A wind box structure and method for controlling combustion deviation on both sides of a counter-firing boiler

Abstract

A bellows structure and method for controlling combustion deviations on both sides of a counter-fired boiler, the bellows structure comprising burner bellows arranged on the front wall and the rear wall, and one layer of burners is arranged corresponding to one layer of burners, and each layer of burners is arranged inside the corresponding layer of burner bellows; the burners include pulverized coal burners and burnout air burners; each layer of burner bellows is provided with a vertical partition, and the number of pulverized coal burners or burnout air burners arranged inside the burner bellows on both sides of the vertical partition is the same. The control method comprises increasing the air intake of the burner bellows on the side with lower oxygen amount when the deviation of the operating oxygen amount on both sides is greater than a threshold value; when the deviation of the smoke temperature at the furnace outlet is greater than a threshold value or the deviation of the steam temperature on both sides of the screen superheater outlet is greater than a threshold value, increasing the air intake of the burner bellows on one side or reducing the air intake of the burner bellows on the other side. The present invention can match the difference in the amount of pulverized coal entering the burners on both sides of the furnace and reduce the steam temperature deviation on both sides.

Description

Technical Field

[0001] The invention belongs to the field of coal-fired power station boilers, and in particular relates to a wind box structure and method for controlling combustion deviations on both sides of a counter-firing boiler. Background Art

[0002] The uneven distribution of flame temperature and oxygen concentration in the furnace section is an important characteristic of coal-fired power plant boilers. The deviation of the cross-section heat load causes the deviation of the heat absorption of the heating surface, leading to problems such as overheating of the heating surface wall temperature, deviation of steam temperature on both sides, and slagging of the heating surface.

[0003] The front and rear walls of the counter-fired boiler are arranged with multiple layers (three or two layers) of swirl burners. Depending on the capacity of the boiler, a single layer is generally equipped with 4, 6, or 8 swirl burners. The pulverized coal entering each layer of the burner is provided by a coal mill. Due to the uneven distribution of pulverized coal at the outlet of the coal mill, there is a large difference in the amount of pulverized coal entering the burners on the same layer, which in turn causes uneven combustion heat loads on the burners on the same layer, causing problems such as overheating of the heating surface wall temperature, deviation of steam temperature on both sides, and slagging on the heating surface. For example, a 600MW opposed-firing boiler has problems with furnace outlet flue gas temperature deviation and reheat steam temperature deviation during operation. By measuring the powder quantity in the powder tube at the outlet of each coal mill, it was found that the powder quantity deviation of the primary air duct of coal mill A was -28.36%~53.15%, the powder quantity deviation of the primary air duct of coal mill B was -46.21%~30.86%, the powder quantity deviation of the primary air duct of coal mill D was -7.91%~19.33%, the powder quantity deviation of the primary air duct of coal mill E was -24.85%~22.6%, and the powder quantity deviation of the primary air duct of coal mill F was -62.93%~27.45%. The powder quantity deviation of the primary air duct of each coal mill was large, and the powder quantity deviation of the powder tube was the main reason for the deviation of the furnace outlet flue gas temperature.

[0004] The counter-fired boiler adopts a large bellows structure, that is, a bellows is designed on the front wall and the rear wall of the boiler. The front wall bellows and the rear wall bellows are divided into multiple wind chambers by partitions according to the number of burner layers. The number of wind chambers is the same as the number of burner layers. The air volume is controlled by the shutter adjustment baffles on the secondary air ducts on both sides of the entrance of each wind chamber. Actual operation and experimental tests have found that when the opening of the secondary air swirl blades of the swirl burners on the same layer is consistent, there are obvious differences in the air intake of each burner. The air intake of the burner in the middle area is larger, and the air intake of the burners close to the two sides is smaller. During combustion, the oxygen content of the counter-fired boiler along the furnace width is generally high in the middle and low on both sides, that is, the O2 content in the center area of ​​the furnace along the furnace width is large and the CO content is small, while the O2 content on both sides is small and the CO content is high. There are differences in the air intake and powder intake between the burners on the same layer of the counter-fired boiler, which causes deviations in boiler combustion. In order to balance the heat load and oxygen deviation in the furnace area along the furnace width, most of the solutions that have been proposed adopt the method of increasing the opening of the secondary air swirl blades of the side wall burners and reducing the opening of the secondary air swirl blades of the middle burners to balance the air volume entering the burners on the same layer. However, the inherent structural characteristics of the burner bellows and the difference in the powder feed amount of the coupled burners are the main reasons for the combustion deviation problem in the hedge combustion boiler. Therefore, the bellows structure needs to be improved. Summary of the invention

[0005] The purpose of the present invention is to address the problems in the above-mentioned prior art and provide a bellows structure and method for controlling the combustion deviation on both sides of a counter-firing boiler, thereby increasing the means of regulating combustion in the furnace and matching the difference in the amount of pulverized coal entering the burners on both sides of the furnace.

[0006] In order to achieve the above object, the present invention has the following technical solutions:

[0007] A bellows structure for controlling combustion deviations on both sides of a counter-firing boiler comprises burner bellows arranged on a front wall and a rear wall, wherein one layer of burners corresponds to one layer of burner bellows, and each layer of burners is arranged inside the burner bellows of the corresponding layer; the burners comprise pulverized coal burners and burnt-out air burners; vertical partitions are arranged inside each layer of burner bellows, and the number of pulverized coal burners or burnt-out air burners arranged inside the burner bellows on both sides of the vertical partitions is the same.

[0008] As a preferred solution of the bellows structure of the present invention, a damper adjustment baffle, an air duct expansion joint and an air volume measuring device are arranged on both sides of the vertical partition inside the burner bellows, and the damper adjustment baffle, the air duct expansion joint and the air volume measuring device on both sides of the vertical partition are symmetrically arranged with respect to the vertical partition; the air duct expansion joint is arranged on the burner bellows outside the damper adjustment baffle, and the air volume measuring device is arranged in the burner bellows inside the damper adjustment baffle.

[0009] As a preferred solution of the bellows structure of the present invention, the damper adjustment baffle is adjusted by an electric or pneumatic actuator, and the damper adjustment baffles located on both sides of the vertical partition inside each layer of the burner bellows are independently adjusted by an electric or pneumatic actuator.

[0010] As a preferred solution of the bellows structure of the present invention, bellows pressure measuring points and bellows temperature measuring points are arranged inside the burner bellows on both sides of the vertical partition, and the bellows pressure measuring points and bellows temperature measuring points on both sides of the vertical partition are symmetrically arranged about the vertical partition.

[0011] As a preferred solution of the bellows structure of the present invention, the pulverized coal burners are arranged in layers on the front wall and the rear wall. Four, six or eight pulverized coal burners are selected on each layer according to the capacity of the boiler. The number of pulverized coal burners on the front wall and the rear wall is equal and their positions are relative.

[0012] As a preferred solution of the wind box structure of the present invention, the overburnt air burners are arranged in layers on the front wall and the rear wall, the number of overburnt air burners on each layer is the same as the number of pulverized coal burners on each layer, and the number of overburnt air burners on the front wall and the rear wall are equal and their positions are relative.

[0013] As a preferred solution of the bellows structure of the present invention, the pulverized coal burner is inserted and installed on the burner bellows, and the load of the pulverized coal burner is transmitted to the boiler support beam through the truss of the burner bellows; the burnout air burner is inserted and installed on the burner bellows, and the load of the burnout air burner is transmitted to the boiler support beam through the truss of the burner bellows.

[0014] As a preferred solution of the wind box structure of the present invention, the wind source of the burner wind box is taken from the hot secondary air at the outlet of the air preheater.

[0015] A control method for a wind box structure based on the control of combustion deviations on both sides of a counter-fired boiler comprises:

[0016] The operating oxygen deviation control includes the following steps: detecting the operating oxygen on both sides of the furnace during the combustion process of the boiler, and when the operating oxygen deviation on both sides is greater than a threshold, increasing the air intake of the burner wind box on the side with lower oxygen;

[0017] The control of the furnace outlet smoke temperature and the platen superheater outlet steam temperature includes the following steps: detecting the furnace outlet smoke temperature deviation and the steam temperature deviation on both sides of the platen superheater outlet. When the furnace outlet smoke temperature deviation is greater than a threshold value or the steam temperature deviation on both sides of the platen superheater outlet is greater than a threshold value, the air intake of the burner bellows on one side is increased or the air intake of the burner bellows on the other side is reduced, thereby reducing the furnace outlet smoke temperature on one side or the steam temperature at the platen superheater outlet on one side, and increasing the furnace outlet smoke temperature on the other side or the steam temperature at the platen superheater outlet on the other side.

[0018] As a preferred embodiment of the control method of the present invention, the threshold of the operating oxygen deviation is set to 1 percentage point, the threshold of the furnace outlet flue gas temperature deviation is 50°C, and the threshold of the steam temperature deviation on both sides of the platen superheater outlet is 10°C.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: by arranging each layer of burners inside the corresponding layer of burner bellows and arranging a vertical partition in the middle of the burner bellows, the traditional large bellows is evenly divided into independent bellows on the left and right sides, so that the air volume entering the furnace on the left and right sides of the furnace can be controlled by the air intake of the small bellows on the left and right sides, and the number of pulverized coal burners or burnt-out air burners arranged inside the burner bellows on both sides of the vertical partition is the same, thereby increasing the means of regulating combustion in the furnace, and being able to match the difference in the amount of pulverized coal entering the burners on the left and right sides of the furnace, thereby reducing the distribution deviation of the oxygen content and temperature field (especially the flue gas temperature at the furnace outlet) in the furnace section, thereby reducing the steam temperature deviation on both sides. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic cross-sectional view of a wind box structure for controlling combustion deviations on both sides of a counter-firing boiler according to the present invention;

[0021] Figure 2 A schematic side view of a wind box structure for controlling combustion deviations on both sides of a counter-firing boiler according to the present invention;

[0022] In the attached figure: 1-front wall; 2-rear wall; 3-burner bellows; 4-coal powder burner; 5-burnout air burner; 6-vertical partition; 7-damper adjustment baffle; 8-air duct expansion joint; 9-air volume measuring device; 10-bellows pressure measuring point; 11-bellows temperature measuring point. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] The present invention proposes a wind box structure for controlling the combustion deviation on both sides of the counter-firing boiler, such as Figure 1 As shown, it includes a burner wind box 3 arranged on the front wall 1 and the rear wall 2, and one layer of burner is arranged corresponding to one layer of burner wind box 3. The wind source of the burner wind box 3 is taken from the hot secondary air at the outlet of the air preheater. The burner includes a pulverized coal burner 4 and a burnt air burner 5. Please refer to Figure 2, each layer of burners is arranged inside the corresponding layer of burner windbox 3. A vertical partition 6 is arranged inside each layer of burner windbox 3, and the number of pulverized coal burners 4 or burnt-out air burners 5 arranged inside the burner windbox 3 on both sides of the vertical partition 6 is the same. A damper adjustment baffle 7, an air duct expansion joint 8 and an air volume measuring device 9 are arranged inside the burner windbox 3 on both sides of the vertical partition 6, and the damper adjustment baffle 7, the air duct expansion joint 8 and the air volume measuring device 9 on both sides of the vertical partition 6 are symmetrically arranged about the vertical partition 6, the air duct expansion joint 8 is arranged on the burner windbox 3 outside the damper adjustment baffle 7, and the air volume measuring device 9 is arranged in the burner windbox 3 inside the damper adjustment baffle 7. A windbox pressure measuring point 10 and a windbox temperature measuring point 11 are arranged inside the burner windbox 3 on both sides of the vertical partition 6, and the windbox pressure measuring point 10 and the windbox temperature measuring point 11 on both sides of the vertical partition 6 are symmetrically arranged about the vertical partition 6. The pulverized coal burners 4 are arranged in layers on the front wall 1 and the rear wall 2. Four, six or eight pulverized coal burners 4 can be selected on each layer according to the capacity of the boiler. The number of pulverized coal burners 4 on the front wall 1 and the rear wall 2 is equal and their positions are opposite. The above-mentioned overburnt air burners 5 are also arranged in layers on the front wall 1 and the rear wall 2. The number of overburnt air burners 5 on each layer is the same as the number of pulverized coal burners 4 on each layer. The number of overburnt air burners 5 on the front wall 1 and the rear wall 2 is equal and their positions are opposite. In one embodiment, the damper adjustment baffle 7 is adjusted by an electric or pneumatic actuator, and the damper adjustment baffles 7 on both sides of the vertical partition 6 inside the wind box 3 of each layer of the burner are independently adjusted by an electric or pneumatic actuator. The pulverized coal burner 4 is inserted and installed on the burner wind box 3, and the load of the pulverized coal burner 4 is transmitted to the boiler support beam through the truss of the burner wind box 3; the overburnt air burner 5 is inserted and installed on the burner wind box 3, and the load of the overburnt air burner 5 is transmitted to the boiler support beam through the truss of the burner wind box 3.

[0025] In the embodiment of the present invention, pulverized coal burners 4 and overfire air burners 5 are symmetrically arranged in layers on the front wall 1 and the rear wall 2 of the counter-fired boiler. The overfire air burners 5 are arranged about 3m to 5m above the pulverized coal burners 4, and the number of single-layer overfire air burners 5 is the same as the number of single-layer pulverized coal burners 4. The number of burners varies according to the capacity of the boiler. For example, a 350MW supercritical counter-fired boiler is arranged with 20 pulverized coal burners, with three layers arranged on the front wall 1 and two layers arranged on the rear wall 2, and each layer has 4 pulverized coal burners 4; a 600MW supercritical counter-fired boiler is arranged with 36 pulverized coal burners 4, with three layers arranged on the front wall 1 and the rear wall 2, and each layer has 6 pulverized coal burners 4; a 1000MW ultra-supercritical counter-fired boiler is arranged with 48 pulverized coal burners, with three layers arranged on the front wall 1 and the rear wall 2, and each layer has 8 pulverized coal burners 4.

[0026] The pulverized coal burners 4 on the same layer of the counter-firing boiler are supplied by a coal mill. Deviations in the distribution of pulverized coal at the outlet of the coal mill lead to differences in the amount of pulverized coal entering the pulverized coal burners 4 on the same layer. The deviation in the amount of pulverized coal causes differences in the combustion heat loads of the burners on the same layer, leading to deviations in the operating oxygen volume on both sides of the boiler, deviations in the flue gas temperatures on both sides of the boiler furnace outlet exceeding 50°C, deviations in the steam temperature, and local slagging or over-temperature of the wall temperature on the high-temperature heating surface at the furnace outlet, all of which affect the safe operation of the boiler.

[0027] After the coal quality is determined, the amount of air required for the combustion and burnout of the coal powder is determined. Under ideal conditions, the amount of coal powder entering each coal powder burner 4 is the same, and the air volume entering a single coal powder burner 4 is the same, so that the heat load of each burner is the same, and the overall heat load of the boiler furnace is average. However, due to the inherent characteristics of the coal mill, the hedge combustion boiler has more or less certain combustion deviation problems. Since the burner wind box 3 of the traditional hedge combustion boiler is a large wind box that is connected, the effect of adjusting and controlling the combustion deviation by the difference in the opening of the wind box damper on both sides is often not good, especially the oxygen deviation on both sides of the boiler operation, and its improvement effect is limited.

[0028] The present invention arranges a burner wind box 3 separately on each layer of burners (including pulverized coal burners 4 and overburnt air burners 5), and a vertical partition 6 is arranged in the middle position of the burner wind box 3. The vertical partition 6 divides the burner wind box 3 on the same layer into two equal parts. The number of pulverized coal burners 4 and overburnt air burners 5 arranged in the burner wind boxes 3 on both sides of the vertical partition 6 is the same, that is, for a 350MW supercritical counter-fired boiler, a vertical partition 6 is arranged between the second burner and the third burner on each layer; for a 600MW supercritical counter-fired boiler, a vertical partition 6 is arranged between the third burner and the fourth burner on each layer; for a 1000MW ultra-supercritical counter-fired boiler, a vertical partition 6 is arranged between the fourth burner and the fifth burner on each layer.

[0029] The burner wind box 3 provides the secondary air required for combustion and burnout for the pulverized coal burner 4 and the burnout air burner 5. The air source of the burner wind box 3 is taken from the hot secondary air at the outlet of the air preheater. The burner wind box 3 is centered on the vertical partition 6, and the air door adjustment baffle 7, the air duct expansion joint 8, the air volume measurement device 9, the wind box pressure measurement point 10, and the wind box temperature measurement point 11 are symmetrically arranged on both sides.

[0030] The damper regulating baffle 7 is adjusted by an electric or pneumatic actuator, and the electric or pneumatic actuators on both sides of the single-layer burner wind box 3 can be adjusted separately to adjust the air volume in the burner wind box 3 area between the damper regulating baffle 7 and the vertical partition 6.

[0031] The pulverized coal burner 4 and the burnt-out air burner 5 are inserted into the burner bellows 3, and the loads of the pulverized coal burner 4 and the burnt-out air burner 5 are transmitted to the boiler support beam through the burner bellows 3 truss. Therefore, when the boiler is in operation, the pulverized coal burner 4, the burnt-out air burner 5 and the burner bellows 3 expand along with the boiler furnace. Since there is a deviation between the expansion amount of the air duct and the expansion amount of the boiler furnace, an air duct expansion joint 8 is provided on the burner bellows 3 connected to the hot secondary air duct at the air preheater outlet, and the air duct expansion joint 8 is close to the position of the air door adjustment baffle 7.

[0032] The air volume measuring device 9, the wind box pressure measuring point 10, and the wind box temperature measuring point 11 are thermal measuring points in the burner wind box 3, which respectively test the air volume, wind box pressure, and temperature inside the wind box on both sides of the vertical partition 6 in the single-layer burner wind box 3, and provide guidance for boiler operators to adjust the air distribution.

[0033] A vertical partition 6 is set in the middle of the burner wind box 3, and the burner wind box 3 on the same layer is divided into left and right independent wind boxes. By adjusting the air door damper opening 7 corresponding to the independent wind boxes, the secondary air volume entering the two sides of the burners on the same layer can be changed to match the coal powder amount entering the burners on both sides, so that the air supply volume of each layer of burners is adapted to the coal powder amount entering the burner, the oxygen field and temperature field distribution deviation in the furnace are improved, and the input heat is evenly distributed along the width of the furnace, thereby improving the overall combustion efficiency and controlling the combustion deviation.

[0034] A control method for a wind box structure based on controlling the combustion deviation on both sides of the counter-fired boiler is provided below, comprising:

[0035] Running oxygen deviation control includes the following steps:

[0036] Detect the operating oxygen levels on both sides of the furnace during boiler combustion. When the deviation of the operating oxygen levels on both sides is greater than a threshold, increase the air intake of the burner wind box 3 on the side with lower oxygen levels.

[0037] The control of furnace outlet flue gas temperature and screen superheater outlet steam temperature includes the following steps:

[0038] Detect the smoke temperature deviation at the furnace outlet and the steam temperature deviation on both sides of the platen superheater outlet. When the smoke temperature deviation at the furnace outlet is greater than the threshold or the steam temperature deviation on both sides of the platen superheater outlet is greater than the threshold, increase the air intake of the burner wind box 3 on one side or reduce the air intake of the burner wind box 3 on the other side, thereby reducing the smoke temperature at the furnace outlet on one side or the steam temperature at the platen superheater outlet on one side, and at the same time increase the smoke temperature at the furnace outlet on the other side or the steam temperature at the platen superheater outlet on the other side.

[0039] In this embodiment, the threshold of the operating oxygen deviation is set to 1 percentage point, the threshold of the furnace outlet flue gas temperature deviation is 50°C, and the threshold of the steam temperature deviation on both sides of the platen superheater outlet is 10°C. That is, if the oxygen content on the left side is 1 percentage point lower than that on the right side, the opening of the left burner wind box damper 7 can be appropriately increased for control. When the furnace outlet flue gas temperature deviation is greater than 50°C and the steam temperature deviation on both sides of the platen superheater outlet is greater than 10°C, increasing the opening of the left burner wind box damper 7 and reducing the opening of the right burner wind box damper 7 can reduce the left furnace outlet flue gas temperature and the left platen superheater outlet steam temperature, while increasing the right furnace outlet flue gas temperature and the right platen superheater outlet steam temperature.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A wind box structure for controlling combustion deviation on both sides of a counter-firing boiler, characterized in that: It comprises a burner wind box (3) arranged on a front wall (1) and a rear wall (2), wherein one layer of burners corresponds to one layer of burner wind box (3), and each layer of burners is arranged inside the burner wind box (3) of the corresponding layer; the burners comprise coal powder burners (4) and burnt-out air burners (5); a vertical partition (6) is arranged inside the burner wind box (3) of each layer, and the number of coal powder burners (4) or burnt-out air burners (5) arranged inside the burner wind boxes (3) on both sides of the vertical partition (6) is the same; The burner wind boxes (3) on both sides of the vertical partition (6) are provided with wind box pressure measuring points (10) and wind box temperature measuring points (11), and the wind box pressure measuring points (10) and wind box temperature measuring points (11) on both sides of the vertical partition (6) are symmetrically arranged with respect to the vertical partition (6); The air source of the burner wind box (3) is taken from the hot secondary air at the outlet of the air preheater.

2. The wind box structure for controlling combustion deviation on both sides of a counter-firing boiler according to claim 1 is characterized in that: The burner wind box (3) is provided with a damper adjustment baffle (7), an air duct expansion joint (8) and an air volume measuring device (9) on both sides of a vertical partition (6), and the damper adjustment baffle (7), the air duct expansion joint (8) and the air volume measuring device (9) on both sides of the vertical partition (6) are symmetrically arranged with respect to the vertical partition (6); the air duct expansion joint (8) is arranged on the burner wind box (3) outside the damper adjustment baffle (7), and the air volume measuring device (9) is arranged in the burner wind box (3) inside the damper adjustment baffle (7).

3. The wind box structure for controlling combustion deviation on both sides of a counter-firing boiler according to claim 2 is characterized in that: The damper adjustment baffle (7) is adjusted by an electric or pneumatic actuator, and the damper adjustment baffles (7) located on both sides of the vertical partition (6) inside each layer of the burner wind box (3) are independently adjusted by an electric or pneumatic actuator.

4. The wind box structure for controlling combustion deviation on both sides of a counter-firing boiler according to claim 1 is characterized in that: The pulverized coal burners (4) are arranged in layers on the front wall (1) and the rear wall (2). Four, six or eight pulverized coal burners (4) are selected on each layer according to the capacity of the boiler. The number of pulverized coal burners (4) on the front wall (1) and the rear wall (2) are equal and their positions are opposite.

5. The wind box structure for controlling combustion deviation on both sides of a counter-firing boiler according to claim 4 is characterized in that: The overburnt air burners (5) are arranged in layers on the front wall (1) and the rear wall (2); the number of overburnt air burners (5) on each layer is the same as the number of pulverized coal burners (4) on each layer; the number of overburnt air burners (5) on the front wall (1) and the rear wall (2) are equal and their positions are opposite.

6. The wind box structure for controlling combustion deviation on both sides of a counter-firing boiler according to claim 5 is characterized in that: The pulverized coal burner (4) is inserted and installed on the burner wind box (3), and the load of the pulverized coal burner (4) is transmitted to the boiler support beam through the truss of the burner wind box (3); the overburnt air burner (5) is inserted and installed on the burner wind box (3), and the load of the overburnt air burner (5) is transmitted to the boiler support beam through the truss of the burner wind box (3).

7. A control method for a wind box structure for controlling combustion deviations on both sides of a counter-firing boiler according to any one of claims 1 to 6, characterized in that: Running oxygen deviation control includes the following steps: Detecting the operating oxygen levels on both sides of the furnace during the combustion process of the boiler, and when the deviation of the operating oxygen levels on both sides is greater than a threshold, increasing the air intake of the burner wind box (3) on the side with the lower oxygen level; The control of the flue gas temperature at the furnace outlet and the steam temperature at the platen superheater outlet comprises the following steps: detecting the flue gas temperature deviation at the furnace outlet and the steam temperature deviation at both sides of the platen superheater outlet; when the flue gas temperature deviation at the furnace outlet is greater than a threshold value or the steam temperature deviation at both sides of the platen superheater outlet is greater than a threshold value, increasing the air intake of the burner wind box (3) on one side or reducing the air intake of the burner wind box (3) on the other side, thereby reducing the flue gas temperature at the furnace outlet on one side or the steam temperature at the platen superheater outlet on one side, and increasing the flue gas temperature at the furnace outlet on the other side or the steam temperature at the platen superheater outlet on the other side.

8. The control method according to claim 7, characterized in that: The threshold value of the operating oxygen deviation is set at 1 percentage point, the threshold value of the furnace outlet flue gas temperature deviation is 50°C, and the threshold value of the steam temperature deviation on both sides of the platen superheater outlet is 10°C.

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