JP4044577B2 - Methane fermentation equipment - Google Patents

Description

  The present invention is a methane fermentation apparatus for methane fermentation of raw materials such as livestock manure and garbage by anaerobic microorganisms.

When methane gas is generated from livestock manure and garbage by anaerobic fermentation and the methane gas is effectively used for cogeneration, etc., each stage in performing methane fermentation is separated into individual tanks in order to improve methane fermentation efficiency. The method of performing in is adopted. FIG. 1 shows a typical example. For example, in the first tank, after generating an organic acid as an acid generator, it is transferred to a methane fermenter in the second tank and subjected to anaerobic fermentation. Is introduced into the desulfurization tower of the III tank, hydrogen sulfide (H ₂ S) in the methane gas is removed, and gas is stored in the IV tank. In some cases, a combination of an acid generator and a methane fermenter, a methane fermenter and a gas reservoir, etc. is employed.
JP 2003-285031 A

  However, in the above-mentioned conventional ones, each of acceptance heating, acid generation, methane fermentation, desulfurization, and gas storage is independent, and there are also combinations of acid generation and methane fermentation, methane fermentation and gas storage, etc. A transfer pump and piping between the processing apparatuses are required, and when each processing apparatus is installed independently, there is a problem that heat loss is large, and it cannot be applied in a place where there is not enough space for installation.

  When the raw material manure is heated to a temperature suitable for fermentation in the pretreatment supplied to the methane fermenter, it becomes aerobic fermentation in the raw material heating and acid generation, so its exhaust becomes a source of bad odor, It becomes a factor that deteriorates the environment, and it is necessary to take countermeasures.

  When anaerobic fermentation of livestock manure and garbage, solid waste such as litter is contained in livestock manure, so solid residue remains in the fermenter, and the discharge work is carried out regularly. However, since the fermenter is opened to the atmosphere and the fermentation liquid is discharged and carried out, it becomes complicated, and even if the fermentation liquid is refilled after discharge, it becomes an anaerobic atmosphere from atmospheric contact due to anaerobic fermentation. Has a drawback that it takes a long time to recover. Moreover, since organic solid content accumulates as a solid content residue in a methane fermenter, it may be separated into solid and liquid before methane fermentation, and may not be utilized effectively for methane fermentation.

In view of the above situation, the present invention arranges triple cylinders on the same axis, and integrates the functions of raw material heating, acid generation, methane fermentation, desulfurization, and gas storage, and a desulfurization section is provided at the top. In addition, the malodorous component of the aerobic biogas generated in the raw material heating section and the acid generation section and the hydrogen sulfide (H ₂ S) contained in the anaerobic biogas generated from the methane fermentation section are removed, and the residual content is also removed. An object of the present invention is to provide a methane fermentation apparatus that prevents the generation of malodors from being discharged outside the system of the methane fermentation apparatus.

In order to solve the above problems, the present invention provides the following configurations.
In the methane fermentation apparatus according to claim 1, in the triple cylinder on the concentric axis, the first cylinder is used as the raw material heating part of the raw material that is organic waste from the center, and the first cylinder and the second cylinder The annular part formed between the cylindrical body is an acid generator, the annular part formed between the second cylindrical body and the third cylindrical body is a methane fermentation part, and the raw material is a raw material heating part A means for heating from a lower part of the raw material to heat to a temperature suitable for acid generation and methane fermentation, and a means for preventing sludge accumulation in the raw material heating part by supplying air from the lower part of the raw material heating part to form an air lift And the heated raw material overflows the raw material heating part and flows into the acid production part, and the acid production part retains the fermentation period n days (0.2 to 0.3) × n days. Means to flow the raw material from the bottom of the acid generator to the methane fermentation section and the bottom of the acid generator using a conical inclined surface. A means to prevent sludge accumulation in the material and an anaerobic process in which the raw material rises up the methane fermentation part by placing a methane fungus support in order to promote methane fermentation in the inflow part from the acid generation part to the methane fermentation part Hydrogen sulfide by introducing means for fermenting and generating methane gas, the generated methane gas, the air supplied to the raw material heating section and the biogas generated in the acid generation section into the desulfurization section located above the acid generation section and methane fermentation section (H ₂ S) removing means, and a float tank is installed to store biogas containing methane flowing out from the desulfurization section in a gas storage section at the upper part of the desulfurization section. A gas storage means with a float tank guide at the top of the float tank is provided to remove malodorous components contained in biogas out of the methane fermentation system. Without out, receiving warm, acid generation, methane fermentation, desulfurization, characterized in that integrating the functions of the gas reservoir.

In the methane fermentation apparatus according to claim 2, as the desulfurization means, air of 15% (vol) or less of the amount of methane fermentation gas is supplied from the raw material heating unit, and the air is supplied from the raw material heating unit and the acid generation unit. The biogas having a bad odor generated and the methane gas generated in the methane fermentation part are cross-flowed at the gas inlet of the desulfurization part to improve the mixing of the two, and in the desulfurization part, hydrogen sulfide (H ₂ S) and It is characterized by removing malodorous components in biogas.

  The methane fermentation apparatus according to claim 3 extracts, as the desulfurization means, a digestive liquid that is a residual liquid after methane fermentation from the upper part of the methane fermentation part, stores the digested liquid in a desulfurization liquid culture tank, and a lighting window at the upper part of the tank. It is characterized in that it is more lit and promotes the cultivation of sulfur-oxidizing bacteria and photosynthetic bacteria in the digested liquid to form a desulfurized liquid, which is sprayed to the desulfurized part by a desulfurized liquid circulation pump, and the desulfurized liquid is circulated.

  In the methane fermentation apparatus according to claim 4, an annular duct is provided on the bottom of the methane fermentation section on a concentric axis with the methane fermentation tank, and the circulation flow of the fermentation liquid is provided in the annular duct outside the axial flow stirrer or the fermentation tank. A methane fermenter by means of a circulation pump and means for providing a pit part in a part of an annular duct to settling solid residue in the fermentation broth and automatically discharging the solid residue intermittently By preventing the accumulation of solid residue in the interior, organic solids such as garbage are used effectively as bio raw materials for methane fermentation, and the solid residue remaining in the bottom of the methane fermentation tank is automatically discharged. It is characterized by that.

  In the methane fermentation apparatus according to the present invention, by integrating the functions of methane gas storage, piping such as a liquid transfer pump for transferring between the apparatuses is completely unnecessary, and only the outer peripheral part of the methane fermentation section has a heat retention measure. Therefore, the installation space can be reduced and the cost can be reduced, and the odor is not discharged out of the system by the integrated structure, and the structure is made to prevent the odor.

  In addition, by installing an automatic discharge device for sludge in the raw material in the methane fermentation tank, it is possible to continue the operation for a long time without the need for internal inspection and cleaning by discharging the entire amount of raw material for removing the sludge in the methane fermentation tank. The organic solid content can increase the amount of methane gas produced by effectively using it for methane fermentation without solid-liquid separation before the methane fermentation tank.

Hereinafter, embodiments of the present invention will be described with reference to the drawings showing examples.
FIG. 1 is a conventional example of a methane fermentation apparatus as described above.

  FIG. 2 shows measured values of the methane gas fermentation period and the amount of methane gas generated in livestock manure by a combination of acid generation and methane fermentation in medium temperature fermentation (38 ° C.) of methane. As a result, methane fermentation after 4 to 5 days of acid production period shows that the amount of methane gas produced is saturated after 15 to 16 days. Conventionally, in medium temperature fermentation of methane, the fermentation period requires about 30 days. However, the fermentation period including acid generation and methane fermentation can be shortened to 20-22 days.

Biofermentation gas generally contains 60% methane (CH ₄ ), 40% carbon dioxide (CO ₂ ), and 2000 ppm hydrogen sulfide (H ₂ S). Hydrogen sulfide is an instrument and piping system for effective use of methane gas. Removal is an essential issue because it causes corrosion. As a desulfurization method, biological desulfurization using microorganisms to remove hydrogen sulfide has the lowest running cost, but the equipment cost is higher than the adsorption method using metal oxide and activated carbon. In order to suppress the cost, the methane fermentation apparatus according to the present invention has a structure in which the desulfurization part is accommodated in the methane fermentation apparatus.

3 is a cross-sectional view of the methane fermentation apparatus according to the embodiment of the present invention, FIG. 4 is a cross-sectional view along AA ′ in FIG. 3, and FIG. 5 is a cross-sectional view along BB ′ in FIG.
In the methane fermentation apparatus of the present invention, the first cylindrical body 11 at the center of the three sets of cylindrical bodies on the same axis has a hot water jacket 11a. It supplies to the part 10, and it heats to the temperature suitable for acid production | generation and methane fermentation (38 degreeC is suitable in medium temperature fermentation, and 55 degreeC is suitable in high temperature fermentation). The heated raw material overflows from the upper part of the raw material heating unit 10 to the first cylindrical body 11 and forms an annular acid generator 20 formed by the first cylindrical body 11 and the second cylindrical body 21. Inflow.

  In addition, the air supplied from the air supply unit 13 installed at the lower part of the raw material heating unit 10 forms an air lift as a bubble rising flow, prevents sludge accumulation in the raw material, and is supplied to the desulfurization unit 40. The air is desirably 15% (vol) or less of the amount of methane fermentation gas.

  The raw material overflowing the raw material heating unit 10 generates an organic acid in the acid generator 20, descends the acid generator 20, and the methane fermentation unit 30 from the acid generator outlet 22 at the bottom of the acid generator 20. Flow into. The acid generator outlet 22 of the acid generator 20 has a structure that prevents sludge accumulation in the raw material due to the inclination of the conical inclined part 23. In addition, a porous methane bacterium holding body 30a is disposed at the acid generator outlet 22 to promote methane fermentation of the raw material.

  A horizontal axis propeller type stirrer 32 is installed at the bottom of the annular methane fermentation unit 30 formed by the second cylindrical body 21 and the third cylindrical body 31, and the raw material is stirred so that sludge is contained in the raw material. Preventing accumulation. The residence period of the raw material in the methane fermentation unit 30 is 15 to 17 days. During the methane fermentation period, the raw material is heated by the hot water jacket 21a of the second cylindrical body 21, and methane fermentation is promoted. When the liquid level of the methane fermentation unit 30 rises, the overflow from the specified liquid level overflows from the digested liquid U-shaped discharge pipe 33.

The biogas containing methane generated in the methane fermentation unit 30 flows into the desulfurization unit 40 from the gas inlet 40b, and the air used for the air lift of the raw material heating unit 10 and the CO ₂ generated in the acid generation unit 20 are used. The biogas as the main component flows into the desulfurization section 40 from the gas inlet 40a. The outflow of gas from each gas inflow port is mixed by flowing perpendicularly and introduced into the desulfurized gas-liquid contact portion 41.

The desulfurized gas-liquid contact portion 41 is filled with a filler for gas-liquid contact. Here, the biogas is brought into gas-liquid contact with the desulfurized liquid, thereby removing hydrogen sulfide (H ₂ S).
The method for circulating the desulfurization liquid is as follows. First, the digestive liquid which is the residual liquid after methane fermentation is extracted from the upper part of the methane fermentation unit 30 and supplied to the desulfurization liquid culture tank 45 through the digestive liquid supply valve 44. The digested liquid that has moved into the desulfurization liquid culture tank 45 is promoted to culture sulfur-oxidizing bacteria and photosynthetic bacteria by light from the lighting window 45a, and becomes a desulfurized liquid. Further, the desulfurization liquid is supplied to the desulfurization liquid spraying section 42 by the desulfurization liquid circulation pump 46 and sprayed to the desulfurization gas-liquid contact section 41, where the biogas is desulfurized by contacting with the biogas. The desulfurization liquid after biogas desulfurization falls to the lower part of the desulfurization section 50 and returns to the desulfurization liquid culture tank 45 through the desulfurization liquid discharge pipe 43. The desulfurization liquid is replenished from the methane fermentation unit 30 via the digestive liquid replenishment valve 44, and the rise in the specified liquid level in the desulfurization liquid culture tank 45 is discharged through the desulfurization liquid U-shaped discharge pipe 47.
The methane gas biodesulfurized by gas-liquid contact at the desulfurization gas-liquid contact unit 41 is stored in the gas storage unit 50 in the float tank 51.

  FIG. 6 is a vertical cross-sectional view of a float tank unit installed in the upper part of the methane fermentation apparatus according to the present invention. The float tank 51 is held by a float tank guide 52a at the center of the float tank cover 52, and is sealed from the outside air by a seal portion 52b. Therefore, even if the float tank 51 moves up and down as the methane gas in the gas reservoir 50 increases or decreases, the methane gas is not discharged to the outside.

A methane fermentation apparatus according to a second embodiment of the present invention is shown in FIGS.
FIG. 7 is a schematic longitudinal sectional view of a methane fermentation apparatus according to the second embodiment of the present invention, and FIG. 8 (a) is an AA ′ section when an axial flow stirrer is used in the methane fermentation apparatus shown in FIG. Fig. 8 (b) is a cross-sectional view taken along line AA 'when a circulation pump is used in the methane fermentation apparatus.
In the three cylinders shown in FIG. 7, the first cylindrical body 11 at the center portion forms the raw material heating unit 10, and the raw material is supplied from the raw material supply unit 12 located at the lower part of the raw material heating unit 10. Heated by 11 a, overflows from the upper part of the raw material heating unit 10, and is supplied to the acid generation unit 20 that is the second cylindrical body 21.

In the acid production | generation part 20, air is supplied and an organic acid is produced | generated, and air is mixed with methane gas in the desulfurization part 40, and desulfurization is accelerated | stimulated by sulfur oxidation bacteria.
The raw material supplied to the acid generator 20 descends the acid generator 20. Since the bottom part of the acid production | generation part 20 forms the inclined surface, the raw material in an acid production | generation part flows down to the bottom part of the methane fermentation part 30 which the 3rd cylindrical body 31 forms as it is. The bottom of the methane fermentation unit 30 forms a V-shaped annular duct 31a, and an axial flow propeller type stirrer 32 shown in FIG. 8A is installed in the duct. The fermentation liquor in the fermentation unit 30 forms an annular flow.

In FIG. 8B, the fermentation liquid flows out from the circulation discharge port 32b in the annular duct 31a by the circulation pump 32a installed outside the methane fermentation unit 30 to form a circulation flow.
The circulating flow in the annular duct 31a formed by the agitator 32 or the circulation pump 32a does not cause solids and sludge in the raw material to stay, but a sludge pit 34 is partially formed in the annular duct 31a. The sludge settles in the sludge pit 34 and stays there. The accumulated sludge is periodically discharged by a sludge discharge pump 35 to prevent the accumulation of solid residue in the fermenter, and the raw material is not separated into solid and liquid before being supplied to the fermenter. Is effectively used for gas generation in the fermenter.

As described above, according to the methane fermentation apparatus according to the present invention, when organic waste is subjected to methane fermentation, in order to improve methane fermentation performance, a method of acid generation treatment before methane fermentation is employed, and desulfurization is also performed. The gas storage part is integrated with the methane fermentation part.
In the present invention, when organic waste is heated to generate acid, it becomes a source of bad odor, so the raw material heating section and acid generation section are housed in the methane fermentation apparatus, and the desulfurization section and gas storage section are By storing and integrating in the apparatus, the installation space can be reduced, the heat radiation amount of the equipment can be reduced by reducing the contact area with the outside air, and the cost can be reduced. Moreover, prevention of bad odor generation by storing the raw material heating section and the acid generation section in the methane fermentation section is effective for improving the environment.

  Further, according to the methane fermentation apparatus according to the present invention, when organic waste is used as a raw material, livestock manure as the raw material cannot be mixed with bedding such as beef barn and pig barn, but solid content such as bedding is not avoided. In the methane fermentation, it contributes to gas generation. In its effective use, an automatic discharge unit is provided to prevent the sludge in the raw material from accumulating on the bottom of the methane fermentation tank, which is effective in increasing the amount of methane produced and reducing maintenance costs.

It is a schematic block diagram of the conventional methane fermenter. Methane gas fermentation time and amount of methane gas generated when acid is generated in the pretreatment of methane fermentation. It is a longitudinal cross-sectional view of the methane fermentation apparatus which concerns on embodiment of this invention. FIG. 4 is a cross-sectional view taken along the line A-A ′ of FIG. 3. FIG. 4 is a B-B ′ sectional view of FIG. 3. It is a longitudinal cross-sectional view of the float tank part installed in the methane fermentation apparatus upper part by this invention. It is a schematic longitudinal cross-sectional view of the methane fermentation apparatus which concerns on 2nd Embodiment of this invention. (A) is AA 'sectional drawing at the time of using an axial-flow stirrer for the methane fermentation apparatus in FIG. 7, (b) is AA' at the time of using a circulation pump for the methane fermentation apparatus in FIG. It is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Raw material heating part 11 1st cylinder 11a Hot water jacket 12 Raw material supply part 13 Air supply part 20 Acid production | generation part 21 2nd cylindrical body 21a Hot water jacket 22 Acid production | generation part outlet 23 Conical inclination part 30 Methane fermentation part 30a Methane bacteria support body 31 3rd cylindrical body 31a Toroidal duct 32 Stirrer 32a Circulation pump 32b Circulation discharge port 33 Digested liquid U-shaped discharge pipe 34 Sludge pit 35 Sludge discharge pump 40 Desulfurization part 40a Gas inlet 40b Gas inlet DESCRIPTION OF SYMBOLS 41 Desulfurization gas-liquid contact part 42 Desulfurization liquid spraying part 43 Desulfurization liquid discharge pipe 44 Digestion liquid supply valve 45 Desulfurization liquid culture tank 45a Daylighting window 46 Desulfurization liquid circulation pump 47 Desulfurization liquid U-shaped discharge pipe 50 Gas storage part 51 Float tank 52 Float tank cover 52a Float tank guide 52b Seal part

Claims (4)

In the triple cylinder on the concentric axis, a circle formed between the first cylinder and the second cylinder, with the first cylinder from the center serving as the raw material heating part of the raw material that is organic waste The ring part is an acid generator, the annular part formed between the second cylinder and the third cylinder is a methane fermentation part,
The raw material is supplied from the lower part of the raw material heating part and heated to a temperature suitable for acid generation and methane fermentation, and the sludge in the raw material heating part is formed by supplying air from the lower part of the raw material heating part to form an air lift. Means for preventing accumulation, means for the heated and raised raw material to overflow the raw material warming part and flow into the acid production part, and fermentation period n days (0.2 to 0.3 in the acid production part) ) × n means that the raw material retained for n days flows out from the bottom of the acid generator to the methane fermentation section, the bottom of the acid generator uses a conical inclined surface to prevent sludge accumulation in the raw material, and acid generation In order to promote methane fermentation from the methane fermentation section to the methane fermentation section, a methane bacterium holding body is arranged, and the means for anaerobic fermentation and generation of methane gas in the process of the raw material rising up the methane fermentation section, the generated methane gas, Generated by the air and acid generator supplied to the hot section Means for introducing the produced biogas into a desulfurization section located above the acid generation section and the methane fermentation section and removing hydrogen sulfide (H ₂ S) (hereinafter referred to as desulfurization);
A float tank is installed to store the biogas containing methane flowing out of the desulfurization unit in the gas storage unit at the top of the desulfurization unit. The float tank is stored in the float tank cover, and the float tank guide is at the top of the float tank. It is equipped with gas storage means with a combined function of receiving heating, acid generation, methane fermentation, desulfurization, and gas storage without discharging malodorous components contained in biogas outside the methane fermentation system. A methane fermentation device characterized in that As the desulfurization means, air of 15% (vol) or less of the amount of methane fermentation gas is supplied from the raw material heating unit, the biogas having malodor generated from the raw material heating unit and the acid generation unit, and methane To improve the mixing of the methane gas produced in the fermentation section by cross-flowing at the gas inlet of the desulfurization section, and to remove hydrogen sulfide (H ₂ S) and malodorous components in the biogas in the desulfurization section The methane fermentation apparatus according to claim 1.   As the desulfurization means, the digestive liquid, which is a residual liquid after methane fermentation, is extracted from the upper part of the methane fermentation section, the digestive liquid is stored in a desulfurized liquid culture tank, and is collected from the lighting window at the upper part of the tank. The sulfur-oxidizing bacteria and photosynthetic bacteria in the culture are promoted to form a desulfurization liquid, which is dispersed to the desulfurization section by a desulfurization liquid circulation pump, and biogas is brought into gas-liquid contact with the biogas in the desulfurization section. 2. The methane fermentation apparatus according to claim 1, wherein the desulfurization liquid is circulated by returning the desulfurization liquid after desulfurization and biogas desulfurization to the desulfurization liquid culture tank 45 through the desulfurization liquid discharge pipe 43. A means for forming an annular duct on the concentric shaft with the methane fermentation tank at the bottom of the methane fermentation section, and forming a circulating flow of the fermentation liquid in the annular duct with an axial flow stirrer or a circulation pump outside the fermentation tank;
A pit part is provided in a part of the annular duct, and solid residue in the fermentation liquid is settled and accumulated, and the solid residue is accumulated in the methane fermentation tank by means of intermittent automatic discharge of the solid residue. The organic solid content such as garbage is effectively used for methane fermentation as a bio raw material by preventing the solid content residue accumulated in the bottom of the methane fermentation tank and discharged automatically. The methane fermentation apparatus as described in any one of 3.

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