JP2011132624A - Method for dewatering scum discharged in papermaking process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for dewatering scum discharged in a papermaking process without using chemicals. <P>SOLUTION: The dewatering method for the scum discharged in the papermaking process removes water from the scum containing water in sludge such as sewage separated from white water used in the papermaking process. The scum is supplied into a bottom-opened concave rotary vessel 12 through a supply pipe extended from below the vessel upward and scattered by keeping a contact with a top plate 121 of the rotating rotor 12 to deposit the sludge on the side face 122 of the rotor 12 while dropping water downward along the side face 122 of the rotor 12 to separate the sludge and the water. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for dewatering scum generated during the treatment of white water used in a paper mill, and more particularly to a method for dewatering scum that is performed without using chemicals.

  In recent years, demands for resource conservation and global environmental conservation have increased, and the recycling rate of waste paper and waste paper has increased. Magazines that have been difficult to deink and remove foreign matter, laminated paper containers, etc. Are also being used as paper stock. To recycle waste paper, waste paper put into the pulper is dissolved by a solution mixed with chemicals in water, and after removing coarse foreign substances from the resulting paper slurry by a cleaner device, the paper is deinked by a flotator. Bleaching is performed, and fine foreign matter is removed by a cleaner. Recycled paper is made from the resulting liquid pulp through a papermaking process.

  By the way, because a large amount of water is used in paper mills, the water used in the papermaking process is circulated and sent back to the pulper. Wastewater treatment is performed after such circulating water (white water) is also used repeatedly. . In this case, for example, a pressure levitation device is used, and fine fibers and sludge (generally referred to as “sludge”) in white water are attached to fine bubbles generated by dissolving air in water at a high pressure to float. The surface sludge that has surfaced is scraped off, and the remaining water is discharged or reused. Since the scraped sludge (referred to as “scum”) contains a lot of water, it is dehydrated, and then incinerated.

Reissue WO2006 / 022188 JP 2003-119680 A JP 2000-153106 A

“Triple Earl Co., Ltd. / Product Information / Centrifuge series”, [online], [Searched on November 20, 2009], Internet <URL: http://www.triple-r.co.jp/products/ ensin / index.html>

  Conventionally, dewatering of the scum using a screw press (see Patent Document 2) or a belt press (see Patent Document 3) has been performed, but fine sludge flows together with moisture from the gap as it is. Therefore, the dehydration process was difficult. Therefore, as described in Patent Document 1, dehydration has been performed in which a scum aggregated by adding a chemical such as a polymer flocculant is squeezed using a belt press or a screw press. However, when such a dehydration process was performed, the cost of chemicals such as a polymer flocculant increased the papermaking cost.

  Accordingly, an object of the present invention is to provide a method for dewatering scum produced in the papermaking process without using chemicals in order to solve such problems.

The dewatering method of the scum produced in the papermaking process according to the present invention is for removing moisture from the scum containing moisture in sludge such as sludge extracted from white water used in the papermaking process, and opened downward. The scum fed into the rotating body of the concave container through the supply pipe extending from the lower side to the upper side of the rotating container is brought into contact with the top plate portion of the rotating body to be blown, and the sludge is attached to the side surface of the rotating body. On the other hand, the sludge and the moisture are separated by dropping the moisture downward along the side surface of the rotating body.
Also, in the method for dewatering a scum produced in the papermaking process according to the present invention, the scum is continuously fed into the rotating body by a predetermined amount, and then the rotating body is rotated for a certain time in a state where the feeding of the scum is stopped. It is preferable to make it.

  Therefore, according to the present invention, the scum fed into the rotating body is blown off by the rotation of the top plate, and the sludge adheres to the side surface of the rotating body by centrifugal force, while moisture falls along the side surface of the rotating body. Since they are separated, the scum can be dehydrated without using any chemicals, and the cost can be reduced accordingly.

It is sectional drawing which showed schematic structure of the centrifugal dehydrator used with the spin-drying | dehydration method of this embodiment. It is the figure which showed the dehydration method of the scum by a centrifugal dehydrator. It is the figure which showed the dehydration method of the scum by a centrifugal dehydrator.

Hereinafter, an embodiment of a method for dewatering a scum produced in a papermaking process according to the present invention will be described with reference to the drawings.
In the paper mill, as described above, the water used in the paper making process (white water) is reused and sent to the pulper. After being used to some extent, the white water that has been used repeatedly is drained and discharged. The In the pressurized levitation device used in the wastewater treatment, air is dissolved in used white water at high pressure, sludge such as sludge adhering to fine bubbles is levitated, and scraped off to obtain scum. .

  Since the scum contains a lot of moisture, chemicals have been used so far, but in this embodiment, a dehydration method that removes moisture from the scum using a centrifugal dehydrator without using the chemicals is adopted. . FIG. 1 is a cross-sectional view showing a schematic configuration of a centrifugal dehydrator used in the present embodiment. In the centrifugal dehydrator 10, a rotating body 12 of a concave container is rotatably supported in a box-shaped main body 11. The rotating body 12 is disposed with its concave shape turned upside down, and the upper part is closed and the lower part is opened. The top plate portion 121 at the upper end is a flat surface, and the cylindrical tube portion 122 has a shape in which the lower end portion 123 is inclined inward.

  The rotating body 12 is connected to a rotating shaft 13 penetrating the main body 11 upward, and is rotatably supported by a bearing 14 via the rotating shaft 13. A V pulley 15 is fixed to the rotary shaft 13 so that the rotation of the motor is transmitted via a V belt (not shown). For example, the rotating body 12 is given a rotational speed of 2500 revolutions per minute. On the other hand, a supply pipe 16 for introducing scum is attached to the lower side of the main body 11. The supply pipe 16 enters horizontally from the side of the main body, is bent at 90 degrees, and rises along the rotation center of the rotating body 12. The distal end of the supply pipe 16 reaches a position close to the top plate portion 121 of the rotating body 12, and the scum that has been sent blows out from the tip and hits the top plate portion 121.

  In the centrifugal dehydrator 10, the scum that hits the top plate part 121 is blown to the cylinder part 122 by rotation, and sludge such as sludge adheres to the cylinder part 122 by centrifugal force, while moisture droops downward. Is flowing. By the way, a receiving tray 17 for receiving moisture separated from the scum is provided under the rotating body 12. The tray 17 is provided with a through hole 171 with a wall standing at the center side end portion thereof, so that accumulated water flows out through a drain pipe 18 formed in the main body 11.

  A sludge scraper 19 that is disposed along the radial direction and is movable in that direction is provided in the rotating body 12. The sludge scraping plate 19 is moved to the right side of the drawing from the rotation center side shown in the drawing by a driving means (not shown) to the right side of the drawing, and scrapes off the sludge adhering to the rotating cylinder portion 122. For this reason, sludge also falls from the rotating body 12 in addition to moisture, but the tray 17 has a shutter structure, and when the sludge is scraped off, the tray 17 is slid and does not rest on the tray 17. . The sludge scraped out by the sludge scraper 19 falls and is collected in a container (not shown).

  Next, a scum dehydration method using the centrifugal dehydrator 10 will be described. FIG. 2 and FIG. 3 are diagrams showing a scum dehydration process by the centrifugal dehydrator 10. The scum obtained by the pressure levitation device is sent to the centrifugal dehydrator 10 through the supply pipe 16. The scum that rises from the supply pipe 16 and blows out from the tip of the supply pipe 16 hits the top plate portion 121 of the rotating rotating body 12 and is blown to the cylindrical portion 122. Therefore, as shown in FIG. 2, sludge S such as sludge adheres to the cylindrical portion 122 by centrifugal force, while moisture W hangs down from the tip of the lower end portion 123 and falls to the tray 17 and is drained through the drain pipe 18. .

  When the scum is sent to the centrifugal dehydrator 10 in this way, the sludge and moisture are separated, and a deposit layer of sludge S adhering to the inner surface of the cylindrical portion 122 of the rotating body 12 is formed. Then, after the scum is fed for a predetermined time, the supply of the scum from the supply pipe 16 is once stopped, and then the rotation of the scum is continued for a certain period of time. The remaining water W is dropped to increase the dehydration effect.

  After that, the sludge scraper 19 moves in the radial direction of the arrow as shown in FIG. 3 while the rotation of the rotating body 12 is continued. When the sludge scraping plate 19 reaches the sludge S adhering to the inner surface of the cylindrical portion 122, the sludge S that has hit the sludge scraping plate 19 is scraped off, and the container prepared below through the recovery hole 11a of the main body 11 To be recovered. After the sludge S is scraped off, the scum is sent again from the supply pipe 16, and a dehydration process is performed in which the sludge and moisture are separated by such repetition.

  Therefore, according to the scum dehydration method in the present embodiment, by using the centrifugal dehydrator 10, it is possible to dehydrate the scum without using chemicals, thereby reducing the cost. It became possible. Further, the sludge S that has been subjected to the dehydration process becomes easy to handle for transportation and the like, and can be reused as it is as a raw material for boiler fuel or cement.

  As mentioned above, although the dehydration method of the scum produced in the papermaking process according to the present embodiment has been described, the present invention is not limited to this and can be changed without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 10 Centrifugal dehydrator 11 Main body 12 Rotating body 13 Rotating shaft 16 Supply pipe 17 Receptacle 19 Sludge scraper 121 Top plate part 122 Cylinder part

Claims (2)

In the dewatering method of scum produced in the papermaking process to remove moisture from the scum containing moisture in sludge such as sludge taken out from the white water used in the papermaking process,
The scum fed through a supply pipe extending upward from below into the rotating body of the concave container opened downward is brought into contact with the top plate portion of the rotating rotating body, and sludge is removed from the rotating body. A method for dewatering scum produced in a papermaking process, wherein the sludge is separated from moisture by dropping water along the side surface of the rotating body while adhering to the side surface of the rotating body. In the method for dewatering scum produced in the papermaking process according to claim 1,
The dewatering of the scum generated in the papermaking process, wherein the scum is continuously fed into the rotating body after a predetermined amount and then the rotating body is rotated for a certain time in a state where the feeding of the scum is stopped. Method.

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