Fourdrinier paper machine

Fig. 4. Fourdrinier paper machine A, headbox B, Fourdrinier wet end with foil boxes C, wet and D, dry suction boxes, pickup, and closed transfer of web...

The type of paperboard used by the carton industry is boxboard. Boxboard may be categorized, based on the raw material, as combination or soHd boxboard. Combination boxboard, of which there are many grades, normally is made on a multicylinder paper machine using a substantial percentage of waste paper with virgin pulp. SoHd boxboard usually is made on a Fourdrinier paper machine using only virgin pulp and it is bleached or coated. 

The processed pulp is converted into a paper product via a paper production machine, the most common of which is the Fourdrinier paper machine (see Figure 21.6). In the Fourdrinier system,3 the pulp slurry is deposited on a moving belt (made from polyester forming fabrics) that carries it through the first stages of the process. Water is removed by gravity, vacuum chambers, and vacuum rolls. This waste water is recycled to the slurry deposition step of the process due to its high fiber content. The continuous sheet is then pressed between a series of rollers to remove more water and compress the fibers. 

FIGURE 21.6 Fourdrinier paper machine. (Taken from U.S. EPA, Profile of the Pulp and Paper Industry, 2nd ed., report EPA/310-R-02-002, U.S. EPA, Washington, November 2002.)... 

Once the pulp fibres have been refined to the necessary degree, they are then formed into a sheet of paper on the paper machine. The paper formation process itself is essentially a fast filtration process and involves the delivery of a dilute fibre suspension in water on to a woven endless plastic wire belt, through which it drains to form a wet fibre network. The Fourdrinier paper machine is the most well-established system for forming the wet web, but there are now many variations of this basic principle. A schematic diagram of the Fourdrinier formation process is shown in Figure 5.15. 

The papermaking process is essentially a system whereby the pulp is diluted to a very low consistency (about 0.5%) and continuously formed into a sheet of paper at high speeds, and then the water is removed by filtration, pressing, and drying. The basic units of the fourdrinier paper machine are diagrammed in Fig. 28.14 a picture is shown in Fig. 28.15. 

Fig. 28.16. Dry end of a large Fourdrinier paper machine. (Courtesy of Regis Paper Co.)...

FIGURE 15.12 Principal components of a Fourdrinier paper machine. (From Kirk-Othmer [4], courtesy of Beloit Corporation.)... 

The prepared fibre stock is made into paper (or cardboard) by so-called Fourdrinier paper machines. First, the prepared stock containing approximately 0.2-1.5% of solid material flows via the stock inlet or flow spreader into a pressurised head boXy from which the stock is distributed evenly onto a moving wire. On this moving, endless wire, now made of plastic polymers, the paper sheet is formed by draining away water by gravity and vacuum suction, and by fibre orientation under turbulence, which forms fibre networks. 

Paper stock (or furnish) may consist of a mixture of cellulose, filler (for example clay, titanium dioxide, calcium carbonate), rosin, alum and water brought together in predetermined proportions. The percent of fiber and other furnish materials suspended in the total volume and weight of water is commonly known as consistency . Control of furnish consistency in the stock preparation and papermaking area is a prime prerequisite of paper making. The Fourdrinier paper machine was developed for the specific purpose of converting this paper furnish into a finished reel of paper on a continuous basis. 

Continuous paper machines have undergone extensive mechanical developments since the 1950s, although the principles employed have changed Utde. Cylinder machines stUl are operated and involve multiples of five to seven cylinders they are used to produce heavy multi-ply boards. Fourdriniers are common in the industry and can be used to produce virtually any grade of paper or paperboard. They vary from 1 to 10 meters in width and, including the press and dryer sections, may be more than 200 m long. 

Subsequent to stock preparation and proper dilution, the paper furnish usually is fed to the paper machine through one or more screens or other devices to remove dirt and fiber bundles. It then enters a flow spreader which provides a uniform flowing stream and which is the width of the paper machine. The flow spreader, or manifold, discharges the slurry into a headbox, where fiber flocculation is minimised by microturbulence and where the proper pressure head is provided to cause the slurry to flow at the proper velocity through the slice and onto the moving Fourdrinier wire. 

Paper machine Machine on which paper or paperboard is manufactured. The most common type is the fourdrinier machine using the fourdrinier wire as a felting medium for the fibers. 

The section of the paper machine where the paper is formed is referred to as the wet end. The fourdrinier machine is characterized by a... 

The furnish is fed to the headbox of a paper machine (Fig. 15.12), about the length of a city block. Sufficient additional fresh water (white water) is added to bring the pulp concentration in the headbox down to about 0.5%. White water, the water removed from the fibers as the paper sheet is formed on the machine, is continuously recycled. This low-concentration of pulp in water is necessary to obtain an even distribution of fiber (a smooth formation ) as the sheet is formed. The diluted furnish is fed through an adjustable horizontal slot (the slice) in the headbox onto an endless wire screen (the Fourdrinier wire), which moves rapidly away from the headbox. Direct drain-... 

Fourdrinier The machine most widely used for papermaking. Includes use of plastic fibers to produce plastic papers or nonwoven fabrics. 

Fourdrinier A machine that uses a wire mesh belt to deliver a continuous sheet of raw paper from a slurry of fibers to the calendaring rollers. 

Fourdrinier paper making machine, 1812. (SSPL via Getty Images)... 

The paper machine is the mechanical system used to convert the pulp suspension into a sheet of paper or paperboard. Until recently, the only type of paper machine used was the Fourdrinier design. 

The prepared furnish material for the Fourdrinier paper maehine is stored ahead of the machine in the machine chest (stoek chest). The furnish is agitated continuously to maintain an even blend of furnish materials. Stock consistency in the machine chest is typically 3 to 4%. 

The majority of paper machines worldwide produce graphic paper grades on fourdrinier wire sections or on hybrid formers. These kinds of conventional forming section usually satisfy the quaHty requirements. Their disadvantages are the limitation in machine speed of about 1200 m min and for some paper grades the nonsymmetry in the web z-direction. 

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