Hydrothermal treatment equipment and hydrothermal treatment system

Abstract

The hydrothermal treatment apparatus (10) includes: a sealed container (11); a temperature measuring device (18) for measuring the internal temperature of the sealed container (11); an inlet pipe (14) for introducing water vapor into the sealed container (11); a solenoid valve (15) disposed on the inlet pipe (14); a pressure reducing device (17); and a control device (19). After organic waste is introduced into the sealed container (11), the control device (19) controls the hydrothermal reaction of the organic waste as follows: after the internal temperature is raised to a first temperature, the first temperature is maintained for a first time, and then the temperature is lowered; after the internal temperature drops from the first temperature to a second temperature, the second temperature is maintained for a second time (equal to or longer than the first time), and then the temperature is raised; after the internal temperature reaches a third temperature equal to the first temperature, the third temperature is maintained for a third time equal to the first time, and then the temperature is lowered.

Description

Technical Field

[0001] This invention relates to a hydrothermal treatment apparatus for treating waste containing organic matter and a hydrothermal treatment system for generating gas using the same apparatus. Background Technology

[0002] A system has been developed that uses high-temperature and high-pressure steam to hydrothermally react and dissolve organic waste such as kitchen waste (household waste), paper, wood and other woody waste, livestock manure, and sludge from urban waste and other household waste (hydrothermal treatment). The hydrothermally treated slurry is then used for gas generation based on microorganisms and fungi, such as methane fermentation (e.g., patent documents 1 and 2).

[0003] Patent Document 1 discloses a hydrothermal treatment device that performs hydrothermal treatment while simultaneously adding organic waste into a sealable container and stirring it. In Patent Document 1, when the temperature inside the container is less than 180°C, hard components such as the bones of organisms will not be fully dissolved; therefore, hydrothermal treatment is performed at 180°C and 1.0 MPa.

[0004] However, as described in Patent Document 2, when hydrothermal treatment is performed at temperatures above 150°C, the Maillard reaction of sugars and proteins contained in organic waste is promoted, and the formation of melanoidin, a nitrogen-containing antioxidant and a gas generation inhibitor, becomes significant. Therefore, Patent Document 2 discloses a system equipped with two hydrothermal treatment devices to reduce the amount of melanoidin.

[0005] First, hydrothermal treatment is performed in a first hydrothermal treatment device at a low temperature (e.g., 120°C) that inhibits the Maillard reaction. Next, the liquid generated by the first hydrothermal treatment device (conveniently referred to as "hydrothermal treatment liquid 1") is removed by solid-liquid separation, and the resulting solid is transferred to a second hydrothermal treatment device. Then, hydrothermal treatment is performed in the second hydrothermal treatment device at a high temperature (e.g., 220°C), and the liquid generated by the second hydrothermal treatment device (conveniently referred to as "hydrothermal treatment liquid 2") and the previously removed hydrothermal treatment liquid 1 are transferred to a fermentation device, where hydrothermal treatment liquid 1 and hydrothermal treatment liquid 2 undergo methane fermentation.

[0006] Since hydrothermal treatment solution 1 is generated through hydrothermal treatment at low temperatures that inhibit the Maillard reaction, the formation of melanoidins is, in principle, minimal. Furthermore, by removing hydrothermal treatment solution 1, the amount of nitrogen compounds transferred to the second hydrothermal treatment unit is reduced, thus decreasing the amount of melanoidins generated by the second hydrothermal treatment unit, which performs hydrothermal treatment at high temperatures that promote the Maillard reaction. Therefore, compared to a system where hydrothermal treatment is performed using only the second hydrothermal treatment unit without the first, the system with both units reduces the total amount of melanoidins contained in hydrothermal treatment solutions 1 and 2, resulting in reduced fermentation inhibition during methane fermentation.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2009-119378

[0010] Patent Document 2: Japanese Patent Application Publication No. 2020-163280 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] For example, when using organic waste collected by garbage trucks or stored in garbage bins at waste treatment plants to generate gas through microorganisms or fungi, it is preferable to selectively perform hydrothermal treatment on kitchen waste, paper, and plant matter. However, even if kitchen waste, paper, and plant matter are selectively removed from the organic waste, organic matter that does not contribute to or is unlikely to contribute to gas generation is usually not completely removed and remains. Inorganic matter such as metals and organic matter such as plastics do not contribute to or are unlikely to contribute to gas generation based on microorganisms, etc. Therefore, inorganic matter such as metals and organic matter such as plastics with a diameter greater than 6 mm are removed by solid-liquid separation after hydrothermal treatment (e.g., a sieve with a mesh size of 6 mm).

[0013] However, in this case, plastic particles finely processed to a diameter of 6 mm or less through hydrothermal treatment may be transferred to a gas generation device (e.g., a fermentation device) that uses microorganisms or fungi to generate gas, while still contained in the liquid separated after hydrothermal treatment (hereinafter referred to as the "hydrothermal treatment liquid"). The hydrothermal treatment liquid introduced into the gas generation device is a predetermined amount (fixed amount). Therefore, the more finely processed plastic is contained in the hydrothermal treatment liquid, the higher the proportion of plastic in that predetermined amount, and the lower the gas generation efficiency. Thus, the finely processed plastic does not contribute to gas generation based on microorganisms, etc. Furthermore, while it does not hinder gas generation based on microorganisms, it can be considered an obstacle to gas generation in terms of reducing the amount of gas generated from the predetermined amount of hydrothermal treatment liquid.

[0014] According to the inventors' experiments, when subjected to hydrothermal treatment at a constant temperature of 180°C for 60 minutes, approximately 65% ​​of the plastic contained in organic waste is refined to a size of less than 6 mm. Therefore, when performing solid-liquid separation through a sieve with a mesh diameter of 6 mm, most of the plastic contained in the organic waste is refined through the hydrothermal reaction and transferred to the gas generating device. This may prevent efficient gas generation, but this is expected to be improved.

[0015] Therefore, as an improvement, hydrothermal treatment at low temperatures could be considered. This is because, similar to melanoidins, the higher the temperature at which the hydrothermal reaction occurs, the greater the amount of fine plastics produced. However, in this case, according to Patent Document 1, the organic waste will not be sufficiently dissolved, and the amount of organic matter dissolved in the hydrothermal treatment liquid may decrease, potentially still preventing efficient gas generation.

[0016] It should be noted that in the technology of Patent Document 2, even if the amount of melanoidin produced can be reduced, the amount of fine plastics cannot be reduced, and the use of two hydrothermal treatment devices cannot avoid increasing the cost of the system.

[0017] Therefore, the object of the present invention is to provide a hydrothermal treatment apparatus and a hydrothermal treatment system that can dissolve organic waste through a hydrothermal treatment device and reduce the generation of melanoidins and fine plastics, which are two inhibitory substances related to gas generation.

[0018] Technical solution

[0019] The hydrothermal treatment apparatus of the present invention comprises: a sealed container having an inlet and an outlet for feeding organic waste; a temperature measuring device for measuring the internal temperature of the sealed container; an inlet pipe for introducing water vapor into the sealed container; a solenoid valve disposed on the inlet pipe for introducing the water vapor into the sealed container by opening the valve and stopping the introduction by closing the valve; a pressure reducing device for reducing the pressure inside the sealed container by releasing the water vapor from the sealed container containing the water vapor; and a control device for controlling the solenoid valve and the pressure reducing device based on the internal temperature measured by the temperature measuring device, thereby causing the organic waste in the sealed container to undergo a hydrothermal reaction.

[0020] Furthermore, during the hydrothermal reaction, after introducing water vapor into the sealed container to raise the internal temperature to a first temperature above the Maillard reaction promotion temperature, the control device maintains the first temperature for a first time. After the first time has elapsed, the control device immediately reduces the pressure, causing the internal temperature to drop from the first temperature. After the internal temperature drops from the first temperature to a second temperature above the hydrothermal reaction lower limit temperature through the cooling, the control device maintains the second temperature for a second time equal to or longer than the first time. After the second time has elapsed, the internal temperature immediately rises to a third temperature equal to the first temperature. The control device maintains the third temperature for a third time equal to the first time. After the third time has elapsed, the control device immediately reduces the pressure, causing the internal temperature to drop from the third temperature.

[0021] Furthermore, the hydrothermal treatment system of the present invention comprises: the hydrothermal treatment apparatus of the present invention; a solid-liquid separation apparatus for separating organic waste containing organic matter that has undergone a hydrothermal reaction through the hydrothermal treatment apparatus into a hydrothermal treatment liquid and a residue; and a gas generation apparatus for generating gas based on microorganisms using the hydrothermal treatment liquid separated by the solid-liquid separation apparatus as raw material.

[0022] After organic waste is introduced into a sealed container, the hydrothermal treatment apparatus of the present invention raises the temperature inside the sealed container to a first temperature above the Maillard reaction promoting temperature and maintains the first temperature for a first time. Then, it immediately cools down to a second temperature lower than the first temperature (however, a temperature above the lower limit temperature of the hydrothermal reaction) and maintains the second temperature for a second time. Then, it raises the temperature again to a third temperature and maintains the third temperature for a third time. Then, it immediately cools down from the third temperature. That is, if the temperature change after starting the hydrothermal treatment apparatus is recorded by using "→" to indicate the passage of time, it becomes "low (room temperature: when the apparatus is started)" → "high (hydrothermal reaction occurs above the Maillard reaction promoting temperature)" → "low (hydrothermal reaction occurs above the lower limit temperature of the hydrothermal reaction)" → "high (hydrothermal reaction occurs above the Maillard reaction promoting temperature)" → "low".

[0023] In other words, the internal temperature of the sealed container is first raised to a first temperature above the Maillard reaction promoting temperature to initiate the hydrothermal reaction of the organic waste. After a first period, the internal temperature of the sealed container is immediately lowered, then raised again to a third temperature equal to the first temperature, and then cooled down. Thus, during the hydrothermal reaction, temperature changes are applied to the organic matter containing the organic waste to subject its cell walls to multiple thermal shocks, promoting the solubility of the organic matter. That is, in the organic waste that undergoes a hydrothermal reaction using the hydrothermal treatment apparatus of the present invention, a portion of the cell walls of the organic matter is destroyed by the thermal shocks applied during the hydrothermal reaction. Therefore, compared to the case where the hydrothermal reaction only occurs at a constant second temperature, more organic matter is soluble even in the second temperature region of the present invention.

[0024] Furthermore, the second time for hydrothermal treatment at a second temperature lower than the first temperature is equal to or longer than the first time. Therefore, compared with the case of hydrothermal treatment at a constant temperature with only the first temperature, the amount of melanoidins and fine plastics are reduced.

[0025] Therefore, the hydrothermal treatment liquid generated by the hydrothermal treatment apparatus of the present invention has a high content of organic matter, and compared with the past, the content of melanoidins and fine plastics, which are obstacles to gas generation, is reduced.

[0026] Furthermore, the hydrothermal treatment apparatus system of the present invention uses the hydrothermal treatment liquid generated by the hydrothermal treatment apparatus of the present invention to generate gas, thus enabling efficient gas generation.

[0027] Invention Effects

[0028] According to the hydrothermal treatment apparatus of the present invention, even a single hydrothermal treatment apparatus can dissolve organic waste and reduce the generation of melanoidins and fine plastics, which are inhibitory substances for the generation of gases based on microorganisms and fungi.

[0029] Furthermore, according to the hydrothermal treatment system of the present invention, gas generation is achieved by using two hydrothermal treatment liquids with low obstruction, thus enabling efficient gas generation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the hydrothermal treatment system implemented in this way.

[0031] Figure 2 This is a schematic diagram illustrating a hydrothermal treatment apparatus for an embodiment.

[0032] Figure 3 This is a diagram used to illustrate the internal temperature control and stirring control of a closed container implemented by the hydrothermal treatment apparatus of the embodiment. Detailed Implementation

[0033] Hereinafter, a hydrothermal treatment apparatus and a hydrothermal treatment system having the apparatus will be described as embodiments with reference to the accompanying drawings. The configurations shown below are merely examples and are not intended to exclude various modifications or applications of techniques not explicitly shown. The configurations shown below can be modified and implemented in various ways without departing from the essential elements and spirit of the present invention.

[0034] Figure 1 This is a schematic diagram illustrating the hydrothermal treatment system 1 of this embodiment. The hydrothermal treatment system 1 includes: a hydrothermal treatment apparatus 10, which uses high-temperature and high-pressure steam to cause a hydrothermal reaction and dissolve organic waste; a solid-liquid separation apparatus 20, which separates the organic waste (hereinafter referred to as hydrothermal treated material) that has undergone a hydrothermal reaction in the hydrothermal treatment apparatus 10 into a hydrothermal treatment liquid and a residue; and a gas generation apparatus 30 (for example, a methane fermentation apparatus for methane fermentation), which uses the hydrothermal treatment liquid separated by the solid-liquid separation apparatus 20 as raw material and generates gas using microorganisms or fungi.

[0035] Examples of organic waste fed into the hydrothermal treatment unit 10 include household waste, wood-based waste, livestock manure, and sludge. Organic waste collected by garbage trucks or stored in garbage bins at waste treatment plants can be fed into the hydrothermal treatment unit 10 as is, or it can be fed into the unit after inorganic matter has been removed. Alternatively, kitchen waste, paper, or plant matter can be selectively removed from the organic waste and fed into the hydrothermal treatment unit 10. However, in either case, it is generally impossible to completely remove organic matter, i.e., plastics, that does not contribute to or is difficult to contribute to the generation of gases based on microorganisms, fungi, etc., from the organic waste.

[0036] It should be noted that the composition and control of the hydrothermal treatment device 10 will use... Figure 2 and Figure 3 This will be described in more detail later.

[0037] The solid-liquid separation device 20 is a device that separates liquids smaller than a certain particle size by allowing them to pass through while preventing solids larger than that particle size from passing through. It can use a screen with a specified mesh size (e.g., a 6mm diameter mesh), a screw press, or the like. The hydrothermal treatment liquid contains a large amount of organic matter containing organic waste, which becomes the raw material for gas generation in the gas generation device 30 described later.

[0038] It should be noted that the residue discharged from the solid-liquid separation device 20 is disposed of by waste or incineration.

[0039] The gas generating device 30 is, for example, a device that generates methane gas through methane fermentation. The hydrothermal treatment system 1 can reduce the amount of melanoidins and fine plastics in the hydrothermal treatment device 10 described later, thus enabling efficient gas generation.

[0040] It should be noted that the gas generating device 30 can be any device that uses hydrothermal treatment liquid as raw material and generates gas through microorganisms or fungi, or it can be a device that generates gases such as hydrogen.

[0041] Figure 2This is a schematic diagram illustrating the hydrothermal treatment apparatus 10 of this embodiment. The hydrothermal treatment apparatus 10 includes: a sealed container 11 capable of sealing its interior; an inlet pipe 14 for introducing water vapor into the sealed container 11; a solenoid valve 15 disposed on the inlet pipe 14; a temperature sensor 18 (temperature measuring device) for measuring the internal temperature of the sealed container 11; a pressure reducing device 17 for reducing the internal pressure of the sealed container 11 containing water vapor; a stirring device 16 for stirring organic waste fed into the sealed container 11; and a control device 19 for controlling the solenoid valve 15, the pressure reducing device 17, and the stirring device 16 based on the internal temperature measured by the temperature sensor 18.

[0042] The sealed container 11 has an inlet 12 and an outlet 13. Organic waste to be subjected to a hydrothermal reaction is fed into the sealed container 11 through the inlet 12. During hydrothermal treatment, the inlet 12 and outlet 13 are closed, and the sealed container 11 is sealed. By opening the outlet 13, the hydrothermally treated organic waste (hydrothermal treated material) is discharged to the outside of the sealed container 11, for example, by being transferred to the solid-liquid separation device 20 via a conveyor. It should be noted that since the organic waste is dissolved through hydrothermal treatment, the hydrothermal treated material is mostly in a slurry state.

[0043] The inlet pipe 14 is a pipe that connects one end to the sealed container 11 and introduces high-temperature steam from the other end. This steam can be, for example, steam used for power generation in the turbine of a waste incinerator. It should be noted that the temperature of the steam immediately after power generation is higher than 200°C. Therefore, depending on the setting of the first temperature C1 described later, sometimes the steam immediately after power generation may be introduced into the sealed container 11 as is, and sometimes it may be used after allowing the steam to cool naturally or after it has been properly cooled by a cooling device.

[0044] Solenoid valve 15 allows water vapor to be introduced into the sealed container 11 via inlet pipe 14 by opening the valve, and stops the introduction of water vapor by closing the valve. The opening and closing of solenoid valve 15 is controlled by control device 19.

[0045] Temperature sensor (temperature measuring device) 18 measures the internal temperature of the sealed container 11 and sends the internal temperature to control device 19.

[0046] The stirring device 16 agitates the organic waste to promote the hydrothermal reaction of the organic waste fed into the sealed container 11 and prevents scorching. The stirring device 16 may be, for example, equipped with stirring blades disposed within the sealed container 11 and rotating within the fixed sealed container 11, or it may be a device that rotates the sealed container 11 itself. The stirring speed of the stirring device 16 is controlled by the control device 19.

[0047] The pressure reduction device 17 reduces the internal pressure of the sealed container 11 by releasing a portion of the water vapor from the sealed container 11 containing water vapor to the outside of the sealed container 11 during hydrothermal treatment, or by releasing all of the water vapor from the sealed container 11 containing water vapor to the outside of the sealed container 11 after the hydrothermal treatment is completed. The degree of pressure reduction is controlled by the control device 19.

[0048] During hydrothermal treatment, the control device 19 opens or closes the solenoid valve 15 based on the internal temperature measured by the temperature sensor 18. Furthermore, it controls the pressure reducing device 17 to appropriately reduce the internal pressure of the sealed container 11, thereby controlling the internal temperature of the sealed container 11. Additionally, the control device 19 controls the stirring device 16 based on the internal temperature measured by the temperature sensor 18, increasing / decreasing the stirring speed of the organic waste fed into the sealed container 11.

[0049] So, using Figure 3 The control of the control device 19 will be explained.

[0050] After the organic waste is added to the sealed container 11 and the container 11 is sealed, the control device 19 opens the solenoid valve 15 to introduce high-temperature water vapor into the sealed container 11, thereby raising the internal temperature of the sealed container 11 to a first temperature C1 above the Maillard reaction promoting temperature. Then, the control device 19 closes the solenoid valve 15 or repeats the closing and opening of the valve as appropriate to maintain the first temperature C1 for a first time T1. At this time, the control device 19 controls the stirring device 16 to stir the organic waste in the sealed container 11 at a first stirring speed R1. Through this control, after the hydrothermal treatment begins, the hydrothermal reaction of the organic waste occurs at a temperature above the Maillard reaction promoting temperature, thus enabling the dissolution of the organic waste to begin smoothly.

[0051] It should be noted that, as mentioned above, according to Patent Document 2, the Maillard reaction promoting temperature is 150°C or higher. Furthermore, in Patent Document 2, 120°C is set as the temperature inhibiting the Maillard reaction. Therefore, it can be said that the lower limit of the Maillard reaction promoting temperature is a temperature higher than 120°C and lower than 150°C. Therefore, it is assumed that the midpoint between these two values, i.e., 135°C, is this lower limit. Therefore, here, the Maillard reaction promoting temperature is set to 135°C or higher, ideally 150°C or higher.

[0052] Then, after the first time interval T1, the control device 19 immediately controls the pressure reducing device 17 to release a portion of the water vapor inside the sealed container 11 to the outside of the sealed container 11. As a result, the control device 19 reduces the internal pressure of the sealed container 11, causing the internal temperature of the sealed container 11 to rapidly decrease from the first temperature C1. Ideally, at this point, the control device 19 closes the solenoid valve 15.

[0053] Through this control, the cell walls of the organic matter containing organic waste are subjected to thermal shock (first thermal shock) midway through the hydrothermal reaction, and a portion of the cell walls are destroyed. It should be noted that when cooling the internal temperature from the first temperature C1, it is ideal to cool it rapidly within a short time (within 0 to 10 minutes, ideally around 0 to 5 minutes). Therefore, it is also possible to force cooling of the sealed container 11 not only through the pressure reducing device 17, but also through a cooling device (not shown).

[0054] Here, the plastics contained in organic waste are also subject to thermal shock. However, comparing the cells of organic matter with plastics reveals differences in the presence or absence of moisture and thermal conductivity. Therefore, the impact of thermal shock on plastics is less than its impact on cells. Consequently, the miniaturization of plastics caused by this thermal shock does not actually occur.

[0055] After the internal temperature of the sealed container 11 drops from the first temperature C1 to a second temperature C2 above the lower limit temperature of the hydrothermal reaction, the control device 19 maintains the second temperature C2 for a second time T2 that is equal to or longer than the first time T1. At this time, the control device 19 controls the stirring device 16 to stir the organic waste in the sealed container 11 at a second stirring speed R2, which is lower than the first stirring speed R1.

[0056] Through this control, a longer hydrothermal reaction containing organic waste is carried out at the second temperature C2. However, since some cell walls have already been damaged by the first thermal shock, the solubility of organic matter containing organic waste is promoted compared to the case without the first thermal shock. Furthermore, the second temperature C2 is lower than the first temperature C1, thus suppressing the formation of melanoidins and fine plastics, which are inhibitors of gas generation, compared to the case where hydrothermal treatment is only performed at the first temperature C1, which is higher than the second temperature C2. Moreover, the stirring speed is also a low second stirring speed R2, thus further suppressing the formation of fine plastics compared to the case where hydrothermal treatment is performed at a high first stirring speed R1, which is higher than the second stirring speed R2.

[0057] It should be noted that before reaching the second temperature C2 from the first temperature C1, the control device 19 has stopped the pressure reduction achieved by the pressure reducing device 17. Furthermore, the control device 19 causes the solenoid valve 15 to close or, appropriately, repeatedly close and open to maintain the second temperature C2 for a second time T2. Moreover, since water vapor is used in the hydrothermal reaction, the lower limit temperature of the hydrothermal reaction is set to 100°C, which is the temperature at which water vapor is generated under atmospheric pressure.

[0058] also, Figure 3The value of the second stirring speed R2 is shown to be greater than 0 rpm, but the second stirring speed R2 can also be set to 0 rpm if the organic waste will not be burned.

[0059] Then, after a second time interval T2, the control device 19 immediately opens the solenoid valve 15 to introduce water vapor into the sealed container 11, thereby raising the internal temperature of the sealed container 11 to a third temperature C3, equal to the first temperature C1. Through this control, the cell walls of the incompletely soluble organic matter containing organic waste are further subjected to a thermal shock (second thermal shock) during the second time interval T2, and a portion of the cell walls of the incompletely soluble organic matter is destroyed. Therefore, organic matter that is not easily soluble, such as bone, will also gradually become soluble through the first and second thermal shocks (multiple thermal shocks in the hydrothermal reaction).

[0060] Then, the control device 19 closes the solenoid valve 15 or repeatedly closes and opens it to maintain the third temperature C3 at a third time T3 equal to the first time T1. At this time, the control device 19 controls the stirring device 16 to stir the organic waste in the sealed container 11 at a third stirring speed R3, which is faster than the second stirring speed R2 and equal to (or slightly slower than) the first stirring speed R1.

[0061] Then, after the third time interval T3, the control device 19 immediately controls the pressure reducing device 17 to release the water vapor inside the sealed container 11 to the outside of the sealed container 11. As a result, the control device 19 reduces the internal pressure of the sealed container 11, causing the internal temperature of the sealed container 11 to drop from the third temperature C3. Alternatively, in addition to using the pressure reducing device 17 to force cooling the sealed container 11, a cooling device can also be used to force cooling the sealed container 11.

[0062] Here, Figure 3 The diagram shows that the hydrothermal treatment ends and the hydrothermal treatment device 10 stops immediately after the third time T3. Therefore, after the third time T3, the control device 19 immediately controls the pressure reducing device 17 to release all the water vapor inside the sealed container 11 to the outside, thereby reducing the internal pressure of the sealed container 11. Furthermore, after the third time T3, the control device 19 immediately stops the stirring device 16. That is, Figure 3 The reaction time T shown is defined as the time from when the internal temperature reaches the first temperature C1, in other words, from the start of the first time T1 to the end of the third time T3.

[0063] but, Figure 3 As just one example, hydrothermal treatment can also continue after the third time interval T3. In this case, Figure 3The reaction time T shown will naturally be longer. The reaction time T is the time from the start point of the first time T1 until the hydrothermal reaction of the hydrothermal treatment device 10 ends.

[0064] For example, it can also be done after passing through Figure 3 After the third time T3, the same control as the first time T1 and the second time T2 is applied again, that is, the same thermal shock control as the first and second thermal shocks is applied. In other words, multiple thermal shocks can be applied more than twice within the reaction time T, that is, in the middle of the hydrothermal reaction. The more times the thermal shocks occur in the hydrothermal reaction, such as 3 or 4 times, the more soluble organic materials, such as bones, will be soluble at the lower second temperature C2.

[0065] It should be noted that, in this case, after the third time period T3, the control device 19 immediately controls the pressure reducing device 17 to release a portion (not all) of the water vapor inside the sealed container 11 to the outside of the sealed container 11, thereby reducing the internal pressure of the sealed container 11 and lowering the internal temperature of the sealed container 11 from the third temperature C3. Furthermore, in this case, the control device 19 can continue the stirring performed by the stirring device 16 at any time.

[0066] According to the inventors, the effects of the present invention can theoretically be obtained through the above-described configuration and controls.

[0067] Furthermore, according to the inventors, under the following conditions, with a reaction time T of 60 minutes, a first temperature C1 of approximately 180°C, a second temperature C2 of approximately 165°C, a third temperature C3 of approximately 180°C, a first time T1 of 5 to 10 minutes, a second time T2 of approximately 30 minutes, a third time T3 of 5 to 10 minutes, a first stirring speed R1 of approximately 80 rpm, a second stirring speed R2 of substantially 0 rpm (approximately 1 rpm), and a third stirring speed R3 of approximately 80 rpm, the following experimental results were obtained: the amount of plastic refined to a diameter of less than 6 mm was approximately 45% of the total amount of plastic in the organic waste fed into the sealed container 11.

[0068] On the other hand, when hydrothermal treatment was performed as described above, with the internal temperature of the sealed container 11 set to a constant value of only 180°C, the reaction time set to 60 minutes, and the stirring speed set to a constant value of only 30 rpm, the following experimental results were obtained: the amount of plastic refined to a diameter of less than 6 mm was about 65% of the total amount of plastic in the organic waste fed into the sealed container 11.

[0069] Comparing the results of these two experiments, although the former is considered to have a more gradual temperature change over time and a slightly smaller impact from thermal shock, it still yielded a value of about 45%, which can be considered a better result than the latter.

[0070] That is, according to the hydrothermal treatment apparatus 10 of the present invention, by appropriately setting the first temperature C1, the second temperature C2, the third temperature C3, the first time T1, the second time T2, and the third time T3, the temperature change over time can be made more rapid, and the effect of thermal shock can be increased. Therefore, compared with the past, the amount of plastic refined to a diameter of less than 6 mm can be reliably reduced relative to the total amount of plastic in the organic waste fed into the sealed container 11.

[0071] Furthermore, when the hydrothermal treatment liquid of the hydrothermal treatment apparatus of the present invention is used as raw material and methane fermentation is carried out through a methane fermentation apparatus which is a gas generation device, methane gas can be generated more efficiently than in the past.

[0072] Through the above-described structure and control, the hydrothermal treatment apparatus of the present invention can dissolve organic waste and not only reduce the generation of melanoidins, which are inhibitors of gas generation, but also reduce the generation of fine plastics. Since it can reduce the amount of both inhibitory substances with a single hydrothermal treatment apparatus, it offers high cost-effectiveness.

[0073] Furthermore, the hydrothermal treatment system of the present invention, which uses the hydrothermal treatment apparatus of the present invention, can efficiently generate gas.

[0074] Explanation of reference numerals in the attached figures

[0075] 1: Hydrothermal treatment system;

[0076] 10: Hydrothermal treatment equipment;

[0077] 11: Sealed container;

[0078] 12: Input port;

[0079] 13: Discharge outlet;

[0080] 14: Import tube;

[0081] 15: Solenoid valve;

[0082] 16: Stirring device;

[0083] 17: Pressure reducing device;

[0084] 18: Temperature sensor (temperature measuring device);

[0085] 19: Control device;

[0086] 20: Solid-liquid separation device;

[0087] 30: Gas generating device (e.g., methane fermentation device).

Claims

1. A hydrothermal treatment apparatus, wherein the apparatus enables the smooth initiation of a hydrothermal reaction containing organic waste and reduces the generation of melanoidins and fine plastics, wherein... The hydrothermal treatment device has the following features: A sealed container with an inlet and an outlet for disposing of waste containing organic matter; A temperature measuring device for measuring the internal temperature of the sealed container; An inlet tube is used to introduce water vapor into the sealed container; A solenoid valve, configured in the inlet pipe, is used to introduce water vapor into the sealed container by opening the valve and to stop the introduction by closing the valve. A pressure-reducing device reduces the pressure inside a sealed container by releasing the water vapor from the sealed container into which the water vapor has been introduced. and The control device controls the solenoid valve and the pressure reducing device based on the internal temperature measured by the temperature measuring device, causing a hydrothermal reaction to occur in the organic waste inside the sealed container. During the hydrothermal reaction, after water vapor is introduced into the sealed container, thereby raising the internal temperature to a first temperature above the Maillard reaction promotion temperature, the control device maintains the first temperature for a first time. After the first time interval has elapsed, the control device immediately reduces the pressure, causing the internal temperature to drop from the first temperature. After the internal temperature is lowered from the first temperature to a second temperature above the lower limit temperature of the hydrothermal reaction by the cooling process, the control device maintains the second temperature for a second time that is equal to or longer than the first time. After the second time interval, the internal temperature immediately rises to a third temperature equal to the first temperature, and then the control device maintains the third temperature at a third time interval equal to the first time interval. After the third time period, the control device immediately reduces the pressure, causing the internal temperature to drop from the third temperature.

2. The hydrothermal treatment apparatus according to claim 1, wherein, The hydrothermal treatment device also includes a stirring device, which stirs the organic waste material that is fed into the sealed container. The control device controls the stirring device to stir at a first stirring speed during the first time period, not to stir or to stir at a second stirring speed slower than the first stirring speed during the second time period, and to stir at a third stirring speed equal to the first stirring speed during the third time period.

3. A hydrothermal treatment system, wherein the hydrothermal treatment system comprises: The hydrothermal treatment apparatus according to claim 1 or 2; A solid-liquid separation device separates organic waste that has undergone a hydrothermal reaction in the hydrothermal treatment device into a hydrothermal treatment liquid and a residue; and A gas generating device that uses the hydrothermal treatment liquid separated by the solid-liquid separation device as raw material to generate gas based on microorganisms.

4. The hydrothermal treatment system according to claim 3, wherein, The gas generating device is a methane fermentation device.

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