Patent Description:
A gas turbine system may include a gas turbine engine having a compressor, a combustor, and a turbine driven by combustion gases from the combustor. Combustion of fuel in the combustor generates various exhaust emissions, such as nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter, and other pollutants. Unfortunately, some of these exhaust emissions may be visible (e.g., a yellow plume) when discharged from the gas turbine system into the atmosphere under some operating conditions, such as start-up when the downstream emission control systems (e.g., carbon monoxide (CO) and selective catalytic reduction (SCR) catalysts) may not be fully functional. Accordingly, as emission regulations and community awareness are getting stricter in some parts of the world, a need exists for reducing concentrations of exhaust emissions and the corresponding visibility of such emissions being exhausted into the atmosphere.

<CIT> discloses systems and methods for cooling the exhaust gas of power generation systems; <CIT> use of a gas turbine heated fluid for reductant vaporization; <CIT> method and plant for reducing the nitrogen oxide emissions of a gas turbine; <CIT> a gas turbine uniformizing the temperature distribution of the combustion gas that acts on a plurality of stator vanes and rotor blades or limiting temperature unevenness; <CIT> a gas turbine device additionally providing exhaust gas boiler with built-in exhaust gas denitrification device; and <CIT> an emission control system for a gas turbine engine.

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

A method in accordance with the invention as hereinafter claimed comprises the features of claim <NUM> below.

These and other features, aspects, and advantages of the present system 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 system will be described below.

The disclosed embodiments are directed toward systems and methods to reduce exhaust emissions, and a corresponding visibility of such exhaust emissions, in a gas turbine system. The exhaust emissions may include any undesirable pollutants or emissions that are visible in an exhaust being discharged from the gas turbine system. For example, the exhaust emissions may include nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter, and other pollutants. The visible emissions may have a variety of colors depending on the type and concentration of the exhaust emissions. For example, the visible emissions may be yellow (e.g., a yellow plume) when the concentration of nitrogen oxides (e.g., nitrogen dioxide (NO<NUM>)) exceed a threshold level.

The disclosed embodiments include an emissions control system and associated method to reduce the concentration and visibility of such exhaust emissions by, for example, supplying a reducing agent into one or more fluid pathways of the gas turbine engine (e.g., a cooling circuit or a bypass circuit). For example, the cooling circuit may extend through various parts of the gas turbine system that typically heat up during operation and/or that benefit from cooling to improve performance or extend the life of the parts. For example, the cooling circuit may include one or more cooling flow paths that extend along and/or through portions of the combustor (e.g., framework, combustor liner, head end, etc.), rotating parts (e.g., shaft, bearings, seals, etc.), portions of the turbine (e.g., rotating turbine blades, stationary turbine vanes, turbine nozzles, turbine wheels, turbine casings, etc.), or any other parts of the gas turbine system exposed to the heat of combustion or exhaust gases. The bypass circuit may include bypass lines coupled to the compressor (e.g., one or more compressor stages) and other portions of the gas turbine system (e.g., one or more turbine stages of the turbine).

The reducing agent flows through these fluid pathways and eventually enters a flow path of the exhaust gas, wherein the reducing agent is then able to help reduce the concentration of the exhaust emissions and the corresponding visibility of such exhaust emissions. By using the fluid pathways of the gas turbine engine, the emissions control system and method may be retrofitted into exhaust gas turbine systems by using pre-existing fluid pathways. The use of the fluid pathways also may improve the distribution and mixing of the reducing agent in the exhaust gas and may increase the residence time of the reducing agent in the exhaust gas upstream from one or more additional emissions control systems, such as a selective catalytic reduction (SCR) system disposed in an exhaust duct downstream from the turbine.

<FIG> is a block diagram of an embodiment of a gas turbine system <NUM> having an emissions control system <NUM> configured to reduce the level of exhaust emissions and the visibility of the exhaust emissions (e.g., nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter, and other pollutants). In the illustrated embodiment, the gas turbine system <NUM> includes a turbine engine <NUM> coupled to a load <NUM>, e.g., an electrical generator. In one embodiment, the turbine engine <NUM> may be a 7FA gas turbine engine manufactured by General Electric Company, Greenville, S. The turbine engine <NUM> includes an air intake <NUM>, a compressor <NUM>, one or more fuel nozzles <NUM>, a combustor <NUM>, a turbine <NUM>, and an exhaust duct <NUM>. The exhaust duct <NUM> may include a horizontal duct portion <NUM> and a vertical stack portion <NUM>. However, the duct <NUM> may extend in any direction to an exhaust outlet.

As appreciated, the compressor <NUM> may include any number of stages, e.g., <NUM> to <NUM> stages, of compressor blades rotatable in shrouds. Likewise, the turbine <NUM> may include any number of stages, e.g., <NUM> to <NUM> stages, of turbine blades rotatable in shrouds. The turbine engine <NUM> can also include multiple compressor <NUM>-turbine <NUM> couples as found, e.g., in a two shaft aeroderivative turbine engine <NUM>. The combustor <NUM> also may include a single combustor (e.g., an annular combustor) or multiple combustors (e.g., <NUM> to <NUM> combustor cans arranged circumferentially about a rotational axis of the turbine engine <NUM>) arranged in any manner including different designs not mentioned here.

In operation, the turbine engine <NUM> routes air <NUM> through the air intake <NUM> and the compressor <NUM>, which generates compressed air <NUM> for combustion and cooling flows. In the illustrated embodiment, the fuel nozzles <NUM> within the combustor <NUM> receive at least a portion of the compressed air <NUM> and a fuel <NUM>, which are then directed into a combustion zone of the combustor <NUM> as indicated by arrows <NUM>. A portion of the compressed air <NUM> also may flow along the combustor <NUM> and/or the turbine <NUM> for cooling purposes. Inside the combustor <NUM> (e.g., inside the combustion liner), the air <NUM> and the fuel <NUM> mix and combust to generate hot products of combustion, which then flow into and through the turbine <NUM> and the exhaust duct <NUM>. These combustion gases drive turbine blades to rotate within the turbine <NUM>, thereby driving a shaft <NUM> to rotate the compressor <NUM> and the load <NUM>.

The emissions control system <NUM> includes an emissions control unit <NUM> coupled to an emissions control fluid supply system <NUM> and a monitoring system <NUM>. The emissions control unit <NUM> includes a controller <NUM> having a processor <NUM>, a memory <NUM>, and instructions <NUM> stored on the memory <NUM> and executable by the processor <NUM> to control the emissions control fluid supply system <NUM> based on feedback from the monitoring system <NUM>. The emissions control fluid supply system <NUM> includes one or more emissions control fluid supplies <NUM>, one or more flow control units <NUM>, and one or more fluid supply conduits <NUM>. The emissions control fluid supplies <NUM> may include one or more tanks or storage containers configured to hold and supply emissions control fluids, such as reducing agents. For example, the emissions control fluid supplies <NUM> (e.g., reducing agent supplies) may include tanks or storage containers of reducing agents, such as ammonia, ethanol, alcohol, and/or hydrogen. The flow control units <NUM> may include one or more valves, pressure regulators, flowmeters or flow regulators, or any combination thereof. The flow control units <NUM> may include electric actuators controlled by the emissions control unit <NUM>. In the following discussion, the flow control units <NUM> may be referred to as valves; however, any reference to valves may include other types of flow control units as noted above.

The fluid supply conduits <NUM> may be coupled to one or more fluid pathways <NUM> of the gas turbine system <NUM>, such that the emissions control system <NUM> can supply one or more of the emissions control fluids (e.g., reducing agents) into the fluid pathways to reduce the level of exhaust emission and the visibility of the exhaust emissions. Additionally, the monitoring system <NUM> may include one or more sensors <NUM>, indicated by S, configured to obtain sensor feedback of one or more parameters of the gas turbine system <NUM>, such that the emissions control system <NUM> can adjust (e.g., increase or decrease) the supply of the emissions control fluids (e.g., reducing agents) based on the sensor feedback. The sensors <NUM> may be distributed throughout the gas turbine system <NUM> at various locations, such as the compressor <NUM>, the combustor <NUM>, the turbine <NUM>, and the exhaust duct <NUM>.

The sensor feedback of one or more operating parameters may include, or be indicative of, a level of the exhaust emissions and/or a visibility of the exhaust emissions. For example, the sensors <NUM> may include exhaust emissions sensors (e.g., NOx sensors, SOx sensors, particulate matter sensors, and other pollutant sensors) configured to sense emissions levels in the exhaust gas. The sensors <NUM> include visibility sensors, such as opacity sensors, color sensors, or a combination thereof. The visibility sensors <NUM> may be configured to sense an intensity or level of opacity and/or color of the exhaust emissions in the exhaust gas. Additionally, the sensors <NUM> may include pressure sensors, temperature sensors (e.g., combustion temperature sensors), flow rate sensors (e.g., fuel flow rate sensors), vibration sensors, and/or fuel composition sensors.

In response to the sensor feedback from the sensors <NUM>, the emissions control system <NUM> may be configured to (A) selectively supply one or more different emissions control fluids (e.g., reducing agents) by opening and/or closing the flow control units <NUM> associated with the different emissions control fluid supplies <NUM>, (B) adjust (e.g., increase or decrease) the flow of the selected emissions control fluids to the one or more fluid pathways <NUM> of the gas turbine system <NUM>, and (C) selectively change the target destination of the selected emissions control fluids in the one or more fluid pathways <NUM> as discussed further below. For example, the emissions control unit <NUM> may compare the sensor feedback against one or more thresholds (e.g., upper and/or lower thresholds), determine if the sensor feedback indicates compliance with the one or more thresholds (e.g., falls within acceptable levels or fails to meet the acceptable levels), and then adjust the emissions control fluid supply system <NUM> based on the indicated compliance or lack of compliance.

For example, the one or more thresholds may include one or more visibility thresholds (e.g., opacity thresholds and/or color thresholds), such as a minimum or lower visibility threshold and an upper or maximum visibility threshold. If the sensed visibility (e.g., opacity or color) does not meet the minimum or lower visibility threshold, then the emissions control unit <NUM> may selectively increase a flow of the emissions control fluids to the one or more fluid pathways <NUM> to help reduce the level of emissions and reduce the visibility of the emissions in the exhaust gas. If the sensed visibility (e.g., opacity or color) meets the minimum or lower visibility threshold and exceeds the maximum or upper visibility threshold, then the emissions control unit <NUM> may selectively hold or reduce a flow of the emissions control fluids to the one or more fluid pathways <NUM> to avoid wasting the emissions control fluid while maintaining an acceptable level of emissions and an acceptable visibility of the emissions in the exhaust gas. In certain embodiments, the one or more visibility thresholds (e.g., opacity thresholds and/or color thresholds) may correspond to a yellow plume in the exhaust gas, and thus the thresholds may correspond to an opacity and/or intensity of yellow in the yellow plume. However, the disclosed emissions control system <NUM> may be used for any exhaust emissions and associated colors in the exhaust gas.

The fluid pathways <NUM> may include external conduits outside the gas turbine engine <NUM>, internal passages or conduits extending through the gas turbine engine <NUM>, or a combination thereof. For example, the fluid pathways <NUM> may include one or more compressor bleed conduits <NUM> coupled to one or more compressor stages of the compressor <NUM>. In the illustrated embodiment, the compressor bleed conduits <NUM> are coupled to the compressor <NUM> driven by the gas turbine engine <NUM>. In some embodiments, the compressor bleed conduits <NUM> may be coupled to a standalone compressor (e.g., not driven by the gas turbine engine <NUM>). The emissions control system <NUM> may selectively open or close valves along the compressor bleed conduits <NUM> to change the temperature and pressure of the compressor bleed air being extracted from the compressor <NUM> depending on the location (e.g., compressor stage) of extraction.

As an alternative or in addition to the compressor bleed conduits <NUM>, the fluid pathways <NUM> may include one or more coolant supplies <NUM>, such as an air supply, an inert gas supply (e.g., a nitrogen gas supply), a recirculated exhaust gas supply, or a combination thereof. For example, the coolant supplies <NUM> may include one or more storage tanks, compressors, pumps, or a combination thereof. In some embodiments, the coolant supplies <NUM> may include a standalone air compressor, such as an air compressor skid, which may supplement or replace the compressor bleed air from the compressor <NUM>. The one or more compressor bleed conduits <NUM> and/or the one or more coolant supplies <NUM> are coupled to one or more distribution conduits <NUM>, which are configured to fluidly couple to one or more target locations throughout the gas turbine system <NUM>.

In certain embodiments, the distribution conduits <NUM> include one or more coolers <NUM> (e.g., heat exchangers) configured to cool the flows from the compressor bleed conduits <NUM> and/or the coolant supplies <NUM>. For example, in certain embodiments, at least one of the coolant supplies <NUM> is configured to flow a coolant through the cooler <NUM> to transfer heat away from the compressor bleed air from the compressor bleed conduits <NUM> and/or a different coolant from a different one of the coolant supplies <NUM>. In some embodiments, at least one of the coolant supplies <NUM> is configured to direct a coolant into the compressor bleed conduit <NUM> with or without the compressor bleed air from the compressor bleed conduits <NUM>. Accordingly, the compressor bleed air from the compressor bleed conduits <NUM> and/or the coolant from one or more of the coolant supplies <NUM> may be described as coolant supplies for other components of the gas turbine system <NUM>.

The foregoing coolant supplies (e.g., <NUM>, <NUM>) are fluidly coupled to one or more target locations in the gas turbine system <NUM> via the distribution conduits <NUM>, such as one or more coolant conduits <NUM>, <NUM>, <NUM>, and <NUM> as described below. For example, the fluid pathways <NUM> may include one or more coolant conduits <NUM> fluidly coupled to bearing cavities or housings having bearings <NUM> for the shaft <NUM>. These bearing cavities or bearings <NUM> may be part of an internal cooling circuit of the gas turbine engine <NUM>.

The fluid pathways <NUM> may include one or more coolant conduits <NUM> fluidly coupled to the combustor <NUM>. For example, the coolant conduits <NUM> may be fluidly coupled to an internal compressed air flow path between a combustor liner <NUM> and a flow sleeve <NUM> of the combustor <NUM>, an internal cavity in a head end <NUM> of the combustor <NUM>, an internal cavity of the fuel nozzles <NUM>, or a combination thereof. The foregoing flow paths or cavities of the combustor <NUM> may be part of an internal cooling circuit of the gas turbine engine <NUM>.

The fluid pathways <NUM> also may include one or more coolant conduits <NUM> fluidly coupled to one or more turbine stages of the turbine <NUM>. For example, the coolant conduits <NUM> may fluidly couple to an internal cooling flow path between an outer casing <NUM> and an inner shroud <NUM> of the turbine <NUM>, and one or more internal cooling flow paths through turbine stator vanes, turbine rotor blades, turbine wheels, and/or bearing cavities. Again, the foregoing flow paths of the turbine <NUM> may be part of an internal cooling circuit of the gas turbine engine <NUM>.

The fluid pathways <NUM> also may include one or more conduits <NUM> (e.g., bypass conduits) fluidly coupled to the exhaust duct <NUM> downstream from the turbine <NUM>. The conduits <NUM> may be coupled to the exhaust duct <NUM> upstream, downstream, or at locations of one or more emissions control units <NUM> inside the exhaust duct <NUM>. The exhaust duct <NUM> may include any number and arrangement (e.g., parallel or series arrangements) of emissions control units <NUM>, such as emissions control units <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In certain embodiments, the emissions control system <NUM> may include a fluid manifold <NUM> configured to distribute the coolant from the conduits <NUM>, <NUM> into the exhaust duct <NUM>. The fluid manifold <NUM> also may be configured to inject other fluids into the exhaust duct <NUM>, such as emissions control fluids (e.g., reducing agents) supplied by the emissions control fluid supply system <NUM>.

The emissions control units <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>) may include one or more of: heat exchangers, evaporators, emissions control fluid injection grids, catalysts (e.g., selective catalytic reduction (SCR) systems), or any combination thereof. For example, in certain embodiments, the emissions control units <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may include a first injection grid, a heat exchanger (e.g., a high pressure superheater), a second injection grid, an evaporator (e.g., a high pressure evaporator), and a SCR system, respectively. The first and second injection grids (e.g., <NUM>, <NUM>) may be configured to inject the same or different emissions control fluids. For example, the first injection grid (e.g., <NUM>) may be configured to inject a first emissions control fluid comprising ethanol, and the second injection grid (e.g., <NUM>) may be configured to inject a second emissions control fluid comprising ammonia. The emissions control fluids may be injected into the exhaust gas in liquid form (e.g., as a spray) via the injection grids, in vapor form (e.g., vaporized with additional heat) via an evaporator, or any combination thereof. For example, the second injection grid <NUM> may be configured to inject ammonia (e.g., ammonia solution or anhydrous ammonia) or in some cases urea that can be hydrolyzed/decomposed in the end making vaporized ammonia.

In the illustrated embodiment, the emissions control system <NUM> is configured to supply the emissions control fluid directly into the exhaust gas via the fluid conduit <NUM> coupled to the exhaust duct <NUM> and/or indirectly into the exhaust gas via the one or more fluid pathways <NUM> (e.g., coolant circuits in the gas turbine engine <NUM>) as discussed above. Accordingly, based on an analysis of the sensor feedback from sensors <NUM> as discussed above, the emissions control unit <NUM> may selectively adjust one or more flow control units <NUM> (e.g., valves) to vary a flow of the emissions control fluid (e.g., reducing agent) from the one or more emissions control fluid supplies <NUM> into the one or more fluid pathways <NUM> eventually leading into the exhaust gas and also directly into the exhaust duct <NUM> via the fluid supply conduit <NUM>. At the exhaust duct <NUM>, the supplied emissions control fluid may be injected via one or more of the emissions control units <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>), such as via an injection grid and/or an evaporator as discussed above. The injection grid(s) may include a plurality of conduits (e.g., parallel conduits) having injection openings or nozzles distributed across an exhaust flow path of the exhaust duct <NUM>. A heat exchanger may be used to add heat to the exhaust flow path, thereby helping to evaporate the injected emissions control fluid. An evaporator may be used to evaporate the emissions control fluid prior to injection into the exhaust flow path. The supply of the emissions control fluid into the one or more fluid pathways <NUM> of the gas turbine engine <NUM> may improve the mixing and residence time of the emissions control fluid with the exhaust gas, thereby helping to reduce emissions and visibility of the emissions before being discharged from the exhaust duct <NUM> into the atmosphere.

<FIG> is a partial cross-sectional view of an embodiment of the turbine <NUM> of <FIG>, illustrating cooling flows along the fluid pathways <NUM> inside the turbine <NUM>. In the illustrated embodiment, the turbine <NUM> includes a rotor <NUM> circumferentially surrounded by a stator <NUM>, wherein the turbine <NUM> includes a plurality of axially spaced turbine stages <NUM>. In each stage <NUM>, the rotor <NUM> includes a plurality of turbine blades <NUM> mounted in a circumferential arrangement about a wheel <NUM>, and the stator <NUM> includes a plurality of stator vanes <NUM> mounted in a similar circumferential arrangement about a casing <NUM>. The illustrated casing <NUM> includes the outer casing <NUM> and an inner shroud <NUM>, wherein the outer casing <NUM> has a plurality of hangers <NUM> supporting shroud segments <NUM>. In particular, each hanger <NUM> includes a pair of hooks <NUM> and <NUM>, which mate with complementary hooks <NUM> and <NUM> of the respective shroud segment <NUM>. These shroud segments <NUM> generally align with the turbine blades <NUM> in each stage <NUM> and define a clearance <NUM>. In operation, the hot combustion gases flow through each stage <NUM>, thereby driving rotation of the turbine blades <NUM> within the respective shroud segments <NUM>.

In the illustrated embodiment, various components of the turbine <NUM> (e.g., the rotor <NUM>, the stator <NUM>, the blades <NUM>, the wheels <NUM>, the stator vanes <NUM>, and the casing <NUM>) include one or more of the fluid pathways <NUM> discussed above with reference to <FIG>. For example, the fluid pathways <NUM> may extend through the rotor <NUM>, around and/or into the wheels <NUM>, and into an exhaust flow path <NUM> as indicated by arrows <NUM>. The fluid pathways <NUM> also may extend from the rotor <NUM>, into and through the blades <NUM>, and into the exhaust flow path <NUM> as indicated by arrows <NUM>. As illustrated by arrows <NUM>, the fluid pathways <NUM> may extend into and through the stator <NUM> between the outer casing <NUM> and the inner shroud <NUM> of the casing <NUM>, through and/or around the shroud segments <NUM> and into the exhaust flow path <NUM>, through the stator vanes <NUM> and into the exhaust flow path <NUM>, and/or through the stator vanes <NUM> to the rotor <NUM> and then into the exhaust flow path <NUM>.

The illustrated fluid pathways <NUM> (e.g., as represented by arrows <NUM>, <NUM>, and <NUM>) are used by the emissions control system <NUM> to supply one or more emissions control fluids (e.g., reducing agents) into the exhaust flow path <NUM> upstream of an exhaust outlet <NUM> of the turbine <NUM>. As noted above, the illustrated fluid pathways <NUM> may be part of a cooling circuit (e.g., a turbine cooling circuit) of the gas turbine engine <NUM>. Thus, the emissions control system <NUM> advantageously supplies the one or more emissions control fluids (e.g., reducing agents) into the cooling circuit, such that the emissions control system <NUM> can be retrofitted into any new or pre-existing gas turbine engine <NUM> (e.g., already installed on site) to improve the emissions control of the gas turbine system <NUM>.

<FIG> is a diagram of an embodiment of the gas turbine system <NUM>, illustrating an embodiment of the emissions control system <NUM> having a valve control system <NUM> and a flow meter system <NUM> configured to control and monitor flows along the fluid pathways <NUM>. In the following discussion, reference may be made to an axial direction or axis <NUM> (e.g., along a longitudinal axis) of the gas turbine engine <NUM>, a radial direction or axis <NUM> extending radially away from the longitudinal axis of the gas turbine engine <NUM>, and a circumferential direction or axis <NUM> extending circumferentially about the longitudinal axis of the gas turbine engine <NUM>. Reference may also be made to a downstream direction <NUM> and an upstream direction <NUM> relative the flow direction through the gas turbine engine <NUM>.

In the illustrated embodiment, each of the compressor bleed conduits <NUM> coupled to the compressor <NUM> includes a valve <NUM> and a flowmeter <NUM> communicatively coupled to the emissions control unit <NUM>. For example, the compressor bleed conduits <NUM> may be coupled to extraction points <NUM> at different stages of the compressor <NUM>, such that different temperatures and pressures of compressor bleed air can be extracted from the compressor <NUM> into the compressor bleed conduits <NUM>.

Similarly, each of the coolant conduits <NUM> coupled to the turbine <NUM> includes a valve <NUM> and a flowmeter <NUM> communicatively coupled to the emissions control unit <NUM>. For example, the coolant conduits <NUM> may be coupled to injection points <NUM> at different stages of the turbine <NUM>, such that the same or different coolant flows can be injected into the turbine <NUM> depending on the temperature in various locations in the turbine <NUM>.

Similarly, each of the coolant conduits <NUM> coupled to the exhaust duct <NUM> includes a valve <NUM> and a flowmeter <NUM> communicatively coupled to the emissions control unit <NUM>. For example, the coolant conduits <NUM> may be coupled to injection points <NUM> at different positions (e.g., different axial positions relative to the downstream direction <NUM>), such that the same or different coolant flows can be injected into the exhaust duct <NUM> at various positions relative to the emissions control units <NUM> (e.g., upstream, downstream, or directly at the units <NUM>). The illustrated emissions control units <NUM> include a duct burner assembly <NUM> having a plurality of duct burners <NUM> positioned upstream from a SCR system <NUM>. The illustrated injection points <NUM> are disposed at a first position upstream from both the duct burner assembly <NUM> and the SCR system <NUM>, at a second position between the duct burner assembly <NUM> and the SCR system <NUM>, and at a third position downstream from both the duct burner assembly <NUM> and the SCR system <NUM>.

In operation, as discussed above, the emissions control unit <NUM> is configured to monitor flowrates of the coolant flows via the flowmeters <NUM>, <NUM>, and <NUM> of the flow meter system <NUM> and to selectively adjust the valves <NUM>, <NUM>, and <NUM> of the valve control system <NUM> to control the coolant flows from the compressor <NUM> into the turbine <NUM> and the exhaust duct <NUM>. Additionally, the emissions control unit <NUM> is configured to selectively control the flow control units <NUM> to supply one or more emissions control fluids into the one or more fluid pathways <NUM>. In certain embodiments, the emissions control system <NUM> is configured to supply the one or more emissions control fluids into a common distribution conduit <NUM> coupled to the coolant conduits <NUM> and/or the coolant conduits <NUM>. However, in some embodiments, the emissions control system <NUM> is configured to supply the one or more emissions control fluids into a separate distribution conduit <NUM> coupled to each of the coolant conduits <NUM> and/or a separate distribution conduit <NUM> coupled to each of the coolant conduits <NUM>.

Each valve <NUM>, <NUM>, and <NUM> may be a ball valve, a globe valve, a butterfly valve, a diaphragm valve, or any other valve type that allows for rotary or sliding action to control the flow of a fluid. In some embodiments, the valves <NUM>, <NUM>, and/or <NUM> may be multi-way valves (e.g., <NUM>-way valves) or include injection ports to supply the emissions control fluid into the one or more fluid pathways <NUM>. The flowmeters <NUM>, <NUM>, and <NUM> may include mechanical flowmeters (e.g., gear flowmeters, turbine flowmeters, and/or jet flowmeters), pressure-based flowmeters (e.g., venturi meters), variable area flowmeters, optical flowmeters, magnetic flowmeters, ultrasonic flowmeters, or any combination thereof.

The valve control system <NUM> may be operated by the controller <NUM> based at least in part on flowrate information sensed by the flow meter system <NUM>. For example, flow information acquired from the flowmeters <NUM>, <NUM>, and <NUM> may be analyzed by the controller <NUM> to determine operation of the valves <NUM>, <NUM>, and <NUM>. In one or more embodiments, the controller <NUM> may automatically control the position of the valves <NUM>, <NUM>, and <NUM> to adjust the flow path (i.e., open a valve to allow flow, close a valve to stop flow). In one or more embodiments, the controller <NUM> determines flow of an emissions control fluid (e.g., reducing agent) through the gas turbine system <NUM>. The controller <NUM> may be located with the gas turbine system <NUM> or separate in a remote location receiving information through a network (e.g., located in an operating room receiving data via a LAN network).

<FIG> shows a detailed view of the extraction points <NUM>, the injection points <NUM> into the turbine <NUM>, the injection points <NUM> into the exhaust duct <NUM>, and a cooling circuit <NUM> associated with the gas turbine engine <NUM>. The extraction points <NUM> may include low pressure, medium pressure, and high pressure extraction points, which are configured to obtain a low pressure air extraction <NUM>, a medium pressure air extraction <NUM>, and a high pressure air extraction <NUM> for use in the cooling circuit <NUM>. The injection points <NUM> may include high pressure, medium pressure, and low pressure injection points, which are configured to inject the extracted compressor air into a high pressure turbine section <NUM>, a medium pressure turbine section <NUM>, and a low pressure turbine section <NUM> of the turbine <NUM> for use in the cooling circuit <NUM>. In one or more embodiments, the extraction points <NUM> and the injection points <NUM> may not be limited to the pressure rating of the fluid (i.e., low, medium, and high) and may, for example, be determined by the flow rate of the fluid. Additionally, the pressure ratings may be distinguished and not limited to low, medium, and high. For example, the labeling may use the specific pressure of the extraction point, the stage of the extraction point, or a combination thereof.

As discussed above, the emissions control system <NUM> is configured to supply one or more emissions control fluids (e.g., reducing agents) into fluid pathways <NUM> of the cooling circuit <NUM>, thereby combining the emissions control fluids with the extracted air being supplied into the injection points <NUM> into the turbine <NUM>. The cooling circuit <NUM> may include a connected series of pipes or tubes that interconnect with the injection points <NUM> and extraction points <NUM> via valves, fittings, open connections, or any other type of connection. A combination of air and emissions control fluid passes through the fluid pathways <NUM> inside the turbine <NUM> (e.g., through casings, blades, vanes, wheels, etc.) and eventually flows into the exhaust gas flowing through and driving the turbine <NUM>.

Additionally, the emissions control system <NUM> is configured to supply one or more emissions control fluids (e.g., reducing agents) into fluid pathways <NUM> leading directly to the exhaust duct <NUM>, such as the injection points <NUM>. In the illustrated embodiment, the injection points <NUM> include a first injection point <NUM> upstream of the duct burner assembly <NUM>, a second injection point <NUM> between the duct burner assembly <NUM> and the SCR system <NUM>, and a third injection point <NUM> downstream of the SCR system <NUM>. Again, the emissions control system <NUM> is configured control the flows of emissions control fluids to these injection points <NUM> and <NUM> to reduce the level of exhaust emissions and the visibility of the exhaust emissions (e.g., nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter, and other pollutants).

<FIG> shows an expanded view of the gas turbine system <NUM> with an injection system <NUM> coupled to the exhaust duct <NUM>. In one or more embodiments, the injection system may provide an ammonia solution or anhydrous ammonia, or, in some cases, urea that may be hydrolyzed or decomposed to produce vaporized ammonia. As discussed above with reference to <FIG>, the exhaust duct <NUM> may include one or more emissions control units <NUM>. In the illustrated embodiments, the injection system <NUM> is part of the emissions control units <NUM>. For example, the emissions control units <NUM> of the injection system <NUM> may include injection grids <NUM> and <NUM>, and the emissions control units <NUM> may also include a SCR system <NUM>, a heat exchanger <NUM> (e.g., a high pressure superheater), and an evaporator <NUM> (e.g., a high pressure evaporator) in the exhaust duct <NUM>. In one or more embodiments, the injection grids <NUM> and <NUM> may be yellow plume elimination systems (YPES). The injection grids <NUM> and <NUM> may utilize various emissions control fluids (e.g., reducing agents such as ethanol, ammonia, and/or alcohol) to cool and reduce exhaust emissions in the exhaust gas <NUM> passing through the injection grids <NUM> and <NUM>.

In one or more embodiments, the amount of emissions control fluid injected is controlled by a remote operator and/or the controller <NUM> based on sensor feedback and various thresholds as discussed in detail above. For example, the controller <NUM> may adjust (e.g., increase or decrease) the flow of the emissions control fluids if the temperature of the exhaust gas <NUM> is above or below one or more temperature thresholds, if the visibility of exhaust emissions is above or below one or more visibility thresholds, and/or if the level of exhaust emissions is above or below one or more emissions thresholds. The injection grids <NUM> and <NUM> may operate during start up, steady state, and shut down of the gas turbine system <NUM> to decrease the exhaust emissions (e.g., NOx, SOx,, or other pollutants) and the visibility of the exhaust emissions in the exhaust gas <NUM>.

In addition to the injection grids <NUM> and <NUM>, the gas turbine system <NUM> may utilize the SCR system <NUM> to decrease levels of the exhaust emissions. The SCR system <NUM> may be used in conjunction with the injection grids <NUM> and <NUM> or as a stand-alone system. As pollutants, such as NOx, flow through the SCR system <NUM>, the catalyst converts the NOx into nitrogen and water through reaction with vaporized ammonia as a reduction agent. The catalyst of the SCR system <NUM> may be made from various ceramic materials such as titanium oxide, vanadium, molybdenum, tungsten, zeolites, or various precious metals. Each material may have advantages and disadvantages, such as operating temperature range, thermal durability, and catalyzing potential. The SCR system <NUM> may receive an injection of a reducing agent to reduce pollutants. The amount of reducing agent (e.g., vaporized ammonia) may be controlled by the controller <NUM>.

The SCR system <NUM> may use a high temperature (><NUM>°F) to achieve a high conversion rate of NOx to nitrogen and water. The heat exchanger <NUM> is configured to add heat into the exhaust gas <NUM> upstream of the SCR system <NUM>, thereby helping to improve the conversion rate of the NOx. In certain embodiments, a heated fluid (e.g., steam) may circulate through the heat exchanger <NUM> and transfer heat from the heated fluid into the exhaust gas <NUM>. For example, the heat exchanger <NUM> may include a superheater (e.g., a high pressure superheater or steam drum) of a heat recovery steam generator (HRSG), which recovers heat from the exhaust gas <NUM> to generate steam for a steam turbine. The heated fluid (e.g., steam) flowing through the heat exchanger <NUM> may be at a temperature greater than or equal to a target temperature suitable for the SCR system <NUM>, such as a steam temperature greater than <NUM>°F.

The gas turbine system <NUM> may also include a blower <NUM> coupled to the exhaust duct <NUM> downstream of the turbine <NUM>. The blower <NUM> may be an air blower that assists in dilution by providing blowback air across the compressor <NUM> and the turbine <NUM>. The blower <NUM> may be linked to the controller <NUM> that monitors the gas turbine system <NUM>. The controller <NUM> may adjust the operational speed of the blower <NUM> or turn on/off the blower <NUM> based on the requirements of the gas turbine system <NUM>.

The gas turbine system <NUM> may also include a reducing solution system <NUM>. The reducing solution system <NUM> may connect to the gas turbine system <NUM> via the injection grids <NUM> and <NUM>. In one or more embodiments, the reducing solution system <NUM> may connect to the gas turbine system <NUM> via one or more fluid pathways <NUM>, such as the cooling circuit <NUM>. The connection may be made through pipes, tubes, valves, and other methods of mechanical connection. The connection may allow one or more reducing agents to be injected directly into the injection grids <NUM> and <NUM>, one or more fluid pathways <NUM>, the cooling circuit <NUM>, or the SCR system <NUM>. In one or more embodiments, the reducing agent may be delivered through the air cooling and/or bleeding lines of the gas turbine <NUM>, e.g., fluid pathways <NUM>. The reducing agent may be ammonia (solution, anhydrous, or derived from urea or other ammonia compounds), ethanol, alcohol, or any other type of chemical configured to reduce exhaust emissions.

In one or more embodiments, the reducing solution system <NUM> may include an ammonia solution train <NUM> and a reducing solution train <NUM>. The ammonia solution train <NUM> may include an ammonia solution tank <NUM>, a pump <NUM>, a valve <NUM>, an evaporator or evaporation tank <NUM>, electric heaters <NUM> and <NUM>, an air blower <NUM>, and a fluid conduit <NUM> coupled to the injection grid <NUM>. The pump <NUM> and valve <NUM> are controlled by the controller <NUM> to adjust (e.g., increase or decrease) a flow of an ammonia solution from the ammonia solution tank <NUM> to the evaporator <NUM>, while the air blower <NUM> provides an airflow to the evaporator <NUM>. The electric heaters <NUM> and <NUM> are configured to heat the airflow and/or the ammonia solution in the evaporator <NUM>, thereby evaporating the ammonia solution to supply an evaporated ammonia solution to the injection grid <NUM>.

The reducing solution train <NUM> may include a reducing solution tank <NUM>, a pump <NUM>, a valve <NUM>, an evaporator or evaporation tank <NUM>, an electric heater <NUM>, and a fluid conduit <NUM> coupled to the injection grid <NUM>. The pump <NUM> and valve <NUM> are controlled by the controller <NUM> to adjust (e.g., increase or decrease) a flow of a reducing solution (e.g., ethanol) from the reducing solution tank <NUM> to the evaporator <NUM>. The electric heater <NUM> is configured to heat the reducing solution in the evaporator <NUM>, thereby evaporating the reducing solution to supply an evaporated reducing solution to the injection grid <NUM>.

In addition to supplying emissions control fluids to the exhaust duct <NUM>, the reducing solution system <NUM> may be integrated with or cooperate with the emissions control fluid supply system <NUM> of the emissions control system <NUM> to supply the ammonia solution and/or the reducing solution into the one or more fluid pathways <NUM>.

<FIG> is a diagram illustrating an embodiment of the reducing solution system <NUM> of the emissions control system <NUM> interacting with the gas turbine system <NUM>. The reducing solution system <NUM> includes the ammonia solution train <NUM> and the reducing solution train <NUM> having the tanks <NUM> and <NUM> connected to a single control valve <NUM>. The control valve <NUM> may control the amount of flow for each emissions control fluid (e.g., ammonia and emissions reducing agent) through a common fluid conduit to the gas turbine system <NUM>, which may be controlled by the controller <NUM>. The emissions control fluids are injected into the gas turbine system <NUM> at various portions of the fluid pathways <NUM>, such as at the compressor bleed conduits <NUM>, the distribution conduits <NUM>, the coolant conduits <NUM> coupled to the turbine <NUM>, and/or the coolant conduits <NUM> coupled to the exhaust duct <NUM>.

The controller <NUM> may monitor the exhaust gas <NUM> and various operating parameters of the gas turbine system <NUM> to determine the amount of flow of the emissions control fluids suitable to reduce the level of exhaust emissions and the visibility of the exhaust emissions (e.g., yellow plume levels). The controller <NUM> may route at least part of the emissions control fluids to the one or more fluid pathways <NUM> (e.g., cooling circuit <NUM>) and also may route at least part of the emissions control fluids to the exhaust gas <NUM> in the exhaust duct <NUM> (e.g., via injection grids <NUM> and <NUM>). In the illustrated embodiment, the injection grid <NUM> is disposed in the exhaust duct <NUM> upstream of the duct burner assembly <NUM> while the injection grid <NUM> is disposed in the exhaust duct <NUM> downstream from the duct burner assembly <NUM>.

<FIG> is a diagram illustrating an embodiment of the reducing solution system <NUM> of the emissions control system <NUM> interacting with the gas turbine system <NUM>. The embodiment of <FIG> is substantially the same as the embodiment of <FIG>, except that a separate control valve <NUM> is used for each of the tanks <NUM> and <NUM>, an injection grid <NUM> is disposed in the exhaust duct <NUM> downstream from the injection grids <NUM> and <NUM>, and a heat exchanger <NUM> (e.g., <NUM>, <FIG>) is disposed between the injection grids <NUM> and <NUM>. The controller <NUM> is communicatively coupled to the control valves <NUM>, such that the controller <NUM> can independently control the flows of ammonia and emissions reducing agent from the tanks <NUM> and <NUM>, respectively.

The reducing solution train <NUM> may be connected to a first one of the control valves <NUM>, which is connected to a first fluid circuit <NUM> (e.g., coolant circuit) extending from one of the compressor bleed conduits <NUM> to a plurality of coolant conduits <NUM> coupled to the turbine <NUM> and a plurality of coolant conduits <NUM> coupled to the exhaust duct <NUM>. In particular, the first fluid circuit <NUM> extends to the coolant conduits <NUM> coupled to the injection grids <NUM> and <NUM>. The ammonia solution train <NUM> may be connected to a second one of the control valves <NUM>, which is connected to a second fluid circuit <NUM> extending from one of the compressor bleed conduits <NUM> to one of the coolant conduits <NUM> coupled to the exhaust duct <NUM>. In particular, the second fluid circuit <NUM> extends to the coolant conduit <NUM> coupled to the injection grid <NUM> (e.g., an ammonia injection grid). The controller <NUM> may determine the amount of reducing agent and/or ammonia suitable to lower a level of exhaust emissions and a visibility of the exhaust emissions (e.g., yellow plume) and may operate the control valves <NUM> to route the reducing agent to the first fluid circuit <NUM> and the ammonia to the second fluid circuit <NUM>. While the example shows specific flow paths for the reducing solution system <NUM>, the control valves <NUM> may divert flow for each solution train <NUM> and <NUM> in any number of ways.

<FIG> is a flow chart of an embodiment of a process <NUM> for reducing exhaust emissions and a visibility of the exhaust emissions in a gas turbine system <NUM>. The process <NUM> may include the instructions <NUM> stored on the memory <NUM> and executable by the processor <NUM> of the controller <NUM> as discussed above. In step <NUM>, the process <NUM> measures one or more parameters of the gas turbine system <NUM>. For example, the process <NUM> may measure (e.g., using sensors) the parameters in the exhaust duct <NUM>, in the combustor <NUM>, in the turbine <NUM>, or any other suitable location. The process <NUM> may measure the parameters during start up, during steady state operation, or during shutdown of the gas turbine system <NUM>. The measured parameters may include NOx levels, SOx levels, CO levels, temperature of the exhaust, temperature of a catalyst of the SCR system <NUM>, visibility levels (e.g., degree of opacity and/or color), and any other parameter associated with the exhaust emissions.

In step <NUM>, the process <NUM> evaluates whether a temperature of the SCR system <NUM> (e.g., TSCR) is greater than <NUM>°F. The TSCR may be the temperature of the exhaust gas <NUM> at the SCR system <NUM>, a temperature of a catalyst of the SCR system <NUM>, or a combination thereof. The controller <NUM> may continually monitor the temperature of the SCR system <NUM> to determine the next steps. If the temperature at the SCR system <NUM> is greater than <NUM>° F, the process <NUM> moves to step <NUM>. If the temperature at the SCR system <NUM> is less than <NUM>° F, the process <NUM> moves to step <NUM>.

In step <NUM>, the process <NUM> controls a reducing solution system to begin or adjust an ammonia injection into the SCR system <NUM> via coolant conduits <NUM> and/or into one or more fluid pathways <NUM> (e.g., coolant conduits <NUM>, <NUM>, and/or <NUM>) of the gas turbine engine <NUM>. The ammonia may be injected into the SCR system <NUM> to allow for the SCR system <NUM> to reduce NOx and other emissions using a catalyst in the SCR system for conversion. The efficiency of the conversion is proportional to the temperature of the SCR system <NUM>. Thus, with the SCR system <NUM> operating above <NUM>° F, the controller <NUM> selectively routes ammonia to the SCR system <NUM>. The controller <NUM> may operate a control valve <NUM> connected to the reducing solution system to control the flow of ammonia into the SCR system <NUM>.

In step <NUM>, the process <NUM> begins or adjusts an ethanol injection via a reducing solution system. The process <NUM> may control the ethanol injection into one or more fluid pathways <NUM> (e.g., coolant conduits <NUM>, <NUM>, <NUM>, and/or <NUM>), such as the cooling circuit <NUM>. The process <NUM> may selectively supply the ethanol to all or select injection points in the bearings <NUM>, the combustor <NUM>, the turbine <NUM>, the exhaust duct <NUM>, or a combination thereof, thereby helping to reduce emission levels (e.g., NOx levels) and visibility of the emissions (e.g., yellow plume). The controller <NUM> may operate a control valve <NUM> connected to the reducing solution system <NUM> to control the flow of ethanol into the gas turbine system <NUM>. As noted above, reducing agents other than ethanol may be used.

Although the process <NUM> illustrates steps <NUM> and <NUM> as alternatives following step <NUM>, embodiments of the process <NUM> may simultaneously use the emissions control measures of both steps <NUM> and <NUM> and make adjustments to both ammonia injection and ethanol injection to reduce emissions levels and visibility of the emissions. In step <NUM>, the process <NUM> evaluates whether the NOx levels are reduced below a target level (e.g., threshold). The controller <NUM> actively monitors NOx levels at the turbine exhaust, the flow of reducing agents (e.g., ammonia and ethanol), and operations at each part of the gas turbine system (e.g., injection points, compressor, turbine, injection grids, cooling circuit). If the NOx levels are determined to be below a pre-determined target level, the process <NUM> continues maintaining operation at the operating point as indicated by step <NUM>. However, if NOx levels still exceed the pre-determined target level, the process <NUM> may repeat the process or move to optional step <NUM>.

In optional step <NUM>, the controller <NUM> operates a blower <NUM> to provide bypass air to the gas turbine system <NUM>. In optional step <NUM>, another determination is made by the controller <NUM> to determine if NOx levels are reduced below a target level due to the bypass air. If the controller <NUM> determines NOx levels are reduced below a target level, the process <NUM> continues to maintain operating at the operating point as indicated by step <NUM>. If the controller <NUM> determines that NOx levels are not below a target level, the controller <NUM> may begin the process again.

Technical effects of the disclosed embodiments enable a reduction in exhaust emissions levels and associated visibility of the exhaust emissions by injecting an emissions control fluid (e.g., reducing agent) into one or more fluid pathways <NUM> of the gas turbine engine <NUM>. The fluid pathways <NUM> may including cooling pathways through the bearings <NUM>, the combustor <NUM>, and/or the turbine <NUM> (e.g., one or more cooling circuits). The fluid pathways <NUM> also may extend to the exhaust duct <NUM>. However, the injection of emissions control fluids into the fluid pathways upstream from the exhaust outlet <NUM> of the turbine <NUM> may help improve the mixing and residence time of the emissions control fluids with the exhaust gas, thereby helping to reducing the exhaust emissions and the visibility of the exhaust emissions before being discharged into the atmosphere.

Claim 1:
A system (<NUM>), comprising:
an emissions control system (<NUM>) configured to couple to a turbine engine (<NUM>), wherein the emissions control system (<NUM>) comprises:
an emission control fluid supply (<NUM>) having one or more conduits (<NUM>) configured to couple to one or more fluid pathways (<NUM>) of the system (<NUM>), wherein the one or more fluid pathways (<NUM>) are fluidly coupled to a flow path of an exhaust gas from a combustor (<NUM>) through a turbine (<NUM>) of the turbine engine (<NUM>);
at least one sensor (<NUM>) configured to obtain a feedback of one or more parameters of the turbine engine (<NUM>), wherein the one or more parameters are indicative of a visibility of emissions of the exhaust gas;
at least one valve (<NUM>) coupled to the emissions control fluid supply (<NUM>); and
a controller (<NUM>) communicatively coupled to the at least one sensor (<NUM>) and the at least one valve (<NUM>), wherein the controller (<NUM>) is responsive to the feedback to adjust the at least one valve (<NUM>) to adjust a flow of the emission control fluid to reduce the visibility of the emissions of the exhaust gas, the emission control fluid comprising a reducing agent; characterized in that
the at least one sensor comprises a visibility sensor, wherein the visibility sensor includes an opacity sensor, a color sensor, or a combination thereof.