JP2000039147A - Pilot nozzle for combustor equipped with flexible joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the affection of a thermal stress on the tip end unit of a combustor by absorbing the difference of thermal elongation between the outside and the inside of the same, with respect to a dual system pilot nozzle for the gas turbine combustor employed by switching oil into gas. SOLUTION: An air passage 21 is formed between a cylindrical unit 13 and an outside pipe 14 while a gas passage 22 is formed between the outside pipe 14a and an inside pipe 15 to pass air 34 and gas pilot fuel 32 respectively and inject them from an air injection port 25 and a gas injection port 24, which are equipped at the tip end of a combustor. An oil fuel nozzle 20 is penetrated through the inside pipe 15 and water is passed through the periphery of the nozzle 20 while oil is injected from an oil injection port 26. The temperature of air is 400 deg.C, the temperature of the gas fuel is 15-200 deg.C, the temperature of the water passage is a normal temperature and, accordingly, the difference of thermal elongation is generated between the outside pipe 14 and the inside pipe 15, however, one end of the outside cover 2 is fixed to the fore outside tube 14a the other end of the same is slid on a rear tube 14b and a flexible tube 1 is also contractable whereby the difference of thermal elongation can be absorbed and a stress will not be generated in the tip end unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor pilot nozzle having a flexible joint, and more particularly to a dual-type pilot nozzle for switching between gas fuel and oil fuel of a gas turbine, and incorporating the flexible joint into a thermal expansion pipe. The difference is absorbed and the thermal stress applied to the tip is absorbed.

[0002]

2. Description of the Related Art FIG. 2 is an external view of a combustor of a gas turbine. In FIG. 2, reference numeral 10 denotes a combustor main body, a pilot fuel nozzle 11 is provided at a central portion thereof, and a plurality of main fuel nozzles are provided therearound. A nozzle 12 is provided. An oil fuel 30, a gas fuel 31, a gas pilot fuel 32, and water 33 are supplied to the combustor body 10, and any one of the fuels is burned in the combustor by switching between the gas and the oil fuel to generate a high-temperature combustion gas. And supply it to the gas turbine. At the start of combustion, oil fuel 30 is supplied to pilot nozzle 11 at the center.
Alternatively, the gas pilot fuel 32 is sent and ignited.

FIG. 3 is a sectional view of the tip of the pilot fuel nozzle 11 of the combustor 10 described with reference to FIG. In the drawing, 13 is a cylindrical portion for introducing air, 14 is an outer pipe,
Reference numeral 15 denotes an inner pipe, and an air passage 21 is formed between the inner peripheral surface of the air introduction cylindrical portion 13 and the outer peripheral surface of the outer pipe 14. A gas passage 22 is formed between the inner peripheral surface of the outer pipe 14 and the outer peripheral surface of the inner pipe 15. Further, an oil fuel nozzle 20 is inserted into the inner pipe 15 so that water flows into a surrounding space.

[0004] The air 34 flowing from the air passage 21 is blown obliquely inward from the air injection port 25 at the periphery of the tip as shown in the figure, flows out into the combustor, and flows from the gas passage 22 to the tip. The fuel 32 squirts obliquely outward from the gas injection port 24 at the periphery of the tip. The oil fuel 30 passes through the oil fuel nozzle 20 and is injected into the combustor from the oil injection port 26 at the center of the tip. Oil fuel nozzle 20
The water that has flowed around is sprayed from a tip water spray nozzle (not shown). As described above, the air 34 and the gas fuel 32 or the oil fuel 30 are injected into the combustor main body 10 from the distal end of the pilot fuel nozzle 11, burn, and burn.
The main fuel from 2 is ignited.

FIG. 4 is an enlarged sectional view of the periphery of the tip of the pilot fuel nozzle in FIG. In the figure, the air passage 2
The air flowing in 1 is air extracted from the compressor,
The temperature is about 400 ° C., and the gas fuel flowing through the gas passage 22 on the inner side is also 15 ° to 200 ° C. On the other hand, there is water 33 between the oil fuel nozzle 20 and the inner pipe 15.
Flows into the inner pipe 15 and a considerable temperature difference occurs between the inner peripheral side and the outer side of the inner pipe 15.
A thermal expansion difference occurs between the inner pipe 4 and the inner pipe 15, and thermal stress is applied to the distal end where the outer and inner pipes 14 and 15 are joined, and excessive force is applied particularly to the welded portion 16 at the distal end, and cracks occur. It is easy to do.

[0006]

As described above, in the dual type pilot nozzle in the conventional gas turbine combustor, there is a temperature difference between the outer pipe 14 and the inner pipe 15, and a heat difference exists between the two pipes. A difference in elongation occurs,
The difference in thermal elongation causes an unreasonable stress to be generated in the welded portion 16 at the tip end, and a crack is generated in the welded portion 16. Therefore, some measure for absorbing the difference in thermal expansion between the outer pipe 14 and the inner pipe 15 has been desired more strongly than before.

Accordingly, the present invention employs a dual-type pilot fuel nozzle for a gas turbine that uses gas fuel and oil fuel by switching between them, employing a structure that absorbs the difference in thermal expansion between the outer pipe and the inner pipe. An object of the present invention is to provide a combustor pilot nozzle provided with a flexible joint capable of absorbing a difference in thermal expansion between the two and eliminating an excessive force applied to the tip.

[0008]

The present invention provides the following means for solving the above-mentioned problems.

An outer cylinder and an inner cylinder are arranged concentrically while keeping a predetermined space around them, and gas fuel is allowed to flow through the space so as to be able to be injected from a tip end thereof, and an oil fuel nozzle is provided at the center of the inner cylinder. In the pilot nozzle of the combustor that allows oil fuel to be injected from the front end portion, the outer cylinder has a front and rear divided structure, and the divided portion is connected by a member that can be extended and contracted back and forth. Combustor pilot nozzle with flexible joint.

According to the present invention, since the outer cylinder is divided into two parts at the front and rear, and an extensible member is interposed in the divided portion, the extensible member can be extended even if a difference in thermal expansion occurs between the outer cylinder and the inner cylinder. Is absorbed by stretching. Gas fuel flows through a space formed by the outer inner cylinder and the inner cylinder, an oil fuel nozzle is inserted into the inner cylinder, and water flows around the oil fuel nozzle. The gaseous fuel is at a temperature between 15 ° and 200 ° C.,
Water is at room temperature. Further, air extracted from the compressor flows from the outer periphery of the pilot nozzle tip toward the tip. The temperature of the air is about 400 ° C.

As a result, the temperature of the outer cylinder is considerably higher than that of the inner cylinder, and this temperature difference causes a difference in thermal expansion between the two cylinders. This difference in thermal elongation causes a large thermal stress to occur at the tip of the nozzle where the outer cylinder and the inner cylinder are joined, and cracks have conventionally occurred in the welded portion.
In the present invention, since the difference in thermal expansion is absorbed by the elastic member, no stress is generated at the distal end, and the reliability of the pilot nozzle is improved.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a sectional view of a combustor pilot nozzle provided with a flexible joint according to one embodiment of the present invention. In the figure, the components other than the reference numerals 1 and 2 and 14a, 14b, 17, 18 are the same as those of the conventional structure shown in FIG. 3, so the same reference numerals are used as they are, and detailed description is omitted. The characteristic part of will be described in detail.

In FIG. 1, the outer pipe is divided into a front outer tube 14a and a rear outer tube 14b. 1 is a flexible tube, 2 is an outer cover, which connects these divided parts. Front outer tube 14
A groove 18 is formed on the outer peripheral surface of the end of the outer cover 2, and the protrusion 2 a provided on the inner surface of the end of the outer cover 2 is engaged. The rear end of the outer cover 2 is in contact with a step 17 provided on the outer peripheral surface of the end of the rear outer tube 14b, and is slidably inserted.

The outer cover 2 includes outer pipes 14a and 14
b, the periphery of the connecting portion is cylindrically covered, and the flexible tube 1 has one end inside the front outer tube 14a,
The other end is fixed and attached to the rear tube 14b with bolts or the like. Accordingly, the flexible tube 1 also covers the entire periphery of the connection portion and communicates with the front and rear gas passages 22 to form a gas passage.

In the pilot nozzle to which the flexible joint having the above configuration is applied, the outer pipes 14a, 1
As described in the conventional example, there is a temperature difference between 4b and the inner pipe 15, and when a thermal expansion difference occurs, the thermal expansion of the outer tube 14 is larger than that of the inner tube 15,
The difference in extension slides with the rear outer tube 14b at the rear step 17 in the outer cover 2, and the flexible tube 1 can easily absorb the amount of expansion at both ends due to the elastic structure.

As described above, the difference in thermal expansion caused by the temperature difference between the outer pipes 14a, 14b and the inner pipe 15 is absorbed by the outer cover 2 and the flexible tube 1, so that an excessive force applied to the welded portion at the distal end is generated. It hardly occurs, and the pilot fuel nozzle can be safely operated.

[0017]

The combustor pilot nozzle having a flexible joint according to the present invention has an outer cylinder and an inner cylinder arranged concentrically while maintaining a predetermined space around the outer cylinder, and a gas fuel is caused to flow through the space to form a distal end portion. In a pilot nozzle of a combustor, which is capable of injecting more and injecting an oil fuel through a center portion of the inner cylinder and injecting an oil fuel from a front end portion, the outer cylinder has a front and rear divided structure, Are characterized in that they are connected by a member that can be extended and retracted back and forth.
With such a configuration, the thermal expansion difference generated between the outer cylinder and the inner cylinder is absorbed, the stress generated at the tip of the nozzle can be eliminated, and the occurrence of cracks in the weld at the tip can be prevented. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a flexible joint of a combustor pilot nozzle according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a typical combustor of a gas turbine.

FIG. 3 is a sectional view of a conventional combustor pilot nozzle.

FIG. 4 is an enlarged sectional view of a tip portion of a conventional combustor pilot nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible tube 2 Outer cover 2a Projection part 11 Pilot fuel nozzle 13 Cylindrical part 14 Outer pipe 14a Front outer pipe 14b Back outer pipe 15 Inner pipe 16 Welding part 17 Step part 20 Oil fuel nozzle 21 Air passage 22 Gas passage 23 Water passage 24 Gas injection port 25 Air injection port 26 Oil injection port 30 Oil fuel 32 Gas pilot fuel 34 Air

Claims (1)

[Claims] 1. An outer cylinder and an inner inner cylinder are concentrically arranged while maintaining a predetermined space around the inner cylinder. Gas fuel is allowed to flow through the space so that injection can be performed from a tip end thereof. In a pilot nozzle of a combustor which allows a fuel nozzle to be inserted and a fuel fuel to be injected from a front end portion, the outer cylinder has a front and rear divided structure, and the divided portion is connected by a member which can be extended and contracted back and forth. Combustor pilot nozzle with a flexible joint.