JPH0375414A - Gas turbine combustor - Google Patents

Abstract

PURPOSE:To obtain high durability even if heat load is repeated by arranging a shielding cylinder in the inside of a ceramic inner cylinder of a combustor, and inserting a flange projected on the outer periphery of the shielding cylinder to an inner cylinder into the ceramic inner cylinder to support while dividing the shielding cylinder into a plurality of sections along a shaft center line. CONSTITUTION:A shielding cylinder 5 of high heat resistance is located in the inside of an inner cylinder 2 made of ceramic. As the result, a radiation heat transfer quantity to the inner cylinder 2 can be reduced remarkably to effectively control local temperature increase of the inner cylinder 2 so as to protect the ceramic-made inner cylinder 2 from cracks, failure and the like. Since the shielding cylinder 5 is formed of monolith ceramic, or ceramic fiber- contained composite ceramic and the like, and axially divided into a plurality of section is the plane including air holes 8, concentration of thermal stress can be eased even if radiation heat is received to make it high temperature. Thereby it is far superior in thermal durability, compared with the ceramic-made inner cylinder 2 whose circumference is formed integrally, and there is nothing to fear of failure even if high temperature heat is directly received by radiation.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in combustor structures for gas turbines.

(Prior art) Japanese Patent Application Laid-Open No. 56-100233 as a combustor for a gas turbine
As disclosed in the above publication, there is a combustor constructed of a double cylinder consisting of a ceramic inner cylinder and a metal outer cylinder.

By forming a heat insulating layer between the inner cylinder and the outer cylinder, the temperature gradient inside and outside the cylinder is reduced, thereby increasing the durability of the combustor against thermal shock during ignition and the like.

(Problem to be Solved by the Invention) However, in this case, since the inner cylinder and the outer cylinder are connected to each other at both ends, excessive stress is repeatedly applied due to the difference in thermal expansion between them, and the inner cylinder made of ceramic, which is a brittle material, is Cracks may occur in the cylinder.

Also, the properties of the fuel to be burned (aromatic ratio, residual coal ratio, etc.)
When the emissivity of the flame increases significantly due to the mixture ratio (rich mixture combustion region of stratified combustion), the difference in local heat input to the ceramic inner cylinder increases, and the allowable heat due to increased thermal stress and high temperature increases. Cracks and failures may also occur due to stress reduction.

The present invention aims to solve such problems.

(Means for Solving the Problems) Therefore, the present invention arranges a shielding cylinder inside a ceramic inner cylinder of a combustor, and a flange that protrudes from the outer periphery of the shielding cylinder with respect to the inner cylinder. While being inserted into the cylinder for support, the shielding cylinder was divided into multiple parts along the axis.

(Function) Since the shielding tube is placed inside the ceramic inner tube, even if the radiant heat increases, the shielding tube can significantly reduce the amount of secondary radiant heat transfer to the ceramic inner tube. To avoid the danger of cracking and breaking the inner cylinder.

The shielding cylinder is divided into parts in the axial direction, so there is less concentration of thermal stress even when receiving radiant heat, and the inner cylinder is held between flanges to allow free deformation of each other during thermal expansion. This can prevent the occurrence of thermal stress.

(Example) Embodiments of the present invention will be described below based on the drawings.

The ceramic inner cylinder 2 arranged approximately concentrically inside the casing 1 is composed of a surrounding cylindrical part 2a and a dome part 2b forming a ceiling surface, and flanges 3, 3 are provided on the joint surfaces of the two.
is formed.

A shielding cylinder 5 made of monolithic ceramic, ceramic fiber-containing composite ceramic, or the like, which is less brittle than the ceramic inner cylinder 2, is arranged inside the ceramic inner cylinder 2. The shielding cylinder 5 is formed into a substantially cylindrical shape so as to mainly cover the upstream part of the cylindrical part 2a from the inside, and has seven flange 6 projecting outward from the vicinity of its end, and this seven flange 6 is connected to each of the seven flange parts. It is designed to be held between the lunges 3 and 3. The shielding cylinder 5 is divided into a plurality of parts in the axial direction (four divisions in this embodiment) along the plane passing through the primary air holes 7 arranged equally around the inner cylinder 2. Air holes 8 are also formed at positions corresponding to the primary air holes 7.

Note that a secondary air hole 9 is formed in the inner cylinder 2 at a position downstream of the primary air hole 7. A fuel injection valve 10 is arranged at the center of the dome portion 2b of the inner cylinder 2.
0 is pressed against the insertion opening 13 of the dome portion 2b under the compressive force of the spring 11. On the other hand, the casing 1 is inserted into the cylindrical portion 2a of the inner cylinder 2 from the outside (back side) of the flange 3.
The flange 6 of the shielding cylinder 5 is caught between the flanges 3, 3 of the dome part 2b and the cylindrical part 2a, and the compressive force of the spring 11 causes the inner part to be pulled out. The tube 2 and the shield tube 5 are elastically supported between the support arm 15.

A swirler 17 is located around the fuel injection valve 10 and is provided in the dome portion 2b to impart swirling motion to the air introduced into the combustion chamber.
is formed. Moreover, between the casing 1 and the inner cylinder 2,
An annular air passage 18 is formed through which compressed air from a compressor (not shown) passes.

The system is constructed as described above, and its operation will be explained next.

The fuel injected into the combustion chamber from the fuel injection valve 10 is combusted together with the air from the swirler 17 at a relatively rich mixture ratio, and the primary air flows in from the primary air hole 7 and the secondary air hole further downstream. This combustion gas, which gradually shifts to lean combustion while taking in secondary air from 9, flows into a turbine (not shown) and drives the turbine to rotate.

By the way, when using a fuel with a lot of aromatics (such as cracked oil) or a fuel with a lot of residual components (such as heavy oil), or when setting a high mixing ratio in the secondary combustion region, the emissivity of the flame increases, causing becomes extremely hot.

In particular, when ceramic, which is a brittle material, is directly exposed to high heat in this way, the temperature difference between the area around the air hole and other parts increases, and the strength decreases at high temperatures.
There is a risk of cracking and failure occurring within a relatively short period of time.

Such a phenomenon is likely to occur in the main combustion region from the fuel injection valve 10 to the vicinity of the primary air hole 7.

However, in the present invention, since the highly heat-resistant shielding cylinder 5 is located inside the ceramic inner cylinder 2, the amount of radiation heat transferred to the inner cylinder 2 can be significantly reduced, and the local Ceramic inner cylinder 2 effectively suppresses temperature rise.
can be protected from cracking, destruction, etc.

The shielding cylinder 5 is made of monolithic ceramic, composite ceramic containing ceramic fibers, etc., and is divided into a plurality of parts in the axial direction on the surface including the air holes 8, so that it can prevent concentration of thermal stress even if the temperature increases due to radiant heat. Compared to the ceramic inner cylinder 2 whose periphery is integrally formed, it has far superior thermal durability, and there is no fear of damage even if it is directly exposed to high heat due to radiation.

Moreover, the ceramic inner cylinder 2 and the shielding cylinder 5 have a flange 3,
The flange 6 of the shielding cylinder 5 is sandwiched between the shielding cylinder 5 and the flange 6 of the shielding cylinder 5, and the entire structure is elastically supported by the compressive force of the spring 11. Therefore, even if there is a difference in thermal expansion between the two, the flange 6 of the shielding cylinder 5 can be freely deformed. It can release thermal stress and exhibit high durability against thermal stress and mechanical vibration.

<Effects of the Invention> As described above, according to the present invention, since the shielding tube is arranged inside the ceramic inner tube, high radiant heat is prevented from being transmitted to the ceramic inner tube, improving thermal durability. In addition, the shielding cylinder is divided into a plurality of parts in the axial direction to alleviate the concentration of thermal stress, and is also supported by being sandwiched between the inner cylinder via flanges so that they can be freely thermally deformed. Therefore, there is little occurrence of thermal stress due to local high radiant heat or differences in the amount of thermal deformation, and it exhibits high durability even under repeated thermal loads.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Casing, 2... Inner cylinder, 3... Flange, 5... Shield cylinder, 6... Flange, 7, 9... Air hole, 1o... Fuel injection valve, 11 ···spring,
15...Support arm.

Claims (1)

[Claims] A shield tube is placed inside the ceramic inner tube of the combustor, and a flange protruding from the outer periphery of the shield tube relative to the inner tube is inserted into the ceramic inner tube to support the shield tube. A gas turbine combustor characterized by being divided into multiple parts along a core wire.