WO1999037891A1

WO1999037891A1 - Combined cycle power plant

Info

Publication number: WO1999037891A1
Application number: PCT/JP1998/000262
Authority: WO
Inventors: Kazuhiko Takaoka; Sadakazu Goto; Hiroyuki Yamamoto
Original assignee: Mitsubishi Heavy Industries, Ltd.
Priority date: 1996-07-24
Filing date: 1998-01-23
Publication date: 1999-07-29
Also published as: JPH1037714A; JP3825091B2

Abstract

A combined cycle power plant which performs preferable mixing when a steam having cooled a high temperature portion being cooled, of a gas turbine to be raised in temperature, is mixed with other steams, ensures safety for downstream equipments, and stably operates over a long time. A mixing pipe (700) is provided, in which an outlet steam from a steam cooling system (400), which causes a high temperature portion being cooled, of a gas turbine (101) to be cooled by steam, is mixed with a bypass steam and the like, and the outlet steam leaving the steam cooling system (400) after heated when it cooled the high temperature portion being cooled, of the gas turbine (101), and the bypass steam and the like, having not been introduced into the high temperature portion being cooled, but bypassed in order to control a flow rate and temperature of a steam introduced into the high temperature portion being cooled, are introduced into the mixing pipe (700) to be mixed with each other, so that a mixed superheated steam having uniform pressure, temperature and the like is formed to free downstream equipment from adverse influence.

Description

Description Combined cycle power plant Technical field

The present invention relates to a combined cycle power plant combining a gas turbine plant and a steam turbine plant.

^ View: Technology

A combined cycle power generation plant is a power generation system that combines a gas turbine plant and a steam turbine plant. It is a power generation system that has been effectively collected and used, and has recently been particularly spotlighted.

In this combined cycle power plant, research and development has been promoted with one point for improving efficiency in terms of how high the temperature range of the gas turbine can be raised.

On the other hand, a cooling system must be provided for the formation of the high-temperature region in view of the heat resistance of the turbine structure, and air has been conventionally used as a cooling medium in this cooling system.

As long as air is used as the cooling medium, even if a high temperature range can be achieved, the power loss required to raise the air required for cooling to the required pressure with its own air compressor, and Considering both the fact that the air used for cooling components is finally mixed into the turbine flow path through which hot gas passes, thereby lowering the average gas temperature and reducing the energy possessed by the gas. However, further improvements in thermal efficiency have not been expected. In order to solve this problem and further improve the efficiency, a gas turbine has been proposed which employs steam instead of the above-described air as a cooling medium. As an example, there is one disclosed in Japanese Patent Application Laid-Open No. H05-166390. However, the technology disclosed in Japanese Patent Application Laid-Open No. H05-169390 does not disclose the concept of employing steam as a cooling medium for gas turbines, but has devised and solved the details. There are many issues that need to be addressed. For example, steam heated to a high temperature by cooling the high-temperature cooling section of a gas turbine is combined with steam supplied from a reheater and introduced into a medium-pressure turbine. It has only been shown as a working steam supply system, and no consideration or consideration has been given to the point of how and where it will be merged. It is the current situation.

In other words, attempts to cool the high-temperature cooling section of a gas turbine with steam are still in a trial-and-error stage, and there are many problems that need to be clarified and solved. As described above, in addition to the technique disclosed in Japanese Patent Application Laid-Open No. H05-166390, as a conventional technique, the study of the mixing of a plurality of steams to be introduced into a medium-pressure turbine is studied in particular. There is no awareness of the problem.

However, the steam, which is cooled by the high-temperature cooling section of the gas turbine as described above and has a high temperature, and the steam supplied from the reheater have different conditions such as pressure and temperature. If the mixture is introduced into the medium-pressure turbine with the proper mixing, steam at a higher or lower temperature than the set temperature is injected into the turbine as it is, May cause damage. In addition, if a structure is adopted in which a plurality of steam to be mixed are brought to the vicinity of the medium-pressure turbine as pipes, if the amount of pipes is large, the cost will increase immediately. Furthermore, there is a concern that a temperature difference may occur in the piping and the pipe may be cracked due to thermal stress. Disclosure of the invention

The present invention prevents the occurrence of such a problem when mixing a plurality of steams, The purpose is to ensure the safety of the equipment and to provide equipment that operates stably for a long time.

In order to achieve the above object, the present invention combines a gas turbine plant and a steam turbine plant, and comprises an exhaust heat recovery boiler that generates steam for driving a steam turbine using exhaust heat from a gas turbine, A combined cycle power plant configured to provide a steam cooling system for cooling a high-temperature cooled portion of the gas turbine with steam, and to recover superheated steam from the steam cooling system to the steam turbine; To provide a combined cycle power plant provided with a mixing pipe for mixing the outlet steam and the bypass steam of the gas turbine, and the reheated by cooling the high temperature cooled part of the gas turbine, and the outlet steam coming out of the steam cooling system To the high-temperature cooled section to control the flow rate and temperature of the steam introduced into the high-temperature cooled section. By introducing the bypass steam that has bypassed without being introduced into the mixing pipe and mixing it, a mixed superheated steam with uniform pressure, temperature, etc. is formed, and this mixed superheated steam is used as the downstream steam. This is to be recovered by a turbine, for example, a medium pressure turbine.

As described above, according to the present invention, a plurality of steams having different conditions such as pressure and temperature are aggregated to form a mixed superheated steam having a uniform condition, and the mixed superheated steam is formed into a downstream steam turbine, for example, a medium-pressure turbine. Because of this, unnecessary troubles such as steam turbine damage due to unstable steam conditions and pipe cracking can be avoided. Further, according to the present invention, the mixing pipe includes a steam inlet from a pipe end, and steam inlets from a plurality of pipe sides, and the inlets from the pipe sides are spaced apart in the pipe longitudinal direction. Provided is a combined cycle power plant in which adjacent inlets are arranged at an angle to each other in the circumferential direction, and the installation position of the steam inlet is determined from the pipe end and from the pipe side. In addition, those from the side of the pipe are spaced from each other in the longitudinal direction of the pipe and the adjacent ones are angled in the circumferential direction. A plurality of vapors with different conditions can be mixed well so as to have uniform conditions. As described above, according to the present invention, when forming the mixed superheated steam, by specifying the positional relationship of the plurality of steams entering the mixing pipe, it is possible to reliably promote uniform mixing of the plurality of steams having different conditions, The stability and reliability of the system were obtained by securing the stability of the steam turbine described above. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a system diagram of a combined cycle power plant according to one embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of the mixing tube 700 of FIG. 1 in detail. BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to FIGS.

100 is a gas turbine plant, which burns the gas turbine 101, the air compressor 102 driven by the gas turbine 101, and the compressed air supplied from the air compressor 102 together with fuel. The combustor 103 is configured as main equipment.

Reference numeral 200 denotes an exhaust heat recovery poirer, which uses the exhaust gas of the gas turbine 101 as a heating source, and mainly includes a high-pressure steam generator 201, a medium-pressure steam generator 202, and a low-pressure steam generator 203. It is configured as a main part.

Reference numeral 300 denotes a steam turbine plant, which is a high-pressure turbine 301 supplied with high-pressure steam from the exhaust heat recovery boiler 200, and a medium-pressure turbine supplied with steam from a steam recovery system 405, which will be described later. A low-pressure turbine 303 supplied with low-pressure steam from 302 and the exhaust heat recovery poir 200 is constituted as a main device.

Reference numeral 400 denotes a steam cooling system, which is a cooling steam supply system 401 connected to the exhaust part 304 of the high-pressure turbine 301, and which branches off from the cooling steam supply system 401 and the combustor 103. A first steam cooling system 402 that cools the gas turbine 101 and a high-temperature cooled part of the gas turbine 101 branched from the cooling steam supply system 401 similarly to the first steam cooling system 402. The second and third steam cooling systems 403 and 404 are configured as main equipment. Reference numeral 500 denotes a bypass system, which is arranged in parallel with each of the first to third steam cooling systems to control the flow rate and temperature of steam introduced into the 402, 403, and 404. The first, second, and third bypass systems 501, 502, and 503 are provided.

700 is a mixing pipe, which has a steam inlet 701 at the end of the pipe, and a plurality of steam inlets 702, 703, 704, 705 at the side of the pipe. The steam inlet 701 at the end communicates with the second and third steam cooling systems 403, 404 for cooling the high-temperature cooled part of the gas turbine 101, and The steam inlet 702 communicates with the first steam cooling system 402 for cooling the combustor 103, and the other steam inlets 703, 704, 705 bypasses the first to third steam cooling systems 402, 403, 404 and flows through the first to third bypass systems 501, 520, 503 It is supplied with bypass steam.

Reference numeral 706 denotes a steam outlet provided at a pipe end opposite to the steam inlet 701, which communicates with the inlet of the intermediate-pressure turbine 302 through a steam recovery system 405.

The steam inlets 72, 703, 704, and 705 on the side of the tube are spaced apart in the longitudinal direction of the tube and are arranged at an angle of 90 degrees in the circumferential direction. You. Here, there are four steam inlets at the side of the pipe, from 702 to 705, which are separated from the upstream and downstream, and are arranged at an angle of 90 degrees in the circumferential direction. However, the interval and direction apart from this number are not limited to this, and may be changed as appropriate, such as 90 degrees or an intermediate angle, depending on the number and properties of the steam sources to be mixed. Needless to say.

In addition, the position where the mixing pipe 700 is provided is shown only schematically in FIG. 1, but in actuality it is located as close as possible to the outlet of the high-temperature cooled part of the gas turbine 101. Preferably, the arrangement is such that the distance from the steam outlet 706 to the intermediate pressure turbine 302 is as long as possible. Since the present embodiment is configured as described above, the height of the gas turbine 101 The outlet steam from the second and third steam cooling systems 403 and 404 heated by cooling the warm cooled part is supplied from the steam inlet 701 at the pipe end to the mixing pipe 704. The steam and the combustor 103 are cooled, and the steam supplied to the mixing pipe 700 through the first steam cooling system 402 through the steam inlet / outlet 702 at the pipe side is supplied to the mixing pipe 700. Mixing pipes from steam and other steam-carrying populations 703, 704, 705 on the side of the pipe via the first to third bypass systems 501, 502, 503 Each of the bypass steams supplied to the mixing pipe 700 is mixed in the mixing pipe 700 to become mixed superheated steam.

At this time, the outlet steam entering from the steam inlet 700 at the end of the pipe advances in the axial direction of the mixing pipe 700, and the flow of the steam causes the steam inlet 720 on the pipe side and other steam to flow. The steam supplied from the inlets 703 to 705 is separated by the steam inlets 702, 703, 704, and 705 in the longitudinal direction of the mixing tube 700. Are arranged at an angle of 90 degrees in the circumferential direction with each other (or even in the middle), so that mixing is performed sequentially at different positions along the flow direction, and the respective steam inlets Vapors with different conditions coming in from 701, 702, 703, 704, and 705 are mixed well to form a mixed superheated steam with uniform pressure, temperature, etc. be able to.

This mixing is performed by arranging the mixing pipe 700 as close as possible to the outlet of the gas turbine high-temperature cooled part and consolidating each steam immediately after the gas turbine high-temperature cooled part. Since the distance of the path from the mixing pipe 700 to the intermediate pressure turbine 302 can be formed with a margin, the uniformization of the conditions of the mixed superheated steam is further promoted, and the amount of piping material is reduced and the cost is reduced. It greatly contributes to down. In this way, according to the present embodiment, by specifying the positional relationship of a plurality of steams entering mixing pipe 700, the conditions of mixed superheated steam to be recovered by medium-pressure turbine 302 can be made uniform. To prevent damage to the medium-pressure turbine 302 and to avoid unnecessary troubles such as cracks in the piping, and to stabilize the medium-pressure turbine 302 to improve system stability and reliability. In addition to reducing the amount of piping, it greatly contributes to cost reduction.

The present invention has been described above with reference to the illustrated embodiments. It is needless to say that the present invention is not limited to the embodiment, and various modifications may be made to the specific structure within the scope of the present invention.

Claims

The scope of the claims

1. Combination of a gas turbine plant and a steam turbine plant, equipped with an exhaust heat recovery poirer that generates steam for driving the steam turbine by using exhaust heat from the gas turbine, In a combined cycle power plant configured to provide a steam cooling system for cooling by

A combined cycle power plant having a mixing pipe for mixing outlet steam and bypass steam of the steam cooling system.

2. The mixing pipe has a steam inlet from a pipe end and steam inlets from a plurality of pipe sides, and the inlets from the pipe sides are arranged at intervals in the pipe longitudinal direction. 2. The combined cycle power plant according to claim 1, wherein adjacent inlets are arranged at an angle in a circumferential direction.