# Patent

## Title
Gas turbine fuel flow measurement using inert gas

## Abstract

The fuel flow rate to a gas turbine is measured using an inert gas. The inert gas is injected into the fuel flow and the concentration of the inert gas in the fuel/inert gas mixture is later measured. The concentration of the inert gas in the fuel/inert gas mixture is then used to calculate the mass flow rate of the fuel.

## Background
CROSS-REFERENCE TO APPLICATION
The application is a continuation-in-part of U.S. patent application Ser. No. 13/415,382, filed Mar. 8, 2012, pending, which is incorporated herein by reference in its entirety.


FIELD OF THE INVENTION
The present technology relates generally to gas turbines and more particularly to systems and methods for optimizing gas turbines by, for example, accurately measuring fuel mass flow rate.
BACKGROUND OF THE INVENTION
Gas turbine engines typically include a compressor for compressing incoming air, a combustor for mixing fuel with the compressed air and igniting the fuel/air mixture to produce a high temperature gas stream, and a turbine section that is driven by the high temperature gas stream. The amount of fuel required to generate an observed power level defines the efficiency of the system. However, in many known gas turbine systems, the accuracy of the fuel flow measurement is not adequate for detailed performance assessments.
BRIEF SUMMARY OF THE INVENTION
One exemplary but nonlimiting aspect of the disclosed technology relates to a system. The system comprises a transport medium to convey a gas flow, an injection device to inject an inert gas into the gas flow to form a gas mixture, and a concentration measuring device downstream of the injection device to measure a concentration of the inert gas in the gas mixture, wherein a flow rate of the gas flow is calculated based on the measured concentration of the inert gas in the gas mixture.
In another exemplary but nonlimiting embodiment, there is provided a method of measuring the flow rate of a gas. The method comprises injecting an inert gas into a gas flow at an injection location, mixing the inert gas with the gas flow to form a gas mixture, measuring a concentration of the inert gas in the gas mixture downstream of the injection location, and calculating a flow rate of the gas flow based on the measured concentration of the inert gas in the gas mixture.
In another exemplary but nonlimiting embodiment, there is provided a gas turbine. The gas turbine comprises a fuel line to convey a flow of fuel to a combustor section of the gas turbine, an injection device to inject an inert gas into the fuel flow to form a gas mixture, and a concentration measuring device downstream of the injection device to measure a concentration of the inert gas in the gas mixture, wherein a flow rate of the fuel flow is calculated based on the measured concentration of the inert gas in the gas mixture.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings facilitate an understanding of the various examples of this technology. In such drawings:
FIG. 1 is a schematic representation of an example gas flow rate measuring system;
FIG. 2 is a flow chart diagram of computer program code structure for an example gas flow rate measuring method;
FIG. 3 is an example block diagram representing a general purpose computer system in which aspects of the example gas flow rate measuring system and gas flow rate measuring method may be incorporated.



DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Referring to FIG. 1, an example gas flow rate measuring system is shown. Particularly, a fuel flow rate measuring system 100 for use with a gas turbine is shown in the illustrated example of FIG. 1. The mass flow rate of the fuel is calculated based on the measured concentration of a test gas injected into the fuel flow.
Accurately understanding the amount of fuel being burned by a gas turbine is critical when assessing the performance of the gas turbine system. The amount of fuel required to generate an observed power level defines the efficiency of the system. Thus, accurately measuring the fuel flow rate is essential for detailed performance assessments. For instance, an accurate fuel flow measurement enables accurate assessments of gas turbine efficiency. The disclosed technique improves on the accuracy of current systems for measuring mass flow rate. An improved heat balance resulting from a more accurate representation of the fuel flow allows for more accurate assignment of component performance during testing. Further, when the fuel flow rate is accurately represented, sophisticated control algorithms may be developed that use the measured fuel flow as an input. Real-time plant optimization related to system efficiency may also be implemented.
As shown in FIG. 1, the fuel flow rate measuring system 100 includes a transport medium (e.g., fuel line 102) for transporting a fuel flow 104 to a gas turbine (not shown). The fuel flow 104 may be methane gas or any other suitable gas fuel. A test gas 110 is injected into the fuel flow 104 with an injection device 108 (e.g., a nozzle). The injection device 108 may be configured to dispense a desired known quantity of the test gas into the fuel flow 104 thereby forming a fuel/test gas mixture 114. The injection device 108 is in fluid communication with a supply 106 of the test gas 110. A flow meter 112 may measure the amount of the test 110 gas injected into the fuel flow 104.
The amount of test gas 110 injected into the fuel flow 104 may be communicated to a controller 130. The controller 130 may include at least one programmable processor. Further, the controller 130 may control the injection device 108 (e.g., by a valve) so as to control the amount of test gas 110 injected into the fuel flow 104.
The composition of the fuel/test gas mixture 114 is measured at a location downstream of the injection device. The gas composition may be measured by a gas analyzer 120 or any other suitable device as those skilled in the art will recognize. The test gas 110 is adequately mixed into the fuel flow before the composition measurement is taken. The concentration of the test gas 110 in the fuel/test gas mixture 114 is identified and recorded. The composition data may be communicated to the controller 130.
The mass flow rate of the fuel flow 104 may be calculated based on the measured concentration of the test gas 110 in the fuel/test gas mixture 114. Since the composition and amount of the test gas 110 are known, the measured concentration of the test gas in the fuel/test gas mixture 114 can be used to calculate the volume of fuel passing through a given point in the fuel line 102 (i.e., mass flow rate) as one skilled in the art will understand.
Control of a device (e.g., a gas turbine system or component thereof) may be based on the fuel flow rate measurement. In an example, the controller 130 may control such a device through communication line 132.
The test gas 110 is preferably a gas that is not already present in the fuel flow 104 so that an accurate concentration of the injected test gas can be measured. Additionally, the test gas 110 may be a gas that does not impede the combustion process such as an inert gas (e.g., neon). In an example, the gas may be a gas mixture (e.g., comprised of multiple gases) of known constituents.
Referring to FIG. 2, an example method may be performed with assistance of the controller 130. The method may include injecting a known quantity of the test gas (the composition of which is also known) into the fuel flow, as indicated in step 202. In step 204, the test gas is mixed into the fuel flow. Next, in step 206, the concentration of the test gas in the fuel flow is measured. In step 208, the fuel flow rate is calculated. Then, the controller 130 may control a device (e.g., a gas turbine or component thereof) based on the calculated fuel flow rate.
FIG. 3 and the following discussion are intended to provide a brief general description of a suitable computing environment in which the disclosed technology and/or portions thereof may be implemented. The gas concentration and subsequent gas turbine control may both be handled through a gas turbine control system. It is possible that a separate computing system may be used in parallel or series with the gas turbine controller to handle the test gas concentration calculation and information distribution.
The disclosed technology may be described in the general context of computer-executable instructions, such as computer program code structures or program modules, being executed by a computer, such as a client workstation, server, or personal computer. Generally, program modules include routines, programs, objects, components, data structures and the like that perform particular tasks or implement particular abstract data types. Moreover, it should be appreciated that the disclosed technology and/or portions thereof may be practiced with other computer system configurations, including hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers and the like. The disclosed technology may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
FIG. 3 is a block diagram representing a general purpose computer system in which aspects of the disclosed technology and/or portions thereof may be incorporated. As shown, the exemplary general purpose computing system includes a computer 320 or the like, including a processing unit 321, a system memory 322, and a system bus 323 that couples various system components including the system memory to the processing unit 321. The system bus 323 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory includes read-only memory (ROM) 324 and random access memory (RAM) 325. A basic input/output system 326 (BIOS), containing the basic routines that help to transfer information between elements within the computer 320, such as during start-up, is stored in ROM 324.
The computer 320 may further include a hard disk drive 327 for reading from and writing to a hard disk (not shown), a magnetic disk drive 328 for reading from or writing to a removable magnetic disk 329, and an optical disk drive 330 for reading from or writing to a removable optical disk 331 such as a CD-ROM or other optical media. The hard disk drive 327, magnetic disk drive 328, and optical disk drive 330 are connected to the system bus 323 by a hard disk drive interface 332, a magnetic disk drive interface 333, and an optical drive interface 334, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer readable instructions, data structures, program modules and other data for the computer 320.
Although the exemplary environment described herein employs a hard disk, a removable magnetic disk 329, and a removable optical disk 331, it should be appreciated that other types of computer readable media which can store data that is accessible by a computer may also be used in the exemplary operating environment. Such other types of media include, but are not limited to, a magnetic cassette, a flash memory card, a digital video or versatile disk, a Bernoulli cartridge, a random access memory (RAM), a read-only memory (ROM), and the like.
A number of program modules may be stored on the hard disk, magnetic disk 329, optical disk 331, ROM 324 or RAM 325, including an operating system 335, one or more application programs 336, other program modules 337 and program data 338. A user may enter commands and information into the computer 320 through input devices such as a keyboard 340 and mouse 342. Other input devices (not shown) may include a microphone, joystick, game pad, satellite disk, scanner, or the like. These and other input devices are often connected to the processing unit 321 through a serial port interface 346 that is coupled to the system bus, but may be connected by other interfaces, such as a parallel port, game port, or universal serial bus (USB). A monitor 347 or other type of display device is also connected to the system bus 323 via an interface, such as a video adapter 348. In addition to the monitor 347, a computer may include other peripheral output devices (not shown), such as speakers and printers. The exemplary system of FIG. 3 also includes a host adapter 355, a Small Computer System Interface (SCSI) bus 356, and an external storage device 362 connected to the SCSI bus 356.
The computer 320 may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer 349. The remote computer 349 may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and may include many or all of the elements described above relative to the computer 320, although only a memory storage device 350 has been illustrated in FIG. 3. The logical connections depicted in FIG. 3 include a local area network (LAN) 351 and a wide area network (WAN) 352. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet.
When used in a LAN networking environment, the computer 320 is connected to the LAN 351 through a network interface or adapter 353. When used in a WAN networking environment, the computer 320 may include a modem 354 or other means for establishing communications over the wide area network 352, such as the Internet. The modem 354, which may be internal or external, is connected to the system bus 323 via the serial port interface 346. In a networked environment, program modules depicted relative to the computer 320, or portions thereof, may be stored in the remote memory storage device. It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used.
Computer 320 may include a variety of computer readable storage media. Computer readable storage media can be any available media that can be accessed by computer 320 and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, computer readable media may comprise computer storage media and communication media. Computer storage media include both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer 320. Combinations of any of the above should also be included within the scope of computer readable media that may be used to store source code for implementing the methods and systems described herein. Any combination of the features or elements disclosed herein may be used in one or more embodiments.
While the invention has been described in connection with what is presently considered to be the most practical and preferred examples, it is to be understood that the invention is not to be limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

## Claims

1. A system, comprising:
a transport medium to convey a fuel flow;
an injection device to inject an inert gas into the fuel flow to form a gas mixture; and
a gas composition measuring device downstream of the injection device to measure a concentration of the inert gas in the gas mixture,
wherein a flow rate of the fuel flow is calculated based on the measured concentration of the inert gas in the gas mixture.

2. The system of claim 1, wherein the transport medium is configured to convey the fuel flow to a gas turbine for combustion, and wherein the gas composition measuring device is arranged to measure the concentration of the inert gas in the gas mixture upstream of the gas turbine.

3. The system of claim 1, wherein the fuel flow powers at least one gas turbine.

4. The system of claim 1, further comprising a controller to control a device based on the calculated flow rate of the fuel flow.

5. The system of claim 1, further comprising a flow meter to measure an amount of the inert gas injected into the fuel flow, wherein the flow rate of the fuel flow is calculated based on the amount of the inert gas injected into the fuel flow and the measured concentration of the inert gas in the gas mixture.

6. The system of claim 1, further comprising a controller to control a device based on the measured concentration of the inert gas.

7. The system of claim 4, wherein the device is a gas turbine.

8. The system of claim 1, wherein the inert gas is neon.

9. A method of measuring the flow rate of a gas, comprising:
injecting an inert gas into a fuel flow at an injection location;
mixing the inert gas with the fuel flow to form a gas mixture;
measuring a concentration of the inert gas in the gas mixture downstream of the injection location; and
calculating a flow rate of the fuel flow based on the measured concentration of the inert gas in the gas mixture.

10. The method of claim 9, further comprising conveying the fuel flow to a gas turbine for combustion,
wherein the concentration of the inert gas in the gas mixture is measured upstream of the gas turbine.

11. The method of claim 9, wherein the fuel flow powers at least one gas turbine.

12. The method of claim 9, further comprising controlling, with a controller, a device based on the calculated flow rate of the fuel flow.

13. The method of claim 9, further comprising measuring an amount of the inert gas injected into the fuel flow, wherein the flow rate of the fuel flow is calculated based on the amount of the inert gas injected into the fuel flow and the measured concentration of the inert gas in the gas mixture.

14. The method of claim 9, wherein the inert gas is neon.

15. A gas turbine system, comprising;
a fuel line to convey a flow of fuel to a combustor section of a gas turbine;
an injection device to inject an inert gas into the fuel flow to form a gas mixture; and
a gas composition measuring device downstream of the injection device to measure a concentration of the inert gas in the gas mixture,
wherein a flow rate of the fuel flow is calculated based on the measured concentration of the inert gas in the gas mixture.

16. The gas turbine system of claim 15, further comprising a controller to control the gas turbine based on the calculated flow rate of the fuel flow.

17. The gas turbine system of claim 15, further comprising a flow meter to measure an amount of the inert gas injected into the fuel flow, wherein the flow rate of the fuel flow is calculated based on the amount of the inert gas injected into the fuel flow and the measured concentration of the inert gas in the gas mixture.

18. The gas turbine system of claim 15, further comprising a controller is control the gas turbine based on the measured concentration of the inert gas.

19. The gas turbine system of claim 15, wherein the inert gas is neon.