JPH10331607A - Exhaust heat recovery boiler blowing device and a boiler blowing-out method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical and simple blowing device, capable of saving generated vapor without installing strainers and control valves of temporary piping, and a blowing-out method. SOLUTION: Blowing out piping 39 is connected to a condenser 25 at a position that is under a tube nest 31 within the condenser 25 thus preventing tubing from being damaged by foreign matter flowing into the condenser 25. Moreover, desuperheaters 23 and 24, provided on turbine bypass tubes 14 and 15, lower vapor temperature thereby blowing out to the condenser 25. Furthermore, the use of turbine bypass valves 19 to 21 makes temporary pressure control valves unnecessary. Opening and closing the turbine bypass valves 19 to 21 enable intermittent blowing. For a reheat system, such as a reheater 7, blowing out can be done by using temporary piping 38 from a reheat steam stop valve 18 to a high pressure turbine bypass tube 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler, and more particularly to a blowing apparatus and a blowing out method for removing foreign matter in piping of the boiler by blowing steam from the exhaust heat recovery boiler.

[0002]

2. Description of the Related Art Combined power plants have recently attracted attention as plants most suitable for high-efficiency power generation and intermediate load operation. This plant generates electricity using a gas turbine, and has an exhaust heat recovery boiler that recovers the heat of the exhaust gas discharged from the gas turbine.The steam generated by the exhaust heat recovery boiler drives a steam turbine to generate power. It is.

[0003] Blowing out is performed for the purpose of cleaning the steam system of the exhaust heat recovery boiler. Blowing out of an exhaust heat recovery boiler means that after the steam generated in the steam generator of the boiler is raised to a certain pressure, the on-off valve provided on the steam pipe is fully opened to remove foreign matter in the heat transfer pipe and pipe. This is the work to remove.

[0004] As the blowing-out method, there are an air blowing method shown in FIG. 2 for discharging used steam to the atmosphere and a condenser blowing method for collecting the steam in a condenser 25 shown in FIG. It is being implemented at the plant.

In FIG. 2 and FIG. 3, a low-pressure superheater 4 and a low-pressure superheater 4 are sequentially arranged in the exhaust gas passage of an exhaust heat recovery boiler A into which exhaust gas of a gas turbine B is introduced from a downstream side to an upstream side of the exhaust gas flow. A pressure superheater 5, a reheater 7, a high-pressure superheater 6, and the like are arranged. The steam from the low-pressure drum 1 is superheated by the low-pressure superheater 4, and is passed through a low-pressure main steam pipe 8 and a low-pressure main steam stop valve 16. It is supplied to a low pressure turbine (not shown) using low pressure steam. The steam from the medium pressure drum 2 is superheated by the medium pressure superheater 5, passes through the medium pressure main steam pipe 9 provided with the medium pressure superheater outlet valve 30, passes through the reheater 7, and reheats to a high temperature. Medium pressure turbine (not shown) via steam pipe 12 and reheat steam stop valve 18
Supplied to The steam from the high-pressure drum 3 is superheated by the high-pressure superheater 6 and supplied to a high-pressure turbine (not shown) via the high-pressure main steam pipe 10 and the high-pressure main steam stop valve 17 to perform work. Via the reheat steam pipe 11, it joins the medium pressure main steam pipe 9 on the downstream side of the intermediate pressure superheater outlet valve 30.

A low-pressure main steam pipe 8 and a high-pressure main steam pipe 10
Are provided with a low-pressure turbine bypass pipe 13 and a high-pressure turbine bypass pipe 15 that respectively detour the turbine, and each of the bypass pipes 13 and 15 has an on-off valve 19, 2.
1 is provided. The intermediate-pressure main steam pipe 9 is provided with an intermediate-pressure turbine bypass pipe 14 on the upstream side of the intermediate-pressure superheater outlet valve 30, and the bypass pipe 14 is provided with an on-off valve 20. Further, the respective on-off valves 2 of the intermediate pressure turbine bypass pipe 14 and the high pressure turbine bypass pipe 15
On the downstream side of 0 and 21, temperature reducers 23 and 24 are provided, respectively.

At the time of blowing out, FIG.
In the atmospheric blow method, the low-pressure turbine bypass pipe 13, the medium-pressure turbine bypass pipe 14, and the high-pressure turbine bypass pipe 1
5 are connected to temporary pipes 47, 48 and 49, respectively.
A temporary pipe 50 is connected from the high-pressure main steam stop valve 17 to the low-temperature reheat steam pipe 11. Each temporary piping 47, 48, 4
At the upstream side of the exit 9, test pieces 51, 52, 53 for checking the blowing-out effect are provided, respectively. In addition, eyeglass flange 46 for system switching
Is provided in a temporary pipe 50 connected to the low-temperature reheat steam pipe 11 branched from the medium-pressure main steam pipe.

In the air blowing system shown in FIG. 2, the sound is silenced by the silencer 54 when the steam is blown and discharged to the atmosphere. Superheaters 4 to 6, reheater 7 and low-pressure main steam pipe 8, medium-pressure main steam pipe 9, high-pressure main steam pipe 10, low-temperature reheat steam pipe 1 in exhaust heat recovery boiler A shown in FIG.
1, high-temperature reheat steam pipe 12, low-pressure turbine bypass pipe 1
3. For the purpose of cleaning the mill scale adhered to the intermediate-pressure turbine bypass pipe 14 and the high-pressure turbine bypass pipe 15 and the deposits (foreign matter) adhering during the on-site welding by a high-speed steam flow. Carry out blowing-out work. When performing the blowing-out operation, the steam stop valves 16, 17, 18 and the turbine bypass valves 19, 2, depending on the piping system to be cleaned and the heat transfer tube system.
The appropriate corresponding valve in 0, 21 is closed, the steam is stored in the pipe in which the closed valve is arranged, and when a predetermined pressure is reached, the turbine bypass valve having the corresponding valve is opened to release the steam. Blow.

In the exhaust heat recovery boiler A shown in FIG. 3, members having the same functions as those shown in FIG. 2 are denoted by the same reference numerals and the description thereof is omitted, but the exhaust heat recovery boiler A shown in FIG. In the low-pressure, medium-pressure, and high-pressure steam supply systems, the turbine bypass pipes 13, 14, and 15 are respectively provided with temporary pipes 35,
36 and 37 are connected. A temporary pipe 41 for connecting the intermediate-pressure turbine bypass pipe 14 and the reheat steam stop valve 18 is provided. The temporary pipe 41 is connected to the temporary pipe 41 in a branched state. The temporary pipes 35 and 36 are provided with spectacle flanges 26 and 27, respectively, and the temporary pipe 3 on the condenser 25 side from the spectacle flanges 26 and 27 is provided.
5 and 36 are temporary pipes 39 that join and connect to the condenser 25.
Is formed. Further, test pieces 44 and 29 are provided in the temporary pipes 37 and 39, respectively. The temporary pipe 37 is provided with a strainer 43, and the temporary pipe 41 is provided with an on-off valve 42 and a temperature reducer 45. In the drawings of the present invention, all temporary pipes are represented by dotted lines.

In the blowing-out method shown in FIG. 3, the steam stop valves 16 and 1 are used in accordance with the piping system to be cleaned and the heat transfer tube system.
7, 18 and the appropriate valves among the turbine bypass valves 19, 20, and 21 are closed, and the steam is stored in the piping in which the closed valves are arranged. A certain turbine bypass valve is opened, steam is blown, foreign matter and scale in the blown pipe are removed, and steam and water are all collected in the condenser 25.
At this time, if foreign matter or the like enters the upper part of the condenser 25, it may cause damage or failure of the apparatus. Therefore, the foreign matter is removed by the strainer 43 in the temporary pipe 36 on the inlet side of the condenser 25. In addition, the foreign matter from the bypass pipes 13 and 14 enters the lower part of the condenser 25 and can be settled and discharged, so that there is no possibility of causing damage or failure of the apparatus.

[0011]

In the above-mentioned conventional blowing method, the air blowing method shown in FIG. 2 discharges generated steam to the atmosphere to generate white smoke, and is not economical because it is not recovered. . In addition, the condenser blow method shown in FIG. 3 is excellent in economy because the generated steam is collected in the condenser 25. However, reheat steam stop valve 1
It is necessary to reduce the temperature of the steam passing through the condenser 8 before flowing into the condenser 25. Therefore, a temperature reducer 45 is required for the temporary pipe 41, and the temporary pipe 36 is connected to the high-pressure turbine bypass pipe 15. A strainer 43 is required to prevent foreign matter and the like from flowing into the upper portion of the condenser 25 through the nozzle. If the strainer 43 is clogged, blowing out is interrupted to clean the strainer 43. There is a problem that it is necessary to do.

In the blow-out method shown in FIG. 3, in the above-mentioned conventional method, the generated steam is continuously and continuously passed through the pipe, and the pressure is adjusted by a temporary control valve 42 installed in a temporary blow-out pipe 41. Meanwhile, a method is employed in which dynamic pressure is generated by swinging the pressure to secure the foreign matter scattering force.

In this method, the control valve 42 of the temporary pipe 41
In addition, since a large amount of steam flows continuously, a load (about 40 to 60%) of the gas turbine B is taken, thereby causing a problem that a large amount of fuel is consumed.

Further, the exhaust gas temperature is high (about 500 ° C. or higher) in order to load-operate the gas turbine B.
It is necessary to adopt alloy steel also for ~ 37, 39, 41,
There was a problem that the cost was extremely increased.

An object of the present invention is to solve the above-mentioned problems of the blowing-out method, and particularly to a strainer for temporary piping,
An object of the present invention is to provide an economical and simple blowing device and a blowing-out method capable of saving the generated steam amount without installing a control valve.

[0016]

The object of the present invention is achieved by the following constitution. That is, an exhaust heat recovery boiler for introducing exhaust gas from a gas turbine, a steam turbine using steam obtained by the exhaust heat recovery boiler, and a condenser for collecting steam used in the steam turbine as condensate. In the exhaust heat recovery boiler system provided with, a turbine bypass pipe that bypasses the steam turbine is provided in a steam pipe that connects the exhaust heat recovery boiler and the steam turbine, and the turbine bypass pipe is connected through a temporary pipe for steam pipe blowing out. An exhaust heat recovery boiler blowing device connected to the condenser at a level lower than the tube nest in the condenser, or
In a waste heat recovery boiler system including a waste heat recovery boiler for introducing exhaust gas from a gas turbine and a condenser for recovering steam obtained by using the steam obtained by the boiler in a steam turbine as condensate, In this method, the steam of the heat recovery boiler is blown, and the blown out steam is recovered to the condenser at a height lower than the tube nest in the condenser.

The features of the present invention are that the connection between the blow-out pipe to the condenser and the condenser is made at a position lower than the condenser tube nest, and that the present turbine bypass valve is used. An intermittent blow-out system in which the turbine bypass valve is closed, steam is stored in the turbine bypass pipe, and the turbine bypass valve is opened and blown after reaching a predetermined pressure. Here, the term “main installation” refers to equipment that is always provided in the exhaust heat recovery boiler, and is used as a term for temporary installation.

The condenser has different steam receiving conditions depending on the upper part and the lower part of the condenser tube nest. However, the temperature of the steam flowing into the condenser is reduced by the permanent cooler of the turbine bypass pipe. By lowering and lowering the temperature to the lower receiving condition, it is possible to blow out to the lower part of the condenser. Further, by using the permanent turbine bypass valve, a temporary pressure control valve is not required, and intermittent blowing can be performed by opening and closing the permanent turbine bypass valve.

Further, the exhaust heat recovery boiler of the present invention is provided with a reheat steam piping system, the reheat steam piping system is provided with a reheat steam stop valve, and the reheat steam stop valve is connected to the high pressure turbine bypass pipe. A temporary pipe for blowing the reheat steam pipe may be connected therebetween.

Here, regarding the reheat system, a temporary pipe from the reheat steam stop valve to the high-pressure turbine bypass pipe is used.
By connecting to the upstream side of the high-pressure turbine bypass valve and the desuperheater adjacent to the high-pressure turbine bypass valve, blow-out can be performed using the high-pressure turbine bypass valve and the desuperheater provided in this embodiment.

A test piece for checking foreign matter is provided in the blow-out pipe, and when the test piece is intermittently blown out, the number of dents on the test piece confirms that foreign matter in the system has been discharged out of the system. can do.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the exhaust heat recovery boiler blowing-out system according to the present invention will be described with reference to an example of a reheat triple pressure exhaust heat recovery boiler A shown in FIG. FIG. 1 is a system diagram of the combined cycle power plant. The combined cycle power plant includes a gas turbine B, a generator (not shown) driven by the gas turbine B, and an exhaust heat recovery boiler A and an exhaust heat recovery boiler A that introduce exhaust gas from the gas turbine B and recover heat thereof. And a steam turbine (not shown) driven by steam from the steam turbine.

In the exhaust gas passage of the exhaust heat recovery boiler A, a low pressure superheater 4, a medium pressure superheater 5, a reheater 7, a high pressure superheater 6, and the like are arranged in order from the downstream side of the exhaust gas flow to the upstream side. The steam from the low-pressure drum 1 is superheated by a low-pressure superheater 4 and supplied to a low-pressure turbine (not shown) using low-pressure steam via a low-pressure main steam pipe 8 and a low-pressure main steam stop valve 16. You. The steam from the medium pressure drum 2 is supplied to the medium pressure superheater 5.
And then passes through the reheater 7 and passes through the high-temperature reheat steam pipe 1
2 and a reheat steam stop valve 18 to supply it to a medium pressure turbine (not shown) or the like. The steam from the high-pressure drum 3 is superheated by the high-pressure superheater 6 and supplied to a high-pressure turbine (not shown) via the high-pressure main steam pipe 10 and the high-pressure main steam stop valve 17.

The low-pressure, medium-pressure, and high-pressure steam supply systems have low-pressure turbine bypass pipes 13, medium-pressure turbine bypass pipes 14, and high-pressure turbine bypass pipes 15, respectively. , 21
Is provided. Turbine bypass valves 19, 20, 2
Numeral 1 is provided at the connection between the turbine bypass pipes 13, 14, 15 of the low-pressure, medium-pressure, and high-pressure steam supply systems and the flow paths of the temporary pipes 35, 36, 37 following these pipes. Turbine bypass valve 20 and temporary piping 37 for medium pressure
A desuperheater 23 is provided in the turbine bypass pipe 14 between them, and a desuperheater 24 is provided in the turbine bypass pipe 15 between the high-pressure turbine bypass valve 21 and the temporary high-pressure pipe 35. Further, a temporary pipe 38 for connecting the high pressure turbine bypass pipe 15 branched from the high pressure main steam pipe 10 and the reheat steam stop valve 18 is provided. The connection between the temporary pipe 38 and the high-pressure turbine bypass pipe 15 is provided between the high-pressure turbine bypass valve 21 and the high-pressure turbine bypass valve front valve 22 provided in the high-pressure turbine bypass pipe 15 on the upstream side thereof.

Further, spectacle flanges 26, 27, 28 for switching between opening and closing of the pipes are provided in the temporary pipes 35, 36, 37 of the low pressure, medium pressure, and high pressure steam supply systems, respectively. Flanges (flanges for switching between opening and closing adjacent pipes) 26, 2
On the downstream side of 7 and 28, a blow-out pipe 39 for integrating the temporary pipes 35, 36 and 37 is provided. The blow-out pipe 39 is provided with a test piece 29 for checking the blow-out effect. The test piece 29 counts the number of dents caused by the scattered foreign matter, and confirms the removal state of the foreign matter in the system by the blow-out.

Next, the procedure of blowing out according to this embodiment will be described. The low-pressure blowing-out closes the low-pressure main steam stop valve 16 and the eyeglass flanges 27 and 28, and the low-pressure drum 1, the low-pressure superheater 4, the low-pressure main steam pipe 8, the low-pressure turbine bypass pipe 13, and the temporary low-pressure pipe 3 subsequent thereto.
5. This is performed by the blowing-out pipe 39.

The high-pressure blowing-out is performed by closing the high-pressure main steam stop valve 17 and the eyeglass flanges 26 and 27, opening the high-pressure turbine bypass valve front valve 22, and opening the high-pressure drum 3, the high-pressure superheater 6, and the high-pressure main steam pipe 10. This is performed by the turbine bypass pipe 15, the temporary high pressure pipe 36, and the blowing out pipe 39.

The intermediate-pressure blowing-out is performed by closing the intermediate-pressure superheater outlet valve 30 and the spectacle flanges 26 and 28, the intermediate-pressure drum 2, the intermediate-pressure superheater 5, the intermediate-pressure main steam pipe 9, and the intermediate-pressure turbine bypass pipe 14. This is followed by a temporary piping 37 for medium pressure and a piping 39 for blowing out.

The reheating blow-out is performed using both medium-pressure steam and high-pressure steam. The high-pressure turbine bypass valve front valve 22, the medium-pressure turbine bypass valve 20, and the spectacle flanges 26 and 27 are closed, and the high-pressure drum 3 A high-pressure system connected to a low-temperature reheat steam pipe 11 through a high-pressure superheater 6, a high-pressure main steam pipe 10, and a high-pressure main steam stop valve 17, a medium-pressure drum 2, a medium-pressure superheater 5, and a medium-pressure main steam pipe 9. , A low-temperature reheat steam pipe 11, a reheater 7, a high-temperature reheat steam pipe 12, a reheat steam stop valve 18, and further connected to a high-pressure turbine bypass pipe 15 via a temporary pipe 38. This is carried out by a temporary piping 36 for piping and a piping 39 for blowing out.

Each blowing-out system has a system configuration in which it is connected to the condenser 25 through a common blowing-out pipe 39 and a test piece 29 attached thereto.

Here, a blow-out pipe 39 to the condenser 25 is connected to a lower part of the condenser tube nest 31, and foreign matters separated and separated from the exhaust heat recovery boiler A by blowing out are removed from the condenser 25. To prevent the tubule from being damaged.

In the blowing out, in all systems, the main turbine bypass valves 19 to 21 are all closed, the temporary pipes 35 to 39 are provided, the gas turbine B is started, and the system is brought to a pressure required for the blowing out. Increase the pressure inside. Here, at the time of pressurization in the system, a drain valve (not shown) is opened to warm the system and discharge excess steam generated. Then, after reaching a predetermined pressure, the steam is stocked in the system, the turbine bypass valves 19 to 21 are sequentially opened as appropriate, and the generated steam is caused to flow rapidly to generate a dynamic pressure. This operation is repeated until blowing out is performed by the intermittent blow method that is generated, and the number of dents on the test piece 29 confirms that foreign matter in the system has been discharged out of the system.

In the case of the present system in which generated steam is stocked in the system, the pressure is raised to a predetermined pressure, and the gas is intermittently blown, no-load operation of the gas turbine B is sufficient. Therefore, the exhaust gas temperature of the gas turbine B is about 300
Because the temperature is as low as ° C., carbon steel can be used as a constituent material of the temporary pipes 35 to 38 and the blow-out pipe 39, which is very economical.

[0034]

According to the present invention, since the steam temperature is reduced without installing a temporary strainer, damage to the thin tube of the condenser can be prevented. In addition, the gas turbine can be operated in no-load operation by performing intermittent blowing with the turbine bypass valve provided without installing a temporary pressure control valve, and an economical reheating triple-pressure exhaust heat recovery boiler can be used. Blowing out is possible.

[Brief description of the drawings]

FIG. 1 shows a blowing-out system of a reheat triple-pressure exhaust heat recovery boiler according to the present invention.

FIG. 2 shows a conventional blowing-out system using atmospheric blowing.

FIG. 3 shows a conventional condenser-type blowing-out system.

[Explanation of symbols]

A Exhaust heat recovery boiler B Gas turbine 1 Low pressure drum 2 Medium pressure drum 3 High pressure drum 4 Low pressure superheater 5 Medium pressure superheater 6 High pressure superheater 7 Reheater 8 Low pressure main steam pipe 9 Medium pressure main steam pipe 10 High pressure main steam Pipe 11 Low pressure reheat steam pipe 12 High temperature reheat steam pipe 13 Low pressure turbine bypass pipe 14 Medium pressure turbine bypass pipe 15 High pressure turbine bypass pipe 16 Low pressure main steam stop valve 17 High pressure steam stop valve 18 Reheat steam stop valve 19 Low pressure turbine bypass Valve 20 Medium-pressure turbine bypass valve 21 High-pressure turbine bypass valve 22 High-pressure turbine bypass front valve 23, 24 Decooler 25 Condenser 26, 27, 28 Eyeglass flange 29 Test piece 30 Medium-pressure superheater outlet valve 35 Temporary piping for low pressure 36 Temporary piping for medium pressure 37 Temporary piping for high pressure 39 Piping for blowing out

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shusaku Ueda 6-9 Takaracho, Kure-shi, Hiroshima Babcock Hitachi Kure Factory

Claims (10)

[Claims] 1. An exhaust heat recovery boiler for introducing exhaust gas from a gas turbine, a steam turbine using steam obtained by the exhaust heat recovery boiler, and a condensate for collecting steam used in the steam turbine as condensate water. In a waste heat recovery boiler system including a water device, a turbine bypass pipe for bypassing a steam turbine is provided in a steam pipe connecting the waste heat recovery boiler and the steam turbine, and the turbine bypass pipe is a temporary pipe for blowing out a steam pipe. A waste heat recovery boiler blowing device connected to the condenser at a height lower than the tube nest in the condenser via the condenser. 2. The exhaust heat recovery boiler is provided with steam piping systems having different pressure levels, and the steam piping systems at each pressure level are provided with turbine bypass pipes each bypassing a turbine having a corresponding pressure level. The exhaust heat recovery boiler blowing device according to claim 1, wherein the bypass pipes are connected to the blow-out pipes through temporary pipes. 3. The steam pipe system of each pressure level of the exhaust heat recovery boiler is provided with a main steam stop valve of a corresponding pressure level, and a turbine bypass valve is provided between each turbine bypass pipe and each temporary pipe. 3. The exhaust heat recovery boiler blowing apparatus according to claim 2, wherein each of the turbine bypass pipes is connected to a blowing-out pipe via an eyeglass flange. 4. A reheat steam piping system is provided in the exhaust heat recovery boiler, a reheat steam stop valve is provided in the reheat steam piping system, and a reheat steam stop valve is connected between the reheat steam stop valve and the high-pressure turbine bypass pipe. The exhaust heat recovery boiler blowing apparatus according to claim 1, wherein a temporary pipe for hot steam pipe blowing is connected. 5. A high-pressure turbine bypass pipe opening / closing valve is provided on each of the upstream and downstream sides of a connection portion of a temporary pipe for reheat steam piping blowing to a high-pressure turbine bypass pipe, and a rear end of the two high-pressure turbine bypass pipe opening / closing valves is provided. 5. The exhaust heat recovery boiler blowing device according to claim 4, wherein a temperature reducer is provided in a high-pressure turbine bypass pipe on a downstream side of the on-off valve on the downstream side. 6. The apparatus according to claim 2, wherein a temperature reducer is provided in a portion of the turbine bypass pipe downstream of the turbine bypass valve provided in the turbine bypass pipe at a relatively high pressure level and each temporary pipe. Exhaust heat recovery boiler blowing equipment. 7. The exhaust heat recovery boiler blowing apparatus according to claim 1, wherein a test piece for confirming foreign matter is provided in the blow-out pipe. 8. An exhaust heat recovery system comprising: an exhaust heat recovery boiler for introducing exhaust gas from a gas turbine; and a condenser for recovering steam obtained by using the steam obtained by the boiler in a steam turbine as condensate. In a boiler system, exhaust heat recovery boiler blowing is characterized in that the steam of the waste heat recovery boiler is blown, and the blown out steam is recovered in the condenser at a height lower than the tube nest in the condenser. Out method. 9. The exhaust heat recovery boiler blow-out method according to claim 8, wherein the blow-out is performed by intermittent blow. 10. The exhaust heat recovery boiler blow-out method according to claim 9, wherein the blow-out is performed in a steam piping system having a plurality of pressure levels.