JP5623854B2 - Methane fermentation purification system - Google Patents

Description

  The present invention relates to a methane fermentation and purification system, and more particularly, to a methane fermentation and purification system that can be operated at low cost, and that can obtain methane gas with a high concentration and low hydrogen sulfide.

  In recent years, disposal of organic waste such as manure in the livestock industry has become a major problem. That is, by not disposing of septic tank equipment or the like and discarding manure or the like into the environment, bad odors are generated or livestock pollution such as river, groundwater, marine pollution, etc. is adversely affected. In addition, other types of organic waste such as garbage are currently incinerated and landfilled. However, there are problems with carbon dioxide generation and landfill sites, and the development of effective treatment methods is required. It has been.

  Therefore, in recent years, attention has been focused on methane fermentation using organic waste such as manure and garbage under anaerobic conditions and using the generated methane gas as fuel. This methane fermentation can be said to have the greatest feature that heat energy can be extracted as a combustible gas from a liquid or mud organic waste having a high water content by a simple process. Moreover, it can be said that it is an energy-saving process because it does not require electric power for aeration as in the activated sludge method, and the produced gas is recovered as fuel gas.

  Conventionally, this septic tank using methane fermentation is used in sewage treatment plants in Naha, Nago, Nishihara, etc. in Okinawa alone, but these have high construction costs, high running costs, complicated equipment, There are drawbacks such as difficulty in maintenance, and it was not available to general livestock farmers or small businesses, regardless of public facilities.

  The present inventor previously proposed several anaerobic methane fermentation septic tanks as an inexpensive and easy-to-maintain manure processing facility that can be borne by general livestock farmers (Patent Document 1). Among these methane fermentation septic tanks, the one of Patent Document 1 is intended to destroy and remove the scum layer generated by using the intermittent jet power of methane accumulated in the methane fermentation tank. It also had the feature of not requiring power. However, although this can be operated at a low cost, it is still not sufficient in terms of smooth circulation of the processing liquid, and further improvement has been demanded.

  In addition, the present inventor separately uses the power of methane gas generated by methane fermentation, as shown in FIG. 1, and a fermentation purification apparatus that smoothly circulates the processed material in the methane fermentation tank without requiring power means. Has been invented (Japanese Patent Application No. 2009-215125). In this case, when the pressure of the generated gas is low, desulfurization of hydrogen sulfide cannot be performed well, or when the amount of processed material is small, the treatment liquid is circulated. There was still room for improvement, such as not going well.

  That is, the methane fermentation purification apparatus 1 in FIG. 1 is configured such that the bubbles of methane gas generated in the methane fermentation tank 2 are in a mixture with a processed product (hereinafter referred to as “methane-containing processed product”). Begin to surface. And since the methane fermentation tank upper part 5 is formed so that the outlet pipe connection part 6 may become the highest position, all the methane containing processed materials will gather to the outlet pipe connection part 6. FIG.

  Since the outlet pipe connecting portion 6 is connected to the outlet pipe 3 extending obliquely upward and the subsequent return pipe 4, the methane-containing product further passes upward through the outlet pipe 3. It moves and reaches the methane gas separation part 10 provided in the upper part of the return pipe 4, and is divided into methane gas and processed material.

  The methane gas thus separated in the methane gas separation unit 10 is supplied as fuel or the like through a methane gas pipe (not shown). On the other hand, the treated product from which methane gas has been separated has a return pipe due to an increase in specific gravity due to the disappearance of methane gas bubbles and the pressure of the methane-containing treated product that continuously moves upward through the outlet pipe 3. 4 flows downward and returns to the methane fermentation tank 2 through the return pipe outlet 8.

  Since such a mechanism works, in the said methane fermentation purification apparatus, it becomes possible to circulate and stir a processed material, without requiring external power. Furthermore, when manure or the like is introduced from the processed material introduction port 9, since it flows down the return pipe 4, the force for further circulation and stirring is further increased by this force. In particular, when the processed material inlet 9 is provided in the methane gas separation unit 10, even if scum is generated on the processed material, the processed material is returned to the return pipe 4 and returned to the methane fermentation tank. Is.

  However, in the apparatus of FIG. 1, since the methane gas generated in the methane fermentation tank 2 is supplied as it is from the methane gas separation unit 10 to the methane gas pipe, the pressure is low, and the generated gas contains about 0.2%. There was a problem that it was difficult to remove the hydrogen sulfide gas. Further, as described above, the methane-containing processed product moves upward through the outlet pipe 3 and is transported to the methane gas separation unit 10 provided at the upper part of the return pipe 4. If the amount is too small, the upward flow in the outlet pipe 3 is weak, and there is a possibility that the circulation will not go smoothly. Therefore, it is necessary to use a methane fermentation tank of a certain size, and it is difficult to reduce the size. There was also.

JP-A-11-197696

  Therefore, while using a methane fermentation septic tank that can be operated at a low cost as shown in FIG. 1, the treatment liquid can be smoothly circulated and efficiently fermented with methane even if the amount of treatment is small. An object of the present invention is to provide a methane fermentation and purification system capable of desulfurizing methane and supplying it with a certain high pressure.

  As a result of earnest research to solve the problem of the methane fermentation septic tank shown in FIG. 1, the present inventor increases the concentration of methane gas if the methane gas separated in the methane gas separation unit is returned to the fermenter again. In addition, the present inventors have found that the processed product in the methane fermentation tank can be circulated more smoothly and completed the present invention.

That is, the present invention
(1) A methane fermentation tank, a lead-out pipe that guides the methane gas produced in the methane fermentation tank together with the processed product to the methane gas separation unit, and a return pipe that returns the processed product after separating the methane gas to the methane fermentation tank. And the upper surface of the methane fermenter is formed so that the outlet pipe connecting portion is at the highest position, and the outlet pipe is connected to the return pipe at least at a position higher than the outlet pipe connecting portion, The upper part of the return pipe forms a methane gas separation part,
A lower part of the return pipe communicates with the methane fermentation tank, and a methane fermentation and purification apparatus in which a process input is provided at the upper part of the methane gas separation unit or the return pipe;
(2) An air supply device that communicates with the methane gas separation part of the methane fermentation and purification device through a methane gas pipe and supplies methane gas;
(3) provided in the methane fermentation tank, communicated with the air supply device, and blown pipe for injecting methane gas into the methane fermentation tank; and (4) a methane gas extraction section provided in any of the methane gas pipes. This is a methane fermentation and purification system.

  Moreover, this invention is the said methane fermentation purification system which provided the desulfurization apparatus between the methane gas separation part and the air supply apparatus, or behind the air supply apparatus.

  Furthermore, the present invention provides the methane fermentation tank, wherein the top surface of the methane fermentation tank has a conical or quadrangular pyramid shape with the lead-out pipe connection portion at the top, or a single-flow roof that rises toward the lead-out pipe connection portion. Fermentation purification system.

  The methane fermentation purification system of the present invention can smoothly circulate the treatment liquid in an anaerobic state in an anaerobic state without causing generation of scum, and can obtain high-concentration methane with a low hydrogen sulfide content. It can be done.

  Moreover, if a desulfurization apparatus is installed in the front | former stage or back | latter stage of an air supply apparatus of the said system, methane gas with higher purity can be obtained and can be utilized for various purposes.

  Therefore, the methane fermentation and purification system according to the present invention can carry out the anaerobic methane fermentation and purification treatment of organic waste more easily, at low cost and with energy saving.

It is drawing which showed typically one embodiment of the methane fermentation purification apparatus which this inventor developed previously. It is drawing which showed typically one embodiment of the methane fermentation purification apparatus used with the methane fermentation purification system of this invention. It is drawing which shows the outline | summary of the methane fermentation purification system which is 1 aspect of this invention. It is drawing which shows the outline | summary of the methane fermentation purification system which is another aspect of this invention.

  Hereinafter, the present invention will be described together with drawings showing some embodiments of the methane fermentation and purification system of the present invention.

  FIG. 2 is a drawing schematically showing a basic configuration of a methane fermentation and purification apparatus used in the methane fermentation and purification system of the present invention. In the figure, 1 is a methane fermentation purification device, 2 is a methane fermentation tank, 3 is a discharge pipe, 4 is a return pipe, 5 is a top surface of the methane fermentation tank, 6 is a discharge pipe connection section, 7 is a return pipe connection section, and 8 is a return pipe. Pipe outlet, 9 treated product inlet, 10 is a methane gas separation unit, 11 is a sludge discharge pipe, 24 is a blow pipe, and 25a and 25c are methane pipes, respectively.

  As shown in FIG. 2, the methane fermentation and purification apparatus 1 of the present invention includes a methane fermentation tank 2, a lead-out pipe 3, a return pipe 4, and a blow-in pipe 24. Among these, the methane fermentation tank 2 is formed so that the upper surface 5 thereof is at the highest position in the outlet pipe connecting portion 6. Specifically, the upper surface 5 of the methane fermentation tank may have a conical or quadrangular pyramid shape with the outlet pipe connecting portion 6 as an apex, or a single-flow roof shape toward the outlet pipe connecting portion 6. .

  The outlet pipe 3 extending from the outlet pipe connecting portion 6 is connected to the return pipe 4 at least at a position higher than the outlet pipe connecting portion 6. That is, the outlet pipe 3 extends obliquely upward, and the outlet pipe 3 is connected to the return pipe 4 at the return pipe connecting portion 7.

  The return pipe 4 is a pipe provided substantially vertically. A methane gas separation unit 10 is formed in the upper part of the return pipe 4. The lower part penetrates the fermenter upper part 5 and communicates with the methane fermenter 2 at the return pipe outlet 8. To do. The methane gas separation unit 10 is connected to a methane gas pipe 25a.

  Further, a processed material inlet 9 is provided at the upper part of the return pipe 4, from which manure, raw garbage, etc. can be input, and from the return pipe 4 through the return pipe outlet 8 in the methane fermentation tank 2. To supply. The processed material inlet 9 may be located anywhere as long as the processed material does not flow out of the processed material input port 9. For example, as shown in FIG. 2, the treatment object inlet 9 and the methane gas separation unit 10 can be provided at the same position. In this case, for example, the U-tube 12 or the like is used to separate them, It is desirable to prevent methane gas from leaking.

  FIG. 3 is a drawing showing an outline of one aspect of a methane fermentation and purification system using the methane fermentation and purification tank 1. In the figure, 1, 3, 4, 9 and 10 are the same as above, 21 is an air supply device, 22 is a desulfurization device, 23 is a methane gas outlet, 24 is a blow-in tube, 25 is a methane gas pipe, and 26 is Each valve is shown.

  In the system of FIG. 3, methane gas that has flowed from the methane gas separation unit 10 to the methane gas pipe 25a flows into, for example, the desulfurization device 22 of FIG. 3, and hydrogen sulfide is removed. The desulfurization device 22 may be any device as long as it can remove hydrogen sulfide, and examples thereof include a desulfurization device using iron hydroxide or zeolite, a device for washing methane gas with water or lime water, and the like. . Note that hydrogen sulfide is removed to some extent by blowing methane gas, which will be described later, and bringing it into contact with the processed material. Therefore, if the methane gas does not require a very high degree of purification, the desulfurization device 22 can be omitted.

  Next, the methane gas purified by the desulfurization device 22 flows into the air supply device 21 through the methane gas pipe 25b by the suction force of the air supply device 21, and the blowing pipe from the methane gas pipe 25c by the force of the air supply device 21. 24 is blown into the methane fermentation septic tank 1. As this air supply device 21, a general blower or the like can be used. In addition, since the blow pipe 24 has a large number of holes and protrudes into the processing object, the methane gas sent through the methane gas pipe 25c by the air supply device 21 is released into the processing object in a bubble state. In combination with the methane bubbles generated in the original methane fermentation, a strong upward flow can be formed. The blowing tube 24 may be a rod-shaped tube having a bubble discharge hole at the tip, but preferably has a ring shape at the tip and provided with a bubble discharge hole.

  In the system of FIG. 3, a methane gas outlet 23 is installed in a pipe between the desulfurization device 22 and the air supply device 21 via a valve 26, and a pipe 25 a, the desulfurization device 22, a pipe 25 b, an air supply After the concentration of the methane gas circulating with the apparatus 21 and the blow-in pipe 24 becomes high to some extent, the methane gas can be taken out from this and used.

  FIG. 4 is a drawing showing an outline of another aspect of the methane fermentation purification system of the present invention. Each symbol in the figure is the same as described above. In the methane fermentation and purification system of this embodiment, the positions of the air supply device 21 and the desulfurization device 22 are basically different from those in FIG. That is, in the methane fermentation and purification system of this aspect, the methane gas generated in the methane fermentation and purification tank 1 is sent directly from the methane gas separation unit 10 to the air supply device 21 through the methane gas pipe 25d.

  And the methane gas in this air supply apparatus 21 is sent into the desulfurization apparatus 22 through the methane gas piping 25e by the force, and is desulfurized. The desulfurized methane gas is discharged into the treatment object in the form of bubbles from the blowing pipe 24 through the methane gas pipe 25f.

  4, the methane gas generated in the methane fermentation tank 2 can be circulated in the system of the embodiment of FIG. 4 as well, but the positions of the air supply device 21 and the desulfurization device 22 are the same. Therefore, since the discharge pressure of the methane gas blown from the blow pipe 24 becomes low, it is preferable to provide this at the upper part as much as possible. For example, it is preferable to provide the blowing pipe 24 in the vicinity of the upper part 5 of the methane fermentation tank 2 so that it can be released as bubbles even at a low pressure.

  The position of the blowing pipe 24 is preferably separated from the outlet pipe connecting portion 6 so that the blown methane gas moves as long as possible to improve the overall circulation. For example, when the upper surface 5 of the methane fermentation tank 2 has the outlet pipe connection portion 6 as the apex and is in the shape of a single-flow roof toward this, the outlet pipe connection portion 6 and the return pipe 4 are in the methane fermentation tank 2. The outlet pipe connection portion 6 is provided at the highest position on the upper surface 5 while the return pipe 4 is provided at the lowest position in the vicinity of the upper surface 5 or in the vicinity thereof. However, the blowing pipe 24 is also provided at a position close to the return pipe 4 so that the methane gas is widely discharged into the processed material and finally collected at the outlet pipe connecting portion 6. Is preferred. Further, in FIG. 4, the methane gas outlet 23 is installed in the pipe before the air supply device 21 via the valve 26, but the present invention is not limited to this, and a methane gas extraction port may be provided after the air supply device 21. good.

  In the system of the present invention, the reason why a certain level of methane gas can be supplied that has been sufficiently methane-fermented while being low in power and has been stably desulfurized is described as follows by referring to FIG. is there. That is, the bubbles of methane gas generated in the methane fermentation tank 2 start to float upward due to the buoyancy in the state of a mixture with the treated product (hereinafter referred to as “methane-containing treated product”). Since the methane gas that has already been generated is blown into the processed material through the blowing pipe 24, this force is also applied, and the methane-containing processed material moves upward with a stronger force.

  And since the upper part 5 of the methane fermentation tank 2 used by this invention system is formed so that the outlet pipe connection part 6 may become the highest position as mentioned above, all the methane-containing processed materials go to the outlet pipe connection part 6. Will be gathered.

  As shown in FIG. 2, the outlet pipe connecting portion 6 is connected to the outlet pipe 3 extending obliquely upward and the return pipe 4 that follows the outlet pipe 3. It moves upward with a strong force, reaches the methane gas separation unit 10 provided at the upper part of the return pipe 4, and is separated into methane gas and processed material.

  The methane gas thus separated in the methane gas separation unit 10 starts to circulate from the pipe 25a to the blow-in pipe 24 by the suction force of the air supply device 21 via the pipes 25a and 25b.

  On the other hand, the treated product from which methane gas has been separated has a return pipe due to an increase in specific gravity due to the disappearance of methane gas bubbles and the pressure of the methane-containing treated product that continuously moves upward through the outlet pipe 3. 4 flows downward and returns to the methane fermentation tank 2 through the return pipe outlet 8.

  Since such a mechanism works, in the methane fermentation and purification apparatus of the present invention, the processed product can be circulated and stirred with a small amount of external power. Furthermore, when manure or the like is introduced from the processed material introduction port 9, they flow down the return pipe 4, so that circulation and agitation can be achieved by this force. In particular, as shown in FIG. 2, in the case where the methane gas separation unit 10 is provided with the processed material inlet 9, even if scum is generated on the processed material, it is returned to the return pipe 4 by the processed material that is input. It will return to the tank.

  In the system of FIG. 4 as well, the methane gas separated in the methane gas separation unit 10 passes through the desulfurization device 22 by the suction force of the air supply device 21 through the pipe 25d, and is then blown into the blow-in pipe 24 to start circulation. Except for this, it is almost the same as the system of FIG.

  In addition, the system of this invention needs to be a structure sealed as a whole. That is, if air flows in from either, it is mixed in methane gas, and when it is blown into the methane fermentation tank, anaerobic conditions cannot be maintained. Therefore, the methane fermentation tank 2 used in the present system is preferably a sealed structure in which air or the like does not flow, such as an iron tank or concrete.

  Moreover, it is preferable to provide the sludge discharge pipe 11 for taking out the solid residue in fermentation in the lower part of the methane fermenter 2. Furthermore, when the methane generator of the present invention is used in a cold region, heating is preferable. In this case, the heating device may be installed in the outlet tube 3 or the methane fermentation tank 2, but it is structurally simple and preferable to install the heating device in the outlet tube 3.

  According to the present invention configured as described above, the processed material is always treated using the buoyancy of the generated methane gas bubbles and the buoyancy of the methane gas bubbles sent by the air supply device 21, and the processed product is always returned to the methane fermentation tank 2, the lead-out pipe 3, and the return. Since it circulates between the pipes 4, it is possible to stir with less power. And since the methane gas which blows in does not contain oxygen unlike air, it does not disturb the anaerobic conditions of methane fermentation.

  Moreover, since the generated methane gas is circulated from the pipe 25 to the blow-in pipe 24 based on the suction force of the air supply device 21 from the methane gas separation unit 10, the concentration can be increased and the pressure can be increased. It will be stable and easy to use. In particular, high-purity methane gas from which hydrogen sulfide has been removed, which is obtained by the system of the present invention provided with the desulfurization apparatus 22, is widely used for general purposes.

  Currently, in livestock farmers, etc., the mainstream is to separate the feces and urine of livestock, compost the manure, and the activated sewage to treat the urine, but in the methane fermentation septic tank of the present invention, fecal urine can be mixed, Maintenance costs can be significantly reduced. Further, in the methane fermentation apparatus of the present invention, a special stirring device or the like is not used, and only an air supply device is used. Therefore, the construction cost is also low, so that the economy is high and extremely economical for livestock farmers. Is something.

  In addition, the present invention is not limited to this, and can treat effluent from small-scale breweries, leftovers from restaurants, etc., or raw garbage from garbage disposal plants to obtain methane gas, so that it can be widely used in various business establishments.

DESCRIPTION OF SYMBOLS 1 ...... Methane fermentation purification apparatus 2 ...... Methane fermentation tank 3 ...... Outlet pipe 4 ...... Return pipe 5 ...... Methane fermentation tank upper surface 6 ...... Outlet pipe connection part 7 ...... Return pipe connection part 8 ...... Return pipe outlet 9…… Processed material inlet 10…… Methane gas separation part 11…… Sludge discharge pipe 12…… U-shaped pipe 21…… Air supply device 22…… Desulfurization device 23…… Methane gas outlet 24…… Blowing tube 25… … Methane gas piping 26…… valve

Claims (5)

(1) A methane fermentation tank, a lead-out pipe that guides the methane gas produced in the methane fermentation tank together with the processed product to the methane gas separation unit, and a return pipe that returns the processed product after separating the methane gas to the methane fermentation tank. And the upper surface of the methane fermenter is formed so that the outlet pipe connecting portion is at the highest position, and the outlet pipe is connected to the return pipe at least at a position higher than the outlet pipe connecting portion, The upper part of the return pipe forms a methane gas separation part,
A lower part of the return pipe communicates with the methane fermentation tank, and a methane fermentation and purification apparatus in which a process input is provided at the upper part of the methane gas separation unit or the return pipe;
(2) An air supply device that communicates with the methane gas separation part of the methane fermentation and purification device through a methane gas pipe and supplies methane gas;
(3) provided in the methane fermentation tank, communicated with the air supply device, and blown pipe for injecting methane gas into the methane fermentation tank; and (4) a methane gas extraction section provided in any of the methane gas pipes. A methane fermentation purification system characterized by that.   The methane fermentation purification system according to claim 1, wherein a desulfurization device is provided between the methane gas separation unit and the air supply device.   The methane fermentation purification system according to claim 1, wherein a desulfurization device is provided after the air supply device.   The methane fermentation purification system according to any one of claims 1 to 3, wherein the upper surface of the methane fermentation tank has a conical or quadrangular pyramid shape with the outlet pipe connecting portion 6 as a vertex. The methane fermentation purification system according to any one of claims 1 to 3, wherein the upper surface of the methane fermentation tank has a shape of a single-flow roof that rises toward the outlet pipe connection portion 6.

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