Oxygen and chemical adding device and method for water supply system of thermal power generating unit

Abstract

The invention relates to the technical field of water chemical working conditions of thermal power generating units, in particular to an oxygen and chemical adding device and method for a water supply system of a thermal power generating unit. The oxygen and chemical adding device for the water supply system of the thermal power generating unit comprises a production water tank, and a demineralized water conveying assembly, an oxygen conveying assembly and an oxygen adding assembly which are simultaneously connected with the production water tank, the ammonia gas conveying assembly and the ammonia adding assembly are connected with the ammonia solution storage tank; the fine treatment device, the deaerator, the high-pressure heater and the economizer are sequentially connected; the plurality of dissolved oxygen measuring devices and the plurality of pH measuring devices are respectively arranged between the fine treatment device and the deaerator, between the deaerator and the high-pressure heater and between the high-pressure heater and the economizer; and the controller is electrically connected with the plurality of dissolved oxygen measuring devices, the plurality of pH measuring devices, the oxygen adding assembly and the ammonia adding assembly. The problems that an existing water supply system cannot meet the control requirement for low-content oxygenation of water supply, and corrosion is still obvious are solved.

Description

Technical Field

[0001] This invention relates to the field of water chemistry operating conditions for thermal power units, specifically to an oxygenation and chemical dosing device and method for the feedwater system of thermal power units. Background Technology

[0002] Currently, feedwater oxygenation is widely recognized as an effective chemical treatment method for preventing corrosion of thermal equipment in thermal power generating units. Traditional oxygenation processes involve adding oxygen to the condensate polishing outlet and the deaerator downcomer to control a high dissolved oxygen level in the feedwater, allowing the thermal system to oxidize step-by-step according to the steam-water flow, ensuring the entire system operates under aerobic conditions. In recent years, with the frequent occurrence of scale buildup on the high-temperature sections of ultra-supercritical boiler heating surfaces (superheaters and reheaters), the impact of traditional oxygenation methods on high-temperature steam oxidation has raised concerns. To avoid the potential adverse effects of oxygen in the steam on high-temperature steam oxidation, many units have switched to low-oxygen feedwater treatment. This method reduces the dissolved oxygen content in the steam, but it cannot solve the problem of accelerated corrosion in the high-pressure heater drainage system. Therefore, researchers and technicians have implemented oxygenation on the high-pressure heater drainage side. However, because oxygen is used as the oxidant, the injection of trace amounts of gas is difficult to control accurately, making practical operation challenging and failing to meet the requirements for low-oxygen feedwater control; corrosion problems remain significant. Summary of the Invention

[0003] On the one hand, the present invention provides an oxygenation and chemical dosing device for the feedwater system of thermal power units, in order to solve the problem that existing oxygenation and chemical dosing devices use oxygen as an oxidant, which makes it difficult to achieve the control requirements of low oxygenation in feedwater and corrosion is still relatively obvious.

[0004] On the other hand, the present invention provides a method to solve the problem of accelerated corrosion caused by the low pH value of the high-pressure heater condensate and the difficulty in controlling oxygenation when the unit load fluctuates greatly due to the small flow of the high-pressure heater condensate.

[0005] On one hand, the present invention provides an oxygenation and chemical dosing device for a thermal power unit feedwater system, comprising: An oxygen-enriched water supply device includes a production water tank and a demineralized water conveying assembly, an oxygen conveying assembly, and an oxygenation assembly connected to the production water tank. The ammonia supply device includes an ammonia solution storage tank and an ammonia gas conveying assembly and an ammonia addition assembly connected to the ammonia solution storage tank. The ammonia solution storage tank is also connected to the demineralized water conveying assembly. The fine treatment unit, deaerator, high-pressure heater and economizer are connected in sequence. The first outlet of the oxygen addition component and the first outlet of the ammonia addition component are connected between the fine treatment unit and the deaerator. The second outlet of the oxygen addition component and the second outlet of the ammonia addition component are connected between the deaerator and the high-pressure heater. The high-pressure heater is connected to the third outlet of the oxygen addition component and the third outlet of the ammonia addition component. Multiple dissolved oxygen measuring devices and multiple pH measuring devices are respectively installed between the fine treatment unit and the deaerator, between the deaerator and the high-pressure heater, and between the high-pressure heater and the economizer; The controller is electrically connected to multiple dissolved oxygen measuring devices, multiple pH measuring devices, oxygenation components, and ammonia addition components to receive electrical signals from the dissolved oxygen and pH measuring devices and to regulate the flow rate of the oxygenation or ammonia addition components.

[0006] Beneficial effects: When oxygenation is required in the water supply system, demineralized water is first added to the production water tank through the demineralized water delivery component, and then oxygen is added to the production water tank through the oxygen delivery component, thus producing oxygen-enriched water. When the system pH is within the first preset range, the oxygen-enriched water is then delivered through the oxygenation component to the area between the fine treatment unit and the deaerator, between the deaerator and the high-pressure heater, and into the high-pressure heater. The controller regulates the flow rate of the oxygen-enriched water in the oxygenation component to control the dissolved oxygen index of the system. Compared with pure oxygen or compressed air as the oxygenation medium, the oxygenation process is safer and more reliable, and the dissolved oxygen index is easier to control. Moreover, by adopting three-point oxygenation, the dissolved oxygen content of the water supply system is effectively controlled, and a dense Fe2O3 oxide film is formed on the inner wall of the system pipes. This effectively avoids unsafe events caused by deposition corrosion of thermal equipment and can also indirectly reduce the pH value of the water supply, reducing the amount of ammonia added. When ammonia needs to be added to the water supply system, the demineralized water is first added to the ammonia solution storage tank through the demineralized water conveying component, and then ammonia gas is added to the ammonia solution storage tank through the ammonia gas conveying component. The ammonia solution is then conveyed through the ammonia addition component to the area between the fine treatment unit and the deaerator, between the deaerator and the high-pressure heater, and into the high-pressure heater. The controller adjusts the flow rate of the ammonia solution in the ammonia addition component according to the system pH to control the system pH. When the dissolved oxygen in the high-pressure heater fluctuates greatly, oxygen addition is stopped and replaced with ammonia addition to increase the pH value of the high-pressure heater's hydrophobic pipes and effectively suppress the problem of flow-accelerated corrosion in the high-pressure heater's hydrophobic pipes.

[0007] In one optional embodiment, the oxygenation assembly includes an oxygenation pipe and an oxygen-enriched water pump connected in series, and the ammonia addition assembly includes an ammonia addition pipe and an ammonia pump connected in series. The controller adjusts the dissolved oxygen index of the water supply system by controlling the frequency of the oxygen-enriched water pump, and the controller adjusts the pH value of the water supply system by controlling the frequency of the ammonia pump.

[0008] The controller adjusts the dissolved oxygen and pH levels of the water supply system by separately controlling the frequencies of the oxygen-enriched water pump and the ammonia pump, making it more intuitive and convenient.

[0009] In one alternative implementation, a buffer tank is also provided between the production water tank and the oxygenation assembly.

[0010] The buffer tank can temporarily store oxygen-enriched water, maintaining a continuous and stable output when the production water tank experiences brief fluctuations. This prevents water hammer caused by system interruption or sudden pressure changes, protecting pipelines, valves, and pumps. In addition, the buffer tank can stabilize the dissolved oxygen concentration of the oxygen-enriched water, avoiding uneven dissolved oxygen distribution due to sudden changes in flow rate, ensuring stable subsequent oxygenation treatment conditions, and reducing the risk of corrosion in the thermal system.

[0011] In one alternative implementation, the production tank is also connected to an internal circulation component.

[0012] The main function of the internal circulation component in the production water tank is to enhance the uniform mixing of the water and the gas-liquid mass transfer within the tank, avoiding localized uneven concentrations, dead water zones, and oxygen stratification. Through continuous internal circulation, the dissolved oxygen concentration of the oxygen-enriched water is kept uniform and stable throughout the entire tank, while also improving the oxygen dissolution efficiency and utilization rate, preventing the oxygenation effect of the subsequent system from being affected by localized low dissolved oxygen levels.

[0013] In one alternative embodiment, the internal circulation assembly includes a first outlet pipe, a circulation pump, a return pipe, and a dissolved oxygen measuring device arranged in series, with the other end of the first outlet pipe also connected to a buffer tank.

[0014] Oxygen-enriched water, under the action of the circulating pump, returns to the production water tank through the first outlet pipe, dissolved oxygen measuring device, and return pipe. This reduces the deposition of suspended solids and algae growth in the tank, keeps the water in the tank clean, and prevents impurities from entering subsequent pipelines and water pumps, causing blockages or wear. In addition, it can help eliminate local pressure fluctuations and bubble accumulation in the tank, reduce cavitation factors, and work with the external delivery system to achieve more stable water output conditions, further improving the stability, reliability, and economy of the entire process of oxygen-enriched water preparation and delivery.

[0015] In one optional embodiment, the oxygen delivery assembly includes an oxygen cylinder, an oxygen pipe, and a first valve arranged in series. The production water tank is provided with a first distribution pipe and a plurality of first branch pipes connected to the first distribution pipe. The oxygen pipe is connected to the first distribution pipe.

[0016] Oxygen-enriched water is evenly added to the production water tank through the first distribution pipe and multiple first branch pipes, which further improves the oxygenation effect.

[0017] In one optional embodiment, the demineralized water conveying assembly includes a second distribution pipe connected to the demineralized water inlet pipe, the second distribution pipe having a first demineralized water branch pipe and a second demineralized water branch pipe connected in parallel, the first demineralized water branch pipe being connected to the production water tank, and the second demineralized water branch pipe being connected to the ammonia solution storage tank.

[0018] The demineralized water is introduced into the production water tank and the ammonia solution storage tank through the second distribution pipe, the first demineralized water branch pipe, and the second demineralized water branch pipe, respectively, which reduces the number of pipelines and lowers costs.

[0019] In one optional embodiment, the ammonia delivery assembly includes an ammonia cylinder, an ammonia pipe, and a second valve arranged in series. The ammonia solution tank is provided with a third distribution pipe and a plurality of second branch pipes connected to the third distribution pipe. The ammonia pipe is connected to the third distribution pipe.

[0020] Ammonia gas is evenly added to the ammonia solution tank through the third distribution pipe and multiple second branch pipes, further improving the ammonia addition effect.

[0021] In one alternative embodiment, the high-pressure heater has a built-in high-pressure heater inner coil, the inlet of which is connected to an extraction pipe, the outlet of which is connected to a high-pressure heater drain pipe, and the other end of which is connected to a deaerator.

[0022] The high-pressure heater features an internal coil, with its inlet connected to the extraction steam pipe and its outlet connected to the deaerator via a high-pressure heater condensate drain pipe. This design fully utilizes the heat from the turbine extraction steam, achieving indirect heat exchange between steam and the heated water through the coil-type heat exchange structure. This avoids steam-water impact and pressure fluctuations caused by direct mixing of steam and feedwater, improving heat exchange safety and stability. The condensate formed after the steam condenses and releases heat inside the coil is directly introduced into the deaerator through the drain pipe, enabling cascaded heat utilization and condensate recovery, reducing high-quality working fluid and heat loss, and improving the unit's thermal cycle efficiency. The internal coil structure simplifies the internal layout of the high-pressure heater, reducing equipment size and space occupation, while also facilitating maintenance and reducing leakage risks. Direct discharge of condensate into the deaerator also reduces condensate expansion and flash evaporation, simplifying system piping, reducing throttling losses and energy consumption, and improving the unit's operational economy and reliability.

[0023] On the other hand, the present invention also provides an oxygenation and chemical dosing method, which utilizes an oxygenation and chemical dosing device in the feedwater system of a thermal power unit for oxygenation and chemical dosing, including the following steps: When ammonia is added to the water supply system, the controller adjusts the flow rate of the ammonia addition component based on the received system pH and the signal from the ammonia addition component, so as to control the system pH to reach the first preset value. When oxygenating the water supply system, the controller adjusts the flow rate of the oxygenation component based on the received system pH to control the dissolved oxygen index of the system to reach the second preset value. When the dissolved oxygen index of the system reaches the second preset value, the controller adjusts the flow rate of the ammonia addition component based on the received system pH and the signal from the ammonia addition component to control the system pH to reach the third preset value, which is less than the first preset value.

[0024] Beneficial effects: When oxygenation is required in the water supply system, demineralized water is first added to the production water tank through the demineralized water delivery component, and then oxygen is added to the production water tank through the oxygen delivery component, thus producing oxygen-enriched water. When the system pH is within the first preset range, the oxygen-enriched water is then delivered through the oxygenation component to the area between the fine treatment unit and the deaerator, between the deaerator and the high-pressure heater, and into the high-pressure heater. The controller regulates the flow rate of the oxygen-enriched water in the oxygenation component to control the dissolved oxygen index of the system. Compared with pure oxygen or compressed air as the oxygenation medium, the oxygenation process is safer and more reliable, and the dissolved oxygen index is easier to control. Moreover, by adopting three-point oxygenation, the dissolved oxygen content of the water supply system is effectively controlled, and a dense Fe2O3 oxide film is formed on the inner wall of the system pipes. This effectively avoids unsafe events caused by deposition corrosion of thermal equipment and can also indirectly reduce the pH value of the water supply, reducing the amount of ammonia added. When ammonia needs to be added to the water supply system, the demineralized water is first added to the ammonia solution storage tank through the demineralized water conveying component, and then ammonia gas is added to the ammonia solution storage tank through the ammonia gas conveying component. The ammonia solution is then conveyed through the ammonia addition component to the area between the fine treatment unit and the deaerator, between the deaerator and the high-pressure heater, and into the high-pressure heater. The controller adjusts the flow rate of the ammonia solution in the ammonia addition component according to the system pH to control the system pH. When the dissolved oxygen in the high-pressure heater fluctuates greatly, oxygen addition is stopped and replaced with ammonia addition to increase the pH value of the high-pressure heater's hydrophobic pipes and effectively suppress the problem of flow-accelerated corrosion in the high-pressure heater's hydrophobic pipes. Attached Figure Description

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

[0026] Figure 1 This is a schematic diagram of an oxygenation and chemical dosing device for a thermal power unit feedwater system according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Oxygen cylinder; 2. Production water tank; 3. Buffer water tank; 4. First oxygen-enriched water pump; 5. Second oxygen-enriched water pump; 6. Third oxygen-enriched water pump; 7. Ammonia cylinder; 8. Ammonia solution storage tank; 9. First ammonia pump; 10. Second ammonia pump; 11. Third ammonia pump; 12. Controller; 13. Oxygen pipe; 14. First pressure reducing valve; 15. Second electric valve; 16. First distribution pipe; 17. First branch pipe; 18. Second branch pipe; 19. Third branch pipe; 20. First exhaust pipe; 21. ... 21. Safety valve; 22. First drain pipe; 23. First manual valve; 24. First level gauge; 25. First outlet pipe; 26. Circulation pump; 27. First electric valve; 28. Return pipe; 29. ​​First oxygen gauge; 30. Third level gauge; 31. Second vent pipe; 32. Second safety valve; 33. Second drain pipe; 34. Second manual valve; 35. Water outlet pipe; 36. Fourth distribution pipe; 37. First oxygen supply pipe; 38. Second oxygen supply pipe; 39. Third oxygen supply pipe; 40. Ammonia pipe. ; 41. Second pressure reducing valve; 42. Fifth electric valve; 43. Third distribution pipe; 44. Fourth branch pipe; 45. Fifth branch pipe; 46. Sixth branch pipe; 47. Conductivity meter; 48. Second level gauge; 49. Stirring rod; 50. Impeller; 51. Stirring motor; 52. Tank opening; 53. Second outlet pipe; 54. Fifth distribution pipe; 55. First ammonia charging pipe; 56. Second ammonia charging pipe; 57. Third ammonia charging pipe; 58. Demineralized water inlet pipe; 59. Second distribution pipe; 60. 61. First demineralized water branch pipe; 62. Third electric valve; 63. Second demineralized water branch pipe; 64. Fourth electric valve; 65. Fine treatment unit; 66. Deaerator; 67. High-pressure heater; 68. First connecting pipe; 69. Second connecting pipe; 70. Third connecting pipe; 71. First pH meter; 72. Fourth oxygen meter; 73. Second pH meter; 74. Third oxygen meter; 75. Steam extraction pipe; 76. High-pressure heater inner coil; 77. High-pressure heater drain pipe; 78. Third pH meter; 79. Second oxygen meter. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The following is combined Figure 1 Embodiments of the present invention are described.

[0030] According to an embodiment of the present invention, an oxygenation and chemical dosing device for a thermal power unit feedwater system is provided, comprising: The oxygen-enriched water supply device includes a production water tank 2 and a demineralized water conveying assembly, an oxygen conveying assembly, and an oxygenation assembly connected to the production water tank 2. The ammonia supply device includes an ammonia solution storage tank 8 and an ammonia gas conveying assembly and an ammonia addition assembly connected to the ammonia solution storage tank 8. The ammonia solution storage tank 8 is also connected to the demineralized water conveying assembly. A fine treatment device 64, a deaerator 65, a high-pressure heater 66 and an economizer are connected in sequence. The first outlet of the oxygen addition component and the first outlet of the ammonia addition component are connected between the fine treatment device 64 and the deaerator 65. The second outlet of the oxygen addition component and the second outlet of the ammonia addition component are connected between the deaerator 65 and the high-pressure heater 66. The high-pressure heater 66 is connected to the third outlet of the oxygen addition component and the third outlet of the ammonia addition component. Multiple dissolved oxygen measuring devices and multiple pH measuring devices are respectively installed between the fine treatment device 64 and the deaerator 65, between the deaerator 65 and the high-pressure heater 66, and between the high-pressure heater 66 and the economizer. The controller 12 is electrically connected to multiple dissolved oxygen measuring devices, multiple pH measuring devices, an oxygenation assembly, and an ammonia addition assembly to receive electrical signals from the dissolved oxygen measuring devices and pH measuring devices, and to regulate the flow rate of the oxygenation assembly or the ammonia addition assembly.

[0031] The production water tank 2 is equipped with a first vent pipe 20 at the top, and a first safety valve 21 is installed on the first vent pipe 20. The production water tank 2 is equipped with a first drain pipe 22 at the bottom, and a first manual valve 23 is installed on the first drain pipe 22. The production water tank 2 has a built-in first level gauge 24. The ammonia solution storage tank 8 is equipped with a built-in stirring rod 49. The stirring rod 49 has a stirring motor 51 and an impeller 50 installed at its top and bottom, respectively. The ammonia solution storage tank 8 has a tank opening 52 at the top, and a conductivity meter 47 and a second level gauge 48 are also installed inside. A first connecting pipe 67 is provided between the fine treatment device 64 and the deaerator 65. The first outlet of the oxygenation component and the first outlet of the ammonia addition component are both located on the first connecting pipe 67. A second connecting pipe 68 is provided between the deaerator 65 and the high-pressure heater 66. The second outlet of the oxygenation component and the second outlet of the ammonia addition component are both located on the second connecting pipe 68. The high-pressure heater 66 is connected to a high-pressure heater drain pipe 76. The third outlet of the oxygenation component and the third outlet of the ammonia addition component are both located on the high-pressure heater drain pipe 76. In this embodiment, the dissolved oxygen measuring device is an oxygen meter, the pH measuring device is a pH meter, and the controller 12 is a PLC controller.

[0032] Beneficial effects: When oxygenation is required in the water supply system, demineralized water is first added to the production water tank 2 through the demineralized water delivery component, and then oxygen is added to the production water tank 2 through the oxygen delivery component, thereby producing oxygen-enriched water. When the system pH is within the first preset range, the oxygen-enriched water is then delivered through the oxygenation component to the area between the fine treatment device 64 and the deaerator 65, between the deaerator 65 and the high-pressure heater 66, and to the high-pressure heater 66. The controller 12 regulates the flow rate of the oxygen-enriched water in the oxygenation component to control the dissolved oxygen index of the system. Compared with pure oxygen or compressed air as the oxygenation medium, the oxygenation process is safer and more reliable, and the dissolved oxygen index is easier to control. Moreover, by adopting three-point oxygenation, the dissolved oxygen content of the water supply system is effectively controlled, and a dense Fe2O3 oxide film is formed on the inner wall of the system pipes. This effectively avoids unsafe events caused by deposition corrosion of thermal equipment and can also indirectly reduce the pH value of the water supply, reducing the amount of ammonia added. When ammonia needs to be added to the water supply system, demineralized water is first added to the ammonia solution storage tank 8 through the demineralized water conveying assembly. Then, ammonia gas is added to the ammonia solution storage tank 8 through the ammonia gas conveying assembly. The ammonia solution is then conveyed through the ammonia addition assembly to the area between the fine treatment unit 64 and the deaerator 65, between the deaerator 65 and the high-pressure heater 66, and into the high-pressure heater 66. The controller 12 adjusts the flow rate of the ammonia solution in the ammonia addition assembly according to the system pH to control the system pH. When the dissolved oxygen in the high-pressure heater hydrophobic pipe fluctuates greatly, oxygen addition is stopped and ammonia addition is switched to increase the pH value of the high-pressure heater hydrophobic pipe to effectively suppress the problem of accelerated corrosion caused by the flow of the high-pressure heater hydrophobic pipe.

[0033] In one embodiment, the oxygenation assembly includes an oxygenation pipe and an oxygen-enriched water pump connected in series, the ammonia addition assembly includes an ammonia addition pipe and an ammonia pump connected in series, the controller 12 adjusts the dissolved oxygen index of the water supply system by controlling the frequency of the oxygen-enriched water pump, and the controller 12 adjusts the pH value of the water supply system by controlling the frequency of the ammonia pump.

[0034] All three oxygenation units and three ammonia addition units are connected in parallel to simultaneously deliver oxygen-enriched water and ammonia solution to different connecting pipelines.

[0035] The controller 12 adjusts the dissolved oxygen index and pH value of the water supply system by controlling the frequency of the oxygen-enriched water pump and the ammonia pump respectively, which is more intuitive and convenient.

[0036] In one embodiment, a buffer water tank 3 is also provided between the production water tank 2 and the oxygenation assembly.

[0037] The buffer tank 3 is equipped with a second vent pipe 31 on top, and a second safety valve 32 on the second vent pipe 31. The buffer tank 3 is equipped with a second drain pipe 33 at the bottom, and a second manual valve 34 on the second drain pipe 33. The buffer tank 3 is equipped with a third level gauge 30. The buffer tank 3 is also equipped with a water outlet pipe 35 on one side. The water outlet pipe 35 is connected to a fourth distribution pipe 36. The fourth distribution pipe 36 is connected in parallel with three sets of oxygenation components. The three sets of oxygenation components are a first oxygen-enriched water pump 4 and a first oxygenation pipe 37, a second oxygen-enriched water pump 5 and a second oxygenation pipe 38, and a third oxygen-enriched water pump 6 and a third oxygenation pipe 39.

[0038] The buffer tank 3 can temporarily store oxygen-enriched water, maintaining a continuous and stable output when the production tank 2 experiences brief fluctuations. This prevents water hammer caused by system interruption or sudden pressure changes, protecting pipelines, valves, and pumps. In addition, the buffer tank 3 can stabilize the dissolved oxygen concentration of the oxygen-enriched water, avoiding uneven dissolved oxygen distribution due to sudden changes in flow rate, ensuring stable subsequent oxygenation treatment conditions, and reducing the risk of corrosion in the thermal system.

[0039] In one embodiment, the production tank 2 is also connected to an internal circulation component.

[0040] The main function of the internal circulation component in production water tank 2 is to enhance the uniform mixing of water and gas-liquid mass transfer within the tank, avoiding localized uneven concentrations, dead water zones, and oxygen stratification. Through continuous internal circulation, the dissolved oxygen concentration of the oxygen-enriched water is kept uniform and stable throughout the entire tank, while also improving the oxygen dissolution efficiency and utilization rate, preventing the oxygenation effect of the subsequent system from being affected by localized low dissolved oxygen levels.

[0041] In one embodiment, the internal circulation assembly includes a first outlet pipe 25, a circulation pump 26, a return pipe 28, and a dissolved oxygen measuring device arranged in series. The other end of the first outlet pipe 25 is also connected to a buffer tank 3.

[0042] One end of the first outlet pipe 25 is connected to the bottom of the production water tank 2, and the other end is connected to the middle of the buffer water tank 3. A circulation pump 26 and a first electric valve 27 are sequentially installed on the first outlet pipe 25 near the production water tank 2. One end of the return pipe is connected to the middle of the production water tank 2, and the other end is connected to the first outlet pipe 25 between the circulation pump 26 and the first electric valve 27. In this embodiment, the dissolved oxygen measuring device is a first oxygen meter 29.

[0043] Under the action of the circulating pump 26, the oxygen-enriched water returns to the production water tank 2 through the first outlet pipe 25, the dissolved oxygen measuring device, and the return pipe 28. This reduces the deposition of suspended solids and algae growth in the tank, keeps the water in the tank clean, and prevents impurities from entering the subsequent pipelines and water pumps, causing blockages or wear. In addition, it can help eliminate local pressure fluctuations and bubble accumulation in the tank, reduce cavitation factors, and work with the external conveying system to achieve a more stable water output condition, further improving the stability, reliability, and economy of the entire process of oxygen-enriched water preparation and transportation.

[0044] In one embodiment, the oxygen delivery assembly includes an oxygen cylinder 1, an oxygen pipe 13 and a first valve arranged in series. The production water tank 2 is provided with a first distribution pipe 16 and a plurality of first branch pipes connected to the first distribution pipe 16. The oxygen pipe 13 is connected to the first distribution pipe 16.

[0045] One end of the oxygen tube 13 is connected to the oxygen cylinder 1, and the other end is connected to the first distribution tube 16. A first pressure reducing valve 14 and a second electric valve 15 are sequentially installed on the oxygen tube 13 near the oxygen cylinder 1. The first pressure reducing valve 14 and the second electric valve 15 together constitute the first valve. In this embodiment, the multiple first branch tubes are a first branch tube 17, a second branch tube 18, and a third branch tube 19.

[0046] Oxygen-enriched water is evenly added to the production water tank 2 through the first distribution pipe 16 and multiple first branch pipes, which further improves the oxygenation effect.

[0047] In one embodiment, the demineralized water delivery assembly includes a second distribution pipe 59 connected to a demineralized water inlet pipe 58. The second distribution pipe 59 is connected in parallel to a first demineralized water branch pipe 60 and a second demineralized water branch pipe 62. The first demineralized water branch pipe 60 is connected to the production water tank 2, and the second demineralized water branch pipe 62 is connected to the ammonia solution storage tank 8.

[0048] The first demineralized water branch pipe 60 is connected at one end to the second distribution pipe 59 and at the other end to the lower part of the production water tank 2. A third electric valve 61 is installed on the first demineralized water branch pipe 60. The second demineralized water branch pipe 62 is connected at one end to the second distribution pipe 59 and at the other end to the top of the ammonia solution storage tank 8. A fourth electric valve 63 is installed on the second demineralized water branch pipe 62.

[0049] The demineralized water is introduced into the production water tank 2 and the ammonia solution storage tank 8 through the second distribution pipe 59, the first demineralized water branch pipe 60, and the second demineralized water branch pipe 62, respectively, which reduces the number of pipelines and lowers the cost.

[0050] In one embodiment, the ammonia delivery assembly includes an ammonia cylinder 7, an ammonia pipe 40, and a second valve arranged in series. The ammonia solution storage tank 8 is provided with a third distribution pipe 43 and a plurality of second branch pipes connected to the third distribution pipe 43. The ammonia pipe 40 is connected to the third distribution pipe 43.

[0051] Ammonia pipe 40 is connected to an ammonia cylinder at one end and to a third distribution pipe 43 at the other end. Multiple second branch pipes are designated as a fourth branch pipe 44, a fifth branch pipe 45, and a sixth branch pipe 46. A second pressure reducing valve 41 and a fifth electric valve 42 are sequentially installed on the ammonia pipe 40 near the ammonia cylinder 7. The second pressure reducing valve 41 and the fifth electric valve 42 together constitute a second valve. A second outlet pipe 53 is also provided on one side of the ammonia solution storage tank 8. The second outlet pipe 53 is connected to a fifth distribution pipe 54. Three sets of ammonia charging components are connected in parallel to the fifth distribution pipe 54. The three sets of ammonia charging components are: a first ammonia pump 9 and a first ammonia charging pipe 55; a second ammonia pump 10 and a second ammonia charging pipe 56; and a third ammonia pump 11 and a third ammonia charging pipe 57.

[0052] Ammonia gas is evenly added to the ammonia solution tank through the third distribution pipe 43 and multiple second branch pipes, which further improves the ammonia addition effect.

[0053] In one embodiment, the high-pressure heater 66 has a built-in high-pressure heater inner coil 75. The inlet of the high-pressure heater inner coil 75 is connected to a steam extraction pipe 74, and the outlet of the high-pressure heater inner coil 75 is connected to a high-pressure heater drain pipe 76. The other end of the high-pressure heater drain pipe 76 is connected to the deaerator 65. A third connecting pipe 69 is also provided on one side of the high-pressure heater 66. A second pH meter 72 and a third oxygen meter 73 are provided on the third connecting pipe 69.

[0054] The high-pressure heater 66 has a built-in high-pressure heater coil 75, with its inlet connected to the extraction steam pipe 74 and its outlet connected to the deaerator 65 via the high-pressure heater drain pipe. This configuration can fully utilize the heat from the turbine extraction steam and achieve indirect heat exchange between steam and the heated water through the coil-type heat exchange structure, avoiding steam-water impact and pressure fluctuations caused by direct mixing of steam and feedwater, thus improving heat exchange safety and stability. The condensate formed after the steam condenses and releases heat in the coil is directly introduced into the deaerator 65 through the drain pipe, enabling the cascade utilization of heat and condensate recovery, reducing the loss of high-quality working fluid and heat, and improving the unit's thermal cycle efficiency. The built-in coil structure simplifies the internal layout of the high-pressure heater 66, reduces equipment size and space occupation, and facilitates maintenance while reducing the risk of leakage. Direct discharge of condensate into the deaerator 65 also reduces condensate expansion and flash evaporation, simplifies system piping, reduces throttling losses and energy consumption, and improves the unit's operating economy and reliability.

[0055] On the other hand, the present invention also provides an oxygenation and chemical dosing method, which utilizes an oxygenation and chemical dosing device in the feedwater system of a thermal power unit for oxygenation and chemical dosing, including the following steps: When ammonia is added to the water supply system, the controller 12 adjusts the flow rate of the ammonia addition component according to the received system pH and the signal from the ammonia addition component, so as to control the system pH to reach the first preset value. When oxygenating the water supply system, the controller 12 adjusts the flow rate of the oxygenation component according to the received system pH to control the dissolved oxygen index of the system to reach the second preset value; when the dissolved oxygen index of the system reaches the second preset value, the controller 12 adjusts the flow rate of the ammonia addition component according to the received system pH and the signal from the ammonia addition component to control the system pH to reach the third preset value, which is less than the first preset value.

[0056] Beneficial effects: When oxygenation is required in the water supply system, demineralized water is first added to the production water tank 2 through the demineralized water delivery component, and then oxygen is added to the production water tank 2 through the oxygen delivery component, thereby producing oxygen-enriched water. When the system pH is within the first preset range, the oxygen-enriched water is then delivered through the oxygenation component to the fine treatment device and deaerator 65, the deaerator 65 and high-pressure heater 66, and the high-pressure heater 66, respectively. The controller 12 regulates the flow rate of the oxygen-enriched water in the oxygenation component to control the dissolved oxygen index of the system. Compared with pure oxygen or compressed air as the oxygenation medium, the oxygenation process is safer and more reliable, and the dissolved oxygen index is easier to control. Moreover, by adopting three-point oxygenation, the dissolved oxygen content of the water supply system is effectively controlled, and a dense Fe2O3 oxide film is formed on the inner wall of the system pipes. This effectively avoids unsafe events caused by deposition corrosion of thermal equipment and can also indirectly reduce the pH value of the water supply and reduce the amount of ammonia added. When ammonia needs to be added to the water supply system, demineralized water is first added to the ammonia solution storage tank 8 through the demineralized water conveying component. Then, ammonia gas is added to the ammonia solution storage tank 8 through the ammonia gas conveying component. The ammonia solution is then conveyed through the ammonia addition component to the area between the fine treatment unit and the deaerator 65, between the deaerator 65 and the high-pressure heater 66, and into the high-pressure heater 66. The controller 12 adjusts the flow rate of the ammonia solution in the ammonia addition component according to the system pH to control the system pH. When the dissolved oxygen in the high-pressure heater fluctuates greatly, oxygen addition is stopped and replaced with ammonia addition to increase the pH value of the high-pressure heater's hydrophobic pipes and effectively suppress the problem of accelerated corrosion caused by the flow of the high-pressure heater's hydrophobic pipes.

[0057] The specific methods for oxygenation and drug administration are as follows: To prepare oxygen-enriched water: Close the first manual valve 23, close the first electric valve 27, ensure the first safety valve 21 is closed, activate the first level gauge 24, and open the third electric valve 61. This allows the demineralized water to flow through the demineralized water inlet pipe 58, the second distribution pipe 59, and the first demineralized water branch pipe 60 into the production water tank 2. When the first level gauge 24 shows 2 / 3 full, close the third electric valve 61. Activate the first oxygen meter 29 and start the circulation pump 26. This allows the demineralized water in the production water tank 2 to circulate internally through the first outlet pipe 25 and the return pipe 28. At this time, the dissolved oxygen level of the demineralized water in the production water tank 2 can be observed through the first oxygen meter 29. After opening the first pressure reducing valve 14 and the regulating valve, adjust the pressure to 0.05MPa, open the second electric valve 15, that is, oxygen in oxygen cylinder 1 is simultaneously transported to the demineralized water in production water tank 2 through oxygen pipe 13, first distribution pipe 16 and three first branch pipes. Through the input of oxygen in oxygen cylinder 1 and the internal circulation of circulation pump 26, when the index of the first oxygen gauge 29 reaches 100-150mg / L, close the first pressure reducing valve 14 and the second electric valve 15.

[0058] Transferring oxygen-enriched water: Close the second manual valve 34, ensure the second safety valve 32 is closed, activate the third level gauge 30, open the first electric valve 27, and start the circulation pump 26. This means that a portion of the oxygen-enriched demineralized water in the production water tank 2 circulates through the first outlet pipe 25 and return pipe 28, while the other portion flows to the buffer water tank 3. When the oxygen-enriched demineralized water in the buffer water tank 3 reaches 3 / 2 full, stop the circulation pump 26 and close the first electric valve 27.

[0059] Preparing ammonia solution: Operate the second level gauge 48 and open the fourth electric valve 63. The demineralized water flows through the demineralized water inlet pipe 58, the second distribution pipe 59, and the second demineralized water branch pipe 62 into the ammonia solution storage tank 8. When the second level gauge 48 displays 2 / 3 of its full capacity, close the fourth electric valve 63. Operate the conductivity meter 47 and start the stirring motor 51. The stirring motor 51 drives the impeller 50 connected to the stirring rod 49 to stir the demineralized water in the ammonia solution storage tank 8. The conductivity of the demineralized water in the ammonia solution storage tank 8 can be observed through the conductivity meter 47. After opening the second pressure reducing valve 41 and the regulating valve, adjust the pressure to 0.01 MPa, open the fifth electric valve 42, that is, the ammonia gas in the ammonia cylinder 7 enters the demineralized water in the ammonia solution storage tank 8 through the ammonia pipe 40, the third distribution pipe 43 and the three second branch pipes. With the input of ammonia gas in the ammonia cylinder 7 and the stirring of the stirring motor 51, when the conductivity meter 47 index is 1000~1200 μs / cm, close the second pressure reducing valve 41 and the fifth electric valve 42.

[0060] Ammonia addition to the feedwater system: The unit is operating normally. The fine treatment unit 64, deaerator 65, and high-pressure heater 66 are operating normally. The water-side flow rate of high-pressure heater 66 and the steam-side high-pressure heater drain pipe 76 are stable and normal. The first pH meter 70, the second pH meter 72, and the third pH meter 77 are put into operation. The first ammonia pump 9, the second ammonia pump 10, and the third ammonia pump 11 are started. The PLC controller 12 is put into operation. The PLC controller 12 receives information from the first pH meter 70, the second pH meter 72, and the third pH meter 77, and also receives frequency signals from the first ammonia pump 9, the second ammonia pump 10, and the third ammonia pump 11. By adjusting the frequencies of the first ammonia pump 9, the second ammonia pump 10, and the third ammonia pump 11, the pH values ​​of the first pH meter 70, the second pH meter 72, and the third pH meter 77 are controlled within the range of 9.2-9.6.

[0061] Oxygenation of the feedwater system: The unit is in normal operation. The fine treatment unit 64, deaerator 65, and high-pressure heater 66 are operating normally. The water-side flow rate of high-pressure heater 66 and the steam-side high-pressure heater drain pipe 76 are stable and normal. When the pH values ​​of the first pH meter 70, the second pH meter 72, and the third pH meter 77 are all within the range of 9.2-9.6, the second oxygen meter 78, the third oxygen meter 73, and the fourth oxygen meter 71 are put into operation. The first oxygen-enriched water pump 4, the second oxygen-enriched water pump 5, and the third oxygen-enriched water pump 6 are started. The PLC controller 12 is put into operation. The PLC controller 12 controls the dissolved oxygen index of the second oxygen meter 78, the third oxygen meter 73, and the fourth oxygen meter 71 within the range of 10-30 μg / L by adjusting the frequency of the first oxygen-enriched water pump 4, the second oxygen-enriched water pump 5, and the third oxygen-enriched water pump 6. Lowering the feedwater pH: With the unit operating normally, the fine treatment unit 64, deaerator 65, and high-pressure heater 66 are functioning normally. The water-side flow rate of high-pressure heater 66 and the steam-side high-pressure heater drain pipe 76 are both stable and normal. When the dissolved oxygen levels of the second oxygen meter 78, third oxygen meter 73, and fourth oxygen meter 71 are within the range of 10-30 μg / L, the PLC controller 12 is activated. The PLC controller 12 receives information from the first pH meter 70, second pH meter 72, and third pH meter 77, as well as the frequency signals from the first ammonia pump 9, second ammonia pump 10, and third ammonia pump 11. By adjusting the frequencies of the first ammonia pump 9, second ammonia pump 10, and third ammonia pump 11, the pH levels of the first pH meter 70, second pH meter 72, and third pH meter 77 are controlled within the range of 8.8-9.0.

[0062] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An oxygenation and chemical dosing device for a thermal power unit feedwater system, characterized in that, include: The oxygen-enriched water supply device includes a production water tank (2) and a demineralized water conveying assembly, an oxygen conveying assembly, and an oxygenation assembly connected to the production water tank (2). The ammonia supply device includes an ammonia solution storage tank (8) and an ammonia gas conveying assembly and an ammonia addition assembly connected to the ammonia solution storage tank (8). The ammonia solution storage tank (8) is also connected to a demineralized water conveying assembly. A fine treatment device (64), a deaerator (65), a high-pressure heater (66), and an economizer are connected in sequence. The fine treatment device (64) and the deaerator (65) are connected by a first outlet of an oxygenation component and a first outlet of an ammonia addition component. The deaerator (65) and the high-pressure heater (66) are connected by a second outlet of an oxygenation component and a second outlet of an ammonia addition component. The high-pressure heater (66) is connected to a third outlet of an oxygenation component and a third outlet of an ammonia addition component. Multiple dissolved oxygen measuring devices and multiple pH measuring devices are respectively installed between the fine treatment device (64) and the deaerator (65), between the deaerator (65) and the high-pressure heater (66), and between the high-pressure heater (66) and the economizer; The controller (12) is electrically connected to multiple dissolved oxygen measuring devices, multiple pH measuring devices, the oxygenation component and the ammonia addition component to receive electrical signals from the dissolved oxygen measuring devices and the pH measuring devices, and to regulate the flow rate of the oxygenation component or the ammonia addition component.

2. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 1, characterized in that, The oxygenation assembly includes an oxygenation pipe and an oxygen-enriched water pump connected in series. The ammonia addition assembly includes an ammonia addition pipe and an ammonia pump connected in series. The controller (12) adjusts the dissolved oxygen index of the water supply system by controlling the frequency of the oxygen-enriched water pump. The controller (12) adjusts the pH value of the water supply system by controlling the frequency of the ammonia pump.

3. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 1, characterized in that, A buffer water tank (3) is also provided between the production water tank (2) and the oxygenation component.

4. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 3, characterized in that, The production water tank (2) is also connected to an internal circulation component.

5. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 4, characterized in that, The internal circulation assembly includes a first outlet pipe (25), a circulation pump (26), a return pipe (28), and a dissolved oxygen measuring device arranged in series. The other end of the first outlet pipe (25) is also connected to the buffer water tank (3).

6. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 1, characterized in that, The oxygen delivery assembly includes an oxygen cylinder (1), an oxygen pipe (13), and a first valve arranged in series. The production water tank (2) is provided with a first distribution pipe (16) and a plurality of first branch pipes connected to the first distribution pipe (16). The oxygen pipe (13) is connected to the first distribution pipe (16).

7. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 6, characterized in that, The demineralized water conveying assembly includes a demineralized water inlet pipe (58) connected to a second distribution pipe (59). The second distribution pipe (59) is connected in parallel with a first demineralized water branch pipe (60) and a second demineralized water branch pipe (62). The first demineralized water branch pipe (60) is connected to the production water tank (2), and the second demineralized water branch pipe (62) is connected to the ammonia solution storage tank (8).

8. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to claim 7, characterized in that, The ammonia delivery assembly includes an ammonia cylinder (7), an ammonia pipe (40), and a second valve arranged in series. The ammonia solution tank is provided with a third distribution pipe (43) and a plurality of second branch pipes connected to the third distribution pipe (43). The ammonia pipe (40) is connected to the third distribution pipe (43).

9. The oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to any one of claims 1 to 8, characterized in that, The high-pressure heater (66) has a built-in high-pressure heater inner coil (75), the inlet of the high-pressure heater inner coil (75) is connected to a steam extraction pipe (74), the outlet of the high-pressure heater inner coil (75) is connected to a high-pressure heater drain pipe (76), and the other end of the high-pressure heater drain pipe (76) is connected to the deaerator (65).

10. A method for oxygenation and drug administration, characterized in that, Oxygenation and chemical dosing using the oxygenation and chemical dosing device for the feedwater system of a thermal power unit according to any one of claims 1 to 9 includes the following steps: When ammonia is added to the water supply system, the controller (12) adjusts the flow rate of the ammonia addition component according to the received system pH and the signal from the ammonia addition component, so as to control the system pH to reach the first preset range; When oxygen is added to the water supply system, the controller (12) adjusts the flow rate of the oxygenation component according to the received system pH to control the dissolved oxygen index of the system to reach the second preset range; when the dissolved oxygen index of the system reaches the second preset range, the controller (12) adjusts the flow rate of the ammonia addition component according to the received system pH and the signal of the ammonia addition component to control the system pH to reach the third preset range, which is less than the first preset range.

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