Vacuum pumps are key equipment in the papermaking industry, enabling efficient dewatering, ensuring stable operation of paper machines, and contributing to energy saving and environmental protection.
Headbox Compressor & Vacuum Pumps
In equipment equipped with an air-cushioned headbox, vacuum pumps and compressors work together to precisely regulate the air cushion pressure at the top of the headbox. By controlling the air pressure through suction or pressurization, the pulp level and jet velocity are maintained with absolute stability, ensuring that the pulp is ejected onto the forming wire in the optimal and most uniform state. This is a primary prerequisite for achieving excellent paper basis weight and uniformity.
Ozone Compression in Paper Pulp Bleaching
In the ozone (O₃) bleaching process for medium-to-high concentration pulp, vacuum pumps are used to create negative pressure conditions, safely and efficiently drawing and compressing gaseous ozone into the pulp pipeline or mixer. The core of this application is to ensure sufficient contact and reaction between the ozone and the pulp fibers, while preventing ozone leakage into the working environment, thereby guaranteeing bleaching efficiency and operational safety.
Paper Machine Forming Section-Dewatering
This is the core dewatering stage of paper sheet formation. A series of suction boxes (commonly known as “wet suction boxes”) driven by vacuum pumps are arranged sequentially along the wire section, with the vacuum level increasing progressively. Through negative pressure penetrating the forming wire, most of the free water in the paper web is rapidly removed, causing the fibers to deposit, intertwine, and form a paper sheet with a certain wet strength. The dewatering efficiency directly determines the energy consumption and machine speed of subsequent processes.
Paper Machine Press Section Vacuum
In the press section, vacuum pumps primarily serve two key types of equipment: firstly, vacuum press rolls, which perform axial suction simultaneously with mechanical pressing to enhance dewatering and assist in separating the wet paper web from the felt; and secondly, felt vacuum dewatering boxes, used to clean and dewater the circulating felt, maintaining its breathability and dewatering capacity, which is crucial for ensuring the efficient and stable operation of the press section.
Vacuum Filtration
In pulp and paper mill water circulation systems, vacuum pumps are the core power source for various vacuum filters (such as disc filters and belt filters). By generating negative pressure on one side of the filter screen or filter cloth, they achieve efficient separation of solids (fibers, fillers) from liquids in pulp, white water, or black liquor. This is used for pulp thickening, white water recovery, and chemical recovery, and is a key step in achieving resource recycling and wastewater reduction.
Other Papermaking Processes
Vacuum pumps are also widely used in various auxiliary and special processes. For example, they are used in vacuum degassing to remove microbubbles from pulp or coatings to prevent paper defects; in vacuum conveying systems for the enclosed transport of powdered materials (such as calcium carbonate fillers); to ensure the stable transfer of the wet paper web from the forming wire to the press section on vacuum suction rolls; and in equipment maintenance for lifting large paper rolls or rollers using vacuum suction cups.