Production cycle

Description of a typical production cycle

The source material for producing paper is 100% paper waste. The collecting and storage of this waste includes outdoor and indoor facilities. With the help of a tractor, equipped with a hamper, the waste is loaded on two conveyer belts via which it is unloaded into two hydropulpers. Together with the raw material, the hydropulpers are filled with running water to maintain an intensive mixing process. The paper waste disintegrates into fibers and is transformed into a fiber-like suspension. The hydropulpers operate non-stop and they are constantly loaded with raw material to produce and discharge paper mass. The screens at the outlet of the hydropulpers prevent non-processed material to mix with the discharged flow. Further on, the paper mass flows gravitationally into a reception basin from which, with the help of a pump and through a vortical mass cleaning installation, the fiber-like suspension enters a tank located on the 3d floor of the building. The vortical cleaner processes the paper mass on the centrifugal principal cleaning it from impurities with a greater relative weight than that of the fibers. Mostly, these are mineral fractions (sand, glass, ceramics) or metals (paper clips, staples). The paper mass, which is now clean, passes through a turbine separator before gravitationally entering the machining tank. This phase is necessary as the turbine separator eliminates residual impurities which cannot be separated centrifugally and which have a relative weight close to that of the fibers. Such impurities are mostly various types of plastics and they are separated with the help of a very fine sieve. Periodically, the impurities are discharged into a vibration separator and after being washed in process water they are loaded into metal containers.

            With the help of a pump, from the machine tank the paper mass is sent to the suction inlet of the mixer pump at exactly specified rates. This is the main pump in any paper manufacturing process because it feeds the paper-producing machine. The mass, which is of low concentration after having passed vortical cleaning, separation and after being diluted with process water, is sent by the mixer pump to the pressure box of the paper machine. Prior to its entry into the machine the paper mass undergoes another fine cleaning run.

            Form the pressure box, and through the outlet slit, the fiber suspension is poured onto the endless moving wire mesh in a flat parallel flow. Almost instantly, the suspension gets filtered and the surface of the mesh is covered with a fibrous layer. The separated water falls into the tank below the mesh to be brought back to the mixer pump for diluting the incoming new paper mass. From a certain moment on, the dewatering of the paper mat, which is now being formed as a sheet, is done by vacuum boxes, located under the mesh. At the end of this part of the machine the paper sheet is completely formed although still containing lots of water. Its dewatering continues in the machine's presses, which are two, with two rollers exerting an exactly set compression thanks to which more water is squeezed out of the paper sheet.  After the presses, the paper sheet still contains about 55 % moisture, which cannot be eliminated mechanically and so it has to be dried in the paper machine's drier.  This unit consists of two rows of drying cylinders in chess-board order, steam heated. The paper sheet passes over the cylinders in succession and in contact with their hot surfaces. At the end of this process the remaining moisture is in the whereabouts of 6 %. For improved drying, additional ventilation is employed.

            For the consolidating and smoothing of its structure the paper sheet then passes through the machine's calender.  This consists of several metal rollers located vertically one over another with perfectly glossy surfaces and exceptional hardness. It is thanks to their large weight and smooth surface that the paper is consolidated and smoothened.

            Following the calendar the paper sheet enters the finishing section, which is the last in the serious of processes performed by the paper machine. Here the paper is wound onto special spools, called "tambour" and after reaching a set diameter these are replaced with new, empty tambours. The entire operation is executed in motion.

            Finally, the now ready paper will undergo additional processing. It is either wound into reels or cut into sheets of a set size depending on the customer's order. After packaging and weighing it is then transported to the storage facility for ready products.

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