Gas turbine engine fuel system

Patent metadata

Field	Value
Publication number	US-2025188869-A1
Application number	US-202418741964-A
Country	US
Kind code	A1
Filing date	Jun 13, 2024
Priority date	Jul 5, 2023
Publication date	Jun 12, 2025
Grant date	—

Abstract

A fuel system for a gas turbine engine includes a fuel offtake configured to divert a portion of hydrogen fuel from a main fuel conduit, a burner configured to burn the portion of hydrogen fuel diverted from the main fuel conduit and at least first and second heat exchangers. The first heat exchanger is configured to transfer heat from exhaust gasses produced by the burner to hydrogen fuel in the main fuel conduit and the second heat exchanger is provided upstream in hydrogen flow of the first heat exchanger and is configured to transfer heat from a further heat exchange fluid to hydrogen fuel in the main fuel conduit. In an embodiment, the further heat exchange fluid is compressor bleed air bled from a core compressor of the gas turbine engine.

First claim

1 . A fuel system for a hydrogen fuelled gas turbine engine, the fuel system comprising:
a fuel offtake configured to divert a portion of hydrogen fuel from a main fuel conduit; a burner configured to burn the portion of hydrogen fuel diverted from the main fuel conduit; a first heat exchanger configured to transfer heat from exhaust gasses produced by the burner to hydrogen fuel in the main fuel conduit; wherein
the fuel offtake is provided downstream in hydrogen fuel flow of the first heat exchanger.

2 . The fuel system according to claim 1 , wherein the burner is configured to burn hydrogen fuel with air from a compressor bleed of a gas turbine engine.

3 . The fuel system according to claim 1 , wherein the fuel system comprises a second hydrogen fuel offtake upstream in hydrogen fuel flow of the first heat exchanger configured to divert a portion of hydrogen fuel from the main fuel conduit to the burner.

4 . The fuel system according to claim 3 , wherein the second hydrogen fuel offtake comprises an auxiliary fuel heater such as an electric fuel heater.

5 . The fuel system according to claim 1 , wherein the fuel system comprises a second heat exchanger provided upstream in hydrogen fuel flow of the first heat exchanger, and configured to exchange heat with a second heat exchange fluid.

6 . The fuel system according to claim 5 , wherein, the fuel system is configured such that, in use, the further heat exchange fluid has a lower temperature at entry to the second heat exchanger than burner exhaust gasses at entry to the first heat exchanger.

7 . The fuel system according to claim 5 , wherein the further heat exchange fluid comprises compressed air provided from a compressor bleed of a gas turbine engine.

8 . The fuel system according to claim 7 , wherein the second heat exchanger is configured to cool the compressor bleed air to a temperature above 273K at an outlet of the second heat exchanger.

9 . The fuel system according to claim 6 , wherein the fuel system comprises an exhaust mixer configured to mix compressor bleed outlet air from the second heat exchanger with exhaust gases from an outlet of the first heat exchanger.

10 . The fuel system according to claim 5 , wherein the fuel system comprises a third heat exchanger provided downstream of the second heat exchanger and upstream of the first heat exchanger in hydrogen fuel flow and configured to exchange heat between exhaust gasses from the burner downstream of the second heat exchanger, and hydrogen in the main fuel conduit.

11 . The fuel system according to claim 3 , wherein the fuel system comprises a second heat exchanger provided upstream in hydrogen fuel flow of the first heat exchanger. and configured to exchange heat with a second heat exchange fluid. and wherein the second fuel offtake is configured to receive hydrogen fuel from an outlet of the second heat exchanger.

12 . A gas turbine engine comprising a fuel system according to claim 1 .

13 . A method of starting a gas turbine engine according to claim 12 , comprising:
flowing gaseous hydrogen through the main fuel conduit, first heat exchanger, fuel offtake and burner; igniting the gaseous hydrogen in the burner to produce heated burner exhaust gases, and flowing these gases through the first heat exchanger; and, subsequently: flowing chilled hydrogen through the main fuel conduit and first heat exchanger; and starting the main gas turbine engine combustor using the hydrogen flowed through the first heat exchanger.

Assignees

• Rolls Royce Plc

Inventors

• Palmer Chloe J
• Bacic Marko
• Harris Paul J H

Classifications

• F02C7/228

  Dividing fuel between various burners · CPC title

• F02C3/22

  the fuel or oxidant being gaseous at standard temperature and pressure (F02C3/28 takes precedence) · CPC title

• F02C6/08

  the gas being bled from the gas-turbine compressor · CPC title

• F05D2260/213

  by the provision of a heat exchanger within the cooling circuit · CPC title

• F02C7/224 Primary

  Heating fuel before feeding to the burner · CPC title