Shaft seal heater drain system

Abstract

The present disclosure relates to a shaft seal heater drainage system, comprising a shaft seal heater, a water seal device and a drainage pipeline connected between the water seal device and the shaft seal heater, the water seal device comprising a water seal cylinder and a water seal suction pipe, the drainage pipeline being connected with the water seal cylinder, and a first emptying pipe being connected with the top of the water seal cylinder; one end of the water seal suction pipe extends into the water seal cylinder and extends close to the bottom of the water seal cylinder, and the other end of the water seal suction pipe extends out of the water seal cylinder and is connected to a low-pressure heater drainage pump to pump the drainage to a condensate system. Through the above technical solution, shaft drainage enters the water seal cylinder through the drainage pipeline, and then the drainage is pumped to the condensate system by the drainage pump arranged on the water seal suction pipe, so that the shaft drainage no longer passes through the condenser, eliminating the influence of shaft drainage on the vacuum of the condenser and eliminating the risk of air leakage, thereby solving the problem that air enters the condenser at low load, which cannot guarantee the vacuum of the unit and poses a safety risk.

Description

Technical Field

[0001] The present disclosure relates to the technical field of steam turbine draining, and in particular to a shaft seal heater draining system. Background Art

[0002] The shaft seal heater is a crucial heat exchange device in the turbine shaft seal system. Its primary function is to collect the steam-gas mixture from the turbine seal system and from the high- and medium-pressure valve stems, cooling it to form a drain. During operation, the drain is transported to the main engine condenser throat for cooling, then pumped through the condensate pump to the low-pressure heater for further heating before being discharged from the low-pressure heater into the condensate system.

[0003] Currently, drain water is heated and directly fed into the condenser throat. Under low load conditions, the existing drain U-tube fails to form an effective seal, allowing air to enter the condenser, disrupting unit vacuum and posing a safety hazard. Furthermore, drain water discharged from the shaft seal heater is hot. After entering the condenser, it is cooled by circulating water and then heated by the low-pressure heater. This repeated cooling and heating cycle impacts the unit's economical operation. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a shaft seal heater drain system to solve the problem that air enters the condenser at low load, the vacuum of the unit cannot be guaranteed, and there is a safety hazard.

[0005] In order to achieve the above-mentioned object, the present disclosure provides a shaft seal heater drain system, comprising a shaft seal heater;

[0006] Water seals; and

[0007] A drain pipe is connected between the water seal device and the shaft seal heater,

[0008] Among them, the water seal device includes a water seal cylinder and a water seal suction pipe, the drain pipe is connected to the water seal cylinder, and the top of the water seal cylinder is connected to a first drain pipe; one end of the water seal suction pipe extends into the water seal cylinder and extends to near the bottom of the water seal cylinder, and the other end passes through the water seal cylinder and is connected to the low-pressure drain pump to pump the drain to the condensate system.

[0009] Optionally, the hydrophobic system further comprises a hydrophobic expansion tank and a low-pressure heater for adding hydrophobic water into the hydrophobic expansion tank; wherein,

[0010] The hydrophobic expansion tank is provided with a water outlet pipe, the water outlet pipe is connected to the water seal suction pipe, and the low-pressure hydrophobic pump is arranged at the connection between the water outlet pipe and the water seal suction pipe.

[0011] Optionally, a second drain pipe is provided on the top of the hydrophobic expansion container.

[0012] Optionally, a third drain pipe is provided on the water seal suction pipe, one end of the third drain pipe is connected to the second drain pipe, and the other end of the third drain pipe is connected to the water seal suction pipe.

[0013] Optionally, a second control valve is further provided on the water seal suction pipe, and the second control valve is located upstream of a connection position between the second emptying pipe and the water seal suction pipe.

[0014] Optionally, the water seal device further includes a condenser, a steam pump water seal connected to the condenser, and an overflow pipe provided on the wall of the water seal cylinder;

[0015] One end of the overflow pipe is communicated with the water seal cylinder, and the other end is communicated with the steam pump water seal device, so as to transport the overflowed drain water to the condenser through the steam pump water seal device.

[0016] Optionally, the system further includes a steam pump sealing water return pipeline, one end of which is connected to the steam pump, and the other end is connected to the steam pump water sealer, and a fourth control valve is provided on the steam pump sealing water return pipeline.

[0017] Optionally, a first control valve is provided on the first exhaust pipe.

[0018] Optionally, the water seal device further includes a water injection pipe, which is arranged on the wall of the water seal cylinder and is provided with a third control valve.

[0019] Optionally, a water level gauge is provided on the shaft seal heater for monitoring the water level of the shaft seal heater.

[0020] Through the above technical solution, the shaft drain enters the water seal cylinder through the drain pipe, and then is pumped to the condensate system by the drain pump on the water seal suction pipe, so that the shaft drain no longer passes through the condenser, eliminating the influence of the shaft drain on the condenser vacuum and the hidden danger of air leakage, thereby solving the problem of air entering the condenser at low load, unable to ensure the vacuum of the unit, and posing a safety hazard.

[0021] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0023] Figure 1 Schematic diagram of a shaft seal heater drain system according to an exemplary embodiment of the present disclosure.

[0024] Description of Reference Numerals

[0025] 1. Shaft seal heater; 2. Drain pipe; 3. Water seal device; 31. Water seal cylinder; 311. First drain pipe; 312. First control valve; 32. Water seal suction pipe; 321. Third drain pipe; 322. Second control valve; 33. Water injection pipe; 331. Third control valve; 34. Overflow pipe; 4. Drain expansion tank; 41. Water outlet pipe; 42. Second drain pipe; 5. Steam pump water seal device; 51. Steam pump sealing water return line; 52. Fourth control valve; 6. Condenser. DETAILED DESCRIPTION

[0026] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0027] In this disclosure, unless otherwise indicated, directional terms such as "up, down, left, and right" generally refer to directions in normal use of the shaft seal heater hydrophobic system provided by this disclosure. "Inside" and "outside" refer to the inside and outside of the outline of the corresponding component. "Far" and "near" refer to distance from and proximity to a certain component. The terms "first" and "second" used in this disclosure are intended to distinguish one element from another and do not have a sense of order or importance.

[0028] The present disclosure provides a shaft seal heater drain system, such as Figure 1 As shown, it includes a shaft seal heater 1, a water seal device 3 and a drain pipe 2 connected between the water seal device 3 and the shaft seal heater 1. Among them, the water seal device 3 includes a water seal cylinder 31 and a water seal suction pipe 32, and the drain pipe 2 is connected to the water seal cylinder 31. The top of the water seal cylinder 31 is connected to a first drain pipe 311, which is used to connect the interior of the water seal cylinder 31 to the atmosphere, balance the internal and external air pressure, ensure that there is no accumulation inside the water seal cylinder 31, reduce the amplitude of air pressure fluctuations, and prevent water seal damage. One end of the water seal suction pipe 32 extends into the water seal cylinder 31 and extends to near the bottom of the water seal cylinder 31, and the other end passes through the side wall of the water seal cylinder 31 and is connected to the low-pressure water pump, so that the shaft seal water pump can be sent to the condensate system (not shown in the figure) through the low-pressure water pump (not shown in the figure), which can directly recycle its heat energy and working fluid, thereby improving system efficiency. Since the water seal suction pipe 32 has a pressure difference of the water column height after being inserted into the water seal cylinder 31, the water seal suction pipe 32 always remains in a water state, which can achieve continuous and uninterrupted sealing between the water seal cylinder 31 and the atmosphere, and the effect is reliable.

[0029] During actual use, water is first injected into the water seal cylinder 31. When the water reaches a certain height, the injection is stopped. The steam is cooled by the shaft seal heater 1 and becomes hydrophobic. The shaft-added hydrophobic water is discharged into the water seal cylinder 31 through the hydrophobic pipe 2. Since the water seal cylinder 31 is connected to the atmosphere through the first drain pipe 311, as long as the shaft-added hydrophobic water enters the water seal cylinder 31 through the hydrophobic pipe 2, the hydrophobic water entering the water seal cylinder 31 can be sucked out by the low-pressure hydrophobic pump through the water seal suction pipe 32 and pumped into the condensate system. The hydrophobic water here refers to the water formed by the cooling of the steam-gas mixture overflowing from the steam turbine steam seal system and the high and medium pressure gate rods, that is, steam condensate; the shaft-added hydrophobic water refers to the hydrophobic water formed by the steam cooling by the shaft seal heater.

[0030] Through the above technical solution, the shaft drain enters the water seal cylinder 31 through the drain pipe 2, and then is pumped to the condensate system by the drain pump on the water seal suction pipe 32, so that the shaft drain no longer passes through the condenser 6, eliminating the influence of the shaft drain on the vacuum of the condenser 6 and the hidden danger of air leakage, thereby solving the problem that air enters the condenser 6 at low load, the vacuum of the unit cannot be guaranteed, and there is a safety hazard.

[0031] In some embodiments, the drain system may further include a drain expansion tank 4 and a low-pressure heater (not shown) for adding drain water to the drain expansion tank 4. The drain expansion tank 4 is provided with an outlet pipe 41 located at the bottom of the drain expansion tank 4. One end of the outlet pipe 41 is connected to the drain expansion tank 4, and the other end is connected to the water seal suction pipe 32. A low-pressure heater drain pump is located at the junction of the outlet pipe 41 and the water seal suction pipe 32. In actual use, the low-pressure heater discharges drain water into the drain expansion tank 4. After entering the drain expansion tank 4, the drain water is discharged through the outlet pipe 41 and mixed with the drain water in the water seal suction pipe 32. The low-pressure heater drain pump is activated to extract the drain water in the drain expansion tank 4 and the drain water in the water seal suction pipe 32 and pump them to the condensate system. It should be noted that the low-pressure heater utilizes steam that has performed some work within the steam turbine, pumping it into the heater to heat condensate. This raises the condensate's temperature, reduces energy loss, and improves the thermal system's circulation efficiency. After absorbing the heat from the heating steam, the condensate is discharged through the heater's outlet pipe into the drain expansion tank 4. The drain expansion tank 4 expands the volume and reduces the pressure of the drain discharged from the low-pressure heater. This also increases the amount of water flowing from the LP heater drain pump outlet to the condensate system, reducing the amount of drain circulating and improving the unit's operating efficiency.

[0032] In some embodiments, a second drain pipe 42 may be provided on the top of the hydrophobic expansion container 4. The second drain pipe 42 connects the hydrophobic expansion container 4 to the atmosphere, ensuring that there is no accumulation of water inside the hydrophobic expansion container 4, allowing water to flow smoothly from the water seal suction pipe 32, and preventing the water seal device 3 from failing.

[0033] In some embodiments, the water seal suction pipe 32 may be provided with a third drain pipe 321, one end of which is connected to the second drain pipe 42 and the other end to the water seal suction pipe 32. Because the water seal suction pipe 32 is connected to the outlet pipe 41, and the pressure of the hydrophobic water discharged from the water seal suction pipe 32 is relatively high, the hydrophobic water in the water seal suction pipe 32 is likely to continuously flow into the hydrophobic expansion tank 4, a phenomenon known as siphoning. This can result in a low water output from the LP-type hydrophobic pump, impacting system operation. The provision of the third drain pipe 321 allows the high-pressure hydrophobic water in the water seal suction pipe 32 to be discharged through the third drain pipe 321, releasing its pressure and equalizing it with the hydrophobic water pressure in the outlet pipe 41. Therefore, after the hydrophobic water in the outlet pipe 41 and the hydrophobic water in the water seal suction pipe 32 mix, the pressure is relatively stable and is then pumped out by the LP-type hydrophobic pump and delivered to the condensate system. In this way, not only the amount of water from the low-pressure heater drain pump to the condensate system is increased, but also the effectiveness of the water seal device 3 is guaranteed, while the heat of the shaft heater drain is effectively recovered, thereby improving the economic efficiency of the unit operation.

[0034] In some embodiments, the water seal suction pipe 32 may also be provided with a second control valve 322, located upstream of the connection between the second drain pipe 42 and the water seal suction pipe 32. In the event of a fault on the LP heater drain pump side, the second control valve 322 is closed, disconnecting the water seal device 3 from the faulty equipment, allowing the faulty equipment to be repaired, thereby avoiding continued damage to the equipment that could affect the safe operation of the entire unit.

[0035] In some embodiments, the water seal device 3 may further include a condenser 6, a steam pump water seal 5 connected to the condenser 6, and an overflow pipe 34 disposed on the wall of the water seal cylinder 31. One end of the overflow pipe 34 is connected to the water seal cylinder 31, and the other end is connected to the steam pump water seal 5, so that overflowing drain water is transported through the steam pump water seal 5 to the condenser 6. During actual operation, when the unit is under high load, for example, at 500 MW or above, the pressure within the drain expansion tank 4 increases, and the pressure within the drain expansion tank 4 exceeds the pressure within the water seal cylinder 31. At this time, water no longer enters the water seal suction pipe 32. After the shaft-added drain water enters the water seal cylinder 31, it can overflow into the steam pump water seal 5 through the overflow pipe 34 and be recovered into the condenser 6. In this way, the overflowing drain water, after passing through the steam pump water seal 5 and then entering the condenser 6, can also eliminate the impact of the shaft-added drain water on the vacuum of the condenser 6, thereby improving the safety and reliability of the unit operation.

[0036] In some embodiments, the system may further include a steam pump sealing water return pipeline 51, one end of which is connected to the steam pump (not shown in the figure), and the other end is connected to the steam pump water seal 5, and a fourth control valve 52 is provided on the steam pump sealing water return pipeline 51. The steam pump continuously returns water during operation, and water is introduced into the steam pump water seal 5 through the steam pump sealing water return pipeline 51 to recycle the water, thereby saving costs and improving the economic efficiency of the unit operation. It should be noted that the fourth control valve 52 is in a normally open state, and continuously returns water to the steam pump water seal. When an equipment failure occurs on the steam pump side, the fourth control valve 52 is closed and disconnected from the steam pump side, which facilitates the maintenance of system equipment and improves the reliability of the unit operation.

[0037] In some embodiments, the first drain pipe 311 may be provided with a first control valve 312. When the main body of the water seal 31 is assembled and welded, water is injected into the water seal 31. At this time, the first control valve 312 is closed, completely sealing the water seal 31. A leak check is then performed to observe whether the water seal 31 is leaking. After injecting water to check for leaks, the first control valve 312 is opened again. It should be noted that after injecting water to check for leaks, the first control valve 312 is normally open during operation, allowing the interior of the water seal 31 to communicate with the atmosphere and ensuring that no accumulation of water is present within the water seal 31.

[0038] In some embodiments, the water seal device 3 may further include a water injection pipe 33, which is disposed on the wall of the water seal cylinder 31 and is equipped with a third control valve 331. During actual use, the third control valve 331 is opened, and water is injected into the water seal cylinder 31 through the water injection pipe 33 until the water in the water seal cylinder 31 overflows from the overflow pipe 34, thereby creating a vacuum in the water seal cylinder 31. The third control valve 331 is then closed. Water can be added to the water seal cylinder 31 through the water injection pipe 33, ensuring the effectiveness of the water seal device 3. The third control valve 331 controls the flow rate of the injected water and prevents backflow when the water pressure decreases or stops during water replenishment.

[0039] In some embodiments, a water level gauge (not shown in the figure) may be provided on the shaft seal heater 1 to monitor the water level of the shaft seal heater 1. During the operation of the unit, under normal circumstances, the shaft water level does not exceed 1 / 3 of the full water level. If the water level of the shaft seal heater is high, it will affect the condensation of the steam-gas mixture entering the shaft seal heater 1 and the slight negative pressure of the shaft seal heater 1, which is not conducive to the return of steam from the shaft seal. If the water level is higher, it will easily cause water to enter the fan of the shaft seal heater 1, and then trip, or even cause water to enter the shaft seal main pipe, threatening the safe operation of the unit. If the water level of the shaft seal heater is low, the water seal will be damaged, affecting the vacuum of the condenser 6. Therefore, a water level gauge is provided to monitor the water level of the shaft seal heater 1 to ensure the safe operation of the unit.

[0040] The specific working process of this system is:

[0041] When the unit is under low load: The third control valve 331 opens, and water is injected into the water seal cylinder 31 through the water injection pipe 33 until the water in the water seal cylinder 31 overflows from the overflow pipe 34, creating a vacuum in the water seal cylinder 31. The third control valve 331 then closes. The shaft seal heater 1 opens, and the shaft heater drain enters the water seal cylinder 31 through the drain pipe 2 and is discharged through the water seal suction pipe 32. Simultaneously, the low-pressure heater drains water into the drain expansion tank 4, which is then discharged through the outlet pipe 41 and mixed with the drain in the water seal suction pipe 32. The low-pressure heater drain pump opens, pumping the drain from the drain expansion tank 4 and the drain from the water seal suction pipe 32 to the condensate system.

[0042] When the unit is under high load: the pressure in the hydrophobic expansion tank 4 gradually increases. When the pressure in the hydrophobic expansion tank 4 is greater than the pressure in the water seal cylinder 31, no more hydrophobic water will enter the water seal suction pipe 32, and the water level of the hydrophobic water entering the water seal cylinder 31 will gradually rise. After rising to a certain height, the hydrophobic water can overflow into the steam pump water seal 5 through the overflow pipe 34 connected thereto, and then be recovered to the condenser 6.

[0043] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0045] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A shaft seal heater drain system, characterized in that: include: Shaft seal heater; Water seal device; as well as A drain pipe is connected between the water seal device and the shaft seal heater, The water seal device includes a water seal cylinder and a water seal suction pipe. The drain pipe is connected to the water seal cylinder, and the top of the water seal cylinder is connected to a first drain pipe. One end of the water seal suction pipe extends into the water seal cylinder and extends to near the bottom of the water seal cylinder, and the other end passes through the water seal cylinder and is connected to the low-pressure drain pump to pump the drain water to the condensate system. The water seal device also includes a condenser, a steam pump water seal connected to the condenser, and an overflow pipe arranged on the wall of the water seal cylinder; one end of the overflow pipe is connected to the water seal cylinder, and the other end is connected to the steam pump water seal, so as to transport the overflowed drainage to the condenser through the steam pump water seal. The system also includes a steam pump sealing water return pipeline, one end of the steam pump sealing water return pipeline is connected to the steam pump, and the other end is connected to the steam pump water seal, and a fourth control valve is provided on the steam pump sealing water return pipeline.

2. The shaft seal heater drain system according to claim 1, characterized in that: The hydrophobic system further includes a hydrophobic expansion tank and a low-pressure heater for adding hydrophobic water into the hydrophobic expansion tank; wherein, The hydrophobic expansion tank is provided with a water outlet pipe, the water outlet pipe is connected to the water seal suction pipe, and the low-pressure hydrophobic pump is arranged at the connection between the water outlet pipe and the water seal suction pipe.

3. The shaft seal heater drain system according to claim 2, characterized in that: A second drain pipe is provided on the top of the hydrophobic expansion container.

4. The shaft seal heater drain system according to claim 3, characterized in that: A third drain pipe is provided on the water seal suction pipe. One end of the third drain pipe is connected to the second drain pipe, and the other end is connected to the water seal suction pipe.

5. The shaft seal heater drain system according to claim 4, characterized in that: The water seal suction pipe is further provided with a second control valve, and the second control valve is located upstream of the connection position between the second emptying pipe and the water seal suction pipe.

6. The shaft seal heater drain system according to claim 1, characterized in that: The first exhaust pipe is provided with a first control valve.

7. The shaft seal heater drain system according to claim 1, characterized in that: The water seal device further comprises a water injection pipe, which is arranged on the cylinder wall of the water seal cylinder and is provided with a third control valve.

8. The shaft seal heater drain system according to claim 1, characterized in that: The shaft seal heater is provided with a water level gauge for monitoring the water level of the shaft seal heater.

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