JP2000096066A - Production of fuel having low chlorine content - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a fuel having remarkably decreased chlorine content to solve the problems such as the corrosion of a furnace burning the fuel by treating a carbonized material produced by the thermal decomposition of a chlorine-containing plastic. SOLUTION: The objective fuel having low chlorine content can be produced by the water-washing of a carbonized material obtained by the thermal decomposition of a chlorinecontaining plastic. The chlorine-containing plastic to be used as a starting material preferably contains >=1 wt.% of a metal-containing additive. Preferably, the water-washing of the carbonized material is carried out at >=50 deg.C after crushing the material to an average particle diameter of 10-1,200 μm. The chlorine concentration of the carbonized material after water- washing treatment is preferably <=1.2 wt.%. The troubles such as the lowering of the decomposition ratio caused by the agglomeration of the chlorine- containing plastic material can be prevented by mixing at least a part of the carbonized material produced by the thermal decomposition to the chlorine- containing plastic and carrying out the thermal decomposition of the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for producing a low chlorine fuel from a carbide (residue of dehydrochlorination) obtained by pyrolysis of a chlorine-containing plastic such as vinyl chloride, and a method obtained by the method. The present invention relates to a novel method for producing cement using a low chlorine fuel as part of a fuel for producing cement.

[0002]

2. Description of the Related Art In recent years, a large amount of waste containing chlorine-containing plastics such as polyvinyl chloride has been discharged, and the amount of waste has been increasing steadily. Most of these wastes are simply incinerated or directly landfilled. It is presumed that the amount of processing of chlorine-containing plastics such as polyvinyl chloride contained in such wastes is also large.

[0003] When these plastics containing chlorine are simply incinerated, harmful substances such as hydrogen chloride and dioxin generated during incineration may be directly released into the atmosphere. On the other hand, simple landfill is a problem in terms of securing land and reusing resources.

In recent years, these wastes have been pyrolyzed,
The active ingredient as fuel in it is collected as carbide,
Reuse is being considered.

[0005]

However, the carbide obtained by the above method was considered to be substantially free of chlorine, but the waste chlorine-containing plastic after being used as a material for various products. When the pyrolysis is carried out by actually using, the resulting carbide is, surprisingly,
It contains a high concentration of chlorine and has problems such as corrosion of the furnace supplied when used as a fuel, or a problem such as deterioration of cement quality when the carbide is used as a fuel for producing cement. Have been confirmed by the present inventors. In particular, when the chlorine-containing plastic contains a metal element as an additive such as a metal-containing stabilizer or an inorganic filler, the above-described problem is remarkably exhibited.

Accordingly, it is an object of the present invention to provide a method for obtaining a low-chlorine fuel in which the problems due to chlorine are reduced from carbides obtained by pyrolysis of chlorine-containing plastics.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the chlorine content in the carbide obtained by pyrolyzing a chlorine-containing plastic has a considerable proportion. It has been found that the metal exists in the form of a metal element and a salt, and by washing it with water, it is possible to extremely effectively remove chlorine from the carbide, thereby completing the present invention.

[0008] That is, the present invention is a method for producing a low chlorine fuel, which comprises washing a carbide obtained by pyrolyzing a chlorine-containing plastic with water.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as the chlorine-containing plastic to be decomposed, a known chlorine-containing plastic is used without any particular limitation. When the chlorine-containing plastic has a large volume, a small piece obtained by pulverization, cutting or the like is preferably used.

Specific examples of the chlorine-containing plastic include chlorinated polyolefins such as polyvinyl chloride, polyvinylidene chloride, and chlorinated polyethylene.
The present invention is particularly preferably used for polyvinyl chloride among these chlorine-containing plastics.

The shape and size of the chlorine-containing plastic are not particularly limited. For example, as the shape, in addition to the irregular shape obtained by pulverization, spherical, cylindrical, prismatic,
Any shape such as a cube and a flat shape is used. In addition to these shapes, as the chlorine-containing plastic, a bulky one such as a film, which is formed by compression molding, can be used.

Further, the size of the chlorine-containing plastic is
In general, irregular shape, spherical, cylindrical, prismatic, when relatively thick like a cube, the longest diameter that is the maximum length to be measured is 1 to 30 mm, preferably 2 to 5 mm, the thickness is 30 mm In the case of the following flat shape, those having a major axis of 200 mm or less, preferably 100 mm or less are suitably used.

In the present invention, as the chlorine-containing plastic, a chlorine-containing plastic after being used as a material for various products, that is, a waste chlorine-containing plastic is preferably used. That is, these waste chlorine-containing plastics contain at least one metal-containing stabilizer, an inorganic filler, and a metal-containing additive such as a plasticizer in order to satisfy physical properties required as a material of the product. As a result, the chlorine content in the carbide obtained by the thermal decomposition described later increases. According to our confirmation, such metals form chlorides in the carbide, which causes an increase in the chlorine concentration in the carbide.

By applying the present invention to a carbide obtained by thermally decomposing such waste chlorine-containing plastic, the effect of reducing the concentration of chlorine contained therein is remarkably exhibited.

Of course, virgin chlorine-containing plastics that do not contain these additives are also an object of the present invention, and in this case, the concentration of chlorine contained in the obtained carbide can be further reduced.

In the present invention, known conditions for thermal decomposition of chlorine-containing plastics are employed without particular limitation.
For example, in the case of polyvinyl chloride, a method of heating at a temperature of 250 to 350 ° C. in an atmosphere of an inert gas such as nitrogen gas is generally adopted. Further, the decomposition reaction can be performed using a known thermal decomposition furnace. For example, furnaces such as a rotary kiln, a fluidized-bed furnace, and a vertical furnace are exemplified. Among them, a rotary kiln is preferably used in terms of the stability and efficiency of the thermal decomposition reaction.

In the pyrolysis of the chlorine-containing plastic of the present invention, when the chlorine-containing plastic is supplied to a pyrolysis furnace, a powder for preventing sticking which does not adversely affect the pyrolysis reaction or the use of the resulting carbide as a fuel. It is preferable to perform thermal decomposition by supplying the mixture in a state of being mixed with the body.

That is, in general, the thermal decomposition of chlorine-containing plastics is carried out by heating to the decomposition temperature in a decomposition furnace such as a rotary kiln. Not only does the decomposition rate drop significantly due to the adhesion of the plastics contained, it also adheres to the inner wall of the decomposition furnace, which may lead to a decrease in thermal conductivity and a decrease in yield. Such a phenomenon can be effectively prevented by adding the mixture to the pyrolysis furnace in a state of being mixed with the powder for preventing adhesion.

Examples of the anti-adhesion powder include coke powder, carbide powder obtained by pyrolysis of chlorine-containing plastic, etc., which can be used as a fuel, and fuel made of the carbide obtained according to the present invention. When used, cement clinker powder or the like is used.

Among them, the above-mentioned embodiment in which carbide powder is used as an anti-adhesion powder has a small specific gravity and a high adhesion activity, so that a small amount of addition exerts a sufficient effect, and the thermal decomposition of chlorine-containing plastics is continuously performed. In the case of performing, by temporarily using the powder that can prevent sticking and adhesion at the start, after that, without preparing additional additives, by crushing and using a part of the obtained carbide This is preferable because it can cover this and can very economically process chlorine-containing plastics.

In the above embodiment, the use of the carbide obtained by water washing described below as the carbide powder can reduce the amount of chlorine accumulated in the pyrolysis furnace by repeating the recycling of the carbide, and can reduce the amount of chlorine-containing plastic. This is preferable because the thermal decomposition efficiency of the compound can be further improved.

In the above embodiment, the powder mixed with the chlorine-containing plastic at the time of starting is not particularly limited as long as the powder can prevent the chlorine-containing plastic from sticking and sticking. For example, separately manufactured carbide powder, cement clinker powder, coke powder, and the like are suitably used. Among the above powders, carbide powder and coke powder containing no metal element are particularly suitable.

In a preferred embodiment using the above-mentioned powder for preventing adhesion, the powder has an average particle diameter of 0.01 to 2 mm,
It is preferably 0.02 to 1 mm, and can be obtained by crushing with a known crusher.

The mixing amount of the above-mentioned powder for preventing adhesion to the chlorine-containing plastic varies depending on the size of the particles and the like, and thus cannot be unconditionally limited. In general, the mixing amount is 100 parts by weight of the chlorine-containing plastic. 3 ~
300 parts by weight, preferably 5 to 200 parts by weight, more preferably 5 to 50 parts by weight. If the addition amount is less than 3 parts by weight, it is difficult to exhibit a sufficient effect for preventing the sticking and adhesion. Conversely, if the addition amount is more than the above range, the effect level out and is economically disadvantageous. Becomes

Further, the mixing of the chlorine-containing plastic and the powder for preventing sticking is preferably carried out before being subjected to the thermal decomposition, and particularly preferably, the preliminary mixing is carried out before being subjected to the thermal decomposition furnace. Mixing is effective. The preliminary mixing can be carried out using a known dry mixer such as a mill, a mixer equipped with a stirring blade. In this case, it is preferable that the surface of the chlorine-containing plastic is slightly melted, for example, about 100 to 2 in the case of a piece of polyvinyl chloride.
It is preferable to carry out the above-mentioned mixing at a temperature of 00 ° C., since the powder for preventing adhesion can be securely attached to the surface of the chlorine-containing plastic.

In a preferred embodiment using the above-mentioned powder for preventing sticking, it is preferable that the chlorine-containing plastic and the powder for preventing sticking are mixed in advance and supplied to a pyrolysis furnace. In the present invention, the chlorine-containing plastic is thermally decomposed by staying in a pyrolysis furnace for a required time to be decomposed into carbide and hydrogen chloride.

The processing time of the chlorine-containing plastic in the above-mentioned pyrolysis furnace varies somewhat depending on the set temperature of the pyrolysis, the size of the chlorine-containing plastic, and the like.
It is 5 hours, preferably about 10 to 60 minutes.

The most important feature of the present invention resides in that a low chlorine fuel is obtained by washing the carbide obtained by the thermal decomposition of the chlorine-containing plastic described above with water.

As mentioned above, chlorine-containing plastics,
In particular, the present inventors have confirmed that a surprisingly large amount of chlorine remains in the carbide obtained by thermal decomposition of the waste chlorine-containing plastic. In particular, when the chlorine-containing plastic contains 1% by weight or more of the metal-containing additive, the amount of chlorine remaining in the obtained carbide is extremely problematic.

The present inventors have made various studies on the removal of chlorine, and as a result, surprisingly, chlorine contained in the carbide can be removed very effectively by a simple operation of washing with water. I found something.

In the present invention, the method of washing with water is not particularly limited, but preferred embodiments include the following embodiments.

For example, the temperature at the time of washing with water is preferably adjusted to a temperature of 50 ° C. or higher, particularly 70 to 100 ° C.
That is, by performing the water washing at such a temperature, the efficiency of removing chlorine from the carbide can be further drastically improved. In addition, although it is possible to carry out the washing at a temperature of 100 ° C. or higher, it is necessary to carry out the washing under pressure, which is not economical.

The method of adjusting the temperature at the time of water washing to the above range is as follows. In the case of washing a carbide cooled to room temperature, washing is performed using warm water heated so that the temperature at the time of washing becomes the above temperature. If the carbide has a certain temperature due to heat generated by the following pulverization or residual heat during thermal decomposition, use water having a temperature lower than the above temperature range. What is necessary is just to wash with water.

In addition, at the time of washing with water, it is preferable to previously grind the carbide to an appropriate particle size in order to improve the efficiency of removing chlorine by washing with water. Considering the ease of draining after washing with water, the average degree of particle size is 12
It is preferable to perform the process so as to be 00 to 10 μm, preferably 800 to 100 μm.

The above-mentioned pulverization can be carried out using a known pulverizer. For example, a pulverizer such as a hard crusher or an impact shear mill is preferably used.

When the preferred particle size for use as fuel is smaller than the above-mentioned range of the average particle size, it is also possible to carry out pulverization again after washing with water.

In the present invention, the method of contacting the carbide with water is employed without particular limitation in the water washing method. For example, a method in which a powdery material of carbide is deposited on a pit having a drainage mechanism such as a wire mesh or a groove at a lower portion, and water is sprayed from the upper portion of the deposited carbide, or the carbide is suspended in water in a washing tank with a stirrer. After turbidity, a method of filtering and removing water is common. For the filtration, a known filtration device such as a filter press or a centrifuge is industrially employed.

The above-mentioned water washing preferably reduces chlorine in the carbide as much as possible. However, for use as a fuel, the chlorine concentration of the carbide is 1.2% by weight or less, preferably 0.5% by weight or less. % By weight or less, particularly preferably 2000 p
pm or less.

The carbide obtained by the above-mentioned water washing can be used as various fuels as a low-chlorine fuel after drying if necessary.

For example, by supplying the low-chlorine fuel as a part of fuel from a firing fuel supply unit for firing a cement raw material in a cement manufacturing process, it is possible to treat the entire amount of the fuel. An excellent process that does not adversely affect the quality of the resulting cement clinker can be realized.

In the above process, the low-chlorine fuel is supplied by mixing with the fuel supplied to the main burner present in the fuel supply section provided at the kiln end of the kiln for firing the cement, or is separately provided in the vicinity of the main burner. It is used as a part of fuel by providing a burner and supplying it by airflow.

When the above low chlorine fuel is used as a fuel for cement, it is desirable to carry out grinding if necessary. When coal is used as the fuel, it is more preferable that the low-chlorine fuel is pulverized together with the coal and supplied as fuel together with the coal.

Although the amount of the low chlorine fuel used does not affect the quality of the obtained cement clinker even if it is slightly increased or decreased, it is generally 90% or less, preferably 70% or less of the main fuel. It is desirable to adjust so as to be preferably 1 to 50%.

Although the amount of chlorine-containing plastic used depends on the amount of chlorine-containing plastic used, the amount of chlorine-containing plastic in the waste plastic in one area where the cement production process exists is insignificant with respect to the main fuel in the cement production process. Usually, the whole amount can be used as a part of the fuel, and a closed processing system can be constructed.

Further, since the chlorine concentration in the low chlorine fuel of the present invention is extremely low, when it is burned in a cement kiln, it is usually used to prevent the accumulation of chlorine. The operation of extracting a part of the atmosphere gas from the kiln bottom of the kiln can be performed sufficiently stably under ordinary extraction conditions of, for example, about 0.1 to several percent.

On the other hand, the gas by-produced in the thermal decomposition of the chlorine-containing plastic in the present invention is mainly hydrogen chloride gas. The gas can be produced by a known method, for example, adsorption with activated carbon, or an aqueous alkaline solution represented by an aqueous solution of caustic soda. It can be excluded by absorbing it. Of course,
Purify without exception and use in other processes, for example, preparation of aqueous hydrochloric acid solution, production method of ethylene dichloride by oxychlorination reaction of ethylene and hydrochloric acid, production of vinyl chloride monomer by gas phase reaction with acetylene Is also possible.

In particular, when chlorine is finally used in chlorine-containing plastics such as polyvinyl chloride as in the production of ethylene dichloride by oxychlorination, a recycling system for chlorine-containing plastics can be constructed in a broad sense. can do.

[0048]

As can be understood from the above description, according to the method of the present invention, a low-chlorine fuel having a significantly reduced chlorine concentration can be obtained by treating a carbide obtained by pyrolysis of a chlorine-containing plastic. , Can be obtained in a simple manner. In particular, when waste chlorine-containing plastic is used as chlorine-containing plastic, the effect of the present invention is remarkable, and the industrial value in this case is extremely large.

The carbide obtained by the method of the present invention is useful as various fuels. In particular, by using the above-mentioned carbide as a part of the fuel for calcining the cement raw material in the cement production process, the chlorine-containing plastic can be treated extremely efficiently without affecting the quality of the obtained cement. It is possible to realize a closed processing system that can be used, and it can be said that its industrial significance is extremely large in the processing of chlorine-containing plastics such as vinyl chloride pieces.

[0050]

EXAMPLES In order to more specifically describe the present invention,
Examples are shown, but the present invention is not limited to these examples.

Examples 1 to 7 About 4.7% by weight of a stabilizer and a Ca-based filler 1 were added to a 20A hard glass reaction tube (inner diameter: 20 mmφ) as a metal-containing additive.
An amorphous hard polyvinyl chloride piece (PVC piece) pulverized to a long diameter of 2 to 3 mm containing 5% by weight and a carbide powder having an average particle diameter of 0.5 mm obtained by pyrolyzing the polyvinyl chloride piece. Was mixed in the proportions shown in Table 1 and premixed, and then the reaction tube was externally heated to a temperature shown in Table 1 in a ring electric furnace to perform thermal decomposition. While rotating the reaction tube twice per minute,
The treatment was performed for the treatment time shown in Table 1 to complete the thermal decomposition.

The carbide obtained by the thermal decomposition was pulverized to an average particle size of about 400 μm.

On the other hand, the temperature-controlled water is stored in the glass container, and the crushed carbide is washed in the glass container at each water temperature and washing time shown in Table 1 while stirring with a stirrer. Filtration was performed to separate water and carbide, and the water in the carbide was evaporated and dried by a drier to obtain a low chlorine fuel composed of carbide from which chlorine was removed.

The obtained low chlorine fuel was analyzed for its residual chlorine content (% by weight; hereinafter, simply expressed as%) by fluorescent X-ray analysis. The results are also shown in Table 1. .

In Examples 1 to 7, the carbide powder to be added to the PVC pieces was obtained by pulverizing a carbide produced by thermally decomposing polyvinyl chloride in an electric furnace at 350 ° C. under a nitrogen atmosphere. did.

[0056]

[Table 1]

Comparative Example 1 A carbide was obtained in the same manner as in Example 1, except that washing was not performed.

The obtained carbide was analyzed for residual chlorine by X-ray fluorescence analysis. As a result, the ratio of residual chlorine in the carbide was 6.20%.

Example 8 A low-chlorine fuel was obtained in the same manner as in Example 1, except that the premixing of the hard polyvinyl chloride pieces and the carbide powder was performed by heating to 120 ° C.

The obtained carbide was analyzed for residual chlorine by fluorescent X-ray analysis. As a result, the ratio of residual chlorine in the carbide was 0.35%.

Example 9 The same apparatus as in Example 1 was scaled up, and a low chlorine fuel made of carbide was produced from the same PVC piece under the same conditions as in Example 1. Here, draining after washing was performed using a centrifuge. The average residual chlorine content in the thus obtained low chlorine fuel carbide was 0.45%.

As a result of producing the cement clinker by using the low chlorine fuel in a proportion corresponding to 10% of the pulverized coal used as a fuel in the cement kiln, the quality of the obtained cement clinker is hardly affected. A cement clinker was obtained.

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[Procedure amendment]

[Submission date] June 11, 1999 (1999.6.1
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

6. The method according to claim 1, wherein the chlorine-containing plastic contains at least 1% by weight of a metal-containing additive.

7. The method of claim 1, wherein the chlorine-containing plastic to obtain a carbide by thermal decomposition in a state where at least a portion of the carbide obtained by pyrolysis was mixed with chlorine-containing plastic.

8. A method for producing cement, wherein the low chlorine fuel obtained by the method according to claim 1 is used as a part of a fuel for cement production.

Claims (7)

[Claims] 1. A method for producing a low chlorine fuel, comprising washing a carbide obtained by pyrolyzing a chlorine-containing plastic with water. 2. The method according to claim 1, wherein the water washing is performed at a temperature of 50 ° C. or higher. 3. The chlorine concentration in the carbide after washing is 1.2.
The method of claim 1, wherein the amount is less than or equal to the weight percent. 4. The method according to claim 1, wherein after crushing the carbide, washing is performed with water. 5. The method according to claim 1, wherein the chlorine-containing plastic contains at least 1% by weight of a metal-containing additive. 6. The method according to claim 1, wherein the carbide is obtained by performing pyrolysis in a state where at least a part of the carbide obtained by pyrolyzing the chlorine-containing plastic is mixed with the chlorine-containing plastic. 7. A method for producing cement, wherein the low-chlorine fuel obtained by the method according to claim 1 is used as a part of fuel for producing cement.