Method for pre-operational cleaning of water and steam systems in combined cycle power plant and combined cycle power plant arranged therefor

Abstract

A method of pre-operational cleaning of a water and steam system in a combined cycle power plant is disclosed that includes a gas turbine engine, a steam turbine system, a condenser, and a heat recovery steam generator (HRSG). The method comprises: performing pre-operation initial scouring and chemical cleaning operations on a water and steam system of the combined cycle power plant; igniting the gas turbine engine and commissioning the gas turbine engine; and while commissioning the gas turbine engine, performing a validated steam purge procedure including a steam purge operation in which steam is generated in the HRSG and purged through portions of the closed flow circuit under high speed, temperature and cleaning force ratio conditions, a steam turbine system for cleaning steam delivery parts of the HRSG and connecting the HRSG to a steam line of the steam turbine system; and monitoring and verifying the cleanliness of the selected steam purged steam line. A combined cycle power plant arranged to perform such pre-operational cleaning is also disclosed.

Description

Technical Field

[0001] The present disclosure relates to pre - operation cleaning of new or refurbished components in a combined cycle power generation plant, and more particularly, to a method for pre - operation cleaning of the water and steam systems in a combined cycle power generation plant. Background Art

[0002] A combined cycle power generation plant utilizes a gas turbine engine and a steam turbine engine in combination to generate power. In a combined cycle power generation plant, the gas turbine engine is thermally connected to the steam turbine engine through a heat recovery steam generator (HRSG). The HRSG is a non - contact heat exchanger that allows feed water for the steam generation process to be heated by the exhaust gases discharged from the gas turbine engine, which would otherwise be wasted. The HRSG can be a large duct with a tube bundle inserted therein such that the water flowing through the tube bundle is heated into steam by the exhaust gases passing through the duct.

[0003] Modern combined cycle power generation plants use multi - pressure HRSGs that can have three different operating pressures (high, medium, and low) with components to generate steam at various pressures and temperatures. The HRSG can include, for example, a low - pressure section, a medium - pressure section, and a high - pressure section, each of which typically can include one or more economizers, evaporators, and / or superheaters. The steam at the corresponding pressure is used as the steam supply for the corresponding stage of the steam turbine system. The gas turbine system and the steam turbine system drive one or two generators to generate electricity.

[0004] The used steam from the steam turbine system is discharged into a condenser where the steam condenses, and then the condensate is supplied back to the HRSG from the condenser via one or more conduits by means of a condensate pump.

[0005] In the operation of a power generation plant, the purity of the steam must meet strict requirements. It is important to avoid situations where particulate debris is entrained in the steam and may affect the operation of the power generation plant or even cause damage to the equipment components. For example, particulate debris may clog a steam screen or block narrow steam channels. Particulate debris may cause corrosion and impact damage to the stationary and rotating components of the steam turbine, and may also clog or damage the inner surface of the steam valves used to control the steam flow.

[0006] During the manufacture and installation of a combined cycle power generation plant, despite all preventive measures, contaminants such as welding spatter, chips, welding electrode residues, mud, sand, dust, etc. may still remain in the system. The contaminants sometimes exist loosely, and they sometimes adhere to the inner walls of the equipment parts.

[0007] Thus, in typical prior art methods for starting new and refurbished steam turbine generator facilities, many methods have been employed to remove particulate contamination from the internal surfaces of steam delivery equipment and tubing (including the HRSG area, the steam line between the HRSG and the steam turbine system, and the steam line leading to the condenser) and control valves therein. Typically, such steam delivery components are blown out or flushed prior to commissioning the gas turbine engine and prior to each first steam pulse in the steam turbine system to ensure that they are free of particulate contaminants prior to startup.

[0008] Pre-operation cleaning methods in the art involve flushing steam and water system components with treated water and chemical cleaning procedures (chemical cleaning procedures may include hot caustic degreasing, acid cleaning, passivation, rinsing, and / or air purge cleaning), followed by inspection of drums and low point headers and manual cleaning or flushing of any deposits therein. Only then is the gas turbine engine and the entire combined cycle power generation equipment commissioned.

[0009] It is also known to perform steam purge procedures, where steam discharged to the atmosphere via temporary tubing and silencers installed at the steam turbine isolation and control valves is used to purge the steam generator and associated steam lines. The steam purge can be continuous or discontinuous (pulse purge) and is typically carried out at low load and low exhaust pressure to achieve a desired disturbance factor. Some other methods include combined loading of steam via temporary tubing to the atmosphere and condenser. Steam discharge to the condenser during normal bypass operation has also been used without achieving a high disturbance factor and without target verification of the cleaned water and steam system components, but with less efficiency than required.

[0010] US2009 / 0107532 A1 discloses a method for pre - operation cleaning of equipment parts for power generation equipment, the method comprising: continuously guiding a medium through one or more equipment parts to be cleaned in a closed flow loop, and testing the medium for the purity of the operating equipment parts. Steam is extracted from a steam boiler plant, and the liquid obtained from the steam in a condenser is supplied to the operating equipment parts and guided in the closed flow loop for cleaning the equipment parts via steam. To bypass the high - pressure stage of a steam turbine unit, a branch is provided from a high - pressure steam line for a temporary cleaning facility, which has a temporary steam line system and a plurality of blow - out inserts and a measuring device arranged between these blow - out inserts. The measuring device is a polished metal baffle, which is introduced transversely to the flow direction into the steam line, and which allows visual observation and judgment of the purity of the medium by the impact of particles hitting the baffle during the blow - out operation. The method requires the installation of a temporary steam line system for performing a steam purging procedure. The temporary steam line system and the temporary blow - out facility are to be removed for the normal operation of the power generation equipment. This increases the workload, cost and time required for pre - operation cleaning.

[0011] US10 612 771 B2 discloses a method for pre - operation cleaning of a water and steam system in a combined cycle power generation equipment, the method comprising: blowing steam into a condenser using a minor pre - operation cleaning, and first blowing the steam into the atmosphere using temporary tubing, and then blowing the steam into the condenser using another temporary tubing to bypass a bypass valve in a pipeline leading to the condenser. The temporary tubing and equipment are designed to allow base - load or up to 100% load operation. To monitor and confirm the cleanliness of the discharged steam, a target insertion device in the form of a highly polished metal plate is inserted into the steam purging exhaust pipe, and then it can be removed and inspected to determine the persistence of particulate contamination in the discharged steam. The steam purging procedure is effective and can be carried out during the commissioning of a gas turbine engine. However, the entire set of temporary tubing, temporary equipment and temporary controls required to verify the steam purging procedure greatly increases the corresponding configuration and re - configuration workload, material requirements and costs. In addition, since the first steam purge is discharged into the atmosphere, an atmospheric silencer must be installed and used at the steam - to - atmosphere discharge point to avoid excessive noise pollution.

[0012] Conventional methods for pre - operation cleaning of steam - generating equipment and tubing use large temporary tubing arrangements with corresponding configuration and re - configuration workloads, required man - power and material costs; they perform steam purges to the atmosphere in cases where an atmospheric silencer and large amounts of de - ionized water are required; they cannot be carried out in parallel with the normal commissioning of a gas turbine engine; and / or they are time - consuming and costly to implement.

[0013] One object of the present invention is to provide a new method for pre - operation cleaning of the water and steam systems in a combined cycle power generation plant using verified steam purging, which overcomes one or more of the above - mentioned deficiencies of conventional pre - operation cleaning methods. The method should allow for effective cleaning of the steam and water systems and can preferably be carried out at least partially in parallel with the commissioning of the gas turbine system in order to reduce the ignition hours and fuel consumption in the gas turbine system as well as the consumption of de - ionized water for pre - operation cleaning. In addition, the method should have no safety issues and visual pollution and should meet noise and emission compliance requirements.

[0014] Another object of the present invention is to provide a combined cycle power generation plant arranged to perform such pre - operation cleaning. Summary of the Invention

[0015] To achieve the above object, according to one aspect of the present invention, a method for pre - operation cleaning of the water and steam systems in a combined cycle power generation plant is provided. The combined cycle power generation plant includes a gas turbine engine, a steam turbine system, a condenser, and a heat recovery steam generator (HRSG). The method includes: performing a pre - operation initial flushing and chemical cleaning operation on the water and steam systems of the finally constructed combined cycle power generation plant; igniting the gas turbine engine and commissioning the gas turbine engine; while commissioning the gas turbine engine, performing a verified steam purging procedure including a steam purging operation, wherein steam is generated in the HRSG and the steam is purged through a part of a closed - flow loop under high speed, temperature, and cleaning force ratio conditions to clean the steam delivery parts of the HRSG and the steam pipeline connecting the HRSG to the steam turbine, wherein the steam is directed around the steam turbine system via a permanent operation bypass pipeline without using any temporary tubing and is discharged to the condenser; and monitoring and verifying the cleanliness of selected steam - purged steam pipelines.

[0016] In the method of the present invention, the normal commissioning of the gas turbine system is carried out in parallel with the verified purging procedure. In particular, normal and comprehensive gas turbine commissioning activities can be carried out, that is, driving the gas turbine in bypass operation to full - speed no - load (FSNL) conditions, performing synchronization and HRSG safety valve tests, loading the gas turbine system up to base load for combustion adjustment in the case of installing a fuel gas coarse filter, and other common commissioning activities. The power generation plant can be started in its normal configuration without any temporary or manual controls. No temporary tubing or pipelines are required, resulting in minimal configuration and re - configuration of the equipment for performing the pre - cleaning.

[0017] Temporary pipelines or lines are understood to particularly mean steam pipes or lines that are required only for the cleaning process (e.g., bypassing the steam turbine system) and will be installed only for the cleaning process. In contrast, permanent operating pipelines or lines are required for normal operation (e.g., bypassing the steam turbine system under specific operating conditions such as load rejection) and are installed for normal operation. Since the method of the present invention does not require such temporary pipes, temporary compressors, temporary outflow members, and temporary controls, the effort, time, and personnel and material costs for performing pre-cleaning can be greatly reduced.

[0018] Furthermore, the verification purge method to the condenser avoids discharging steam to the atmosphere, as done in some conventional pre-cleaning methods. Therefore, the deionized water consumption for maintaining the quality of the circulating water, reducing noise, and minimizing visual pollution can be restricted. In addition, commissioning the gas turbine system in parallel with the verification purge procedure facilitates restricting the ignition hours and fuel consumption in the gas turbine system, as well as meeting emission compliance during steam purging at high loads. There are no safety issues because the equipment is in normal operation, including all normal regulating and protecting components. Effective cleaning can be achieved using thermal cycling and the maximum cycle temperature. Due to extensive pre-operation cleaning using a condenser included in the steam flow path, early steam quality is obtained, where the cycle is under vacuum and operates at high loads.

[0019] For a new generation of gas turbine systems, the exhaust gas temperature of the gas turbine engine is higher, and the method has no limitations for some dry steam sections in the HRSG and is also not limited by the design temperature of any temporary pipes that may require additional temperature control. For a new generation of gas turbine engines, the steam flow becomes higher, and traditional pre-cleaning methods represent a significant deionized water consumption. Therefore, the temporary pipes and installations in conventional systems are gradually becoming larger.

[0020] In the method of the present invention, the initial flushing and chemical cleaning operations before operation may include any known chemical cleaning procedures, including open or closed flushing, hot degreasing, acid cleaning, passivation, and rinsing. Chemical cleaning is performed on the entire steam and water system (including the HRSG drum, economizer, evaporator, superheater, and reheater, the balance of the plant steam lines, auxiliary steam lines, feedwater lines, and condensate systems). In some specific cases, if the steam tubing from the HRSG to the steam turbine is mechanically cleaned by another method (e.g., sandblasted and cleaned after prefabrication and installation, or water-sprayed and inspected after installation), then acid cleaning may be limited to the HRSG water and steam systems. Once the chemical cleaning is completed, long-term inspections can be carried out at various locations including low points and HRSG collectors, and these locations can be hydrolyzed using high-pressure water jets for cleaning to remove any solid deposits remaining from the chemical cleaning. Together with the steam purging procedure, all steam-generating equipment contaminants (such as sand, dust, mud, welding spatter, chips, welding electrode residues, etc.) that may remain in the system after the manufacture and installation of the power generation equipment can be effectively removed before the initial start-up of the equipment.

[0021] In any of the above versions of the method, the steam purging operation can be advantageously performed when the gas turbine engine is operating at base load or maximum load conditions. The steam delivery parts, steam lines, and operating bypass lines (including bypass valves) of the HRSG to be steam purged can each be designed for a cleaning force ratio CFR of at least 1.1 or even at least 1.2. During commissioning, the gas turbine engine is loaded to base load in order to achieve the CFR desired and required to provide effective cleaning of the steam system.

[0022] When the overall steam purging procedure and calculations are well integrated during the initial design and concept process, the overall steam purging procedure and calculations can be greatly simplified. During the initial engineering and procurement phases of a project for constructing a new combined cycle power generation plant, engineers can calculate various steam purging scenarios to allow for sufficient CFR to be obtained in the HRSG and steam lines. In addition to other normal operating scenarios, the steam purging scenarios can be included in the bypass function specifications to allow the pipeline and bypass suppliers to size the bypass lines and bypass valves accordingly. Thus, the need for specific equipment for verifying the purging procedure can be limited.

[0023] To determine what steam bypass capacity should be for verifying steam purging, when the gas turbine engine is operating at base load on the steam bypass under the expected actual environmental conditions of the steam purging, it can be checked at what pressure each tubing section should operate to exceed the expected CFR when steam flow is available. For this purpose, normal environmental conditions are generally considered, and normal environmental conditions are usually acceptable.

[0024] In a preferred application of any of the above versions of the method, the HRSG may have multiple pressure levels (including a high pressure (HP) level, an intermediate pressure (IP) level, and a low pressure (LP) level) and a reheater. The steam turbine system may include an HP steam turbine, an IP steam turbine, and an LP steam turbine. The steam lines to be steam purged may at least include: an HP steam line for supplying HP steam from the HP level of the HRSG towards the HP steam turbine, an IP steam line connecting the IP level of the HRSG to the reheater, a hot reheat (HRH) line for supplying IP steam from the reheater towards the IP steam turbine, a cold reheat (CRH) line for receiving used HP steam from the HP steam turbine and supplying the used HP steam to the reheater, an operating HP bypass line arranged between the HP steam line and the CRH line, an operating HRH bypass line arranged between the HRH line and the condenser, and an operating LP bypass line arranged between the LP steam line and the condenser. Designing the permanent operating lines may then include sizing and arranging at least the HP steam line, the IP steam line, the HRH line, the CRH line, and the LP steam line, as well as the HP bypass line, the HRH bypass line, and the LP bypass line for a cleaning force ratio CFR of at least 1.1, preferably at least 1.2.

[0025] In any of the above embodiments, the method may further include: providing a modulating sacrificial valve trim to at least some of the bypass valves, namely the HP bypass valve, the HRH bypass valve, and the LP bypass valve, in the operating HP bypass line, the operating HRH bypass line, and the operating LP bypass line, the modulating sacrificial valve trim being designed to increase the flow coefficient (CV) capacity of the bypass valves to support a cleaning force ratio CFR of at least 1.2 for a single HRSG plant configuration and at least 1.03 for a multi-HRSG plant configuration.

[0026] The sacrificial valve trim may be installed in the bypass valves only during the verification of the purging procedure to prevent damage to the operating valve trim and to increase the flow coefficient capacity of the bypass valves. The sacrificial valve trim may have reduced durability and may be removed from the bypass valves again when the verification steam purging procedure is completed. The permanent valve trim included in the bypass valves for normal operation may be sized based on the maximum load case other than the steam purging situation and may have greater strength and durability.

[0027] In some embodiments, when designing the sacrificial valve internals, a margin of, for example, about 10% can be added to the required valve flow coefficient CV of the sacrificial valve internals to ensure that the required cleaning force ratio CFR can be achieved under the actual operating conditions in the field. For the HP bypass line, the sacrificial valve internals can be set to provide the maximum CV that the valve body can accommodate in order to be able to perform a verification purge under base load conditions. In some embodiments, the sacrificial valve internals can consist of a piston and a cage with an associated gasket, and the cage has, for example, an increased number and / or larger-sized holes to allow for a higher volumetric flow rate and velocity of the steam passing through it.

[0028] When designing the HP bypass line and the HP bypass valve, the bypass attemperating flow that may be required can also be considered. According to normal bypass attemperating control, the temperature setpoint of HP bypass attemperation can be set based on the expected CRH pressure, but during steam purging, the expected CRH pressure can be used for setting.

[0029] Any of the above embodiments of the method can further include: positioning the take-off connection of the operating HP bypass line, the operating HRH bypass line, and the operating LP bypass line as close as possible to the steam turbine system, very close to the control and isolation valve assemblies of the HP steam turbine, the IP steam turbine, and the LP steam turbine and exactly upstream of the control and isolation valve assemblies. "As close as possible" means reasonably close to the steam turbine system to avoid the bypass lines being affected by the turbine building, condenser type, etc. The bypass lines will not be installed in the HRSG area, especially not on the HRSG pipe racks, but installed closer to the steam turbine system. The HRH bypass line and the LP bypass line can be directly installed in the steam turbine area. The HP bypass line will not be directly installed in the steam turbine area, but as close as possible and reasonably close to the steam turbine area. The check valve on the CRH line and the downstream connection of the HP bypass line to the CRH line should also be positioned as close as possible to the HP steam turbine. In this way, a longer section of the steam delivery parts and the steam lines can be cleaned by steam purging.

[0030] In any of the above embodiments, the method can further include: installing target inserts at least in the HRH steam line and the LP steam line, and the target inserts are preferably in the form of mirrors or highly polished steel plates. The target inserts are configured and arranged to allow for on-line target inspection and monitoring of cleanliness under the steam temperature and pressure operating conditions during the verification purge procedure. The target inserts can visually show the impact of the debris entrained by the steam purging.

[0031] In any of the above embodiments, the method may further comprise: installing steam flow meters in relevant portions of the steam delivery components, steam pipelines, and operating bypass pipelines of the HRSG, and calculating the CFR in the relevant portions online based on the steam flow measurements of the steam flow meters during the verification of the steam purging procedure.

[0032] The type of the steam flow meter may be, for example, a Venturi tube or nozzle type. The CFR calculation may be included as part of the normal equipment control software for verifying the cleaning ratio during the verification purge.

[0033] Any of the above embodiments of the method may further comprise: providing inspection / cleaning ports in the non-steam-purged sections of the steam pipeline; and after completion of the verification purge procedure, inspecting and cleaning the non-steam-purged sections (if necessary). The cleaning may be performed, for example, by flushing with deionized water. This can ensure that all critical paths, dead legs, etc. are substantially free of contaminants.

[0034] In some advantageous embodiments of any of the above methods, T-joints may be provided to at least some of the branch point connections in the branch point connections of the HP bypass pipeline, HRH bypass pipeline, and LP bypass pipeline, the T-joints leading directly to the respective bypass pipelines without leading directly to the respective steam turbine sections, so as to reduce the accumulation of debris in the dead legs upstream of the respective steam turbine sections. This can save time for inspecting and cleaning the critical paths. Then some of the usually required inspection and cleaning ports may be omitted. The method may be particularly applicable to configurations without steam isolation valves and sections upstream of the steam isolation valves. In the case of the HP steam pipeline where the option of adding inspection flanges or ports is more challenging, this method may also be particularly interesting. In addition, recent studies have shown that the direct pipeline to the bypass can limit the corrosion of the steam turbine valves during long-term equipment operation.

[0035] Any of the above embodiments of the method may be further applied to a combined cycle power generation equipment including a multi-unit configuration, the multi-unit configuration including a single steam turbine system, a first unit including a first HRSG and a first gas turbine engine, and a second unit including a second HRSG and a second gas turbine engine. Then, the method may preferably comprise: independently performing the verification purge procedure between the units. Since there is no common section of the units, this can be easily achieved. Preferably, the verification purge procedures of the first unit and the second unit are performed one after another. In an advantageous embodiment, the verification purge procedure may be performed on one of the first unit and the second unit, while the dead legs are inspected and cleaned in the other unit after the verification purge procedure. This can save time for completing the pre-operation cleaning.

[0036] In some embodiments of the method applied to a combined cycle power generation device including a multi-unit configuration, the method may include: performing a verification purge in one of a first unit and a second unit, and using at least one bypass line and a bypass valve in the other unit to direct the verification steam therethrough. This can help avoid over-sizing the bypass valve in the bypass line.

[0037] As an alternative, a connection from the HP steam line to the HRH warming line can be used for a multi-unit device configuration so as not to over-size the HP bypass valve. During the verification steam purge, both the HP bypass line and the HP to HRH warming line can be used to reduce the HP bypass line pressure.

[0038] In some embodiments of any of the above methods applied to a combined cycle power generation device including a multi-unit configuration, in the case where the HP bypass valve may not be able to achieve a sufficient CFR on the HP steam line or may not be able to limit the unpurged sections of HP and CRH, a modified embodiment of the method may include: installing a temporary jumper with an optional throttling device from the HP steam turbine valve of the HP steam turbine to the check valve on the CRH line, and sizing the HRH bypass valve to allow a required CFR of at least 1.03 to be obtained on the HRH steam system. If necessary, a throttling device can be used on the temporary pipework to limit the CFR on the HP steam system. Only use limited temporary pipework common to two units of the multi-unit device configuration to avoid using the HP bypass lines and valves of the two units for the steam purge operation.

[0039] Furthermore, when using temporary pipework, the HP steam terminal thermostat (if used) can be designed to allow the HP steam to be temperature-controlled before entering the CRH steam line to obtain maximum steam purge conditions. When no HP terminal thermostat is available, a specific port can be provided on the HP steam line to allow connection of a temporary temperature control during the verification purge. In addition to these aspects, do not use such temporary pipework or equipment in each of the first unit and the second unit of the multi-unit configuration of the combined cycle power generation device.

[0040] According to another aspect of the present invention, to solve the above object, a combined cycle power generation device is provided, which includes: a gas turbine engine for generating power; a heat recovery steam generator (HRSG) fluidly connected to the gas turbine engine for receiving high-energy exhaust gas generated from the power generation in the gas turbine engine, and configured to generate steam from the high-energy exhaust gas; a steam turbine system fluidly connected to the HRSG via a steam pipeline for receiving the steam generated in the HRSG, and configured to generate additional power from the steam; a condenser and condensate system, the condenser being connected to the steam turbine system for condensing the used steam output from the steam turbine system, and the condensate system being used to return the condensate from the condenser to the HRSG; a permanent operation bypass pipeline fluidly connected between the steam pipeline and the condenser, and arranged to bypass the steam turbine system; and a control system for controlling the normal operation of the gas turbine system, the HRSG, the steam turbine system and the condenser to generate power under varying operating conditions, the control system being further configured to perform pre-operation cleaning on the water and steam systems in the combined cycle power generation device by: igniting the gas turbine engine and commissioning the gas turbine engine; when commissioning the gas turbine engine, performing a verification steam purging procedure including a steam purging operation, wherein steam is generated in the HRSG and the steam is purged through a part of a closed flow loop under high speed, temperature and cleaning force ratio conditions to clean the steam delivery parts of the HRSG and the steam pipeline connecting the HRSG to the steam turbine, wherein the steam is guided to bypass the steam turbine system via the operation bypass pipeline without using any temporary pipes, and is discharged to the condenser; and monitoring and verifying the cleanliness of the selected steam purged steam pipeline.

[0041] The combined cycle power generation device is designed to effectively and finally clean the pollutants in the water and steam systems in a short time, for example, after a newly installed or repaired power generation device, in parallel with commissioning the gas turbine system, to prepare for the normal operation of the power generation device, without any temporary pipes, installations and controls, and corresponding configurations and reconfigurations, thereby achieving the advantages described above in connection with the method of the present invention. The above additional embodiments of the method and the associated effects and advantages are equally applicable to the combined cycle power generation device. The most preferred embodiment of the combined cycle power generation device of the present invention is as follows:

[0042] The control system can be configured to perform a steam purging operation when operating a gas turbine engine at base load (i.e., maximum load conditions), and the operating tubing, steam lines, and operating bypass lines including bypass valves of the HRSG to be steam purged can each be designed for a cleaning force ratio CFR of at least 1.03, at least 1.1, or even at least 1.2.

[0043] In a preferred embodiment of any of the above types of combined cycle power generation equipment, the HRSG can have multiple pressure levels (including a high pressure (HP) level, an intermediate pressure (IP) level, and a low pressure (LP) level) and a reheater. The steam turbine system can include an HP steam turbine, an IP steam turbine, and an LP steam turbine. The steam lines can include: an HP steam line for supplying HP steam from the HP level of the HRSG towards the HP steam turbine, an IP steam line connecting the IP level of the HRSG to the reheater, a hot reheat (HRH) line for supplying IP steam from the reheater towards the IP steam turbine, a cold reheat (CRH) line for receiving used HP steam from the HP steam turbine and supplying the used HP steam to the reheater, an operating HP bypass line arranged between the HP steam line and the CRH line, an operating HRH bypass line arranged between the HRH line and the condenser, and an operating LP bypass line arranged between the LP steam line and the condenser. The sizes and arrangements of at least the HP steam line, IP steam line, HRH line, CRH line, and LP steam line, as well as the HP bypass line, HRH bypass line, and LP bypass line, can be set for a cleaning force ratio CFR of at least 1.03, at least 1.1, and preferably at least 1.2.

[0044] In a preferred embodiment of the combined cycle power generation equipment, at least some of the bypass valves among the HP bypass valve, HRH bypass valve, and LP bypass valve of the operating HP bypass line, operating HRH bypass line, and operating LP bypass line can be equipped with a modulating sacrificial valve internals for verifying the steam purging procedure, and the modulating sacrificial valve internals are designed to increase the flow coefficient CV capacity of the bypass valve so as to support a cleaning force ratio CFR of at least 1.2 for a single HRSG device and at least 1.03 for a multi-HRSG device. The sacrificial valve internals are installed to prevent damage to the operating valve internals during the verification of the purging procedure and to increase the flow coefficient capacity of the bypass valve, which may reduce durability in some cases. When the verification of the steam purging procedure is completed, the sacrificial valve internals can be removed from the bypass valve.

[0045] In any of the above-described embodiments of the combined cycle power generation equipment, the branch point connections for operating the HP bypass line, the HRH bypass line, and the LP bypass line may preferably be positioned as close as possible to the steam turbine system, i.e., as close as possible and reasonably close to the steam turbine system, farther from the HRSG area than from the steam turbine area, not on the HRSG pipe rack and not directly in the steam turbine area, but very close to the control and isolation valve assemblies of the HP steam turbine, the IP steam turbine, and the LP steam turbine and located exactly upstream of the control and isolation valve assemblies. The isolation valve (if any) on the CRH line and the downstream connection of the HP bypass line to the CRH line may also be positioned as close as possible to the HP steam turbine to allow steam purging of a longer section of the operating pipe material.

[0046] In any of the above-described embodiments of the combined cycle power generation equipment, for verifying the steam purging procedure, target inserts may be installed in the HRH steam line 49 and the LP steam line 41 and / or other steam delivery parts and lines, preferably in the form of mirrors or highly polished steam vanes, where the target inserts may be configured and arranged to allow on-line target inspection and monitoring of cleanliness under steam temperature and pressure operating conditions during the verification of the purging procedure.

[0047] In any of the above-described embodiments of the combined cycle power generation equipment, a steam flow meter may be installed in the relevant parts of the operating pipe material, steam lines, and / or bypass lines of the HRSG to be steam purged, and the control system may be configured to calculate the CFR in the relevant parts based on the steam flow measurement of the steam flow meter during the verification of the steam purging procedure. The calculated CFR in the relevant parts may be presented to the operator of the power generation equipment on the graphical interface of the control system 9 to allow the operator to verify whether the required CFR is achieved.

[0048] In any of the above-described embodiments of the combined cycle power generation equipment, inspection / cleaning ports may be provided in the non-steam-purged sections of the steam lines to provide access for inspecting and cleaning the non-steam-purged sections. These sections may be acid cleaned and hydrolyzed and inspected by a pipe mirror, a robotic camera, etc. before the gas turbine engine is then ignited for normal operation. The blind pipes around the steam turbine system may be inspected during and after the steam purging procedure. The debris accumulated in the blind pipes may be removed by flushing.

[0049] In any advantageous additional embodiment of any of the above-described combined cycle power generation devices, a T-junction may be provided to at least some of the branch point connections in the HP bypass line, the HRH bypass line, and the LP bypass line branch point connections, which T-junction goes straight through the corresponding bypass line without going straight through the corresponding steam turbine section, to reduce the accumulation of debris in the dead ends upstream of the corresponding steam turbine section. This can save time for inspection and cleaning of the critical path and allow some inspection / cleaning ports to be omitted. In addition, corrosion of the steam turbine valves during long-term equipment operation can be reduced.

[0050] In a preferred application of any of the above embodiments, the combined cycle power generation device may include a multi-unit configuration that includes a single steam turbine system, a first unit including a first HRSG and a first gas turbine engine, and a second unit including a second HRSG and a second gas turbine. In the multi-unit configuration, the control system may be configured to perform a verification purge procedure independently and one by one between the units. In particular, the control system may be configured to perform a verification purge procedure on one of the first unit and the second unit while inspecting and cleaning the dead ends in the other unit after the verification purge procedure.

[0051] In some embodiments of any of the above-described combined cycle power generation devices, in order not to oversize the bypass valve and / or to avoid installing sacrificial valve internals in the bypass valve, the control system may be configured to perform a verification steam purge procedure by using at least one bypass line and bypass valve in one of the first unit and the second unit to direct the verification steam flow therethrough.

[0052] As an alternative, a connection from the HP steam line to the HRH warming line may be used for a multi-unit device configuration in order not to oversize the HP bypass valve.

[0053] In some additional embodiments of the combined cycle power generation device, a temporary jumper may be installed between the HP steam turbine valve of the HP steam turbine and the check valve on the CRH line to direct the HP steam therethrough and avoid using the HP bypass line and the HP bypass valve. The size of the HRH bypass valve may be set to allow a CFR of at least 1.1 on the HP and HRH steam systems. These embodiments are particularly advantageous in applications where the HP bypass valve cannot achieve a sufficient CFR on the HP steam line or cannot limit the unpurged sections of the HP and CRH.

[0054] These and other advantages and features of the present invention will become more apparent from the following description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the claims at the end of the specification. The foregoing and other features and advantages of the aspects described herein will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0056] Figure 1 is a process flow schematic diagram of an embodiment of the invention for achieving pre - operation cleaning using a verified steam purge of the water and steam system in a combined cycle power generation plant with a single HRSG configuration;

[0057] Figure 2 is a process flow schematic diagram of an embodiment of the invention for achieving pre - operation cleaning using a verified steam purge of the water and steam system in a combined cycle power generation plant with a multi - HRSG configuration having isolation valves;

[0058] Figure 3 is similar to Figure 2 is a process flow schematic diagram of an alternative embodiment of a combined cycle power generation plant in a multi - unit configuration, which shows a verified flow path in the multi - HRSG configuration of the combined cycle power generation plant with a temporary jumper from the high - pressure steam turbine valve to the cold reheat pipeline; and

[0059] Figure 4 and Figure 5 is a process flow schematic diagram of a combined cycle power generation plant in a multi - unit configuration, which shows another embodiment of the verified steam purge procedure according to the invention using the bypass of two units to avoid over - sizing the bypass valve. Detailed Description

[0060] Now referring to the drawings, and particularly to Figure 1 , a combined cycle power generation plant 1 is provided, which may hereinafter be referred to simply as the power generation plant 1. The power generation plant 1 includes: a gas turbine engine 2 for generating power; a heat recovery steam generator (HRSG) 3 fluidly connected to the gas turbine engine 2 to receive high - energy exhaust gases generated from the generation of power in the gas turbine engine 2 and configured to generate steam from the high - energy exhaust gases; a steam turbine system 4 fluidly connected via a steam pipeline to the HRSG 3 to receive the steam generated in the HRSG and configured to generate additional power from the steam; a condenser 6 coupled to the steam turbine system 4 for condensing the used steam output from the steam turbine system 4 and coupled to a condensate system 7 for returning the condensate from the condenser 6 to the HRSG 3; a generator 8 driven by the steam turbine system 4 and the gas turbine engine 2 to generate electricity; and a control system that is in Figure 1is schematically shown in the form of a box 9 and is configured to control the normal operation of the gas turbine engine 2, the HRSG 3, the steam turbine system 4, and the condenser 6 for power generation under varying operating conditions. As further explained below, the control system 9 is further configured to perform pre-operational cleaning of the water and steam systems in the combined cycle power generation plant 1.

[0061] The gas turbine engine 2 includes: a compressor 10 that receives air through an inlet 11 and compresses the air; a combustor 12 that receives a flow of compressed air from the compressor 10 and fuel (e.g., natural gas) from a fuel source (not shown), mixes the compressed air and fuel, and combusts the mixture to produce high-energy exhaust gases; and a turbine section 13 that receives the flow of high-energy exhaust gases from the combustor 12. In the turbine section 13, the high-energy exhaust gases expand, and the thermal energy of the exhaust gases is converted into kinetic energy to drive a shaft 14. The mechanical power of the shaft 14 drives the compressor 10 and an external load (such as an electric generator 8, etc.). The flow of high-energy exhaust gases is delivered from the turbine section 13 to the HRSG 3 through an exhaust duct 16. In the illustrated exemplary embodiment of the power generation plant 1, the gas turbine engine 2, the steam turbine system 4, and the generator 8 are arranged on a single shaft 14, but other configurations with a separated shaft and external load may also be used.

[0062] In the illustrated exemplary embodiment of the power generation plant 1, the steam turbine system 4 includes a high-pressure (HP) steam turbine 17, an intermediate-pressure (IP) steam turbine 18, and a low-pressure (LP) steam turbine 19, which have multiple steam admission points at different pressures. The LP steam turbine 19 is coupled to the condenser 6 to discharge the used steam that has been used for power generation to the condenser 6.

[0063] The HRSG 3 is a counterflow heat exchanger that is arranged to use the high-energy exhaust gases received from the gas turbine engine 2 via the exhaust duct 16 to heat the feed water passing through the HRSG 3. The HRSG 3 is associated with the steam turbine system 4 and includes corresponding multiple pressure stages (including an HP stage 21, an IP stage 22, and an LP stage 23) and a reheater 24 to generate steam at various pressures and temperatures. The steam is used as the steam supply to the corresponding stages of the steam turbine system 4.

[0064] Each of the HP stage 21, IP stage 22, and LP stage 23 of the HRSG 3 typically may include one or more drums, economizers, evaporators, OT (once-through) sections, and / or superheaters. For example, the HP stage 21 may include an HP drum 26, an HP economizer 27, an HP evaporator 28, and one or more HP superheaters 29. Similarly, the IP section 22 may include an IP drum 31, an IP economizer 32, an IP evaporator 33, and an IP superheater 34. The LP section 23 may include an LP drum 35, an LP economizer 36, an LP evaporator 37, and an LP superheater 38. The economizers, evaporators, and superheaters of the HP stage 21, IP stage 22, and LP stage 23 of the HRSG 3 and the reheater 24 are arranged as tubes or tube bundles inside the HRSG 3 such that the high-energy exhaust gas passing through the HRSG 3 can transfer heat to the fluid (feed water or steam) circulating through the tubes or tube bundles. Although the multi-pressure HRSG 3 with the Figure 1 configuration shown is a preferred embodiment of the steam generation facility in the combined cycle power generation device 1, other configurations of HRSGs and other steam generation facilities, such as different types of steam boiler plants, etc., may be used.

[0065] As can be seen in Figure 1 , the power generation device 1 includes a plurality of steam pipelines arranged to supply the steam generated in the HRSG 3 to the steam turbine system 4. For example, the plurality of steam pipelines may include: an LP steam transfer pipeline 39 fluidly connected between the LP drum 35 and the LP superheater 38; and an LP steam pipeline 41 fluidly connected between the LP superheater 38 and the LP steam turbine 19 to supply LP steam to the LP steam turbine. The IP stage 22 of the HRSG 3 may include: an IP steam transfer pipeline 42 fluidly connected between the IP drum 31 and the IP superheater 34; and an IP steam pipeline 43 fluidly connecting the IP superheater 34 to the reheater 24. If needed, another steam pipeline (not numbered in Figure 1 ) may be used to transfer IP steam from the IP drum 31 back to the LP drum 35. The HP stage 21 of the HRSG 3 may include: an HP steam transfer pipeline 44 fluidly connected between the HP drum 26 and the HP superheater 29; an HP steam transmission pipeline 46 fluidly connecting different sections (if any) of the HP superheater 29; and an HP steam pipeline 47 fluidly connected between the HP superheater 29 and the HP steam turbine 17 to supply HP steam to the HP steam turbine.

[0066] In addition, the reheater 24 may include: a reheater steam transfer line 48 that fluidly connects different sections (if any) of the reheater 24; a hot reheat (HRH) line 49 that is fluidly coupled between the output of the reheater 24 and the input of the IP steam turbine 18 for supplying IP steam to the IP steam turbine; and a cold reheat (CRH) line 51 that is fluidly coupled at one end to the input of the reheater 24 and the IP steam line 43 and at the other end to the output of the HP steam turbine 17 for receiving the used HP steam from the HP steam turbine 17. At least some of the steam lines 39 to 51 may include isolation valves and / or control valves for blocking or regulating the steam flow therethrough.

[0067] The power generation device 1 further includes a permanent bypass system that includes a plurality of permanently operating steam bypass lines that can be used during normal operation (such as during load rejection) to bypass the steam generated in the HRSG 3 around the steam turbine system 4 and supply it to the condenser 6. In particular, the plurality of operating bypass lines may include an HP bypass line 52, an HRH bypass line 53, and an LP bypass line 54. The HP bypass line 52 is fluidly coupled between the HP steam line 47 and the CRH line 51 and includes an HP bypass valve 55 mounted thereon to control the HP bypass steam flow therethrough. The HRH bypass line 53 is fluidly coupled between the HRH line 49 and the condenser 6 and includes an HRH bypass valve 56 mounted thereon to control the IP bypass steam flow therethrough. The LP bypass line 54 is fluidly coupled between the LP steam line 41 and the condenser 6 and includes an LP bypass valve 57 mounted thereon to control the LP bypass steam flow therethrough.

[0068] The condenser 6 is a large heat exchanger that is coupled to the steam turbine system 4 (specifically the LP steam turbine 19) to receive the used steam therefrom and is arranged to cool the used steam to condense it into water. Although several types of condensers are known, a common design includes a large number of small-diameter tubes 58 through which cooling water passes. The steam condensate from the condenser may fall into a hot well 59 located at the bottom of the condenser and / or may be provided to a condensate tank 60 (see Figure 2 ). The condensate system 7 includes a condensate pump 61 and a condensate line 62. The condensate pump 61 returns the condensate from the condenser 6 to the HRSG 3 via the condensate line 62. A coarse filter (not shown) may be arranged on the suction side of the condensate pump 61 to remove particulate contamination from the condenser hot well 59 or the condensate tank 60 ( Figure 2)Removed from the steam condensate supplied to the condensate pump 61, thereby preventing damage to the condensate pump 61 and other components of the condensate system 7. Although Figure 1 a liquid-cooled deaerating condenser is shown in the embodiment of Figure 2 the air-cooled condenser schematically shown in the embodiment of

[0069] During normal operation, the gas turbine engine 2 generates mechanical power, which is converted into electrical power by the generator 8. The steam turbine system 4 can generate additional power from the steam received from the HRSG 3. The used steam from the steam turbine system 4 is condensed in the condenser 6 and returned to the HRSG 3 via the condensate system 7. Depending on the load requirements, one or more of the HP steam turbine 17, IP steam turbine 18, and / or LP steam turbine 19 may not be used. Then, the operating HP bypass line 52, operating HRH bypass line 53, and operating LP bypass line 54 can be used to bypass the corresponding steam turbine sections. Control and stop valve assemblies 63, 64, 65 are arranged at the inlets of the HP steam turbine 17, IP steam turbine 18, and LP steam turbine 19 to stop, open, and control the steam flow to the corresponding steam turbine stages. The isolation valve 66 is arranged on the CRH line 51 downstream of the outlet of the HP steam turbine 17 (e.g., arranged in the CRH line section 71).

[0070] During the manufacture and assembly of the combined cycle power generation plant 1 or during renovation or repair, contaminants (such as mud, sand, dust, welding spatter, chips, welding electrode residues, debris, and other particulate contaminants) may remain in the system. To prevent contamination and damage to the steam turbine components during operation, such contaminant particles must be removed from all steam delivery and water delivery equipment parts of the HRSG 3, condenser 6, and condensate system 7, the steam lines connecting the HRSG 3 to the steam turbine system 4 and condenser 6, and the operating bypass lines 52, 53, 54. For this purpose, a method for pre-operational cleaning of the water and steam systems in a combined cycle power generation plant is provided. The pre-operational cleaning method of the present disclosure will be described below in conjunction with Figure 1 the combined cycle power generation plant 1 shown, but the pre-operational cleaning method can be applied to any other power generation plant including a steam generation facility.

[0071] As provided herein, the pre-operation cleaning method begins with performing a pre-operation initial flushing and chemical cleaning operation on the water and steam systems of the constructed combined cycle power generation device 1. Treated deionized water can be used to flush substantially all parts and pipelines (including the HRSG drum, economizer, superheater, and reheater, steam pipelines, auxiliary steam pipelines, bypass pipelines, feedwater pipelines, and condensate systems) that convey steam or steam condensate to remove contaminants. In addition, additional chemical cleaning steps can be performed, including one or more of hot degreasing, acid cleaning, passivation, and rinsing. The low points and HRSG collectors can be inspected and hydrolyzed if necessary to remove particulate contaminants. Finally, a dry air protection step can be carried out subsequently.

[0072] When the chemical cleaning operation is completed, as the next step of the pre-operation cleaning method, a verified steam purge procedure is performed. According to this method, the verified steam purge procedure to the condenser is performed when commissioning the gas turbine engine.

[0073] Therefore, first, the gas turbine engine 2 is ignited, and the commissioning of the gas turbine engine 2 is started. Normal gas turbine engine commissioning activities will drive a normal schedule in which the gas turbine engine 2 is in bypass operation, and the bypass operation includes full speed no load (FSNL) operation, testing the safety valve of the HRSG 3, and loading the gas turbine engine 2 to the base load (i.e., the maximum rated load) for combustion adjustment.

[0074] The verified steam purge procedure is performed in parallel with the commissioning of the gas turbine engine 2. The verified steam purge procedure includes a steam purge operation in which steam is generated in the HRSG 3 using the high-energy exhaust gas from the gas turbine engine 2, and the steam is purged through the steam delivery section of the closed flow loop at high speed, temperature, and cleaning force ratio conditions to clean the steam delivery parts. The closed flow loop is formed by the HRSG 3, the tubing connecting the HRSG 3 to the steam turbine system 4, bypass pipelines 52, 53, 54, the condenser 6, and the condensate system 7. When doing so, the verified steam is directed to bypass the steam turbine system 4 via a permanent bypass system and discharged to the condenser 6. The permanent bypass system includes a permanently operating HP bypass pipeline 52, a permanently operating HRH bypass pipeline 53, and a permanently operating LP bypass pipeline 54. The condensate generated in the condenser 6 is cleaned if necessary and returned to the HRSG 3, thereby forming a closed-loop circuit. The steam-purged steam pipelines of the closed-loop circuit of the verified steam purge are indicated by thicker solid lines in Figure 1 The verified steam purge procedure further includes monitoring and verifying the cleanliness of the steam-purged steam pipelines in parallel with the steam purge.

[0075] The combination of the verification steam purge to the condenser with the parallel execution simultaneous to the normal gas turbine engine commissioning presents various advantages. The power generation plant 1 will start up in its normal configuration without any temporary controls and without the need for any temporary tubing that would otherwise be required only for the verification steam purge procedure and would not be used during normal operation. Instead, the permanent operation HP bypass line 52, the permanent operation HRH bypass line 53, and the permanent operation LP bypass line 54 will be used for the verification steam purge to the condenser 6 in the present document. Since steam and water circulate in a closed loop, the consumption of deionized water can be limited. During the steam purge procedure, there is no noise and visual pollution, and the procedure is emission compliant. Additionally, the normal gas turbine engine commissioning is carried out in parallel, so that the ignition hours and fuel consumption for implementing the procedure can also be reduced. There are no safety issues because the power generation plant 1 is in normal operation. Effective cleaning can be achieved using thermal cycling and high temperatures, and the steam quality required for normal operation can be achieved within a short period of time and in a cost-effective manner.

[0076] In order to achieve the required disturbance factor and cleaning efficiency in the steam purge procedure while avoiding damage to the equipment to be steam purged, it is preferably already integrated and taken into account in the initial design or concept phase of the project for constructing a new power generation plant. The steam purge operation will be carried out when the gas turbine engine is operating at base load, and all the operating tubing of the HRSG 3, the steam lines 39 to 51, the bypass lines 52 to 54, and the bypass valves 55 to 57 (which will be effectively steam purged) are thus each designed for such operating conditions and for a cleaning force ratio CFR of at least 1.1 or even at least 1.2. The cleaning force ratio CFR can be calculated as

[0077]

[0078] where Q c is the calculated flow rate during cleaning, Q max is the maximum load flow rate, (PV) c is the pressure - specific volume product during cleaning, (PV) max is the pressure - specific volume product at the maximum load flow rate, P max is the pressure at the maximum load flow rate, and P c is the pressure during cleaning. Therefore, under the maximum rated operating conditions, the steam delivery parts to be steam purged must meet more stringent requirements than the corresponding parts of a conventional power generation plant.

[0079] To determine what capabilities of the equipment in the steam and water systems should be targeted for the steam purging procedure, each pipe section should be examined to determine at what pressure it should operate to exceed the expected CFR when the gas turbine system is operating at base load under the expected actual ambient conditions for the steam purge. Typically, normal ambient conditions can be considered. At Figure 1 In the preferred embodiment of the power generation equipment shown, the size and arrangement of at least the bodies of the steam lines 39 to 51, the bypass lines 52 to 54, and the bypass valves 55 to 57 are set for a cleaning force ratio CFR of at least 1.1. More preferably, the size and arrangement of at least some of these steam lines can be set for a CFR of at least 1.2.

[0080] Some preparatory work can be carried out to allow for an effective and safe verification of the steam purging procedure. In particular, a modulating sacrificial valve internals (not shown) can be installed in at least some of the HP bypass valve 55, the HRH bypass valve 56, and the LP bypass valve 57 in the operation of the HP bypass line 52, the operation of the HRH bypass line 53, and the operation of the LP bypass line 54 to prevent damage to the operating valve internals and to increase the flow coefficient (CV) capacity of the bypass valves when needed. The permanent valve internals will be sized based on the maximum load case (except for the steam purge case) and for good durability. In contrast, the sacrificial valve internals are specifically designed for an increased or maximum flow coefficient CV. Durability is a secondary objective.

[0081] The sacrificial valve internals can be designed to support a cleaning force ratio CFR of at least 1.2 for a single HRSG equipment configuration and at least 1.03 for a multi-HRSG equipment configuration. The required flow coefficient CV of the sacrificial valve internals can be calculated based on the estimated conditions, and a margin of, for example, 10% to 20% can be added to the required CV to ensure that the required CFR can be achieved under the actual operating conditions in the field. For the HP bypass valve 55 that is exposed to the maximum load during the steam purging procedure, the sacrificial valve internals can preferably be designed to provide the maximum CV that the valve body can accommodate.

[0082] In a preferred embodiment, the installed modulating sacrificial valve internals can consist of a piston and a cage with an associated gasket, and the cage has an increased number of holes or larger holes to allow for a higher volumetric flow rate and flow velocity of the steam passing through it. After the steam purging procedure is completed, the sacrificial valve internals are removed again and replaced with the final operating valve internals.

[0083] Steam purging implemented during bypass operation may require that the bypass attemperation flow (if any) be taken into account for planning the verification steam purging procedure. For example, in accordance with normal bypass attemperation control, the temperature setpoint of the HP bypass line 52 may be set based on the expected pressure in the CRH line 51, but during verification of steam purging, the expected CRH line pressure may be used for setting.

[0084] To allow for cleaning of longer sections of the steam delivery tubing, the branch points of the permanently operating HP bypass line 52, the permanently operating HRH bypass line 53, and the permanently operating LP bypass line 54 are positioned as close as possible to the steam turbine system 4. This means that they are positioned reasonably close to the steam turbine system 4, so as to be in the vicinity of the area of the steam turbine system 4, but at a distance sufficient to avoid the bypass lines 52, 53, 54 being affected by the steam turbine building, the type of condenser 6, and its operation. The branch points of the HP bypass line 52, the HRH bypass line 53, and the LP bypass line 54 will be positioned very close to and immediately upstream of the steam control and isolation valve assemblies 63, 64, 65. The HP bypass line 52, the HRH bypass line 53, and the LP bypass line 54 should not be installed in the area of the HRSG 3, and in particular should not be installed on the HRSG pipe rack. The HRH bypass line 53 and the LP bypass line 54 extend directly to the condenser 6 and are generally installed close to the condenser 6 in the steam turbine area. The HP bypass line 52 should not be installed directly in the steam turbine area, but should be positioned as close as possible and reasonably close to the steam turbine area. The check valve 66 on the CRH line 51 and the downstream connection of the HP bypass line 52 to the CRH line 51 are also positioned as close as possible to the HP steam turbine 17.

[0085] To allow for targeted inspection and monitoring of cleanliness under steam temperature and pressure operating conditions during verification of the purging procedure, target inserts are installed in relevant parts of the steam delivery tubing. In particular, a first target insert 67 is installed in the HRH line 49 slightly upstream of the HRH bypass line 53 and the IP control and isolation valve assembly 64, and a second target insert 68 is installed in the LP steam line 41 slightly upstream of the LP bypass line 54 and the LP control and isolation valve assembly 65.

[0086] The target inserts 67, 68 preferably use mirrors or highly polished metal plates constructed of steel that are capable of withstanding the maximum steam conditions and forces of the respective steam flows in the HRH steam line 49 and the LP steam line 41. The target plates of the target inserts 67, 68 are impacted by debris entrained in the steam flow during verification of the steam purging procedure and will visually show the presence of particulate contamination entrained in the steam flow by the impact of particles on the target (metal or mirror) plates.

[0087] Additionally, in the present method for validating steam purging, steam flow meters (not shown) may also be installed in the operating pipe materials of the HRSG 3, in the relevant portions of the steam pipelines 39 to 51, and in the bypass pipelines 52 to 54 to measure the flow rate of steam purging in these portions. The steam flow meter ( Figure 1 not shown) may be, for example, of the venturi tube or nozzle type. Then, the cleaning force ratio CFR in the relevant portions can be calculated online based on the steam flow rate measurement results received from the steam flow meter during the validation of the purging procedure. In particular, the CFR calculation can be included as part of the normal equipment control software of the control system 9 for validating the cleaning force ratio during the validation of the steam purging procedure. The calculated CFR value can be presented to the operator of the power generation equipment 1 via a suitable graphical interface during the validation of the steam purging procedure to facilitate monitoring and verification of meeting the required steam purging conditions.

[0088] The method for performing pre-operation cleaning may further include: providing inspection / cleaning ports ( Figure 1 not shown) in the non-steam-purged sections of the steam pipelines, and inspecting and cleaning the non-steam-purged sections after completion of the validation purging process. The non-steam-purged sections are indicated by thicker dashed lines in Figure 1 (and other figures), and specifically include: the non-purged HP steam pipeline section 69 located between the branch point connection of the HP bypass pipeline 52 to the CRH pipeline 51 and the HP control and isolation valve assembly 63; the non-purged HRH pipeline portion 70 located between the branch point connection of the HP bypass pipeline 53 to the condenser 6 and the HP control and isolation valve assembly 64; the non-purged CRH pipeline portion 71 located between the downstream connection of the HP bypass pipeline 52 to the CRH pipeline 51 and the check valve 66 at the outlet of the HP steam turbine 17; and the non-purged LP steam pipeline portion 72 located between the branch point connection of the LP bypass pipeline 54 to the condenser 6 and the LP control and isolation valve assembly 65.

[0089] The inspection / cleaning ports in the non-steam-purged sections 69 to 72 are provided at appropriate positions to facilitate easy inspection and cleaning. Inspection can be performed using a borescope or a robot equipped with a camera, and residual contaminants in the critical portions can be removed by flushing or other suitable means. Other inspection / cleaning ports can be provided to facilitate access to other pipe material portions, thereby allowing inspection and cleaning of blind pipes, drain ports, etc.

[0090] In some additional embodiments of the combined cycle power generation equipment 1, in order to make the pre-operation cleaning method more effective, at least some of the branch point connections in the HP bypass pipeline 52, the HRH bypass pipeline 53, and the LP bypass pipeline 54 can be achieved through a T-shaped connection part (not shown). The T-shaped connection part leads directly to the corresponding bypass pipeline 52, 53, or 54, rather than directly to the corresponding steam turbines 17, 18, or 19. This arrangement facilitates reducing the accumulation of debris in the blind pipes upstream of the corresponding steam turbines 17, 18, or 19, and can save the time for inspecting the critical path and cleaning the dust therein. Then it may not be necessary to inspect and clean the ports, and they can be discarded. This option is preferably applicable to configurations without steam isolation valves or the sections upstream of the steam isolation valves, and may be particularly interesting in the case of HP steam where adding inspection flanges may be more challenging. Advantageously, it has been found that the straight pipelines of the bypass pipelines can also limit the corrosion of the steam turbine valves during long-term equipment operation.

[0091] Now referring to Figure 2 , a schematic diagram of a combined cycle power generation equipment 1' including a multi-unit configuration is shown. In Figure 2 the exemplary embodiment shown, the power generation equipment 1' includes a single steam turbine system 4, a first unit 73 including a first HRSG 3a and a first gas turbine engine 2a, and a second unit 74 including a second HRSG 3b and a second gas turbine engine 2b. The relevant components of the first unit 73 are shown using the corresponding reference numerals with an additional "a" in Figure 1 , while the corresponding components of the second unit 74 are indicated with an additional "b".

[0092] As can be seen in Figure 2 , the method for pre-operation cleaning of the water and steam systems in the combined cycle power generation equipment 1' can be advantageously performed independently for each of the first unit 73 and the second unit 74 from the other unit. Similarly here, the steam pipelines purged with steam are indicated by thicker solid lines in Figure 2 , while the sections not purged with steam are indicated by thicker dashed lines. The sections not purged with steam extend from the bypass branch points all the way to the steam turbine valves. All sections not purged with steam need pre-cleaning, inspection, and verification after chemical cleaning. The part immediately upstream of the steam isolation valve may accumulate debris during the verification steam purge and may require post-cleaning (assuming the steam isolation valve is closed during the verification steam purge to avoid the accumulation being transferred to the part downstream of the steam isolation valve).

[0093] The verification purge procedures for the first unit 73 and the second unit 74 can be carried out simultaneously, but more preferably sequentially (i.e., one after another). Similarly, the verification steam purge operations for each of the first unit 73 and the second unit 74 do not require temporary tubing or temporary controls. Instead, only the permanent operating steam lines (including the bypass lines 52a, 52b, 53a, 53b, 54a, 54b) can be used for the steam purge procedure to the condenser 6 carried out in parallel with the normal commissioning of the gas turbine engines 2a, 2b. Figure 2 The condenser 6 in [description] is shown as an air-cooled condenser, but it should be understood that the condenser can also be a water-cooled condenser or any other type of condenser, such as a direct condenser (jet condenser).

[0094] In some preferred embodiments, the verification purge procedure can be carried out on one of the first unit 73 and the second unit 74, while in the other unit, the blind tubes and other critical paths are inspected and post-cleaned after the verification purge procedure. Since there is usually no common section, the steam purge, inspection, and post-cleaning procedures can be carried out independently for each of the first unit 73 and the second unit 74.

[0095] In Figure 2 In the multi-unit configuration of the combined cycle power generation equipment 1' shown, the first unit 73 and the second unit 74 are fluidly connected to each other through the communication line 76. The communication line connects the LP steam lines 41a, 41b, the HRH lines 49a, 49b, and the HP steam lines 47a, 47b together downstream of the branch point connections of the respective HP bypass lines 52a, 52b, the HRH bypass lines 53a, 53b, and the LP bypass lines 54a, 54b. The communication line 76 is not included in the verification steam purge procedure. Isolation valves 77a, 77b are integrated slightly downstream of the respective branch point connections of the bypass lines 52a, 52b, 53a, 53b, 54a, 54b to block the communication line 76 during the verification steam purge procedure, so that the steam purge can be directed to the condenser 6 via the bypass lines 52a, 52b, 53a, 53b, 54a, 54b and prevent potential contamination of those connection / common lines during the verification steam purge. After chemical cleaning and before verification steam purge, the tubing sections located downstream of the isolation valves 77a, 77b, including the communication line 76 up to the steam turbines 17, 18, 19, are jet-cleaned with high-pressure water and comprehensively (100%) inspected and verified.

[0096] In addition to providing two units 73, 74 and the communication line 76, the configuration of the power generation equipment 1' (especially the configuration of the steam turbine system 4 and each unit 73, 74) corresponds to Figure 1the configuration of the power generation device 1 (in particular the combination of the steam turbine system 4 and the gas turbine engine 2 and the HRSG 3) in the embodiment. The operation of these units and in particular the method of pre-operational cleaning of the water and steam systems in the combined cycle power generation devices 1 and 1' also basically correspond to each other, such that the above descriptions of the configuration and the pre-operational cleaning method and the associated technical effects and advantages also apply to Figure 2 the embodiment.

[0097] Now referring to Figure 3 it shows a schematic view of a modification of the embodiment of the power generation device 1' of Figure 2 . The entire description of the embodiment of Figure 2 in combination with the description of the embodiment of Figure 1 should also apply to Figure 3 the embodiment, except for the differences mentioned below. Figure 2 and Figure 3 the same components in the embodiments of

[0098] Figure 3 the embodiment are indicated by the same reference numerals. Figure 2 The embodiment of differs from the embodiment of basically in that a temporary jumper 78 is installed from the HP control and isolation valve assembly 63 of the HP steam turbine 17 to the check valve 79 on the common CRH pipeline 81, and the common CRH pipeline is located upstream of the branch point connection of the CRH pipelines 51a, 51b of the first unit 73 and the second unit 74. The temporary jumper 78 allows the steam flow to be directly guided from the HP steam pipelines 47a, 47b to the CRH pipelines 51a, 51b through the temporary jumper 78 during the verification of the steam flow procedure, without using or reducing the use of the HP bypass pipelines 52a, 52b. This embodiment is advantageous in applications where the HP bypass valves 55a, 55b cannot achieve sufficient CFR on the HP pipeline or cannot limit the unpurged sections of the HP steam pipelines 47a, 47b and the CRH pipelines 51a, 51b. The sizes of the HRH bypass valves 56a, 56b are set to allow the correct CFR to be achieved on the HP and HRH steam pipelines.

[0099] In order not to overheat the CRH pipelines 81, 51a, 51b and to control the temperature of the steam flowing through the CRH pipelines, an HP steam terminal thermostat (not shown) can be designed and arranged to allow the HP steam to be temperature-controlled before entering the common CRH pipeline 81 to obtain the maximum steam purging conditions. When no HP terminal thermostat is available, specific ports can be planned on the HP steam pipe material to allow the connection of a temporary thermostat during the verification of the purge. All the other aspects mentioned above still apply.

[0100] Figure 4 and Figure 5An embodiment of the combined cycle power generation device 1' is shown in a modified schematic process flow representation. Generally, Figure 2 and the configuration of the power generation device shown in Figure 4 and Figure 5 corresponds to the configuration of the power generation device 1' shown in Figure 2 The same reference numerals are assigned to the same components in Figure 4 and Figure 5 and the same components in Figure 2 and generally the description of the embodiment of Figure 2 above also applies to the embodiments shown in Figure 4 and Figure 5 In this device configuration, only one of the HRSGs 3a or 3b is heated to generate steam, while the other HRSG will be in standby.

[0101] In Figure 4 and Figure 5 's embodiments, only a part of the verification steam purging procedure is slightly modified so as not to oversize the bypass valves (especially the HP bypass valves 55a, 55b) in the first unit 73 and the second unit 74. To this end, when the verification steam purging procedure is performed in one of the first unit 73 and the second unit 74, at least one bypass line and bypass valve are used in the other unit 74 or 73 to direct at least a part of the verification steam flow through it, so that the volumetric flow rate of the steam can be reduced in the bypass valve. The verification steam flow is also indicated by a thicker solid line in Figure 4 and Figure 5 .

[0102] In Figure 4In the scenario shown, in the first unit 73, verification steam is provided from the HRSG 3a through the HP superheater 29a to the branch point connection of the HP bypass line 52a, where the verification steam flow is split into two parts. The first part of the verification steam flow passes through the HP bypass line 52a and the HP bypass valve 55a and is directed to the reheater 24a through the CRH line 51a. The second part of the verification steam purge is diverted through the communication line 76a of the communication line 76 to the high-pressure bypass line 52b of the second unit 74, and this communication line connects the HP steam lines 47a, 47b of the two units 73, 74 together. The second part of the verification steam flow then passes through the HP bypass line 52b and the HP bypass valve 55b, the CRH line 51b, and another common communication line 76b of the communication line 76 and is directed back to the CRH line 51a of the first unit 73 to be mixed with the first part of the verification steam flow and is provided to the reheater 24a of the first unit 73. To allow this verification steam flow, all the control and isolation valves in the HP steam lines 47a, the common communication line 76a, the CRH lines 51a, 51b, and the common communication line 76b need to be opened. Then, the combined verification steam flow is directly discharged from the reheater 24a to the condenser 6 via the HRH line 49a and the HRH bypass line 53a of the first unit 73.

[0103] Similarly, during the verification steam flow procedure, the HP steam flow applied to the second unit 74 can be controlled such that the HP steam flow is split and directed through the two HP bypass lines 52a, 52b, the CRH lines 51a, 51b, and the common communication lines 76a, 76b of the two units 73 and 74, and then recombined and directly provided to the condenser 6 through the reheater 24b and the HRH bypass line 53b of the second unit 74.

[0104] In Figure 4 the example shown, the verification steam purge procedure is not performed independently between the first unit 73 and the second unit 74, but can reduce the requirements for the HP bypass lines 52a, 52b and the HP bypass valves 55a, 55b.

[0105] In Figure 5In the modified process flow shown, HP steam from the HRSG 3a of the first unit 73 passes through the HP steam line 47a and is directed to the reheater 24a via the HP bypass line 52a and the HP bypass valve 55a. A first portion of the verified steam flow then passes directly from the reheater 24a to the condenser 6 via the HRH line 49a, the HRH bypass line 53a, and the HRH bypass valve 56a of the first unit 73. A second portion of the verified steam flow is diverted in the HRH line 49a located downstream of the reheater 24a and is directed via the common connection line 76c of the connection line 76 to the HRH line 49b of the second unit 74. The second portion of the verified steam flow can then be discharged directly to the condenser 6 via the HRH bypass line 53b and the HRH bypass valve 56b. Thus, the verified steam flow can be split and passed through the HRH bypass lines and bypass valves of both the first unit 73 and the second unit 74, thereby reducing the sizing requirements imposed on the HRH bypass lines and the HRH bypass valves to achieve the required CFR.

[0106] The technical effects and advantages of the method for pre - operating cleaning of the water and steam system in a combined cycle power generation device according to the present invention and the corresponding combined cycle power generation device at least include the following technical effects and advantages: The power generation device can be started according to the normal configuration without temporary control, thus providing an easy start - up sequence. During the initial commissioning of the power generation device, effective cleaning can be achieved at high heat cycles and high temperatures when the power generation device is operating at full load (base load) of the gas turbine engine. The steam quality can be quickly achieved through condenser cleaning and closed - loop operation at higher loads. Generally, no temporary pipes and temporary control are required to perform the verified steam purge procedure. The ignition hours and the consumption of natural gas or other fuel gases can be limited. The consumption of de - ionized water can also be limited. Normal gas turbine and generator commissioning can be performed in parallel with the verified purge, with only limited downtime for re - configuration. The remaining inspections and cleaning of the critical path require very little time. There are no safety issues as the equipment is in normal operation and there is no noise and visual pollution. The gas turbine exhaust emissions can be reduced because the steam purge is performed above the minimum environmental load. Since the gas turbine engine is already operating at base load, the selective catalytic reduction (SCR) catalyst can be directly installed after the verified steam purge during the interruption of the steam purge for inspection and final cleaning, which provides maximum protection against the toxicity of the catalyst from the grease and dust in the gas turbine engine and HRSG air duct flow and eliminates the requirement for further downtime during the hot commissioning. In a multi - unit configuration of a combined cycle power generation device, the verified steam purge procedure can be performed independently for each unit. Alternatively, the verified steam purge procedure in the two units can be performed in a combined manner and / or using short lengths of temporary jumpers to allow for a reduction in the requirements for the bypass valves used.

Claims

1. A method for pre-operation cleaning of a water and steam system in a combined cycle power plant (1, 1'), the combined cycle power plant comprising a gas turbine engine (2), a steam turbine system (4), a condenser (6) and a heat recovery steam generator HRSG (3), the method comprising: performing a pre-operation initial flushing and chemical cleaning operation on the water and steam systems of the finally constructed combined cycle power plant (1, 1'); Ignite the gas turbine engine (2) and debug the gas turbine engine (2); performing a verification steam purge procedure including a steam purge operation when commissioning the gas turbine engine (2), wherein steam is generated in the HRSG (3) and purged through a portion of a closed flow loop under high velocity, temperature and cleaning force ratio conditions for cleaning steam transport parts of the HRSG (3) and steam lines (39 to 51) connecting the HRSG (3) to the steam turbine system (4), wherein the steam is directed to bypass the steam turbine system (4) via an operating bypass line (52 to 54) without using any temporary piping and is discharged to the condenser (6); and Monitor and verify the cleanliness of selected steam purged steam lines (39 to 54).

2. The method according to claim 1, wherein the steam purging operation is performed when the gas turbine engine (2) is operated at base load; and wherein the steam conveying parts of the HRSG (3) to be steam purged, the steam lines (39 to 51) and the operating bypass lines (52 to 54) including bypass valves (55 to 57) are each designed for a cleanliness force ratio (CFR) of at least 1.

1.

3. The method according to claim 1, wherein the HRSG (3) has a plurality of pressure stages and a reheater (24), the plurality of pressure stages comprising a high pressure HP stage (21), a medium pressure IP stage (22), and a low pressure LP stage (23); wherein the steam turbine system (4) comprises a HP steam turbine (17), an IP steam turbine (18) and a LP steam turbine (19); The steam pipeline (39 to 51) comprises: an HP steam line (47) for supplying HP steam from the HP stage (21) of the HRSG (3) toward the HP steam turbine (17), an IP steam line (43) connecting the IP stage (22) of the HRSG (3) to the reheater (24), a hot reheat HRH line (49) for supplying IP steam from the reheater (24) toward the IP steam turbine (18), a cold reheat CRH line (51) for receiving spent HP steam from the HP steam turbine (17) and supplying the spent HP steam to the reheater (24), an operating HP bypass line (52) arranged between the HP steam line (47) and the CRH line (51), an operating HRH bypass line (53) arranged between the HRH line (49) and the condenser (6), and an operating LP bypass line (54) arranged between the LP steam line (41) and the condenser (6); and The design of the steam conveying parts, the steam lines (39 to 51) and the operating bypass lines (52 to 54) including bypass valves (55 to 57) of the HRSG (3) includes setting the size and arrangement of at least the HP steam line, the IP steam line, the HRH line, the CRH line and the LP steam line (47, 43, 49, 51, 41) and the HP bypass line, the HRH bypass line and the LP bypass line (52, 53, 54) for a cleanliness ratio (CFR) of at least 1.

1.

4. The method according to claim 3, further comprising: Modulating sacrificial valve trims are provided to at least some of the HP bypass valves, the HRH bypass valves and the LP bypass valves (55, 56, 57) in the operating HP bypass line, the operating HRH bypass line and the operating LP bypass line (52, 53, 54), the modulating sacrificial valve trims being designed to increase the flow coefficient CV capability of the bypass valves (55, 56, 57) so as to support a cleanliness force ratio (CFR) of at least 1.2 for a single HRSG device configuration and at least 1.03 for a multi-HRSG device configuration.

5. The method according to claim 3 or 4, further comprising: The branch point connections of the operating HP bypass line, the operating HRH bypass line and the operating LP bypass line (52, 53, 54) are positioned as close as possible to the steam turbine system (4), very close to and just upstream of the control and isolation valve assemblies (63, 64, 65) of the HP steam turbine, the IP steam turbine and the LP steam turbine (17, 18, 19); and the non-return valve (66) on the CRH line (51) and the downstream connection of the HP bypass line (52) to the CRH line (51) are positioned as close as possible to the HP steam turbine (4).

6. The method according to any one of claims 3 to 5, further comprising: Target inserts (67, 68), preferably in the form of highly polished steel plates, are installed in the HRH line (49) and the LP steam line (41), the target inserts (67, 68) being configured and arranged to allow online targeted inspection and monitoring of the cleanliness of the steam purged steam lines (39 to 57) under steam temperature and pressure operating conditions during a validation purge procedure.

7. The method according to any one of claims 2 to 6, further comprising: Installing steam flow meters in relevant parts of the steam conveying parts, the steam lines (39 to 51) and the operating bypass lines (52 to 54) of the HRSG (3); and calculating the CFR in the relevant parts based on the steam flow measurement results of the steam flow meters during the verification purge procedure.

8. The method according to any one of the preceding claims, further comprising: Providing an inspection / cleaning port in a non-steam-purged section (69 to 72) of the steam line (47, 41, 49, 51); and inspecting and cleaning the non-steam-purged section (69 to 72) after completing the validation purge procedure.

9. The method according to any one of claims 3 to 8, further comprising: At least some of the branch point connections of the HP bypass line, the HRH bypass line, and the LP bypass line (52, 53, 54) are provided with T-shaped connections, which are connected directly to the corresponding bypass line instead of directly to the corresponding steam turbine section (17, 18, 19) to reduce the accumulation of debris in a blind leg located upstream of the corresponding steam turbine section (17, 18, 19).

10. The method according to any one of the preceding claims, wherein the combined cycle power plant (1') has a multi-unit configuration comprising a single steam turbine system (4), a first unit (73) comprising a first HRSG (3a) and a first gas turbine engine (2a), and a second unit (74) comprising a second HRSG (3b) and a second gas turbine engine (2b), the method comprising: The verification purge procedure is performed independently between the first unit (73) and the second unit (74).

11. The method according to claim 10, comprising: The verification purge procedure is performed on the first unit and the second unit (73, 74) one by one, and preferably the verification purge procedure is performed on one of the first unit and the second unit (73, 74), while the blind leg is checked and cleaned after the verification purge procedure in the other unit (74, 73).

12. The method according to any one of claims 1 to 9, wherein the combined cycle power plant (1') comprises a multi-unit configuration, the multi-unit configuration comprising a single steam turbine system (4), a first unit (73) comprising a first HRSG (3a) and a first gas turbine engine (2a), and a second unit (74) comprising a second HRSG (3b) and a second gas turbine engine (2b), the method comprising: When the validation purge procedure is performed in one of the first and second units (73, 74), at least one bypass line (52 to 54) and bypass valve (55 to 57) in the other unit (74, 73) is used to direct the validation steam therethrough.

13. The method according to any one of claims 3 to 9, wherein the combined cycle power plant (1') comprises a multi-unit configuration, the multi-unit configuration comprising a single steam turbine system (4), a first unit (73) comprising a first HRSG (3a) and a first gas turbine engine (2a), and a second unit (74) comprising a second HRSG (3b) and a second gas turbine engine (2b), the method comprising: A temporary jumper (78) is installed from the HP steam turbine valve (63) of the HP steam turbine (17) to a check valve (79) on a common cold reheat CRH line (81), and the HRH bypass valves (56a, 56b) are sized to allow a CFR of at least 1.1 to be obtained on the HP and HRH steam systems.

14. A combined cycle power generation device (1, 1'), comprising: a gas turbine engine (2) for generating power; a heat recovery steam generator HRSG (3) fluidly connected to the gas turbine engine (2) for receiving high energy exhaust gas resulting from the generation of power in the gas turbine engine (2) and configured to generate steam from the high energy exhaust gas; a steam turbine system (4) fluidly connected to the HRSG (3) via steam lines (39 to 51) for receiving steam generated in the HRSG (3) and configured to generate additional power from the steam; a condenser (6) coupled to the steam turbine system (4) for condensing spent steam output from the steam turbine system (4), and a condensate system (7) for returning condensate from the condenser (6) to the HRSG (3); an operating bypass line (52 to 54) fluidly connected between the steam line (39 to 51) and the condenser (6) and arranged to bypass the steam turbine system (4); and A control system (9) for controlling normal operation of the gas turbine engine (2), the HRSG (3), the steam turbine system (4) and the condenser (6) for generating power under varying operating conditions, the control system (9) being further configured to perform pre-operation cleaning of the water and steam systems in the combined cycle power plant (1, 1') by: Ignite the gas turbine engine (2) and debug the gas turbine engine (2); When commissioning the gas turbine engine (2), a verification steam purge procedure including a steam purge operation is performed, wherein steam is generated in the HRSG (3) and purged through a portion of a closed flow loop under high velocity, temperature and cleaning force ratio conditions for cleaning the steam transport parts of the HRSG (3) and the steam lines (39 to 51) connecting the HRSG (3) to the steam turbine system (4), wherein the steam is directed to bypass the steam turbine system (4) via the operating bypass line (52 to 54) without using any temporary piping and is discharged to the condenser (6); and Monitor and verify the cleanliness of selected steam purged steam lines (39 to 54).

15. A combined cycle power plant (1, 1') according to claim 14, wherein the combined cycle power plant (1, 1') is configured according to any one of the preceding claims, and the control system (9) is configured to perform a validation steam purge procedure according to any one of the preceding claims.

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