The present invention relates to a screen apparatus, and more particularly, to a screen apparatus capable of improving screen cleaning effect to efficiently reduce clogging of a screen.
In a screen apparatus, a foil is positioned on an inner side of the screen, and a papermaking material is stirred by the foil, so that good fibers in the papermaking material pass through the screen and are separated from foreign materials not passing through the screen (see, for example, Patent Reference Patent Reference 1: Japanese Patent Publication (Kokai) No. 2004-137621
In the screen apparatus described above, when the papermaking material is cleaned, water is discharged from the screen along with fibers with time. Accordingly, a concentration of the papermaking material increases toward a downstream side in a flow of the papermaking material within the screen. For this reason, water is supplied into the screen via a water supply passage to reduce the concentration of the papermaking material, thereby preventing clogging of the screen. However, it is necessary to improve screen cleaning effect.
In view of the problems described above, an object of the present invention is to provide a screen apparatus with improved screen cleaning effect.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to achieve the objects described above, according to a first aspect of the present invention, a screen apparatus comprises a tank for receiving a papermaking material; a screen for dividing the tank into a primary chamber and a secondary chamber; a papermaking material supply passage connected to the primary chamber of the tank for supplying the papermaking material into the tank; a foreign material discharge passage connected to the primary chamber for discharging the papermaking material not passing through the screen and including foreign materials from the tank; a papermaking material discharge passage connected to the secondary chamber for discharging the papermaking material passing through the screen from the tank; a foil disposed in the primary chamber inside the screen for rotating and stirring the papermaking material in the primary chamber; and a dilute water introducing passage for introducing dilute water into the primary chamber. The dilute water introducing passage is tilted at least on a tip end thereof toward a rotational center of the foil in a direction that the foil rotates. The tip opening section faces a side of the foil rotating from a front edge to a rear edge where the dilute water is supplied.
According to a second aspect of the present invention, in the screen apparatus in the first aspect, the dilute water introducing passage has a first passage fastened to the tank so that one end thereof is situated outside the tank, the other end thereof is situated inside the tank, and a mid section thereof penetrates through the tank; and a second passage having one end connected to the other end of the first passage and the other end with a tip opening section facing the side of the foil from the front edge to the rear edge on the side that the dilute water is supplied. The screen is a tubular member having a ring section at a middle portion thereof. The second passage is disposed at the ring section, and the screen disposed in the tank so that an axis thereof extends vertically. The one end of the second passage has a second curved surface formed in an arc-shaped curved surface at a portion of a periphery of the screen. The other end of the first passage has a first curved surface formed in an arc-shaped curved surface contacting the second curved surface.
According to the screen apparatus in the first aspect, at least, the tip end of the dilute water introducing passage is tilted in the rotational direction of the foil toward the rotational center of the foil. Accordingly, the dilute water is introduced in a direction opposite to the rotational direction of the foil, thereby reducing a rotation rate of the papermaking material, so that a difference between the rotation rates of the foil and the papermaking material is increased. As a result in the primary chamber, a pressure at a location near openings of the screen where the foil passes becomes greater than that in the secondary chamber. Accordingly, a reverse flow of the papermaking material passing through the screen increases by an amount corresponding to the difference between the rotation rates of the foil and the papermaking material, thereby improving cleaning effect of the screen and effectively reducing clogging of the screen.
According to the screen apparatus in the second aspect in addition to the effects of the first aspect, the one end of the first passage has the first curved surface formed in the arc-shaped curved surface contacting the second curved surface of the second passage. That is, the first passage and the second passage of the dilute water introducing passage are separated. Accordingly, it is possible to move the screen in a vertical direction, while leaving the first passage as it is. Therefore, it is easy to perform maintenance and replacement of the screen.
Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawings.
In FIGS. 1 to 7, reference A represents a screen apparatus, and the screen apparatus A is configured to continuously remove foreign materials from a papermaking material by, separating fibers from the foreign materials and cleaning a screen 1 by rotating foils 2 disposed inside the screen 1 to oppose one another.
The screen 1 and the foils 2 are disposed within a tank 3 which receives the papermaking material. The tank 3 is divided by the screen 1 into a primary chamber 3A and a secondary chamber 3B. The tank 3 has a supply port 3a to receive the papermaking material; a papermaking material discharge port 3b to discharge the papermaking material passing through the screen 1 from the tank 3; and a foreign material discharge port 3c to discharge the papermaking material not passing through the screen 1 and containing the foreign materials.
Reference numeral 4 represents a papermaking supply passage connected to the primary chamber 3A for supplying the papermaking material to the tank 3. Reference numeral 5 represents a foreign material discharge passage connected to the primary chamber 3A for discharging the papermaking material not passing through the screen 1 and containing the foreign materials from the tank 3. Reference numeral 6 is a papermaking material discharge passage connected to the secondary chamber 3B for discharging the papermaking material passing through the screen 1.
The screen 1 has a tubular shape, and a plurality of openings 11 in a side surface thereof. The openings 11 are, for example, holes, slits (elongated rectangular gaps), or gaps created by bar-shaped longitudinal members that are annularly arranged so as to leave gaps (longitudinal gaps) between the members. The screen 1 is fastened upright in the tank 3 with a ceiling section 12 and a bottom section 13 open.
The foils 2 are disposed in the primary chamber 3A, i.e., inside the screen 1, so as to, rotate freely and stir the papermaking material within the primary chamber 3A. The foils 2 overhang and drop down at plural locations from a ceiling and a side of a disc-shaped member 21 connected to a rotation shaft 31 disposed within the tank 3. The foils 2 are provided at multiple locations. In this embodiment, the foils 2 are provided at four levels four pieces at each level. The foils 2 are disposed at multiple levels, and may be provided at one level and extend out from the ceiling of the disc-shaped member 21 and drop down in elongated shapes (not shown). The foils 2 are rotated by a motor (not shown) via a power transmission member 7 (a belt, for example).
Reference numeral 8 is dilute water introducing passages for introducing dilute water into the primary chamber 3A. A tip side of the dilute water introducing passage 8 is tilted in a direction of the rotation of the foil 2 as it approaches a rotational center 0 of the foil 2. (see
Each of the dilute water introducing passages 8 has a first passage 81 and a second passage 82. The first passage 81 is fixed (welded, for example) to the tank 3, so that one end A of the first passage 81 is situated outside the tank 3, the other end B of the first passage 81 is situated inside the tank 3, and a mid section of the first passage 81 penetrates through the tank 3 (see
One end C of the second passage 82 is connected to the end B of the first passage 81, and the other end D (tip opening section 8A) faces the edge 2A of the foil 2 on the dilute water side which spans from the front edge 2a to the rear edge 2b. The dilute water introducing passages 8 are preferably positioned at, one half of a height H of the screen 1 or lower.
The screen 1 described above is a tubular member and has a ring section R in the middle. The second passages 82 are disposed in the ring section R, and the screen 1 is disposed in the tank 3, so that an axis thereof extends vertically. The end C of the second passage 82 has a second curved surface K2 formed in an arc-shaped curved surface that is a portion of the periphery of the screen 1. The end B of the first passage 81 has a first curved surface K1 formed in an arc-shaped curved surface so as to abut against the second curved surface K2.
The tip sides of the dilute water introducing passages 8 are tilted in the rotational direction of the foil 2 toward the rotational center of the foil 2. Accordingly, the dilute water is introduced in the reverse direction of the rotation of the foil 2 to slow the rotation rate of the papermaking material. As a result, the difference, between the rotation rates of the foil 2 and the papermaking material is increased. This temporarily provides a higher pressure at a location X in the primary chamber 3A (see
The other end B of the first passage 81 has the first curved surface K1 formed in the arc-shaped curved surface so as to abut against the second curved surface K2 of the second passage 82, i.e., the first passage 81 and the second passage 82 of the dilute water introducing passage 8 are separated. Therefore, the screen 1 can be moved in the perpendicular direction, while leaving the first passage 81 as it is, as shown in
In the embodiments described above, the second passages 82 are tilted entirely in the ring section R, and only the side located near the tip opening section 8A may be tilted, as shown in
The disclosure of Japanese Patent Application No. 2004-362758, filed on Dec. 15, 2004, is incorporated in the application.
While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.
Number | Date | Country | Kind |
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2004-362758 | Dec 2004 | JP | national |