Purge system for dual-fuel gas turbine engine

A method of operating a dual-fuel turbine engine configured to receive liquid fuel and gaseous fuel, the dual-fuel turbine engine comprising:

• a fuel manifold having a first passage to carry a first portion of the liquid fuel, a second passage to carry a second portion of the liquid fuel, and a third passage to carry the gaseous fuel,
• a primary line network connecting a liquid fuel source to the first passage of the fuel manifold via a first passage,
• a secondary line network connecting the liquid fuel source to the second passage of the fuel manifold via a second passage, and
• a gaseous fuel intake system connecting to the third passage of the fuel manifold via a third passage, and
• a purge system fluidly coupled to the primary line network, the secondary line network, and the third passage and comprising a purge dividing fitting fluidically coupled to a primary liquid fuel dividing fitting of the primary line network and to a secondary liquid fuel dividing fitting of the secondary line network,
• the method comprising:
• supplying the first portion of the liquid fuel from the liquid fuel source to the first passage of the fuel manifold via the primary line network and the first passage to facilitate startup of the dual-fuel turbine engine;
• supplying the second portion of the liquid fuel to the second passage of the fuel manifold via the secondary line network and the second passage to fuel the dual-fuel turbine engine;
• switching from the liquid fuel to gaseous fuel for fueling the dual-fuel turbine engine;
• and
• continuously flowing a purging fluid through the first passage via the purge dividing fitting and the primary liquid fuel dividing fitting of the primary line network and through the second passage via the purge dividing fitting and the secondary liquid fuel dividing fitting of the secondary line network while fueling the dual-fuel turbine engine with the gaseous fuel from the gaseous fuel intake system via the third passage that receives the gaseous fuel from the gaseous fuel intake system;
• and
• continuously flowing the purging fluid through the third passage when the liquid fuel is used for combustion.

A dual-fuel turbine engine comprising:

• a fuel manifold to combust liquid fuel or gaseous fuel;
• a liquid fuel intake system, in fluid communication with the fuel manifold, to supply a first portion of the liquid fuel to the fuel manifold via a first liquid fuel dividing fitting and a first passage of the fuel manifold for start-up of the dual-fuel turbine engine and to supply a second portion of the liquid fuel to the fuel manifold via a second liquid fuel dividing fitting and a second passage of the fuel manifold for powering the dual-fuel turbine engine;
• a gaseous fuel intake system, in fluid communication with the fuel manifold, to supply the gaseous fuel to the fuel manifold via a third passage of the fuel manifold;
• and
• a purge system, in fluid communication with the fuel manifold, to continuously purge (i) the first passage via a purge dividing fitting fluidically coupled to the first liquid fuel dividing fitting and (ii) the second passage of the fuel manifold with purging fluid via the purge dividing fitting and the second liquid fuel dividing fitting while the gaseous fuel intake system supplies the gaseous fuel to the fuel manifold via the third passage of the fuel manifold and to continuously purge the third passage of the fuel manifold with the purging fluid while the liquid fuel intake system supplies the first portion of the liquid fuel to the fuel manifold via the first passage and the second portion of the liquid fuel to the fuel manifold via the second passage.