Stop and standby protection structure of header system drum boiler and method of stop and standby protection structure

Abstract

The invention discloses a shutdown and standby protection structure and method for a header system drum boiler, and belongs to the technical field of boiler shutdown and standby protection. An air inlet pipeline is arranged on a regular blowdown main pipe of the drum boiler, and a nitrogen or oil-free compressed air quick connector is arranged on the air inlet pipeline; a detection pipeline is arranged on a water supply main pipe and a superheated steam main pipe of the drum boiler, a sampling connection short pipe is arranged on the detection pipeline, and a detection sampling valve is arranged on a pipeline of the sampling connection short pipe. The waste heat of the boiler system is utilized to ensure that residual water in the boiler system is completely vaporized, then industrial nitrogen or oil-free compressed air is used for replacing residual water vapor in the boiler, and the relative humidity of air in the boiler is reduced to 60% or below within a short time and is kept stable; the metal inner wall of a water vapor system of the boiler is ensured to form a compact protective film in a dry state for a long time under an alkaline condition, corrosion is prevented when the boiler is stopped and standby, and the method is suitable for short-term and long-term stop and standby protection of the header-system drum boiler.

Description

Technical Field

[0001] The invention relates to the technical field of boiler shutdown and standby protection, and more specifically to a shutdown and standby protection structure of a main pipe drum boiler and a method thereof. Background Art

[0002] The methods of shutdown (standby) protection can be roughly divided into two categories: full water protection and dry protection. Full water protection is to fill the boiler with a protective aqueous solution to prevent oxygen in the air from entering the boiler. Dry protection is to keep the metal surface of the boiler dry at all times to prevent corrosion. For the main tube drum boiler, the commonly used shutdown (standby) protection methods have shortcomings and unsatisfactory effects. Full water protection is not suitable for equipment corrosion protection during maintenance, and there are difficulties in environmental protection treatment after the discharge of the protective liquid; when the main tube boiler is shut down alone, it is difficult to completely discharge the moisture in the furnace, and the relative humidity is usually above 70%, which cannot meet the implementation conditions of dry protection.

[0003] At present, the commonly used shutdown (standby) protection methods for mother tube boilers include hot boiler water discharge waste heat drying method, ammonia water alkalization drying method, ammonia-hydrazine method, film-forming amine method, etc. Other protection methods are rarely used due to cumbersome operation, difficult implementation, and high cost. The hot boiler water discharge waste heat drying method is suitable for the protection of boilers during short-term shutdown (generally within one week), but not suitable for long-term shutdown. When the mother tube boiler is shut down and protected by ammonia water alkalization drying method, it is difficult to ensure that all the water vapor in the furnace is discharged. After implementation, the relative humidity of the air in the boiler basically does not reach below 70%. When the temperature in the boiler drops to close to the ambient temperature, the remaining water vapor in the boiler condenses into water again, resulting in the protective film formed in the boiler under alkaline conditions. It is difficult to maintain a dense state under high humidity conditions, and the long-term protection effect is very limited. When the mother tube boiler is shut down and protected by film-forming amine (usually n-octadecylamine), n-octadecylamine is basically insoluble in water, which can easily cause blockage of the dosing pipe and pump body during the dosing, and it is impossible to deliver a sufficient amount of reagents to the boiler within the specified time. In addition, during the shutdown of the mother tube boiler, the water vapor circulation in the system is not smooth, and the added n-octadecylamine is difficult to form a uniform protective film in the system, resulting in a very unstable protection effect. In the event of a boiler failure or emergency shutdown, the protection effect of the film-forming amine method is even worse. In short, there is currently a lack of simple and effective mother tube boiler shutdown and standby protection methods. Summary of the invention

[0004] 1. Technical problem to be solved by the invention

[0005] Aiming at the defects and deficiencies existing in the prior art, the present invention provides a standby protection structure and method for a header-type steam drum boiler. The present invention utilizes the waste heat of the boiler system to ensure that all the residual water in the boiler system is vaporized, and then replaces the residual water vapor in the furnace with industrial nitrogen or oil-free compressed air, so that the relative humidity of the air in the furnace is reduced to below 60% in a short time and maintained stably, ensuring that a dense protective film is formed on the inner wall of the metal of the boiler water-vapor system under alkaline conditions and is in a dry state for a long time, achieving the purpose of preventing corrosion during the standby period of the boiler. The system of the present invention is simple and easy to operate, and is applicable to the short-term and long-term standby protection of header-type steam drum boilers.

[0006] 2. Technical solution

[0007] To achieve the above object, the technical solution provided by the present invention is as follows:

[0008] A standby protection structure for a header-type steam drum boiler of the present invention includes a steam drum. One end of the steam drum is connected to an economizer, one end of the economizer is connected to a feed water pipe, and a detection pipe is provided on the pipeline of the feed water pipe;

[0009] The other end of the steam drum is connected to a superheater, one end of the superheater is connected to a superheated steam header, and a detection pipe is also provided on the pipeline of the superheated steam header;

[0010] A sampling primary valve and a sampling secondary valve are sequentially connected to the detection pipe. A sampling connection short pipe is provided between the sampling primary valve and the sampling secondary valve. A detection sampling valve is provided on the pipeline of the sampling connection short pipe, and a detection box connection port is provided at one side port of the sampling connection short pipe;

[0011] One end of the detection box connection port is connected to a detection box body through a hose. The two ends of the detection box body are respectively connected to an inlet short pipe and an outlet short pipe. A pick-and-place door is provided on the surface of the detection box body, and a thermometer and a hygrometer are respectively provided in the detection box body.

[0012] Further, two detection sampling valves are serially provided on the pipeline of the sampling connection short pipe.

[0013] Further, one end of the detection box connection port is connected to the inlet short pipe of the detection box body through a hose.

[0014] Further, the detection box body is made of plexiglass material and has a volume of 10 - 50 L.

[0015] Further, a downcomer and a water wall are respectively connected to the bottom of the steam drum. The bottom of the water wall is connected to a lower header. One end of the lower header is connected to the downcomer through a pipeline, and the other end of the lower header is connected to a regular blowdown pipeline.

[0016] Further, a blowdown valve is provided on the pipeline of the regular blowdown pipeline. One end of the regular blowdown pipeline is provided with a regular blowdown port. A nitrogen filling short pipe is provided on the pipeline of the regular blowdown pipeline, and a nitrogen filling valve is provided on the pipeline of the nitrogen filling short pipe.

[0017] Further, two groups of nitrogen filling valves are connected in series on the pipeline of the nitrogen filling short pipe. Both groups of nitrogen filling valves are high-pressure stop valves. A quick connector is provided at the input end of the nitrogen filling short pipe. The nitrogen filling short pipe can be connected to the industrial nitrogen main pipe through the quick connector and a hose.

[0018] A method for the shutdown and standby protection structure of a header-type steam drum boiler, the steps are as follows:

[0019] Step 1: Check the preparatory work before protection;

[0020] Step 2: Carry out the boiler shutdown protection operation:

[0021] A. 1-2 hours before the boiler is shut down, increase the ammonia addition amount of the boiler feed water to keep the pH value of the boiler feed water between 9.5 and 10.0;

[0022] B. Reduce the phosphate content in the boiler water, control the phosphate dosing amount in the boiler water according to the specified lower limit, and maintain the qualified pH value of the boiler water;

[0023] C. Measure the pH values of the boiler feed water, boiler water, and steam every 15 minutes. When the pH value of the boiler saturated steam reaches between 9.2 and 9.6, the boiler is ready for shutdown and can start to shut down;

[0024] D. After the boiler is shut down, quickly close all the air dampers and baffles of the boiler, seal the furnace to prevent the heat from dissipating too quickly. When the steam drum naturally depressurizes to 0.8 MPa, carry out hot boiler water discharge. During the water discharge process, fully open the air valve, exhaust valve, and drain valve;

[0025] E. Connect the nitrogen filling short pipe at the bottom of the boiler. The sampling connection short pipes on the feed water pipeline and the superheated steam main pipe are connected to the detection box body through the detection box connection port and a hose;

[0026] F. After the water discharge is completed, close the drain valve, close the chemical sampling secondary valve and the boiler dosing valve, open the nitrogen filling valve at the bottom of the boiler and slowly fill in nitrogen, and maintain the nitrogen within the range of 0.01 MPa - 0.03 MPa;

[0027] G. When the humidity meter in the detection box body on the feed water pipeline and the superheated steam main pipe shows that the humidity drops below 90%, gradually close the air valve, exhaust valve, and continuous blowdown valve of the boiler; continue to fill in nitrogen until the humidity meters in the detection box bodies on the feed water pipeline and

[0028] the superheated steam main pipe all show that the humidity drops below 60%, then close the nitrogen filling valve, air valve, exhaust valve, and detection sampling valve, and remove the connecting hose, and the operation is completed.

[0029] Further, Step 1 includes the following preparatory work:

[0030] Check whether the ammonia addition system for the decommissioned boiler feed water is in good condition, whether there is sufficient ammonia water and it has been transported to the site;

[0031] Check whether the nitrogen filling system for the decommissioned boiler is in good condition and whether nitrogen has been sent to the front of the furnace;

[0032] Prepare the detection box body, thermometer and hygrometer for standby.

[0033] 3. Beneficial effects

[0034] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects:

[0035] According to the basic principle of preventing corrosion during the shutdown and standby of the boiler, and combining the characteristics of the common ammonia water alkalization drying protection method and nitrogen filling protection method for thermal equipment during shutdown (standby), before the shutdown of the header type steam drum boiler, by increasing the ammonia addition amount of the boiler feed water, a dense protective film is formed on the inner wall of the metal of the boiler water-vapor system under alkaline conditions. After the boiler is shut down, hot boiler water drainage is adopted, and by using the waste heat of the boiler system, it is ensured that all the residual water in the boiler system is vaporized. Then, industrial nitrogen or oil-free compressed air is used to displace the residual water vapor in the furnace, and the relative humidity of the air in the furnace is reduced to below 60% in a short time and maintained stably, ensuring that the dense protective film formed on the inner wall of the metal of the boiler water-vapor system under alkaline conditions is in a dry state for a long time, achieving the purpose of preventing corrosion during the shutdown and standby of the boiler. The system of the present invention is simple, easy to operate, and applicable to the short-term and long-term shutdown and standby protection of the header type steam drum boiler. Description of the drawings

[0036] Figure 1 is the overall structure diagram of the present invention;

[0037] Figure 2 is the structure diagram of the detection box body of the present invention.

[0038] In the figure: 1. Steam drum; 2. Economizer; 3. Feed water pipeline; 4. Detection pipeline; 400. Sampling connection short pipe; 4001. Detection sampling valve; 4002. Detection box connection port; 401. Sampling primary valve; 402. Sampling secondary valve; 403. Detection box body; 4031. Inlet short pipe; 4032. Outlet short pipe; 4033. Access door; 4034. Thermometer; 4035. Hygrometer; 5. Superheater; 6. Superheated steam main pipe; 7. Downcomer; 8. Water wall; 9. Lower header; 10. Regular blowdown pipeline; 1001. Blowdown valve; 1002. Regular blowdown port; 11. Nitrogen filling short pipe; 1101. Nitrogen filling valve; 1102. Quick coupling. Detailed implementation manners

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0040] Embodiment 1

[0041] From Figure 1 It can be seen that a standby protection structure for a header-type steam drum boiler in this embodiment includes a steam drum 1. One end of the steam drum 1 is connected to an economizer 2, one end of the economizer 2 is connected to a feed water pipe 3, and a detection pipe 4 is arranged on the pipeline of the feed water pipe 3;

[0042] The other end of the steam drum 1 is connected to a superheater 5, one end of the superheater 5 is connected to a superheated steam header 6, and a detection pipe 4 is also arranged on the pipeline of the superheated steam header 6;

[0043] A sampling primary valve 401 and a sampling secondary valve 402 are sequentially connected to the detection pipe 4. A sampling connection short pipe 400 is arranged between the sampling primary valve 401 and the sampling secondary valve 402. A detection sampling valve 4001 is arranged on the pipeline of the sampling connection short pipe 400, and a detection box connection port 4002 is arranged at one side port of the sampling connection short pipe 400;

[0044] From Figure 2 It can be seen that one end of the detection box connection port 4002 is connected to a detection box body 403 through a hose. The detection box body 403 is made of plexiglass material and has a volume of 10 - 50 L;

[0045] The two ends of the detection box body 403 are respectively connected to an inlet short pipe 4031 and an outlet short pipe 4032. A pick-up door 4033 is arranged on the surface of the detection box body 403. A thermometer 4034 and a hygrometer 4035 are respectively arranged inside the detection box body 403. It adopts a portable and easy-to-pick-up design for easy observation.

[0046] Two detection sampling valves 4001 are serially arranged on the pipeline of the sampling connection short pipe 400; to prevent internal leakage of the valve from affecting the normal operation of the boiler, one end of the detection box connection port 4002 is connected to the inlet short pipe 4031 of the detection box body 403 through a hose.

[0047] Embodiment 2

[0048] From Figure 1 It can be seen that for a standby protection structure of a header-type steam drum boiler in this embodiment, a downcomer 7 and a water wall 8 are respectively connected to the bottom of the steam drum 1. The bottom of the water wall 8 is connected to a lower header 9. One end of the lower header 9 is connected to the downcomer 7 through a pipeline, and the other end of the lower header 9 is connected to a regular blowdown pipeline 10.

[0049] The pipeline of the regular blowdown pipeline 10 is provided with a blowdown valve 1001. One end of the regular blowdown pipeline 10 is provided with a regular blowdown port 1002. A nitrogen charging short pipe 11 is arranged on the pipeline of the regular blowdown pipeline 10, and a nitrogen charging valve 1101 is arranged on the pipeline of the nitrogen charging short pipe 11.

[0050] Two groups of nitrogen charging valves 1101 are connected in series on the pipeline of the nitrogen charging short pipe 11 to prevent internal leakage of the valve from affecting the normal operation of the boiler. Both groups of nitrogen charging valves 1101 are high-pressure stop valves. A quick coupling 1102 is arranged at the input end of the nitrogen charging short pipe 11. The nitrogen charging short pipe 11 can be connected to the industrial nitrogen main pipe through the quick coupling 1102 and a flexible hose.

[0051] During nitrogen charging, it is connected to the industrial nitrogen (or oil-free compressed air) main pipe through a flexible hose. After nitrogen charging is completed, the connection is disconnected to prevent the safety of the industrial nitrogen (or oil-free compressed air) main pipe from being endangered by internal leakage of the high-pressure stop valve during boiler operation.

[0052] One to two hours before the shutdown of the header type steam drum boiler, by increasing the ammonia addition amount of the boiler feed water, adjust the pH value of the boiler feed water between 9.5 and 10.0. When the continuously detected pH value of the boiler saturated steam reaches between 9.2 and 9.6, the boiler is ready for shutdown and can start to shut down. When the boiler pressure drops to 0.8 Mpa, perform hot boiler water drainage, and use the waste heat of the boiler to vaporize all the residual water vapor in the furnace. At the same time, connect the boiler nitrogen charging flexible hose.

[0053] After the water drainage is completed, slowly fill the furnace with industrial nitrogen (or oil-free compressed air) from the lower header 9 of the boiler to displace the residual water vapor in the furnace. At the sampling connection short pipe at the inlet of the economizer 2 in the boiler site and the superheated steam, connect the sampling detection box body 403 through a flexible hose. A portable thermometer 4034 and a hygrometer 4035 are placed in the box. When the relative humidity of the exhaust steam at each sampling port drops below 60%, the inflation valves, exhaust valves, and sampling valves can be closed, and the nitrogen charging flexible hose and the sampling detection flexible hose can be disconnected, and the operation is completed.

[0054] Example 3

[0055] From Figure 1 It can be seen that a method for the shutdown and standby protection structure of a header type steam drum boiler in this embodiment is as follows: Its steps are:

[0056] Step 1: Check the preparatory work before protection; the protection scope is the steam-water system of the header type boiler body;

[0057] The following preparatory work is included:

[0058] Check whether the ammonia addition system of the shutdown boiler feed water is in good condition, whether the ammonia water is sufficient and transported to the site;

[0059] Check whether the nitrogen charging system of the shutdown boiler is in good condition and whether the nitrogen has been sent to the front of the furnace; the nitrogen charging system can be replaced by the compressed air system;

[0060] The detection box body 403, thermometer 4034 and hygrometer 4035 are in reserve.

[0061] Step 2: Conduct the boiler shutdown protection operation:

[0062] A. Before the boiler shuts down for 1 - 2 hours, increase the ammonia addition amount in the boiler feed water to maintain the pH value of the boiler feed water between 9.5 and 10.0.

[0063] B. Reduce the phosphate content in the boiler water. Control the phosphate dosing amount in the boiler water according to the lower limit specified in the "GB∕T 12145-2016 Water Quality Standards for Steam Power Equipment and Feed Water in Thermal Power Generating Units" and maintain the qualified pH value of the boiler water.

[0064] C. Measure the pH values of the boiler feed water, boiler water, and steam every 15 minutes. When the pH value of the boiler saturated steam reaches between 9.2 and 9.6, the boiler is ready for shutdown and shutdown can begin.

[0065] D. After shutdown, quickly close all the air dampers and baffles of the boiler, seal the furnace to prevent excessive heat dissipation. When the natural pressure of the steam drum 1 drops to 0.8 MPa, conduct hot boiler water drainage. During the drainage process, fully open the air valve, exhaust valve, and drainage valve.

[0066] E. Connect the nitrogen filling short pipe 11 at the bottom of the boiler. The sampling connection short pipes 400 on the feed water pipe 3 and the superheated steam main pipe 6 are connected to the detection box body 403 through the detection box connection port 4002 and the hose.

[0067] F. After the water drainage is completed, close the drainage valve, close the chemical sampling secondary valve 402 and the boiler dosing valve, open the nitrogen filling valve 1101 at the bottom of the boiler and slowly fill in nitrogen (or compressed air) to maintain the nitrogen (or compressed air) within the range of 0.01 MPa - 0.03 MPa.

[0068] G. When the humidity shown by the hygrometer 4035 in the detection box body 403 on the feed water pipe 3 and the superheated steam main pipe 6 drops below 90%, gradually close the air valve, exhaust valve, and continuous blowdown valve of the boiler; continue to fill in nitrogen until the humidity shown by the hygrometer 4035 in the detection box body 403 on the feed water pipe 3 and the superheated steam main pipe 6 both drop below 60%, then close the nitrogen filling valve 1101, air valve, exhaust valve, and detection sampling valve 4001, and remove the connection hose. The operation is completed.

[0069] The specific operation cases according to the above method are as follows: There are 5 boilers and 3 turbines in a certain plant area, which are connected by a header system. When a boiler is shut down alone, the shutdown (standby) protection plan is implemented according to the above method. One hour before the boiler is shut down, the pH value of the feed water is adjusted to 9.5 - 9.6, and the pH value of the saturated steam is greater than 9.2, and then wait for the boiler to be shut down. When the drum pressure drops to 0.8 MPa, start the hot boiler water draining operation. When the boiler water is completely drained, slowly send nitrogen into the boiler bottom header through the DN20 nitrogen pipeline. After 2 hours, it is detected that the relative humidity of the air at the outlet of the boiler superheated steam drops below 60%, which is lower than the requirement that the relative humidity of the air inside the boiler should not be higher than 70% during boiler shutdown as specified by the drying method. And because the furnace is filled with nitrogen, during the subsequent shutdown period, external water vapor and oxygen in the air cannot enter at the same time, and corrosion is difficult to occur, and the protection effect is good.

[0070] According to the basic principle of preventing corrosion during boiler shutdown and standby, and combining the characteristics of the common ammonia water alkalization drying protection method and nitrogen filling protection method during the shutdown (standby) period of thermal equipment, before the shutdown of the header system drum boiler, by increasing the ammonia addition amount of the boiler feed water, a dense protective film is formed on the inner wall of the metal of the boiler water vapor system under alkaline conditions. After the boiler is shut down, hot boiler water draining is adopted, and by using the waste heat of the boiler system, it is ensured that all the residual water in the boiler system is vaporized. Then, industrial nitrogen or oil-free compressed air is used to displace the residual water vapor in the furnace, and the relative humidity of the air in the furnace is reduced below 60% in a short time and maintained stably, ensuring that the dense protective film formed on the inner wall of the metal of the boiler water vapor system under alkaline conditions is in a dry state for a long time, achieving the purpose of preventing corrosion during boiler shutdown and standby. The system of the present invention is simple and easy to operate, and is applicable to the short-term and long-term shutdown and standby protection of the header system drum boiler.

[0071] The above schematically describes the present invention and its implementation manners. This description is not restrictive, and only one of the implementation manners of the present invention is shown in the drawings. The actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments to this technical solution without creative work without departing from the purpose of the present invention creation, they shall fall within the protection scope of the present invention.

Claims

1. A shutdown and standby protection structure for a header-type boiler drum boiler, including a boiler drum (1), characterized in that: One end of the steam drum (1) is connected to an economizer (2), one end of the economizer (2) is connected to a feed water pipe (3), and a detection pipeline (4) is arranged on the pipeline of the feed water pipe (3); The other end of the steam drum (1) is connected to a superheater (5), one end of the superheater (5) is connected to a superheated steam main pipe (6), and a detection pipeline (4) is also arranged on the pipeline of the superheated steam main pipe (6); A sampling primary valve (401) and a sampling secondary valve (402) are successively connected to the detection pipeline (4). A sampling connection short pipe (400) is arranged between the sampling primary valve (401) and the sampling secondary valve (402). A detection sampling valve (4001) is arranged on the pipeline of the sampling connection short pipe (400), and a detection box connection port (4002) is arranged at one side port of the sampling connection short pipe (400); One end of the detection box connection port (4002) is connected to a detection box body (403) through a hose. An inlet short pipe (4031) and an outlet short pipe (4032) are respectively connected to both ends of the detection box body (403). A pick-and-place door (4033) is arranged on the surface of the detection box body (403), and a thermometer (4034) and a hygrometer (4035) are respectively arranged in the detection box body (403).

2. The standby protection structure of a header-type steam drum boiler according to claim 1, characterized in that: Two detection sampling valves (4001) are connected in series on the pipeline of the sampling connection short pipe (400).

3. The standby protection structure of a header type steam drum boiler according to claim 2, characterized in that: One end of the detection box connection port (4002) is connected to the inlet short pipe (4031) of the detection box body (403) through a hose.

4. The standby protection structure of a header-type steam drum boiler according to claim 3, characterized in that: The detection box body (403) is made of plexiglass material with a volume of 10 - 50L.

5. A standby protection structure for a header-type steam drum boiler according to claim 1, characterized in that: The bottom of the steam drum (1) is respectively connected to a downcomer (7) and a water wall (8). The bottom of the water wall (8) is connected to a lower header (9). One end of the lower header (9) is connected to the downcomer (7) through a pipeline, and the other end of the lower header (9) is connected to a regular blowdown pipeline (10).

6. The standby protection structure of a header-type steam drum boiler according to claim 5, characterized in that: A blowdown valve (1001) is arranged on the pipeline of the regular blowdown pipeline (10). One end of the regular blowdown pipeline (10) is provided with a regular blowdown port (1002). A nitrogen filling short pipe (11) is arranged on the pipeline of the regular blowdown pipeline (10), and a nitrogen filling valve (1101) is arranged on the pipeline of the nitrogen filling short pipe (11).

7. A standby protection structure for a header-type steam drum boiler according to claim 6, characterized in that: Two groups of nitrogen filling valves (1101) are connected in series on the pipeline of the nitrogen filling short pipe (11). Both groups of nitrogen filling valves (1101) are high-pressure stop valves. A quick connector (1102) is arranged at the input end of the nitrogen filling short pipe (11). The nitrogen filling short pipe (11) can be connected to an industrial nitrogen main pipe through the quick connector (1102) and a hose.

8. A method for the standby protection structure of a header-type steam drum boiler according to claim 1, characterized in that: The steps are as follows: Step 1: Check the preparations before protection; Step 2: Perform the boiler shutdown protection operation: A. 1 - 2 hours before the boiler stops operating, increase the ammonia addition amount in the boiler feed water to keep the pH value of the boiler feed water between 9.5 and 10.0; B. Reduce the phosphate content in the boiler water, control the phosphate dosing amount in the boiler water according to the specified lower limit, and maintain the qualified pH value of the boiler water; C. Measure the pH values of boiler feed water, boiler water, and steam every 15 minutes. When the pH value of the boiler saturated steam reaches between 9.2 and 9.6, the boiler is ready for shutdown and the shutdown can begin. D. After shutdown, quickly close all the air dampers and baffles of the boiler, seal the furnace to prevent excessive heat dissipation. When the natural pressure of the steam drum (1) drops to 0.8 MPa, conduct hot boiler water drainage. During the drainage process, fully open the air valve, exhaust valve, and drainage valve. E. Connect the nitrogen filling short pipe (11) at the bottom of the boiler. The sampling connection short pipes (400) on the feed water pipe (3) and the superheated steam main pipe (6) are connected to the detection box body (403) through the detection box connection port (4002) and a flexible hose. F. After the water drainage is completed, close the drainage valve, close the chemical sampling secondary valve (402) and the boiler chemical dosing valve, open the nitrogen filling valve (1101) at the bottom of the boiler and slowly fill with nitrogen, maintaining the nitrogen pressure within the range of 0.01 MPa - 0.03 MPa. G. When the humidity meter (4035) in the detection box body (403) on the feed water pipe (3) and the superheated steam main pipe (6) shows that the humidity drops below 90%, gradually close the air valve, exhaust valve, and continuous blowdown valve of the boiler; continue to fill with nitrogen until the humidity meters (4035) in the detection box bodies (403) on the feed water pipe (3) and the superheated steam main pipe (6) both show that the humidity drops below 60%. Then close the nitrogen filling valve (1101), air valve, exhaust valve, and the detection sampling valve (4001), and remove the connecting hose. The operation is completed.

9. A method for the standby protection structure of a header-type steam drum boiler according to claim 1, characterized in that: The first step mentioned above includes the following preparatory work: Check whether the ammonia addition system for the boiler feed water of the out-of-service boiler is in good condition, whether there is sufficient ammonia water and it has been transported to the site; Check whether the nitrogen filling system of the out-of-service boiler is in good condition and whether the nitrogen has been delivered to the front of the furnace; Prepare the detection box body (403), thermometer (4034), and humidity meter (4035).

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