Method for jointly controlling emission of NOx by utilizing multi-stage bias combustion and fuel reburning

Abstract

The invention belongs to the technical field of pulverized coal combustion, and discloses a method for jointly controlling the emission of NOx by utilizing multi-stage bias combustion and fuel reburning. The method comprises the steps: arranging a multi-stage bias burner containing 2 to 6 layers of bias burners in a multi-stage bias combustion area, sending 75 to 85 percent of fuel into the multi-stage bias combustion area, and generating flue gas containing the NOx during the combustion; spraying mixed reburning fuel of 15 to 25 percent of coal and biomass fuel into a mixed reburning area, forming a reburning reduction area, precipitating CHi and NHi active groups by the mixed reburning fuel in reducing atmosphere, and reacting the CHi and NHi active groups with the NOx generated in the multi-stage bias combustion area to be reduced into N2; and spraying the air into a burnout area, and completely combusting combustible substances which are not completely combusted. The method can efficiently control the emission of the NOx, ensure that the removal efficiency of the NOx is more than 80 percent, realize the combustion of high pulverized coal concentration, improve the performance of ignition and steady combustion, improve the adaptability of coal types, effectively prevent the slag bonding of water-cooled walls, and achieve the aims of improving boiler efficiency, saving energy and reducing consumption.

Description

technical field

[0001] The invention belongs to the technical field of pulverized coal combustion, and specifically uses multi-stage rich-lean combustion and fuel reburning to jointly control NO x method of emission. Background technique

[0002] my country is a large energy consumption country dominated by coal. With the improvement of energy conservation and environmental protection requirements in our country, the pulverized coal combustion technology of coal-fired power stations is facing a comprehensive solution to wide adaptability of fuel, high combustion efficiency, stable combustion at low load, and prevention of slagging. , low NO x issues such as emissions.

[0003] In recent years, combustion technology at home and abroad has made great progress, and low-NOx combustion technologies such as low-oxygen combustion, air-staged combustion, rich-lean combustion, and reburning have been developed. Most of my country's power plant boilers use air classification and low...

Examples

Embodiment 1

[0018] The device of this embodiment is as figure 1 As shown, the pulverized coal 7 of the pulverizing system of the power plant boiler is divided into two paths through the primary air pipe 8, which are respectively connected with the reburning fuel connecting pipe 6 and the furnace multi-stage thick-lean burner 11. The multi-stage thick-lean burner is arranged at the four corners of the furnace to The tangential form is sprayed into the multi-stage thick-lean combustion zone I in the furnace, forming a tangent circle of φ450~900mm in the center of the furnace, such as figure 2 shown. Multi-stage rich-lean burner 11 such as image 3 As shown, there are 11 layers of spouts in total, and the furnace includes 5 layers of rich-lean burners from bottom to top, of which the first and fourth layers are upper-rich and lower-lean burners 1104 and are deflected upward by 4 to 6 degrees, and the second layer is horizontal thick-lean burners. Burner 1105, the third and fifth floors ar...

Embodiment 2

[0023] In this embodiment, multi-stage rich-lean combustion and mixed fuel reburning are used to jointly control NO x The difference between the discharge method and embodiment 1 is the arrangement of the rich-lean burner, Figure 4 A schematic diagram of the arrangement of the second multi-stage rich-lean burner is given. The rich-lean burner has five layers of nozzles, two of which are rich-lean burners (lower thicker upper thinner type 1102 and upper thicker lower thinner type 1104). Side air 1103 is provided on the side and backfire side of the rich-lean burner, and the other three layers are secondary air nozzles 1101, which are respectively arranged between the rich-lean burners. This type of burner has a low arrangement height, which is suitable for pulverized coal boilers with small capacity.

Embodiment 3

[0025] In this embodiment, multi-stage rich-lean combustion and mixed fuel reburning are used to jointly control NO x The difference between the discharge method and that of Example 1 lies in the preparation and feeding of biomass reburned fuel. When in use, the purchased granular biomass reburning fuel is stored in the reburning fuel storage bin 40 and transported to the intermediate feeding bin 4 by means of pneumatic conveying. This embodiment cancels the pretreatment of biomass, and the system is simpler.

technical field

[0001] The invention belongs to the technical field of pulverized coal combustion, and specifically uses multi-stage rich-lean combustion and fuel reburning to jointly control NO x method of emission. Background technique

[0002] my country is a large energy consumption country dominated by coal. With the improvement of energy conservation and environmental protection requirements in our country, the pulverized coal combustion technology of coal-fired power stations is facing a comprehensive solution to wide adaptability of fuel, high combustion efficiency, stable combustion at low load, and prevention of slagging. , low NO x issues such as emissions.

[0003] In recent years, combustion technology at home and abroad has made great progress, and low-NOx combustion technologies such as low-oxygen combustion, air-staged combustion, rich-lean combustion, and reburning have been developed. Most of my country's power plant boilers use air classification and low...

Examples

Embodiment 1

[0018] The device of this embodiment is as figure 1 As shown, the pulverized coal 7 of the pulverizing system of the power plant boiler is divided into two paths through the primary air pipe 8, which are respectively connected with the reburning fuel connecting pipe 6 and the furnace multi-stage thick-lean burner 11. The multi-stage thick-lean burner is arranged at the four corners of the furnace to The tangential form is sprayed into the multi-stage thick-lean combustion zone I in the furnace, forming a tangent circle of φ450~900mm in the center of the furnace, such as figure 2 shown. Multi-stage rich-lean burner 11 such as image 3 As shown, there are 11 layers of spouts in total, and the furnace includes 5 layers of rich-lean burners from bottom to top, of which the first and fourth layers are upper-rich and lower-lean burners 1104 and are deflected upward by 4 to 6 degrees, and the second layer is horizontal thick-lean burners. Burner 1105, the third and fifth floors ar...

Embodiment 2

[0023] In this embodiment, multi-stage rich-lean combustion and mixed fuel reburning are used to jointly control NO x The difference between the discharge method and embodiment 1 is the arrangement of the rich-lean burner, Figure 4 A schematic diagram of the arrangement of the second multi-stage rich-lean burner is given. The rich-lean burner has five layers of nozzles, two of which are rich-lean burners (lower thicker upper thinner type 1102 and upper thicker lower thinner type 1104). Side air 1103 is provided on the side and backfire side of the rich-lean burner, and the other three layers are secondary air nozzles 1101, which are respectively arranged between the rich-lean burners. This type of burner has a low arrangement height, which is suitable for pulverized coal boilers with small capacity.

Embodiment 3

[0025] In this embodiment, multi-stage rich-lean combustion and mixed fuel reburning are used to jointly control NO x The difference between the discharge method and that of Example 1 lies in the preparation and feeding of biomass reburned fuel. When in use, the purchased granular biomass reburning fuel is stored in the reburning fuel storage bin 40 and transported to the intermediate feeding bin 4 by means of pneumatic conveying. This embodiment cancels the pretreatment of biomass, and the system is simpler.

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