JP2011031168A - Sludge digestion apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indirect heating sludge digestion apparatus whose equipment cost is lower than that of conventional apparatuses. <P>SOLUTION: An outer pipe 28 is disposed outside a draft tube 2 to form an outside passage between the draft tube 2 and the outer pipe 28. A heating medium introduction pipe 41 and a heating medium delivery pipe 42 are connected to the outer pipe 28. In a part where the outer pipe 28 is arranged, sludge passes through the inside of the draft tube 2 and a heating medium passes through the outside passage, thereby heating the sludge in the draft tube 2. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sludge digester used in a process of digesting sludge (anaerobic decomposition of organic matter) generated in a process such as sewage treatment.

When performing the process of digesting sludge in the sludge digestion tank, it is necessary to stir so that the sludge in the tank does not accumulate on the bottom and to heat the sludge in the tank to an appropriate temperature.
Regarding the method of stirring sludge in the digestion tank, for example, a draft tube (vertical tube) extending in the vertical direction is provided at the center of the digestion tank, and the sludge in the tank is guided into the draft tube with a stirrer installed in the draft tube. It is done to circulate.
In the example described in Patent Document 1, the screw blade of the screw pump is arranged at the upper end portion in the draft tube, and the motor for operating the rotating shaft is arranged outside the tank. And by the action | operation of a motor, the sludge in a tank is introduce | transduced in a draft tube from a lower end opening (or upper end opening), is derived | led-out from the upper end opening (or lower end opening), and is circulated.

As a method for heating the sludge in the digestion tank, for example, as described in Patent Document 2, a direct method in which a heat source is put in the tank and heated, and the sludge in the tank is taken out and returned to the tank. There is an indirect method in which a circulation pipe is provided and the sludge in the circulation pipe is heated by a heat exchanger.
For example, as shown in FIG. 3, the direct method is a method in which a blowing pipe 6 is provided in the upper part of the tank 1 in which the sludge 5 is put, and steam generated from boiler equipment or the like is blown into the sludge 5 in the tank 1. This method has a problem in that the sludge in the digestion tank is diluted with water by adding steam, and the sludge concentration decreases.

In FIG. 3, reference numeral 2 indicates a draft tube, reference numeral 31 indicates a rotating shaft of the screw pump, and reference numeral 32 indicates a motor part of the screw pump.
In the indirect method, for example, as shown in FIG. 4, a circulation path 7 for heating is provided separately from the draft tube 2 provided for stirring. In this example, a pair of horizontal pipes 71 and 72 that pass through the wall portion 11 of the tank 1 and are arranged from the inside of the tank to the outside of the tank, and a vertical pipe 73 that connects both the horizontal pipes outside the tank are arranged. A pump 74 is provided between the side horizontal pipe 72 and the vertical pipe 73, and the heat exchanger 4 is provided in a portion of the vertical pipe 73 between the pump 74 and the inlet side horizontal pipe 71.

  In the method of FIG. 4, since the sludge in the piping arranged outside the tank is heated by the heat exchanger, even when steam generated from boiler equipment or the like is used as the heat source of the heat exchanger, the steam itself is sludge. The sludge concentration in the digestion tank does not decrease. However, this method has a problem that the equipment cost is higher than the direct method.

Japanese Patent Publication No.59-46654 Japanese Patent Laid-Open No. 5-269596

  An object of the present invention is to introduce sludge in a digestion tank into a draft tube installed in the tank and circulate it so that stirring is performed and the sludge in the digestion tank is heated by an indirect method. And it is providing the thing whose installation cost is low compared with the conventional indirect heating type sludge digester.

In order to solve the above-mentioned problems, a sludge digesting apparatus of the present invention comprises a tank for containing sludge and a draft tube arranged in the tank, and guides and circulates the sludge in the tank into the draft tube. Thus, a sludge digesting apparatus for stirring the sludge in the tank is characterized in that the draft tube is provided with a double pipe structure part through which sludge passes inside and a heat medium passes outside.
In the sludge digesting apparatus of the present invention, the sludge is heated by the heat medium in the double tube structure portion of the draft tube provided for stirring the sludge, so that the heating is performed separately from the circulation path for stirring. Compared with a conventional indirectly heated sludge digester provided with a circulation path, the equipment cost can be kept low. Further, since the heated sludge is returned into the tank to form a stirring flow, the entire tank is efficiently heated.

  The sludge digester of the present invention is a sludge in which the sludge in the digestion tank is stirred by being guided and circulated in a draft tube disposed in the tank, and the sludge in the digestion tank is heated by an indirect method. Compared with the conventional indirect heating sludge digester, the equipment cost is low and the heating efficiency of the entire tank is high.

It is a schematic block diagram which shows the sludge digestion apparatus corresponded to embodiment of this invention. It is AA sectional drawing of FIG. It is a schematic block diagram which shows the conventional direct heating type sludge digester. It is a schematic block diagram which shows the conventional indirect heating type sludge digester.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic configuration diagram showing the sludge digesting apparatus of this embodiment, in which a tank for putting sludge is a cross-sectional view at the center in the depth direction. 2 is a cross-sectional view taken along the line AA in FIG.
As shown in FIG. 1, the sludge digester includes a tank 1 for containing sludge, a draft tube 2 disposed in the tank 1, and a screw pump 3.

The draft tube 2 is disposed along the vertical direction at the center of the tank 1, and a lower part thereof is fixed to the bottom 12 of the tank 1 by a support leg 15. Further, the upper portion of the draft tube 2 is fixed to the wall portion 11 of the tank 1 by the support arm 16.
The screw pump 3 includes a rotating shaft 31 and a motor unit 32, and a screw blade 31 a is attached to the tip of the rotating shaft 31. All of the screw blades 31 a are disposed in the upper opening 21 of the draft tube 2. The motor part 32 is attached to the lid part 13 of the tank 1 and arranged outside the tank 1.
Outside the draft tube 2, an outer tube 28 is arranged in a range below the tip of the rotary shaft 31 arranged inside. Thereby, as shown in FIG. 2, an outer flow path 20 is formed between the draft tube 2 and the outer tube 28. Both ends of the outer channel 20 are closed.

In addition, a heat medium introduction tube 41 is connected to the lower end portion of the outer tube 28, and a heat medium outlet tube 42 is connected to the upper end portion. The heat medium introduction pipe 41 and the heat medium lead-out pipe 42 are disposed horizontally in the tank 1, and each end penetrates the wall 11 of the tank 1 and reaches the outside.
Therefore, the portion of the draft tube 2 where the outer tube 28 is disposed has a double-pipe structure that allows sludge to pass through the draft tube 2 and heat medium to pass through the outer flow path 20.

In the sludge digestion apparatus of this embodiment, the sludge 5 in the tank 1 is introduced into the draft tube 2 from the upper end opening and is circulated by being led out from the lower end opening by operating the screw pump 3. Thereby, the sludge 5 in the tank 1 is stirred. Further, the sludge introduced into the draft tube 2 is heated by the heat medium passing through the outer flow path 20 when passing through the double pipe structure.
According to the sludge digestion apparatus of this embodiment, since the sludge is heated by the heat medium in the double tube structure portion of the draft tube 2 provided for stirring the sludge, for the stirring as shown in FIG. Compared with a conventional indirectly heated sludge digester, which is provided with a circulation path 7 for heating separately from the draft tube 2, the equipment cost can be kept low. Moreover, since the sludge heated by the double pipe structure part of the draft tube 2 is returned in the tank 1 and forms a stirring flow, the sludge 5 of the whole tank 1 is heated efficiently.

DESCRIPTION OF SYMBOLS 1 Tank 11 Wall part 12 Bottom part 13 Cover part 15 Support leg 16 Support arm 2 Draft tube 20 Outer flow path 28 Outer pipe 3 Screw pump 31 Rotating shaft 31a Screw blade 32 Motor part 41 Heat medium introduction pipe 42 Heat medium outlet pipe 5 Sludge 6 Blowing pipe 7 Circulation path 71 for heating Horizontal pipe 72 Horizontal pipe 73 Vertical pipe 74 Pump 81 Branch pipe 82 Branch pipe

Claims (1)

A tank for containing sludge, and a draft tube arranged in the tank,
A sludge digester that stirs the sludge in the tank by introducing and circulating the sludge in the tank into the draft tube,
A sludge digesting apparatus, wherein the draft tube is provided with a double pipe structure part through which sludge passes inside and a heat medium passes outside.

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