阅读说明：本技术 可燃物的处理方法和处理装置 (Method and apparatus for treating combustible material ) 是由 山本泰史 于 2019-08-06 设计创作，主要内容包括：在维持稳定运转的同时,有效利用废塑料、废轮胎、稻谷壳、木屑、PKS、RDF、污泥等可燃性废弃物,并且提高煤、焦炭等化石燃料的燃烧效率,进一步减少水泥窑排气中的NOx浓度。可燃物的处理装置(1),其包括：将可燃物(C)与从水泥烧成装置(10)的预热器旋风器分取的600℃以上且900℃以下的预热原料(R2)混合并气化的混合装置(3)、和将气化了的可燃物和预热原料(混合原料(M))从水泥烧成装置的窑尾(13a)供给至预烧炉(12)的区域的供给装置(5)。可在将可燃物与预热原料混合时添加水分以进行水性气化反应,将生成的水性气体和预热原料从水泥烧成装置的窑尾导入预烧炉的区域。(Combustible waste materials such as waste plastics, waste tires, rice husks, wood chips, PKS, RDF, sludge, and the like are effectively utilized while maintaining stable operation, and the combustion efficiency of fossil fuels such as coal and coke is improved, thereby further reducing the NOx concentration in the exhaust gas of the cement kiln. Device (1) for treating combustible materials, comprising: the cement burning device comprises a mixing device (3) for mixing and gasifying a combustible material (C) and a preheating raw material (R2) which is obtained from a cyclone of a preheater of the cement burning device (10) and is higher than 600 ℃ and lower than 900 ℃, and a supply device (5) for supplying the gasified combustible material and the preheating raw material (mixing raw material (M)) to a region of a pre-burning furnace (12) from a kiln tail (13a) of the cement burning device. The water-based gasification reaction may be carried out by adding water when the combustible and the preheating raw material are mixed, and the produced aqueous gas and the preheating raw material may be introduced into the area of the pre-firing furnace from the kiln tail of the cement burning apparatus.)

1. A method for treating a combustible, characterized by mixing and gasifying a combustible with a preheated raw material having a temperature of 600 ℃ to 900 ℃ which is taken from a cyclone of a preheater of a cement burning apparatus, and supplying the gasified combustible and the preheated raw material from a kiln tail of the cement burning apparatus to a region of a preheater.

2. The method for treating combustible according to claim 1, wherein moisture is added to the combustible and the preheated raw material to perform an aqueous gasification reaction, and the produced aqueous gas and the preheated raw material are introduced from a kiln tail of a cement burning apparatus into a region of a pre-burning furnace.

3. Combustible treatment device, characterized in that it comprises: the cement burning device comprises a mixing device for mixing and gasifying the combustible material and the preheating raw material which is extracted from a cyclone of a preheater of the cement burning device and is higher than 600 ℃ and lower than 900 ℃, and a supplying device for supplying the gasified combustible material and the preheating raw material to a region of a pre-burning furnace from a kiln tail of the cement burning device.

4. The combustible treatment apparatus according to claim 3, comprising a moisture addition device for adding moisture to the mixing device to perform an aqueous gasification reaction.

Technical Field

The present invention relates to a technique for efficiently utilizing combustible waste such as waste plastics, waste tires, rice hulls, wood chips, PKS, RDF, and sludge, improving the combustion efficiency of the combustible waste and fossil fuels such as coal and coke, and further efficiently reducing the NOx concentration in exhaust gas from a cement kiln.

Background

General waste such as municipal waste and industrial waste such as sludge are directly disposed of in landfills or are incinerated in refuse incinerators. Incineration ash generated at the time of incineration is brought into a final disposal site, and a new lot of the final disposal site has been difficult in recent years, so that the residual capacity of the final disposal site is constantly embarrassed. Therefore, combustible waste such as waste plastics and sludge is incinerated and gasified for effective use (for example, patent document 1). Further, there is a technique of burning combustible waste at a kiln end or a pre-firing furnace, but in order to increase the throughput, it is necessary to crush the waste finely, or the burning time in the pre-firing furnace is changed from 1 to 3 seconds to 5 seconds or more.

In addition, recently, the discharge amount of waste plastics is increasing, and the import of waste plastics is prohibited in china and the like, and therefore the demand for waste plastic processing is increasing at home and abroad. Further, NOx control of exhaust gas discharged to the atmosphere in china and korea is under reinforcement.

On the other hand, the exhaust gas from the cement kiln contains NOx in a high temperature range caused by the burning zone, and when the NOx concentration is high, a denitration agent such as urea or ammonia is added, or the NOx concentration is reduced by a reduction action by combustion in the calcining furnace. However, in the method using urea as a denitration agent, the cost of operation increases because urea is expensive. Further, if only urea is added, the denitration efficiency is low, and there is a possibility that the remaining ammonia that has not reacted with NOx is directly discharged to the outside of the system.

Therefore, the applicant proposes the following techniques: a denitration burner for blowing fuel and combustion air into the kiln tail of a cement kiln is provided, and NOx in the cement kiln exhaust gas is reduced in a low oxygen region in the kiln tail and the fuel is combusted, whereby the decarbonation efficiency of the cement raw material can be improved, and the NOx concentration in the cement kiln exhaust gas can be efficiently reduced while maintaining a good firing state regardless of the form of the pre-firing furnace (see patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-155484

Patent document 2: japanese patent No. 6476165

Disclosure of Invention

Problems to be solved by the invention

If combustible waste such as waste plastics, waste tires, rice husks, wood chips, PKS, RDF, sludge, etc. is gasified, tar is generated, and thus there is a problem that stable operation is hindered by adhesion, clogging, etc. Further, the risk of explosion or the like due to combustion cannot be eliminated.

On the other hand, in the denitration of exhaust gas from a cement kiln, the coal two-stage combustion described in patent document 2 has problems such as insufficient NOx reducing agent, insufficient denitration effect, and adhesion of a coating layer to a coal introduction portion.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to effectively utilize combustible waste such as waste plastics, waste tires, rice husks, wood chips, PKS, RDF, and sludge while maintaining stable operation, to improve combustion efficiency of fossil fuel such as coal and coke, and to reduce NOx concentration in exhaust gas from a cement kiln.

Means for solving the problems

In order to achieve the above object, the present invention is a method for treating a combustible, characterized by mixing and gasifying a combustible with a preheated raw material having a temperature of 600 ℃ to 900 ℃ which is taken from a cyclone of a preheater of a cement burning apparatus, and supplying the gasified combustible and the preheated raw material from a kiln tail of the cement burning apparatus to a region of a pre-burning furnace.

According to the present invention, combustible materials such as combustible waste and fossil fuel are mixed with the preheated raw material, thereby preventing tar generation during gasificationAdhesion problems, etc. In addition, by gasifying combustible substances in an oxygen-free state, reducing substances can be generated to preheat Fe in the raw material₂O₃Can also be reduced to FeO, and the amount of the reducing agent can be increased. Further, since the combustion time can be shortened by gasification, even in the conventional pre-combustion furnace for coal combustion in which the retention time of the exhaust gas in the pre-combustion furnace is 1 to 3 seconds, the combustible waste can be effectively combusted, and the amount of coal used and the amount of CO generated can be reduced. The gasified combustible containing the reducing agent and the preheating raw material containing the reducing agent are supplied from the kiln tail to the area of the pre-combustion furnace, so that the powder and the gas can be dispersed in the gas, and the NOx in the combustion gas of the cement kiln can be effectively reduced. Further, since the gasified combustible and the preheating raw material are introduced into the pre-firing furnace, the problem of adhesion of the coating layer can be avoided. Further, since the combustion time can be shortened by gasification, the electric power for breaking the combustible can be reduced.

In the method of treating the combustible, water may be added to perform an aqueous gasification reaction when the combustible and the preheating raw material are mixed, and the produced aqueous gas and the preheating raw material may be introduced into a region of the pre-firing furnace from a kiln tail of the cement firing apparatus. Since the sealing is carried out with steam without introducing oxygen, there is no danger of explosion, and H is generated by aqueous gasification reaction₂While Fe in the raw material is also reduced₂O₃Since FeO is reduced, the amount of the reducing agent is dramatically increased. Thereby, NOx in the combustion gas of the cement kiln can be effectively reduced.

Further, the present invention is a combustible treatment device, comprising: the cement burning device comprises a mixing device for mixing and gasifying the combustible material and the preheating raw material which is extracted from a cyclone of a preheater of the cement burning device and is higher than 600 ℃ and lower than 900 ℃, and a supplying device for supplying the gasified combustible material and the preheating raw material to a region of a pre-burning furnace from a kiln tail of the cement burning device.

According to the present invention, by mixing combustible materials such as combustible waste and fossil fuel with the preheated raw material, it is possible to avoid problems such as adhesion due to tar generated during gasification. In additionIn addition, by gasifying combustible substances in an oxygen-free state, reducing substances can be generated, and Fe in the raw material can be preheated₂O₃Can also be reduced to FeO, and the amount of the reducing agent can be increased. Further, since the combustion time can be shortened by gasification, even in the conventional pre-combustion furnace for coal combustion in which the retention time of the exhaust gas in the pre-combustion furnace is 1 to 3 seconds, the combustible waste can be effectively combusted, and the amount of coal used and the amount of CO generated can be reduced. The gasified combustible containing the reducing agent and the preheating raw material containing the reducing agent are supplied from the kiln tail to the area of the pre-combustion furnace, so that the powder and the gas can be dispersed in the gas, and the NOx in the combustion gas of the cement kiln can be effectively reduced. Further, since the gasified combustible and the preheating raw material are introduced into the pre-firing furnace, the problem of adhesion of the coating layer can be avoided. Further, since the combustion time can be shortened by gasification, the electric power for breaking the combustible can be reduced.

The combustible material treatment device may include a water addition device for adding water to the mixing device to perform the aqueous gasification reaction. Thereby eliminating the danger of explosion and generating H by aqueous gasification reaction₂The reducing agent of (2), and also Fe in the raw material₂O₃Since the amount of the reducing agent is drastically increased by reducing the NOx to FeO, NOx in the combustion gas of the cement kiln can be efficiently reduced. Further, the aqueous gasification reaction is an endothermic reaction, and the temperature does not rise excessively basically, so SUS310S can be used as a material for a mixing device. Even if the temperature rises, the temperature rises to only 850 ℃ at the maximum due to the evaporation of water and the heat absorption by decarbonation of the raw material.

ADVANTAGEOUS EFFECTS OF INVENTION

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

Drawings

Fig. 1 is a schematic view showing an embodiment of a combustible treatment apparatus according to the present invention.

Detailed Description

Fig. 1 shows an embodiment of a combustible treatment device according to the invention, the treatment device 1 comprising: a hopper 2 containing combustibles C; a mixing device 3 for mixing and gasifying the combustible C supplied from the hopper 2 with a preheated raw material R2 having a temperature of 600 ℃ or higher and 900 ℃ or lower which is taken from a cyclone 11B in a second stage from the bottom of a preheater 11 of the cement burning device 10; and a supply device 5 for supplying the gasified combustible C and the preheated raw material R2 (including the non-gasified combustible C, hereinafter referred to as "mixed raw material M") from a kiln tail 13a of the cement kiln 13 of the cement burning device 10 to a region of the pre-burning furnace 12. Note that, in fig. 1, 2 cyclones 11B are described, which is for convenience of explanation, and 2 are the same.

The combustible material C to be treated is waste plastic, waste tires, rice hulls, wood chips, combustible waste such as PKS, RDF, sludge, and fossil fuel such as coal and coke.

The mixing device 3 is a kneading mill or the like in which a plurality of blades 3b are attached to a horizontal shaft 3a and the blades 3b are rotated by rotating the horizontal shaft 3a, and mixes and gasifies the combustible C and the preheated raw material R2.

A water spraying device (not shown) is provided above the mixing device 3, and water is sprayed (water W is supplied) into the mixing device 3 to perform the aqueous vaporization reaction. In the mixing device 3, a cover (フード)3c is provided to prevent the scattering dust from increasing due to the rapid generation of water vapor.

A closed damper (シャットダンパー)4 is provided below the mixing device 3, and the mixed raw material M is introduced into the area of the pre-firing furnace 12 from the kiln tail 13a of the cement kiln 13 of the cement burning device 10 via the supply device 5 while maintaining airtightness. Further, an exhaust line 6 for discharging the gasified gas G is provided, and the gas G discharged from the exhaust line 6 is merged with the mixed raw material M below the closed damper 4 and is introduced into the region of the pre-combustion furnace 12 from the kiln tail 13a of the cement kiln 13 of the cement burning apparatus 10 via the supply device 5. The supply device 5 includes a chute (シュート), a pipeline, and a conveyor.

The cement burning apparatus 10 with the treatment apparatus 1 is constituted by a preheater 11 for preheating the cement raw material R1, a preburning furnace 12 for preburning the preheated raw material R2 from the cyclone 11B of the second stage from below of the preheater 11, a cement kiln 13 for burning the raw material R3 from the cyclone 11A of the lowest stage of the preheater 11 by the fuel F blown from the main burner 15, a clinker cooler 14 for cooling the cement clinker burned in the cement kiln 13, and the like, and is similar to the conventional cement burning apparatus. Further, it is preferable to provide a powder and granular material dispersing device according to japanese patent No. 6396433 of the present applicant at a supply position of the mixed raw material M by the supply device 5, so that the preheated raw materials of the gasified combustible C and the powder are effectively dispersed in the gas.

Next, a method of treating combustible by using the treatment apparatus 1 will be described with reference to fig. 1.

During operation of the cement burning apparatus 10, the combustible C contained in the hopper 2 is supplied to the mixing device 3, and a part of the preheated raw material R2 discharged from the cyclone 11B of the preheater 11 is separated, and the separated preheated raw material R2 is introduced into the mixing device 3. The undivided preheated raw material R2 was decarbonated in the preburning furnace 5 and the lowest cyclone 11A as usual, and then calcined in the cement kiln 13 to produce cement clinker.

In the mixing device 3, the combustible C and the preheated raw material R2 are conveyed while being mixed and stirred, the combustible C is heated and gasified by the divided preheated raw material R2, and water is sprayed from the water spraying device to perform the aqueous gasification reaction. By mixing the combustible C with the preheated raw material R2, the problem of adhesion due to tar generated during gasification can be avoided. In addition, the acid gas generated from the combustible C can be fixed to the preheated raw material R2. Further, since the combustion time can be shortened by gasification, even the conventional preburning furnace 12 for coal combustion can be efficiently combusted, and the amount of coal used and the amount of CO generated can be reduced.

The mixing ratio of the combustible C and the preheated raw material R2 is not particularly limited, and when the combustible C adheres to the inside of the mixing device 3 or the conveyance route, the mixing ratio of the preheated raw material R2 is increased. When waste plastics or the like is processed, it is preferable that the waste plastics or the like is crushed to a size of 200mm or less in advance in the front stage of the mixing device 3. Preferably, the residence time of the combustible C in the mixing device 3 is set to 5 to 15 minutes, and the rotation speed of the horizontal shaft 3a of the mixing device 3 is variable to adjust the residence time.

Further, since oxygen is not introduced into the mixing device 3 and sealed with steam, there is no danger of explosion, and H is generated by the aqueous gasification reaction₂And Fe in the raw material R2 is preheated₂O₃Since FeO is also reduced, the amount of the reducing agent is dramatically increased.

The mixed raw material M discharged from the mixing device 3 is supplied from the kiln inlet 13a of the cement kiln 13 of the cement burning device 10 to the area of the pre-burning furnace 12 through the supply device 5 by closing the damper 4. As described above, the amount of the reducing agent is drastically increased, and therefore NOx in the cement kiln combustion gas can be efficiently reduced. The non-gasified combustible C in the mixed raw material M is used as a fuel substitute in the pre-burner 12, and the separated pre-heated raw material R2 is decarbonated in the pre-burner 12 and the lowest cyclone 11A, and then burned in the cement kiln 13 to produce cement clinker.

In the above embodiment, the preheated raw material R2 is separated from the cyclone 11B of the preheater 11, but if the temperature of the separated cement raw material is 600 ℃ or higher and 900 ℃ or lower, it can be separated from other parts.

Further, by providing the water spraying device, spraying water into the mixing device 3, performing the aqueous gasification reaction, and even if the combustible C is gasified by merely mixing the divided preheating material R2 without spraying water, the problem of adhesion due to tar generated during gasification can be avoided, and there is an effect that the combustion time can be shortened by gasification, and the like, and the combustible C can be effectively utilized while maintaining the stable operation of the treatment device 1 and the cement burning device 10, and the NOx concentration in the cement kiln exhaust gas can be reduced.

Further, the configuration of the mixing device 3 is not limited to the above-mentioned mixing device, and any other type of device may be employed as long as it can mix and gasify the combustible C with the divided preheated raw material R2 and further, as long as it can add water to perform the aqueous gasification reaction.

Description of reference numerals

1 combustible treatment device

2 hopper

3 mixing device

4 closing the air lock

5 supply device

6 exhaust pipeline

10 cement burning device

11 preheater

12 pre-burning furnace

13 Cement kiln

14 clinker cooler

15 main burner