JPH04159423A - Gas turbine and change-over method of gas turbine combustor - Google Patents

Abstract

PURPOSE:To enable start control step by step in the stable operation area at the time of change-over with a main combustor by connecting the main combustor to a plural number of combustors for start in parallel between a compressor and a turbine, and controlling a flow amount control valve which is provided in each pipe. CONSTITUTION:A gas turbine is provided with a main combustor 3 and a plural number of combustors for start 8a, 8b,..., which are connected in parallel by a group of pipes 11 between a compressor 1 and a turbine 5. That is, the group of pipes 11 consist of a main pipe 12 which connects the compressor 1, a main combustor 2, and the turbine 5 and a plural number of crossover pipes 10a, 10b, 10c,... which are connected to the main pipe 12 in parallel. The main pipe 12 is provided with an air control valve 2 and a gas control valve 4. On the other hand, each crossover pipe 10a,... is provided with start control valves 9a, 9b,... upstream of the combustors for start 8a,.... At the time of change-over between the combustors for start 8a,... and the main combustor 3, each start control valve 9a,' is operated from open to close or from close to open sequentially.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gas turbine and a gas turbine combustor switching method applied to a gas turbine for power generation and the like.

Conventional technology FIG. 3 shows an example of a conventional gas turbine system for power generation.

In FIG. 3, air compressed by an axial flow air compressor 1 passes through an air control valve 2 and flows into a main combustor 3 such as a coal-fired boiler, a pressurized fluidized bed boiler, or a coal gasifier; It is designed to encourage the generation of high-temperature gas. The generated high-temperature gas is guided to the turbine 5 through the gas control valve 4, expands, and drives the axial air compressor 1 and the generator 6.

The exhaust gas from the turbine 5 flows into the exhaust gas boiler 7, is used to generate steam, and is then released into the atmosphere.

In such a turbine system, conventionally, apart from the main combustor 3, a single startup combustor 8 capable of burning a fuel other than coal, such as kerosene, light oil, heavy oil, or natural gas, and the combustor A single jumper pipe 10 connects the upstream side of the air control valve 2 to the downstream side of the gas control valve 4 so that the single start control valve 9 that controls the compressed air flowing into the air control valve 8 bypasses the main combustor 3. It is installed in

Problems to be Solved by the Invention In the conventional gas turbine having the system configuration described above, when switching from the startup combustor 8 to the main combustor 3, the startup control valve 9 is changed from open to closed. When the state is close to a fully closed state, the cross-sectional wind speed in the starting combustor 8 decreases, and combustion becomes unstable. When combustion becomes unstable, load fluctuations and rotational speed fluctuations occur in the turbine 5, making stable operation impossible at the time of switching.

Also, when switching from the main combustor 3 to the startup combustor 8,
Although the activation control valve 9, the air control valve 2, and the gas control valve 4 operate in reverse, the same unstable phenomenon occurs.

The present invention was made in order to solve the problems of the prior art, and it does not cause load fluctuations or rotational speed fluctuations when switching from the startup combustor to the main combustor and vice versa. It is an object of the present invention to provide a gas turbine and a gas turbine combustor switching method that provide stable behavior.

Means and Action for Solving the Problems The present inventor has investigated the cause of load fluctuations and rotational speed fluctuations during switching from the startup combustor to the main combustor and reverse switching in the conventional gas turbine described above. However, the following became clear.

In other words, when examining the relationship between the air flow rate of the startup combustor and the cross-sectional wind speed, the two are inversely proportional to each other;
Moreover, regardless of the size of the air flow rate ratio, combustion becomes unstable in a region where the cross-sectional wind speed is below a certain level.

Conventional gas turbines use a single startup combustor, so when switching between combustors, operation in an unstable combustion region where the air flow rate is high and the cross-sectional wind speed is low is unavoidable. During operation in this area, load fluctuations and rotational speed fluctuations occurred, impairing stable operation.

Based on the above knowledge, the gas turbine according to the invention of claim 1 includes a main combustor, a plurality of starting combustors, and a main combustor and a plurality of starting combustors between the compressor and the turbine. The configuration includes a group of piping that connects each of the piping groups in parallel, and a plurality of flow rate control valves provided in each of the piping groups. This allows operation within the operating range.

Further, the gas turbine combustor switching method according to the invention of claim 2 provides a main combustor, a plurality of starting combustors, and a plurality of flow control valves in a parallel relationship between the compressor and the turbine. When operating the connected gas turbine according to the invention of claim 1, when switching from the startup combustor to the main combustor or from the main combustor to the startup combustor, the plurality of flow control valves are sequentially operated. It is characterized by operating from open to closed or from closed to open. As a result, when switching from the startup combustor to the main combustor or from the main combustor to the startup combustor, by sequentially extinguishing or igniting multiple startup combustors, the air flow rate becomes large ( , and the cross-sectional wind speed is also large.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a system configuration diagram of a gas turbine according to this embodiment, and FIG. 2 is an explanatory diagram of its operation. In order to simplify the explanation, in FIG. 1, the same components as before are as follows.
The same symbols as in FIG. 3 are used.

As shown in FIG. 1, the gas turbine of this embodiment includes a single main combustor 3, a plurality of starting combustors 8a, 8b,
8c... is provided. The main combustor 2 and a plurality of startup combustors 8a... are connected in parallel between the compressor 1 and the turbine 5 by a pipe group 11, and each of the pipe groups 11 is , a plurality of flow control valves are provided.

To be more specific, the pipe group 11 includes a main pipe 127 connecting the compressor 1, the main combustor 2, and the turbine 5, and a plurality of crossover pipes 10a and 1 connected in parallel to the main pipe 12, respectively.
It consists of 0b, 10c... In the main pipe 12, an air control valve 2 and a gas control valve 4 as flow control valves are provided at upstream and downstream positions of the main combustor 2.

In addition, each crossover pipe 10a... connects an air pipe section of the main pipe 12 from the compressor 1 to the air control valve 2, and a gas pipe section of the main pipe 12 from the gas control valve 4 to the turbine 5. They are connected in parallel. In each crossover pipe 10a..., startup control valves 9a, 9b, 9c... as flow control valves are installed, respectively, located upstream of the startup combustor 8a... .

During normal operation, air compressed by the axial air compressor 1 passes through the air control valve 2 and flows into the main combustor 3, promoting the generation of high-temperature gas. The generated hot gas is led to the turbine 5 through the gas control valve 4 and is engraved to drive the trickle air compressor 1 and the generator 6. The exhaust gas from the turbine 5 flows into the exhaust gas boiler 7, is used to generate steam, and is then released into the atmosphere.

On the other hand, when switching from the starting combustor 8a... to the main combustor 3, or from the main combustor 3 to the starting combustor 8a..., each starting control valve 9a... is sequentially operated. The multiple starting combustors 8a are sequentially extinguished or ignited by operating from open to close or from close to open.

According to such a switching method, as shown in FIG. 2, switching can be made stepwise within a stable operating region where the air flow rate is large and the cross-sectional wind speed is also large.

That is, FIG. 2 shows the relationship between the air flow rate ratio of the startup combustor 8a and the cross-sectional wind speed. As shown by the broken line A in the figure, the air flow rate and the cross-sectional wind speed are inversely proportional to each other. In addition, as indicated by diagonal lines in the figure, there is an area (B) where combustion is unstable when the cross-sectional wind speed is below a certain level.
exists.

Conventional gas turbines use a single startup combustor, so when switching between combustors, the behavior follows the broken line A, resulting in a narrow stable operation range (C) and an unstable combustion region (B). Driving in the car was unavoidable. Therefore, during operation in the region (B), load fluctuations and rotational speed fluctuations occur, impairing stable operation.

In contrast, in the present invention, a plurality of starting combustors 8a,
By sequentially extinguishing or igniting ..., the stable operation range (E) can be expanded and combustion becomes unstable, as shown by the curve in the figure. The operating area can be reduced. Therefore, stable switching action can be obtained without causing load fluctuations or rotational speed fluctuations during switching.

Effects of the Invention As described above, according to the present invention, by using a plurality of starting combustors, starting control can be performed in stages within a stable operating range when switching with the main combustor. An excellent effect is achieved in that a stable switching action can be obtained without causing load fluctuations or rotational speed fluctuations during switching.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of a gas turbine according to the present invention, FIG. 2 is a characteristic diagram showing its operation, and FIG. 3 is a system diagram showing a conventional gas turbine. 1. Compressor, 2. Air control valve, 3. Main combustor, 4
...Gas control valve, 5..Turbine, 6..Generator, 7.
・Exhaust gas boiler, 8a, 8b, gc... Start-up combustor, 9a, 9b, 9C""Start-up control valve, 10a. 10b, 10c...crossover piping, 11...piping group, 12
...Main piping.

Claims (1)

[Claims] 1. A main combustor, a plurality of startup combustors, and piping connecting the main combustor and the plurality of startup combustors in a parallel relationship between the compressor and the turbine. A gas turbine comprising: a group of pipes; and a plurality of flow control valves provided in each of the pipe groups. 2. When operating a gas turbine in which a main combustor, multiple starting combustors, and flow control valves are connected in parallel between the compressor and the turbine, from the starting combustor to the main combustor. or when switching from the main combustor to the startup combustor, the multiple flow control valves are sequentially switched from open to closed.
Or a method for switching a gas turbine combustor, characterized by operating from closed to open.