JPS62131927A - Cooling construction of gas turbine combustor tail pipe - Google Patents

Abstract

PURPOSE:To cool efficiently and evenly a tail pipe, by mounting an external wall with a specified interval from the external surface of a combustor tail pipe and forming plural number of hole on the external wall. CONSTITUTION:An external wall 10 is installed with a specified interval from the external surface of the tail pipe of a combustor. Plural number of hole 11 are formed on the external wall 10. Holes 12 are formed on the tail pipe 1. Projected fins 13 are mounted to the external side area of the tail pipe 1 which is not covered with the external wall 10. The air supplied from the holes 11 flows inside the tail pipe 1 through the holes 12 after colliding with the tail pipe 1. Thus, the heat transfer rate of the tail pipe external side is improved and the tail pipe can be cooled evenly and efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a transition piece of a gas turbine combustor, and particularly relates to a cooling structure suitable for a transition piece of a high-temperature gas turbine combustor where the combustor exit gas temperature is high. .

[Background of the invention]

One way to improve the thermal efficiency of a gas turbine power generation system is to increase the temperature at the gas turbine combustor outlet, and development of various elements to cope with the increase in temperature is progressing. In the transition piece, the temperature of the combustion gas flowing inside the transition piece increases, which causes the wall surface temperature to rise, resulting in a problem of reduced lifespan and reliability.

As shown in FIG. 2, the multi-can type combustor transition piece 1 has the largest cross-sectional area at the liner 2, which corresponds to the inlet of the transition piece 1, and the turbine nozzle, which corresponds to the outlet of the transition piece 1. It is minimum on the 3rd side. Since the cross-sectional average flow velocity is inversely proportional to the cross-sectional area, it increases as it approaches the exit of the transition piece 1. There is a relationship α(X:V'' between the heat transfer coefficient α inside the transition piece 1, which controls the wall surface temperature, and the flow velocity V, and the index n is positive, so the heat transfer coefficient inside the transition piece 1 is The value becomes small at the inlet of the transition tube 1 and becomes large at the exit of the transition tube 1, as shown in Figure 3.In the transition tube 1 with such heat transfer characteristics, conventionally, the value is as shown in Figure 4. As shown, air 51 flowing into the liner 2 from the compressor 5 is guided into the casing 8 formed by the transition piece l and the casing 6, and the entire body is cooled by the air 51 flowing outside the transition piece 1. Small-diameter air holes are provided in areas with high heat transfer coefficients, and forced convection cooling of the hole surface and film cooling are performed to flow cooling air along the inner surface of the transition piece 1 to lower the combustion gas temperature near the transition piece 1. However, 1-1 This cooling method creates a high-temperature part in the transition piece 1, and cannot cope with high temperatures.

In JP-A-55-2:1400, in order to strengthen and make the cooling uniform, the transition piece 1 has a double structure, and in the part where the inner heat transfer coefficient is high, the outer wall is made with a hole to allow the air to flow through the air hole. In other parts, forced convection cooling is performed by supplying the air after impingement cooling into the liner 2 through the flow path formed by the inner and outer walls. .

From the perspective of improving the overall performance of the gas turbine, the requirements for the tail pipe cooling method are: (1) the amount of air that cannot be supplied to the liner 2 after cooling the tail is small; and (2) the flow from the compressor 5 to the turbine nozzle 3 is (3) The wall temperature of the transition piece 1 is uniform, and thermal stress is small.

[Purpose of the invention]

An object of the present invention is to provide a structure that increases the heat transfer coefficient outside the transition piece of a gas turbine combustor and cools the transition piece efficiently and uniformly.

[Fake invention]

In the present invention, impingement cooling with high cooling performance is applied to the inner part of the transition piece 1 where the heat transfer coefficient is high, and protruding fins are provided on the outside of the transition piece 1 to other parts where the heat transfer coefficient is small. This improves the cooling performance of the air 51 flowing from the compressor 5 to the liner 2, uniformly cools the transition piece 1, and reduces the amount of air that is used for cooling the transition piece and is not supplied to the liner 2. , the pressure loss from the compressor 5 to the turbine nozzle 3 is reduced.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG. An outer wall 10 is provided near the exit of the transition piece 1. A plurality of air holes 11 are provided in the outer wall 10, and the air flow 52 passes through the tail portion IVc.

The outer wall 10 is designed to prevent air from entering from other than the air holes 11.
It is fixed to the tail tube 1. The air supplied from the air hole 11 collides with the transition piece 1 (after hitting the transition piece 1), it passes through the air hole 12 and enters the transition piece 1.
flows inside the wall, forming a low-temperature air layer near the wall.

The material strength of the transition tube 1 depends on the temperature, and structurally speaking, uneven temperature on the wall surface of the transition tube 1 causes thermal stress. Therefore, in order to ensure the strength and reliability of the transition tube 1, one transition tube is required. ] It is necessary to reduce the wall temperature uniformly. This is achieved by making the heat transfer coefficient distribution on the outside of the transition piece 1 similar to the inside. In the structure shown in Fig. 1, the amount of air used only for cooling the transition piece 1 is reduced by using impingement cooling with a high heat transfer coefficient near the exit of the transition piece 1 and limiting its application range. There is. Since the heat transfer coefficient required for cooling the remaining portion is relatively small, the effect of increasing the heat transfer coefficient by expanding the heat transfer area of the protruding fins 13 installed on the outside of the transition piece 1 and disturbing the flow, Convection heat transfer by the air 51 flowing through the vehicle compartment 8 enables uniform cooling. , (Straight fins are not preferable because the flow direction changes in a complicated manner inside the vehicle. Also, compared to bin fins, straight fins are disadvantageous in terms of thermal stress if they cause temperature unevenness.) Provided with protruding fins. The increase in pressure loss due to this is small and has little effect on the thermal efficiency of the gas turbine as a whole. Examples of the shape of the protruding fin include a cylinder, a polygonal prism, a cone, and a polygonal pyramid.

The impingement cooling section of the present invention not only has the structure shown in FIG.
The structure shown in Fig. 5 reduces the amount of heat input from the impingement, and the air after impingement cooling is guided from the air passage 15 to the turbine cooling air passage, and the air consumed by other equipment, such as oxidizing air in a coal gasifier, is The structure shown in FIG. 6 can be considered, leading to use as a.・ In the figure, 4 is the fuel nozzle, 7 is the outer cylinder, 14 is the slit, 5
0 is combustion gas.

〔Effect of the invention〕

According to the present invention, it is possible to suppress an increase in the wall temperature of one tail tube without impairing the increase in thermal efficiency of the gas turbine due to the increase in temperature.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a combustor transition piece according to an embodiment of the present invention, FIG. 2 is a diagram showing changes in cross-sectional area of a multi-can type combustor transition piece, and FIG. 3 is a diagram showing changes in cross-sectional area of a multi-can type combustor transition piece. Figure 4 is a longitudinal cross-sectional view of a conventional combustor, Figures 5 and 6 are
The figure is a sectional view of a modified example of the impingement cooling section of the transition piece according to the present invention. 1... Tail piece, 10... Outer wall, 11.12... Air hole, 13... Projection fin.

Claims (1)

[Claims] 1. Compressed air pressurized by a compressor and fuel pressurized by a separate system are guided to a combustor liner, combustion proceeds within the combustor liner, and the combustion gas generated here In a gas turbine that obtains output by guiding the transition piece to a turbine through a transition piece, an outer wall is provided that covers at least a part of the transition piece at a predetermined distance from the outer surface of the transition piece, and a plurality of holes are formed in the outer wall. A gas turbine combustor tail, characterized in that a part of the compressed air is caused to flow and collide with an outer surface of the transition piece, and a protruding fin is provided on a part of the outside of the transition piece that is not covered by the outer wall. Cylindrical cooling structure.