Solid fuel manufacturing method

Abstract

A method for producing solid fuel is provided that can produce dechlorinated and semi-carbonized solid fuel by shear heat of an agitating blade without using external heating. [Solution] A method for producing solid fuel in which waste plastics and anti-adhesion material are stirred in a high-speed rotary mixer and heated to over 180°C by shear heat from the stirring blades, and granulated while undergoing dechlorination and semi-carbonization, characterized in that the anti-adhesion material is at least one selected from biomass powder and granules, solid fuel, and oil with a flash point higher than the maximum temperature of the waste plastics and anti-adhesion material during granulation.

Description

[Technical Field]

[0001] The present invention relates to a method for producing solid fuel using waste plastics (waste plastics) as a raw material. [Background technology]

[0002] The 2015 G7 Summit raised the issue of marine litter and plastic waste as a global challenge. To prevent illegal dumping of plastic waste, Japan doubled the amount of temporary storage in 2019 and formulated the "Plastic Resource Circulation Strategy" in May of the same year. The "Plastic Resource Circulation Strategy" outlines a strategy for recycling plastic containers and packaging (plastic packaging) and non-plastic packaging waste from ordinary households at low cost and with low CO2 emissions, achieving high resource recovery rates, including thermal recovery. It also calls for the elimination of illegal dumping, aiming for zero marine plastic emissions. The Ministry of the Environment's figures for illegal dumping in fiscal years 2020 and 2021 show that waste plastic, sludge, and wood chips are listed as combustible waste, excluding construction waste. Criticism has also been directed at greenhouse gas emissions generated when illegally dumping plastic waste in the ocean.

[0003] Meanwhile, there are known technologies for recycling waste plastic and paper into solid fuels such as RPF (Refuse-derived paper and plastics densified fuel). In light of the fact that waste plastics with a high content of chlorine-containing polyvinyl chloride (PVC), which are considered unsuitable for use as fuel, are subject to rising industrial waste disposal costs and are being illegally dumped, the current situation, in which waste plastics are deemed unsuitable for use as fuel unless they contain less than 0.3% chlorine, as defined by JIS Z7311:2010 "Refuse-derived paper, plastic, etc. solidified fuel (RPF)," is being reviewed, and the RPF industry is moving toward easing acceptance restrictions, allowing use of fuel with a chlorine content of 1% or less.

[0004] As a technology for dechlorinating high-chlorine-content waste plastics, for example, a twin-screw dechlorination treatment device that uses external indirect heating has been proposed. Patent Document 1, for example, describes a twin-screw dechlorination treatment device as follows: "If the device does not have an active mixing / kneading function, energy efficiency is poor and uniform dechlorination cannot be achieved. In the embodiment of the invention, the molten waste plastics are heated by the heater and passed through the cylinder of the dechlorination device (external indirect heating), and the twin-screw rotating screws that actively have a mixing / kneading function apply a shearing action to generate shear heat, thereby enabling the molten waste plastics to be efficiently heated and thermally decomposed." However, no detailed data on the shearing action and processing capacity is provided.

[0005] There has also been a report on a technology for dechlorinating waste plastics using a twin-screw dechlorination device (see Non-Patent Document 1). To summarize the examples in this report, it states that "the residual chlorine concentration hardly changes at residence times of 10 minutes or more. After water washing, general waste plastics with a chlorine content of 1.8 wt% are dechlorinated to a residual chlorine concentration of just over 0.8 wt% (about half the amount of chlorine input) through the shearing action of twin-screws with an outer diameter of 174 mm and a peripheral speed of approximately 0.37 m / s, which passes through a cylinder at a heating temperature of 310°C by external indirect heating and levels off at residence times of 10 minutes or more." However, no detailed data on processing capacity is given. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-86447 [Non-patent literature]

[0007] [Non-Patent Document 1] Masayoshi Tokihisa et al., "Plastic Dechlorination Solid Fuel Production Equipment," Journal of the Japan Paper and Pulp Technology Association, Vol. 55, No. 5, pp. 82-88, May 2001 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method capable of producing dechlorinated and torrefied granular solid fuel by shear heat of a stirring blade without using external heating. [Means for solving the problem]

[0009] While investigating methods for producing solid fuel from waste plastics, the inventors discovered that dechlorinated and semi-carbonized granular solid fuel can be produced by heating the waste plastics and anti-adhesion material to over 180°C using shear heat from the mixing blades in a high-speed rotary mixer and then granulating them, which led to the completion of the present invention.

[0010] That is, the present invention is as follows. [1] A method for producing solid fuel in which waste plastics and anti-adhesion materials are stirred in a high-speed rotary mixer and heated to over 180°C by shear heat from the stirring blades, and granulated with dechlorination and semi-carbonization, A method for producing solid fuel, characterized in that the anti-adhesion material is at least one selected from biomass powder, the solid fuel, and oil having a flash point higher than the maximum temperature of the waste plastic and anti-adhesion material during granulation. [2] The method for producing a solid fuel according to [1] above, wherein the produced solid fuel has a chlorine content of 1.0 mass % or less. [3] The method for producing a solid fuel according to [1] or [2] above, characterized in that the anti-adhesion material contains at least biomass powder, and the biomass powder is organic sludge powder generated from a wastewater treatment facility.

[0011] [4] A method for producing solid fuel according to any one of [1] to [3] above, characterized in that the granulation involves melting waste plastics by shear heat of the stirring blades, dechlorinating and semi-carbonizing them, and then adding water to solidify and granulate the waste plastics. [5] The method for producing a solid fuel according to any one of [1] to [4] above, characterized in that a purging treatment of air or an inert gas is carried out when heating to above 180°C by shear heat of the stirring blades of the high-speed rotary mixer. [6] The method for producing a solid fuel according to [4] above, wherein the water used for the hydration contains a neutralizing agent that neutralizes chlorinated compounds.

[0012] [7] A method for producing a solid fuel according to any one of [1] to [6] above, characterized in that the solid fuel produced has a chlorine content of 1.0% by mass or less, a higher heating value of 25 MJ / kg or more, a moisture content of 5% by mass or less, and an ash content of 10% by mass or less, in compliance with the RPF quality standards. [8] The solid fuel produced has a chlorine content of 1.0 mass% or less and a bulk density of 0.4 t / m 3 Above, average particle diameter D 50 The method for producing a solid fuel according to any one of [1] to [7] above, characterized in that the grains have a particle size of 10.0 mm or less, and 90% or more of the grains have a particle size of 0.01 mm or more, and an angle of repose of 50° or less. [9] The method for producing a solid fuel according to any one of the above [1] to [8], wherein the produced solid fuel has a sulfur content of 1 mass % or less.

[0013]

[10] A granular solid fuel containing plastic, characterized in that the chlorine content is 1.0% by mass or less, the granular solid fuel complies with the RPF quality standards, has a higher heating value of 25 MJ / kg or more, a moisture content of 5% by mass or less, and an ash content of 10% by mass or less.

[11] Granular solid fuel containing plastic, with a chlorine content of 1.0% by mass or less and a bulk density of 0.4 t / m 3 Above, average particle diameter D 50 A granular solid fuel characterized in that the particle size is 10.0 mm or less, and 90% or more of the particles have a particle size of 0.01 mm or more and an angle of repose of 50° or less. [Effects of the Invention]

[0014] According to the method for producing solid fuel of the present invention, it is possible to produce granular solid fuel that has been dechlorinated and torrefied by shear heat of the stirring blades without using external heating. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram of a method for producing solid fuel according to an embodiment of the present invention. [Figure 2] FIG. 1 is an explanatory diagram of a high-speed rotary mixer used in the examples. [Figure 3] FIG. 2 is a graph showing the cumulative undersize particle size distribution of the solid fuels obtained in Examples 2 and 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] The method for producing solid fuel of the present invention is a method for producing solid fuel in which waste plastics and anti-adhesion material are stirred in a high-speed rotary mixer while being heated to above 180°C by shear heat from the stirring blades, and granulated while undergoing dechlorination and semi-carbonization, and is characterized in that the anti-adhesion material is at least one selected from biomass powder and granules, solid fuel, and oil having a flash point higher than the maximum temperature of the waste plastics and anti-adhesion material during granulation.

[0017] The solid fuel production method of the present invention can produce dechlorinated and semi-carbonized granular solid fuel by heating waste plastics and a specific anti-adhesion material in a high-speed rotary mixer using shear heat from the mixing blades without using external heating. Furthermore, if the biomass powder contains sulfur-containing compounds, the sulfur components can be volatilized and removed (desulfurized) by thermal decomposition.

[0018] In addition, the method for producing solid fuel of the present invention melts and mixes waste plastic with an anti-adhesion material, thereby preventing the molten waste plastic from adhering and enabling granulation accompanied by dechlorination and semi-carbonization.

[0019] Furthermore, the method for producing solid fuel of the present invention allows granulation regardless of whether water is added or not, and can produce solid fuel of quality equal to or better than that produced using a conventional twin-screw dechlorination device using external heating.

[0020] Furthermore, the solid fuel production method of the present invention dechlorinates, desulfurizes, and torrefies waste plastics by direct heating caused by the powerful local shearing of the agitating blades of a high-speed rotary mixer, thereby realizing reduced CO2 emissions through low power consumption and enabling efficient production of solid fuel with low initial and running costs.In other words, the solid fuel production method of the present invention has lower initial and running costs (power consumption) per processing capacity, as well as lower power consumption and CO2 emissions, compared to production methods using conventional twin-screw dechlorination equipment with external heating, allowing for efficient production of solid fuel at low cost.

[0021] Patent Document 1 and Non-Patent Document 1 do not mention the processing capacity of screw-type dechlorination technology, but Non-Patent Document 1 states that "the residual chlorine concentration hardly changes at residence times of 10 minutes or more." The lower the screw rotation speed, the longer the residence time and the higher the dechlorination performance, but the lower the processing capacity, the less direct heating due to shearing by the screw, and the dechlorination becomes more dependent on the external indirect heating, and the efficiency of direct heating decreases.

[0022] In contrast, the present invention has been evaluated in Example 3, which achieves the same dechlorination rate at a lower resin temperature as the dechlorination technology of Patent Document 1. At the same resin temperature, the present invention, which does not use external indirect heating, consumes less power for direct heating. As the resin temperature increases, the melt viscosity increases, increasing the power consumption for both drive components. Therefore, the present invention, which has a lower resin temperature than Patent Document 1, consumes less power for drive components.

[0023] Furthermore, when the power consumption required for external indirect heating and screw drive in Patent Document 1 is compared with the power consumption required for direct heating and drive of only the stirring blades of the present invention, the latter consumes less power for heating and drive. As will be described later, the initial cost of the high-speed rotary mixer of the present invention is about 20% cheaper than the twin-screw system of Patent Document 1 when they have the same processing capacity.

[0024] [Waste plastic] The waste plastics (waste plastics) to be treated in the present invention are not particularly limited as long as they can be treated using a high-speed rotary mixer, and examples thereof include recycled plastic container packaging (recycled plastic containers). The form of the waste plastics may be in a discarded state or may be processed after disposal, with processed plastics being preferred. As processed waste plastics, crushed waste plastics are more preferred. The shape of the waste plastics may include various shapes such as fluff, beads, flakes, chips, powder, and pellets.

[0025] Examples of waste plastics include general-purpose waste plastics, such as PP (polypropylene), PE (polyethylene), PS (polystyrene), and PET (polyethylene terephthalate), which are the main components of plastic container recycling. The preferred waste plastics are those containing polyvinyl chloride (PVC), which is unsuitable for recycling and settles during wet gravity separation of plastic container recycling. The method for producing solid fuel of the present invention can recycle this polyvinyl chloride-containing plastic into solid fuel.

[0026] [Anti-adhesion material] Examples of the anti-adhesion material of the present invention include biomass powder, solid fuel, and oil with a flash point higher than the maximum temperature (also called resin temperature) of the waste plastic and anti-adhesion material during granulation, and these may be mixed with the waste plastic alone or in combination. The addition of these anti-adhesion materials prevents the adhesion of molten waste plastic, enabling granulation accompanied by dechlorination and semi-carbonization.

[0027] (biomass powder) The biomass powder or granule of the present invention is not particularly limited as long as it is volatile biomass that generates gases such as carbon monoxide and hydrogen when heated, or combustible biomass, and examples thereof include powder or granule of organic sludge generated from wastewater treatment facilities containing a large amount of organic matter, such as food factories, sewage treatment plants, paper mills, animal farms, etc. The biomass powder or granule of the present invention can also be applied to biomass that has a high chlorine or sulfur content and is therefore unsuitable for use as fuel and difficult to treat, such as bark, bamboo, organic sludge, and livestock manure.

[0028] For example, organic sludge from wastewater treatment discharged from a material recycling processing plant that performs wet gravity separation of the aforementioned container recycling plastics, and polyvinyl chloride (PVC)-containing waste plastics that settle during the wet gravity separation, can be dechlorinated, desulfurized, and semi-carbonized to form pellets in the high-speed rotary mixer, making it possible to effectively utilize them as a solid fuel instead of fossil fuels.This will enable the realization of a zero-emission material recycling plant that does not require industrial waste treatment of polyvinyl chloride (PVC)-containing waste plastics and organic sludge from wastewater treatment, contributing to low CO2 emissions.

[0029] The biomass granular material of the present invention plays a role in suppressing the melting and adhesion of waste plastics and improving the efficiency of dechlorination and desulfurization processes. That is, when the resin temperature rises and the waste plastics melt, the molten plastics adhere to the inside of the mixer due to their melting and adhesion force, but cannot be heated by the local shear heat generated by the mixing blades. The melting and adhesion of waste plastics, which is a factor that hinders dechlorination and desulfurization, can be suppressed by mixing biomass granular material. When biomass granular material and molten waste plastics are mixed and stirred, the melting and adhesion force decreases, and the stirred biomass granular material scrapes off the molten adhesion, suppressing the melting and adhesion, and enabling granulation accompanied by dechlorination and semi-carbonization.

[0030] (solid fuel) As the anti-adhesion material of the present invention, the solid fuel (granules) produced by the manufacturing method of the present invention can be used in place of biomass powder and granules. The solid fuel of the present invention can also be mixed with biomass powder and granules. The solid fuel of the present invention is semi-carbonized, which reduces its melting stickiness when heated, and is dechlorinated and desulfurized, making it useful as a substitute for biomass powder and granules. In other words, adding solid fuel prevents adhesion of molten waste plastics and enables granulation accompanied by dechlorination and semi-carbonization.

[0031] (oil) As the anti-adhesion material of the present invention, instead of biomass powder or solid fuel, oil having a flash point higher than the maximum temperature of the waste plastic and anti-adhesion material during granulation (hereinafter, sometimes referred to as high flash point oil) can be used. Also, this high flash point oil can be mixed with biomass powder or solid fuel.

[0032] Adding oil with a flash point higher than the maximum temperature of the waste plastic and anti-adhesive material during granulation, such as soybean oil with a flash point of 330°C, can prevent adhesion and burning, similar to adding oil to a frying pan to prevent adhesion and burning. Adding this oil forms an oil film inside the mixer, providing lubrication and uniform heat conduction, preventing adhesion and burning and enabling granulation accompanied by dechlorination, desulfurization, and semi-carbonization. Furthermore, mixing waste plastic and high-flash-point oil can improve the higher heating value of the granulated fuel. Waste oil is preferred as the high-flash-point oil. Specifically, the flash point of the high-flash-point oil used is preferably one that exceeds the maximum resin temperature for dechlorination and desulfurization. The maximum resin temperature is preferably a temperature that does not reduce yield. The maximum resin temperature varies depending on the composition of the waste plastic being added, so it is not limited; however, for example, a temperature of 300°C or less is preferred for waste plastic containers and packaging.

[0033] The amount of biomass powder and / or anti-adhesion material added to granulation accompanied by dechlorination, desulfurization, and semi-carbonization is preferably large, since the adhesive strength increases as the resin temperature increases upon melting. Specifically, for example, when waste plastic and biomass powder are added simultaneously to a mixer, the amount is preferably such that the latter penetrates into the gaps between the former and the resulting volume remains the same after mixing. Similarly, when the solid fuel or high-flash-point oil according to the present invention is added simultaneously with the waste plastic, the amount is preferably such that the resulting volume remains the same after mixing.

[0034] The input ratio of waste plastic and anti-adhesion materials (biomass powder, solid fuel, high flash point oil) varies depending on their particle size and bulk density. For example, if the dry bulk density is 0.1t / m 3 , Φ20mm screen for the mass of crushed waste plastic, the dry bulk density of which does not change is 0.8t / m 3 , average particle diameter D 50 The maximum mass of 0.9 mm organic sludge that can be added is approximately 100%. By adjusting the amount of anti-adhesion material added so that the volume does not increase after mixing, the volume of the molten material, which is the most reduced volume, can be kept below 60-70% of the mixer's capacity. This ensures the amount of waste plastic added and the processing capacity, and also enables dechlorination within the time required to process the planned amount, ensuring the planned amount of dechlorination and desulfurization.

[0035] If there is room in the planned waste plastic processing capacity, this does not necessarily mean that the amount of anti-adhesion material added can be increased. The amount of anti-adhesion material added is preferably 1% by mass or more of the waste plastic, more preferably 5% by mass or more, and even more preferably 10% by mass or more. There is no particular upper limit, but it is preferably 1000% by mass or less of the waste plastic, more preferably 600% by mass or less, even more preferably 300% by mass or less, even more preferably 200% by mass or less, and most preferably 100% by mass or less.

[0036] When biomass powder or solid fuel is used as the anti-adhesion material, the size (particle size) and moisture content of the anti-adhesion material fed into the mixer are not particularly limited, and since the powerful shearing of the agitator blades rotating at high speed inside the mixer causes the material to be pulverized, reduced in volume, mixed, dried, kneaded, melted, and then dechlorinated, desulfurized, and torrefied, the smaller the particle size and moisture content of the raw material fed into the mixer, the better. In other words, the smaller the particle size and the lower the moisture content of the anti-adhesion material, the shorter the pulverization, volume reduction, and drying times, ensuring more time for dechlorination within the time required to process the planned amount, and allowing the planned amount of dechlorination and desulfurization to be achieved, making this preferable.

[0037] Specifically, the particle size of the biomass powder and solid fuel is preferably 3.0 mm or less, more preferably 1.5 mm or less, and even more preferably 0.1 to 1.0 mm. The moisture content of the biomass powder and solid fuel is preferably 20 mass % or less, more preferably 10 mass % or less, and even more preferably 5 mass % or less.

[0038] In the method for producing solid fuel of the present invention, the waste plastic melted by the strong local shear heat of the agitator blades is kneaded and coated on the surface of the biomass powder and granules, and the fine powder is bonded by the melt adhesive force, and the dechlorination, desulfurization, and semi-carbonization proceed to form granules. For example, wastewater treatment organic sludge with a particle size of 0.09 mm or less, which accounts for 15% of the total mass, and wastewater treatment organic sludge with a particle size of 1.2 mm or more, which accounts for 40% of the total mass, are mixed together to form a granular granule with a dry bulk density of 0.15 t / m 3 By mixing 10% by mass of the above with waste plastics to be crushed using a Φ20 mm screen and granulating them in a mixer, it is possible to granulate them to a granular particle size as shown in the particle size cumulative distribution in Figure 3 (see Example 2).

[0039] [High-speed rotating mixer] The high-speed rotary mixer directly heats the waste plastics and anti-adhesion materials placed inside it with the powerful shear heat generated by the high-speed rotation of the mixing blades, to a resin temperature of over 180°C as detected by a resin temperature sensor, enabling granulation that involves dechlorination, desulfurization, semi-carbonization, and granulation. Here, the resin temperature in this specification refers to the temperature of the mixture of waste plastics placed inside the high-speed rotary mixer and anti-adhesion materials (biomass powder, solid fuel, oil).

[0040] The solid fuel manufacturing method of the present invention melts plastics by directly heating them using the strong local shear heat of the agitator blades, without the need for external or indirect heating, starting from a resin temperature of room temperature (equivalent to the ambient air temperature). This means that the temperature of the local shear is higher than the resin temperature detected by the resin temperature sensor, and dechlorination of chlorine compounds contained in waste plastics through thermal decomposition can be carried out more efficiently and with less power consumption than in Patent Document 1, which uses external indirect heating.

[0041] If the main components of waste plastics, such as PP (polypropylene), PE (polyethylene), PS (polystyrene), and PET (polyethylene terephthalate), contained in plastic containers, can be kept in a state where they do not undergo thermal decomposition, a decrease in the yield of these main components can be prevented. It is known that PP, PE, PS, and PET undergo thermal decomposition at resin temperatures of 300°C or higher, so if the resin is granulated while maintaining a resin temperature of 300°C or lower, a decrease in the yield of these main components can be prevented. Since the resin temperature at which thermal decomposition occurs varies depending on the components of the waste plastic, the upper limit of the resin temperature is not limited, but the upper limit of the resin temperature is preferably 500°C or lower, more preferably 400°C or lower, and even more preferably 300°C or lower.

[0042] It is also known that polyvinyl chloride (PVC) thermally decomposes at resin temperatures of 200°C or higher, and that the higher the resin temperature, the greater the amount of volatilization. However, in a granulation test (Example 2) using powdered plastic waste and organic sludge of the present invention, it was confirmed that direct heating from strong local shear heat caused hydrogen chloride (HCl) to be generated in the gas released from the volatilized gases at a resin temperature of 160°C, and that the hydrogen chloride concentration rapidly increased at resin temperatures of 180°C or higher, resulting in dechlorination. Therefore, when treating polyvinyl chloride (PVC), the temperature may be 200°C or lower, or 250°C or lower.

[0043] That is, while preventing a decrease in yield, the higher the resin temperature, the greater the amount of volatilization due to thermal decomposition, which increases the amount of chlorine removed and promotes torrefaction. Therefore, a higher resin temperature is desirable, but if it is too high, the yield will decrease. For example, in the case of container recycling plastics, it is preferable to dechlorinate and torrefy the chlorine content to 1% or less at a resin temperature range of 180°C to 300°C, which does not reduce the yield of these main components. Note that if the amount of chlorine removed is prioritized over a decrease in yield, there is no need to limit the upper limit of the resin temperature.

[0044] Examples of high-speed rotary mixers include high-speed flow mixers that mix by rotating a stirring blade attached to the bottom of a container at high speed.Specific examples of high-speed flow mixers include a Henschel mixer and a micro speed mixer.

[0045] The peripheral speed of the impeller during dechlorination and semi-carbonization treatments should be such that the resin can be heated to the above-mentioned resin temperature range by shear heat from the impeller, and cannot be generalized as it depends on the shape of the impeller, etc. However, in the case of a Henschel mixer, for example, the maximum speed is obtained and the maximum shear heat is generated at the outermost periphery of the impeller rotating at high speed. The maximum speed at the outermost periphery varies depending on the capacity of the mixer, but from the perspective of bearing durability, etc., it is generally about 10 to 100 m / s, preferably 20 to 80 m / s, and more preferably 30 to 50 m / s.

[0046] The smaller the capacity of the mixer, the smaller the outer circumference of the agitator blades, so the rotation speed (rpm) of the agitator blades becomes higher. The higher the outer circumference speed, the higher the shear heat generated. By mixing at such a speed, the waste plastic (and anti-adhesion material) in the vertical container is subjected to the strong shear force of the agitator blades rotating at high speed, generating strong local shear heat, which can directly heat the waste plastic (and anti-adhesion material).

[0047] In a high-speed fluid mixer such as a Henschel mixer, direct heating by the powerful local shear of rapidly rotating agitating blades can be used to perform granulation accompanied by dechlorination, desulfurization, torrefaction, and granulation with low power consumption and high efficiency, rather than external indirect heating in which heating is performed through the mixer walls using an electric heater, etc. The method for producing solid fuel of the present invention does not require external indirect heating, but it is possible to supplement direct heating by powerful local shear heat with external indirect heating in order to increase the granulation processing capacity for dechlorination, desulfurization, and torrefaction, and the amount of dechlorination and desulfurization.

[0048] If the amount of chlorine removed by granulation using direct heating by strong local shear heat and supplemented by external indirect heating is the same as the amount of chlorine removed by granulation using external indirect heating and direct heating by local low shear heat through the cylinder of a twin-screw type dechlorination device such as that in Patent Document 1, the former (the present invention) will have lower power consumption and higher efficiency.

[0049] In the solid fuel production method of the present invention, the resin temperature exceeds 180°C due to localized direct heating caused by the powerful shear heat generated by the high-speed rotating agitator blades. This melts the waste plastic and thermally decomposes chlorine-containing compounds, such as polyvinyl chloride (PVC), contained in the waste plastic, thereby volatilizing and removing the chlorine components (dechlorination). Furthermore, when biomass powders, such as organic sludge, contain sulfur-containing compounds, the sulfur-containing compounds can be thermally decomposed to volatilize and remove the sulfur components (desulfurization). In a granulation test (Example 2) using waste plastic and organic sludge, the concentrations of hydrogen chloride (HCl) and sulfur oxide (SO2) in the exhaust gas rapidly increased from a resin temperature of 180°C due to the powerful localized shear heat generated by the high-speed rotating agitator blades, resulting in desulfurization. Furthermore, the solid fuel production method of the present invention can thermally decompose and volatilize organic biomass powders, converting them into substances with a high carbon content (semi-carbonization).

[0050] The more waste plastic is put into the mixer (filling amount), the higher the density of the waste plastic near the local area that comes into contact with the agitator blades, allowing more waste plastic to be sheared. At the same time, the high-density waste plastic that flows through the mixer due to the agitator blades comes into contact with the mixer's inner wall, increasing resistance and increasing local shear force. As a result, shear heat due to direct heating increases, the resin temperature rises more quickly over time, and processing capacity improves.

[0051] The mixer is a batch-type process that uses high-speed rotating agitator blades to crush, reduce volume, and mix materials, while also directly heating them to the extent that they are dried, kneaded, and melted using powerful local shear heat, and can granulate them by dechlorinating, desulfurizing, and semi-carbonizing them.

[0052] As described above, the amount that can be fed into the mixer is preferably such that the volume of the molten material, which is the most reduced volume, is 60 to 70% or less of the mixer capacity. In one-cycle batch processing, if the volume of the molten material in a single feeding is less than 60 to 70% of the mixer capacity, it is preferable to feed the waste plastic and anti-adhesion material two or more times and perform batch processing at 60 to 70%.

[0053] [Efficient dechlorination, desulfurization, and torrefaction for the production of granular solid fuel] The high-speed rotary mixer uses strong local shearing at the points where the mixer blades come into contact to agitate the waste plastics while pulverizing, reducing the volume, and mixing them, and also directly heats them to the extent that they dry, knead, and melt using strong local shear heat, thereby carrying out dechlorination, desulfurization, and semi-carbonization.This is a batch processing method, but a continuous processing method is also possible.In the production method of the present invention, it is preferable to use multiple batch processing high-speed rotary mixers and stagger the timing of dechlorination, which consumes the most power in one batch processing, to reduce the maximum power consumption and achieve efficient processing.

[0054] The high-speed rotary mixer can control the rotation speed by driving a motor via an inverter to rotate the agitator blades. In Example 2 of the present invention, it was confirmed that the higher the current value of the motor that rotates the mixer's agitator blades, the stronger the shear force of the agitator blades, the higher the resin temperature, and the stronger the dechlorination and desulfurization performance. Furthermore, in Example 3 of the present invention, by operating the motor at a current value as close as possible to the rated current value, high processing capacity and high dechlorination and desulfurization rates were possible. Furthermore, it was confirmed that even if the rotation speed of the agitator blades decreases, as long as it is close to the rated current value, efficient processing capacity can be maintained and semi-carbonized granules can be produced through the dechlorination and desulfurization processes.

[0055] Furthermore, slowing the rotation speed of the agitator blade weakens the shear force, which reduces the resin temperature and the current value of the motor. Therefore, slowing the rotation speed reduces the current value of the motor and prevents the motor from being overloaded.

[0056] If the resin temperature is too low, increasing the rotation speed will increase the resin temperature and motor current. By adjusting the rotation speed, the resin temperature and motor current can be controlled, allowing operation as close to the rated current as possible. This achieves the highest processing capacity and dechlorination / desulfurization treatment, enabling highly efficient treatment.

[0057] (Air or inert gas purging) When heating above 180°C due to shear heat from the agitator blades of a high-speed rotary mixer, it is preferable to perform a purging process using air or inert gas. The purging process not only adjusts the exhaust temperature but also the concentration of HCl and other volatiles that fill the mixer due to dechlorination and desulfurization. High concentrations of HCl and other volatiles in the mixer can cause corrosion problems, so a high purging rate is preferable. The purging rate varies depending on the mixer capacity and the amount of dechlorination and desulfurization, so a general limit cannot be set. However, a ventilation rate of approximately 1x the mixer capacity per minute is preferable. For example, for a 20L mixer, a room-temperature purging rate of approximately 20L / min or more is preferable. Inert gases such as nitrogen can be used instead of air for the process, but using inert gas is safer as it prevents fires due to high resin temperatures and other high-temperature problems.

[0058] Strengthening dechlorination and desulfurization generates large amounts of acidic gases such as HCl and SO2, which can cause corrosion of metal machinery inside the mixer and exhaust pipes, leading to breakdowns and other problems. Purging with air or inert gas can dilute the acidic gas concentration and reduce the risk of corrosion problems, but it also lowers the temperature of the exhaust gas that evaporates inside the mixer and is then discharged. The temperature range in which dechlorination and desulfurization occur exceeds the dew point of HCl and SO2, approximately 120°C, at which corrosion accelerates, so corrosiveness is suppressed in the dechlorination temperature range.

[0059] In order to reduce the risk of corrosion by purging with air or inert gas, it is preferable not only to minimize the concentration of acidic gas components, but also to adjust the purge amount so that the exhaust temperature does not fall below the dew point of HCl and SO2. The correlation between the purge amount and the exhaust temperature varies depending on the mixer capacity, the amount of resin input, the rotation speed of the agitator blades, the resin temperature, the motor rating, etc., and therefore cannot be generally determined. For example, in Example 3, the minimum exhaust temperature during dechlorination was 160°C when the room-temperature purge amount was 1.25 times the mixer capacity per minute, and the maximum exhaust temperature during dechlorination was 234°C when it was 2.75 times the mixer capacity.

[0060] (Water treatment) The hydrophobic resin heated to a high temperature through dechlorination, desulfurization, semi-carbonization, and granulation in a high-speed rotary mixer is preferably rapidly cooled by adding water while stirring, like hot oil exploding violently, and then solidified and granulated while being pulverized. That is, the granulation is preferably carried out by melting the waste plastic to dechlorinate and semi-carbonize it using shear heat from the stirring blades, and then adding water to solidify and granulate the waste plastic. This shortens the granulation time and enables efficient granulation compared to granulation without adding water, as in Example 2 of the present invention.

[0061] In addition, the water expands 1,700 times in one go, generating steam, which is then released, and at the same time, the thermally expanded metal mixer contracts all at once, removing any deposits that have adhered to the mixer's inner walls, just as pouring water on a burnt frying pan removes the burnt food instantly. If water-soluble chlorine or sulfur compounds are contained in the waste plastics and anti-adhesion materials that have been subjected to direct heating treatment using strong local shear heating, these can be dissolved in the treated water and discharged together with the water. After the water treatment, the waste is usually subjected to solid-liquid separation and drying, and the solid fuel is recovered from which the water-soluble chlorine and sulfur compounds have been dechlorinated and desulfurized.

[0062] The treated water used for adding water may contain a neutralizing agent that neutralizes dissolved chloride compounds such as hydrogen chloride and sodium chloride. Specific examples of the neutralizing agent include caustic soda.

[0063] The more water is added, the smaller the granule size becomes, and the better the cleaning performance against water-soluble inorganic chlorine, redeposited HCl, etc. and the ability to remove fused adhesions. Therefore, a larger amount of water is preferable. However, if the amount is too much, the burden on the subsequent cleaning, solid-liquid separation, drying and wastewater treatment processes increases, so it is preferable to add water to a mass that can be subjected to cleaning, solid-liquid separation, drying and wastewater treatment plus the evaporated mass.

[0064] The amount of evaporation varies depending on the mixer capacity and the temperature of the resin to be watered, so it cannot be generally determined, but the mass (total mass of resin and biomass powder, etc.) added when the resin temperature is around 250°C is a good guide for the evaporation mass. Furthermore, since water can be added in an emergency if the resin temperature becomes abnormally high, the water-adding device is also suitable as a safety device for preventing fires, etc. The amount of water added is preferably 50% by mass or more of the waste plastic, more preferably 100% by mass or more, and even more preferably 200% by mass or more, from the perspective of the promotion effect and removal of deposits inside the mixer. Furthermore, the upper limit is preferably 800% by mass or less.

[0065] [Low-cost and efficient dechlorination, desulfurization, torrefaction, and granular solid fuel production equipment] When waste plastics and anti-adhesion materials that have been heat-treated using shear heat contain small amounts of water-soluble chlorine compounds, sulfur compounds, or redeposited HCl, reducing the amount of water added makes it possible to treat the granulated product without affecting its chlorine, sulfur, particle size, or moisture content. This allows for the performance of washing, solid-liquid separation, and drying processes to be reduced, or these facilities to be omitted and solid fuel to be recovered directly. As a result, initial and running costs related to wastewater treatment can be reduced, and CO2 emissions can be reduced due to lower power consumption.

[0066] This dechlorination, desulfurization, and torrefaction granulation equipment uses a high-speed rotary mixer with an amount of water added that eliminates the need for wastewater treatment, and direct heating through powerful local shear heat.When installed in the aforementioned zero-emission material recycling plant, it can replace the granulation equipment of the waste plastic dechlorination treatment device described in Patent Document 1, which uses a low-shear force twin-screw system with external indirect heating through a cylinder.However, the former granulation equipment (this invention) has the same processing capacity, is approximately 20% lower in initial cost, and produces solid fuel with the same dechlorination rate and residual chlorine content of 1% or less, with lower running costs and lower CO2 emissions due to lower power consumption due to lower resin temperature.Furthermore, the latter does not form a zero-emission plant because it treats organic sludge from wastewater treatment as industrial waste.

[0067] [Unexpected semi-carbonized granules formed during dechlorination and desulfurization treatment using a high-speed rotary mixer (Example 2)] As mentioned above, PP, PE, PS, and PET do not undergo thermal decomposition and volatilization until the resin temperature exceeds 300°C. However, polyvinyl chloride (PVC) begins thermal decomposition, volatilization, and carbonization at resin temperatures above 200°C. 87.3% by mass of waste plastic containers and packaging (81.1% PP, PE, PS, and PET blend, 3.8% ash, 2.4% PVC), 8.0% by mass of organic sludge (4.0% ash), and 4.7% soybean oil (with a flash point of 330°C, lower than the ignition point) were fed into a mixer. Due to the powerful local shear heat generated by the high-speed rotating impeller, dechlorination and desulfurization proceeded even at resin temperatures below 258°C, resulting in a loss of melt adhesion. As a result, the current of the impeller drive motor decreased, and the resin temperature dropped to a range where dechlorination was not possible. Granulation was then performed without adding water. The resulting product, shown in Figure 3, was a black granular product.

[0068] The amount of volatilization of the obtained granules was analyzed based on industrial analysis (JISM8812), and it was found that 28.5% of the dry input mass to the mixer was volatilized, resulting in semi-carbonized granules.

[0069] As mentioned above, the amount of organic sludge volatilized at a resin temperature of 258°C or less is about 6.4% by mass, which is a total of polyvinyl chloride (PVC) and ash, but unexpectedly, semi-carbonized granulation was achieved, with volatilization of about four times more than the amount of organic sludge. In addition, in this granulation test, water was added in a semi-molten state at the resin temperature before the resin melted in a similar mixer, and the average particle diameter D 50 We expected to produce granules of about 1 to 2 cm in size, but in fact, we were able to produce granules of a granular size without adding water, as shown in Figure 3. As shown in the results of Example 2 of the present invention, the unexpected formation of semi-carbonized granules was confirmed as a result of the dechlorination and desulfurization treatment using a high-speed rotary mixer.

[0070] [Dechlorination, desulfurization, torrefaction, granular solid fuel] According to the method for producing a solid fuel of the present invention, the chlorine content is 1.0% or less, and the bulk density is 0.4 t / m 3 Above, average particle diameter D 50It is possible to produce a solid fuel having a particle size of 10.0 mm or less, with 90% or more of the total particles having a particle size of 0.01 mm or more, and an angle of repose of 50° or less. Furthermore, by the solid fuel production method of the present invention, it is possible to produce a solid fuel having a chlorine content of 1.0 mass% or less, a higher heating value of 25 MJ / kg or more, a moisture content of 5 mass% or less, and an ash content of 10 mass% or less, which conforms to the RPF quality standard. Furthermore, by the solid fuel production method of the present invention, it is possible to produce a solid fuel having a sulfur content of 1% or less.

[0071] The granular solid fuel of the present invention will now be described. The granular solid fuel of the present invention is a granular solid fuel containing plastic, has a chlorine content of 1.0 mass % or less, and a bulk density of 0.4 t / m 3 Above, average particle diameter D 50 It is characterized by having a particle size of 10.0 mm or less, with 90% or more of the total particles being 0.01 mm or more, and an angle of repose of 50° or less.

[0072] The chlorine content of the granular solid fuel of the present invention is preferably 1.0 mass% or less, more preferably 0.8 mass% or less, and even more preferably 0.6 mass% or less. In the present invention, the chlorine content of the solid fuel can be reduced by raising the resin temperature efficiently at low cost. In addition, the bulk density is 0.4 t / m 3 More than 0.5t / m 3 More than 0.6t / m is preferable. 3 More preferably, 0.7t / m 3 The above range is more preferable. By having the bulk density in this range, it is possible to reduce the cost of transportation and handling. In addition, the average particle diameter D 50 teeth 、 The average particle diameter D is 10.0 mm or less, preferably 5.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.6 mm or less. 50This range improves combustibility and compatibility with coal. Furthermore, the particle size is such that 90% or more of the total particles are 0.01 mm or larger, preferably 0.05 mm or larger, more preferably 0.08 mm or larger, and even more preferably 0.1 mm or larger. By maintaining the particle size within this range, scattering and dust explosions can be suppressed. Furthermore, the angle of repose is preferably 50° or smaller, more preferably 40° or smaller. A repose angle within this range reduces clogging of the flow path of the equipment and facilitates transport. Regarding sulfur content, while there are no established standards for the sulfur content of solid fuels such as RPF, a sulfur content testing method for waste-derived fuels is established in JIS Z 7302-7. This measurement method can be used to ensure compliance with sulfur content regulations at shipping destinations. For example, Fukuoka City has measures regarding the use of petroleum-based fuels with a sulfur content standard of 1.0% or less. The sulfur content of the granular solid fuel of the present invention can be 1.0% or less.

[0073] The solid fuel produced in the examples of the present invention has a particle size of approximately 0.1 mm or more, so there is almost no scattering of fine powder, making it easy to handle and reducing the risk of dust explosions. Furthermore, the angle of repose is approximately 30-40°, which is the same as that of commercially available RPF pellets (particle size diameter 6-40 mm x length 2-3 times the diameter, approximately 30-40°, bulk density 0.3-0.5 t / m). 3 ), but because the particle size is small, bridging between particles is less likely to occur at the tank outlet, making it easier to transport by equipment. In addition, the bulk density is 0.9t / m 3 Therefore, the bulk density of RPF pellets in circulation is 0.3 to 0.5 t / m 3 It is larger than conventional RPF pellets, which reduces transportation and shipping costs. Furthermore, as a fuel, its particle size is smaller than that of commercially available RPF pellets, making it easier to inject into a combustion furnace and allowing for rapid combustion. It can also be easily mixed with coal, and by torrefying the biomass powder, its energy density per unit weight increases, its calorific value approaches that of coal, and its water resistance improves. This makes it easier to crush, and it can also be easily mixed with pulverized coal. As a result, handling for storage, transportation, and combustion improves, allowing for a higher coal mixed-firing ratio, contributing to lower CO2 emissions and lower costs. Due to the above characteristics, the solid fuel manufacturing method of the present invention can produce granular solid fuel that is equivalent to or better than commercially available RPF solid fuel and is superior in terms of quality and functionality, and can be used as an alternative fuel to heavy oil, coal, etc.

[0074] [Can handle the quality of solid fuels such as RPF] The solid fuel manufacturing method of the present invention can produce granular solid fuel of a quality stipulated in the RPF quality standard. Specifically, by blending waste plastic, biomass powder, and oil that meet the RPF quality requirements specified in JIS Z 7311:2010, "Solid Fuel (RPF) from Waste Materials, Including Paper and Plastics," it is possible to produce solid fuel that meets the RPF quality requirements of a higher heating value of 25 MJ / kg or more, a moisture content of 5% by mass or less, and an ash content of 10% by mass or less. For blends that meet RPF quality, it is preferable to use raw materials with as little ash as possible, which affects the higher heating value. The lower the ash content, the higher the higher heating value, which extends the life of the mixer's agitator blades and other components against wear. Regarding wear, we note that increasing the hardness of the agitator blades and the interior of the mixer chamber, which come into contact with the waste plastic and biomass powder, through quenching, can extend the life of the components.

[0075] In the examples, organic sludge from wastewater treatment that has been subjected to compost fermentation (ash content 50.4% by mass, higher heating value 11.2 MJ / kg), which is readily available and readily available, was used as the biomass powder and granules. However, if organic sludge from food factory wastewater treatment (ash content 14.6% by mass, 17.0 MJ / kg) were used, the amount of sludge that conforms to RPF quality could be doubled. Furthermore, if woody biomass powder and granules, which have low ash content and high heating value, are used, the amount of biomass powder and granules that conform to RPF quality could be increased more than organic sludge. This does not apply if the quality of the solid fuel required by the shipping destination does not require compliance with RPF quality. [Example]

[0076] FIG. 1 shows an outline of a method for producing a solid fuel according to an embodiment of the present invention. Solid fuel was produced using the high-speed fluid mixer shown in Figure 2. The top of the high-speed fluid mixer (high-speed rotary mixer) 1 contains a container 2 equipped with a raw material inlet 3, an exhaust outlet 4, a hydration nozzle 5 for spraying treated water, and an air purge nozzle 6 for spraying air or inert gas during dechlorination. The bottom of the container 2 is equipped with upper and lower impellers 7 and a discharge valve 8. A resin temperature sensor 9 is installed inside the container 2 to detect the resin temperature. An exhaust temperature sensor 10 installed at the exhaust outlet detects the temperature of the exhaust gas. The black arrows in the figure indicate the movement of the processed material within the device.

[0077] Table 1 shows an overview of the test conditions.

[0078] [Table 1]

[0079] Specifically, the following tests were carried out and evaluated. The waste plastic (resin) used as raw material was sediment from container recycling (mainly a mixture of PP, PE, PS, and PET (92.8% by mass), ash content 4.4% by mass DB, PVC 2.8% by mass (equivalent to a chlorine content of 1.57% by mass DB)). Wastewater treatment organic sludge (ash content 50.4 mass% DB, chlorine content 1.13 mass% DB, sulfur content 0.61 mass% DB) was used as the raw material biomass powder. Soybean oil (chlorine content <0.02 mass% DB, sulfur content <0.02 mass% DB, flash point 330°C) was used as the raw material oil.

[0080] Sediment and organic sludge from container recycling plastics were fed into a high-speed fluid mixer, where they were fluidized and stirred by high-speed rotating impellers with a maximum tip speed of 56 m / s, while being pulverized, reduced in volume, and mixed. At the same time, they were directly heated to the extent that they dried, kneaded, and melted using only powerful local shear heat, and were dechlorinated, desulfurized, semi-carbonized, and granulated. While the mixer was operating, the water vapor, chlorine-based gases, and sulfur-based gases generated were treated as safe exhaust gases by exhaust gas cleaning equipment such as wet scrubbers, where the chlorine and sulfur were removed. Air purging was performed during this dechlorination process. The motor was driven via an inverter, and the rotation speed was adjusted.

[0081] [Example 2 Evaluation: Unexpected semi-carbonized granule formation during dechlorination and desulfurization treatment using a high-speed rotary mixer] 2 kg of wet resin containing polyvinyl chloride (PVC), 0.2 kg of wet organic sludge containing chlorine and sulfur, and 0.1 kg of soybean oil were placed in a mixer. Direct heating from the agitator blades alone melted the resin, and once the resin temperature exceeded approximately 160°C, the chlorine contained in the resin and the sulfur contained in the organic sludge thermally decomposed, generating hydrogen chloride (HCl) and sulfur dioxide (SO2), which were then vented. As the resin temperature rose above 180°C, the concentrations of hydrogen chloride and sulfur dioxide increased sharply, resulting in dechlorination and desulfurization. The resin reached a maximum temperature of 258°C, completing dechlorination and desulfurization. Carbonization of the resin progressed, reducing shear strength. The resin temperature decreased without the addition of water, resulting in the production of a semi-carbonized black granular product (dry bulk density 0.92 t / m 3 , dry angle of repose 35°).

[0082] An air purge of 60 L / min during dechlorination reduced the hydrogen chloride and sulfur dioxide concentrations inside the mixer chamber and in the exhaust, and the exhaust temperature during dechlorination remained above 150°C, which suppresses dew-point corrosion. The curves for motor current, resin temperature, and exhaust concentrations (hydrochloric acid, sulfur dioxide) each showed a correlated increase and decrease characteristic.

[0083] As shown in Figure 3, the cumulative undersieve particle size distribution of the granular solid fuel granulated without adding water shows that the particle size is larger than the powder particle size, approximately 0.1 mm to 1.2 mm (approximately 90% by mass undersieve), and the average particle size is 0.57 mm-D50 The granulation was carried out.

[0084] Although no standard value or method for calculating the degree of torrefaction has been established, the material was torrefied to an index carbonization degree (dry volatilization amount due to treatment ÷ dry volatilization amount before treatment) of 32.0 mass%. At resin temperatures below 258°C, volatilization should be small, at around 6.4 mass% of the dry input amount (PVC, organic sludge excluding ash), but in fact 28.5 mass% of the dry input amount volatilized. The amount of volatilization before and after treatment was analyzed in accordance with JIS M 8812, an industrial analysis standard useful for the waste-derived fuel testing method (JIS Z 7302).

[0085] [Example 3 Evaluation: Granulation and washing method and granule properties with the same dechlorination rate at a lower resin temperature compared to Patent Document 1 and Non-Patent Document 1] 3 kg of resin containing polyvinyl chloride (PVC) (2 kg + 1 kg added twice) and 1.2 kg of organic sludge containing chlorine and sulfur were added to the mixer, and dechlorination, desulfurization, semi-carbonization, and granulation were carried out using direct heating only from the shear heat of the mixing blades. A large amount of water (6 L) was added during mixing (cooling solidification, melting adhesion removal, chlorine and sulfur washing) to produce semi-carbonized black granular product (dry bulk density 0.88 t / m 3 At a maximum resin temperature of 280°C, the chlorine content went from 1.45% DB to 0.68% DB (index dechlorination rate 53%) and the sulfur content went from 0.16% DB to 0.068% DB (index desulfurization rate 56%). There was almost no adhesion inside the mixer chamber or on the mixing blades.

[0086] Index dechlorination / desulfurization rate = (amount of chlorine / sulfur input - amount of chlorine / sulfur input from solid fuel) ÷ amount of chlorine / sulfur input

[0087] Air purging during dechlorination controls the hydrogen chloride and sulfur dioxide concentrations in the mixer chamber and exhaust, as well as the exhaust temperature, and the exhaust temperature during dechlorination remains above 150°C, which suppresses dew-point corrosion. By adjusting the frequency of the mixing blade motor, the correlated resin temperature and motor current value can be controlled, and the motor does not shut down due to overload, and the material is dechlorinated, desulfurized, semi-carbonized, and granulated.

[0088] After adding a large amount of water, the mixture is stirred, granulated, and washed, and then the granulated product is discharged in a mixed state with the water. The chlorine and other substances contained in the granulated product are washed away by solid-liquid separation, and when the quality of the separated liquid was measured, it showed an acidity similar to that of HCl. The liquid after washing with water and solid-liquid separation had a pH of 5.0 (acidic) and a total chlorine content of 4.8 mg / L.

[0089] As shown in Figure 3, the cumulative particle size distribution of the granular product is larger than the powder particle size, with a particle size of approximately 0.1 mm to 1.2 mm (approximately 85% of the mass is under the sieve), and the average particle size is 0.56 mm-D. 50 A granulation of 100g was produced.

[0090] [Comparative evaluation of Example 1 and Example 2: Higher input amount leads to higher shear heat] With the same input materials, blending ratio, and agitator blade rotation speed, the processing time from start of operation to maximum resin temperature (direct heating process using only agitator blade shear heat) was 1 hour 54 minutes for Example 1 and 45 minutes for Example 2. Example 2, which had 1.33 times the input amount of Test 22, was 69 minutes (61%) shorter than Example 1, which means that the shear heat increases when the input amount is large.

[0091] [Comparative evaluation of Example 2 with Examples 4 and 5: Effect of adding water and increasing the amount of organic sludge on preventing melting and adhesion] The contribution to preventing melting and adhesion due to an increase in the amount of organic sludge was demonstrated from the state of melting and adhesion inside the mixer and on the agitator blades after granulation in Examples 2 and 4. Furthermore, the effect of adding water to remove adhered matter was demonstrated from the state of melting and adhesion inside the mixer and on the agitator blades after granulation in Examples 2 and 5. [Industrial Applicability]

[0092] The solid fuel produced by the method of the present invention can be used as a fuel to replace heavy oil or coal, and is therefore industrially useful, complying not only with the Containers and Packaging Recycling Law and the Plastic Resource Circulation Strategy, but also with the Basic Energy Plan and the Feed-in Tariff System. [Explanation of symbols]

[0093] 1 high-speed rotary mixer 2 containers 3 Inlet 4 exhaust port 5 Water nozzle 6 Air purge nozzle 7 Stirring blade 8. Discharge valve 9 Resin temperature sensor 10 Exhaust gas temperature sensor

Claims

1. A method for producing solid fuel, comprising the steps of: stirring waste plastics and anti-adhesion material in a high-speed rotary mixer; heating the waste plastics and anti-adhesion material to a temperature of over 180°C by shear heat generated by stirring blades; and granulating the waste plastics and anti-adhesion material while dechlorinating and semi-carbonizing the waste plastics; A method for producing solid fuel, characterized in that the anti-adhesion material is at least one selected from biomass powder, the solid fuel, and oil having a flash point higher than the maximum temperature of the waste plastic and anti-adhesion material during granulation.

2. 2. The method for producing a solid fuel according to claim 1, wherein the produced solid fuel has a chlorine content of 1.0 mass % or less.

3. 2. The method for producing a solid fuel according to claim 1, wherein the adhesion preventing material contains at least biomass powder and granular material, and the biomass powder and granular material is organic sludge powder and granular material generated from a wastewater treatment facility.

4. 3. The method for producing a solid fuel according to claim 2, wherein the adhesion preventing material contains at least biomass powder and granular material, and the biomass powder and granular material is organic sludge powder and granular material generated from a wastewater treatment facility.

5. 5. A method for producing solid fuel according to any one of claims 1 to 4, characterized in that the granulation involves melting waste plastics by shear heat of the stirring blades, dechlorinating and semi-carbonizing them, and then adding water to solidify and granulate the waste plastics.

6. The method for producing a solid fuel according to any one of claims 1 to 4, characterized in that a purging treatment with air or an inert gas is carried out when heating the mixture to above 180°C by shear heat of the stirring blades of the high-speed rotary mixer.

7. 6. The method for producing a solid fuel according to claim 5, wherein a purging treatment with air or an inert gas is carried out when the mixture is heated to a temperature exceeding 180°C by shear heat of the stirring blades of the high-speed rotary mixer.

8. 6. The method for producing a solid fuel according to claim 5, wherein the water used for the hydration contains a neutralizing agent for neutralizing chlorinated compounds.

9. 5. The method for producing a solid fuel according to any one of claims 1 to 4, wherein the produced solid fuel has a chlorine content of 1.0 mass% or less, a higher heating value of 25 MJ / kg or more, a moisture content of 5 mass% or less, and an ash content of 10 mass% or less, which comply with the RPF quality standards.

10. The solid fuel produced has a chlorine content of 1.0 mass% or less and a bulk density of 0.4 t / m ３ Above, average particle diameter D ５０ 5. The method for producing a solid fuel according to claim 1, wherein the particle size of the particles is 10.0 mm or less, and 90% or more of the particles have a particle size of 0.01 mm or more and an angle of repose of 50° or less.

11. 5. The method for producing a solid fuel according to claim 1, wherein the produced solid fuel has a sulfur content of 1% by mass or less.

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