An ammonia oxygen adding system and method for a water vapor system of a thermal power plant

Abstract

This invention discloses an ammonia-oxygen addition system for a steam-water system in a thermal power plant, comprising: an ammonia source; an ammonia-water solution stored in the ammonia source, the outlet of the ammonia source being connected to the inlet of an ammonia addition branch, the outlet of the ammonia addition branch being connected to the first inlet of a mixing branch; an oxygen source storing oxygen, the outlet of the oxygen source being connected to the inlet of an oxygen addition branch, the outlet of the oxygen addition branch being connected to the second inlet of the mixing branch; the outlet of the mixing branch being connected to the inlet of a mixing device, the outlet of the mixing device being connected to the steam-water system of the thermal power plant via an output branch; a mixing device including an atomizing nozzle; the atomizing nozzle being disposed at the upper interior of the mixing tank, the inlet of the atomizing nozzle being connected to the outlet of the mixing branch; and a stirrer disposed at the bottom interior of the mixing tank. This invention ensures corrosion and scale prevention of the equipment by organically integrating the ammonia addition pipeline and the oxygen addition pipeline, and the device has a simple structure, is easy to operate, and facilitates later maintenance.

Description

Technical Field

[0001] This invention belongs to the field of equipment corrosion prevention technology in the thermal power generation industry, and specifically relates to an ammonia-oxygen addition system and method for the water-steam system of thermal power plants. Background Technology

[0002] Currently, supercritical or ultra-supercritical units are the main units for building a clean and efficient power generation system. Under the circumstances of coal blending, large-scale grid connection of new energy sources, and frequent peak-shaving start-ups and shutdowns, the thermal equipment of supercritical or ultra-supercritical units faces technical challenges in corrosion and scale prevention. Chemical corrosion prevention or oxygenation corrosion prevention are commonly used corrosion prevention methods for thermal equipment in thermal power plants.

[0003] Chemical corrosion prevention involves continuously adding a chemical solution at a certain concentration to the feed water or boiler water. First, the scale inhibitor is prepared into a solution of a certain concentration and then quantitatively added through a dosing device. Because the concentration of the added solution remains uniform and various water quality indicators remain stable, it can effectively play the role of corrosion and scale prevention. Oxygen-based corrosion prevention involves adding an appropriate amount of oxygen to the water-steam system, which causes a dense metal oxide film to form on the metal surface of the thermal equipment, thereby achieving the effect of corrosion and scale prevention. Most existing technologies use separate dosing and oxygenation devices to achieve the purpose of chemical corrosion prevention and oxygenation corrosion prevention at the same time. However, due to the large size of the equipment, it requires a lot of space and has the disadvantages of complicated operation procedures, high maintenance difficulty, and high safety hazards. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides an ammonia-oxygen addition system and method for a steam-water system in a thermal power plant, in order to solve the technical problems that existing independent chemical dosing devices and oxygenation devices are large in size, require a large space, and have complex operating procedures, high maintenance difficulty, and high safety hazards.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides an ammonia-oxygen addition system for a steam-water system in a thermal power plant, comprising an ammonia source, an ammonia addition branch, an oxygen source, an oxygen addition branch, a mixing branch, a mixing device, and an output branch; The ammonia source stores an ammonia solution, and the outlet of the ammonia source is connected to the inlet of the ammonia addition branch, the outlet of the ammonia addition branch is connected to the first inlet of the mixing branch; the oxygen source stores oxygen, and the outlet of the oxygen source is connected to the inlet of the oxygen addition branch, the outlet of the oxygen addition branch is connected to the second inlet of the mixing branch. The outlet end of the mixing branch is connected to the inlet end of the mixing device, and the outlet end of the mixing device is connected to the water and steam system of the thermal power plant through the output branch. The mixing device includes a mixing tank, an atomizing nozzle, and a stirrer; the atomizing nozzle is located at the upper interior of the mixing tank, and the inlet end of the atomizing nozzle is connected to the outlet end of the mixing branch; the stirrer is located at the bottom interior of the mixing tank.

[0006] Furthermore, the ammonia charging branch includes a first electric shut-off valve, a first booster pump, a first manual shut-off valve, a second electric shut-off valve, and a first check valve; The inlet of the first electric shut-off valve is connected to the outlet of the ammonia source. The outlet of the first electric shut-off valve is connected to the inlet of the first booster pump. The outlet of the first booster pump is connected to the inlet of the first manual shut-off valve. The outlet of the first manual shut-off valve is connected to the inlet of the second electric shut-off valve. The outlet of the second electric shut-off valve is connected to the inlet of the first check valve. The outlet of the first check valve is connected to the first inlet of the mixing branch.

[0007] Furthermore, the ammonia charging branch also includes a first flow meter; the first flow meter is disposed between the second electric shut-off valve and the first check valve.

[0008] Furthermore, the ammonia source is an ammonia tank, which is equipped with a first level gauge; the oxygen source is an oxygen cylinder.

[0009] Furthermore, the oxygen supply branch includes an air compressor, a second manual shut-off valve, a third electric shut-off valve, and a second check valve; the inlet end of the air compressor is connected to the outlet end of the oxygen source, the outlet end of the air compressor is connected to the inlet end of the second manual shut-off valve, the outlet end of the second manual shut-off valve is connected to the inlet end of the third electric shut-off valve, the outlet end of the third electric shut-off valve is connected to the inlet end of the second check valve, and the outlet end of the second check valve is connected to the second inlet end of the mixing branch.

[0010] Furthermore, the oxygen supply branch also includes a pressure reducing valve and a pressure regulating valve; the pressure reducing valve and the pressure regulating valve are sequentially arranged between the outlet end of the oxygen source and the inlet end of the air compressor.

[0011] Furthermore, the oxygenation branch also includes a second flow meter; the second flow meter is disposed between the third electric shut-off valve and the second check valve.

[0012] Furthermore, the output branch includes a third flow meter, a second booster pump, a primary manual shut-off valve, a secondary manual shut-off valve, and a third check valve; the inlet of the second booster pump is connected to the outlet of the mixing device, the outlet of the second booster pump is connected to the inlet of the primary manual shut-off valve, the outlet of the primary manual shut-off valve is connected to the inlet of the secondary manual shut-off valve, the outlet of the secondary manual shut-off valve is connected to the inlet of the third check valve, and the outlet of the third check valve is used to connect to the water and steam system of the thermal power plant; the third flow meter is installed between the mixing device and the second booster pump.

[0013] Furthermore, the mixing device also includes a pressure gauge and a second level gauge; the pressure gauge is installed on the mixing tank and is used to monitor the pressure data inside the mixing tank; the second level gauge is installed inside the mixing tank.

[0014] The present invention also provides a method for adding ammonia and oxygen to a steam-water system in a thermal power plant, utilizing the aforementioned ammonia and oxygen addition system for a steam-water system in a thermal power plant. The method for adding ammonia oxygen includes the following steps: During the initial startup phase of a thermal power plant unit, an oxygen-free AVT (Automatic Transmission) mode is used. Specifically, when the liquid level in the ammonia source is greater than or equal to a preset value, the ammonia supply branch is opened, and the ammonia solution is transported to the mixing device. When the liquid level in the mixing device is greater than or equal to a set value, the output branch is opened, and the ammonia solution is added to the water-steam system of the thermal power plant. After the generating units in the thermal power plant are operating normally and the water quality in the steam-water system is up to standard, the plant switches to OT (Operational Time) mode. Specifically, when the liquid level in the ammonia source is greater than or equal to a preset value, the ammonia supply branch is opened. At the same time, the oxygen supply branch is opened, and the ammonia solution and oxygen are simultaneously transported to the mixing device. Then, the agitator is turned on to mix the oxygen and ammonia solution evenly to form an oxygen-containing mixture. When the liquid level in the mixing device is greater than or equal to a set value and the pressure value is greater than or equal to a preset threshold, the output branch is opened to add the oxygen-containing mixture to the steam-water system of the thermal power plant.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an ammonia-oxygen addition system and method for a steam-water system in a thermal power plant. An ammonia addition branch connects the ammonia source to a mixing device, and an oxygen addition branch connects the oxygen source to the mixing device. After mixing by the mixing device, the oxygen is delivered to the steam-water system via an output branch, achieving simultaneous ammonia and oxygen addition, or ammonia or oxygen addition separately. The organic integration of the ammonia and oxygen addition pipelines ensures corrosion and scale prevention for the unit's thermal equipment. The device has a simple structure, is easy to operate, and facilitates later maintenance. It eliminates the need to add both oxygen and ammonia addition points to the unit's thermal equipment, reducing heat loss, significantly reducing equipment size and space requirements, and improving plant utilization. Simultaneously, it reduces the need for drilling and welding on high-pressure equipment, improving the safety and economy of unit operation.

[0016] Furthermore, by installing a first electric shut-off valve, a first booster pump, a first manual shut-off valve, a second electric shut-off valve, and a first check valve in the ammonia addition branch, the opening degree of the valves can be adjusted to achieve effective control of the ammonia addition operation, ensuring the accuracy and safety of ammonia addition.

[0017] Furthermore, by installing an air compressor, a second manual shut-off valve, a third electric shut-off valve, and a second check valve on the oxygen supply branch, the accuracy and safety of oxygen supply are ensured.

[0018] Furthermore, by installing level gauges, flow meters, and pressure gauges in the system, the operating status of the system can be monitored in real time, ensuring the normal operation of the system and facilitating the timely detection and handling of faults. Attached Figure Description

[0019] Figure 1 This is a structural block diagram of the ammonia-oxygen addition system for the steam-water system of a thermal power plant, as described in the embodiment.

[0020] The components include: 1. Ammonia tank; 2. First level gauge; 3. First electric shut-off valve; 4. First booster pump; 5. First manual shut-off valve; 6. Second electric shut-off valve; 7. First flow meter; 8. First check valve; 9. Oxygen cylinder; 10. Pressure reducing valve; 11. Pressure stabilizing valve; 12. Air compressor; 13. Second manual shut-off valve; 14. Third electric shut-off valve; 15. Second flow meter; 16. Second check valve; 17. Mixing device; 18. Atomizing nozzle; 19. Agitator; 20. Pressure gauge; 21. Second level gauge; 22. Third flow meter; 23. Second booster pump; 24. Primary manual shut-off valve; 25. Secondary manual shut-off valve; 26. Third check valve; 27. PLC module. Detailed Implementation

[0021] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] This invention provides an ammonia-oxygen addition system for a steam-water system in a thermal power plant. A first level gauge 2 is installed in an ammonia tank 1. A first electric shut-off valve 3, a first booster pump 4, a first manual shut-off valve 5, a second electric shut-off valve 6, a first flow meter 7, and a first check valve 8 are sequentially installed on the outlet pipe of the ammonia tank 1. A pressure reducing valve 10, a pressure stabilizing valve 11, an air compressor 12, a second manual shut-off valve 13, a third electric shut-off valve 14, a second flow meter 15, and a second check valve 16 are sequentially installed on the outlet pipe of the oxygen cylinder 9. The chemical dosing branch and the oxygen dosing branch converge into a mixing device 17 via a mixing branch. The mixing device 17 is equipped with an atomizing nozzle 18 and a stirrer 19 to ensure thorough mixing of the chemical dosing medium and the oxygen dosing medium. A pressure gauge 20 and a second level gauge 21 are installed in the mixing device 17. The mixed medium... The gas flows sequentially through the third flow meter 22, the second booster pump 23, the primary manual shut-off valve 24, the secondary manual shut-off valve 25, and the third check valve 26 before being introduced into the water-steam system thermal equipment. The first level gauge, the first electric shut-off valve, the second electric shut-off valve, the first flow meter, the third electric shut-off valve, the second flow meter, the pressure gauge, and the second level gauge are all connected to the PLC module. These pressure gauges, flow meters, level gauges, and electric shut-off valves are all monitored and controlled by the PLC. During system operation, the level gauges, flow meters, and pressure gauges are used to observe the system's operation. Any malfunctions are addressed promptly to ensure normal system operation. The system has a simple structure and is easy to operate. By organically integrating oxygenation and chemical dosing, it ensures corrosion and scale prevention for the unit's thermal equipment while significantly reducing equipment size and improving plant utilization.

[0023] Example This embodiment takes the process of adding ammonia and oxygen for corrosion prevention in the steam-water system of a supercritical or ultra-supercritical unit in a thermal power plant as an example.

[0024] As attached Figure 1 As shown in the figure, the embodiment provides an ammonia-oxygen addition system for a steam-water system in a thermal power plant, including an ammonia source, an oxygenation branch, an oxygen source, an oxygenation branch, a mixing branch, a mixing device 17, an output branch, and a PLC module 27.

[0025] The ammonia source stores an ammonia solution, and its outlet is connected to the inlet of the ammonia addition branch, which is connected to the first inlet of the mixing branch. The oxygen source stores oxygen, and its outlet is connected to the inlet of the oxygen addition branch, which is connected to the second inlet of the mixing branch. The outlet of the mixing branch is connected to the inlet of the mixing device, and the outlet of the mixing device is connected to the water vapor system via an output branch.

[0026] In this embodiment, the ammonia source is an ammonia tank 1, and a first level gauge 2 is installed inside the ammonia tank 1. The first level gauge 2 is used to monitor the liquid level of the ammonia solution in the ammonia tank 1 in real time. The ammonia supply branch includes a first electric shut-off valve 3, a first booster pump 4, a first manual shut-off valve 5, a second electric shut-off valve 6, a first flow meter 7, and a first check valve 8. The inlet end of the first electric shut-off valve 3 is connected to the outlet end of the ammonia source, that is, the inlet end of the first electric shut-off valve 3 is connected to the outlet end of the ammonia tank 1. The outlet end of the first electric shut-off valve 3 is connected to the inlet end of the first booster pump 4, and the outlet end of the first booster pump 4 is connected to the first manual shut-off valve 5. The inlet end is connected, the outlet end of the first manual shut-off valve 5 is connected to the inlet end of the second electric shut-off valve 6, the outlet end of the second electric shut-off valve 6 is connected to the inlet end of the first check valve 8, and the outlet end of the first check valve 8 is connected to the first inlet end of the mixing branch; the first flow meter 7 is installed between the second electric shut-off valve 6 and the first check valve 8, and the first flow meter 7 is used to monitor the flow rate of ammonia solution in the ammonia addition branch in real time; the data output end of the first level gauge 2, the control end of the first electric shut-off valve 3, the control end of the second electric shut-off valve 6, and the data output end of the first flow meter 7 are all connected to the input end of the PLC module 27.

[0027] In this embodiment, the oxygen source is an oxygen cylinder 9, which stores oxygen. The oxygen supply branch includes a pressure reducing valve 10, a pressure regulating valve 11, an air compressor 12, a second manual shut-off valve 13, a third electric shut-off valve 14, a second flow meter 15, and a second check valve 16. The inlet of the pressure reducing valve 10 is connected to the outlet of the oxygen source, i.e., the inlet of the pressure reducing valve 10 is connected to the outlet of the oxygen cylinder 9. The outlet of the pressure reducing valve 10 is connected to the inlet of the pressure regulating valve 11, the outlet of the pressure regulating valve 11 is connected to the inlet of the air compressor 12, and the outlet of the air compressor 12 is connected to the second manual shut-off valve 16. The inlet end of the third electric shut-off valve 14 is connected to the outlet end of the second manual shut-off valve 13, which is connected to the inlet end of the third electric shut-off valve 14. The outlet end of the third electric shut-off valve 14 is connected to the inlet end of the second check valve 16, which is connected to the second inlet end of the mixing branch. The second flow meter 15 is disposed between the third electric shut-off valve 14 and the second check valve 16. The second flow meter 15 is used to monitor the oxygen flow rate in the oxygen supply branch in real time. The control end of the third electric shut-off valve 14 and the data output end of the second flow meter 15 are both connected to the input end of the PLC module 27.

[0028] In this embodiment, the mixing branch includes a mixing pipeline, and the inlet end of the mixing pipeline is provided with two inlets; one inlet is connected to the outlet end of the first check valve 8, and the other inlet is connected to the outlet end of the second check valve 16; the outlet end of the mixing pipeline is connected to the inlet end of the mixing device 17.

[0029] In this embodiment, the mixing device 17 includes a mixing tank, an atomizing nozzle 18, a stirrer 19, a pressure gauge 20, and a second level gauge 21. The mixing tank is a hollow, sealed tank structure. An inlet is located at the upper end of the mixing tank, and an outlet is located at the lower end. The atomizing nozzle 18 is installed inside the upper part of the mixing tank, and the outlet end of the mixing pipeline is connected to the inlet end of the atomizing nozzle 18 after passing through the inlet. The stirrer 19 is located inside the bottom end of the mixing tank. The stirrer 19 is used to stir and mix the ammonia solution and oxygen delivered to the mixing tank through the atomizing nozzle 18 to form an oxygen-containing mixture; the pressure gauge 20 is installed on the mixing tank to monitor the pressure data in the mixing tank in real time; the second level gauge 21 is installed in the mixing tank to monitor the level of the oxygen-containing mixture or ammonia solution in the mixing tank in real time; the data output terminals of the pressure gauge 20 and the second level gauge 21 are both connected to the input terminal of the PLC module 27.

[0030] In this embodiment, the output branch includes a third flow meter 22, a second booster pump 23, a primary manual shut-off valve 24, a secondary manual shut-off valve 25, and a third check valve 26. The inlet of the second booster pump 23 is connected to the outlet of the mixing device 17, i.e., the inlet of the second booster pump 23 is connected to the outlet of the mixing tank. The outlet of the second booster pump 23 is connected to the inlet of the primary manual shut-off valve 24, the outlet of the primary manual shut-off valve 24 is connected to the inlet of the secondary manual shut-off valve 25, the outlet of the secondary manual shut-off valve 25 is connected to the inlet of the third check valve 26, and the outlet of the third check valve 26 is connected to the water and steam system of the thermal power plant. The data output of the third flow meter 22 is connected to the input of the PLC module 27. The third flow meter 22 is used to monitor the flow rate of the oxygen-containing mixed liquid, ammonia solution, or oxygen transported in the output branch in real time.

[0031] The ammonia-oxygen addition system described in this embodiment connects the ammonia source to the mixing device via an ammonia addition branch and the oxygen source to the mixing device via an oxygen addition branch. It is then connected to the steam-water system of a thermal power plant via an output branch, enabling either mixed ammonia-oxygen addition or ammonia addition alone. When adding ammonia alone, the second manual shut-off valve 13 in the oxygen addition branch is closed, and the air compressor 12 is simultaneously shut off. Then, the first electric shut-off valve 3, the first booster pump 4, the first manual shut-off valve 5, and the second electric shut-off valve 6 in the ammonia addition branch are opened sequentially. When simultaneous ammonia and oxygen addition is required, the air compressor 12, the second manual shut-off valve 13, and the third electric shut-off valve 14 are opened after the ammonia addition branch is opened.

[0032] In this embodiment, before use, it is necessary to ensure that the medium added to the ammonia tank 1 is a well-prepared mixture of ammonia and water, and that the mixture is uniform; otherwise, it is difficult to calculate the amount of ammonia added using a flow meter. That is, the ammonia tank 1 contains an ammonia solution of a preset concentration. The first booster pump 4 is used to bring the medium pressure in the ammonia branch to 2.5 MPa to ensure that it can be added to the mixing device 17. The pressure resistance of the first flow meter 7 and the first check valve 8 is greater than or equal to 3 MPa to ensure pipeline safety. When the air compressor 12 is running, it should be able to ensure that the oxygen pressure reaches 2.5 MPa to ensure that oxygen can be added to the mixing device 17. The pressure resistance of the second flow meter 15 and the second check valve 16 is greater than or equal to 3 MPa to ensure pipeline safety. The mixing tank is made of stainless steel and should withstand a pressure of 3 MPa to ensure equipment safety.

[0033] This embodiment also provides a method for adding ammonia and oxygen to a steam-water system in a thermal power plant, including the following steps: During the initial startup of the units in the thermal power plant, the AVT operating condition without oxygen is adopted; specifically: when the liquid level in the ammonia source is greater than or equal to a preset value, the ammonia supply branch is opened, and the ammonia solution is transported to the mixing device 17; when the liquid level in the mixing device 17 is greater than or equal to a set value, the output branch is opened, and the ammonia solution is added to the water-steam system of the thermal power plant. After the generating units in the thermal power plant are operating normally and the water quality in the steam-water system is up to standard, the plant switches to OT (over-the-top) operation mode. Specifically, when the liquid level in the ammonia source is greater than or equal to a preset value, the ammonia supply branch is opened. At the same time, the oxygen supply branch is opened, and the ammonia solution and oxygen are simultaneously transported to the mixing device 17. Then, the stirrer 19 is turned on to mix the oxygen and ammonia solution evenly to form an oxygen-containing mixture. When the liquid level in the mixing device 17 is greater than or equal to a set value and the pressure value is greater than or equal to a preset threshold, the output branch is opened to add the oxygen-containing mixture to the steam-water system of the thermal power plant.

[0034] Specifically, the method for adding ammonia and oxygen includes the following steps: During the initial startup phase, the unit operates under AVT (Automatic Transmission) conditions without oxygen, requiring separate ammonia addition. Specifically, the first level gauge 2 in the ammonia tank 1 monitors the level of the ammonia solution in the dosing tank 1 in real time. When the level of the ammonia tank 1 is greater than or equal to the set value, the first electric shut-off valve 3 and the first booster pump 4 are opened. The first booster pump 4 is used to increase the pressure of the ammonia solution to 2.5 MPa. Then, the first manual shut-off valve 5 and the second electric shut-off valve 6 are opened in sequence, and the ammonia solution passes through the first flow meter 7, the first check valve 8 and the atomizing nozzle 18 to reach the mixing tank. At this time, it is not necessary to turn on the agitator 19. When the level of the mixing tank is greater than or equal to the set value, the second booster pump 23 is turned on to increase the pressure of the ammonia solution to a pressure greater than the oxygenation point. Then, the primary manual shut-off valve 24 and the secondary manual shut-off valve 25 are opened to allow the ammonia solution to enter the water vapor system.

[0035] After the unit is operating normally and the water quality is qualified, it will switch to OT (over-the-air) mode, which requires simultaneous addition of chemicals and oxygen. Specifically, the first level gauge 2 in the ammonia tank 1 monitors the ammonia solution level in the dosing tank 1 in real time. When the ammonia level in the ammonia tank 1 is greater than or equal to the set value, the first electric shut-off valve 3 and the first booster pump 4 are opened. The first booster pump 4 increases the pressure of the ammonia solution to 2.5 MPa. The first manual shut-off valve 5 and the second electric shut-off valve 6 are opened in sequence, and the ammonia solution passes through the first flow meter 7, the first check valve 8, and the atomizing nozzle 18 to reach the mixing tank. At the same time, the pressure reducing valve 10 at the outlet of the oxygen cylinder 9 is opened, and the pressure regulating valve 11 is adjusted. If the pressure is greater than 2.5 MPa, it is not necessary to turn on the air compressor 12. Otherwise, turn on the air compressor 12 to increase the gas pressure to above 2.5 MPa; then, turn on the second manual shut-off valve 13 and the third electric shut-off valve 14 in sequence to allow oxygen to enter the mixing tank; turn on the agitator 19 in the mixing device 17 to mix the oxygen and ammonia solution evenly to form an oxygen-containing mixture; when the liquid level of the oxygen-containing mixture in the mixing device 17 is greater than or equal to the set value, and the pressure is greater than or equal to the set value, turn on the second booster pump 23 to increase the pressure to a level greater than the oxygenation point, and then turn on the primary manual shut-off valve 24 and the secondary manual shut-off valve 25 to allow the oxygen-containing mixture to enter the water-steam system.

[0036] The ammonia-oxygen addition system and method for the steam-water system of thermal power plants described in this invention achieves corrosion prevention by separately setting up ammonia addition branches and oxygen addition branches, and then uniformly mixing the media in a mixing device before adding them to the steam-water system. It realizes both mixed ammonia-oxygen addition and separate ammonia addition functions, applicable to various operating conditions of supercritical or ultra-supercritical units. This reduces the number of equipment, simplifies the equipment structure, and helps reduce equipment footprint and construction costs, thus contributing to cost reduction and efficiency improvement for supercritical or ultra-supercritical units. Since supercritical or ultra-supercritical units require the addition of ammonia water for corrosion prevention during the initial startup and normal operation, and need to switch to OT (over-the-top) operation after the water quality meets standards, requiring simultaneous oxygenation and chemical addition, with both addition points essentially at the same location, this invention combines the oxygenation and chemical addition devices into one, significantly reducing equipment footprint and space requirements, while also reducing equipment maintenance.

[0037] In this invention, the mixing device can be placed in the chemical dosing room of the power plant boiler room. The pipeline after the mixing device is shared by oxygenation and chemical dosing, eliminating the need to lay separate oxygenation and chemical dosing pipelines, thus reducing construction and material costs. For newly built units, this helps to further shorten the construction period and improve project efficiency. Using this system for oxygenation and chemical dosing eliminates the need to add oxygenation and chemical dosing points to the unit's thermal equipment, reducing heat loss. At the same time, it reduces the need for drilling and welding on high-pressure equipment, improving the safety and economy of unit operation.

[0038] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. An ammonia-oxygen addition system for a steam-water system in a thermal power plant, characterized in that, It includes an ammonia source, an ammonia addition branch, an oxygen source, an oxygen addition branch, a mixing branch, a mixing device (17), and an output branch; The ammonia source stores an ammonia solution, and the outlet of the ammonia source is connected to the inlet of the ammonia addition branch, the outlet of the ammonia addition branch is connected to the first inlet of the mixing branch; the oxygen source stores oxygen, and the outlet of the oxygen source is connected to the inlet of the oxygen addition branch, the outlet of the oxygen addition branch is connected to the second inlet of the mixing branch. The outlet end of the mixing branch is connected to the inlet end of the mixing device, and the outlet end of the mixing device is connected to the water and steam system of the thermal power plant through the output branch. The mixing device (17) includes a mixing tank, an atomizing nozzle (18), and a stirrer (19); the atomizing nozzle (18) is located at the upper part of the mixing tank, and the inlet end of the atomizing nozzle (18) is connected to the outlet end of the mixing branch; the stirrer (19) is located at the bottom part of the mixing tank. The ammonia charging branch includes a first electric shut-off valve (3), a first booster pump (4), a first manual shut-off valve (5), a second electric shut-off valve (6), and a first check valve (8). The inlet end of the first electric shut-off valve (3) is connected to the outlet end of the ammonia source. The outlet end of the first electric shut-off valve (3) is connected to the inlet end of the first booster pump (4). The outlet end of the first booster pump (4) is connected to the inlet end of the first manual shut-off valve (5). The outlet end of the first manual shut-off valve (5) is connected to the inlet end of the second electric shut-off valve (6). The outlet end of the second electric shut-off valve (6) is connected to the inlet end of the first check valve (8). The outlet end of the first check valve (8) is connected to the first inlet end of the mixing branch. The ammonia charging branch also includes a first flow meter (7); the first flow meter (7) is disposed between the second electric shut-off valve (6) and the first check valve (8); The output branch includes a third flow meter (22), a second booster pump (23), a primary manual shut-off valve (24), a secondary manual shut-off valve (25), and a third check valve (26); the inlet end of the second booster pump (23) is connected to the outlet end of the mixing device, the outlet end of the second booster pump (23) is connected to the inlet end of the primary manual shut-off valve (24), the outlet end of the primary manual shut-off valve (24) is connected to the inlet end of the secondary manual shut-off valve (25), the outlet end of the secondary manual shut-off valve (25) is connected to the inlet end of the third check valve (26), and the outlet end of the third check valve (26) is used to connect with the water and steam system of the thermal power plant; the third flow meter (22) is located between the mixing device and the second booster pump (23).

2. The ammonia-oxygen addition system for a steam-water system in a thermal power plant according to claim 1, characterized in that, The ammonia source is an ammonia tank (1), and the ammonia tank (1) is equipped with a first level gauge (2); the oxygen source is an oxygen cylinder (9).

3. The ammonia-oxygen addition system for a steam-water system in a thermal power plant according to claim 1, characterized in that, The oxygen supply branch includes an air compressor (12), a second manual shut-off valve (13), a third electric shut-off valve (14), and a second check valve (16). The inlet end of the air compressor (12) is connected to the outlet end of the oxygen source. The outlet end of the air compressor (12) is connected to the inlet end of the second manual shut-off valve (13). The outlet end of the second manual shut-off valve (13) is connected to the inlet end of the third electric shut-off valve (14). The outlet end of the third electric shut-off valve (14) is connected to the inlet end of the second check valve (16). The outlet end of the second check valve (16) is connected to the second inlet end of the mixing branch.

4. An ammonia-oxygen addition system for a steam-water system in a thermal power plant according to claim 3, characterized in that, The oxygen supply branch also includes a pressure reducing valve (10) and a pressure regulating valve (11); the pressure reducing valve (10) and the pressure regulating valve (11) are sequentially arranged between the outlet end of the oxygen source and the inlet end of the air compressor (12).

5. An ammonia-oxygen addition system for a steam-water system in a thermal power plant according to claim 3, characterized in that, The oxygenation branch also includes a second flow meter (15); the second flow meter (15) is disposed between the third electric shut-off valve (14) and the second check valve (16).

6. An ammonia-oxygen addition system for a steam-water system in a thermal power plant according to claim 1, characterized in that, The mixing device (17) also includes a pressure gauge (20) and a second level gauge (21); the pressure gauge (20) is installed on the mixing tank and is used to monitor the pressure data inside the mixing tank; the second level gauge (21) is installed inside the mixing tank.

7. A method for adding ammonia and oxygen to a steam-water system in a thermal power plant, characterized in that, Using the ammonia-oxygen addition system for steam-water systems in thermal power plants as described in any one of claims 1-6; The method for adding ammonia oxygen includes the following steps: In the initial stage of unit startup in a thermal power plant, an AVT operating condition without oxygen is adopted; specifically: when the liquid level in the ammonia source is greater than or equal to a preset value, the ammonia addition branch is opened, and the ammonia solution is transported to the mixing device (17); when the liquid level in the mixing device (17) is greater than or equal to a set value, the output branch is opened, and the ammonia solution is added to the water and steam system of the thermal power plant; After the units in the thermal power plant are operating normally and the water quality in the steam-water system is qualified, the plant switches to OT (over-the-top) operation mode. Specifically, when the liquid level in the ammonia source is greater than or equal to the preset value, the ammonia supply branch is opened. At the same time, the oxygen supply branch is opened, and the ammonia solution and oxygen are simultaneously transported to the mixing device (17). Then, the stirrer (19) is turned on to mix the oxygen and ammonia solution evenly to form an oxygen-containing mixture. When the liquid level in the mixing device (17) is greater than or equal to the set value and the pressure value is greater than or equal to the preset threshold, the output branch is opened to add the oxygen-containing mixture to the steam-water system of the thermal power plant.

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