JPH0329836B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing solid fuel using waste plastics.

[Conventional technology]

Conventionally, wood-based solid fuels have been produced simply by crushing, extrusion, and pressure molding, such as the ogalite method or Udecks pellets. Therefore, it is beautiful immediately after molding,
Although we can expect considerable strength from this type of solid fuel,
While stored in warehouses or elsewhere, the product absorbs moisture from the air and deteriorates, and as it contains more than 15% water, its value as a fuel is halved. For this reason, some conventional fuels have included waste plastics added to the above-mentioned wood-based solid fuel.

[Problem to be solved by the invention]

However, when using a large amount of the above-mentioned waste plastics, a dedicated furnace must be used, otherwise the combustion process will be
Immediately after the coal is dumped, rapid thermal decomposition occurs and a significant amount of black smoke is emitted, which not only becomes dust, but also
Furthermore, over time, the plastic melts and drips, making it no longer a good quality fuel. This obstructed ventilation inside the furnace, and there was a risk that combustion would be interrupted.

Furthermore, the waste plastics used as the above-mentioned compounding materials often contain some amount of vinyl chloride, which generates harmful gases when burned. In general, raw materials containing waste plastics are passed through a heating cylinder at a temperature of around 200 degrees Celsius, and the final The kneaded material obtained from the outlet is compression molded into solid fuel, but if it contains more than 10% vinyl chloride, it will cause secondary pollution and cannot be used as a raw material. That is, if a solid fuel product contains a large amount of chlorine, it undergoes thermal decomposition during combustion and generates chlorine gas and HCl gas. Therefore, it cannot be used as a fuel because it corrodes equipment and pollutes the environment.
For example, when such fuel is used as fuel for a heating machine for greenhouse cultivation, there is a problem that chlorine gas and HCl gas are mixed in the combustion gas, and this exhaust gas can cause the surrounding crops to wither. It was hot.

[Means to solve the problem]

This invention was made to solve the above-mentioned problems, and the solid fuel production method using waste plastics of the present invention uses 20 to 70% thermoplastic plastics such as waste polyethylene, polypropylene, and polystyrene. The balance is mixed with agricultural and forestry waste such as sawdust, burgundy, paper residue, cellulose, and bagasse, and the combustion temperature in the combustion chamber is set to the highest in the order of primary combustion chamber, secondary combustion chamber, and tertiary combustion chamber.
Multiple units are arranged in order from 1100℃ to a minimum of 1000℃, and for raw materials with a vinyl chloride content close to the highest value of the allowable range, a screw with the highest kneading effect is used in the primary combustion chamber where the combustion temperature is highest, and the chloride For raw materials with a low vinyl content, a screw with a small kneading effect is used in the primary combustion chamber, and dechlorination is performed by heat treatment while applying forced grinding and mixing to the raw materials in an atmosphere in the range of 270℃ to 290℃. After performing the process, solid fuel is produced by a compression molding process.

〔Example〕

FIG. 1 shows a heating and melting apparatus used to carry out the method of this invention, and this heating and melting apparatus A is
A power unit 6 that rotates a screw 3 in a heating cylinder 4 (described later) in one direction is arranged at one end position on the base 1. At an intermediate position adjacent to this power section 6, there is a raw material C, which will be described later, to become solid fuel.
A hopper 7 for charging the raw material is installed vertically so as to be able to supply the raw material to the screw 3. A combustion chamber 2 shown below is arranged at the other position on the base 1. The combustion chamber 2 includes a primary combustion chamber 2a, a secondary combustion chamber 2b, and a tertiary combustion chamber 2c, which are divided by vertical walls. Primary combustion chamber 2a, secondary combustion chamber 2
b. The axial lengths of the tertiary combustion chambers 2c are approximately equal. A rooster 9 on which fuel B is placed is provided at the bottom of the primary combustion chamber 2a. Primary combustion chamber 2
A ventilation hole 5 for introducing air from the outside is provided on the side wall surface of the secondary combustion chamber 2b and the secondary combustion chamber 2b, and a chimney is provided on the top of the terminal chamber 2c. Each room 2a, 2b, 2
The combustion temperature of c is set as follows. That is, the temperature of the primary combustion chamber 2a is 1100℃, and the temperature of the secondary combustion chamber 2b is
The temperature in the tertiary combustion chamber 2c is 1000°C. Therefore, if we arrange this in order of temperature, 2a>2b>2c...(1).

A heating cylinder 4, which is provided with heat exchange fins 4a over the entire outer periphery at approximately the center height within the combustion chamber 2, is installed in a horizontal arrangement penetrating the above-mentioned chambers 2a, 2b, and 2c. A screw 3 having a length extending through the hopper 7 and the combustion chamber 2 from a position immediately before the hopper 7 to the outer end of the combustion chamber 2 connects a shaft 3e to the power unit 6 and uses the driving force and the heating cylinder 4.
It is shaft-fitted to allow rotation in one direction by a supporting body. This screw 3 has the following 4
Different types of screws 3A, 3B, 3C, and 3D are provided. That is, as shown in FIG. 2a, the screw 3A has a spiral blade portion 3f.
are continuously provided around the entire circumference of the shaft 3e. The screw 3B has blade portions 3f and gap portions 3g arranged alternately around the shaft 3e. However, most of the space is occupied by the blade portion 3f. Further, in the screw 3C, mid-range void portions 3g are provided in the same arrangement at four locations in one round of the blade portion 3f, and the blade portion 3f and the void portion 3g are formed in approximately the same volume area. Further, in the screw 3D, large-area voids 3g are similarly provided at four locations in one round of the blade portion 3f, and the volume of the blade portion 3f is smaller than that of the void portion 3g. Each screw 3B, 3
The length of C, 3D is the length of each combustion chamber 2a, 2b, 2 mentioned above.
It is approximately equal to the axial length of c. The screw 3A mentioned above only serves to feed the raw material C, but
The area proportions of the blade portion 3f and the gap portion 3g of the screws 3B, 3C, and 3D are different, and the gap portion 3g does not feed the raw material C, so the raw material C stays, and the retained raw material C is transferred to the blade portion. Kneaded by 3f. The larger the void portion 3g is, the larger the retention amount is, so the kneading effect increases. That is, the kneading action is as follows in descending order of magnitude.

3D＞3C＞3B ...(2) The raw material C is located directly below the terminal end of the screw 3 in the heating cylinder 4.
An outlet 8 for the heated melt D kneaded by C and 3D is provided.

A method for producing solid fuel using the heating melting apparatus A having the above configuration will be explained.

In FIG. 2a, the screw 3 has a blade portion 3 on the entire circumference at the initial end side, as shown in a partial cross section.
A screw 3A having a small gap 3g is placed next to it, a screw 3B having a small gap 3g is placed next to the screw 3A, a screw 3C having a medium gap 3g is placed next to the screw 3A, and a screw 3C having a large gap 3g is placed at the terminal position. Gap 3g
The screws 3D having the following values are sequentially provided.
Then, when fuel B is put on the rooster 9 of the primary combustion chamber 2a and air is blown into the primary combustion chamber 2a from one of the vent holes 5, the secondary combustion chamber 2b also has a similar vent hole 5, and the tertiary combustion chamber 2a also has a similar vent hole 5. Since a chimney is provided at the top of the combustion chamber 2c, each chamber exerts its combustion power according to the temperature order according to equation (1) above.

At the same time as combustion starts, 20 to 70%
thermoplastic plastics such as waste polyethylene, polypropylene, and polystyrene, and the remainder (80 to 30
%) of agricultural and forestry waste such as sawdust, burgundy, paper waste, cellulose, and bagasse is input, the screw 3 is rotated in one direction by the driving force of the power unit 6, In the combustion chamber 2, the raw material C that has been
Under the combustion temperature of c, the material is subjected to the kneading action described in equation (2) above, and is subjected to heat treatment while being subjected to forced grinding and mixing action in an atmosphere in the range of approximately 270 to 290°C. Become. Therefore, when vinyl chloride is mixed in raw material C, the lowest temperature in the combustion chamber 2 is 270°C or higher, so at this temperature vinyl chloride decomposes and chlorine gas and
It becomes HCl gas and is separated from the raw material. After the raw material is discharged from the outlet 8 as a kneaded heated melt D, it can be produced into solid fuel through a compression molding step provided next to the heated melting device.

FIG. 2b shows a modification of the screw. From the left, Screw 3 is Screw 3A, 3C, 3D,
They are provided in the order of 3B. Then, the screw 3C with a relatively high kneading effect is located in the primary combustion chamber 2a where the combustion temperature is highest, and the screw 3D with the highest kneading action is located in the secondary combustion chamber 2b with the next highest combustion temperature. Therefore,
Even if the raw materials contain a large amount of vinyl chloride, chlorine can be easily and sufficiently removed as a result of sufficient kneading in the high temperature range.

FIG. 2c shows yet another modification of the screw. Screw 3 is screw 3A, 3 from the left.
They are provided in the order of D, 3C, and 3B, which is the reverse order of the first embodiment. Therefore, since the screw 3D with the highest kneading effect is located in the primary combustion chamber 2a where the combustion temperature is highest, the raw materials are sufficiently kneaded in the high temperature range and chlorine can be sufficiently removed. This embodiment is suitable when the mixing ratio of vinyl chloride in the raw material is close to the maximum value of the allowable range.

As stated above, Screw 3A, 3B,
By preparing multiple types of screws 3 with different positions of 3C and 3D, and selecting the suitable screw according to the mixing ratio of vinyl chloride in the raw materials, the heating temperature and degree of kneading to which the raw materials are subjected can be adjusted. can be adjusted to sufficiently remove chlorine and produce high-quality solid fuel.

Next, the physical properties of the solid fuel produced in each of the above examples are shown in FIG. 3 and subsequent figures. In the figure, a shows the test results when using the screw shown in Fig. 2 a, b shows the test results when using the screw shown in Fig. 2 b, and c shows the test results when using the screw shown in Fig. 2 c. Show the test results.

FIG. 3 shows the water resistance (water immersion strength) and heating temperature of solid fuel. FIG. 4 shows the pressure resistance and heating temperature. FIG. 5 shows the water absorption rate and heating temperature. Figure 6 shows the individual product weight and heating temperature. FIG. 7 shows the product density and heating temperature. FIG. 8 shows the relationship between heating temperature and dechlorination rate for each product in each example. FIG. 9 shows the relationship between the passage time in the heating device and the dechlorination rate in each example.

[Effect of the invention] Each screw 3B, 3C, 3D has a blade portion 3f.
The area ratio of the void part 3g and the void part 3g are different, and the screw with a large area ratio of the void part 3g and the void part 3f has a large circulation amount of raw materials, so the kneading effect is large, and the screw with a small area ratio. has a small kneading effect.

In a combustion chamber with a high temperature, the chlorine removal action is promoted compared to a combustion chamber with a lower temperature.

When the mixing rate of vinyl chloride in the raw material is high, chlorine can be sufficiently removed by placing the screw 3D, which has the greatest kneading effect, in the combustion chamber 2a, which has the highest temperature, so that a harmless and high-quality solid material can be removed. Fuel can be produced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a heating and melting device used in carrying out the present invention, Fig. 2a is a side view of the screw, Fig. 2b is a side view of a modified example of the screw, Fig. 2c
3 is a side view of yet another modification of the screw.
9 to 9 are diagrams showing the characteristics of solid fuel produced by the method of the present invention. 2... Combustion chamber, 2a... Primary combustion chamber, 2b...
Secondary combustion chamber, 2c...Tertiary combustion chamber, 3, 3A, 3
B, 3C, 3D... Screw, 3e... Axis, 3
f...Blade part, 3g...Gap part, 4...Heating cylinder, 6...Power part, A...Heating melting device, C
……material.

Claims (1)

[Claims] 1 Using a raw material that is a mixture of 20-70% thermoplastic plastics such as waste polyethylene, polypropylene, and polystyrene, and the remainder being agricultural and forestry wastes such as sawdust, bark, paper waste, cellulose, and bagasse, the combustion temperature in the combustion chamber is controlled. Maximum 1100℃ to minimum 1000℃ in the order of primary combustion chamber, secondary combustion chamber, and tertiary combustion chamber
For raw materials with a vinyl chloride mixture rate close to the highest value within the allowable range, a screw with the highest kneading effect is used in the primary combustion chamber where the combustion temperature is highest, and the vinyl chloride mixture rate is low. The raw materials are subjected to a dechlorination process in which a screw with a small kneading effect is used in the primary combustion chamber, and the raw materials are heat treated while being subjected to forced grinding and mixing in an atmosphere in the range of 270°C to 290°C. A method for producing solid fuel using waste plastic, characterized by producing solid fuel through a compression molding process.