JP5951386B2 - Turbine and turbine cooling method - Google Patents

Description

  Embodiments described herein relate generally to a turbine and a turbine cooling method.

  For example, in a stationary part of a gas turbine in which high-temperature combustion gas flows through a passage part, a stationary blade (hereinafter referred to as a “turbine nozzle”) having a nozzle through which cooling air or the like passes is attached to the casing. A shroud segment is attached to the casing for the purpose of protecting against combustion gases and maintaining optimum clearance with the opposing blade tips and minimizing leakage of working fluid from the blade tips. The turbine nozzle and the shroud segment are each cooled by cooling air or the like so that the temperature is equal to or lower than the allowable temperature of the material.

Japanese Patent No. 4698847

  When mounting the shroud segment, it is necessary to form a hook portion for holding the shroud segment in the casing, a hook portion for holding the turbine nozzle in the shroud segment, etc., and a large space is required for the configuration. I need. Moreover, when cooling a turbine nozzle and a shroud segment, it is necessary to form each cooling passage, and the routing of a cooling passage becomes complicated. Furthermore, since the flow rate of cooling air or the like increases or cooling air or the like leaks from a hook portion where the turbine nozzle and the shroud segment are fitted, it cannot be said that the cooling efficiency is good.

  The problem to be solved by the invention is to provide a turbine and a turbine cooling method capable of operating efficiently.

In the turbine according to the embodiment, the working fluid is CO ₂ obtained through a heat exchanger and a combustor, and the cooling fluid is CO ₂ obtained from the middle of the flow path in the heat exchanger . A casing that constitutes a stationary part; and a stationary blade that is attached to the casing, wherein the stationary blade has CO ₂ as the cooling fluid flowing from the casing side toward the inner ring side of the stationary blade, and the inner ring And a second cooling passage that has a first cooling passage that flows toward the casing side and that continues to flow CO ₂ that has turned back at the inner ring and flows toward the casing side, and has a function of a shroud segment. Having an extension .

The block diagram which shows an example of schematic structure of the thermal power generation system which concerns on one Embodiment. FIG. 2 is a cross-sectional view showing a configuration example of a part of a cooling mechanism applied to a stationary part of a turbine included in the thermal power generation system of FIG.

  Hereinafter, embodiments will be described with reference to the drawings.

In recent years, realization of a thermal power generation system with high environmental harmony that can use CO ₂ as a working fluid and a cooling fluid of a turbine and can simultaneously generate power and separate and collect CO ₂ has been studied.

For example constitute a circulation system for oxyfuel combustion with CO ₂ supercritical pressure, by effectively utilizing the CO _2, it is possible to realize a zero emission system which does not emit NO _x.

In such a thermal power generation system, for example, natural gas (methane or the like) and oxygen are introduced into a combustor and burned, and power is generated by rotating a turbine using high-temperature CO ₂ generated thereby as a working fluid. The exhausted gas (CO ₂ and water vapor) is cooled by a heat exchanger, and after moisture is separated, CO ₂ is compressed by a high pressure pump to obtain high pressure CO ₂ , most of which is heated by a heat exchanger. The remaining high pressure CO ₂ is recovered and used for other applications while being circulated to the combustor.

  FIG. 1 is a block diagram illustrating an example of a schematic configuration of a thermal power generation system according to an embodiment.

The thermal power generation system shown in FIG. 1 is an environmentally friendly thermal power generation system that uses CO ₂ as a working fluid of a turbine and can simultaneously generate power and separate and collect CO ₂ . In this thermal power generation system, a oxyfuel combustion circulation system using supercritical pressure CO ₂ is configured, and a zero emission system that does not emit NO _x is realized by effectively using CO ₂ .

  The thermal power generation system shown in FIG. 1 has a combustor 1, a turbine 2, a generator 3, a heat exchanger 4, a cooler 5, a moisture separator 6, and a high-pressure pump 7 as main components. The combustor 1 may be integrated with the turbine 2.

The combustor 1 introduces high-pressure CO ₂ obtained by recycling from the exhaust gas of the turbine 2, and introduces and burns fuel methane and oxygen to generate high-temperature (for example, about 1150 ° C.) CO ₂ .

The turbine 2 introduces high-temperature CO ₂ generated from the combustor 1 into the turbine as a working fluid, performs expansion work, and rotates the rotor through the moving blades, while the middle of the flow path in the heat exchanger 4. Low temperature (for example, about 400 ° C) CO ₂ is introduced into the turbine as a cooling / seal fluid, and a sealing process is performed to cool the rotor blades and their surroundings (inner casing, etc.) and prevent leakage of the working fluid to the outside. Then, the gas (CO ₂ and water vapor) after the expansion work and the cooling / sealing process are discharged.

  The generator 3 is arranged coaxially with the turbine 2 and generates power according to the rotation of the turbine 2.

The heat exchanger 4 takes heat from the gases (CO ₂ and water vapor) exhausted from the turbine 2 by heat exchange, and gives heat to the CO ₂ introduced again into the turbine 2. In this case, the heat exchanger 4 supplies, for example, about 700 ° C. CO ₂ to the combustor 1, and supplies, for example, about 400 ° C. CO ₂ obtained from the middle of the flow path in the heat exchanger 4 to the turbine 2. To do.

  The cooler 5 further cools the gas deprived of heat by the heat exchanger 4.

The moisture separator 6 separates moisture from the gas cooled by the cooler 5 and outputs CO ₂ from which moisture has been removed.

The high-pressure pump 7 compresses the CO ₂ from which moisture has been removed by the moisture separator 6, outputs high-pressure CO ₂ , and supplies most of it to the heat exchanger 4 for turbine reintroduction, The remaining high pressure CO ₂ is supplied to other equipment.

In such a configuration, when high-pressure CO ₂ obtained by recycling from the exhaust gas of the turbine 2 is introduced into the combustor 1 and fuel methane and oxygen are introduced and burned, high-temperature CO ₂ is generated. The high-temperature CO ₂ generated from the combustor 1 is introduced as a working fluid from the upper upstream side of the turbine 2, while the low-temperature CO ₂ supplied from the middle of the flow path in the heat exchanger 4 is It is introduced as cooling fluid / seal fluid from the lower side of the upstream stage. The high-temperature CO ₂ performs expansion work in the turbine 2 and rotates the turbine through the moving blades, while the low-temperature CO ₂ cools and seals the moving blades and their peripheral parts (inner casing, etc.). When the rotor of the turbine 2 rotates, the generator 3 generates power.

The gas (CO ₂ and water vapor) that has finished the expansion work and cooling / sealing process is discharged from the turbine 2, deprived of heat by the heat exchanger 4, further cooled by the cooler 5, and the moisture separator 6. After the water is separated by the above, CO ₂ from which the water has been removed is taken out. The CO _{2 from} which moisture has been removed by the moisture separator 6 is compressed by the high-pressure pump 7 and output as high-pressure CO ₂ , most of which is supplied to the heat exchanger 4 for turbine reintroduction, The remaining high-pressure CO ₂ is supplied to other facilities. The high pressure CO ₂ supplied to the heat exchanger 4 is supplied with heat by the heat exchanger 4 and supplied to the combustor 1, and high pressure CO ₂ having a temperature lower than that of the high pressure CO ₂ is supplied to the turbine 2. The

With such a configuration, without providing facilities to separate and recover the CO ₂ a (CCS) separately, can be recovered high pressure CO ₂ of high purity. Further, the recovered high-pressure CO ₂ can be stored and used effectively such as being applicable to EOR (Enhanced Oil Recovery) used in oil mining sites.

FIG. 2 is a cross-sectional view showing a configuration example of a part of a cooling mechanism applied to a stationary part of the turbine 2 included in the thermal power generation system of FIG. In addition, the arrow shown with the broken line in FIG. 2 represents the flow of the cooling fluid (low-temperature CO ₂ ).
As shown in FIG. 2, the turbine 2 in this embodiment is a single-flow turbine that uses high-temperature CO ₂ as a working fluid and low-temperature CO ₂ as a cooling fluid. A rotor (rotating body) 11 on which the axle is supported by a thrust bearing, and a casing (stationary portion) 12 surrounding the rotor 11.

  The rotor 11 includes a plurality of stages of moving blades 14 along the axial direction. The casing 12 constitutes a stationary part of the rotor 11, and includes a plurality of stages of stationary blades 15 arranged in accordance with the positions of the plurality of stages of moving blades 14 on the rotor 11 side. A stationary vane diaphragm (inner ring) 15 a is provided so as to face each other, and an end portion of the stationary vane diaphragm (inner ring) 15 a facing the rotor 11 is close to the surface of the rotor 11. Further, the stationary blade 15 has a stationary blade outer wall 15 b attached to the casing 12.

Further, the stationary blade 15 has a stationary blade outer wall extension 15c having a cooling passage through which a cooling fluid flows and having a function of a shroud segment. The stationary blade outer wall extension 15c protects the casing 12 from the heat of the high temperature working fluid (high temperature CO ₂ ) along the axial direction of the rotor 11 and adjusts the clearance of the portion through which the working fluid passes. It has the function of

  The stationary blade outer wall extension 15c has a structure in which the stationary blade outer wall 15b is extended in the rotor axial direction. The stationary blade outer wall 15b and the stationary blade outer wall extension 15c are integrally formed as a single member. The surface of the stationary blade outer wall extension 15 c facing the end of the moving blade 14 is close to the end surface of the moving blade 14.

The cooling fluid (low-temperature CO ₂ ) introduced into the turbine 2 flows into the cooling passage inside the stationary blade 15 via the cooling passage 12 a processed in the casing 12, and this fluid is the stationary blade diaphragm. After flowing through the (inner ring) 15a, at least a part of the inner ring flows into the cooling passage inside the stationary blade outer wall extension 15c. The fluid after cooling the stationary blade outer wall extension 15c flows into the gas passage, and is discharged and collected from the turbine 2 together with the working fluid.

  In the portion of the stationary blade outer wall extension 15c that faces the tip of the moving blade 14, an uneven shape (labyrinth shape) is formed in order to reduce leakage at the tip of the moving blade 14, Seals may be joined or a wear-resistant or wear-resistant coating may be applied. Further, a thermal barrier coating may be applied to reduce the temperature.

By comprising in this way, the space for attachment of each member can be minimized, and it becomes possible to make a casing size small. In addition, the number of parts can be reduced, and the manufacturing cost can be reduced. Furthermore, it becomes easy to form a cooling passage from the nozzle of the stationary blade 15 to the stationary blade outer wall extension 15c, and the cooling flow rate can be minimized. In particular, CO ₂ used as a cooling fluid has a high thermal conductivity compared to a gas such as air, and has a characteristic of easily depriving heat. Further, since there is no fitting portion such as a hook portion between the stationary blade outer wall 15b and the stationary blade outer wall extension portion 15c, the leakage of the cooling fluid from the portion can be eliminated.

  As described above in detail, according to the embodiment, the turbine can be operated efficiently.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Combustor, 2 ... Turbine, 3 ... Generator, 4 ... Heat exchanger, 5 ... Cooler, 6 ... Moisture separator, 7 ... High pressure pump, 11 ... Rotor, 12 ... Casing, 12a ... Cooling passage, 14 ... moving blade, 15 ... stationary blade, 15a ... stationary blade diaphragm (inner ring), 15b ... stationary blade outer wall, 15c ... stationary blade outer wall extension.

Claims (5)

In a turbine that uses CO ₂ obtained through a heat exchanger and a combustor as a working fluid, while using CO ₂ obtained from the middle of the flow path in the heat exchanger as a cooling fluid,
A casing constituting a stationary part of the turbine;
Comprising a stationary blade attached to the casing,
The stationary blade has a first cooling passage through which CO ₂ as the cooling fluid flows from the casing side toward the inner ring side of the stationary blade, turns back at the inner ring, and flows toward the casing side, and A turbine comprising a second cooling passage having a function of a shroud segment and having a second cooling passage through which CO _{2 which} is turned back at the inner ring and flows toward the casing continues . The stationary blade has an outer wall attached to the casing,
The turbine according to claim 1, wherein the extension portion has a structure in which the outer wall is extended in the rotor axial direction.   The turbine according to claim 2, wherein the outer wall and the extension portion are integrally formed by a single member.   The said extension part is provided with the function which protects the said casing from the heat | fever of a working fluid, and the function which maintains the clearance with a moving blade tip, The Claim 1 characterized by the above-mentioned. Turbine. The CO ₂ obtained through the heat exchanger and the combustor is used as a working fluid, while the CO ₂ obtained from the middle of the flow path in the heat exchanger is used as a cooling fluid, and a casing constituting a stationary part is attached to the casing. A turbine cooling method applied to a turbine comprising a stationary vane,
In the stationary blade, CO ₂ as the cooling fluid flows from the casing side toward the inner ring side of the stationary blade, turns back at the inner ring, and forms a first cooling passage that flows toward the casing side, A turbine cooling method, comprising: a second cooling passage that has a second cooling passage through which CO ₂ that has been turned back at the inner ring and flows toward the casing continues and has a function of a shroud segment .

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