JPH11209767A - Utilization of spent plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for reutilizing useless fly ashes and bottom ashes discharged from a coal-fired power plant or boiler, and/or slag discharged from a coal gasification furnace as a medium for milling spent plastics, and easily milling spent plastic packing containers (e.g. PET bottles) discharged from the residential sector and/or spent plastics with no value discharged from a plant by finely and slurrying them, in order to produce a stock for gasification or fuel for, e.g. boilers firing pulverized coal. SOLUTION: This method preliminary mixes spent plastics with at least one of slag discharged from a coal gasification furnace, fly ashes or bottom ashes discharged from a coal-fired boiler, an inorganic mineral (e.g. clay) and pulverized coal or the like; melts and further mixes the mixture obtained by the above preliminary step; cools the molten mixture, and mils it into a slurry or powder, in order to produce a stock or fuel for gasification furnaces, boilers or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gasification furnace or a boiler utilizing slags, fly ash or bottom ash, inorganic minerals such as clay, etc. to facilitate the pulverization or pulverization of waste plastics. The present invention relates to a method of using waste plastic that can be converted to raw fuel such as.

[0002]

2. Description of the Related Art Recently, there has been a growing social demand for the reuse of waste plastics discharged from general households and businesses due to a lack of capacity of general waste landfill sites and environmental problems. For this reason, many proposals have been made to recycle waste plastics by reprocessing for effective use and to use them as raw fuels.

[0003] As one method for effectively utilizing these waste plastics, the waste plastics are pulverized using various cutters or pulverizers, or are converted into liquids by utilizing a chemical reaction using a catalyst or the like. Attempts have been made to convert the fuel into a fuel.

[0004]

However, as described above, when waste plastics are crushed using various cutting machines or crushers, or when a catalyst or the like is used, the thermoplasticity of the waste plastics is reduced. And extensibility,
In order to pulverize sufficiently to a desired particle size, an excessive investment in equipment is required. If a waste plastic is to be slurried, a special dispersant must be used, which is costly and economically unviable. There was such a problem.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide fly ash, bottom ash, and slag discharged from a coal gasifier which are unnecessary in a coal-fired power plant or a coal boiler. As a crushing medium for waste plastics, and easily pulverize and slurry plastic packaging containers such as plastic bottles discarded from ordinary households and waste plastics that are not added to the commercial value and discharged from companies. Accordingly, the present invention is to provide a raw material for gasification or a fuel for pulverized coal boilers.

[0006]

According to a first aspect of the present invention, waste plastics, slag discharged from a coal gasifier, and fly ash discharged from a coal boiler are provided. Or bottom ash, inorganic minerals such as clay, and premixed with at least one of pulverized coal such as coal, the mixture obtained by further melting and mixing the mixture obtained by the premixing is cooled, and then pulverized. The slurry or powder is used as a raw fuel for a gasifier or a boiler. Also, the first
In the second invention mainly based on the invention of the above, the mixing ratio of at least one of slag, fly ash or bottom ash, inorganic minerals such as clay, and pulverized coal such as coal is increased by 75% by weight to 97% by weight of waste plastics. % Or less, slag, fly ash or bottom ash,
At least one of inorganic minerals such as clay and pulverized coal such as coal is contained in an amount of 3% by weight or more and 25% by weight or less.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for utilizing waste plastic according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block flow diagram according to the present invention, FIG. 2 is an explanatory diagram of the production of waste plastic slurry using waste plastic of the present invention, and FIG. 3 is production of raw fuel using dry waste plastic of the present invention. FIG. 4 is a cumulative frequency distribution curve showing the crushability when the ratio between PET bottle and slag is changed. FIG. 5 is the viscosity and the concentration of a mixture of PET and fine slag when the temperature of COM is 65 ° C. FIG.

The present invention will be described with reference to FIG. Desired is waste plastics () such as various thermoplastics and thermosetting plastics, and slags, inorganic minerals such as fly ash, bottom ash and clay discharged from coal boilers, and grinding media () such as pulverized coal such as coal. And mixing at a constant rate to obtain a waste plastic mixture.

The waste plastic mixture is melt-kneaded () using, for example, an injection molding machine. The melt-kneaded waste plastic mixture is continuously discharged out of the injection molding machine. The discharged molten waste plastic mixture is cooled () to a desired temperature in a cooler to obtain a waste plastic mixture of a certain size.

Thereafter, in the case of producing a waste plastic slurry, the waste plastic mixture is put into, for example, a wet pulverizer together with a dispersant () and a slurry fluidizing medium (), and wet pulverization is performed. In this way, a waste plastic slurry having a certain concentration is obtained and supplied to a gasifier, a boiler or the like as a raw fuel for the slurry combustion (). In addition, water, oil, orimulsion, etc. can be used as the fluid medium for slurry.

On the other hand, when producing a raw fuel using dry waste plastics, a waste plastic mixture of a certain size obtained by cooling () to a desired temperature with a cooler is desirably used by a dry pulverizer. Pulverized to a particle size of (), and the pulverized waste plastic mixture is compressed as inert gas, or powdered as raw fuel into a gasifier or boiler by pneumatic transportation ((10)) To be served.

[0013]

FIG. 2 shows a specific embodiment. FIG. 2 is a diagram illustrating the production of waste plastic slurry using water as a fluid medium for slurry. For example, waste plastic 2 such as a PET bottle (hereinafter referred to as PET) and grinding media 4 such as slag are determined in advance. The mixture can be put into the hopper 8 of the injection molding machine 6 at the mixed ratio.

In this case, it is desirable that the waste plastic 2 put into the hopper 8 is crushed in advance to a size that can pass through the throat portion 8a at the lower part of the hopper 8. As shown in FIG. 2, the injection molding machine 6 is provided with a heater (not shown) on the outer periphery of a barrel 10 having a cylindrical shape.

A kneading screw 12 that can rotate and move back and forth is helically wound around the screw shaft inside the barrel 10, and the waste plastic 2 is stopped at a shielding plate 14, near the lower end of the tip of the barrel 10. Is provided with an outlet 16 for the waste plastic 2 that has been melted and kneaded.

The outlet of the discharge port 16 has a cooling conveyor 1
8 are provided. The thin belt 22 constituting the cooling conveyer 18 is stretched endlessly between two spaced rollers 20 and is adapted to rotate in the direction shown in FIG.

A square or rectangular lattice-shaped frame is disposed on the belt 22. The melt-kneaded waste plastic 2 flowing out from the discharge port 16 is blocked by the lattice-shaped frame. The melted and mixed waste plastic 2 placed on the belt 22 along with the rotation of the belt 22 is cooled by the cooling means during the movement, and is cooled and solidified from the start end side of the belt 22 located near the lower portion of the discharge port 16. The waste plastic pieces in the form of squares or rectangles are discharged from the terminal side.

Reference numeral 24 denotes a wet pulverizer, and the belt 22
The waste plastic pieces discharged from are supplied together with an appropriate amount of a dispersant 26 and water 28. This dispersant 26 is used to suppress an increase in viscosity due to an increase in concentration. As the dispersant 26, a substance known per se can be used, and examples thereof include naphthalene sulfonate, petroleum sulfonate, lignin sulfonate, and formalin condensate thereof, and polyoxyethylene alkyl ether sulfate. And polyoxyethylene alkylaryl ether sulfates, sulfates of polyglycerin, sulfonates of melamine resins, sulfonates of coal extracts and the like.

The dispersant is used in an amount of 0.1 parts by weight based on 100 parts by weight of the waste plastic mixture / water slurry used as the solid fuel.
01 to 3 parts by weight is suitable. Examples of the wet pulverizer 24 include a well-known wet pulverizer such as a ball mill, a tube mill, an attrition mill, and a hammer mill.
Can be mentioned.

The content of the solid fuel in the solid fuel / water slurry obtained by the present invention is usually at least 50% by weight, preferably at least 60% by weight. In this case, the concentration of the solid fuel is 30 to 80% by weight, preferably 50 to 70% by weight.
Is appropriate.

In the present invention, if the mixing ratio of the waste plastic 2 and the crushing medium 4 is not more than 75% by weight, the remaining slag, fly ash, bottom ash, clay, etc. Since the amount of the pulverizing medium 4 which is pulverized coal such as minerals and coal increases, it cannot be sufficiently mixed with the molten waste plastic 2.

Conversely, the ratio of waste plastics 2 is 97
When the content is more than 3% by weight, the amount of the grinding medium 4 becomes 3% by weight or less,
The pulverizability of the waste plastic 2 is reduced, and a desired particle size suitable for combustion may not be obtained. Attempts to solve such problems will cause new problems such as the necessity of special crushers and large-scale equipment. In consideration of such points, the waste plastic 2 and the crushing medium 4
The mixing ratio with waste plastics is 75% by weight or more and 97% by weight.
% By weight, and the amount of the pulverizing medium 4 was 3% by weight or more and 25% by weight or less. Examples of the pulverizing medium 4 include slags, fly ash or bottom ash, inorganic minerals such as clay,
Pulverized coal such as coal is conceivable, but not limited thereto.

As shown in FIG. 4, the solid fuel particles in the solid fuel / water slurry have a geometric mean diameter of about 150 μm.
m, preferably 100-200 μm. In the case of the present invention, in the mixing ratio of the waste plastic 2 and the pulverizing medium 4, for example, fine slag (meaning slag having a large geometric mean diameter of 1.68 mm or less containing a large amount of unburned coal discharged from a coal gasifier). 1 part by weight of the crushing medium 4 and 4 parts by weight (80% by weight), 5 parts by weight (83.3% by weight), 10 parts by weight (90.9% by weight) of waste plastic as PET. , 20 parts by weight (95.2% by weight) and 30 parts by weight (96.8% by weight) were mixed under the same conditions, and the test results of the grindability were compared. On the other hand, as the ratio of the waste plastic 2 increases, the pulverizability tends to decrease and the particle size tends to increase (see Table 1).

[0024]

[Table 1]

It is considered that the reason for this is that when the ratio of the waste plastic 2 is high, the waste plastic 2 has elastic properties, so that it is difficult to grind and the grindability decreases. Further, in Table 2, when the slurry concentration is fixed at 67% by concentration, the difference in the amount of the dispersant 26 used and the good / bad of the fluidity of the slurry depending on the mixing ratio of the waste plastic 2 and the grinding medium 4 are shown. Have been.

[0026]

[Table 2]

As shown in Table 2, the same slurry concentration (6
(7% by weight), when the amount of the dispersant 26 used is small, the fluidity of the slurry tends to be poor. Further, the same slurry concentration (67% by weight) and the same dispersant 26 (0.
(2% by weight), the fluidity of the slurry tends to deteriorate as the mixing ratio of the waste plastic 2 increases with respect to the grinding medium 4.

From the above, when considering the processing amount of PET, the pulverizability of PET, the slurry concentration, the amount of dispersant used, the fluidity of the slurry, and the like, the fine slag, which is the pulverizing medium 4, is taken into consideration. It is most desirable to mix PET, which is waste plastic 2, with 10 parts by weight with respect to 1 part by weight.

The waste plastic mixture / water slurry of 67% by weight thus produced is temporarily stored in the storage tank 30. Then, the stored waste plastic mixture / water slurry is appropriately fed to a burner 34 by a feed pump 32 to be subjected to combustion.

Next, the production of raw fuel using dry waste plastic will be described with reference to FIG. As in the production of the waste plastic slurry shown in FIG. 2, the waste plastic 2 such as PET and the crushing medium 4 such as slag can be put into the hopper 8 of the injection molding machine 6 at a predetermined mixing ratio. ing.

In this case, it is desirable that the waste plastic 2 put into the hopper 8 is crushed in advance to a size that can pass through the throat portion 8a at the lower part of the hopper 8. As shown in FIG. 2, the injection molding machine 6 is provided with a heater (not shown) on the outer periphery of a barrel 10 having a cylindrical shape.

A kneading screw 12 that is rotatable and movable back and forth is spirally wound around the screw shaft inside the barrel 10, and the melt-kneaded waste plastic 2 is discharged near the lower end of the barrel 10. An outlet 16 is provided.

The outlet of the discharge port 16 has a cooling conveyor 1
8 are provided. The thin belt 22 constituting the cooling conveyor 18 is stretched endlessly between two spaced rollers 20 and is configured to rotate in the direction shown in FIG.

A square or rectangular lattice frame is disposed on the belt 22, and the melt-kneaded waste plastic 2 flowing out from the discharge port 16 is blocked by the lattice frame. The melted and mixed waste plastic 2 placed on the belt 22 along with the rotation of the belt 22 is cooled by the cooling means during the movement, and is cooled and solidified from the start end side of the belt 22 located near the lower portion of the discharge port 16. The waste plastic pieces in the form of squares or rectangles are discharged from the terminal side.

Reference numeral 36 denotes a dry pulverizer, and the belt 22
The waste plastic pieces discharged from are supplied to the dry pulverizer 6. Examples of the dry pulverizer 36 include a ball mill, a tube mill, an attrition mill,
A known dry pulverizer 36 such as a hammer mill can be used.

The waste plastic mixture is pulverized in a dry pulverizer 36 over a predetermined period of time to a geometric mean diameter of about 150 μm, preferably 100 to 200 μm. The crushed fine crushed material is discharged together with an airflow generated by blowing air (not shown) or the like from the discharge side, and the coarse crushed material not entrained by the airflow remains in the dry pulverizer 36 to have a desired shape. Grind to particle size.

The fine objects to be crushed entrained in the air flow are captured by means such as a bag filter (not shown) and stored in the next storage tank 38. Storage tank 38
The material to be ground stored in the storage tank is sealed by the rotary valve 42 between the supply pipe 40 and the storage tank 38, and the material to be ground in the storage tank 38 is continuously discharged.

The material to be pulverized discharged through the rotary valve 42 is conveyed by compressed air flowing through the supply pipe 40 in an air stream. The conveyed material to be crushed is supplied as raw fuel for the boiler 46 or the like via the burner 48, for example. In this embodiment, the mixture powder of the waste plastic 2 and the pulverizing medium 4 which is the object to be pulverized is burned in the boiler 46, but is not limited to the boiler and may be used as a gasification source in a gasification furnace or the like. Good.

In this embodiment, the fine slag used as the grinding medium 4 has a composition of 68.2% by weight of fixed carbon, 27.3% by weight of ash and 4.5% by weight of volatile matter, and has a geometric mean diameter of 69. 0.8 μm. Coal or petroleum coke slurry supplied to a high-temperature, high-pressure gasification furnace is mostly gasified by a partial oxidation reaction in the furnace, and the generated chemical gas such as CO and H ₂ Then, it is quenched in a quenching chamber below the gasification furnace. In this case, a slurry composed of by-product slag containing unreacted solid fuel generated during the gasification reaction and water is formed in the lower end region of the quenching chamber, and this slurry has an appropriate opening, for example, 1.168 m.
The slurry was separated and dehydrated with a m (14 mesh) sieve, and only the slurry containing fine slag that passed through the sieve was taken out.

Next, apart from the above-described solid fuel / water slurry, a so-called COM (Coa) was used as a solid fuel / oil slurry.
l Oil Mixture). In this example, as in the case of the solid fuel / water slurry, fine slag was added to the molten PET bottle,
After being cooled and solidified, it is pulverized finely and subsequently added with heavy fuel oil C to obtain a solid fuel / oil slurry.

As the fine slag, what was generated during gasification of petroleum coke was used.
4 parts by weight of PET (PET bottle) (80 parts by weight)
Wt%). As a result of the experiment, in the case of COM at 65 ° C., the relationship between the concentration and the viscosity is as shown in Table 3 below.

[0042]

[Table 3]

In the case of COM, the viscosity decreases when the temperature rises to 65 ° C. or higher. Therefore, in order to maintain the same viscosity, the mixture of PET and fine slag can be relatively increased. Conversely, when the temperature falls to 65 ° C. or lower, the viscosity increases. Therefore, if the same viscosity is to be maintained, a mixture of PET and fine slag is relatively reduced. Figure 5 shows CO
FIG. 4 is a graph showing the relationship between the viscosity when the temperature of M is 65 ° C. and the concentration of a mixture of PET and fine slag, and is a graph of Table 3. FIG. In the examples, the results were shown with water or C heavy oil as the slurry fluid medium, but the present invention is not limited to these examples.

[0044]

As is apparent from the above description, in the present invention, the fineness of the waste plastic is improved by mixing the waste plastic with fine slag and the like, so that the waste plastic can be used as a raw fuel for boilers and gasification furnaces. Can be used. Further, since waste plastic can be treated, it is possible to reduce waste such as industrial waste and general waste.

[Brief description of the drawings]

FIG. 1 is a block flow diagram according to the present invention.

FIG. 2 is a diagram illustrating the production of waste plastic slurry using the waste plastic of the present invention.

FIG. 3 is a diagram illustrating the production of raw fuel using the dry waste plastic of the present invention.

FIG. 4 is a cumulative frequency distribution curve showing crushability when the ratio between a PET bottle and slag is changed.

FIG. 5 is a graph showing the relationship between the viscosity when the temperature of COM is 65 ° C. and the concentration of a mixture of PET and fine slag.

[Explanation of symbols]

 Reference Signs List 2 waste plastic 4 crushing medium 6 injection molding machine 8 hopper 8a throat section 10 barrel 12 kneading screw 14 shielding plate 16 discharge port 18 cooling conveyor 20 roller 22 belt 24 wet crusher 26 dispersant 28 water 30 storage tank 32 feed pump 34 burner 36 dry pulverizer 38 storage tank 40 feed pipe 42 rotary valve 44 blower 46 boiler 48 burner

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Morihiko Sawada 5 at 1978 Kogushi, Oji, Ube City, Yamaguchi Prefecture Inside Ube Research Institute, Inc. (72) Inventor Yoshiharu Sawamura 5 at 1978 Kogushi, Oji, Ube City, Yamaguchi Prefecture Ube Industries Ube Laboratory Co., Ltd.

Claims (2)

[Claims] 1. Premixed with at least one of waste plastics and slag discharged from a coal gasifier, fly ash or bottom ash discharged from a coal boiler, inorganic minerals such as clay, and pulverized coal such as coal. The mixture obtained by further melting and mixing the mixture obtained by the preliminary mixing is cooled, and then the mixture obtained is cooled, pulverized, slurryed or powdered, and used as a raw fuel for a gasification furnace or a boiler. A method of using waste plastic, characterized in that: 2. The waste plastics according to claim 1, wherein at least one of slag, fly ash or bottom ash, inorganic minerals such as clay, and pulverized coal such as coal is mixed in an amount of 75% by weight or more and 97% by weight or less. Slags, fly ash or bottom ash,
A method of using waste plastic, wherein at least one of inorganic minerals such as clay and pulverized coal such as coal is contained in an amount of 3% by weight or more and 25% by weight or less.