the lime slurry from the clarification process of white water, the precipitate of the particles compounds extracted from the green liquid, and the vacuum dehydration to increase the concentration of raw materials, etc.

Black liquor is the wastewater produced during the papermaking and pulping process. Due to the presence of lignin in the papermaking wastewater, which gives it a dark brown color, it is called black liquor. In paper mills, there are black liquor evaporators that use vacuum evaporation to concentrate the black liquor generated during the paper pulp cleaning process. This makes it easier to recover the chemicals from the furnace for reuse.

Raw materials and white water (wastewater from the papermaking process, named for its white color due to the presence of fine short fibers and other substances added to the pulp) degassing system. The raw materials and white water degassing system is used in the raw material stage. Through a vacuum system, it removes air from the raw materials and the air from the dilution water before the raw materials enter the pulp mixing tank (flowing pulp tank). Failure to remove this air can cause pinholes on the paper, affecting the printing quality and mechanical properties of the paper.

The application of the vacuum pump paired with the suction box and the couch roll: the suction box is a stationary device used for dewatering pulp in the forming section of the paper machine. The suction box is equipped with a vacuum chamber, and there is a separator in between. The vacuum pump generates a vacuum in the vacuum chamber to make dewatering more efficient. The couch roll is the last vacuum point in the forming section, removing some moisture through the action of the vacuum. The dryness of the paper after leaving the couch roll and entering the pressing section will affect the dewatering performance of the pressing section and the steam consumption in the drying section.