A corrosion protection device for low-additive hydrophobic systems under different working conditions

Abstract

The utility model discloses a kind of anticorrosion devices of low pressure feedwater heater drainage system under different working conditions, including automatic oxygenation system, automatic ethanolamine system, monitoring system and control system;Automatic oxygenation system includes compressed air storage tank, oxygenation electric cut-off valve and low pressure heater;Compressed air storage tank is connected with oxygenation electric cut-off valve, oxygenation electric cut-off valve is connected with low pressure heater;Automatic ethanolamine system includes ethanolamine solution tank and dosing pump electric cut-off valve;Ethanolamine solution tank is connected with dosing pump electric cut-off valve, dosing pump electric cut-off valve is connected with low pressure heater;Low pressure heater is connected with monitoring system, monitoring system is connected with control system, oxygenation electric cut-off valve and dosing pump electric cut-off valve are connected with control system.The utility model can monitor low pressure feedwater heater drainage system water vapor quality in real time.Realize AVT (O) and OT two kinds of operating condition Full coverage anticorrosion requirement, accurate, real-time feedback low pressure feedwater heater drainage water vapor quality, through ammonia oxygen collaborative device dynamic optimization oxygenation and ethanolamine addition amount Realize intelligent collaborative anticorrosion control.

Description

Technical Field

[0001] This utility model belongs to the field of water treatment technology in thermal power plants, and is an anti-corrosion device for low-pressure water treatment systems under different operating conditions. Background Technology

[0002] High scaling rates on boiler heating surfaces, blockage of water-cooled wall throttling orifices, rapid increases in boiler differential pressure, and jamming of high-pressure heater drain valves caused by the migration of corrosion products from the feedwater system or high-pressure heater drain system are major problems affecting the safe and stable operation of ultracritical (supercritical) units. Feedwater oxygenation treatment technology is an important means to solve these problems. The fully protected oxygenation treatment process meets the corrosion prevention requirements of low-pressure feedwater, high-pressure feedwater systems, and high-pressure heater systems. However, in actual unit operation, it was found that the iron content in the low-pressure feedwater heater (hereinafter referred to as: low-pressure heater) drain system is high, indicating that the low-pressure heater and its drain system also suffer from flow-accelerated corrosion. The low-pressure heater drain water eventually enters the condensate system, causing iron contamination of the condensate polishing resin and a short operating cycle of the condensate polishing unit, thus affecting the economic operation of the unit. Given the problems existing in the low-pressure heater system, it is necessary to suppress the flow-accelerated corrosion caused by the hydrophobic flow of the low-pressure heater. In order to more accurately suppress the flow-accelerated corrosion of the low-pressure heater system under the two operating conditions of boiler feedwater oxidative volatile treatment (AVT(O)) and feedwater oxygenation treatment (OT), it is urgent to develop an ammonia-oxygen synergistic control device suitable for low-pressure heater systems. Utility Model Content

[0003] The purpose of this invention is to provide an anti-corrosion device for a low-pressure hydrophobic system under different operating conditions. By adding alkalizing agents and oxidizing agents under AVT(O) and OT operating conditions, the invention solves the problems of insufficient FAC inhibition and inability to accurately prevent corrosion under both AVT(O) and OT operating conditions in the existing technology, thereby realizing real-time monitoring and intelligent collaborative anti-corrosion control of the water vapor quality of the low-pressure hydrophobic system.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] A corrosion protection device for a low-pressure hydrophobic system under different operating conditions includes an automatic oxygen supply system, an automatic ethanolamine supply system, a monitoring system, and a control system;

[0006] The automatic oxygen supply system includes a compressed air storage tank, an electric oxygen supply shut-off valve, and a low-pressure heater; the compressed air storage tank is connected to the inlet of the electric oxygen supply shut-off valve, and the outlet of the electric oxygen supply shut-off valve is connected to the low-pressure heater.

[0007] The automatic ethanolamine dosing system includes an ethanolamine solution tank and an electric shut-off valve for the dosing pump; the ethanolamine solution tank is connected to the inlet of the electric shut-off valve for the dosing pump, and the inlet of the electric shut-off valve for the dosing pump is connected to a low-pressure heater;

[0008] The low-pressure heater is connected to the monitoring system, which is connected to the control system. The oxygen supply electric shut-off valve and the chemical dosing pump electric shut-off valve are connected to the control system.

[0009] Furthermore, an electric pressure regulating valve is installed between the compressed air storage tank and the oxygen supply electric shut-off valve.

[0010] Furthermore, a compressed air pressure gauge, an oxygen supply valve, and an electric pressure regulating valve pressure gauge are installed between the compressed air storage tank and the electric pressure regulating valve.

[0011] Furthermore, a flow meter, a pressure gauge, and a pressure regulating valve are installed between the electric pressure regulating valve and the oxygen supply electric shut-off valve.

[0012] Furthermore, a check valve is installed between the oxygen supply electric shut-off valve and the low-pressure heater.

[0013] Furthermore, a first dosing valve and a dosing metering pump are installed between the ethanolamine solution tank and the electric shut-off valve of the dosing pump.

[0014] Furthermore, a buffer is installed between the dosing metering pump and the electric shut-off valve of the dosing pump.

[0015] Furthermore, the first dosing valve and the dosing metering pump are connected to the control system.

[0016] Furthermore, the monitoring system includes an online iron meter, an online oxygen meter, and an online pH meter; the low-pressure heater is connected to a low-pressure condensate drain pipe, and a low-pressure condensate drain sampling point is set on the low-pressure condensate drain pipe. The outlet of the low-pressure condensate drain sampling point is divided into three paths, which are respectively connected to the online iron meter, the online oxygen meter, and the online pH meter.

[0017] Furthermore, the control system includes a PLC control system, and online iron meters, online oxygen meters, and online pH meters are connected to the PLC control system.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] This invention is specifically designed for low-pressure condensate systems, incorporating an automatic oxygenation system, an automatic ethanolamine dosing system, a monitoring system, and a control system. The automatic oxygenation and ethanolamine dosing systems can be switched on and off via the control system according to different operating conditions. Both dosing systems share a common sampling point on the low-pressure condensate pipeline. The monitoring system and PLC control system enable real-time monitoring and intelligent collaborative corrosion prevention control of the water vapor quality in the low-pressure condensate system. Furthermore, the ammonia-oxygen synergistic control directly suppresses FAC in this area, solving the problem of high iron content in the low-pressure condensate. This invention allows for precise corrosion prevention under both operating conditions by switching between the automatic oxygenation system (OT mode) and the automatic ethanolamine dosing system (AVT(O) mode) via the PLC control system, adapting to the needs of different operating stages of the unit. Existing technologies cannot achieve this dynamic adaptation.

[0020] Furthermore, the online iron meter, online oxygen meter, and online pH meter provide real-time feedback on the iron content, dissolved oxygen, and pH value of the low-hydrophobic solution. Based on this, the PLC control system dynamically adjusts the oxygen or chemical dosage, forming an intelligent closed loop of "monitoring-feedback-adjustment," which is more accurate and efficient than the manual adjustment of existing technologies.

[0021] Furthermore, online iron meters and online pH meters can monitor the changing trend of iron content in low-pressure hydrophobic water in real time. Once the detected value rises abnormally, the system can issue an alarm in a timely manner, which facilitates rapid response and handling, avoids deterioration of water quality in low-pressure hydrophobic water, reduces the burden on the condensate polishing system, and extends its operating cycle. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an anti-corrosion device for a low-pressure hydrophobic system under different working conditions according to this utility model.

[0023] Among them, 1 is a compressed air storage tank, 2 is a compressed air pressure gauge, 3 is the first oxygen supply valve, 4 is an electric pressure regulating valve pressure gauge, 5 is an electric pressure regulating valve, 6 is a flow meter, 7 is a pressure stabilizing valve pressure gauge, 8 is a pressure stabilizing valve, 9 is an electric oxygen supply shut-off valve, 10 is a check valve, 11 is a low-pressure heater dosing point, 12 is a low-pressure heater, 13 is a low-pressure heater hydrophobic sampling point, 14 is an ethanolamine solution tank, 15 is the first dosing valve, 16 is a dosing metering pump, 17 is a buffer, 18 is an electric shut-off valve for the dosing pump, 19 is an online iron gauge, 20 is an online oxygen gauge, 21 is an online pH meter, and 22 is a PLC control system. Detailed Implementation

[0024] To facilitate understanding of this utility model, a more comprehensive description will be given below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of this utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0025] Furthermore, the elements in this invention are referred to as being "fixed to" or "set on" another element, which may be directly on the other element or may also include an intervening element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or may also include an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] like Figure 1 As shown, this utility model discloses an anti-corrosion device for a low-pressure heater hydrophobic system under different operating conditions, comprising an automatic oxygenation system, an automatic ethanolamine dosing system, a monitoring system, and a control system. The automatic oxygenation system includes a compressed air storage tank 1, a compressed air pressure gauge 2, an oxygenation first valve 3, an electric pressure regulating valve 4, an electric pressure regulating valve 5, a flow meter 6, a pressure stabilizing valve 7, a pressure stabilizing valve 8, an electric oxygenation shut-off valve 9, a check valve 10, a low-pressure heater dosing point 11, and a low-pressure heater 12. The outlet of the compressed air storage tank 1 is connected to the inlet of the compressed air pressure gauge 2, and the outlet of the compressed air pressure gauge 2... The outlet is connected to the inlet of the oxygenation first valve 3, the outlet of the oxygenation first valve 3 is connected to the inlet of the electric pressure regulating valve pressure gauge 4, the outlet of the electric pressure regulating valve pressure gauge 4 is connected to the inlet of the electric pressure regulating valve 5, the outlet of the electric pressure regulating valve 5 is connected to the inlet of the flow meter 6, the outlet of the flow meter 6 is connected to the inlet of the pressure stabilizing valve pressure gauge 7, the outlet of the pressure stabilizing valve pressure gauge 7 is connected to the inlet of the oxygenation electric shut-off valve 9, the outlet of the oxygenation electric shut-off valve 9 is connected to the inlet of the check valve 10, the outlet of the check valve 10 is connected to the low-pressure heater dosing point 11, and the low-pressure heater dosing point 11 is connected to the low-pressure heater 12.

[0028] The automatic ethanolamine dosing system includes an ethanolamine solution tank 14, a first dosing valve 15, a dosing metering pump 16, a buffer 17, and a dosing pump electric shut-off valve 18. The outlet of the ethanolamine solution tank 14 is connected to the inlet of the first dosing valve 15, the outlet of the first dosing valve 15 is connected to the inlet of the dosing metering pump 16, the outlet of the dosing metering pump 16 is connected to the inlet of the buffer 17, the outlet of the buffer 17 is connected to the inlet of the dosing pump electric shut-off valve 18, and the outlet of the dosing pump electric shut-off valve 18 is connected to the low-pressure heater dosing point 11.

[0029] The monitoring system includes an online iron meter 19, an online oxygen meter 20, an online pH meter 21, and a PLC control system 22. A low-pressure heater condensate sampling point 13 is provided on the low-pressure heater condensate pipe connected to the low-pressure heater 12. The outlet of the low-pressure heater condensate sampling point 13 is divided into three paths, which are respectively connected to the online iron meter 19, the online oxygen meter 20, and the online pH meter 21. The online iron meter 19, the online oxygen meter 20, and the online pH meter 21 are connected to the PLC control system 22 for monitoring the water vapor quality of the low-pressure heater condensate.

[0030] The control system includes a PLC control system 22. Electric regulating valve 5, oxygenation electric shut-off valve 9, dosing metering pump 16, and dosing pump electric shut-off valve 18 are all connected to the PLC control system 22 for controlling the ammonia-oxygen co-oxygenation and dosing quantity control in the low-pressure heater. The PLC control system 22 is connected to a DCS control system, which displays the control results.

[0031] To activate the automatic oxygen supply system (OT mode), first, open the first oxygen supply valve 3. Then, open the electric oxygen supply valve 9 to create the automatic oxygen supply system pathway. The outlet of the compressed air storage tank 1 is connected to the inlet of the compressed air pressure gauge 2. The outlet of the compressed air pressure gauge 2 is connected to the inlet of the first oxygen supply valve 3. The outlet of the first oxygen supply valve 3 is connected to the inlet of the electric pressure regulating valve pressure gauge 4. The outlet of the electric pressure regulating valve pressure gauge 4 is connected to the inlet of the electric pressure regulating valve 5. The outlet of the electric pressure regulating valve 5 is connected to the inlet of the flow meter 6. The outlet of the flow meter 6 is connected to the... The inlet of pressure gauge 7 is connected to the pressure valve, the outlet of pressure gauge 7 is connected to the inlet of oxygen-injecting electric shut-off valve 9, the outlet of oxygen-injecting electric shut-off valve 9 is connected to the inlet of check valve 10, the outlet of check valve 10 is connected to the low-pressure heater dosing point 11, the low-pressure heater dosing point 11 is connected to the low-pressure heater 12, and the outlet of low-pressure heater condensate sampling point 13 is connected to online iron gauge 19, online oxygen gauge 20, and online pH gauge 21 respectively. Online iron gauge 19, online oxygen gauge 20, and online pH gauge 21 are connected to PLC control system 22. By adjusting the opening of the oxygenation electric valve 9, setting the pressure of the electric pressure regulating valve pressure gauge 4 to 2 MPa, adjusting the flow rate of the flow meter 6 to 30 ml / min, and setting the pressure of the pressure stabilizing valve to 1 MPa (which is 0.6 MPa higher than the maximum pressure of the low-pressure heater 12), the opening of the electric pressure regulating valve 5 can be adjusted to create a pressure difference between the electric pressure regulating valve pressure gauge 4 and the pressure stabilizing valve pressure gauge 7, thus achieving a direct proportional adjustment of the oxygenation amount. Therefore, the unit's feedwater flow signal can be used as feedforward, and the opening of the electric pressure regulating valve 5 can be automatically adjusted through the PLC control system 22 to achieve automatic adjustment of the oxygenation amount. The online oxygen meter 20 collects the real-time dissolved oxygen amount and compares it with the set value of the PLC control system 22 to obtain the offset. The opening of the electric pressure regulating valve 5 is then corrected in real time based on the offset. The online iron meter 19 displays the iron content of the low-pressure hydrophobic vapor quality in real time. When the iron content level is too high, it can guide the correction of the low-pressure hydrophobic oxygen content setting value of the PLC control system. The PLC control system 22 automatically adjusts the amount of oxygen added to the set value, further reducing the flow-accelerated corrosion of the low-pressure hydrophobic system.

[0032] When the automatic ethanolamine dosing system is put into operation under AVT(O) conditions, firstly, the first dosing valve 15 is opened, and secondly, the electric shut-off valve 18 of the dosing pump is opened to form the dosing system passage. The outlet of the ethanolamine solution tank 14 is connected to the inlet of the first dosing valve 15, the outlet of the first dosing valve 15 is connected to the inlet of the metering pump 16, the outlet of the metering pump 16 is connected to the inlet of the buffer 17, the outlet of the buffer 17 is connected to the inlet of the electric shut-off valve 18 of the dosing pump, the outlet of the electric shut-off valve 18 of the dosing pump is connected to the inlet of the check valve 10, the outlet of the check valve 10 is connected to the dosing point 11 of the low-pressure heater, the dosing point 11 of the low-pressure heater is connected to the low-pressure heater 12, and the outlet of the low-pressure heater hydrophobic sampling point 13 is connected to the online iron meter 19, the online oxygen meter 20, and the online pH meter 21 respectively. The online iron meter 19, the online oxygen meter 20, and the online pH meter 21 are connected to the PLC control system 22. The dosage can be proportionally adjusted by changing the frequency of the metering pump 16. Therefore, the unit's feedwater flow signal can be used as feedforward, and the PLC control system can automatically adjust the frequency of the metering pump 16 to achieve automatic dosage adjustment. The online pH meter 21 provides real-time feedback on the pH value of the low-pressure condensate, comparing it with the pH value set by the PLC control system. The frequency of the metering pump 16 is corrected in real-time based on the deviation. The online iron meter 19 displays the iron content of the water vapor quality in the low-pressure condensate system in real-time. When the iron content is too high, it guides the correction of the pH setpoint of the low-pressure condensate system in the PLC control system. The PLC control system automatically adjusts the amount of ethanolamine added to the pH setpoint, further reducing flow-accelerated corrosion in the low-pressure condensate system.

[0033] The ammonia-oxygen synergistic control system first activates the automatic ethanolamine dosing system according to the above steps, then activates the automatic oxygenation system according to the same steps. When the online oxygen meter 20 detects a dissolved oxygen level greater than 10 ug / L, the PLC control system 22 sequentially stops the dosing metering pump 16 and closes the electric shut-off valve 18, operating only the automatic oxygenation system. When the online oxygen meter 20 detects a dissolved oxygen level less than 10 ug / L, the PLC control system sequentially starts the dosing metering pump 16, opens the electric shut-off valve 18, and activates the automatic dosing system, ensuring the long-term stable operation of the water vapor quality in the low-pressure condensate system.

[0034] In this invention, the automatic oxygenation system and the automatic ethanolamine dosing system can be switched on and off by the control system according to different working conditions. The two dosing systems have a common sampling point on the low-pressure condensate pipeline. The sampling point is connected in parallel with the online iron meter 19, the online oxygen meter 20, and the online pH meter 21. The signals from the online iron meter, the online oxygen meter, and the online pH meter are connected to the PLC control system. The PLC control system is also connected to the electric pressure regulating valve of the automatic oxygenation system and the metering pump of the dosing system, thereby realizing real-time monitoring and intelligent collaborative corrosion prevention control of the water vapor quality of the low-pressure condensate system.

[0035] 1) Existing full-protection oxygenation processes only cover low-pressure water supply, high-pressure water supply and high-pressure heating systems, while this utility model is specifically designed for low-pressure heating hydrophobic systems. It directly inhibits flow-accelerated corrosion (FAC) in this area through ammonia-oxygen synergistic control, thus solving the problem of high iron content in low-pressure heating hydrophobic systems.

[0036] 2) The automatic oxygen supply system (OT condition) and the automatic ethanolamine supply system (AVT(O) condition) can be switched through the PLC control system to achieve precise corrosion prevention under the two conditions and adapt to the needs of different operating stages of the unit. Existing technology cannot achieve this dynamic adaptation.

[0037] 3) The online iron meter, online oxygen meter, and online pH meter provide real-time feedback on the iron content, dissolved oxygen, and pH value of the low-hydrophobic solution. The PLC control system uses this information to dynamically adjust the oxygen or chemical dosage, forming an intelligent closed loop of "monitoring-feedback-adjustment," which is more accurate and efficient than the manual adjustment of existing technologies.

[0038] 4) Online iron meter and online pH meter can monitor the change trend of iron content in low-pressure hydrophobic water in real time. Once the detected value rises abnormally, the system can issue an alarm in time, which facilitates rapid response and handling, avoids the deterioration of water quality in low-pressure hydrophobic water, reduces the burden on the condensate polishing system, and extends its operating cycle.

[0039] The above description only illustrates the preferred embodiment of this utility model and should not be construed as limiting the claims. This utility model is not limited to the above embodiments, and variations in its specific structure are permitted. All changes made within the scope of the independent claims of this utility model are also within the scope of protection of this utility model.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A corrosion protection device for a low-pressure hydrophobic system under different operating conditions, characterized in that, Includes an automatic oxygenation system, an automatic ethanolamine dosing system, a monitoring system, and a control system; The automatic oxygenation system includes a compressed air storage tank (1), an oxygenation electric shut-off valve (9), and a low-pressure heater (12); the compressed air storage tank (1) is connected to the inlet of the oxygenation electric shut-off valve (9), and the outlet of the oxygenation electric shut-off valve (9) is connected to the low-pressure heater (12); The automatic ethanolamine dosing system includes an ethanolamine solution tank (14) and a dosing pump electric shut-off valve (18); the ethanolamine solution tank (14) is connected to the inlet of the dosing pump electric shut-off valve (18), and the inlet of the dosing pump electric shut-off valve (18) is connected to the low-pressure heater (12); The low-pressure heater (12) is connected to the monitoring system, which is connected to the control system. The oxygenation electric shut-off valve (9) and the dosing pump electric shut-off valve (18) are connected to the control system.

2. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 1, characterized in that, An electric pressure regulating valve (5) is installed between the compressed air storage tank (1) and the oxygen supply electric shut-off valve (9).

3. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 2, characterized in that, A compressed air pressure gauge (2), an oxygen supply first valve (3), and an electric pressure regulating valve pressure gauge (4) are installed between the compressed air storage tank (1) and the electric pressure regulating valve (5).

4. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 2, characterized in that, A flow meter (6), a pressure gauge (7), and a pressure regulating valve (8) are installed between the electric pressure regulating valve (5) and the oxygen supply electric shut-off valve (9).

5. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 1, characterized in that, A check valve (10) is provided between the oxygen supply electric shut-off valve (9) and the low-pressure heater (12).

6. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 1, characterized in that, An ethanolamine solution tank (14) and a dosing pump electric shut-off valve (18) are provided between the dosing first valve (15) and the dosing metering pump (16).

7. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 1, characterized in that, A buffer (17) is provided between the dosing metering pump (16) and the electric shut-off valve (18) of the dosing pump.

8. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 6, characterized in that, The first dosing valve (15) and the dosing metering pump (16) are connected to the control system.

9. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 1, characterized in that, The monitoring system includes an online iron meter (19), an online oxygen meter (20), and an online pH meter (21); the low-pressure heater (12) is connected to a low-pressure condensate pipe, and a low-pressure condensate sampling point (13) is provided on the low-pressure condensate pipe. The outlet of the low-pressure condensate sampling point (13) is divided into three paths, which are respectively connected to the online iron meter (19), the online oxygen meter (20), and the online pH meter (21).

10. The anti-corrosion device for a low-pressure hydrophobic system under different operating conditions according to claim 9, characterized in that, The control system includes a PLC control system, and online iron meter (19), online oxygen meter (20) and online pH meter (21) are connected to the PLC control system.

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