Combustion system and method for preventing high-temperature sulfur corrosion of water cooling wall

Abstract

The invention discloses a combustion system and method for preventing high-temperature sulfur corrosion of a water cooling wall. The combustion system comprises a low-sulfur coal mill, a high-sulfur coal mill, a plurality of low-sulfur coal combustors and a plurality of high-sulfur coal combustors. The low-sulfur coal combustors are arranged on the two sides of the combustor area water cooling wall, and the high-sulfur coal combustors are arranged between the middle area of the combustor area water cooling wall and the low-sulfur coal combustors. Wherein the high-sulfur coal mill is connected with the high-sulfur coal combustors, and the low-sulfur coal mill is connected with the low-sulfur coal combustors. According to the low-sulfur coal / high-sulfur coal burner, an installation connector of an original turbulent burner can be directly utilized, large-scale transformation of a hearth structure is not needed, only a coal type supply pipeline of the burner needs to be adjusted, the technical transformation difficulty is low, and the low-sulfur coal / high-sulfur coal burner can be rapidly copied and applied to existing opposed firing boilers with different capacities in China; according to the opposed firing boiler, only one low-sulfur coal mill is arranged, the high-sulfur coal blending combustion proportion of the opposed firing boiler can be increased to the maximum extent, and compared with a conventional pulverized coal boiler, under the same as-fired coal sulfur content condition, the H2S atmosphere concentration of the wall face of the side wall water cooling wall can be remarkably reduced, and the side wall water cooling wall is prevented from being corroded by high-temperature sulfur.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power plant boiler technology, specifically relating to a combustion system and method for preventing high-temperature sulfur corrosion of water-cooled walls. Background Technology

[0002] During the long-term operation of coal-fired power plant boilers, high-temperature corrosion of the heating surfaces is a core technical challenge that restricts equipment service life, threatens the safe and stable operation of the unit, and increases maintenance costs. Based on the differences in corrosion mechanisms and product composition, it is generally accepted in the industry that this type of corrosion is mainly divided into three categories: sulfide type, sulfate type, and chloride type. Among them, sulfate corrosion is mostly concentrated in the superheater and reheater areas where the tube wall temperature is 400-700℃. Its formation depends on the reaction of SO3 generated by fuel combustion with metal oxides (such as Fe2O3) on the tube wall to form sulfates such as ferric sulfate (Fe2(SO4)3). When the tube wall temperature is in the sulfate melting range (approximately 550-700℃), the molten sulfate will destroy the dense oxide protective film on the tube wall surface, leading to continuous erosion of the metal substrate. However, because this type of corrosion occurs in a clearly defined area and has a fixed temperature window, it can be specifically controlled by selecting alloy tubes resistant to high-temperature sulfate corrosion (such as TP347H). Existing technologies already provide mature solutions.

[0003] Chloride corrosion is mainly related to chlorine in fuels (such as organic and inorganic chlorine in coal). HCl gas generated during combustion can react with metals to form volatile chlorides (such as FeCl2 and FeCl3), and these chlorides significantly lower the melting point of metal oxides (e.g., reducing the melting point of Fe2O3 from 1565℃ to below 800℃), accelerating the corrosion process. However, this type of corrosion occurs very rarely in pure coal-fired power plants (where the chlorine content in coal is usually <0.1%), and is only prominent in mixed fuel power plants burning waste, biomass, etc., with a chlorine content >0.5%. Therefore, it is not the mainstream corrosion problem in pure coal-fired power plant boilers.

[0004] Unlike the two types of corrosion mentioned above, sulfide corrosion is the most prevalent form of corrosion in the water-cooled walls (especially the sidewall water-cooled walls) of coal-fired power plant boilers. To control high-temperature sulfur corrosion of water-cooled walls, existing technologies mainly employ the following three schemes, but all have significant limitations: Source control method (limiting the sulfur content of the coal fed into the boiler): This is currently the most widely used scheme. The industry generally believes that when the sulfur content of the coal fed into the boiler is controlled below 1%, the amount of H2S generated can be reduced to a safe threshold (H2S volume fraction on the wall < 300 ppm), and the corrosion rate can be controlled within 0.1 mm / year. However, in the current coal market, low-sulfur high-quality coal (sulfur content < 1%) reserves account for only 15% of the total national coal reserves, and its price is 20%-40% higher than high-sulfur coal (sulfur content > 1.5%). Fuel costs account for 60%-80% of the total operating costs of coal-fired power plants. Especially for large power plants with an installed capacity of ≥ 600 MW, if low-sulfur coal is used exclusively, the average annual fuel cost will increase by tens of millions of yuan. Material upgrade method (using corrosion-resistant pipes): By replacing the water-cooled wall pipes with corrosion-resistant alloys containing Cr and Ni (such as 12Cr1MoVG, TP304H), the resistance to sulfide corrosion can be improved. However, this solution has two major drawbacks: First, the cost is extremely high. The price of corrosion-resistant alloy pipes is 3-5 times that of ordinary 20G steel, and the water-cooled wall retrofit of a single 600MW boiler requires an additional investment of tens of millions of yuan. Second, the retrofit is difficult. Replacing the water-cooled walls of boilers already in operation requires a shutdown of 1-2 months, and the welding process of alloy pipes is complex and prone to welding defects, making it unsuitable for old boilers that have been in operation for more than 3 years. Operational optimization methods (furnace air distribution / calcium injection adjustment): Some power plants attempt to eliminate the reducing zone in the furnace by increasing the secondary air supply, but this method leads to an increase in boiler flue gas temperature (usually 5-10℃) and a decrease in boiler thermal efficiency of 0.3%-0.8%, which in turn increases energy costs. Other power plants use furnace calcium injection desulfurization technology, which can reduce SO2 emissions, but the CaSO4 generated by the reaction of CaO and SO2 is prone to slagging on the surface of water-cooled walls, affecting heat exchange efficiency, and cannot specifically reduce the H2S concentration on the wall surface, with a control effect of less than 20% on sulfide corrosion.

[0005] In summary, existing technologies cannot simultaneously address the dual requirements of "fuel cost control" and "high-temperature sulfur corrosion prevention and control of the water-cooled sidewalls of offset combustion boilers" in high-sulfur coal co-firing scenarios. Source control methods fail due to cost pressures, while material upgrades and operational optimization methods suffer from low efficiency and high cost. Furthermore, existing technologies have not developed specific solutions for the independent flare structure of offset combustion boilers. Therefore, developing a novel combustion system that addresses the high-temperature sulfur corrosion problem of the water-cooled sidewalls of offset combustion boilers, precisely reduces the H2S concentration on the sidewall surface, and is adaptable to high-sulfur coal co-firing has become an urgent technical challenge in the field of coal-fired power plant boilers. Summary of the Invention

[0006] To address the problem of high-temperature sulfur corrosion of the sidewall water-cooled wall in a counter-firing boiler, the present invention aims to provide a combustion system and method for preventing high-temperature sulfur corrosion of the water-cooled wall. This method can reduce the H2S atmosphere concentration and prevent high-temperature sulfur corrosion of the sidewall water-cooled wall under full load conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A combustion system for preventing high-temperature corrosion of water-cooled walls, characterized in that it includes a low-sulfur coal mill, a high-sulfur coal mill, a plurality of low-sulfur coal burners and a plurality of high-sulfur coal burners; the low-sulfur coal burners are arranged on both sides of the water-cooled wall in the burner area, and the high-sulfur coal burners are arranged in the middle area of ​​the water-cooled wall in the burner area between the low-sulfur coal burners and the low-sulfur coal burners.

[0009] The high-sulfur coal mill is connected to each high-sulfur coal burner, and the low-sulfur coal mill is connected to each low-sulfur coal burner.

[0010] Furthermore, the low-sulfur coal burner includes a first low-sulfur coal burner, a second low-sulfur coal burner, a third low-sulfur coal burner, a fourth low-sulfur coal burner, a fifth low-sulfur coal burner, and a sixth low-sulfur coal burner.

[0011] The high-sulfur coal burners include the first high-sulfur coal burner, the second high-sulfur coal burner, the third high-sulfur coal burner, the fourth high-sulfur coal burner, the fifth high-sulfur coal burner, the sixth high-sulfur coal burner, the seventh high-sulfur coal burner, the eighth high-sulfur coal burner, the ninth high-sulfur coal burner, the tenth high-sulfur coal burner, the eleventh high-sulfur coal burner, and the twelfth high-sulfur coal burner.

[0012] Furthermore, H2S online monitoring devices are installed in the upper side wall water-cooled wall area of ​​the third and sixth low-sulfur coal burners.

[0013] Furthermore, the high-sulfur coal mill includes a first high-sulfur coal mill, a second high-sulfur coal mill, and a third high-sulfur coal mill. The first high-sulfur coal mill is connected to the first, second, third, and fourth high-sulfur coal burners. The second high-sulfur coal mill is connected to the fifth, sixth, seventh, and eighth high-sulfur coal burners. The third high-sulfur coal mill is connected to the ninth, tenth, eleventh, and twelfth high-sulfur coal burners.

[0014] Furthermore, the low-sulfur coal mill is connected to each low-sulfur coal burner via pulverized coal pipelines, and relevant shut-off valves are installed on the pulverized coal pipelines.

[0015] Furthermore, the shut-off gates include the first shut-off gate, the second shut-off gate, the third shut-off gate, the fourth shut-off gate, the fifth shut-off gate, and the sixth shut-off gate.

[0016] Furthermore, a first shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the first low-sulfur coal burner; a second shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the second low-sulfur coal burner; a third shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the third low-sulfur coal burner; a fourth shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the fourth low-sulfur coal burner; a fourth shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the fifth low-sulfur coal burner; and a sixth shut-off valve is installed on the pulverized coal pipeline between the low-sulfur coal mill and the sixth low-sulfur coal burner.

[0017] Furthermore, the first high-sulfur coal mill, the second high-sulfur coal mill, the third high-sulfur coal mill, and the low-sulfur coal mill are all medium-speed coal mills.

[0018] The first high-sulfur coal mill, the second high-sulfur coal mill, the third high-sulfur coal mill, and the low-sulfur coal burner are all swirl burners.

[0019] A combustion method for preventing high-temperature corrosion of water-cooled walls based on the system includes the following steps:

[0020] The pulverized coal produced by the high-sulfur coal mill and the low-sulfur coal mill is fed into several high-sulfur coal burners and low-sulfur coal burners respectively through pulverized coal pipelines.

[0021] When a high-sulfur coal burner in a certain layer is put into operation, open the shut-off valve on the pulverized coal inlet pipe of the low-sulfur coal burner in that layer.

[0022] The dry ash-free sulfur content of coal milled by low-sulfur coal mills should be controlled below 0.3%.

[0023] The dry ash-free sulfur content of coal milled by high-sulfur coal mills is increased to over 1%.

[0024] By adjusting the coal feed rate of the high-sulfur coal mill and the low-sulfur coal mill, the sulfur content of the coal fed into the boiler can be increased to more than 1% under full load conditions.

[0025] When the sulfur content of high-sulfur coal exceeds 3%, the sulfur content of low-sulfur coal is reduced to 0.1% to ensure that the H2S concentration on the water-cooled wall surface is reduced to below 100ppm under full load conditions.

[0026] Compared with the prior art, the present invention has the following technical effects:

[0027] The low-sulfur / high-sulfur coal burner used in this invention can directly utilize the existing swirl burner's installation interface, without requiring large-scale modifications to the furnace structure. Only the coal supply pipeline of the burner needs adjustment, making the technical modification difficult. It can be quickly replicated and applied to existing offset combustion boilers of different capacities, such as 300MW, 600MW, and 1000MW, in China. By arranging the low-sulfur coal burner on both sides of the water-cooled wall in the burner area and the high-sulfur coal burner in the middle area of ​​the water-cooled wall between the low-sulfur coal burner and the burner, only one low-sulfur coal mill is needed to maximize the proportion of high-sulfur coal blending in the offset combustion boiler. Compared with conventional pulverized coal boilers, under the same sulfur content of the coal entering the furnace, it can significantly reduce the H2S atmosphere concentration on the side wall water-cooled wall surface, preventing high-temperature sulfur corrosion of the side wall water-cooled wall. This not only meets the cost control requirements under high-sulfur coal blending but also fundamentally reduces the risk of high-temperature sulfur corrosion of the side wall water-cooled wall in offset combustion boilers, providing a practical and feasible technical solution for the safe, economical, and efficient operation of coal-fired power plant boilers.

[0028] Furthermore, this invention allows the pulverized coal from the burner near the side wall to exit from a low-sulfur coal mill, and through a shut-off valve installed on the pipeline, it can effectively control the H2S atmosphere concentration on the water-cooled wall under different load conditions and different numbers of operating coal mills.

[0029] Furthermore, the present invention can control the H2S atmosphere concentration on the sidewall water-cooled wall surface by dynamically adjusting the sulfur content of low-sulfur coal and the coal feed rate, thereby preventing high-temperature sulfur corrosion of the sidewall water-cooled wall under full load conditions. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the result of a high-sulfur coal co-firing combustion system for preventing high-temperature corrosion of water-cooled walls according to the present invention;

[0031] Among them: 1-Low-sulfur coal mill, 2-First high-sulfur coal mill, 3-Second high-sulfur coal mill, 4-Third high-sulfur coal mill, 5-First low-sulfur coal burner, 6-Second low-sulfur coal burner, 7-Third low-sulfur coal burner, 8-Fourth low-sulfur coal burner, 9-Fifth low-sulfur coal burner, 10-Sixth low-sulfur coal burner, 11-First high-sulfur coal burner, 12-Second high-sulfur coal burner, 13-Third high-sulfur coal burner, 14-Fourth high-sulfur coal mill Burners, 15-Fifth high-sulfur coal burner, 16-Sixth high-sulfur coal burner, 17-Seventh high-sulfur coal burner, 18-Eighth high-sulfur coal burner, 19-Ninth high-sulfur coal burner, 20-Tenth high-sulfur coal burner, 21-Eleventh high-sulfur coal burner, 22-Twelfth high-sulfur coal burner, 23-First shut-off valve, 24-Second shut-off valve, 25-Third shut-off valve, 26-Fourth shut-off valve, 27-Fifth shut-off valve, 28-Sixth shut-off valve. Detailed Implementation

[0032] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0038] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this 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.

[0039] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0040] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0041] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0042] like Figure 1As shown, a combustion system for preventing high-temperature corrosion of water-cooled walls according to the present invention includes a low-sulfur coal mill 1, high-sulfur coal burners (a first high-sulfur coal mill 2, a second high-sulfur coal mill 3, and a third high-sulfur coal mill 4), several low-sulfur coal burners (a first low-sulfur coal burner 5, a second low-sulfur coal burner 6, a third low-sulfur coal burner 7, a fourth low-sulfur coal burner 8, a fifth low-sulfur coal burner 9, and a sixth low-sulfur coal burner 10), and several high-sulfur coal burners (a first high-sulfur coal burner 11, a second high-sulfur coal burner 12, a third high-sulfur coal burner 13, a fourth high-sulfur coal burner 14, a fifth high-sulfur coal burner 15, a sixth high-sulfur coal burner 16, a seventh high-sulfur coal burner 17, an eighth high-sulfur coal burner 18, a ninth high-sulfur coal burner 19, a tenth high-sulfur coal burner 20, and an eleventh high-sulfur coal burner 21). Coal burner 21 is connected to the twelfth high-sulfur coal burner 22; the first high-sulfur coal mill 2, the second high-sulfur coal mill 3, and the third high-sulfur coal mill 4 are respectively connected to several high-sulfur coal burners through pulverized coal pipelines, and the low-sulfur coal mill 1 is connected to several low-sulfur coal burners through pulverized coal pipelines. Specifically, the first high-sulfur coal mill 2 is connected to the first high-sulfur coal burner 11, the second high-sulfur coal burner 12, the third high-sulfur coal burner 13, and the fourth high-sulfur coal burner 14; the second high-sulfur coal mill 3 is connected to the fifth high-sulfur coal burner 15, the sixth high-sulfur coal burner 16, the seventh high-sulfur coal burner 17, and the eighth high-sulfur coal burner 18; the third high-sulfur coal mill 4 is connected to the ninth high-sulfur coal burner 19, the tenth high-sulfur coal burner 20, the eleventh high-sulfur coal burner 21, and the twelfth high-sulfur coal burner 22.

[0043] High-sulfur coal burners are arranged in the middle of the water-cooled wall of the burner area and between the low-sulfur coal burners; low-sulfur coal burners are arranged on both sides of the water-cooled wall (front wall or rear wall) of the burner area.

[0044] The low-sulfur coal mill 1 and the pulverized coal pipelines of each low-sulfur coal burner are equipped with shut-off valves (first shut-off valve 23, second shut-off valve 24, third shut-off valve 25, fourth shut-off valve 26, and sixth shut-off valve 28), which are only opened when the low-sulfur coal burner of that layer is put into operation. Specifically, a first shut-off valve 23 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the first low-sulfur coal burner 5; a second shut-off valve 24 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the second low-sulfur coal burner 6; a third shut-off valve 25 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the third low-sulfur coal burner 7; a fourth shut-off valve 26 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the fourth low-sulfur coal burner 8; a fourth shut-off valve 26 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the fifth low-sulfur coal burner 9; and a sixth shut-off valve 28 is installed on the pulverized coal pipeline between the low-sulfur coal mill 1 and the sixth low-sulfur coal burner 10.

[0045] The first high-sulfur coal mill 2, the second high-sulfur coal mill 3, the third high-sulfur coal mill 4, and the low-sulfur coal mill 1 are all medium-speed coal mills; the high-sulfur coal burner and the low-sulfur coal burner are both swirl burners, suitable for counter-current combustion boilers.

[0046] An online H2S monitoring device is installed in the upper side wall water-cooled wall area of ​​the third low-sulfur coal burner 7 and the sixth low-sulfur coal burner 10 to monitor the concentration of H2S atmosphere attached to the wall.

[0047] The present invention provides a method for preventing high-temperature corrosion of water-cooled walls based on the aforementioned device, comprising the following steps:

[0048] (1) Coal powder ground by several high-sulfur coal mills (1 to 3 of the first high-sulfur coal mill 2, the second high-sulfur coal mill 3, and the third high-sulfur coal mill 4) and low-sulfur coal mill 1 is fed into several high-sulfur coal burners (first high-sulfur coal burner 11, second high-sulfur coal burner 12, third high-sulfur coal burner 13, fourth high-sulfur coal burner 14, fifth high-sulfur coal burner 15, sixth high-sulfur coal burner 16, seventh high-sulfur coal burner 17, eighth high-sulfur coal burner 18, ninth high-sulfur coal burner 19, tenth high-sulfur coal burner 20, eleventh high-sulfur coal burner 21 and twelfth high-sulfur coal burner 22) and low-sulfur coal burners (first low-sulfur coal burner 5, second low-sulfur coal burner 6, third low-sulfur coal burner, fourth low-sulfur coal burner 8, fifth low-sulfur coal burner 9 and sixth low-sulfur coal burner 10) through coal powder pipelines.

[0049] (2) When a certain layer of high-sulfur coal burner (such as the burner corresponding to the first high-sulfur coal mill 2 at the bottom layer, including the first high-sulfur coal burner 11, the second high-sulfur coal burner 12, the third high-sulfur coal burner 13, and the fourth high-sulfur coal burner 14) is put into operation, the shut-off valves (such as the first shut-off valve 23 and the fourth shut-off valve 26) on the inlet pulverized coal pipeline of the low-sulfur coal burner at that layer are opened.

[0050] (3) The ash-free sulfur content of the coal ground by the low-sulfur coal mill 1 is controlled to be below 0.3% (e.g., 0.2%).

[0051] (4) It can increase the dry ash-free sulfur content of coal ground by high-sulfur coal mill to more than 1% (e.g., 1.8%).

[0052] (5) Adjusting the coal feed rate of the high-sulfur coal mill and the low-sulfur coal mill 1 can increase the sulfur content of the coal fed into the boiler to more than 1% under full load conditions (e.g., if the high-sulfur coal and low-sulfur coal are 70t / h and 50t / h respectively, the sulfur content of the coal fed into the boiler can be increased to 1.13%); as the load decreases, the proportion of high-sulfur coal blending can be further increased (for every 10% reduction in rated load of the unit, the sulfur content of the coal fed into the boiler can be increased by 0.1 percentage points);

[0053] (6) When the sulfur content of high-sulfur coal is too high (e.g., exceeding 3%), the sulfur content of low-sulfur coal can be further reduced (e.g., reduced to 0.1%) to ensure that the H2S atmosphere concentration on the water-cooled wall surface is reduced to below 100ppm under full load conditions (obtained through the H2S online monitoring device) to prevent high-temperature sulfur corrosion of the water-cooled wall.

[0054] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A combustion system for preventing high-temperature corrosion of water-cooled walls, characterized in that, It includes a low-sulfur coal mill (1), a high-sulfur coal mill, several low-sulfur coal burners and several high-sulfur coal burners; the low-sulfur coal burners are arranged on both sides of the water-cooled wall of the burner area, and the high-sulfur coal burners are arranged in the middle area of ​​the water-cooled wall of the burner area between the low-sulfur coal burners. Among them, the high-sulfur coal mill is connected to each high-sulfur coal burner, and the low-sulfur coal mill (1) is connected to each low-sulfur coal burner.

2. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 1, characterized in that, The low-sulfur coal burners include a first low-sulfur coal burner (5), a second low-sulfur coal burner (6), a third low-sulfur coal burner (7), a fourth low-sulfur coal burner (8), a fifth low-sulfur coal burner (9), and a sixth low-sulfur coal burner (10). The high-sulfur coal burners include the first high-sulfur coal burner (11), the second high-sulfur coal burner (12), the third high-sulfur coal burner (13), the fourth high-sulfur coal burner (14), the fifth high-sulfur coal burner (15), the sixth high-sulfur coal burner (16), the seventh high-sulfur coal burner (17), the eighth high-sulfur coal burner (18), the ninth high-sulfur coal burner (19), the tenth high-sulfur coal burner (20), the eleventh high-sulfur coal burner (21), and the twelfth high-sulfur coal burner (22).

3. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 2, characterized in that, H2S online monitoring devices are installed in the upper side wall water-cooled wall area of ​​the third low-sulfur coal burner (7) and the sixth low-sulfur coal burner (10).

4. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 2, characterized in that, The high-sulfur coal mill includes a first high-sulfur coal mill (2), a second high-sulfur coal mill (3), and a third high-sulfur coal mill (4). The first high-sulfur coal mill (2) is connected to the first high-sulfur coal burner (11), the second high-sulfur coal burner (12), the third high-sulfur coal burner (13), and the fourth high-sulfur coal burner (14). The second high-sulfur coal mill (3) is connected to the fifth high-sulfur coal burner (15), the sixth high-sulfur coal burner (16), the seventh high-sulfur coal burner (17), and the eighth high-sulfur coal burner (18). The third high-sulfur coal mill (4) is connected to the ninth high-sulfur coal burner (19), the tenth high-sulfur coal burner (20), the eleventh high-sulfur coal burner (21), and the twelfth high-sulfur coal burner (22).

5. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 2, characterized in that, The low-sulfur coal mill (1) is connected to each low-sulfur coal burner through a pulverized coal pipeline, and relevant shut-off valves are installed on the pulverized coal pipeline.

6. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 5, characterized in that, The shut-off gates include the first shut-off gate (23), the second shut-off gate (24), the third shut-off gate (25), the fourth shut-off gate (26), the fourth shut-off gate (26), and the sixth shut-off gate (28).

7. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 6, characterized in that, A first shut-off valve (23) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the first low-sulfur coal burner (5). A second shut-off valve (24) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the second low-sulfur coal burner (6). A third shut-off valve (25) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the third low-sulfur coal burner (7). A fourth shut-off valve (26) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the fourth low-sulfur coal burner (8). A fourth shut-off valve (26) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the fifth low-sulfur coal burner (9). A sixth shut-off valve (28) is installed on the pulverized coal pipeline between the low-sulfur coal mill (1) and the sixth low-sulfur coal burner (10).

8. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 1, characterized in that, The first high-sulfur coal mill (2), the second high-sulfur coal mill (3), the third high-sulfur coal mill (4), and the low-sulfur coal mill (1) are all medium-speed coal mills.

9. The combustion system for preventing high-temperature corrosion of water-cooled walls according to claim 1, characterized in that, Both high-sulfur coal burners and low-sulfur coal burners are swirl burners.

10. A combustion method for preventing high-temperature corrosion of water-cooled walls according to any one of claims 1-9, characterized in that, Includes the following steps: The pulverized coal produced by the high-sulfur coal mill and the low-sulfur coal mill is fed into several high-sulfur coal burners and low-sulfur coal burners respectively through pulverized coal pipelines. When a high-sulfur coal burner in a certain layer is put into operation, open the shut-off valve on the pulverized coal inlet pipe of the low-sulfur coal burner in that layer. The dry ash-free sulfur content of coal milled by low-sulfur coal mills should be controlled below 0.3%. The dry ash-free sulfur content of coal milled by high-sulfur coal mills is increased to over 1%. By adjusting the coal feed rate of the high-sulfur coal mill and the low-sulfur coal mill, the sulfur content of the coal fed into the boiler can be increased to more than 1% under full load conditions. When the sulfur content of high-sulfur coal exceeds 3%, the sulfur content of low-sulfur coal is reduced to 0.1% to ensure that the H2S concentration on the water-cooled wall surface is reduced to below 100ppm under full load conditions.

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