A dual fuel heating system can be used in a gas appliance. A dual fuel heating system can have a fuel selector valve for selecting between a first fuel and a second fuel different from the first. The dual fuel heating system can include a regulator unit configured to regulate the pressure of the two different fuels. The selector valve determines which flow path for which fuel is open and which is closed.

A fuel injection device includes a plurality of main burners and pilot burners. Each main burner is connected to a main distribution line, and each pilot burner is connected to a pilot distribution line. A setting device provides fuel to the main fuel line and/or to the pilot fuel line. A control unit adjusts the setting device between a first mode for exclusive pilot burner operation and a second mode for joint pilot burner operation and main burner operation such that, in the first mode, a tank connection is connected to a first line section of the main fuel line, and a second line section of the main fuel line is connected to the pilot supply line to conduct fuel through the main fuel line before it is supplied to the pilot fuel line to cool the main burner.

A fuel distribution device is provided wherein an axis is defined. The device comprises a body housing a distribution path for fuel; the distribution path has one inlet and a plurality of outlets; the inlet is located on the external surface of the body at an end of an inlet branch of the distribution path; the plurality of outlets are located on the external surface of the body at ends of a corresponding plurality of outlet branches of the distribution path; the inlet branch and the outlet branches are fluidly connected to a distribution space; and the outlet branches are arranged radially.

A fuel distribution device is provided wherein an axis is defined. The device comprises a body housing a distribution path for fuel; the distribution path has one inlet and a plurality of outlets; the inlet is located on the external surface of the body at an end of an inlet branch of the distribution path; the plurality of outlets are located on the external surface of the body at ends of a corresponding plurality of outlet branches of the distribution path; the inlet branch and the outlet branches are fluidly connected to a distribution space; and the outlet branches are arranged radially.

In one aspect, a fuel supply system may include a fuel injector having a primary and a secondary pilot fuel nozzle in fluid communication with a primary and a secondary fuel circuit, respectively, and a main fuel nozzle in fluid communication with a main fuel circuit. The fuel injector may also define a by-pass fuel circuit connected between the primary circuit and the secondary circuit and/or the main circuit. The system may also include a primary fuel manifold configured to be fluidly connected to the primary pilot fuel nozzle via the primary fuel circuit. Moreover, the system may include a by-pass valve provided in operative association with the by-pass fuel circuit. The by-pass valve may be configured to be opened such that a portion of the fuel flowing through the primary circuit from the primary fuel manifold is directed to the secondary circuit and/or the main circuit.

In one aspect, a fuel supply system may include a fuel injector having a primary and a secondary pilot fuel nozzle in fluid communication with a primary and a secondary fuel circuit, respectively, and a main fuel nozzle in fluid communication with a main fuel circuit. The fuel injector may also define a by-pass fuel circuit connected between the primary circuit and the secondary circuit and/or the main circuit. The system may also include a primary fuel manifold configured to be fluidly connected to the primary pilot fuel nozzle via the primary fuel circuit. Moreover, the system may include a by-pass valve provided in operative association with the by-pass fuel circuit. The by-pass valve may be configured to be opened such that a portion of the fuel flowing through the primary circuit from the primary fuel manifold is directed to the secondary circuit and/or the main circuit.

A fuel supply system includes a metering and splitting arrangement receiving a fuel flow and controllably meters and splits the received fuel flow into metered pilot and mains flows for injecting at injector pilot and mains fuel discharge orifices to perform combustor staging control. The system includes mains isolation valves and a mains fuel distribution pipework has fuel lines connected to one of the orifices and extending therefrom to a respective one of the valves. Each valve has a closed position for removing the mains fuel from its injector through its line when the mains distribution pipework is deselected for pilot-only operation, and isolates its line from the metering and splitting arrangement. Each valve has an open position for refilling its injector with mains fuel through its line when the mains distribution pipework is selected for pilot and mains operation, and reconnects its line to the metering and splitting arrangement.

A fuel supply system for fuel injectors of a multi-stage combustor of a gas turbine engine. The fuel supply system includes a metering and splitting arrangement which receives a total fuel flow and controllably meters and splits the received total fuel flow into metered pilot and mains flows. The fuel supply system further includes a de-priming sub-system, one or more fuel lines of a mains fuel distribution pipework being fluidly connected to the mains fuel discharge orifices and extending to the de-priming sub-system, and the de-priming sub-system being configured to remove the mains fuel from the injectors. A re-priming sub-system, the one or more fuel lines of the mains fuel distribution pipework also extending to the re-priming sub-system, and the re-priming sub-system being configured to refill the injectors with mains fuel through the one or more fuel lines when the mains distribution pipework is selected for pilot and mains operation.

The fuel supply system includes mains pressurising and metering arrangement including a positive displacement ecology pump and an ecology valve piston chamber and a piston slidably movable in the chamber between de-prime and re-prime positions, the chamber forming a fuel sink to one side of the piston which increases in volume when the piston moves to de-prime position and reduces in volume when the piston moves to re-prime position. The ecology valve is fluidly connected to the ecology pump for pilot-only operation reverse direction operation of the ecology pump causes the piston to move to de-prime position removing mains fuel from injectors through a mains fuel distribution pipework and into the fuel sink, and for pilot and mains operation the forward direction operation of the ecology pump causes the piston to move to re-prime position refilling injectors with mains fuel from the fuel sink.

A fuel flow system comprising a fuel manifold and a fuel nozzle. A fluidic valve having an inlet, a first outlet and a control flow inlet. The inlet is coupled to the fuel manifold. The first outlet is coupled to the fuel nozzle. The control flow inlet is coupled to a source of control fuel. The fluidic valve is configured to selectively couple the inlet to the first outlet dependent on the control flow into the control flow inlet.