A fuel system can include a first fuel circuit, a second fuel circuit, and an inert gas purge system operatively connected to both the first fuel circuit and the second fuel circuit to purge at least a portion of either or both of the first and/or second fuel circuit. The first fuel can be a liquid fuel and the second fuel can be a gaseous fuel. The first fuel circuit can include a first fuel manifold configured to fluidly communicate a first fuel supply with at least one dual fuel nozzles downstream of the first fuel manifold.

A power generation system includes a combustion system, a liquid supply system, and a vapor supply system. The combustion system is configured to generate power by combusting an alternative fuel. The liquid supply system is configured to channel a liquid alternative fuel to the combustion system. The vapor supply system is configured to channel a vapor alternative fuel to the combustion system. The combustion system is ignited by combusting the liquid alternative fuel from the liquid supply system and is operated by combusting the vapor alternative fuel from the vapor supply system.

A gas turbine engine for an aircraft. The gas turbine comprises a staged combustion system having pilot injectors and main injectors, a fuel metering system configured to control fuel flow to the pilot injectors and the main injectors, and a fuel system controller. The controller is configured to identify an atmospheric condition, determine a ratio of pilot fuel flow rate for the pilot injectors to main fuel flow rate for the main injectors in response to the atmospheric condition, and inject fuel by the pilot injectors and the main injectors in accordance with said ratio to control an index of soot emissions caused by combustion of fuel therein.

Methods and systems for supply of fuel for a turbine-driven fracturing pump system used in hydraulic fracturing may be configured to identify when the supply pressure of primary fuel to a plurality of gas turbine engines of a plurality of hydraulic fracturing units falls below a set point, identify a gas turbine engine of the fleet of hydraulic fracturing units operating on primary fuel with highest amount of secondary fuel available, and to selectively transfer the gas turbine engine operating on primary fuel with the highest amount of secondary fuel from primary fuel operation to secondary fuel operation. Some methods and systems may be configured to transfer all gas turbine engines to secondary fuel operation and individually and/or sequentially restore operation to primary fuel operation and/or to manage primary fuel operation and/or secondary fuel operation for portions of the plurality of gas turbine engines.

Methods and systems for supply of fuel for a turbine-driven fracturing pump system used in hydraulic fracturing may be configured to identify when the supply pressure of primary fuel to a plurality of gas turbine engines of a plurality of hydraulic fracturing units falls below a set point, identify a gas turbine engine of the fleet of hydraulic fracturing units operating on primary fuel with highest amount of secondary fuel available, and to selectively transfer the gas turbine engine operating on primary fuel with the highest amount of secondary fuel from primary fuel operation to secondary fuel operation. Some methods and systems may be configured to transfer all gas turbine engines to secondary fuel operation and individually and/or sequentially restore operation to primary fuel operation and/or to manage primary fuel operation and/or secondary fuel operation for portions of the plurality of gas turbine engines.

An aircraft propulsion system includes a hydrocarbon fuel store, a hydrogen fuel store, an engine system capable of producing thrust by combusting hydrocarbon fuel and/or combusting or oxidising hydrogen fuel, a conveying system to convey hydrocarbon and hydrogen fuel from the fuel stores to the engine system and a control system to control the respective flow rates of the fuel within the conveying system. The control system adapts the fractions of the total fuel energy flow rate to the engine system represented by the hydrocarbon and hydrogen fuel energy flow rates in order to reduce climate warming impact caused by at least one of carbon dioxide, water vapour and condensation trails and/or increase climate cooling impact caused by condensation trails produced by the aircraft propulsion system compared to a dual-fuel propulsion system in which a reserve of hydrocarbon fuel is entirely combusted before any of a reserve of hydrogen fuel.

A fuel power transfer system for an engine may include a cryogenic fuel supply, a fuel pump in fluid communication with the cryogenic fuel supply, a multi-position valve in fluid communication with the fuel pump and a combustion chamber of the engine, a fuel turbine operatively coupled to the fuel pump and having a primary discharge port in fluid communication with the combustion chamber, a primary heat exchanger in fluid communication between the multi-position valve and the fuel turbine, and a gearbox operatively coupled to the fuel turbine and the fuel pump and configured to transfer power from the fuel turbine to the engine.

A propulsion system for an aircraft includes a gas turbine engine and a fuel tank, wherein the fuel includes at least a proportion of a sustainable aviation fuel—SAF—having a density between 90% and 98% of the density, ρ.sub.K, of kerosene and a calorific value between 101% and 105% the calorific value CV.sub.K, of kerosene. The engine includes a combustor; and a fuel pump arranged to supply a fuel thereto at an energy flow rate, C, the pump being arranged to output fuel at a volumetric flow rate, Q, the percentage of fuel passing through the pump not provided to the combustor being referred to as a spill percentage. The fuel include X % SAF, where X % is in the range from 5% to 100%, and has a density, ρ.sub.F, and a calorific value CV.sub.F. The propulsion system is arranged so: the fuel-change spill ratio, R.sub.s, of: $R_s=\frac{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{kerosene}}{\mathrm{spill}\mathrm{percentage}\mathrm{at}\mathrm{cruise}\mathrm{using}\mathrm{the}\mathrm{fuel}\mathrm{with}X\%SAF}$ is equal to: $\frac{Q-\left(C/\left({\mathrm{CV}}_K\times {\rho }_K\right)\right)}{Q-(C/({\mathrm{CV}}_F\times {\rho }_{}}$

The invention may be embodied a valve for a combustor of a gas turbine, the valve including: a housing including a fluid inlet and fluid outlets; an actuator within the housing and movable between an open position and a closed position; a fluid path through the housing between the fluid inlet and the fluid outlets, wherein the fluid path is blocked while the actuator is in the closed positions such that fluid may not flow from the inlet to the outlets and fluid may not flow between the outlets, and wherein one of the fluid outlets is fluidly connected to a first combustion can of the combustor, and another of the fluid outlets is fluidly connected to a second combustion can of the combustor.

The present invention provides a burner, a combustor equipped with the burner, and a gas turbine, with which it is possible to premix a first hydrocarbon-based fuel (for example, natural gas), a second fuel (for example, hydrogen gas), and combustion air, and to spray into the combustion chamber of the combustor a thin and uniform concentration distribution of the premixed air, and with which it is possible to suppress the amount of NOx discharged. On the upstream side of the premix flow path, hydrogen gas is sprayed from second fuel spray nozzles, which project into the premix flow path, into the flow of the combustion air flowing toward the center from the outer edge of an outer cylinder, whereby a primary air-fuel mixture having a uniform concentration distribution is generated without affecting a low-speed region of the combustion air. Natural gas is then sprayed from first fuel spray nozzles into the primary air-fuel mixture, whereby the natural gas, which has a high specific gravity, and the primary air-fuel mixture are adequately mixed in a stirring fashion, and a secondary air-fuel mixture (premixed air) is generated that is lean and has a more uniform concentration distribution than the first air-fuel mixture. By combusting this type of premixed air in the combustion chamber, NOx in the combustion exhaust gas can be suppressed.