A constant pressure continuous replacement system for a generator stator cooling water tank

Abstract

The application provides a generator stator cooling water tank constant pressure continuous replacement system, which comprises a first pressure reducing valve, a first isolation valve, a second isolation valve, a pressure gauge, a needle valve, a third isolation valve, a hydrogen concentration detector, a fourth isolation valve, a first constant pressure valve, a flowmeter, a stator cooling water tank and a nitrogen cylinder; the outlet of the nitrogen cylinder is connected with a main pipeline through the first pressure reducing valve; the main pipeline is sequentially connected with the first isolation valve, the needle valve, the stator cooling water tank, the fourth isolation valve, the first constant pressure valve and the flowmeter; the pressure gauge is arranged between the first isolation valve and the needle valve and is connected with the main pipeline through the second isolation valve; the hydrogen concentration detector is arranged between the stator cooling water tank and the fourth isolation valve and is connected with the main pipeline through the third isolation valve. The application can continuously replace hydrogen in the stator cooling water tank without interruption, and greatly reduces the workload of operators.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal power generation, in particular to a constant pressure continuous replacement system for a generator stator cooling water tank. BACKGROUND

[0002] In order to solve the problem of heat generation due to current flowing through the stator bars during generator operation, a set of stator cooling water system is provided for the generator. Through a plurality of hollow bars, cooling water is continuously introduced into the bars to carry away the heat generated in the bars.

[0003] Most domestic large generators are hydrogen-cooled generators, i.e. the hydrogen gas cools the surface of the generator rotor and the core. In order to ensure the hydrogen cooling effect and avoid the leakage of stator cooling water into the generator, the hydrogen pressure of the generator is set to be higher than the stator cooling water pressure. Generally, the rated hydrogen pressure of large and medium-sized generators is 0.4 MPa, and the stator cooling water pressure is about 0.25 MPa. Because the stator bars are connected to the stator cooling water inlet and outlet pipes by joints, there are inevitably some leaks, and hydrogen will leak into the stator cooling water. The hydrogen will accumulate in the stator cooling water tank, causing the hydrogen concentration in the tank to rise.

[0004] In order to monitor the hydrogen leakage of the generator and avoid the hydrogen concentration in the stator cooling water exceeding the explosion limit, in recent years many generators have added hydrogen concentration detection devices, which are generally installed at the top of the water tank exhaust pipe.

[0005] According to the requirements of the Anti-Money Laundering Regulations, the hydrogen concentration in the stator cooling water tank should not exceed 4%. Generally, when the hydrogen concentration detection device detects that the hydrogen concentration in the tank has risen to 2%-3%, an alarm will be sent. After receiving the alarm signal, the operator will manually operate the relevant valves to perform the replacement operation, i.e. by using a nitrogen cylinder and nitrogen charging pipeline to charge nitrogen into the stator cooling water tank to discharge hydrogen and reduce the hydrogen concentration. In order to prevent air from leaking into the stator cooling water tank, the nitrogen charging should ensure a slight positive pressure in the tank. The existing stator cooling water system can be as shown in Fig. Figure 1

[0006] However, in the prior art, due to the small density of hydrogen, even if a small amount of hydrogen leaks into the stator cooling water system, the hydrogen will float to the top of the tank and be detected by the hydrogen concentration detector, triggering an alarm for exceeding the concentration limit. Therefore, the detected concentration value cannot represent the concentration level of the entire tank. Although a small amount of hydrogen leakage does not reflect the actual tank concentration, after the value exceeds the limit, manual replacement is necessary, resulting in a large waste of human resources and an increase in labor intensity. Moreover, frequent nitrogen replacement basically requires the consumption of a batch of nitrogen cylinders for each replacement operation, resulting in high nitrogen consumption costs. SUMMARY

[0007] ​To solve the above problems, the application provides a generator stator cooling water tank constant pressure continuous replacement system, which comprises a first pressure reducing valve, a first isolation valve, a second isolation valve, a pressure gauge, a needle valve, a third isolation valve, a hydrogen concentration detector, a fourth isolation valve, a first constant pressure valve, a flow meter, a cooling water tank and a nitrogen cylinder.

[0008] In one embodiment, the sixth isolation valve, the seventh isolation valve and the water seal device are further included, the water seal device is connected to the needle valve and the cooling water tank on the main pipeline through the sixth isolation valve, and the water seal device is connected to the cooling water tank through the seventh isolation valve.

[0009] In one embodiment, the second pressure reducing valve and the fifth isolation valve are further included and arranged on the main pipeline, and the second pressure reducing valve and the fifth isolation valve are arranged between the first isolation valve and the needle valve in sequence.

[0010] In one embodiment, the second constant pressure valve is further included and arranged between the sixth isolation valve and the water seal device.

[0011] In one embodiment, the bypass valve is further included and arranged between the needle valve and the seventh isolation valve and connected to the bypass pipeline in parallel with the sixth isolation valve.

[0012] In one embodiment, the first blowdown valve is further included and arranged on the first blowdown pipeline, and the first blowdown pipeline is arranged between the fifth isolation valve and the needle valve.

[0013] In one embodiment, the second blowdown valve is further included and arranged on the second blowdown pipeline, and the second blowdown pipeline is arranged on the water seal device.

[0014] In one embodiment, the pressure gauge and the flow meter comprise a data transmission module.

[0015] In one embodiment, the pressure transmitter is further included and arranged between the seventh isolation valve and the fourth isolation valve.

[0016] This invention enables continuous and uninterrupted replacement of hydrogen in a constant-temperature cooling water tank. By recording the flow meter readings, it also monitors whether hydrogen leakage is increasing, preventing hydrogen accumulation in the tank from exceeding the explosion limit and eliminating the risk of a hydrogen explosion. Furthermore, after the system is put into operation, nitrogen consumption is significantly reduced, greatly decreasing the workload for operators. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of an existing generator stator cooling water system;

[0019] Figure 2 This is a schematic diagram of the constant pressure continuous replacement system for the generator stator cooling water tank in the first embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the constant pressure continuous replacement system for the generator stator cooling water tank in the second embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the constant pressure continuous replacement system for the generator stator cooling water tank in the third embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the constant pressure continuous replacement system for the generator stator cooling water tank in the fourth embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] This invention provides a constant pressure continuous displacement system for generator stator cooling water tanks, such as... Figure 2As shown, the system includes a first pressure reducing valve 1, a first isolation valve 2, a second isolation valve 5, a pressure gauge 6, a needle valve 8, a third isolation valve 12, a hydrogen concentration detector 13, a fourth isolation valve 14, a first constant pressure valve 15, a flow meter 20, a constant cooling water tank 30, and a nitrogen cylinder 40. The outlet of the nitrogen cylinder 40 is connected to the main pipeline via the first pressure reducing valve 1. The main pipeline is sequentially connected to the first isolation valve 2, the needle valve 8, the constant cooling water tank 30, the fourth isolation valve 14, the first constant pressure valve 15, and the flow meter 20. A pressure gauge 6 is installed between the first isolation valve 2 and the needle valve 8, and the pressure gauge 6 is connected to the main pipeline via the second isolation valve 5. A hydrogen concentration detector 13 is installed between the constant cooling water tank 30 and the fourth isolation valve 14, and the hydrogen concentration detector 13 is connected to the main pipeline via the third isolation valve 12.

[0025] Therefore, this embodiment continuously connects the nitrogen cylinder 40 to the stator cooling water system to purge the system with nitrogen. The nitrogen purging pressure in the stator cooling water tank 30 is controlled by the first pressure reducing valve 1. The pressure after pressure reduction is monitored by the pressure gauge 6. The nitrogen purging flow rate in the stator cooling water tank 30 is limited by the needle valve 8. A slight positive pressure is maintained in the stator cooling water tank 30 by the first constant pressure valve 15. Furthermore, the trend of changes in the flow meter 20 value can be used to monitor whether hydrogen leakage is increasing. Based on the flow meter 20 reading, the size of the needle valve 8 can be adjusted, thereby adjusting the nitrogen output flow rate of the nitrogen cylinder 40. This avoids excessive nitrogen consumption caused by adjusting the nitrogen output flow rate of the nitrogen cylinder 40 solely based on data from the hydrogen concentration detector 13.

[0026] This embodiment enables uninterrupted and continuous replacement of hydrogen in the constant cooling water tank. While avoiding the need for periodic manual replacement required in existing technologies, it prevents hydrogen accumulation in the tank from exceeding the explosion limit, thus eliminating the risk of hydrogen explosion. Furthermore, due to the aforementioned structural improvements to the cooling pipe network, technicians can precisely control the balance between nitrogen output and hydrogen leakage, avoiding excessive nitrogen consumption caused by adjusting the nitrogen output flow rate of nitrogen cylinder 40 solely based on data from the hydrogen concentration detector 13. After the system is put into operation, nitrogen consumption is significantly reduced. This greatly reduces the workload of operators, decreasing the replacement operation from once a day to once every 15 days.

[0027] like Figure 3 As shown, in one embodiment, the system further includes a sixth isolation valve 9, a seventh isolation valve 11, and a water seal device 19. The inlet of the water seal device 19 is connected between the needle valve 8 on the main pipeline and the constant cooling water tank 30 via the sixth isolation valve 9, and the connection and disconnection with the constant cooling water tank 30 are controlled by the seventh isolation valve 11.

[0028] By setting up a water seal device 19, when the flow meter 20 malfunctions, the water seal is broken, and the exhaust gas is discharged through the water seal and the discharge pipe 18, thus not affecting the normal exhaust of the system and preventing overpressure in the constant cooling water tank.

[0029] In one embodiment, the system further comprises a second pressure reducing valve 3 and a fifth isolation valve 4 arranged on the main pipeline, the second pressure reducing valve 3 and the fifth isolation valve 4 are arranged between the first isolation valve 2 and the second isolation valve 5 in sequence, through two-stage pressure reduction, the nitrogen pressure can be greatly reduced, thereby facilitating fine flow control. And when the second pressure reducing valve 3 fails, the first isolation valve 2 and the fifth isolation valve 4 can realize online maintenance of the second pressure reducing valve 3.

[0030] In one embodiment, the system further comprises a second constant pressure valve 10 arranged between the sixth isolation valve 9 and the water seal device 19. By arranging the second constant pressure valve 10, when the water tank inlet pressure exceeds 35kPa, the pressure relief is automatically opened, realizing overpressure protection of the water tank. At the same time, it can also be used as a backup for the constant pressure valve 15, when the constant pressure valve 15 fails, the water tank pressure exceeds 35kPa, the constant pressure valve 10 is opened, maintaining the water tank pressure at 35kPa, realizing double protection of the water tank.

[0031] In one embodiment, the system further comprises a bypass valve 17, as shown in Figure 4 The bypass valve 17 is arranged between the needle valve 8 and the seventh isolation valve 11, and is connected with the bypass pipe parallel to the sixth isolation valve 9, so that the pressure relief function can be realized in the fault condition.

[0032] In one embodiment, the system further comprises a first blowdown valve 7, as shown in Figure 5 The first blowdown valve 7 is arranged between the fifth isolation valve 4 and the needle valve 8, and the first blowdown valve 7 is at the lowest point of the system, which is used for blowdown of the main pipeline.

[0033] In one embodiment, the system further comprises a second blowdown valve 18 arranged on the second blowdown pipeline and arranged on the water seal device 19, which is used for blowdown treatment during pipeline purging and flushing and cleaning.

[0034] In one embodiment, the pressure gauge 6 and the flowmeter 20 comprise a data transmission module, which can remotely transmit the system pressure and flow signals to the central control room, so as to realize monitoring of the nitrogen filling pressure, and the pressure reducing valve can be processed in time after failure or after the nitrogen is used up, and the exhaust flow can be continuously monitored, so as to discover the increasing trend of hydrogen leakage in time.

[0035] In one embodiment, the system further comprises a pressure transmitter arranged on the pipeline between the seventh isolation valve 11 and the fourth isolation valve 14, so as to remotely transmit the pressure to the central control room, and realize continuous monitoring of the water tank pressure.

[0036] Through the pipeline setting of the above-mentioned embodiment, after the system is started, the isolation valves 2, 4, 5, 9, 11, 12 and 14 are opened, the blowdown valves 7 and 17 are closed, the bypass valve 10 is closed, the water seal 19 is filled with salt water from the top to the drain pipe with water escaping, the pressure reducing valves 1 and 3 are adjusted to the minimum, the needle valve 8 is closed to the minimum, the nitrogen cylinder pressure is confirmed to be normal, generally greater than 0.1 MPa, the pressure reducing valve 1 is slowly adjusted, the outlet pressure of the pressure reducing valve is controlled to be 0.1 MPa, the pressure reducing valve 2 is slowly adjusted, the outlet pressure of the pressure reducing valve is controlled to be 0.01 MPa, the needle valve 8 is slowly opened, after the water tank pressure exceeds 7 kPa, the constant pressure valve 15 is automatically opened to maintain the water tank pressure at 7 kPa, the needle valve 8 is adjusted according to the reading of the flowmeter 20 to ensure that the flowmeter 20 reads 0.2 liters per minute, or the flow is determined according to the actual situation on site. Maintain the opening of the needle valve 8, monitor the outlet pressure of the nitrogen cylinder, and replace the new nitrogen cylinder if the outlet pressure of the nitrogen cylinder is lower than 0.1 MPa. The uninterrupted and continuous replacement of hydrogen in the fixed cold water tank can be realized, the trend of the value change of the recording flowmeter can be monitored to monitor whether the hydrogen leakage increases, the hydrogen in the water tank is prevented from gathering to exceed the explosion limit, and the hydrogen explosion hazard is eliminated. The system can maintain long-term micro-positive pressure operation, avoid air leakage, and the water tank side and the exhaust side of the system have double overpressure protection, which can ensure the safe operation of the water tank. After the signal is remotely transmitted to the control system, the system pressure and flow can be remotely and continuously monitored. After the system is put into operation, the nitrogen consumption is greatly reduced, the workload of the operator is reduced, and the operation once a day is reduced to replacing the cylinder every 15 days.

[0037] Although the present application has been described in detail above with general description and specific embodiments, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application claimed.

Claims

1. A generator stator cooling water tank constant pressure continuous replacement system, characterized in that, It comprises a first pressure reducing valve, a first isolation valve, a second isolation valve, a pressure gauge, a needle valve, a third isolation valve, a hydrogen concentration detector, a fourth isolation valve, a first constant pressure valve, a flow meter, a stator cooling water tank, a nitrogen cylinder; The outlet of the nitrogen cylinder is connected to the main pipeline through the first pressure reducing valve, The main pipeline is sequentially connected with the first isolation valve, the needle valve, the stator cooling water tank, the fourth isolation valve, the first constant pressure valve and the flow meter, and the outlet of the flow meter is connected to the atmosphere through a pipeline, A pressure gauge is arranged between the first isolation valve and the needle valve, and the pressure gauge is connected to the main pipeline through the second isolation valve, A hydrogen concentration detector is arranged between the stator cooling water tank and the fourth isolation valve, and the hydrogen concentration detector is connected to the main pipeline through the third isolation valve; It further comprises a sixth isolation valve, a seventh isolation valve and a water seal device, the inlet of the water seal device is connected to the main pipeline between the needle valve and the stator cooling water tank through the sixth isolation valve, and the water seal device is connected to the stator cooling water tank through the seventh isolation valve; It further comprises a second pressure reducing valve and a fifth isolation valve arranged on the main pipeline, and the second pressure reducing valve and the fifth isolation valve are sequentially arranged between the first isolation valve and the needle valve; It further comprises a second constant pressure valve arranged between the sixth isolation valve and the water seal device.

2. The generator stator cooling water tank constant pressure continuous replacement system according to claim 1, characterized in that, It further comprises a bypass valve arranged between the needle valve and the seventh isolation valve and connected to a bypass pipeline connected in parallel with the sixth isolation valve.

3. The generator stator cooling water tank constant pressure continuous replacement system according to claim 1, characterized in that, It further comprises a first blowdown valve arranged on a first blowdown pipeline, and the first blowdown pipeline is arranged at the lowest end of the main pipeline.

4. The generator stator cooling water tank constant pressure continuous replacement system according to claim 1, characterized in that, It further comprises a second blowdown valve arranged on a second blowdown pipeline, and the second blowdown pipeline is arranged on the water seal device.

5. The generator stator cooling water tank constant pressure continuous replacement system according to claim 1, characterized in that, The pressure gauge and the flow meter comprise a data transmission module.

6. The generator stator cooling water tank constant pressure continuous replacement system according to claim 1, characterized in that, It further comprises a pressure transmitter arranged between the seventh isolation valve and the fourth isolation valve.

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