# US 2021/0172385 A1 · Fuel supply system, gas turbine, electricity generation plant, control method, and program

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- Number: US 2021/0172385 A1
- Document ID: US20210172385A1
- Status: Published application
- Kind: A1
- Application number: 16/772,972
- Filed: 2018-11-27
- Published: 2021-06-10
- Earliest claimed: 2018-01-12
- Assignees: Mitsubishi Hitachi Power Systems, Ltd.
- Applicants: Mitsubishi Hitachi Power Systems, Ltd.
- Inventors: Makoto KISHI; Keisuke YAMAMOTO; Hiroyuki NAKAGAWA; Hisashi NAKAHARA; Shinya UCHIDA; Ryo KOTO
- Web page: https://patentgrep.com/patent/US20210172385A1

## CPC

- F02C 9/28: Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence)
- F02C 7/232: Fuel valves {(control of fuel supply by means of fuel metering valves F02C9/263)}; Draining valves or systems (valves in general F16K)
- F02C 9/46: Emergency fuel control
- F02C 7/224: Heating fuel before feeding to the burner
- F05D 2220/76: an electrical generator
- F05D 2240/35: Combustors or associated equipment
- F05D 2270/301: Pressure
- F05D 2270/303: Temperature
- Y02E 20/16: Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A gas turbine fuel supply system includes a fuel supply flow passage that includes a fuel gas heater which heats fuel and supplies the fuel heated by the fuel gas heater to a first nozzle and a second nozzle, a bypass flow passage that supplies the fuel to the first nozzle without passing through the fuel supply flow passage, and a bypass fuel flow rate adjusting valve that adjusts a flow rate of the fuel flowing in the bypass flow passage.

## Claims

### Claim 1

A fuel supply system comprising:
a fuel supply flow passage that includes a fuel gas heater which heats fuel of a gas turbine and supplies the fuel heated by the fuel gas heater to a first nozzle of a pilot system which supplies flames serving as pilot flames and a second nozzle of another fuel system;
a bypass flow passage that connects to the pilot system and supplies the fuel to the first nozzle without passing through the fuel supply flow passage; and
a bypass fuel flow rate adjusting valve that adjusts a flow rate of the fuel flowing in the bypass flow passage.

### Claim 2 (depends on 1)

The fuel supply system according to claim 1, wherein a density of the fuel which is supplied to the first nozzle via the bypass flow passage is higher than a density of the fuel which is supplied to the first nozzle via the fuel supply flow passage.

### Claim 3 (depends on 1)

The fuel supply system according to claim 1, wherein a pressure loss in the bypass flow passage is less than a pressure loss in the fuel supply flow passage.

### Claim 4 (depends on 1)

The fuel supply system according to claim 1, further comprising a discharge flow passage of drainage that connects the bypass flow passage and the fuel supply flow passage.

### Claim 5 (depends on 4)

The fuel supply system according to claim 4, wherein the bypass fuel flow rate adjusting valve is provided between a connection position of the discharge flow passage in the bypass flow passage and a manifold to which the first nozzle is connected.

### Claim 6 (depends on 5)

The fuel supply system according to claim 5, wherein the bypass fuel flow rate adjusting valve is provided at a position which is closer to the manifold than the connection position of the discharge flow passage.

### Claim 7 (depends on 1)

The fuel supply system according to claim 1, wherein, when a piping distance between the bypass fuel flow rate adjusting valve and a manifold to which the first nozzle is connected is defined as a first distance and a piping distance between a first fuel flow rate adjusting valve that is disposed in the fuel supply flow passage and adjusts a flow rate of the fuel supplied to the first nozzle and the manifold is defined as a second distance, the bypass fuel flow rate adjusting valve is provided at a position at which the first distance is equal to or less than the second distance.

### Claim 8 (depends on 1)

The fuel supply system according to claim 1, further comprising a control device that adjusts an opening of the bypass fuel flow rate adjusting valve.

### Claim 9 (depends on 8)

The fuel supply system according to claim 8, wherein a first fuel flow rate adjusting valve that adjusts a flow rate of the fuel supplied to the first nozzle is provided in the fuel supply flow passage, and
wherein the control device opens the first fuel flow rate adjusting valve and the bypass fuel flow rate adjusting valve at the time of the decrease in load with an opening greater than that before a decrease in load of the gas turbine.

### Claim 10 (depends on 9)

The fuel supply system according to claim 9, wherein the control device performs control for fully opening the first fuel flow rate adjusting valve for a predetermined time at the time of the decrease in load and opening the bypass fuel flow rate adjusting valve, which is in a closed state before the decrease in load, with a predetermined opening at the time of the decrease in load.

### Claim 11 (depends on 10)

The fuel supply system according to claim 10, wherein the control device controls the opening of the bypass fuel flow rate adjusting valve after the decrease in load, on the basis of a change index of a fuel flow rate which is determined according to an elapsed time after the decrease in load.

### Claim 12 (depends on 9)

The fuel supply system according to claim 9, wherein the control device learns a coefficient for adjusting the opening of the bypass fuel flow rate adjusting valve on the basis of a fuel-air ratio of the first nozzle and a fuel-air ratio of the second nozzle at the time of the decrease in load and information indicating a relationship between the fuel-air ratio of the first nozzle and the fuel-air ratio of the second nozzle at which a misfire occurs.

### Claim 13 (depends on 8)

The fuel supply system according to claim 8, wherein the control device corrects the opening of the bypass fuel flow rate adjusting valve on the basis of an environmental condition indicating a state of air which is suctioned into the gas turbine.

### Claim 14 (depends on 8)

The fuel supply system according to claim 8, wherein the control device corrects the opening of the bypass fuel flow rate adjusting valve on the basis of a fuel condition indicating a feature of the fuel.

### Claim 15

A fuel supply system comprising:
a fuel supply flow passage that supplies fuel to a first nozzle and a second nozzle at the time of a normal load operation of a gas turbine;
a bypass flow passage that supplies the fuel to the first nozzle without passing through the fuel supply flow passage; and
a bypass fuel flow rate adjusting valve that adjusts a flow rate of the fuel flowing in the bypass flow passage,
wherein the bypass fuel flow rate adjusting valve is closed at the time of the normal load operation and the bypass fuel flow rate adjusting valve is open when the load is lower than that at the time of the normal load operation.

### Claim 16 (depends on 1)

A gas turbine comprising:
a compressor;
a combustor;
a turbine; and
the fuel supply system according to claim 1.

### Claim 17 (depends on 16)

A power generation plant comprising:
the gas turbine according to claim 16;
a steam turbine; and
a power generator.

### Claim 18

A control method for a fuel supply system including a fuel supply flow passage that includes a fuel gas heater which heats fuel of a gas turbine and supplies the fuel heated by the fuel gas heater to a first nozzle of a pilot system which supplies flames serving as pilot flames and a second nozzle of another fuel system, a bypass flow passage that connects to the pilot system and supplies the fuel to the first nozzle without passing through the fuel supply flow passage, and a bypass fuel flow rate adjusting valve that adjusts a flow rate of the fuel flowing in the bypass flow passage,
wherein the bypass fuel flow rate adjusting valve is controlled from a closed state to an open state at the time of a decrease in load of the gas turbine.

### Claim 19

(canceled)