JP3483791B2 - Centrifuge with chemical injection means - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention injects chemicals such as a flocculant used for solid-liquid separation of raw sludge in a sewage treatment plant or a sewage treatment plant into the raw sludge efficiently. The present invention relates to a chemical injection device and a centrifuge equipped with the chemical injection device.

[0002]

2. Description of the Related Art FIG. 3 (a) is a schematic front view showing a main part of the structure of a conventional centrifuge in a sectional view.
FIG. 3B is an enlarged view taken along the line AA of the composite pipe in the centrifugal separator shown in FIG. Reference numeral 1 in the figure is a centrifuge. The centrifuge 1 includes a rotatable outer case bowl 2, a main motor (M / M) 3 that gives the outer case bowl 2 rotation about the axis, and the outer case bowl 2 described above.
Inner shell screw 4 arranged coaxially inside, and forward / reverse rotation about the axis of the inner shell screw 4 (directions of arrows B and C)
A back drive motor (B / M) 5 for supplying the sludge, a sludge supply chamber 6 provided in the inner shell screw 4 for receiving the raw sludge, and a sludge supply for supplying the raw sludge into the sludge supply chamber 6. A pipe 7, a chemical injection pipe 8 coaxially arranged on the outer peripheral portion of the sludge supply pipe 7 for injecting a chemical such as a coagulant for facilitating solid-liquid separation with respect to the raw sludge, and the sludge supply chamber 6 Of the sludge supply chamber 6 and a plurality of communication ports 9 for communicating the outer shell bowl 2 with each other. That is, the centrifuge 1 has a chemical injection device equipped with the chemical injection pipe 8 therein.

The outer case bowl 2 is a substantially cylindrical member having a larger diameter on the front side (on the right side in FIG. 3A) than on the rear side (on the left side in FIG. 3). On the inner surface side of the section, a pool 2a for separating and separating the raw sludge is formed. The pool 2a is a separation tank for precipitating and separating raw sludge supplied from the sludge supply chamber 6 through the communication port 9, and utilizes the centrifugal force generated by the rotation of the outer shell bowl 2 to pool 2a. Is moved to the bottom surface of the outer body bowl 2, that is, the inner surface side of the outer body bowl 2, and the supernatant liquid is discharged as a separated liquid from a discharge port 10 provided in front of the outer body bowl 2.

The solid content moved to the bottom side of the pool 2a is dehydrated from the discharge port 11 provided at the rear of the outer case bowl 2 by the screw 4a spirally provided on the outer peripheral surface of the inner case screw 4. It is discharged as a cake.

A large-diameter chemical injection pipe 8 is coaxially arranged and integrated on the outer peripheral portion of the sludge supply pipe 7.
This composite pipe constitutes a double pipe feed pipe. One end (tip) of the composite pipe is inserted into the sludge supply chamber 6, and the other end side sludge supply pipe 7 is connected to a sludge supply pump (not shown) and a sludge storage tank (not shown), The chemical injection pipe 8 is connected to a chemical storage tank (not shown). The supply port 7a of the sludge supply pipe 7 and the injection port 8 of the chemical injection pipe 8 constituting the composite pipe configured as described above
As shown in FIG. 3B, the a is concentric with each other, and the raw sludge and the chemicals are discharged in the substantially axial direction of the pipe.

Reference numeral 12 is a gear box that is interposed between the outer case bowl 2 and the inner case screw 4 and the back drive motor 5 to change the rotating direction and the rotating speed of the inner case screw 4. . When the rotation speed of the outer case bowl 2 is constant, the rotation speed of the inner case screw 4 is changed by the gear box 12 so that the speed difference between the two can be appropriately adjusted.

Next, the operation will be described. When the sludge dewatering process is started, the raw sludge stored in the sludge storage tank (not shown) is supplied to the sludge supply pipe 7 by a supply pump (not shown).
Is supplied to the sludge supply chamber 6 in the inner body screw 4 of the centrifugal separator 1 and the chemicals that agglomerate the raw sludge and the like are coaxial with the sludge supply pipe 7 from a chemical storage tank (not shown). It is discharged toward the raw sludge through the arranged chemical injection pipe 8. The mixture of raw sludge and chemicals is retained in the pool 2a, and is separated into solid content (SS) and water that are aggregated by the chemicals. At this time, the centrifugal force generated by the rotating force of the outer case bowl 2 promotes the sedimentation of the solid content in the mixture. The separated liquid is discharged from the discharge port 10, the solid content is separated and dehydrated, and is discharged from the discharge port 11 as a dehydrated cake.

In such a centrifuge 1, the smaller the rotational speed difference between the outer case bowl 2 and the inner case screw 4, the longer the sludge retention time. Therefore, the water content of the dehydrated cake should be lowered. However, the SS recovery rate deteriorates. On the other hand, the larger the differential speed, the shorter the retention time of the sludge, and the better the SS recovery rate, but the higher the water content of the dehydrated cake.

[0009]

By the way, the performance of such a centrifuge 1 depends on the state of sludge and the amount of chemicals injected, and the cost of chemicals such as coagulant is particularly high.
The current situation is that 70 to 80% of the running cost is occupying a large weight. Therefore, in the sludge treatment technology field, technological development for reducing the chemical injection rate is strongly desired. This chemical cost can be reduced by efficiently mixing (reacting) the raw sludge and the chemical, and further efficiency of mixing is required.

Under these circumstances, when the conventional centrifuge 1 shown in FIGS. 3 (a) and 3 (b) is examined again, as described above, the chemicals are injected into the outer peripheral portion of the sludge supply pipe 7. The pipe 8 is combined and integrated, and the supply port 7a of the sludge supply pipe 7
And the injection port 8a of the chemical injection pipe 8 are concentric with each other.
Therefore, since the chemicals are discharged along the substantially axial direction of the chemical injection pipe 8 similarly to the original sludge, the sludge supply chamber 6 also rotates with the rotation of the inner body screw 4 in the above configuration, and the chance of contact increases. However, there is a problem that the chemical cannot be sufficiently brought into contact with the raw sludge in the sludge supply chamber 6.

4 (a) and 4 (b) show another example of the conventional composite pipe disclosed in, for example, Japanese Patent Laid-Open No. 10-5627, in which FIG. 4 (a) is a front view.
(B) is an AA arrow enlarged view of (a). Contrary to the conventional composite pipe shown in FIGS. 3 (a) and 3 (b), the composite pipe of this example has a small diameter chemical injection pipe 8 coaxially arranged in the sludge supply pipe 7. The direction of release of the chemicals from the raw sludge is substantially along the axial direction of the chemical injection pipe 8 as in the conventional composite pipe. Therefore, also in the case of this composite pipe, similar to the composite pipe shown in FIGS. 3 (a) and 3 (b), there is a problem in that the chemical can be brought into contact with only a part of the raw sludge in the sludge supply chamber 6. there were.

The present invention has been made in order to solve the above problems, and is applicable to the above-mentioned centrifugal separator and is provided with a chemical injection means capable of reducing the chemical injection rate. Aim to get the opportunity.

[0013]

A centrifuge equipped with a chemical injection means according to the present invention comprises a rotatable outer barrel bowl,
An inner barrel screw rotatably disposed coaxially in the outer barrel bowl, a pool formed between the inner barrel screw and the outer barrel bowl, and a pool provided in the inner barrel screw It has a sludge supply chamber, a sludge supply pipe for supplying raw sludge to the sludge supply chamber, a communication port for communicating the sludge supply chamber with the pool, and a chemical injection means for injecting a chemical into the sludge supply chamber. in centrifuge equipped with dosing means, the dosing means includes a chemical injection tube disposed in the sludge supply chamber, provided on the outer circumference of the vicinity of the distal end portion of the drug product filling tube and the sludge supply chamber And a plurality of drug release holes for radially releasing the drug.

Further, the sludge feed pipe may be disposed within the dosing tube.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. 1 (a), 1 (b) and 1 (c) are diagrams showing a configuration of a centrifuge according to Embodiment 1 of the present invention, in which (a) is a front view and (b) is sludge supply. It is a front view which shows the structure of the composite pipe which consists of a pipe and a chemical | medical agent injection pipe, (c) is an AA arrow line view of (b). In addition,
Of the constituent elements in the first embodiment, the same parts as those of the conventional centrifuge or the chemical injection device shown in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted. To do.

The feature of the first embodiment is that the tip of the chemical injection pipe 8 arranged on the outer peripheral portion of the sludge supply pipe 7 is closed, and a plurality of chemical discharge holes 20 are formed in the outer peripheral portion near the front end. Are formed at equal intervals.

The inside diameter of the sludge supply pipe 7 is in the range of about 15 to 80 mm, and the inside diameter of the chemical injection pipe 8 coaxially arranged on the outer periphery of the sludge supply pipe 7 is in the range of about 20 to 100 mm. It is preferable that SUS304, which is excellent in corrosion resistance, be used as the forming material for each of the tubes. Further, the number of the drug discharge holes 20 is in the range of about 2 to 8, and the shape thereof may be circular, rectangular or the like. The diameter of the chemical discharge hole 20 is appropriately determined in consideration of physical properties such as the viscosity of the chemical, the sludge supply amount, the sludge treatment performance of the centrifuge 1, and the like, and is in the range of about 2 to 10 mm. Further, the chemical discharge hole 20 is set within a range of about 5 to 200 mm from the opening end of the sludge supply pipe 7. The dewatering performance of this centrifuge 1 is 0.8 to 100.
m ³ / hour. The sludge concentration of the raw sludge supplied to such a centrifuge 1 is 0.8 to 3.0% (8000 to 30%).
000 mg / L), the concentration of the polymer coagulant as a chemical injected into the raw sludge is usually 0.1 to 0.3%, and the injection amount is 0.04 to ³⁰ m ³ / hour. is there.
The chemical injection rate, which is the injection rate of chemicals to the raw sludge, is 0.
It is 4 to 3.0%. Although the chemical injection pipe 8 is arranged coaxially with the sludge supply pipe 7, both pipes do not necessarily have to be arranged coaxially.

Next, the operation will be described. As shown in FIG. 1 (a), the raw sludge is supplied into the sludge supply chamber 6 via the sludge supply pipe 7, and the chemicals are provided in a plurality of chemical injection pipes 8 provided on the outer peripheral portion of the sludge supply pipe 7. Radially discharged from the chemical discharge holes 20 toward the outside in the radial direction of the chemical injection pipe 8 toward the raw sludge in the sludge supply chamber 6. That is, since the tip of the chemical injection pipe 8 is closed and a plurality of small-diameter chemical discharge holes are provided on the outer peripheral surface instead of the chemical, the chemical is forced at a high pressure rather than being discharged from one place such as the tip. Often,
It is emitted in multiple directions. As a result, the chances of contact of the chemicals with the raw sludge are significantly increased, and the raw sludge and the chemicals are sufficiently mixed, so that solid-liquid separation with respect to the raw sludge is promoted. The supernatant liquid overflows from the pool 2a of the outer body bowl 2 and is efficiently discharged as a separated liquid from the discharge port 10,
The dehydrated cake is discharged from the discharge port 11 by the screw 4a of the inner body screw 4.

By thus providing the chemical injection hole 8 in the chemical injection pipe 8, the chemical is injected into the chemical injection pipe 8.
It discharges in a direction intersecting with the axis line of (in this case, orthogonal) and can diffuse the chemical efficiently to the original sludge, so even if the chemical injection rate is small, the conventional SS recovery rate and water content of dehydrated cake The rate level can be maintained.

Embodiment 2. In the previous embodiment, FIG.
As shown in (b), the structure in which the sludge supply pipe 7 and the chemical injection pipe 8 are combined and integrated is adopted.
Then, the sludge supply pipe 7 and the chemical injection pipe 8 may be separately provided, and both ends may be inserted into the same sludge supply chamber 6. In this case, the inner diameter of the chemical injection pipe 8 is 5
The range is about 50 mm, preferably 10 mm.

Embodiment 3. The chemical injection pipe 8 can be configured to be movable back and forth along the axial direction. By using such a chemical injection pipe 8 that can move back and forth, it becomes possible to inject chemicals evenly into the raw sludge supplied into the sludge supply chamber 6, and to further reduce the chemical injection rate. Can be planned. For moving back and forth, hydraulic pressure, pneumatic pressure, or the like may be used, or an electric type may be adopted. Alternatively, an elastic material may be used to utilize the reaction force of drug release.

Example 1. Solid-liquid separation of raw sludge was performed using the centrifuge 1 having the structure shown in FIGS. 1 (a) to 1 (c).
In the centrifuge 1, the inner diameter of the sludge supply pipe 7 is 20 mm.
And the inner diameter of the chemical injection pipe 8 is 30 mm, and the inner diameter is 3 mm
10 mm from the open end of the sludge supply pipe 7
4 pieces were formed at the position. The dewatering performance of this centrifuge 1 was 1 m ³ / hour. The sludge concentration of raw sludge supplied to such a centrifuge 1 is 1.0% (1000
It was 0 mg / L). Concentration of polymer flocculant is 0.1%
And the injection amount was 0.04 to 0.12 m ³ / hour. The chemical injection rate was in the range of 0.4 to 1.2%.

On the other hand, in the conventional centrifuge shown in FIGS. 3A and 3B, the inner diameter of the sludge supply pipe 7 is 20 m.
1 except that the inner diameter of the medicine injection pipe 8 is 30 mm and the medicine is discharged substantially along the axial direction of the medicine injection pipe 8.
The same operation was performed as in the centrifuge of the present invention shown in (a) and (b).

The SS recovery rate and the water content of the dehydrated cake were measured, and the results are shown in FIG. FIG. 2 is a characteristic diagram of the centrifuge 1 in which the vertical axis represents the SS recovery rate (%) and the water content (%) of the dehydrated cake, and the horizontal axis represents the chemical injection rate (%). In FIG. 2, the line containing white circles shows the result of this embodiment, and the line containing black circles shows the result of the conventional example.

As is clear from FIG. 2, in the case where the same SS recovery rate and water content of the dehydrated cake are achieved, the number of cases of this example is smaller than that of the conventional example, and specifically about 10
% Reduction can be achieved.

[0026]

As it is evident from the foregoing description, according to the present invention, provided the drug release hole which releases the drug radially provided on the outer periphery near the tip of the chemical injection tube dosing means and in the sludge supply chamber As a result, the chemicals are vigorously injected into the raw sludge in the sludge supply chamber at high pressure in multiple directions, so that the chemicals and the raw sludge can be efficiently mixed. Further, since the chemicals and the raw sludge sufficiently react with each other, there is an effect that the conventional SS recovery rate and the water content of the dehydrated cake can be maintained even if the chemical injection rate is small. Therefore, it is possible to reduce sludge treatment at a low cost because the chemical cost, which has dominated the running cost of the centrifuge, can be reduced. Further, according to the present invention, since the chemical injection pipe and the sludge supply pipe are combined and integrated, space saving of the device can be achieved.

[Brief description of drawings]

1 (a), (b) and (c) are diagrams showing a configuration of a centrifuge according to Embodiment 1 of the present invention,
(A) is a schematic front view of a part of which is shown in cross section, (b) is a front view showing a structure of a composite pipe including a sludge supply pipe and a chemical injection pipe, and (c) is an A of (b). FIG.

FIG. 2 is a characteristic diagram of a centrifuge in which the vertical axis represents the SS recovery rate (%) and the water content of the dehydrated cake (%), and the horizontal axis represents the chemical injection rate (%).

FIG. 3 (a) is a schematic front view showing a part of a configuration of a conventional centrifuge in a sectional view, and FIG. 3 (b) is an opening of a composite pipe in the centrifuge shown in FIG. 3 (a). Part A
FIG.

4A and 4B show another example of a conventional composite pipe, FIG. 4A is a front view, and FIG. 4B is an enlarged view taken along the line AA of FIG. is there.

[Explanation of symbols]

1 centrifuge 2 outer body bowl 2a pool 3 Main motor 4 Inner trunk screw 4a screw 5 Back drive motor 6 Sludge supply room 7 Sludge supply pipe 7a Supply port (sludge supply pipe) 8 chemical injection tubes 8a Injection port (chemical injection pipe) 9 communication ports 10, 11 outlet 12 gearbox 20 Chemical release hole

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-151958 (JP, A) JP-A-47-40556 (JP, A) Actually-opened Shou 61-11963 (JP, U) Polymer flocculant Research Report on Improvement of Dewatering Efficiency of Centrifugal Dewatering Machine, Tokyo Metropolitan Sewerage Bureau, Technical Development Department, Planning Department, March 1989, 8, 10, 116-119 (58) Fields investigated (Int.Cl. ⁷ , DB name) B04B 1/20 B04B 11/02 C02F 11/14 C02F 1/38

Claims (2)

(57) [Claims] 1. A rotatable outer barrel bowl, and an inner barrel screw coaxially rotatably disposed in the outer barrel bowl,
A pool formed between the inner body screw and the outer body bowl, a sludge supply chamber provided in the inner body screw, a sludge supply pipe for supplying raw sludge to the sludge supply chamber, In a centrifuge equipped with a chemical injection means having a communication port for communicating a sludge supply chamber and the pool, and a chemical injection means for injecting a chemical into the sludge supply chamber, wherein the chemical injection means is the sludge supply chamber chemicals to the disposed a chemical injection tube, characterized in that it has a plurality of drug release hole which releases chemicals radially outside is provided on the peripheral and the sludge supply chamber near the tip of the drug product injection tube Centrifuge with injection means. 2. A centrifugal separator sludge supply pipe equipped with a chemical injection unit according to claim 1, characterized in that it is disposed within the dosing tube.