JPH1085793A - Agitating device for digestion tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the gas in an anaerobic digestion tank from remaining therein and prevent the pressure of the gas from abnormally rising. SOLUTION: A center dome (top protrusion) 57 is provided at a ceiling of a digestion tank 1 and a through hole 5 is provided in the dome 57, and a water sealing pipe 34 is provided in the hole 5 so as to provide a predetermined gap between the pipe 34 and the inner wall of the hole 5. A gas vent pipe 53 is connected to the dome through a wall 8b of the dome. The water level of sludge does not rise as far as the pipe 53 and hence when the interior of the tank 1 is water-sealed, gas does not remain in the upper zone of the tank 1. By connecting a safety valve pipe 56 and a safety valve 54 to the wall 8b, a rise in gas pressure due to clogging of the pipe 53 can be prevented so that the gas pressure in the tank 1 can be prevented from abnormally rising.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stirring device for an anaerobic digestion tank for sludge.

[0002]

2. Description of the Related Art An anaerobic digestion tank for sludge has conventionally been provided with a stirrer for stirring water in which sludge contained therein floats. FIG. 3 is a front view showing an example of a conventional digestion tank stirring device, and FIG. 4 is a front view showing an example of a conventional digestion tank stirring device in the overall configuration.

As shown in FIGS. 3 and 4, sludge 4 floats on the surface of water contained in digestion tank 1 (hereinafter, the water in which sludge floats is referred to as "sludge"). 4a is the water surface of the sludge at the time of water sealing. An inspection port 32 is opened in the ceiling of the digestion tank 1, and a blind flange 36 is provided in the inspection port 32.
Is provided. The blind flange 36 is a removable lid. Inside the digestion tank 1 is a tubular water sealing pipe 34.
Are provided vertically. The upper end of the water sealing pipe 34 is connected to the inspection port 32. The lower end of the water sealing pipe 34 can be submerged in the sludge 4 in the digestion tank 1,
The digestion tank 1 can be sealed.

[0004] In the digestion tank 1, a draft tube 2 is provided.
(Three in FIG. 3) are provided with their lower ends fixed to the tank bottom of the digestion tank 1. The upper ends of the legs 6 are combined, and the upper end of the draft tube 2 is fixed to the upper end of the legs 6 via an annular ring plate 27 disposed therearound. . A jig 31 connects the upper end of the leg 6 and the ring plate 27. The lower end of the draft tube 2 erected vertically is fixed by legs 6. In addition, the lower end of the draft tube 2 is located at a height separated from the tank bottom by a predetermined distance.

On the upper surface of the ring plate 27, four guide rods 22 are vertically provided around the draft tube 2. In FIG. 3, the illustration of the guide rod on the near side is omitted. Ring-shaped connecting rings 28 and 29 for connecting the guide rods 22 to each other are provided horizontally at the upper end and the intermediate part of the guide rods 22.
A sliding mechanism 2 slidable between the left and right guide rods 22a and 22b shown in FIG.
1a, the guide rods 22a,
2b so as to be slidable horizontally. Lifting guide 2
1 are provided with wire (or chain) mounting holes 24 at the sliding mechanism mounting portions at both ends, and a lifting wire 38 (or chain) is provided between the inner wall of the tank 1 and the mounting hole 24. They are connected. At the center of the lifting guide 21, an arm 23 is provided vertically downward from the center. The underwater stirrer 3 is provided at the lower end of the arm 23. The stirrer 3 includes a motor 37 attached to the lower end of the arm 23, and a rotatable screw 39 attached to the motor shaft. Furthermore, the motor 3
7 is provided with a holder 25 at the lower part. Holder 25
Can connect the lower part of the motor 37 and the wrapper part 26 of the holder at the upper end of the draft tube 2, and the stirrer 3 can be installed on the top of the draft tube 2 by connecting both parts.

During normal operation, the sludge 4 is stirred by the underwater stirrer 3, and generated gas is collected in a gas holder (not shown) by a gas vent pipe 10 penetrating the tank outer wall 8. Also, when checking or replacing the underwater stirrer 3, the water level of the sludge is set to the water level 4a at the time of water sealing, and the inside gas is not released to the outside. I have. The stirrer 3 installed on the top of the draft tube 2 is a lift guide 2
By the operation of the carrying-in / out mechanism including the arm 1, the arm 23, the holding tool 25, and the guide rod 22, it is possible to move up and down inside the tubular body of the water seal pipe 34 and inside the digestion tank 1 below the tubular body. . Here, the length of the arm 23 is such that when the underwater stirrer 3 is installed at the top of the draft tube 2 by the holder 25, the position of the elevating guide 21 is above the water surface 4a of the sludge at the time of water sealing. It has been adjusted to be. 3 and 4, the arrow A indicates the stirrer 3
Shows the direction in which sludge flows due to the action of. (Hereinafter referred to as "prior art")

[0007]

However, the prior art has the following problems. If the water level at the time of water sealing is set high, the gas vent pipe will also be water sealed, and if left unattended for a long time during inspection or replacement of the underwater stirrer, the gas pressure will increase, and explosive gas will blow at once. Released through the water seal pipe and released into the atmosphere, which is dangerous for work.

Accordingly, an object of the present invention is to provide a stirrer for a digestion tank capable of safely checking and replacing an underwater stirrer without increasing the gas pressure in the tank in view of the above points. It is in.

[0009]

According to the first aspect of the present invention,
In a stirring device for an anaerobic digestion tank for sludge, an upper projection is provided on a ceiling portion of the digestion tank so as to project upward from the ceiling portion, and has a through-hole therein for communicating the inside and the outside of the digestion tank. Part, in the through-hole and in the digestion tank, in the through-hole, a predetermined gap with the inner wall of the through-hole is opened, and in the digestion tank, the lower end is submerged in water in which the sludge floats. A water sealing pipe provided so as to seal the digestion tank, and an upper end and a lower end thereof are opened below the water sealing pipe in a state of being immersed in water in which sludge floats. Draft tube, detachable at the upper end of the draft tube, a stirrer for stirring the water in which the sludge floats,
A stirrer carry-in / out mechanism for carrying the stirrer into and out of the digestion tank through the through-hole and the water sealing pipe, and attaching and detaching the stirrer to an upper end of the draft tube,
A gas vent pipe for penetrating the digestion gas generated in the digestion tank, penetrating the wall of the upper protrusion, connected to the gap between the water sealing pipe and the inner wall of the through hole. It is characterized by having the following.

According to a second aspect of the present invention, the safety valve pipe penetrates the wall of the upper protruding portion and is connected to the gap between the water sealing pipe and the inner wall of the through hole. And a safety valve provided when the digestion gas accumulated in the upper part of the digestion tank reaches a predetermined pressure or more.

An upper protruding portion is provided on a ceiling portion of the anaerobic digestion tank, a through hole is provided inside the upper protruding portion for communicating between the inside and the outside of the digestion tank, and a predetermined gap is provided in the digestion tank with an inner wall of the through hole. Open the water seal pipe. A gas vent pipe is connected to a gap between the through hole and the water sealing pipe by penetrating the wall of the upper protruding portion, and gas is vented. The water level of the sludge does not rise to the gas vent pipe, and gas does not accumulate at the upper part of the digestion tank when water is sealed in the digestion tank. In addition, by connecting the safety valve pipe and the safety valve, it is possible to cope with the gas pressure rise due to clogging of the gas vent pipe, etc., and the gas pressure does not abnormally increase in the digestion tank, and the gas release of the digestive gas is stabilized. I can do it.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the upper structure of the digester tank stirring device according to one embodiment of the present invention, and FIG. 2 is a front view showing the entire configuration of the digester tank stirring device according to one embodiment of the present invention. 1 and 2, substantially the same or equivalent parts as those in FIGS. 3 and 4 showing the conventional example are denoted by the same reference numerals as in FIGS.

As shown in FIGS. 1 and 2, sludge 4 floats on the surface of water contained in an anaerobic digestion tank 1 for sludge. 4a is the water surface of the sludge at the time of water sealing. Less than,
The water in which the sludge floats will be described as sludge as in the description of the prior art.

The ceiling of the digestion tank 1 is provided with a center dome 57 which is an upper projecting portion provided to project upward from the ceiling. Inside the center dome 57 is provided a through-hole 5 that communicates between the inside and the outside of the digestion tank 1. A blind flange 36 is provided in the inspection port 32 which is an upper opening of the through hole 5. Blind flange 36
Is a removable lid. Inside the through-hole 5 and inside the digestion tank 1, a tubular water sealing pipe 34 is provided vertically. The upper end of the water sealing pipe 34 is connected to the inspection port 32. The lower end of the water sealing pipe 34 can be submerged in the sludge 4, and the digestion tank 1 can be sealed by submerging the water sealing pipe 34 in the sludge 4.

In the digestion tank 1, a draft tube 2 is provided.
(In the present embodiment shown in FIG. 1, 3
The leg 6 of the book is fixed to the bottom of the digestion tank 1 at the lower end thereof. The upper ends of the legs 6 are combined, and the upper end of the draft tube 2 is fixed to the upper end of the legs 6 via an annular ring plate 27 disposed therearound. . On the upper surface of the ring plate 27, a plurality of, in this embodiment, four, guide rods 22 are vertically provided around the draft tube 2. In FIGS. 1 and 2, the front and rear guide bars are not shown. Between the left and right guide bars 22a, 22b, the guide bars 22a,
An elevating guide 21 having a sliding mechanism 21a slidable with the guide rod 22b is provided horizontally slidably with the guide bars 22a and 22b.

At the center of the lifting guide 21, an arm 23 is provided vertically downward from the center. The underwater stirrer 3 is provided at the lower end of the arm 23, and the stirrer 3 is installed on the top of the draft tube 2 by the holder 25. The stirrer 3 can be moved up and down inside and below the water sealing pipe 34 by the action of the stirrer carrying-in / out mechanism including the elevating guide 21, the arm 23, the holder 25, and the guide rod 22. By the operation of the stirrer 3, the sludge enters the draft tube 2 from the upper end thereof and is discharged from the lower end as indicated by an arrow A in FIG.

A predetermined gap 51 is provided between the concrete slab 8a and the wall 8b constituting the center dome 57 of the digestion tank 1 and the water sealing pipe 34. On one side (the left side in FIG. 1) of the wall body 8b constituting the upper part of the center dome 57, a gas vent pipe port 52 is provided so as to penetrate therethrough.
3 are connected and connected to a gas holder (not shown). A safety valve piping port 55 is provided through the other side (the right side in FIG. 1) of the wall body 8b, and a safety valve piping 56 is connected to the safety valve piping port 55. Further, the safety valve piping 56
Is provided with a safety valve 54 in the middle. Safety valve 54
Is opened when the digestion gas accumulated in the upper part of the digestion tank 1 becomes higher than a predetermined pressure.

When the water level of the sludge is raised to the water level 4a of the sludge at the time of water sealing by checking or replacing the underwater stirrer 3, the generated gas is directly connected to the gas vent pipe 52 provided at the upper portion after the sludge rises. Since the gas flows from the drain pipe 53 to the gas holder, it does not stay at the upper part in the digestion tank. In addition, when the digestion gas accumulates in the upper part of the digestion tank due to clogging of the gas vent pipe opening 52 or the like, and when the pressure exceeds a predetermined pressure, the safety valve 54 automatically opens, and the accumulated gas is released to the atmosphere from the safety valve pipe 56. It has become so.

In this way, even during the operation of the digestion tank and the inspection or replacement of the submersible agitator, the degassing pipe provided at the top of the digestion tank constantly stably releases the generated digestive gas. Since this is performed, gas does not stay in the digestion tank, and high-pressure gas does not blow out.

[0020]

As described above, according to the present invention, since the gas vent pipe is provided at the upper projecting portion above the water surface, the gas vent is sufficiently performed without submerging.
The gas does not accumulate in the upper part of the digestion tank, and the gas pressure does not increase, so that the digestion tank can be operated safely, and the inspection and replacement work of the underwater agitator can be performed, and thus an industrially useful effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing the upper structure of a digester tank stirring device according to an embodiment of the present invention.

FIG. 2 is a front view showing the entire configuration of the digester tank stirring device according to one embodiment of the present invention.

FIG. 3 is a front view showing one example of a conventional digestion tank stirring device.

FIG. 4 is a front view showing an example of a conventional agitating device for a digestion tank in an overall configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anaerobic digestion tank 2 Draft tube 3 Underwater stirrer 4 Sludge 4a Sludge water sealing surface 5 Through hole 6 Leg 8 Tank outer wall 8a Concrete slab 8b Wall 10 Gas release pipe 21 Elevating guide 21a Sliding mechanism 22, 22a, 22b Guide rod 23 Arm 24 Wire mounting hole 25 Holder 26 Wrapper part of holder 27 Ring plate 28, 29 Connection ring 31 Jig 32 Inspection port 34 Water sealing pipe 36 Blind flange 37 Motor 38 Lifting wire 39 Screw 51 Gap 52 Gas Vent piping port 53 Gas vent piping 54 Safety valve 55 Safety valve piping port 56 Safety valve piping 57 Center dome A Direction of sludge flow

Continued on the front page (72) Inventor Shunichi Kamezaki 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (2)

[Claims] 1. A stirrer for an anaerobic digestion tank for sludge, which is provided on a ceiling portion of the digestion tank so as to protrude upward from the ceiling portion. An upper protruding portion having a hole, a predetermined gap with the inner wall of the through hole in the through hole and the digestion tank in the through hole, and sludge floats at a lower end portion in the digestion tank. A water-sealing pipe provided so as to be able to seal the digestion tank by being submerged in water, and an upper end and a lower end thereof, which are erected below the water-sealing pipe in a state of being immersed in the water in which sludge floats. A draft tube that is open, a stirrer that is detachable at the upper end of the draft tube, and that stirs the water in which the sludge floats, and that the stirrer is connected through the through-hole and the water-sealing pipe. A stirrer carry-in / out mechanism for carrying in / out the digestion tank and attaching / detaching to / from the upper end of the draft tube, and a penetrating wall of the upper projecting portion, between the water sealing pipe and an inner wall of the through hole And a gas vent pipe connected to the gap for exhausting digestion gas generated in the digestion tank. 2. A safety valve pipe penetrating a wall of the upper protruding portion and connected to the gap between the water sealing pipe and an inner wall of the through hole, and the safety valve pipe is provided on the safety valve pipe. The apparatus according to claim 1, further comprising a safety valve that opens when the digestion gas accumulated in the upper part of the digestion tank reaches a predetermined pressure or higher.