JP2007146044A - Process and apparatus for producing fuel from waste like municipal waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease a heavy metal concentration in ashes after combustion of a fuel produced by eluting heavy metals contained in a carbonized product resulting from the carbonization of domestic waste and mixing the resultant carbonized product with paper and waste plastics. <P>SOLUTION: Domestic waste 1 is subjected to pyrolysis in a pyrolysis furnace 2. The resultant carbonized product 4 is pulverized and washed with water in a washing water tank 6. Heavy metals contained in the carbonized product 4 are eluted into the water by the washing, to decrease a heavy metal concentration in the carbonized product 4. Subsequently, the carbonized product 4a with heavy metals at a lower concentration is mixed with paper 14 and waste plastics 16 and molded, and further cooled and solidified to produce a solid fuel 25. Ashes after combustion of the solid fuel 25 have a decreased concentration of heavy metals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing fuel by using pyrolysis of carbonized waste (C: char) obtained from pyrolysis of waste such as municipal waste. The present invention relates to a method and an apparatus for producing fuel from waste such as municipal waste, in which waste plastics and the like as waste are mixed and molded into fuel (C-RPF).

As fuel, fossil fuels such as coal with a high calorific value have been used as having high utility value, but when they are burned, carbon dioxide (CO ₂ ) is generated, which causes the problem of global warming. ing. For this reason, development of fuel-based methods using waste that can contribute to the prevention of global warming by reducing CO ₂ and can be expected as an alternative to fossil fuels has been underway.

As one of the methods of making fuel from waste that has been developed in recent years, waste solidified fuel (RDF: Refuse) is processed through processes such as crushing, sorting, and compression molding using waste (general waste) such as municipal waste as raw materials. Derived Fuel) is manufactured and used as fuel for power generation and other various incinerators.

  However, since the raw material used for the RDF is general waste, there is a large variation in composition, and therefore, the amount of heat generated during combustion may become unstable, and it is difficult to stabilize the quality. It was said. In addition, when the general waste used as a raw material contains moss and the like, there is a concern about the problem of spoilage. Therefore, it is necessary to adjust pH by adding lime or the like separately. Furthermore, since the calorific value at the time of combustion is relatively low, the utility value as a fuel is not so high.

  Therefore, in order to obtain solid fuel with a high calorific value of fuel, paper (waste paper) and plastic (waste plastic) as industrial waste whose emission source is clearer than general waste such as municipal waste In recent years, attention has been focused on producing high-calorific solid fuel (RPF: Reuse Paper & Plastic Fuel) using waste paper selected from general waste and waste plastic as raw materials.

  The RPF is, for example, crushed waste paper that is difficult to recycle and waste plastic from which chlorine-containing plastics such as vinyl chloride have been removed, and then mixed to obtain a mixture of the waste paper crushed piece and waste plastic crushed piece into a required shape. It is designed to be manufactured by extrusion molding (compression molding). As a result, the RPF can stabilize the quality as a fuel due to the use of relatively stable raw materials such as waste paper and waste plastic, and can eliminate the risk of corruption. Therefore, the amount of heat can be increased to the extent that it can be used as an alternative fuel for fossil fuel, and the utility value as fuel can be increased. Furthermore, it is also possible to adjust the heat generation amount by changing the mixing ratio of waste paper and waste plastic.

  Furthermore, in addition to the waste paper and waste plastics similar to the RPF, the following methods have also been proposed as methods for converting to solid fuel using a wider range of combustible waste as a raw material. That is, as shown in FIGS. 3 and 4, combustible waste (waste) a such as waste mainly discharged from households is first installed in a carbonization apparatus (pyrolysis furnace) not shown in the carbonization step ST1. And carbonized by steaming to make trash char (carbide) b. Next, in the mixing step ST2, the garbage charcoal b, waste plastic c, and waste paper d are mixed at a predetermined weight ratio, and then the mixture is crushed to a required size in the crushing step ST3. Next, the obtained crushed product is compressed in the compression step ST4 until the contained plastic waste c is softened, and the compressed product is sized (molded) into a required shape in the sizing step ST5. ) To produce solid fuel.

  Specifically, the compression step ST4 and the granulation step ST5 are performed by one compression / granulation device e as shown in FIG. That is, a compression / granulation apparatus e shown in FIG. 4 is inscribed in a rotating drum-shaped die (ring die) g having a large number of die holes h in a peripheral wall surface in a casing f and the die g. The rollers i and j that support and rotate the die g, the cutter k disposed along the outer peripheral surface of the die g, and the crushed material l crushed in the crushing step ST3 to the inside of the die g. It is composed of an input duct m to be input. Thereby, the crushed material l thrown into the inside of the die g through the throwing duct m is pushed into the die hole h by being strongly pushed by the rollers i and j, and at this time, the shatter already in the die hole h. The object l is pushed out from the die hole h so as to protrude to the outer peripheral side of the die g, and the crushed object l of the protruding part is cut by the cutter k, so that the diameter is constant and the length is constant. Granulated solid fuel (waste carbonized and paper / plastic mixed fuel) n is manufactured (for example, see Patent Document 1).

  Solid fuel obtained by mixing waste plastics with char (char) obtained by carbonizing the above general waste, and compressing the solid fuel is mixed with waste plastics that have a calorific value higher than that of the carbides. The amount of heat is adjusted to be comparable to the amount of heat of coal as a fossil fuel, and is attracting attention as being able to obtain the amount of heat at the coal level.

In addition, the carbonized material obtained by carbonizing general waste containing chlorine-containing plastics such as vinyl chloride retains the chlorine content that was not gasified during the carbonization process in the carbonization furnace (pyrolysis furnace). May have. When the solid fuel produced by compression molding after mixing paper and waste plastic with the remaining carbides is used as a fuel, harmful gases such as hydrogen chloride gas are generated. There's a problem. Therefore, as the desalting of the carbide, most of the chlorine content is an inorganic salt (NaCl, CaCl ₂ ), which can be dissolved and easily removed by washing with water. It has been proposed that the carbide is desalted by dehydrating and drying after washing (see, for example, Patent Document 2).

JP 2001-240882 A JP 2002-95993 A

  However, in the case of carbide obtained by carbonizing municipal solid waste such as municipal waste, it has been found that the content of heavy metals such as lead, chromium and selenium is higher than that of coal, wood, paper and the like. Solid fuel (C-RPF) formed by mixing paper and waste plastic as described in Patent Document 1 with the carbide obtained as described above is used as fuel. When burned, the heavy metals contained in the carbide are concentrated on the incineration ash side except for some heavy metals with a low boiling point. If the heavy metal concentrated on the ash side elutes, it becomes difficult to reuse the ash or it cannot be disposed of in landfills. Therefore, until now, the actual situation is that the contrivance and idea to prevent elution of heavy metals in ash generated by incineration have been mainly taken, and the concentration of heavy metals has not been reduced. . Patent Document 1 discloses that such a carbide has a heavy metal content, and when incinerated using solid fuel produced by mixing paper and waste plastic with the carbide, heavy metal is contained in the incineration ash. There is no description or suggestion of being concentrated, reducing the heavy metal concentration in advance, or the like.

  Therefore, the present invention reduces the concentration of heavy metals concentrated on the ash side when fuel produced using char obtained from carbonization of general waste such as municipal waste is used as fuel. Thus, the present invention aims to provide a method and an apparatus for producing a fuel with a high calorific value in place of fossil fuel such as coal.

  In order to solve the above-mentioned problem, the present invention is to directly wash the carbide obtained by pyrolyzing waste such as municipal waste with water, or wash the pulverized carbide after pulverization with water, The heavy metal contained in the carbide is eluted in water, and then the carbide having a reduced concentration of heavy metal is dehydrated and dried. Next, the dried carbide is mixed with paper and / or waste plastic, and then the required shape is obtained. A method and apparatus for producing a solid fuel by molding.

  Further, in the above configuration, the pH of the cleaning water is adjusted so that the carbide is cleaned, and the elution of heavy metal in the carbide is promoted.

According to the method and apparatus for producing fuel from municipal solid waste such as municipal waste of the present invention, the following excellent effects can be obtained.
(1) The carbide obtained by pyrolyzing waste such as municipal waste is washed directly with water, or the pulverized carbide is washed with water to remove heavy metals contained in the carbide. A method of producing a solid fuel by eluting into water and then dehydrating and drying the carbides having a reduced heavy metal concentration, and then mixing the dried carbides with paper and / or waste plastic and then forming into a required shape. Therefore, heavy metals contained in the carbide can be removed in the process of producing fuel by mixing paper and waste plastic with the carbide of general waste. Thereby, the produced fuel can be made to have a low heavy metal concentration, the heavy metal concentration of the ash after being burned as the fuel is reduced, and the elution is also reduced. Therefore, the problem of ash reuse and landfill disposal can be solved or reduced.
(2) Moreover, by washing with a wash water adjusted in pH at the time of washing the carbide, heavy metals in the carbide can be positively eluted, and the heavy metal concentration in the carbide can be further reduced. Thereby, even the carbide containing a relatively large amount of heavy metal can be reduced in concentration, and the concentration of heavy metal in ash when used as fuel can be further reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of the present invention, in which municipal waste 1 such as municipal waste is pyrolyzed in a pyrolysis furnace 2 to produce pyrolysis gas 3 and carbide 4 as pyrolysis residue, After pulverizing the carbide 4, the carbide 4 is washed with water to elute the heavy metal contained in the carbide 4 into the water, and the wastewater is treated with a wastewater treatment device so that the heavy metal is taken out as sludge. The carbide 4 after being washed with water is dehydrated and dried, and then, as a carbide having a low heavy metal concentration, mixed with paper or waste plastic as industrial waste, compression-molded, dried, and then carbide and paper or waste. Solid fuel (C-RPF) made of plastic and having a low heavy metal concentration is produced.

  More specifically, municipal waste 1 such as municipal waste that does not contain chlorine-containing plastics such as vinyl chloride is pyrolyzed by indirect heating with external heat to produce pyrolysis gas 3 and carbide 4 as pyrolysis residue. The pyrolysis furnace (carbonization apparatus) 2 is charged and carbonized to generate carbides 4. Since the carbide 4 obtained by carbonizing the general waste 1 has a heavy metal content as compared with coal, wood, paper, etc. as described above, a high heat generation waste plastic or the like is added to the carbide 4. In the process of producing the solid fuel, heavy metals in the carbide are removed so that the leaching of heavy metals from the ash when the produced solid fuel is incinerated is reduced. Therefore, before mixing the waste plastic or the like with the carbide 4 obtained in the pyrolysis furnace 2, a pulverizer 5 and a downstream thereof are provided to pulverize and wash the carbide 4 taken out from the pyrolysis furnace 2. A cleaning water tank 6 as a cleaning device is provided on the side. A water supply line 8 for supplying water 7 is connected to the cleaning water tank 6, and a waste water treatment device 10 is connected via a drain line 9. Further, on the downstream side of the washing water tank 6, a dehydrating device 11 and a drying device 12 for sequentially drying the carbide 4a that has been washed and whose heavy metal concentration has been reduced are installed. A steam generator 22 that generates steam based on the pyrolysis gas 3 generated and taken out by the pyrolysis furnace 2 is connected to the drying device 12 via a steam line 23 to dry the carbide 4a. Steam 24 is used. Further, on the downstream side of the drying device 12, the paper 14 supplied from the paper supply unit 13 and the waste plastic 16 supplied from the waste plastic supply unit 15 to the dried low-concentration heavy metal-containing carbide 4 a are disposed. A mixer 17 for mixing is installed. A molding machine (for example, an extrusion molding machine) 19 for compressing and molding the mixture 18 of the carbide 4a, the paper 14, and the waste plastic 16 mixed in the mixer 17 is installed on the downstream side of the mixer 17.

  On the downstream side of the molding machine 19, a curing conveyor 21 is installed as a device for cooling and curing the molded product 20, and a solid fuel 25 made of carbide, paper, and waste plastic as a product is produced.

  Since it has the above-described configuration, when the general waste 1 is pyrolyzed in the pyrolysis furnace 2 to produce pyrolysis gas 3 and carbide 4 as a pyrolysis residue, each is taken out from the pyrolysis furnace 2. The carbide 4 taken out from the pyrolysis furnace 2 is finely pulverized by a pulverizer 5 and then charged into a washing water tank 6. Since the carbide 4 put into the washing water tank 6 is finely pulverized to increase the surface area, the contact area with the water 7 supplied into the washing water tank 6 through the water supply line 8 increases, and the carbide 4 Experiments confirmed that the contained heavy metals such as lead were easily dissolved in water. As a result of examining the heavy metal concentration of water in the washing water tank 6, the present inventor found that when the washing time was 5 minutes, lead was about 0.244 mg / L, chromium was about 0.006 mg / L, and selenium was about 0.00. As with 030 mg / L, it was confirmed that heavy metals were eluted at a considerable concentration on the washing water side. As described above, it has been found that the heavy metal concentration in the carbide can be lowered by elution of heavy metal to the washing water side at a considerable concentration.

  The heavy metal dissolved in the washing water by the washing in the washing water tank 6 is discharged from the washing water tank 6 as drainage through the drainage line 9 and finally taken out as sludge in the drainage treatment apparatus 10 and subjected to intermediate treatment as necessary. Will be done and disposed of.

  On the other hand, the carbide 4a having the heavy metal concentration lowered by being washed in the washing water tank 6 is taken out from the washing water tank 6 and dehydrated in the dehydrating device 11, and then transferred to the drying device 12 to be dried (hydrated water). Rate up to about 20%).

  Next, as described above, when the carbide 4a having a reduced heavy metal concentration is dried, the paper 14 is supplied from the paper supply unit 13 to be put into the mixer 17 to produce the solid fuel of the present invention. Then, the waste plastic 16 supplied from the waste plastic supply unit 15 is supplied to the mixer 17, and the paper 14 and the waste plastic 16 are mixed with the carbide 4a at a required mixing ratio. In this case, it is assumed that the paper 14 supplied from the paper supply unit 13 has been crushed in advance by a crusher and the dirt has been removed in advance. Similarly, the waste plastic 16 is preliminarily crushed by a crusher and the dirt is removed in advance. Thereby, the carbide 4a and the paper 14 are mixed, and the carbide 4a and the waste plastic 16 are mixed, so that a mixture 18 of the carbide 4a, the paper 14, and the waste plastic 16 is obtained.

  The mixture 18 is guided to a molding machine 19 and compressed, and then formed into a molded product 20 having a required size. When an extrusion molding machine is used as the molding machine 19, the mixture 18 is extruded into a required shape while being compressed with a required pressing force.

  The molded product 20 molded into a required shape by the molding machine 19 is transferred to a curing conveyor 21 as a device for cooling and curing. As a result, a solid fuel 25 in which the general waste carbide 4a, the paper 14, and the waste plastic 16 are mixed is obtained.

  When the solid fuel 25 is manufactured as described above, fuels having different calories are obtained. By mixing waste plastic 16 with a high calorific value as industrial waste, the calorific value of the carbide 4a itself can be adjusted and used as a high calorie fuel, and the mixing ratio of the waste plastic 16 and the like to the carbide 4a is changed. By this, what has a calorific value equivalent to coal can be obtained from the carbide of general waste, and at the same time, it can be used as a fuel by the carbide 4a having a low heavy metal concentration. Thereby, when the fuel 25 obtained by the present invention is used as a fuel and burned, the heavy metal concentration of the incinerated ash can be reduced and the elution can be reduced.

  Next, FIG. 2 shows another embodiment of the present invention. In a configuration similar to that shown in FIG. 1, steam generation is performed so that steam 24 is used to dry carbide 4a having a low heavy metal concentration. In place of the configuration in which the heat generator 22 is installed, a hot air generator 26 that generates the hot air of a required temperature by burning the pyrolysis gas 3 is installed, and the hot air generator 26 is connected to the hot air line 27. The hot air 28 can be guided to the drying device 12 through the hot air line 27. Other configurations are the same as those shown in FIG. 1, and the same components are denoted by the same reference numerals.

  In this embodiment, similarly to the case of the steam 24 in the above embodiment, the carbide 4a can be heated and dried, and the same effect as that shown in FIG. 1 can be obtained. .

  In each of the above embodiments, when the produced solid fuel 25 is used for incineration, it is incinerated in the unlikely event that it is not reduced in concentration by washing with a carbide having a high heavy metal content depending on the type of waste. When the heavy metal concentration in the ash may be high, the pH adjusting agent supply unit 29 is connected to the water supply line 8 to the washing water tank 6 as shown by a two-dot chain line in FIG. The agent 30 may be mixed with water so that the pH of the washing water can be adjusted.

  If the pH of the washing water is adjusted to, for example, the pH of about 12, the heavy metal contained in the carbide 4 can be actively eluted into the washing water. This makes it possible to reduce the concentration of heavy metals even for carbides containing a relatively large amount of heavy metals such as those of municipal waste.

  The present invention is not limited to the above embodiment. For example, in the embodiment shown in FIGS. 1 and 2, the paper 14 and the waste plastic 16 are mixed with the carbide 4a having a low concentration of heavy metal. However, it is possible to use only waste plastic or paper alone, and without mixing the paper 14 and waste plastic 16 with the carbide 4a having a low concentration of heavy metals, the carbide 4a is molded alone after drying and solidified. You may make it make it fuel. In this case, the mixer 17 shown in FIGS. 1 and 2 may be omitted, and the carbide 4a may be supplied directly to the molding machine 19. Furthermore, in the above-described embodiment, when the paper 14 is mixed with the carbide 4a, biomass containing fibers such as grass and wood in addition to the paper may be mixed. Of course, various changes can be made without departing from the scope.

It is a schematic diagram showing one embodiment of a method for producing fuel from municipal solid waste such as municipal waste. It is a schematic diagram which shows the other form of implementation of this invention. It is a schematic diagram which shows the method of manufacturing a solid fuel from the general waste, waste plastic, and waste paper which were proposed conventionally. It is a cutting | disconnection side view which shows the outline of the molding machine in FIG.

Explanation of symbols

1 General waste (waste)
2 Pyrolysis furnace 4,4a Carbide 5 Pulverizer 6 Washing water tank (cleaning device)
7 Water 11 Dehydrator 12 Dryer 14 Paper 16 Waste plastic 17 Mixer 19 Molding machine 25 Solid fuel (fuel)
30 pH adjuster

Claims (6)

  The carbide obtained by pyrolyzing the waste such as municipal waste is washed with water to elute heavy metals contained in the carbide into water, and then dehydrated and dried the carbides with reduced heavy metal concentration, and then A method for producing fuel from waste such as municipal waste, wherein the dried carbide is mixed with paper and / or waste plastic and then molded into a required shape to produce solid fuel.   Carbide obtained by pyrolyzing waste such as municipal waste is pulverized and washed with water to elute heavy metals contained in the carbide into water, and then dehydrated carbides with reduced heavy metal concentration A method for producing fuel from waste such as municipal waste, comprising drying and then mixing paper and / or waste plastic with the dried carbide and then molding the solid into a required shape. .   The method for producing fuel from waste such as municipal waste according to claim 1 or 2, wherein the carbide is washed by adjusting the pH of the washing water.   A cleaning device configured to wash the carbide with water downstream of a line for taking out the carbide from a pyrolysis furnace configured to thermally decompose waste such as municipal waste to generate pyrolysis gas and carbide; An apparatus for dehydrating and drying the washed carbide, and further, a mixer for generating a mixture of the dried carbide and paper and / or waste plastic on the downstream side of the drying apparatus, and the mixer A fuel from waste such as municipal waste, comprising a molding machine for molding the mixture into a molded product having a required shape and a device for cooling and curing the molded product on the downstream side Manufacturing equipment.   A pulverizer for finely pulverizing the above-mentioned carbides on the downstream side of the line for taking out the carbides from a pyrolysis furnace in which waste such as municipal waste is pyrolyzed to generate pyrolysis gas and carbides, A washing device configured to wash the pulverized carbide with water, and a device for dehydrating and drying the washed carbide, and further, on the downstream side of the drying device, the dried carbide and paper, And / or a mixer for generating a mixture with waste plastic, a molding machine for forming the mixture into a molded product having a required shape, and a device for cooling and curing the molded product on the downstream side of the mixer. An apparatus for producing fuel from waste such as municipal waste, characterized by having a configuration.   The apparatus for producing fuel from waste such as municipal waste according to claim 4 or 5, wherein the pH of water supplied to the cleaning apparatus can be adjusted.

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