Cleaning methods for steam systems in combined cycle equipment

Abstract

The steam system cleaning method includes intermittent operation and commissioning procedures. The intermittent operation procedure comprises: a no-load operation, in which the gas turbine is operated without load with the steam shut-off valve and bypass valve closed; a accumulator operation, in which steam is stored in an accumulator region that is part of both the main steam line and the bypass line during the no-load operation; and an intermittent purging operation, in which the bypass valve is opened after the accumulator operation to allow steam in the accumulator region to flow into the condenser. The commissioning procedure comprises: a commissioning operation, in which the gas turbine is tested with the steam shut-off valve closed and the bypass valve open; and a continuous purging operation, in which steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam line and the bypass line during the commissioning operation.

Description

Technical Field

[0001] This invention relates to a method for cleaning a steam system in a combined cycle equipment.

[0002] This application claims priority under Japanese Patent Application No. 2021-040565, filed in Japan on March 12, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] The combined cycle system includes: a gas turbine; a waste heat recovery boiler that uses the heat from the exhaust gas from the gas turbine to generate steam; a steam turbine driven by the steam from the waste heat recovery boiler; a condenser that converts the steam discharged from the steam turbine back into water; various pumps such as a condensate pump or a feedwater pump; a main steam line that guides the steam generated in the boiler to the steam turbine; a steam shut-off valve located on the main steam line; a water line that guides water from the condenser to the boiler via a condensate pump or a feedwater pump; a bypass line that branches off from the main steam line closer to the boiler than the steam shut-off valve and connects to the condenser; and a bypass valve located on the bypass line.

[0004] After the construction of a combined cycle system is completed, foreign objects such as welding slag or grinding dust may remain in the piping or various machines of the combined cycle system. Therefore, in the combined cycle system described above, in order to remove foreign objects after construction or maintenance, a blowing out (or flushing) is performed.

[0005] Methods for cleaning piping, etc., are disclosed, for example, in Patent Document 1 below.

[0006] The cleaning method disclosed in Patent Document 1 involves either continuous purging or intermittent purging. In the continuous purging method, the steam shut-off valve is closed and the temporary bypass valve is open, guiding steam from the waste heat recovery boiler to the condenser via the main steam line and bypass line. In the intermittent purging method, the steam shut-off valve and the temporary bypass valve are closed, storing steam from the waste heat recovery boiler in the main steam line and bypass line, then the temporary bypass valve is opened, guiding the stored steam to the condenser via the bypass line.

[0007] In the cleaning method disclosed in Patent Document 1, foreign matter remaining in the piping is not discharged into the atmosphere along with steam, thus suppressing pollution around the equipment or noise when steam is discharged into the atmosphere.

[0008] Previous technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 10-331607 Summary of the Invention

[0011] The technical problem to be solved by the invention

[0012] In combined cycle equipment, it is desirable to shorten the period from the completion of its construction to the introduction of steam into the steam turbine.

[0013] Therefore, the object of the present invention is to provide a cleaning method that can shorten the period from the completion of construction of a combined cycle equipment to the introduction of steam into the steam turbine.

[0014] means for solving technical problems

[0015] The cleaning method for combined circulation equipment, as one way to achieve the stated purpose, is applicable to the following combined circulation equipment.

[0016] The combined cycle unit includes: a gas turbine; a waste heat recovery boiler capable of generating steam using the heat from the exhaust gas from the gas turbine; a steam turbine driven by the steam from the waste heat recovery boiler; a condenser capable of converting the steam from the steam turbine back into water; a condensate pump capable of pressurizing the water from the condenser; a main steam line capable of guiding the steam generated in the waste heat recovery boiler to the steam turbine; a steam shut-off valve located on the main steam line capable of preventing steam from flowing into the steam turbine; a bypass line branching from the main steam line at a position closer to the waste heat recovery boiler than the steam shut-off valve and connecting to the condenser; a bypass valve located on the bypass line; a condensate line capable of guiding water from the condenser to the condensate pump; and a feedwater line capable of guiding water pressurized by the condensate pump to the waste heat recovery boiler.

[0017] In the cleaning method, an intermittent operation processing step is performed, followed by a trial operation processing step.

[0018] The intermittent operation process includes: a no-load operation process, in which fuel is supplied to the gas turbine and the gas turbine is operated without load while the steam shut-off valve and the bypass valve are closed; a pressure storage process, in which the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler during the no-load operation process, and the steam is stored in a pressure storage area in the main steam pipeline (a portion closer to the waste heat recovery boiler than the steam shut-off valve) and the bypass pipeline (a portion closer to the waste heat recovery boiler than the bypass valve); an intermittent purging process, after the pressure storage process, the fuel supply to the gas turbine is stopped and the bypass valve is opened, allowing the steam in the pressure storage area to flow into the condenser; and a foreign matter removal process after the intermittent purging process, after the intermittent purging process, foreign matter is removed from the condenser and the condensing pipeline.

[0019] The trial operation process includes: a trial operation process in which fuel is supplied to the gas turbine while the steam shut-off valve is closed and the bypass valve is open, and the gas turbine is put into trial operation; a continuous purging process in which the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler during the trial operation process, and the steam from the waste heat recovery boiler flows into the condenser through a part of the main steam pipeline and the bypass pipeline; and a foreign matter removal process after the trial operation process, in which foreign matter is removed from the condenser and the condenser pipeline after the fuel supply to the gas turbine is stopped during the trial operation process.

[0020] In this method, the steam system is cleaned without the need for temporary piping, thus reducing cleaning costs. Furthermore, since foreign matter blown away by steam flows into the condenser along with the steam, pollution around the equipment or noise from steam emissions into the atmosphere can be suppressed.

[0021] In this method, since the steam system is cleaned by performing an intermittent purging process to clean it, and then a continuous purging process to further clean it, the steam system can be cleaned efficiently.

[0022] Furthermore, in this method, steam generated during the commissioning of the gas turbine is used to perform a continuous purging process to clean the steam system during the commissioning. Therefore, compared to performing the commissioning of the gas turbine and the purging for cleaning the steam system separately, this method can shorten the period from the completion of the construction of the combined cycle plant to the introduction of steam into the steam turbine.

[0023] Invention Effects

[0024] In one aspect of the cleaning method of the present invention, the period from the completion of the construction of the combined cycle equipment to the introduction of steam into the steam turbine can be shortened. Attached Figure Description

[0025] Figure 1 This is a system diagram of a combined circulation device in one embodiment of the present invention.

[0026] Figure 2 This is a flowchart illustrating the execution sequence of multiple processes from the completion of the construction of the combined cycle equipment in one embodiment of the present invention to the overall trial operation of the combined cycle equipment. Detailed Implementation

[0027] The following describes an embodiment of the cleaning method for the steam system in the combined cycle equipment according to the present invention.

[0028] Combined cycle equipment

[0029] refer to Figure 1 The combined circulation device of this embodiment will be described.

[0030] The combined cycle equipment of this embodiment includes a gas turbine 10, a gas turbine generator 18, a waste heat recovery boiler 20, a steam turbine 25, a steam turbine generator 28, a condenser 30, a condenser line 31, a strainer 32, a condenser pump 33, a feed water line 34, a feed water pump 35, a feed water valve 34v, a main steam line 36, a steam shut-off valve 37, a steam regulating valve 38, a bypass line 39, and a bypass valve 39v.

[0031] The gas turbine 10 includes a compressor 13 for compressing air A, a combustor 14 for burning fuel F in the air compressed by the compressor 13 to generate combustion gas, and a turbine 15 driven by the combustion gas. The compressor 13 includes a compressor rotor 13r capable of rotating about an axis Arg, a compressor housing 13c covering the compressor rotor 13r, and an intake volume regulator (hereinafter referred to as an IGV (inlet guide vane)) 13i. The IGV 13i is provided on the intake side of the compressor housing 13c and is capable of regulating the flow rate of air A drawn into the compressor housing 13c. The turbine 15 includes a turbine rotor 15r capable of rotating about an axis Arg and a turbine housing 15c covering the turbine rotor 15r.

[0032] The gas turbine 10 also has an intermediate housing 12. The intermediate housing 12 is disposed between the compressor housing 13c and the turbine housing 15c in the direction of the extension of the axis Arg, connecting the compressor housing 13c and the turbine housing 15c.

[0033] A burner 14 is disposed within the intermediate housing 12. A fuel line 16 is connected to the burner 14. A fuel regulating valve 17 is provided on the fuel line 16 to regulate the flow rate of the fuel flowing through the fuel line 16.

[0034] The compressor rotor 13r and the turbine rotor 15r are located on the same axis Arg and connected to each other to form the gas turbine rotor 11. The rotor of the gas turbine generator 18 is connected to the gas turbine rotor 11. The gas turbine generator 18 can be electrically connected to the external power system PS via the transformer 19t and the circuit breaker 19b.

[0035] The waste heat recovery boiler 20 has a water inlet 20i and a steam outlet 20o. The waste heat recovery boiler 20 uses the heat of the exhaust gas from the gas turbine 10 to turn the water flowing in from the water inlet 20i into steam. The steam flows out from the steam outlet 20o.

[0036] The steam turbine 25 has a steam turbine rotor 25r capable of rotating around an axis Ars and a steam turbine casing 25c covering the steam turbine rotor 25r. A steam inlet 25i and an exhaust port 25o are formed on the steam turbine casing 25c. A rotor of a steam turbine generator 28 is connected to the steam turbine rotor 25r. The steam turbine generator 28 is electrically connected to an external power system PS via a transformer 29t and a circuit breaker 29b.

[0037] As described above, in this embodiment, a gas turbine generator 18 is connected to the gas turbine rotor 11, and a steam turbine generator 28 is connected to the steam turbine rotor 25r. That is, the combined cycle device in this embodiment is a dual-shaft combined cycle device. However, the gas turbine rotor 11 and the steam turbine rotor 25r can also be connected, and a generator can be connected to these rotors. That is, the combined cycle device can also be a single-shaft combined cycle device.

[0038] A condenser 30 is connected to the exhaust port 25o of the steam turbine casing 25c. The condenser 30 allows the steam from the steam turbine 25 to exchange heat with the cooling medium CM, cooling the steam into water.

[0039] One end of a condenser pipe 31 is connected to the bottom of the condenser 30. The other end of the condenser pipe 31 is connected to the suction port of the condenser pump 33. The condenser pump 33 can pressurize the water from the condenser 30. A filter 32 is provided on the condenser pipe 31 to remove foreign matter contained in the water flowing through the condenser pipe 31.

[0040] One end of a water supply line 34 is connected to the outlet of the condensate pump 33. The other end of the water supply line 34 is connected to the water inlet 20i of the waste heat recovery boiler 20. A water supply pump 35 and a water supply valve 34v are installed on the water supply line 34. The water supply pump 35 pressurizes the water from the condensate line 31 and delivers the water to the waste heat recovery boiler 20 via the water supply line 34.

[0041] One end of a main steam pipe 36 is connected to the steam outlet 20o of the waste heat recovery boiler 20. The other end of the main steam pipe 36 is connected to the steam inlet 25i of the steam turbine casing 25c. A steam shut-off valve 37 and a steam regulating valve 38 are installed on the main steam pipe 36. A bypass pipe 39 is connected to one end of the main steam pipe 36, closer to the waste heat recovery boiler 20 than the steam shut-off valve 37 and the steam regulating valve 38. The other end of the bypass pipe 39 is connected to the condenser 30. A bypass valve 39v is installed on the bypass pipe 39.

[0042] Cleaning methods for steam systems

[0043] according to Figure 2 The flowchart shown illustrates the cleaning method for the steam system in the combined cycle equipment of this embodiment.

[0044] Apply the steam system cleaning method to use Figure 1 The steam system in the combined cycle unit is described. This steam system includes a main steam line 36, a bypass line 39, and a condenser 30.

[0045] If the construction of the combined cycle unit is completed, the initial ignition process S10 is executed. Subsequently, the intermittent operation processing process S20 of the gas turbine 10, the trial operation processing process S30 of the gas turbine 10, and the overall trial operation process S50 are executed sequentially. The cleaning method of this embodiment is performed in the intermittent operation processing process S20 and the trial operation processing process S30 of the gas turbine 10.

[0046] In the initial ignition step S10, fuel is supplied to the burner 14 to generate combustion gases within the burner 14, which drive the turbine 15. In this initial ignition step S10, it is confirmed whether the combustion of fuel within the burner 14 and the driving of the turbine 15 are taking place.

[0047] After the initial ignition process S10, the gas turbine 10 undergoes an intermittent operation processing process S20. This intermittent operation processing process S20 includes a no-load operation process S21, a pressurization process S22, an intermittent purging process S23, a foreign matter removal process after intermittent purging S24, and a judgment process S25.

[0048] In the no-load operation step S21, fuel is supplied to the gas turbine 10 with the steam shut-off valve 37 and bypass valve 39v closed, and the gas turbine 10 operates under no-load conditions. In this no-load operation step S21, the condensate pump 33 and feedwater pump 35 are driven with the feedwater valve 34v open. Furthermore, no-load operation refers to the state where the gas turbine generator 18 is not electrically connected to the external system, i.e., the operation of the gas turbine 10 with circuit breakers 19b and 29b open.

[0049] The accumulator step S22 is performed during the no-load operation step S21. In this accumulator step S22, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas from the gas turbine 10, and the steam is stored in the accumulator area of ​​the main steam line 36, which is located closer to the waste heat recovery boiler 20 than the steam shut-off valve 37, and in the bypass line 39, which is located closer to the waste heat recovery boiler 20 than the bypass valve 39v.

[0050] During the execution of the accumulator step S22, if the pressure in the accumulator area reaches or exceeds the specified pressure, fuel supply to the gas turbine 10 is stopped, ending the no-load operation step S21 and the accumulator step S22. At this time, the feedwater valve 34v is closed, and the condenser pump 33 and the feedwater pump 35 are stopped. The intermittent purging step S23 is executed after the no-load operation step S21 and the accumulator step S22. In this intermittent purging step S23, the bypass valve 39v is opened, allowing the steam in the accumulator area to flow into the condenser 30 in one go. During the execution of this intermittent purging step S23, a portion of the foreign matter in the accumulator area and the bypass line 39 between the bypass valve 39v and the condenser 30 flows into the condenser 30 along with the steam.

[0051] The intermittent purging followed by foreign matter removal step S24 is performed after the intermittent purging step S23. In this step S24, foreign matter is removed from the condenser 30 and the condenser piping 31. Specifically, for example, a worker enters the condenser 30 and removes the foreign matter therein. Furthermore, a worker removes foreign matter stored in the filter 32 located in the condenser piping 31.

[0052] The judgment step S25 is performed after the intermittent purging and foreign matter removal step S24. In this judgment step S25, the operator determines whether the end conditions of the intermittent operation process are met. Here, the end conditions of the intermittent operation process are, for example, that the number of times the intermittent operation process S20 has been performed has reached a predetermined number, or that the amount of foreign matter removed in the intermittent purging and foreign matter removal step S24 has reached or fallen below a predetermined amount.

[0053] When the operator determines that the termination conditions for intermittent operation are not met, the above-described no-load operation step S21, pressurization step S22, intermittent purging step S23, foreign matter removal step S24 after intermittent purging, and judgment step S25 are executed again. That is, in this embodiment, the intermittent operation process S20 is sometimes executed multiple times. Thus, when the intermittent operation process S20 is executed multiple times, the intermittent purging step S23 is executed in each intermittent operation process S20, thereby improving the removal efficiency of foreign matter in the steam system.

[0054] Furthermore, when the staff determines that the conditions for ending the intermittent operation process are met, the trial operation process S30 of the gas turbine 10 is executed.

[0055] The trial operation process S30 of the gas turbine 10 includes a no-load trial operation process S31 and a partial load trial operation process S41 performed after the no-load trial operation process S31.

[0056] The no-load trial operation process S31 includes the no-load trial operation process S32, the no-load continuous purging process S33, the no-load foreign matter removal process S34, and the judgment process S35.

[0057] In the no-load test run step S32, fuel is supplied to the gas turbine 10 with the steam shut-off valve 37 closed and the bypass valve 39v open, and the gas turbine 10 is subjected to a no-load test run. In this no-load test run step S32, the condensate pump 33 and the feedwater pump 35 are driven with the feedwater valve 34v open. Here, test run refers to the operation including the adjustment of the gas turbine 10's control system. Specifically, the adjustment of the control system refers to adjusting the control parameters of the IGV 13i or the fuel regulating valve 17 based on data obtained from the operation of the gas turbine 10. Furthermore, in the no-load operation step S21 of the aforementioned intermittent operation processing step S20, the control system of the gas turbine 10 is not adjusted. Therefore, the operation of the gas turbine 10 in the no-load operation step S21 is not a test run.

[0058] The no-load continuous purging process S33 is performed during the no-load trial run process S32. In this no-load continuous purging process S33, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, and the steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam line 36 and the bypass line 39. During the execution of this no-load continuous purging process S33, a portion of foreign matter in the main steam line 36 and the bypass line 39 flows into the condenser 30 along with the steam.

[0059] After the no-load test run step S32, fuel supply to the gas turbine 10 is stopped, and the feedwater valve 34v is closed. After stopping the condensate pump 33 and the feedwater pump 35, the no-load post-external debris removal step S34 is performed. In this no-load post-external debris removal step S34, foreign matter inside the condenser 30 and the condensate pipe 31 is removed in the same way as in the aforementioned intermittent purging post-external debris removal step S24.

[0060] The judgment step S35 is performed after the no-load foreign matter removal step S34. In this judgment step S35, the operator determines whether the end conditions of the no-load test run are met. Here, the end conditions of the no-load test run are, for example, that the adjustment of the control system in the no-load test run step S32 has been completed, or that the adjustment of the control system in the no-load test run step S32 has been completed and the amount of foreign matter removed in the no-load foreign matter removal step S34 has reached or fallen below a predetermined amount.

[0061] When the operator determines that the termination conditions for the no-load test run are not met, the no-load test run procedure S32, the no-load continuous purging procedure S33, the no-load post-exhaust foreign matter removal procedure S34, and the judgment procedure S35 described above are executed again. That is, in this embodiment, the no-load test run procedure S31 may be executed multiple times. Thus, when the no-load test run procedure S31 is executed multiple times, the no-load continuous purging procedure S33 is executed in each no-load test run procedure S31, thereby improving the removal efficiency of foreign matter in the steam system.

[0062] Furthermore, when the staff determines that the conditions for the end of the no-load test run are met, the partial load test run process S41 of the gas turbine 10 is executed.

[0063] The partial load test run process S41 includes a first load test run process S41a and a second load test run process S41b executed after the first load test run process S41a.

[0064] The first load trial run processing step S41a includes the first load trial run step S42a, the first load continuous purging step S43a, the first load post-foreign matter removal step S44a, and the judgment step S45a.

[0065] In the first load test run step S42a, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 is tested under a first load. In this first load test run step S42a, with the feedwater valve 34v open, the condensate pump 33 and the feedwater pump 35 are driven. Here, the first load is, for example, 20% to 40% of the rated load of the gas turbine 10 when it is set to 100%.

[0066] The first load continuous purging process S43a is performed in the first load trial run process S42a. In this first load continuous purging process S43a, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, and the steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam line 36 and the bypass line 39. During the execution of this first load continuous purging process S43a, a portion of foreign matter in the main steam line 36 and the bypass line 39 flows into the condenser 30 along with the steam.

[0067] After the first load test run step S42a, fuel supply to the gas turbine 10 is stopped, and the feedwater valve 34v is closed. After stopping the condensate pump 33 and the feedwater pump 35, the first load post-load foreign matter removal step S44a is performed. In this first load post-load foreign matter removal step S44a, foreign matter inside the condenser 30 and the condensate pipe 31 is removed in the same way as in the aforementioned intermittent purging post-foreign matter removal step S24.

[0068] The judgment process S45a is executed after the foreign matter removal process S44a following the first load. In this judgment process S45a, the operator determines whether the load change conditions are met. Here, the load change conditions may refer to, for example, the completion of the control system adjustment in the first load trial run process S42a, or the completion of the control system adjustment in the first load trial run process S42a, and the amount of foreign matter removed in the foreign matter removal process S44a following the first load being below a predetermined amount.

[0069] When the operator determines that the load change conditions are not met, the first load test run procedure S42a, the first load continuous purging procedure S43a, the first load post-load foreign matter removal procedure S44a, and the judgment procedure S45a described above are executed again. That is, in this embodiment, the first load test run procedure S41a may be executed multiple times. Thus, when the first load test run procedure S41a is executed multiple times, the first load continuous purging procedure S43a is executed in each first load test run procedure S41a, thereby improving the foreign matter removal efficiency in the steam system.

[0070] Furthermore, when the staff determines that the load change is met, the second load test run process S41b of the gas turbine 10 is executed.

[0071] The second load trial operation process S41b includes the second load trial operation process S42b, the second load continuous purging process S43b, the second load post-foreign matter removal process S44b, and the judgment process S45b.

[0072] In the second load test run step S42b, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 is tested at a second load greater than the first load. In this second load test run step S42b, with the feedwater valve 34v open, the condensate pump 33 and the feedwater pump 35 are driven. Here, the second load is, for example, 45% to 70% of the rated load of the gas turbine 10 when it is set to 100%.

[0073] The second load continuous purging process S43b is performed in the second load trial run process S42b. In this second load continuous purging process S43b, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, and the steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam line 36 and the bypass line 39. During the execution of this second load continuous purging process S43b, a portion of foreign matter in the main steam line 36 and the bypass line 39 flows into the condenser 30 along with the steam.

[0074] After the second load test run step S42b, fuel supply to the gas turbine 10 is stopped, and the feedwater valve 34v is closed. After stopping the condensate pump 33 and the feedwater pump 35, the second load post-load foreign matter removal step S44b is executed. In this second load post-load foreign matter removal step S44b, foreign matter in the condenser 30 and the condensate pipe 31 is removed in the same way as in the aforementioned intermittent purging post-foreign matter removal step S24.

[0075] The judgment step S45b is executed after the foreign matter removal step S44b following the second load. In this judgment step S45b, the operator determines whether the end conditions of the second load trial run are met. Here, the end conditions of the second load trial run are, for example, that the adjustment of the control system in the second load trial run step S42b has been completed, or that the adjustment of the control system in the second load trial run step S42b has been completed and the amount of foreign matter removed in the foreign matter removal step S44b following the second load has reached or fallen below a predetermined amount.

[0076] When the operator determines that the termination conditions for the second load test run are not met, the second load test run procedure S42b, the second load continuous purging procedure S43b, the second load post-foreign matter removal procedure S44b, and the judgment procedure S45b described above are executed again. That is, in this embodiment, the second load test run procedure S41b may be executed multiple times. Thus, when the second load test run procedure S41b is executed multiple times, the second load continuous purging procedure S43b is executed in each second load test run procedure S41b, thereby improving the removal efficiency of foreign matter in the steam system.

[0077] Furthermore, when the staff determines that the conditions for the completion of the second load test run are met, the second load test run process S41b of the gas turbine 10 ends. Therefore, at this time, the test run process S30 of the gas turbine 10 ends. With the completion of this test run process S30, the cleaning method in this embodiment is completed.

[0078] If the trial run procedure S30 of the gas turbine 10 is completed, the overall trial run procedure S50 is executed. In this overall trial run procedure S50, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, for example, to perform a trial run at rated load. In this overall trial run procedure S50, with the feedwater valve 34v open, the condensate pump 33 and the feedwater pump 35 are driven. In the initial stage of this trial run, steam from the waste heat recovery boiler 20 flows into the condenser 30 via the main steam line 36 and the bypass line 39. Then, in this initial stage, if the steam from the waste heat recovery boiler 20 meets the turbine supply conditions, the bypass valve 39v is closed, and the steam shut-off valve 37 and the steam regulating valve 38 are opened. As a result, steam from the waste heat recovery boiler 20 begins to flow into the steam turbine 25. Then, the opening of the steam regulating valve 38 is gradually increased, for example, to perform a trial run of the steam turbine 25 at rated load.

[0079] In the processes described above, the no-load trial run process S32, the first load trial run process S42a, and the second load trial run process S42b are all parts of the trial run processes S32, S42a, and S42b in the trial run processing process S30. Furthermore, the first load trial run process S42a and the second load trial run process S42b are all parts of the partial load trial run processes S42a and S42b in the partial load trial run processing process S41. The no-load continuous purging process S33, the first load continuous purging process S43a, and the second load continuous purging process S43b are all parts of the continuous purging processes S33, S43a, and S43b in the trial run processing process S30. The first load continuous purging process S43a and the second load continuous purging process S43b are all parts of the partial load continuous purging processes S43a and S43b. The foreign matter removal process S34 after no load, the foreign matter removal process S44a after the first load, and the foreign matter removal process S44b after the second load are all parts of the foreign matter removal processes S34, S44a, and S44b after the trial operation processing process S30. The foreign matter removal process S44a after the first load and the foreign matter removal process S44b after the second load are all parts of the foreign matter removal processes S44a and S44b after partial load.

[0080] As described above, in this embodiment, the steam system is cleaned without the need for temporary piping, thus reducing cleaning costs. Furthermore, in this embodiment, since foreign matter blown away by steam flows into the condenser 30 along with the steam, pollution around the equipment or noise from steam emissions into the atmosphere can be suppressed.

[0081] Furthermore, in this embodiment, after performing the intermittent purging step S23 to clean the steam system, the continuous purging steps S33, S43a, and S43b are performed to further clean the steam system, thus enabling efficient cleaning of the steam system.

[0082] Furthermore, in this embodiment, steam generated during the trial operation of the gas turbine 10 is used to perform continuous purging processes S33, S43a, and S43b to clean the steam system. Therefore, in this embodiment, compared to performing the trial operation of the gas turbine 10 and the steam purging for cleaning the steam system separately, the period from the completion of the combined cycle equipment construction project to the introduction of steam into the steam turbine 25 can be shortened.

[0083] Here, the force used to remove foreign matter from the piping by steam is called the cleaning force F. As shown in the following equation (1), the cleaning force F is the dynamic pressure P in the piping multiplied by the flow rate Q of the steam flowing through the piping.

[0084] F = P × Q (1)

[0085] The dynamic pressure P in the piping can be expressed by the following equation (2).

[0086] P=(γ / 2g)×V (2)

[0087] In addition, γ is the specific weight of steam, g is the acceleration due to gravity, and V is the flow velocity.

[0088] Furthermore, the steam flow rate Q can be represented by the following equation (3).

[0089] Q = A·V (3)

[0090] Additionally, A represents the cross-sectional area of ​​the piping.

[0091] If the dynamic pressure P in the piping, expressed by equation (2), and the steam flow rate Q, expressed by equation (3), are substituted into equation (1), then the cleaning force F can be expressed as shown in equation (4) below.

[0092] F = P × Q

[0093] =((γ / 2g)×V)×A·V

[0094] = (γ / 2g)×A·V 2 (4)

[0095] The cleaning force within the main steam pipe 36 during rated operation of the steam turbine 25 is defined as the rated cleaning force Fn, and the cleaning force within the main steam pipe 36 and bypass pipe 39 during the purging processes S23 and S33, S43a, and S43b described above is defined as the purging cleaning force Fb. Furthermore, the purging cleaning force Fb relative to the rated cleaning force Fn is defined as the cleaning force ratio R (=Fb / Fn).

[0096] In this embodiment, during the intermittent purging process S23, the no-load continuous purging process S33, and the first load continuous purging process S43a, the operation of the bypass valve 39v is adjusted to set the cleaning power ratio R to less than 1. Furthermore, in this embodiment, during the second load continuous purging process S43b, the operation of the bypass valve 39v is adjusted to set the cleaning power ratio R to 1 or more.

[0097] In this embodiment, as described above, the cleaning power rate R in the intermittent purging process S23, the no-load continuous purging process S33, and the first load continuous purging process S43a is set to less than 1 to remove foreign matter that is relatively easy to remove from the piping in these processes, and to make it easy to remove foreign matter that is relatively difficult to remove from the piping. Then, the cleaning power rate R in the second load continuous purging process S43b following these processes is set to 1 or more to remove foreign matter that could not be removed in the previous processes in the second load continuous purging process S43b. Therefore, from this viewpoint, the steam system can also be cleaned efficiently in this embodiment.

[0098] Alternatively, the cleaning efficiency R in the intermittent purging process S23, the no-load continuous purging process S33, and the first load continuous purging process S43a may be 1 or higher.

[0099] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Various additions, modifications, substitutions, and partial deletions may be made without departing from the conceptual idea and spirit of the present invention derived from the content specified in the technical solution and its equivalents.

[0100] Postscript

[0101] The cleaning method for the steam system in the combined cycle equipment in the above embodiments can be mastered as follows, for example.

[0102] (1) The cleaning method for the steam system in the combined cycle equipment in the first method is applicable to the following combined cycle equipment.

[0103] The combined cycle unit includes: a gas turbine 10; a waste heat recovery boiler 20 capable of generating steam using the heat from the exhaust gas from the gas turbine 10; a steam turbine 25 driven by the steam from the waste heat recovery boiler 20; a condenser 30 capable of converting the steam from the steam turbine 25 back into water; a condensate pump 33 capable of pressurizing the water from the condenser 30; a main steam line 36 capable of guiding the steam generated in the waste heat recovery boiler 20 to the steam turbine 25; and a steam shut-off valve 37. The main steam line 36 is configured to prevent steam from flowing into the steam turbine 25; the bypass line 39 branches off from the main steam line 36 at a position closer to the waste heat recovery boiler 20 than the steam shut-off valve 37 and connects to the condenser 30; the bypass valve 39v is configured on the bypass line 39; the condensate line 31 guides water in the condenser 30 to the condensate pump 33; and the water supply line 34 guides water pressurized by the condensate pump 33 to the waste heat recovery boiler 20.

[0104] In the cleaning method, an intermittent operation processing step S20 is performed, followed by a trial operation processing step S30.

[0105] The intermittent operation processing step S20 includes: a no-load operation step S21, in which fuel is supplied to the gas turbine 10 and the gas turbine 10 is operated without load while the steam shut-off valve 37 and the bypass valve 39v are closed; and a pressure storage step S22, in which the heat from the exhaust gas from the gas turbine 10 is used to generate steam in the waste heat recovery boiler 20 during the no-load operation step S21, and the steam is stored in the main steam pipeline 36, which is located closer to the waste heat recovery boiler than the steam shut-off valve 37. The pressure storage area on the furnace 20 side and the portion of the bypass pipe 39 that is closer to the waste heat recovery boiler 20 side than the bypass valve 39v; intermittent purging process S23, after the pressure storage process S22, stops supplying fuel to the gas turbine 10 and opens the bypass valve 39v to allow steam in the pressure storage area to flow into the condenser 30; and intermittent purging foreign matter removal process S24, after the intermittent purging process S23, removes foreign matter from the condenser 30 and the condensing pipe 31.

[0106] The trial operation process S30 includes: trial operation processes S32, S42a, and S42b, in which fuel is supplied to the gas turbine 10 and the gas turbine 10 is tested while the steam shut-off valve 37 is closed and the bypass valve 39v is open; continuous purging processes S33, S43a, and S43b, in which the heat from the exhaust gas from the gas turbine 10 is used to generate steam in the waste heat recovery boiler 20 during the trial operation processes S32, S42a, and S42b, and the steam from the waste heat recovery boiler 20 flows into the condenser 30 through a part of the main steam pipeline 36 and the bypass pipeline 39; and foreign matter removal processes S34, S44a, and S44b after the trial operation processes S32, S42a, and S42b, after the fuel supply to the gas turbine 10 is stopped, foreign matter is removed from the condenser 30 and the condensation pipeline 31.

[0107] In this method, the steam system is cleaned without the need for temporary piping, thus reducing cleaning costs. Furthermore, in this method, foreign matter blown away by steam flows into the condenser 30 along with the steam, thus reducing pollution around the equipment and noise from steam emissions into the atmosphere.

[0108] In this method, after performing the intermittent purging step S23 to clean the steam system, the continuous purging steps S33, S43a, and S43b are performed to further clean the steam system, thus enabling efficient cleaning of the steam system.

[0109] Furthermore, in this method, steam generated during the trial operation of the gas turbine 10 is used to perform continuous purging processes S33, S43a, and S43b to clean the steam system. Therefore, in this method, compared to separately performing the trial operation of the gas turbine 10 and the purging for cleaning the steam system, the period from the completion of the combined cycle equipment construction project to the introduction of steam into the steam turbine 25 can be shortened.

[0110] (2) Cleaning method for the steam system in the combined cycle equipment in the second method.

[0111] In the cleaning method of the steam system in the combined cycle equipment in the first approach, the intermittent operation processing step S20 is performed multiple times before the trial operation steps S32, S42a, and S42b.

[0112] In this method, multiple intermittent operation processing steps S20 are performed, and an intermittent purging step S23 is performed in each intermittent operation processing step S20, thereby improving the removal efficiency of foreign matter in the steam system.

[0113] (3) Cleaning method for the steam system in the combined cycle equipment in the third method.

[0114] In the cleaning method of the steam system in the combined cycle equipment of the first or second method

[0115] The trial operation process S30 includes a partial load trial operation process S41.

[0116] The partial load test run process S41 includes: partial load test run processes S42a and S42b as part of the test run processes S32, S42a, and S42b; partial load continuous purging processes S43a and S43b as part of the continuous purging processes S33, S43a, and S43b; and partial load post-test run foreign matter removal processes S44a and S44b as part of the post-test run foreign matter removal processes S34, S44a, and S44b. In the partial load test run processes S42a and S42b, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 undergoes a partial load test run. In the partial load continuous purging processes S43a and S43b, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10 during the partial load trial operation processes S42a and S42b. This steam flows from the waste heat recovery boiler 20 into the condenser 30 via a portion of the main steam pipeline 36 and the bypass pipeline 39. After the partial load trial operation processes S42a and S42b, and after the fuel supply to the gas turbine 10 is stopped, the post-partial load foreign matter removal processes S44a and S44b are performed. In the post-partial load foreign matter removal processes S44a and S44b, foreign matter is removed from the condenser 30 and the condensation pipeline 31.

[0117] In this method, the partial load continuous purging steps S43a and S43b are performed in the partial load trial operation process S41. Therefore, compared with continuous purging without load, the removal efficiency of foreign matter in the steam system can be improved.

[0118] (4) Cleaning method for the steam system in the combined cycle equipment in the fourth method.

[0119] In the cleaning method of the steam system in the combined cycle equipment in the third approach, the partial load trial run process 41 (S41a, S41b) is performed multiple times.

[0120] In this method, multiple partial load trial operation processing steps S41 (S41a, S41b) are performed, and partial load continuous purging steps S43a, S43b are performed in each partial load trial operation processing step S41a, 41b, thereby improving the removal efficiency of foreign matter in the steam system.

[0121] (5) Cleaning method for the steam system in the combined cycle equipment in the fifth method.

[0122] In the cleaning method of the steam system in the combined cycle equipment in the fourth approach,

[0123] When the ratio of the force Fb used to remove foreign matter through steam in the main steam pipeline 36 and the bypass pipeline 39 during the purging of the intermittent purging process S23 and the continuous purging processes S33, S43a, and S43b to the force Fn used to remove foreign matter through steam in the main steam pipeline 36 during the rated operation of the steam turbine 25 is set as the cleaning power rate R, in the partial load trial operation process S41 that is executed multiple times, at least in the partial load continuous purging process S43b of the last partial load trial operation process 41, the action of the bypass valve 39v is adjusted to set the cleaning power rate R to 1 or more.

[0124] In this method, at least in the purging process performed before the partial-load continuous purging process S43b in the last partial-load trial operation processing step S41b, foreign matter that is relatively easy to remove from the steam system is purged, and foreign matter that is relatively difficult to remove from the steam system is also easily purged. Furthermore, the cleaning power rate in the partial-load continuous purging process S43b following this purging process is set to 1 or higher to remove foreign matter that was not removed in the preceding purging process. Therefore, in this method, the steam system can be cleaned efficiently.

[0125] (6) Cleaning method for the steam system in the combined cycle equipment in the sixth method.

[0126] In the cleaning method of the steam system in the combined cycle equipment in the fifth method, in the intermittent purging step S23, the action of the bypass valve 39v is adjusted to set the cleaning force rate R to be less than 1.

[0127] (7) Cleaning method for the steam system in the combined cycle equipment in the seventh method.

[0128] In the cleaning method of the steam system in the combined cycle equipment in the first or second method, the trial operation process S30 includes a partial load trial operation process S41.

[0129] The partial load test run process S41 includes a first load test run process S41a and a second load test run process S41b executed after the first load test run process. The first load test run process S41a includes: a first load test run process S42a as part of the test run processes S32, S42a, and S42b; a first load continuous purging process S43a as part of the continuous purging processes S33, S43a, and S43b; and a first post-load foreign matter removal process S44a as part of the post-test run foreign matter removal processes S34, S44a, and S44b. In the first load test run process S42a, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 is tested at a first load less than the rated load. In the first load continuous purging process S43a, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, which was used in the first load trial run process S42a. The steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam line 36 and the bypass line 39. After the first load trial run process S42a, and after the fuel supply to the gas turbine 10 is stopped, the first load post-load foreign matter removal process S44a is performed. In the first load post-load foreign matter removal process S44a, foreign matter is removed from the condenser 30 and the condensation line 31. The second load test run process S41b includes: a second load test run process S42b as part of the test run processes S32, S42a, and S42b; a second load continuous purging process S43b as part of the continuous purging processes S33, S43a, and S43b; and a second load post-test run foreign matter removal process S44b as part of the post-test run foreign matter removal processes S34, S44a, and S44b. In the second load test run process S42b, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 is tested at a second load greater than the first load and less than the rated load. In the second load continuous purging process S43b, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, which was used in the second load trial run process S42b. The steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam line 36 and the bypass line 39. After the second load trial run process S42b, and after the fuel supply to the gas turbine 10 is stopped, the second load post-load foreign matter removal process S44b is performed.In the second load-after foreign matter removal process S44b, foreign matter is removed from the condenser 30 and the condensation pipe 31.

[0130] In this method, multiple partial load trial operation processes S42a and S42b are performed, and partial load continuous purging processes S43a and S43b are performed in each partial load trial operation process S42a and S42b, thus improving the removal efficiency of foreign matter in the steam system.

[0131] (8) Cleaning method for the steam system in the combined cycle equipment in the eighth method.

[0132] In the cleaning method of the steam system in the combined cycle equipment in the seventh method, when the ratio of the force Fb for removing foreign matter by steam in the main steam pipeline 36 and the bypass pipeline 39 during the intermittent purging process S23 and the continuous purging processes S33, S43a, and S43b to the force Fn for removing foreign matter by steam in the main steam pipeline 36 during the rated operation of the steam turbine 25 is set as the cleaning force rate R, in the second load continuous purging process S43b, the operation of the bypass valve 39v is adjusted to set the cleaning force rate R to 1 or more.

[0133] In this method, the purging process performed before the second load continuous purging process S43b in the second load trial operation processing step S41b removes foreign matter that is relatively easy to remove from the steam system, and also makes it easy to remove foreign matter that is relatively difficult to remove from the steam system. Furthermore, the cleaning power rate R in the second load continuous purging process S43b following this purging process is set to 1 or more to remove foreign matter that was not removed in the previous purging process in this partial load continuous purging process S43b. Therefore, in this method, the steam system can be cleaned efficiently.

[0134] (9) Cleaning method for the steam system in the combined cycle equipment of the ninth method.

[0135] In the cleaning method of the steam system in the combined cycle equipment in the eighth method, in the intermittent purging step S23 and the first load continuous purging step S43a, the action of the bypass valve 39v is adjusted to set the cleaning force rate R to be less than 1.

[0136] (10) Cleaning method for the steam system in the combined cycle equipment of the tenth method.

[0137] In the cleaning method of the steam system in the combined cycle equipment of any of the third to the ninth methods, the trial run process S30 includes a no-load trial run process S31 performed before the partial load trial run process S41.

[0138] The no-load test run process S31 includes: a no-load test run process S32 as part of the test run processes S32, S42a, and S42b; a no-load continuous purging process S33 as part of the continuous purging processes S33, S43a, and S43b; and a no-load post-test run foreign matter removal process S34 as part of the post-test run foreign matter removal process. In the no-load test run process S32, with the steam shut-off valve 37 closed and the bypass valve 39v open, fuel is supplied to the gas turbine 10, and the gas turbine 10 undergoes a no-load test run. In the no-load continuous purging process S33, steam is generated in the waste heat recovery boiler 20 using the heat from the exhaust gas of the gas turbine 10, and the steam from the waste heat recovery boiler 20 flows into the condenser 30 via a portion of the main steam pipeline 36 and the bypass pipeline 39. After the no-load test run step S32, and after stopping the fuel supply to the gas turbine 10, the no-load post-extraction foreign matter removal step S34 is performed. In the no-load post-extraction foreign matter removal step S34, foreign matter is removed from the condenser 30 and the condenser pipe 31.

[0139] In this method, the continuous purging process S33 is also performed in the no-load test run process S31, which is performed before the partial load test run process S41, thus improving the removal efficiency of foreign matter in the steam system.

[0140] (11) Cleaning method for the steam system in the combined cycle equipment in Method 11.

[0141] In the cleaning method of the steam system in the combined cycle equipment in the tenth method, the no-load trial run process S31 is performed multiple times.

[0142] In this method, multiple no-load test run processes S31 are performed, and a no-load continuous purging process S33 is performed in each no-load test run process S31, thereby improving the removal efficiency of foreign matter in the steam system.

[0143] (12) Cleaning method for the steam system in the combined cycle equipment of the twelfth method.

[0144] In the cleaning method of the steam system in the combined cycle equipment in the tenth or eleventh method, when the ratio of the force Fb for removing foreign matter by steam in the main steam pipeline 36 and the bypass pipeline 39 during the continuous purging steps S33, S43a, and S43b to the force Fn for removing foreign matter by steam in the main steam pipeline 36 during the rated operation of the steam turbine 25 is set as the cleaning force rate R, in the no-load continuous purging step S33, the operation of the bypass valve 39v is adjusted to set the cleaning force rate R to be less than 1.

[0145] Industrial availability

[0146] In one aspect of the cleaning method of the present invention, the period from the completion of the construction of the combined cycle equipment to the introduction of steam into the steam turbine can be shortened.

[0147] Symbol Explanation

[0148] 10-Gas turbine, 11-Gas turbine rotor, 12-Intermediate casing, 13-Compressor, 13r-Compressor rotor, 13c-Compressor casing, 13i-Intake volume regulator (IGV), 14-Burner, 15-Turbine, 15r-Turbine rotor, 15c-Turbine casing, 16-Fuel line, 17-Fuel regulating valve, 18-Gas turbine generator, 19t-Transformer, 19b-Circuit breaker, 20-Waste heat recovery boiler, 20i-Water inlet, 20o-Steam outlet, 25-Steam turbine, 2 5r - Steam turbine rotor, 25c - Steam turbine casing, 25i - Steam inlet, 25o - Exhaust port, 28 - Steam turbine generator, 29t - Transformer, 29b - Circuit breaker, 30 - Condenser, 31 - Condensate piping, 32 - Filter, 33 - Condensate pump, 34 - Feed water piping, 34v - Feed water valve, 35 - Feed water pump, 36 - Main steam piping, 37 - Steam shut-off valve, 38 - Steam regulating valve, 39 - Bypass piping, 39v - Bypass valve, Arg, Ars - Shaft, PS - External power system.

Claims

1. A method for cleaning a steam system in a combined cycle unit, the combined cycle unit comprising: Gas turbine; Waste heat recovery boilers are capable of generating steam using the heat from the exhaust gases discharged from the gas turbine; A steam turbine capable of being driven by steam from the waste heat recovery boiler; A condenser that can convert the steam discharged from the steam turbine back into water; A condensation pump is capable of pressurizing the water from the condenser; The main steam line is capable of guiding the steam generated in the waste heat recovery boiler to the steam turbine; A steam shut-off valve, installed in the main steam pipeline, is capable of preventing steam from flowing into the steam turbine; A bypass line branches off from the main steam line at a position closer to the waste heat recovery boiler than the steam shut-off valve and connects to the condenser. A bypass valve is installed in the bypass pipeline; The condenser piping guides water from the condenser to the condenser pump; and The water supply pipeline is capable of guiding the water pressurized in the condensate pump to the waste heat recovery boiler. In the cleaning method of the steam system in the combined cycle equipment, Performing an intermittent operation processing step and a trial operation processing step following the intermittent operation processing step. The intermittent operation processing procedure includes: In the no-load operation process, fuel is supplied to the gas turbine while the steam shut-off valve and the bypass valve are closed, and the gas turbine is operated without load. In the pressure storage process, during the no-load operation process, heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam is stored in a pressure storage area that is a portion of the main steam pipeline closer to the waste heat recovery boiler side than the steam shut-off valve and a portion of the bypass pipeline closer to the waste heat recovery boiler side than the bypass valve. In the intermittent purging process, after the accumulator process, fuel supply to the gas turbine is stopped, and the bypass valve is opened to allow steam in the accumulator area to flow into the condenser; and The foreign matter removal process following the intermittent purging step removes foreign matter from the condenser and the condenser piping. The trial operation process includes: In the trial operation process, fuel is supplied to the gas turbine while the steam shut-off valve is closed and the bypass valve is open, and the gas turbine is put into trial operation. In the continuous purging process, during the trial operation, heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam pipeline and the bypass pipeline; and The foreign matter removal process after trial operation involves removing foreign matter from the condenser and condenser pipes after the fuel supply to the gas turbine has been stopped.

2. The cleaning method for the steam system in a combined cycle unit according to claim 1, wherein, The intermittent operation process is performed multiple times before the trial operation process.

3. The cleaning method for the steam system in a combined cycle unit according to claim 1 or 2, wherein, The trial operation process includes a partial load trial operation process. The partial load trial run process includes: a partial load trial run process as part of the trial run process, a partial load continuous purging process as part of the continuous purging process, and a partial load post-trial foreign matter removal process as part of the post-trial run foreign matter removal process. During the partial load test run, with the steam shut-off valve closed and the bypass valve open, fuel is supplied to the gas turbine, and the gas turbine is subjected to a partial load test run. In the partial load continuous purging process, during the partial load trial operation, the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam pipeline and the bypass pipeline. After the partial load test run, and after stopping the fuel supply to the gas turbine, the post-partial load foreign matter removal process is performed. In the partial load removal process, foreign matter is removed from the condenser and the condensation pipeline.

4. The cleaning method for the steam system in a combined cycle unit according to claim 3, wherein, Perform the partial load trial operation process multiple times.

5. The cleaning method for the steam system in a combined cycle unit according to claim 4, wherein, When the ratio of the force used to remove foreign matter through the steam in the main steam pipeline and the bypass pipeline during the intermittent purging process and the continuous purging process to the force used to remove foreign matter through the steam in the main steam pipeline during the rated operation of the steam turbine is defined as the cleaning power rate, In the partial load trial run process that is performed multiple times, at least in the partial load continuous purging process of the last partial load trial run process, the action of the bypass valve is adjusted to set the cleaning power rate to 1 or more.

6. The cleaning method for the steam system in a combined cycle unit according to claim 5, wherein, In the intermittent purging process, the action of the bypass valve is adjusted to set the cleaning power rate to less than 1.

7. The cleaning method for the steam system in a combined cycle unit according to claim 1 or 2, wherein, The trial operation process includes a partial load trial operation process. The partial load trial operation process includes: a first load trial operation process and a second load trial operation process executed after the first load trial operation process. The first load test run process includes: a first load test run process as part of the test run process, a first load continuous purging process as part of the continuous purging process, and a first load post-test run foreign matter removal process as part of the post-test run foreign matter removal process. In the first load test run, with the steam shut-off valve closed and the bypass valve open, fuel is supplied to the gas turbine, and the gas turbine is tested at a first load less than the rated load. In the first load continuous purging process, during the first load trial operation, the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam pipeline and the bypass pipeline. After the first load test run, and after stopping the fuel supply to the gas turbine, the first load-after-foreign matter removal process is performed. In the foreign matter removal process after the first load, foreign matter inside the condenser and the condensation pipeline is removed. The second load trial run process includes: a second load trial run process as part of the trial run process, a second load continuous purging process as part of the continuous purging process, and a second load post-trial foreign matter removal process as part of the post-trial run foreign matter removal process. In the second load test run, with the steam shut-off valve closed and the bypass valve open, fuel is supplied to the gas turbine, and the gas turbine is tested at a second load greater than the first load and less than the rated load. In the second load continuous purging process, during the second load trial operation, the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam pipeline and the bypass pipeline. After the second load test run, and after stopping the fuel supply to the gas turbine, the second post-load foreign matter removal process is performed. In the second load-after foreign matter removal process, foreign matter inside the condenser and the condensation pipeline is removed.

8. The cleaning method for the steam system in a combined cycle unit according to claim 7, wherein, When the ratio of the force used to remove foreign matter through the steam in the main steam pipeline and the bypass pipeline during the intermittent purging process and the continuous purging process to the force used to remove foreign matter through the steam in the main steam pipeline during the rated operation of the steam turbine is defined as the cleaning power rate, In the second continuous purging process, the action of the bypass valve is adjusted to set the cleaning power rate to 1 or higher.

9. The cleaning method for the steam system in a combined cycle unit according to claim 8, wherein, In the intermittent purging process and the first load continuous purging process, the action of the bypass valve is adjusted to set the cleaning power rate to less than 1.

10. The cleaning method for the steam system in a combined cycle unit according to claim 3, wherein, The trial operation process includes a no-load trial operation process performed before the partial load trial operation process. The no-load trial run process includes: a no-load trial run process as part of the trial run process, a no-load continuous purging process as part of the continuous purging process, and a no-load post-trial foreign matter removal process as part of the post-trial run foreign matter removal process. During the no-load test run, with the steam shut-off valve closed and the bypass valve open, fuel is supplied to the gas turbine, and the gas turbine is subjected to a no-load test run. In the no-load continuous purging process, during the no-load trial operation, the heat from the exhaust gas from the gas turbine is used to generate steam in the waste heat recovery boiler, and the steam from the waste heat recovery boiler flows into the condenser via a portion of the main steam pipeline and the bypass pipeline. After the no-load test run, and after stopping the fuel supply to the gas turbine, the no-load post-external debris removal process is performed. In the no-load foreign matter removal process, foreign matter is removed from the condenser and the condensation pipeline.

11. The method for cleaning the steam system in a combined cycle unit according to claim 10, wherein, Perform the no-load trial run process multiple times.

12. The method for cleaning the steam system in a combined cycle unit according to claim 10 or 11, wherein, When the ratio of the force used to remove foreign matter through steam in the main steam pipeline and the bypass pipeline during the continuous purging process to the force used to remove foreign matter through steam in the main steam pipeline during the rated operation of the steam turbine is defined as the cleaning power rate, In the no-load continuous purging process, the action of the bypass valve is adjusted to set the cleaning force rate to less than 1.

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