TECHNICAL FIELD

The present disclosure relates to a gas turbine apparatus and a manufacturing method for the same, and an operation method for the gas turbine apparatus.

BACKGROUND

A component (for example, a turbine rotor) exposed to a high-temperature gas in a gas turbine may be cooled by using a cooling fluid.

For example, Patent Document 1 discloses a gas turbine including a cooler (cooling device) for cooling compressed air. In the gas turbine, compressed air extracted from a compressor is cooled by the cooler, and the cooled air thus generated is supplied to the turbine.

CITATION LIST

Patent Literature

Patent Document 1: JP2017-78362A

SUMMARY

Meanwhile, the gas turbine may be operated to change an output in accordance with a fluctuation in required load. In the gas turbine, a CO concentration in a flue gas tends to increase if a turbine inlet temperature decreases. Thus, in an operation at a relatively low load, it is desired that the turbine inlet temperature is maintained high in order to suppress an increase in CO emission.

In this regard, the gas turbine of Patent Document 1 is provided with a turbine bypass line for discharging the compressed air from the compressor to a turbine outlet by bypassing a combustor and the turbine. It is considered that using the turbine bypass line, a part of the compressed air is caused to bypass the combustor and the turbine, and is discharged without being used as combustion air, making it possible to reduce the combustion air and to increase the turbine inlet temperature.

However, if the above-described turbine bypass line is provided, for example, a pipe forming the turbine bypass line needs to be connected to a casing, increasing the cost of construction.

In view of the above, an object of at least one embodiment of the present invention is to provide a gas turbine apparatus capable of suppressing an increase in CO emission during an operation at a relatively low load, while suppressing an increase in cost and a manufacturing method for the same, and an operation method for the gas turbine apparatus.

A gas turbine apparatus according to at least one embodiment of the present invention includes a turbine configured to be driven by a combustion gas from a combustor, an exhaust passage configured to allow exhaust air from the turbine to flow, an extraction line configured to extract a fluid from a combustor casing, a cooling part disposed in the extraction line and configured to cool the fluid, a return line for returning the fluid from the cooling part to an inside of the combustor casing, the return line being connected to the extraction line downstream of the cooling part, a bypass line for introducing the fluid from the cooling part to the exhaust passage by bypassing the turbine, the bypass line branching from the return line, and a communication state switching part for controlling a communication state between the extraction line and the combustor casing via the return line, and a communication state between the extraction line and the exhaust passage via the bypass line. The communication state switching part is configured to, during an operation of the gas turbine apparatus at a first load, cause the extraction line and the combustor casing to communicate with each other via the return line, and shut off a communication between the extraction line and the exhaust passage via the bypass line, and, during an operation of the gas turbine apparatus at a second load which is lower than the first load, shut off a communication between the extraction line and the combustor casing via the return line, and cause the extraction line and the exhaust passage to communicate with each other via the bypass line.

Moreover, a manufacturing method for a gas turbine apparatus, which includes a turbine configured to be driven by a combustion gas from a combustor, an exhaust passage configured to allow exhaust air from the turbine to flow, an extraction line configured to extract a fluid from a combustor casing, a cooling part disposed in the extraction line and configured to cool the fluid, a return line for returning the fluid from the cooling part to an inside of the combustor casing, the return line being connected to the extraction line downstream of the cooling part, and a bypass line for introducing the fluid from the cooling part to the exhaust passage by bypassing the turbine, the bypass line branching from the return line, according to at least one embodiment of the present invention includes a step of connecting an upstream end of a bypass pipe to the return line or another line communicating with the return line to form the bypass line by the bypass pipe.

Moreover, an operation method for a gas turbine apparatus, which includes a turbine configured to be driven by a combustion gas from a combustor, an exhaust passage configured to allow exhaust air from the turbine to flow, an extraction line configured to extract a fluid from a combustor casing, a cooling part disposed in the extraction line and configured to cool the fluid, a return line for returning the fluid from the cooling part to an inside of the combustor casing, the return line being connected to the extraction line downstream of the cooling part, and a bypass line for introducing the fluid from the cooling part to the exhaust passage by bypassing the turbine, the bypass line branching from the return line, according to at least one embodiment of the present invention includes, during an operation of the gas turbine apparatus at a first load, a step of operating the gas turbine apparatus in a state in which the extraction line and the combustor casing are caused to communicate with each other via the return line, and the communication between the extraction line and the exhaust passage via the bypass line is shut off, and a step of shutting off the communication between the extraction line and the combustor casing via the return line, and causing the extraction line and the exhaust passage to communicate with each other via the bypass line, at a time of switching from the operation of the gas turbine apparatus at the first load to an operation at a second load which is lower than the first load.

According to at least one embodiment of the present invention, a gas turbine apparatus capable of suppressing an increase in CO emission during an operation at a relatively low load, while suppressing an increase in cost and a manufacturing method for the same, and an operation method for the gas turbine apparatus are provided.

