JPH0882421A - Gas turbine combustor - Google Patents

Abstract

PURPOSE: To improve high temperature characteristics (strength at high temperature, oxidation-resistance, corrosion resistance, etc.) of a gas turbine combustor. CONSTITUTION: A porous ceramic cylinder 5 of an oxide is disposed on a contact surface with a combustion gas in an inner cylinder 1 to deal with oxidation and thermal shock. A dense ceramic cylinder 4 for a general structure is bonded to the back surface of the cylinder 5 into a cladding structure to improve structural strength. Both cylinders 4, 5 are divided into a plural structures to compensate low strength with a volume effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for improving the high temperature characteristics of a premixed combustor inner cylinder of a gas turbine.

[0002]

The thermal efficiency of gas turbines and combined cycles using gas turbines can be significantly improved by increasing the turbine inlet temperature. Therefore, the turbine inlet temperature has been raised by the development of heat-resistant materials and the improvement of cooling technology, but there are plans to further increase the temperature in the future, and in order to respond to this, in addition to the improvement of the cooling structure, Materials having excellent high temperature characteristics (strength, oxidation resistance, corrosion resistance, etc.) are desired. Therefore, attention has been paid to ceramics having excellent heat resistance, and SiC (silicon carbide) for general structure,
Non-oxide ceramics with high strength such as Si ₃ N ₄ (silicon nitride) are used.

[0003]

The high temperature (≧ 1300 ° C.) required for an industrial gas turbine and the long time (≧ 80)
00hr), the SiC that is used conventionally
Non-oxide ceramics for general structure having high strength such as Si ₃ N _{4 and the} like are weak against oxidation and cannot maintain strength for a long time, and thus have a drawback that they cannot withstand long-term operation as described above.

[0004]

In order to solve the above-mentioned conventional problems, the present inventor uses an inorganic adhesive to attach a cylindrical body of oxide-based porous ceramics to the inner surface of the cylindrical body of dense ceramics. A gas turbine combustor in which a joined cylindrical ceramic having a clad structure is provided on a contact surface with a combustion gas in a combustor inner cylinder; and, in addition to the above requirements, a cylindrical body of the dense ceramic. The present invention proposes a gas turbine combustor characterized in that is divided into a plurality of members in the axial direction and the cylindrical body of the porous ceramic is divided into a plurality of members in the axial direction and the circumferential direction.

[0005]

In the first solution, since oxide-based porous ceramics are used on the contact surface with the combustion gas in the inner cylinder of the combustor, it is resistant to thermal shock and long against oxidation. Time stable operation is possible. Further, since a dense ceramic having a relatively high strength is bonded to the outer side thereof, the overall strength is improved.

Further, in the second means for solving the problems, since each ceramic cylindrical body is divided into a plurality of members,
Low strength is supplemented by the volume effect.

[0007]

1 is a longitudinal sectional view showing a premixed combustor according to an embodiment of the present invention. In the figure, (1) is the combustor inner cylinder, (2)
Is a main nozzle, and (3) is a pilot nozzle.

In this embodiment, a cylindrical ceramic having a clad structure in which the cylindrical body (4) of oxide-based porous ceramics is bonded to the inner surface of the cylindrical body (4) of dense ceramics by an inorganic adhesive, It is provided on the contact surface with the combustion gas in the combustor inner cylinder (1). As dense ceramics, Al ₂ O ₃ (alumina), 3Al ₂ O ₃ .2SiO
_As oxide-based porous ceramics such as ₂ (mullite) and Si ₃ N ₄ (silicon nitride), Al ₂ O ₃ (alumina) and ZrO ₂ (stabilized zirconia) can be used.

In the present embodiment, the two cylindrical bodies (4) and (5) are also axially divided into a plurality of members (in the illustrated example, three divisions) by dividing lines (6) in the circumferential direction. At the same time, the cylindrical body (5) of the porous ceramic is divided into a plurality of members (not shown) in the circumferential direction by the dividing line along the cylindrical generatrix.

As described above, the inside of the combustor inner cylinder (1) is 130
It is exposed to combustion gas at 0 ° C or higher and becomes an environment where it is very susceptible to oxidation. Therefore, in this embodiment, oxide-based ceramics that are stable against oxidation are used inside the cylindrical ceramics that contacts the combustion gas. Since the inside of the cylindrical ceramics also becomes hot, it is subjected to a high thermal shock due to the rapid temperature drop at the time of emergency stop. In this embodiment, since porous ceramics is used in that portion, the propagation of cracks caused by thermal shock is prevented by the pores existing in the material, and immediate destruction is avoided.

However, porous ceramics have low structural strength. Therefore, in this embodiment, dense ceramics such as Si ₃ N ₄ and Al ₂ O ₃ which have high strength and are also proven as structural ceramics are arranged on the outside at a temperature lower than that on the inside and less affected by oxidation and thermal shock. , Supplements the structural strength.

In general, ceramics are materials in which the overall strength is governed by the weakest intervening defects (microcracks). Therefore, the larger the size (the larger the volume), the higher the probability of including weak defects, and the lower the strength thereof (this is called the volume effect). Therefore, when ceramics are used, it is more advantageous in strength to assemble small parts than to use large ones integrally. Also in this embodiment, the strength is improved by forming the tubular bodies (4) and (5) into an assembly structure of a plurality of divided members. However, the temperature of the outer side of the cylindrical ceramic is lower than that of the inner side, so that the environment is easy in terms of thermal stress, and the outer cylindrical body (4) supports the cylindrical shape (structure) of the combustor. Therefore, the inner cylindrical body (5) is divided into both axial and circumferential directions, whereas the outer cylindrical body (4) is divided only into the axial direction and is divided into circumferential directions. Not divided.

It is advantageous to increase the number of divisions as much as possible. However, in the gas turbine combustor of the present embodiment, the inner cylinder is fixed only by the axial pressing force in order to prevent the local stress from being generated by complicating the method of supporting the ceramic parts. Therefore, it is appropriate that the number of divisions of the limit that can hold the whole by only this force is 3 to 4 divisions in the axial direction and 3 divisions in the circumferential direction.

[0014]

The gas turbine combustor of the present invention can be operated with excellent long-term stability against oxidation and thermal shock, and its structural strength is improved, so that the service life is dramatically extended. Therefore, it is possible to cope with a further increase in the gas turbine inlet temperature.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a premixed combustor according to an embodiment of the present invention.

[Explanation of symbols]

 (1) Inner cylinder (2) Main nozzle (3) Pilot nozzle (4) Dense ceramics (5) Oxide-based porous ceramics (6) Dividing line

Claims (2)

[Claims] 1. A cylindrical ceramic having a clad structure in which a cylindrical body of oxide-based porous ceramics is bonded to an inner surface of a cylindrical body of dense ceramics with an inorganic adhesive, and is used as a combustion gas in a cylinder of a combustor. A gas turbine combustor provided on the contact surface of the gas turbine combustor. 2. The cylindrical body of the dense ceramics is divided into a plurality of members in the axial direction, and the cylindrical body of the porous ceramics is divided into a plurality of members in the axial direction and the circumferential direction. The gas turbine combustor according to claim 1.