Axial compressor and operation method of the same

1. An axial compressor comprising a liquid drop spray nozzle for feeding liquid drops to an operating fluid of the compressor as intake air, a casing for forming a flow path through which the operating fluid flows down and a plurality of stages, each of which is composed of one continuous rotor blade row and one continuous stator vane row, the axial compressor being structured so that the liquid drops evaporate inside the compressor, characterized in that:

the casing is provided with a cavity therein, and the cavity is formed by an outer casing and an inner casing which is enclosing a periphery of the rotor blade rows at the plurality of stages and forming internally a flow path of the operating fluid, and

another flow path is provided for feeding the operating fluid to the cavity on a downstream side of a region forming the cavity of the inner casing, wherein

the another flow path is a flow path for feeding the operating fluid bled from an intermediate stage of the compressor via a bleed pipe as turbine cooling air for cooling a turbine driven by high-temperature combustion gas and connected to the cavity for feeding a part of the operating fluid to the cavity.

2. The axial compressor according to claim 1 , wherein:

the inner casing is formed by a material with a low coefficient of linear expansion compared with a material of the outer casing.

3. The axial compressor according to claim 1 , comprising:

means for adjusting a flow rate of operating fluid fed to the cavity.

4. The axial compressor according to claim 3 , comprising:

means for adjusting a flow rate of liquid drops fed to the operating fluid by the liquid drop spray nozzle.

5. The axial compressor according to claim 4 , comprising:

measuring means capable of measuring a clearance between an inner peripheral surface of the inner casing and tips of rotor blades at the plurality of stages enclosed and arranged by the inner peripheral surface, and

a control unit, in accordance with a measured value of the clearance measured by the measuring means, for controlling at least one of the means for adjusting a flow rate of the operating fluid fed to the cavity and the means for adjusting a flow rate of the liquid drops fed to the operating fluid.

6. The axial compressor according to claim 3 , comprising:

temperature measuring means for measuring a temperature in the inner casing, and

a control unit, in accordance with a temperature measured by the temperature measuring means, for inferring a clearance between an inner peripheral surface of the inner casing and tips of rotor blades at a plurality of stages enclosed and arranged by the inner peripheral surface and controlling at least either the means for adjusting a flow rate of the operating fluid fed to the cavity or means for adjusting a flow rate of liquid drops fed to the operating fluid.

7. The axial compressor according to claim 1 , wherein:

the flow path is a flow path for feeding a part of turbine cooling air for cooling a turbine driven by high-temperature combustion gas to the cavity.

8. The axial compressor according to claim 1 , wherein:

abradable coating is applied to an inner peripheral side of the inner casing.

9. An operation method of an axial compressor comprising a liquid drop spray nozzle for feeding liquid drops to an operating fluid of the compressor as intake air, a casing forming a flow path through which the operating fluid flows down, and a plurality of stages, each of which is composed of one continuous rotor blade row and one continuous stator vane row, the axial compressor being structured so that the liquid drops evaporate inside the compressor, wherein

the casing is provided with a cavity therein, and the cavity is formed by an outer casing and an inner casing which is enclosing a periphery of the rotor blade rows at a plurality of stages and forming internally a flow path of the operating fluid, and another flow path is provided for feeding the operating fluid to the cavity on a downstream side of a region for forming the cavity of the inner casing, and the another flow path is a flow path for feeding the operating fluid bled from an intermediate stage of the compressor via a bleed pipe as turbine cooling air for cooling a turbine driven by high-temperature combustion gas and connected to the cavity for feeding a part of the operating fluid to the cavity,

the operation method comprising the steps of:

measuring or inferring a clearance between an inner peripheral surface of the inner casing and tips of the rotor blades at a plurality of stages enclosed and arranged by the inner peripheral surface, and

adjusting at least either a flow rate of the operating fluid fed to the cavity or a flow rate of liquid drops fed to the operating fluid in accordance with the measured or inferred clearance.

10. An axial compressor comprising liquid drop feed means for feeding liquid drops to an operating fluid of the compressor, a casing for forming a flow path through which the operating fluid flows down and a plurality of stages, each of which is composed of one continuous rotor blade row and one continuous stator vane row, the axial compressor being structured so that the liquid drops evaporate inside the compressor, characterized in that:

the casing is provided with a cavity therein, and the cavity is formed by an outer casing and an inner casing which is enclosing a periphery of the rotor blade rows at the plurality of stages and forming internally a flow path of the operating fluid, and

a flow path is provided for feeding the operating fluid to the cavity on a downstream side of a region forming the cavity of the inner casing, wherein

the casing is provided with a downstream side cavity through which the operating fluid on a downstream side of the region for forming the cavity of the inner casing flows in on a downstream side of the cavity, and

an interconnection hole for interconnecting the cavity and the downstream side cavity is provided in the outer casing or the inner casing as the flow path for feeding the operating fluid to the cavity.