High-temperature corrosion prevention method and apparatus for water-cooled wall

Abstract

The present invention relates to the technical field of corrosion prevention for water-cooled walls, and in particular to a high-temperature corrosion prevention method and apparatus for a water-cooled wall. The apparatus comprises wall-attached air for isolating a water-cooled wall from contact with reducing gases, and an air jet apparatus, which can further maintain the momentum of the wall-attached air. In the high-temperature corrosion prevention method and apparatus for a water-cooled wall, a wall-attached air isolation layer is formed on the surface of a water-cooled wall to isolate reducing gases from contact with the water-cooled wall, thereby preventing the water-cooled wall from being corroded.

Description

A method and apparatus for preventing high-temperature corrosion of water-cooled walls Technical Field

[0001] This invention relates to the technical field of water-cooled wall corrosion prevention, and in particular to a method and apparatus for preventing high-temperature corrosion of water-cooled walls. Background Technology

[0002] Due to environmental standards and policies, almost all large-scale coal-fired power plant boilers in China have undergone low-NOx combustion system optimization retrofits. These systems reduce the excess air coefficient in the main combustion zone and then supplement it in the burnout air zone. While this reduces the NOx concentration at the furnace outlet, it significantly increases the concentration of reducing gases (CO, H2S) near the boiler water-cooled walls, while decreasing the oxygen (O2) concentration. This leads to severe high-temperature sulfur corrosion, causing the boiler water-cooled wall thickness to decrease at a rate of 2–5 mm / y, seriously threatening the safe operation of the power plant boiler. Therefore, this invention provides a method and apparatus for preventing high-temperature corrosion of water-cooled walls. Summary of the Invention

[0003] In view of the problems existing in the current water-cooled wall, the present invention is proposed.

[0004] Therefore, the purpose of this invention is to provide a method for preventing high-temperature corrosion of water-cooled walls, which aims to avoid corrosion of water-cooled walls.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preventing high-temperature corrosion of water-cooled walls, comprising,

[0006] Wall-mounted airflow used to isolate water-cooled walls from reducing gases; and

[0007] A jet device that can further maintain the wind power against the wall.

[0008] In a preferred embodiment of the water-cooled wall anti-high temperature corrosion method of the present invention, the wall-adhering air is denitrification flue gas generated by the boiler.

[0009] In a preferred embodiment of the water-cooled wall high-temperature corrosion prevention method of the present invention, the denitrification flue gas is extracted before entering the denitrification device.

[0010] As a preferred embodiment of the water-cooled wall high-temperature corrosion prevention method of the present invention, the wall-adhering air is a mixture of denitrification flue gas and hot secondary air.

[0011] As a preferred embodiment of the water-cooled wall anti-high temperature corrosion method of the present invention, the jetting device is a high temperature explosion-proof fan and connecting pipe, as well as a star-shaped wall-mounted air nozzle.

[0012] The high-temperature explosion-proof fan pressurizes the wall-mounted air and sprays it out through connecting pipes and star-shaped wall-mounted air nozzles to form an isolation layer on the surface of the water-cooled wall.

[0013] As a preferred embodiment of the water-cooled wall anti-high temperature corrosion method of the present invention, the connecting pipes are arranged in a matrix, the connecting pipes are located in the middle of the boiler, and the connecting pipes are provided with multiple layers, and each layer is provided with multiple extension channels close to the water-cooled wall. Star-shaped wall-mounted air nozzles are installed in the layers without extension channels.

[0014] The beneficial effect of this method is that by forming a wall-mounted wind isolation layer on the surface of the water-cooled wall, reducing gases are prevented from contacting the water-cooled wall, thereby avoiding corrosion of the water-cooled wall.

[0015] Another objective of this invention is to provide a device for preventing high-temperature corrosion of water-cooled walls, the purpose of which is to prevent water-cooled walls from being corroded.

[0016] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a water-cooled wall anti-high-temperature corrosion method, comprising a star-shaped wall-mounted air nozzle, which includes,

[0017] A mounting housing connected to an extension duct, with three air outlets located at the top of the mounting housing.

[0018] As a preferred embodiment of the water-cooled wall anti-high temperature corrosion device of the present invention, wherein: two air outlets located on the side of the mounting shell are rotatably disposed in the mounting shell, and the mounting shell is provided with adjustment components that are respectively connected to the two air outlets on the side;

[0019] The air outlet connected to the adjustment component includes an arc-shaped tube rotatably mounted on the mounting housing, and an expansion port located at the end of the arc-shaped tube.

[0020] As a preferred embodiment of the water-cooled wall high-temperature corrosion protection device of the present invention, the adjustment component includes: a spring piece disposed between the mounting shell and one side of the arc-shaped tube, a mounting cylinder disposed in the mounting shell, a telescopic rod slidably disposed in the mounting cylinder, a pressing block disposed at the end of the telescopic rod and abutting against the other side of the arc-shaped tube, an air inlet pipe disposed in the mounting cylinder, and a pressure relief hole disposed in the mounting cylinder;

[0021] The two air inlet pipes are connected to a manifold at their ends, and the manifold is connected to the high-temperature explosion-proof fan.

[0022] As a preferred embodiment of the water-cooled wall high-temperature corrosion protection device of the present invention, wherein: one end of the plurality of confluence pipes is connected to a second confluence pipe, and the second confluence pipe passes through the connecting pipe and is connected to the high-temperature explosion-proof fan;

[0023] The second manifold is equipped with a switch valve.

[0024] The beneficial effects of this invention are as follows: the jet rigidity is maintained to the maximum extent by optimizing the nozzle shape design; the coverage area of ​​the wall-mounted air is controlled by adjusting the angle of the star-shaped wall-mounted air nozzle, thereby improving the utilization efficiency of the wall-mounted air and reducing the adverse effects of the wall-mounted air system on the main combustion system. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the overall structure of the water-cooled wall anti-high temperature corrosion method of the present invention.

[0027] Figure 2 is a schematic diagram of the star-shaped wall-mounted air nozzle structure of the water-cooled wall anti-high temperature corrosion device of the present invention.

[0028] Figure 3 is a schematic diagram of the adjustment component structure of the water-cooled wall anti-high temperature corrosion device of the present invention.

[0029] Figure 4 is a schematic diagram of the second manifold structure of the water-cooled wall anti-high temperature corrosion device of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include the three-dimensional spatial dimensions of length, width, and depth.

[0034] Example 1, referring to Figure 1, is the first embodiment of the present invention, providing a method for preventing high-temperature corrosion of water-cooled walls, the method comprising:

[0035] The wall-mounted airflow used to isolate the water-cooled wall from the reducing gas and the jet device M that can further maintain the power of the wall-mounted airflow.

[0036] Among them, the wall-mounted air is the denitrification flue gas generated by the boiler.

[0037] The jet device M consists of a high-temperature explosion-proof fan 100, a connecting pipe 200, and a star-shaped wall-mounted air nozzle 300; the high-temperature explosion-proof fan 100 pressurizes the wall-mounted air and sprays it out through the connecting pipe 200 and the star-shaped wall-mounted air nozzle 300 to form an isolation layer on the surface of the water-cooled wall.

[0038] Furthermore, the connecting pipes 200 are arranged in a matrix. The connecting pipes 200 are located in the middle of the boiler and have multiple layers. Each layer has multiple extension channels 201 close to the water-cooled wall. Star-shaped wall-mounted air nozzles 300 are installed on the pipes 200 without extension channels 201.

[0039] During use, the denitrification flue gas is extracted by the high-temperature explosion-proof fan 100 and sprayed into the boiler through the connecting pipe 200 and the star-shaped wall-mounted air nozzle 300, forming an isolation layer on the surface of the water-cooled wall, thereby preventing the problem of high-temperature corrosion of the water-cooled wall by reducing gases.

[0040] Example 2, referring to Figure 1, is the second embodiment of the present invention. This embodiment differs from the first embodiment in that the denitrification flue gas is extracted before entering the denitrification device. The temperature of the denitrification flue gas at this stage is moderate, there are no large dust particles, and there is no excess ammonia. This not only prevents large dust particles from accumulating and clogging the distribution pipeline, but also prevents them from causing erosion, corrosion, and wear on the blades of the high-temperature explosion-proof fan.

[0041] The remaining structure is the same as that in Example 1.

[0042] Example 3, referring to Figure 1, is the third embodiment of the present invention. The difference between this embodiment and the second embodiment is that the wall-mounted air is a mixture of denitrification flue gas and hot secondary air.

[0043] The denitrification flue gas and hot secondary air are drawn separately by the high-temperature explosion-proof fan 100. The high-temperature explosion-proof fan 100 is equipped with a valve to control the extraction of the denitrification flue gas and hot secondary air.

[0044] Specifically, when the power plant boiler load exceeds 70% BMCR and the sulfur content of the incoming coal is <1%, the valve for generating denitrification flue gas is opened. Simultaneously, the high-temperature explosion-proof fan 100 is activated, distributing the denitrification flue gas to the star-shaped wall-mounted air nozzles 300 arranged on the furnace wall. At this time, the denitrification flue gas serves as the wall-mounted air source, with a temperature between 330 and 380℃, a pressure between 3 and 6 kPa, an oxygen content of 3% to 5%, a CO concentration ≤300 μL / L, and an H2S concentration of 0.

[0045] When the power plant boiler load exceeds 70% BMCR and the sulfur content of the incoming coal is ≥1%, the valves for the denitrification flue gas and hot secondary air are opened. Simultaneously, the high-temperature explosion-proof fan 100 is activated, distributing the mixed airflow to the star-shaped wall-mounted air nozzles 300 arranged on the furnace wall. At this time, the mixed airflow of denitrification flue gas and hot secondary air serves as the wall-mounted air source, with a temperature between 330 and 350°C, a pressure of 3 to 6 kPa, an oxygen content of 10% to 15%, and CO and H2S concentrations of 0.

[0046] The remaining structure is the same as that in Example 1.

[0047] The thickness of the isolation layer affects the corrosion resistance and the combustion efficiency inside the boiler. The calculation formula for the isolation layer is shown below:

[0048] Wherein, the thickness of the isolation layer is h, in meters (m); the ejection pressure of the star-shaped wall-mounted air nozzle 300 is P, in Pascals (Pa); the number of star-shaped wall-mounted air nozzles 300 in the same layer is N, and the distance between every two layers of star-shaped wall-mounted air nozzles 300 is L, in meters (m); the fluid velocity is v, the velocity of the fluid ejected from the star-shaped wall-mounted air nozzle 300, in meters per second (m / s); and the fluid density is ρ, the density of the fluid ejected from the star-shaped wall-mounted air nozzle 300, in kilograms per cubic meter (kg / m³). 3 The unit is ); the area covered by a 300mm star-shaped wall-mounted air nozzle is A, and the area covered by a single 300mm star-shaped wall-mounted air nozzle is expressed in square meters (m²). 2 The unit is t; the fluid interaction time is t, which is in seconds (s).

[0049] The table below shows the effects of the isolation layer on corrosion protection and boiler combustion efficiency under different boiler combustion conditions and varying basic sulfur content of the coal fed into the boiler:

[0050] Specifically, when the power plant boiler load is higher than 70% BMCR and the sulfur content of the coal received is less than 1%, the optimal isolation layer thickness is 3 mm; when the power plant boiler load is higher than 70% BMCR and the sulfur content of the coal received is greater than or equal to 1%, the optimal isolation layer thickness is 4 mm.

[0051] Comparative Example 1: This comparative example uses either secondary wind or primary wind as the wall-hugging wind.

[0052] Low pressure in primary or secondary air leads to low jet velocity and poor penetration of the air jet from the wall-mounted nozzles. Using primary or secondary air as the wall-mounted air source is ineffective with small volumes, while large volumes negatively impact the pulverizing system's output. Furthermore, using primary or secondary air as the wall-mounted air source, compared to the original combustion system, is equivalent to increasing unorganized air distribution, reducing hot air utilization efficiency, and weakening the guidance provided by instruments such as oxygen level meters for adjusting combustion conditions.

[0053] Comparative Example 2: The wall-mounted air arrangement in this comparative example is that the air is set at the four corners of the boiler or introduced from the middle of the furnace wall and jetted to both sides.

[0054] The proportional wall-mounted air arrangement is limited by the arrangement of secondary air ducts and cannot form a multi-point arrangement. Otherwise, pressure balance is easily formed, resulting in the airflow not being able to be ejected or the flow velocity being extremely low.

[0055] Example 4, referring to Figure 2, is the fourth embodiment of the present invention, providing a water-cooled wall high-temperature corrosion protection device. This device includes a star-shaped wall-mounted air nozzle 300, which includes...

[0056] The mounting housing 301 is connected to the extension duct, and three air outlets 302 are provided at the top of the mounting housing 301.

[0057] Two air outlets 302 located on the side of the mounting housing 301 are rotatably disposed in the mounting housing 301, and the mounting housing 301 is provided with adjustment components 303 that are respectively connected to the two air outlets 302 on the side.

[0058] The air outlet 302 connected to the adjustment component 303 includes an arc-shaped tube 302a rotatably mounted on the mounting housing 301, and an expansion port 302b located at the end of the arc-shaped tube 302a. The arc-shaped tube 302a and the mounting housing 301 are rotatably sealed, and when the arc-shaped tube 302a rotates, it can drive the direction of the expansion port 302b, thereby changing the angle of the air jet against the wall.

[0059] Traditional square nozzles are fixed and monotonous, failing to efficiently configure the wall-mounted airflow and hindering the maintenance of rigidity and velocity, essentially amounting to flooding. In contrast, the star-shaped wall-mounted air nozzle 300 allows for flexible adjustment of its direction and angle, enabling precise control and coverage based on the high-temperature corrosion zone and intensity of the boiler water-cooled wall. The star-shaped wall-mounted air nozzle 300 prioritizes maximizing jet rigidity through optimized nozzle design. By adjusting its angle, the coverage area of ​​the wall-mounted air is controlled, improving its utilization efficiency and reducing the adverse effects of the wall-mounted air system on the main combustion system.

[0060] Example 5, referring to Figures 3 and 4, is the fifth embodiment of the present invention. This embodiment differs from the fourth embodiment in that: the adjustment component 303 includes a spring piece 303a disposed between the mounting shell 301 and one side of the arc-shaped tube 302a, a mounting cylinder 303b disposed in the mounting shell 301, a telescopic rod 303c slidably disposed in the mounting cylinder 303b, a pressing block 303d disposed at the end of the telescopic rod 303c and abutting against the other side of the arc-shaped tube 302a, an air inlet pipe 303e disposed in the mounting cylinder 303b, and a pressure relief hole 303f disposed in the mounting cylinder 303b;

[0061] The ends of the two air inlet pipes 303e are connected to a manifold 304, which is connected to the high-temperature explosion-proof fan 100.

[0062] Furthermore, multiple manifold 1 304 ends are connected to manifold 2 305, which passes through connecting pipe 200 and connects to high temperature explosion-proof fan 100; manifold 2 305 is equipped with switch valve 306.

[0063] In the initial state, the spring 303a controls the arc-shaped tube 302a, causing the expansion port 302b to approach the central air outlet 302. When adjusting the angle of the expansion port 302b, simply open the switch valve 306. Under the action of the high-temperature explosion-proof fan 100, some of the wall-adhering air enters the second manifold 305, then enters the first manifold 304, and finally enters the mounting cylinder 303b through the inlet pipe 303e, increasing the air pressure inside the mounting cylinder 303b, thereby extruding... The pressure block 303d pushes out to squeeze the side of the arc-shaped tube 302a, causing the arc-shaped tube 302a to rotate. This causes the expansion port 302b to move away from the central air outlet 302, thus achieving angle adjustment. When the switch valve 306 is closed, the arc-shaped tube 302a returns to its initial state under the elastic force of the spring plate 303a, and the pressure block 303d retracts into the mounting cylinder 303b. At the same time, the gas in the mounting cylinder is discharged from the pressure relief hole 303f, which does not obstruct the retraction of the pressure block 303d.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method of high temperature corrosion prevention for water-cooled walls, characterized by: Comprising, a wall-attached air for isolating the water-cooled wall from the contact with the reducing gas; and a jet device (M) capable of further maintaining the wall-attached air power.

2. The method of high temperature corrosion protection for water walls according to claim 1, characterized in that: The wall-attached air is denitration flue gas generated by the boiler.

3. The method for preventing high-temperature corrosion of water-cooled walls according to claim 2, characterized in that: The denitration flue gas is extracted before entering the denitration device.

4. The method for preventing high-temperature corrosion of water-cooled walls according to claim 3, characterized in that: The wall-attached air is denitration flue gas mixed with hot secondary air.

5. The method of claim 1-4, wherein: The jet device (M) is a high-temperature explosion-proof fan (100) and a connecting pipeline (200), and a star-shaped wall-attached air nozzle (300). The high-temperature explosion-proof fan (100) pressurizes the wall-attached air and sprays it through the connecting pipeline (200) and the star-shaped wall-attached air nozzle (300) to form an isolation layer on the surface of the water-cooled wall.

6. The method of high temperature corrosion protection for water walls of claim 5, wherein: The connecting pipeline (200) is arranged in a matrix, located in the middle of the boiler, and is provided with multiple layers, and each layer is provided with multiple elongated channels (201) close to the water-cooled wall, and each elongated channel (201) is provided with a star-shaped wall-attached air nozzle (300).

7. A high temperature corrosion protection device for a water-cooled wall, characterized by: The star-shaped wall-attached air nozzle (300) according to claim 6 comprises, a mounting shell (301) connected with the elongated pipeline, and three air outlets (302) provided at the top end of the mounting shell (301).

8. The high temperature corrosion protection device for water cooled walls according to claim 7, characterized by: Two air outlets (302) located on the side of the mounting shell (301) are rotatably arranged in the mounting shell (301), and the mounting shell (301) is internally provided with an adjusting assembly (303) connected with the two air outlets (302) on the side. The air outlet (302) connected with the adjusting assembly (303) comprises an arc-shaped pipe (302a) rotatably arranged on the mounting shell (301), and an expansion port (302b) provided at the end of the arc-shaped pipe (302a).

9. The high temperature corrosion protection device for water cooled walls according to claim 8, characterized by: The adjusting assembly (303) comprises a spring sheet (303a) arranged between the mounting shell (301) and one side of the arc-shaped pipe (302a), a mounting cylinder (303b) arranged in the mounting shell (301), an extension rod (303c) slidably arranged in the mounting cylinder (303b), an extrusion block (303d) arranged at the end of the extension rod (303c) and abutting against the other side of the arc-shaped pipe (302a), an air inlet pipe (303e) arranged in the mounting cylinder (303b), and a pressure relief hole (303f) arranged in the mounting cylinder (303b). Two ends of the air inlet pipe (303e) are connected with a converging pipe one (304), and the converging pipe is connected with the high-temperature explosion-proof fan (100).

10. The high temperature corrosion protection device for water walls according to claim 9, characterized in that: Multiple converging pipe two (305) ends are connected with converging pipe two (305), and the converging pipe two (305) passes through the connecting pipeline (200) and is connected with the high-temperature explosion-proof fan (100). The converging pipe two (305) is provided with a switch valve (306).

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