JP3586542B2 - Multi-shaft combined cycle power plant - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-shaft combined cycle power plant configured by applying a single steam turbine to a combination of a plurality of gas turbines and an exhaust heat recovery boiler.
[0002]
[Prior art]
A combined cycle power plant is a power generation system that combines a gas turbine plant and a steam turbine plant.The high-temperature area of thermal energy is shared by the gas turbine, and the low-temperature area is shared by the steam turbine, and heat energy is effectively used. It is a power generation system that has been collected and used, and has been particularly spotlighted in recent years.
[0003]
In this combined cycle power plant, research and development have been promoted with one point for improving the efficiency being the high temperature of the gas turbine.
[0004]
On the other hand, in order to achieve high temperatures, it is necessary to pursue a cooling system from the viewpoint of the heat resistance of the turbine structure, and various trials and errors have been made in this field. It has been progressing to a form in which steam cooling is performed using steam.
[0005]
As an example, there is Japanese Patent Application Laid-Open No. 05-163960. However, the disclosed technology does not disclose the concept of employing steam as a cooling medium of a gas turbine, but the cooling steam is exhausted heat. The medium-pressure steam in the recovery boiler is used, and the total amount of steam is not sufficient, and it is not always sufficient to secure stable and reliable cooling.
[0006]
Therefore, in recent years, a further step has been taken, and the use of exhaust gas from a high-pressure turbine as the cooling steam is studied, focusing on the fact that the cooling steam is quantitatively sufficient and can perform stable cooling. Has been reached.
[0007]
On the other hand, as for the combined cycle power plant itself, from the single-shaft type in which the gas turbine, the exhaust heat recovery boiler and the steam turbine are all arranged in a one-to-one relationship, the combination of the gas turbine and the exhaust heat recovery boiler is changed. A multi-shaft type, in which a plurality of systems are provided and combined with a single steam turbine, has been devised, and the use of cooling steam as a cooling medium regardless of whether the shaft is single-shaft or multi-shaft is being studied. It is in.
[0008]
[Problems to be solved by the invention]
As described above, the conventional steam cooling system further removes the use of medium-pressure steam from a heat recovery steam generator as a cooling medium, and further enhances its practicality by progressing to the use of high-pressure exhaust from a steam turbine. However, since the high-pressure exhaust gas also has a high temperature, the high-temperature portion of the gas turbine corresponding to the portion to be cooled must be made of a material that can withstand this high temperature.
[0009]
However, materials that can withstand high temperatures are naturally required to be expensive due to their strict requirements, etc. In particular, for turbine disks, etc., there are demands for cost reduction, etc. Actually, there are severe problems in designing and manufacturing, which are difficult.
[0010]
Moreover, apart from the so-called single-shaft combined cycle power plant in which the gas turbine, the exhaust heat recovery boiler and the steam turbine are combined in a one-to-one relationship, one set includes the gas turbine and the exhaust heat recovery boiler as one unit. In a so-called multi-shaft combined cycle power plant in which steam generated in each heat recovery steam generator in a plurality of sets is collected and supplied to a steam turbine, multiple sets of gas turbines have unbalanced output. During operation, the temperature of cooling steam, which is high-pressure turbine exhaust, may become abnormally high due to a decrease in the amount of steam supplied to the steam turbine, etc., and the heat resistance of the combustor and blades also goes down. However, the heat resistance of the disk is very important.
[0011]
In view of such a situation, the present invention is particularly applicable to a multi-shaft type so as to obtain a favorable result, without impairing the stability of the function of steam cooling at all, and controlling the temperature of the cooling steam used as a cooling medium. It is an object of the present invention to provide a combined cycle power plant capable of manufacturing a gas turbine using a material which is easily adjusted and which is easily available.
[0012]
[Means for Solving the Problems]
The present invention has the problems described above were solved all Kunasa, the combination of the exhaust heat recovery boiler to heat the exhaust gas turbine and the gas turbine is provided a plurality of rows, and set the steam generated in each heat recovery steam Te in multi-shaft combined cycle power plant to supply a single steam turbine, disposed a temperature reducing apparatus to the cooling steam supply passage for supplying the high temperature section of the gas turbine high pressure steam turbine exhaust as cooling steam, the temperature reducing An object of the present invention is to provide a multi-shaft combined cycle power plant in which high-pressure water is supplied to at least one of a medium-pressure economizer and a high-pressure economizer to reduce the temperature of the cooling steam.
[0013]
That is, a high-pressure steam turbine exhaust is first selected and adopted as a cooling medium for a high-temperature portion of a gas turbine, and a medium-pressure or high-pressure saving device is provided in a cooling steam supply path for supplying the high-pressure steam turbine exhaust as cooling steam. The temperature of the cooling steam is reduced by a temperature reducing device to which high-pressure water is supplied from at least one of the devices, and the cooling steam is supplied to a high-temperature portion of the gas turbine for cooling.
[0014]
In this way, by quantitatively reducing the temperature of the high-pressure exhaust gas in the supply path through the temperature reducing device in the supply path, the temperature of the high-pressure exhaust gas is significantly and surely reduced, and the cooled part is cooled. The high-temperature portion of the gas turbine corresponds to a material that has a reduced heat-resistant performance, and enables stable cooling without lowering the overall efficiency as a multi-shaft combined cycle power plant.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0016]
This embodiment shows a basic type of a multi-shaft combined cycle power generation plant, in which a combination of a gas turbine plant and an exhaust heat recovery plant is arranged in two lines, and steam generated in both lines is converted into a single steam turbine plant. Since the sets of the gas turbine plant and the exhaust heat recovery plant are the same for each series, one series will be described, and the description of the other series will be omitted.
[0017]
A gas turbine plant 10 includes a gas turbine 11, an air compressor 12 driven by the gas turbine 11, and a combustor 13 for burning compressed air supplied from the air compressor 12 together with fuel as main components. I have.
[0018]
The gas turbine 11 includes moving blades, stationary blades, and the like (not shown), which correspond to the high-temperature portion 11a requiring cooling. Further, the combustor 13 has a transition piece cooling section 13a from the rear area of the combustion chamber to the combustion gas outlet, and the transition piece cooling section 13a is also a part requiring cooling like the high temperature section 11a.
[0019]
Then, a cooling steam supply path 14 for supplying cooling steam toward the high temperature section 11a of the gas turbine 11 and a branch from the cooling steam supply path 14 are cooled to the transition piece cooling section 13a of the combustor 13. A cooling steam branch path 15 for supplying steam is provided.
[0020]
Reference numeral 16 denotes a cooling device which is disposed in a cooling steam supply path 14 for supplying cooling steam to the high temperature section 11a of the gas turbine 11, and sprays high temperature water from an exhaust heat recovery boiler 20 or the like described later to spray the cooling steam. Is to lower the temperature.
[0021]
A medium-pressure steam supply path 35 for extracting medium-pressure steam is connected to a medium-pressure evaporator 26 (described later) in the exhaust heat recovery boiler 20, and the medium-pressure steam supply path 35 is connected to the cooling steam supply path. The cooling steam branch path 15 is connected to a downstream position where the cooling steam branch path 15 branches from the cooling steam supply path 14, and is arranged so that medium-pressure steam is mixed into the cooling steam supply path 14.
[0022]
Reference numeral 37 denotes a gas turbine cooling steam recovery path, which communicates with the inlet side of the intermediate pressure second reheater 28, and reference numeral 38 denotes a transition piece cooling steam recovery path, which is the outlet side of the intermediate pressure second reheater 28. Is in communication with
[0023]
Reference numeral 20 denotes an exhaust heat recovery boiler, which uses the exhaust gas of the gas turbine 11 as a heating source, and has an interior divided into a high-pressure steam generator, a medium-pressure steam generator, and a low-pressure steam generator.
[0024]
If the devices divided into the steam generators are arranged in accordance with the macro flow order of the steam, the low-pressure steam generator is composed of a low-pressure economizer 21, a low-pressure evaporator 22, a low-pressure superheater 23, and the like. The generator includes a medium-pressure economizer 24, a medium-pressure feedwater pump 25, a medium-pressure evaporator 26, a first reheater 27, a second reheater 28, and the like.
[0025]
The high-pressure steam generator includes a high-pressure first economizer 29, a high-pressure feedwater pump 30, a high-pressure second economizer 31, a high-pressure evaporator 32, a high-pressure first superheater 33, a high-pressure second superheater 34, and the like. Have been.
[0026]
The steam and high-temperature water generated in the high-pressure steam generator, the medium-pressure steam generator, and the low-pressure steam generator of the exhaust heat recovery boiler 20 serve as high-pressure steam that becomes cooling steam for the steam turbine plant 40 and the gas turbine plant 10 described below. The exhaust gas is supplied to the cooling steam supply path 14 and the like, the details of which will be described later.
[0027]
In the present embodiment, the gas turbine plant 10 and the exhaust heat recovery boiler 20 configured as described above are combined into one set of an array configuration, and the sets are arranged in two lines (two sets) in parallel as illustrated. This is combined with a single steam turbine plant 40.
[0028]
That is, reference numeral 40 denotes a steam turbine plant, in which a high-pressure turbine 41 to which high-pressure steam is supplied through a route * 2 shown in the drawing from the high-pressure second superheater 34 of the exhaust heat recovery boiler 20, An intermediate-pressure turbine 42 supplied with medium-pressure steam from the reheater 28 via a path * 3, and an exhaust of the medium-pressure turbine 42, and a low-pressure turbine supplied with low-pressure steam from the low-pressure superheater 23 via a path * 4. It is constituted by a turbine 43.
[0029]
As for the route * 3, the reheated steam from the exhaust heat recovery boilers 20 of the respective series merges and is supplied to the intermediate pressure turbine 42 as shown in the figure, but the high pressure superheated steam of the route * 2 and the route * 4 The low-pressure superheated steam is supplied to the high-pressure turbine 41 or the low-pressure turbine 43 by merging the two series in the same manner as in the route * 3, though not shown.
[0030]
The exhaust gas of the low-pressure turbine 43 is condensed by a condenser 44 provided downstream thereof, and is circulated to the exhaust heat recovery boiler 20 via a boiler feed pump 45 and a ground condenser 46 in order.
[0031]
Reference numeral 51 denotes a generator driven by the gas turbine plant 10, and 52 denotes a generator driven by the steam turbine plant 40.
[0032]
As described above, various devices have been schematically described. In the present embodiment, the cooling device 16 is disposed in the cooling steam supply path 14 that supplies the cooling steam to the high temperature portion 11a of the gas turbine 11 in each system, and the exhaust gas is discharged. The heat recovery boiler 20 communicates with the high-pressure water supply path 36 as shown by a path * 1 from the medium-pressure and second-pressure economizers 24 and 31, and the heat is reduced by the temperature-reducing device 16 into high-pressure exhaust, which is cooling steam. Water is sprayed to lower the temperature of the cooling steam.
[0033]
In addition, here, as the route * 1, there are shown two routes, one from the medium-pressure economizer 24 and the other from the high-pressure second economizer 31, but if both routes are used together, Needless to say, it may be switched to use only one of them.
[0034]
The present embodiment is configured as described above, and the cooling of the high temperature portion 11a of the gas turbine 11 and the transition piece cooling portion 13a of the combustor 13 in the steady state are performed as follows.
[0035]
That is, the high-pressure exhaust gas of the high-pressure turbine 41 is supplied through the cooling steam supply path 14, and a part of the high-pressure exhaust gas is branched on the way to reach the combustor 13 from the cooling steam branch path 15, and cools the transition piece cooling unit 13 a. The remaining portion that has not been diverted directly passes through the cooling steam supply path 14 to the gas turbine 11 where it is cooled in the high-temperature portion 11a.
[0036]
The temperature of the high-pressure exhaust gas exiting the high-pressure turbine 41 is about 370 ° C. as an example of the temperature drop, and when exposed to steam at this temperature, the movable parts such as the turbine blade and its disk have particularly severe heat-resistant conditions. Requires expensive materials to clear it, and the economic conditions are worse.
[0037]
Moreover, in this embodiment, the gas turbine plant 10 and the exhaust heat recovery boiler 20 are configured as one set, and the steam generated in the plurality of sets of the exhaust heat recovery boilers is assembled and supplied to the steam turbine. Since the multi-shaft combined cycle power plant is operated at an unbalanced output due to a decrease in the function of one of the gas turbines 11, the steam supplied to the steam turbine plant 40 In some cases, the exhaust temperature of the high-pressure turbine becomes abnormally high due to the decrease in the amount, and the heat resistance of the disk becomes extremely problematic as well as the heat resistance of the combustor and the blade.
[0038]
However, since the high-temperature water supplied from the medium pressure economizer 24 and the high-pressure second economizer 31 and the high-temperature water supply path 36 from the exhaust heat recovery boiler 20 is 100 to 300 ° C. Is sprayed into the high-pressure exhaust gas by the temperature reducing device 16, the temperature of the cooling steam is greatly reduced, and a relatively inexpensive and easily available material for manufacturing the moving parts such as the turbine blade and its disk. And economic conditions will improve significantly.
[0039]
In addition, since the transition piece cooling portion 13a of the combustor 13 is a fixed structure, a relatively inexpensive material can be used even under the same 370 ° C. temperature condition. There is no need to mix pressure steam.
[0040]
The cooling steam that has cooled the high temperature portion 11a of the gas turbine 11 is recovered by the second reheater 28 via the gas turbine cooling steam recovery path 37, and also cools the transition piece cooling portion 13a of the combustor 13 to cool the cooling steam. Reaches the outlet side of the second reheater 28 via a transition pipe cooling steam recovery path 38, and is supplied to the medium-pressure turbine 42 together with other steam heated via the second reheater 28 and collected. You.
[0041]
As described above, according to the present embodiment, the cooling steam for cooling the high-temperature portion 11 a of the gas turbine 11 is supplied to the high-pressure exhaust of the high-pressure turbine 41 from the medium-pressure economizer 24, the high-pressure second economizer 31, and the like. And using the cooling steam at a reduced temperature, even when the gas turbine 11 is operated at an unbalanced output in a multi-shaft combined cycle power plant, the high temperature portion 11a of the gas turbine 11 The heat resistance requirement can be cleared, and the production cost of the turbine can be greatly reduced.
[0042]
Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to these embodiments, and various modifications may be made to the specific structure within the scope of the present invention. Nor.
[0043]
【The invention's effect】
According to the present invention, a plurality of combinations of a gas turbine and an exhaust heat recovery boiler using the exhaust gas of the gas turbine as a heat source are provided in a plurality of rows, and the steam generated from each exhaust heat recovery boiler is collected and supplied to a single steam turbine. In a multi-shaft combined cycle power plant, a cooling device is provided in a cooling steam supply path that supplies high-pressure steam turbine exhaust as cooling steam to the high-temperature section of each gas turbine, and a medium pressure economizer or A high-pressure water is supplied from at least one of the high-pressure economizers to reduce the temperature of the cooling steam, and a high-temperature steam turbine exhaust gas selected as a cooling medium of a high-temperature portion of the gas turbine is cooled by a temperature reducing device. The cooling is performed by spraying and adding high-temperature water to lower the temperature of the cooling steam and supplying it to the high-temperature portion of the gas turbine.
[0044]
Thus in the present invention, by using as the cooling steam after having quantity to reduce the temperature over a sufficient temperature reducing device a high pressure exhaust, significantly the temperature of the high-pressure exhaust and reliably reduced, the cooled gas turbine hot section striking the parts are of the employable materials that reduce the heat resistance was able to allow the implementation of stable cooling without reducing the overall efficiency as a multi-shaft combined cycle power plant.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing an outline of a multi-shaft combined cycle power plant according to an embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 gas turbine plant 11 gas turbine 11 a high temperature section 12 air compressor 13 combustor 13 a transition piece cooling section 14 cooling steam supply path 15 cooling steam branch path 16 temperature reducing device 20 exhaust heat recovery boiler 21 low pressure economizer 22 low pressure evaporator 23 Low-pressure superheater 24 Medium-pressure economizer 25 Medium-pressure water supply pump 26 Medium-pressure evaporator 27 First reheater 28 Second reheater 29 High-pressure first economizer 30 High-pressure water pump 31 High-pressure second economizer 32 High-pressure evaporator 33 High-pressure first superheater 34 High-pressure second superheater 35 Medium-pressure steam supply path 36 High-temperature water supply path 37 Gas turbine cooling steam recovery path 38 Tail cooling steam recovery path 40 Steam turbine plant 41 High-pressure turbine 42 Medium Pressure turbine 43 low-pressure turbine 44 condenser 45 boiler feed pump 46 ground condenser 51 generator 52 generator

Claims (1)

A multi-shaft combined cycle power plant in which a combination of a gas turbine and an exhaust heat recovery boiler using the exhaust gas of the gas turbine as a heat source is provided in a plurality of rows, and the steam generated from each exhaust heat recovery boiler is collected and supplied to a single steam turbine. In the cooling steam supply path for supplying high-pressure steam turbine exhaust as cooling steam to the high-temperature section of each gas turbine, a cooling device is disposed, and the cooling device is provided with at least one of a medium-pressure economizer and a high-pressure economizer. A multi-shaft combined cycle power plant, wherein high-pressure water is supplied from one of the two sides to reduce the temperature of the cooling steam.

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