Adjusting method and device for reducing high-temperature corrosion of water cooling wall of opposed firing boiler

Abstract

The invention discloses an adjusting method and device for reducing high-temperature corrosion of a water cooling wall of an opposed firing boiler, and the method comprises the steps: testing the sulfur content of coal as fired, and controlling the sulfur content of the coal as fired; the opening degree or the rotating speed and the ventilation quantity of a baffle of a separator of the coal mill are adjusted, and the primary air speed, the pulverized coal fineness and the uniformity index value of each layer of combustor are adjusted to be within the required range; the boiler operation oxygen amount, the opening degree of a secondary air box and the opening degree of an over-fire air door are adjusted, and the excess air coefficient of a main combustor area is controlled; the opening degree of internal and external secondary air and the rotational flow strength of a main combustor of the boiler are adjusted, a secondary air door in the combustor is fully opened, the rotational flow angle of the internal secondary air is adjusted to be minimum, the rotational flow angle of the external secondary air of the combustor close to two side walls is adjusted to be smaller, and meanwhile the external secondary air volume is increased. After adjustment, pulverized coal airflow deflection wall-attaching combustion is relieved, air supply in the initial stage of combustion is increased, H2S generation is reduced, and meanwhile the air supply amount of a flowing dead zone of the opposed firing boiler and the isolation capacity of a wall-attaching air film on pulverized coal airflow deflection wall-attaching are also increased.

Description

Technical Field

[0001] The present invention belongs to the field of safe operation and energy saving and consumption reduction of power station boilers, and particularly relates to an adjustment method and device for reducing high-temperature corrosion of a water-cooled wall of a counter-firing boiler. Background Art

[0002] A counter-firing pulverized coal boiler is a pulverized coal boiler that uses burners arranged in a counter-firing arrangement on the front and rear walls or at the four corners. Its core feature is that it achieves efficient combustion, low pollution emissions, and stable operation by optimizing the burner layout and aerodynamic field design. The burners of a counter-firing boiler are usually arranged symmetrically on the front and rear walls or at the four corners of the boiler, forming counter-firing flames. This arrangement can reduce the direct impact of the flame on the water-cooled walls of the furnace, reducing the risk of slagging, while enhancing the mixing of airflow in the furnace and improving combustion efficiency. By rationally designing the ratio and swirl intensity of the primary and secondary air, a stable combustion area is formed. For example, when using a low-NOx swirl burner, a multi-layer air duct design including the center air, primary air, and secondary air can achieve air staged combustion and suppress the formation of nitrogen oxides.

[0003] According to statistics, counter-fired pulverized coal-fired boilers with a capacity of over 600 MW account for over half of all large power plant boilers in my country. Counter-fired boilers are widely used due to their stable operation, minimal steam temperature deviation, and high combustion efficiency. However, in actual operation, constrained by the coal market supply and price fluctuations, power plant boilers often burn low-quality, off-design coal, including high-sulfur coal. High-sulfur coal not only causes low-level corrosion in the air preheater and exacerbates ammonium bisulfate blockage, but also, under low-nitrogen combustion conditions, the generation of H2S in the absence of oxygen due to low oxygen combustion and the presence of dead zones near the walls of the counter-fired boiler can exacerbate high-temperature corrosion of the water-cooled walls in the boiler's main burner and reduction zones. This increases the risk of water-cooled wall tube bursts due to high-temperature corrosion, significantly compromising safe operation, increasing boiler maintenance costs, and shortening maintenance cycles.

[0004] To mitigate high-temperature corrosion in the water-cooled walls of counter-heat boilers, wall-mounted airflow is installed to replenish oxygen in dead zones. Power plants also frequently employ methods such as spraying metal alloys for corrosion prevention. However, due to inappropriate wall-mounted airflow sources and inconsistent spraying materials and processes, the corrosion prevention effects of both measures are often subpar. To improve boilers' adaptability to low-cost, high-sulfur coal, a new method to reduce high-temperature corrosion in water-cooled walls is urgently needed. Summary of the Invention

[0005] To address these issues, the present invention proposes an adjustment method and device for reducing high-temperature corrosion of the water-cooled walls of opposed-firing boilers. This invention helps address the severe high-temperature corrosion of the water-cooled walls of power station boilers caused by factors such as inappropriate wall-mounted airflow design, poor spraying, elevated sulfur content, and improper operational adjustments.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides an adjustment method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler, comprising the following steps: 1) Test the quality of coal entering the furnace and control the sulfur content of the coal entering the furnace t,ar ≤0.7%; 2) Adjust the separator baffle or speed of the coal mill to control the coal powder fineness at 8-22%; 3) Adjust the ventilation volume of the coal mill and control the primary air speed of each burner layer to 22-24m / s; 4) Adjust the boiler operating oxygen content, secondary air box opening and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; 5) For boilers with wall-mounted air nozzles installed on the front and rear walls, adjust the wall-mounted air damper opening to 70-100% when the boiler load is above 80% ECR during operation; 6) Adjust the secondary air swirl angle of the main burner to 0° to wrap the pulverized coal airflow, and keep the secondary air door opening at 100%; 7) Adjust the external secondary air swirl angle of the main burner near the two side walls to 0-10°; 8) After adjustment, the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

[0007] A further improvement of the present invention is that, in step 1), the total sulfur content in coal is determined according to GB / T214-2007 "Determination of total sulfur in coal".

[0008] A further improvement of the present invention is that, in step 1), if the coal fed into the furnace is mixed coal and the sulfur content of different types of coal varies greatly, a premixed and blended combustion method is adopted.

[0009] A further improvement of the present invention is that, in step 2), the uniformity index of the coal powder fineness is not less than 1.0.

[0010] A further improvement of the present invention is that in step 2), for lean coal boilers, the coal powder fineness is controlled at 8-16%, and for bituminous coal boilers, the coal powder fineness is controlled at 16-22%.

[0011] A further improvement of the present invention is that, in step 4), the damper opening of the secondary air box of the main burner is adjusted so that when the boiler load is above 80% ECR, the secondary air box opening is not less than 70%.

[0012] A further improvement of the present invention is that, in step 5), the opening of the wall damper is adjusted so as not to cause overheating of the screen or the heating surface tube wall after the adjustment.

[0013] A further improvement of the present invention is that in step 7), the main burners close to the two side walls are in the first row close to the left and right side walls of the boiler and are arranged in 5 or 6 layers.

[0014] A further improvement of the present invention is that the boiler used in the method is a front and rear wall counter-combustion boiler, or a pulverized coal boiler with two side walls counter-combustion.

[0015] The present invention also provides an adjustment device for reducing high-temperature corrosion of the water-cooled wall of a counter-fired boiler, comprising: The coal quality testing unit is used to test the coal quality and control the sulfur content of the coal. t,ar ≤0.7%; The separator adjustment unit adjusts the separator baffle or speed of the coal mill to control the coal powder fineness at 8-22%; The ventilation volume regulating unit adjusts the ventilation volume of the coal mill and controls the primary air speed of the burners on each layer to 22-24m / s; The comprehensive regulation unit adjusts the boiler operating oxygen content, secondary air box opening, and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; The wall damper opening adjustment unit is used to adjust the wall damper opening to 70-100% when the boiler load is above 80% ECR for boilers with wall air nozzles installed on the front and rear walls. The internal secondary air adjustment unit adjusts the internal secondary air swirl angle of the main burner to 0°, wrapping the pulverized coal airflow and maintaining the internal secondary air door opening at 100%; External secondary air adjustment unit, adjusts the external secondary air swirl angle of the main burners near the two side walls to 0-10°; Confirm the unit and adjust it so that the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides an adjustment method and device for reducing high-temperature corrosion of the water-cooled walls of a counter-firing boiler. The method first optimizes and controls the sulfur content of the coal entering the boiler and the blending method of coals with different sulfur contents, thereby reducing the sulfur input to the boiler at the source and preventing severe high-temperature corrosion of the water-cooled walls, either overall or locally. Subsequently, by regulating the fineness and uniformity of the pulverized coal and the excess air coefficient in the main burner area, the oxygen supply to the main burner and the rapid ignition and burnout of the pulverized coal are ensured. Simultaneously, a reasonable primary air velocity is controlled to reduce collisions of the primary air flow in the middle of the furnace. This prevents delayed combustion and burnout of the pulverized coal flow and wall-attached combustion caused by intense collisions, thereby alleviating high-temperature corrosion of the water-cooled walls. Finally, by adjusting the secondary air damper, that is, by opening the secondary air damper in the main burner and reducing its swirl intensity to the minimum, sufficient oxygen is added at the initial stage of combustion, and the internal secondary air is mixed with the primary air in advance, thereby reducing the generation of H2S caused by incomplete combustion. For the burners close to the side walls, the external secondary air damper is opened and the swirl intensity is reduced to reduce its rotational carrying capacity for the pulverized coal airflow, thereby avoiding the pulverized coal airflow deflection and combustion causing corrosion. In addition, on the basis of ensuring the safe operation of the boiler heating surface, the wall damper is basically fully opened to add sufficient oxygen to the dead zone of the flow on both sides of the boiler wall, and an effective protective film is formed on the surface of the water-cooled wall, which effectively protects the boiler water-cooled wall.

[0017] Therefore, the present invention does not require equipment modification. It only needs to control the sulfur content of the coal entering the furnace and optimize and adjust the primary air speed, coal powder fineness and uniformity, the excess air coefficient of the main burner area, the wall damper, the secondary air damper in the burner and the swirl intensity. It can improve boiler combustion, reduce the generation of corrosive gas H2S, and reduce high-temperature corrosion of the water-cooled wall. The operation is simple and can reduce O2≮1.0%, H2S≯200ppm, and CO≯0.5% in the atmosphere near the water-cooled wall, thereby meeting the safe operation requirements of the boiler.

[0018] After adopting the adjustment scheme provided by the present invention, it is estimated that within a 5-year overhaul cycle, a single 600MW unit can save about 3 million to 8 million yuan in coal inspection, maintenance and tube replacement costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 The present invention is a flow chart of an adjustment method for reducing high-temperature corrosion of the water-cooled wall of a counter-firing boiler.

[0021] Figure 2 This is a structural block diagram of an adjustment device for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to the present invention. DETAILED DESCRIPTION

[0022] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0023] In the description of the present invention, it is to be understood that when used in this specification and the appended claims, the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0026] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Example 1 The present invention provides an adjustment method for reducing high-temperature corrosion of the water-cooled wall of a counter-fired boiler, comprising the following steps: 1) Test the quality of coal entering the furnace and control the sulfur content of the coal entering the furnace t,ar ≤0.7%; 2) Adjust the separator baffle or speed of the coal mill to control the coal fineness to 8-16% (lean coal boiler) and 16-22% (bituminous coal boiler) to avoid high water wall temperature due to delayed combustion; 3) Adjust the ventilation volume of the coal mill and control the primary air speed of each burner layer to 22-24m / s to prevent the primary air flow of the front and rear walls from strongly colliding and diffusing in the middle of the furnace wall, and burning against the wall, which may cause high-temperature corrosion in the middle of the side wall water-cooled wall; 4) Adjust the boiler operating oxygen content, secondary air box opening and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; 5) For boilers with wall-mounted air nozzles installed on the front and rear walls, adjust the wall-mounted air damper opening to 70-100% when the boiler load is above 80% ECR during operation; 6) Adjust the secondary air swirl angle of the main burner to 0° to wrap the pulverized coal airflow, and keep the secondary air door opening at 100%; 7) Adjust the external secondary air swirl angle of the main burners near the two side walls to 0-10° (the swirl intensity is maximum at 60°) to reduce the rotation and diffusion of the secondary air flow and strengthen the protection of the side wall water-cooled wall; 8) After adjustment, the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

[0029] In this embodiment, in step 1), the total sulfur content in the coal is determined according to the "Determination of Total Sulfur in Coal" (GB / T214-2007). The "Determination of Total Sulfur in Coal" specifies three methods for determining total sulfur in coal: the Aesculapius method, the coulometric titration method, and the high-temperature combustion neutralization method. The Aesculapius method involves mixing a coal sample with an Aesculapius reagent and burning it. The sulfur in the coal forms sulfate, which is then precipitated as barium sulfate by the sulfate ions. The total sulfur content in the coal is calculated based on the mass of the barium sulfate. In the coulometric titration method, the coal sample is burned and decomposed in an air stream under the action of a catalyst. The sulfur in the coal forms sulfur oxides, of which sulfur dioxide is absorbed by a potassium iodide solution. Iodine generated by electrolysis of the potassium iodide solution is then titrated, and the total sulfur content in the coal is calculated based on the amount of electricity consumed during the electrolysis. The high-temperature combustion neutralization method is to burn the coal sample at high temperature in an oxygen flow, so that all forms of sulfur in the coal are oxidized and decomposed into sulfur oxides, which are then captured in a hydrogen peroxide solution to form a sulfuric acid solution, which is titrated with a sodium hydroxide solution to calculate the total sulfur content in the coal sample.

[0030] In this embodiment, in step 1), if the coal fed into the furnace is mixed coal and the sulfur content of different coal types varies greatly, it is recommended to adopt a premixed combustion method to avoid severe high-temperature corrosion of the boiler water-cooled wall.

[0031] In this embodiment, in step 2), the uniformity index n of the coal powder fineness must be no less than 1.0.

[0032] In this embodiment, in step 4), the damper opening of the secondary air box of the main burner is adjusted. When the boiler load is above 80% ECR, the secondary air box opening should be no less than 70%.

[0033] In this embodiment, in step 5), the adjustment of the wall damper opening should be based on the principle that the adjustment does not cause overheating of the heating surface tube wall such as screen overheating or high overheating.

[0034] In this embodiment, the boiler is a front and rear wall counter-fired boiler, which is also applicable to a pulverized coal boiler with two side wall counter-fired arrangements.

[0035] In this embodiment, in step 7), the main burners adjacent to the two side walls are in the first row adjacent to the left and right side walls of the boiler, and are generally arranged in 5 or 6 layers.

[0036] Example 2 A power plant in Tianjin had a 530MW opposed-fired boiler burning a mixed coal with a sulfur content of approximately 0.45%. During operation, the water-cooled walls on both sides suffered from severe high-temperature corrosion. To improve this condition, the power plant mainly adopted the following technical steps: 1) Install an asymmetric high-speed wall-mounted air system at the front and rear corners of the burner elevations on the upper, middle, and lower levels of the power plant, and maintain an opening of 100% when the load is above 80% ECR; 2) Adjust the opening of the separator baffle at the coal mill outlet to control the coal powder fineness to about 20%; 3) Adjust the secondary air opening and swirl intensity of the boiler main burner, fully open the secondary air damper of the burner, and adjust the secondary air swirl angle to the minimum of 0°; 4) Reduce the swirl angle of the secondary air outside the burners on the two side walls to 10°, and increase the opening of the external secondary air door to 100%.

[0037] After the adjustment, the O2 content in the atmosphere near the water-cooled wall increased from <1.0% to above 2.0%, the H2S content decreased from 500-600ppm to below 200ppm, and the CO concentration decreased to below 0.5%. The amount of tube replacement and overhaul and maintenance required for the boiler due to high-temperature corrosion was greatly reduced.

[0038] Example 3 A power plant in Gansu province had a 350MW opposed-fired boiler burning Xinjiang high-alkali coal with a sulfur content of approximately 0.55% and local low-ash melting point bituminous coal. During operation, the water-cooled walls on both sides suffered from severe high-temperature corrosion. To improve this condition, the power plant implemented the following technical measures: 1) Increase the operating oxygen content from the usual 2.5% to 3.0%, increase the secondary air box opening from 50% to 100% when the load is above 85%, reduce the burnout damper opening from 100% to 50%, increase the air supply to the main burner area, and increase the excess air coefficient of the main burner area from 0.7 to 0.85; 2) Reduce the primary air volume to near the design value, and reduce the burner nozzle velocity from 26m / s to 24m / s. This not only reduces the collision of the primary air flow with the middle of the furnace wall, but also strengthens the mixing of the primary air and secondary air due to the weakened primary air rigidity, reducing the generation of H2S. 3) Adjust the opening of the secondary air damper outside the main burner from the small opening setting of 60 / 50 / 50 / 60% to 90 / 50 / 50 / 90%. The secondary air volume increases, the swirl is minimized, and the airflow deflection to the wall is reduced. 4) When designing the boiler, four layers of wall-mounted air are set at the front and rear corners of the middle elevation of the reduction zone at the third burner level and above. The air source is taken from the secondary air. When adjusting, the wall-mounted air opening is adjusted from 0% to 100% to increase the air supply in the dead zone and form an air film to protect the water-cooled wall.

[0039] After the adjustment, the H2S content in the atmosphere near the water-cooled wall was reduced from 700-800ppm to below 200ppm, and the CO concentration was reduced to below 0.5%. The amount of tube replacement and maintenance required for the boiler due to high-temperature corrosion was greatly reduced.

[0040] Example 4 like Figure 2 As shown, the present invention provides an adjustment device for reducing high-temperature corrosion of the water-cooled wall of a counter-fired boiler, comprising: The coal quality testing unit is used to test the coal quality and control the sulfur content of the coal. t,ar ≤0.7%; The separator adjustment unit adjusts the separator baffle or speed of the coal mill to control the coal powder fineness at 8-22%; The ventilation volume regulating unit adjusts the ventilation volume of the coal mill and controls the primary air speed of the burners on each layer to 22-24m / s; The comprehensive regulation unit adjusts the boiler operating oxygen content, secondary air box opening, and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; The wall damper opening adjustment unit is used to adjust the wall damper opening to 70-100% when the boiler load is above 80% ECR for boilers with wall air nozzles installed on the front and rear walls. The internal secondary air adjustment unit adjusts the internal secondary air swirl angle of the main burner to 0°, wrapping the pulverized coal airflow and maintaining the internal secondary air door opening at 100%; External secondary air adjustment unit, adjusts the external secondary air swirl angle of the main burners near the two side walls to 0-10°; Confirm the unit and adjust it so that the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

[0041] In summary, the present invention controls the sulfur content of the coal entering the furnace by testing it; adjusting the opening or speed of the pulverizer separator baffle and the ventilation volume to adjust the primary air velocity, coal powder fineness, and uniformity index of each layer of the burner to the required range; adjusting the boiler's operating oxygen content, secondary air box opening, and burnout damper opening to control the excess air coefficient of the main burner area; adjusting the internal and external secondary air openings and swirl intensity of the boiler's main burner, fully opening the secondary air damper inside the burner, adjusting the internal secondary air swirl angle to the minimum, reducing the external secondary air swirl angle of the burner near the two side walls, and increasing the external secondary air volume. After the adjustment, the deflection of the coal powder airflow to the wall is reduced, the air supply in the initial stage of combustion is increased, and the generation of H2S is reduced. At the same time, the air supply volume to offset the dead zone of the boiler flow and the isolation ability of the wall-adhering air film against the deflection of the coal powder airflow to the wall are also increased.

[0042] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0043] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A method for reducing high-temperature corrosion of the water-cooled wall of a counter-fired boiler, characterized in that: The following steps are involved: 1) Test the quality of coal entering the furnace and control the sulfur content of the coal entering the furnace t,ar ≤0.7%; 2) Adjust the separator baffle or speed of the coal mill to control the coal powder fineness at 8-22%; 3) Adjust the ventilation volume of the coal mill and control the primary air speed of each burner layer to 22-24m / s; 4) Adjust the boiler operating oxygen content, secondary air box opening and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; 5) For boilers with wall-mounted air nozzles installed on the front and rear walls, adjust the wall-mounted air damper opening to 70-100% when the boiler load is above 80% ECR during operation; 6) Adjust the secondary air swirl angle of the main burner to 0° to wrap the pulverized coal airflow, and keep the secondary air door opening at 100%; 7) Adjust the external secondary air swirl angle of the main burner near the two side walls to 0-10°; 8) After adjustment, the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

2. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 1), the total sulfur content in coal is determined according to GB / T214-2007 "Determination of total sulfur in coal".

3. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 1), if the coal fed into the furnace is mixed coal and the sulfur content of different types of coal varies greatly, a premixed and blended combustion method is adopted.

4. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 2), the uniformity index of the coal powder fineness is not less than 1.

0.

5. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 2), for lean coal boilers, the pulverized coal fineness is controlled at 8-16%, and for bituminous coal boilers, the pulverized coal fineness is controlled at 16-22%.

6. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 4), the damper opening of the secondary air box of the main burner is adjusted. When the boiler load is above 80% ECR, the secondary air box opening is not less than 70%.

7. The method for reducing high-temperature corrosion of water-cooled walls of opposed-firing boilers according to claim 1, characterized in that: In step 5), the wall damper opening is adjusted to ensure that the adjustment does not cause overheating of the screen or the heating surface tube wall.

8. The method for reducing high-temperature corrosion of the water-cooled wall of an opposed-firing boiler according to claim 1, characterized in that: In step 7), the main burners on both side walls are in the first row on the left and right sides of the boiler and are arranged in 5 or 6 layers.

9. The method for reducing high-temperature corrosion of water-cooled walls of opposed-firing boilers according to claim 1, characterized in that: The boiler used in this method is a front and rear wall counter-combustion boiler, or a pulverized coal boiler with two side walls counter-combusting.

10. An adjustment device for reducing high temperature corrosion of the water-cooled wall of an opposed-firing boiler, characterized in that: include: The coal quality testing unit is used to test the coal quality and control the sulfur content of the coal. t,ar ≤0.7%; The separator adjustment unit adjusts the separator baffle or speed of the coal mill to control the coal powder fineness at 8-22%; The ventilation volume regulating unit adjusts the ventilation volume of the coal mill and controls the primary air speed of the burners on each layer to 22-24m / s; The comprehensive regulation unit adjusts the boiler operating oxygen content, secondary air box opening, and burnout damper opening to control the excess air coefficient of the main burner area within the range of 0.85-0.95; The wall damper opening adjustment unit is used to adjust the wall damper opening to 70-100% when the boiler load is above 80% ECR for boilers with wall air nozzles installed on the front and rear walls. The internal secondary air adjustment unit adjusts the internal secondary air swirl angle of the main burner to 0°, wrapping the pulverized coal airflow and maintaining the internal secondary air door opening at 100%; External secondary air adjustment unit, adjusts the external secondary air swirl angle of the main burners near the two side walls to 0-10°; Confirm the unit and adjust it so that the O2 in the atmosphere near the water-cooled wall of the main burner area of the boiler is ≥1.0%, H2S ≤200ppm, and CO ≥0.5%.

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