JP2011031166A - 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: The sludge digestion apparatus includes a tank 1 storing sludge, a sludge circulation path 2 disposed so as to extend over the inside and the outside of the tank 1, a screw pump 3, and a heat exchanger 4. The circulation path 2 has a first horizontal pipe and a second horizontal pipe 26 penetrating the tank wall and extending from the inside to the outside of the tank 1. The heat exchanger 4 for heating the sludge in the circulation path 2 is provided at a part of the horizontal pipes arranged outside the tank 1. <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 the sludge in the digestion tank, the following Patent Document 1 describes that the sludge in the digestion tank is guided into the circulation path by a pump disposed outside the tank and returned to the digestion tank. . The circulation path includes a pair of vertical pipes arranged in the tank and extending vertically, a pair of horizontal pipes connected to the vertical pipes and extending through the tank wall from the inside of the tank to the outside of the tank, and both horizontal pipes Are connected to the outside of the tank, and a pump is installed in the U-shaped tube.

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. 5, 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 addition, in FIG. 5, the code | symbol 2 shows the circulation path provided for stirring. This circulation path 2 is arranged over the inside and outside of the tank 1 and has a first vertical pipe 21 that opens upward and a second vertical pipe 24 that opens downward. Further, a screw pump 3 is provided in a portion of the circulation path 2 disposed outside the tank 1.
In the indirect method, for example, as shown in FIG. 6, a circulation path 7 for heating is provided separately from the circulation path 2 provided for stirring. In this example, a pair of horizontal pipes 71 and 72 arranged from the inside of the tank to the outside of the tank through the tank wall 11 and a vertical pipe 73 connecting both the horizontal pipes outside the tank are arranged, A pump 74 is provided between the 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. 6, since the sludge in the pipes arranged outside the tank is heated by a heat exchanger, even when steam generated from boiler equipment or the like is used as a heat source for the heat exchanger, the steam itself is sludge. The sludge concentration in the digester does not decrease. However, this method has a problem that the equipment cost is higher than the direct method.

Japanese Patent Laid-Open No. 8-173992 Japanese Patent Laid-Open No. 5-269596

  The object of the present invention is to stir the sludge in the digestion tank by introducing it into a circulation path arranged inside and outside the tank and circulating it, and heating the sludge in the digestion tank is an indirect method. An object of the present invention is to provide a sludge digester to be performed, which has a lower equipment cost as compared with a conventional indirectly heated sludge digester.

  In order to solve the above-mentioned problems, a sludge digesting apparatus according to the present invention includes a tank for containing sludge, a first vertical pipe disposed in the tank and opened on the upper side, and a first pipe disposed in the tank and opened on the lower side. Two vertical pipes, first and second horizontal pipes connected to the first and second vertical pipes and extending through the tank wall from the inside of the tank to the outside of the tank, and the first and second outside the tank, A U-shaped pipe connecting a second horizontal pipe; and a pump installed in the U-shaped pipe; the first and second vertical pipes; the first and second horizontal pipes; And the U-shaped pipe, and the sludge in the tank is guided and circulated in a circulation path having one of the first and second vertical pipes as an inlet and the other as an outlet. A heat exchanger that heats the sludge in the circulation path in a portion disposed outside the tank of the first and second horizontal pipes. And wherein the digit.

  In the sludge digestion apparatus of this invention, since the heat exchanger for heating sludge is provided in the 1st and 2nd horizontal pipe which comprises the circulation path provided in order to stir sludge, for stirring Compared with the conventional indirect heating sludge digester that provides a circulation path for heating separately from the 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.

  In the sludge digester of the present invention, stirring is performed by guiding the sludge in the digestion tank to the circulation path arranged outside the tank and outside the tank, and the sludge in the digestion tank is heated indirectly. It is a sludge digestion apparatus performed by the method, Comprising: Equipment cost is low compared with the conventional indirect heating type sludge digestion apparatus, and the heating efficiency of the whole tank becomes high.

It is a schematic block diagram which shows the sludge digestion apparatus corresponded to 1st Embodiment of this invention. It is the elements on larger scale of FIG. It is a figure which shows a part of sludge digestion apparatus corresponded to 2nd Embodiment of this invention, Comprising: It is a figure corresponding to the elements on larger scale of FIG. It is a figure which shows a part of sludge digestion apparatus corresponded to 3rd Embodiment of this invention, Comprising: It is a figure corresponding to the elements on larger scale 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 the first embodiment, in which a tank for putting sludge is a cross-sectional view at the center in the depth direction. FIG. 2 is a partially enlarged view of FIG. 1 and shows a part outside the tank and a part where the horizontal pipe penetrates the tank wall.
As shown in these drawings, the sludge digester of the first embodiment includes a tank 1 for containing sludge, a sludge circulation path 2 arranged inside and outside the tank 1, a screw pump 3, and a heat pump. And an exchanger 4.

The circulation path 2 is arranged inside the tank 1 and has a first vertical pipe 21 opened on the upper side, and a first diagonal pipe 22 arranged inside the tank 1 and extending obliquely downward from the first vertical pipe 21. And a first horizontal tube 23 extending horizontally from the oblique tube 22 inside the tank 1 and penetrating the tank wall 11 of the tank 1 to reach the outside of the tank 1.
The circulation path 2 is also arranged in the tank 1 and has a second vertical pipe 24 opened on the lower side, and a second diagonal pipe arranged in the tank 1 and extending obliquely upward from the second vertical pipe 24. A pipe 25 and a second horizontal pipe 26 extending horizontally from the oblique pipe 25 inside the tank 1 and penetrating the tank wall 11 of the tank 1 to reach the outside of the tank 1 are provided. The second horizontal tube 26 is disposed at the same height as the first horizontal tube 23.

The circulation path 2 further includes a U-shaped tube 27 that connects the first horizontal tube 23 and the second horizontal tube 26 outside the tank 1. The first horizontal tube 23, the second horizontal tube 26, and the U-shaped tube 27 are arranged in the same horizontal plane.
A rotating shaft 31 with screw blades that constitutes the screw pump 3 is disposed in the U-shaped tube 27. This screw pump 3 is a reversible type, and the direction of flow changes in the direction of arrow A and the opposite direction according to the direction of rotation of the rotary shaft 31, but the performance does not change.

The heat exchanger 4 is installed in a portion of the first horizontal tube 23 and the second horizontal tube 26 that is disposed outside the tank 1.
The heat exchanger 4 has a single heat source circulation pipe, and the heat transfer pipe into which the sludge is put is a first part 41 for the first horizontal pipe 23 and a second part 42 for the second horizontal pipe 26. It is divided into and. And while the steam which is a heat source is introduced from the introduction pipe 43 of the heat exchanger 4 and led out from the outlet pipe 44, the heat transfer pipe and steam into which the sludge in the first horizontal pipe 23 enters in the first portion 41 The heat exchange tube and the steam are brought into contact with each other and the heat transfer tube into which the sludge in the second horizontal tube 26 enters is in contact with the second portion 42 to perform heat exchange. The heat exchanger 4 has the same performance even if the direction of the sludge flow in the first and second horizontal tubes 23 and 26 is changed.

  In the sludge digesting apparatus of this embodiment, the sludge 5 in the tank 1 is circulated from the first vertical pipe 21 to the circulation path 2 by operating the screw pump 3 so that the flow direction is in the direction of arrow A in FIG. The first oblique tube 22, the first horizontal tube 23, the U-shaped tube 27, the second horizontal tube 26, and the second oblique tube 22 are moved in this order, and from the second vertical tube 24 Returned to the tank 1. Thereby, the sludge 5 in the tank 1 is stirred. The sludge introduced into the circulation path 2 is heated by the first portion 41 of the heat exchanger 4 when passing through the first horizontal pipe 23, passes through the U-shaped pipe 27, and then passes through the second horizontal pipe 23. As it passes through the tube 26, it is heated in the second part 42 of the heat exchanger 4.

When the screw pump 3 is operated so that the flow direction is opposite to the arrow A in FIG. 2, the sludge 5 in the tank 1 is guided into the circulation path 2 from the second vertical pipe 24. Then, it moves in the circulation system path 2 in the reverse order to the above, and is returned from the first vertical pipe 21 into the tank 1.
According to the sludge digester of this embodiment, the heat exchanger 4 for heating the sludge is provided in the first and second horizontal pipes 23 and 26 constituting the circulation path 2 provided for stirring the sludge. Therefore, as shown in FIG. 6, the equipment cost is lower than that of a conventional indirect heating sludge digester that is provided with a circulation path 7 for heating separately from the circulation path 2 for stirring. Can be suppressed. Moreover, since the sludge heated by the circulation path 2 is returned in the tank 1 and forms stirring flow, the sludge 5 of the whole tank 1 is heated efficiently.

  The sludge digestion apparatus of 2nd Embodiment is the same structure as the sludge digestion apparatus of 1st Embodiment except the method of providing the heat exchanger 4. FIG. In this embodiment, as shown in FIG. 3, the independent heat exchanger 4 is provided in the part arrange | positioned outside the tank 1 of the 1st horizontal pipe 23 and the 2nd horizontal pipe 26, respectively. Thereby, in 2nd Embodiment, in each heat exchanger 4, while the vapor | steam which is a heat source is introduce | transduced from the introductory pipe 43, and is derived | led-out from the derivation | leading-out pipe 44, the heat exchanger tube into which the sludge in each horizontal pipe 23 and 26 enters. And steam contact to exchange heat.

  The sludge digestion apparatus of 3rd Embodiment is the same structure as the sludge digestion apparatus of 1st Embodiment except the method of providing the heat exchanger 4. FIG. In this embodiment, the heat exchanger 4 is not provided directly on the first horizontal pipe 23 and the second horizontal pipe 26, but as shown in FIG. 4, the first horizontal pipe 23 and the second horizontal pipe 26 The heat exchanger 4 is connected by branch pipes 81 and 82. The heat exchanger 4 is disposed between the first horizontal tube 23 and the second horizontal tube 26 that are disposed outside the tank 1.

  When the screw pump 3 is operated so that the flow direction becomes the arrow A in FIG. 4 (the rotating shaft 31 is rotated), a differential pressure is generated between the first horizontal tube 23 and the second horizontal tube 26. Then, the sludge immediately after leaving the U-shaped tube 27 and entering the second horizontal tube 26 is introduced from the branch tube 82 into the heat transfer tube of the heat exchanger 4, and steam as a heat source is introduced from the introduction tube 43. While being led out from the lead-out pipe 44, the heat transfer pipe and the steam come into contact with each other to perform heat exchange. The heat-exchanged sludge enters the branch pipe 81 on the second horizontal pipe 26 side, and returns from the second horizontal pipe 26 to the U-shaped pipe 27.

DESCRIPTION OF SYMBOLS 1 Tank 2 Circulation path | route 21 1st vertical pipe 22 1st diagonal pipe 23 1st horizontal pipe 24 2nd vertical pipe 25 2nd diagonal pipe 26 2nd horizontal pipe 27 U-shaped pipe 3 Screw pump 31 Rotating shaft 4 Heat exchanger 41 First part 42 Second part 43 Steam introduction pipe 44 Steam outlet pipe 5 Sludge 6 Blow pipe 7 Circulation path for heating 71 Horizontal pipe 72 Horizontal pipe 73 Vertical pipe 74 Pump 81 Branch pipe 82 Branch pipe

Claims (1)

A tank for sludge,
A first vertical pipe disposed in the tank and having an upper opening;
A second vertical pipe disposed in the tank and having an open lower side;
First and second horizontal pipes connected to the first and second vertical pipes respectively and extending through the tank wall from the inside of the tank to the outside of the tank;
A U-shaped tube connecting the first and second horizontal tubes outside the tank;
A pump installed in the U-shaped tube;
With
The first and second vertical pipes, the first and second horizontal pipes, and the U-shaped pipe are included, and one of the first and second vertical pipes is an inlet and the other is an outlet. A sludge digester that stirs the sludge in the tank by introducing and circulating the sludge in the tank in the circulation path,
A sludge digesting apparatus, wherein a heat exchanger for heating the sludge in the circulation path is provided in a portion of the first and second horizontal tubes arranged outside the tank.

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