Patent Description:
A gas turbine engine may include one or more fuel circuits, such as a liquid fuel circuit and a gas fuel circuit. Unfortunately, the heat generated by the gas turbine engine can cause coking in the liquid fuel circuit if the liquid fuel circuit is not properly purged. To prevent coking, purging systems as exemplary described in <CIT> or <CIT> may thus be provided. Coking can result in plugged fuel lines, valves, and fuel nozzles. As a result, the coking can result in undesirable downtime of the gas turbine engine. A need exists for an improved purging system for the liquid fuel circuit of the gas turbine engine.

Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

A gas turbine system in accordance with the invention as hereinafter claimed includes the features of claim <NUM> below.

These and other features, aspects, and advantages of the present technology will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:.

One or more specific embodiments of the present technology will be described below.

<FIG> is a schematic of an embodiment of a gas turbine system <NUM> having a gas turbine engine <NUM>, a dual-fuel (supply) system <NUM>, and a steam purge system <NUM>. As discussed in further detail below, the steam purge system <NUM> includes an ejector <NUM> configured to receive water (e.g., a flow of water) from a water supply <NUM> and a gas (e.g., a hot compressed air) from a gas supply <NUM> and generate a flow of steam, such as a saturated steam, for use in purging a liquid fuel circuit <NUM> of the gas turbine system <NUM>. For example, the ejector <NUM> of the steam purge system <NUM> may be configured to generate steam and supply the steam to the liquid fuel circuit <NUM> when switching between a liquid fuel supply system <NUM> and a gas fuel supply system <NUM> and/or when stopping operation of the liquid fuel supply system <NUM>. The steam supplied through the liquid fuel circuit <NUM> is configured to purge the liquid fuel circuit <NUM> of any residual liquid fuel, thereby helping to reduce the possibility of coking in the liquid fuel circuit <NUM>.

The illustrated gas turbine <NUM> include a gas turbine enclosure <NUM> housing the gas turbine engine <NUM>. The gas turbine engine <NUM> includes an air intake section <NUM>, a compressor section <NUM>, a combustion section <NUM>, a turbine section <NUM>, and a load <NUM> (e.g., an electrical generator). The air intake section <NUM> includes an intake duct <NUM> having a plurality of intake louvers <NUM>, one or more air filters <NUM>, and one or more additional air treatment systems <NUM> (e.g., anti-icing systems, silencer baffles, etc.). The compressor section <NUM> includes a single stage or multi-stage compressor <NUM> having one or more stages of compressor blades <NUM> coupled to a compressor shaft <NUM> inside a compressor casing <NUM>. For example, the compressor <NUM> may include between <NUM> and <NUM> compressor stages of compressor blades <NUM> coupled to the shaft <NUM>. Each stage of the compressor <NUM> has a plurality of the compressor blades <NUM> arranged circumferentially about the shaft <NUM>. The compressor section <NUM> outputs a compressed airflow <NUM> to the combustion section <NUM>.

The combustion section <NUM> includes one or more combustors <NUM> having one or more fuel nozzles <NUM>. For example, the combustion section <NUM> may include between two and fourteen combustors <NUM>, wherein each combustor <NUM> includes between one and six fuel nozzles <NUM>. As discussed and from the detail below, each fuel nozzle <NUM> is configured for dual-fuel operation (e.g., dual-fuel nozzles), such that the gas turbine engine <NUM> may be configured to selectively switch between liquid fuel operation via the liquid fuel supply system <NUM> and gas fuel operation via the gas fuel supply system <NUM>. For example, the liquid fuel supply system <NUM> may be configured to supply liquid fuel to the fuel nozzles <NUM> via a plurality of liquid fuel lines <NUM>, while the gas fuel supply system <NUM> may be configured to supply a gas fuel to the fuel nozzles <NUM> through a plurality of gas fuel lines <NUM>. In the illustrated embodiment, the liquid fuel lines <NUM> extend from the liquid fuel supply <NUM> to a manifold <NUM> coupled to the fuel nozzle <NUM> of each combustor <NUM>. Therefore, the fuel manifold <NUM> distributes the liquid fuel to each of the fuel nozzles <NUM> at each respective combustor <NUM>. The gas fuel lines <NUM> may be coupled to the fuel nozzles <NUM> in a similar manner. The fuel nozzles <NUM> facilitate combustion of the fuel (e.g., liquid or gas fuel) in the combustors <NUM>, which then output hot combustion gases <NUM> to the turbine section <NUM>.

The turbine section <NUM> includes a single stage or multi-stage turbine <NUM> having one or more stages of turbine blades <NUM> coupled to a turbine shaft <NUM> within a turbine casing <NUM>. For example, the turbine <NUM> may include between <NUM> and <NUM> turbine stages of turbine blades <NUM> coupled to the shaft <NUM>. Each stage of the turbine <NUM> has a plurality of the turbine blades <NUM> arranged circumferentially about the shaft <NUM>. The turbine <NUM> and the compressor <NUM> are rotationally coupled together via an intermediate shaft <NUM>, which connects with the shafts <NUM> and <NUM>. Additionally, the load <NUM> is rotationally coupled to the turbine <NUM> via a shaft <NUM>. In certain embodiments, one or more of the shafts <NUM>, <NUM>, <NUM>, and <NUM> may be integrated together as a common shaft. Also, in certain embodiments, the load <NUM> may be rotationally coupled to the gas turbine engine <NUM> at the compressor <NUM> end of the gas turbine engine <NUM>, rather than the turbine <NUM> end of the gas turbine engine <NUM>. The gas turbine enclosure <NUM> generally surrounds and contains the entirety of the gas turbine engine <NUM>, including the compressor section <NUM>, the combustion section <NUM>, and the turbine section <NUM>. However, the dual-fuel system <NUM>, the steam purge system <NUM>, and the load <NUM> are generally disposed outside of the gas turbine enclosure <NUM>.

The dual-fuel system <NUM> includes a variety of tanks, pipelines, valves, pumps, manifolds, filters, and other supporting equipment to supply both liquid and gaseous fuels to the gas turbine engine <NUM>. In the illustrated embodiment, the liquid fuel supply system <NUM> may include one or more fuel tanks <NUM>, one or more valves <NUM>, one or more pumps <NUM>, and one or more manifolds and distribution valves <NUM>. The one or more pumps <NUM> are configured to force a flow of a liquid fuel from the fuel tanks <NUM>, while the valves <NUM> are configured to open and close the flow from the fuel tanks <NUM>, and the manifolds and valves <NUM> are configured to distribute the liquid fuel flow through the plurality of liquid fuel lines <NUM> to the various combustors <NUM> and fuel nozzles <NUM>.

Similarly, the gas fuel supply system <NUM> may include one or more fuel filters <NUM>, one or more valves <NUM>, and one or more manifolds and distribution valves <NUM>. The gas fuel supply system <NUM> also may include one or more fuel storage units, such as fuel tanks and/or pipelines. The gas fuel provided by the fuel tanks and/or pipelines may be pressurized, such that the gas fuel supply system <NUM> is configured to control the flow of the gas fuel by opening and closing the valves <NUM> and allowing the gas flow to pass through the manifolds and distribution valves <NUM> to the various fuel nozzles <NUM> through the plurality of gas fuel lines <NUM>.

In operation, the gas turbine engine <NUM> receives an air flow <NUM> through the air intake section <NUM>, compresses the air flow <NUM> in one or more stages of compressor blades <NUM> in the compressor section <NUM>, and directs the compressed airflow <NUM> into the combustors <NUM> of the combustion section <NUM>. The engine <NUM> then mixes the compressed airflow <NUM> with fuel (e.g., liquid fuel from the liquid fuel supply system <NUM> and/or gas fuel from the gas fuel supply system <NUM>) in each of the fuel nozzles <NUM>, ignites the fuel-air mixture and generates hot combustion gases <NUM> in a combustion chamber <NUM> of each combustor <NUM>, and outputs the hot combustion gases <NUM> to the turbine section <NUM>. The engine <NUM> flows the hot combustion gases <NUM> through the turbine section <NUM>, thereby driving rotation of the turbine blades <NUM> as the hot combustion gases <NUM> expand through the turbine section <NUM>. As the hot combustion gases <NUM> drive rotation of the turbine section <NUM>, the turbine shaft <NUM> rotates the shaft <NUM> coupled to the compressor shaft <NUM> and the shaft <NUM> coupled to the load <NUM>. Accordingly, the turbine section <NUM> drives rotation of the compressor <NUM> to compress the intake air <NUM>, while also driving the load <NUM>, such as an electrical generator.

As noted above, the illustrated steam purge system <NUM> includes the water supply <NUM>, the gas supply <NUM>, and the ejector <NUM>. The water supply <NUM> may include one or more water tanks <NUM> and one or more water pumps <NUM> configured to respectively store and pump a flow of water to the ejector <NUM>. The gas supply <NUM> may include an atomizing module <NUM>, such as an air atomizing module, configured to facilitate atomization of liquid fuel in the fuel nozzles <NUM>. Accordingly, the gas supply <NUM>, or specifically the atomizing module <NUM>, may further include one or more gas supply components <NUM> and one or more compressors <NUM>. For example, the compressor <NUM> may include an air compressor (e.g., an atomizing air compressor) for the atomizing module <NUM>. The gas supply components <NUM> may include filters, check valves, tanks, pressure regulators, and other flow control equipment. In some embodiments, the gas supply components <NUM> may include one or more additional heat sources (e.g., heaters or heat exchangers) configured to increase a temperature of the compressed gas from the compressor <NUM>. However, the compressor <NUM> may be configured to output a compressed gas (e.g., compressed air) with a sufficient pressure and temperature to convert the water to steam in the ejector <NUM> without any additional heat sources. Although the illustrated embodiment may use a hot compressed air as the gas, in some embodiments, the gas supply <NUM> may be configured to supply a hot compressed inert gas, such as nitrogen.

The water supply <NUM> is configured to supply the water to the ejector <NUM> through a water line <NUM> having one or more flow control devices, such as a valve <NUM>, a check valve <NUM>, a water tank <NUM> (e.g., a buffer tank), and a valve <NUM>. For example, the valves <NUM> and <NUM> may be rotary valves, gate valves, ball valves, or other suitable actuator-controlled valves, which can be selectively opened and closed in response to control signals from a controller <NUM>. The check valve <NUM> is configured to block backflow of gas (e.g., hot compressed air) from the gas supply <NUM> and/or water from the ejector <NUM> towards the water supply <NUM>. The water tank <NUM> is configured to provide a buffer of water between the check valve <NUM> and the valve <NUM>. The valves <NUM> and <NUM> are configured to open and close the water flow through the water line <NUM> from the water supply <NUM> to the ejector <NUM>.

Similarly, the gas supply <NUM> is configured to supply a gas flow (e.g., a hot compressed air flow) along a gas line <NUM> to the ejector <NUM>. The gas line <NUM> may include one or more flow control devices, such as a valve <NUM>, which is configured to selectively open and close the gas flow in response to a signal from the controller <NUM>. Again, similar to the valves <NUM> and <NUM>, the valve <NUM> may be an actuator-controlled valve, such as a ball valve, a gate valve, a rotary valve, or another suitable actuator-controlled valve.

As discussed further below, the water from the water supply <NUM> and the gas (e.g., hot compressed air) from the gas supply <NUM> are supplied to the ejector <NUM>, such that the gas mixes with and converts the water to steam in the ejector <NUM>. In particular, the relatively high temperature and pressure of the gas (e.g., hot compressed gas) helps to convert the water into steam in the ejector <NUM>. Additionally, a Venturi effect of the ejector sucks the water into the gas flowing through the ejector <NUM>, thereby facilitating flow of the water and mixing in the ejector <NUM>. As the water-gas mixture (e.g., water-air mixture) mixes and expands in the ejector <NUM>, the change in pressure and the heat transferred from the gas (e.g., hot compressed air) to the water helps to convert the water to steam. In certain embodiments, the initially formed steam in the ejector <NUM> may not have the desired characteristics for purging the liquid fuel circuit <NUM> (e.g., the steam may not be immediately a saturated steam). Accordingly, the steam purge system <NUM> may be configured to address a transition of the steam to a saturated steam prior to purging the liquid fuel circuit <NUM>.

An outlet <NUM> of the ejector <NUM> is coupled to an output line <NUM> having a valve <NUM>, a manifold <NUM> is coupled to the output line <NUM>, and a plurality of distribution lines <NUM> are coupled to the manifold <NUM> and extend to the liquid fuel lines <NUM> of the liquid fuel circuit <NUM>. Additionally, a vent line <NUM> is coupled to the output line <NUM> between the ejector <NUM> and the valve <NUM>, and the vent line <NUM> includes a valve <NUM> and a vent/drain <NUM>. When the controller <NUM> initiates a steam purge with the steam purge system <NUM>, the water and gas supplied to the ejector <NUM> may initially generate a steam that is not fully saturated. Accordingly, the controller <NUM> may control the valve <NUM> to close and may control the valve <NUM> to open, thereby blocking the steam from flowing through the output line <NUM> to the manifold <NUM> and venting the steam through the vent line <NUM> to the vent/drain <NUM>. The controller <NUM> may be configured to perform this initial venting of the steam through the vent line <NUM> based on a predetermined time delay or other criteria. However, once the controller <NUM> determines that the steam is or should be a saturated steam, the controller <NUM> is configured to open the valve <NUM> and to close the valve <NUM>, thereby stopping the venting of the steam through the vent line <NUM> and enabling the flow of the steam (now a saturated steam) through the output line <NUM> to the manifold <NUM>.

The manifold <NUM> then distributes the saturated steam to the plurality of liquid fuel lines <NUM> via the distribution lines <NUM>. Each of the distribution lines <NUM> may include a check valve <NUM> configured to block backflow of liquid fuel from the liquid fuel line <NUM> toward the manifold <NUM> and the ejector <NUM>. Additionally, each of the liquid fuel lines <NUM> may include a check valve <NUM> configured to block a backflow of the steam and fuel through the liquid fuel lines <NUM> toward the liquid fuel supply system <NUM>. Accordingly, when the liquid fuel supply system <NUM> is not supplying liquid fuel to the fuel nozzle <NUM> via the liquid fuel circuit <NUM>, the steam purge system <NUM> supplies the saturated steam through the liquid fuel lines <NUM> through the entirety of the liquid fuel circuit <NUM> downstream of the check valves <NUM> and <NUM>, including the liquid fuel lines <NUM>, the manifolds <NUM>, the fuel nozzles <NUM>, and any other flow control devices along the liquid fuel lines <NUM>. As a result, the saturated steam helps to clean out any residual liquid fuel in the liquid circuit <NUM> and reduce the possibility of coke formation in the liquid fuel circuit <NUM>.

The steam purge of the liquid fuel circuit <NUM> by the steam purge system <NUM> may be performed for a predetermined amount of time at regular intervals or during scheduled maintenance. For example, the steam purge may be performed for <NUM> to <NUM> minutes every <NUM> to <NUM> months of operation of the gas turbine system <NUM>. Additionally, the steam purge system <NUM> may be configured to perform the steam purge of the liquid fuel circuit <NUM> while the gas turbine system <NUM> is operational, e.g., operating on gas fuel from the gas fuel supply system <NUM>.

In the illustrated embodiment, the steam purge system <NUM> is at least partially disposed in a housing <NUM> coupled to an exterior of the gas turbine enclosure <NUM> at an elevated area <NUM>, which may be disposed at least partially or entirely vertically above the fuel nozzles <NUM> and/or the combustors <NUM>. Accordingly, the liquid fuel lines <NUM> passing through the housing <NUM> may then enter the gas turbine enclosure <NUM> at an elevated height, such that the liquid fuel lines <NUM> are inclined downwardly toward each of the combustors <NUM> and the fuel nozzles <NUM>. In this matter, the liquid fuel may be driven by gravity downward into and through the fuel nozzles <NUM> and the combustors <NUM>, thereby helping to facilitate steam purging of the liquid fuel in the liquid fuel circuit <NUM> via gravity.

As illustrated, the liquid fuel lines <NUM> pass through the housing <NUM>, the check valves <NUM> are disposed along the liquid fuel lines <NUM> in the housing <NUM>, the check valves <NUM> are disposed along the distribution lines <NUM> in the housing <NUM>, and one or more of the other components of the steam purge system <NUM> also may be disposed in the housing <NUM>. For example, in certain embodiments, the housing <NUM> also may contain the manifold <NUM>, the valves <NUM> and <NUM>, the ejector <NUM>, the valves <NUM>, <NUM>, <NUM>, <NUM>, and the water tank <NUM>. Additionally, in certain embodiments, the housing <NUM> may contain the gas supply <NUM> and the liquid fuel supply system <NUM>. In some embodiments, a separate housing <NUM> (indicated by dashed lines) may house the manifold <NUM>, the valves <NUM> and <NUM>, the ejector <NUM>, the valves <NUM>, <NUM>, <NUM>, <NUM>, the water tank <NUM>, the gas supply <NUM>, and the liquid fuel supply system <NUM>.

In some embodiments, as discussed below with reference to <FIG>, the steam purge system <NUM> may include a plurality of housings <NUM> each having some of the liquid fuel lines <NUM> and the corresponding distribution lines <NUM> and associated components of the steam purge system <NUM>. Again, the liquid fuel lines <NUM>, the check valves <NUM>, the distribution lines <NUM>, and the check valves <NUM> are disposed at the elevated area <NUM>, such that the saturated steam being provided into the liquid fuel lines <NUM> gains the benefit of gravity driving the liquid fuel downward through the liquid fuel circuit <NUM> and out through the fuel nozzles <NUM> into the combustors <NUM> during the steam purge. After completion of the steam purge via the steam purge system <NUM>, the gas turbine <NUM> may then open valves <NUM> disposed along air purge lines <NUM> between the compressor <NUM> and the liquid fuel lines <NUM> of the liquid fuel circuit <NUM>. The air purge lines <NUM> are configured to bleed a stream of compressor air off of the compressor <NUM> to further purge the liquid fuel lines <NUM> after completion of the steam purge. The air purge lines <NUM> also include check valves <NUM> to block a backflow of the liquid fuel and/or the steam through the lines <NUM> into the compressor <NUM>.

As discussed above, the steam purge system <NUM> includes the gas supply <NUM>, which may include one or more compressors <NUM> separate from the compressor <NUM> of the gas turbine engine <NUM>. For example, as noted above, the gas supply <NUM> may use an air compressor <NUM> (e.g., atomizing air compressor) configured to provide an atomizing flow <NUM> (e.g., an atomizing air flow) through one or more atomizing air flow lines <NUM> to each of the fuel nozzles <NUM> in each of the combustors <NUM>. In operation, the atomizing flow <NUM> is configured to atomize the liquid fuel in the fuel nozzle <NUM>. Accordingly, the gas supply <NUM>, particularly the air compressor <NUM> of the atomizing module <NUM>, may be used for multiple purposes, including both atomizing the liquid fuel during liquid fuel operation of the gas turbine engine <NUM> and also producing a hot compressed gas for generating saturated steam in the ejector <NUM> of the steam purge system <NUM>.

The gas supply <NUM>, such as the air compressor <NUM>, may be configured to provide a suitable temperature and pressure to generate steam (e.g., a saturation steam) in the ejector <NUM>. For example, the air compressor <NUM> may be configured to supply a hot compressed air flow to the ejector <NUM> at a temperature of at least equal to or greater than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius, with a pressure of at least equal to or greater than <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> psi. In some embodiments, the gas supply <NUM> may also include a bleed flow (e.g., a hot compressed air flow) from the compressor <NUM> of the gas turbine system <NUM> and/or a gas supply from another tank or compressor within the facility.

As noted above, the gas turbine system <NUM> includes the controller <NUM> configured to control aspects of the steam purge system <NUM>. The illustrated controller <NUM> includes a processor <NUM> and memory <NUM>. The memory <NUM> is configured to store instructions configured to be executed by the processor <NUM> to operate the steam purge system <NUM>. For example, the controller <NUM> may be configured to store and execute instructions in accordance with the process illustrated in <FIG>. In operation, the controller <NUM> may be configured to open and close the various valves, control operation of dual-fuel system <NUM>, control the generation of saturated steam, control the duration and timing of the steam purge, control the transition between liquid and gas fuel operation of the gas turbine system <NUM>, and control aspects of operation of the gas turbine engine <NUM>.

<FIG> is a schematic in view of an embodiment of the gas turbine system <NUM>, illustrating a plurality of combustors <NUM> disposed inside the gas turbine enclosure <NUM>, wherein the steam purge system <NUM> includes a plurality of housings <NUM> at the elevated areas <NUM> on opposite sides of the gas turbine enclosure <NUM>. In particular, in the illustrated embodiment, the housings <NUM> are disposed on opposite sides of the gas turbine enclosure <NUM>, such that the liquid fuel lines <NUM> of the liquid fuel supply system <NUM> and the distribution lines <NUM> of the steam purge system <NUM> are evenly divided between the two housings <NUM>. Each of the housings <NUM> includes three liquid fuel lines <NUM> configured to receive steam from a corresponding three distribution lines <NUM> of the steam purge system <NUM>. As illustrated, each of the distribution lines <NUM> includes a check valve <NUM> configured to block backflow of liquid fuel into the steam purge system <NUM>, and each of the liquid fuel lines <NUM> includes a check valve <NUM> configured to block a backflow of steam into the liquid fuel supply system <NUM>. Additionally, as illustrated, the housings <NUM> are disposed at the elevated areas <NUM>, such that each of the liquid fuel lines <NUM> is angled downwardly toward the fuel nozzles <NUM> in each of the combustors <NUM> within the gas turbine enclosure <NUM>.

The illustrated embodiment has six combustors <NUM>, each having six fuel nozzles <NUM>. However, any suitable number of combustors <NUM> and fuel nozzles <NUM> is within the scope of the disclosed embodiments. The illustrated fuel nozzles <NUM> are arranged with a central fuel nozzle <NUM> and five outer or circumferential fuel nozzles <NUM>. The fuel nozzles <NUM> are also configured with a central liquid fuel cartridge <NUM> surrounded by a gas fuel supply area <NUM>. Details of these fuel nozzles <NUM> will be discussed in further detail below with reference to <FIG>.

<FIG> is a schematic of an embodiment of the ejector <NUM> of the steam purge system <NUM>. As illustrated, the ejector <NUM> receives a gas <NUM> (e.g., hot compressed air) from the gas supply <NUM> (e.g., air compressor <NUM>) through the gas line <NUM> having the valve <NUM>. The ejector <NUM> receives the gas <NUM> at a gas inlet <NUM>, which is fluidly coupled to a gas flow path <NUM> through a central gas conduit <NUM>. The ejector <NUM> is also coupled to the water supply <NUM> via the water line <NUM>, which includes the valve <NUM>, the check valve <NUM>, the water tank <NUM>, and the valve <NUM>. The water line <NUM> is coupled to the ejector <NUM> at a water inlet <NUM>. The illustrated ejector <NUM> has an outer wall <NUM> disposed circumferentially about a central axis <NUM>. For example, the outer wall <NUM> may be an annular outer wall defining an inner annular chamber <NUM>.

The outer wall <NUM> may define a converging section <NUM>, a throat <NUM> downstream from the converging section <NUM>, and a diverging section <NUM> downstream from the throat <NUM>. Accordingly, the ejector <NUM> provides a Venturi effect to help draw in the water and mix the water and gas <NUM> in the ejector <NUM>. The converging section <NUM>, the throat <NUM>, and the diverging section <NUM> may define annular walls or wall portions of the outer wall <NUM>. For example, the converging section <NUM> may define a curved annular wall portion or a conical wall portion of the outer wall <NUM>, which gradually decreases in cross-sectional area or diameter in the downstream flow direction (e.g., as indicated by the gas flow path <NUM>) toward the throat <NUM>. In turn, the diverging section <NUM> may define a curved annular wall portion or conical wall portion of the outer wall <NUM>, which increases in cross-sectional area or diameter from the throat <NUM> toward the outlet <NUM> of the ejector <NUM>.

In the illustrated embodiment, the central gas conduit <NUM> extends at least partially or entirely through the converging section <NUM> to the throat <NUM>. However, other embodiments may include a shorter or longer length of the central gas conduit <NUM>, such that an outlet <NUM> of the central gas conduit <NUM> may be disposed entirely within the converging section <NUM>, directly in throat <NUM>, or in the diverging section <NUM>. Some embodiments also may direct the gas <NUM> directly into the converging section <NUM> without use of the central gas conduit <NUM>.

The water inlet <NUM> is coupled to the outer wall <NUM> at the throat <NUM> of the ejector <NUM>. However, in certain embodiments, one or more water inlets <NUM> may be coupled to the outer wall <NUM> at locations upstream or downstream from the throat <NUM>. In operation, the flow of the gas <NUM> through the ejector <NUM> and particularly through the throat <NUM> into the diverging section <NUM> creates a suction that draws in the water through the water inlet <NUM>. Accordingly, the construction of the ejector <NUM> helps facilitate drawing in the water through the water inlet <NUM>, therefore helping to mix the water with the gas <NUM> in the throat <NUM> and the diverging section <NUM>. The relatively high pressure and temperature of the gas <NUM> also helps to facilitate steam formation as the gas <NUM> and the water mix within the ejector <NUM>.

For example, after a certain duration of time, the steam being generated within the ejector <NUM> may become saturated, thereby producing a saturated steam <NUM> within the ejector <NUM>. Initially, before the steam becomes saturated, the valve <NUM> may open to vent the steam through the vent line <NUM>, while the valve <NUM> is closed to block flow of the steam through the output line <NUM> to the liquid fuel lines <NUM> as discussed above with reference to <FIG>. However, after the steam becomes saturated, the valve <NUM> is closed and the valve <NUM> is opened by the controller <NUM>, thereby routing the saturated steam <NUM> through the output line <NUM> to the liquid fuel lines <NUM> as discussed above with reference to <FIG>.

<FIG> is a schematic of an embodiment of the gas turbine system <NUM> having the steam purge system <NUM> coupled to one of the combustors <NUM> along with the dual-fuel system <NUM>. As illustrated, the dual-fuel system <NUM> has both the liquid fuel supply system <NUM> and the gas fuel supply system <NUM> fluidly coupled to the fuel nozzles <NUM> of the combustor <NUM> via the liquid fuel lines <NUM> and gas fuel line <NUM>. Additionally, the steam purge system <NUM> is fluidly coupled to the liquid fuel line <NUM> via the distribution line <NUM> having the check valve <NUM>. Again, the check valve <NUM> and the distribution line <NUM> and the check valve <NUM> and the liquid fuel line <NUM> are configured to block backflow through those lines toward the steam purge system <NUM> and the liquid fuel supply system <NUM>, respectively.

The illustrated combustor <NUM> has a combustion section <NUM> and a head end <NUM>. The fuel nozzles <NUM> are disposed in the head end <NUM>, which is separated from the combustion section by a plate <NUM>. The combustion section <NUM> includes a combustion liner <NUM> disposed circumferentially about the combustion chamber <NUM>, and a flow sleeve <NUM> disposed circumferentially disposed about the combustion liner <NUM> to define an air flow passage <NUM>. The air flow passage <NUM> is fluidly coupled to a discharge from the compressor <NUM>, such that the air flow from the compressor flows between the flow sleeve <NUM> and combustion liner <NUM> in a flow direction toward the head end <NUM> as indicated by arrows <NUM>. Upon reaching the head end <NUM>, the air flow turns and enters each of the fuel nozzles <NUM> as indicated by arrows <NUM>.

Each of the fuel nozzles <NUM> includes an outer sleeve <NUM> disposed circumferentially about the liquid fuel cartridge <NUM>, and a plurality of vanes <NUM> (e.g., swirl vanes) extending radially between the outer sleeve <NUM> and the liquid fuel cartridge <NUM>. For example, the fuel nozzles <NUM> may include two to ten vanes <NUM> spaced circumferentially about the liquid fuel cartridge <NUM>. Each of these vanes <NUM> is configured to receive gas fuel from the gas fuel lines <NUM> of the gas fuel supply system <NUM>, thereby directing gas fuel into an air flow path <NUM> (as indicated by arrows <NUM>) between the outer sleeve <NUM> and the liquid fuel cartridge <NUM>. The air flow path <NUM> may be an annular air flow path defined by and between an annular shaped outer sleeve <NUM> and an annular shaped liquid fuel cartridge <NUM>. The fuel nozzles <NUM> include an upstream air inlet <NUM> and a downstream fuel-air mixture outlet <NUM>. Each fuel nozzle <NUM> is configured to receive the air <NUM> through the upstream air inlet <NUM>, swirl the air flow with the vanes <NUM>, inject gas fuel through outlets <NUM> disposed on the vanes <NUM> (in gas fuel operation), and mix the fuel and air within the outer sleeve <NUM> before exiting through the fuel-air mixing outlet <NUM> of the fuel nozzles <NUM>. In liquid fuel operation, the gas fuel is not injected through the outlets <NUM> of the vanes <NUM>. Instead, the liquid fuel is injected through the liquid fuel cartridge <NUM> and exits through one or more outlets <NUM> into the outer sleeve <NUM>. As discussed above with reference to <FIG>, the liquid fuel cartridge <NUM> also receives the atomizing flow <NUM> from the gas supply <NUM>, thereby helping to atomize the liquid fuel exiting from the liquid fuel cartridges <NUM>.

Accordingly, in the illustrated embodiment, the gas turbine system <NUM> is configured to selectively operate in a liquid fuel operation mode using the liquid fuel supply system <NUM>, the liquid fuel supply lines <NUM>, and the liquid fuel cartridges <NUM> in the fuel nozzles <NUM>. Additionally, the gas turbine supply system <NUM> is configured to selectively operate in a gas fuel operation mode using the gas fuel supply system <NUM>, the gas fuel lines <NUM>, and the vanes <NUM> disposed in the fuel nozzles <NUM>. The steam purge system <NUM> is configured to purge the liquid fuel circuit <NUM> when stopping the liquid fuel operation mode with the liquid fuel supply system <NUM> and/or when changing from the liquid fuel operation mode to the gas fuel operation mode using the gas fuel supply system <NUM>. The steam purge system <NUM> uses the ejector <NUM> to combine water and gas (e.g., hot compressed air) to generate steam (e.g., saturated steam) to purge the liquid fuel from the liquid fuel line <NUM>, the manifold <NUM>, the liquid fuel cartridges <NUM>, and various valves and other equipment along the liquid fuel circuit <NUM>.

<FIG> is a flow chart of an embodiment of a process <NUM> for purging the liquid fuel circuit <NUM> of the gas turbine system <NUM> with the steam purge system <NUM>. As illustrated, the process <NUM> may begin by stopping the liquid fuel flow to the fuel nozzles <NUM> (block <NUM>). For example, the process <NUM> may be initiating a switch between the liquid fuel operation mode via the liquid fuel supply system <NUM> and the gas fuel operation mode with the gas fuel supply system <NUM>, or the process <NUM> may be initiating a general shutdown of the gas turbine system <NUM>. The process <NUM> then proceeds to start a gas flow (e.g., a hot compressed air flow) to the ejector <NUM> of the steam purge system <NUM> (block <NUM>). For example, the process <NUM> may open the valve <NUM> along the gas line <NUM> and enable operation of the gas supply <NUM>, such as the compressor <NUM> (e.g., air compressor of the atomizing module <NUM>). The process <NUM> may then start a water flow from the water supply <NUM> to the ejector <NUM> of the steam purge system <NUM> via the water line <NUM> (block <NUM>). For example, the process <NUM> may open the valves <NUM> and <NUM> and initiate operation of the pump <NUM> to enable the water flow. The process <NUM> may then produce steam in the ejector <NUM> as the water and gas mix within the ejector <NUM> (block <NUM>).

As the ejector <NUM> begins to generate steam at block <NUM>, the process <NUM> may determine whether the steam is saturated at block <NUM>. In certain embodiments, the process <NUM> may determine whether or not the steam is saturated in block <NUM> based on a predetermined time (e.g., <NUM>, <NUM>, <NUM>, or <NUM> minutes), historical data of operation of the gas turbine engine <NUM>, computer models, sensor data regarding operation of the gas turbine engine <NUM> and the steam purge system <NUM>, and various other parameters. If the steam is not saturated at block <NUM>, then the process <NUM> vents the steam to atmosphere (block <NUM>) by closing the valve <NUM> along the output line to <NUM> and opening the valve <NUM> along the vent line <NUM>.

If the process <NUM> (at block <NUM>) determines that the steam is saturated, then the process <NUM> proceeds to open the flow of saturated steam through the liquid fuel circuit <NUM> of the gas turbine engine <NUM>, as indicated by block <NUM>. For example, the process <NUM> may open the valve <NUM> along the output line <NUM> and close the valve <NUM> along the vent line <NUM>, thereby enabling the saturated steam to flow through the manifold <NUM> into the distribution lines <NUM> to the liquid fuel lines <NUM>. Further, the process <NUM> may determine an appropriate duration of time for the steam purge depending on user input, historical data, sensor data, a time since a previous steam purge of the liquid fuel circuit <NUM>, or a predetermined time for the steam purge based on one or more conditions.

At block <NUM>, the process <NUM> may determine if the steam purge is complete. If the steam purge is not complete, then the process <NUM> may continue operating the steam purge, as indicated by block <NUM>. If the process <NUM> determines at block <NUM> that the steam purge is complete, then the process <NUM> may then proceed to stop the flow of saturated steam through the liquid fuel circuit <NUM> of the gas turbine engine <NUM> (block <NUM>).

Claim 1:
A gas turbine system (<NUM>), comprising:
a gas turbine engine (<NUM>) comprising a combustor (<NUM>) having a fuel nozzle (<NUM>) fluidly coupled to a liquid fuel line (<NUM>) of a liquid fuel circuit (<NUM>);
a steam purge system (<NUM>) to which the liquid fuel circuit (<NUM>) is fluidly coupled, said steam purge system (<NUM>) comprising:
a water supply (<NUM>);
a gas supply (<NUM>) comprising an atomizing module (<NUM>) and a compressor (<NUM>);
an ejector (<NUM>), comprising:
an outer wall (<NUM>) extending circumferentially about a flow path (<NUM>), wherein the outer wall (<NUM>) comprises a throat section (<NUM>) along the flow path (<NUM>), and a diverging section (<NUM>) downstream from the throat section (<NUM>) along the flow path (<NUM>);
a gas inlet (<NUM>) configured to supply a gas from the gas supply into the flow path (<NUM>);
a water inlet (<NUM>) configured to supply water from the water supply into the flow path (<NUM>), wherein the ejector (<NUM>) is configured to produce steam in response to mixing of the water and the gas along the flow path (<NUM>), wherein the compressor is configured to output compressed gas with a sufficient pressure and temperature to convert the water to steam in the ejector (<NUM>) without any additional heat sources;
a controller (<NUM>) configured to control flows of the gas and the water to produce the steam for a steam purge of the liquid fuel circuit (<NUM>).