Fourdrinier

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...

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. 

Another development is the Inverform process and its more modem version, the Bel Bond (Fig. 8). In the Inverform unit, several pHes are formed on top of each other by consecutive, twin-wke forming units above a long carrying fabric. The Inverform process also is used for the forming of paper grades and is capable of moderately high speeds. Other versions of board machines involve mini-Fourdriniers and/or twin wkes which are placed on top of a carrying fabric. 

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. 

Fiberboard or hardboard is made of low grade wood and wood waste. In the wet production process, a sheet is produced on a papermaking machine, such as a fourdrinier. A Hquid resole is usually added to the beater section and precipitated onto the wood fibers by adjusting the pH. The moderately dry felt is further dried and cured in an off-line press. 

Langsieb, n. (Paper) endless wire, Fourdrinier web. -maschine, /. (Paper) Fourdrinier machine. 

The pulp and paper additives enter the process first through a dump chest in their concentrated form. Adjustments are then made to the concentration in the stock chest just prior to transfer onto the Fourdrinier wire where the paper sheet is produced. Surface additives are sprayed after sheet formation and the final sheet is dried at high temperatures in dryers. The water from the wire is removed into underground tanks and in most cases, recirculated and reused. 

In some situations, if good plant hygiene is not maintained, fungal spores can also become established in and around the Fourdrinier wire. These can develop into large surface colonies which can become dislodged and transfer onto the paper sheet during formation. Again, this can lead to paper sheet failure. 

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. 

Head box Fourdrinier formation table Press section... 

Krause, H. H., Simon, R., and Levy, A. (1973). Smelt-Water Explosions, Final reports to Fourdrinier Kraft Board Institute, Inc. Biittelle Laboratories, Columbus, Ohio. Lemmon, A. W. (1980). Explosions of molten aluminum and water. In Light Metals 1980 (E. McMinn, ed.), p. 817. (Proceedings of Technical Sessions Sponsored by TMS Light Metals Committee at 190tb AIME Armuat Meeting.)... 

Lougher, E. H., Blue, G., Goddard, S., Gurev, H. S., Miller, J. F., Putnam, A. A., and Simon, R. (1968). Feasibility Study on Smelt-Water Explosions, Summary report to Fourdrinier Kraft Board Institute, Inc. Battelle Memorial Institute, Columbus,... 

Only handmade single sheets of paper were fabricated until, in 1798, a machine that could make continuous rolls of paper was invented in France. This machine consisted of a conveyor belt submerged at one end in a vat of suspended cellulose fibers. The conveyor belt was a screen so that water would drain from it as fibers were pulled out of the suspension. The entangled fibers were then squeezed through a series of rollers to create a long continuous sheet of paper. Within a few years, an improved version of this machine that used heated rollers was produced in England. The improved machine was called the Fourdrinier, after a wealthy industrialist who financed its creation. Automated Fourdrinier machines, such as the one shown in Figure 18.2, are still used today. 

What is a Fourdrinier machine, and what was the impact of its invention ... 

An important development in paper forming is the use of a top wire dewatering unit placed above the wire of the Fourdrinier. The top wire units use various dewatering elements such as rolls, foils, and vacuum... 

Fig. 1. Fourdrinier machine for producing printing-grade paper. iBeloit Corporation)...

Although the Fourdrinier machine is used for making almost all grades of paper and board, other designs are sometimes more advantageous. The cylinder machine, invented at about the same time as the Fourdrinier, consists of a rotating cylindrical mold covered with a wire screen and partially submerged in a vat. The stock flows into the vat, and a mat is formed on the cylinder under a hydraulic head difference between the stock level in the vat and the white-water level inside the cylinder. The... 

The slurry is pumped into another stock chest, where wax in emulsion form, usually about 0.5—1.0% wax-to-fiber weight, and 1—3% PF resin are added. PF resin is also added on the basis of resin solids-to-dry fiber. Then a small amount of alum is added, which changes the pH (acidity) of the slurry, causing the resin to precipitate from solution and deposit on the fibers. Resin is required in greater quantity than in the Masonite process because only light bonding occurs between fibers prepared in a refiner. The fiber slurry is then pumped to the headbox of a Fourdrinier mat former, and from this point the process is similar to the Masonite process. 

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 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. 

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... 

Many new methods of forming a sheet of paper are being developed. The most common concept is to introduce the pulp slurry between two converging wires and remove the water from both sides. This is termed twin-wire forming, and many variations are now in operation. This technique has many advantages and may eventually replace the fourdrinier. 

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