Combustor arrangement structure of coal and gas co-combustion boiler

Abstract

The utility model relates to a burner arrangement structure of a coal and gas co-combustion boiler, which is characterized in that a boiler furnace is divided into a blast furnace gas combustion area, a coke oven gas combustion area, a pulverized coal combustion area and a nitrogen reduction racemization area from bottom to top in height, blast furnace gas burners are arranged in the blast furnace gas combustion area, and the blast furnace gas burners are adjacently arranged at the lower part of a main air bellow in multiple layers; a coke oven gas combustor is arranged between the pulverized coal combustion area and the blast furnace gas combustion area in the coke oven gas combustion area; secondary air nozzles, conventional pulverized coal combustors and self-ignition pulverized coal combustors are arranged in the pulverized coal combustion area at intervals and are jointly positioned at the upper part of the main air bellow; a wall type burnout air bellow is arranged at the position, away from the main air bellow by a certain distance H in the height direction of the hearth, in the nitrogen reduction racemization area, and burnout air nozzles are arranged in the partition bins. According to the combustion characteristics of blast furnace gas, coke oven gas and pulverized coal, fuels are arranged in different areas, and the environment-friendly index and deviation control requirements of the boiler are considered. The blast furnace gas has enough long in-furnace combustion retention time and can be fully burnt out.

Description

Technical Field

[0001] The utility model relates to a burner for a coal and gas co-fired boiler, in particular to a burner layout structure for a coal and gas co-fired boiler. Background Art

[0002] As a by-product in the steelmaking process, blast furnace gas contains a large amount of combustible and harmful substances. If not treated and utilized, it will not only cause energy waste but also pollute the environment. Effective utilization and emission reduction of blast furnace gas are important issues in the current iron and steel industry. At present, using blast furnace gas as fuel is the most common utilization method, and many iron and steel enterprises choose to send blast furnace gas into the pulverized coal boilers of their own power plants for combustion. The blast furnace gas incineration power generation technology has the characteristics of high energy conversion efficiency and obvious emission reduction effect. Through this technology, it is possible to achieve the efficient utilization of blast furnace gas, make up for the shortage of power supply, and save fuel costs. Blast furnace gas has the characteristics of low calorific value, high ignition temperature, low theoretical combustion temperature, and poor combustion stability. When the proportion of blast furnace gas burned in a coal-fired boiler is relatively high, it will cause problems such as a decrease in the furnace combustion temperature, a decrease in combustion stability, and a reduction in boiler efficiency. The existing technologies for burning blast furnace gas in coal-fired boilers generally have problems such as a low proportion of blast furnace gas burned, an overly high boiler furnace height, and a low utilization rate of the radiant heating surface. Summary of the Invention

[0003] The purpose of the utility model is to provide a burner layout structure for a coal and gas co-fired boiler, so as to achieve the purpose of being able to burn coal alone and burn blast furnace gas in a large proportion and stably.

[0004] To achieve the above purpose, the technical solution of the utility model is: a burner layout structure for a coal and gas co-fired boiler, which divides the boiler furnace into a blast furnace gas combustion zone, a coke oven gas combustion zone, a pulverized coal combustion zone, and a nitrogen reduction and swirl zone from bottom to top in the height direction. In the blast furnace gas combustion zone, blast furnace gas burners are used and are arranged in multiple layers adjacent to the lower part of the main air box; in the coke oven gas combustion zone, coke oven gas burners are arranged between the pulverized coal combustion zone and the blast furnace gas combustion zone; in the pulverized coal combustion zone, secondary air nozzles and conventional pulverized coal burners and self-igniting pulverized coal burners are arranged at intervals and are all located in the upper part of the main air box; in the nitrogen reduction and swirl zone, a wall-type overfire air box is arranged at a position a certain distance H away from the main air box in the furnace height direction, and overfire air nozzles are arranged in the partition chamber.

[0005] Furthermore, the blast furnace gas burners adopt multi-tube or grid-type direct current burners; an ignition device is arranged inside the blast furnace gas burners, and the ignition fuel is coke oven gas or fuel oil or natural gas.

[0006] Furthermore, 1 to 5 layers of blast furnace gas burners are arranged in the boiler furnace; 1 to 2 layers of coke oven gas burners are arranged in the boiler furnace; and 3 to 7 layers of pulverized coal burners are arranged in the boiler furnace.

[0007] Furthermore, the inside of the primary air box and the wall-type overfire air box is divided into multiple compartments by partitions, and the secondary air nozzles, conventional pulverized coal burners, self-igniting pulverized coal burners, coke oven gas burners, blast furnace gas burners, and overfire air nozzles are respectively arranged in their respective compartments.

[0008] Furthermore, the primary air box is arranged at the four corners of the boiler furnace, and the wall-type overfire air box is arranged on the four walls of the boiler furnace; the tangential rotation direction formed by the centerlines of the wall-type overfire air boxes is opposite to the tangential rotation direction formed by the centerlines of the primary air boxes.

[0009] Furthermore, the self-igniting pulverized coal burners are arranged in two layers, respectively arranged in the first layer and the third layer of the pulverized coal burners from bottom to top.

[0010] Furthermore, an ignition device is arranged inside the self-igniting pulverized coal burner, and the micro-oil ignition method or the plasma ignition method is adopted.

[0011] Furthermore, the coke oven gas burner is composed of a coke oven gas passage and a combustion-supporting secondary air passage.

[0012] Furthermore, the first layer of the blast furnace gas burner is arranged between the second layer and the third layer of the pulverized coal burners and is located in the pulverized coal combustion area.

[0013] Furthermore, when there is no self-igniting pulverized coal burner in the pulverized coal combustion area, the ignition of the pulverized coal burner is carried out by an ignition device arranged in the secondary air tuyere, and the ignition device uses fuel oil, coke oven gas, natural gas or fuel other than fuel oil, coke oven gas, and natural gas.

[0014] The beneficial effects of the present utility model are as follows:

[0015] The advantages of the present utility model are that according to the respective combustion characteristics of blast furnace gas, coke oven gas, and pulverized coal, the fuels are arranged in different regions, taking into account the environmental protection indicators and deviation control requirements of the boiler. The blast furnace gas has a sufficiently long residence time for combustion in the furnace and can be fully burned out. The blast furnace gas burner is equipped with its own ignition device to prevent flameout and unstable combustion. The two layers of self-igniting pulverized coal burners are arranged at intervals and are used as backups for each other to ensure the safety and flexibility during the startup of the boiler. The coke oven gas burner area can increase the combustion temperature in the blast furnace gas combustion area, enhance the stability of blast furnace gas combustion, and also improve the burnout rate of pulverized coal combustion and the combustion efficiency of the boiler. The wall-type overfire air utilizes the principle of air staging technology and can reduce the NO at the boiler outlet xThe emission level can, to a certain extent, offset the swirling intensity of the flue gas in the upper part of the furnace, reducing the flue gas temperature deviation and steam temperature deviation. The burner layout is structurally compact and has good adaptability to different zones, minimizing the increase in the height dimension of the boiler furnace required for burning blast furnace gas. On the basis of meeting the demand for burning a large proportion of blast furnace gas, the structure of the boiler heating surface is well optimized, and the boiler cost is controlled. Brief Description of the Drawings

[0016] Figure 1 is an elevation view of the burner layout structure of the coal-gas co-fired boiler of the present utility model;

[0017] Figure 2 is an elevation view of the layout of the main air box and the wall-type overfire air box;

[0018] Figure 3 is a plan view of the burner layout structure of the coal-gas co-fired boiler of the present utility model

[0019] Figure 4 is Figure 1 the sectional view taken along line E-E in

[0020] Figure 5 is an elevation view of the main burner of the burner layout structure of the coal-gas co-fired boiler in Embodiment 2;

[0021] Figure 6 is an elevation view of the main burner of the burner layout structure of the coal-gas co-fired boiler in Embodiment 3. Detailed Embodiments

[0022] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0023] Embodiment 1:

[0024] As Figures 1 to 4As shown in the figure, a burner layout structure of a coal-gas mixed combustion boiler provided by an embodiment of the present utility model. The burner of the coal-gas mixed combustion boiler is composed of a secondary air nozzle 1, a conventional pulverized coal burner 2, a self-igniting pulverized coal burner 3, a coke oven gas burner 4, a blast furnace gas burner 5, a main air box 6, an overfire air nozzle 7, and a wall-mounted overfire air box 8. The interior of the main air box 6 and the wall-mounted overfire air box 8 is divided into multiple compartments by partitions. The secondary air nozzle 1, the conventional pulverized coal burner 2, the self-igniting pulverized coal burner 3, the coke oven gas burner 4, the blast furnace gas burner 5, and the overfire air nozzle 7 are respectively arranged in their respective compartments. An ignition device is provided inside the self-igniting pulverized coal burner 3, generally using a micro-oil ignition method or a plasma ignition method. The secondary air nozzle 1 is arranged at intervals with the conventional pulverized coal burner 2 and the self-igniting pulverized coal burner 3, and they are jointly located at the upper part of the main air box 6 to form a pulverized coal combustion zone 12. The self-igniting pulverized coal burner 3 is generally arranged in two layers, respectively arranged in the first layer and the third layer of the pulverized coal burner from bottom to top. An ignition device is provided inside the blast furnace gas burner 5, and the ignition fuel is coke oven gas, fuel oil, natural gas, etc. It is arranged in multiple layers adjacent to the lower part of the main air box 6 to form a blast furnace gas combustion zone 10. The coke oven gas burner 4 is arranged between the pulverized coal combustion zone 12 and the blast furnace gas combustion zone 10, which is composed of a coke oven gas passage and an auxiliary combustion secondary air passage to form a coke oven gas combustion zone 11; a wall-mounted overfire air box 8 is arranged at a position away from the main air box 6 by a certain distance H in the furnace height direction, and the overfire air nozzle 7 is arranged in the compartment to form a nitrogen reduction and swirl elimination zone 13. The main air box 6 is arranged at the four corners of the boiler furnace, and the wall-mounted overfire air box 8 is arranged on the four walls of the boiler furnace. The rotation direction of the imaginary tangent circle formed by the center line of the wall-mounted overfire air box 8 is opposite to the rotation direction of the imaginary tangent circle formed by the center line of the main air box 6.

[0025] In the present utility model, the blast furnace gas combustion zone 10 is located at the bottommost part of the entire combustion area, which can ensure that the blast furnace gas has a sufficient long residence time for combustion in the furnace. Moreover, during the combustion process, the blast furnace gas will move upward through the coke oven gas combustion zone and the pulverized coal combustion zone to achieve full combustion of the blast furnace gas. The blast furnace gas burner 5 is equipped with its own ignition device, which can be started and put into operation under special circumstances to support the combustion of the blast furnace gas and prevent the flame of the blast furnace gas from extinguishing and the combustion from being unstable. The self-igniting pulverized coal burner 3 adopts a micro-oil ignition or plasma ignition method, which can meet the ignition needs for the cold start of the boiler and can also meet the combustion support needs during the low-load operation of the boiler. The two layers of self-igniting pulverized coal burners 3 arranged at intervals are used as backups for each other to ensure the safety and flexibility during the start-up of the boiler. The coke oven gas burner 4 is located above the blast furnace gas combustion zone 10, which can not only meet the need for burning coke oven gas but also increase the combustion temperature of the blast furnace gas combustion zone, thereby enhancing the stability of the blast furnace gas combustion. The coke oven gas combustion zone can also improve the burnout rate of the pulverized coal combustion, reduce the carbon content in the large slag, and improve the combustion efficiency of the boiler.

[0026] Part of the air volume required for boiler combustion is sent into the furnace through the overfire air nozzles 7. Using the principle of air staging technology, the NO emissions at the boiler outlet can be reduced. x The swirling direction of the overfire air flow is opposite to that of the lower main air box air flow, which can offset the swirling intensity of the flue gas in the upper part of the furnace to a certain extent and reduce the flue gas temperature deviation and steam temperature deviation.

[0027] The utility model combines the combustion characteristics of each fuel, divides the boiler furnace into a blast furnace gas combustion zone 10, a coke oven gas combustion zone 11, a pulverized coal combustion zone 12 and a nitrogen reduction and swirl elimination zone 13 in the height direction, and the proportion of blast furnace gas burned can reach 100%. The burner layout structure is compact, with good adaptability to different zones, minimizing the increase in the height dimension of the boiler furnace required for burning blast furnace gas. On the basis of meeting the demand for burning a large proportion of blast furnace gas, the boiler cost is well controlled.

[0028] According to the boiler design conditions, the blast furnace gas burner adopts a multi-tube or grid-type direct current burner, and generally 1 - 5 layers can be arranged; the coke oven gas burner can be arranged in 1 - 2 layers; the pulverized coal burner can be arranged in 3 - 7 layers. The distance H is generally 5.5 - 10 meters; the overfire air nozzles 7 are generally 2 - 6 layers; the secondary air flow of the wall-mounted overfire air box 8 is generally designed to be 15% - 40% of the total boiler combustion air volume.

[0029] Embodiment 2:

[0030] As Figure 5 shown, it is a front elevation schematic diagram of the main burner of another coal-gas co-firing boiler burner layout. The difference between this Embodiment 2 and Embodiment 1 is that one layer of the blast furnace gas burner 5 is arranged between the second and third layers of pulverized coal burners, in the pulverized coal combustion zone. This layout increases the height of the pulverized coal combustion zone and can reduce the heat load intensity of pulverized coal combustion in this area. Since the theoretical combustion temperature of blast furnace gas is significantly lower than that of pulverized coal, when co-firing blast furnace gas, the heat load level in this area will be further reduced, which is especially beneficial for burning coal types with low ash fusion temperature and strong slagging, such as Xinjiang high-alkali coal, etc. Other structures are the same as those in Embodiment 1.

[0031] Embodiment 3:

[0032] As Figure 6 shown, it is a front elevation schematic diagram of the main burner of another coal-gas co-firing boiler burner layout. The difference between this Embodiment 3 and Embodiment 1 is that there is no self-igniting pulverized coal burner 3 in the pulverized coal combustion zone, and the ignition of the pulverized coal burner is achieved by an ignition device 9 arranged in the secondary air tuyere. The ignition device 9 can use fuel oil, coke oven gas, natural gas or other fuels. Other structures are the same as those in Embodiment 1.

Claims

1. A burner arrangement structure for a coal-gas mixed-firing boiler, comprising a boiler furnace, characterized in that: The boiler furnace is composed of a blast furnace gas combustion zone, a coke oven gas combustion zone, a pulverized coal combustion zone and a nitrogen reduction and de-cyclization zone from bottom to top in the height direction. A blast furnace gas combustion zone is provided with a blast furnace gas burner, which is arranged in multiple layers adjacent to each other at the lower part of the main wind box; the coke oven gas combustion zone is provided with a coke oven gas burner arranged between the pulverized coal combustion zone and the blast furnace gas combustion zone; in the pulverized coal combustion zone, secondary air nozzles and conventional pulverized coal burners and self-ignition pulverized coal burners are arranged at intervals and are located together at the upper part of the main wind box; the nitrogen reduction and de-cyclization zone is provided with a wall-type burnout wind box arranged at a certain distance H away from the main wind box in the height direction of the furnace, and the burnout air nozzles are arranged in the partition.

2. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The blast furnace gas burner adopts a multi-tube or grid type direct current burner; an ignition device is arranged inside the blast furnace gas burner, and the ignition fuel is coke oven gas, fuel oil or natural gas.

3. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: Blast furnace gas burners are arranged in 1 to 5 layers in the boiler furnace; coke oven gas burners are arranged in 1 to 2 layers in the boiler furnace; pulverized coal burners are arranged in 3 to 7 layers in the boiler furnace.

4. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The interior of the main wind box and the wall-type burnout wind box is divided into multiple compartments by partitions, and the secondary air nozzles, conventional pulverized coal burners, self-ignition pulverized coal burners, coke oven gas burners, blast furnace gas burners and burnout air nozzles are arranged in their respective compartments.

5. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The main wind boxes are arranged at the four corners of the boiler furnace, and the wall-type burnout wind boxes are arranged on the four walls of the boiler furnace; the rotation direction of the tangential circle formed by the center line of the wall-type burnout wind boxes is opposite to the rotation direction of the tangential circle formed by the center line of the main wind boxes.

6. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The self-ignition pulverized coal burners are arranged in two layers, which are arranged in the first layer and the third layer of the pulverized coal burners from bottom to top.

7. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: An ignition device is arranged inside the self-ignition pulverized coal burner, which adopts a micro-oil ignition method or a plasma ignition method.

8. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The coke oven gas burner is composed of a coke oven gas channel and a combustion-supporting secondary air channel.

9. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1 is characterized in that: The first layer of blast furnace gas burners is arranged between the second and third layers of pulverized coal burners and is located in the pulverized coal combustion zone.

10. The burner arrangement structure of the coal-gas mixed-firing boiler according to claim 1, characterized in that: When there is no self-ignition pulverized coal burner in the pulverized coal combustion zone, the pulverized coal burner is ignited by an ignition device arranged in the secondary air inlet, and the ignition device uses fuel oil, coke oven gas, natural gas or fuel other than fuel oil, coke oven gas and natural gas.

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