JP2020132805A - Manufacturing method of solid fuel - Google Patents

Abstract

To provide a manufacturing method for manufacturing a solid fuel which is safe on burning from a waste plastic as a raw material.SOLUTION: In the manufacturing method of a solid fuel, a solid fuel is manufactured by treating a plastic-based waste containing multiple kinds of plastics in a treatment space of a closed vessel by a temperature rising process, a temperature holding process, and a cooling process including treatment process, in which manufacturing method of a plastic-based solid fuel is characterized by that: in the temperature rising process, a temperature rising rate in the closed vessel to 7-12°C/min is set by using a high-temperature high-pressure water vapor; in the temperature holding process, a subcritical state having a temperature to 120°C or over and 175°C or under, and a pressure of 12-15atm is set in the closed vessel and a subcritical water treatment process is performed to a plastic-based waste by agitation in the subcritical state for 15-35 min for dissolution of several kinds of plastics among the plastic-based waste containing multiple kinds of plastics, allowing them to deposit around remaining other plastic and solidify; and in a cooling process, the obtained is cooled.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a solid fuel, and more particularly to a method for producing a solid fuel using plastic waste as a raw material.

The amount of industrial waste and domestic waste generated by the progress of urbanization and industrial development is increasing year by year, and its treatment and effective utilization have become major issues. In particular, organic waste generated at sewage treatment plants and industrial wastewater treatment plants contains carbon, which is a combustible component, and therefore effective utilization as solid fuel is being studied. For example, in Patent Document 1, organic waste is mixed with waste plastic crushed into powder, chips, threads, etc., and this mixture is pressurized under heating at 100 to 150 ° C. to obtain a solid fuel. According to this method, the calorific value can be increased as compared with the configuration in which the dehydrated organic waste is simply impregnated with oil, and the crushed waste plastic is melted or softened by heating. Since the pressure is applied in that state, the retention is improved, and handling such as transportation and storage becomes easier.

However, as a problem in solid fuel using organic waste such as dehydrated sludge as a raw material, there is an odor derived from organic waste. Therefore, in a solid fuel using a mixture of organic waste and waste plastic as described above, a method for preventing an odor derived from organic waste has been proposed.

For example, in Patent Document 2, after undergoing a deodorizing and drying step consisting of a step of mixing wood chips, paper scraps, etc. with organic waste and fermenting and deodorizing under reduced pressure, and a heat drying step under reduced pressure, the resulting mixture is discarded. A method has been proposed in which a plastic is added and compression molding is performed, preferably under heating at 100 to 180 ° C., to obtain a solid fuel. However, this method has a problem that many manufacturing processes are required and running cost is high.

Further, in Patent Document 3, waste plastic is melted to form a plastic sheet, and dehydrated sludge is wrapped therein as it is to obtain a solid fuel of a required size, or a plastic sheet is formed into a cylindrical shape and inside the solid fuel. It has been proposed to fill the dehydrated sludge, join it, and then cut it to the required size to make solid fuel. The purpose of this method is to eliminate the need for the drying step of dehydrated sludge and the pressure molding step requiring high pressure, but a separate step of melting waste plastic to form a plastic sheet is required. In addition, solid fuel is required to have strength suitable for transportation, storage, and handling such as injection into a furnace. However, the solid fuel obtained by the above method is made of plastic as it is dehydrated sludge. Since it is only wrapped in a sheet, there is a problem in its strength, such as a risk of breakage during its handling.

Further, Patent Document 4 proposes to accommodate a fuel mixture in which an organic substance containing organic sludge and a first thermoplastic are mixed in an outer shell made of a second thermoplastic. Organic sludge, which causes odor, is sealed inside the outer shell to reduce the release of odor to the outside. Then, as the forming method, a method of forming an outer shell having a predetermined shape in advance, injecting the fuel mixture into the outer shell and then sealing the outer shell, or an injection of the fuel mixture into the outer shell due to low fluidity. If it is difficult, the fuel mixture is molded into a predetermined shape in advance, and then the waste plastic powder or granular material is applied to the surface of the molded product as a liquid, or the molded product is placed in a container that becomes a pair of containers by combining them. It describes how to put it in and weld the seams. Similar to the method described in Patent Document 3, the method described in Patent Document 4 has a problem that a step of melting the thermoplastic plastic is separately required in any case.

On the other hand, in the method of producing solid fuel containing plastic waste using an extrusion molding machine, the surface of the extrusion molding is firmly surrounded by melting and solidifying the plastic existing on the surface of the extrusion molding. , It is being studied to impart integrity to extruded products. For example, in Patent Document 5, waste is separated into plastic waste containing a large amount of plastic components and other waste, and the plastic waste is supplied into the outer casing of a double screw extruder to be supplied to the outside. It has been proposed to obtain a two-layer structure extrude by making a donut-like extrude in the casing. However, Patent Document 5 does not mention the use of sludge as a raw material for solid fuel at all, and does not study at all about preventing the odor derived from organic waste. For example, the two-layer structure extruded product obtained by this method is cut to a predetermined length by a cutting blade, but when organic waste containing sludge is used as a raw material, odor is generated from the cut surface. Will end up.

Further, in Patent Document 6, by impregnating the outer periphery of a conventional solid fuel molded by a molding machine or a granulator with waste plastic, the initial thermal power of the solid fuel can be stabilized and the fuel calorie can be maintained during use. Furthermore, it has been proposed to process the shape cross section of the solid fuel like a Kintaro candy in order to stabilize the shape during production. However, in Patent Document 6, as in Patent Document 5, there is no mention of using sludge as a raw material for solid fuel, and prevention of odor derived from organic waste is completely examined. Not. Further, in this method, it is necessary to separately dissolve the waste plastic in order to impregnate the outer periphery of the fixed fuel molded by the molding machine or the granulator with the waste plastic.

As mentioned above, although some methods have been proposed to solve the odor derived from organic waste in the solid fuel obtained by mixing waste plastic with organic waste such as sewage sludge, all of them have been proposed. Since a separate step such as a deodorizing and drying step or a process of melting waste plastic is required, a simple method is used to reduce the odor derived from organic waste and improve the moldability and shape retention. A method for obtaining solid fuel is desired.

Therefore, in Japanese Patent Application Laid-Open No. 2018-154831, which is Patent Document 7, in view of the above circumstances, the odor derived from organic waste is reduced and the moldability and shape retention are improved by a simple method. The purpose is to provide a method for producing solid fuel and a production device for that purpose, and in order to achieve the above object, organic waste such as sewage sludge, which is a raw material, is covered with waste plastic, and the surface of this waste plastic is softened and melted. By solidifying the mixture while lowering the temperature to room temperature, a continuous layer of melted and solidified waste plastic is formed on the entire surface to provide a solid fuel with reduced odor derived from organic waste, easily and inexpensively. I tried to do it.

That is, the method for producing solid fuel proposed in the above patent document is a method for producing solid fuel composed of a compression molded product containing at least organic waste and waste plastic, and produces organic waste or organic waste. By covering the periphery of the raw material mixture containing or any of these preliminary solids with waste plastic, heating under pressure or after pressure to soften and melt the waste plastic, and then solidifying the waste plastic at room temperature during cooling. It is characterized in that it is a solid fuel having a continuous layer in which waste plastic is melted and solidified on the entire surface.

According to the technology disclosed in this patent document, there is a possibility that waste plastic, which has conventionally been disposed of only by landfill, can be effectively used as a part of solid fuel. Further, according to the technique disclosed in this patent document, there is a problem of chlorine content as one of the concerns when converting organic waste into solid fuel and burning it. According to this technique, the chlorine content Even when organic waste with a high level of chlorine is used, it is possible to reduce the chlorine content in solid fuel by mixing other waste such as waste plastic.

However, in the technique of Patent Document 7, no consideration is given to harmful substances generated from the waste plastic itself when the obtained solid fuel is burned.

Japanese Unexamined Patent Publication No. 9-87646 JP-A-2008-195910 Japanese Unexamined Patent Publication No. 11-61162 Japanese Unexamined Patent Publication No. 2008-2018878 Japanese Unexamined Patent Publication No. 2000-246212 Japanese Unexamined Patent Publication No. 2012-219239 JP-A-2018-154831

Therefore, an object of the present invention is to provide a method for producing a solid fuel, which uses waste plastic as a raw material and produces a solid fuel that is safe even when burned.

The above object is achieved by the method for producing a solid fuel according to the following configurations (1) to (5) of the present invention. (1)
Production of solid fuel to produce solid fuel by processing plastic waste containing various kinds of plastics in the processing space of a closed container by a processing process including a temperature raising step, a temperature holding step, and a cooling step. It's a method
Using high temperature and high pressure steam,
The heating rate in the closed container in the temperature raising step is set to 7 to 12 ° C./min.
In the temperature holding step, the inside of the closed container is set to a subcritical state with a temperature of 120 ° C. or higher and 175 ° C. or lower and a pressure of 12 to 15 atm.
By treating the plastic-based dust with subcritical water for 15 to 35 minutes while stirring in the subcritical state, some plastics among the plastic-based dust containing various plastics are dissolved. A method for producing a solid fuel, which is adhered around the remaining other plastic, solidified, and cooled by the cooling step to produce a plastic-based solid fuel.
(2)
The airtight container is provided, and the processing space of the airtight container is provided with a supply unit for supplying plastic dust, a steam ejection means for ejecting high-temperature and high-pressure steam, and an opening / closing mechanism. The method for producing solid fuel according to (1) above, which comprises an apparatus preparation step of preparing a manufacturing apparatus including a discharge unit for discharging solid fuel to the outside.
(3)
The method for producing a solid fuel according to (1) or (2), wherein 90% or less of the processing space is introduced with plastic waste in a volume ratio.
(4)
The method for producing a solid fuel according to (1) or (2), wherein 50 to 80% of the processing space is introduced with plastic waste in a volume ratio.
(5)
The method for producing a solid fuel according to any one of (1) to (4) above, wherein the stirring in the processing step is performed by a rotating stirring member arranged in the processing space.

According to the method for producing a solid fuel of the present invention, the entire plastics are hydrothermally treated to dechlorinate the plastics, and when the produced solid fuel is burned, harmful gas is generated. Can be suppressed. Further, by setting the temperature rise rate in the closed container, which is the processing container, to a relatively high temperature rise rate of 7 to 12 ° C./min, the low melting point plastics are initially melted into a liquid state. By stirring, it is possible to produce a solid fuel coated with high melting point plastics with low melting point plastics. Such a solid fuel made of a low melting point plastic coating high melting point plastic is easy to ignite and has good combustibility.

It is the schematic of the sub-critical water production apparatus used in the solid fuel production method of this invention. It is a graph which shows the temperature pattern in the temperature raising step, the temperature holding step and the cooling step in the solid fuel manufacturing method of this invention.

Embodiment of the invention

First, with reference to FIG. 1, an example of a solid fuel production apparatus (production apparatus) 10 which is a subcritical water production apparatus used in the solid fuel production method of the present invention will be described.
FIG. 1 is a cross-sectional view of the manufacturing apparatus.

The manufacturing apparatus 10 has a closed container 12 having a closed space S1 for accommodating a raw material which is a breaking material for plastic waste containing various plastics inside, and a high temperature and high pressure which is subcritical water in the closed container 12. The steam ejection means 14 for ejecting the steam of the above, the discharge port 16 provided on the bottom side of the closed container 12 and having the opening / closing mechanism 26, and the raw material and the liquid processed only by the direct discharge operation from the discharge port 16 are separated. It is provided with a separation / recovery means 18 for collecting the waste. The shape of the closed container 12 may be, for example, a rectangular box shape, a three-dimensional polygonal cylinder shape, a cylindrical shape, a barrel shape, a drum shape, or any other shape, but gravity is used from the discharge port 16 provided on the lower surface side. A shape that allows discharge is preferable. It is preferable that the lower surface of the closed container is provided so as to be inclined downward toward the discharge port. The diameter of the discharge port 16 is preferably 30 cm or more so that the produced solid fuel can be discharged. Similarly, it is desirable that the input port (described below) for charging waste plastics into the device also has a diameter of the same size.

The separation / recovery means 18 has another closed space S2 different from the closed space S1 of the closed container 12, and has a liquid recovery unit 50 communicating with the inside of the closed container 12 via the discharge port 16 and the inside of the closed container 12. It may have a natural flow recovery mechanism 52 for collecting only the liquid of the above to the recovery unit 50 by natural flow through the discharge port 16. The raw material as the solid content treated near the discharge port 16 remains as it is in the closed container 12, and only the liquid naturally flows down to the recovery unit 50 using gravity, so that the raw material and the liquid can be separated and recovered. The structure of the recovery unit 50 may be arbitrary as long as it has a closed space S2 for collecting liquid, such as a metal tank, a three-dimensional polygonal box body, or a tubular body. A plurality of accommodating portions may be formed.

The natural flow recovery mechanism 52 may include the same pressure forming means 62 that makes the closed space S1 of the closed container 12 and the closed space S1 of the recovery unit 50 equal in pressure before the liquid recovery operation. If the closed container 12 and the recovery unit 50 are configured to have the same pressure at all times, the liquid recovery work can be performed immediately after the treatment, and the work time can be shortened.
In the above example, an example in which the separating means is incorporated in the manufacturing apparatus has been described, but the manufacturing apparatus itself may be provided separately without providing the separating means.

Further, the same pressure forming means 62 for making the closed space S1 of the closed container 12 and the closed space S2 of the recovery unit 50 the same pressure may be provided. The same pressure forming means 62 has a same pressure communication pipe 64 that communicates the closed space S1 of the closed container 12 and the closed space S2 of the recovery unit 50 by a different route from the liquid recovery path via the discharge port 16. It may be that. The same pressure communication pipe 64 may always communicate with the closed space S1 and the closed space S2 so that the inside of the closed container 12 and the inside of the collection unit 50 are always in the same pressure state. The same pressure communication pipe 64 may have the same pressure by communicating the closed container 12 and the recovery unit 50 at least before the liquid recovery operation, and an opening / closing mechanism for communicating / shutting off the same pressure communication pipe is provided. It may be provided.

Further, the communication between the same pressure communication pipe 64 and the closed container 50 forming another path may be performed via the communication connecting portion 68 set on the upper end side of the closed container 12.

Further, the natural flow recovery mechanism 52 includes a liquid recovery flow path 54 that connects the discharge port 16 of the closed container 12 and the recovery section 50 in communication, and the liquid recovery flow path 54 is a recovery section from the communication side with the discharge port 16. It may be provided horizontally or downwardly inclined toward the 50 side.

Further, an opening / closing mechanism 26 is provided in the middle of the discharge path R1 from the discharge port 16 of the processed raw material, and the liquid introduction port 58 of the liquid recovery flow path 54 is continuously connected to the discharge upstream side of the opening / closing mechanism 26. May be.

Further, for the liquid recovery flow path 54, a communication state is selected so that the flow path is blocked during the processing of the raw material in the closed container 12 and the flow path is communicated when only the liquid is recovered after the treatment. An opening / closing mechanism 60 for switching between the two may be provided.

Further, the bottom surface of the closed space S2 of the collection unit 50 may be provided lower than the position of the discharge port 16 of the closed container 12.

Further, the recovery unit 50 may be provided so that the liquid level WL of the liquid recovered in the closed space S2 is always lower than the discharge port 16.

A stirring means 30 for stirring the raw material is installed in the closed container 12.

Further, the closed container 12 is formed in a sideways barrel shape in which the diameter is gradually reduced from the left and right center portions toward the left and right end sides while the discharge ports 16 are provided on the bottom side of the left and right center portions, and the stirring means 30 Has a rotating shaft 49 provided in a closed container 12 in a horizontally long manner and rotatably supported, and a stirring blade 48 attached to the rotating shaft 49 and having a portion extending in the circumferential direction of the rotating shaft 49. The length from the rotating shaft 49 of the stirring blade 48 to the tip of the blade is long at the center position in the longitudinal direction of the rotating shaft 49, corresponding to the sideways barrel shape of the closed container 12, and gradually becomes shorter toward both ends. It may be formed so as to be.

Further, the steam ejection means 14 includes a rotary shaft and steam ejection pipe 28 having a rotary shaft 49 as a hollow pipe and forming a plurality of steam ejection holes 44 on the peripheral surface of the hollow pipe. May be good.

In this example, the closed container 12 is supported by the support legs 13 so as to be arranged at a certain height from the ground. The closed container 12 is formed in a sideways barrel shape in which the diameter is gradually reduced from the central portion in the left-right direction toward the end walls 12a on both the left and right ends. The closed container 12 is formed by processing a metal plate so as to have heat resistance and pressure resistance, and is provided with a size capable of accommodating about 2 m ^{3 of} a raw material. The closed container 12 is provided with an input unit 20 which is a raw material supply unit and a discharge unit 22 on the bottom side of the central portion above the central portion, and is opened and closed by the opening / closing mechanisms 24 and 26, respectively. It is provided in. In the closed space S1 of the closed container 12, a steam ejection pipe 28 constituting the steam ejection means 14 and a stirring means 30 for stirring the raw materials are arranged. The closed container 12 is provided with a safety valve 32 that releases the internal steam when the internal pressure becomes higher than the set value, for example, the set pressure can be adjusted. Further, a muffling / deodorizing device 34 is provided in the middle of the exhaust pipe connected to the safety valve 32, and the steam exhausted through the safety valve 32 is deodorized and deodorized and discharged to the outside air side. ..

As shown in the figure, the discharge port 16 is opened on the bottom surface side of the central portion in the left-right direction of the closed container 12, and is provided with the discharge direction of the raw material facing downward. The diameter of the discharge port 16 is provided to be, for example, about 300 mm. A discharge cylinder 36 projecting downward is connected to the discharge port 16 to form a discharge path R1 for the processed raw material, and the discharge port 16 is provided in the middle of the discharge port R1 to open and close the discharge port 16. An opening / closing mechanism 26 is provided. That is, the discharge unit 22 includes a discharge port 16, a discharge cylinder 36, and an opening / closing mechanism 26. Since the closed container 12 is formed in a barrel shape by lying down, the raw materials inside are easily collected toward the central portion where the discharge port 16 is provided due to gravity, and the raw materials can be easily discharged by simply opening the opening / closing mechanism 26. It can be discharged from 16.

In the loading section 20, a loading port 42 is opened on the upper side of the closed container 12, and a loading cylinder 43 projecting upward is attached to the loading port 42, for example, a ball so as to open and close the inside of the loading cylinder 43. An opening / closing mechanism 24 such as a valve is provided. The input port 42 can be opened via the opening / closing mechanism 24 to charge the raw material into the closed container, and the raw material can be closed during processing to maintain the closed state of the closed space S1 in the closed container 12.

The steam ejection means 14 ejects high-temperature and high-pressure steam into the closed container 12, and puts the inside of the closed container 12 into a high-temperature and high-pressure state so that the raw material is processed through the steam. As shown in FIG. 1, the steam ejection means 14 includes a steam ejection pipe 28 formed of a hollow tube arranged in a closed container 12 and having a large number of steam ejection holes 44 formed on the peripheral surface side, and steam generation of a boiler or the like. The device 46 includes a steam transmission pipe 47 that supplies steam from the steam generator 46 into the steam ejection pipe 28. The steam ejected from the steam ejection means 14 into the closed container 12 is set to a high temperature and high pressure such that it is sub-critical water in order to properly process the raw material. For example, the temperature of the steam ejected from the steam ejection pipe 28 is set to about 100 to 250 ° C. and the pressure is set to about 5 to 35 atm. Then, the temperature inside the closed container 12 is set to about 100 to 250 ° C. and the pressure is set to about 5 to 35 atm. The steam ejection pipe 28 is arranged long in the horizontal direction at a substantially central position in the vertical direction of the closed container 12, and is rotatably supported by bearings 45 provided on both end walls 12a of the closed container. That is, the steam ejection pipe 28 is adapted to directly hit the raw material while ejecting steam radially while rotating around the horizontal axis. The steam ejection pipe 28 is adapted to rotate by obtaining a rotational driving force from a rotational driving device 51 such as a motor via a chain or the like. Further, a stirring blade 48 constituting the stirring means is attached to the steam ejection pipe 28, and the steam ejection pipe 28 also serves as a rotating shaft 49 of the stirring means. That is, in the present embodiment, the steam ejection means 14 has a rotating shaft 49 of the stirring means as a hollow tube, and a plurality of steam ejection holes are formed on the peripheral surface of the hollow tube to form a rotating shaft and steam. The ejection pipe 28 is included. The steam ejection means is not limited to this form, and may be any other configuration such as a configuration in which steam is ejected from the tip of a pipe inserted into a closed container, a configuration in which a plurality of steam ejection pipes are arranged, and the like. Good.

The stirring means 30 is a means for stirring the raw material to be processed in the closed container, and the raw material can be processed evenly and at an early stage. The stirring means 30 includes a rotating shaft 49 composed of the steam ejection pipe 28 described above, and a stirring blade 48 attached to the rotating shaft 49 and having a portion extending in the circumferential direction of the rotating shaft 49. In the present embodiment, the stirring blade 48 is formed by a right-handed spiral blade 48a and a left-handed spiral blade 48b, which are provided in opposite directions to each other at a substantially central position in the axial direction of the rotating shaft 49. The stirring blade 48 is provided so that the length from the rotation shaft to the tip of the blade is gradually reduced from the left and right central portions to both ends. As a result, the raw material can be reliably agitated corresponding to the sideways barrel shape of the closed container 12. Further, it is provided so as to form a certain gap H between the tip of the blade and the inner wall of the closed container 12. The spiral blades 48a and 48b stir the raw material while crushing the solid raw material while transporting the raw material from the central portion toward both end walls. The raw material transported to the end wall 12a side by the stirring blade 48 is pushed by the raw material transported later on the end wall 12a side, and returns to the center after passing through the gap H along the inner wall of the closed container 12. Will be transported to. The stirring means 30 is not limited to the above configuration, and may have any other configuration.

The separation / recovery means 18 is a separation / recovery means that separates and recovers the processed raw material and the liquid in the closed container 12 after the vapor treatment only by a direct operation from the discharge port. As shown in FIG. 1, the separation / recovery means 18 causes the collection unit 50 to collect the liquid that communicates with the inside of the closed container 12 via the discharge port 16 and the liquid by natural flow through the discharge port 16. It has a natural flow recovery mechanism 52 and.

The collection unit 50 is a second closed container having an inner closed space S2 different from the closed space S1 of the closed container 12. The recovery unit 50 is made of, for example, a metal cylindrical closed tank having heat resistance and pressure resistance. The recovery unit 50 is communicated with and connected to the discharge port 16 of the closed container 12 via a liquid recovery flow path 54 formed of, for example, a metal pipe member or the like. The collection unit 50 is provided so that the bottom surface of the closed space S2 is lower than the position of the discharge port 16 of the closed container 12, and the liquid level WL of the liquid collected in the closed space S2 is always lower than the discharge port 16. It is provided in the above so that the liquid on the discharge port side can easily flow naturally to the collection part side. The recovery unit 50 is provided with a drain 56 for taking out the recovered liquid, and is provided so as to be opened and closed by an on-off valve.

The natural flow recovery mechanism 52 is a natural flow recovery means that allows only the liquid to flow down from the discharge port to the recovery unit 50 by the natural flow of the liquid collected in the closed container 12 due to gravity. The natural flow recovery mechanism 52 includes a liquid recovery flow path 54, and the liquid recovery flow path 54 is branched from the treated raw material discharge path R1 by connecting the liquid introduction port 58 to the discharge port 16. It forms a liquid recovery path R2. In the present embodiment, the liquid recovery flow path 54 is provided, for example, with a metal pipe having an inner diameter of about 6 mm. The liquid recovery flow path 54 is provided with an opening / closing mechanism 60 that selectively switches the communication state of the flow path. The opening / closing mechanism 60 is switched so as to block the flow path during the processing of the raw material in the closed container and to communicate the flow path when separating and recovering only the liquid after the treatment. As a result, the water and steam contained in the raw material are liquefied at the same time as the raw material, and the liquid containing bacteria and malodorous components in the raw material can be treated with high-temperature and high-pressure steam. The liquid separated and recovered after the treatment can be recovered in a state of being sterilized or decomposed of malodorous and harmful components, and the separated and recovered liquid does not need to be secondarily treated, and no labor is required. The time can be shortened.

In the liquid recovery flow path 54, the liquid introduction port 58 is communicatively connected to a position on the discharge upstream side of the opening / closing mechanism 26. Therefore, with the opening / closing mechanism 26 of the discharge port 16 closed, the opening / closing mechanism 60 of the liquid recovery flow path 54 is opened to bring the flow path into a communicating state, so that the liquid is separated and collected from the discharge port. The liquid recovery flow path 54 is connected to the discharge cylinder 36 in the orthogonal direction, and the liquid recovery path R2 is provided in the direction orthogonal to the raw material discharge path R1. That is, in the closed state of the opening / closing mechanism 26, the liquid flows in the intersecting direction with respect to the direction in which the deposition pressure of the raw material in the closed container is applied. As a result, the structure is such that the raw material does not easily enter the liquid introduction port 58 with a simple structure, and only the liquid naturally flows down into the liquid recovery path 54, so that the liquid can be separated and recovered satisfactorily. If the momentum of the liquid in the closed container 12 flowing to the liquid introduction port 56 is too strong, the raw materials may flow together due to the force of the liquid flow. Therefore, the processed raw materials are not preferably carried. The connection configuration of the liquid recovery path, the liquid inlet, etc. is set so that the flow is moderate. The liquid recovery flow path 54 is provided horizontally as a whole from the communication side with the discharge port 16 (the liquid introduction port side) toward the recovery portion side. As a result, the liquid flows smoothly in the liquid recovery flow path and naturally flows down from the discharge port to the recovery section. The liquid recovery flow path 54 may be provided in a downward slope toward the recovery section side so that the liquid flow can flow more smoothly in the liquid recovery path 54. At this time, for example, the liquid introduction port 58 side may be provided horizontally to a certain length and then provided on a downward slope. Further, the liquid introduction port 58 may be provided with a filter or the like, if necessary.

Further, as shown in FIG. 1, the natural flow mechanism 52 provides the same pressure forming means 62 for forming the closed space S1 of the closed container 12 and the closed space S2 of the recovery unit 50 at the same pressure before the liquid recovery operation. Including. Normally, since the inside of the closed container 12 after the treatment has a high pressure, a pressure feeding force due to a pressure difference acts toward the closed space S2 of the recovery portion, which has a lower pressure than the inside of the closed container. When such a pumping force acts, both the liquid and the raw material flow into the liquid recovery flow path 54, which makes it difficult to separate and recover the liquid and the raw material, and there is a high possibility that the raw material is clogged in the liquid recovery flow path. .. By using the same pressure forming means 62 to keep the two closed spaces S1 and S2 of the closed container 12 and the recovery unit 50 at the same pressure before the liquid recovery operation, the difference in pressure between the two closed spaces S1 and S2. It is possible to prevent the raw material produced by the above from being pumped, and by utilizing the natural flow action of the liquid, it can be satisfactorily recovered in the recovery unit while being separated from the raw material. Further, since the separation and recovery work can be performed even in the high pressure state in the closed container after the treatment, the work time can be shortened.

The same pressure forming means 62 connects the closed space S1 of the closed container 12 and the closed space S2 of the recovery unit 50 with another path R3 different from the liquid recovery path R2 (liquid recovery flow path 54) via the discharge port 16. Includes the same pressure communication pipe 64 to communicate. The same pressure communication pipe 64 is made of, for example, a metal pipe, and can efficiently make the two closed spaces S1 and S2 have the same pressure with a simple structure. In FIG. 1, one end side of the same pressure communication pipe 64 is communicated with the upper end side of the left and right central portions of the closed container 12, and the other end side is communicated with the upper end side of the recovery portion 50. The communication between the same pressure communication pipe 64 forming another path R3 and the closed container 12 is performed via the communication connecting portion 68 set on the upper end side of the closed container 12. The connection port of the communication connection portion 68 with the closed container is set to face downward. As a result, the raw material accumulated in the closed container 12 in the same pressure communication pipe 64 is less likely to enter the pipe, and the raw material is prevented from being clogged in the pipe to maintain the communication state of the same pressure communication pipe. The closed container 12 and the recovery unit 50 can be surely made to have the same pressure. The same pressure communication pipe 64 is always in a communication state, and when the opening / closing mechanism 60 of the liquid recovery flow path 54 is closed, the pressure inside the closed container 12, the recovery unit 50, and the liquid recovery flow path 54 is the same. Become. As a result, it is possible to prevent pressure feeding of the raw material due to the pressure difference on the liquid introduction port 58 side of the discharge port 16 immediately after opening the opening / closing mechanism 60 of the liquid recovery flow path 54. Further, even when the opening / closing mechanism 60 is opened to collect the liquid, the same pressure state is always maintained in the closed container 12 and the collection unit 50. Therefore, the pressure is the same from before the recovery to after the recovery, and only the liquid can be satisfactorily flowed down from the discharge port 16 for separation and recovery. The pressure forming means 62 is not limited to this type of configuration, and may have any configuration. For example, the same pressure forming means 62 is provided with another high pressure forming device for increasing the pressure inside the recovery unit, and adjusts the pressure inside the collection unit while monitoring the pressure inside the closed container with a sensor to be the same as the pressure inside the closed container. It may be pressured. Further, the pressure inside the closed container may be reduced.

Next, a method for producing a solid fuel according to the embodiment of the present invention using the production apparatus 10 described above will be described.

The method for producing a solid fuel according to the embodiment of the present invention is
Equipment preparation process for preparing the manufacturing equipment as described above,
A raw material charging process in which a raw material, which is plastic waste, is charged from the supply unit into the processing space of the closed container of the manufacturing apparatus.
A temperature raising step of introducing high-temperature and high-pressure steam into the processing space to raise the temperature in the processing space.
Steam having a temperature of 120 to 175 ° C. and a pressure of 12 to 35 atm is introduced into the treatment space in which the raw material is charged, and the raw material is subjected to sub-critical water reaction treatment while stirring the raw material to form a solid. Processing process for producing fuel,
A cooling step for cooling the inside of the processing space, and
It is provided with a take-out process in which the produced solid fuel is taken out of the closed container through the discharge port.

Hereinafter, each step described above will be described in detail.
<< Equipment preparation process >>
While referring to the figure, prepare the manufacturing equipment (manufacturing equipment) as described above.

《Raw material input process》
Plastic waste as a raw material First, plastic waste to be treated, that is, containing waste plastics as a raw material for solid fuel is prepared. The waste plastics may be in the same shape as they are, but at least, the waste plastics are preferably of a size that can be charged from the input port of the manufacturing apparatus 10, and in particular, they are made into small pieces such as chips or granules. Is preferable. By the way, the breakdown of these waste plastics by resin is as follows, according to a 2017 survey by the Plastic Recycling Association, polyethylene (PE) is 33.9%, polypropylene (PP) is 22.2%, and polystyrenes (1 company). PS) is 11.8%, vinyl chloride resin (VC) is 7.5%, and others are 24.5%. The breakdown of waste plastics by resin in the plastic waste prepared this time was similar to this.

Insertion of plastic-based dust The plastic-based waste containing various types of plastics is charged into the processing space of the closed container of the manufacturing apparatus 10 from the charging port. At this time, the amount of the plastic waste charged into the closed container is preferably 90% or less, particularly 50 to 80% of the processing space for the plastic waste in terms of volume ratio.

<< Heating process >>
In this temperature raising step, the temperature rising rate is set to 7 to 12 ° C./min in consideration of the amount of plastic dust charged into the processing space in the closed container and the following holding temperature (treatment temperature) values. .. This temperature rise is performed by introducing high-temperature and high-pressure steam into the processing space.
If the rate of temperature rise is less than the above, the processing time is too long, the amount of processing is reduced, and as a result, the cost is increased. , The low melting point plastics are melted and do not become the outer coating layer of the high melting point plastics. As a result, the ignitability of the resulting solid fuel becomes insufficient.

<< Processing process >>
In this treatment step, the inside of the closed container is kept in a subcritical state at a temperature of 120 ° C. or higher and 175 ° C. or lower and a pressure of 12 to 15 atm for a predetermined time. This temperature and pressure are achieved by introducing high-temperature and high-pressure steam having a temperature of 120 ° C. or higher and 175 ° C. or lower and a pressure of 12 to 15 atm into the closed container.
By treating the plastic-based dust with subcritical water for 15 to 35 minutes while stirring the plastic-based dust in the subcritical state by the stirring means, some plastics among the plastic-based dust containing various kinds of plastics are used. Is melted and attached around the rest of the plastic to solidify.
In this treatment step, if the temperature and / or pressure is less than the subcritical state, the softening of at least the peripheral portion of the high melting point plastic does not proceed, and therefore, the melt of the low melting point plastic is produced. It becomes difficult to adhere to the outside, and dechlorination is not sufficient. On the other hand, if it exceeds it, most of the refractory plastics are melted, and the solid fuel is not formed.
In this treatment step, plastics having a relatively low melting point are melted, while plastics having a relatively high melting point are softened but not melted, and are dechlorinated accordingly.

《Cooling process》
After that, an intermediate of a fixed fuel made of high melting point plastics whose outside is coated with low melting point plastics is cooled by this cooling step to produce a plastic-based solid fuel. This cooling step may be performed by natural cooling after returning the processing space to normal pressure.

<< Solid fuel acquisition process >>
In this step, first, the solution component is separated from the solid fuel component. This separation is performed by allowing the solution component to fall naturally and leaving the solid fuel component in the closed container using the separation / recovery means.
After the liquid component is discharged from the inside of the device, the discharge port is opened and the solid fuel is taken out of the device.
With the above, the production of solid fuel is completed.

[Example]
First, a manufacturing apparatus having a structure as shown in FIG. 1 having a processing space volume of 2 m ^{3 in} a closed container was prepared.
In the processing space, plastic-based waste having the above-mentioned contents of waste plastics was prepared as a raw material, and experiments were conducted on the production of waste plastic fuels using the plastic wastes.
For the pretreatment of plastic-based waste, the one having a size that cannot be charged from the input port of the device was used as it was except that the volume was reduced by crushing it.
The amount of plastic waste input was 1.6 m ³ (80% of the volume of the treatment space).

After charging the plastic waste, high-temperature and high-pressure steam was introduced so that the temperature in the treatment space became the treatment temperature shown in the table. The temperature rising rate in the processing space at that time was set to the value shown in the table, and the temperature rising step was performed.
Next, the temperature in the treatment space was the treatment temperature, the pressure was fixed at 14 atm, the treatment time was fixed at 25 minutes, and subcritical water treatment was performed to produce a sample solid fuel. An ignition test was conducted on each of the solid fuels of the obtained samples, and the state of dioxin generation during combustion was determined. This determination was made by measuring the amount of dioxin generated within 5 minutes after ignition. The results are shown in the evaluation in Table 1.
The ignition test was determined by irradiating the solid fuel of the sample with the flame of a gas burner and measuring the time until ignition. The judgment contents are as follows.
〇: Ignished within 20 seconds after applying the flame. Evaluation x: No ignition even after 20 seconds.
In the dioxin generation test, when the amount of dioxin generated is 1 when burned without any treatment other than solidifying plastic waste, the amount generated is 1/2 or less. The time when it did not become x was defined as x.
From the above, the effect of the present invention is clear.

10 Solid fuel manufacturing equipment 12 Sealed container 14 Steam ejection means 16 Discharge port 18 Separation and recovery means 26 Opening and closing mechanism 30 Stirring means 50 Recovery unit 52 Natural flow recovery mechanism 54 Liquid recovery flow path 58 Liquid introduction port 60 Opening and closing mechanism 62 Same pressure formation Means 64 Same pressure communication pipe

Claims (5)

Production of solid fuel to produce solid fuel by processing plastic waste containing various kinds of plastics in the processing space of a closed container by a processing process including a temperature raising step, a temperature holding step, and a cooling step. It's a method
Using high temperature and high pressure steam,
The heating rate in the closed container in the temperature raising step is set to 7 to 12 ° C./min.
In the temperature holding step, the inside of the closed container is set to a subcritical state with a temperature of 120 ° C. or higher and 175 ° C. or lower and a pressure of 12 to 15 atm.
By treating the plastic-based dust with subcritical water for 15 to 35 minutes while stirring in the subcritical state, some plastics among the plastic-based dust containing various plastics are dissolved. A method for producing a solid fuel, which is adhered around the remaining other plastic, solidified, and cooled by the cooling step to produce a plastic-based solid fuel. The airtight container is provided, and the processing space of the airtight container is provided with a supply unit for supplying plastic dust, a steam ejection means for ejecting high-temperature and high-pressure steam, and an opening / closing mechanism. The method for producing a solid fuel according to claim 1, which comprises an apparatus preparation step of preparing a manufacturing apparatus including a discharge unit for discharging the solid fuel to the outside. The method for producing a solid fuel according to claim 1 or 2, wherein 90% or less of the processing space is introduced with plastic waste in a volume ratio. The method for producing a solid fuel according to claim 1 or 2, wherein 50 to 80% of the processing space is introduced with plastic waste in a volume ratio. The method for producing a solid fuel according to any one of claims 1 to 4, wherein the stirring in the processing step is performed by a rotating stirring member arranged in the processing space.