Apparatus to seal with a turbine blade stage in a gas turbine

1. An apparatus configured to seal with a turbine blade stage of a gas turbine, the apparatus comprising:

a casing that at least partially encloses the gas turbine;

an outer shroud configured to be coupled to the casing and circumferentially surround the turbine blade stage; and

an inner shroud configured to circumferentially surround the turbine blade stage to seal with the turbine blade stage and comprising an attachment element configured to be inserted into the outer shroud to couple the inner shroud to the outer shroud, the inner shroud defining a void internal to the inner shroud;

wherein the outer shroud and the inner shroud form a cavity that is in fluid communication with a purge gas supply attached to the casing and supplying cool gas such that the cavity is cooled by the cool gas purging the casing, the cavity being in communication with the attachment element.

2. The apparatus according to claim 1 , wherein a width of the void is greater than a height of the void.

3. The apparatus according to claim 1 , wherein the inner shroud comprises a rib disposed in the void and configured to increase the rigidity of the inner shroud.

4. The apparatus according to claim 1 , wherein the outer shroud comprises one or more contact pads configured to contact the inner shroud when the inner shroud is coupled to the outer shroud.

5. The apparatus according to claim 1 , wherein the inner shroud comprises a plurality of inner shroud sections, each inner shroud section being configured to be disposed adjacent to another inner shroud section with each inner shroud section circumferentially surrounding a portion of the turbine blade stage.

6. The apparatus according to claim 1 , wherein the inner shroud is made of at least one of ceramic matrix composite material or a refractory alloy configured to withstand an operating temperature in the turbine blade stage.

7. An apparatus configured to seal with a turbine blade stage of a gas turbine, the apparatus comprising:

a casing that at least partially encloses the gas turbine;

an outer shroud configured to be coupled to the casing and circumferentially surround the turbine blade stage:,

an inner shroud configured to circumferentially surround the turbine blade stage to seal with the turbine blade stage and comprising an attachment element configured to be inserted into the outer shroud to couple the inner shroud to the outer shroud, the attachment element comprising a flange defining a hole therein;

wherein the outer shroud and the inner shroud form a cavity that is in fluid communication with a purge gas supply attached to the casing and supplying cool gas such that the cavity is cooled by the cool gas purging the casing, the cavity being in communication with the attachment element, the outer shroud defining a hole that is configured to be in alignment with the hole defined by the flange when the inner shroud is inserted into the outer shroud;

a pin configured to be inserted into the hole defined by the outer shroud and the hole defined by the inner shroud, wherein alignment comprises the hole defined by the outer shroud being offset an amount from the hole defined by the flange such that when the pin is inserted, the pin is elastically deformed to keep the inner shroud pressing against the outer shroud.

8. An apparatus configured to seal with a turbine blade stage of a gas turbine, the apparatus comprising:

a casing that at least partially encloses the gas turbine;

an outer shroud configured to be coupled to the casing and circumferentially surround the turbine blade stage:,

an inner shroud configured to circumferentially surround the turbine blade stage to seal with the turbine blade stage and comprising an attachment element configured to be inserted into the outer shroud to couple the inner shroud to the outer shroud, the attachment element comprising a flange defining a hole therein;

wherein the outer shroud and the inner shroud form a cavity that is in fluid communication with a purge gas supply attached to the casing and supplying cool gas such that the cavity is cooled by the cool gas purging the casing, the cavity being in communication with the attachment element, the outer shroud defining a hole that is configured to be in alignment with the hole defined by the flange when the inner shroud is inserted into the outer shroud;

a pin configured to be inserted into the hole defined by the outer shroud and the hole defined by the inner shroud, wherein the pin comprises a taper configured to press the inner shroud against the outer shroud when the pin is inserted into the hole defined by the outer shroud and the hole defined by the flange.

9. A gas turbine comprising:

a compressor section configured to compress intake air;

a combustion section configured to combust compressed intake air and fuel;

a turbine section comprising a turbine blade stage configured to rotate upon impingement of hot gas from the combustion section;

a casing that at least partially encloses the gas turbine;

an outer shroud configured to be coupled to the casing and circumferentially surround the turbine blade stage;

an inner shroud configured to circumferentially surround the turbine blade stage to seal with the turbine blade stage and comprising an attachment element configured to be inserted into the outer shroud to couple the inner shroud to the outer shroud, the inner shroud defining a void internal to the inner shroud; and

wherein the outer shroud and the inner shroud form a cavity that is in fluid communication with a purge gas supply attached to the casing and supplying cool gas such that the cavity is cooled by the cool gas purging the casing, the cavity being in communication with the attachment element.

10. A gas turbine system comprising:

a gas turbine comprising: a turbine blade stage; an outer shroud configured to circumferentially surround the turbine blade stage; and an inner shroud configured to circumferentially surround the turbine blade stage to seal with the turbine blade stage and comprising an attachment element configured to be inserted into the outer shroud to couple the inner shroud to the outer shroud, the inner shroud defining a void internal to the inner shroud;

a load coupled to the gas turbine;

a casing configured to be coupled to the outer shroud and to at least partially enclose the gas turbine; and

one or more cavities formed by the outer shroud and the inner shroud, the one or more cavities being in fluid communication with a purge gas supply attached to the casing such that the purge gas purges an interior of the casing with a cool gas;

wherein the one or more cavities are cooled by the cool gas purging the casing, the cavities being in communication with the attachment element.

11. The system according to claim 10 , wherein the load is an electric generator.