JPH031109Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention further separates the solids from the liquid separated by a centrifugal separator to improve the clarity of the liquid. The present invention relates to a separation device that is capable of increasing the recovery rate of a solid component by removing air bubbles from the liquid component and improving the recovery rate of the solid component.

[Conventional technology]

Referring to Figure 4, a screw decanter type centrifugal separator is an example of a centrifugal separator that has been conventionally used to separate liquid and solids from a mixture of liquids and solids. An inner shell b is provided inside the shell a, a screw c is attached to the outside of the inner shell b, and an inner shell supply chamber d is provided inside the inner shell b. and outer body a
Both the inner cylinder b and the inner cylinder b are adapted to be rotated at high speed.

Slurry to be treated, such as sewage wastewater sludge, which is a mixture of liquid and solid components, is sent from the storage tank e to the feed pipe g by the pump f, and is fed to the inner shell supply chamber d.
supplied to The slurry to be processed supplied to the inner shell supply chamber d enters the outer shell a through the inner shell discharge hole h, where the liquid and solid components are separated. The solids are then sent to the right in FIG. 4 by the screw c and are discharged to the outside from the discharge port i provided in the outer shell a. Further, the liquid is discharged into the casing k from an orifice j formed in the outer shell a.

By the way, the suction of air from the gaps l, m, and n between the outer shell a rotating at high speed, the fixed field pipe g, and the casing k cannot be avoided, and the air sucked from the gap l cannot be avoided. is combined with the slurry to be treated in the inner shell b, compressed by centrifugation in the outer shell a, and is discharged from the orifice j in the form of a separated liquid with bubbles into the casing k. The separated liquid under centrifugal pressure in the outer shell a is discharged from the orifice j at a considerable circumferential speed of about 10 to 50 m/sec into the casing k, which is close to atmospheric pressure. Considerable agitation will occur.

[Problem that the invention attempts to solve]

The separated liquid discharged into the casing k usually does not contain any solids, so the solids in the separated liquid rise to the surface together with the air in the separated liquid in a short period of time. As a result, the recovery rate of solids was poor and the treatment of air bubbles became a problem.

The present invention aims to further separate solids from the liquid separated by a centrifuge to improve the clarity of the liquid, improve the recovery rate of the solids, and remove air bubbles.

[Means for solving problems]

The present invention includes a centrifugal separator that separates liquid and solid components, a flotation tank, and a plurality of partition plates of different heights and spaced apart from the bottom of the flotation tank. , a flow path for introducing the liquid separated by the centrifuge between the peripheral wall of the flotation tank and the high partition plate, and a flow path between the peripheral wall of the flotation tank and the low partition plate. A liquid flow path leading from the lower part to the outside of the flotation tank, a scum tank provided on the outer periphery of the flotation tank to receive overflow from the upper edge of the flotation tank, and a defoaming shower provided above the scum tank. , and discharge passages attached to the bottom of the flotation separation tank and the bottom of the scum tank, respectively.

[Effect]

The liquid separated by the centrifuge is introduced into the flotation tank, and the solids contained in the liquid float up in the flotation tank together with air bubbles and overflow into the scum tank, and the air bubbles are removed from the defoaming shower. The solids are discharged from the bottom of the scum tank to the discharge passage together with the defoaming water, and the liquid from which the solids have been removed is taken out from the liquid flow passage to the outside of the flotation separation tank.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 1 denotes a screw decanter type centrifugal separator, which is the same as the conventional centrifugal separator explained in FIG. A flotation tank 3 is provided below the screw decanter centrifuge 1.

The peripheral wall 4 of the flotation tank 3 has a cylindrical shape as shown in FIG. 3, and is provided with a viewing window 5 as shown in FIG. 2 so that the inside can be seen through the glass. ing. The bottom 6 of the flotation tank 3 is funnel-shaped as shown in FIGS. 1 and 2.

A high-height partition plate 7 and a low-height partition plate 8 are provided in the flotation tank 3, and a gap 9 is provided between the lower ends of these partition plates and the bottom 6 of the flotation tank 3. , 10 (see Figure 2) are opened.
A flow path 11 is provided above between the high partition plate 7 and the peripheral wall 4, and the liquid separated from the slurry to be processed by the screw decanter type centrifugal separator 1 shown in FIG. , the casing 2 , and the flow path 11 , and are introduced between the high-height partition plate 7 and the peripheral wall 4 in the flotation separation tank 3 . A liquid flow path 12 is opened in a low part between the low-height partition plate 8 and the peripheral wall 4 in the flotation tank 3, and this liquid flow path 12 is used to connect liquid outside the flotation tank 3. Tank 1
It is connected to 3.

An annular scum tank 14 is provided at a high position on the outer periphery of the flotation separation tank 3, and above the scum tank 14, a large number of defoaming showers 15 are installed to supply water to the scum tank 14. It is now starting to spray. Discharge passages 17 and 18 are attached to the bottom 16 of the scum tank 14 and the bottom 6 of the flotation tank 3, respectively, and the discharge passages 17 and 18 communicate with a storage tank 19 as shown in FIG. ing. A valve 20 is installed in the middle of one of the discharge passages 18, and a submersible pump 21 is provided in the storage tank 19, the discharge side of which is connected to a pipe 22.

In the above-mentioned apparatus, the liquid separated from the slurry to be treated by the screw decanter type centrifugal separator 1 shown in FIG. introduced in between.
The liquid then passes through the gap 9 between the high partition plate 7 and the bottom 6, flows further over the low partition plate 8, and is discharged from the liquid flow path 12 through the liquid tank 13 to the outside. Compared to the flow rate of this liquid, the volume between the high-height partition plate 7 and the low-height partition plate 8 in the flotation tank 3 is made to be extremely large. Between the high partition plate 7 and the low partition plate 8, the upward flow rate of the liquid component is made to be extremely slow. Therefore, the unrecovered solids in the liquid are captured by the large amount of air bubbles contained in the liquid, and together with the air bubbles, the unrecovered solids are transferred to the flotation tank.
Separate by flotation.

The scum floated and separated in the flotation tank 3 in this way overflows from the upper edge of the flotation tank 3,
The scum is stored in the scum tank 14. In the scum tank 14,
Water is injected from a defoaming shower 15 to defoam whenever necessary, and the solid content and defoaming water are stored in a storage tank 19 through a discharge passage 17. On the other hand, the solids that have settled on the bottom 6 of the flotation tank 3 are removed from the discharge passage 18 as necessary.
It is stored in the storage tank 19 through the valve 20. The solids and defoamed water thus stored in the storage tank 19 are returned to a storage tank for the slurry to be treated (not shown) via the submersible pump 21 and the pipe 22.

Since the flotation speed of the fine solids remaining in the liquid without being separated by the screw decanter centrifuge 1 is generally 20 to 40 cm/sec, a high partition plate in the flotation tank 3 is used. It is desirable to determine the size of the horizontal cross-sectional area of the flotation tank 3 so that the flow velocity between the flotation tank 7 and the low-height partition plate 8 is less than this.

[Effect of idea]

The present invention has the following effects.

(i) Since the clarity of the liquid component is increased, post-processing of the separated liquid becomes easier.

(ii) Since the foam is extinguished by the anti-foaming shower, it becomes easier to dispose of the foam, and since there are no bubbles in the separated liquid, troubles such as clogging of the piping for discharging the separated liquid are eliminated, and the piping can be made smaller. can.

(iii) The solids that floated up with the bubbles are easily disposed of afterward since the bubbles are eliminated.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a cross-sectional view of Fig. 3 showing the main parts of the invention, Fig. 3 is a plan view of Fig. 2, and Fig. 4 is a sectional view of an embodiment of the present invention. FIG. 2 is a sectional view of a conventional device. In the figure, 1 is a screw decanter type centrifuge;
3 is a flotation separation tank, 4 is a peripheral wall, 6, 16 is a bottom, 7
8 is a high-height partition plate, 8 is a low-height partition plate,
9 and 10 are intervals, 11 is a flow path, 12 is a liquid flow path, 1
4 is a scum tank, 15 is an antifoaming shower, 17, 18
indicates the discharge passage.

Claims (1)

[Scope of utility model registration request] A centrifugal separator that separates a liquid component and a solid component, a flotation tank, and a plurality of partition plates provided in the flotation tank and having different heights and having intervals between them and the bottom of the flotation tank; A flow path for introducing the liquid separated by the centrifuge between the peripheral wall of the flotation tank and a high partition plate, and between the peripheral wall of the flotation tank and the low partition plate. a liquid flow path leading from the bottom of the flotation tank to the outside of the flotation tank; a scum tank provided on the outer periphery of the flotation tank to receive overflow from the upper edge of the flotation tank; and a defoaming tank provided above the scum tank. A separation device characterized by comprising a shower and discharge passages respectively attached to the bottom of the flotation tank and the bottom of the scum tank.