Hydrothermal treatment system

Abstract

The hydrothermal treatment system (1) comprises: a hydrothermal treatment device (10) for causing a hydrothermal reaction in waste containing organic matter; an adjustment tank (11) for humidifying the hydrothermally treated material after the hydrothermal reaction; a first transfer device (21) for transferring the humidified hydrothermally treated material; a pressurized separation device (12) for pressurizing the transferred hydrothermally treated material to separate the hydrothermally treated material into a hydrothermally treated liquid and a residue; a solubilization tank (13) for storing and heating the separated hydrothermally treated liquid; a second transfer device (22) for returning the heated and solubilized hydrothermally treated liquid to the adjustment tank (11); a methane fermentation device (14) for generating methane gas and digestion liquid using the hydrothermally treated liquid stored in the solubilization tank (13); a dehydrator (15) for separating the digestion liquid into dehydrated sludge and dehydrated separated liquid; and a waste liquid treatment device (16) for nitrifying and denitrifying the dehydrated separated liquid to generate reused water. The second transfer device (22) transfers the hydrothermally treated liquid stored in the solubilization tank (13) to the methane fermentation device (14) when the concentration of organic matter contained in the hydrothermally treated liquid reaches a predetermined concentration.

Description

Technical Field

[0001] The invention relates to a hydrothermal treatment system for generating methane gas from organic matter-containing waste. Background Art

[0002] A system has been developed that uses high-temperature, high-pressure steam to hydrothermally react and solubilize organic wastes such as municipal waste, household kitchen waste (domestic waste), woody waste such as paper and grass, livestock manure, and sludge (hydrothermal treatment). The organic wastes (hydrothermally treated products) after hydrothermal treatment are then separated into a liquid (hydrothermally treated liquid) such as a solution or slurry. This liquid is then used to generate gas, such as methane fermentation, using microorganisms or fungi (e.g., Patent Documents 1 and 2). In this system, a screen or a screw press, such as that described in Patent Document 3, can be used to separate the pancreatic juice solution from the hydrothermally treated products.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-119378

[0006] Patent Document 2: Japanese Patent Application Publication No. 2019-181397

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2011-200836 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Generally speaking, in organic waste collected by garbage trucks and stored in garbage chutes at garbage disposal plants, in addition to organic matter that contributes to gas production, inorganic matter such as organic matter that does not or only rarely contributes to gas production (such as plastics) and metals and glass are not completely removed and remain. Furthermore, the ratio of organic to inorganic matter contained in collected or stored organic waste, the ratio of organic matter that is actually kitchen waste and paper, and the ratio of organic matter that contributes to gas production to organic matter that has little to no contribution to gas production (i.e., the proportion of each of these various components in a given amount of organic waste) vary depending on the region, season, and time of day.

[0010] Furthermore, generally speaking, regardless of the ratio of each content to the organic waste, a predetermined amount of organic waste is hydrothermally treated in a hydrothermal treatment apparatus for a predetermined fixed time (prescribed time). Upon expiration of the prescribed time, the hydrothermal treatment is terminated, and the hydrothermally treated product is removed from the hydrothermal treatment apparatus. Therefore, depending on the ratio of each content to the organic waste, the properties of the removed hydrothermally treated product vary. For example, a hydrothermally treated product with low water content may be obtained, resulting in a sandy or powdery state, while a hydrothermally treated product with high water content may be obtained, resulting in a muddy or liquid state.

[0011] On the other hand, when using hydrothermal treatment liquid to carry out methane fermentation to generate methane gas, it is ideal that the tiny organic matter contained in the hydrothermal treatment material is contained in the hydrothermal treatment liquid as much as possible. Therefore, it is preferred that, as described in patent documentation 3, when separating hydrothermal treatment liquid from hydrothermal treatment material, a pressurized screw press is used. However, pressurizing the hydrothermal treatment material of low moisture content (for example, sandy) by a screw press may increase power consumption and may also cause a malfunction, so it is not preferred.

[0012] Furthermore, when using a hydrothermal treatment solution to generate methane gas, the concentration of minute organic matter contained in the solution is a crucial factor in improving gas generation efficiency. However, the concentration of this organic matter differs significantly between hydrothermally treated products containing high and low amounts of water, making stable gas generation difficult in methane fermentation equipment.

[0013] Therefore, an object of the present invention is to provide a hydrothermal treatment system capable of stably generating methane gas regardless of the ratio of contents contained in organic matter-containing waste.

[0014] Technical Solution

[0015] The hydrothermal treatment system of the present invention comprises: a hydrothermal treatment device for causing a hydrothermal reaction of waste containing organic matter; an adjustment tank for humidifying the hydrothermally treated product after the hydrothermal reaction; a first transfer device for transferring the hydrothermally treated product humidified by the adjustment tank; a pressurized separation device for pressurizing the hydrothermally treated product transferred by the first transfer device to separate the hydrothermally treated product into a hydrothermally treated liquid and a residue; a solubilization tank for storing and heating the hydrothermally treated liquid separated by the pressurized separation device; a second transfer device for returning the hydrothermally treated liquid heated and solubilized by the solubilization tank to the adjustment tank; a methane fermentation device for using the methane stored in the methane fermentation tank. The invention relates to a method for treating a hydrothermally treated liquid in a solubilizing tank to generate methane gas and a digestion liquid; a dehydrator to separate the digestion liquid into dehydrated sludge and a dehydrated separation liquid; and a waste liquid treatment device to perform at least nitrification and denitrification on the dehydrated separation liquid to generate reused water. The second transfer device returns the hydrothermally treated liquid stored in the solubilizing tank to the adjustment tank when the concentration of organic matter contained in the hydrothermally treated liquid is less than a specified concentration, and transfers the hydrothermally treated liquid to the methane fermentation device when the concentration of the organic matter is greater than the specified concentration, wherein the specified concentration is a concentration of organic matter suitable for generating methane gas by microorganisms or fungi.

[0016] Effects of the Invention

[0017] According to the present invention, methane gas can be stably generated regardless of the ratio of each content contained in organic matter-containing waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram showing a hydrothermal treatment system according to an embodiment.

[0019] Figure 2 It is a schematic diagram showing an example of the second equipment of the hydrothermal treatment system according to the embodiment. DETAILED DESCRIPTION

[0020] The hydrothermal treatment system of the present invention is described below with reference to the accompanying drawings. The following configurations are merely illustrative and are not intended to exclude variations or technical applications not explicitly described. The following configurations may be modified and implemented in various ways without departing from the essential components and the spirit of the present invention.

[0021] Figure 1This is a schematic diagram of a hydrothermal treatment system 1 according to this embodiment. The hydrothermal treatment system 1 is a system that uses high-temperature, high-pressure steam to hydrothermally react and solubilize organic waste (hereinafter referred to as "hydrothermal treatment"), and then uses a liquid (hereinafter referred to as "hydrothermally treated liquid"), such as a solution, mixed liquid, or slurry, separated from the organic waste after the hydrothermal treatment (hereinafter referred to as "hydrothermally treated product"), to generate gas using microorganisms and fungi.

[0022] The hydrothermal treatment system 1 includes at least a hydrothermal treatment device 10 , an adjustment tank 11 , a first transfer device 21 , a pressurized separation device 12 , a solubilization tank 13 , a second transfer device 22 , a methane fermentation device 14 , a dehydrator 15 , and a waste liquid treatment device 16 .

[0023] Then, the following Figure 1 All the components of the hydrothermal treatment system 1 shown will be described in detail.

[0024] The hydrothermal treatment device 10 is a device for performing hydrothermal treatment on waste containing organic matter. Examples of waste containing organic matter that can be fed into the hydrothermal treatment device 10 include kitchen garbage (domestic garbage), wood-based waste, livestock feces, and sludge discharged from households. Organic waste collected by garbage collection trucks and organic waste stored in garbage chutes of garbage disposal plants can be fed into the hydrothermal treatment device 10 as they are, or they can be fed into the hydrothermal treatment device 10 after inorganic matter is removed from these organic wastes. It is also possible to selectively extract kitchen garbage, paper, and grass containing organic matter suitable for gas generation from these organic wastes and feed the extracted kitchen garbage, paper, or grass into the hydrothermal treatment device 10. The hydrothermal treatment device 10 can also perform hydrothermal treatment on disposable diapers, which have become a problem in handling in facilities for the elderly in recent years.

[0025] It will be later seen that in the hydrothermal treatment system 1, even if the ratio of each content in a prescribed amount of organic-containing waste treated by the hydrothermal treatment device 10 through a single hydrothermal treatment varies greatly depending on the organic-containing waste treated in each hydrothermal treatment performed multiple times, methane gas (biogas) can be stably generated by the methane fermentation device 14 described later.

[0026] The hydrothermal treatment is performed for a predetermined time in the hydrothermal treatment apparatus 10 , and the hydrothermally treated product discharged from the hydrothermal treatment apparatus 10 is stored in the adjustment tank 11 .

[0027] The adjustment tank 11 is a device for adjusting the properties of the hydrothermally treated material discharged from the hydrothermal treatment device 10 by humidifying the material. It should be noted that, herein, "humidifying" the hydrothermally treated material includes not only wetting the hydrothermally treated material with water or liquid, but also immersing the hydrothermally treated material in water or liquid.

[0028] The hydrothermal treatment liquid stored in the solubilization tank 13 described later is poured into the adjustment tank 11, thereby humidifying the hydrothermally treated product stored in the adjustment tank 11. In addition to pouring the hydrothermal treatment liquid into the adjustment tank 11, tap water (not shown) or recycled water described later may be appropriately poured into the adjustment tank 11.

[0029] Furthermore, a stirring device may be provided in the adjustment tank 11 to stir and mix the hydrothermally treated product stored in the adjustment tank 11 and the injected liquid or water. When provided with a stirring device, the adjustment tank 11 can adjust the properties of the hydrothermally treated product in a short time. For example, if the hydrothermally treated product stored in the adjustment tank 11 is in the form of sand, the stirring device can be operated while the liquid or water is injected, thereby converting the hydrothermally treated product into a slurry in a short time.

[0030] The stirring device may be any device as long as it stirs and mixes the hydrothermally treated product stored in the adjustment tank 11 and the injected liquid or water by air stirring, mechanical stirring, or the like.

[0031] It should be noted that the hydrothermal treatment device 10 and the adjustment tank 11 are equipment for hydrothermally treating waste containing organic matter and humidifying and storing the hydrothermally treated product obtained by the hydrothermal treatment. They are components of the first equipment 2 for performing the first stage of treatment in the hydrothermal treatment system 1.

[0032] Although described later, the device that pressurizes the hydrothermally treated product stored in the first device 2 to separate the hydrothermally treated liquid (hereinafter referred to as "pressurized separation") and solubilizes the hydrothermally treated liquid obtained by this pressurized separation is the second device 3 that performs the second-stage treatment in the hydrothermal treatment system 1. Furthermore, the device that generates gas using the hydrothermally treated liquid solubilized in the second device 3 is the third device 4 that performs the third-stage treatment in the hydrothermal treatment system 1.

[0033] The first transfer device 21 is a device that transfers the hydrothermally treated product, which has been humidified in the adjustment tank 11 of the first device 2, to the second device 3. When the first device 2 and the second device 3 are located close to each other, for example, when the first device 2 and the second device 3 are located in the same or adjacent locations with a distance of less than approximately 500 meters between them, the first transfer device 21 is preferably a pipeline connected to the adjustment tank 11 of the first device 2 and the pressurized separation device 12 of the second device 3, and equipped with a pulverizing pump that pressure-feeds the hydrothermally treated product, whose properties have been adjusted in the adjustment tank 11, to the pressurized separation device 12. Generally, the pipeline is constructed by connecting multiple pipes to form a single path.

[0034] In this case, the hydrothermally treated product stored in the adjustment tank 11 of the first equipment 2 is pulverized by a pulverizing pump through a pipeline and transferred to the pressurized separation device 12 of the second equipment 3. When the hydrothermally treated product is transferred, the pulverizing pump can be used to pulverize the hydrothermally treated product, thereby reducing the load on the pressurized separation device 12 (for example, a screw press) described later.

[0035] It should be noted that, in the following, when two devices among the first device 2, the second device 3 and the third device 4 are set "closely", it means that the two devices are set in the same or different places with a distance between the two devices less than about 500m.

[0036] On the other hand, when the first facility 2 and the second facility 3 are remotely located, the first transfer device 21 is ideally a vehicle equipped with a storage tank (e.g., a vacuum truck). For example, if the first facility 2 and the second facility 3 are located approximately 500 meters or more apart, they can be considered "remotely located," regardless of whether they are located at the same or different sites. In this case, the hydrothermally treated product stored in the adjustment tank 11 of the first facility 2 is loaded onto the vehicle and transported to the pressurized separation device 12 of the second facility 3, where it is then fed into the pressurized separation device 12.

[0037] Here, the car may be a car driven by a person, or an autonomous car whose driving is controlled not by a person but by a computer such as artificial intelligence (so-called AI).

[0038] Alternatively, a central control room may be provided in the hydrothermal treatment system 1, and a person may remotely monitor the system using surveillance cameras while controlling the operation of the vehicle. In this case, if surveillance cameras are provided in the equipment, devices, and facilities included in the hydrothermal treatment system 1, these can be remotely monitored from the central control room, thereby improving the safety of the operation of the hydrothermal treatment system 1.

[0039] Furthermore, the hydrothermal treatment system 1 may be configured to control the operation of each of the equipment, devices, and facilities included in the hydrothermal treatment system 1 through a central control room, or the operation of the hydrothermal treatment system 1 may be fully automated by utilizing AI.

[0040] It should be noted that, in the following, when two devices among the first device 2, the second device 3 and the third device 4 are “remotely” arranged, it means that the two devices are arranged in the same or different places with a distance of about 500m or more from each other.

[0041] In the following, when a "car" is referred to, the car may be a car driven by a person or a car that drives itself. The car may also be a car controlled by a person through remote monitoring.

[0042] The pressurized separation device 12 of the second apparatus 3 is a device that pressurizes the hydrothermally treated product transferred from the adjustment tank 11 of the first apparatus 2 by the first transfer device 21, thereby separating the hydrothermally treated product into a hydrothermally treated liquid and a residue (the material remaining after the hydrothermally treated liquid is separated from the hydrothermally treated product). It should be noted that the hydrothermally treated liquid is also called a fermentation-suitable product, and the residue is also called a fermentation-unsuitable product.

[0043] The pressurized separation device 12 can be constructed as follows: Figure 2 As shown, a rotary drum screen 12A is arranged at the front end, and a screw press 12B is arranged at the rear end. Rotary drum screen 12A may be, for example, a punched metal drum screen device described in Japanese Patent No. 6384015, registered by Mitsubishi Heavy Industries & Chemicals, Ltd. Furthermore, screw press 12B may be, for example, a dehydration system described in FIG. 13 of Japanese Patent No. 6734496, registered by Mitsubishi Heavy Industries & Chemicals, Ltd.

[0044] In the pressurized separation device 12, the mesh size, opening ratio, and screw pitch (the distance between the screw and the discharge port) are carefully set because the moisture content and viscosity of the hydrothermally treated product affect the recovery rate of the hydrothermally treated liquid and the removal rate of fermentation-inappropriate substances. The dehydration system described in Figure 13 of the registered gazette of Japanese Patent No. 6734496, which changes the mesh size in response to changes in the properties of the hydrothermally treated product, is therefore suitable for use in the pressurized separation device 12. The pressurized separation device 12 can also adjust the pressure within the device in response to changes in the properties of the hydrothermally treated product, for example by increasing or decreasing the size of the discharge port.

[0045] In addition, the pressurized separation device 12 can also be used with Figure 2 It is different from the conventional screw press and is composed of only a single unit of the screw press.

[0046] exist Figure 2In the pressurized separation device 12, the hydrothermally treated product, transferred from the adjustment tank 11 of the first equipment 2 by the first transfer device 21, is first fed into the rotary drum screen 12A. The rotary drum screen 12A then separates a portion of the hydrothermally treated liquid from the hydrothermally treated product. The hydrothermally treated product, discharged from the rotary drum screen 12A, is then fed into the screw press 12B.

[0047] Therefore, compared to the case where the rotary drum screen 12A is not provided in the front stage (the case where the pressurized separation device 12 is only a single screw press), the screw press 12B in the rear stage pressurizes the hydrothermally treated material whose amount is reduced compared to the total amount of the hydrothermally treated material transferred by the first transfer device 21, thereby separating the hydrothermally treated material into the hydrothermally treated liquid and the remainder. Figure 2 The pressurized separation device 12 can achieve power reduction (electricity saving) of the screw press 12B.

[0048] It should be noted that a portion of the hydrothermal treatment liquid separated by the rotary drum screen 12A and the hydrothermal treatment liquid separated by the screw press 12B are both stored in the solubilization tank 13 of the second equipment 3 .

[0049] The solubilization tank 13 of the second device 3 is a device for storing and heating the hydrothermal treatment liquid separated by the pressure separation device 12 to solubilize the hydrothermal treatment liquid. The heating temperature can be set to about 40°C to 60°C, for example.

[0050] By solubilizing the hydrothermal treatment liquid in the solubilization tank 13, the insoluble solids (suspended solids, hereinafter referred to as "SS") suspended in the hydrothermal treatment liquid are converted into dissolved solids (hereinafter referred to as "DS"). Consequently, the proportion of SS in the total solids (hereinafter referred to as "TS"; TS = SS + DS) contained in the hydrothermal treatment liquid stored in the solubilization tank 13 decreases. Therefore, the solubilization tank 13 can be said to be a device that reduces the SS in the stored hydrothermal treatment liquid and increases the DS, thereby promoting acid fermentation.

[0051] Generally speaking, a larger amount of DS of organic matter in TS is more desirable for gas generation by microorganisms and fungi. TS, SS, or DS of the hydrothermal treatment liquid stored in the solubilization tank 13 can be measured by a dedicated measuring device (not shown).

[0052] Furthermore, similarly to the adjustment tank 11 , the solubilization tank 13 may be provided with a stirring device to stir the hydrothermally treated liquid stored in the solubilization tank 13 to promote solubilization of the hydrothermally treated liquid.

[0053] The second transfer device 22 is a device that, when the concentration of organic matter contained in the hydrothermally treated liquid stored in the solubilization tank 13 of the second device 3 is less than a specified concentration (for example, TS is about 10%, DS is about 6%), returns the hydrothermally treated liquid from the solubilization tank 13 to the adjustment tank 11 of the first device 2; and when the concentration of the organic matter reaches the specified concentration (substantially including a case where it is above the specified concentration. In addition, the specified concentration may also be a concentration with a range, such as TS of about 10% to 12%, DS of about 6% to 8%), transfers the hydrothermally treated liquid from the solubilization tank 13 to the methane fermentation device 14 of the third device 4.

[0054] The second transfer device 22 may be configured to automatically select one of the adjustment tank 11 and the methane fermentation device 14 as a transfer destination based on the measurement results of the above-mentioned measuring device, and transfer the hydrothermally treated liquid stored in the solubilization tank 13 to the selected transfer destination.

[0055] It should be noted that this predetermined concentration is set to a concentration of organic matter suitable for methane fermentation in the methane fermentation device 14 described later, that is, a concentration of organic matter suitable for generating methane gas by microorganisms or fungi. At this predetermined concentration, the pH (acidity) of the hydrothermally treated liquid stored in the solubilization tank 13 is acidic, less than 7, and ideally, is 5 or less.

[0056] Ideally, similar to the first transfer device 21, when the first device 2 and the second device 3 are arranged close to each other, the second transfer device 22 is a pipeline that is connected to the adjustment tank 11 of the first device 2 and the solubilization tank 13 of the second device 3, and is equipped with a pump that pressurizes the hydrothermal treatment liquid of the solubilization tank 13 to the adjustment tank 11.

[0057] On the other hand, when the first equipment 2 and the second equipment 3 are remotely located from each other, it is desirable that the second transfer device 22 is a vehicle (e.g., a vacuum cleaning vehicle) equipped with a storage tank, etc. In this case, the hydrothermal treatment liquid is transported from the solubilization tank 13 to the adjustment tank 11 by the vehicle.

[0058] In either case, the hydrothermal treatment liquid circulates between the first device 2 and the second device 3 via the second transfer device 22 .

[0059] In addition, ideally, when the second device 3 and the third device 4 are arranged close to each other, the second transfer device 22 is a pipeline that is connected to the solubilization tank 13 of the second device 3 and the methane fermentation device 14 of the third device 4, and is equipped with a pump that pressurizes the hydrothermal treatment liquid of the solubilization tank 13 to the inlet of the methane fermentation device 14.

[0060] It should be noted that when the first device 2, the second device 3 and the third device 4 are arranged close to each other, the second transfer device 22 can also be configured as follows: a switching device is provided in the middle of the pipeline connecting the solubilization tank 13 of the second device 3 and the adjustment tank 11 of the first device 2, and another pipeline branching from the pipeline is connected to the switching device and the inlet of the methane fermentation device 14 of the third device 4.

[0061] As described above, depending on the concentration of organic matter contained in the hydrothermal treatment liquid stored in the solubilization tank 13 of the second device 3, the second transfer device 22 can selectively select, through a switching device, to transfer the hydrothermal treatment liquid stored in the solubilization tank 13 through either the pipeline connecting the solubilization tank 13 of the second device 3 and the adjustment tank 11 of the first device 2 or the above-mentioned other pipeline.

[0062] On the other hand, when the second equipment 3 and the third equipment 4 are remote from each other, the second transfer device 22 is preferably a vehicle equipped with a storage tank, etc. (for example, a vacuum cleaning vehicle). In this case, the hydrothermal treatment liquid is transported from the solubilization tank 13 to the methane fermentation device 14 by the vehicle and is added to the inlet of the methane fermentation device 14.

[0063] It should be noted that, when the first device 2 and the second device 3 are located close to each other and the second device 3 and the third device 4 are located remotely from each other, the second transfer device 22 may be a pipeline for transferring the hydrothermal treatment liquid between the first device 2 and the second device 3, and a vehicle for transferring the hydrothermal treatment liquid between the second device 3 and the third device 4. In other words, the second transfer device 22 may serve as both a pipeline and a vehicle.

[0064] Similarly, when the first device 2 and the second device 3 are remotely located from each other and the second device 3 and the third device 4 are close to each other, in the transfer of the hydrothermal treatment liquid between the first device 2 and the second device 3, the second transfer device 22 is a car, and further, in the transfer of the hydrothermal treatment liquid between the second device 3 and the third device 4, the second transfer device 22 is a pipeline.

[0065] The second transfer device 22 returns the hydrothermally treated liquid to the adjustment tank 11 of the first device 2 until the concentration of the organic matter contained in the hydrothermally treated liquid stored in the solubilization tank 13 of the second device 3 reaches the predetermined concentration.

[0066] Therefore, the hydrothermally treated product stored in the adjustment tank 11 of the first device 2 can be humidified, so that the hydrothermally treated product can be easily transferred by the first transfer device 21, and the power of the pressurized separation device 12 of the second device 3 can be reduced.

[0067] In addition, the hydrothermal treatment liquid returned from the solubilization tank 13 of the second device 3 to the adjustment tank 11 of the first device 2 has been heated by the solubilization tank 13, so the hydrothermal treatment liquid can be injected into the adjustment tank 11 in the state of the heated temperature or in the state of maintaining a temperature higher than normal temperature even if it is slightly cooled due to natural heat dissipation, etc.

[0068] In this case, the returned hydrothermal treatment liquid can contribute to the adjustment of the properties of the hydrothermally treated product by promoting the solubilization of at least a portion of the hydrothermally treated product stored in the adjustment tank 11 .

[0069] Furthermore, in the hydrothermal treatment system 1, multiple hydrothermal treatments are performed sequentially in time. However, even if the ratio of each content in the organic waste to be hydrothermally treated by the hydrothermal treatment device 10 of the first device 2 is greatly different during each hydrothermal treatment, and there is a large deviation in the concentration of organic matter contained in the hydrothermal treatment liquid obtained by each hydrothermal treatment, the hydrothermal treatment liquid can be circulated between the first device 2 and the second device 3 by the above-mentioned return, thereby averaging the concentration of organic matter contained in the hydrothermal treatment liquid stored in the solubilization tank 13.

[0070] When the concentration of organic matter in the hydrothermally treated liquid stored in the solubilization tank 13 reaches a predetermined concentration, the hydrothermally treated liquid of predetermined concentration is transferred to the methane fermentation unit 14 by the second transfer unit 22. Therefore, the concentration of organic matter in the hydrothermally treated liquid fed to the methane fermentation unit 14 remains substantially constant with minimal variation, and the hydrothermally treated liquid contains a high amount of organic matter that contributes to the production of methane gas. Consequently, the methane fermentation unit 14 can stably produce methane gas.

[0071] In a methane fermentation device that uses organic matter as a raw material and produces methane gas by microorganisms or fungi, generally, two steps, namely, solubilization of the organic matter and acid fermentation, need to be carried out first within the device.

[0072] However, in the hydrothermal treatment system 1, when the concentration of organic matter contained in the hydrothermal treatment liquid stored in the solubilization tank 13 reaches the predetermined concentration, the above-mentioned two steps have already been performed and completed in the solubilization tank 13. Therefore, the methane fermentation device 14 can omit the solubilization step and the acid fermentation step, thereby rapidly generating methane gas.

[0073] Methane fermentation unit 14 of third facility 4 uses the hydrothermally treated liquid stored in solubilization tank 13 of second facility 3 to generate methane gas and digestion liquid. Methane fermentation unit 14 heats the hydrothermally treated liquid (to approximately 37°C or 55°C) to generate methane gas through methane fermentation. The remaining liquid manure (also known as fermentation residue or digestion sludge) after methane gas generation serves as digestion liquid.

[0074] If the hydrothermal treatment liquid stored in the solubilization tank 13 of the second equipment 3 contains a large amount of fiber components, such as paper, the fiber components will not be completely decomposed by the methane fermentation device 14, and some will remain and be discharged in the digestion liquid. Therefore, if the digestion liquid contains a sufficient amount of fiber components, the fiberizing liquid supply device 17 and the feces and urine receiving tank 18 described later are unnecessary in order to improve the dehydration efficiency of the dehydrator 15 described later.

[0075] The dehydrator 15 is a device (e.g., a screw press) that separates the digestate discharged from the methane fermentation unit 14 into dehydrated sludge and dehydrated separated liquid. The separated dehydrated sludge can be transferred to the waste incineration facility 20 described below for incineration. Meanwhile, the separated dehydrated separated liquid is transferred to the waste liquid treatment unit 16.

[0076] The waste liquid treatment device 16 is a device that performs at least nitrification and denitrification, i.e., biological treatment, on the dehydrated separated liquid separated by the dehydrator 15 to purify the dehydrated separated liquid and generate reusable water. Examples of the waste liquid treatment device 16 include biological treatment devices that perform nitrification and denitrification, and manure and urine treatment facilities.

[0077] The reused water generated by the waste liquid treatment device 16 can be supplied to the adjustment tank 11 of the first equipment 2 through a supply path 25 (for example, a pipeline).

[0078] Immediately after the operation of the hydrothermal treatment system 1 is started, no hydrothermal treatment liquid is stored in the solubilization tank 13 of the second device 3. Therefore, the hydrothermal treatment system 1 cannot return the hydrothermal treatment liquid to the adjustment tank 11, and cannot use the hydrothermal treatment liquid to humidify the hydrothermally treated product stored in the adjustment tank 11. Therefore, in this case, the hydrothermal treatment system 1 supplies recycled water from the waste liquid treatment device 16 to the adjustment tank 11, thereby humidifying the hydrothermally treated product stored in the adjustment tank 11, and enabling smooth transfer of the hydrothermally treated product by the first transfer device 21 and operation of the pressurized separation device 12 of the second device 3 from the start of the operation of the hydrothermal treatment system 1.

[0079] When the above-mentioned return is not possible, the hydrothermal treatment system 1 may also humidify the hydrothermal treatment product by injecting tap water into the adjustment tank 11. However, in order to improve the cost performance of the hydrothermal treatment system 1, it is ideal to use recycled water instead of tap water.

[0080] The above description has been given of the at least one structure of the hydrothermal treatment system 1. Figure 1 As shown, the hydrothermal treatment system 1 may further include the following devices and facilities.

[0081] The defibration liquid supply device 17 is a device that supplies the defibration liquid, which is a liquid obtained by defibration of paper (for example, waste paper such as old newspapers), to the digestion liquid discharged from the methane fermentation device 14 .

[0082] Because the fibrinolytic liquid supply device 17 mixes the fibrinolytic liquid with the digestive liquid, the resulting mixture of digestive liquid and fibrinolytic liquid is dehydrated in the dewatering machine 15. The fibrinolytic liquid contains a high fiber content, and the fiber in this mixture acts as a substitute for the dewatering agent, absorbing moisture from the mixture. This improves the dewatering efficiency of the mixture in the dewatering machine 15. It should be noted that this fiber content is discharged from the dewatering machine 15 as part of the dewatered sludge, resulting in an increased amount of dewatered sludge compared to a process where the fibrinolytic liquid is not mixed with the digestive liquid.

[0083] Furthermore, the fiber components contained in the defibration liquid do not contain nitrogen. Furthermore, when the water in the mixed liquid is absorbed, the nitrogen contained in the mixed liquid is also absorbed. Therefore, the nitrogen concentration in the dehydrated separated liquid separated by the dehydrator 15 is reduced. This reduces the load on the biological treatment in the waste liquid treatment device 16. The defibration liquid supply device 17 may also be composed of, for example, the paper supply device, defibration device, defibrated waste paper storage tank, and defibrated waste paper supply pump described in the registered gazette of Japanese Patent No. 5905364 of Mitsubishi Heavy Industries, Ltd.

[0084] The feces and urine receiving tank 18 is a water tank for storing feces and urine. The hydrothermal treatment system 1 utilizes the fact that feces and urine have a "C / N ratio" (the ratio of the amount of nitrogen contained in the liquid to the amount of carbon available as a nutrient source for microorganisms during denitrification during biological treatment) of approximately 3 to 5, and that they contain fiber.

[0085] Specifically, in the hydrothermal treatment system 1, feces and urine stored in the feces and urine receiving tank 18 are supplied to the methane fermentation device 14, the digestive fluid discharged from the methane fermentation device 14, or the waste liquid treatment device 16. It should be noted that feces and urine can be supplied to not only one of these three locations, but also two or all of these three locations.

[0086] In order to efficiently perform methane fermentation in the methane fermentation device 14, the nitrogen content of the hydrothermally treated liquid must be approximately 1000 mg / L or more and approximately 3000 mg / L or less. However, the nitrogen content of the hydrothermally treated liquid transferred from the solubilization tank 13 to the methane fermentation device 14 may not meet this requirement.

[0087] In this case, by supplying feces and urine from the feces and urine receiving tank 18 to the methane fermentation device 14 and mixing it with the hydrothermal treatment liquid, the feces and urine can compensate for the nitrogen deficiency contained in the hydrothermal treatment liquid transferred to the methane fermentation device 14. In other words, feces and urine are supplied to adjust the nitrogen balance during methane fermentation.

[0088] It should be noted that, by supplying feces and urine to the methane fermentation device 14 , the amount of carbon contained in the hydrothermal treatment liquid stored in the methane fermentation device 14 increases, but most of the carbon is converted into methane gas in the methane fermentation device 14 , so it does not have an adverse effect on the hydrothermal treatment system 1 .

[0089] Alternatively, the feces and urine from the feces and urine receiving tank 18 may be supplied not directly to the methane fermentation device 14 but upstream of the methane fermentation device 14, for example, to the adjustment tank 11 of the first device 2 or the solubilization tank 13 of the second device 3. In this case, the feces and urine are indirectly supplied to the methane fermentation device 14.

[0090] In addition, when the feces and urine in the feces and urine receiving tank 18 are supplied to the digestive fluid discharged from the methane fermentation device 14 to form a mixed liquid, the fiber components contained in the feces and urine function as a substitute for the dehydration aid, similar to the fiber components contained in the above-mentioned fibrillating liquid, and can improve the dehydration efficiency of the mixed liquid in the dehydrator 15.

[0091] If the hydrothermal treatment system 1 includes both the defibrillating liquid supply device 17 and the feces and urine receiving tank 18, then if the digestive fluid contains insufficient fiber and fiber needs to be supplemented to improve the dehydration efficiency, the fiber content of the defibrillating liquid and feces and urine can compensate for the deficiency. It should be noted that the hydrothermal treatment system 1 may include only one of the defibrillating liquid supply device 17 and the feces and urine receiving tank 18, or both.

[0092] Furthermore, in general, when performing biological treatment for denitrification of a liquid, efficient treatment is achieved when the C / N ratio of the liquid is approximately 2 to 3. Therefore, when biologically treating the dehydrated separated liquid using the waste liquid treatment device 16, if the C / N ratio of the dehydrated separated liquid is less than 2, it is preferable to increase the C / N ratio by supplying feces and urine from the feces and urine receiving tank 18 to the dehydrated separated liquid and mixing them.

[0093] When the dehydrated separated liquid is mixed with feces and urine to form a mixed liquid, the addition of feces to the dehydrated separated liquid increases both the carbon and nitrogen contents. However, as mentioned above, the C / N ratio of feces and urine is approximately 3 to 5, so the increase in carbon content is greater than the increase in nitrogen content. Therefore, even if the C / N ratio of the dehydrated separated liquid is less than 2, the C / N ratio of the mixed liquid can be easily adjusted to approximately 2 to 3 by mixing the dehydrated separated liquid with feces and urine. In other words, feces and urine are added here to adjust the C / N balance of the dehydrated separated liquid undergoing biological treatment.

[0094] The third transfer device 23 is a device that transfers the methane gas generated by the methane fermentation device 14 of the third equipment 4 to the gas utilization facility 19 described later.

[0095] When the methane fermentation device 14 and the gas utilization facility 19 are installed close to each other, the third transfer device 23 is ideally a pipeline that connects the methane fermentation device 14 and the gas utilization facility 19 and transfers the methane gas generated by the methane fermentation device 14 to the gas utilization facility 19.

[0096] On the other hand, when the methane fermentation unit 14 and the gas utilization facility 19 are remotely located, the third transfer device 23 is preferably a vehicle (truck) equipped with a cargo platform for loading gas cylinders, or a vehicle equipped with gas tanks. In this case, the methane gas generated by the methane fermentation unit 14 can be filled into gas cylinders or gas tanks, loaded or carried on the vehicle, and then transferred to the gas utilization facility 19.

[0097] Gas utilization facility 19 utilizes the methane gas generated by methane fermentation unit 14 of third equipment 4. Gas utilization facility 19 is, for example, a power plant that generates steam using the heat generated by burning methane gas or a mixture of other gases with methane gas in a boiler. This steam then rotates a steam turbine, generating electricity. In recent years, thermal power plants that use liquefied natural gas (LNG), primarily methane, as fuel have become the mainstream in order to reduce carbon dioxide emissions during combustion. Gas utilization facility 19 can also be designed as a power plant modeled after this thermal power plant.

[0098] The gas utilization facility 19 may be a power plant equipped with a gas turbine, a gas engine, a fuel cell, or the like, or a facility that reforms the methane gas to generate city gas.

[0099] When the gas utilization facility 19 is a power plant equipped with a gas engine, it is generally equipped with a heat recovery device for exhaust gas generated by the gas engine. The heat recovery device can generate hot water from the exhaust gas.

[0100] When the gas utilization facility 19 is a power plant that generates electricity through a steam turbine and at least any one of the first device 2, the second device 3 and the third device 4 is arranged close to the gas utilization facility 19, high-temperature water vapor, i.e., waste water vapor, produced after being used for power generation in the steam turbine of the gas utilization facility 19 can be utilized in the close first device 2, the second device 3 or the third device 4.

[0101] For example, when a gas utilization facility 19 equipped with a steam turbine is installed close to the first device 2, the gas utilization facility 19 and the first device 2 can be connected by a pipeline, and the waste water vapor can be transferred to the hydrothermal treatment device 10 of the first device 2 via the pipeline to be used as high-temperature and high-pressure water vapor or a part thereof for use in the hydrothermal treatment device 10.

[0102] Furthermore, when the gas utilization facility 19 equipped with a steam turbine is installed close to the second device 3, the gas utilization facility 19 and the second device 3 can be connected by a pipeline, and the waste water vapor can be transferred to the solubilization tank 13 of the second device 3 via the pipeline to be used for heating the hydrothermal treatment liquid stored in the solubilization tank 13.

[0103] Moreover, when the gas utilization facility 19 equipped with a steam turbine is installed close to the third device 4, the gas utilization facility 19 and the third device 4 can be connected by a pipeline, and the waste water vapor can be transferred to the methane fermentation device 14 of the third device 4 via the pipeline for heating the hydrothermal treatment liquid stored in the methane fermentation device 14.

[0104] Furthermore, when the gas utilization facility 19 equipped with a gas engine is installed close to the second device 3, the gas utilization facility 19 and the second device 3 can be connected by a pipeline, and the warm water generated by the above-mentioned heat recovery device can be transferred to the solubilization tank 13 of the second device 3 via the pipeline to be used for heating the hydrothermal treatment liquid stored in the solubilization tank 13.

[0105] Similarly, when the gas utilization facility 19 equipped with a gas engine is installed close to the third device 4, the gas utilization facility 19 and the third device 4 can be connected by a pipeline, and the warm water can be transferred to the methane fermentation device 14 of the third device 4 via the pipeline for heating the hydrothermal treatment liquid stored in the methane fermentation device 14.

[0106] As described above, the heating temperature of the solubilization tank 13 is about 40°C to 60°C, and the heating temperature of the methane fermentation device 14 is about 37°C or about 55°C. Therefore, when heating the solubilization tank 13 and the methane fermentation device 14, warm water is easier to handle than waste water vapor.

[0107] In this way, when the gas utilization facility 19 is equipped with a steam turbine, the waste water vapor discharged from the steam turbine can be used as a heat source in the hydrothermal treatment system 1. In addition, when the gas utilization facility 19 is equipped with a gas engine, the warm water generated by the above-mentioned heat recovery device can be used as a heat source in the hydrothermal treatment system 1, thereby further improving the cost-effectiveness of the hydrothermal treatment system 1.

[0108] The fourth transfer device 24 is a device for transferring the residue separated by the pressurized separation device 12 of the second equipment 3 to the waste incineration facility 20 described later.

[0109] When the second device 3 and the waste incineration facility 20 are arranged close to each other, it is ideal that the fourth transfer device 24 is a conveyor belt that is connected to the discharge outlet of the residue of the pressurized separation device 12 and the garbage chute of the waste incineration facility 20, and transfers the residue discharged from the pressurized separation device 12 to the garbage chute.

[0110] On the other hand, when the second equipment 3 and the waste incineration facility 20 are remotely located, the fourth transfer device 24 is preferably a vehicle such as a truck or a garbage truck. In this case, the residue discharged from the pressurized separation device 12 can be loaded or stored on the truck bed or the garbage truck and then transferred to the waste incineration facility 20.

[0111] The waste incineration facility 20 is a facility that incinerates waste using an incinerator. It can also incinerate the residue discharged from the pressurized separation device 12 of the second equipment 3 and the dehydrated sludge separated by the dehydrator 15. The waste incineration facility 20 uses the heat generated by the incinerator to generate high-temperature, high-pressure steam in a boiler. This high-temperature, high-pressure steam is used to rotate a steam turbine, thereby generating electricity.

[0112] When at least any one of the first device 2, the second device 3 and the third device 4 is arranged close to the waste incineration facility 20, the high-temperature water vapor, i.e., waste water vapor, which has been used for power generation in the steam turbine of the waste incineration facility 20 can be utilized in the close first device 2, the second device 3, and the third device 4.

[0113] For example, when the waste incineration facility 20 is installed close to the first device 2, a pipeline can be used to connect the waste incineration facility 20 and the first device 2, and the waste water vapor can be transferred to the hydrothermal treatment device 10 of the first device 2 via the pipeline to be used as high-temperature and high-pressure water vapor or a part thereof for use by the hydrothermal treatment device 10.

[0114] In addition, when the waste incineration facility 20 and the second device 3 are installed close to each other, a pipeline can be used to connect the waste incineration facility 20 and the second device 3, and the waste water vapor can be transferred to the solubilization tank 13 of the second device 3 via the pipeline to be used for heating the hydrothermal treatment liquid stored in the solubilization tank 13.

[0115] Moreover, when the waste incineration facility 20 and the third device 4 are installed close to each other, a pipeline can be used to connect the waste incineration facility 20 and the third device 4, and the waste water vapor can be transferred to the methane fermentation device 14 of the third device 4 via the pipeline for heating the hydrothermal treatment liquid stored in the methane fermentation device 14.

[0116] In this manner, the wastewater vapor from the waste incineration facility 20 can be effectively utilized as a heat source in the hydrothermal treatment system 1 , thereby further improving the cost-effectiveness of the hydrothermal treatment system 1 .

[0117] It should be noted that the hydrothermal treatment system 1 can be a system that does not have any of the four (1) defibrillating liquid supply device 17, (2) feces and urine receiving tank 18, (3) third transfer device 23 and gas utilization facility 19, (4) fourth transfer device 24 and waste incineration facility 20, or a system that only has any one, any two or any three of the four, or a system that has all four.

[0118] Description of Reference Numerals

[0119] 1: Hydrothermal treatment system;

[0120] 2: First device;

[0121] 3: Second device;

[0122] 4: Third device;

[0123] 10: Hydrothermal treatment device;

[0124] 11: Adjustment slot;

[0125] 12: pressurized separation device;

[0126] 12A: Rotary drum screen;

[0127] 12B: screw press;

[0128] 13: Soluble tank;

[0129] 14: Methane fermentation device;

[0130] 15: Dehydrator;

[0131] 16: Waste liquid treatment device (feces and urine treatment facilities);

[0132] 17: Fibrinolytic liquid supply device;

[0133] 18: feces and urine receiving trough;

[0134] 19: Gas utilization facilities;

[0135] 20: Waste incineration facilities;

[0136] 21: first transfer device;

[0137] 22: second transfer device;

[0138] a third transfer device;

[0139] a fourth transfer device;

[0140] Supply road.

Claims

1. A hydrothermal treatment system comprising: A hydrothermal treatment device to cause the waste containing organic matter to undergo a hydrothermal reaction; an adjustment tank for humidifying the hydrothermally treated product after the hydrothermal reaction; a first transfer device for transferring the hydrothermally treated product humidified by the adjustment tank; a pressurizing separation device for pressurizing the hydrothermally treated product transferred by the first transfer device to separate the hydrothermally treated product into a hydrothermally treated liquid and a residue; a solubilization tank for storing and heating the hydrothermal treatment liquid separated by the pressurized separation device; a second transfer device for returning the hydrothermal treatment liquid heated and dissolved in the solubilization tank to the adjustment tank; a methane fermentation device that uses the hydrothermal treatment liquid stored in the solubilization tank to generate methane gas and digestion liquid; A dehydrator, which separates the digestate into dehydrated sludge and dehydrated separated liquid; as well as A waste liquid treatment device is used to perform at least nitrification and denitrification on the dehydrated separated liquid to generate reused water, The second transfer device returns the hydrothermally treated liquid stored in the solubilization tank to the adjustment tank when the concentration of organic matter contained in the hydrothermally treated liquid is less than a specified concentration, and transfers the hydrothermally treated liquid to the methane fermentation device when the concentration of the organic matter is greater than or equal to the specified concentration, wherein the specified concentration is a concentration of organic matter suitable for generating methane gas by microorganisms or fungi.

2. The hydrothermal treatment system according to claim 1, wherein: The hydrothermal treatment system further includes a defibrillating liquid supply device for supplying a defibrillating liquid obtained by defibrillating paper to the digestive liquid.

3. The hydrothermal treatment system according to any one of claims 1 or 2, wherein: The hydrothermal treatment system also has a feces and urine receiving tank for storing feces and urine. The hydrothermal treatment system supplies the feces and urine from the feces and urine receiving tank to the methane fermentation device and mixes it with the hydrothermal treatment liquid, or mixes the feces and urine from the feces and urine receiving tank with the digestion liquid, or mixes the feces and urine from the feces and urine receiving tank with the dehydrated separation liquid.

4. The hydrothermal treatment system according to claim 3, wherein: The pressurized separation device is provided with a rotary drum screen at the front end and a screw press at the rear end. The hydrothermal treatment liquid separated by the rotary drum screen and the hydrothermal treatment liquid separated by the screw press are stored in the solubilization tank.

5. The hydrothermal treatment system according to claim 4, wherein: The hydrothermal treatment system further comprises: a third transfer device for transferring the methane gas generated by the methane fermentation device and a gas utilization facility for utilizing the methane gas transferred by the third transfer device; or a fourth transfer device and a waste incineration facility, wherein the fourth transfer device transfers the residue separated by the pressurized separation device, and the waste incineration facility incinerates the residue transferred by the fourth transfer device. When the hydrothermal treatment device and the adjustment tank are arranged close to the pressurized separation device and the solubilization tank, the first transfer device is a pipeline equipped with a pulverization pump, and the second transfer device is a pipeline equipped with a pump. When the hydrothermal treatment device and the adjustment tank are remotely located from the pressurized separation device and the solubilization tank, the first transfer device and the second transfer device are both automobiles. When the methane fermentation device and the gas utilization facility are installed close to each other, the third transfer device is a pipeline. When the methane fermentation device and the gas utilization facility are remotely located from each other, the third transfer device is a car. When the waste incineration facility is installed close to the pressurized separation device and the solubilization tank, the fourth transfer device is a conveyor belt. When the waste incineration facility is remotely located from the pressurized separation device and the solubilization tank, the fourth transfer device is a vehicle. The gas utilization facility includes a steam turbine or a gas engine, and supplies steam after being used for power generation in the steam turbine to at least one of the hydrothermal treatment device, the solubilization tank, and the methane fermentation device, or supplies warm water generated from exhaust gas generated by the gas engine to at least one of the solubilization tank and the methane fermentation device. The waste incineration facility includes a steam turbine, and supplies steam used for power generation in the steam turbine to at least one of the hydrothermal treatment device, the solubilization tank, and the methane fermentation device. The waste liquid treatment device is a feces and urine treatment facility, and the reused water is supplied to the adjustment tank.

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