JP3825088B2 - Combined cycle power plant - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combined cycle power plant that combines a gas turbine plant and a steam turbine plant.
[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 region of the thermal energy is shared by the gas turbine, and the low temperature region is shared by the steam turbine. It is a power generation system that has been collected and used, and has been particularly in the spotlight in recent years.
[0003]
In this combined cycle power plant, research and development has been promoted with the point of increasing the high temperature range as one point for improving efficiency.
[0004]
On the other hand, in order to form a high temperature region, a cooling system must be provided from the viewpoint of heat resistance of the turbine structure, and air has been conventionally used as a cooling medium in this cooling system.
[0005]
However, as long as air is used as the cooling medium, even if a high temperature range can be achieved, the power loss required for boosting the air required for cooling to the required pressure with its own air compressor, and the high temperature gas Considering both the fact that the average gas temperature is lowered by finally mixing the air used for cooling the parts in the turbine passage through which the gas passes, resulting in lowering the energy of the gas. We can't expect any further improvement.
[0006]
In order to solve this problem and further improve the efficiency, there has been proposed one that employs steam instead of the above-mentioned air as the cooling medium of the gas turbine, for example, one disclosed in JP-A-5-163960 has been proposed. It came to be.
[0007]
If the main part of Japanese Patent Laid-Open No. 5-163960 is extracted and shown in FIG. 2, it has the following configuration.
[0008]
A gas turbine plant 11 having a gas turbine 13, an air compressor 18, and a combustor 19 as main components, and an exhaust gas from the gas turbine plant 11 as a heat source, a high pressure drum 20, an intermediate pressure drum 21, and a low pressure drum 22 as main components. The combined cycle power plant 10 includes the exhaust heat recovery boiler 14 and the steam turbine plant 12 mainly including the high pressure turbine 15a, the intermediate pressure turbine 15b, and the low pressure turbine 15c to which steam is supplied from the exhaust heat recovery boiler 14. Has been.
[0009]
The cooling system incorporated here is a steam cooling system 50, and the intermediate pressure steam that has exited from the intermediate pressure drum 21 of the exhaust heat recovery boiler 14 is used as cooling steam to pass through the steam supply path 51 of the gas turbine 13. The cooling steam is led to a steam cooling system 52 provided in the high-temperature cooled part, and the high-temperature cooled part is heated, that is, the cooling steam is heated, that is, given thermal energy, passes through the steam recovery system 53, and enters the steam turbine plant 12. It is supplied to the pressure turbine 15b and effectively recovered.
[0010]
The steam system 60 is a backup system that can supply the backup steam from the high-pressure drum 20 of the exhaust heat recovery boiler 14 via the high-pressure steam line 42 and is used immediately after the gas turbine 13 is started. is there.
[0011]
[Problems to be solved by the invention]
As described above, since the conventional one uses the intermediate pressure steam that has exited the intermediate pressure drum 21 as the cooling steam, the turbine inlet temperature of the gas turbine further increases, or the high temperature coverage of the gas turbine increases. As the cooling section expands and the range of the cooled section of the turbine section expands to the moving blades, stationary blades, and annular sections, the intermediate pressure steam increases the heat load of these high-temperature cooled sections. Due to the limit of the amount of steam generated in the gas turbine, there is a problem that the cooling capacity of the high-temperature cooled part of the gas turbine is insufficient, and the high-temperature cooled part, which is the initial purpose, cannot be sufficiently and reliably cooled. is there.
[0012]
The present invention eliminates such problems in the conventional system, always reliably and sufficiently cools the high-temperature cooled part of the gas turbine, and reliably recovers the amount of heat obtained by this cooling, thereby improving the efficiency. It is an object to provide what is intended.
[0013]
[Means for Solving the Problems]
The present invention has Re resolve all Kunasa the problems described above, combination of a gas turbine plant and a steam turbine plant, comprising a heat recovery steam by utilizing exhaust heat from a gas turbine to generate steam turbine driving steam In addition, in a combined cycle power plant configured to provide a steam cooling system that cools a high-temperature cooled portion of the gas turbine with steam, and configured to cause the steam turbine to recover superheated steam from the steam cooling system, the steam turbine plant is together consist of at least the high-pressure turbine and the low-pressure turbine, and supplies the electrically-out in the high pressure turbine directly the steam cooling system the total amount of the exhaust gas, and directly to the first stage inlet after subsequent steam turbine exiting the same steam cooling system A combined cycle power plant Hot cooled parts of the turbine identifies an exhaust of the high pressure turbine as cooling steam guided to the steam cooling system for cooling steam, quantitative possessed by the high-pressure exhaust led to the whole amount directly the steam cooling system, the pressure, or Using the temperature characteristics, the high-temperature cooled part of the gas turbine is efficiently and adequately cooled , and the exhaust of the high-pressure turbine specified as the cooling steam is subjected to a predetermined work in the high-temperature cooled part. After being supplied, it is supplied directly to the first stage inlet of the subsequent steam turbine without detouring to equipment such as a boiler reheater, so that it is not necessary to install a reheater in the exhaust heat recovery boiler. fully in the steam turbine is obtained by the obtained so that at a predetermined work.
[0015]
The present invention also provides a combined cycle power plant in which the exhaust heat recovery boiler is a three-pressure type of at least high pressure, medium pressure, and low pressure, and cools a high temperature cooled part of a gas turbine with high pressure exhaust from a high pressure turbine. Then, since it is introduced into the intermediate pressure turbine, the reheater is not necessarily provided even if the exhaust heat recovery boiler is a three-pressure type of high pressure, medium pressure, and low pressure.
[0016]
Furthermore, the present invention provides a combined cycle power plant that distributes the exhaust of the high-pressure turbine in parallel to a plurality of cooled parts of the high-temperature cooled part, and the high-pressure exhaust that has exited the high-pressure turbine is diverted, Since it flows through the high-temperature parts to be cooled arranged in parallel, the pressure loss of a specific path is shared only by the shunt that flows through the specific path.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0018]
Reference numeral 101 denotes a gas turbine, reference numeral 102 denotes an air compressor driven by the gas turbine 101, and reference numeral 103 denotes a combustor that burns compressed air supplied from the air compressor 102 together with fuel to drive the gas turbine 101. A generator 104 is driven together with the air compressor 102. The gas turbine plant 100 is configured by the gas turbine 101, the air compressor 102, the combustor 103, and the generator 104.
[0019]
The exhaust gas of the gas turbine 101 is led to the exhaust heat recovery boiler 200 through the exhaust duct 105. The exhaust heat recovery boiler 200 includes a high pressure superheater 204, a high pressure evaporator 205, a high pressure economizer 206, an intermediate pressure superheater 207, a low pressure superheater 208, an intermediate pressure evaporator 209, a high intermediate pressure economizer 210, and a low pressure evaporator. 211, low pressure economizer 212, high pressure evaporator 205, medium pressure evaporator 209, low pressure evaporator 211, high pressure drum 201 connected to low pressure evaporator 211, medium pressure drum 202, low pressure drum 203, etc. Using gas as a heat source, steam of high pressure, medium pressure, and low pressure is generated.
[0020]
301 is a high-pressure turbine, 302 is a medium-pressure turbine or 303 is a low-pressure turbine, and the high-pressure turbine 301 is driven by high-pressure steam supplied from the high-pressure superheater 204 of the exhaust heat recovery boiler 200 via the high-pressure steam line 306, The low-pressure turbine 303 is driven by mixed steam of low-pressure steam supplied from the low-pressure superheater 208 of the exhaust heat recovery boiler 200 via the low-pressure steam line 307 and exhaust of the intermediate-pressure turbine 302 described later.
[0021]
On the other hand, the intermediate pressure turbine 302 does not depend only on the intermediate pressure steam supplied from the exhaust heat recovery boiler 200 via the intermediate pressure steam line 311, but cools the high-temperature cooled part with a steam cooling system 400 described later. The high-pressure turbine 301 supplied from the steam recovery system 405 is driven by steam mainly composed of high-pressure exhaust.
[0022]
The high-pressure turbine 301, the intermediate-pressure turbine 302, and the low-pressure turbine 303 are directly connected to the shaft together with the generator 304, and the steam turbine plant 300 includes the condenser 305 connected to the low-pressure turbine 303.
[0023]
A cooling steam supply system 401 is connected to the exhaust section 310 of the high-pressure turbine 301 and is configured to receive the exhaust from the high-pressure turbine 301.
A first steam cooling system 402 branches from the cooling steam supply system 401 and cools the combustor 103. Reference numeral 403 denotes a second steam cooling system, and reference numeral 404 denotes a third steam cooling system, which are arranged in parallel with the first steam cooling system 402 and branch from the cooling steam supply system 401, respectively, to the gas turbine 101. The high temperature cooled part is cooled.
[0024]
The first, second, and third steam cooling systems 402, 403, and 404 branching in parallel constitute the steam cooling system 400, and the high-temperature cooled parts are cooled using the high-pressure exhaust gas supplied to each as a cooling medium. Thereafter, the coolants are merged again, and supplied to the intermediate pressure turbine 302 via the steam recovery system 405.
[0025]
In the figure, 106 is an air supply system to the air compressor 102, 308 is a cooling water supply system for the condenser 305, and 309 is a water supply system in which the condensate obtained by the condenser 305 is supplied to the exhaust heat recovery boiler 200. Show.
[0026]
As described above, according to the present embodiment, when the high-temperature cooled part of the gas turbine plant 100 is cooled, the high-pressure exhaust, intermediate-pressure exhaust and low-pressure exhaust in the steam turbine plant 300, or the exhaust heat recovery boiler 200 Focusing on the high-pressure exhaust of the high-pressure turbine that is optimal in terms of quantity, pressure, or temperature among high-pressure steam, medium-pressure steam, and low-pressure steam, using substantially the entire amount as a cooling medium, As a result, the amount of heat obtained by cooling the cooled part of the gas turbine plant 100 is brought into the intermediate pressure turbine 302 and recovered without being thrown out of the system, thereby improving the thermal efficiency.
[0027]
That is, among the steams obtained by the exhaust heat recovery boiler 200, first, when considering high-pressure steam, although the amount of steam is satisfactory, the pressure is high, so the high-temperature cooled part of the gas turbine plant 100 has a strong structure. Therefore, the thickness of the portion to be cooled is increased and the thermal stress is increased, and the structural design of the cooled portion is very expensive and difficult.
[0028]
For medium-pressure steam, the amount of steam is insufficient relative to the amount of heat required for the part to be cooled, so it is conceivable to increase the amount of medium-pressure steam by redesigning the boiler side. This results in a conflicting result that the exhaust heat recovery efficiency in the case becomes worse.
[0029]
Further, the low-pressure steam is usually at a pressure lower than the atmospheric pressure of the high-temperature cooled part of the gas turbine plant 100, and the safety design principle that the high-temperature gas of the gas turbine is not leaked to the steam system cannot be observed.
[0030]
This individual pursuit reveals that anything other than high-pressure exhaust is ineligible, but more than that, in the cooling of high-temperature cooled parts of this gas turbine plant, The big discovery here was how well high-pressure exhaust was qualified.
[0031]
Since most of the working steam of the intermediate pressure turbine 302 is supplied from the steam cooling system 400 of the gas turbine plant 100, a reheater in the exhaust heat recovery boiler 200 that is indispensable for this kind of plant is installed. This is not necessary, and the cost is greatly reduced when designing and producing the plant.
[0032]
When directly using the high-pressure exhaust of the high-pressure turbine, it is desirable to suppress the pressure loss in the cooled part of the gas turbine plant 100 as much as possible in order to maintain the plant efficiency. The first, second, and third steam cooling systems 402, 403, and 404 are of course branched in parallel, and the steam flow is paralleled as much as possible in each part to be cooled and pressure loss is suppressed. It was possible to disperse the danger of overheating due to local blockage .
[0033]
Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to this embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention. Absent.
[0034]
【The invention's effect】
As described above, according to the present invention, the entire amount of high-pressure exhaust of a high-pressure turbine that is optimal in terms of quantity, pressure, or temperature is directly guided and used as cooling steam for cooling a high-temperature cooled part of a gas turbine plant. Even if the temperature of the high-temperature cooled part is increased or the range of the cooled part is expanded, it is possible to cope with it, and further, this high-temperature cooled part can be used as a reheater, and the exhaust heat recovery boiler Since there is no need to install a reheater inside, the cost could be greatly reduced in the design and manufacture of the plant.
[0035]
Further, according to the present invention, the exhaust of the high pressure turbine, after a predetermined work at high temperature the cooled portion of the gas turbine, without detour example the device of the reheater or the like of a boiler, a subsequent example medium pressure Since it is directly supplied to the first stage inlet of a steam turbine such as a turbine , it is obvious that no reheater is required in the exhaust heat recovery boiler.
[0036]
According to the invention of claim 2, the reheater that is indispensable as a standard product is omitted because the exhaust heat recovery boiler is a three-pressure type of high pressure, medium pressure, and low pressure. The cost reduction effect due to this is large and remarkable.
[0037]
Furthermore, according to the invention of claim 3 , by forming a plurality of high temperature cooled parts in parallel , the pressure loss in the high temperature cooled parts is suppressed, and the high pressure exhaust of the high pressure turbine is directly used effectively. those that could and to Turkey.
[Brief description of the drawings]
FIG. 1 is a system diagram of a combined cycle power plant according to an embodiment of the present invention.
FIG. 2 is a system diagram of a conventional combined cycle power plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Gas turbine plant 101 Gas turbine 103 Combustor 200 Waste heat recovery boiler 201 High pressure drum 202 Medium pressure drum 203 Low pressure drum 300 Steam turbine plant 301 High pressure turbine 302 Medium pressure turbine 303 Low pressure turbine 400 Steam cooling system 401 Cooling steam supply system 402 1 steam cooling system 403 second steam cooling system 404 third steam cooling system

Claims (3)

A gas turbine plant and a steam turbine plant are combined, and an exhaust heat recovery boiler that generates steam for driving a steam turbine using exhaust heat from the gas turbine is provided, and a high-temperature cooled part of the gas turbine is cooled with steam. In a combined cycle power plant provided with a steam cooling system and configured to cause the steam turbine to recover superheated steam from the steam cooling system, the steam turbine plant is composed of at least a high pressure turbine and a low pressure turbine, and the high pressure turbine the total amount of the exhaust-out directly the guide to the steam cooling system, and of combined cycle power plant, characterized in that the so supplied directly to the first stage inlet after subsequent steam turbine exiting the same steam cooling system. The combined cycle power plant according to claim 1, wherein the exhaust heat recovery boiler is a three-pressure type of at least high pressure, medium pressure, and low pressure.   3. The combined cycle power plant according to claim 1, wherein exhaust gas of the high-pressure turbine is circulated in parallel to a plurality of cooled parts of the high-temperature cooled part.

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