System and method to actively control turndown temperature of a gas turbine engine
The active control strategy for gas turbine engines adjusts turbine temperature using inlet guide vanes and bleed valves to optimize efficiency and reduce emissions, addressing inefficiencies from variable fuel and ambient conditions.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SIEMENS ENERGY GLOBAL GMBH & CO KG
- Filing Date
- 2025-12-08
- Publication Date
- 2026-07-23
AI Technical Summary
Existing gas turbine engine turndown temperature control methods using a fixed temperature compromise efficiency and increase emissions when dealing with variable fuel reactivity and ambient conditions.
An active control strategy adjusts turbine entry or firing temperature using inlet guide vanes and bleed valves based on monitored operational parameters, including fuel reactivity and ambient conditions, to maintain an optimal turndown temperature range.
Improves engine efficiency and reduces undesirable emissions by maintaining the turbine temperature within a desired range, even with varying fuel and ambient conditions.
Smart Images
Figure EP2025085896_23072026_PF_FP_ABST
Abstract
Description
SYSTEM AND METHOD TO ACTIVELY CONTROL TURNDOWN TEMPERATURE OF A GAS TURBINE ENGINEBACKGROUND
[0001] Disclosed embodiments are generally directed to control techniques in connection with operation of a gas turbine engine, and, more specifically, to method and system to actively control the turndown temperature of a gas turbine engine.
[0002] When gas turbine engines operate at a part-load condition, to inhibit production of emissions, such as CO emissions etc., certain known turndown temperature control approaches are typically implemented to, for example, reduce the amount of air entering a combustion system of the engine. Such known control approaches are premised on utilization of a fixed turndown control temperature; however, operating the engine under a fixed turndown control temperature can compromise the part-load efficiency of the engine under certain operational conditions, such as when relatively more reactive fuel types and / or fluctuation of ambient conditions are involved. This is because, under control approaches relying on the fixed turndown control temperature, the engine can be actually operating at a higher turndown temperature than necessary and in turn this can lead to increased fuel consumption and reduced performance.
[0003] For example, in case a relatively more reactive fuel is used --such as comprising H2 or a higher order form of hydrocarbon fuel such as liquefied petroleum gas (LPG) comprising, for example, propane and butane content— the temperature at which CO emissions start to substantially increase (the so-called CO kick-off point) occurs at a relatively lower temperature compared to a fuel having less reactivity properties. That is, when using the foregoing fixed turndown control temperature approach, if the engine is operated with a fuel or fuel blend involving higher fuel reactivity, then the CO kick-off point would be lowered when such more reactive fuel is utilized. At least in view of the foregoing considerations, there is a need for techniques conducive to further improvements in engine part-load efficiency that considers the foregoing operational conditions.BRIEF SUMMARY
[0004] In one aspect, a method to control operation of a gas turbine engine is provided. The method includes monitoring respective operational parameter values of the gas turbine engine.The respective operational parameter values being monitored comprising load of the gas turbine engine, fuel reactivity of a fuel or fuel blend used by the gas turbine engine, and engine control temperature . The method further includes supplying to a controller of the gas turbine engine the respective operational parameter values of the gas turbine engine being monitored and storing in the controller a look-up table configured to identify a desired turndown temperature control range of the gas turbine engine appropriate for the operational parameter values of the gas turbine engine being monitored. Searching in the look-up table to identify the desired turndown temperature control range based on the respective operational parameter values supplied to the controller, and then determining whether the respective value of the engine control temperature is within the desired turndown temperature control range of the gas turbine engine. Executing by way of the controller an active control strategy involving at least one component of the gas turbine engine to actively adjust, as needed, the value of the engine control temperature to be within the desired turndown temperature control range of the gas turbine engine.
[0005] The engine control temperature is one of the following: turbine entry temperature (TET) and turbine firing temperature (Tfire).
[0006] In one embodiment, the respective operational parameter values being monitored further comprise ambient conditions in connection with the operation of the gas turbine engine, where the ambient conditions comprise ambient temperature, and ambient pressure.
[0007] The at least one component of the gas turbine engine comprises a plurality of respective inlet guide vanes or a plurality of respective bleed valves.
[0008] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is within the desired turndown temperature control range, then the control strategy is to control an angular position of the respective inlet guide vanes or to control an amount of bleed by way of the respective bleed valves to remain within the desired turndown temperature control range.
[0009] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is below a lower range point of the desired turndown temperature control range, then the control strategy is to set the respective angular position of the plurality of inlet guide vanes to a predefined minimal angular position or to set the respective bleed valves to a fully open position.
[0010] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is above an upper range point of the desired turndown temperature control range, then the control strategy comprises no adjustment of the respective angular position of the plurality of respective inlet guide vanes or no adjustment of the respective amount of bleed provided by the respective plurality of bleed valves in response to the respective operational parameter values supplied to the controller.
[0011] In another aspect, a system to control operation of a gas turbine engine is provided. The system includes a monitor subsystem configured to monitor respective operational parameter values of the gas turbine engine. The respective operational parameter values being monitored comprising load of the gas turbine engine, fuel reactivity of fuel used by the gas turbine engine, and engine control temperature. A controller of the gas turbine engine is connected to receive the respective operational parameter values of the gas turbine engine. A look-up table stored in the controller to identify a desired turndown temperature control range of the gas turbine engine appropriate for the operational parameter values of the gas turbine engine being monitored, where the look-up table is searched based on the respective operational parameter values supplied to the controller to identify the desired turndown temperature control range. The controller is configured to determine whether the value of the engine control temperature is within the desired turndown temperature control range of the gas turbine engine, and the controller is further configured to execute an active control strategy involving at least one component of the gas turbine engine to actively adjust, as needed, the value and engine control temperature to be within the desired turndown temperature control range of the gas turbine engine.
[0012] In one embodiment, the respective operational parameter values being monitored further comprise ambient conditions in connection with operation of the gas turbine engine, where the ambient conditions comprise ambient temperature, and ambient pressure.
[0013] The at least one component of the gas turbine engine comprises a plurality of respective inlet guide vanes or a plurality of respective bleed valves.
[0014] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is within the desired turndown temperature control range, then the control strategy is to control an angular position of the respective inlet guide vanes or to control an amount of bleed by way of the respective bleed valves to remain within the desired turndown temperature control range.
[0015] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is below a lower range point of the desired turndown temperature control range, then the control strategy is to set the respective angular position of the plurality of inlet guide vanes to a predefined minimal angular position or to set the respective bleed valves to a fully open position.
[0016] When the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is above an upper range point of the desired turndown temperature control range, then the control strategy comprises no adjustment of the respective angular position of the plurality of respective inlet guide vanes or no adjustment of the respective amount of bleed provided by the respective plurality of bleed valves in response to the respective operational parameter values supplied to the controller.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 shows part of a turbine engine in a sectional view and in which disclosed embodiments are incorporated in accordance with the present disclosure.
[0018] FIG. 2 shows respective plots indicative of CO emissions as a function of engine control temperature (e.g., turbine entry temperature (TET) or turbine firing temperature (Tfire)) in connection with example fuels having different reactivity properties. The respective plots show respective CO kickoff points marked on respective CO turndown temperature curves for the example fuels.
[0019] FIG. 3 shows respective plots indicative of engine control temperature (e.g., turbine entry temperature (TET) and turbine firing temperature (Tfire)) as a function of engine load in connection with the example fuels shown in FIG. 2. The plots show respective example turndown control temperature ranges (including respective start and end points) for the example fuels.DETAILED DESCRIPTION
[0020] The present inventors have recognized that gas turbine engines are known to use certain techniques involving a fixed turndown control temperature at part-load to try inhibiting generation of emissions to acceptable levels. The present inventors have further recognized that such techniques do not consider variability of fuel reactivity in the fuel used by the engineand / or fluctuation of ambient conditions in connection with operation of the engine. Accordingly, when a relatively more reactive fuel is used and / or when the gas turbine is subject to varying ambient conditions, the engine can lose substantial efficiency while increasing undesirable emissions.
[0021] In view of such recognition, disclosed embodiments propose an innovative and cost-effective active control methodology in connection with the turndown temperature. As elaborated in greater detail below, this active control is conducive to improving engine efficiency while inhibiting undesirable emissions regardless of variability of fuel reactivity and / or ambient conditions. For example, with the proposed active control, a gas turbine engine can efficiently operate at part-load at an actively adjusted turndown control temperature and, for example, have significantly reduced CO emissions.
[0022] As will be appreciated by one skilled in the art, natural turndown temperature in the context of a gas turbine engine involves a process where a parameter, such as engine control temperature, which is indicative of gaseous flow temperature —as the gaseous flow enters or is in close proximity to the first stage of the turbine— decreases naturally in value with decreasing engine load without involving compressor modulation or bleeding of compressor air to the exhaust. Practically analogous variants of such a parameter are turbine entry temperature (TET), or Turbine firing temperature (Tfire). TET refers to the temperature of the gaseous flow directly after the combustion chamber just upstream of the first-stage turbine nozzles while Tfire refers to the temperature of the gaseous flow at the trailing edge of the first-stage turbine nozzles. That is, as would be appreciated by one skilled in the art, the engine control temperature (e.g., TET or Tfire) is each indicative of combustor outlet temperatures. As the temperature value of the foregoing parameter, (TET or Tfire) reaches or is below a certain critical low point, some emissions, such as CO emissions, can rise substantially. The load point at which this phenomenon occurs is known as the turndown point, and the corresponding TET or Tfire temperature represents the turndown control temperature.
[0023] FIG. 1 is a schematic illustration of a simplified example arrangement of a turbine engine 10 having an inlet 12, a compressor 14, a combustion system 16, a turbine 18, an exhaust duct 20 and a shaft arrangement, such as a twin shaft arrangement 22, 24. It will be appreciated that the turbine engine 10 shown and described with reference to FIG. 1 is just one example of turbomachinery in which disclosed embodiments can be incorporated. Turbineengine 10 can be a gas turbine and include single, double or triple shaft arrangements and can be used in various application, such as marine, industrial or aerospace applications.
[0024] Turbine engine 10 is generally arranged about an axis 26 which for rotating components is their rotational axis. The shafts of the twin-shaft arrangement 22, 24 may have the same or opposite directions of rotation. Combustion system 16 may comprise an annular array of combustors 36, only one of which is shown for the sake of avoiding visual cluttering. In one example, there are six combustors 36 evenly spaced about the engine 10. Each combustor 36 extends along a respective longitudinal combustor axis 44 and defines a respective combustion chamber 38.
[0025] The terms radial, circumferential and axial are with respect to the engine's rotational axis 26 or as otherwise stated. The terms upstream and downstream are with respect to the general direction of gas flow through the engine and, as seen in FIG. 1, is generally from left to right.
[0026] Compressor 14 comprises an axial series of stator vanes and rotor blades mounted in a conventional manner. In operation, ambient air 32 is drawn into engine 10 through inlet 12 and into compressor 14, where successive compression stages of vanes and blades compress the air before delivering compressed air 34 into combustion system 16.
[0027] The compressor vanes comprise inlet guide vanes 102 configured with variable angular positioning to regulate the mass flow of air onto the downstream rotor and compressor blades. In one example embodiment, turbine engine 10 further includes bleed valves 104 as a further modality for regulating airflow by releasing excess compressed air from the engine.
[0028] In one example embodiment, a monitoring system is configured to monitor respective operational parameter values of the gas turbine engine. The respective operational parameter values comprise load of the gas turbine engine, fuel reactivity of fuel used by the gas turbine engine as may be monitored by a fuel reactivity sensor device 103, engine control temperature, (e.g., turbine entry temperature (TET) or turbine firing temperature (Tfire)) as may be monitored by a temperature sensor device 105 or otherwise monitored by way of an estimator, for example. In one example embodiment, the respective operational parameter values may further comprise ambient conditions in connection with operation of the gas turbine engine. The ambient conditions may include ambient temperature, ambient pressure, ambient humidity.
[0029] In one example embodiment, the respective operational parameters are supplied to a controller 120 that includes at least one look-up table 122 configured to identify a desiredturndown temperature control range of the gas turbine engine appropriate for the operational parameter values of the gas turbine engine. In operation, look-up table 122 is searched to identify the desired turndown temperature control range based on the respective operational parameter values supplied to the controller.
[0030] In one example embodiment, controller 120 is configured to determine whether the respective value of the engine control temperature (e.g., the turbine entry temperature (TET) or the turbine firing temperature (Tfire)) is within the desired turndown temperature control range of the gas turbine engine. Controller 120 is further configured to execute an active control strategy involving at least one component of the gas turbine engine to actively adjust, as needed, the value of the engine control temperature (e.g., the turbine entry temperature (TET) or the turbine firing temperature (Tfire)) to be within the desired turndown temperature control range of the gas turbine engine. In one example embodiment, the at least one component of the gas turbine engine comprises inlet guide vanes 102 or bleed valves 104.
[0031] In one example embodiment, the active control strategy may be as follows: 1) when the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is within the desired turndown temperature control range, then the control strategy is to control the mass of air flow by way of the angular position of the respective inlet guide vanes or to control an amount of bleed of the respective bleed valves so that TET or Tfire remains within the desired turndown temperature control range; 2) when the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire) is below a lower range point of the desired turndown temperature control range, then the control strategy is to set respective angular positions of the plurality of inlet guide vanes to a predefined minimal angular position (e.g., minimal air flow) or to set the respective bleed valves to a fully open position (e.g., maximal bleed); and 3) when the value of the turbine entry temperature (TET) or the turbine firing temperature (Tfire)) is above an upper range point of the desired turndown temperature control range, then the control strategy comprises no adjustment of the respective angular positions of the plurality of respective inlet guide vanes or no adjustment of the respective amount of bleed provided by the respective plurality of bleed valves in response to the monitored parameters.
[0032] FIG. 2 shows respective plots indicative of CO emissions as a function of engine control temperature (e.g., turbine entry temperature (TET) or turbine firing temperature (Tfire)) in connection with example fuels having different reactivity properties. The respective plotsshow respective CO kickoff points marked on respective CO turndown temperature curves for the example fuels. The idea is to actively keep the engine control temperature sufficiently high so that the CO kickoff points and concomitant high-level of CO emissions are not triggered.
[0033] FIG. 3 shows respective plots indicative of engine control temperature (e.g., turbine entry temperature (TET) and turbine firing temperature (Tfire)) as a function of engine load in connection with the example fuels having different reactivity properties. Th plots show respective turndown temperature control ranges (including respective start and end points in connection with the actively controlled turndown temperature) for the example fuels. The idea is to during part-load operation actively keep the engine control temperature within the respective turndown temperature control ranges so as to inhibit the effects of varying fuel reactivity and / or varying ambient conditions on the natural turndown temperature behavior, indicated by straight line 302.
[0034] In operation, the disclosed active control is conducive to improving engine efficiency while inhibiting undesirable emissions regardless of variability of fuel reactivity and / or ambient conditions. For example, with the proposed active control, a gas turbine engine can efficiently operate at part-load at a desirable turndown control temperature and, for example, have significantly reduced CO emissions.
[0035] In operation, disclosed embodiments are conducive to substantial operational flexibility in connection with utilization of fuels or fuel blends involving variable fuel reactivity, such as comprising H2 or a higher order form of hydrocarbon fuel, such as liquefied petroleum gas (LPG) comprising propane and butane content.
Claims
AMENDED CLAIMSreceived by the International Bureau on 14 April 2026 (14.04.2026)Claims1. A method of controlling part-load operation of a gas turbine engine, comprising:monitoring an engine control temperature of the gas turbine engine, wherein the engine control temperature is a turbine entry temperature (TET) or a turbine firing temperature (Tfire);monitoring a fuel reactivity of a fuel or fuel blend supplied to the gas turbine engine;determining, based on the monitored fuel reactivity, a CO-emission kickoff point expressed as an engine control temperature at which CO emissions begin to increase with decreasing engine control temperature for the monitored fuel reactivity;defining, based on the CO-emission kickoff point, an active turndown temperature control range bounded by (i) an active turndown control start temperature, and (ii) an active turndown control end temperature that is lower than the active turndown control start temperature;comparing the monitored engine control temperature to the active turndown temperature control range; andduring part-load operation of the gas turbine engine, actively controlling operation of the gas turbine engine to maintain the engine control temperature within the active turndown temperature control range, thereby inhibiting an increase in CO emissions associated with decreasing engine control temperature for the monitored fuel reactivity.
2. The method of claim 1, wherein the fuel reactivity is monitored using a fuel reactivity sensor device.
3. The method of claim 1, wherein the active turndown control start temperature is at or above the CO-emission kickoff point for the monitored fuel reactivity.
4. The method of claim 1, wherein actively controlling operation of the gas turbine engine comprises controlling airflow into a combustor system of the gas turbine engine.
5. The method of claim 4, wherein controlling airflow into the combustor system comprises adjusting an angular position of one or more inlet guide vanes.
6. The method of claim 4, wherein controlling airflow into the combustor system comprises controlling an amount of compressor air bled from the gas turbine engine.AMENDED SHEET (ARTICLE 19)