A device and method for removing condensate from a shaft-driven fan

Abstract

The application discloses a device and method for removing condensate of shaft air supply fan, and relates to the technical field of steam turbine shaft seal system and condensate discharge and recovery. The application comprises a shaft air supply fan, an inlet header, an outlet pipeline, a shaft seal heat exchanger and a condenser. The inlet of the shaft air supply fan is connected with the inlet header, and the outlet is connected with the outlet pipeline. The inlet header is connected with the shaft seal heat exchanger, and the shaft seal heat exchanger is connected with the condenser. A DN25 drain pipe is arranged at the bottom of the shaft air supply fan, and is connected with the side wall of the inlet header through a DN25 seamless steel pipe. First and second control valves are arranged on the drain pipe. Both of the valves are stop valves with a nominal pressure greater than or equal to 1.6 MPa and a distance greater than or equal to 100 mm. The application uses the self negative pressure of the inlet pipeline of the shaft air supply fan as a driving force to suck the condensate in the shaft air supply fan to the inlet header, and then to the condenser through the shaft seal heat exchanger, so as to solve the problem that the accumulated water in the standby shaft air supply fan cannot be discharged and the standby equipment cannot be normally put into operation, and to realize the recovery and utilization of the condensate.

Description

Technical Field

[0001] This invention belongs to the field of turbine shaft sealing system and condensate discharge and recovery technology, and in particular relates to a device and method for removing condensate from shaft-mounted fans. Background Technology

[0002] During the operation of a steam turbine generator set, the shaft sealing system plays a crucial role in preventing steam leakage from the turbine shaft end and the ingress of external air. Shaft seal exhaust steam is typically extracted by a shaft-mounted fan and sent to the shaft seal heat exchanger to heat the condensate, recovering the heat from the shaft seal steam and maintaining the normal operation of the turbine shaft sealing system. The shaft-mounted fans generally operate in a standby mode with one fan in use and the others interlocked. The two fans are arranged horizontally in parallel, with the outlet pipes higher than the fan bodies. To drain the condensate inside the fans, each fan casing typically has a DN25 drain pipe at the bottom, originally designed to drain directly into a trench. To ensure the standby fan can be activated promptly in case of an emergency, the standby fan inlet valve remains fully open, and the fan path is automatically switched using an outlet check valve.

[0003] However, in actual operation, it was found that some condensate would enter the standby shaft fan through the outlet pipe. Because the standby fan's inlet pipe was open, negative pressure formed inside the fan, preventing the condensate from being automatically discharged by gravity through the existing drain pipe, resulting in severe water accumulation inside the standby fan. This water accumulation caused excessive starting current, preventing the fan from starting normally and even leading to overload. Furthermore, when the operating fan failed, the standby fan could not be activated in time, posing a safety hazard of equipment backup failure and potentially causing unit shutdown. Simultaneously, the direct discharge of existing drain water into the sewer also resulted in the waste of condensate and heat, leading to poor system economics.

[0004] To address this issue, we provide a device and method for removing condensate from shaft-driven fans, thereby resolving the aforementioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a device and method for removing condensate from shaft-driven fans. The device directly utilizes the negative pressure generated by the inlet pipe of the shaft-driven fan itself during operation as a driving force to draw the condensate from the bottom of the shaft-driven fan casing to the inlet main pipe. The condensate then enters the shaft seal heat exchanger along with the shaft seal exhaust steam and flows into the condenser. This solves the problems of water accumulation inside the standby shaft-driven fan, the inability of the standby fan to start and operate normally, and condensate waste by using the system's own negative pressure characteristics, without the need for additional external power equipment.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] This invention provides a device and method for removing condensate from a shaft-driven fan, comprising a shaft-driven fan, an inlet manifold, an outlet pipe, a shaft seal heat exchanger, and a condenser. The inlet of the shaft-driven fan is connected to the inlet manifold, the outlet of the shaft-driven fan is connected to the outlet pipe, the inlet manifold is connected to the shaft seal exhaust inlet of the shaft seal heat exchanger, and the condensate outlet of the shaft seal heat exchanger is connected to the condenser. The device also includes a drain pipe and control valves. A DN25 drain pipe is provided at the bottom of the shaft-driven fan casing. The drain pipe is a DN25 seamless steel pipe, one end of which is connected to the drain pipe, and the other end of which is connected to the side wall of the inlet manifold. This allows the negative pressure generated by the operation of the shaft-driven fan in the inlet manifold to directly act on the drain pipe, serving as the driving force for condensate discharge. The control valves include a first control valve and a second control valve installed on the drain pipe. Both the first and second control valves are shut-off valves with a nominal pressure ≥1.6MPa, and the distance between the first and second control valves is ≥100mm.

[0008] Furthermore, the shaft-assisted fan includes a first shaft-assisted fan and a second shaft-assisted fan arranged in parallel. One of the first shaft-assisted fan and the second shaft-assisted fan serves as the operating fan and the other serves as the standby fan. The inlet valve of the standby fan is kept open and the outlet is equipped with a check valve. The drain pipe at the bottom of the casing of each shaft-assisted fan is connected to the inlet main pipe through its own drain pipe.

[0009] Furthermore, the drainage tube is made of carbon steel; the connection between the drainage tube and the side wall of the inlet main pipe is sealed.

[0010] Furthermore, the inlet manifold is connected to the shaft seal heat exchanger, and the shaft seal heat exchanger is connected to the condenser via pipelines. The shaft seal heat exchanger is also equipped with a condensate inlet and a condensate outlet to the low-pressure heater outlet.

[0011] Furthermore, the opening degree of both the first control valve and the second control valve is 30% to 70%, and the vacuum fluctuation of the shaft seal heat exchanger is ≤ ±0.005MPa.

[0012] The present invention also provides a method for removing condensate from a shaft-driven fan, comprising the following steps:

[0013] Provide the above-mentioned device for removing condensate from shaft-driven fans;

[0014] Start the shaft fan and use the negative pressure generated by the inlet manifold, i.e. the inlet pipe of the shaft fan itself, as the driving force for the discharge of condensate, so that negative pressure is formed in the inlet manifold;

[0015] Open the first control valve and the second control valve to draw the condensate collected in the shaft fan housing into the drain pipe through the drain pipe under the negative pressure of the inlet main pipe.

[0016] The condensate drawn into the inlet manifold is allowed to enter the shaft seal heat exchanger along with the shaft seal exhaust steam, and then flow into the condenser via the shaft seal heat exchanger.

[0017] Furthermore, the shaft-assisted fan includes a No. 1 shaft-assisted fan and a No. 2 shaft-assisted fan that are connected in parallel and interlocked with each other. One of them is in operation and the other is on standby. The inlet valve of the standby fan is kept fully open, and the outlet is automatically switched through a check valve. The drain pipe at the bottom of the casing of each shaft-assisted fan is connected to the inlet main pipe through a drain pipe.

[0018] Furthermore, the opening degree of the first control valve and the second control valve is adjusted to 30% to 70% to control the drainage volume and reduce the impact on the vacuum of the shaft seal heat exchanger, so that the vacuum fluctuation of the shaft seal heat exchanger is controlled within ±0.005MPa.

[0019] Furthermore, after starting the shaft fan, once a stable negative pressure of -0.002MPa to -0.008MPa is formed in the inlet main pipe, the first control valve and the second control valve are opened slowly in sequence. During operation, the valve status and pipeline patency are checked regularly, and the valve opening is finely adjusted as needed.

[0020] Furthermore, before installing the drainage pipe and control valve, clean the impurities in the original drainage pipe of the shaft fan; after installation, conduct a sealing test with a pressure of 0.3-0.5 MPa compressed air and hold the pressure for 30 minutes without leakage; the entire modification is completed while the machine is stopped.

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention uses negative pressure to divert condensate from the bottom of the shaft fan casing into the inlet manifold, completely solving the problems of overload of the running fan and water accumulation inside the standby fan preventing it from starting. This avoids unit shutdown due to equipment failure, reduces fan maintenance and replacement costs, extends equipment lifespan, and lowers operation and maintenance costs.

[0023] 2. This invention uses a dual-valve control system with a first control valve and a second control valve to precisely adjust the drainage volume, reduce the impact on the vacuum of the shaft seal heat exchanger, and keep the vacuum fluctuation of the shaft seal heat exchanger within ±0.005MPa, ensuring the stable operation of the shaft seal system and improving the unit's thermal efficiency.

[0024] 3. This invention recovers the condensate inside the shaft fan to the condenser, realizing the recycling of condensate, reducing the amount of demineralized water makeup water and heat loss, and reducing the heat exchange load of the condenser. It has significant energy-saving, water-saving, emission-reduction and efficiency-enhancing effects.

[0025] 4. This invention replaces external drainage power with the system's own negative pressure, does not rely on gravity drainage, and does not require additional equipment such as condensate pumps or vacuum pumps, thus not increasing energy consumption. It embodies the design concept of solving the system's own problems with the system's own characteristics.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a diagram of the overall system structure after the modification.

[0029] Figure 2 This is a diagram of the overall system structure before the modification.

[0030] Figure 3 This is a magnified view of a section of the drainage pipe, the drain pipe, and the double valve.

[0031] Figure 4 This is a flowchart of the method.

[0032] The attached diagram lists the components represented by each number as follows:

[0033] 1. Shaft-mounted fan; 1a. First shaft-mounted fan; 1b. Second shaft-mounted fan; 2. Inlet main pipe; 3. Outlet pipe; 4. Drain pipe; 5. Drain pipe; 6a. First control valve; 6b. Second control valve; 7. Shaft seal heat exchanger; 8. Condenser; 9. Check valve; 10. Inlet valve. Detailed Implementation

[0034] 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, and 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.

[0035] Example 1, please refer to Figure 1 , Figure 2 and Figure 3This invention relates to a device for draining condensate from a shaft-driven fan, comprising a shaft-driven fan 1, an inlet manifold 2, an outlet pipe 3, a shaft seal heat exchanger 7, and a condenser 8; the inlet of the shaft-driven fan 1 is connected to the inlet manifold 2, and the outlet of the shaft-driven fan 1 is connected to the outlet pipe 3; the inlet manifold 2 is connected to the shaft seal exhaust inlet of the shaft seal heat exchanger 7, and the condensate outlet of the shaft seal heat exchanger 7 is connected to the condenser 8; a DN25 drain pipe 4 is provided at the bottom of the shaft-driven fan 1 casing; the device also includes a drain pipe 5, a first control valve 6a, and a second control valve 6b; the drain pipe 5 is a DN25 drain pipe without... The steel pipe has one end connected to the drain pipe 4, and the other end connected to the side wall of the inlet main pipe 2. This allows the negative pressure generated by the operation of the shaft fan 1 in the inlet main pipe 2 to directly act on the drain pipe 4 and serve as the driving force for the discharge of condensate. The first control valve 6a and the second control valve 6b are both installed on the drain pipe 5 and are both shut-off valves with a nominal pressure ≥1.6MPa. The distance between the first control valve 6a and the second control valve 6b is ≥100mm. This distance is used to ensure that there is sufficient operating space between the two valves, which facilitates step-by-step isolation and safe maintenance.

[0036] In this embodiment, the drain pipe 5 is made of carbon steel, and the connection between the drain pipe 5 and the side wall of the inlet main pipe 2 is sealed to ensure no leakage; the inlet main pipe 2 and the shaft seal heat exchanger 7, and the shaft seal heat exchanger 7 and the condenser 8 are all connected by pipes; the shaft seal heat exchanger 7 is also provided with a condensate inlet and a condensate outlet to the low pressure heater outlet.

[0037] like Figure 1 As shown, the shaft-assisted fan 1 includes a first shaft-assisted fan 1a and a second shaft-assisted fan 1b arranged in parallel; one of the first shaft-assisted fan 1a and the second shaft-assisted fan 1b serves as the operating fan and the other serves as the standby fan, and the two are interlocked with each other; the inlet valve 10 of the standby fan is kept open, and a check valve 9 is provided at the outlet, and the fan path is automatically switched by relying on the outlet check valve 9; the drain pipe 4 at the bottom of the casing of each shaft-assisted fan 1 is connected to the inlet main pipe 2 through its own drain pipe 5.

[0038] The working principle is as follows: When the shaft-fed blower 1 is running, a negative pressure is formed in the inlet main pipe 2; this negative pressure is both the suction power for the shaft seal exhaust steam and is directly introduced into the drain pipe 4 by the diversion pipe 5, serving as the driving force for the discharge of condensate inside the shaft-fed blower 1 casing; the condensate entering from inside the shaft-fed blower 1 and the outlet pipe 3 collects in the drain pipe 4 at the bottom of the casing; since the drain pipe 4 is connected to the inlet main pipe 2 through the diversion pipe 5, driven by the negative pressure of the inlet main pipe 2 itself, the condensate in the drain pipe 4 flows through the diversion pipe 5 and the first control valve 6 The condensate drawn into the inlet manifold 2 is drawn by the first control valve 6a and the second control valve 6b. The condensate drawn into the inlet manifold 2 enters the shaft seal heat exchanger 7 along with the shaft seal exhaust steam, and then flows into the condenser 8 after passing through the shaft seal heat exchanger 7, thus completing the condensate recovery. By adjusting the opening of the first control valve 6a and the second control valve 6b, the amount of condensate discharged can be controlled, while reducing the impact on the vacuum of the shaft seal heat exchanger 7. The condensate discharge power comes entirely from the negative pressure characteristics of the system itself, without the need for external power, thus solving the system water accumulation problem with the system's own characteristics.

[0039] like Figure 2 The diagram shown is the overall system structure before the modification. Before the modification, the drain pipe 4 at the bottom of the housing of each shaft fan 1 was directly discharged into the ditch. The water inside the standby fan could not be discharged by gravity, which caused the standby fan to fail to start normally. The present invention adds a drain pipe 5 and a first control valve 6a and a second control valve 6b between the original drain pipe 4 and the inlet main pipe 2, thereby using the negative pressure of the system itself to solve the above problems.

[0040] like Figure 3 The diagram shows a partial enlarged view of the drain pipe, the diversion pipe, and the dual valves. The drain pipe 4 is connected to the diversion pipe 5. The first control valve 6a and the second control valve 6b are installed on the diversion pipe 5 in sequence, with a distance of ≥100mm between them. The other end of the diversion pipe 5 is connected to the side wall of the inlet main pipe 2. The original drainage ditch direction is retained and can be used as a backup discharge path.

[0041] Example 2, please refer to Figure 4 Based on Example 1, the present invention also provides a method for removing condensate from a shaft-driven fan, comprising the following steps:

[0042] Step 1: Provide the aforementioned device for draining condensate from the shaft fan; before installing the drain pipe 5, the first control valve 6a, and the second control valve 6b, clean the impurities in the original drain pipe 4 of the shaft fan 1 to ensure that the original drain pipe is unobstructed; make a hole in the original drain pipe at the bottom of the shaft fan 1, connect one end of the drain pipe 5 to the drain pipe 4, and connect the other end of the drain pipe 5 to the side wall of the inlet main pipe 2, ensuring that the connection is sealed and leak-free; install the first control valve 6a and the second control valve 6b in the middle of the drain pipe 5, with a distance of ≥100mm between them for easy operation and maintenance; after installation, conduct a sealing test with a pressure of 0.3~0.5MPa compressed air, and maintain the pressure for 30 minutes without leakage; the entire modification is completed in a shutdown state, with a construction period of approximately 1 day; this modification utilizes the system's own negative pressure drainage, requiring no additional power equipment;

[0043] Step 2: Start the shaft fan 1, using the negative pressure generated by the inlet manifold 2 (i.e., the inlet pipe of the shaft fan) as the driving force to create a negative pressure inside the inlet manifold 2; after the inlet manifold 2 forms a stable negative pressure of -0.002MPa to -0.008MPa, slowly open the first control valve 6a and the second control valve 6b in sequence; adjust the opening of the first control valve 6a and the second control valve 6b to 30% to 70%, ensuring that there is no condensate accumulation and the vacuum fluctuation of the shaft seal heat exchanger 7 is ≤ ±0.005MPa; after debugging, fix the valve opening and mark it;

[0044] Step 3: During the operation of the shaft fan 1, the internal condensate is collected in the original drain pipe 4 at the bottom. Driven by the negative pressure of the inlet main pipe 2, it is drawn into the inlet main pipe 2 through the diversion pipe 5, the first control valve 6a and the second control valve 6b. It then enters the shaft seal heat exchanger 7 with the shaft seal exhaust steam and finally flows into the condenser 8 to complete the recovery.

[0045] Step four: During operation, regularly inspect the valve status and pipeline patency, and fine-tune the valve opening as needed to ensure stable system operation; through dual valve control, the drainage volume can be controlled and the impact on the vacuum of shaft seal heat exchanger 7 can be reduced, so that the vacuum fluctuation of shaft seal heat exchanger 7 is controlled within ±0.005MPa; the present invention solves the condensate drainage problem with the system's own negative pressure characteristics, does not rely on gravity drainage, and does not require external drainage power equipment.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0047] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A device for removing condensate from a shaft-driven fan, comprising a shaft-driven fan (1), an inlet manifold (2), an outlet pipe (3), a shaft seal heat exchanger (7), and a condenser (8), wherein the inlet of the shaft-driven fan (1) is connected to the inlet manifold (2), the outlet of the shaft-driven fan (1) is connected to the outlet pipe (3), the inlet manifold (2) is connected to the shaft seal exhaust inlet of the shaft seal heat exchanger (7), and the condensate outlet of the shaft seal heat exchanger (7) is connected to the condenser (8); characterized in that, It also includes a drain pipe (5) and a control valve; the bottom of the housing of the shaft fan (1) is provided with a DN25 drain pipe (4), the drain pipe (5) is a DN25 seamless steel pipe, one end of the drain pipe (5) is connected to the drain pipe (4), and the other end of the drain pipe (5) is connected to the side wall of the inlet main pipe (2), so that the negative pressure generated by the operation of the shaft fan (1) in the inlet main pipe (2) directly acts on the drain pipe (4) and serves as the driving force for discharging the condensate in the housing of the shaft fan (1); the control valve includes a first control valve (6a) and a second control valve (6b) set on the drain pipe (5), the first control valve (6a) and the second control valve (6b) are both shut-off valves with a nominal pressure ≥1.6MPa, and the distance between the first control valve (6a) and the second control valve (6b) is ≥100mm.

2. The device for removing condensate from a shaft-driven fan according to claim 1, characterized in that, The shaft-assisted fan (1) includes a first shaft-assisted fan (1a) and a second shaft-assisted fan (1b) arranged in parallel. One of the first shaft-assisted fan (1a) and the second shaft-assisted fan (1b) serves as the operating fan and the other serves as the standby fan. The inlet valve (10) of the standby fan is kept open and the outlet is equipped with a check valve (9). The drain pipe (4) at the bottom of the casing of each shaft-assisted fan (1) is connected to the inlet main pipe (2) through its respective drain pipe (5).

3. The device for removing condensate from a shaft-driven fan according to claim 1, characterized in that, The drainage pipe (5) is made of carbon steel; the connection between the drainage pipe (5) and the side wall of the inlet main pipe (2) is sealed.

4. The device for removing condensate from a shaft-driven fan according to claim 1, characterized in that, The inlet manifold (2) is connected to the shaft seal heat exchanger (7) and the shaft seal heat exchanger (7) is connected to the condenser (8) by pipes. The shaft seal heat exchanger (7) is also provided with a condensate inlet and a condensate outlet to the low-pressure heater outlet.

5. The device for removing condensate from a shaft-driven fan according to claim 1, characterized in that, The opening degree of the first control valve (6a) and the second control valve (6b) is 30% to 70%, and the vacuum fluctuation of the shaft seal heat exchanger (7) is ≤ ±0.005MPa.

6. A method for removing condensate from a shaft-driven fan, characterized in that, Includes the following steps: A device for removing condensate from a shaft-driven fan, as described in any one of claims 1 to 5; Start the shaft fan (1), and use the negative pressure generated by the inlet manifold (2), i.e. the inlet pipe of the shaft fan itself, as the driving force for the discharge of condensate, so that negative pressure is formed in the inlet manifold (2); Open the first control valve (6a) and the second control valve (6b) to draw the condensate collected in the housing of the shaft fan (1) into the drain pipe (4) through the drain pipe (5) under the negative pressure of the inlet main pipe (2). The condensate drawn into the inlet manifold (2) is allowed to enter the shaft seal heat exchanger (7) along with the shaft seal exhaust steam, and then flow into the condenser (8) through the shaft seal heat exchanger (7).

7. The method for removing condensate from a shaft-driven fan according to claim 6, characterized in that, The shaft-assisted fan (1) includes a No. 1 shaft-assisted fan (1a) and a No. 2 shaft-assisted fan (1b) that are connected in parallel and interlocked with each other. One of them is in operation and the other is on standby. The inlet valve (10) of the standby fan is kept fully open, and the outlet is automatically switched through a check valve (9). The drain pipe (4) at the bottom of the casing of each shaft-assisted fan (1) is connected to the inlet main pipe (2) through a drain pipe (5).

8. The method for removing condensate from a shaft-driven fan according to claim 6, characterized in that, Adjust the opening of the first control valve (6a) and the second control valve (6b) to 30% to 70% to control the drainage volume and reduce the impact on the vacuum of the shaft seal heat exchanger (7), so that the vacuum fluctuation of the shaft seal heat exchanger (7) is controlled within ±0.005MPa.

9. The method for removing condensate from a shaft-driven fan according to claim 6, characterized in that, After starting the shaft fan (1), wait for the inlet main pipe (2) to form a stable negative pressure of -0.002MPa to -0.008MPa, and then slowly open the first control valve (6a) and the second control valve (6b) in sequence; during operation, regularly inspect the valve status and pipeline patency, and finely adjust the valve opening as needed.

10. The method for removing condensate from a shaft-driven fan according to claim 6, characterized in that, Before installing the drain pipe (5) and control valve, clean the impurities in the original drain pipe (4) of the shaft fan (1); after installation, conduct a sealing test with a test pressure of 0.3-0.5 MPa compressed air and hold the pressure for 30 minutes without leakage; the entire modification is completed in a shutdown state.

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