JP2003095712A - Method of manufacturing cement clinker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing cement clinker which easily disposes a large amount combustible wastes in a calcining furnace. SOLUTION: The method of manufacturing the cement clinker while charging the combustible wastes into a cement firing process step comprises charging the combustible wastes K onto a fluidized bed in the lower part of a furnace casing of the fluidized bed calcining furnace 10 installed before a rotary kiln 2 of the cement firing process step. In charging, a raw material supply chute and a fuel oil and air blowoff pipe are utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cement clinker while introducing a combustible waste such as waste plastic into a cement firing process.

[0002]

2. Description of the Related Art The amount of industrial waste generated is increasing year by year. Known disposal methods include landfill processing and incineration processing. However, as it is becoming difficult to secure landfill sites, incineration treatment is drawing attention. Among such industrial waste, combustible waste such as waste plastic generates a sufficient amount of heat when incinerated, and is being used as a fuel for various combustion furnaces in order to effectively utilize the amount of heat generated by the combustion.

For example, as a method of using combustible wastes such as waste plastics as fuel, the crushed products are blown by burning by blowing air from the kiln front part of the rotary kiln of the cement firing equipment into the rotary kiln and blowing it. The technology for reducing the amount of pulverized coal used as the main fuel has long been known.

As examples thereof, those disclosed in JP-A-8-283052 and JP-A-2001-58857 are known. In these conventional techniques, waste plastic (solid matter) is placed on an air flow as a single unit and blown into the rotary kiln from the front of the kiln.As a method of blowing it, another dedicated burner is provided above the main fuel burner. I try to blow from there.

A brief description will be given with reference to FIG. In FIG. 4, 1 is a preheater, 2 is a rotary kiln, 3 is a cooler, and the cement raw material enters the kiln butt portion 2A of the rotary kiln 2 from the preheater 1 and the rotary kiln 2
The cement clinker is calcined while gradually moving to the kiln front part 2B side which is the downstream side, becomes a cement clinker, is cooled by a cooler 3, and is then sent to a finishing step. A main fuel burner 4 for injecting a main fuel such as pulverized coal is provided in the kiln front portion 2B of the rotary kiln 2, and a dedicated burner 5 for injecting a combustible waste such as waste plastic is provided above the main fuel burner 4 separately. Is provided. At the time of operation, the main fuel is blown from the main fuel burner 4 for combustion, and combustible waste such as waste plastic is blown from the dedicated burner 5 for combustion.

[0006]

By the way, in general, it is common to put combustible waste in the rotary kiln 2 as described above, but the amount of the combustible waste required to be disposed of. As the number increased, it became impossible to dispose of it using the rotary kiln 2 alone. Therefore, it has been expected that the combustible waste is thrown into equipment other than the rotary kiln 2 for disposal.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a cement clinker capable of disposing a large amount of combustible waste in a calcining furnace without obstacles.

[0008]

According to a first aspect of the present invention, there is provided a method for producing a cement clinker while introducing a combustible waste into a cement firing step, wherein a flow is provided before a rotary kiln in the cement firing step. It is characterized in that the combustible waste is put into the fluidized bed in the lower part of the furnace of the layer calcining furnace.

When combustible waste is put into the fluidized bed calcining furnace as in the method of the present invention, since the ambient temperature condition inside the calcining furnace is lower than that of the kiln front part of the rotary kiln, unburned components are produced. Although there is a possibility, even if some unburned material comes out of the calcination furnace, it will eventually enter the rotary kiln and gradually move to the front side of the kiln as the rotary kiln rotates. There is no fear of affecting the quality of cement clinker. Also, even if there is a slight change in the manner of combustion, for the same reason, there is no fear of giving any problems to the quality of the cement clinker. Therefore, even if the amount of disposal in the rotary kiln is limited, a large amount of combustible waste can be disposed in the calcining furnace. Of course, the amount of heat generated by the combustion of the combustible waste in the calcining furnace contributes to the saving of fuel such as pulverized coal that is put into the calcining furnace.

In addition, when the meltable combustible waste such as waste plastic is charged into the calcining furnace, there is a problem in which part of the calcining furnace is charged. For example, in the case of waste plastic, since it undergoes gasification and combustion, it is necessary to secure a certain burning time (for example, 4 to 5 seconds for waste plastic having a diameter of 10 mm). From this point, it is most conceivable to blow combustible waste together with the pulverized coal into the calcination furnace from the pulverized coal injection pipe at the bottom of the fluidized bed calcination furnace. There is concern that the nozzle may be blocked by depositing / welding on the base of the layer (fluidizing nozzle, etc.).

On the other hand, in the method of the present invention, since the combustible waste is put on the fluidized bed in the lower part of the furnace body, the combustible waste does not deeply sink due to the floating effect of the fluidized bed raw material. , Combustion progresses while staying in the upper part of the bed for a relatively long time. For this reason, there is no fear of hindering the stability of the fluidized air.

As a concrete charging point, in the invention of claim 2, a combustible waste charging port is formed in the raw material supply chute of the fluidized bed calcining furnace, and the combustible waste is discharged from the charging port into the chute. Added on the flowing cement raw material, thereby
It is characterized in that combustible waste is made to flow into the fluidized bed in the lower part of the furnace together with the cement raw material.

According to the third aspect of the present invention, an inlet for combustible waste is provided on the furnace body wall of the fluidized bed calciner, and the combustible waste is introduced from the inlet to the fluidized bed below the furnace body. It is characterized by doing. Further, in the invention of claim 4, in claim 3, an air outlet is provided adjacent to the lower side of the inlet of the combustible waste provided in the furnace body wall of the fluidized bed calcining furnace, and the blower is provided. It is characterized by dispersing the combustible waste that has been injected into the furnace body by blowing out air from the outlet.

Further, in the invention of claim 5, the combustible air injection pipe of the fluidized bed calcination furnace is provided with an inlet for combustible waste, and the combustible waste is added from this inlet to combustible waste. The feature is that the waste is allowed to flow into the fluidized bed in the lower part of the furnace.

Further, in the invention of claim 6, as the combustible waste in the method of any one of claims 1 to 5, a thing mainly composed of granular or flaky crushed waste plastics is put on the fluidized bed. It is characterized by doing.

Further, the invention of claim 7 uses a granular or flaky waste plastic as the combustible waste in the method of any one of claims 1 to 5, and the slurry is mixed with liquid waste in advance. It is characterized in that the mixture is put into the fluidized bed in the lower part of the furnace body of the fluidized bed calciner.

In particular, as in the invention of claim 7, solid slurry is produced by introducing a slurry-like mixture of granular combustible waste (solid waste) and liquid waste onto the fluidized bed of the calciner. Liquid waste can be transported together using a general-purpose slurry pump and disposed of at the same time.
This can be realized, and the device configuration can be simplified. Further, since the solid waste can be transported as a slurry, it is not necessary to crush the solid waste to be finer than necessary and have a uniform particle size for pneumatic transportation, and the crushing load can be reduced. Furthermore, since the granular combustible waste and the liquid waste are mixed and put into the calcining furnace, the combustibility of the liquid waste can be improved compared to the case where the liquid waste such as waste oil is disposed of alone. You can

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of cement burning equipment for carrying out the treatment method of the present invention.

In the figure, 1 is a preheater, 2 is a rotary kiln, 3 is a cooler, 10 is a fluidized bed calcination furnace, and the cement raw material is directly from the preheater 1 or partly through the calcination furnace 10. After entering the kiln bottom of the rotary kiln 2 and gradually moving inside the rotary kiln 2 to the kiln front side which is the downstream side, the kiln is fired into a clinker, cooled by a cooler 3, and then sent to a finishing process.
A main fuel burner 4 for injecting a main fuel such as pulverized coal is provided at the front of the kiln of the rotary kiln 2.

The preheater 1 includes a plurality of cyclones 1a.about.
It is a multi-stage cyclone type in which 1e is connected by a duct, and the crushed cement raw material is preheated to a predetermined temperature (800 to 900 ° C.) using the exhaust of the rotary kiln 2. The fluidized bed calciner 10 burns fuel in this,
In order to reduce the heat load on the front part of the kiln of the rotary kiln 2, a predetermined amount of raw material before being introduced into the rotary kiln 2 is calcined, and the raw material from the second cyclone 1d from the bottom of the preheater 1 is located below itself. And then calcined in a fluidized bed, and then returned from the upper outlet to the cyclone 1e in the lowermost stage of the preheater 1 together with the exhaust from the kiln butt housing of the rotary kiln 2.

The fluidized bed calcination furnace 10 has a chamber 14 for introducing fluidized air from an air supply pipe 15 at the lowermost end of the furnace body 10A, as shown in detail in FIG. The fluidizing air introduced into the chamber 14 is blown upward from a fluidizing nozzle (not shown) to fluidize the raw material and the pulverized coal. Therefore, on the lower side wall of the furnace body 10A, in order from the bottom, a pulverized coal injection pipe 12 for injecting pulverized coal, and a raw material supply chute 11 for introducing a raw material from the second cyclone 1d from the lowest stage of the preheater 1. Gas extracted from the cooler 3 (see Fig. 1) (high-temperature gas at 700 ° C)
Combustion air blow-in pipe 1 for introducing air as combustion air
3 is provided.

Next, a method for producing a cement clinker will be described. In manufacturing cement clinker,
In the method of the present embodiment, the furnace body 10A of the fluidized bed calcination furnace 10 is used.
The combustible waste K is put on the fluidized bed in the lower part. Since several methods can be adopted as the charging method, description will be made with reference to FIGS. 2 and 3.

In the first example (1), an inlet 21 for combustible waste is formed in the raw material supply chute 11 of the fluidized bed calciner 10, and the combustible waste K is fed from the inlet 21 to the chute 11. It is added on the cement raw material flowing in,
The combustible waste K together with the cement raw material is made to flow into the fluidized bed in the lower part of the furnace body 10A.

When the combustible waste K is actually charged in this manner, the combustible waste K does not deeply sink due to the floating effect of the fluidized bed raw material and stays in the upper part of the fluidized bed for a relatively long time and burns. It was way. Therefore, it is no longer possible to see that the combustible waste submerges in the lower part of the fluidized bed and is welded to block the fluidizing nozzle and reduce the amount of fluidized air inserted. However, it did not affect the fluidizing nozzle.

In the second example (2), the combustible waste input port 22 is provided on the wall of the furnace body 10A of the fluidized bed calciner 10, and the combustible waste K is supplied from the input port 22 to the furnace. It is designed to be put on the fluidized bed in the lower part of the body 10A. in this case,
The position in the height direction in which the charging port 22 is provided is preferably set to be above the center position where the combustion air blowing pipe 13 is connected to the furnace body 10A and to be set to the range A to the blow-up portion. This is because if it is above that, fine-grained components of the combustible waste may escape directly to the outside of the calcination furnace 10.

When, for example, crushed particles of waste plastic are introduced as combustible waste from the inlet 22 provided in the range A as described above, the behavior is expected to be as follows. First, the wind speed in the lower part of the range A is 10 m / s or more,
It is usually 12 to 13 m, and fresh hot air is blown up. After this, in the upper part of the range A, the wind speed is 3 to 5 m.
/ S is decelerated. The raw material and the relatively coarse fuel circulate in the subsequent dilution zone and the upper part of the range A, and stay for a certain period of time, and only the amount accompanied by the gas is outside the system (calcining furnace 10
Outside). Therefore, by throwing the waste plastic into the range exposed to the wind speed, the waste plastic is lifted and is not deposited or welded to the lower part of the fluidized bed.

In this case, as shown in FIG. 3 (a), the air flow outlet is adjacent to the lower side of the flammable waste inlet 22 provided in the wall of the furnace body 10A of the fluidized bed calciner. 32 is provided, and it is more preferable that the combustible waste put into the furnace body 10A is dispersed by blowing air from the air outlet 32. In such a case, the waste plastic is substantially removed from the furnace body 10.
The furnace body 10 can be charged at a position away from the wall A.
This is because welding to the A wall can be prevented. Here, as for the opening shape of the air outlet 32 for dispersion air, when the shape is horizontally long rather than circular as shown in FIG. 3B, the dispersion effect is higher. The opening width L of the outlet 32 is 1 of the opening width D of the inlet 22.
/ 3 to 1 times, and the opening height H is set to about 2 to 20 mm. The chute forming the charging port 22 is preferably cooled by introducing the outside air or by a cooling water jacket in order to prevent the welding of the waste plastic.

In the third example (3), the combustible waste injection port 23 is provided in the combustion air blowing pipe 13 of the fluidized bed calcination furnace 10, and the combustible waste is added from this injection port 23. The combustible waste is allowed to flow into the fluidized bed in the lower part of the furnace body 10A. Also in this case, it was possible to burn the combustible waste without causing a problem such as blocking the fluidizing nozzle as in the above case.

The above is the example in which the combustible waste can be incinerated without any trouble by charging the combustible waste on the fluidized bed. I will describe.

A case where waste plastic is blown from the pulverized coal supply port 12 will be described as a failure example. In this example, the blowing air velocity is 30 m / s, and the particle diameter is 15 to 20 mm.
Simply infused with 1.5 t / h of flammable waste. As a result, a decrease in the amount of air inserted by the blower that sends fluidized air to the fluidized bed was observed, and a phenomenon was observed in which the operation of the calcination furnace 10 became unstable.

When the reason for this was examined after stopping the operation, it was found that the combustible waste (waste plastic) sinked and was welded to the vicinity of the fluidized air injection nozzle, narrowing the injection hole. This is because the waste plastic was blown together with the fuel into the fluidized bed with a slow wind speed of about 1 m / s (inside, not above), and the blowing position was close to the injection nozzle. It is presumed that this is because the combustible waste having a relatively coarse particle size dropped to the level of the fluidizing nozzle, and was sprinkled on the material that had been fluidized and accumulated there.

The flammable waste used in the present invention is ideally composed mainly of granular or flaky crushed waste plastics, but other flammable wastes may be used. .

Further, as the combustible waste, granular or flaky waste plastic is used, and the slurry-like mixture obtained by mixing this with liquid waste (mainly waste oil) in advance is used as the furnace body of the fluidized bed calciner 10. You may make it throw in on the fluidized bed of 10 A inside lower part.

When the combustible waste in the form of a slurry mixture is disposed of in the calcining furnace 10 as described above, the mixture can be conveyed together using a general-purpose slurry pump and disposed of at the same time. It becomes possible to use a single transportation system for the objects, and the device configuration can be simplified. Further, since it can be transported as a slurry, it is not necessary to crush the solid waste to a finer size and a uniform particle size for pneumatic transportation, and the crushing load is reduced. Further, since the granular combustible waste and the liquid waste are put into the calcining furnace 10 in a mixed state, the combustibility of the liquid waste is enhanced as compared with the case where the liquid waste such as waste oil is disposed of alone. be able to.

[0035]

As described above, according to the inventions of claims 1 to 7, the quality of the cement clinker is not affected at all, and the operation of the fluidized bed calciner is not affected at all.
A large amount of combustible waste can be incinerated while being used as a part of combustion in a calciner. In particular, claims 2 to 5
According to the invention of (1), the combustible waste can be surely added onto the fluidized bed by providing the charging port and charging the combustible waste.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a cement clinker of the present invention.

FIG. 2 is an enlarged cross-sectional view of a fluidized bed calcination furnace used for explaining a method for charging combustible waste.

3A and 3B are explanatory views of the contents of improvement in the case of implementing one of the charging methods, FIG. 3A is a side sectional view, and FIG. 3B is a front view of an opening portion as viewed from the inside of the furnace.

FIG. 4 is an explanatory view of a conventional method for manufacturing a cement clinker.

[Explanation of symbols]

1 preheater 2 Rotary kiln 10 Fluidized bed calciner 10A furnace body 11 Raw material supply chute 13 Fuel air blow pipe 21,22,23 Input port for combustible waste

Claims (7)

[Claims] 1. A method for producing a cement clinker while injecting combustible waste in a cement firing step, comprising: a fluidized bed in a lower part of a furnace of a fluidized bed calcination furnace provided before a rotary kiln in the cement firing step. A method for producing a cement clinker, which comprises charging combustible waste on the top. 2. An inlet for combustible waste is formed in a raw material supply chute of the fluidized bed calciner, and the combustible waste is added to the cement raw material flowing through the chute through the inlet.
Thereby, the combustible waste is caused to flow into the fluidized bed in the lower part of the furnace body together with the cement raw material, and the method for producing a cement clinker according to claim 1. 3. An inlet for combustible waste is provided on the furnace body wall of the fluidized bed calcining furnace, and the combustible waste is introduced from the inlet to the fluidized bed in the lower part of the furnace body. Claim 1
The method for producing a cement clinker according to 1. 4. An air outlet is provided adjacent to a lower side of an inlet for combustible waste provided on a furnace wall of the fluidized bed calciner, and air is blown from the outlet. The method for producing a cement clinker according to claim 3, wherein the combustible waste that has been introduced into the furnace body is dispersed. 5. A combustible waste injection port is provided in the combustion air blowing pipe of the fluidized bed calcination furnace, and the combustible waste is added from this injection port to remove the combustible waste from the lower part of the furnace body. The method for producing a cement clinker according to claim 1, wherein the cement clinker is poured into the fluidized bed. 6. The combustible waste, which is mainly composed of granular or flaky crushed waste plastics, is put into a fluidized bed. Cement clinker manufacturing method. 7. A granular or flaky waste plastic is used as the combustible waste, and the slurry-like mixture prepared by mixing the waste plastic with the liquid waste in advance is placed on the fluidized bed in the lower part of the furnace body of the fluidized bed calciner. It is charged into
5. The method for producing a cement clinker according to any one of 5 above.