Gas compressor operating method and gas turbine equipped with gas compressor

1. A method for operating a gas compressor which compresses gas whose supply conditions change and which is equipped with an intake-flow regulating mechanism, said method comprising:

determining a reference limit pressure ratio based on design conditions of the gas compressor;

detecting an operating-state value of the gas compressor;

determining a first correction factor based on the detected operating-state value;

deriving a corrected limit pressure ratio by correcting the reference limit pressure ratio using the first correction factor; and

operating the gas compressor using the corrected limit pressure ratio,

wherein each of the reference limit pressure ratio and the corrected limit pressure ratio defines an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism to prevent surging in the gas compressor, and

wherein the first correction factor is obtained from a correcting rotational speed ratio (α) obtained from the following [Eq. 1], where N 0 is a reference rotational speed of the gas compressor, κ 0 is a reference specific heat ratio of the intake gas to the gas compressor, R 0 is a reference gas constant of the intake gas to the gas compressor, T 0 is a reference temperature of the intake gas to the gas compressor, N is an actual rotational speed of the gas compressor, κ is a present specific heat ratio of the intake gas to the gas compressor, R is a present gas constant of the intake gas to the gas compressor, and T is a present temperature of the intake gas to the gas compressor.

Correcting

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rotational

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speed

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ratio

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α

=

N

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κ

0

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R

0

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T

0

N

0

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κ

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RT

.

[

Eq

.

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1

]

2. The method for operating a gas compressor according to claim 1 , wherein the gas constant (R) and the specific heat ratio (κ) of the intake gas to the gas compressor are calculated from a gas composition measured at the inlet side of the gas compressor.

3. The method for operating a gas compressor according to claim 1 , wherein the gas constant (R) and the specific heat ratio (κ) of the intake gas to the gas compressor are calculated from a gas composition obtained by conversion from a gas density or the amount of gas generated, which is measured at the inlet side of the gas compressor.

4. The method for operating a gas compressor according to claim 1 , wherein if the intake gas to the gas compressor is a gas in which a plurality of gases are mixed, a gas constant (R) and a specific heat ratio (κ) after mixing are obtained from the compositions and flow ratio between the individual gases.

5. The method for operating a gas compressor according to claim 1 , wherein, after being corrected using the first correction factor, the limit pressure ratio is corrected using a second correction factor which is determined in advance depending on an intake flow rate of the gas compressor or a degree of opening and an actuating direction of the intake-flow regulating mechanism.

6. A method for operating a gas turbine equipped with a gas compressor which compresses gas whose supply conditions change and which supplies the compressed gas to a combustor as gas fuel, the gas compressor being provided with an intake-flow regulating mechanism,

wherein an operating method for preventing surging in the gas compressor by defining an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism is achieved by the gas-compressor operating method according to claim 1 .

7. The method for operating a gas compressor according to claim 6 , wherein the operating method for preventing surging in the gas compressor includes a gas-fuel bypass operation.

8. The method for operating a gas turbine according to claim 6 , wherein an interlock that immediately halts the operation when an operating pressure ratio of the gas compressor has exceeded the limit pressure ratio is provided.

9. A method for operating a gas compressor which compresses gas whose supply conditions change and which is equipped with an intake-flow regulating mechanism, said method comprising:

determining a reference limit pressure ratio based on design conditions of the gas compressor;

detecting an operating-state value of the gas compressor;

determining a first correction factor based on the detected operating-state value;

deriving a corrected limit pressure ratio by correcting the reference limit pressure ratio using the first correction factor; and

operating the gas compressor using the corrected limit pressure ratio,

wherein each of the reference limit pressure ratio and the corrected limit pressure ratio defines an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism to prevent surging in the gas compressor,

wherein the first correction factor is calculated from an intake gas temperature of the gas compressor,

wherein in the calculation of the first correction factor, a gas constant (R) and a specific heat ratio (κ) of the intake gas to the gas compressor are included, and

wherein the gas constant (R) and the specific heat ratio (κ) of the intake gas to the gas compressor are calculated from a gas composition measured at the inlet side of the gas compressor.

10. A method for operating a gas compressor which compresses gas whose supply conditions change and which is equipped with an intake-flow regulating mechanism, said method comprising:

determining a reference limit pressure ratio based on design conditions of the gas compressor;

detecting an operating-state value of the gas compressor;

determining a first correction factor based on the detected operating-state value;

deriving a corrected limit pressure ratio by correcting the reference limit pressure ratio using the first correction factor; and

operating the gas compressor using the corrected limit pressure ratio,

wherein each of the reference limit pressure ratio and the corrected limit pressure ratio defines an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism to prevent surging in the gas compressor,

wherein the first correction factor is calculated from an intake gas temperature of the gas compressor,

wherein in the calculation of the first correction factor, a gas constant (R) and a specific heat ratio (κ) of the intake gas to the gas compressor are included, and

wherein the gas constant (R) and the specific heat ratio (κ) of the intake gas to the gas compressor are calculated from a gas composition obtained by conversion from a gas density or the amount of gas generated, which is measured at the inlet side of the gas compressor.

11. A method for operating a gas compressor which compresses gas whose supply conditions change and which is equipped with an intake-flow regulating mechanism, said method comprising:

determining a reference limit pressure ratio based on design conditions of the gas compressor;

detecting an operating-state value of the gas compressor;

determining a first correction factor based on the detected operating-state value;

deriving a corrected limit pressure ratio by correcting the reference limit pressure ratio using the first correction factor; and

operating the gas compressor using the corrected limit pressure ratio,

wherein each of the reference limit pressure ratio and the corrected limit pressure ratio defines an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism to prevent surging in the gas compressor,

wherein the first correction factor is calculated from an intake gas temperature of the gas compressor,

wherein in the calculation of the first correction factor, a gas constant (R) and a specific heat ratio (κ) of the intake gas to the gas compressor are included, and

wherein if the intake gas to the gas compressor is a gas in which a plurality of gases are mixed, a gas constant (R) and a specific heat ratio (κ) after mixing are obtained from the compositions and flow ratio between the individual gases.

12. The method for operating a gas compressor according to claim 11 , wherein the composition of at least one of the plurality of gases is obtained by conversion from the gas density or the amount of gas generated.

13. A method for operating a gas compressor which compresses gas whose supply conditions change and which is equipped with an intake-flow regulating mechanism, said method comprising:

determining a reference limit pressure ratio based on design conditions of the gas compressor;

detecting an operating-state value of the gas compressor;

determining a first correction factor based on the detected operating-state value;

deriving a corrected limit pressure ratio by correcting the reference limit pressure ratio using the first correction factor; and

operating the gas compressor using the corrected limit pressure ratio,

wherein each of the reference limit pressure ratio and the corrected limit pressure ratio defines an operational upper limit of a pressure ratio relative to an intake flow rate of the gas compressor or a degree of opening of the intake-flow regulating mechanism to prevent surging in the gas compressor, and

wherein the intake flow rate of the gas compressor is a corrected flow rate Q 0 (the unit is volume flow rate) obtained from the following [Eq. 2], where Q is an actual intake flow rate of the gas compressor (the unit is volume flow rate), N 0 is a reference rotational speed of the gas compressor, κ 0 is a reference specific heat ratio of the intake gas to the gas compressor, R 0 is a reference gas constant of the intake gas to the gas compressor, T 0 is a reference temperature of the intake gas to the gas compressor, N is an actual rotational speed of the gas compressor, κ is a present specific heat ratio of the intake gas to the gas compressor, R is a present gas constant of the intake gas to the gas compressor, and T is a present temperature of the intake gas to the gas compressor, or a corrected flow rate G 0 (the unit is mass flow rate) obtained from the following [Eq. 3], where G is an actual intake flow rate of the gas compressor (the unit is mass flow rate), N 0 is a reference rotational speed of the gas compressor, κ 0 is a reference specific heat ratio of the intake gas to the gas compressor, R 0 is a reference gas constant of the intake gas to the gas compressor, T 0 is a reference temperature of the intake gas to the gas compressor, N is an actual rotational speed of the gas compressor, κ is a present specific heat ratio of the intake gas to the gas compressor, R is a present gas constant of the intake gas to the gas compressor, and T is a present temperature of the intake gas to the gas compressor.

Corrected

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flow

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rate

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Q

0

=

Q

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κ

0

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R

0

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T

0

κ

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RT

[

Eq

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2

]

Corrected

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flow

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rate

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G

0

=

G

·

κ

0

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RT

κ

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R

0

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T

0

P

/

P

0

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[

Eq

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3

]