TWI819065B - Combustible material processing methods and processing devices - Google Patents

Abstract

[Problem] While maintaining stable operation, effectively utilize combustible waste such as waste plastics, waste tires, chaff, wood chips, PKS, RDF, and sludge, and improve the combustion efficiency of fossil fuels such as coke and coke, thereby further reducing NOx concentration in cement kiln exhaust gas. [Solution] A combustible material processing device equipped with a mixing device for mixing and gasifying the combustible material with preheated raw materials of 600°C or more and 900°C or less separated from the preheater cyclone of the cement burning device. ; and a supply device that supplies the gasified combustibles and preheated raw materials (mixed raw materials) from the kiln end of the cement burning device to the calcining furnace area. It is also possible to add water when mixing combustibles and preheated raw materials to perform a water gasification reaction, and introduce the generated water gas and preheated raw materials from the kiln end of the cement burning device into the calcining furnace area.

Description

Combustible material processing methods and processing devices

The invention relates to a method that effectively utilizes combustible wastes such as waste plastics, waste tires, chaff, wood chips, PKS, RDF, sludge, etc., and improves the combustion efficiency of the aforementioned combustible wastes and fossil fuels such as coke and coke. This is a technology that can more efficiently reduce the NOx concentration in cement kiln exhaust gas.

General waste such as municipal garbage and industrial waste such as sludge are directly buried or incinerated in garbage incineration plants. The incineration ash generated during incineration is sent to a final disposal site. However, in recent years, it has been difficult to find new locations for final disposal sites, so the remaining capacity of final disposal sites continues to be tight. Therefore, combustible wastes such as waste plastics and sludge are effectively utilized by incineration or gasification (for example, Patent Document 1). In addition, although there is a technology for burning combustible waste at the end of a kiln or a calciner, in order to increase the processing capacity, it needs to be ground into fine particles, or the combustion time in the calciner needs to be changed from 1 to 3 seconds to more than 5 seconds.

In addition, the discharge amount of waste plastics is increasing recently, and China and other countries have banned the import of waste plastics, so the demand for waste plastic processing at home and abroad is increasing. In addition, China and South Korea are strengthening the control of NOx emissions into the atmosphere.

On the other hand, the exhaust gas from the cement kiln contains NOx caused by the high temperature range of the calcining zone. When the concentration of NOx is high, denitrifying agents such as urea and ammonia are added, or through combustion in the calcining furnace. The reduction effect produced reduces NOx concentration. However, in the method of using urea as a denitrification agent, the operating cost is high because urea is expensive. In addition, the denitrification efficiency is low when only urea is added, and there is a concern that the remaining ammonia that has not reacted with NOx is directly discharged out of the system.

Here, the applicant proposed the following technology: installing a denitration burner that blows fuel and combustion air into the kiln tail of the cement kiln, and reducing NOx in the cement kiln exhaust gas in the low-oxygen zone in the kiln tail. In addition, the decarboxylation efficiency of cement raw materials can be improved by using combustion fuel, and the NOx concentration in the cement kiln exhaust gas can be efficiently reduced while maintaining a good firing state regardless of the type of calciner (see Patent Document 2).

patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-155484 Patent Document 2: Japanese Patent No. 6476165

Summary of the invention The problem to be solved by the invention When flammable wastes such as waste plastics, waste tires, chaff, wood chips, PKS, RDF, and sludge are gasified, tar will be generated, which may cause adhesion or clogging, which may hinder stable operation. Furthermore, the risk of explosion due to combustion cannot be denied.

On the other hand, regarding the denitration of cement kiln exhaust gas, in the two-stage combustion of pebbles described in Patent Document 2, the denitrification effect is insufficient due to insufficient reducing agent for NOx, and there is a coating on the introduction part of the pebbles. ) problems with attachment, etc.

Here, the present invention was completed in view of the above-mentioned problems of the conventional technology, and its purpose is to effectively utilize combustible waste such as waste plastics, waste tires, chaff, wood chips, PKS, RDF, and sludge while maintaining stable operation. It also improves the combustion efficiency of fossil fuels such as coke and coke, thereby further reducing the NOx concentration in cement kiln exhaust gas.

means to solve problems In order to achieve the above object, the present invention is a method for treating combustible materials, which is characterized in that the combustible materials and 600°C or more and 900°C or less differentiated from a preheater cyclone of a cement burning device The preheated raw materials are mixed and gasified, and the gasified combustibles and the preheated raw materials are supplied from the kiln tail of the cement burning device to the area of the calcining furnace.

According to the present invention, by mixing combustible materials such as combustible waste or fossil fuels with preheated raw materials, adhesion problems caused by tar generated during gasification can be avoided. In addition, reducing substances can be generated by gasifying combustibles in an oxygen-free state, and Fe ₂ O ₃ in the preheated raw material can also be reduced to FeO, thereby increasing the amount of reducing agent. In addition, the combustion time can be shortened by gasification, so even a conventional calciner for pebble combustion in which the residence time of the exhaust gas in the calciner is 1 to 3 seconds can effectively burn combustible waste, and can Reduce the amount of coal used and the amount of CO generated. The aforementioned preheated raw material containing the reducing agent is supplied from the end of the kiln to the calcining furnace area along with the gasified combustibles containing the reducing agent, which can disperse the powder and gas in the gas and effectively reduce the cement kiln combustion gas. of NOx. In addition, since the gasified combustibles and the aforementioned preheated raw materials are introduced into the calcining furnace, the problem of film adhesion can be avoided. In addition, since the combustion time can be shortened by gasification, the power required for crushing combustibles can also be reduced.

In the above method for treating combustibles, water can be added when the combustibles are mixed with the preheated raw materials to perform a water gasification reaction, and the generated water gas and the preheated raw materials can be introduced from the kiln end of the cement burning device. Calcining furnace area. Since it is sealed with water vapor without introducing oxygen, there is no risk of explosion, and the H ₂ reducing agent is generated through the water gasification reaction, and the Fe ₂ O ₃ in the raw material will also be reduced to FeO, so The amount of reducing agent will increase dramatically. In this way, NOx in the cement kiln combustion gas can be effectively reduced.

Furthermore, the present invention is a combustible material processing device, characterized in that it is provided with a mixing device for mixing the combustible material and the preheated raw material of 600°C or more and 900°C or less separated from the preheater cyclone of the cement burning device. Mix and gasify; and a supply device supplies the gasified combustibles and the aforementioned preheated raw materials from the kiln tail of the cement burning device to the calcining furnace area.

According to the present invention, by mixing combustible materials such as combustible waste or fossil fuels with preheated raw materials, adhesion problems caused by tar generated during gasification can be avoided. In addition, reducing substances can be generated by gasifying combustibles in an oxygen-free state, and Fe ₂ O ₃ in the preheated raw material can also be reduced to FeO, thereby increasing the amount of reducing agent. In addition, the combustion time can be shortened by gasification, so even a conventional calciner for pebble combustion in which the residence time of the exhaust gas in the calciner is 1 to 3 seconds can effectively burn combustible waste, and can Reduce the amount of coal used and the amount of CO generated. The aforementioned preheated raw material containing the reducing agent is supplied from the end of the kiln to the calcining furnace area along with the gasified combustibles containing the reducing agent, which can disperse the powder and gas in the gas and effectively reduce the cement kiln combustion gas. of NOx. In addition, since the gasified combustibles and the aforementioned preheated raw materials are introduced into the calcining furnace, the problem of film adhesion can be avoided. In addition, since the combustion time can be shortened by gasification, the power required for crushing combustibles can also be reduced.

The above-mentioned combustible material processing device may include a moisture adding device, and the moisture is added to the mixing device to cause the water-coal gasification reaction to proceed. In this way, the risk of explosion can be eliminated, and the H ₂ reducing agent is generated through the water-coal gasification reaction. Fe ₂ O ₃ in the raw material will also be reduced to FeO, so the amount of reducing agent will increase dramatically, effectively reducing NOx in cement kiln combustion gas. In addition, the water-gasification reaction is an endothermic reaction, and there is basically no excessive temperature rise. Therefore, SUS310S can be used as the material of the mixing device. Assuming that even if the temperature rises, heat will be absorbed through evaporation of water and decarboxylation of raw materials, and the temperature will only rise to a maximum of 850°C. Invention effect

As described above, according to the present invention, while maintaining stable operation, it is possible to effectively utilize combustible wastes such as waste plastics and sludge, and improve the combustion efficiency of fossil fuels such as coke and coke, thereby further reducing NOx in the cement kiln exhaust gas. concentration.

Figure 1 shows one embodiment of the combustible material processing device of the present invention. The processing device 1 is equipped with: a feeding funnel 2 to receive the combustible material C; and a mixing device 3 for mixing the combustible material C supplied from the feeding funnel 2 and the cement burned. The preheated raw material R2 of 600°C or more and 900°C or less separated by the cyclone separator 11B in the second stage below the preheater 11 of the device 10 is mixed and vaporized; and the supply device 5 vaporizes the vaporized raw material R2. The combustible material C and the preheated raw material R2 (including the ungasified combustible material C, hereinafter referred to as the "mixed raw material M") are supplied from the kiln tail 13 a of the cement kiln 13 of the cement burning device 10 to the area of the calcining furnace 12 . In addition, although two cyclones 11B are illustrated in FIG. 1 , for convenience of explanation, both are identical.

The above-mentioned combustible materials C are waste plastics, waste tires, chaff, wood chips, PKS, RDF, sludge and other combustible wastes, or fossil fuels such as pebbles and coke.

The mixing device 3 is a mixer (pug mill) or the like that has a plurality of blades 3b attached to a horizontal shaft 3a, and mixes the combustible material C and the preheated raw material R2 by rotating the horizontal shaft 3a and rotating the blades 3b. Gasification.

A water sprinkling device (not shown) is provided above the mixing device 3, and water is sprinkled (moisture content W is supplied) in the mixing device 3 to perform the water-coal gasification reaction. In order to prevent an increase in flying dust due to the rapid generation of water vapor, the mixing device 3 is provided with a hood 3c.

A shut-off damper 4 is provided below the mixing device 3, and the mixed raw material M is introduced from the kiln tail 13a of the cement kiln 13 of the cement burning device 10 through the supply device 5 while maintaining air tightness. Area of the calciner 12. In addition, an exhaust duct 6 is provided to discharge the vaporized gas G. The gas G discharged from the exhaust duct 6 meets the mixed raw material M under the shut-off baffle 4 and passes through the supply device 5 to be burned from the cement. The kiln tail 13a of the cement kiln 13 of the device 10 is introduced into the area of the calcining furnace 12. A shoot, a duct, or a conveyor can be used in the supply device 5 .

The cement burning device 10 equipped with the above-mentioned processing device 1 is the same as a conventional device, and is composed of the following components: a preheater 11 for preheating the cement raw material R1; a calcining furnace 12 for heating the cement raw material R1 from the preheater 11. Counting below, the preheated raw material R2 of the cyclone separator 11B in the second stage is calcined; the cement kiln 13 uses the fuel F blown from the main burner 15 to burn the raw material R2 from the cyclone separator 11A in the lowermost stage of the preheater 11. The raw material R3 is fired; and the clinker cooler 14 cools the cement clinker fired in the cement kiln 13. In addition, it is preferable to install the powder and granule dispersing device disclosed in Japanese Patent No. 6396433 of the applicant of the present application at the supply position of the mixed raw material M of the supply device 5, so that the vaporized combustible material C and the powder can be preliminarily dispersed. Hot raw materials are efficiently dispersed in the gas.

Next, a method of processing combustible materials using the above-mentioned processing device 1 will be described with reference to FIG. 1 .

When the cement burning device 10 is operating, the combustible material C received in the charging funnel 2 is supplied to the mixing device 3, and a part of the preheated raw material R2 discharged from the cyclone separator 11B of the preheater 11 is decomposed, and The differentiated preheated raw material R2 is introduced into the mixing device 3 . In addition, the undifferentiated preheated raw material R2 is decarboxylated in the calcining furnace 5 and the lowermost cyclone separator 11A as usual, and then is fired in the cement kiln 13 to generate cement clinker.

In the mixing device 3, the combustible material C and the preheated raw material R2 are mixed and stirred while being conveyed. The combustible material C is heated and vaporized by the decomposed preheated raw material R2, and water is sprinkled from the sprinkler device to perform a water-gas reaction. . By mixing the combustible C and the preheated raw material R2, the adhesion problem caused by the tar produced during gasification can be avoided. In addition, the acid gas generated from the combustible material C can be fixed to the preheated raw material R2. In addition, the combustion time can be shortened by gasification, so even the conventional calciner 12 for burning coal can burn efficiently, and the amount of coal used and the amount of CO generated can be reduced.

In addition, the mixing ratio of the combustible material C and the preheated raw material R2 is not particularly limited. However, when the combustible material C adheres to the inside of the mixing device 3 or the conveyance path, the mixing ratio of the preheated raw material R2 increases. In addition, when processing waste plastics, etc., it is preferable to crush them in advance to about 200 mm or less at the front stage of the mixing device 3. Furthermore, it is preferable to set the residence time of the combustible material C in the mixing device 3 to 5 to 15 minutes, to make the rotation speed of the horizontal shaft 3a of the mixing device 3 variable, and to configure the residence time to be adjustable.

In addition, since oxygen is sealed with water vapor without introducing oxygen into the mixing device 3, there is no risk of explosion, and the H ₂ reducing agent is generated by the water-coal gasification reaction, and Fe ₂ in the raw material R2 is preheated. _O3 will also be reduced to FeO, so the amount of reducing agent will increase dramatically.

The mixed raw material M discharged from the mixing device 3 passes through the shut-off baffle 4 and is supplied from the kiln tail 13 a of the cement kiln 13 of the cement burning device 10 to the area of the calcining furnace 12 through the supply device 5 . As mentioned above, since the amount of the reducing agent is increased dramatically, NOx in the cement kiln combustion gas can be effectively reduced. In addition, among the mixed raw materials M, the unvaporized combustible C is used as an alternative fuel in the calcining furnace 12, and the decomposed preheated raw material R2 is decarboxylated in the calcining furnace 12 and the lowermost cyclone separator 11A. It is fired in the cement kiln 13 to produce cement clinker.

In addition, in the above-mentioned embodiment, although the preheating raw material R2 is differentiated from the cyclone 11B of the preheater 11, as long as the temperature of the differentiated cement raw material is 600°C or more and 900°C or less, it may also be separated from other locations. differentiation.

In addition, although a sprinkler device is provided to sprinkle water in the mixing device 3 to perform the water-coal gasification reaction, even if the water is not sprinkled and the combustible C is mixed and gasified only with the decomposed preheated raw material R2, there may be a possibility. It avoids the adhesion problem caused by the tar generated during gasification, and can shorten the combustion time through gasification. It can also effectively utilize the combustible C while maintaining the stable operation of the processing device 1 and the cement burning device 10. , and reduce the NOx concentration in cement kiln exhaust gas.

In addition, the structure of the mixing device 3 is not limited to the above-mentioned structure, as long as the combustible material C can be mixed and gasified with the decomposed preheated raw material R2, and moisture can be added to perform a water-coal gasification reaction. Other types of devices may also be used.

1: Combustible materials processing device 2: Adding funnel 3: Mixing device 3a: Horizontal axis 3b: blade 3c: Cover body 4: Shut-off baffle 5: Supply device 6:Exhaust duct 10: Cement burning device 11:Preheater 11A: Cyclone separator 11B: Cyclone separator 12:Calcining furnace 13:Cement kiln 13a: kiln end 14:Clinker cooler 15: Main burner C: Combustibles F:Fuel G: gas M: mixed raw materials R1: cement raw materials R2: Preheat raw materials R3: raw materials W:moisture

FIG. 1 is a schematic diagram showing an embodiment of the combustible material processing apparatus of the present invention.

1: Combustible materials processing device

2: Adding funnel

3: Mixing device

3a: Horizontal axis

3b: blade

3c: Cover body

4: Shut-off baffle

5: Supply device

6:Exhaust duct

10: Cement burning device

11: Preheater

11A: Cyclone separator

11B: Cyclone separator

12:Calcining furnace

13:Cement kiln

13a: kiln end

14:Clinker cooler

15: Main burner

C: Combustibles

F:Fuel

G: gas

M: mixed raw materials

R1: cement raw materials

R2: Preheat raw materials

R3: raw materials

W:moisture

Claims (2)

A method for treating combustible materials, which is characterized in that: while mixing the combustible materials with preheated raw materials of 600°C or more and 900°C or less separated from the preheater cyclone of the cement burning device, the method is characterized by mixing the combustible materials in a mixture without adding oxygen. In this case, water is added to perform a water gasification reaction, and the generated water gas and the aforementioned preheating raw materials are supplied from the kiln end of the cement burning device to the calcining furnace area. A combustible material processing device, characterized in that it is provided with a mixing device that rotates blades to separate the combustible material and preheated raw materials of 600°C or more and 900°C or less separated from the preheater cyclone of the cement burning device. Mixing, while adding water without adding oxygen to perform a water-gasification reaction; a water-adding device for adding water in the aforementioned mixing device; and a supply device for transferring the generated water-gas and the aforementioned preheated raw material from the cement burning device. The end of the kiln supplies the area to the calciner.

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