Abstract: A combustion staging system includes a splitting unit receiving a metered fuel flow and controllably splitting the received flow into pilot and mains flows for injecting at pilot and mains fuel stages performing staging combustor control. Pilot and mains fuel manifolds distribute fuel from the unit, which can select pilot-only and pilot and mains operations. A cooling flow recirculation line provides a cooling flow to the mains manifold during pilot-only operation, and a return section to collect mains manifold cooling flow. A fuel recirculating control valve open position allows the cooling flow to enter a delivery section during pilot-only operation; a shut off position prevents the cooling flow from entering the delivery section during pilot and mains operation. The unit can divert a mains flow portion into the delivery section during pilot and mains operation, the diverted portion re-joining the rest of the mains flow in the mains fuel stages.

Abstract: A combustion staging system includes a splitting unit receiving a metered fuel flow and controllably splitting the received flow into pilot and mains flows for injecting at pilot and mains fuel stages performing staging combustor control. Pilot and mains fuel manifolds distribute fuel from the unit, which can select pilot-only and pilot and mains operations. A cooling flow recirculation line provides a cooling flow to the mains manifold during pilot-only operation, and a return section to collect mains manifold cooling flow. A fuel recirculating control valve open position allows the cooling flow to enter a delivery section during pilot-only operation; a shut off position prevents the cooling flow from entering the delivery section during pilot and mains operation. The unit can divert a mains flow portion into the delivery section during pilot and mains operation, the diverted portion re-joining the rest of the mains flow in the mains fuel stages.