Waste treatment system, waste treatment method and pellets

Abstract

To provide pellets from organic waste including plastics that have a calorific value equivalent to that of coal, contain almost no substances such as chlorine or potassium, and have a quality equivalent to the quality classification in terms of the mass fraction of total chlorine content specified by RPF, as well as a waste treatment system and waste treatment method capable of producing such pellets. [Solution] One aspect of the present invention provides a waste treatment system that includes a subcritical water treatment device that breaks down organic waste, including plastics, into smaller molecules to obtain a treated product, a gas discharge mechanism that discharges gas components from within the subcritical water treatment device, a torrefaction device that torrefaction-treating pellet raw material containing the treated product, and a pelletizing device that pelletizes the pellet raw material or the torrefaction-treating pellet raw material to obtain pellets.

Description

[Technical field]

[0001] The present invention relates to high-quality pellets obtained from organic waste including plastics, a waste treatment system and a waste treatment method for producing energy (pellets) from the organic waste, and in particular to pellets that are a coal substitute fuel that can be used in a wide variety of fields, and a waste treatment system and a waste treatment method capable of producing such pellets. [Background technology]

[0002] To date, most of the energy consumed by humans has been generated by burning fossil fuels, all of which release carbon dioxide and combustion products into the environment.

[0003] Japan has set a reduction target of reducing greenhouse gas emissions by 26.0% in FY2012 compared to FY2013 by reducing domestic greenhouse gas emissions and ensuring absorption. Following the adoption of the Paris Agreement at COP21, the Cabinet approved the Global Warming Countermeasures Plan in May 2016.

[0004] Meanwhile, the Ministry of the Environment revised the "Basic Policy for Comprehensive and Planned Promotion of Measures for the Reduction of Waste and Other Appropriate Treatment of Waste" based on the Waste Management Act on January 21, 2016. This policy sets targets from the perspective of waste-to-energy utilization, and calls for the effective use of waste as an energy source and the regional utilization of waste-to-energy.

[0005] However, at small and medium-sized municipal waste treatment facilities, the current situation is that waste-to-energy utilization is not being fully implemented due to factors such as a lack of accumulated know-how and high costs.

[0006] Methods for converting waste into solid fuel include technologies for producing solid fuels such as RDF (Refuse Derived Fuel) and RPF (Refuse Paper & Plastic Fuel) from waste. RDF is a solid fuel made primarily from combustible municipal waste. Its lower heating value is roughly half to two-thirds that of coal, due to the presence of foreign matter.

[0007] On the other hand, RPF is a solid fuel made primarily from waste paper and plastics collected as industrial waste. The lower heating value of RPF is higher than that of RDF, and is equivalent to that of coal. However, low-quality plastics that are heavily soiled or otherwise poorly made are not suitable for use as RPF, and the types of plastics that can be used as materials are limited.

[0008] RPF types and grades are classified by the Japan RPF Industry Association as RPF-coke and RPF, and RPF grades are further classified as A, B, and C. The quality of RPF is defined as follows: higher heating value of 25 MJ / kg or more, total chlorine mass fraction of Category A: 0.3% or less, Category B: more than 0.3% and 0.6% or less, Category C: more than 0.6% and 2.0% or less.

[0009] The Ministry of Economy, Trade and Industry and the Agency for Natural Resources and Energy's explanation of standard calorific values ​​and carbon emission coefficients by energy source (revised in 2018) (January 2020) states that the total calorific value (higher calorific value) of coal (imported anthracite) is 27.80 MJ / kg. Here, the higher heating value is the amount of heat generated when fuel is burned, the temperature is returned to the temperature before combustion, and the amount of heat included is the amount of energy generated when the steam generated changes into water (condenses) (heat of vaporization). On the other hand, the amount of heat obtained by subtracting the latent heat of condensation of the steam from the higher heating value is the lower heating value.

[0010] Therefore, there is a need to develop technology that can produce solid fuel from organic waste, including plastics, that has a stable calorific value equivalent to that of coal, a quality equivalent to the quality classification in terms of total chlorine mass fraction specified in the RPF, excellent hydrophobicity, water resistance, and safety in terms of preventing spontaneous combustion, and that can be transported and stored efficiently.

[0011] Furthermore, the effects of "population decline" and "low birthrate and aging society" are having a major impact on waste management in local governments. In other words, it will be extremely difficult to maintain waste treatment facilities on a scale appropriate for the current demographic trends into the future.

[0012] Moreover, financial pressures are already evident in many municipalities. The initial costs of necessary upgrades to waste treatment facilities, as well as future maintenance costs and the costs of dismantling and removing them, are all extremely high. For these reasons, many municipalities are putting off the problem by preserving their aging treatment facilities.

[0013] In addition, the waste currently being incinerated by local governments contains a large amount of plastic mixtures. If such waste is simply incinerated, the heat generated and toxic gases it emits can damage the incinerator. On the other hand, plastic industrial waste, which has been exported to China and other countries in the past, has been banned from being imported because it causes environmental pollution in the importing country itself. However, the industrial waste treatment facilities currently existing in Japan are unable to treat the entire amount of plastic waste, making it a major social issue.

[0014] Although local governments do not bear primary responsibility for the disposal of industrial waste, they are also asked to cooperate in its disposal. In addition, the disposal of combustible waste, including plastics, contributes to the increase in carbon dioxide emissions, and is therefore a major social issue on a global scale.

[0015] The method for treating industrial waste as described above involves incinerating combustible waste. However, as an alternative to incineration, a method is known in which subcritical water treatment is used to break down organic waste, including plastics, into smaller molecules and reduce its volume.

[0016] Subcritical water treatment is a method of solubilizing organic waste by contacting it with gaseous subcritical water at a high temperature below the critical temperature of water and a high pressure above the saturated water vapor pressure. Subcritical water treatment can also decompose packages and plastic containers that could not be decomposed by conventional low-molecular-weight treatments. Therefore, even when packaged food waste or food waste contained in plastic containers is reduced to low molecular weight substances, it can be solubilized together with the food waste without removing the packages or plastic containers. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Patent No. 6640268 Summary of the Invention [Problem to be solved by the invention]

[0018] However, simply solubilizing organic waste through such subcritical water treatment does not provide a very high efficiency in generating energy from the organic waste, and problems remain in terms of practicality.

[0019] There is a known treatment system that treats organic waste with subcritical water, and then ferments the resulting treatment product into methane. This treatment system requires large equipment and storage facilities. In addition, because the product (output) is a flammable gas, it is difficult to implement in urban areas under current laws and regulations such as the Building Standards Act, City Planning Act, and Fire Service Act.

[0020] There is also a known processing system in which organic waste is treated with subcritical water, and then passed through a solid-liquid separator, a dryer, a classifier, and a molding device to produce fuel pellets (see, for example, Patent Document 1). However, the fuel pellets obtained by the processing system described in Patent Document 1 do not have a stable calorific value equivalent to that of coal, and also contain large amounts of substances such as chlorine and potassium, and do not have the same quality as the quality classification for the total chlorine mass fraction defined by the RPF.

[0021] In addition, the composition of organic waste (paper, cloth, vinyl, synthetic resin, rubber, leather, wood, bamboo, straw, kitchen waste, non-combustible materials, etc.) varies depending on the collection region and time of year, and there is also the problem that the heat value of the treated material using subcritical water is prone to fluctuations.

[0022] In view of the above circumstances, the present invention provides pellets made from organic waste, including plastics, that have a calorific value equivalent to that of coal, contain almost no substances such as chlorine or potassium, and have a quality equivalent to the quality classification for the total chlorine mass fraction defined by the RPF, as well as a waste treatment system and waste treatment method capable of producing such pellets. [Means for solving the problem]

[0023] According to one aspect of the present invention, there is provided a waste treatment system comprising a subcritical water treatment device for breaking down organic waste, including plastics, into smaller molecules to obtain a treated material, a gas discharge mechanism for discharging gas components within the subcritical water treatment device, a semi-carbonization device for semi-carbonizing a pellet raw material including the treated material, and a pelletization device for pelletizing the pellet raw material or the semi-carbonized pellet raw material to obtain pellets.

[0024] It may be provided in any of the following ways: The waste treatment system further comprises a mixer that mixes the material to be treated with woody biomass to obtain the mixture as the pellet raw material. The gas discharge mechanism of the waste treatment system includes a suction device that sucks in the gas components in the subcritical water treatment device, and a particle removal device that is arranged between the suction device and the subcritical water treatment device and removes particle particles in the gas components. The waste treatment system further comprises a water treatment device for treating the gas components that have passed through the gas exhaust mechanism. The waste treatment system, wherein the water treatment device is a device that performs pressurized flotation treatment. The waste treatment system further comprises a foreign matter removal device for removing solid foreign matter from the treated material discharged from the subcritical water treatment device. The waste treatment system, wherein the semi-carbonization apparatus is a superheated steam generating apparatus that supplies superheated steam to the material to be treated in the subcritical water treatment apparatus. The waste treatment system further comprises a pressure reducing device for reducing the pressure inside the subcritical water treatment device in an open state, and a sterilization treatment device for sterilizing the gas discharged from the pressure reducing device. The waste treatment system further comprises a pellet generator that generates electricity by using the pellets as fuel. The waste treatment system further comprises a water maker that produces water from air using electricity generated by the pellet generator. At least one of the elements constituting the waste treatment system is configured as a freely movable unit. The waste treatment system, wherein the unit is housed within a container. A waste treatment method comprising the steps of: treating organic waste, including plastics, with subcritical water to reduce the molecular weight of the waste to obtain a treated material; separating the treated material from gas components; and semi-carbonizing and pelletizing a pellet raw material including the treated material to obtain pellets. The waste treatment method further comprises a step of mixing the treated material with woody biomass prior to the step of obtaining the pellets, to obtain a mixture of these as the pellet raw material. A pellet made by semi-carbonizing and pelletizing a pellet raw material including a product of subcritical water treatment of organic waste including plastics, and characterized in that the pellet has a higher heating value of 30 MJ / kg or more. The pellets have a total chlorine mass fraction of 0.3% or less as specified in JIS Z7311:2010. The pellet raw material is a pellet containing the material to be treated and wood biomass. Of course, this is not the case. Effect of the Invention

[0025] According to the present invention, it is possible to produce pellets from organic waste, including plastics, that have a calorific value equivalent to that of coal, contain almost no substances such as chlorine or potassium, and have a quality equivalent to the quality classification for the total chlorine mass fraction defined by the RPF. [Brief description of the drawings]

[0026] [Figure 1] 1 is a conceptual diagram showing the overall configuration of a first embodiment of a waste treatment system of the present invention. [Diagram 2] FIG. 2 is a conceptual diagram showing the overall configuration of a second embodiment of a waste treatment system according to the present invention. [Diagram 3] FIG. 4 is a conceptual diagram showing the overall configuration of a third embodiment of a waste treatment system according to the present invention. [Figure 4] FIG. 11 is a conceptual diagram showing the overall configuration of a fourth embodiment of a waste treatment system of the present invention. [Diagram 5] FIG. 13 is a conceptual diagram showing the overall configuration of a fifth embodiment of a waste treatment system of the present invention. [Figure 6] FIG. 2 is a conceptual diagram showing a state in which a subcritical water treatment device is unitized in the waste treatment system of the present invention. [Figure 7] 1 is a conceptual diagram showing a configuration of a water treatment device in a waste treatment system of the present invention. [Figure 8] 1 is a conceptual diagram showing the configuration of a pellet generator in a waste treatment system of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment.

[0028] First Embodiment First, a first embodiment of a waste treatment system according to the present invention will be described. FIG. 1 is a conceptual diagram showing the overall configuration of a first embodiment of a waste treatment system according to the present invention. A waste treatment system (organic waste treatment system including plastics) 100 shown in FIG. 1 has a subcritical water treatment device 2 that performs subcritical water treatment on organic waste 1 including plastics, and a high-pressure boiler 3.

[0029] The high-pressure boiler 3 includes a combustion chamber for burning fuel and a heat exchanger disposed within the combustion chamber. The high-pressure boiler 3 transfers heat generated by combustion in the combustion chamber to water passing through a heat exchanger to generate high-temperature, high-pressure steam. The high-pressure boiler 3 then supplies this steam to the subcritical water treatment device 2. The water supplied to the high-pressure boiler 3 can be not only tap water, but also recycled digestive fluid.

[0030] The subcritical water treatment device 2 includes a pressure vessel and a shaft rotatably disposed within the pressure vessel and having an agitating blade attached thereto. The organic waste 1 in the pressure vessel is transported toward the outlet of the pressure vessel and stirred by the rotation of the stirring blades as the shaft rotates. At this time, the organic waste 1 is treated with subcritical water by steam supplied from a high-pressure boiler 3.

[0031] Subcritical water treatment is a method of reducing organic waste 1 to smaller molecules by contacting the organic waste with gaseous subcritical water under high temperature and pressure, which is below the critical temperature of water and above the saturated water vapor pressure. This reduction in molecular weight decomposes the organic waste 1 to obtain a treated product. The temperature of the gaseous subcritical water is preferably about 180 to 230° C., and more preferably about 190 to 220° C. The pressure is preferably about 15 to 25 atm, and more preferably about 18 to 22 atm.

[0032] The specific temperature and pressure of the gaseous subcritical water are preferably about 200° C. and about 20 atmospheres. The time for the subcritical water treatment is appropriately set depending on the type of organic waste 1 and is not particularly limited, but is preferably about 0.1 to 10 hours, and more preferably about 0.5 to 5 hours.

[0033] This subcritical water has a dielectric constant of 15 to 45, which is equivalent to the dielectric constant of low-polarity solvents. Therefore, it can dissolve many organic substances. Furthermore, subcritical water has an ion product of 1×10 -12 ~1×10 -11 Mol 2 / kg 2 The proportion of hydrogen ions that separate into hydrogen ions and hydroxide ions is high, and therefore the hydrogen ions exhibit a strong hydrolysis effect. The dielectric constant of water at room temperature and atmospheric pressure is about 80, and the ionic product of water at a temperature of about 25°C and atmospheric pressure is 1 x 10 -14 Mol 2 / kg 2 It is.

[0034] Subcritical water can also decompose plastics such as polypropylene and polyethylene due to the strong hydrolysis action described above. Therefore, it can also decompose and convert into smaller molecules paper, vinyl, plastic, polystyrene foam, infectious medical waste, clothing containing synthetic fibers, discarded food still in its packaging, and other substances that cannot normally be hydrolyzed by anaerobic or aerobic bacteria.

[0035] In the present invention, the organic waste 1 (treated material) that has been reduced in molecular weight has a solubilization rate of preferably 50% or more, more preferably 70% or more, and even more preferably 85% or more. Here, the solubilization rate is the ratio of soluble organic matter to the total organic matter before pelletization, and a higher value indicates that the organic matter has been broken down into smaller molecules.

[0036] Specific examples of the decomposition of the organic waste 1 into smaller molecules include decomposition into carbohydrates, proteins, fats, and other sugars, amino acids, higher fatty acids, and the like. Moreover, the subcritical water treatment in the subcritical water treatment apparatus 2 is a batch treatment by its nature, but in the present invention, it can be carried out at a rate of several batches per day.

[0037] A gas discharge mechanism that discharges gas components within the subcritical water treatment device 2 is connected to the subcritical water treatment device 2. This gas discharge mechanism is composed of a centrifugal separator (particle removal device) 9 and a vacuum device (suction device) 10, which are arranged in this order from the subcritical water treatment device 2 side. The vacuum device 10 sucks gas components inside the subcritical water treatment device 2. The gas components include gases such as water vapor, water-soluble substances accompanying the water vapor, and the like.

[0038] The gas components also contain fine particles, which are separated into gas and solids and removed when passing through a centrifugal separator (particle remover) 9 arranged between the vacuum device 10 and the subcritical water treatment device 2. The particulate removal device may be any device capable of separating gas and solid matter, and may be configured, instead of the centrifugal separator 9, with, for example, a filter device, a column device, a scrubber device, an adsorption device, or the like.

[0039] It is possible to reduce the moisture content of the treated material (pellet raw material) and reduce water-soluble substances (chlorine, potassium, etc.) by sucking out the gas components in the subcritical water treatment device 2. This makes it possible to obtain pellets of the same quality as the quality classification for the total chlorine mass fraction specified by the RPF.

[0040] In addition, when contaminated waste, contaminated soil, contaminated forest resources, etc. contaminated with radioactive substances are treated with subcritical water, there is an advantage that radioactive substances with relatively long half-lives such as cesium discharged from the subcritical water treatment device 2 can also be removed.

[0041] A water treatment device 14 is connected to the vacuum device 10. This water treatment device 14 is a device that performs water treatment on the gas components discharged from the vacuum device 10. In other words, the water treatment device 14 performs water treatment on the gas components that have passed through the gas discharge mechanism. Water treatment methods are broadly divided into physicochemical treatment and biochemical treatment, and the treatment method can be selected according to the purpose and standards of water quality treatment.

[0042] It is preferable to use a device that performs pressure flotation treatment as the water treatment device 14. FIG. 7 is a conceptual diagram showing the configuration of a water treatment device in a waste treatment system of the present invention. The water treatment device 14 shown in FIG. 7 includes a flocculation reaction tank 60, a flotation tank 61, a circulation pump 62, and a pressurized water tank 63. The gas components discharged from the subcritical water treatment apparatus 2 by the suction of the vacuum device 10 are subjected to coagulation treatment in the coagulation reaction tank 60 by adding a coagulant.

[0043] Next, in the flotation tank 61, the pressurized water from the pressurized water tank 63 is returned to atmospheric pressure, generating a large amount of fine bubbles due to the air that is generated. Water containing fine bubbles (hereinafter also referred to as "fine bubble water") is mixed with water containing suspended solids, and the suspended solids are captured by the fine bubbles. Thereafter, the buoyancy of the bubbles is utilized to cause them to float, and the floated fine bubbles and suspended solids are removed by mechanical scraping or the like, and clean treated water is discharged from the portion below.

[0044] A part of the treated water can be recycled as circulating water by a circulating pump 62. In addition, in the pressurized flotation treatment, the fine bubble water is also called fine bubble water. By making this fine bubble water into CO2 fine bubble water using CO2 instead of air and treating the gas components, the decontamination effect can be enhanced.

[0045] A sterilization / deodorization device (sterilization treatment device) 22 that sterilizes the gas discharged from the pressure reduction device is connected to water treatment device 14. The pressure reduction device reduces the pressure inside subcritical water treatment device 2, which is in an open state. This sterilization / deodorization device 22 can deodorize the gas components discharged from subcritical water treatment device 2 after water treatment and release them into the atmosphere. The sterilization / deodorization device 22 can be composed of, for example, an adsorption filter device. The treated water in which the water-soluble substances are dissolved is diluted as necessary and then discharged.

[0046] In addition, a classifier (foreign matter remover) 8 is connected to the subcritical water treatment apparatus 2. This classifier 8 removes solid foreign matter from the treatment material discharged from the subcritical water treatment apparatus 2. Examples of the classifying device 8 include a trommel and a sieving device. Of these, it is preferable to use a trommel. The use of a trommel not only removes foreign matter but also makes the treated material uniform.

[0047] The organic waste 1 used in the present invention includes general waste, and therefore may contain various foreign matter depending on the waste collection conditions of each local government or company. Examples of foreign matter include pieces of pottery (ceramics), bottle fragments (glass fragments), metal fragments, etc. By removing such foreign matter, it is possible to prevent the treated material (pellet raw material) from becoming non-uniform and the calorific value from decreasing.

[0048] The classifier 8 is connected to the solidifier / semi-carbonizer 4. Although not shown, the solidifier / semi-carbonizer 4 is equipped with a mixer that mixes the material to be treated with woody biomass 5 to obtain the mixture as pellet raw material. The mixture (pellet raw material) containing the material to be treated may be semi-carbonized by a semi-carbonization device that semi-carbonizes the pellet raw material containing the material to be treated, and then pelletized by a solidification device (pelletization device), or vice versa. Here, the pelletization device pelletizes the pellet raw material or the semi-carbonized pellet raw material to obtain pellets.

[0049] The composition of waste varies depending on the region and time of collection, and the calorific value of the treated material obtained by subcritical water treatment varies. In order to compensate (adjust) this fluctuation in calorific value, woody biomass 5 is mixed with the treated material. This makes it possible to satisfactorily produce pellets (referred to as "solid fuel" in the figure) that have a stable calorific value equivalent to that of coal and have the same quality as the quality classification for the total chlorine mass fraction specified by the RPF in an extremely short time. Depending on the type of waste, etc., if pellets having the above-mentioned quality can be produced using only the treated material, the mixing of woody biomass 5 can be omitted.

[0050] Examples of woody biomass 5 that can be used in the present invention include the ends (so-called "offcuts") that are generated when logs (timber) cut down from the mountains are processed into lumber (boards, posts, etc.), crushed log bark, and waste paper made from wood. The resulting pellets will generate CO2 when burned, but woody biomass 5 is carbon neutral because it simply returns the CO2 absorbed by the trees in the forest back into the atmosphere. Therefore, the "biomass energy fuel" such as the pellets obtained by the present invention can be said to be an ecological fuel.

[0051] The pellets obtained in the present invention are not particularly limited in size, shape, etc., so long as they can be suitably used as fuel for a target device (for example, a pellet generator 6 described below). In addition, the pellets obtained by semi-carbonization according to the present invention are made of highly pure carbonized material with a reduced moisture content and volatile organic component content, and therefore have an increased calorific value and excellent durability and storage stability in the natural environment.

[0052] The semi-carbonization process using the semi-carbonization apparatus is carried out by subjecting the pellet raw material to a heat treatment in an atmosphere with a low oxygen concentration. The heat treatment temperature is preferably about 200 to 700° C., and more preferably about 200 to 300° C. The heat treatment time is preferably about 1 to 24 hours, and more preferably about 1 to 3 hours. By carrying out the semi-carbonization treatment under such conditions, the pellet raw material can be reliably semi-carbonized. Here, the semi-carbonized state refers to a state in which about half of the pellet raw material is converted into carbide.

[0053] As the solidification device, for example, a strand type extruder, a hot cut type extruder, or the like can be used.

[0054] In this embodiment, at least one of the elements constituting the waste treatment system 100 is configured as a freely movable unit. FIG. 6 is a conceptual diagram showing a state in which the subcritical water treatment apparatus in the waste treatment system of the present invention is unitized. 6, the subcritical water treatment apparatus 2 is housed in a container 40 and loaded onto a large vehicle 41. That is, in the example of Fig. 6, the unit is housed inside the container 40. Note that M in the figure represents a motor, and the organic waste 1 is transported or stirred in the subcritical water treatment apparatus 2 by the rotational force thereof.

[0055] The subcritical water treatment apparatus 2 accommodated in the container 40 in this manner is separated from other components of the waste treatment system 100, and can be easily moved together with the container 40. Similarly, the other components of the waste treatment system 100 described above and below can also be accommodated in containers, making them easily movable. In this case, the waste treatment system 100 can be transported and temporarily assembled and installed according to the region where the organic waste 1 is to be treated, making it possible to implement the system in urban areas. After treatment, the waste treatment system 100 can be disassembled and transported.

[0056] Furthermore, the subcritical water treatment apparatus 2 shown in FIG. 6 can be operated as a batch treatment with an operation time of about 2 hours. Therefore, the vehicle-mounted subcritical water treatment device 2 can travel to multiple locations in search of the equipment subsequent to the solidification / semi-carbonization device 4, which are installed almost permanently, thereby contributing to a significant reduction in initial capital investment.

[0057] The waste treatment system 100 can be configured to be able to execute the AI ​​process 15 . The AI ​​processing 15 can collect and store various data (temperature, pressure, flow rate, valve opening / closing degree, electricity consumption, water consumption, etc.) by installing sensors in the group of devices used in the waste treatment system 100. Then, the AI ​​processing 15 can optimize and streamline the operation timing and time of each device group using an integrated algorithm that utilizes AI based on the accumulated data.

[0058] Next, a method of using the waste treatment system 100 described above (the waste treatment method of the present invention) will be described. [1] First, organic waste 1 including plastics is placed into a subcritical water treatment device 2 as the material to be treated. [2] Next, high-temperature, high-pressure steam is generated in the high-pressure boiler 3 and supplied to the subcritical water treatment device 2. At this time, in the subcritical water treatment device 2, the organic waste 1 comes into contact with high-temperature and high-pressure steam (gaseous subcritical water), and is broken down into smaller molecules by its high hydrolysis action, producing a treated product. In other words, in this process, organic waste including plastics is treated with subcritical water.

[0059] [3] At this time, the gas components in the subcritical water treatment device 2 are discharged by the vacuum device 10 (solid-gas separation of the treated material), and fine particles contained in the gas components are removed when passing through the centrifugal separator 9. That is, in this process, solid-gas separation is performed between the treated material and the gas components. [4] Next, the gas components discharged from the vacuum device 10 are treated by the water treatment device 14. The gas components discharged from the water treatment device 14 are released into the atmosphere after passing through a sterilization / deodorization device 22. In addition, the treated water is diluted as necessary and then discharged.

[0060] [5] Meanwhile, the treated material in the subcritical water treatment device 2 is discharged from an outlet and supplied to a classifier 8. In the classifier 8, solid foreign matter mixed in the treated material is removed. [6] Next, the treated material is supplied to a solidification / semi-carbonization device 4, where it is first mixed with woody biomass 5 to obtain a mixture (pellet raw material containing the treated material). That is, in this process, prior to the process of obtaining pellets, the treated material and woody biomass are mixed to obtain a mixture of these as pellet raw material. That is, the pellet raw material contains the treated material and woody biomass. [7] Next, the mixture is semi-carbonized in a semi-carbonizer and pelletized in a solidifier. Through the above process, pellets (also called "black pellets") are obtained. In other words, in this process, the pellet raw material containing the treated material is semi-carbonized and pelletized to obtain pellets.

[0061] <Second embodiment> Next, a second embodiment of the waste treatment system of the present invention will be described. The following describes the waste treatment system of the second embodiment, focusing on the differences from the waste treatment system of the first embodiment, and omits a description of the similarities. FIG. 2 is a conceptual diagram showing the overall configuration of a second embodiment of a waste treatment system according to the present invention. The waste treatment system 200 shown in Figure 2 is similar to the waste treatment system 100, except that it includes a pellet generator 6 that generates electricity using pellets as fuel, and a water maker 7 that makes water from air using the electricity generated by the pellet generator 6.

[0062] In the second embodiment, the pellets (solid fuel) produced in the solidification device / semi-carbonization device 4 are used as fuel for power generation in a pellet generator 6 . Here, LP gas may be used as a supplementary fuel in the pellet generator 6. The pellet generator 6 has a mechanism that uses pellets as fuel. Figure 8 is a conceptual diagram showing the configuration of the pellet generator in the waste treatment system of the present invention. The pellet generator 6 shown in FIG. 8 is composed of a fuel supply device 81, a gasification device 82, an ash discharge device 83, a gas cooling device 84, a gas filter 85, a gas engine 86, and a generator 87.

[0063] In the pellet generator 6, first, the fuel supply device 81 arranged at the most upstream position transports the pellets into the gasifier 82. This gasifier 82 has a vaporization function and vaporizes the transported pellets. At this time, the components that are not vaporized are discharged to the outside by the ash discharge device 83. The gas components vaporized in the gasifier 82 are then transferred to a gas cooler 84 and cooled.

[0064] The cooled gas components are passed through a gas filter 85 to remove unnecessary components, and are then transferred to a gas engine 86 installed downstream. This gas engine 86 runs on the gas components cooled in a gas cooler 84 as fuel, and uses this power to operate a generator 87. In this manner, electricity is generated in the generator 87. As described above, LP gas may be used as a supplemental fuel for this power generation. The electricity may be temporarily charged into a storage battery, power storage equipment, next-generation automobile, or the like (not shown).

[0065] The electricity generated is used to produce water in a water maker (a machine that makes water from air) 7, and can also be used as a small-scale power generation facility to provide a good energy source for the local area. For this water maker 7, for example, a product manufactured by Japan Israel Research Institute under the product name "Watergen", model number GEN-350 (capacity: 900 L / Day) or model number GENNY (capacity: 27 L / Day), a product manufactured by Aquam Co., Ltd. under the product name "Eco Blue", model number 30sME / 30JP (capacity: 10-15 L / Day), etc. can be used.

[0066] Furthermore, the waste treatment system 200 can optimize the balance between supply and demand of electricity in the community surrounding the local government or business entity that has introduced it. In particular, the waste treatment system 200 can function as a small-scale power generation facility that serves as a good energy source for the local area, and by using AI processing (new information technology) 15, it is possible to aggregate multiple small-scale power generation facilities and storage facilities scattered around homes, buildings, factories, etc., and remotely control them to function as a single power plant, instead of a large-scale power plant.

[0067] <Third embodiment> Next, a third embodiment of the waste treatment system of the present invention will be described. Hereinafter, the waste treatment system of the third embodiment will be described focusing on the differences from the waste treatment system of the first embodiment, and a description of the similar points will be omitted. FIG. 3 is a conceptual diagram showing the overall configuration of a waste treatment system according to a third embodiment of the present invention. The waste treatment system 300 shown in FIG. 3 is similar to the waste treatment system 100, except that it is capable of treating infectious waste.

[0068] In the waste treatment system 300, a pressure reducing device (not shown) for reducing the pressure inside the subcritical water treatment device 2 in an open state is disposed in the middle of a line connecting the subcritical water treatment device 2 and the sterilization / deodorization device 22. Here, medical waste generated during medical procedures (defined as "infectious waste" under the Waste Management and Public Cleansing Act) may have come into contact with pathogens carried by the patient, and therefore poses the risk of biological hazards.

[0069] According to the waste treatment system 300 of the third embodiment, even when treating such infectious waste, by operating the pressure reducing device when feeding the waste into the subcritical water treatment device 2, it is possible to prevent the dispersion of pathogens into the surrounding environment. Moreover, the air exposed to the infectious waste in the subcritical water treatment apparatus 2 is exhausted to a pressure reducing device, and then supplied to the sterilization / deodorization apparatus 22 where it is sterilized.

[0070] When the sterilization / deodorization device 22 is configured with an adsorption filter, it is preferably heated to about 150 to 250° C. in order to sufficiently enhance the sterilization effect. With the above configuration, the risk of infection for workers can be reduced, and the infectious waste can be smoothly introduced into the subcritical water treatment apparatus 2.

[0071] In addition, the use of conventional small-scale incineration equipment for infectious waste, etc., is becoming difficult due to the tightening of regulations on tioxins. In addition, as a general rule, infectious waste should be disposed of within facilities such as medical institutions, and ideally it should be disposed of promptly at the location where it is generated. The waste treatment system 300 of the third embodiment is preferable because it can satisfy the above requirements.

[0072] <Fourth embodiment> Next, a fourth embodiment of the waste treatment system of the present invention will be described. Hereinafter, the waste treatment system of the fourth embodiment will be described focusing on the differences from the waste treatment system of the first embodiment, and a description of the similarities will be omitted. FIG. 4 is a conceptual diagram showing the overall configuration of a fourth embodiment of a waste treatment system according to the present invention. The waste treatment system 400 shown in FIG. 4 is similar to the waste treatment system 100, except that the configuration of the torrefaction apparatus is different.

[0073] In this embodiment, the semi-carbonization apparatus is configured with a superheated steam generator 20 that supplies superheated steam to the material to be treated in the subcritical water treatment apparatus. Specifically, the semi-carbonization apparatus is configured with the superheated steam generator 20 that is connected to a high-pressure boiler 3 and generates high-temperature steam (superheated steam) at a relatively low pressure. For this reason, in this embodiment, instead of the solidification device / semi-carbonization device 4, a solidification device 21 connected to the classifier 8 is provided. Steam from the high-pressure boiler 3 is converted to superheated steam by the superheated steam generator 20 and supplied to the subcritical water treatment device 2. This makes it possible to semi-carbonize the input organic waste 1 while it is contained within the subcritical water treatment device 2. This makes it possible to simplify the treatment process and reduce the size of the waste treatment system 400.

[0074] The temperature of the superheated steam is preferably about 200 to 800° C., and more preferably about 500 to 700° C. The pressure of the superheated steam is more preferably about atmospheric pressure. The treatment time with superheated steam is preferably about 1 to 24 hours, and more preferably about 1 to 3 hours. By carrying out the semi-carbonization treatment under the above conditions, the pellet raw material can be reliably semi-carbonized. The superheated steam generator 20 may be disposed inside or outside the subcritical water treatment device 2 .

[0075] <Fifth embodiment> Next, a fifth embodiment of the waste treatment system of the present invention will be described. Hereinafter, the waste treatment system of the fifth embodiment will be described, focusing on the differences from the waste treatment system of the first embodiment, and a description of the similarities will be omitted. FIG. 5 is a conceptual diagram showing the overall configuration of a waste treatment system according to a fifth embodiment of the present invention. The waste treatment system 500 shown in FIG. 5 is similar to the waste treatment system 100, except that a low-pressure boiler 31 and a steam compressor 30 are used instead of the high-pressure boiler 3.

[0076] The low-pressure boiler 31 converts the supplied water into steam, which is pressurized by passing through the steam compressor 30 , and can be supplied in this state to the subcritical water treatment device 2 . According to this configuration, it is possible to reduce the number of high-pressure and high-temperature parts in the entire waste treatment system 500, and the waste treatment system 500 can be made more compact. In particular, the low-pressure boiler 31 can be designed to be lower in height than the high-pressure boiler 3, and is therefore suitable for mounting on a vehicle.

[0077] The pellets of the present invention are produced by semi-carbonizing and pelletizing a pellet raw material including a treated product of subcritical water treatment of organic waste including plastics. The pellet raw material may include the treated product and woody biomass depending on the quality of the desired pellets. The pellets have a higher heating value of 25 MJ / kg or more, and preferably 27 MJ / kg or more. The upper limit of the higher heating value of the pellets is usually 40 MJ / kg. The heating value of the pellets can be adjusted by changing the amount of woody biomass added. The pellets preferably have a total chlorine mass fraction of 0.3% or less, more preferably 0.1% or less, as specified in JIS Z 7311: 2010. The lower limit of the total chlorine mass fraction is usually 0.01%. Pellets that satisfy these conditions have a calorific value equivalent to that of coal and can be considered to have a high quality equivalent to the quality category in terms of total chlorine mass fraction specified in the RPF.

[0078] Although the waste treatment system, the waste treatment method, and the pellets of the present invention have been described above, the present invention is not limited to the configurations of the above-mentioned embodiments. For example, the waste treatment system and pellets of the present invention may each have any other configuration added to the configuration of the above-mentioned embodiment, or may be replaced with any configuration that performs a similar function. Furthermore, in the configuration of the above-described embodiment of the waste treatment method of the present invention, any other process may be added, or any process that exhibits a similar function may be substituted. Furthermore, the waste treatment system and waste treatment method of the present invention may each be configured by combining any of the configurations of the first to fifth embodiments described above. EXAMPLES

[0079] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. 1. Pellet production Example 1 Using the waste treatment system shown in Figure 1, pellets were produced from organic waste containing plastics. In the subcritical water treatment, the temperature of the subcritical water was set to about 200° C., the pressure was set to about 20 atmospheres, and the treatment time was 2 hours.

[0080] Example 2 Using the waste treatment system shown in FIG. 4, pellets were produced in the same manner as in Example 1 from organic waste containing plastics having the same composition as in Example 1. Example 3 Using the waste treatment system shown in FIG. 5, pellets were produced in the same manner as in Example 1 from organic waste containing plastics having the same composition as in Example 1. Example 4 Pellets were produced in the same manner as in Example 1 from organic waste containing plastics having the same composition as in Example 1, except that the mixing of woody biomass was omitted.

[0081] Comparative Example 1 Using the waste treatment system shown in FIG. 1, in which the semi-carbonization device is omitted, pellets were produced in the same manner as in Example 1 from organic waste containing plastics having the same composition as in Example 1. Comparative Example 2 Using the waste treatment system shown in FIG. 1, in which the centrifugal separator and the vacuum device are omitted, pellets were produced in the same manner as in Example 1 from organic waste containing plastics having the same composition as in Example 1.

[0082] 2. Measurement For each of the pellets obtained in the Examples and Comparative Examples, the higher heating value and the mass fraction of the total chlorine content were measured according to the method specified in JIS Z 7311:2010 "Solid fuel (RPF) made from paper, plastic, etc. derived from waste materials." The results are shown in Table 1 below.

[0083] [Table 1] [Explanation of symbols]

[0084] 1: Organic waste 2: Subcritical water treatment equipment 3: High pressure boiler 4: Torrefaction device 5: Woody biomass 6: Pellet generator 7:Water making machine 8:Classifier 9: Centrifugal separator 10: Vacuum device 14: Water treatment equipment 15: AI processing 20: Superheated steam generator 21: Solidification device 22: Deodorizing device 30: Steam compressor 31: Low pressure boiler 40: Container 41: Large vehicles 60: Coagulation reaction tank 61:Flotation tank 62: Circulation pump 63: Pressurized water tank 81:Fuel supply device 82: Gasifier 83 :Ash discharge device 84: Gas cooling device 85: Gas filter 86: Gas engine 87: Generator 100: Waste treatment systems 200: Waste treatment systems 300: Waste treatment system 400: Waste treatment system 500: Waste treatment system

Claims

1. a step of treating organic waste including plastics with subcritical water in a subcritical water treatment device to obtain a treated product by reducing the molecular weight of the organic waste; a step of discharging the gas components in the subcritical water treatment device by a gas discharge mechanism having a suction device that sucks the gas components in the subcritical water treatment device, and performing solid-gas separation between the treated material and the gas components; a step of subjecting the gas component that has passed through the gas exhaust mechanism to water treatment using a water treatment device; The pellet raw material containing the treated material is semi-carbonized and pelletized to obtain pellets having a higher heating value of 25 MJ / kg or more. When the organic waste is introduced into the subcritical water treatment apparatus prior to supplying high-temperature and high-pressure steam into the subcritical water treatment apparatus, the organic waste is introduced into the subcritical water treatment apparatus while reducing the pressure inside the subcritical water treatment apparatus, which is open to the surrounding environment, by a pressure reducing device different from the gas exhaust mechanism; A method for producing pellets, comprising the steps of: sterilizing the gas discharged from the pressure reducing device and the gas components after the water treatment by the water treatment device using a sterilization device.

2. The method for producing pellets according to claim 1, wherein the pellets have a total chlorine mass fraction of 0.3% or less as specified in JIS Z 7311:2010.

3. a step of treating organic waste including plastics with subcritical water in a subcritical water treatment device to obtain a treated product by reducing the molecular weight of the organic waste; a step of discharging the gas components in the subcritical water treatment device by a gas discharge mechanism having a suction device that sucks the gas components in the subcritical water treatment device, and performing solid-gas separation between the treated material and the gas components; a step of subjecting the gas component that has passed through the gas exhaust mechanism to water treatment using a water treatment device; The pellet raw material containing the treated material is semi-carbonized and pelletized to obtain pellets having a total chlorine mass fraction of 0.3% or less as specified in JIS Z 7311:2010; When the organic waste is introduced into the subcritical water treatment apparatus prior to supplying high-temperature and high-pressure steam into the subcritical water treatment apparatus, the organic waste is introduced into the subcritical water treatment apparatus while reducing the pressure inside the subcritical water treatment apparatus, which is open to the surrounding environment, by a pressure reducing device different from the gas exhaust mechanism; A method for producing pellets, comprising the steps of: sterilizing the gas discharged from the pressure reducing device and the gas components after the water treatment by the water treatment device using a sterilization device.

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