JP3538780B2 - Initial cleaning method of steam piping system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an initial cleaning method for a steam piping system applied to a combined cycle power plant having a shaft arrangement in which respective rotating shafts are connected in series in the order of a gas turbine, a steam turbine and a generator. About.

[0002]

2. Description of the Related Art A power generation plant combining a gas turbine and a steam turbine, that is, a so-called combined cycle power generation plant, is often employed for the purpose of high power generation efficiency. FIGS. 4 and 5 show a typical combined cycle power plant conventionally employed. The example of FIG. 4 is a combined cycle power plant having a shaft arrangement in which respective rotating shafts are connected in series in the order of a gas turbine 1, a generator 2, and a steam turbine 3. The steam pipe system 4 has a steam source 5 and a steam pipe 6, and the steam source 5 is connected to a water supply pipe 7, a economizer 8, an evaporator 9, a drum 10, a superheater 11, and an exhaust duct 12 of the gas turbine 1. It has a heater 13 connected thereto. On the inlet side of the steam turbine 3, a switching valve 16 for switching the steam pipe 6 from the steam generation source 5 to a steam turbine pipe 14 and a temporary discharge pipe 15 is provided. Are open to the silencer 18.

The initial cleaning of the steam piping system 4 in the plant shown in FIG. 4, that is, the first cleaning of the piping system after the completion of the steam piping system 4, is performed using the steam generated from the steam generating source 5 as follows. Has been done. First, the switching valve 16 provided in the steam pipe 6 is switched to the discharge pipe 15 side, and the on-off valve 17 is opened. Next, water is supplied from the water supply pipe 7 of the steam generation source 5 to burn the boiler, and the gas turbine 1 is operated to heat the heater 13 with the exhaust gas (normally about 450 ° C.) to generate steam. The steam turbine 3 is separated from the generator 2 by a coupling 19, and the output of the generator is connected to a temporary load such as a water resistance (not shown). Steam from the steam generation source 4 is supplied to the steam pipe 6 and the switching valve 1.
6. Discharged from the tip of the discharge pipe 15 to the silencer 18 via the on-off valve 17, whereby the initial cleaning of the steam pipe system 4 is performed.

FIG. 5 shows an example of a combined cycle power plant having a shaft arrangement in which respective rotating shafts are connected in series in the order of a gas turbine 1, a steam turbine 3, and a generator 2.
The same devices as those in FIG. 4 are denoted by the same reference numerals. The example of FIG. 5 differs from the example of FIG. 4 in the arrangement of the shafts of the steam turbine 3 and the like. Therefore, the initial cleaning method of the steam piping system 4 is more restricted than that of FIG. As shown in the figure, since the steam turbine 3 exists between the gas turbine 1 and the generator 2, only the steam turbine 3 cannot be separated from the gas turbine 1, so that the
Cannot be operated with a predetermined load. That is, the generator 2
Cannot be used as the load of the gas turbine 1,
As a result, steam cannot be generated using the exhaust gas of the gas turbine 1. Therefore, in this plant, it becomes necessary to supply steam for the initial cleaning from the steam generation source 5 to the switching valve 17 without operating the gas turbine 1. For this reason, a method conventionally used in a plant as shown in FIG. 5 is a method in which auxiliary steam is supplied from another existing steam generation source 20 or the like to the self-canister steam generation source 5 as shown in FIG. And using such auxiliary steam,
Initial cleaning is performed by flowing steam from the steam generation source 5 to the steam pipe 6.

[0005]

However, the initial cleaning methods for the plants shown in FIGS. 4 and 5 have the following problems. First, in the initial cleaning of the plant of FIG. 4, it was necessary to install a silencer 18 for releasing cleaning steam to the atmosphere. Since the silencer 18 emits a large amount of steam, it becomes a large-sized facility, and requires a lot of man-hours and time for installation. Further, it is necessary to perform the initial cleaning after the construction of the gas turbine 1 and the like and the completion of the test. Therefore, even if the steam generation source 5 is completed, it has to wait for the initial cleaning.

Next, in the initial cleaning of the plant shown in FIG. 5, it is necessary to install the silencer 18 as in the case of the plant shown in FIG. 4, and it is necessary to supply auxiliary steam from another steam generating source. There is. Particularly for the latter, it is inevitable that the cost will be extremely high, including the piping equipment. Therefore, the present invention is to solve the problem of the initial cleaning of the steam piping system in such a conventional combined cycle power plant, and in particular, to provide an initial cleaning method suitable for solving the problem in the plant shown in FIG. It is an issue.

[0007]

That is, an initial cleaning method of the present invention is directed to a steam piping system in a combined cycle power plant having a shaft arrangement in which respective rotating shafts are connected in series in the order of a gas turbine, a steam turbine, and a generator. This is applied to the initial cleaning method described above. In this method, a switching valve for switching a steam pipe from a steam generation source to a steam turbine pipe and a discharge pipe at a steam turbine inlet side is provided, and an on-off valve is further provided on the discharge pipe, and the tip thereof is connected to a condenser circulating water system or a gas turbine exhaust pipe. Open to a large capacity piping system such as a system. Prior to cleaning, the switching valve is switched to the discharge pipe side, and pressurized air or nitrogen gas is supplied from the steam generation source side to gas-pressurize the steam pipe system, and then the on-off valve is opened intermittently. Thus, cleaning is performed by intermittently generating a gas jet flow in a steam piping system from the steam generation source side to the on-off valve.

[0008]

According to the method of the present invention, the cleaning is carried out by a gas jet generated intermittently. Therefore, even if it is applied to a plant as shown in FIG. 5, there is no need to construct an auxiliary steam pipe unlike the conventional method. . In addition, the initial cleaning can be freely performed (for example, adopting a forward moving process) in accordance with the construction process of the steam piping system, and there is no need to wait for the completion of the steam turbine or the gas turbine, thereby facilitating the process management. Further, the gas jet stream for cleaning is discharged to a large-capacity piping system such as a condenser circulating water system or a gas turbine exhaust system which is generally completed earlier than the installation of a steam turbine or a gas turbine. Eliminates the need for large silencers. In addition, by using nitrogen gas as the pressurized gas for cleaning, initial cleaning can be performed after the water pressure test of the steam piping system, and the system can be directly stored with nitrogen gas.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a plant system diagram for implementing the cleaning method of the present invention. The main parts of the plant are the same as those of the conventional plant shown in FIG. 5, and the same components are denoted by the same reference numerals as in FIG. That is, this power plant is composed of the gas turbine 1,
This is a combined cycle power plant in which the rotating shafts are connected in series in the order of a steam turbine 3 and a generator 2. A steam piping system 4 includes a steam generating source 5 and a steam piping 6.
The steam generation source 5 has a water supply pipe 7, a economizer 8, an evaporator 9, a drum 10, and a superheater 11. Although not shown, the steam generation source 5 has a heater connected to the exhaust duct of the gas turbine 1 as in the example of FIG.

On the inlet side of the steam turbine 3, there is provided a switching valve 16 for switching the steam pipe 6 from the steam generation source 5 to a steam turbine pipe 14 and a discharge pipe 30. The discharge pipe 30 is provided with, for example, an open / close valve 31 which is hydraulically driven or manually opened and closed intermittently, and a leading end of which is a condenser pipe circulating water pipe 33 using a blowout seat 32. 34. On the other hand, a nitrogen cylinder card 35 in which a large number of nitrogen cylinders are connected in parallel and an evaporator 9 in the vapor generation source 5 are connected by a gas pipe 36, whereby a pressurized nitrogen gas of, for example, 7 kg / cm ² G is supplied to the vapor generation source. 5. Open / close valve 37
Is provided to close the water supply pipe 7 during the initial cleaning.

FIG. 2 shows another example of a large-capacity piping system capable of discharging a gas jet stream. In this example, a condenser 38 is used as the large-capacity piping system 33, and a piping connection portion 39 is provided below the condenser 38 to connect the distal end of the discharge piping 30 in FIG. FIG. 3 is an example of still another large-capacity piping system capable of discharging a gas jet stream. In this example, the exhaust duct 12 of the gas turbine 1 is used as the large-capacity piping system 33.
A pipe connection part 40 is provided to connect the tip of the discharge pipe 30 of FIG.

Next, the operation of the above apparatus will be described with reference to FIG. 1. First, the switching valve 16 provided in the steam pipe 6 is connected to the discharge pipe 30.
And the nitrogen gas pressurized from the nitrogen cylinder 35 is supplied to the evaporator 9 to pressurize the steam piping system 4. Next, the on-off valve 31 provided in the discharge pipe 30
Is intermittently opened to intermittently generate a gas jet flow in the steam piping system 4 from the steam generation source 5 side to the on-off valve 31 to blow off dust and debris in the steam piping system 4 for cleaning. . In order to open the on-off valve 31 intermittently, for example, it may be controlled intermittently by a control circuit using a timer means.

Dust and debris carried along with the gas jet stream in the steam piping system 4 by cleaning are discharged into a condenser circulating water piping 34 as a large-capacity piping system 33. Note that dust and debris discharged into such a large-capacity piping system 33 are carried by running water or the like during a test operation of the apparatus and are removed outside the system. After the initial cleaning of the steam piping system 4 is completed as described above, the switching valve 16 is switched to the steam turbine piping 14 side to bring the steam piping system 4 into an operating state.

[0014]

The initial cleaning method for a steam pipe system according to the present invention having the above-described structure has the following effects. (1) Since cleaning is performed by a gas jet generated intermittently, there is no need to construct an auxiliary steam pipe unlike the conventional method. (2) The initial cleaning can be freely performed in accordance with the construction process of the steam piping system, and there is no need to wait for the completion of the steam turbine or the gas turbine. (3) The gas jet stream for cleaning is discharged into a large-capacity piping system such as a condenser circulating water system or a gas turbine exhaust system which is generally completed earlier than the installation of a steam turbine, a gas turbine, or the like. Becomes unnecessary. (4) By using nitrogen gas as the pressurized gas for cleaning, the initial cleaning can be performed after the water pressure test of the steam piping system, and the system can be directly stored with nitrogen gas.

[Brief description of the drawings]

FIG. 1 is a plant system diagram for implementing a cleaning method of the present invention.

FIG. 2 is an explanatory view showing another example of a large-capacity piping system for discharging a gas jet stream in the present invention.

FIG. 3 is an explanatory view showing still another example of a large-capacity piping system for discharging a gas jet stream in the present invention.

FIG. 4 is a plant system diagram for implementing a conventional cleaning method.

FIG. 5 is another plant system diagram for implementing the conventional cleaning method.

[Explanation of symbols]

1 Gas turbine 2 generator 3 Steam turbine 4 Steam piping system 5 Steam source 6. Steam piping 7 Water supply piping 8 Economizer 9 Evaporator 10 drums 11 Superheater 12. Exhaust duct 13 heater 14 Steam turbine piping 15 Release piping 16 Switching valve 17 On-off valve 18 Silencer 19 Coupling 20 steam sources 30 Release piping 31 On-off valve 32 blowout seat 33 Large capacity piping system 34 Condenser circulating water piping 35 Nitrogen cylinders 36 Gas piping 37 On-off valve 38 condenser 39 Piping connection 40 piping connection

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-101604 (JP, A) JP-A-62-273093 (JP, A) Fully open Showa 56-120301 (JP, U) Really open Showa 60- 172000 (JP, U) JP-A 4-1601 (JP, U) JP-A 54-108844 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01K 17/04

Claims (1)

(57) [Claims] 1. An initial cleaning method for a steam piping system 4 in a combined cycle power generation plant having a shaft arrangement in which respective rotating shafts are connected in series in the order of a gas turbine 1, a steam turbine 3, and a generator 2. A switching valve 16 for switching the steam pipe 6 from 5 to a steam turbine pipe 14 and a discharge pipe 30 on the steam turbine inlet side;
Further, an opening / closing valve 31 is provided on the discharge pipe 30 and the end thereof is opened to a large-capacity pipe system 33 such as a condenser circulating water system or a gas turbine exhaust system. Prior to cleaning, the switching valve 16 is moved to the discharge pipe 30 side. Switching,
Pressurized air or nitrogen gas is supplied from the steam generation source 5 side to gas-pressurize the steam piping system 4.
1. An initial cleaning method for a steam piping system, characterized by intermittently generating a gas jet flow in a steam piping system 4 from the steam generation source 5 side to the on-off valve 31 by intermittently opening the gas supply line 1 to perform cleaning.