Pulp and Paper

Due to the special properties of paper, vacuum and compressed air are essential features in paper manufacturing and processing. In every stage of the production process of paper and the subsequent printing Gardner Denver products excel and provide energy-efficient and reliable vacuum and pressure.

Compressed Air Applications

As paper mills have many moving and printing processes, they are renowned for using large volumes of compressed air. Compair’s Quantima compressors have been used in paper mills to efficiently supply the volumes required. Smaller oil lubricated and oil free compressors are also used for applications such as material handling or printing where air operated pumps are used.

  • Air bearings for product handling – air bearings or air castors enable heavy products to be easily handled by literally floating heavy loads on a virtually frictionless film of air
  • Vacuum generation – using compressed air and a venturi systems vacuum is generated very efficiently. Vacuum is used for many processes such as product handling.
  • Paper pressing – compressed air is used via cylinders for a variety of pressing applications
  • Printing – compressed air used for operation of printing pumps and equipment. As air is non explosive, it is safe and reliable
  • Roller adjustment – compressed air is used to precisely control the roller thickness which determines the paper thickness, essential for an efficient process

Headbox Compressor / Vacuum Pump

Used in "airpadded" headboxes, headbox compressor/vacuum pumps create a pressure/vacuum above the stock level (or "pond" level) in the headbox to ultimately control the velocity by which the stock exits the headbox ("jet" velocity) onto the moving wire. Liquid ring pumps are usually configured to operate as both vacuum pumps and compressors through a series of valves. They either create a vacuum or a pressure in the void volume above the pond level to control the static head in the headbox.

Inkjet Printing

Ink jet printing is widely used in the industrial coding, marking, and labelling markets. In this procedure 64,000 droplets per second are formed. The droplets needed for marking get electrostatically charged and fly directly onto the media, while the uncharged drops are deflected into a gutter for recirculation. Thomas liquid pumps transport the ink from the collection area back into the storage tank.

Paper Machine Forming Section (Dewatering)

Nash vacuum pumps are used throughout the forming section of a paper machine to remove water from the paper stock. In the forming section, varying levels of vacuum are applied applied across the flat boxes and couch rolls to remove the bulk of the water.

Paper Machine Press Section Vacuum

Suction pickup and transfer rolls – The suction pickup and transfer rolls use vacuum to transfer the paper from the forming section to the press section and guide the sheet from one felt to another in the press section.

Pre-Press, Press and Post-Press

Vacuum is required for a variety of applications in the pre-press area, including preparing images and film for scanning or exposure and for copying printing plates. There are also many applications where over-pressure is needed as well, such as for guiding plates or film in automatic systems.

In classic sheet fed offset presses, vacuum and overpressure is always needed for paper handling – at the feeder to separate the sheets, to feed the single sheets to the different colour-aggregates or to guide the sheets through the machine. All these applications need different amounts of air at different pressures. There are a variety of applications in the post-press arena. For example, side channel blowers for folding and cutting machines; pressure-vacuum pumps and individual vacuum pumps and compressors for collating and book binding machines; and radial blowers for removing waste paper.

Suction Press

The suction press uses mechanical action to extract the water from the paper sheet. In the press section, large granite or hard rubber covered rolls are placed in close contact to form a "nip". As the paper passes through the nips, the water is pressed out of the sheet into press felts that transport and cushion the sheet on its journey through the press section. Presses can have suction or non-suction rolls to aid in the water removal process.

Vacuum Filtration (Pulp and Paper Stock)

Used on brown stock washers, lime and mud precoat filters, dregs filters and deckers, liquid ring pumps pull a vacuum on the interior of a rotating drum filter, removing proportionate amounts of liquid from the pulp, paper stock or other filtrate.