JPH0137759Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to an anaerobic fermenter that uses an immobilization method in which anaerobic bacteria are immobilized on a carrier and fermentation is carried out by increasing the concentration of the bacteria. In particular, the present invention relates to an anaerobic fermenter equipped with a device for effectively collecting gas produced by bacterial cells.

[Prior art] Digestion methods have generally been widely used for methane fermentation, but since this reaction requires a long time, instead of this method, anaerobic bacterial cells are immobilized on carriers such as raschich rings or honeycomb structures. An immobilization method has been developed that increases the bacterial cell concentration and thereby shortens the reaction time. The apparatus adopts a fixed bed type as shown in FIG. 2, in which a carrier 2 on which anaerobic bacterial cells are immobilized is filled inside a chamber sealed by a cylindrical outer tube member 10 to form a fixed bed. are doing. This fixed bed portion is hereinafter referred to as the fixed portion 14.

The stock solution is supplied from the supply pipe 3 and rises while coming into contact with the carrier 2 of the fixed part 14, and the substrate is decomposed by the anaerobic bacterial cells, generating gases such as carbon dioxide and methane. That is, the raw solution rising through the fixing part 14 moves upward along with the produced gas as if passing through the gap between the carriers and reaches the treated liquid layer 13, where the produced gas and the treated liquid are separated, and the produced gas flows into the produced gas layer. 12 and is led out of the tank from the generated gas recovery pipe 5, and the treated liquid passes through the upper discharge port 4 of the liquid layer and is successively taken out of the tank.

The circulation pump 6 whose pumping port is immersed in the treated liquid layer is used to bring a part of the raw solution into contact with the bacterial cells again to increase the chances of fermentation, or to release excess bacterial cells attached to the carrier (so-called The stock solution is circulated from the top of the tank to the bottom of the tank for backwashing.

[Problems to be solved by the invention] When operating the device as described above, the proliferation of bacterial cells is promoted over time, and the density of bacterial cells eventually becomes too high, causing the carrier to become The apparent gap with the carrier becomes narrower, eventually causing a portion to become blocked. When such blockage occurs, not only does the contact area between the stock solution and the bacterial cells decrease, but the escape route for the produced gas is limited, further restricting the flow of the stock solution, and eventually the opportunity for contact with new stock solution decreases. As a result, a problem arises in that the substrate decomposition rate in the stock solution decreases. That is, as shown in FIG. 3 (graph), the amount of gas generated and the substrate decomposition rate decrease with the passage of operating time.

Therefore, the inventors of the present invention conducted various studies and came up with the guideline that in order to make the flow of stock solution proceed smoothly, it is a prerequisite to quickly remove the gas in the fixing part 14. As a result of repeated research into devising a device that can collect the same amount of water, the present invention was completed.

[Means for solving the problem] The present invention is intended to solve the above problem, and has an arbitrary pitch in the depth direction in the fixed part of the anaerobic fermenter, and has a spiral shape in plan view. The gist lies in the provision of a gas discharge gutter which is a downwardly opening gutter and is configured such that the gutter volume of the downwardly opening gutter increases continuously or stepwise as it goes upward.

[Function] In order to draw out the gas that is generated and rising within the fixed part from the fixed part 14 without causing congestion near the carrier, it is necessary to at least perform separation from the carrier, that is, solid-gas separation, to collect only the gas and float it. I thought it would be a good idea to go. Therefore, we considered an arm-shaped gas collection member that would accept the floating gas, but this would require a separate communication member and lifting guide to further collect the collected gas and raise it. I thought of a gas vent gutter that looks like a horizontally long arm connected in a spiral manner. In other words, the gas extraction gutter of the present invention has an opening shape in which the lower side that can receive floating gas is covered with a net-like material that allows only gas and liquid to flow in (the carrier does not pass through), and the opening from the upper side to the side side. The gutter is covered with an impermeable material that does not allow gas to pass through, and is shaped like a gutter turned upside down, and is called a gas vent gutter 7.
Moreover, the gas protruding gutter 7 is inclined upward, and the gutter itself is continuous and extends at least to the upper end of the fixing part 14, so that the produced gas is guided to the produced gas layer 12 at the upper part of the fermenter. do. In addition, gas generation takes place over the entire surface of the fermenter, and the gas rises almost directly upwards, so the idea is to capture this gas throughout the tank, so it is said to cover the inside of the tank when viewed from above. In accordance with the purpose, the gas extraction gutter was a spiral gutter having a spiral shape in plan view and having an arbitrary pitch in the depth direction. Further, when the gas extraction gutter 7 is configured as described above, the amount of gas passing through the gas extraction gutter 7 increases as it goes toward the upper part of the fixed part because the gas generated in each part is collected in sequence. Therefore, the volume of the gutter 7 needs to be shaped so that it increases continuously or stepwise as it goes upward.

[Example] As a typical example of the present invention, a case of a methane production fermenter is taken up and shown in Fig. 1 (perspective view), Fig. 4 (schematic view), Fig. 5 (sectional view), and Fig. 6 (explanation). figure),
This will be explained along with FIG. 7 (graph). Outer tube member 1
The carrier 2 on which methanogens are immobilized is filled in a container sealed with 0 to form the immobilizing part 14. The gas vent gutter 7 provided in the fixed part 14 has the shape of an upside-down gutter as shown in FIG. The lower part is covered with a mesh material 9 having a mesh size large enough to prevent the carrier from passing through. Note that the shape of the gas venting gutter 7 is not limited to this example, and may be one in which a hole is formed at the bottom of a tubular object. Any structure may be used as long as it can be caught in the gutter. Since the gas extraction gutter 7 is arranged continuously from the fixed lower end to the upper end, the gas collected on the way to the upper part gathers, and the amount of generated gas passing through the gutter increases as it moves towards the upper part. Therefore, the volume of the gas discharge gutter 7 is set so that it increases toward the upper side, and the structure is such that the collected gas is not discharged out of the gutter again.

Fixing part 1 determines the amount of gas generated in the methane fermentation tank.
As a result of investigating the relationship with the height of 4, it was found that the peak of the gas generation amount appeared at _H1 slightly above the middle position of the fixed part, as shown in FIG. Note that H ₀ indicates the lower end of the fixed portion, and H ₂ indicates the upper end of the fixed portion.

Therefore, in this embodiment, considering that the gas collection function itself is maximized near H ₁ , the distance from the center is increased toward H ₁ starting from the center of the fixed lower end H ₀ surface. spiral, and the sixth
As shown in the figure, the gas vent gutter 7 is located below from the _H1 position.
As can be seen, the gutter 7 is arranged so as to cover almost the entire cross-sectional area of the bottom surface of the fixing part. In this example, the spiral pitch is configured to reach from H ₀ to H ₁ in 3 turns, but any pitch can be selected depending on the shape of the fixed part and various other conditions. Needless to say. Further, in this embodiment, the gas venting gutter 7 is connected between H ₁ and _{H 2} as well _.
As with the case, it has a spiral shape that completely covers the cross section of the fixed part, and the distance from the center decreases from _H1 to _H2 . By configuring the spiral shape as described above, methane gas can be quickly and effectively recovered at a location where a large amount of gas is generated. Note that the present invention is not limited to the spiral-shaped gutter as described above, but as shown in FIG. It may be of a shape that leads upward. Furthermore, the cross-sectional shape of the gas discharge gutter 7 is not limited to a semicircular shape as in this embodiment, but a circular shape or a semicircular shape as in the present embodiment.
It may be of any shape, such as rectangular, polygonal, semi-circular, semi-polygonal, etc., as long as it has air permeability at the bottom. Next, using FIG. 4 (schematic diagram), a simulated explanation will be given of the route through which the gas generated at point _A0 in the fixed part moves.

First, the gas generated at point _A0 rises in a meandering manner as if threading through the gap between the carriers 2, and after reaching the gas release gutter 7 at point _A1 , it passes through the mesh 9 and enters the gutter. reach the wall. Then, it merges with the produced gas that had similarly flowed into the gutter, moves to the upper part while turning along the inner wall of the upper part of the gutter, and finally passes through the gas passage 8 and enters the produced gas layer 12, whereupon the gas is recovered. It is guided out of the fermenter from the tube 5.

[Effect of the invention] By providing the gas extraction gutter 7 in the fixed part 14 as described above, the generated gas can be recovered smoothly, and the gas escape path between the carriers will not be blocked. Ta. Therefore, the stock solution flows smoothly between the carriers without restricting the contact between the bacterial cells and the stock solution, and a decrease in the substrate decomposition rate is prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a typical embodiment of the present invention, FIG. 2 is an explanatory view showing a conventional anaerobic fermenter,
Fig. 3 is a graph showing the relationship between gas generation amount and substrate decomposition rate and time, Fig. 4 is an explanatory diagram showing an embodiment of the present invention, and Fig. 5 is a diagram showing an example of the cross-sectional shape of a gas extraction gutter. , Figure 6 is a schematic diagram of a part of the gas extraction gutter in the fermenter viewed from above, Figure 7 is a graph showing the relationship between the amount of gas generated and the height of the fixed part, and Figure 8 is the gas extraction gutter. FIG. 7 is a schematic diagram showing another embodiment of the present invention. 1... Anaerobic fermentation tank, 2... Carrier, 3... Stock solution supply pipe, 4... Treated liquid recovery pipe, 5... Produced gas recovery pipe, 6... Circulation pump, 7... Produced gas extraction Gutter, 8... Produced gas passage, 10... Outer pipe member, 1
2... Produced gas layer, 13... Treated liquid layer.

Claims (1)

[Scope of utility model registration request] An anaerobic fermentation tank having an anaerobic cell fixing part and a produced gas extraction part has an arbitrary pitch in the depth direction in the fixing part, and is a downward opening gutter with a spiral shape in plan view. An anaerobic fermentation tank characterized in that it is provided with a gas discharge gutter configured such that the gutter volume of the downwardly opening gutter increases continuously or stepwise as it goes upward.