Cleaning method for gland steam supply piping

Abstract

The present invention provides a method for cleaning gland steam supply piping that allows for the recovery of the steam used to clean the gland steam supply piping in the condenser while suppressing the rise in internal pressure of the condenser. [Solution] A method for cleaning gland steam supply piping in a steam turbine plant comprising a steam turbine having an openable and closable manhole, a condenser capable of returning steam exhausted from the steam turbine back into water, gland steam supply piping capable of supplying steam to the gland of the steam turbine, and drain piping branching from the gland steam supply piping and connected to the condenser, the method comprising: a preparation step of opening the manhole and installing an exhaust passage in the manhole; and a piping cleaning step after the preparation step of circulating steam through the gland steam supply piping and guiding the steam flowing through the gland steam supply piping to the condenser through the drain piping.

Description

Technical Field

[0001] This disclosure relates to a method for cleaning a main steam supply pipe.

Background Art

[0002] Patent Document 1 discloses a steam turbine plant. This steam turbine plant includes a steam turbine and a condenser. The condenser cools and condenses the steam that has driven the rotor of the steam turbine to produce condensate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a sealing mechanism is provided in the steam turbine to prevent steam leakage and air inflow from the gap where the rotor penetrates the turbine compartment. This sealing mechanism is called a gland. A sealing steam slightly higher in pressure than atmospheric pressure is supplied to the gland through a pipe. Thereby, steam leakage and air inflow are prevented. Hereinafter, the sealing steam supplied to the gland is referred to as "main steam", and the pipe for supplying the main steam to the gland is referred to as "main steam supply pipe".

[0005] When rust, dust, etc. accumulate in this main steam supply pipe, blockage occurs in the main steam supply pipe. Therefore, it is necessary to clean the inside of the main steam supply pipe. As a method for cleaning the main steam supply pipe, there is a method in which a temporary pipe is connected to the main steam supply pipe, high-pressure steam is sent into the main steam supply pipe, and the rust and dust in the main steam supply pipe are discharged to the atmosphere through the temporary pipe. However, with this method, a large amount of steam contaminated with rust and dust is released into the atmosphere.

[0006] Recently, a method has been employed to recover the steam used to clean the gland steam supply piping into the condenser. However, with this method, the steam used to clean the gland steam supply piping is sent to the condenser before the condenser reaches a vacuum. In other words, high-pressure steam is supplied to the condenser under atmospheric pressure. This can cause the internal pressure of the condenser to rise, potentially leading to damage.

[0007] This disclosure was made to solve the above problems and aims to provide a method for cleaning gland steam supply piping that can recover the steam used to clean the gland steam supply piping in the condenser while suppressing the rise in internal pressure of the condenser. [Means for solving the problem]

[0008] To solve the above problems, the method for cleaning a gland steam supply pipe according to the present disclosure is a method for cleaning a gland steam supply pipe in a steam turbine plant comprising: a steam turbine having an openable and closable manhole; a condenser capable of returning steam exhausted from the steam turbine back into water; a gland steam supply pipe capable of supplying steam to the gland of the steam turbine; and a drain pipe branching off from the gland steam supply pipe and connected to the condenser, the method comprising: a preparation step of opening the manhole and installing an exhaust passage in the manhole; and a pipe cleaning step, after the preparation step, of circulating steam through the gland steam supply pipe and guiding the steam flowing through the gland steam supply pipe to the condenser through the drain pipe. [Effects of the Invention]

[0009] According to the gland steam supply piping cleaning method of this disclosure, it is possible to recover the steam used to clean the gland steam supply piping in the condenser while suppressing the rise in internal pressure of the condenser. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a steam turbine plant according to an embodiment of the present disclosure. [Figure 2] This flowchart shows the procedure for a method of cleaning a gland steam supply pipe according to an embodiment of the present disclosure. [Figure 3] This figure illustrates a method for cleaning gland steam supply piping according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0011] (Configuration of a steam turbine plant) Hereinafter, a steam turbine plant 1 according to an embodiment of this disclosure will be described with reference to Figures 1 to 3.

[0012] As shown in Figure 1, the steam turbine plant 1 comprises a boiler 2, a steam turbine 20, a condenser 30, a feedwater pump 3, a main steam line 4, a feedwater line 5, a vacuum device 6, a spray unit 7, a second boiler 8, a gland steam supply pipe 40, a supply-side gland steam pressure control valve 43, a gland steam discharge pipe 45, a second condenser 9, a relief pipe 48, a relief-side gland steam pressure control valve 49, a drain pipe 50, and a drain valve 53.

[0013] Boiler 2 generates steam ST. Steam turbine 20 is driven by the steam ST generated in boiler 2. The configuration of steam turbine 20 will be described in detail later. Condenser 30 is capable of cooling and condensing the steam ST exhausted from steam turbine 20 back into water. The configuration of condenser 30 will be described in detail later.

[0014] The main steam line 4 connects the boiler 2 and the steam turbine 20. Steam ST generated in the boiler 2 is supplied to the steam turbine 20 via this main steam line 4. The feedwater line 5 connects the condenser 30 and the boiler 2. The feedwater pump 3 is located in the middle of the feedwater line 5. The water that has returned to liquid form from the steam ST in the condenser 30 is supplied to the boiler 2 through the feedwater line 5 by the feedwater pump 3.

[0015] (Steam turbine) The steam turbine 20 has a rotor 21, a turbine casing 22, a gland 23, and a manhole 24.

[0016] (Rotor) The rotor 21 is covered by the turbine casing 22. The rotor 21 rotates within the turbine casing 22. In the embodiment, the rotor 21 extends in the horizontal direction. The rotor 21 penetrates the turbine casing 22, and one end of the rotor 21 is connected to, for example, the rotor 21 of a generator (not shown). The rotor 21 is rotationally driven about its central axis by the steam ST supplied into the turbine casing 22 from the main steam line 4. A rotor such as a generator (not shown) is connected to the rotor 21, and when the rotor 21 is rotationally driven, the generator and the like operate.

[0017] (Turbine Casing) The turbine casing 22 opens downward. The downstream end of the main steam line 4 is connected to the upper wall of the turbine casing 22. Steam ST for driving the rotor 21 is supplied into the turbine casing 22 through the main steam line 4. The turbine casing 22 partitions and forms the internal space A1 of the steam turbine 20.

[0018] (Gland) The gland 23 is attached to both ends of the rotor 21 at the portion penetrating the turbine casing 22. The gland 23 is a sealing mechanism for preventing steam leakage and air inflow from the gap between the rotor 21 and the turbine casing 22. Sealing steam ST (gland steam) slightly higher in pressure than the atmospheric pressure is supplied to the gland 23 through a gland steam supply pipe 40 described later. Thereby, steam leakage and air inflow are prevented.

[0019] (Manhole) The manhole 24 is provided in the turbine compartment 22. The manhole 24 is provided as an access port for an operator to enter the inside of the turbine compartment 22 for maintenance of the steam turbine 20 and the like. The manhole 24 has an opening 24a and a lid 24b. The opening 24a penetrates the turbine compartment 22. The lid 24b is detachably attached to the opening 24a. By attaching and detaching the lid 24b, the manhole 24 can open and close the turbine compartment 22. The manhole 24 and the turbine compartment 22 are formed of a metal such as iron, for example.

[0020] (Condenser) The condenser 30 is provided below the steam turbine 20. The condenser 30 has a shell 31, a heat transfer tube group 32, an inlet water chamber 33, and an outlet water chamber 34.

[0021] (Shell) The shell 31 partitions and forms the internal space A2 of the condenser 30. In the internal space A2 of the condenser 30, a heat transfer tube group 32 and the like described later are provided. And the internal space A2 of the condenser 30 communicates with the internal space A1 of the steam turbine 20 and is sealed. Through the opening of the shell 31, the steam ST exhausted from the steam turbine 20 is supplied to the condenser 30 from above. As an example, the steam turbine 20 is a downflow exhaust type that exhausts the steam ST downward. Also, as another example of the steam turbine 20, there is a side exhaust type that exhausts the steam ST sideways.

[0022] (Heat transfer tube group) The heat transfer tube group 32 is arranged in the middle part in the vertical direction inside the shell 31. The heat transfer tube group 32 includes a plurality of heat transfer tubes 32a. The plurality of heat transfer tubes 32a are substantially parallel to each other. Each of the plurality of heat transfer tubes 32a extends in the horizontal direction. At both ends in the extending direction of each of the plurality of heat transfer tubes 32a, the ends are supported by the shell 31.

[0023] (Inlet water chamber and outlet water chamber) An inlet water chamber 33 and an outlet water chamber 34 are formed in the middle of the shell 31 in the vertical direction. The inlet water chamber 33 and the outlet water chamber 34 are formed on one side and the other side of the shell 31 in the horizontal direction. The inlet water chamber 33 is formed so as to extend a part of the shell 31 that extends in the vertical direction to one side in the horizontal direction. The outlet water chamber 34 is formed so as to extend a part of the shell 31 that extends in the vertical direction to the other side in the horizontal direction. One end of a plurality of heat transfer tubes 32a is connected to the inlet water chamber 33, and the other end of a plurality of heat transfer tubes 32a is connected to the outlet water chamber 34. Cooling water is supplied to the inlet water chamber 33 from outside the condenser 30. The cooling water supplied to the inlet water chamber 33 flows into the plurality of heat transfer tubes 32a. The cooling water flows through the heat transfer tubes 32a from the inlet water chamber 33 to the outlet water chamber 34. As the cooling water flows through the heat transfer tubes 32a, it exchanges heat with the steam ST in the condenser 30. This cools and condenses the steam ST in the condenser 30 back into water. The cooling water that has passed through the heat transfer tubes 32a is supplied to the outlet water chamber 34. The cooling water supplied to the outlet water chamber 34 is discharged to the outside of the condenser 30 through a drain outlet (not shown). The shell 31, inlet water chamber 33, and outlet water chamber 34 are formed from a metal such as iron.

[0024] In the shell 31, a hot well 35 is formed below the heat transfer tube group 32. In the hot well 35, water that has condensed from steam ST is stored. The upstream end of the feedwater line 5 is connected to the bottom of the shell 31.

[0025] (vacuum equipment) The vacuum device 6 creates a vacuum in the condenser 30, increasing the vacuum level in the internal space A2 of the condenser 30. This increase in vacuum level improves the heat exchange efficiency of the condenser 30. The vacuum device 6 comprises a vacuum device body 6a and a vacuum line 6b. The vacuum device body 6a includes a vacuum pump (not shown), etc. The vacuum device body 6a draws gas from the internal space A2 of the condenser 30. The vacuum line 6b connects the shell 31 of the condenser 30 to the vacuum device body 6a, guiding the gas drawn in by the vacuum device body 6a to the outside of the condenser 30.

[0026] (Spray part) The spray unit 7 is located inside the turbine casing 22 of the steam turbine 20, below the rotor 21 and the manhole 24. The spray unit 7 sprays water downwards. The spraying of water by the spray unit 7 suppresses the swirling of steam ST inside the condenser 30.

[0027] (Second boiler) The second boiler 8 generates steam ST, which is supplied to the ground 23. The second boiler 8 is located separately from boiler 2.

[0028] (Gland steam supply piping) The gland steam supply pipe 40 connects the second boiler 8 and the gland 23. The gland steam supply pipe 40 is capable of supplying steam ST generated in the second boiler 8 to the gland 23. The gland steam supply pipe 40 has a main supply channel 41 and a branch supply channel 42. The main supply channel 41 of the gland steam supply pipe 40 is also called the gland steam main pipe. The upstream end of the main supply channel 41 is connected to the second boiler 8. The branch supply channel 42 extends from the downstream end of the main supply channel 41, branching out to each gland 23.

[0029] (Supply side gland steam pressure regulating valve) The supply-side gland steam pressure control valve 43 is installed to open and close the gland steam supply pipe 40 and controls the pressure in the gland steam supply pipe 40 so that gland steam (steam ST generated in the second boiler 8) can be supplied to the steam turbine 20 at the appropriate pressure. The supply-side gland steam pressure control valve 43 is installed in the main supply passage 41. The supply-side gland steam pressure control valve 43 automatically opens and closes so that the pressure in the main supply passage 41 is set to the pressure specified, and controls the supply of auxiliary steam.

[0030] (Gland steam exhaust piping) The gland steam discharge pipe 45 connects each gland 23 to the second condenser 9, which will be described later. The gland steam discharge pipe 45 is capable of supplying steam ST discharged from each gland 23 to the second condenser 9. The gland steam discharge pipe 45 has a main discharge channel 46 and a branch discharge channel 47. The downstream end of the main discharge channel 46 is connected to the second condenser 9. The branch discharge channel 47 extends from the upstream end of the main discharge channel 46 so as to branch to each gland 23.

[0031] (Second condenser) The second condenser 9 recovers the steam ST discharged from the gland 23 through the gland steam discharge pipe 45. The second condenser 9 is installed separately from the condenser 30. The second condenser 9 cools and condenses the steam ST discharged from the gland 23 back into water.

[0032] (Relief piping) The relief pipe 48 branches off from the gland steam supply pipe 40. The relief pipe 48 is connected to the condenser 30.

[0033] (Relief side gland steam pressure regulating valve) The relief-side gland steam pressure control valve 49 is installed to open and close the gland steam supply pipe 40 and controls the pressure in the gland steam supply pipe 40 so that gland steam (steam ST generated in the second boiler 8) can be supplied to the steam turbine 20 at an appropriate pressure. The relief-side gland steam pressure control valve 49 is installed to open and close the relief pipe 48. The relief-side gland steam pressure control valve 49 is installed to control the pressure to be slightly higher than the set pressure of the main supply passage 41. The relief-side gland steam pressure control valve 49 is normally fully open, but when the pressure rises it opens automatically and controls the pressure by releasing steam ST to the condenser 30. Only one set of relief pipe 48 and relief-side gland steam pressure control valve 49 is installed.

[0034] (Drain piping) The drain pipe 50 branches off from the gland steam supply pipe 40 (main supply channel 41 in the illustrated example) and is connected to the condenser 30. The drain pipe 50 is a pipe for draining the condensate from the gland steam supply pipe 40. Multiple drain pipes 50 are provided (two in the illustrated example). The arrangement and number of drain pipes 50 can be changed as needed.

[0035] The drain pipe 50 has a drain pipe body 51 and an inner pipe 52. The drain pipe body 51 connects the gland steam supply pipe 40 to the shell 31 of the condenser 30. The inner pipe 52 extends into the shell 31 from the downstream end of the drain pipe body 51. The inner pipe 52 has multiple holes (not shown). The relief pipe 48 and the inner pipe 52, which connect the relief-side gland steam pressure control valve 49 to the condenser 30, release steam ST to the condenser 30 to depressurize it if the pressure in the gland steam supply pipe 40 rises too high. The inner pipe 52 extends horizontally. The inner pipe 52 is also located below the spray section 7. Furthermore, the inner pipe 52 is located below the heat transfer tube group 32.

[0036] (Drain valve) In the illustrated example, the drain valves 53 are provided on the drain pipe body 51 of each drain pipe 50. The drain valves 53 are capable of opening and closing the drain pipes 50. When the steam turbine 20 is driven, all drain valves 53 are closed, and the required amount of steam ST (gland steam) is supplied to the gland 23. The arrangement and number of drain valves 53 can be changed as appropriate.

[0037] (Procedure for cleaning gland steam supply piping) Next, the procedure for cleaning the gland steam supply piping will be explained with reference to the flow chart in Figure 2. As shown in Figure 2, the gland steam supply piping cleaning method according to the embodiment of this disclosure comprises a preparation step S1, a fan start step S2, and a piping cleaning step S3. The series of steps are performed before the steam turbine 20 is driven. Therefore, the gland steam supply piping 40 is cleaned while the condenser 30 is not yet vacuumed by the vacuum device 6, or while vacuuming is not yet complete.

[0038] First, preparation step S1 is performed. In preparation step S1, as shown in Figure 3, a worker removes the cover 24b of the manhole 24 and opens the manhole 24. Then, the worker attaches the exhaust passage 11 to the opened manhole 24. In this embodiment, the exhaust passage 11 is attached to the manhole 24 via a fan 10. Specifically, the worker first attaches the fan 10, which can blow the gas from the internal space A2 of the condenser 30 into the exhaust passage 11, to the opening 24a of the manhole 24 using wires, bolts, etc. After that, the worker attaches the upstream end of the exhaust passage 11 to the fan 10 using wires, bolts, etc. Alternatively, the upstream end of the exhaust passage 11 may be attached to the opening 24a of the manhole 24 first, and the fan 10 may be attached to the downstream end of the exhaust passage 11. In this embodiment, a flexible and expandable bellows pipe is used as the exhaust passage 11. This bellows pipe is a type of duct hose. The corrugated pipe comprises, for example, a flexible, corrugated hose made of vinyl and an annular frame to maintain the hose in a cylindrical shape. Multiple frames are provided at intervals in the direction of the hose's extension. The exhaust passage 11 is installed to avoid obstacles around the steam turbine 20 and condenser 30. The worker leads the downstream end of the exhaust passage 11 to a convenient exhaust location, such as outside the building housing the steam turbine 20 and condenser 30.

[0039] After the preparation process S1, the fan startup process S2 is performed. In the fan startup process S2, an operator starts the fan 10. As a result, the fan 10 blows air from the internal space A2 of the condenser 30 and the internal space A1 of the turbine casing 22, and exhausts it into the atmosphere through the exhaust passage 11.

[0040] After the fan startup process S2, the pipe cleaning process S3 is performed. In the pipe cleaning process S3, the second boiler 8 is started and steam ST is gradually filled into the gland steam supply pipe 40 from upstream. As a result, high-pressure steam ST generated by the second boiler 8 flows through the gland steam supply pipe 40. At this time, by opening the drain valve 53 as appropriate, most of the steam ST generated by the second boiler 8 is sent to the drain pipe 50.

[0041] Then, steam ST, which has been used to clean the gland steam supply pipe 40, is supplied to the condenser 30. At this time, the exhaust passage 11 is connected to the manhole 24 with the manhole 24 open in preparation step S1. Therefore, when high-pressure steam ST is supplied to the condenser 30, the gas in the internal space A2 of the condenser 30 is discharged to the outside of the building via the manhole 24 and the exhaust passage 11.

[0042] The supply-side gland steam pressure control valve 43 and the drain valve 53 may be selectively opened.

[0043] The cleaning of the gland steam supply piping 40 is completed by following the above procedure. After cleaning the gland steam supply piping 40, all drain valves 53 are closed to ensure that the required amount of steam ST (gland steam) is supplied to the gland 23. Then, steam ST is supplied to the steam turbine 20 through the main steam line 4 to drive the steam turbine 20.

[0044] In the above embodiment, the case in which the pipe cleaning step S3 is performed after the fan startup step S2 in the method for cleaning the gland steam supply pipe was described, but it is not limited to this. The fan startup step S2 may be performed after the pipe cleaning step S3.

[0045] Alternatively, a gland cleaning process may be performed after the piping cleaning process S3. In the gland cleaning process, the supply-side gland steam pressure control valve 43 is opened, and all drain valves 53 are closed, and steam ST is supplied to the gland 23 to clean the gland 23.

[0046] (Effects and Benefits) The cleaning method for the gland steam supply piping with the above configuration exhibits the following effects.

[0047] The method for cleaning the gland steam supply piping of this embodiment includes a preparation step S1 and a piping cleaning step S3. In the preparation step S1, an operator opens the manhole 24 and installs an exhaust passage 11 in the manhole 24. Following the preparation step S1, the piping cleaning step S3 is performed. In the piping cleaning step S3, an operator flows steam ST through the gland steam supply piping 40 and guides the steam ST flowing through the gland steam supply piping 40 to the condenser 30 through the drain pipe 50.

[0048] As a result, in the pipe cleaning process S3, high-pressure steam ST is flowed through the gland steam supply pipe 40 to clean the inside of the gland steam supply pipe 40, and the steam ST used for cleaning can be recovered in the condenser 30. This suppresses the discharge of contaminated steam ST to the outside. Therefore, it suppresses the creation of a negative impression of the steam turbine plant 1 among surrounding residents. In addition, preparation process S1 is performed before the pipe cleaning process S3, and the manhole 24 of the steam turbine 20 is opened. Therefore, even if high-pressure steam ST is recovered into the condenser 30 in the pipe cleaning process S3, the gas inside the condenser 30 is discharged to the outside through the manhole 24. This suppresses the rise in internal pressure of the condenser 30. Furthermore, the manhole 24 is a manhole 24 that was previously installed for internal inspection during maintenance of the steam turbine 20. Therefore, there is no need to install a separate manhole to discharge the gas from the condenser 30.

[0049] Furthermore, in this embodiment, the steam turbine 20 is a downflow exhaust type that exhausts steam ST downwards, and a condenser 30 is attached to the lower part of the steam turbine 20. In such a case, if a manhole were to be provided in the condenser 30 and the pressure of the condenser 30 were to be reduced by opening this manhole, it would be difficult to open the manhole of the condenser 30 and install an exhaust passage because the condenser 30 is often installed underground or other devices and equipment are arranged around it. In contrast, in this embodiment, the pressure of the condenser 30 is reduced by utilizing the manhole 24 of the steam turbine 20. Therefore, the preparation process can be carried out more easily compared to the case where the manhole of the condenser 30 is used.

[0050] Furthermore, in this embodiment, the manhole 24 is located above the spray section 7 that prevents the steam ST from rising. As a result, when the manhole 24 is opened, water does not leak out of the manhole 24, making the preparation process even easier to carry out.

[0051] Furthermore, in this embodiment, an exhaust passage 11 is installed in the opened manhole 24 during preparation step S1. This exhaust passage 11 allows for adjustment of the exhaust position of the gas inside the condenser 30.

[0052] Thus, in this embodiment, the rise in internal pressure of the condenser 30 can be suppressed by a simple method such as opening the manhole 24 provided in advance in the steam turbine 20 for internal inspection during maintenance and installing the exhaust passage 11.

[0053] In preparation step S1, an operator installs a fan 10 capable of blowing gas from the internal space A2 of the condenser 30 into the exhaust passage 11. The method for cleaning the gland steam supply piping further includes a fan activation step S2 after preparation step S1, in which the fan 10 is activated.

[0054] This allows the fan 10 to increase the flow rate of gas exhausted from the internal space A2 of the condenser 30. Therefore, the rise in internal pressure of the condenser 30 is further suppressed during the piping cleaning process S3.

[0055] In this embodiment, the fan 10 is directly attached to the open manhole 24.

[0056] As a result, the gas in the condenser 30 is discharged more quickly compared to the case where the fan 10 is attached to the downstream end of the exhaust passage 11.

[0057] In this embodiment, the exhaust passage 11 is a bellows pipe.

[0058] In this case, the exhaust passage 11 can be extended, retracted, or curved. This makes it easy to adjust the position of the exhaust outlet.

[0059] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure.

[0060] In the above embodiment, the steam turbine 20 is a downflow exhaust type that exhausts steam ST downwards, and the condenser 30 is located below the steam turbine 20, but it is not limited to this. The condenser 30 only needs to be in communication with the inside of the steam turbine 20. For example, if the steam turbine 20 is a side exhaust type that exhausts steam ST to the side, the condenser 30 may be located to the side of the steam turbine 20. Alternatively, the condenser 30 may be in communication with the inside of the steam turbine 20 through piping.

[0061] In the above embodiment, the case in which the fan 10 is installed in preparation step S1 has been described, but it is not limited to this. The fan 10 does not necessarily have to be installed in preparation step S1. If the fan 10 is not installed, it is preferable to open multiple manholes 24 and install exhaust passages 11 in each manhole 24 in order to increase the exhaust flow rate. Also, the case in which a corrugated pipe is used as the exhaust passage 11 has been described, but it is not limited to this. Other tubular members may be used as the exhaust passage 11. For example, ordinary piping may be used as the exhaust passage 11. Also, for example, a hose that is not corrugated may be used as the exhaust passage 11.

[0062] <Note> The cleaning method for the gland steam supply piping described in each embodiment can be understood, for example, as follows:

[0063] (1) A method for cleaning a gland steam supply pipe according to the first embodiment is a method for cleaning a gland 23 steam supply pipe in a steam turbine plant 1 comprising: a steam turbine 20 having an openable and closable manhole 24; a condenser 30 capable of returning steam exhausted from the steam turbine 20 back into water; a gland steam supply pipe 40 capable of supplying steam ST to the gland 23 of the steam turbine 20; and a drain pipe 50 branching from the gland steam supply pipe 40 and connected to the condenser 30, the method comprising: a preparation step S1 of opening the manhole 24 and installing an exhaust passage 11 in the manhole 24; and a pipe cleaning step S3 after the preparation step S1 of circulating steam ST through the gland 23 steam supply pipe and guiding the steam ST flowing through the gland 23 steam supply pipe to the condenser 30 through the drain pipe 50.

[0064] As a result, in the pipe cleaning process S3, high-pressure steam ST is flowed through the gland steam supply pipe 40 to clean the inside of the gland steam supply pipe 40, and the steam ST used for cleaning can be recovered in the condenser 30. This suppresses the discharge of contaminated steam ST to the outside. In addition, preparation process S1 is performed before the pipe cleaning process S3, and the manhole 24 of the steam turbine 20 is opened. Therefore, even if high-pressure steam ST is recovered into the condenser 30 in the pipe cleaning process S3, the gas inside the condenser 30 is discharged to the outside through the manhole 24. This suppresses the rise in internal pressure of the condenser 30.

[0065] (2) A second embodiment of the method for cleaning a steam supply pipe is the method for cleaning a gland steam supply pipe according to (1), wherein the preparation step S1 further includes installing a fan 10 capable of blowing the gas in the condenser 30 into the exhaust passage 11, and after the preparation step S1, starting the fan 10.

[0066] This allows the fan 10 to increase the flow rate of gas exhausted from the internal space A2 of the condenser 30. Therefore, the rise in internal pressure of the condenser 30 is further suppressed during the piping cleaning process S3.

[0067] (3) The third embodiment of the method for cleaning the gland steam supply piping is the method for cleaning the gland steam supply piping according to (1) or (2), wherein the exhaust passage 11 may be a corrugated pipe.

[0068] In this case, the exhaust passage 11 can be extended, retracted, or curved. This makes it easy to adjust the position of the exhaust outlet. [Explanation of symbols]

[0069] 1. Steam Turbine Plant 2 Boilers 3. Water supply pump 4 Main steam line 5. Water supply line 6 Vacuum equipment 6a Vacuum apparatus main unit 6b Vacuum Line 7. Spray section 8. Second boiler 9. Second condenser 10 Fans 11 Exhaust passage 20 Steam Turbine 21 Rotors 22 Turbine casing 23 Grand 24 Manholes 24a opening 24b Lid 30 Condenser 31 Torso 32 Heat transfer tube group 32a Heat transfer tube 33 Inlet water chamber 34 Outlet water chamber 35 Hotwell 40 Gland steam supply piping 41 Main supply channel 42 Branch supply channel 43 Supply side gland steam pressure regulating valve 45. Gland steam exhaust piping 46 Main discharge channel 47 Branch discharge channel 48 Relief piping 49 Relief side gland steam pressure regulating valve 50 Drain piping 51 Drain piping body 52 Inner pipe 53 Drain valve A1 Interior space A2 interior space S1 Preparation process S2 Fan Startup Process S3 Pipe Cleaning Process

Claims

1. A steam turbine with an openable and closable manhole, A condenser capable of converting the steam exhausted from the steam turbine back into water, A gland steam supply pipe capable of supplying steam to the gland of the steam turbine, A drain pipe that branches off from the gland steam supply pipe and is connected to the condenser, A method for cleaning gland steam supply piping in a steam turbine plant equipped with, The steps include opening the manhole and preparing to install an exhaust passage in the manhole, After the preparation step, a pipe cleaning step is performed in which steam is circulated through the gland steam supply pipe and the steam flowing through the gland steam supply pipe is guided to the condenser through the drain pipe, A method for cleaning gland steam supply piping, including the pipes.

2. In the preparation step, a fan capable of blowing the gas in the condenser into the exhaust passage is installed. The process further includes a fan startup step, which starts the fan after the preparation step, A method for cleaning a gland steam supply pipe according to claim 1.

3. The method for cleaning a gland steam supply pipe according to claim 1 or 2, wherein the exhaust passage is a bellows pipe.

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