A control system for a gas turbine includes a controller. The controller includes a processor configured to receive a plurality of signals comprising a temperature signal, a pressure signal, a speed signal, a mass flow signal, or a combination thereof, from sensors disposed in the gas turbine system. The processor is further configured to apply the plurality of signals as input to a heating value model. The processor is also configured to execute the heating value model to derive a heating value for a fuel combusted by the gas turbine system. The processor is additionally configured to control operations of the gas turbine system based on the heating value for the fuel.

A gas turbine engine includes: a combustor that combust the fuel and having an exit, a combustor exit temperature (T40) is the average temperature of flow and a combustor exit pressure (P40) is the total pressure there; a turbine including a rotor having a leading edge and a trailing edge, and wherein a turbine rotor entry temperature (T41) is an average temperature of flow at the leading edge and a turbine rotor entry pressure (P41) is the total pressure there; and a compressor having an exit, wherein a compressor exit temperature (T30) is the average temperature of flow at the exit from the compressor and a compressor exit pressure (P30) is the total pressure there (all at cruise conditions). A method of determining at least one fuel characteristic includes changing a fuel supplied to the engine; and determining a change in a relationship between T30 or P30, T40 and T41, or of P40 and P41, respectively.

A method of operating an aircraft that includes a propulsion system. The propulsion system includes a gas turbine engine and a fuel tank arranged to provide fuel to the gas turbine engine. The method includes: determining at least one fuel characteristic of the fuel arranged to be provided to the gas turbine engine; and controlling the propulsion system based on the at least one fuel characteristic.

The present application discloses a method of determining one or more fuel characteristics of an aviation fuel used for powering a gas turbine engine of an aircraft. The method comprises: determining one or more performance parameters of the gas turbine engine during a first time period of operation of the gas turbine engine; and determining one or more fuel characteristics of the fuel based on the one or more performance parameters. A method of operating an aircraft, a fuel characteristic determination system, and an aircraft are also disclosed.

A vent for use in a gaseous fuel supply circuit of a gas turbine is provided. The vent includes an inlet in flow communication with the gaseous fuel supply circuit, a first outlet in flow communication with the gaseous fuel supply circuit and configured to release gaseous fuel at atmospheric pressure, a first valve coupled between the inlet and the first outlet, wherein the first valve includes a second outlet configured to channel the gaseous fuel towards a combustion device. The system also includes a second valve coupled between the inlet and the second outlet, and a control device configured to selectively open and close the first and second valves based on a pressure of the gaseous fuel.

A carbon fiber production method includes a carbon fiber production step including an oxidation step and a carbonization step; and an exhaust gas processing step including a heat exchange step; an external air mixing step; and a mixed external air supplying step in which the mixed external air is supplied to at least one step that uses heated gas in the steps in the carbon fiber production step; and among the exhaust gases, a high heating value exhaust gas having a heating value of 250 kcal/Nm.sup.3 or higher is supplied to an inlet side of an exhaust gas combustion apparatus and a low heating value exhaust gas having a heating value lower than 150 kcal/Nm.sup.3 is supplied to an outlet side of the exhaust gas combustion apparatus, respectively.

A method for determining an estimate of the specific gravity of a fuel for a gas turbine engine is disclosed. The gas turbine engine includes a fuel control valve and one or more fuel injectors. The method includes determining a first estimate of the specific gravity based on an orifice flow model of the fuel control valve. The method also includes determining a second estimate of the specific gravity based on a combined orifice flow model of the one or more fuel injectors. The method further includes recursively filtering the first estimate and the second estimate to determine a third estimate of the specific gravity.

A method and apparatus for controlling a process in a system comprising pre-processing of a raw material, processing the pre-processed raw material and acquisition of the result of the processing of the pre-processed raw material, comprising the steps of: capturing input and output variables of the pre-processing; capturing output variables of the processing of the pre-processed raw material; creating a first, second and third process model for at least two different time scales, which describes the effects of adapting the pre-processing of raw material, the effects of adapting the processing of the pre-processed raw material, the effects of adapting the pre-processing of raw material and adapting the processing of pre-processed raw material on the output variables of the processing of pre-processed raw material; wherein the process in the system is controlled using the prediction of the process model which currently provides the best predictions for the process in the system.

A regulation device for regulating a mixing ratio (x) of a gas mixture comprises a first conduit (1) for carrying a flow of a first gas (e.g., air) and a second conduit (2) for carrying a flow of a second gas (e.g., a fuel gas). The first and second conduits (1, 2) open out into a common conduit (3) in a mixing region (M) to form the gas mixture. A first sensor (S1) is configured to determine at least one thermal parameter of the gas mixture downstream from the mixing region. A control device (10) is configured to receive, from the first sensor, sensor signals indicative of the at least one thermal parameter of the gas mixture and to derive control signals for adjusting device (V1) acting to adjust the mixing ratio, based on the at least one thermal parameter.

Systems and methods for monitoring emissions of a combusted gas are provided. The method includes determining a first net heating value of a flare gas. The method also includes determining a second net heating value of a combustion gas including the flare gas. The second net heating value can be determined based upon the first net heating value and a volumetric flow rate of the flare gas. Based upon the value of the second net heating value, an empirical model or a non-parametric machine learning model can be selected. A combustion efficiency of the combustion gas can be determined using the selected model, the second net heating value, and selected ones of the process conditions and the environmental conditions. Total emissions of the combustion mixture can be further determined from the combustion efficiency and a volumetric flow rate of the combustion gas.