Method for producing solid fuel

The present invention relates to a method for producing solid fuel (RPF) by mixing waste plastic sorted and recovered from municipal waste, industrial waste, and the like with combustible waste and recovered waste paper, and compressing and molding them.

Conventionally, there has been a technology to manufacture solid fuel (RPF) by adjusting the calorific value by adding paper such as waste paper collected separately to waste plastic and combustible waste selected from municipal waste and industrial waste. Are known. In this case, the combustible waste contained various miscellaneous substances, and it was sometimes difficult to mold the waste. In particular, when the raw material waste plastic or combustible waste contains a large amount of water, or when the water content varies, it may be difficult to form uniform properties.

Therefore, in recent years, a method of carbonizing combustible waste once, mixing waste plastic and used paper with the carbonized material, and then compressing and molding to obtain a solid fuel (RPF) mainly composed of waste plastic has been adopted, for example, Japanese Patent Application Laid-Open No. 2001- Proposed in Gazette 240882. That is, as shown in Fig. 4, the solid fuel production method consists of a carbonization process in which combustible waste containing vegetable waste and fish meat waste is steamed with a carbonizer to make charcoal, and waste plastic and waste paper are added to the charcoal. A mixing step of adding a predetermined amount and mixing with a mixer, a crushing step of crushing the mixed charcoal, waste plastic and waste paper with a crushing device, a compression step of compressing the crushed mixture with a compression device, and a compressed crushing mixture. It consists of a molding process of molding to make solid fuel.

This will reduce the amount of combustible waste by effectively reusing combustible waste containing vegetable waste and fish waste, reduce the cost of solid fuel, and realize inexpensive solid fuel. There is an advantage that can be done. Further, the molded solid fuel has an advantage that the combustion efficiency in the combustion furnace can be improved and stable heat can be obtained at a high temperature by making the one side or the diameter into a piece of 8 to 50 mm. Furthermore, for example, a solid fuel can be obtained by mixing 30% by weight of waste charcoal, 20% by weight of waste plastic, and 50% by weight of used paper, and the calorific value can be adjusted by changing the mixing. (See Patent Document 1).

Further, as a conventional technique for solid fuel using carbides, for example, Japanese Patent Application Laid-Open No. 09-53085 can be mentioned. This is a method for producing solid fuel by crushing, drying, separating, and molding municipal waste. A part of the produced solid fuel is used, and the carbonized product obtained by carbonizing the solid fuel is used as a deodorizing / preservative. This is a method of adding to waste plastic and used paper, which are molding raw materials in the fuel molding process, to form solid fuel. That is, the carbide is mixed in the molding raw material of the solid fuel and supplied to the molding apparatus, and the sensible heat possessed by the carbide is used for heating the molding raw material (see Patent Document 2).<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-240882</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 09-53085</text></patcit>

<p> However, the technique of Patent Document 1 is to mix waste charcoal together with waste plastic and used paper in a mixer and then crush it with a crusher. Therefore, the mixer and the crusher are operated by mixing the waste charcoal. Power) The load will increase. Moreover, since the waste charcoal usually has a low water content, the waste charcoal is pulverized and scattered in the mixing / crushing process, which causes deterioration of the working environment.</p><p> Further, in the technique of Patent Document 2, a part of the molded solid fuel, that is, 30% of the molded solid fuel is separated, and the separated solid fuel is carbonized to be a carbide, and this carbide is molded. Since it is added to the raw material waste plastic and used paper, the addition of the carbides improves the moldability to some extent, but it cannot be said to be sufficient. The reason is that when the separated solid fuel is carbonized, the amount after carbonization is reduced to about 1/3, and even if the entire amount is mixed, the amount of carbide mixed in the molding raw material is not as large as about 10%. It depends. In addition, the productivity of solid fuel as a product decreases due to the separation. Moreover, there is a problem that a solid fuel molding machine having a molding capacity corresponding to the amount to be separated for carbonization must be used, and wasteful power is consumed accordingly.</p><p> INDUSTRIAL APPLICABILITY The present invention reduces the crushing power load, does not deteriorate the working environment due to the scattering of dust, contributes to the reduction of the molding power basic unit, does not reduce the productivity, and does not waste power. That is the issue.</p>

<p> In order to achieve the above object, the present invention was obtained by supplying waste plastic and recovered waste paper to a crusher at a predetermined ratio to crush the crushed mixture, and carbonizing the crushed mixture and the combustible waste. A configuration is adopted in which a predetermined amount of carbonized material is supplied to a compression / molding machine to be compressed and molded.</p><p> When molding solid fuel as described above, by adding a predetermined amount of carbide instead of a part of waste plastic, the viscosity that increases with semi-melting due to mixing and compression of waste plastic is small. It is suppressed by the charcoal and the fluidity is improved, so that the moldability of the solid fuel is improved. Further, since the carbides are not added together when the waste plastic and the used paper are crushed (by the crusher), the power load applied to the crusher is reduced by that amount, and the carbides are not scattered due to crushing powder. ..</p><p> The mixing amount of the carbide is set within the range of 15 to 30% by weight. If the amount of waste plastic is reduced and the amount of carbide mixed in is increased accordingly, the moldability will be improved as described above, which will contribute to the reduction of the power intensity. Carbage, which is less likely to form (pellets) and has a smaller calorific value than waste plastic, greatly reduces the amount of heat retained in the molded solid fuel and increases the ash content after combustion in the incinerator, making it suitable for thermal recycling. However, during actual operation, carbon dioxide is generated and the working environment deteriorates. On the other hand, if the amount of carbide mixed is 15% or less, the moldability cannot be improved. Therefore, the mixing amount is preferably about 20%.</p>

<p> In the present invention, as described above, by adding a predetermined amount of carbides to waste plastic and recovered recycled paper, moldability is improved and the molding power basic unit thereof is reduced. Further, since the carbide is not supplied at the time of crushing the waste plastic and the used paper, the working environment is not deteriorated by the scattering of the carbide due to the crushing powder. In addition, since carbonized material obtained by directly carbonizing combustible waste is used, it is solid compared to the conventional one in which a part of the molded solid fuel is separated and the carbonized material obtained by carbonization is mixed with the molding raw material. No reduction in fuel productivity is required, and no extra molding power is required. Therefore, the molding cost can be greatly reduced. Furthermore, by setting the amount of carbide added within the range of 15 to 30% in terms of weight ratio with waste plastic and used paper, moldability is improved and the molding power basic unit is reduced by 3 to 8%.</p>

As shown in FIG. 1, an embodiment of the present invention includes a carbonization process for carbonizing the combustible waste and crushing for crushing the waste plastic and waste paper among waste plastic and combustible waste selected from municipal waste and industrial waste. A solid fuel is produced through the compression / molding step by adding a predetermined amount of the charcoal in the carbonization step to the waste plastic and waste paper in the step and the crushing step.

Specifically, as shown in Fig. 2, the receiving conveyor 1 is used to mix waste plastic and collected waste paper in an appropriate proportion among the waste plastic and combustible waste sorted and collected from municipal waste and industrial waste. It is put into the uniaxial crusher 2 and crushed into small pieces so as to have a constant particle size, and the subsequent mixing is made easier. The crushed waste plastic and used paper are conveyed by the transfer conveyor 3 and put into the fixed quantity supply device 4. The fixed quantity supply device 4 includes a supply conveyor 4a and a hopper 4b provided at the base end thereof. On the other hand, the combustible waste is carbonized by a carbonization device 5 such as a rotary kiln, and the obtained carbonized material is temporarily stored in the hopper 6a of the carbide input conveyor 6, cut out in a fixed amount from the cutting screw 6b below the carbonized waste, and supplied in a fixed amount. It is put into the hopper 4b of the device 4. The mixing amount of carbides is appropriately adjusted according to the amount of waste plastic and used paper.

The above-mentioned waste plastics and combustible waste are those that are separated and sorted after primary crushing of municipal waste and industrial waste. Combustible waste is mainly wood waste and paper waste, and waste paper is separately collected magazines and old newspapers. Although it is corrugated cardboard, wood materials can be used instead of the collected waste paper. Garbage can be included as combustible waste. Further, when powder is used as the carbide to be added to the waste plastic and used paper, the amount to be added can be easily adjusted, and the calorie of the carbide is almost constant at about 4500 kal / kg, so that the calorie of the solid fuel to be molded can be easily adjusted. It becomes.

The waste plastic and waste paper crushed mixture and carbide of the hopper 4b are conveyed by the supply conveyor 4a and supplied (charged) to a compression / molding apparatus 7, for example, a pellet mill from the discharge port 4c, where they are mixed, compressed, and charged. It is molded and discharged as a molded product. The discharged molded product, that is, the product (solid fuel = RPF) is placed on the product conveyor 8 and stored in the hopper 9, and is stored in the predetermined container 10 by opening the opening / closing gate 9a of the hopper 9. To.

The crushed mixture and carbide of waste plastic and used paper are supplied to the pellet mill device 7 and molded. That is, as shown in FIG. 3, the crushed mixture and carbide 12 are continuously supplied from the side portion into the mill body 11 through the supply side chute 13 and the cone portion 14, and the compressed / molded molded product 15 is placed in the lower portion. It is designed to be discharged through the discharge side chute 16 that discharges from. A cylindrical ring die 17 having a large number of forming holes 18 in the mill body 11 is supported by a rotating shaft 19, which is connected to a motor 21 via an appropriate drive transmission function 20. Therefore, the ring die 17 is rotationally driven at a predetermined rotational speed using the motor 21 as a drive source.

A pair of rollers 22 are provided in the ring die 17, and the rollers 22 are rotatably supported on the tip side of the fixed shaft 23 and can roll on the inner peripheral surface of the ring die 17 with a predetermined clearance. It has become like. The waste plastic and the crushed mixture of used paper and the carbide 12 supplied into the mill body 11 are sequentially mixed and compressed between the inner peripheral surface of the ring die 17 and the outer peripheral surface of the roller 22, and the waste plastic generates heat by this compression. Along with this, the recycled paper and carbides are extruded from the molding holes 18 to a predetermined density as a columnar product, and the extruded columnar product is cut by a cutter 24 to form a molded product (pellet) having a predetermined length. It is formed at 15. As the compression / molding apparatus 7, the pellet mill apparatus is used in the above description, but the present invention is not limited to this, and other than this, for example, a twin-screw extrusion molding machine may be adopted.

Experiments were performed on the samples shown in Table 1 using a pellet mill. Samples 1 and 2 in Table 1 are comparative examples, and samples 3 to 5 are experimental examples of the present invention. Solid fuel was molded by keeping the amount of paper constant and changing the amount of waste plastic and carbide. The amount of processing, the power intensity, and the amount of heat retained in the molded product during this molding were measured (the operating status of the molded product is shown in the table below). Compression / molding machine specifications Pellet mill device 650BC-75 x 2 Ring die inner diameter x width: φ650 mm x 175 mm Rotation speed: 176 rpm Electric motor: 75 kW x 2 (400 V, 50 Hz, 3-phase)

<tables num="1"><img file="JP2005290129A_D0001.tif" /></tables>

From the above results, the solid fuels obtained by the production method of the present invention, for example, Samples 3 and 4, have improved moldability and are a power source, although there is a slight decrease in the amount of processing as compared with Sample 2 to which no carbide is added. The unit decreased by 3-8%. That is, if the amount of waste plastic added is large, the viscosity of the waste plastic due to heat generation increases and the moldability decreases. However, by adding a part of the amount of waste plastic added instead of carbide, low-viscosity carbides are added. At the same time, the increase in viscosity is suppressed and the moldability is improved. As described above, the decrease in the power intensity is larger than the decrease in the processing amount, so that the molding cost is low.

<figref num="1">The block diagram of the solid fuel production facility of waste which concerns on embodiment of this invention.</figref><figref num="2">The flowchart of the solid fuel production facility of waste which concerns on embodiment of this invention.</figref><figref num="3">The compression / molding apparatus according to the embodiment of the present invention is shown, (a) is a vertical sectional view, and (b) is an AA line arrow view of (a).</figref><figref num="4">Schematic block diagram of the prior art.</figref>

Code description

1 Receiving conveyor 2 Single-screw crusher 3 Conveyor conveyor 4 Quantitative supply device 4a Supply conveyor 4b Hopper 4c Discharge port 5 Carbonization device 6 Carbage input conveyor 6a Hopper 6b Cutting screw 7 Compression / molding device (pellet mill) 8 Product conveyor 9 Hopper 9a Gate 10 Container 12 Crushed mixture and carbide 13 Supply side chute 14 Cone part 15 Molded product (pellet) 16 Discharge side chute 17 Ring die 18 Molding hole 19 Rotating shaft 20 Drive transmission function 21 Motor 22 Roller 23 Fixed shaft 24 Cutter