Manufacturing method of solid fuel

Abstract

The present invention provides a method for producing solid fuel that can be dechlorinated and semi-carbonized by shear heat generation of a stirring blade without using external heating. [Solution] A method for producing solid fuel, wherein waste plastic and an anti-adhesion agent are stirred in a high-speed rotary mixer and heated to over 180°C by shear heating of the stirring blades, and granulation accompanied by dechlorination and semi-carbonization is performed, characterized in that the anti-adhesion agent 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 plastic and anti-adhesion agent during granulation.

Description

[Technical Field]

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

[0002] At the 2015 G7 Summit, it was raised that "marine debris and plastic waste are global issues." In Japan, to prevent waste plastics that have nowhere else to go from being illegally dumped into the ocean, the amount of temporary storage for waste plastics was doubled in 2019, and the "Plastic Resource Recycling Strategy" was formulated in May of the same year. The "Plastic Resource Recycling Strategy" outlines directions for recycling container and packaging plastics (packaging plastics) and non-packaging plastics discharged from general households at low cost and with low CO2 emissions, achieving a high resource recovery rate including heat recovery, aiming for zero marine plastic emissions, and thoroughly eradicating illegal dumping. According to the Ministry of the Environment's report on illegal dumping in fiscal years 2020 and 2021, waste plastics, sludge, and wood chips are listed as incinerable waste among non-construction waste. Criticism has also been directed at the greenhouse gases generated when illegally dumped waste originating from marine plastics is incinerated.

[0003] On the other hand, technologies for recycling waste plastics and waste paper into solid fuels such as RPF (Refuse-derived paper and plastics densified fuel) are known. However, given that waste plastics with a high percentage of polyvinyl chloride (PVC), which contains chlorine and is considered unsuitable as fuel, have increased waste disposal costs and are often illegally dumped, the current practice of considering waste plastics unsuitable as fuel unless they contain 0.3% or less chlorine, as JIS Z7311:2010 "Solid fuels from waste-derived paper, plastics, etc. (RPF)" dictates, is being reviewed. The RPF industry is moving towards easing acceptance requirements to allow the use of waste plastics with a chlorine content of 1% or less as fuel.

[0004] As a technology for dechlorinating waste plastics with high chlorine content, for example, a twin-screw type dechlorination treatment device that heats by external indirect heating has been proposed. For example, a twin-screw type dechlorination device has been proposed as such a dechlorination treatment device (Patent Document 1). Patent Document 1 states that "if the device does not actively have a mixing and kneading function, the energy efficiency is poor and uniform dechlorination cannot be performed. In the embodiment of the invention, the molten waste plastic is heated by the heater, passing through the cylinder of the dechlorination device (external indirect heating), and its temperature is further raised. A twin-screw rotating screw that actively has a mixing and kneading function applies a shearing action to cause shear heating, so that the molten waste plastic can be efficiently heated and thermally decomposed." However, detailed data on the shearing action and processing capacity are not described.

[0005] Furthermore, a dechlorination technology for waste plastics using a twin-screw dechlorination device has been reported (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, the general waste plastic chlorine content of 1.8 wt% is dechlorinated to a residual chlorine concentration of slightly over 0.8 wt% (about half of the input chlorine amount) by the shear action of a twin-screw rotating screw with an outer diameter of 174 mm and an outer circumference speed of about 0.37 m / s, passing through a cylinder to a heating temperature of 310°C by external indirect heating and a residence time of 10 minutes or more, where the concentration remains constant." However, detailed data on processing capacity is not provided. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-86447 [Non-patent literature]

[0007] [Non-Patent Document 1] Masayoshi Tokihisa et al., "On a Plastic Dechlorination Solid Fuel Device," Journal of the Japan Paper and Pulp Technology Association, Vol. 55, No. 5, pp. 82-88, May 2001. [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a method for producing granular solid fuel that has been dechlorinated and semi-carbonized 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 by heating waste plastics and an anti-adhesion material to over 180°C in a high-speed rotary mixer using shear heat from the stirring blades, and then granulating them, dechlorinated and semi-carbonized granular solid fuel could be produced, thus completing the present invention.

[0010] In other words, the present invention is as follows: [1] A method for producing solid fuel, in which waste plastic and an anti-adhesion material are stirred in a high-speed rotary mixer and heated to over 180°C by shear heat of the stirring blades, thereby performing granulation accompanied by 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 and granules, the solid fuel, and the waste plastic used during granulation and oil, which has a flash point higher than the highest temperature of the anti-adhesion material. [2] The method for producing a solid fuel according to [1] above, characterized in that the solid fuel produced has a chlorine content of 1.0% by mass or less. [3] The method for producing solid fuel according to [1] or [2] above, characterized in that the anti-adhesion material includes at least biomass powder and granules, and the biomass powder and granules are organic sludge powder and granules 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 is performed by melting the waste plastic by the shear heat of the stirring blade, dechlorinating and semi-carbonizing it, and then adding water to solidify the waste plastic and form it into granules. [5] When heating above 180°C by the shear heat of the stirring blade of the high-speed rotary mixer, a purge treatment with air or an inert gas is performed, and the method for producing a solid fuel according to any one of the above [1] to [4] is characterized thereby. [6] The method for producing a solid fuel according to [4] above, wherein the water used for the water addition contains a neutralizing agent that neutralizes a chloride compound.

[0012] [7] The method for producing a solid fuel according to any one of the above [1] to [6], wherein the solid fuel produced has a chlorine content of 1.0 mass% or less, conforms to the RPF quality standard, has a gross calorific value of 25 MJ / kg or more, a moisture content of 5 mass% or less, and an ash content of 10 mass% or less. [8] The solid fuel produced has a chlorine content of 1.0 mass% or less, a bulk density of 0.4 t / m 3 or more, an average particle diameter D 50 of 10.0 mm or less, and 90% or more of all the particles have a particle size of 0.01 mm or more and an angle of repose of 50° or less, and the method for producing a solid fuel according to any one of the above [1] to [7] is characterized thereby. [9] The method for producing a solid fuel according to any one of the above [1] to [8], wherein the solid fuel produced has a sulfur content of 1 mass% or less.

[0013]

[10] A granular solid fuel containing plastic, having a chlorine content of 1.0 mass% or less, conforming to the RPF quality standard, having a gross calorific value of 25 MJ / kg or more, a moisture content of 5 mass% or less, and an ash content of 10 mass% or less.

[11] A granular solid fuel containing plastic, having a chlorine content of 1.0 mass% or less, a bulk density of 0.4 t / m 3 or more, an average particle diameter D 50 of 10.0 mm or less, and 90% or more of all the particles have a particle size of 0.01 mm or more and an angle of repose of 50° or less.

Advantages of the Invention

[0014] According to the method for producing a solid fuel of the present invention, a granular solid fuel that has been dechlorinated and semi-carbonized by the shear heat of the stirring blade can be produced without using external heating. [Brief explanation of the drawing]

[0015] [Figure 1] This is an explanatory diagram for a method of producing solid fuel according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram of the high-speed rotary mixer used in the example. [Figure 3] This figure shows the cumulative particle size distribution after sieving of the solid fuels obtained in Example 2 and Example 3. [Modes for carrying out the invention]

[0016] The present invention relates to a method for producing solid fuel, which involves stirring waste plastic and an anti-adhesion agent in a high-speed rotary mixer and heating them to over 180°C by shear heating of the stirring blades, thereby performing granulation accompanied by dechlorination and semi-carbonization, characterized in that the anti-adhesion agent is at least one selected from biomass powder or granules, solid fuel, and oil, which has a flash point higher than the maximum temperature of the waste plastic and anti-adhesion agent during granulation.

[0017] The present invention provides a method for producing solid fuel by heating waste plastic and a specific anti-adhesion material in a high-speed rotary mixer using shear heat from the stirring blades without external heating, thereby producing dechlorinated and semi-carbonized granular solid fuel. Furthermore, if the biomass powder contains sulfur-containing compounds, the sulfur components can be removed by thermal decomposition (desulfurization).

[0018] Furthermore, the present invention's method for producing solid fuel prevents the molten waste plastic from adhering to the substrate by melting and mixing it with an anti-adhesion agent, thereby enabling granulation accompanied by dechlorination and semi-carbonization.

[0019] Furthermore, the method for producing solid fuel of the present invention allows for granulation regardless of whether water is added, and can produce solid fuel of equivalent or superior quality to that produced using a conventional twin-screw dechlorination device with external heating.

[0020] Furthermore, the present invention's method for producing solid fuel involves dechlorinating, desulfurizing, and semi-carbonizing waste plastics by direct heating through powerful local shearing by the agitator blades of a high-speed rotary mixer. This reduces CO2 emissions due to low power consumption, enabling efficient production of solid fuel with low initial and running costs. In other words, compared to conventional production methods using twin-screw dechlorination equipment with external heating, the present invention's method for producing solid fuel has lower initial and running costs (power consumption) per unit of processing capacity, and also reduces power consumption and CO2 emissions, thus enabling efficient production of solid fuel at low cost.

[0021] Patent Document 1 and Non-Patent Document 1 do not describe the processing capacity of the screw-type dechlorination technology, but Non-Patent Document 1 states that "the residual chlorine concentration hardly changes when the residence time is 10 minutes or more." Lowering the screw rotation speed increases the residence time and improves the dechlorination performance, but it also decreases the processing capacity, reduces direct heating by screw shearing, and becomes more like the external indirect heating method for dechlorination, thus lowering the efficiency of direct heating.

[0022] In contrast, the present invention, compared to the dechlorination technology of Patent Document 1, performs granulation treatment at a lower resin temperature with an equivalent dechlorination rate, as demonstrated in Example 3. At the same resin temperature, the power consumption of the direct heating portion of the present invention, which does not use external indirect heating, is lower. As the resin temperature rises, the melt viscosity increases and the power consumption of both driving components increases, so the power consumption of the driving component is lower in the present invention, which uses a lower resin temperature than Patent Document 1.

[0023] Furthermore, when comparing the power consumption for external indirect heating and screw driving in Patent Document 1 with the power consumption for direct heating and driving of only the stirring blades in the present invention, the latter has lower power consumption for heating and driving. 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 having equivalent processing capacity.

[0024] [Waste plastic] The waste plastic to be processed in this invention is not particularly limited as long as it can be processed by a high-speed rotary mixer, and examples include recycled container and packaging plastics. The waste plastic may be in its discarded state or processed after disposal, but processed waste plastic is preferred. Of the processed waste plastic, crushed waste plastic is more preferred. Examples of waste plastic shapes include fluff, beads, flakes, chips, powders, pellets, and various other shapes.

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

[0026] [Anti-adhesion agent] Examples of anti-adhesion materials of the present invention include biomass powders and granules, solid fuels, and oils with a flash point higher than the maximum temperature (also called the resin temperature) of the waste plastic and anti-adhesion material during granulation. These may be mixed with the waste plastic individually or in combination. By adding these anti-adhesion materials, the adhesion of molten waste plastic is prevented, and granulation accompanied by dechlorination and semi-carbonization becomes possible.

[0027] (Biomass powder and granules) The biomass powders and granules of the present invention are not particularly limited as long as they are volatile biomass that generate gases such as carbon monoxide and hydrogen when heated, or combustible biomass. For example, they can be organic sludge powders and granules generated from wastewater treatment facilities containing a large amount of organic matter, such as food processing plants, sewage treatment plants, paper mills, and animal farms. Furthermore, the biomass powders and granules of the present invention can also be applied to biomass that is unsuitable as fuel and difficult to treat due to its high chlorine and sulfur content, such as tree bark, bamboo, organic sludge, and livestock manure.

[0028] For example, by using a high-speed rotary mixer to dechlorinate, desulfurize, and semi-carbonize the waste plastic containing polyvinyl chloride (PVC) that settles during the wet gravity separation process, the waste plastic discharged from a material recycling plant that wet-separates the aforementioned waste plastics can be effectively utilized as a solid fuel substitute for fossil fuels. This makes it possible to realize a zero-emission material recycling plant that contributes to low CO2 emissions by eliminating the need for industrial waste treatment of waste plastics containing polyvinyl chloride (PVC) and waste plastics containing polyvinyl chloride (PVC) and waste plastics.

[0029] The biomass powder and granules of the present invention play a role in suppressing the molten adhesion of waste plastics and improving the efficiency of dechlorination and desulfurization processing. Specifically, when the resin temperature rises and the waste plastic melts, the molten plastic that adheres to the inside of the mixer due to its molten adhesive force cannot be heated by local shear adiabaticdipose adipose waste plastic. When the biomass powder and granules are mixed with the molten waste plastic and stirred, the molten adhesive force is reduced, and the stirred biomass powder and granules scrape off the molten adherent material, thereby suppressing molten adhesion and enabling granulation accompanied by dechlorination and semi-carbonization.

[0030] (solid fuel) As an anti-adhesion material of the present invention, solid fuel (granulated product) produced by the manufacturing method of the present invention can be used as a substitute for biomass powder or granules. Alternatively, the solid fuel according to the present invention and biomass powder or granules can be mixed and used. The solid fuel according to the present invention is semi-carbonized, so its melt-adhesion properties upon heating are reduced, and it is dechlorinated and desulfurized, making it useful as a substitute for biomass powder or granules. In other words, by adding solid fuel, it is possible to prevent the adhesion of molten waste plastics and to produce granules with dechlorination and semi-carbonization.

[0031] (oil) As an anti-adhesion material of the present invention, instead of biomass powder or solid fuel, an oil with 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. Furthermore, this high-flash-point oil can be used in mixture with biomass powder or solid fuel.

[0032] By adding oil with a flash point higher than the maximum temperature of the waste plastic and anti-adhesion material during granulation, such as waste soybean oil with a flash point of 330°C, adhesion and burning can be suppressed, similar to how oil is added to a frying pan to prevent sticking and burning. The addition of this oil forms an oil film inside the mixer, providing a lubricating effect and uniform heat conduction, thereby suppressing adhesion and burning, and enabling granulation accompanied by dechlorination, desulfurization, and semi-carbonization. Furthermore, mixing waste plastic with high-flash-point oil can improve the higher heating value of the granular fuel. Waste oil is preferred as the high-flash-point oil. Specifically, the flash point of the high-flash-point oil used is preferably higher than the maximum resin temperature at which dechlorination and desulfurization are performed. The maximum resin temperature should be a temperature that does not reduce yield. The maximum resin temperature is not limited as it varies depending on the components of the waste plastic added, but for example, for container and packaging waste plastic, 300°C or lower is preferred.

[0033] When granulating biomass powder and / or anti-adhesion material with dechlorination, desulfurization, and semi-carbonization, it is preferable to use a larger amount, as the adhesive strength increases as the resin temperature rises due to melting. Specifically, for example, when waste plastic and biomass powder and granules are added simultaneously to the volume of waste plastic put into the mixer, it is preferable that the volume after mixing remains the same as the initial volume, as the latter fills the gaps in the former after mixing. Similarly, when solid fuel or high flash point oil according to the present invention is added simultaneously with waste plastic, it is preferable that the volume after mixing remains the same as the initial volume.

[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, dry bulk density 0.1 t / m³ 3 For a given mass of waste plastic to be crushed using a Φ20mm screen, the dry bulk density of 0.8 t / m³ remains unchanged. 3 , average particle diameter D 50 The maximum amount of organic sludge that can be input is approximately 100% of the total volume (0.9 mm). By adjusting the amount of anti-adhesion agent added to an amount that does not increase the volume after stirring, the volume in the molten state, where the volume reduction is greatest, can be maintained at 60-70% or less of the mixer capacity. This ensures the amount of waste plastic to be input and the processing capacity, and allows for dechlorination within the time required to process the planned amount, thereby ensuring the planned amount of dechlorination and desulfurization.

[0035] If there is leeway in the planned waste plastic processing capacity, this does not apply to increasing the amount of anti-adhesion agent added. The amount of anti-adhesion agent added is preferably 1% by mass or more relative to the waste plastic, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, there is no particular upper limit, but it is preferably 1000% by mass or less relative to 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 using biomass powders or solid fuels as anti-adhesion materials, there are no particular limitations on the size (particle size) and moisture content of the anti-adhesion material to be put into the mixer. The material is crushed, reduced in volume, mixed, dried, kneaded, melted, dechlorinated, desulfurized, and semi-carbonized by the powerful shearing action of the high-speed rotating blades in the mixer. Therefore, it is preferable for the raw material to have a small particle size and low moisture content. In other words, the smaller the particle size and the lower the moisture content of the anti-adhesion material, the shorter the crushing, volume reduction, and drying times will be, allowing for a longer time to dechlorinate within the processing time for the planned amount, thus enabling the achievement of the planned amount of dechlorination and desulfurization.

[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% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0038] The present invention's method for producing solid fuel involves using the powerful local shear heat of a stirring blade to melt waste plastic, which is then mixed with the biomass powder and granules. While mixing, the surface of the biomass powder and granules are coated, and the fine powder particles are bound together by the molten adhesive force. Dechlorination, desulfurization, and semi-carbonization of the granules proceed, resulting in granular particle size. For example, wastewater treatment organic sludge with a particle size of 0.09 mm or less, accounting for 15% of the total mass, and wastewater treatment organic sludge with a particle size of 1.2 mm or more, accounting for 40% of the total mass, are used to produce a dry bulk density of 0.15 t / m³. 3 By mixing 10% by mass of this material with waste plastic to be crushed on a Φ20mm screen and granulating it in a mixer, it is possible to granulate it into a granular particle size as shown in the particle size cumulative distribution in Figure 3 (see Example 2).

[0039] [High-speed rotary mixer] The high-speed rotary mixer directly heats the waste plastic and anti-adhesion material introduced inside to over 180°C, as detected by a resin temperature sensor, through powerful shear heat generated by the high-speed rotation of its agitator blades, enabling granulation accompanied by dechlorination, desulfurization, semi-carbonization, and granulation. Herein, the resin temperature as used herein refers to the temperature of the mixture of waste plastic and anti-adhesion material (biomass powder or granules, solid fuel, or oil) introduced inside the high-speed rotary mixer.

[0040] The present invention's method for producing solid fuel involves melting plastic by direct heating through powerful local shear adiabatic action of a stirring blade, without requiring external or indirect heating, starting from a resin temperature equivalent to ambient temperature. Therefore, the temperature at the shear point is higher than the resin temperature detected by the resin temperature sensor, allowing for more energy-efficient and efficient dechlorination of chlorine compounds contained in waste plastics, compared to Patent Document 1, which uses external or indirect heating.

[0041] If the main components of waste plastics, such as PP (polypropylene), PE (polyethylene), PS (polystyrene), and PET (polyethylene terephthalate), can be kept from undergoing thermal decomposition, a decrease in the yield of these main components can be prevented. It is well known that PP, PE, PS, and PET undergo thermal decomposition at resin temperatures above 300°C, so if the resin temperature is kept below 300°C during granulation, a decrease in the yield of these main components can be prevented. The resin temperature at which thermal decomposition occurs varies depending on the components of the waste plastic, so there is no limit to the upper limit of the resin temperature, but it is preferable that the upper limit of the resin temperature be 500°C or less, more preferably 400°C or less, and even more preferably 300°C or less.

[0042] Furthermore, it is well known that polyvinyl chloride (PVC) decomposes at resin temperatures above 200°C, and the amount of volatile material released increases as the resin temperature rises. However, in a granulation test (Example 2) using the waste plastic and organic sludge powder of the present invention, it was confirmed that hydrogen chloride (HCl) began to be generated in the exhaust gas at a resin temperature of 160°C due to direct heating with strong local shear insulation, and that the hydrogen chloride concentration increased sharply at resin temperatures above 180°C, resulting in dechlorination. Therefore, when processing polyvinyl chloride (PVC), the temperature may be 250°C or lower, or even 200°C or lower.

[0043] In other words, while maintaining a high resin temperature to prevent yield reduction, a higher resin temperature is desirable because it increases the amount of volatilization due to thermal decomposition, increases the amount of chlorine removed, and promotes semi-carbonization. However, if the temperature is too high, the yield will decrease. For example, in the case of replasticized containers, it is preferable to dechlorinate and semi-carbonize the resin to a chlorine content of 1% or less within the resin temperature range of 180°C to 300°C, where the yield of these main components does not decrease. If the amount of chlorine removed is prioritized over yield reduction, it is not necessary to limit the upper limit of the resin temperature.

[0044] Examples of high-speed rotary mixers include high-speed fluidized mixers that mix by rapidly rotating agitating blades attached to the bottom of the container. Specific examples of high-speed fluidized mixers include Henschel mixers and microspeed mixers.

[0045] The outer peripheral speed of the impeller during dechlorination and semi-carbonization treatment should be sufficient to heat the resin to the above temperature range by shear heat generation of the impeller. This depends on the shape of the impeller, etc., so it cannot be stated definitively, but for example, with a Henschel mixer, the maximum speed is obtained and the maximum shear heat generation occurs at the outermost circumference of the high-speed rotating impeller. The maximum speed at the outermost circumference varies depending on the size of the mixer, but generally it is around 10 to 100 m / s, preferably 20 to 80 m / s, and more preferably 30 to 50 m / s, considering the durability of the bearings, etc.

[0046] As the mixer capacity decreases, the outer circumference of the agitator blade decreases, and therefore the rotational speed (rpm) of the agitator blade increases. The higher the outer circumference speed, the greater the shear heat insulation obtained. By agitating at such a speed, the waste plastic (and anti-adhesion material) in the vertical container can be directly heated by the strong local shear heat insulation generated when it is locally subjected to the powerful shear force of the high-speed rotating agitator blade.

[0047] High-speed fluidized mixers such as Henschel mixers can perform granulation involving dechlorination, desulfurization, semi-carbonization, and granulation more efficiently and with lower power consumption by direct heating through the powerful local shear of high-speed rotating impellers than by external indirect heating through the mixer walls using electric heaters or the like. The method for producing solid fuel of the present invention does not require external indirect heating, but it is possible to supplement direct heating with powerful local shear by external indirect heating to increase the granulation processing capacity for dechlorination, desulfurization, and semi-carbonization, as well as the amount of dechlorination and desulfurization.

[0048] If the amount of chlorine removed by granulation using direct heating by strong local shear adiabatic

[0049] The present invention's method for producing solid fuel involves strong localized direct heating through shear adiabatic aeration by a high-speed rotating agitator blade, resulting in a resin temperature exceeding 180°C. This melts the waste plastic and thermally decomposes chlorine-containing compounds such as polyvinyl chloride (PVC) contained in the waste plastic, allowing the chlorine components to volatilize and be removed (dechlorination). Furthermore, if the biomass powder or granules, such as organic sludge, contain sulfur-containing compounds, these 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 resin temperature rose from 180°C due to strong localized direct heating through shear adiabatic aeration by a high-speed rotating agitator blade, causing a rapid increase in hydrogen chloride (HCl) and sulfur oxide (SO2) concentrations in the exhaust gas, resulting in desulfurization. Moreover, the present invention's method for producing solid fuel can thermally decompose and volatilize organic biomass powder or granules to produce a substance with a high carbon content (partial carbonization).

[0050] The larger the amount of waste plastic (filling volume) introduced into the mixer, the higher the density of waste plastic near the area in contact with the agitator blades, allowing for shearing of a larger volume of waste plastic. Simultaneously, the high-density waste plastic flowing through the mixer increases resistance as it comes into contact with the inner wall of the mixer, increasing the local shear force. As a result, shear heat due to direct heating increases, the resin temperature rises more rapidly over time, and the processing capacity improves.

[0051] The mixer is a batch-type process that uses high-speed rotating impellers to crush, reduce volume, and mix, while simultaneously drying, kneading, and melting the material through strong local shear heat. This process allows for granulation through dechlorination, desulfurization, and semi-carbonization.

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

[0053] [Efficient dechlorination, desulfurization, and semi-carbonization of granular solid fuel production methods] A high-speed rotary mixer is a batch processing system that uses strong localized shearing in contact with the agitator blades to agitate, crush, reduce the volume of, and mix waste plastics, while simultaneously directly heating them to a degree of drying, kneading, and melting through strong localized shearing and heat, thereby performing dechlorination, desulfurization, and semi-carbonization. However, a continuous processing system may also be used. In the manufacturing 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 a single batch, in order to suppress the maximum power consumption and process efficiently.

[0054] High-speed rotary mixers can control the rotation speed by driving a motor via an inverter to rotate the agitator blades. In Embodiment 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 enhanced dechlorination and desulfurization performance. Furthermore, in Embodiment 3 of the present invention, by operating the motor as close as possible to its rated current value, high processing capacity and high dechlorination and desulfurization volume were achieved. It was also confirmed that even if the rotation speed of the agitator blades decreases, if the current value is close to the rated value, efficient processing capacity can be maintained, and semi-carbonized granule formation can be achieved through dechlorination and desulfurization treatment.

[0055] Furthermore, slowing down the rotation speed of the stirring blades reduces the shear force, which lowers the resin temperature and the motor current. Therefore, slowing down the rotation speed can reduce the motor current and prevent motor overload.

[0056] If the resin temperature is too low, increasing the rotation speed can raise both the resin temperature and the motor current. By adjusting the rotation speed, the resin temperature and motor current can be controlled, allowing the machine to operate as close as possible to its rated current. This enables the highest processing capacity and dechlorination / desulfurization treatment, resulting in highly efficient processing.

[0057] (Purge treatment with air or inert gas) When heating the agitator blades of a high-speed rotary mixer to over 180°C due to shear heating, it is preferable to perform a purging treatment with air or an inert gas. The purging treatment adjusts the exhaust temperature and simultaneously adjusts the concentration of HCl and other substances that volatilize and fill the mixer due to dechlorination and desulfurization. High concentrations of HCl and other substances in the mixer can lead to equipment corrosion problems, so it is preferable to use as high a purging rate as possible. The purging rate varies depending on the mixer capacity and the amount of dechlorination and desulfurization, so it cannot be limited in general, but it is preferable to have a ventilation rate of approximately 1x or more the mixer capacity per minute, for example, approximately 20 L / min or more of room temperature purging for a mixer capacity of 20 L. Instead of air, it is also possible to use an inert gas such as nitrogen as the gas used for the treatment, and using an inert gas is safer because it can prevent fires caused by high-temperature problems such as resin temperature.

[0058] Intensifying dechlorination and desulfurization generates large amounts of acidic gases such as HCl and SO2, causing corrosion of metal machinery inside the mixer and exhaust pipes, leading to malfunctions and other problems. Purge with air or inert gas can dilute the concentration of acidic gases and reduce the risk of corrosion problems, but it lowers the exhaust temperature as the gases volatilize inside the mixer. The temperature range for dechlorination and desulfurization exceeds the dew point of HCl and SO2 (approximately 120°C), which accelerates corrosion, thus suppressing corrosiveness in the dechlorination temperature range.

[0059] To reduce the risk of corrosion by purging with air or an inert gas, it is preferable to not only keep the concentration of acidic gas components as low as possible, 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 stirring blades, the resin temperature, the motor rating, etc., so it cannot be limited in general. For example, in Example 3, the minimum exhaust temperature during dechlorination was 160°C with a room temperature purge amount of 1.25 times the mixer capacity per minute, and the maximum exhaust temperature during dechlorination was 234°C with a purge amount of 2.75 times the mixer capacity per minute.

[0060] (Water treatment) It is preferable that the hydrophobic resin, heated to a high temperature by a high-speed rotary mixer through dechlorination, desulfurization, semi-carbonization, and granulation, is rapidly cooled by adding water while being stirred, causing the heated oil to splatter violently, and then granulated by solidifying while being crushed. In other words, it is preferable that granulation is carried out by melting the waste plastic with the shearing heat of the stirring blades, dechlorinating and semi-carbonizing it, and then adding water to solidify the waste plastic and form it into granules. This shortens the granulation time and enables efficient granulation compared to the case where granulation is carried out without adding water, as in Example 2 of the present invention.

[0061] Furthermore, as the water expands 1700 times in an instant, generating a steam injection, the thermally expanded metal mixer rapidly contracts, causing any deposits attached to the inner walls of the mixer to detach, much like how water can instantly remove burnt-on food from a frying pan. If the waste plastic and anti-adhesion material, which have undergone direct heating treatment using strong local shear insulation, contain water-soluble chlorine compounds or sulfur compounds, these can be dissolved in the treated water and discharged together with the treated water. After the water treatment, solid fuel is typically recovered after solid-liquid separation and drying to remove water-soluble chlorine and sulfur compounds.

[0062] The treated water used for hydration may contain a neutralizing agent that neutralizes dissolved chloride compounds such as hydrogen chloride and sodium chloride. Caustic soda can be specifically used as a neutralizing agent.

[0063] In terms of the amount of water added, a larger amount is preferable because it results in smaller granular particles, improving the cleaning performance of water-soluble inorganic chlorine and re-adhered HCl, as well as the detachment performance of molten adhesion. However, if too much water is added, the burden on subsequent processes such as washing, solid-liquid separation, drying, and wastewater treatment will increase. Therefore, it is preferable to add water in a mass equal to the mass that can be washed, separated, dried, and treated for wastewater treatment, plus the mass that will evaporate.

[0064] The amount of evaporation varies depending on the mixer capacity and the temperature of the resin to which water is added, so it cannot be definitively limited, but the amount of evaporation is roughly equivalent to the mass added (sum of the resin mass and the biomass powder mass) at a resin temperature of around 250°C. Furthermore, since water can be added in an emergency when the resin temperature becomes abnormally high, the water addition device is also suitable as a safety device for fire prevention, etc. Regarding the amount of water added, from the viewpoint of promoting the process and removing deposits in the mixer, 50% by mass or more is preferable, 100% by mass or more is more preferable, and 200% by mass or more is even more preferable. In addition, the upper limit is preferably 800% by mass or less.

[0065] [Low-cost and efficient dechlorination, desulfurization, and semi-carbonization equipment for producing granular solid fuels] When waste plastics and anti-adhesion materials that have undergone heat treatment using shear insulation contain small amounts of water-soluble chlorine compounds, sulfur compounds, and re-adhered HCl, the treatment can be carried out without affecting the chlorine content, sulfur content, particle size, or moisture content of the granulated product by reducing the amount of water added. This reduces the performance of washing, solid-liquid separation, and drying processes, or allows for the direct recovery of solid fuel by omitting these equipment. 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] In a high-speed rotary mixer with a water content that eliminates the need for wastewater treatment, this equipment directly heats the material through powerful local shear heat to perform dechlorination, desulfurization, and semi-carbonization granulation. When this equipment is implemented in the aforementioned zero-emission material recycling plant, it can replace the granulation equipment of the waste plastic dechlorination treatment device using a twin-screw low-speed rotary type with low shear force that uses external indirect heating through a cylinder, as described in Patent Document 1. However, the former (invention) granulation equipment has equivalent processing capacity, an initial cost approximately 20% lower, lower power consumption due to the lower resin temperature, lower running costs and lower CO2 emissions, and can produce solid fuel with equivalent dechlorination of 1% or less residual chlorine. Furthermore, the latter does not form a zero-emission plant because it processes wastewater organic sludge as industrial waste.

[0067] [Unexpected formation of semi-carbonized granules during dechlorination and desulfurization treatment using a high-speed rotary mixer (Example 2)] As described above, PP, PE, PS, and PET do not undergo thermal decomposition and volatilization unless the resin temperature is 300 °C or higher. However, polyvinyl chloride (PVC) begins to decompose thermally, volatilize, and start carbonizing when the resin temperature is 200 °C or higher. 87.3 mass% of waste plastics for container packaging (81.1% mixture of PP, PE, PS, and PET, 3.8 mass% ash, 2.4% PVC), 8.0 mass% of organic sludge (4.0 mass% ash), and 4.7% of soybean oil (flash point lower than the ignition point, 330 °C) were put into a mixer. Due to the strong local shear heat of the stirring blades rotating at high speed, dechlorination and desulfurization proceeded even when the resin temperature was 258 °C or lower, and the melt adhesion force was lost. As a result, the current value of the drive motor of the stirring blades decreased, and the resin temperature dropped to a range where dechlorination did not occur, so granulation was carried out without adding water. As a result, granular black granulated products as shown in Fig. 3 were obtained.

[0068] When the volatile amount of the obtained granulated product was analyzed based on industrial analysis (JISM8812), it became clear that 28.5% of the dry input mass of the mixer had volatilized and semi-carbonized granulation had occurred.

[0069] As described above, among the input materials, the amount that volatilizes at a resin temperature of 258 °C or lower should be about 6.4 mass% in total of polyvinyl chloride (PVC) and organic sludge other than ash, which is small, but an unexpected semi-carbonized granulation with a volatilization about four times stronger occurred. Also, in this granulation test, water was added in a semi-melted state at the resin temperature before the resin melted in the same mixer, and glassy granulation with an average particle diameter D 50 of about 1 - 2 cm was expected, but actually, granulation with a granular particle size without adding water as shown in Fig. 3 was achieved. As shown by the results of Example 2 of the present invention, unexpected semi-carbonized granular granulation accompanying the dechlorination and desulfurization treatment by a high-speed rotary mixer was confirmed.

[0070] [Dechlorination, Desulfurization, Semi-carbonization, Granular Solid Fuel] According to the method for producing a solid fuel of the present invention, the chlorine content is 1.0% or less, the bulk density is 0.4 t / m 3 or more, and the average particle diameter D 50It is possible to produce solid fuel with a particle size of 10.0 mm or less, with 90% or more of the whole grains having a particle size of 0.01 mm or larger, and an angle of repose of 50° or less. Furthermore, according to the method for producing solid fuel of the present invention, it is possible to produce solid fuel with a chlorine content of 1.0% by mass or less, conforming to RPF quality standards, having 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. Moreover, according to the method for producing solid fuel of the present invention, it is possible to produce solid fuel with a sulfur content of 1% or less.

[0071] The granular solid fuel of the present invention will be described below. The granular solid fuel of the present invention is a granular solid fuel containing plastic, having a chlorine content of 1.0% by mass or less, and a bulk density of 0.4 t / m³. 3 Above, average particle diameter D 50 It is characterized by having a particle size of 10.0 mm or less, with more than 90% of the whole grains having a particle size of 0.01 mm or larger, 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% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.6% by mass or less. In this invention, the chlorine content of the solid fuel can be reduced by raising the resin temperature efficiently and at low cost. The bulk density is 0.4 t / m³. 3 That is all, 0.5t / m 3 The above is preferable, and 0.6 t / m 3 The above is more preferable, 0.7 t / m 3 The above is even more preferable. Having a bulk density within this range allows for reduced transportation and handling costs. Also, the average particle size D 50 teeth 、 The average particle size 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 flammability and coal co-firing compatibility. Furthermore, the particle size should be such that 90% or more of the whole grains 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. This particle size range suppresses scattering and dust explosions. The angle of repose should be 50° or less, more preferably 40° or less. This angle of repose makes it less likely for the flow path of the equipment to become blocked and facilitates transport. Regarding sulfur content, while there are no established standards for the sulfur content of solid fuels such as RPF, a test method for the sulfur content of solid waste fuel is established in JIS Z 7302-7. Therefore, this measurement method allows for management to comply with the sulfur content regulations of the shipping destination. For example, Fukuoka City has measures regarding the use of petroleum-based fuels with a sulfur content 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 embodiment of the present invention has a particle size of approximately 0.1 mm or larger, resulting in virtually no scattering of fine powder, excellent handling properties, and a reduced risk of dust explosion. Furthermore, its angle of repose is similar to that of commercially available RPF pellets (particle size 6-40 mm x length approximately 2-3 times the diameter, approximately 30-40°, bulk density 0.3-0.5 t / m³). 3 Despite being equivalent to [another material], its smaller particle size makes it less likely for particles to cross-link at tank outlets, etc., facilitating transport by equipment. Furthermore, its bulk density is 0.9 t / m³. 3 Therefore, the bulk density of commercially available RPF pellets is 0.3~0.5 t / m³ 3 It is larger than conventional materials, reducing transportation and handling costs. Furthermore, as a fuel, its particle size is smaller than commercially available RPF pellets, making it easier to inject into combustion furnaces and allowing for rapid combustion. It is also easy to co-fire with coal, and the semi-carbonization of the biomass granules increases its energy density per unit weight, approaching that of coal, and improves its water resistance. This makes it easier to crush and facilitates co-firing with pulverized coal. As a result, handling during storage, transportation, and combustion is improved, the coal co-firing ratio increases, and it contributes to lower CO2 emissions and reduced costs. Having the above characteristics, the method for producing solid fuel of the present invention can produce granular solid fuel that is of equal or superior quality and functionality to commercially available RPF solid fuel, and can be used as an alternative fuel to heavy oil, coal, etc.

[0074] [Compatible with the quality of solid fuels such as RPF] The present invention's method for producing solid fuel can manufacture granular solid fuel of the quality specified in the RPF quality standards. Specifically, by blending waste plastic, biomass powder and granules, and oil that conform to the RPF quality standards specified in JIS Z 7311:2010 "Solid Fuel (RPF) from Waste-Derived Paper, Plastics, etc.", it is possible to manufacture solid fuel that conforms to the specified RPF quality, with 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. When blending to conform to RPF quality, it is preferable to use raw materials with as little ash content as possible, as this affects the higher heating value. The lower the ash content, the higher the higher heating value, and the longer the lifespan of the mixer's agitator blades, etc., due to wear. It should be noted that wear can be increased by hardening the agitator blades and the inside of the mixer chamber, which come into contact with the waste plastic and biomass powder and granules, thereby increasing their hardness.

[0075] In the example, readily available compost-fermented organic sludge (ash content 50.4% by mass, higher heating value 11.2 MJ / kg) was used as the biomass powder. However, if, for example, organic sludge from food processing plant wastewater (ash content 14.6% by mass, 17.0 MJ / kg) is used, the amount of sludge conforming to RPF quality can be doubled. Furthermore, if woody biomass powder, which has a lower ash content and a higher higher heating value, is used, the amount of biomass powder conforming to RPF quality can be increased compared to organic sludge. This does not apply if the quality of the solid fuel required by the recipient does not require conformity to RPF quality. [Examples]

[0076] Figure 1 shows an overview of the method for producing solid fuel according to an embodiment of the present invention. Solid fuel was manufactured using the high-speed fluidized mixer shown in Figure 2. The container 2 of the high-speed fluidized mixer (high-speed rotary mixer) 1 is equipped with a raw material inlet 3, an exhaust port 4, a water injection nozzle 5 for spraying treated water, and an air purge nozzle 6 for spraying air / inert gas during chlorine removal. The bottom of the container 2 is equipped with upper and lower stirring blades 7 and a discharge valve 8. A resin temperature sensor 9 is also installed inside the container 2 to detect the resin temperature. Furthermore, the temperature of the exhaust gas is detected by an exhaust temperature sensor 10 installed at the exhaust port. The black arrows in the figure indicate the movement of the processed material inside the device.

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

[0078] [Table 1]

[0079] Specifically, the tests were conducted and evaluated as follows. As raw material, we used sediment from plastic packaging (mainly a mixture of PP, PE, PS, and PET, 92.8% by mass, with an ash content of 4.4% by mass DB and PVC of 2.8% by mass (calculated value based on a chlorine content of 1.57% by mass DB)). As the raw material, we used organic sludge from wastewater treatment (ash content 50.4% by mass DB, chlorine content 1.13% by mass DB, sulfur content 0.61% by mass DB). 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] The sediment and organic sludge from the containerized plastic were fed into a high-speed fluidized bed mixer. The mixture was crushed, reduced in volume, and mixed while being fluidized and stirred by high-speed rotating impellers with a maximum tip speed of 56 m / s. Simultaneously, it was directly heated to a degree of drying, kneading, and melting using only strong local shear heat, resulting in dechlorination, desulfurization, and semi-carbonization before granulation. During mixer operation, the generated water vapor, chlorine-based gases, and sulfur-based gases were treated as safe exhaust gases by exhaust gas cleaning equipment such as a wet scrubber, which removed chlorine and sulfur. Air purging was performed during the dechlorination process. The motor was driven via an inverter to adjust the rotation speed.

[0081] [Evaluation of Example 2: Unexpected formation of semi-carbonized granules during dechlorination and desulfurization treatment using a high-speed rotary mixer] 2 kg wet of polyvinyl chloride (PVC) resin, 0.2 kg wet of chlorine and sulfur-containing organic sludge, and 0.1 kg of soybean oil were placed in a mixer. Direct heating was performed using only the shear insulation of the mixing blades. The resin melted, and once the resin temperature exceeded approximately 160°C, the chlorine contained in the resin and the sulfur contained in the organic sludge underwent thermal decomposition, generating hydrogen chloride (HCl) and sulfur dioxide (SO2), which were then exhausted. At resin temperatures above 180°C, the concentrations of hydrogen chloride and sulfur dioxide increased rapidly, resulting in dechlorination and desulfurization. The higher the temperature of the molten resin, the higher the concentrations of hydrogen chloride and sulfur dioxide. Dechlorination and desulfurization occurred at a maximum resin temperature of 258°C, leading to further carbonization of the resin and a decrease in shear strength. Without the addition of water, the resin temperature decreased, resulting in a semi-carbonized black granular product (dry bulk density 0.92 t / m³). 3 A dry angle of repose (35°) was generated.

[0082] During dechlorination, an air purge of 60 L / min reduced the hydrogen chloride and sulfur dioxide concentrations in the mixer chamber and exhaust, and the exhaust temperature remained above 150°C to suppress dew point corrosion. The curves for motor current, resin temperature, and exhaust concentration (hydrochloric acid, sulfur dioxide) each showed correlated increase and decrease characteristics.

[0083] As shown in Figure 3, the cumulative particle size distribution after sieving of granular solid fuel granulated without water addition shows that the particle size is larger than that of the powder, with a particle size of approximately 0.1 mm to 1.2 mm (approximately 90% by mass after sieving) and an average particle diameter of 0.57 mm-D.50 Granulation was performed on the material.

[0084] Although there are no established methods or standards for calculating the degree of partial carbonization, partial carbonization was achieved with an index degree of partial carbonization (amount of dry material volatilized due to treatment ÷ amount of dry material volatilized before treatment) of 32.0 mass%. At resin temperatures below 258°C, only about 6.4 mass% of the dry input amount (organic sludge other than PVC and ash) should volatilize, but 28.5 mass% of the dry input amount volatilized. The amounts of volatilized material before and after treatment were analyzed in accordance with JIS M 8812, an industrial analysis useful for the waste solidification fuel test method (JIS Z 7302).

[0085] [Evaluation of Example 3: Compared to Patent Document 1 and Non-Patent Document 1, this method achieves a similar dechlorination rate at a lower resin temperature and exhibits comparable granular product properties.] Three kilograms of polyvinyl chloride (PVC) resin (added in two batches of 2 kg + 1 kg) and 1.2 kg of chlorine and sulfur-containing organic sludge were added to a mixer. Dechlorination, desulfurization, semi-carbonization, and granulation were performed by direct heating using only the shear insulation of the mixing blades. A generous amount of water (6 liters) was added during mixing (for cooling and solidification, melt adhesion removal, and chlorine and sulfur washing), resulting in a semi-carbonized black granular product (dry bulk density 0.88 t / m³). 3 A dry solution (with an angle of repose of 35°) was generated, and dechlorination and desulfurization were performed at a maximum resin temperature of 280°C, reducing the chlorine content from 1.45% DB to 0.68% DB (indicated dechlorination rate of 53%) and the sulfur content from 0.16% DB to 0.068% DB (indicated desulfurization rate of 56%). There was almost no adhesion inside the mixer chamber or on the impeller.

[0086] Indicator dechlorination / desulfurization rate = (Amount of chlorine and sulfur input - Amount of chlorine and sulfur in solid fuel) ÷ Amount of chlorine and sulfur input

[0087] During the dechlorination process, air purging controlled the hydrogen chloride and sulfur dioxide concentrations in the mixer chamber and exhaust, as well as the exhaust temperature. The exhaust temperature remained above 150°C during dechlorination to suppress dew point corrosion. By adjusting the agitator motor frequency, the correlated resin temperature and motor current values ​​could be controlled, preventing motor overload shutdowns. Dechlorination, desulfurization, and semi-carbonization were performed, followed by hydration and granulation.

[0088] After washing the granulated material with a large amount of water and stirring, the mixture of water and granules was discharged. Solid-liquid separation was then performed to wash away chlorine and other substances contained in the granules. When the water quality of the separated liquid was measured, it showed acidity similar to HCl. The liquid after water washing and solid-liquid separation had a pH of 5.0 (acidic) and a total chlorine concentration of 4.8 mg / L.

[0089] As shown in Figure 3, the cumulative particle size distribution of the granular product after sieving shows that the particle size is larger than that of the powder, with a particle size of approximately 0.1 mm to 1.2 mm (approximately 85% of the mass after sieving) and an average particle diameter of 0.56 mm-D. 50 Granulated granules were produced.

[0090] [Comparative evaluation of Example 1 and Example 2: Higher input amount results in higher sheath insulation] Using the same input materials, mixing ratios, and stirring blade rotation speed, the processing time from the start of operation to the maximum resin temperature (direct heating treatment using only shear insulation from the stirring blades) was 1 hour and 54 minutes for Example 1 and 45 minutes for Example 2. Since Example 2, which used 1.33 times more material than in Test 22, shortened the processing time by 69 minutes (61%) compared to Example 1, it is clear that a larger input amount results in higher shear insulation.

[0091] [Comparative evaluation of Example 2 with Examples 4 and 5: Effect of preventing melt-adhesion by adding water and increasing the amount of organic sludge] The state of molten adhesion inside the mixer and on the agitator blades after granulation in Examples 2 and 4 demonstrated that increasing the amount of organic sludge contributes to preventing molten adhesion. Furthermore, the state of molten adhesion inside the mixer and on the agitator blades after granulation in Examples 2 and 5 demonstrated the effect of adding water on removing the attached material. [Industrial applicability]

[0092] The solid fuel produced by the method of the present invention can be used as a substitute for heavy oil or coal, and is therefore industrially useful, as it complies not only with the Container and Packaging Recycling Law and the Plastic Resource Recycling 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 ports 5. Water nozzle 6. Air purge nozzle 7 Stirring blade 8. Discharge valve 9. Resin temperature sensor 10. Exhaust temperature sensor

Claims

1. A method for producing solid fuel, in which waste plastic and an anti-adhesion material are stirred in a high-speed rotary mixer and heated to over 180°C by the shearing heat of the stirring blades, thereby performing granulation accompanied by 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 and granules, the solid fuel, and the waste plastic used during granulation and oil, which has a flash point higher than the highest temperature of the anti-adhesion material.

2. A method for producing a solid fuel according to claim 1, characterized in that the solid fuel produced has a chlorine content of 1.0% by mass or less.

3. The method for producing solid fuel according to claim 1, characterized in that the anti-adhesion material includes at least biomass powder and granules, and the biomass powder and granules are organic sludge powder and granules generated from a wastewater treatment facility.

4. The method for producing solid fuel according to claim 2, characterized in that the anti-adhesion material includes at least biomass powder and granules, and the biomass powder and granules are organic sludge powder and granules generated from a wastewater treatment facility.

5. A method for producing solid fuel according to any one of claims 1 to 4, characterized in that the granulation is performed by melting the waste plastic by the shearing heat of the stirring blade, dechlorinating and semi-carbonizing it, and then adding water to solidify the waste plastic and form it into granules.

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

7. The method for producing solid fuel according to claim 5, characterized in that when heating to over 180°C by shear heating of the stirring blades of the high-speed rotary mixer, a purging treatment with air or an inert gas is performed.

8. The method for producing solid fuel according to claim 5, characterized in that the water used for adding water contains a neutralizing agent that neutralizes chloride compounds.

9. A method for producing solid fuel according to any one of claims 1 to 4, characterized in that the solid fuel produced has a chlorine content of 1.0% by mass or less, conforms to 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.

10. The solid fuel produced has a chlorine content of 1.0% by mass or less and a bulk density of 0.4 t / m³. ３ Above, average particle diameter D ５０ A method for producing solid fuel according to any one of claims 1 to 4, characterized in that the particles are 10.0 mm or smaller, 90% or more of the whole particles have a particle size of 0.01 mm or larger, and the angle of repose is 50° or less.

11. A method for producing a solid fuel according to any one of claims 1 to 4, characterized in that the solid fuel produced has a sulfur content of 1% by mass or less.

12. A granular solid fuel containing plastic, characterized by having a chlorine content of 1.0% by mass or less, conforming to RPF quality standards, having 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.

13. A granular solid fuel containing plastic, with a chlorine content of 1.0% by mass or less and a bulk density of 0.4 t / m³. ３ Above, average particle diameter D ５０ A granular solid fuel characterized by having a particle size of 10.0 mm or less, with 90% or more of the whole grains having a particle size of 0.01 mm or larger, and an angle of repose of 50° or less.

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