JPH0810798A - Agitation device for digestion tank - Google Patents

Abstract

PURPOSE:To provide the device by which even an existing digestion tank can be provided with a mechanical agitation type agitator without loading the top slab of the tank with any burden and the maintenance of the agitator can simply be performed. CONSTITUTION:In the digestion tank, an inspection hatch 32 consisting of a tightly sealable pipe 34 for water sealing is provided in the outer wall 8 of the tank at the position right above a draft tube 2 so that the pipe 34 projects from the wall 8 into the upper space 14 in the digestion tank. The draft tube 2 is erected and fixed in the digestion tank in such a state that the both ends of the tube 2 are opened so as to submerge in sludge 5. An underwater agitator 33 is placed in the draft tube 2 so as to be insertable into and removable from the draft tube 2 through the inspection hatch 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stirring device for an anaerobic digestion tank for sludge.

[0002]

2. Description of the Related Art FIG. 19 shows, for example, Japanese Examined Patent Publication No. 59-46654.
FIG. 20 is a vertical cross-sectional view showing the entire structure of an example of a digestion tank used for the conventional anaerobic treatment of sludge shown in Japanese Patent Publication, and FIG. 20 is an enlarged vertical cross-sectional view showing details of the mechanical stirring device. .

In this digestion tank 1, a draft tube 2 is installed in an upright state so that it can be submerged in sludge inside, and a screw 4 of an agitator 3 is inserted into the draft tube 2 from an upper end opening thereof. , Screw 4
Is rotated downward in the draft tube 2 (Fig. 19).
Is indicated by a solid line arrow) or upward (indicated by a dashed line arrow in FIG. 19) to generate a circulating flow by forced convection in the tank to stir the sludge 5 as a whole. You can do it. That is, the draft tube 2 and the screw 4 function like a vertical axial flow pump having the screw 4 as an impeller and the draft tube 2 as a casing.

More specifically, as shown in FIG. 19, the lower portion of the draft tube 2 is fixed to the inner wall of the lower portion of the digestion tank 1 via a plurality of legs 6, and the upper portion thereof is connected via a tie rod 7. Is fixed to the upper inner wall of the digestion tank 1 and is vertically arranged in the sludge 5 in the digestion tank 1, whereby the sludge is sucked from one end opening and the sucked sludge is discharged from the other end opening. It can be discharged. As shown in FIG. 20, the agitator 3 has a motor 11 arranged outside a bearing box 10 installed by embedding it in a concrete slab 8 directly above a draft tube of a digestion tank 1 with a mortar 9 and installing the motor 11 via the bearing box 10. The output shaft and the shaft 12 of the screw 4 are connected. Also,
A splash disk 13 is attached to the shaft 12 at a position near the liquid surface of the sludge,
When the upward flow is generated inside, sludge discharged from the upper end opening of the draft tube 2 onto the sludge liquid surface is splashed around by the splash disk 13, and the bearing box 10 is contaminated by the discharged sludge. It is possible to prevent this. In addition, digestion tank 1
The upper void 14 in the inside is a combustible digestion gas (pressure is about 150 mmAq) whose main component is methane gas produced in the digestion process.
Is full.

FIG. 21 is a vertical sectional view showing the entire construction of another example of a conventional digestion tank used for conventional sludge treatment, and the same reference numerals are given to the parts corresponding to those of FIGS. 19 and 20 described above. Is attached.

In the digestion tank 21, the digestion gas produced in the digestion process is collected in a gas holder (not shown) through the gas venting pipe 22, the digestion gas is boosted by a blower, and again the pressure is passed through the agitation pipe 23 to a predetermined pressure. By jetting it near the bottom of the tank, or by jetting steam separately generated from the stirring pipe 23 near the bottom of the tank at a predetermined pressure, the sludge 5 in the tank is stirred and anaerobic bacteria The organic substances in sludge are mineralized and gasified by the action of anaerobic bacteria and methane-fermenting bacteria. The digested sludge that has undergone the process of mineralization and gasification to reduce, stabilize, and improve safety is discharged from a digested sludge drawing pipe 24 provided at the center of the bottom of the tank.

[0007]

However, the draft tube 2 in which the stirrer is installed upright inside the digestion tank 1 and the concrete slab 8 on the top of the digestion tank 1 are provided.
The former one, in which the screw 4 connected to the motor 11 of the stirrer 3 is inserted through the upper end opening of the draft tube 2, is a generally adopted technique. Although it has many achievements, it was proposed on the assumption that it is applied to a digestion tank that is designed in advance to have a strength such that the stirrer 3 can be installed on the concrete slab 8 on the top of the digestion tank 1. The digestion tank (type as shown in FIG. 21) that is already in operation without consideration of the above has a problem in that it cannot be installed due to strength problems.

Further, the latter one, in which the sludge 5 in the tank is agitated by ejecting the digestion gas or steam produced in the digestion process to the vicinity of the bottom of the tank, is the same as the former mechanical agitation method. Then, the stirring effect, that is, the digestion treatment efficiency is poor.

For this reason, the digestion tank 2 like the latter, which employs the stirring system with the already operating gas and pump, is used.
Although there is a recent increasing need for changing the No. 1 to the mechanical stirring method like the former, when the former stirrer 3 is installed in the existing digestion tank 21, there are the following problems. The top slab of the existing digestion tank 21 has a small slab thickness, and the strength for installing the agitator 3 is insufficient,
In the design drawings, it is often the case that the strength of the concrete cannot be guaranteed after a lapse of 10 to 20 years even if it has strength, and the stirrer 3 cannot be installed on the top slab of the existing digestion tank 21. Even in such a case, a strong pedestal is installed inside or outside the existing digestion tank 21, the stirrer 3 is placed on the pedestal to receive the load, and the gas seal of the top slab through which the stirrer 3 penetrates is sufficient. If it is devised, installation will be possible, but the equipment will be large and repair costs will be high. Such a problem can be solved by installing a stirrer inside the digestion tank, but since the digestion tank is a device that emits flammable gas, it has a structure that does not allow easy open inspection of the inside. Maintenance is usually performed only once every five years. For this reason,
Not only can maintenance be insufficiently carried out, but when a problem occurs, it is inevitable to spend a huge amount of time and money on inspection and repair.

In view of the above points, the present invention is a digestion tank in which an existing digestion tank can be easily installed with a mechanical stirring type agitator without burdening the top slab, and maintenance can be performed easily. An object of the present invention is to provide a stirrer.

[0011]

According to a first aspect of the present invention, there is provided a digestion tank agitating device, which comprises a draft tube which is vertically fixed in the digestion tank with both ends open and which is immersed in sludge. , An inspection port consisting of a watertight pipe that can be sealed and is installed on the outer wall of the tank directly above the draft tube and projects into the upper void in the digestion tank, and an independently installed submersible water that can be inserted into and removed from the draft tube through the inspection port And a stirrer.

The digestion tank agitator according to a second aspect of the present invention is the digestion tank internal space between the inspection port and the draft tube in the inspection port formed of the water sealing pipe of the first aspect. A guide pipe, which serves as a guide for inserting and removing the submersible stirrer, is configured so that it can be freely inserted and removed.

According to a third aspect of the present invention, in the agitating device for digestion tank, the inner peripheral surface of the guide pipe of the second aspect is the inner periphery of the draft tube when the inspection port and the draft tube are connected. It is set to be the same surface as the surface.

The digestion tank agitator according to a fourth aspect of the present invention comprises a draft tube which is vertically fixed in the digestion tank with both ends open and is submerged in sludge, and a draft tube. Guide bars installed at multiple locations in the upper circumferential direction and extending upward, and an inspection port consisting of a sealable water sealing pipe provided on the outer wall of the tank directly above the draft tube and protruding into the upper void in the digestion tank. , A plurality of slide plates guided by each guide bar, and an underwater agitator independently installed on the upper part of the draft tube through the inspection port.

According to a fifth aspect of the present invention, there is provided a digestion tank agitating device wherein the motor and the screw of the submersible agitator of the fourth aspect are placed on the upper end of the draft tube and communicate with the draft tube. The slide plate is housed in the body, and each slide plate is attached through a plurality of fixtures provided on the outer circumference of the cylinder and extending in the radial direction.

[0016] According to a sixth aspect of the present invention, there is provided a digestion tank agitating device, wherein a plurality of fixing devices extending radially obliquely rearward are provided on the outer periphery of the casing of the motor of the submersible agitator of the fourth aspect. Tools are provided, each slide plate is attached to these fixtures, and a part of the front edge of each fixture is set to be able to abut on the upper end of the draft tube.

According to a seventh aspect of the present invention, in the agitating device for a digestion tank according to the sixth aspect, the upper end of the draft tube of the sixth aspect is formed in a bell shape so that the front edge of each fixture can be in line contact. It is a thing.

The agitator for a digestion tank according to the invention of claim 8 of the present invention is a draft tube which is vertically fixed in a digestion tank with both ends open and is submerged in sludge, and directly above the draft tube. An inspection port, which is provided on the outer wall of the tank and consists of a watertight pipe that can be sealed and protrudes into the upper void in the digestion tank, and guide bars that are installed at a plurality of circumferential positions on the inner wall of the inspection port and extend in the vertical direction, It has a slide plate guided by a guide bar and a hanging piece for loading and unloading in the upper part, and it is assembled with each other, and a plurality of lifting bars that hang downward, and each lifting bar is fixed to the bottom of each lifting bar. Attached to
It is provided with an underwater agitator independently installed above the draft tube through the inspection port.

Further, in the digestion tank agitator according to the invention of claim 9 of the present invention, each lifting piece of claim 8 is arranged at the upper end of each lifting bar, and the length of each lifting bar is set. Is set to a length such that the upper end of each hanging piece faces the top wall of the inspection port with a slight gap when the submersible stirrer is installed.

According to a tenth aspect of the invention, there is provided a digestion tank agitating device, wherein the motor and screw of the submersible agitator according to the eighth or ninth aspect are placed on the upper end of the draft tube. It is housed in a tubular body that communicates with the tube, and is attached to each lifting bar via a plurality of radially extending fixtures provided on the outer circumference of the tubular body.

The agitating device for a digestion tank according to an eleventh aspect of the present invention is the outer periphery of the casing of the motor of the submersible agitator according to the eighth or the ninth aspect, in the radial direction diagonally rearward. A plurality of extending fixtures are provided, each lifting bar is attached to these fixtures, and a part of the front edge of each fixture is set to be able to contact the upper end of the draft tube.

According to a twelfth aspect of the present invention, in the agitating device for a digestion tank according to the eleventh aspect, the upper end of the draft tube is formed in a bell shape so that the front edges of the respective fixtures can come into line contact. It is a thing.

[0023]

In the first aspect of the present invention, the submerged stirrer can be installed simply by inserting it into the draft tube from the inspection port provided on the outer wall of the tank directly above the draft tube, so that the stirrer can be installed easily. Further, since only the inspection port needs to be installed on the outer wall of the tank directly above the draft tube, the burden on the outer wall of the tank directly above the draft tube can be reduced. Therefore, the present invention can be applied to an existing digestion tank whose top slab is thin or brittle. Furthermore, the submersible stirrer and the draft tube, the screw of the submersible stirrer plays a role of a pump blade, the draft tube serves as a casing of the pump, and forms a separate pump independent from the tank outer wall directly above the draft tube in the digestion tank, Moreover, since the inspection port and the draft tube are almost insulated from each other, the pump, which is a vibration source, can be kept away from the inspection port, that is, the outer wall of the tank directly above the draft tube. Further, like the conventional stirrer of FIG. 19, a strong flow can be excited in the draft tube, and sludge in a large capacity digestion tank can be efficiently stirred. Furthermore, since the inspection port is composed of a watertight pipe for sealing that projects into the upper space in the digestion tank, the inspection port can be water-sealed with sludge in the digestion tank. Therefore, the inside of the digestion tank can be easily inspected without removing the flammable digestive gas filling the upper void, and the maintenance can be easily performed.

Further, in the invention of claim 2 of the present invention, the inspection port formed of the water sealing pipe of claim 1 is sealed and connected between the inspection port and the draft tube from the interior space of the digestion tank. The guide pipe that serves as a guide when inserting and removing the submersible stirrer is configured to be insertable and removable, so the inspection port and the draft tube can be inserted by inserting the guide pipe into and out of the draft tube of the submersible stirrer. It is possible to form a single pipe from the draft tube to the inspection port by connecting the two. Therefore, the loading / unloading work into / from the draft tube of the submersible stirrer can be smoothly performed.

Further, in the invention of claim 3 of the present invention, since the inner peripheral surface of the guide pipe of the second invention is set to be flush with the inner peripheral surface of the draft tube, the guide pipe is There is no step in the single tube from the draft tube formed by insertion to the inspection port. Therefore, when the submersible stirrer is carried in and out of the draft tube, there is no interference with the submersible stirrer, and it is possible to prevent accidents such as collisions with the inner cylinder projections of the submersible stirrer. it can.

In the invention of claim 4 of the present invention,
To set the submersible stirrer, insert the slide plates provided in the submersible stirrer into the multiple guide bars extending from the draft tube, and slide the slide bar downward in that state to place the submersible stirrer on top of the draft tube. Install a stirrer. Each guide bar functions as a rotation stopper for the underwater agitator when the underwater agitator is in operation. Generally, the draft tube installed in the digestion tank is installed by connecting several pipes with a flange, but in production,
The flange tends to fall down. In this case, the draft tube will be fixed in the digestion tank with the connecting portion bent. By allowing the submersible stirrer to be installed above the draft tube as described above, even if the draft tube may be installed while being bent in the middle, the influence of this refraction can be avoided. Further, by providing a guide bar on the draft tube side that serves as a guide for loading and unloading the submersible stirrer, the guide pipe can be eliminated.

According to a fifth aspect of the present invention, the motor and screw of the submersible stirrer according to the fourth aspect are housed in a cylindrical body which is placed on the upper end of the draft tube and communicates with the draft tube. Since each slide plate is attached through a plurality of fixing tools provided on the outer circumference of the cylindrical body and extending in the radial direction,
It can be formed into a single tube from the draft tube to the tubular body. Therefore, the submersible stirrer can be set simply by inserting the slide plate into the guide tube on the draft tube side, sliding the slide plate downward in that state, and placing the tubular body, that is, the submersible stirrer on the upper end of the draft tube. .

Further, in the invention of claim 6 of the present invention, a plurality of fixing tools extending in the radial direction toward the diagonal rear side are provided on the outer periphery of the casing of the motor of the submersible stirrer of claim 4, and these fixing parts are fixed. Since each slide plate was attached to the fixture, part of the front edge of each fixture was set to be able to contact the upper end of the draft tube,
A submersible stirrer can be placed inside the top of the draft tube. Therefore, it is not necessary to provide a tubular body or the like around the submersible stirrer as an introduction path to the draft tube, and the device configuration can be simplified. Further, it becomes possible to give each fixture a centering function, and the accuracy of the setting position of the submersible stirrer is improved.

Further, in the invention of claim 7 of the present invention, since the upper end of the draft tube of claim 6 is formed in a bell shape in which the front edge of each fixture is capable of making line contact with each other, it depends on each fixture. The synergistic effect of the centering action and the centering action of the bell-shaped upper end of the draft tube can further improve the accuracy of the setting position of the submersible stirrer. Furthermore, the contact area between the fixture and the upper end of the draft tube can be increased, and the load due to the weight of the submersible stirrer applied to the upper end of the draft tube can be dispersed.
Therefore, the installation state of the submersible stirrer is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

Further, in the invention of claim 8 of the present invention,
To set the submersible stirrer, hoist each lifting bar, insert the submersible stirrer fixed to the bottom of the bar into the inspection port, and lower it onto the draft tube. At this time, when each slide plate provided on the upper part of each lifting bar comes to the position of a plurality of guide bars installed on the inner wall of the inspection port, these are aligned and each slide plate is adjusted to each guide. Insert each into the bar,
In that state, slide it further downward to install the submersible stirrer on the upper part of the draft tube. Each guide bar is
When the submersible stirrer is in operation, it functions as a rotation stopper for the submersible stirrer. In this way, the slide plate and the hanging piece for loading and unloading are placed on the upper part of each lifting bar with the submersible stirrer fixed to the lower part, and multiple guide bars for guiding each slide plate are installed on the inner wall of the inspection port. By providing the slide plates and the guide bars, the positions of the guide plates can be easily adjusted, and the submersible stirrer can be easily loaded, unloaded, and installed, and these operations can be performed smoothly.

Further, in the invention of claim 9 of the present invention, each hanging piece of claim 8 is arranged at the upper end of each lifting bar, and the length of each lifting bar is set to the submersible stirrer. At the time, the upper end of each hanging piece was set to face the top wall of the inspection port with a slight gap, so that the submersible stirrer tried to levitate due to the upward reaction force during the downward flow operation. This can be suppressed by bringing the hanging piece at the upper end of each lifting bar into contact with the top wall of the inspection port. That is, each lifting bar can function as a stopper for preventing floating of the submersible agitator.

According to a tenth aspect of the present invention, the motor and the screw of the submersible stirrer according to the eighth or ninth aspect are placed on the upper end of the draft tube and communicate with the draft tube. In addition to being housed in the tube, the tube is attached to each lifting bar via a plurality of radially extending fixtures provided on the outer circumference of the tube, so that it can be formed into a single tube extending from the draft tube to the tube. . Therefore, hoist each lifting bar,
Insert the submersible agitator fixed to the lower part into the inspection port and lower it, insert the slide plate into the guide bar on the inspection port side and slide it downward in that state,
The submersible stirrer can be set only by placing the tubular body, that is, the submersible stirrer on the upper end of the draft tube.

Further, in the invention of claim 11 of the present invention, a plurality of fixtures extending radially obliquely rearward are provided on the outer circumference of the casing of the motor of the submersible stirrer of claim 8 or 9. Since each lifting bar was attached to these fixtures and part of the front edge of each fixture was set to be able to contact the upper end of the draft tube, an underwater stirrer integrated with the lifting bar was provided. Can be placed inside the top of the draft tube. Therefore, it is not necessary to provide a tubular body or the like around the submersible stirrer as an introduction path to the draft tube, and the device configuration can be simplified. Further, it becomes possible to give each fixture a centering function, and the accuracy of the setting position of the submersible stirrer is improved.

According to the twelfth aspect of the present invention, the upper end of the draft tube of the eleventh aspect is formed in a bell shape so that the front edge of each fixture can make a line contact.
By the synergistic effect of the centering action of each fixture and the centering action of the bell-shaped upper end of the draft tube, the accuracy of the setting position of the submersible stirrer integrated with the lifting bar can be further improved, and the fixtures It is possible to increase the contact area between the top of the draft tube and
It is possible to disperse the load due to the weight of the submersible stirrer and each lifting bar applied to the upper end of the draft tube.
Therefore, the installation state of the submersible stirrer is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

[0035]

【Example】

Example 1. The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a vertical sectional view showing a stirring device for a digestion tank according to the first, second, and third aspects of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a draft of the stirrer. It is an explanatory view of the carrying-in and carrying-out work in and out of the tube, in each figure, the conventional (Figure 1
9 to 21) are denoted by the same reference numerals.

The agitator 31 of the digestion tank of this embodiment is
Draft tube 2 in the top slab 8 of the digestion tank
An inspection port 32 is provided at a position directly above, and the submersible stirrer 33 can be installed simply by inserting it into the draft tube 2 through the inspection port 32.

More specifically, the inspection port 32 has an inner diameter set to be substantially the same as the outer diameter of the draft tube 2, and a water sealing pipe 34 whose lower end projects into the upper void 14 in the digestion tank. The water-sealing pipe 34 is provided with an outward flange 35 at the upper end protruding outward (atmosphere side) from the top slab 8 of the water-sealing pipe 34, and a blind blind flange 36 for sealing is attached to the outward flange 35. Submersible stirrer 3
Reference numeral 3 extends in the motor axial direction through three fixing portions 38 extending in the radial direction at three locations (three locations in the present embodiment, but not limited to three locations) in the circumferential direction of the casing of the motor 37. The slide rod 39 is integrally provided, and thus the slide rod 39 can slide up and down in the draft tube 2 and the water sealing pipe 34 without tilting. One end of each lifting wire (or chain) 41 is fixed to each slide rod 39, and the other end of each lifting wire 41 is
It is hung from a plurality of hooks 42 detachably attached to the inner wall of the water sealing pipe 34 that is the inspection port 32. The power cable 43 of the motor 37 is spirally wound around one of the hoisting wires 41 or stopped so that it can be prevented from swinging by the sludge 5 flowing in the draft tube 2 when the device is in operation. It is fixed with metal fittings and guided upwards in the draft tube 2, and then the water sealing pipe 3
4 is drawn out from the blind flange 36 of the inspection port 32 to the outside (in the atmosphere). In the draft tube 2,
A ring-shaped stopper 44 that receives the slide rods 39 of the submersible stirrer 33 downward is fixed to the inner periphery of the lower end portion thereof, and a bell mouth having the same inner diameter as the water sealing pipe 34 is formed on the outer periphery of the upper end thereof. 45 is attached. To stop the rotation of the submersible stirrer, a stopper consisting of a flat bar or the like may be fixed vertically to the inner wall of the draft tube, so that even if the submersible stirrer tries to rotate by its own reaction force, the slide rod will stop. Therefore, the free rotation due to the reaction force of the agitator itself can be restricted. Also, since there is a risk that the submersible stirrer will be lifted by the upward reaction force during downward flow operation, either attach a weight that overcomes the lift force or claw the outside of the slide rod at the same time as energizing at the start of operation. It is only necessary to devise such a structure that the Other configurations are the same as those of the above-mentioned conventional example.

In the digestion tank agitation apparatus of this embodiment, the submersible agitator 33 and the draft tube 2 have a screw 46 of the submersible agitator 33 serving as a blade of the pump and a draft tube 2 serving as a casing of the pump. An inspection port 32 immediately above the draft tube, that is, a pump independent of the top slab 8 is formed inside the pump, so that the pump serving as the vibration source is installed at a position far from the top slab 8 and the lifting wire (or chain) 41 Check port 3 as it is only connected with
It is possible to suppress the influence of vibration on the 2 and secure the sealing property easily. Further, like the conventional stirrer, a strong downward or upward flow can be excited in the draft tube 2, and the sludge 5 in the large-capacity digestion tank can be efficiently stirred.

When inspecting the submersible stirrer 33, refer to FIG.
As shown in (1), first, the water level in the digestion tank is raised, and the inspection port 32, that is, the lower end opening of the water sealing pipe 34 is water sealed.
Then, the blind flange 36 of the inspection port 32 is removed, and FIG.
As shown in, a guide pipe 47 is inserted into the inspection port 32 from above so as to seal and connect the inspection port 32 and the draft tube 2 from the internal space of the digestion tank. At this time, the power cable 43, the hoisting wires 41, and the hooks 42 are moved out of the way. After that, the respective hoisting wires 41 are hung on the hooks 48 of the crane and hoisted, and the submersible stirrer 33 is carried out to the outside. The guide pipe 47 is
When the inspection port 32 and the draft tube 2 are connected, the inner peripheral surface 47a thereof is set to be flush with the inner peripheral surface 2a of the draft tube 2, and the guide pipe 47 connects the inspection port 32 and the draft tube 2 to each other. When the spaces are connected, the inner surface from the draft tube 2 to the inspection port 32 can be formed into a single pipe having no step. Therefore, when the submersible stirrer 33 is carried out, there is no interference with the submersible stirrer 33, and no accident such as collision with the inner cylinder step portion of the submersible stirrer 33 occurs, and the submersible stirrer 33 can be carried out smoothly. it can. Resetting of the submersible stirrer 33 is performed in the reverse order of the above.

As described above, in the digestion tank agitation apparatus of this embodiment, the inspection port 32 is provided at a position directly above the draft tube 2 in the top slab 8 of the digestion tank, and the submersible stirrer 33 is inserted from the inspection port 32 into the draft tube 2. Since it can be installed simply by inserting it into the, the installation of the stirrer is simplified, and the load on the top slab 8 of the digestion tank can be reduced. Therefore, the present invention can be applied to an existing digestion tank whose top slab is thin or brittle. Further, since the inspection port 32 is composed of the water sealing pipe 34 that can be sealed and projects into the upper space 14 in the digestion tank, the inspection port 32 can be water-sealed with the sludge 5 in the digestion tank. Therefore, the inside can be easily inspected without removing the flammable digestive gas filling the upper space 14 in the digestion tank, and the maintenance can be easily performed.

In the above embodiment, the submersible stirrer 33 is set in the draft tube 2 so that the screw 46 is located above the motor 37. However, the draft tube 2 is lifted to the screw 46. Screw 4 to avoid entanglement of the power wire 41 and the power cable 43
6 may be set under the motor 37,
Alternatively, as shown in FIG. 4, a casing 49 may be provided around the screw 46 for increasing efficiency and for protection.

Example 2. FIG. 5 is a vertical cross-sectional view showing an agitating device for a digestion tank according to claims 4 and 5 of the present invention.
5 is a cross-sectional view taken along the line BB of FIG. 5, and FIG. 7 is an explanatory view of the loading / unloading work of the agitator into / out of the draft tube,
In each figure, the portions corresponding to those of the above-described first embodiment (FIGS. 1 to 4) are designated by the same reference numerals.

Stirring device 51 of the digestion tank of this embodiment
Is to carry the underwater agitator 52 into the digestion tank through the inspection port 32 provided directly above the draft tube 2 in the top slab 8 of the digestion tank, and place the underwater agitator 52 on the upper end of the draft tube 2. It can be installed at.

More specifically, the draft tube 2 is provided with outward flanges 53 at its upper end, and one end is fixed to the lower surface side of the flange 53 at a plurality of positions in the circumferential direction of the flange 53. A guide bar 54 is installed with its ends extending upward. The motor 37 and the screw 46 of the submersible stirrer 52 are
It is placed on the flange 53 of the draft tube 2 and is housed in a drum-shaped cylinder 55 communicating with the draft tube 2, and is fixed by a plurality of arms 56. The tubular body 55 is provided with fasteners 57 extending in the radial direction at three circumferential locations (three locations in the present embodiment, but not limited to this) on the outer circumference of the tubular body 55. A slide plate 58 that is slidable by being fitted into each guide bar 54 on the draft tube 2 side is attached to the tip end. Therefore, each guide bar 54 functions as a rotation stopper (stopper) that restricts free rotation by the reaction force of the agitator itself when the submersible agitator 52 is operating. In order to prevent the submersible agitator 52 from floating during the downward flow operation, a weight that overcomes the lifting force is attached, or the guide bar 54 is gripped at the same time as the energization at the start of the operation, as in the first embodiment. A device such as a mechanism may be provided. Further, one end of a lifting wire (or chain) 41 is fixed to a plurality of positions on the upper end of the tubular body 55, and the other end of each lifting wire 41 is an inner wall of a water sealing pipe 34 which is an inspection port 32. Is hung from a plurality of hooks 42 which are detachably attached to the. The other structure is the same as that of the first embodiment.

In the stirring apparatus 51 of the digestion tank of this embodiment, in order to set the submersible stirrer 52, each slide plate 58 on the submersible stirrer 52 side is inserted into each guide bar 54 on the draft tube 2 side, In that state, slide the lower end flange 5 of the tubular body 55 by sliding it downward.
9 is placed on the flange 53 of the draft tube 2.

When inspecting the submersible agitator 52, refer to FIG.
As shown in (1), first, the water level in the digestion tank is raised, and the inspection port 32, that is, the lower end opening of the water sealing pipe 34 is water sealed.
Then, the blind flange 36 of the inspection port 32 is removed, and FIG.
As shown in FIG. 5, the extension guide bar 54A is connected to the upper end of each guide bar 54. At this time, power cable 4
3. The hoisting wires 41 and the hooks 42 are moved so as not to get in the way. Then, each hoisting wire 41 is hung on the hook 48 of the crane and hoisted, and the underwater agitator 52 is moved to each guide bar 54 and each extension guide bar 54A.
Slide it upward while guiding it to the outside. The submerged stirrer 52 is reset by the procedure reverse to the above.

As described above, the cylindrical body 5 communicating with the draft tube 2 and forming one tube together with the draft tube 2.
Since the motor 37 and the screw 46 of the submersible stirrer 52 are housed in 5 and the submersible stirrer 52 together with the tubular body 55 can be installed by simply mounting the submersible stirrer 52 on the flange 53 of the draft tube 2, However, the guide pipe can be eliminated, and even if the draft tube 2 is installed while being bent in the middle, the influence of the refraction can be avoided.

In this embodiment, the guide bar 54 and the extension guide bar 54A are described as being separable, but the guide bars 54, 54 are not shown.
Since A does not greatly affect the flow of sludge 5 in the digestion tank, these guide bars 54, 54A may be set to a length that can be accommodated in the inspection port 32 and integrally formed. In this case, the setting positions of the guide bars and the hooks 42 may be displaced from each other in the circumferential direction so that the hooks 42 are always fixed.

Embodiment 3 FIG. FIG. 8 shows claims 8 and 9 of the present invention.
10 is a longitudinal sectional view showing a stirring device for a digestion tank according to the invention of FIG. 10, FIG. 9 is a sectional view taken along the line CC of FIG. 8, FIG. 10 is a sectional view taken along the line DD of FIG. 8, and FIG. It is explanatory drawing of the carrying in / out operation of the draft tube inside and outside of an agitator, and in each figure, the same code | symbol is attached | subjected to the part corresponding to the above-mentioned Example 2 (FIGS. 5-7).

Stirring device 61 of the digestion tank of this embodiment
Is provided with guide bars 62 extending in the vertical direction at the inspection port 32 side, that is, at a plurality of circumferential positions on the inner wall of the water sealing pipe 34. On the side of the submersible agitator 63, the motor 3
A wide fixture 57A extending radially is provided at three circumferential positions (three in this embodiment, but not limited to this) on the outer circumference of the drum-shaped cylindrical body 55 accommodating the screw 7 and the screw 46. Is provided, the lower end of the lifting bar 64 is fixed to the tip of each fixture 57A, and the slide plate 65 guided by each guide bar 62 is attached to the upper part of each lifting bar 64. The upper ends of the lifting bars 64 are connected to each other by a connecting bar 66 so that their positional relationship is fixed. That is, each lifting bar 64 has a cage shape in which the upper end is connected by the connecting bar 66 and the lower end is connected by the respective fixing members 57A. Further, a lifting piece 67 for loading / unloading is provided on the upper end of each lifting bar 64. The length of each lifting bar 64 is such that the upper end of each lifting piece 67 faces the top wall of the inspection port 32, that is, the inner surface of the blind flange 36 with a slight gap when the submersible stirrer 63 is installed. Each is set. The other structure is the same as that of the second embodiment.

In the digestion tank agitator 61 of this embodiment, in order to set the submersible agitator 63, each lifting bar 67 is used to lift each lifting bar 64.
The submersible agitator 63 fixed to the lower part of the inspection port 32
Insert it inside and drop it onto the draft tube 2. At this time, when the slide plates 65 provided on the upper portions of the lifting bars 64 come to the positions of the guide bars 62 installed on the inner wall of the water sealing pipe 34, the slide bars 65 are aligned with each other. The slide plate 65 is inserted into each of the guide bars 62, and in that state, the slide plate 65 is further slid downward to mount the lower end flange 59 of the tubular body 55 on the flange 53 of the draft tube 2. Each guide bar 6
2 functions as a rotation stopper (stopper) that restricts free rotation by the reaction force of the agitator itself when the submersible agitator 63 is operating. In addition, each of the lifting bars 64 is configured such that the submersible stirrer 63 receives an upward reaction force and tries to float when the downflow operation is performed, and the suspension pieces 67 at the upper end contact the inner surface of the blind flange 36. Hold down by. That is,
Each lifting bar 64 functions as a stopper for preventing the submersible agitator 63 from rising.

When inspecting the submersible agitator 63, refer to FIG.
As shown in FIG. 1, first, the water level in the digestion tank is raised, and the inspection port 32, that is, the lower end opening of the water sealing pipe 34 is water sealed. Then, the blind flange 36 of the inspection port 32 is removed to expose each hanging piece 67, and each hanging piece 67 is lifted by hanging each hanging wire 41 hanging from the hook 48 of the crane as shown in FIG. Slide 63 upward while guiding 63 to each guide bar 62. Even if each slide plate 65 provided on the upper part of each hoisting bar 64 is detached from each guide bar 62, hoisting is continued upward until the submersible agitator 63 is carried out to the outside of the inspection port 32. Type stirrer 63 is inspection port 3
If it is carried out to the outside of 2, the lifting is stopped and the inspection is performed in that state, or if necessary, the submersible agitator 63 is moved to the outside of the digestion tank and then the inspection is performed. Resetting of the submersible stirrer 63 is performed in the reverse order of the above.

In this way, the slide plate 65 and the carrying piece 67 for carrying in / out are arranged on the upper part of each lifting bar 64 having the submersible stirrer 63 fixed to the lower part thereof, and each slide plate is arranged on the inner wall of the water sealing pipe 34. By providing a plurality of guide bars 62 for guiding 66, each slide plate 66 and each guide bar 62 are exposed at the time of inspection,
These positions are easily aligned, and loading, unloading and installation of the submersible agitator 63 are facilitated, and these operations can be performed smoothly.

Example 4. FIG. 12 shows claim 4 of the present invention.
6 and 7 are longitudinal sectional views showing a stirring device for a digestion tank, FIG. 13 is a sectional view taken along the line EE of FIG. 12, and FIG. 14 is a description of loading / unloading work of the stirring machine into / out of a draft tube. It is a figure, and in each figure, the same code | symbol is attached | subjected to the part corresponding to the above-mentioned Example 2 (FIGS. 5-7).

Stirring device 71 of the digestion tank of this embodiment
The above-mentioned Example 1 (FIGS. 1 to 4) and Example 2 (FIG. 5).
7 to 7). That is, the digestion tank agitation device 71 of this embodiment has three circumferential positions on the outer periphery of the casing of the motor 37 of the submersible agitator 72 (three in the present embodiment, but not limited to this). Is provided with a wide fixture 57B extending in the radial direction diagonally rearward.
The slide plate 58A is attached to B, and a part of the front edge of each fixture 57B is set to be able to contact the upper end of the draft tube 2. Further, the upper end of the draft tube 2 is formed in a bell shape 53A with which the front edge portion of each fixture 57B can make line contact. Each lifting wire (or chain) 41 has one end connected to the upper end (rear edge) of each fixture 57B, and the other end attachable to and detachable from the inner wall of the water sealing pipe 34 which is the inspection port 32. It is hung from a plurality of hooks 42 attached to each. In addition, also in this embodiment,
Similar to the above, in order to prevent the submersible agitator 72 from floating during the downward flow operation, a weight that overcomes the lifting force is attached, or a gripping mechanism that grips the guide bar 54 at the same time as energization at the start of operation is provided. It goes without saying that the device has been devised. The other structure is the same as that of the second embodiment.

In the digestion tank agitator 71 of this embodiment, the procedure of setting the submersible agitator 72 (FIG. 12) and carrying-in / carrying-out work (FIG. 14) at the time of inspection is the same as that of the second embodiment. Therefore, the description thereof will be omitted. In the agitator 71 of the digestion tank of this embodiment, each of the wide fasteners 57B extending radially obliquely rearward is provided on the outer periphery of the casing of the motor 37 of the submersible agitator 72, and the front edge of each fastener 57B is provided. Since a part of each part is set so as to be able to contact the upper end of the draft tube 2, basically, the stationary submersible agitator 72 can be arranged inside the upper part of the draft tube. Therefore, it is not necessary to provide a cylinder or the like around the submersible agitator 72, which serves as an introduction path to the draft tube 2, and the device configuration can be simplified. Further, each fixture 57B can be provided with an aligning function, and the accuracy of the set position of the submersible agitator 72 is improved.

Further, since the upper end of the draft tube 2 is formed in a bell shape 53A in which the front edge of each fixture 57B can make line contact, the centering action of each fixture 57B and the bell shape of the draft tube 2 are formed. The synergistic effect of the centering action by 53A can further improve the accuracy of the setting position of the submersible agitator 72. Further, the contact area between each fixture 57B and the upper end of the draft tube can be increased, and the load due to the weight of the submersible agitator 72 applied to the upper end of the draft tube can be dispersed. For this reason,
The installation state of the submersible agitator 72 is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

Example 5. FIG. 15 shows claim 8 of the present invention.
FIG. 16 is a vertical sectional view showing a stirring device for a digestion tank according to the invention of 9, 11, and 12, FIG. 16 is a sectional view taken along the line FF of FIG. 15, and FIG. 17 is a sectional view taken along the line GG of FIG. FIG. 18 is an explanatory view of the loading / unloading work of the stirrer into / out of the draft tube, and corresponds to the above-described Embodiment 3 (FIGS. 8 to 11) and Embodiment 4 (FIGS. 12 to 14) in each drawing. The same reference numerals are given to the parts to be marked.

Stirring device 81 of the digestion tank of this embodiment
The above-mentioned Example 1 (FIGS. 1 to 4) and Example 3 (FIG. 8).
Through FIG. 11).
That is, the stirring device 81 of the digestion tank of this embodiment is
A wide fixing extending radially obliquely rearward at three circumferential positions (three in the present embodiment, but not limited to this) on the outer periphery of the casing of the motor 37 of the submersible agitator 82. Tools 57B (similar to the fixtures of the fourth embodiment) are provided, the lower ends of the lifting bars 64 are fixed to the tips of these fixtures 57B, and a part of the front edge of each fixture 57B is fixed. It is set so as to be able to contact the upper end of the draft tube 2. Further, the upper end of the draft tube 2 is formed in a bell shape 53A with which the front edge portion of each fixture 57B can make line contact. Other configurations are the same as those of the above-described third and fourth embodiments.

In the digestion tank agitation device 81 of this embodiment, the procedure of setting the submersible agitator 82 (FIG. 15) and carrying in / out work at the time of inspection (FIG. 18) is the same as that of the above-mentioned third embodiment. Therefore, the description thereof will be omitted. In the digestion tank agitation device 81 of this embodiment, as in the case of the fourth embodiment, each of the wide fixtures 57B extending radially obliquely rearward is provided on the outer periphery of the casing of the motor 37 of the submersible agitator 82. Since a part of the front edge of each fixture 57B is set so as to be able to abut on the upper end of the draft tube 2, a submersible agitator 82 that is basically integrated with the lifting bar 64 and that is a stationary type submersible agitator 82 is provided. It can be placed inside the top of the draft tube. Therefore, the submersible agitator 82
There is no need to provide a tubular body or the like around which the draft tube 2 is introduced, and the device configuration can be simplified.
Further, each fixture 57B can be provided with a centering function, and the accuracy of the setting position of the submersible agitator 82 is improved.

Further, the upper end of the draft tube 2 is formed in a bell shape 53A capable of making line contact with the front edge of each fixing member 57B as in the case of the fourth embodiment.
By the synergistic effect of the centering action by the bell-shaped 53A of the draft tube 2 and the aligning action by the bell-shaped 53A of the draft tube 2, the accuracy of the setting position of the submersible agitator 82 integrated with the lifting bar can be further improved, and each fixture The contact area between 57B and the upper end of the draft tube can be increased, and the submersible stirrer 8 applied to the upper end of the draft tube
It is possible to disperse the load due to the weight of the lifting bar 64 and the lifting bar 64. Therefore, the installation state of the submersible stirrer 82 is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

[0062]

As described above, according to the first aspect of the present invention, the submersible stirrer can be installed only by inserting it into the draft tube from the inspection port provided on the outer wall of the tank directly above the draft tube. As a result, the stirrer can be installed easily and the burden on the outer wall of the tank directly above the draft tube can be reduced. Therefore, the present invention can be applied to an existing digestion tank whose top slab is thin or brittle. Further, since the inspection port is composed of a watertight pipe for sealing that projects into the upper space in the digestion tank, the inspection port can be water-sealed with the sludge in the digestion tank. Therefore, the inside of the digestion tank can be easily inspected without removing the flammable digestive gas filling the upper void, and the maintenance can be easily performed.

According to the invention of claim 2 of the present invention,
The inspection port consisting of a water sealing pipe was sealed from the internal space of the digestion tank between the inspection port and the draft tube, and was connected so that the guide pipe that serves as a guide for inserting and removing the submersible stirrer can be inserted and removed. By doing so, a guide pipe can be inserted when carrying in and out of the draft tube of the submersible agitator, and the inspection port and the draft tube are connected to form a single pipe from the draft tube to the inspection port. can do. Therefore, it is possible to smoothly carry in / out the submersible stirrer into / from the draft tube.

According to the invention of claim 3 of the present invention,
Since the inner peripheral surface of the guide pipe is set so as to be flush with the inner peripheral surface of the draft tube, a step is not generated in one pipe from the draft tube formed by inserting the guide pipe to the inspection port. Disappear. Therefore, when the submersible stirrer is carried in and out of the draft tube, there is no interference with the submersible stirrer, and it is possible to prevent an accident such as a collision with the inner cylinder step of the submersible stirrer.

According to the invention of claim 4 of the present invention,
In addition to installing guide bars that extend upward in multiple circumferential positions on the upper part of the draft tube, a plurality of slide plates that are guided by each guide bar are installed on the submersible agitator, and an inspection is provided on the outer wall of the tank directly above the draft tube. Since the submersible stirrer can be installed on the upper part of the draft tube from the mouth, each guide bar can have the rotation stopping function of the submersible stirrer. Further, even if the draft tube may be installed while being bent in the middle, the influence of this refraction can be avoided.

According to the invention of claim 5 of the present invention,
The motor and screw of the submersible stirrer are housed in a cylinder that is placed on the upper end of the draft tube and communicates with the draft tube, and each slide is attached through a plurality of radially extending fixtures provided on the outer circumference of the cylinder. Since the plate is attached, it is possible to form a single tube from the draft tube to the cylindrical body. Therefore, the submersible stirrer can be set simply by inserting the slide plate into the guide tube on the draft tube side, sliding the slide plate downward in that state, and placing the tubular body, that is, the submersible stirrer on the upper end of the draft tube. .

According to the invention of claim 6 of the present invention,
Provided on the outer periphery of the casing of the motor of the submersible stirrer are a plurality of fixtures extending in the radial direction toward the rear diagonally, and attaching each slide plate to these fixtures,
Since a part of the front edge of each fixture is set to be able to contact the upper end of the draft tube, the submersible stirrer can be arranged inside the upper part of the draft tube. Therefore, it is not necessary to provide a tubular body or the like around the submersible stirrer as an introduction path to the draft tube, and the device configuration can be simplified. Further, it becomes possible to give each fixture a centering function, and the accuracy of the setting position of the submersible stirrer is improved.

According to the invention of claim 7 of the present invention,
Since the upper end of the draft tube is formed in a bell shape so that the front edge of each fixture can make line contact, the synergistic effect of the centering action of each fixture and the bell-shaped centering action of the upper end of the draft tube allows The accuracy of the set position of the stirrer can be further improved. Furthermore, the contact area between the fixture and the upper end of the draft tube can be increased, and the load due to the weight of the submersible stirrer applied to the upper end of the draft tube can be dispersed. Therefore, the installation state of the submersible stirrer is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

According to the invention of claim 8 of the present invention,
Place a slide plate and a hanging piece for loading and unloading on the top of each lifting bar that fixed the submersible stirrer to the bottom,
Since multiple guide bars for guiding each slide plate are provided on the inner wall of the inspection port, it is easy to align each slide plate and each guide bar, and it is easy to carry in, carry out and install the submersible stirrer. Can be done smoothly.

Further, according to the invention of claim 9 of the present invention,
Place each hanging piece on the upper end of each lifting bar, and set the length of each lifting bar so that the upper end of each hanging piece faces the top wall of the inspection port with a slight gap when the submersible stirrer is installed. Since the submersible stirrer tries to levitate due to the upward reaction force during the downward flow operation, the hanging piece at the top of each lifting bar contacts the top wall of the inspection port. By doing so, each lifting bar can function as a stopper for preventing floating of the submersible agitator.

According to the invention of claim 10 of the present invention, the motor and the screw of the submersible stirrer are housed in the cylindrical body which is placed on the upper end of the draft tube and communicates with the draft tube. Since it is attached to each hoisting bar via a plurality of radially extending fixtures provided on the outer periphery, it can be formed into a single tube from the draft tube to the tubular body. For this reason, lift each lifting bar, insert the submersible stirrer that is fixed to the bottom of the bar into the inspection port, and lower it.In the middle, insert the slide plate into the guide bar on the inspection port side, and in that state, move downward. The submersible stirrer can be set simply by sliding and placing the tubular body, that is, the submersible stirrer on the upper end of the draft tube.

According to the eleventh aspect of the present invention, a plurality of fixtures extending radially in a diagonally rearward direction are provided on the outer periphery of the casing of the motor of the submersible stirrer.
Since each lifting bar was attached to these fixtures and part of the front edge of each fixture was set to be able to contact the upper end of the draft tube, the underwater stirrer integrated with the lifting bar was drafted. Can be placed inside the top of the tube. Therefore, it is not necessary to provide a tubular body or the like around the submersible stirrer as an introduction path to the draft tube, and the device configuration can be simplified. Further, it becomes possible to give each fixture a centering function, and the accuracy of the setting position of the submersible stirrer is improved.

According to the twelfth aspect of the present invention, since the upper end of the draft tube is formed in a bell shape so that the front edge of each fixing tool can make line contact, the fixing function of each fixing tool can be improved. The bell-shaped synergistic effect of the bell-shaped upper end of the draft tube can further improve the accuracy of the setting position of the submersible stirrer integrated with the lifting bar, and the contact area between the fixture and the upper end of the draft tube. Can be increased, and the load due to the weight of the submersible stirrer and each lifting bar on the upper end of the draft tube can be dispersed. Therefore, the installation state of the submersible stirrer is stable, and stress concentration due to the load on the upper end of the draft tube can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an agitating device for a digestion tank according to claims 1, 2, and 3 of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view of loading / unloading work of the agitator of FIG. 1 in / out of a draft tube.

FIG. 4 is a perspective view showing another example of the stirrer of FIG.

FIG. 5 is a vertical cross-sectional view showing an agitating device for a digestion tank according to claims 4 and 5 of the present invention.

6 is a sectional view taken along the line BB of FIG.

FIG. 7 is an explanatory view of loading / unloading work of the agitator of FIG. 5 into / out of the draft tube.

FIG. 8 is a vertical cross-sectional view showing a stirring device for a digestion tank according to claims 8, 9, and 10 of the present invention.

9 is a sectional view taken along the line CC of FIG.

10 is a sectional view taken along the line DD of FIG.

FIG. 11 is an explanatory view of the work of loading / unloading the inside and outside of the draft tube of the agitator of FIG.

FIG. 12 is a vertical cross-sectional view showing an agitating device for a digestion tank according to the fourth, sixth, and seventh inventions of the present invention.

13 is a sectional view taken along the line EE of FIG.

FIG. 14 is an explanatory view of the work of loading and unloading the draft tube of the stirrer of FIG. 12 in and out.

FIG. 15 is a vertical cross-sectional view showing a stirring device for a digestion tank according to claims 8, 9, 11, and 12 of the present invention.

16 is a sectional view taken along the line FF of FIG.

17 is a sectional view taken along the line GG in FIG.

FIG. 18 is an explanatory diagram of loading / unloading work of the agitator of FIG. 15 in / out of the draft tube.

FIG. 19 is a vertical sectional view showing an example of a conventional digestion tank.

FIG. 20 is an enlarged vertical sectional view showing details of the conventional mechanical stirring device of FIG.

FIG. 21 is a vertical cross-sectional view showing another example of a conventional digestion tank.

[Explanation of symbols]

 2 Draft Tube 2a Draft Tube Inner Surface 5 Sludge 8 Top Slab (Outer Wall of Tank) 14 Upper Void 32 Inspection Port 33, 52, 63, 72, 82 Submersible Stirrer 34 Water Seal Pipe 36 Blind Flange 37 Motor 46 Screw 47 Guide pipe 47a Inner peripheral surface of guide pipe 53 Flange (upper end of draft tube) 53A Bell 54,62 Guide bar 55 Cylindrical body 57, 57A, 57B Fixing tool 58, 58A, 65 Slide plate 64 Lifting bar 66 Connecting bar 67 Hanging piece

Claims (12)

[Claims] 1. A draft tube which is erected and fixed in a digestion tank with both ends open and is immersed in sludge; and a draft tube which is provided on the outer wall of the tank directly above the draft tube and projects into an upper void in the digestion tank. A stirring device for a digestion tank, comprising an inspection port formed of a watertight pipe that can be sealed, and an underwater agitator independently installed so as to be inserted into and removed from the draft tube through the inspection port. 2. A guide pipe, which serves as a guide for inserting and removing the submersible stirrer, is inserted into and removed from an inspection port formed of a water sealing pipe by sealing and connecting the inspection port and the draft tube from the space inside the digestion tank. The agitating device for a digestion tank according to claim 1, wherein the agitating device is configured freely. 3. The digestion tank stirring device according to claim 2, wherein the guide pipe is set such that an inner peripheral surface thereof is flush with an inner peripheral surface of the draft tube when the inspection port and the draft tube are connected. . 4. A draft tube which is vertically installed and fixed in a digestion tank with both ends open and is immersed in sludge, and a guide which is installed at a plurality of circumferential positions above the draft tube and extends upward. A bar, an inspection port formed on the outer wall of the tank just above the draft tube and formed of a watertight pipe that can be sealed and protrudes into an upper space in the digestion tank, and a plurality of slide plates guided by the guide bars. And an agitator for a digestion tank, comprising an underwater agitator independently installed above the draft tube through the inspection port. 5. The submersible stirrer has a motor and a screw mounted on the upper end of the draft tube and housed in a cylinder communicating with the draft tube, and extends in a radial direction provided on the outer circumference of the cylinder. 5. The digestion tank stirring device according to claim 4, wherein each slide plate is attached via a plurality of fixtures. 6. The submersible stirrer is attached to each slide plate via a plurality of fixing members provided on an outer periphery of a casing of a motor thereof and extending obliquely rearward in a radial direction. The agitating device for a digestion tank according to claim 4, wherein a part of the edge portion is set so as to be able to come into contact with the upper end of the draft tube. 7. The digestion tank stirring device according to claim 6, wherein the upper end of the draft tube is formed in a bell shape so that the front edge of each fixture can make line contact. 8. A draft tube that is vertically fixed in the digestion tank with both ends open and submerged in the sludge, and a draft tube that is provided on the outer wall of the tank directly above the draft tube and projects into the upper void in the digestion tank. Inspection port consisting of a watertight pipe that can be sealed, guide bars installed at a plurality of circumferential positions on the inner wall of the inspection port and extending in the vertical direction, and a slide plate guided by the guide bar at the top and for carrying in / out. A plurality of hoisting bars that are attached to each other and hang downward, and are attached to the lower part of each hoisting bar so as to fix the hoisting bars to each other, and through the inspection port An agitator for a digestion tank, which includes an underwater agitator independently installed above the draft tube. 9. Each hanging piece is arranged at the upper end of each hoisting bar, and the length of each hoisting bar is set so that the upper end of each hoisting piece is slightly smaller than the top wall of the inspection port when the submersible stirrer is installed. 9. The digestion tank stirring device according to claim 8, wherein the length is set to face each other with a gap. 10. The submersible stirrer has a motor and a screw mounted on the upper end of the draft tube and housed in a cylinder communicating with the draft tube, and extends in a radial direction provided on the outer circumference of the cylinder. The stirring device for a digestion tank according to claim 8 or 9, which is attached to each lifting bar via a plurality of fixtures. 11. The submersible stirrer is attached to each lifting bar via a plurality of fasteners provided on the outer periphery of the casing of the motor and extending obliquely rearward in the radial direction. The digestion tank stirring device according to claim 8 or 9, wherein a part of the front edge portion is set so as to be able to come into contact with the upper end of the draft tube. 12. The upper end of the draft tube is formed into a bell shape capable of making line contact with the front edge of each fixture.
1. A stirring device for a digestion tank according to 1.