JP2001354982A - Fuel for manufacturing cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel for cement which has an excellent combustibility and a stably high heat value compared to coals which have been conventionally used as solid fuels for cement. SOLUTION: The fuel for cement comprises a crushed powder of a residue obtained by heating plastics containing a chlorine-containing plastic under a condition wherein the chlorine-containing plastic is thermally decomposed. A fuel adjusted to have a volatile content of from 60 to 95 wt.% is especially preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel fuel for cement production. Specifically, it is made of carbide powder obtained by heat-treating plastics containing chlorine-containing plastics, and has superior flammability and high calorific value compared to coal that has been conventionally used as a solid fuel for cement.
Further, the present invention provides a cement fuel having a stable calorific value.

[0002]

2. Description of the Related Art Hitherto, most of plastic waste has been disposed of by dumping into a landfill or incineration by an incinerator.

However, in recent years, the recycling of resources has been advanced, and attempts have been made to reuse the plastic waste as fuel.

For example, thick molded articles such as plastic cases of electric appliances are crushed into chips, and thin molded articles such as plastic films and plastic sheets are cut into flakes, a part is melted, or a binder is formed. It is reduced in volume and solidified into chips to be used as a fuel for cement.

However, when the plastic waste contains chlorine-containing plastic, a large amount of chlorine accumulates in a cement manufacturing apparatus, particularly in a kiln, due to combustion, and not only the obtained cement product but also a problem such as occurrence of coaching in the apparatus. Occurs.

[0006] Further, there are various kinds of plastics, and the respective calorific values are different. Since waste plastics are generally discharged as a mixture of various types of plastics, the average calorific value is not constant, but fluctuates according to the percentage of the type of waste plastics mixed in . For this reason, it is impossible to increase the fuel replacement ratio by waste plastic without limit while maintaining the operation stability of the cement kiln.

[0007] Waste plastics come in various forms.
Since it is discharged in a form, it needs pretreatment such as crushing or solidifying to an appropriate size to be used as a fuel substitute for cement production, but its burning rate is greatly affected by the size .

[0008] Therefore, in order to increase the fuel cost as much as possible, it is necessary to pretreat waste plastic to an appropriate size in accordance with the combustion conditions at the fuel combustion site in the cement production facility. In particular, a large amount of waste plastic is produced in a calciner whose combustion conditions are inferior to combustion in a cement kiln with favorable conditions such as high combustion temperature, high oxygen concentration, long residence time, etc. In order to burn, it is necessary to crush the size to 5 mm or less, preferably 1 mm or less.

However, since a large amount of energy is required for pretreatment such as crushing and solidification of waste plastics, when pretreating waste plastics to such a size, the cost increases and the economy increases. There was a problem of lack of sexuality, and it was difficult to respond realistically.

[0010] For the above reasons, there is a limit to increasing the substitution rate of waste plastic as a substitute for the main fuel for cement production without limit.

On the other hand, coal is used as a solid fuel for cement production, and the volatile matter content of the coal is 20 to 3%.
It is 0%, and in order to burn it efficiently, it is necessary to pulverize it, and a great amount of energy is required for the pulverizing step. In particular, when coal is used as a fuel for a calciner having a low oxygen concentration and a cement raw material at a low temperature, further pulverization technology has been required.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel for cement which utilizes plastic waste, has superior flammability and higher calorific value than coal, and shows a stable calorific value. To provide.

[0013]

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 residue obtained by heat-treating plastics containing chlorine-containing plastics under specified conditions has been obtained. The present invention has been found to be easy to crush, and that crushed powder obtained by crushing can satisfy all the above requirements as a fuel for cement.

That is, the present invention relates to a fuel for cement production, comprising a crushed powder of a residue obtained by heat-treating plastics containing chlorine-containing plastics under the conditions of thermal decomposition of the chlorine-containing plastics. is there.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, plastics used as raw materials are not particularly limited as long as they contain chlorine-containing plastics. For example, waste plastics separated and recovered from industrial waste, municipal waste, and the like as necessary are preferably used.

Examples of the chlorine-containing plastic include plastics such as polyvinyl chloride and polyvinylidene chloride. Further, as plastics other than the chlorine-containing plastic, polypropylene, polybutene-1,
And thermoplastic resins such as polyolefins such as polyethylene.

The fuel for cement production of the present invention comprises a crushed powder of a residue obtained by heat-treating plastics containing the above-mentioned chlorine-containing plastic under the conditions of pyrolysis of the chlorine-containing plastic.

In the heat treatment of the above-mentioned plastics, known thermal decomposition conditions for chlorine-containing plastics are employed without any particular limitation. That is, generally, the plastics are heat-treated in a non-oxidizing atmosphere at a temperature of 300 to 450 ° C, preferably 350 to 400 ° C. Since the heat treatment time varies somewhat depending on the type, content, heat treatment temperature, etc. of the chlorine-containing plastic, it is determined by conducting experiments in advance to investigate the time during which the chlorine-containing plastic is sufficiently decomposed, dechlorinated, and carbonized. do it. Usually, such a heat treatment time is 10 to 60 minutes.

The degree of the above-mentioned dechlorination is desirably adjusted so that the chlorine content in the residue is 1% by weight or less, preferably 0.5% by weight or less.

As the apparatus used for the heat treatment, a known apparatus can be used without any particular limitation. For example,
A rotary kiln type heating furnace of a type in which heating is performed while rolling plastics supplied inside while rotating a cylindrical object (kiln) having a heating surface formed on the peripheral wall or inside, a tube having a heating surface formed on the peripheral wall A typical example is an extruder-type heating furnace of a type in which a screw is provided in a shaped material and heating is performed while moving plastics by the screw.

[0021] In the present invention, the residue obtained by the above heat treatment is roughly the one in which carbides generated by the decomposition of chlorine-containing plastics and other plastics are intact or in a state in which a part of a molecular chain is cut to reduce the molecular weight. And a volatile component composed of the same.

[0022] The carbides in the residue improve the friability thereof, while the volatile components are characterized by a high calorific value and an excellent flammability as a fuel for cement production (hereinafter, both of these properties are combined. Excellent combustion characteristics).

Therefore, the cement-producing fuel of the present invention containing the above-mentioned carbides and volatile matter has the above-mentioned components, so that even if it is a crushed powder having a size larger than the crushed size of coal powder, it can be mixed with the coal. Achieve equal or better combustion characteristics.

As described above, the fuel for cement production of the present invention comprises a crushed powder of a residue obtained by heat-treating plastics containing chlorine-containing plastics under the conditions of pyrolysis of the chlorine-containing plastics. It is sufficient that the proportion of volatile components present in the crushed powder is 60% by weight or more, preferably 70% by weight, in order to realize more excellent combustion characteristics.
Preferably it is present in a weight percent or higher.

Further, if the proportion of the volatile component is too large, the friability is lowered. Therefore, it is preferable to adjust the content of the volatile component to be in the range of 95% by weight or less.

On the other hand, considering the friability, the proportion of the carbide is preferably adjusted to be at least 3% by weight, preferably at least 5% by weight. However, the carbide is
In order to reduce the flammability of the fuel for cement production, it is preferable to limit the amount to 30% by weight or less, especially 20% by weight or less.

Incidentally, the ratio of the volatile matter and the carbide is determined by JI
This is a value obtained according to SM8812.

The volatile matter and the carbide (fixed carbon)
Means the ratio of the residue in the crushed powder, and when an inorganic substance is present in the residue, such an amount is also included in the reference residue weight.

However, in the fuel for cement production of the present invention, since the presence of a large amount of inorganic substance causes a decrease in flammability, the amount is 10% by weight or less, preferably 5% by weight or less.
More preferably, it is desirable to suppress the content to 3% by weight or less.

In the present invention, the proportions of the volatile components and the carbides (fixed carbon) can be controlled by appropriately adjusting the proportions of the chlorine-containing plastics and the types and proportions of the other plastics.

In the present invention, the method for crushing the residue is as follows:
The method is not particularly limited, and a known method is used without any particular limitation. However, since such a residue contains a large amount of volatile matter and has a risk of causing a dust explosion in the process of forming a powder, a crushing method by grinding or a shearing method is used. A crushing method is suitably employed. As a device used in the crushing method, a known device is used without any particular limitation. For example, a mortar-type crusher, a single-shaft or twin-shaft shear-type crusher and the like can be mentioned.

In the present invention, the particle size of the crushed powder is not particularly limited, but is determined from the range where the average particle size is several μm to 10 mm, particularly 100 μm to 1 mm, depending on the location to be supplied in the cement production process. It is desirable to do.

The cement-producing fuel of the present invention can be supplied as fuel to any of the fuel supply points in the cement production process. For example, in the main burner to which the coal powder is supplied, it can be replaced with the coal powder at an arbitrary ratio.

However, the most effective use of the fuel for cement production of the present invention is in the form of use as a calciner fuel in the cement production process. That is, in the calcining furnace, as described above, the fuel is required to have a low oxygen concentration and a low temperature, and to be burned in a short stagnation.
It is necessary to crush to the following particle size. On the other hand, the fuel for cement production of the present invention, which contains a large amount of volatile matter relative to coal, has an average particle diameter of 1
Even if it is supplied with a particle size of about 00 μm to several mm, it is possible to sufficiently calcine the cement raw material.

[0035]

As will be understood from the above description, the fuel for producing cement of the present invention can exhibit superior flammability as compared with coal conventionally used as a solid fuel for cement. In addition to having good handling properties similar to coal powder, while using plastic waste containing chlorine-containing plastic,
It is possible to provide a fuel for cement production that has higher performance than coal powder.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to the following Examples.
Examples are shown, but the present invention is not limited to these examples.

In the examples and comparative examples, various test results show the results obtained by the following methods.

(1) Measurement of Volatile Content and Ratio of Carbide (Fixed Carbon) Measured according to JIS M8812.

(2) Measurement of chlorine content The chlorine content was measured according to JIS Z7302-6.

(3) Measurement of average particle size of crushed powder The measurement was performed using a laser diffraction type Cirrus particle sizer (Type 715; manufactured by Seishin Enterprise Co., Ltd.).

(4) Fragility of residue Measured according to JIS M8801.

(5) Measurement of calorific value of crushed powder According to JIS M8814, a bomb type calorimeter (CA-4)
PJ; manufactured by Shimadzu Corporation).

(6) Measurement of flammability of crushed powder A sample having a particle diameter of about 5 mm was placed in an electric furnace at 900 ° C, and the time from ignition to completion of combustion was measured.

Examples 1-3 Polyvinyl chloride and polypropylene were mixed while changing the ratio of the polyvinyl chloride to obtain various compositions.

The above composition was supplied to an extruder-type heating furnace,
The furnace was adjusted to have a maximum temperature of 350 ° C., and after a heat treatment for 20 minutes, a residue mass was obtained.

The residue mass obtained was crushed by a mortar crusher to obtain a crushed powder having an average particle diameter shown in Table 1.

Table 1 shows the test results of the crushed powders obtained as described above from the various compositions.

Table 1 shows the calciner outlet gas temperature and the kiln inlet raw material calcining rate when the crushed powders of Examples 1 to 3 were supplied as fuel to the calciner in the cement production process.
As will be better understood from this, the crushed powder of the present invention is:
Even if the average particle size is 100 μm or more, the combustion characteristics are the same as those in the case of using pulverized coal having an average particle size of about 40 μm (Reference Example 1). It was possible to calcine the cement raw material without lowering the raw material calcining rate.

Further, from the above results, even when part or all of the coal used for the main burner of the kiln is replaced with the crushed powder of the present invention, excellent combustion characteristics are exhibited more than when coal is used. You can see that.

Comparative Example 1 A crushed powder was obtained in the same manner as in Example 1 except that polyvinyl chloride was used alone.

The measurement and test results of the obtained crushed powder are shown in Table 1.

Table 1 shows the calciner outlet gas temperature and the kiln inlet raw material calcining rate when the above crushed powder was supplied as a fuel to the calciner in the cement production process.

[0053]

[Table 1]

Claims (5)

[Claims] 1. A fuel for cement production, comprising a crushed powder of a residue obtained by heat-treating plastics containing chlorine-containing plastics under the conditions of thermal decomposition of said chlorine-containing plastics. 2. The fuel for cement production according to claim 1, which contains 60 to 95% by weight of volatile matter. 3. The fuel for cement production according to claim 1, wherein the chlorine content is 1% by weight or less. 4. The fuel for cement production according to claim 1, which is a fuel for a calciner in a cement production process. 5. The fuel for producing cement according to claim 1, wherein the average particle diameter is 100 μm to 10 mm.