阅读说明：本技术 一种降低锅炉结渣沾污并协同处理二次铝灰危废的方法 (Method for reducing slag bonding contamination of boiler and cooperatively treating secondary aluminum ash hazardous waste ) 是由 方顺利 姚伟 张喜来 刘家利 杨忠灿 张森 李仁义 周广钦 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种降低锅炉结渣沾污并协同处理二次铝灰危废的方法,包括步骤：1)分别测试二次铝灰及原煤中的氟元素含量,并确定二次铝灰的添加量2)将待处理的二次铝灰筛分,并将其粒径＞30mm的颗粒破碎；3)通过上料装置,在上煤皮带上将二次铝灰按比例均匀添加到原煤中。4)原煤与二次铝灰混合物,通过锅炉燃烧器进入锅炉内燃烧。5)燃烧过程中,通过煤中及湿法脱硫系统中的钙元素将氟元素转化为不可溶于水的氟化钙。二次铝灰中的铝元素含量较高,燃烧中,降低了入炉灰分中碱性金属元素的比例,降低了燃煤的结渣性和安全性,提高了锅炉运行的安全性。本发明处理过程无其它危险废弃物产生,并且可同时实现二次铝灰处理和降低锅炉结渣和沾污。(The invention discloses a method for reducing slag bonding contamination of a boiler and cooperatively treating secondary aluminum ash hazardous waste, which comprises the following steps: 1) respectively testing the fluorine content in the secondary aluminum ash and the raw coal, and determining the addition amount of the secondary aluminum ash 2) screening the secondary aluminum ash to be treated, and crushing particles with the particle size larger than 30 mm; 3) and uniformly adding the secondary aluminum ash into the raw coal in proportion on the coal feeding belt through a feeding device. 4) The mixture of the raw coal and the secondary aluminum ash enters the boiler for combustion through the boiler burner. 5) During combustion, the fluorine element is converted into calcium fluoride which is not soluble in water through calcium element in coal and in a wet desulphurization system. The secondary aluminum ash has higher aluminum element content, reduces the proportion of basic metal elements in the ash entering the boiler during combustion, reduces the slag bonding property and safety of fire coal, and improves the safety of boiler operation. The invention has no other dangerous waste in the treatment process, and can simultaneously realize secondary aluminum ash treatment and reduce boiler slagging and contamination.)

1. The method is characterized in that secondary aluminum ash is crushed and then mixed with raw coal, fluorine in the secondary aluminum ash is solidified by using the raw coal and calcium in a wet desulphurization system in the combustion process in a boiler, and the slagging and contamination characteristics of the coal are reduced by using aluminum with higher content in the secondary aluminum ash, so that the slagging and contamination characteristics of the boiler are reduced, and the hazardous waste of the secondary aluminum ash is cooperatively treated.

2. The method for reducing the slag-bonding contamination of the boiler and the co-processing the secondary aluminum ash hazardous waste according to claim 1, wherein the method comprises the following steps:

1) measuring the content of fluorine element in the secondary aluminum ash, wherein the fluorine element is expressed by F (secondary aluminum ash) and the unit is mu g/g; testing the content of fluorine element in raw coal, expressed by F (raw coal), and the unit is mug/g;

2) screening the secondary aluminum ash to be treated;

3) uniformly adding the crushed and screened secondary aluminum ash into raw coal according to a proportion, wherein the adding proportion of the secondary aluminum ash is calculated according to the following formula:

wherein omega (secondary aluminum ash) represents the percentage of the mass of the secondary aluminum ash in the mass of the raw coal, and the unit is percent;

4) the mixture of the raw coal and the secondary aluminum ash is ground by a pulverized coal boiler pulverizing system and then enters a boiler for combustion through a boiler burner;

5) in the combustion process in the boiler, the fluorine element in the secondary aluminum ash is released into the fluorine element in the high-temperature environment in the boiler, wherein part of the fluorine element reacts with calcium ions in coal to generate insoluble calcium fluoride which is distributed in fly ash and slag, and part of the fluorine element enters a wet desulphurization system in a gaseous state along with flue gas, is dissolved in water, reacts with the calcium ions in limestone slurry to generate calcium fluoride and is retained in desulfurized gypsum;

the secondary aluminum ash has higher aluminum element content, and the proportion of alkaline metal elements in the ash entering the furnace is reduced in the combustion process.

3. The method for reducing the slag contamination of boilers and co-processing secondary aluminum ash hazardous waste according to claim 2, wherein in step 2), the particles with the particle size larger than 30mm are crushed.

4. The method for reducing the slagging contamination and the cooperative treatment of secondary aluminum ash dangerous waste of the boiler according to claim 2, wherein in the step 3), the crushed and screened secondary aluminum ash is proportionally and uniformly added into the raw coal on the coal feeding belt through a feeding device.

5. The method for reducing the slagging contamination and the cooperative treatment of secondary aluminum ash dangerous waste of the boiler according to claim 4, wherein in the step 3), the secondary aluminum ash is proportionally mixed and added with the raw coal before the feeding belt.

6. The method for reducing the slagging contamination and the cooperative treatment of secondary aluminum ash dangerous waste of the boiler according to claim 4, wherein in the step 3), the secondary aluminum ash is proportionally mixed and added with the raw coal before a coal feeder.

7. The method for reducing the slag-bonding contamination of the boiler and co-processing the secondary aluminum ash dangerous waste according to the claim 2, wherein in the steps 1) -4), the secondary aluminum ash is ground to R₉₀After the granularity is less than 10 percent, the coal powder in the primary air powder pipe and the coal powder in the primary air powder pipe are mixed and added according to the proportion.

8. The method for reducing the slag-bonding contamination of the boiler and co-processing the secondary aluminum ash dangerous waste according to the claim 2, wherein in the steps 1) -4), the secondary aluminum ash is ground to R₉₀After the granularity is less than 10 percent, the mixture is sprayed into a hearth through a nozzle in a boiler hearth.

Technical Field

The invention belongs to the technical field of reduction of slagging and contamination characteristics of boilers which are easy to slag and contaminate coal and treatment of secondary aluminum ash dangerous waste in electrolytic aluminum industry, and particularly relates to a method for reducing slagging and contamination of boilers and cooperatively treating secondary aluminum ash dangerous waste.

Background

The aluminum ash is a waste produced in the production process of electrolytic aluminum industry, and the main component is Al₂O₃According to different processes, the components can reach more than 70 percent, and in addition, a small amount of metallic aluminum, fluoride and other metallic salts are also added. Aluminum ash has been listed in the national hazardous waste catalogue (HW48) and must not be discharged without treatment. The aluminum ash is divided into primary secondary aluminum ash and secondary aluminum ash, wherein the secondary aluminum ash is a product obtained by separating metal aluminum in the primary secondary aluminum ash, the content of the metal aluminum is low, the treatment and utilization efficiency is low at present, and the cost is high.

At present, a large amount of easily-slagging and easily-contaminated coal are available in China, the typical coal is Xinjiang high-alkali coal, and the proportion of alkali metal in fuel ash entering a furnace is reduced by additionally adding part of high-aluminum minerals in the current combustion field of the high-alkali coal, so that slagging and contamination characteristics of the high-alkali coal are reduced. The typical additive mineral is kaolin, but for most power plants, adding kaolin incurs higher cost expenses.

If the hazardous waste secondary aluminum ash which is difficult to treat and utilize in the electrolytic aluminum industry can be used as the aluminum-based additive of the easy-to-slag coal species, the slagging and dirt-adhering properties of the easy-to-slag coal species in the combustion process can be reduced, the hazardous waste of the secondary aluminum ash in the electrolytic aluminum industry can be treated in a synergistic manner, and better economic benefits can be brought to related enterprises.

Disclosure of Invention

The invention aims to provide a method for reducing slagging and contamination of a boiler and cooperatively treating secondary aluminum ash dangerous waste, which mixes crushed secondary aluminum ash with raw coal, solidifies fluorine in the secondary aluminum ash by using the raw coal and calcium in a wet desulphurization system in the combustion process in the boiler, and reduces slagging and contamination characteristics of the coal by using aluminum with higher content in the secondary aluminum ash, thereby realizing the reduction of slagging and contamination characteristics of the boiler and cooperative treatment of the secondary aluminum ash dangerous waste, and having simple and convenient whole realization process and less initial investment.

The invention is realized by adopting the following technical scheme:

a method for reducing slagging and contamination of a boiler and cooperatively treating hazardous waste of secondary aluminum ash comprises the steps of crushing the secondary aluminum ash, mixing the crushed secondary aluminum ash with raw coal, solidifying fluorine elements in the secondary aluminum ash by using the raw coal and calcium elements in a wet desulphurization system in the combustion process in the boiler, and reducing slagging and contamination characteristics of the coal by using aluminum elements with higher content in the secondary aluminum ash, so that slagging and contamination characteristics of the boiler are reduced, and the hazardous waste of the secondary aluminum ash is cooperatively treated.

A further development of the invention is that the method comprises the following steps:

1) measuring the content of fluorine element in the secondary aluminum ash, wherein the fluorine element is expressed by F (secondary aluminum ash) and the unit is mu g/g; testing the content of fluorine element in raw coal, expressed by F (raw coal), and the unit is mug/g;

2) screening the secondary aluminum ash to be treated;

3) uniformly adding the crushed and screened secondary aluminum ash into raw coal according to a proportion, wherein the adding proportion of the secondary aluminum ash is calculated according to the following formula:

wherein omega (secondary aluminum ash) represents the percentage of the mass of the secondary aluminum ash in the mass of the raw coal, and the unit is percent;

4) the mixture of the raw coal and the secondary aluminum ash is ground by a pulverized coal boiler pulverizing system and then enters a boiler for combustion through a boiler burner;

5) in the combustion process in the boiler, the fluorine element in the secondary aluminum ash is released into the fluorine element in the high-temperature environment in the boiler, wherein part of the fluorine element reacts with calcium ions in coal to generate insoluble calcium fluoride which is distributed in fly ash and slag, and part of the fluorine element enters a wet desulphurization system in a gaseous state along with flue gas, is dissolved in water, reacts with the calcium ions in limestone slurry to generate calcium fluoride and is retained in desulfurized gypsum;

the secondary aluminum ash has higher aluminum element content, and the proportion of alkaline metal elements in the ash entering the furnace is reduced in the combustion process.

A further development of the invention is that, in step 2), the particles having a particle size of > 30mm are comminuted.

The further improvement of the invention is that in the step 3), the crushed and screened secondary aluminum ash is uniformly added into the raw coal in proportion on the coal feeding belt through a feeding device.

The further improvement of the invention is that in the step 3), the secondary aluminum ash and the raw coal are mixed and added in proportion before the feeding belt.

The further improvement of the invention is that in the step 3), the secondary aluminum ash and the raw coal are mixed and added in proportion before the coal feeder.

The invention further improves that in the steps 1) to 4), the secondary aluminum ash is ground to R₉₀After the granularity is less than 10 percent, the coal powder in the primary air powder pipe and the coal powder in the primary air powder pipe are mixed and added according to the proportion.

The invention further improves that in the steps 1) to 4), the secondary aluminum ash is ground to R₉₀After the granularity is less than 10 percent, the mixture is sprayed into a hearth through a nozzle in a boiler hearth.

The invention has at least the following beneficial technical effects:

1. the aluminum element with larger mass fraction in the secondary aluminum ash can be utilized to reduce the proportion of the basic metal elements in the total ash entering the furnace, thereby reducing the slag bonding property and the contamination property of the coal entering the furnace and improving the safety of the operation of the boiler.

2. Harmful fluorine elements in the secondary aluminum ash can be supplied by calcium elements in the fire coal entering the furnace and calcium elements in a wet desulphurization system to generate calcium fluoride which is insoluble in water, so that the discharged ash and fluorine pollutants in the smoke are not overproof.

3. The secondary aluminum ash dangerous waste in the electrolytic aluminum industry is treated by utilizing the boiler which is easy to slag and stain and is easy to use, only a primary crushing and feeding device of the aluminum ash needs to be added, the treatment capacity is large, and the environmental benefit and the social benefit are good.

Drawings

FIG. 1 is a flow chart of the process for converting the secondary aluminum ash dangerous waste in the electrolytic aluminum industry.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In the production process of certain electrolytic aluminum plants, primary aluminum ash is generated, and secondary aluminum ash is formed after metal aluminum in the primary aluminum ash is separated and extracted, and the secondary aluminum ash cannot be processed after being stocked in a plant area for a long time, so that the normal production of the electrolytic aluminum plants is influenced. The high-alkali coal in Xinjiang area is designed and used in the self-prepared power plant of the electrolytic aluminum plant, has strong slag bonding and dirt adhering properties, and influences the safe operation of a boiler. The power plant is forced to mix and burn part of kaolin in raw coal to relieve the slag bonding and contamination of the boiler, but the kaolin is high in price and brings great economic burden to the power plant.

The boiler of the self-prepared power plant of the electrolytic aluminum plant can be utilized to cooperatively treat secondary aluminum ash dangerous waste, simultaneously reduce the slagging and the contamination of the boiler and improve the safety of the operation of the boiler. Specifically, as shown in fig. 1, the method for reducing slag formation and contamination of a boiler and cooperatively treating secondary aluminum ash hazardous waste, provided by the invention, comprises the following steps:

1) the fluorine content in the secondary aluminum ash was measured and expressed as F (secondary aluminum ash):

f (secondary aluminum ash) ═ 80000 μ g/g;

the content of fluorine element in the raw coal was measured and expressed as F (raw coal):

f (raw coal) ═ 150 μ g/g;

2) screening the secondary aluminum ash to be treated, and crushing particles with the particle size larger than 30 mm;

3) through loading attachment, evenly add the secondary aluminum ash after crushing, screening to the raw coal in proportion on the coal feeding belt, the proportion of addition of secondary aluminum ash is calculated according to the following formula:

ω (secondary aluminum ash) represents the percentage of the secondary aluminum ash mass to the raw coal mass, and is calculated from the above formula, where ω (secondary aluminum ash) is 0.82%.

When the plant feeds coal for a certain time, the belt coal flow rate is 1000t/h, and secondary aluminum ash is added into raw coal at the rate of 8.20t/h through a feeding device.

4) The mixture of the raw coal and the secondary aluminum ash is ground by a pulverized coal boiler pulverizing system and then enters the boiler for combustion through the boiler burner.

5) In the combustion process in the boiler, fluorine elements in the secondary aluminum ash are released into fluorine elements in the high-temperature environment in the boiler, wherein part of the fluorine elements react with calcium ions in coal to generate insoluble calcium fluoride which is distributed in fly ash and slag, and part of the fluorine elements enter a wet desulphurization system in a gaseous state along with flue gas, are dissolved in water, react with the calcium ions in limestone slurry to generate calcium fluoride and are retained in desulfurized gypsum. The soluble fluorine content in the ash was tested to be 7mg/L, the soluble fluorine content in the slag is 6mg/L, and the requirements of national emission standards are met. The content of HF in the smoke is 3mg/Nm³And meets the requirements of national emission standards.

6) The content of the ash content of the raw coal receiving base is 7 percent, the content of NaO in the ash is 4.5 percent, and Al₂O₃The content is 23 percent, the NaO content in the secondary aluminum ash is 3 percent, and Al₂O₃The content of the secondary aluminum ash is 76 percent, so that after the secondary aluminum ash is added into the raw coal according to 0.82 percent of the mass of the raw coal, the content of NaO in the mixture ash is 4.3 percent, and Al is contained in the mixture ash₂O₃The content is 29%. By adding partial secondary aluminum ash into raw coal, Al in the ash entering the furnace is improved₂O₃The content of the NaO in the ash entering the boiler is reduced, so that the slag bonding property and the safety of the fire coal are reduced, and the safety of the operation of the boiler is improved.

Compared with the existing electrolytic aluminum secondary aluminum ash treatment method and the method for reducing slagging and dirt-sticking of the boiler burning the high-alkali coal, the method has the advantages that the initial investment is small, excessive devices and equipment are not needed to be added in enterprises, the slagging and the dirt-sticking of the boiler burning coal can be simultaneously reduced, the operation safety of the boiler is improved, the secondary aluminum ash dangerous waste is cooperatively treated, and no other dangerous waste is generated in the treatment process.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.