Fermentation device, method for using fermentation device and method for manufacturing methane gas

Abstract

To provide a fermentation device that can suppress a consumption amount of clean water such as tap water.SOLUTION: A fermentation device 1 includes a crushing step part 10 for crushing a fermentation raw material and a fermentation tank 2, introduces the fermentation raw material crushed by the crushing step part 10 into the fermentation tank 2 and ferments the fermentation raw material inside the fermentation tank 2. The fermentation device includes a return flow transportation passage 60 for returning water content from the fermentation tank 2 into the crushing step part 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fermentation apparatus and a method for producing methane gas using food waste or the like as a fermentation raw material. [Background technology]

[0002] As one of the measures for effectively utilizing food waste, it has been proposed to generate methane gas by anaerobic digestion (methane gas fermentation) and collect and utilize the methane gas. That is, food waste and the like are used as raw materials and fermented by anaerobic bacteria to generate methane gas, which can be used for power generation and other purposes. Food waste is crushed into small pieces before being put into the fermentation tank. Wet crushing equipment is often used to crush food waste. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-26301 Summary of the Invention [Problem to be solved by the invention]

[0004] A wet crushing device is a device that crushes objects in liquid, and can crush objects into smaller pieces than a dry crushing device. In conventional technology, clean water such as tap water or groundwater is poured into a wet crushing device along with food waste, and with the chamber of the wet crushing device filled with water, the rotary blades are driven to crush the food waste.

[0005] As mentioned above, the conventional fermentation apparatus injects clean water or the like into the wet crushing device, which poses a problem of high consumption of clean water or the like. The present invention focuses on the above-mentioned problems of the prior art, and aims to propose a fermentation apparatus and a method for producing methane gas that can reduce the consumption of clean water such as tap water. [Means for solving the problem]

[0006] An embodiment for solving the above-mentioned problems is a fermentation apparatus having a crushing process section for crushing fermentation raw materials and a fermentation tank, in which the fermentation raw materials crushed in the crushing process section are introduced into the fermentation tank and the fermentation raw materials are fermented in the fermentation tank, and one of the features of the fermentation apparatus is that it has a reflux conveying path for returning water in the fermentation tank to the crushing process section. An embodiment for solving the above-mentioned problems is a fermentation apparatus having a crushing process section for crushing fermentation raw materials and a fermentation tank, in which the fermentation raw materials crushed in the crushing process section are introduced into the fermentation tank and the fermentation raw materials are fermented in the fermentation tank, and a reflux conveying path for returning water in the fermentation tank to the crushing process section, the crushing process section having a dry-type rough crushing device and a wet-type crushing device, the wet-type crushing device being arranged downstream of the rough crushing device, the fermentation raw materials crushed in the rough crushing device are further crushed in the wet-type crushing device, and the reflux conveying path is connected to both the rough crushing device and the wet-type crushing device. In the above aspect, it is preferable that the crushing process section has a pressure pump, and the return transport line is connected to the pressure pump. Another aspect for solving the above-mentioned problems is a fermentation apparatus having a crushing process section that crushes fermentation raw materials and a fermentation tank, in which the fermentation raw materials crushed in the crushing process section are introduced into the fermentation tank and fermented in the fermentation tank, characterized in that the fermentation apparatus has a reflux conveying path that returns water in the fermentation tank to the crushing process section, the crushing process section has a pressure pump, and has a storage tank that temporarily stores the fermentation raw materials, and has a stockpiling conveying path connecting the pressure pump of the crushing process section to the storage tank, and an input conveying path that connects the storage tank and the fermenter.

[0007] Here, "moisture" means "containing water." The material returned to the crushing process section by the reflux conveying path contains digestive fluid. In this embodiment, the moisture in the digestive fluid is used to supplement the moisture required during crushing. In many cases, the material returned to the crushing process section by the reflux conveying path is a slurry containing a mixture of solids and water. The "conveying path" may be a pipeline made of steel pipes, hoses, or the like, or may be a conveyor capable of transporting materials containing moisture, such as a screw conveyor or a bucket conveyor. According to this embodiment, the water in the fermenter is supplied to the crushing process section, so that the amount of clean water used can be reduced. In some cases, the chamber of the crushing device can be filled with liquid without using tap water or the like.

[0008] In the above-mentioned aspect, it is desirable that the temperature-controlled circulation conveying path has a heat exchange section in the middle, the temperature-controlled circulation conveying path extracts moisture from the fermenter tank, guides it to the heat exchange section to adjust the temperature, and returns it to the fermenter tank, has a pump, the suction side of the pump is connected to the fermenter tank, the discharge side of the pump is branched, one of the branches is connected to the heat exchange section to form the temperature-controlled circulation conveying path, and the other branch forms the reflux conveying path.

[0009] The fermentation apparatus of this embodiment has a temperature-controlled circulation transport path that circulates the contents of the fermenter via a heat exchanger. The fermentation apparatus of this embodiment can regulate the temperature of the contents using a heat exchanger in the temperature-controlled circulation conveying path, so that the fermentation raw materials in the fermenter can be kept at a temperature suitable for fermentation. Furthermore, in the fermentation apparatus of this embodiment, the pump for the temperature-controlled circulation conveying path and the pump for the reflux conveying path are shared, so the number of parts is small.

[0010] In each of the above-mentioned aspects, it is desirable to have a night soil storage tank for storing animal feces and urine, and a night soil supply and conveyance path for sending the night soil stored in the night soil storage tank to the crushing process section.

[0011] "Animals" includes cows, horses, pigs, sheep and other mammals, as well as birds such as chickens. "Animals" also includes humans. Human waste contains a lot of water. In the fermentation apparatus of this embodiment, the night soil is supplied to the crushing process section, and the moisture in the night soil is used to form a slurry of the fermentation raw material, so that the amount of clean water used can be reduced.

[0012] In each of the above-mentioned aspects, it is desirable that the crushing process section has a coarse crushing device and a wet crushing device, the wet crushing device is arranged downstream of the coarse crushing device, and the fermentation raw material crushed by the coarse crushing device is further crushed by the wet crushing device.

[0013] According to this embodiment, food waste and the like are crushed by the coarse crushing device, and then further finely pulverized by the wet crushing device. In the fermentation apparatus of this embodiment, the fermentation raw material is crushed in the coarse crushing device and sent to the wet crushing device, so the fermentation raw material is likely to get caught in the wet crushing device. That is, when the fermentation raw material is large, the fermentation raw material may float in the wet crushing device and may not easily be caught by the blades of the wet crushing device. In the fermentation apparatus of this embodiment, the fermentation raw material crushed in the coarse crushing device is sent to the wet crushing device, so the fermentation raw material is likely to get caught in the wet crushing device and is crushed into small pieces in the wet crushing device. According to this embodiment, the fermentation raw material is transported to the fermenter in a finely pulverized state, so that fermentation can proceed easily.

[0014] In the above-mentioned aspect, it is desirable that the crushing process section has the coarse crushing device and the wet crushing device arranged in upper and lower positions, and that they are connected directly or via a pipeline, and that a water level sensor be provided between a coarse crushing device-side breaking section where the fermentation raw material is broken in the coarse crushing device and a wet-side breaking section where the fermentation raw material is broken in the wet crushing device. That is, in each of the above-mentioned aspects, it is desirable that the crushing process section has a coarse crushing device and a wet crushing device, the coarse crushing device and the wet crushing device are arranged in upper and lower positions and are connected to each other directly or via a pipeline, and a water level sensor is provided between a coarse crushing device-side breaking section where the fermentation raw material is broken in the coarse crushing device and a wet-side breaking section where the fermentation raw material is broken in the wet crushing device.

[0015] In the fermentation apparatus of this embodiment, a water level sensor is provided between the wet-side rupture section where the fermentation raw material is ruptured, so that it is possible to accurately detect whether there is a sufficient amount of liquid in the wet-side rupture section.

[0016] In each of the above-mentioned aspects, it is desirable to have a storage tank for temporarily storing fermentation raw materials, a first input conveying path connecting the crushing process section and the fermentation tank, a stockpiling conveying path connecting the crushing process section and the storage tank, and a second input conveying path connecting the storage tank and the fermentation tank.

[0017] Here, the "storage tank" may be one with an open top space, such as a swimming pool, or one that is sealed, such as a tank. The fermentation apparatus of this embodiment has a storage tank for temporarily storing the fermentation raw material. Therefore, when a large amount of fermentation raw material is transported from the outside to the fermentation apparatus, the fermentation raw material can be crushed and stored in the storage tank via a stockpile transport path. If necessary, the material can be transported from the storage tank to the fermentation tank via the second input transport path.

[0018] In the above-mentioned aspect, it is desirable that the conveying path switching means is provided, and that it is possible to carry out full-amount charging, in which the entire amount of the fermentation raw material crushed in the crushing process section is carried into the fermenter tank, partial charging, in which a portion of the fermentation raw material crushed in the crushing process section is carried into the fermenter tank and the remainder is carried into the storage tank, and additional charging, in which the entire amount of the fermentation raw material crushed in the crushing process section and the fermentation raw material in the storage tank are simultaneously carried into the fermenter tank.

[0019] According to this aspect, even if there is variation in the amount of fermentation raw material introduced into the fermentation device or the amount of collected food waste, the amount of fermentation raw material put into the fermenter can be leveled out.

[0020] An embodiment of the method for using the fermentation apparatus of the above embodiment is characterized in that, when the amount of fermentation raw material being crushed per given time in the crushing process section is greater than the planned amount of fermentation raw material to be charged to the fermenter per given time, a partial charge is carried out in which a part of the fermentation raw material crushed in the crushing process section is carried into the fermenter and the remainder is carried into the storage tank, and when the amount of fermentation raw material being crushed per given time in the crushing process section is less than the planned amount of fermentation raw material to be charged to the fermenter per given time, an additional charge is carried out in which the fermentation raw material in the storage tank is simultaneously carried into the fermenter in addition to the entire amount of fermentation raw material crushed in the crushing process section.

[0021] A "certain period of time" is a relatively long span of time, such as one hour, three hours, or half a day. According to this aspect, even if there is variation in the amount of fermentation raw material introduced into the fermenter, the amount of fermentation raw material introduced into the fermenter can be smoothed out.

[0022] Another aspect for solving the same problem is a methane gas production method including a slurrying step of crushing fermentation raw materials including food waste to form a slurry, and a fermentation step of introducing the fermentation raw materials slurried in the slurrying step into a fermenter and subjecting them to methane fermentation to obtain methane gas and a digestate, characterized in that the digestate obtained in the fermenter is added to the fermentation raw materials and crushed during the slurrying step. [Effects of the Invention]

[0023] The fermentation apparatus and methane gas production method of the present invention have the effect of reducing the consumption of clean water and the like. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a system diagram of a fermentation apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the vicinity of the crushing process section of the fermentation apparatus of FIG. [Figure 3] FIG. 2 is an enlarged view of the vicinity of the night soil tank of the fermentation apparatus of FIG. 1. [Figure 4] FIG. 2 is an enlarged view of the vicinity of the storage tank of the fermentation apparatus of FIG. [Figure 5] 2 is a system diagram of the fermentation apparatus of FIG. 1, showing the flow of the fermentation raw material and digested liquid when the entire amount of the fermentation raw material is charged into the fermenter. [Figure 6] 2 is a system diagram of the fermentation apparatus of FIG. 1, showing the flow of the fermentation raw material when a portion of the fermentation raw material is charged into the fermenter. [Figure 7] 2 is a system diagram of the fermentation apparatus of FIG. 1, showing the flow of the fermentation raw material when the entire amount of crushed fermentation raw material is transported to the storage tank. [Figure 8] 2 is a system diagram of the fermentation apparatus of FIG. 1, showing the flow of the fermentation raw material when the fermentation raw material is added to the fermentation tank. [Figure 9] 2 is a system diagram of the fermentation apparatus of FIG. 1, showing the flow of fermentation raw materials when the temperature of the fermentation raw materials in the fermenter is controlled. [Figure 10] FIG. 2 is a block diagram of a control device of the fermentation apparatus of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] Further embodiments of the present invention will be described below. The fermentation apparatus 1 of this embodiment uses food waste or human waste as fermentation raw materials, crushes them, puts them into a fermentation tank 2, and performs methane fermentation to obtain methane gas. As shown in FIG. 1, the fermentation apparatus 1 of this embodiment can be divided into a fermentation tank 2 and a fermentation fuel supply unit 3. The fermentation fuel supply section 3 is composed of a crushing process section 10, a human waste storage tank 11, and a storage tank 12.

[0026] Each part will be explained below. The fermenter 2 is a sealed tank. Inside the fermenter 2, an agitator 17 is provided. The fermenter 2 is equipped with a liquid level gauge, a temperature sensor, a pressure sensor, etc. (none of which are shown), similar to known devices. The fermenter 2 also has a number of openings (not shown), which function as inlets for introducing fermentation raw materials and outlets for removing fermentation raw materials.

[0027] The fermenter 2 is provided with a temperature-controlled circulating transport path 20 as shown in FIGS. The temperature-controlled circulation conveying path 20 is a pipe connecting the raw material withdrawal hole 21 and the raw material return hole 22 provided in the fermentation tank 2, and a circulation pump 25 and the secondary side of a heat exchanger 26 are interposed in the middle. The primary side of the heat exchanger 26 is connected to a water heater (not shown). A flow path adjustment valve 23 is also provided in the temperature-controlled circulation transfer path 20. The flow path adjustment valve 23 can adjust its opening degree by a motor, and can also be fully closed.

[0028] The fermentation tank 2 receives food waste and human waste, and anaerobic bacteria ferment the waste to produce methane gas (anaerobic digestion method). Digestive juices are also produced as a by-product of fermentation.

[0029] Next, the crushing process section 10 will be described. As shown in FIG. 2, the crushing process section 10 has a crushing section 15 made up of two crushing devices. In this embodiment, the crushing section 15 includes a dry crushing device 30 and a wet crushing device 31 . The type and blade structure of the dry crushing device 30 are not limited, but a two-shaft dry crushing device is used in this embodiment. The dry crushing device 30 also functions as a coarse crushing device. The wet crushing device 31 is not limited to any particular type or blade structure, but in this embodiment, a device having a rotary blade provided in a chamber is used. The wet crushing device 31 is disposed downstream of the dry crushing device 30 .

[0030] In the crushing process section 10 of this embodiment, as shown in FIG. 2, a dry crushing device 30 and a wet crushing device 31 are stacked one on top of the other, and are directly connected to each other. That is, the dry crushing device 30 has an inlet and an outlet, and the outlet of the dry crushing device 30 is directly connected to the inlet of the wet crushing device 31. The two may be connected by a tubular member. The dry crushing device 30 and the wet crushing device 31 are connected together so that water does not leak.

[0031] In this embodiment, a water level sensor 33 is provided between the dry crushing device 30 and the wet crushing device 31. The water level sensor 33 is located between the coarse crusher side breaking section 27 where the fermentation raw material of the dry crusher 30 is broken and the wet side breaking section 28 where the fermentation raw material of the wet crusher 31 is broken. The portion where the fermentation raw material is broken is, for example, the portion where the blade and the liner come into contact in a single-shaft crusher, or the portion where the blades mesh with each other in a twin-shaft crusher.

[0032] Other components that make up the crushing process section 10 include an input conveyor 35, a discharge conveyor 36, and a first pressure pump 37. The input conveyor 35 is a known bucket conveyor or belt conveyor, and transports food waste and the like brought in by truck or the like to the input port of the dry crushing device 30. The discharge conveyor 36 is, for example, a screw conveyor, and sends the slurry fermentation raw material to the first pressure pump 37. The first pressure pump 37 is a mixing pump.

[0033] Next, the human waste storage tank 11 will be described. The human waste storage tank 11 is a sealable tank, and has a human waste inlet 38 and human waste discharge sections 72 and 73.

[0034] Next, the storage tank 12 will be described. The storage tank 12 is composed of an introduction tank 40 and a main storage section 41. The introduction tank 40 is a small tank. The main reservoir 41 is a large tank. Both the introduction tank 40 and the main reservoir 41 are tanks with an open top, like a swimming pool. A lifting conveyor 42 is provided between the introduction tank 40 and the main storage section 41. A screen 43 is provided at the most downstream portion of the lifting conveyor 42. The main storage section 41 is provided with an agitator 45 .

[0035] The storage tank 12 is provided with accessories such as a food waste crusher 47 and an introduction conveyor 46. The introduction conveyor 46 is a screw conveyor.

[0036] Next, the connections between the various components will be described with reference to FIG. In addition to the piping components shown in the drawings, each pipe is provided with a strainer, an on-off valve, a check valve, etc. (not shown). First, we will explain the line that transports food waste (more precisely, slurry made by crushing food waste and mixing it with water). In the fermentation apparatus 1 of this embodiment, the crushing process section 10 and the fermenter 2 are connected by a first input conveying path 50. Specifically, the first input conveying path 50 is a conduit that connects the discharge side of the first pressure pump 37 of the crushing process section 10 to the upper side of the fermenter 2 via piping.

[0037] The first input conveying path 50 has a branch section 76 in the middle, to which a branch pipe 75 is connected. The branch pipe 75 opens above the storage tank 12. In this embodiment, a part of the first input conveying path 50 and the branch pipe 75 constitute a stockpiling conveying path 78 connecting the crushing process section 10 and the storage tank 12 as shown in FIG. The branch pipe 75 that is part of the stockpiling conveying path 78 may be connected to the side or bottom of the storage tank 12. The stockpiling conveying path 78 may be independent from the first input conveying path 50.

[0038] An on-off valve 51 is provided downstream (toward the fermenter 2) of the branching portion 76 of the first input conveying path 50. An on-off valve 53 is also provided in the branching pipe 75. The two on-off valves 51 and 53 function as conveying path switching means 57. The on-off valves 51 and 53 are used to switch the destination of the fermentation raw material and to change the division ratio of the slurry.

[0039] The storage tank 12 and the fermenter 2 are connected by a second input conveying path 55. A second pressure pump 56 is provided on the second input conveying path 55.

[0040] Next, we will explain the reflux conveying path 60 that returns the fermentation raw material containing moisture from the fermenter 2 side to the crushing process section 10 side. The fermentation apparatus 1 of this embodiment uses the digestion liquid in the fermenter 2, and the "fermentation raw material containing moisture" returned from the fermenter 2 to the crushing process section 10 also contains a large amount of undigested fermentation raw material, but for ease of explanation, the "fermentation raw material containing moisture" returned from the fermenter 2 to the crushing process section 10 will be referred to as the "digestion liquid."

[0041] As described above, the fermentation apparatus 1 of this embodiment has the temperature-controlled circulating conveying path 20. The temperature-controlled circulating conveying path 20 branches off downstream of the circulating pump 25 to form a reflux conveying path 60 that leads to the crushing process section 10. In this embodiment, the reflux conveying path 60 partially overlaps with the temperature-controlled circulating conveying path 20, and the digested liquid is sent therethrough by the same circulation pump 25. The fermentation apparatus 1 of this embodiment has a small number of parts because the pipes and the pump are shared. A flow path adjustment valve 67 is interposed in the return transfer path 60. The flow path adjustment valve 67 can adjust the opening degree by a motor, and can also be fully closed.

[0042] 1 and 2, the end of the return transport path 60 branches into branch pipes 60c and 60d, which are connected to the crushing section 15 and the first pressure-feed pump 37. An open / close valve 87 is provided in the branch pipe 60d leading to the first pressure-feed pump 37. The branch pipe 60c is further branched into branch paths 60a and 60b, which are connected to the dry crushing device 30 and the wet crushing device 31 of the crushing section 15. An on-off valve 86 is provided in the branch pipe 60a leading to the dry crushing device 30. As described above, the crushing section 15 is a connection between the dry crushing device 30 and the wet crushing device 31, and the end of the return transport path 60 is connected to both the dry crushing device 30 and the wet crushing device 31 (branch paths 60a, 60b) as shown in Figures 1 and 2.

[0043] By opening the on-off valve 86 and branching a portion of the digestive fluid sent via the circulating conveying path 60 into the branch path 60a, the digestive fluid can be poured into the dry crushing device 30, and the food waste remaining in the hopper and blades of the dry crushing device 30 can be flushed away.

[0044] Next, the piping related to the sewage storage tank 11 will be described. In this embodiment, one of the human waste discharge sections 72 is connected to a junction 71 of the return transport path 60 by a human waste introduction path 62 . In this embodiment, the night soil storage tank 11 is connected to the crushing process section 10 by a night soil inlet channel 62 and a return transport channel 60. In this embodiment, the night soil inlet channel 62 and the return transport channel 60 form a night soil supply transport channel 68. The human waste supply and transport channel 68 may be a channel independent from the return transport channel 60 . The night soil inlet path 62 is provided with a night soil pressure pump 63. An on-off valve 65 is provided at a junction 71 with the reflux conveying path 60, on the fermenter 2 side. In addition, an on-off valve 66 is also provided in the night soil inlet path 62. The on-off valves 65, 66 function as a switching means 81. A connecting pipe 77 is connected to the other human waste discharge section 73 of the human waste storage tank 11, and the connecting pipe 77 opens to the top of the introduction tank 40 of the storage tank 12. An on-off valve 83 is provided on the connecting pipe 77. The connecting pipe 77 may be connected to the side or bottom of the storage tank 12.

[0045] Next, the clean water circuit 85 will be described. In the fermentation apparatus 1 of this embodiment, clean water can be supplied to the introduction tank 40 and the main reservoir 41 of the storage tank. Furthermore, clean water can be supplied to the crushing section 15 as well.

[0046] The fermentation apparatus 1 of this embodiment has a control device 70 that controls the entire apparatus. As shown in FIG. 10, the control device 70 has a temperature adjustment control section and a return flow rate control section. The temperature control unit detects the temperature inside the fermenter 2 using a temperature sensor (not shown) and feeds this back to a water heater (not shown) and flow path adjustment valve 23 to control the temperature inside the fermenter 2. The return flow rate control unit controls the amount of digested liquid returned from the fermenter 2 based on a signal from the water level sensor 33.

[0047] Next, the flow of fermentation raw materials and the like in the fermentation apparatus 1 will be described. The fermentation apparatus 1 of this embodiment uses food waste and livestock manure as fermentation raw materials and ferments them in a fermenter 2 to produce methane gas. The raw food waste is collected in urban areas and transported to the fermentation device 1 by trucks A and B. Livestock manure is provided by farmers, transported by vacuum truck C, and collected in a manure storage tank 11. Human manure may also be used.

[0048] Food waste is usually collected on the side of the crushing process section 10, and is then fed into the crushing section 15 by a feed conveyor 35 and crushed (crushing process). At this time, the circulation pump 25 is driven, and all of the on-off valves (65, 67) provided on the reflux transport path 60 between the fermenter 2 and the crushing process section 10 are opened. As a result, as shown by the thick line in FIG. 5, the digested liquid in the fermenter 2 is supplied to the crushing process section 10 side.

[0049] In the crushing section 15, the digested liquid returned from the fermenter 2 and the newly added food waste are crushed and mixed. That is, newly added food waste is roughly crushed by the upper dry crusher 30 and sent to the downstream wet crusher 31 together with the digested liquid returned from the fermenter 2 . The chamber of the wet crushing device 31 is filled with digestive fluid and food waste, and the food waste is finely crushed in the liquid. The food waste is stirred by a rotary blade or the like and mixed with the digestive fluid to form a slurry. If necessary, clean water is supplied to the crushing section 15, but in the fermentation apparatus 1 of this embodiment, the digestive fluid is returned from the fermentation tank 2 to the crushing section 15, so even if clean water is supplied, only a small amount of clean water is sufficient.

[0050] Furthermore, if there is human waste in the human waste storage tank 11, the human waste is also supplied to the crushing process section 10. That is, in this embodiment, the human waste storage tank 11 is connected to the crushing process section 10 by a human waste supply and transport path 68 which is composed of a human waste inlet path 62 and a return transport path 60 . When supplying the human waste to the crushing process section 10, the on-off valve 66 of the human waste inlet channel 62 is opened to open the human waste supply and conveyance channel 68 extending from the human waste inlet channel 62 to the return conveyance channel 60. Then, the human waste pressure pump 63 is driven. As a result, the human waste in the human waste storage tank 11 is supplied to the crushing process section 10 together with the digested liquid supplied from the fermenter 2, as indicated by the thick line in FIG. Since human waste also contains a lot of water, the chamber of the wet crushing device 31 is filled with liquid, and the food waste is crushed into small pieces in the liquid. In addition, the solid content in the human waste can be crushed and turned into a slurry. The food waste mixed with the digestive fluid and human waste that has been finely crushed in the crushing section 15 and returned from the fermentation tank 2 is sent to the first pressure pump 37 by the discharge conveyor 36 as shown by the arrow in Figure 5, where it is pressurized by the first pressure pump 37 and fed into the fermentation tank 2 through the first input conveying path 50. If necessary, digestive fluid is also mixed into the first pressure pump 37.

[0051] In this embodiment, while the crushing operation is being performed in the crushing process section 10, a water level sensor 33 attached to the crushing section 15 monitors the water level in the crushing section 15. If the water level in the crushing section 15 falls below the position of the water level sensor 33, the flow path adjustment valve 67 provided in the return transport path 60 opens to supply more digestive fluid to the crushing section 15. Conversely, when the water level in the crushing section 15 exceeds the position of the water level sensor 33, the flow path adjustment valve 67 provided in the return transport path 60 is narrowed, thereby reducing the amount of digestive fluid supplied to the crushing section 15. As a result, the wet crushing device 31 (wet side breaking section 28) is filled with liquid, but the dry crushing device 30 (coarse crushing device side breaking section 27) is not filled with liquid, so food waste that floats on water does not float up inside the dry crushing device 30, and the food waste can be crushed in the dry crushing device 30 to turn it into slurry.

[0052] The above is the flow of fermentation materials in normal cases, but the amount of food waste collected varies. For example, during the day, workers who collect food waste are at work, and the amount of food waste collected is large. In contrast, at night, there are fewer workers on duty and less food waste is collected. Furthermore, the amount of food waste and human waste that should be put into the fermentation tank 2 also varies. That is, there are variations in both the demand for food waste and the like required for the fermenter 2 and the supply, which is the amount of food waste and the like collected.

[0053] In this embodiment, as a measure to level out this relationship between supply and demand, it is possible to switch between full-amount input, in which the entire amount of fermentation raw material crushed in the crushing process section 10 is transported into the fermentation tank 2, partial input, in which a portion of the fermentation raw material crushed in the crushing process section 10 is transported into the fermentation tank 2 and the remainder is transported into the storage tank 12, and additional input, in which the entire amount of fermentation raw material crushed in the crushing process section 10 and the fermentation raw material in the storage tank 12 are simultaneously transported into the fermentation tank 2. It is also possible to carry out storage of the entire amount of fermentation raw material crushed in the crushing process section 10 into the storage tank 12.

[0054] As a preferred method of use, the destination of the fermentation raw material is determined based on whether the amount of fermentation raw material being crushed per certain time in the crushing process section 10 is greater than the planned amount of fermentation raw material to be fed into the fermenter 2 per certain time. For example, a fixed time period of 3 hours or half a day is set, and the amount of fermentation raw material crushed in the crushing process section 10 during this time period is compared with the amount of fermentation raw material to be charged into the fermenter 2. When the amount of fermentation raw material being crushed in the crushing process section 10 per certain time is greater than the planned amount of fermentation raw material to be fed to the fermentation tank 2 per certain time, a partial feed is carried out in which part of the crushed fermentation raw material is fed to the fermentation tank 2 and the remainder is fed to the storage tank 12. When the amount of fermentation raw material being crushed in the crushing process section 10 per certain time is less than the planned amount of fermentation raw material to be added, additional addition is carried out by simultaneously transporting the fermentation raw material in the storage tank 12 to the fermentation tank 2 in addition to the entire amount of crushed fermentation raw material. The redirection of the fermentation raw material may be performed automatically or manually.

[0055] For example, if the amount of collected food waste is greater than the amount of food waste to be supplied to the fermentation tank 2, as shown by the arrow in Figure 6, part of the food waste crushed in the crushing process section 10 is sent to the storage tank 12 via the stockpile conveying path 78 (partial input). That is, the on-off valve 53 provided on the branch pipe 75 is opened to open the series of stockpiling conveying paths 78 that run from the first pressure pump 37 of the crushing process section 10 to the branch pipe 75 . As a result, as indicated by the arrow in FIG. 6, a portion of the food waste passing through the first input conveying path 50 enters the branch pipe 75 and is introduced into the storage tank 12.

[0056] When the fermentation tank 2 is full (when there is a lot of undigested material) and there is no need to supply new food waste, etc., the opening / closing valve 51 of the first input conveying path 50 is closed, and as shown by the thick line in Figure 7, the food waste crushed in the crushing process section 10 is introduced in its entirety into the storage tank 12 via the stockpiling conveying path 78 (all amount stored).

[0057] If the amount of collected food waste is even larger, truck B is parked next to storage tank 12 and placed in storage tank 12. The food waste discharged from truck B is finely crushed by food waste crusher 47. At this time, clean water is supplied to food waste crusher 47 from clean water circuit 85, and the food waste is mixed with the clean water to form a slurry. The slurry food waste is then introduced into introduction tank 40 of storage tank 12 by introduction conveyor 46. The slurry-like garbage in the introduction tank 40 is then transported to a screen 43 by a lifting conveyor 42, where the large pieces of garbage are removed, and only the finely crushed garbage is stored in the storage tank 12.

[0058] Conversely, when the stock of food waste is low, the crushed food waste and human waste stored in the storage tank 12 are supplied to the fermentation tank 2, as shown by the thick line in FIG. That is, as shown by the thick line in Figure 8, all of the food waste crushed in the crushing process section 10 is supplied to the fermentation tank 2, and in addition, the food waste in the storage tank 12 is also supplied to the fermentation tank 2 (additional input). If the food waste stock is completely depleted, only the crushed food waste and human waste stored in the storage tank 12 are supplied to the fermentation tank 2.

[0059] The temperature of the fermentation raw material in the fermenter 2 is controlled by the temperature-controlled circulating conveying path 20 to carry out methane fermentation (fermentation process). That is, as shown by the thick line in Figure 9, the fermentation raw material in the fermenter 2 is constantly taken out to the outside by the temperature-controlled circulating conveying path 20 and the temperature is controlled by the heat exchanger 26. The temperature of the hot water on the primary side of the heat exchanger 26 and the opening of the flow path adjustment valve 23 are controlled by feedback of the temperature detected by the temperature sensor attached to the fermenter 2, so that the temperature inside the fermenter 2 is kept constant.

[0060] The fermentation apparatus 1 of the embodiment described above is provided with a storage tank for temporarily storing the crushed fermentation raw materials, in consideration of the fact that there is a variance between the demand for food waste etc. required for the fermentation tank 2 and the supply of collected food waste etc. This technology can also be applied to fermentation apparatuses of other configurations. That is, the fermentation apparatus 1 of this embodiment has a crushing process section 10 that crushes the fermentation raw materials, and a fermentation tank 2, and the fermentation apparatus 1 introduces the fermentation raw materials crushed in the crushing process section 10 into the fermentation tank 2 and ferments the fermentation raw materials in the fermentation tank 2, and is characterized in that it has a storage tank 12 that temporarily stores the fermentation raw materials, a first input conveying path 50 connecting the crushing process section 10 and the fermentation tank 2, a stockpiling conveying path 78 connecting the crushing process section 10 and the storage tank 12, and a second input conveying path 55 connecting the storage tank 12 and the fermentation tank 2.

[0061] A preferred method of using this embodiment is as follows. That is, when the amount of received food waste and human waste is large, such as during the daytime, a portion of the crushed fermentation raw materials is stored in the storage tank 12. At night, when the amount of received food waste etc. decreases, the fermentation raw materials stored in the storage tank 12 are taken out and put into the fermentation tank 2. If a configuration were adopted in which all received fermentation raw materials were stored in storage tank 12 before being poured into fermenter 2, it would be necessary to receive extra food waste even after securing the amount needed for the night. Therefore, storage tank 12 would need to be considerably large. In contrast to this, the measure of this embodiment is to divert the fermentation raw material to the storage tank 12 side if the amount of fermentation raw material added to the fermenter 2 in the daytime exceeds the required amount. According to the configuration of this embodiment, the volume of the storage tank 12 does not need to be excessively large. [Explanation of symbols]

[0062] 1 Fermentation equipment 2 Fermentation tanks 10 Crushing process section 11 Sewage storage tank 12 Storage tank 15 Crushing section 20 Temperature-controlled circulation path 25 Circulation Pump 26 Heat exchanger 30 Dry crushing equipment (coarse crushing equipment) 31 Wet crushing equipment 33 Water level sensor 50 First input conveyor 55 Second input conveyor 57 Conveyor path switching means 60 Circulation transport channel 68 Human waste supply and transport route 78 Stockpile Transport Route

Claims

[Claim 1] A fermentation apparatus having a crushing process section for crushing a fermentation raw material and a fermentation tank, in which the fermentation raw material crushed in the crushing process section is introduced into the fermentation tank and the fermentation raw material is fermented in the fermentation tank, a reflux conveyance path for returning the water in the fermenter to the crushing process section; The crushing process section has a dry coarse crushing device and a wet crushing device, and the wet crushing device is arranged downstream of the coarse crushing device, and the fermentation raw material crushed by the coarse crushing device is further crushed by the wet crushing device, A fermentation apparatus characterized in that the reflux conveying path is connected to both the coarse crushing device and the wet crushing device.

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