Combustion nozzle and combustion method based on circulating fluidized bed boiler for combustion of chemical waste gas

Abstract

A combustion nozzle and a combustion method based on the combustion of chemical waste gas in a circulating fluidized bed boiler. Currently, the units in service have problems such as poor stable combustion capability without oil injection at low load, severe slagging in the furnace when the boiler is running at high load, and severe high-temperature corrosion of the water-cooled wall, which directly affect the deep peak regulation capability of the thermal power unit. The composition of the present invention includes: a main burner installed at the four corners of the boiler furnace, the central axis of the main burner forms an angle with the water-cooled wall of the furnace α The main burner comprises a plurality of groups of secondary air nozzles and primary air nozzles arranged at intervals. The invention is used for a combustion nozzle and a combustion method for chemical waste gas based on a circulating fluidized bed boiler.

Description

Technical field:

[0002] The invention relates to a co-firing nozzle and a co-firing method based on co-firing chemical waste gas in a circulating fluidized bed boiler. Background technology:

[0004] Generally, the synthetic ammonia unit in the chemical industry has two low-pressure fuel gases. In actual production, due to the relatively low calorific value of the low-pressure fuel gas, it cannot meet the requirements of the operating process. Therefore, the fuel gas is discharged as waste gas to the fuel gas main pipe or discharged to the accident flare through the vent valve for a long time, resulting in a large amount of fuel gas waste and environmental pollution. In addition, the chemical industry will produce a variety of complex waste gases in the production process, which cannot be discharged directly and will cause environmental pollution.

[0005] Circulating fluidized bed boilers use fluidized combustion. There is a large amount of bed material (ash and coal mixture) in the furnace. These bed materials are in a fluidized state under the action of the primary and secondary air of the boiler, and realize internal circulation in the furnace and external circulation outside the furnace. Under strong particle backmixing, continuous reciprocating circulation combustion, so circulating fluidized bed boilers can burn a variety of inferior fuels due to their own combustion characteristics. Circulating fluidized bed boilers have a low original NOx concentration due to their circulating fluidized combustion method, and can use low-cost furnace desulfurization and SCR, SNCR denitrification technology to meet environmental ultra-clean emission requirements. It is the best choice for clean and efficient treatment of chemical waste gas. Summary of the invention:

[0007] The purpose of the present invention is to provide a co-firing nozzle and a co-firing method for co-firing chemical waste gas based on a circulating fluidized bed boiler.

[0008] The above purpose is achieved through the following technical solutions:

[0009] A combustion nozzle based on the combustion of chemical waste gas in a circulating fluidized bed boiler, the combustion nozzle based on the combustion of chemical waste gas in a circulating fluidized bed boiler comprising a secondary air duct layered in a dense phase area of ​​the boiler, a combustion nozzle arranged in the secondary air duct to form a sleeve structure with the secondary air duct, the combustion nozzle being a venturi tube structure with a plurality of negative pressure suction holes;

[0010] The annular gap between the blending nozzle and the secondary air duct is a passage for the secondary air.

[0011] The number of the negative pressure suction holes in the circulating fluidized bed boiler-based combustion nozzle for chemical waste gas combustion is 4.

[0012] A blending method based on a blending nozzle for blending chemical waste gas in a circulating fluidized bed boiler, wherein the blended waste gas is fed in layers into a dense phase area of ​​the circulating fluidized bed and then fed into a layered secondary air port in the dense phase area of ​​the boiler, the blending nozzle and the secondary air duct form a casing structure, the annular gap is a passage for the secondary air, and the secondary air also serves as cooling air for the blending waste gas nozzle, so that the blending nozzle can operate stably for a long time in a high temperature environment, when the blended waste gas passes through the nozzle at a high speed, a Venturi effect is formed in the negative pressure area of ​​the specially designed nozzle, and the secondary air is sucked in through a small hole for premixing, and at the same time, the pressure difference between the waste gas and the furnace is large, and defire is easily formed at the waste gas nozzle, so that dispersed combustion under secondary air disturbance is achieved while protecting the nozzle, and when the waste gas is deactivated, the nozzle pressure is reduced, and the secondary air enters the waste gas pipeline from the small hole of the negative pressure suction port for automatic blowing.

[0013] Beneficial effects:

[0014] 1. The co-firing nozzle of the present invention utilizes the circulating fluidized bed boiler to co-firing chemical waste gas, which not only helps to ensure the long-term and stable operation of the co-firing nozzle, but also effectively utilizes the waste gas emission as fuel for a long time. The low-pollutant combustion technology of the circulating fluidized bed boiler solves the pollution of waste gas to the environment, which will bring good economic and environmental benefits to the enterprise.

[0015] The present invention can make clean and efficient use of waste gas fuel, which will bring good economic and environmental benefits to the enterprise. The blending nozzle and the secondary air duct form a sleeve structure, and the secondary air is used as cooling air, so that the blending nozzle can operate stably for a long time in a high temperature environment; the blending nozzle adopts a Venturi tube structure design, and the negative pressure area is premixed with the secondary air through the small hole structure to prevent backfire and flameout; when the waste gas is stopped, the secondary air will enter the waste gas pipeline from the small hole of the negative pressure suction port to automatically purge it, thereby ensuring the safe operation of the system. Description of the drawings:

[0017] Attached Figure 1 It is a schematic diagram of the structure of the layered mixed combustion nozzle in the dense phase area of ​​the boiler of the present invention;

[0018] Attached Figure 2 It is a schematic diagram of the structure of the coordination between the blending nozzle and the secondary air duct;

[0019] Attached Figure 3 It is a schematic diagram of the structure of the boiler;

[0020] In the figure: 1. Combustion nozzle; 2. Secondary air duct; 3. Dense phase area of ​​furnace; 4. Small hole structure; 5. Air distribution plate; 6. Furnace; 7. Separator; 8. Tail flue; 9. Tubular air preheater. Specific implementation method:

[0022] Embodiment 1:

[0023] A combustion nozzle based on the combustion of chemical waste gas in a circulating fluidized bed boiler, the combustion nozzle based on the combustion of chemical waste gas in a circulating fluidized bed boiler comprises a secondary air duct 2 with a boiler dense phase zone layer 3, a combustion nozzle 1 is arranged in the secondary air duct to form a sleeve structure with the secondary air duct, and the combustion nozzle is a venturi tube structure with a plurality of negative pressure suction holes 4;

[0024] The annular gap between the blending nozzle and the secondary air duct is a passage for the secondary air.

[0025] Embodiment 2:

[0026] According to the co-firing nozzle based on the co-firing of chemical waste gas in a circulating fluidized bed boiler described in Example 1, the number of the negative pressure suction holes is 4.

[0027] Embodiment 3:

[0028] A method for blending combustion using the blending nozzle position based on the blending combustion of chemical waste gas in a circulating fluidized bed boiler as described in one of Examples 1-2, wherein the blended combustion waste gas is fed in layers into the dense phase area of ​​the circulating fluidized bed and fed into the layered secondary air port of the dense phase area of ​​the boiler, the blending nozzle and the secondary air duct form a sleeve structure, the annular gap is a channel for the secondary air, and the secondary air also serves as cooling air for the blended combustion waste gas nozzle, so that the blended combustion nozzle can operate stably for a long time in a high temperature environment, when the blended combustion waste gas passes through the nozzle at a high speed, a Venturi effect is formed in the negative pressure area of ​​the specially designed nozzle, and the secondary air is sucked in through the small hole for premixing, and at the same time, the pressure difference between the waste gas and the furnace is large, and the waste gas nozzle is prone to flameout, so that dispersed combustion under the disturbance of the secondary air is achieved while protecting the nozzle, and when the waste gas is deactivated, the nozzle pressure is reduced, and the secondary air will enter the waste gas pipeline from the small hole of the negative pressure suction port to automatically purge it.

[0029] The circulating fluidized bed boiler is composed of a furnace 6, a separator 7, and a tail flue 8. The coal in the furnace burns and releases heat, the separator returns the material to form a cycle, and the heating surface of the tail flue exchanges heat. The air enters the tubular air preheater 9 for heating, and a part of it enters the water-cooled air chamber at the bottom of the furnace through the primary air duct and enters the furnace through the air distribution plate 5; a part of it enters the furnace cone section through the secondary air duct and enters the furnace in two layers. The air entering the furnace and the flue gas generated by the combustion of the coal fed from the front wall pass through the furnace, the separator and the tail flue in turn, and are discharged from the boiler after heat exchange.

[0030] The blending method is to feed the waste gas into the furnace for combustion after the boiler is stably burning. After the boiler is stably burning, the furnace temperature is as high as about 900℃, which is a favorable condition for the full combustion of chemical waste gas. The low-cost in-furnace desulfurization and SCR\SNCR denitrification of the circulating fluidized bed can make the chemical waste gas with high pollution components meet the national environmental ultra-clean emission standards and achieve efficient and clean utilization.

[0031] The mixed combustion exhaust gas is fed in layers in the dense phase area of ​​the circulating fluidized bed and fed from the secondary air port in the dense phase area of ​​the boiler. The mixed combustion nozzle and the secondary air duct form a casing structure, and the annular gap is the channel for the secondary air. The secondary air also serves as the cooling air for the mixed combustion exhaust gas nozzle, so that the mixed combustion nozzle can operate stably for a long time in a high temperature environment. When the mixed combustion exhaust gas passes through the nozzle at high speed, a Venturi effect is formed in the negative pressure area of ​​the specially designed nozzle, and the secondary air is sucked in through the small hole for premixing, which can prevent flashback. At the same time, the pressure difference between the exhaust gas and the furnace is large, and the exhaust gas nozzle is prone to flameout, which protects the nozzle while realizing dispersed combustion under the disturbance of the secondary air. When the exhaust gas is deactivated, the nozzle pressure decreases, and the secondary air will enter the exhaust gas pipeline from the small hole of the negative pressure suction port to automatically purge it, ensuring the safe operation of the system.

Claims

1. A method for mixing and burning chemical waste gas based on the mixing and burning nozzle position of a circulating fluidized bed boiler, characterized in that: The method comprises the following steps: the mixed combustion exhaust gas is fed in layers into the dense phase area of ​​the circulating fluidized bed, and is fed in layers from the secondary air port of the dense phase area of ​​the boiler, the mixed combustion nozzle and the secondary air duct form a sleeve structure, the annular gap is a channel for the secondary air, and the secondary air also serves as cooling air for the mixed combustion exhaust gas nozzle, so that the mixed combustion nozzle can operate stably for a long time in a high temperature environment, when the mixed combustion exhaust gas passes through the nozzle at a high speed, a Venturi effect is formed in the negative pressure area of ​​the specially designed nozzle, and the secondary air is sucked in through the negative pressure suction hole for premixing, and at the same time, the pressure difference between the exhaust gas and the furnace is large, and the exhaust gas nozzle is prone to flameout, so that dispersed combustion under the disturbance of the secondary air is achieved while protecting the nozzle, and when the exhaust gas is stopped, the nozzle pressure is reduced, and the secondary air will enter the exhaust gas pipeline from the negative pressure suction hole to automatically purge it.

2. The method for mixing and burning chemical waste gas based on the mixing and burning nozzle position of the circulating fluidized bed boiler according to claim 1 is characterized by: The co-firing nozzle for co-firing chemical waste gas in a circulating fluidized bed boiler includes a secondary air duct layered in the dense phase area of ​​the boiler, a co-firing nozzle is arranged in the secondary air duct to form a sleeve structure with the secondary air duct, and the co-firing nozzle is a Venturi tube structure with multiple negative pressure suction holes; the annular gap between the co-firing nozzle and the secondary air duct is a channel for secondary air.

3. The method for mixing and burning chemical waste gas based on the mixing and burning nozzle position of the circulating fluidized bed boiler according to claim 1 is characterized by: The number of the negative pressure suction holes is 4.

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