JP4412017B2 - Sedimentation tank - Google Patents

Description

  The present invention relates to a settling tank for separating solids in water, and in particular, a settling tank in which water is flowed in the longitudinal direction of a rectangular tank body to perform a solid-liquid separation process. The present invention relates to a sedimentation tank in which a feed chamber is defined by a baffle plate on one end side (upstream end side).

  One end side (front end side) of the rectangular tank body is partitioned by a rectifying plate to form a feed chamber, and an overflow portion is provided on the other end side (rear end side) of the tank body. A sedimentation tank is known in which a solid-liquid separation process based on a difference in specific gravity is performed in a sedimentation chamber.

  In JP-A-10-314506, a sludge pit is provided adjacent to the current plate; a flow rate adjusting member is provided in upper and lower stages in the middle of the tank body in the longitudinal direction, and flows between the upper and lower sides in the tank body. Are equalized respectively. In the publication, a scraper for scraping the sediment at the bottom of the tank body to the sludge pit is arranged to be movable in the longitudinal direction of the tank body, and the flow rate adjusting member is installed in the scraper.

Further, in Japanese Patent Publication No. 11-500056, a sludge pit is provided on the front side of a rectangular tank body, the bottom surface of the tank body is inclined downward from the rear end side toward the sludge pit, and the settled sludge is the sludge. A settling tank is described which flows down to the pit.
JP 10-314506 A Japanese National Patent Publication No. 11-500056

  An object of this invention is to provide the precipitation tank excellent in the solid-liquid separation efficiency.

The sedimentation tank of the present invention is partitioned by a tank body having a rectangular shape in plan view and a rectifying plate extending in the vertical direction and the tank body lateral direction at one end side (front end side) in the longitudinal direction of the tank body. The feed chamber, the overflow portion provided on the other end side (rear end side) in the longitudinal direction of the tank body, and the vertical direction provided in the settling chamber between the rectifying plate and the overflow portion And a baffle plate made of a perforated plate extending in the short direction of the tank body, and a sludge pit provided at the bottom of the settling chamber adjacent to the rectifying plate, and the bottom surface of the settling chamber is in the settling tank from the rear end side is inclined boiled down gradient toward the sludge pit, between the bottom surface of the lower end and settling chamber of the baffle plate, the rear end of the sludge than the baffle plate the than the baffle plate and spaced to flow into the front side of the sludge pit, and on the said baffle plate An upper baffle plate made of a perforated plate hanging from the water surface is provided behind the baffle plate and in front of the overflow portion. A space is provided between the lower end and the bottom surface of the settling chamber .

  The flow rate adjusting member disclosed in JP-A-10-314506 attempts to equalize the flow rate distribution in the vertical direction of the tank body.

  According to the inventor's research, in a sedimentation tank of a type in which the bottom surface of the tank body having a rectangular shape in plan view is inclined downward toward the sludge pit on the front stage side, it flows into the sludge pit along this bottom surface. It has been found that it is preferable not to disturb the sludge flow.

  In addition, in a sedimentation tank of a type in which the feed chamber is partitioned by a baffle plate, the outflow rate of water from the feed chamber to the settling chamber is higher in the lower part of the feed chamber; It has been found that the flow rate in the lower part is larger than that in the upper part; the solid-liquid separation efficiency is improved by suppressing the flow rate in the lower part of the sedimentation chamber.

In the settling tank of the present invention, the flow velocity distribution in the tank is made uniform by the baffle plate, and the sludge flow toward the sludge pit along the tank bottom is smooth. Thereby, the solid-liquid separation efficiency is improved.

In the present invention, further to the rear than the baffle plate is provided with a top baffle plate made of a porous plate in the vicinity of the water surface. Thereby, the flow velocity distribution in the tank is made more uniform, and the solid-liquid separation efficiency is improved.

Hereinafter, reference examples and embodiments will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view in the longitudinal direction of a sedimentation tank according to a reference example .

  The tank body 1 has a rectangular shape in plan view, and a feed chamber 2 is partitioned from the sedimentation chamber 4 by a rectifying plate 3 on a front end side 1f thereof. The rectifying plate 3 is composed of a porous plate or a slit plate in which a large number of openings are uniformly provided, and is erected vertically from the bottom surface of the tank body 1 to the water surface. The current plate 3 extends in the short width direction of the tank body 1. The distance from the current plate 3 to the rear end 1r of the tank body 1 is S.

  A sludge pit 5 is provided at the bottom of the settling chamber 4 adjacent to the current plate 3. The tank bottom surface 6 behind the sludge pit 5 has a downward slope toward the sludge pit 5. This gradient is n. Note that n is defined as n = b / a using the horizontal length a and the height difference b between both ends of the length a as shown in the figure.

  A baffle plate 7 made of a perforated plate is provided in the vicinity of the middle of the tank body in the longitudinal direction behind the sludge pit 5. The baffle plate 7 extends in the up-down direction and the short width direction of the tank body 1. The opening ratio of the baffle plate 7 is preferably 20 to 40%, particularly 25 to 30%. Between the lower end of the baffle plate 7 and the bottom surface of the tank body 1, there is an interval of C. The baffle plate 7 has a height H at which the upper end is submerged in water. The baffle plate 7 and the rear end 1r of the tank body 1 are separated by a distance L.

  An overflow portion 8 is provided on the rear end 1 r side of the tank body 1. The depth of the tank body 1 at the rear end 1r is D.

In this reference example , the front and rear and vertical positions of the baffle plate 7 are as follows.
0.4S ≦ L ≦ 0.7S, preferably 0.4S ≦ L ≦ 0.66S
0.9 L · n ≦ C ≦ 1.1 L · n, preferably 0.95 L · n ≦ C ≦ 1.05 L · n
0.3D ≦ H ≦ 0.6D, preferably 0.35D ≦ H ≦ 0.5D

  In the sedimentation tank configured as described above, raw water is supplied to the feed chamber 2, passes through the current plate 3, flows in the sedimentation chamber 4 toward the rear end 1 r in the horizontal direction, and during this time, solid-liquid separation is performed. Done. The sediment flows into the sludge pit 5 along the inclined bottom surface 6 and is discharged from a discharge port (not shown) at the bottom of the sludge pit 5.

In this reference example , since the raw water flowing into the feed chamber 2 contains a large amount of untreated solids, the density of the mixed solution is larger than that of the semi-treated water present in the settling chamber 4, so Raw water flows out into the chamber 4 so that the lower the feed chamber 2 is, the baffle plate 7 made of a porous plate is provided in the middle of the settling chamber 4 in the longitudinal direction or slightly forward of the longitudinal direction. The baffle plate 7 suppresses the flow velocity in the lower portion of the settling chamber 4, and the horizontal flow velocity is substantially uniform from the upper portion to the lower portion of the settling chamber 4. Thereby, solid-liquid separation efficiency improves. The baffle plate 7 has a height H of 0.3 D to 0.6 D, and is approximately 0.5 D to 0.8 D between the upper end of the baffle plate 7 and the settling chamber water surface. There is an interval, and the horizontal flow at the top of the sedimentation chamber is not affected by the baffle plate 7.

Since the baffle plate 7 is at the midpoint of the settling chamber length S or slightly in front of it (that is, L is 40 to 70% of S), there is a sufficient settling space behind the baffle plate 7 and solid Liquid separation is sufficiently performed.

Further, in this reference example, there is a gap C between the baffle plate 7 and the tank bottom surface 6 ( C is 90 to 110% of L · n ), so the baffle plate against the sludge flow along the bottom surface 6. 7 does not become an obstacle, and the sludge flows smoothly into the sludge pit 5. The sludge accumulation thickness on the bottom surface 6 increases as it approaches the sludge pit 5, but in this reference example , the interval C increases in proportion to L so that the sludge flows smoothly toward the sludge pit 5. Become.

Figure 2 shows the settling tank according to implementation of the embodiment of the present invention. The sedimentation tank of FIG. 2 is obtained by providing an upper baffle plate 9 behind the baffle plate 7 in the sedimentation tank of FIG. 1, and the other configuration is the same as that of the sedimentation tank of FIG. The upper baffle plate 9 is made of a perforated plate and extends in the short width direction of the tank body 1.

  The upper baffle plate 9 is positioned such that the distance R is 0.3S to 0.6S, preferably 0.35S to 0.5S from the rear end 1r of the tank body 1. The height T of the upper baffle plate 9 is 0.2D to 0.4D, preferably 0.25D to 0.33D.

  The aperture ratio of the porous plate constituting the upper baffle plate 9 is preferably 20 to 40%, particularly preferably 25 to 30%. By providing the upper baffle plate 9 in this way, the flow of water in the upper part of the settling chamber 4 is suppressed by the upper baffle plate 9, so that the water short-circuits the upper part of the settling chamber to the overflow part 8. It is prevented from flowing. As a result, the solid-liquid separation efficiency is further improved.

  In the above embodiment, both the baffle plate 7 and the upper baffle plate 9 are arranged vertically, but are slightly inclined in the front-rear direction (preferably within a range of 30 ° from the vertical, for example, about 10 to 30 °). May be. As for the direction of inclination, the front side of the baffle plate 7 is suitable, and the rear side of the upper baffle plate 9 is suitable.

It is a longitudinal cross-sectional view of the longitudinal direction of the sedimentation tank which concerns on a reference example . It is a longitudinal cross-sectional view of the longitudinal direction of the sedimentation tank which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tank body 2 Feed chamber 3 Current plate 4 Settling chamber 5 Sludge pit 6 Bottom surface 7 Baffle plate 8 Overflow part 9 Upper baffle plate

Claims (1)

A tank body having a rectangular shape in plan view;
A feed chamber that is partitioned and formed on one end side (front end side) in the longitudinal direction of the tank body by a current plate extending in the vertical direction and the tank body short direction;
An overflow portion provided on the other end side (rear end side) in the longitudinal direction of the tank body;
A baffle plate made of a perforated plate provided in the settling chamber between the flow straightening plate and the overflow portion and extending in the vertical direction and the tank body short direction;
A sludge pit provided at the bottom of the settling chamber adjacent to the current plate;
Comprising a bottom surface of該沈Fushitsu, in settling tank from the rear end side is inclined boiled down gradient toward the sludge pit,
There is an interval between the lower end of the baffle plate and the bottom surface of the settling chamber so that sludge on the rear end side of the baffle plate flows into the sludge pit on the front end side of the baffle plate , and the baffle There is a gap between the top edge of the plate and the water surface,
An upper baffle plate made of a porous plate that hangs down from the water surface is provided behind the baffle plate and in front of the overflow portion, and there is a gap between the lower end of the upper baffle plate and the bottom surface of the settling chamber. sedimentation tank, characterized in that vacant.

Images