How to check for leaks

Abstract

To enable easy and low-cost confirmation of the cause of leaking-in of water leakage when a water leakage is detected in a turbine.SOLUTION: The present invention includes a main steam pipe system A and a reheat steam pipe system B having a first system LB and a second system HB. In the main steam pipe system A: first valves 32, 37 are arranged in which drain water pipe systems D1, D2 are provided through which water that has passed through main steam stop valves 17, 18 passes; a second valve 43 is arranged in which a drain water pipe system D3 is provided on an upstream side of a low-temperature reheat check valve 20 of the first system LB of the reheat steam pipe system B; and a third valve 50 is arranged in which a drain water pipe system D4 through which water that has passed through reheat stop valves 22, 24 passes in the second system HB of the reheat steam pipe system B. Bonnets of the first valves 32, 37, the second valve 43, and the third valve 50 are removed to confirm presence / absence of water inside the valves, and based on the confirmation of the valves 32, 37, 43, 50 where water was present, it is determined whether the water leakage occurred in the main steam stop valves 17, 18, the low-temperature reheat check valve 20, or the reheat steam stop valve 22, 24.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for easily identifying a location that may be the cause of a water leak that is found in a turbine when a water filling and hydraulic test is performed on a boiler. [Background technology]

[0002] In thermal power plants, a water-filled hydraulic test may be performed to ensure the soundness of the boiler, as shown in, for example, Patent Document 1. In this water-filled hydraulic test, water is poured into the boiler while the main steam stop valve (herein referred to as MSV), reheat steam stop valve (herein referred to as RSV), and low-temperature reheat steam check valve (herein referred to as LTR) are closed so that water does not enter the turbine, and the main steam pipe system up to the MSV and the reheat steam pipe system up to the RSV and LTR are filled with water.

[0003] When performing a water pressure test on such a boiler, although it is a rare case, a leak may be found in the turbine even with the MSV, RSV and LTR closed as described above. In this case, it is necessary to identify the location that caused the leak and repair the location that caused the leak.

[0004] In the case of leakage from the main steam pipe system, it is expected that the cause of the leakage is a sheet leak in the MSV, and in the case of leakage from the reheat steam pipe system, it is expected that the cause of the leakage is a sheet leak in the RSV or LTR. However, simply discovering a leak in the turbine is not enough to determine which steam pipe system is the cause of the leakage.

[0005] Therefore, in order to confirm the location of the leak, it is possible that water filling and water pressure tests will be conducted on the boiler multiple times, assuming that the cause of the leak is a sheet leak in the MSV, a sheet leak in the RSV, and a sheet leak in the LTR. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-154249 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, if the number of operations of injecting water into the boiler increases, the cost of checking for water leaks increases, resulting in longer downtime for the boiler and therefore for the thermal power plant.

[0008] Furthermore, if it is necessary to cut certain pipes, such as those in a drainage system, in order to locate the leak, the restoration work will take time and money, further increasing the inconvenience of the boiler and, ultimately, the thermal power plant being shut down for an extended period of time.

[0009] The present invention has been made to solve such problems, and its main object is to provide a method for confirming the location of a water leak, which can easily and inexpensively identify the location that caused the water to leak when a water leak is discovered in a turbine. [Means for solving the problem]

[0010] In order to achieve the above object, a method for checking a water leakage point of the invention according to claim 1 is a water leakage detection method for use in a thermal power plant comprising: a boiler having a superheater and a reheater; a turbine; a main steam pipe system connecting the superheater and the turbine by piping and sending steam from the superheater to the turbine; and a reheat steam pipe system connecting the reheater and the turbine by piping, the reheat steam pipe system having a first system for sending steam from the turbine to the reheater and a second system for sending steam from the reheater to the turbine, the main steam pipe system having a main steam stop valve, the first system of the reheat steam pipe system having a low-temperature reheat check valve, and the second system of the reheat steam pipe system having a reheat steam stop valve. The method for checking the location of the reheat steam pipe system includes providing a first drain pipe system in the main steam pipe system through which water that has passed through the main steam stop valve passes, arranging a first valve in the first drain pipe system, providing a second drain pipe system in the first system of the reheat steam pipe system upstream of the low-temperature reheat check valve, arranging a second valve in the second drain pipe system, providing a third drain pipe system in the second system of the reheat steam pipe system through which water that has passed through the reheat steam stop valve passes, arranging a third valve in the third drain pipe system, and removing parts of the first valve, the second valve, and the third valve to make the insides visible and to check for the presence or absence of water in the valves. The first system of the reheat steam pipe system is, for example, called a low-temperature reheat steam pipe system, and the second system of the reheat steam pipe system is, for example, called a high-temperature reheat steam pipe system. In the case where there are two main steam stop valves, for example, there are two first valves arranged in the first drain pipe system. In the case where there are two reheat steam stop valves, for example, a common valve is used for the third drain pipe system and the third valve arranged in the third drain pipe system. The same applies to claim 3 corresponding to the second example described below.

[0011] As a result, if water is found in the first valve when a part of the first valve is removed and the inside is examined, it is possible to confirm that the cause of the water is a seat leak of the main steam stop valve, if water is found in the second valve when a part of the second valve is removed and the inside is examined, it is possible to confirm that the cause of the water leak is a seat leak of the low-temperature reheat check valve, and if water is found in the third valve when a part of the third valve is removed and the inside is examined, it is possible to confirm that the cause of the water leak is a seat leak of the reheat steam stop valve. Moreover, by making the first valve, the second valve, and the third valve valves have removable bonnets, it is possible to confirm the presence or absence of water by removing the bonnets of the valves. Accordingly, it is possible to relatively easily and quickly install the bonnets on the first valve, the second valve, and the third valve in a manner that returns them to their original state.

[0012] In order to achieve the above object, a method of checking a water leakage point according to the invention of claim 3 is a method of checking a water leakage point used in a thermal power plant including a boiler having a superheater and a reheater, a turbine, a main steam pipe system connecting the superheater and the turbine by piping and sending steam from the superheater to the turbine, and a reheat steam pipe system connecting the reheater and the turbine by piping, the reheat steam pipe system having a first system for sending steam from the turbine to the reheater and a second system for sending steam from the reheater to the turbine, the main steam pipe system having a main steam stop valve, the first system of the reheat steam pipe system having a low-temperature reheat check valve, and the second system of the reheat steam pipe system having a reheat steam stop valve, The system is characterized in that a first drain drain pipe system is provided through which water that has passed through the main steam stop valve passes, a first valve is disposed in the first drain drain pipe system, a second drain drain pipe system is provided upstream of the low-temperature reheat check valve in the first system of the reheat steam pipe system, a second valve is disposed in the second drain drain pipe system, a third drain drain pipe system is provided in the second system of the reheat steam pipe system through which water that has passed through the reheat steam stop valve passes, and a third valve is disposed in the third drain drain pipe system, and piping connected to the first valve, the second valve, and the third valve is made detachable from the first valve, the second valve, and the third valve, and water leakage in the piping removed from the first valve, the second valve, and the third valve is checked.

[0013] As a result, when the pipe connected to the first valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the water leakage is a seat leak of the main steam stop valve, when the pipe connected to the second valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the water leakage is a seat leak of the low-temperature reheat check valve, and when the pipe connected to the third valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the water leakage is a seat leak of the reheat steam stop valve. Moreover, the pipes whose ends are connected to the first valve, the second valve, and the third valve are detachable from the first valve, the second valve, and the third valve, so that the presence or absence of water leakage can be confirmed by removing the pipe. Accordingly, it is possible to relatively easily and quickly attach the pipes to the first valve, the second valve, and the third valve in a manner that returns them to their original state. Effect of the Invention

[0014] As described above, according to the method for checking the location of a leak according to the invention of claim 1, if water is found in the first valve when a part of the first valve is removed and the inside is examined, it is possible to confirm that the cause of the leak is a sheet leak of the main steam stop valve, if water is found in the second valve when a part of the second valve is removed and the inside is examined, it is possible to confirm that the cause of the leak is a sheet leak of the low-temperature reheat check valve, and if water is found in the third valve when a part of the third valve is removed and the inside is examined, it is possible to confirm that the cause of the leak is a sheet leak of the reheat steam stop valve. As a result, when a leak is found in a turbine, it is possible to easily identify whether it is a sheet leak of the main steam stop valve, a sheet leak of the low-temperature reheat check valve, or a sheet leak of the reheat steam stop valve without having to perform water filling and pressure tests again and multiple times, and the cost of checking the location of the leak can be kept low.

[0015] In particular, according to the method for checking the location of a water leak according to the invention of claim 2, the first valve, the second valve, and the third valve are valves with removable bonnets, so that the presence or absence of a water leak can be checked by removing the bonnets, and accordingly, the bonnets can be relatively easily and quickly reattached to the first valve, the second valve, and the third valve in a manner that returns them to their original state. This shortens the time required for restoration work after checking the location of a water leak, and shortens the downtime of the boiler and, ultimately, the thermal power plant.

[0016] According to the method for checking the location of a leak according to the invention of claim 3, when the pipe connected to the first valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the leak is a sheet leak of the main steam stop valve, when the pipe connected to the second valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the leak is a sheet leak of the low-temperature reheat check valve, and when the pipe connected to the third valve is disconnected and water is found in the pipe when viewed from the open end of the disconnected pipe, it is possible to confirm that the cause of the leak is a sheet leak of the reheat steam stop valve. As a result, when a leak is found in a turbine, it is possible to easily identify whether it is a sheet leak of the main steam stop valve, a sheet leak of the low-temperature reheat check valve, or a sheet leak of the reheat steam stop valve without having to perform water filling and hydraulic tests again and multiple times, and it is possible to keep the cost of checking the location of the leak low. Moreover, the piping connected to the first valve, the second valve, and the third valve can be detached from the first valve, the second valve, and the third valve, so that the presence or absence of water leakage can be checked by removing the piping, and accordingly, the piping can be relatively easily and quickly restored to its original state on the first valve, the second valve, and the third valve. This shortens the time required for restoration work after the location of the water leakage is confirmed, and shortens the downtime of the boiler and, ultimately, the thermal power plant. [Brief description of the drawings]

[0017] [Figure 1]1 is a schematic diagram showing a boiler, a turbine, a main steam pipe system, a reheat steam pipe system, and the like of a thermal power plant to which the present invention is applied. [Diagram 2] FIG. 1 is an explanatory diagram showing an example of a valve arranged in a drain pipe system as a first example of the present invention, and also showing a method for removing the bonnet of the valve to check for the presence or absence of water leakage inside the valve. [Diagram 3] 5 is a flowchart showing an example of a flow for checking a water leakage location in the first embodiment of the present invention. [Figure 4] As a second example of the present invention, this is an explanatory diagram showing an example of a state in which a pipe is removably attached to a valve arranged in a drain discharge pipe system, and also showing a method of removing the pipe from the valve to check for the presence or absence of water in the pipe. [Diagram 5] 10 is a flowchart showing an example of a flow for checking a water leakage location in a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] An example of a thermal power plant 1 to which the present invention can be applied is shown in Fig. 1. Of the equipment in the thermal power plant 1, a boiler 2 and a turbine 6 are shown in Fig. 1, but equipment that is not necessarily closely related to the present invention, such as a feedwater pump, a condenser, and a generator, is omitted.

[0020] The boiler 2 of the thermal power plant 1 has at least a superheater (abbreviated as SH) 3 and a reheater (abbreviated as RH) 4. The superheater 3 is for converting water sent from a feedwater pump into saturated steam in an evaporator tube (not shown) of the boiler 2, and then further superheating the saturated steam to produce superheated steam. The reheater 4 is for reheating the steam that has rotated a high-pressure turbine 7 (described below) of the turbine 6, and for supplying the steam for rotating the intermediate-pressure turbine 9 (described below) of the turbine 6 to the intermediate-pressure turbine 9.

[0021] The turbine 6 of the thermal power plant 1 has at least a high-pressure turbine 7 and intermediate-pressure turbines 8, 9, which are connected side by side on the same axis by a shaft 10. In this embodiment, the intermediate-pressure turbine 8 is disposed on one axial side of the high-pressure turbine 7, and the intermediate-pressure turbine 9 is disposed on the other axial side of the high-pressure turbine 7. A generator is connected to the end of the shaft 10, and the generator is rotated by the transmission of rotation of the high-pressure turbine 7 and the intermediate-pressure turbines 8, 9 to generate electricity.

[0022] The thermal power generation facility 1 has a main steam pipe system A that connects the superheater 3 and the high-pressure turbine 7 of the turbine 6 with piping 12 and sends superheated steam from the superheater 3 to the high-pressure turbine 7, and a reheat steam pipe system B that connects the reheater 4 and the turbine 6 with piping 13, 14 and is composed of a system (low-temperature reheat steam pipe system) LB that sends low-temperature steam from the high-pressure turbine 7 to the reheater 4 via piping 13, and a system (high-temperature reheat steam pipe system) HB that sends reheated and high-temperature steam from the reheater 4 to the intermediate-pressure turbine 9 via piping 14.

[0023] In this embodiment, the main steam pipe system A branches into a main steam pipe system A1 and a main steam pipe system A2 midway, and the pipes 12 that ultimately constitute the main steam pipe system A1 and the main steam pipe system A2 are connected to the high-pressure turbine 7 to supply superheated steam. In this embodiment, the high-temperature reheat steam pipe system HB branches into two systems HB1 and HB2 midway and is then integrated again into one system HB3, and the pipes 14 that ultimately constitute the system HB3 of the high-temperature reheat steam pipe system HB are connected to the intermediate-pressure turbine 9 to supply steam reheated in the reheater 4. The steam that rotates the intermediate-pressure turbine 9 is sent to a condenser, for example, to return to water, and is then sent to the boiler 2 by a feedwater pump and re-saturated in the evaporation tubes of the boiler 2.

[0024] A main steam stop valve (hereinafter, right MSV) 16 that enables or stops the supply of superheated steam to the high-pressure turbine 7 is arranged on the path of piping 12 of the main steam pipe system A1, and a steam control valve (hereinafter, right GV) 17 is arranged on the turbine 6 side (downstream of steam) of the right MSV 16. A main steam stop valve (hereinafter, left MSV) 18 that enables or stops the supply of superheated steam to the high-pressure turbine 7 is arranged on the path of piping 12 of the main steam pipe system A2, and a steam control valve (hereinafter, left GV) 19 is arranged on the turbine 6 side (downstream of steam) of the left MSV 18.

[0025] A low-temperature reheat steam check valve (hereinafter referred to as LTR) 20 is arranged on the path of the piping 13 of the low-temperature reheat steam pipe system LB to prevent low-temperature reheat steam from flowing back to the high-pressure turbine 7. A reheat steam stop valve (hereinafter referred to as right RSV) 22 that enables or stops the supply of reheated steam to the intermediate-pressure turbine 9 is arranged on the path of system HB1 of the high-temperature reheat steam pipe system HB, and an intercept valve (hereinafter referred to as right ICV) 23 is arranged on the turbine 6 side (downstream of steam) of the right RSV 22. A reheat steam stop valve (hereinafter referred to as left RSV) 24 that enables or stops the supply of reheated steam to the intermediate-pressure turbine 9 is arranged on the path of system HB2 of the high-temperature reheat steam pipe system HB, and an intercept valve (hereinafter referred to as left ICV) 25 is arranged on the turbine 6 side (downstream of steam) of the left RSV 24.

[0026] A drainage pipe system D1 is disposed at a location downstream of the right MSV 16 of the pipe 12 of the main steam pipe system A1, further downstream of the right GV 17, and upstream of the high-pressure turbine 7. The drainage pipe system D1 includes a pipe 30, an electric valve 31 disposed on the path of the pipe 30, a valve 32 disposed upstream of the electric valve 31 in terms of drainage, and a valve 33 disposed downstream of the electric valve 31 in terms of drainage. A drainage pipe system D2 is disposed at a location downstream of the left MSV 18 of the pipe 12 of the main steam pipe system A2, further downstream of the left GV 19, and upstream of the high-pressure turbine 7 in terms of steam. The drainage pipe system D2 includes a pipe 35, an electric valve 36 disposed on the path of the pipe 35, a valve 37 disposed upstream of the electric valve 36 in terms of drainage, and a valve 38 disposed downstream of the electric valve 36 in terms of drainage. The valve 32 of the drain pipe system D1 is hereinafter referred to as the first valve 32. The valve 37 of the drain pipe system D2 is hereinafter also referred to as the first valve 37.

[0027] A drainage pipe system D3 is arranged at a position upstream of the LTR 20 in the low-temperature reheat steam pipe system LB. The drainage pipe system D3 has a pipe 40, an electric valve 41 arranged on the path of the pipe 40, a valve 42 arranged upstream of the drainage from the electric valve 41, and a valve 43 arranged downstream of the drainage from the electric valve 41. In the low-temperature reheat steam pipe system HB, a drainage pipe system D4 is arranged in common to the right RSV 22 and the left RSV 24. The drainage pipe system D4 has a pipe 45 extending from the right RSV 22, a pipe 46 extending from the left RSV 24, a pipe 47 in which the pipes 45 and 46 are joined together, an electric valve 48 arranged on the path of the pipe 47, a valve 49 arranged upstream of the drainage from the electric valve 48, and a valve 50 arranged downstream of the drainage from the electric valve 48. The valve 43 of the drain pipe system D3 is hereinafter referred to as the second valve 43. The valve 50 of the drain pipe system D4 is hereinafter referred to as the third valve 50. In this embodiment, the drain discharge pipe system D3 has a pipe 51 extending from the right ICV 23 and connected to the pipe 45, and a valve 52 arranged on the path of this pipe 51, as well as a pipe 53 extending from the left ICV 25 and connected to the pipe 46, and a valve 54 arranged on the path of this pipe 53.

[0028] In the first example, the first valves 32, 37, the second valve 43, and the third valve 50 are each configured to have a handle 61, a valve stem 62 extending from the handle 61, a valve body 63 provided at the tip of the valve stem 62, a body 64 accommodating most of the valve stem 62 and the valve body 63, and a bonnet 65 closing the upper part of the body 64, as shown in FIG. 2(a). The first valves 32, 37, the second valve 43, and the third valve 50 can be disassembled by removing the bonnet 65 from the body 64 and removing the valve stem 62, etc., as shown in FIG. 2(b), so that the inside of the valve can be seen. It is needless to say that the first valves 32, 37, the second valve 43, and the third valve 50 are not limited to the configuration shown in FIG. 2, as long as they have a bonnet that can be removed from the body.

[0029] In a thermal power plant 1 having such a boiler 2, turbine 6, main steam pipe system A, and reheat steam pipe system B, a water filling and water pressure test is carried out on the boiler 2, and if a water leak is found, for example, between the end of the shaft 10 on the intermediate pressure turbine 8 side of the turbine 6 and the bearing 6a, the location that caused the water leak into the turbine 6 is identified and the identified location is repaired, for example, according to the flowchart of Figure 3.

[0030] That is, as shown in Fig. 3, when preparation work for the boiler water filling hydraulic pressure test is completed, starting from step 100, and after confirming in step 101 that the right MSV 16, left MSV 18, LTR 20, right RSV 22, and left RSV 24 are blocked, proceed to step 102, where water is injected into the boiler 2 and the boiler water filling hydraulic pressure test is started. Note that when injecting water into the boiler 2, after the range from the superheater 3 to the MSVs 16 and 18 in the main steam pipe system A is filled with water, the range from the reheater 4 to the LTR 20 in the reheat steam pipe system LB and the range from the reheater 4 to the RSVs 22 and 24 in the reheat steam pipe system HB are filled with water.

[0031] Then, in step 103, it is determined whether or not a water leak has occurred in the turbine 6 as a result of the water filling and hydraulic pressure test of the boiler. If no water leak has occurred in the turbine 6, the process proceeds to end step 104, where the water filling and hydraulic pressure test of the boiler is completed.

[0032] If a water leak occurs in the turbine 6, proceed to step 105, and disassemble the valves 32, 37, second valve 43, and third valve 50 by removing the bonnets 65 from the body 64 and removing the valve stems 62, etc., so as to change the state from that of Figure 2(a) to that of Figure 2(b), for example, and open the tops of the valves 32, 37, 43, and 50, and visually check whether there is water in the valves, as shown in Figure 2(b).

[0033] Basically, first, in step 106, it is determined whether water is confirmed in the first valves 32, 37 arranged in the drain pipe systems D1, D2 provided in the main steam pipe system A. If water is confirmed in the first valves 32, 37, even if the MSVs 16, 18 are closed, water will have flowed into the drain pipe systems D1, D2 provided downstream of the MSVs 16, 18 in the main steam pipe system A, so it is possible to determine that the seat leak of the MSVs 16, 18 is the cause of the water leakage from the turbine 6. However, in the present invention, the main steam pipe system A has a right MSV 16 and a left MSV 18. For this reason, in step 107, it is confirmed whether the valve in which water was confirmed is the first valve 32 (the first valve 32 corresponding to the right MSV 16) arranged in the drain pipe system D1 through which the water that passed through the right MSV 16 passes, or the first valve 37 (the first valve 37 corresponding to the left MSV 18) arranged in the drain pipe system D2 through which the water that passed through the left MSV 18 passes. If it is the first valve 32 corresponding to the right MSV 16, it is determined that the seat leak of the right MSV 16 is the cause of the water leakage, so the process proceeds to step 108, where the right MSV 16 is repaired. On the other hand, if it is the first valve 37 corresponding to the left MSV 18, it is determined that the seat leak of the left MSV 18 is the cause of the water leakage, so the process proceeds to step 109, where the left MSV 18 is repaired.

[0034] If water is not confirmed inside the first valves 32, 37, a determination is made in step 110 as to whether water is confirmed inside the second valve 43 arranged in the drain discharge pipe system D3 provided in the low-temperature reheat steam pipe system LB. If water is confirmed inside the second valve 43, even if the LTR 20 is closed, water will have flowed into the drain discharge pipe system D3 provided upstream of the LTR 20 in the low-temperature reheat steam pipe system LB, and it is therefore possible to determine that a seat leak in the LTR is the cause of the water leakage from the turbine 6. If water is confirmed inside the second valve 43 in this way, the process proceeds to step 111, and the LTR 20 is repaired.

[0035] If water is not confirmed in the second valve 43, it is determined in step 112 whether water is confirmed in the third valve 50 arranged in the drainage pipe system D4 provided in the high-temperature reheat steam pipe system HB. If water is confirmed in the third valve 50, even if the RSVs 22 and 24 are closed, water will have flowed through the RSVs 22 and 24 into the drainage pipe system D4, so it is possible to determine that the seat leak of the RSVs 22 and 24 is the cause of water leakage from the turbine 6. If water is confirmed in the third valve 50, the process proceeds to step 113, and the RSVs 22 and 24 are repaired. In the present invention, the high-temperature reheat steam pipe system HB has the right RSV 22 and the left RSV 24. Even in this case, if it is determined in step 112 that the RSVs 22 and 24 are the cause, for example, by filling only the right RSV 22 in a closed state with water and checking the presence or absence of water in the third valve 50, it is possible to determine that if water is present, the seat leak of the right RSV 22 is the cause of the water leakage in the turbine 6, and if water is not present, the seat leak of the left RSV 24 is the cause of the water leakage in the turbine 6. In other words, it is possible to identify whether the cause of the water leakage in the turbine 6 is the right RSV 22 or the left RSV 24. Accordingly, in step 113, only the right RSV 22 or only the left RSV 24 can be repaired. Note that, in step 112, if water cannot be confirmed in the third valve 50, it is possible to return to step 106 on the assumption that water may have been overlooked in any of the valves.

[0036] In addition, in the flowchart of Figure 3, if it is clear from the process of the boiler water filling and water pressure test that there is no water leakage from the turbine 6 at the stage when the main steam pipe system A is filled with water, it is also possible to make an adjustment in step 105 by not removing the bonnets of the first valves 32 and 37, but removing the bonnets of the second valve 43 and the third valve 50, and skipping steps 105 and 106 and proceeding to step 110.

[0037] According to the above, when a leak is found in the turbine 6, it is possible to determine whether the cause is a sheet leak in the MSVs 16 and 18, a sheet leak in the LTR 20, or a sheet leak in the RSVs 22 and 24, without having to perform multiple water filling and hydraulic tests again. Furthermore, in the case of a sheet leak in the MSVs 16 and 18, it is also possible to determine whether the sheet leak is in the right MSV 16 or the left MSV 18. In addition, in the case of a sheet leak in the RSVs 22 and 24, it is possible to determine whether the sheet leak is in the right RSV 22 or the left RSV 24 by a simple procedure such as filling only one of the RSVs 22 and 24 with water.

[0038] Figures 4 and 5 show a second example using valves 32, 37, 43, and 50 different from those in the first example shown in Figures 2 and 3 and described above. The second example will be described below with reference to Figures 4 and 5. Note that the boiler 2, turbine 6, main steam pipe system A, reheat steam pipe system B, and drainage pipe systems D1, D2, and D3 of the thermal power generation facility 1 shown in Figure 1 are basically common to the first and second examples, so the symbols of the devices, instruments, etc. shown in Figure 1 will be used as the symbols shown in Figures 4 and 5.

[0039] As shown in Fig. 4(a) and Fig. 4(b), the first valve 32, 37, the second valve 43, and the third valve 50 each include a handle 61, a valve rod 62 extending from the handle 61, a valve body 63 provided at the tip of the valve rod 62, and a body 64 accommodating most of the valve rod 62 and the valve body 63. The first valve 32, 37, the second valve 43, and the third valve 50 are detachably connected to the pipes 30, 35, 40, and 47. For example, in Fig. 4(a) and Fig. 4(b), the body 64 of the valve 32, 37, 43, and 50 is formed with connection ports 66, 66 for communicating with the pipes 30, 35, 40, and 47, and flanges 67, 67 extending laterally from the openings of the connection ports 66, 66 are formed. The pipes 30, 35, 40, 47 are formed with flanges 68 that abut against the flanges 67 of the valves 32, 37, 43, 50. The flanges 67 and 68 are connected with fasteners 69 such as bolts. As a result, as shown in Fig. 4(b), it is possible to remove the pipes 30, 35, 40, 47 from the valves 32, 37, 43, 50 and view the insides of the pipes 30, 35, 40, 47 from the open ends. It is to be noted that the first valves 32, 37, the second valve 43, and the third valve 50 are not limited to the configurations shown in Figs. 4(a) and 4(b) as long as they are detachably connected to the pipes 30, 35, 40, 47.

[0040] In a thermal power plant 1 having a boiler 2, a turbine 6, a main steam pipe system A, and a reheat steam pipe system B shown as a second example, if a water pressure test is performed on the boiler 2 and a water leak is found, for example, between the end of the shaft 10 on the intermediate pressure turbine 8 side of the turbine 6 and the bearing 6a, the location causing the water leak into the turbine 6 is identified and the identified location is repaired, for example, according to the flowchart in Figure 5. However, since steps 100 to 104 are the same as those in the flowchart in Figure 3, their explanation will be omitted and explanation will be given from step 105'.

[0041] If it is determined in step 104 that a water leak has occurred in turbine 6, proceed to step 105', and disconnect pipes 30, 35, 40, 47 from first valves 32, 37, second valve 43, and third valve 50, for example, to change from the state of Figure 4(a) to the state of Figure 4(b), and visually check whether there is water in pipes 30, 35, 40, 47, as shown in Figure 4(b).

[0042] Basically, first, in step 106', it is determined whether water is confirmed in the pipes 30, 35 detached from the first valves 32, 37 arranged in the drain pipe systems D1, D2 provided in the main steam pipe system A. If water is confirmed in the pipes 30, 35 detached from the first valves 32, 37, even if the MSVs 16, 18 are blocked, water will have flowed into the drain pipe systems D1, D2 provided downstream of the MSVs 16, 18 in the main steam pipe system A, so it is possible to determine that the seat leak of the MSVs 16, 18 is the cause of the water leakage from the turbine 6. However, in the present invention, the main steam pipe system A has the right MSV 16 and the left MSV 18. Therefore, in step 107', it is determined whether the pipe in which water is confirmed is the pipe 30 detached from the first valve 32 corresponding to the right MSV 16, or the pipe 35 detached from the first valve 37 corresponding to the left MSV 18. In the case of piping 30 removed from the first valve 32 corresponding to the right MSV 16, it is determined that a seat leak in the right MSV 16 is the cause of the water leakage, so the process proceeds to step 108 to repair the right MSV 16. In contrast, in the case of piping 35 removed from the first valve 37 corresponding to the left MSV 18, it is determined that a seat leak in the left MSV 18 is the cause of the water leakage, so the process proceeds to step 109 to repair the left MSV 18.

[0043] If water is not confirmed in the pipes 30, 35 detached from the first valves 32, 37, a determination is made in step 110' as to whether water is confirmed in the pipe 40 detached from the second valve 43 disposed in the drainage pipe system D3 provided in the low-temperature reheat steam pipe system LB. If water is confirmed in the pipe 40 detached from the second valve 43, even if the LTR 20 is blocked, water will have flowed into the drainage pipe system D3 provided upstream of the low-temperature reheat steam pipe system LB from the LTR 20, so it is possible to determine that a seat leak in the LTR 20 is the cause of the water leakage from the turbine 6. If water is confirmed in the pipe 40 detached from the second valve 43, the process proceeds to step 111, and the LTR 20 is repaired.

[0044] If water is not confirmed in the pipe 40 detached from the second valve 43, it is determined in step 112' whether water is confirmed in the pipe 47 detached from the third valve 50 arranged in the drain pipe system D4 provided in the high temperature reheat steam pipe system HB. If water is confirmed in the pipe 47 detached from the third valve 50, even if the RSVs 22 and 24 are blocked, water flows through the RSVs 22 and 24 into the drain pipe system D4, so it is possible to determine that the seat leak of the RSVs 22 and 24 is the cause of the water leakage from the turbine 6. If water is confirmed in the pipe 47 detached from the third valve 50, the process proceeds to step 113, and the RSVs 22 and 24 are repaired. In the present invention, the high temperature reheat steam pipe system HB has the right RSV 22 and the left RSV 24. Even in this case, if the result of the determination in step 112 indicates that the RSVs 22 and 24 are the cause, for example, water is filled only in the right RSV 22 in the closed state, and the presence or absence of water in the piping 47 detached from the third valve 50 is confirmed. If water is present, it can be determined that the seat leak of the right RSV 22 is the cause of the water leakage in the turbine 6, and if water is not present, it can be determined that the seat leak of the left RSV 24 is the cause of the water leakage in the turbine 6. In other words, it is possible to identify whether the cause of the water leakage in the turbine 6 is the right RSV 22 or the left RSV 24. Accordingly, in step 113, only the right RSV 22 or only the left RSV 24 can be repaired. Note that, if water cannot be confirmed in the piping 47 detached from the third valve 50 in step 112', it is possible to return to step 106' since there is a possibility that water has been overlooked in any of the pipings 30, 35, 40, and 47.

[0045] In addition, in the flowchart of Figure 5, if it is clear from the process of the boiler water filling and water pressure test that there is no water leakage from the turbine 6 at the stage when the main steam pipe system A is filled with water, it is also possible to make adjustments in step 105' by not disconnecting the pipes 30, 35 from the first valves 32, 37, disconnecting the pipe 40 from the second valve 43 and disconnecting the pipe 47 from the third valve 50, and skipping steps 105' to 106' and proceeding to step 110'.

[0046] According to the above, even in the second example, when a leak is found in the turbine 6, it is possible to determine whether the cause is a sheet leak in the MSVs 16 and 18, a sheet leak in the LTR 20, or a sheet leak in the RSVs 22 and 24, without having to perform multiple water filling and hydraulic tests again. Furthermore, in the case of a sheet leak in the MSVs 16 and 18, it is also possible to determine whether the sheet leak is in the right MSV 16 or the left MSV 18. In addition, in the case of a sheet leak in the RSVs 22 and 24, it is possible to determine whether the sheet leak is in the right RSV 22 or the left RSV 24 by a simple procedure such as filling only one of the RSVs 22 and 24 with water.

[0047] In the above description, the first valves are valves 32 and 37, the second valve is valve 43, and the third valve is valve 50. However, in the second example, the valves need only be detachable from the pipes 30, 35, 40, and 47, so this is not limited to this. For example, the first valves could be valves 33 and 38, the second valve 42, and the third valve 49. [Explanation of symbols]

[0048] 1. Thermal power generation facilities 2. Boiler 3 Superheater 4 Reheater 6. Turbine 12 Piping 13 Piping 14 Piping 16, 18 Main steam stop valve 20 Low temperature reheat steam check valve 22, 24 Reheat steam stop valve 30, 35 Piping 32, 37 First valve 40 Piping 43 Second Valve 45, 46, 47 Piping 50 Third Valve 65 Bonnet A Main steam pipe system B Reheat steam pipe system LB The first system of the reheat steam pipe system (low-temperature reheat steam pipe system) HB The second system of the reheat steam pipe system (high temperature reheat steam pipe system) D1 First drain pipe system D2 Second drain pipe system D3 Third drain pipe system

Claims

1. a boiler having a superheater and a reheater, a turbine, a main steam pipe system which connects the superheater and the turbine by piping and sends steam from the superheater to the turbine, and a reheat steam pipe system which connects the reheater and the turbine by piping and includes a first system which sends steam from the turbine to the reheater and a second system which sends steam from the reheater to the turbine, A method for checking a leak location used in a thermal power plant, the method comprising: a main steam pipe system having a main steam stop valve; a first system of the reheat steam pipe system having a low-temperature reheat check valve; and a second system of the reheat steam pipe system having a reheat steam stop valve, the method comprising: a first drain drain pipe system is provided in the main steam pipe system through which water that has passed through the main steam stop valve passes, a first valve is disposed in the first drain drain pipe system, a second drain drain pipe system is provided in a first system of the reheat steam pipe system on the upstream side of the low-temperature reheat check valve, a second valve is disposed in the second drain drain pipe system, a third drain drain pipe system is provided in a second system of the reheat steam pipe system through which water that has passed through the reheat steam stop valve passes, and a third valve is disposed in the third drain drain pipe system; A method for checking the location of a water leak, comprising removing a portion of the first valve, the second valve, and the third valve to enable viewing of the inside of the valve and checking whether or not water is present inside the valve.

2. 2. The method for checking the location of a leak as described in claim 1, wherein the first valve, the second valve, and the third valve are valves having a removable bonnet, and the bonnet is removed to allow the inside to be seen and to check for leaks.

3. a boiler having a superheater and a reheater, a turbine, a main steam pipe system which connects the superheater and the turbine by piping and sends steam from the superheater to the turbine, and a reheat steam pipe system which connects the reheater and the turbine by piping and includes a first system which sends steam from the turbine to the reheater and a second system which sends steam from the reheater to the turbine, A method for checking a leak location used in a thermal power plant, the method comprising: a main steam pipe system having a main steam stop valve; a first system of the reheat steam pipe system having a low-temperature reheat check valve; and a second system of the reheat steam pipe system having a reheat steam stop valve, the method comprising: a first drain drain pipe system is provided in the main steam pipe system through which water that has passed through the main steam stop valve passes, a first valve is disposed in the first drain drain pipe system, a second drain drain pipe system is provided in a first system of the reheat steam pipe system on the upstream side of the low-temperature reheat check valve, a second valve is disposed in the second drain drain pipe system, a third drain drain pipe system is provided in a second system of the reheat steam pipe system through which water that has passed through the reheat steam stop valve passes, and a third valve is disposed in the third drain drain pipe system; A method for checking the location of a leak, comprising making piping connected to the first valve, the second valve, and the third valve detachable from the first valve, the second valve, and the third valve, and checking for leaks in the piping removed from the first valve, the second valve, and the third valve.

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