A GAS TURBINE THROUGH FUEL MISTUNING

TECHNICAL FIELD

[0001] The present disclosure, generally, relates to gas turbines. The present disclosure, particularly, relates to combustion control of a gas turbine engine and, more particularly, relates to a method for reducing fluctuation in a combustion chamber by changing in the fuel flow.

BACKGROUND ART

[0002] Nowadays, gas turbines are considered as one of the main equipment that are widely used in thermal energy conversion and electric energy production. In order to maintain the market and compete with each other, large turbine manufacturing companies apply various innovations in their products and are always trying to increase the efficiency of their turbines. One of the main ways to increase the thermal efficiency of a gas turbine is to increase the inlet temperature of the turbine, which is done by making appropriate changes in the combustion chamber. By increasing the inlet temperature of the turbine, different classes of turbines have been created. In this way, the higher the inlet temperature of the turbine is, the turbine is categorized in a higher working class.

[0003] Although an increase in the temperature of the gases entering the turbine may increase the overall efficiency of the gas turbine, it may also be associated with some side effects. For example, it may reduce the life of hot parts, may reduce the time of inspection and overhaul of the turbine, may cause damaging environmental consequences and other functional complications caused by the increase in temperature. [0004] Turbine manufacturing companies have taken appropriate measures to deal with the consequences mentioned in their products. For example, in order to prevent the reduction of the life of the parts and reduce the resulting costs, they have used new materials that are resistant to high temperatures. As mentioned, one of the main consequences of increasing the temperature of the gas entering the turbine is the environmental issue and the production of harmful pollutants for humans and nature, the production of nitrogen oxides due to the high temperature of the flame in the combustion chamber.

[0005] Nowadays, regional environmental organizations in different regions of the world have provided laws regarding the limit of permissible amounts of pollutants emitted from gas turbines, so that these laws are becoming stricter day by day. Therefore, the products of the turbine manufacturing companies should be designed in such a way that the pollutants emitted from them do not exceed the permissible limits set in these rules.

[0006] There are three general methods to reduce the amount of NOx produced in the gas turbine, which are: 1- using catalysts at the gas turbine outlet, 2- using water or steam spray in the flame zone with high temperature, and 3- using a combustion chamber with Low NOx (DLN-Dry Low NOx) in the gas turbine. The first method and the second method require a lot of equipment and may take a lot of money and may increase the complexity of the gas turbine cycle. Therefore, major turbine manufacturing companies have been inclined towards the third method, i.e. development of combustion chamber with low pollutant without spraying water or water vapor and using them in gas turbine. In the old conventional combustion chambers, fuel and air were ignited in a rich form (high fuel-to-air ratio) at the beginning of the combustion chamber, and liner cooling air and dilution air were added to reduce the temperature of the gas entering the turbine. Therefore, the temperature of the flame and the inlet to the turbine had a large difference, which led to high NOx production due to the high temperature of the flame in the chamber. Therefore, in order to reduce NOx, the temperature of the flame in the combustion chamber should be reduced and become close to the inlet temperature to the turbine, which was done in DLN combustion chambers.

[0007] In the following, more explanation is given about the geometry of the combustion chamber. In gas turbines, the energy required for the rotation of the machine is provided by fuel combustion in a set called the combustion chamber. The combustion chamber simply contains burners for injecting and oxidizing fuel and paths for conducting fuel, primary air and combustion products. Considering the high volume of fuel used and the very high energy produced in the gas turbine combustion chamber, the design of burners, the fuel injection method and the settings and control of this system are very important. In general, the fuel may enter the burner through the feeding lines, and fuel injection may be done through the holes installed on the burner.

[0008] After injecting the fuel in the air, the fuel may be ignited and its energy may be released. There are different options for the fuel injection method and also the number of burners feeding paths. The geometry of the burner includes a main body, where the fuel guiding paths are created inside this main body. The fuel lines are connected to the supply lines on one side and to the burner lances on the other side. Burner lances are shafts on which fuel injection nozzles are installed. The fuel enters the burner body through the supply lines, and from there, it is transferred to the lance to be injected.

[0009] Fuel injection may be done through the holes located at the end of the lance or through the holes located on the blades located on the lance. These vanes are known as swirlers. In general, at least two paths are needed for one burner. The first path is the pilot path, which is usually placed in the center of the burner and is responsible for various tasks, including flame stabilization. The second path is the main path through which a significant percentage of fuel is injected. In different designs, the number of fuel injection paths has increased up to 5, which leads to the complexity of the equipment design and control.

[0010] As a rule, each fuel injection path has a control system that controls the injected fuel flow rate. It should be mentioned that a fuel injection path can be connected to a different number of lances, so the number of lances does not indicate the number of feeding paths. The optimal number of feeding channels is to consider two lines for the main burners and one line for the pilot burner. This selection of the number of feeding lines, while providing two main feeding channels, provides the possibility of adjustments, by minimizing the number of channels.

SUMMARY OF THE DISCLOSURE

[0011] This summary is intended to provide an overview of the subject matter of the present disclosure, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description below and the drawings.

[0012] According to one or more exemplary embodiments of the present disclosure, a method for controlling instability in a combustion chamber of a gas turbine is disclosed. In an exemplary embodiment, the disclosed method may include a first step of measuring pressure fluctuation in the combustion chamber during a first period of time by using a pulsation sensor. In an exemplary embodiment, the disclosed method may further include a second step of obtaining first amplitudes of pressure fluctuation in the first period of time based on measured pressure fluctuation during the first period of time. [0013] In an exemplary embodiment, the disclosed method may further include a third step of comparing the first amplitudes of pressure fluctuation with predetermined acceptable amplitudes. In an exemplary embodiment, as a fourth step of the disclosed method, responsive to the first amplitudes of pressure fluctuation, being greater than the predetermined acceptable amplitudes, a fuel flow rate of a first main burner may be decreased by a first amount and a fuel flow rate of a second main burner may be increased by the first amount.

[0014] In an exemplary embodiment, the disclosed method may further include a fifth step of waiting for a first amount of time. In an exemplary embodiment, the method may further include a sixth step of measuring pressure fluctuation in the combustion chamber during a second period of time by using the pulsation sensor. In an exemplary embodiment, the method may further include a seventh step of obtaining a second amplitudes of pressure fluctuation in the second period of time based on measured pressure fluctuation during the second period of time.

[0015] In an exemplary embodiment, the method may further include an eighth step of comparing the second amplitudes of pressure fluctuation with the predetermined acceptable range. In an exemplary embodiment, as a ninth step of the method, responsive to the second amplitudes of pressure fluctuation being greater than the predetermined acceptable range, the fuel flow rate of the first main burner may be decreased by a second amount and the fuel flow rate of a second main burner may be increased by the second amount.

[0016] In an exemplary embodiment, the method may further include a tenth step of waiting for a second amount of time. In an exemplary embodiment, the method may further include an eleventh step of measuring pressure fluctuation in the combustion chamber during a third period of time by using the pulsation sensor. In an exemplary embodiment, the method may further include a twelfth step of comparing the third amplitudes of pressure fluctuation with the predetermined acceptable amplitudes.

[0017] In an exemplary embodiment, as a thirteenth step of the method, responsive to the third amplitudes of pressure fluctuation being greater than the predetermined acceptable amplitudes, the fuel flow rate of the first main burner may be decreased by a third amount and the fuel flow rate of the second main burner may be increased by the third amount.

[0018] In an exemplary embodiment, decreasing the fuel flow rate of the first main burner by the first amount may include decreasing the fuel flow rate of the first main burner by 2 % of total fuel injected into the combustion chamber. In an exemplary embodiment, increasing the fuel flow rate of the second main burner by the first amount may include increasing the fuel flow rate of the second main burner by 2 % of total fuel injected into the combustion chamber. [0019] In an exemplary embodiment, decreasing the fuel flow rate of the first main burner by the second amount may include decreasing the fuel flow rate of the first main burner by 2 % of total fuel injected into the combustion chamber. In an exemplary embodiment, increasing the fuel flow rate of the second main burner by the second amount may include increasing the fuel flow rate of the second main burner by 2 % of total fuel injected into the combustion chamber. [0020] In an exemplary embodiment, decreasing the fuel flow rate of the first main burner by the third amount may include decreasing the fuel flow rate of the first main burner by 2 % of total fuel injected into the combustion chamber. In an exemplary embodiment, increasing the fuel flow rate of the second main burner by the third amount may include increasing the fuel flow rate of the second main burner by 2 % of total fuel injected into the combustion chamber. [0021] In an exemplary embodiment, waiting for a first amount of time may include waiting for 10 seconds. In an exemplary embodiment, waiting for a second amount of time may include waiting for 10 seconds. [0022] In an exemplary embodiment, after implementing thirteenth step 213 of method 200, if amplitudes of pressure fluctuation are greater than predetermined acceptable amplitudes and in other words is not within the acceptable range, the gas turbine may be tripped and in order to avoid accidents, it may be prevented from working in the unstable combustion state of the combustion chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. [0025] FIG. 1 illustrates a schematic of a combustion chamber of a gas turbine, consistent with one or more exemplary embodiments of the present disclosure.

[0026] FIG. 2 illustrates a flowchart of a method for controlling instability in a combustion chamber of a gas turbine, consistent with one or more exemplary embodiments of the present disclosure. [0027] FIG. 3 illustrates an exemplary embodiment of a processing unit , consistent with one or more exemplary embodiments of the present disclosure.

[0028] FIG. 4 illustrates the test results in two modes before (the left column at each frequency) and after (the right column at each frequency) changing the fuel flow rate.

DESCRIPTION OF EMBODIMENTS

[0029] In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.

[0030] The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

[0031] As mentioned above, the existing methods for controlling the amplitudes of oscillations and vibrations may be associated with some issues. Reducing the number of fuel feeding channels may lead to the simplification of the burner and, accordingly, the simplicity of the fuel supply and control system. In advanced burners, the minimum number of feeding channels to cover all functional aspects of a burner is three. In fact, a good choice of the number of feeding channels may be three, which is also considered by some companies. In this type of arrangement of channels, the flow rate entered into the pilot burner supply line should have the minimum possible value to reduce the amount of pollutants. At the same time, the remaining fuel flow is equally divided between the two main channels.

[0032] It should be mentioned that issues related to combustion stability require a minimum flow rate on the pilot line. The present method is proposed based on the number of three channels, which may create the least complexity, and this issue may be one of the strengths of this proposed method. In the proposed method for pressure fluctuation control, some sensors may be installed on the combustion chamber. The output information from these sensors (including amplitudes and frequency of oscillations) may be used as input to the control system. The signal generated by the control system may control the fuel flow between the two main feeding channels. It should be mentioned that in typical designs, the flow rate is divided equally between the two main lines.

[0033] Changes in flow rate are in the form of reducing a certain amount of flow rate in one channel and adding the same amount of flow rate to the other channel in such a way that at a certain time, the total amount of input to the main channels remains unchanged. The flow regulation operation between the two mentioned channels has a significant effect in eliminating the range of vibrations. Thus, by changing the pattern of energy release rate, the range of vibrations may decrease significantly. And at the same time, the amount of NOx produced may not increase.

[0034] As mentioned, in the previous researches, in order to control the combustion instability in the combustion chamber, dividing the fuel flow into two pilot and main paths has been used. In the method used in these researches, if the range of pressure fluctuation in the combustion chamber increases (which is monitored by dynamic pressure sensors), the fuel flow rate from the main section/s may be reduced and added to the fuel flow rate of the pilot section. This action may increase the temperature of the flame and may finally increase the production NOx. [0035] For purpose of reference, it should be noted that the fuel flow rate of the pilot section has a great effect on the final flame temperature in such a way that with the increase of the fuel flow rate of the pilot section, the flame temperature may increase significantly and since the high flame temperature has a direct relationship with the amount of NOx produced, this increase in fuel flow rate in the pilot section may increase the amount of NOx produced. It should be noted that, as mentioned, preventing the increase of NOx production in the combustion chamber has always been one of the goals of the designers.

[0036] Although the methods suggested in the previous references may help to control the instability, but since these methods increase production of NOx, their use has always faced challenges and doubts. Therefore, a method that can prevent the increase of produced NOx in addition to controlling combustion instability would be very desirable. As it was said, the method proposed in the current application is different from the previous methods and its basis is the change in the amount of fuel of the main fuel routes A and B.

[0037] By performing this method, the pilot fuel flow rate may not change and therefore the flame temperature and consequently the output NOx pollutant may not change as well. This method may satisfactorily cause a significant improvement in the control of combustion instability in the combustion chamber of the gas turbine, and more importantly, despite the significant improvement in the control of combustion instability in the combustion chamber of the gas turbine, it may prevent the increase of production NOx.

[0038] Disclosed herein is a method for controlling instability in a combustion chamber of a gas turbine. FIG. 1 shows a schematic of a combustion chamber 100 of a gas turbine, consistent with one or more exemplary embodiments of the present disclosure. As shown in FIG. 1, in an exemplary embodiment, combustion chamber 100 may include a first main burner 101, a pilot burner 102, a second main burner 103, a first main fuel feed tube 104, a pilot fuel feed tube 105, and a second main fuel feed tube 106. In an exemplary embodiment, combustion chamber 100 may further include a first main valve 142, a pilot valve 152, and a second main valve 162. [0039] FIG. 2 shows a flowchart of a method 200 for controlling instability in a combustion chamber of a gas turbine, consistent with one or more exemplary embodiments of the present disclosure. For example, method 200 may be used for controlling instability in combustion chamber 100 of the gas turbine.

[0040] As shown in FIG. 2, in an exemplary embodiment, method 200 may include a first step 201 of measuring pressure fluctuation in combustion chamber 100 during a first period of time. In an exemplary embodiment, pressure fluctuation of combustion chamber 100 may be measured by using a pulsation sensor. In an exemplary embodiment, pressure fluctuation of combustion chamber 100 may be measured continuously by the pulsation sensor. In an exemplary embodiment, the pulsation sensor may send the measured data to a processor. In an exemplary embodiment, the measured data may also be shown to an operator.

[0041] In an exemplary embodiment, method 200 may further include a second step 202 of obtaining a first amplitudes of pressure fluctuation in the first period of time based on measured pressure fluctuation during the first period of time. In an exemplary embodiment, the first amplitudes of pressure fluctuation in the first period of time may be obtained based on measured data by the pulsation sensor. In an exemplary embodiment, the processor may obtain the first amplitudes of pressure fluctuation in the first period of time based on measured pressure fluctuation during the first period of time. In an exemplary embodiment, an operator may also obtain the first amplitudes of pressure fluctuation in the first period of time based on measured pressure fluctuation during the first period of time. [0042] In an exemplary embodiment, method 200 may further include a third step 203 of comparing the first amplitudes of pressure fluctuation with predetermined acceptable amplitudes. In an exemplary embodiment, the comparison between the first amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the processor. In an exemplary embodiment, the comparison between the first amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the operator. In an exemplary embodiment, if the first amplitudes of pressure fluctuation are less than predetermined acceptable amplitudes and in other words is within the acceptable range, there is no change in the fuel flow rate of first main burner 101, pilot burner 102, and second main burner 103, and the turbine continues to operate in the same way.

[0043] In an exemplary embodiment, method 200 may further include a fourth step 204. In an exemplary embodiment, in order to implement fourth step 204 of method 200, if the first amplitudes of pressure fluctuation is greater than the predetermined acceptable amplitudes, a fuel flow rate of first main burner 101 may be decreased by a first amount and a fuel flow rate of second main burner 103 may be increased by the first amount. In an exemplary embodiment, the first amount may be two percent of the total fuel injected into combustion chamber 100 through first main burner 101, pilot burner 102, and second main burner 103. In an exemplary embodiment, the processors may be in connection with first main valve 142, pilot valve 152, and second main valve 162 to regulate the flow rate of each of first main burner 101, pilot burner 102, and second main burner 103.

[0044] For example, in an exemplary scenario, it may be assumed that, before implementing fourth step 204, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 is such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102, 45 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 45 % of the total fuel is injected to combustion chamber 100 through second main burner 103. In an exemplary embodiment, after implementing fourth step 204, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 may be such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102, 43 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 47 % of the total fuel is injected to combustion chamber 100 through second main burner 103.

[0045] In an exemplary embodiment, method 200 may further include a fifth step 205 of waiting for a first amount of time. In an exemplary embodiment, after that the fuel flow rate distribution between first main burner 101 and second main burner 103 is changed, the first amount of time may be given to combustion chamber 100 so that combustion chamber 100 has enough time to reach a stable condition. In an exemplary embodiment, the first amount of time may be 10 seconds. In other words, in order to implement fifth step 205 of method 100, 10 seconds may be given to combustion chamber 100 so that combustion chamber 100 reaches a stable condition.

[0046] In an exemplary embodiment, method 200 may further include a sixth step 206 of measuring pressure fluctuation in the combustion chamber during a second period of time by using the pulsation sensor. In an exemplary embodiment, in order to implement sixth step 206 of method 200, pressure fluctuation in combustion chamber 100 may be measured by the pulsation sensor during the second period of time. In an exemplary embodiment, method 200 may further include a seventh step 207 of obtaining a second amplitudes of pressure fluctuation in the second period of time based on measured pressure fluctuation during the second period of time. In an exemplary embodiment, the second amplitudes of pressure fluctuation in the second period of time may be obtained based on measured data by the pulsation sensor. In an exemplary embodiment, the processor may obtain the second amplitudes of pressure fluctuation in the second period of time based on measured pressure fluctuation during the second period of time. In an exemplary embodiment, an operator may also obtain the second amplitudes of pressure fluctuation in the second period of time based on measured pressure fluctuation during the second period of time.

[0047] In an exemplary embodiment, method 200 may further include an eighth step 207 of comparing the second amplitudes of pressure fluctuation with the predetermined acceptable range. In an exemplary embodiment, the comparison between the second amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the processor. In an exemplary embodiment, the comparison between the second amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the operator. In an exemplary embodiment, if the second amplitudes of pressure fluctuation is less than predetermined acceptable amplitudes and in other words is within the acceptable range, there is no change in the fuel flow rate of first main burner 101, pilot burner 102, and second main burner 103, and the turbine continues to operate in the same way.

[0048] In an exemplary embodiment, method 200 may further include an eighth step 208. In an exemplary embodiment, in order to implement eighth step 208 of method 200, if the second amplitudes of pressure fluctuation is greater than the predetermined acceptable amplitudes, fuel flow rate of first main burner 101 may be decreased by a second amount and fuel flow rate of second main burner 103 may be increased by the second amount. In an exemplary embodiment, the second amount may be two percent of the total fuel injected into combustion chamber 100 through first main burner 101, pilot burner 102, and second main burner 103.

[0049] For example, in an exemplary scenario, it may be assumed that, before implementing eighth step 208, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 is such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102,43 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 47 % of the total fuel is injected to combustion chamber 100 through second main burner 103. In an exemplary embodiment, after implementing eighth step 208, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 may be such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102, 41 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 49 % of the total fuel is injected to combustion chamber 100 through second main burner 103.

[0050] In an exemplary embodiment, method 200 may further include a ninth step 209 of waiting for a second amount of time. In an exemplary embodiment, after that the fuel flow rate distribution between first main burner 101 and second main burner 103 is changed, the second amount of time may be given to combustion chamber 100 so that combustion chamber 100 has enough time to reach a stable condition. In an exemplary embodiment, the second amount of time may be 10 seconds. In other words, in order to implement ninth step 209 of method 100, 10 seconds may be given to combustion chamber 100 so that combustion chamber 100 reaches a stable condition.

[0051] In an exemplary embodiment, method 200 may further include a tenth step 210 of measuring pressure fluctuation in the combustion chamber during a third period of time by using the pulsation sensor. In an exemplary embodiment, in order to implement tenth step 210 of method 200, pressure fluctuation in combustion chamber 100 may be measured by the pulsation sensor during the third period of time. In an exemplary embodiment, method 200 may further include an eleventh step 211 of obtaining a third amplitudes of pressure fluctuation in the third period of time based on measured pressure fluctuation during the third period of time. In an exemplary embodiment, the third amplitudes of pressure fluctuation in the third period of time may be obtained based on measured data by the pulsation sensor. In an exemplary embodiment, the processor may obtain the third amplitudes of pressure fluctuation in the third period of time based on measured pressure fluctuation during the third period of time. In an exemplary embodiment, an operator may also obtain the third amplitudes of pressure fluctuation in the third period of time based on measured pressure fluctuation during the third period of time.

[0052] In an exemplary embodiment, method 200 may further include a twelfth step 212 of comparing the third amplitudes of pressure fluctuation with the predetermined acceptable range. In an exemplary embodiment, the comparison between the third amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the processor. In an exemplary embodiment, the comparison between the third amplitudes of pressure fluctuation and the predetermined acceptable amplitudes may be done by the operator.

[0053] In an exemplary embodiment, method 200 may further include a thirteenth step 213. In an exemplary embodiment, in order to implement thirteenth step 213 of method 200, if the third amplitudes of pressure fluctuation is greater than the predetermined acceptable amplitudes, fuel flow rate of first main burner 101 may be decreased by a third amount and fuel flow rate of second main burner 103 may be increased by the third amount. In an exemplary embodiment, the third amount may be two percent of the total fuel injected into combustion chamber 100 through first main burner 101, pilot burner 102, and second main burner 103.

[0054] For example, in an exemplary scenario, it may be assumed that, before implementing thirteenth step 213 of method 200, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 is such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102, 41 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 49 % of the total fuel is injected to combustion chamber 100 through second main burner 103. In an exemplary embodiment, after implementing thirteenth step 213 of method 200, the fuel flow rate distribution between first main burner 101, pilot burner 102, and second main burner 103 may be such that 10 % of the total fuel is injected to combustion chamber 100 through pilot burner 102, 39 % of the total fuel is injected to combustion chamber 100 through first main burner 101, and 51 % of the total fuel is injected to combustion chamber 100 through second main burner 103.

[0055] In an exemplary embodiment, if, after implementing thirteenth step 213 of method 200, amplitudes of pressure fluctuation are less than predetermined acceptable amplitudes and in other words is within the acceptable range, there is no change in the fuel flow rate of first main burner 101, pilot burner 102, and second main burner 103, and the turbine continues to operate in the same way. But if, after implementing thirteenth step 213 of method 200, amplitudes of pressure fluctuation are greater than predetermined acceptable amplitudes and in other words is not within the acceptable range, the gas turbine may be tripped and in order to avoid accidents, it may be prevented from working in the unstable combustion state of the combustion chamber.

[0056] FIG. 3 shows an exemplary embodiment of processing unit 300 in which an exemplary embodiment of the present disclosure, or portions thereof, may be implemented as computer- readable code, consistent with one or more exemplary embodiments of the present disclosure. For example, an exemplary processor may be implemented in processing unit 300 using hardware, software, firmware, tangible computer readable media having instructions stored thereon, or a combination thereof and may be implemented in one or more computer systems or other processing systems. In an exemplary embodiment, the processors mentioned above may be similar to processing unit 300 of FIG. 3. [0057] If programmable logic is used, such logic may execute on a commercially available processing platform or a special purpose device. One of ordinary skill in the art may appreciate that an exemplary embodiment of the disclosed subject matter can be practiced with various computer system configurations, including multi-core multiprocessor systems, minicomputers, mainframe computers, computers linked or clustered with distributed functions, as well as microcontrollers, pervasive or miniature computers that may be embedded into virtually any device.

[0058] For instance, a computing device having at least one processor device and a memory may be used to implement the above-described embodiments. A processor device may be a single processor, a plurality of processors, or combinations thereof. Processor devices may have one or more processor “cores.”

[0059] An exemplary embodiment of the present disclosure is described in terms of this example processing unit 300. After reading this description, it will become apparent to a person skilled in the relevant art how to implement the present disclosure using other computer systems and/or computer architectures. Although operations may be described as a sequential process, some of the operations may in fact be performed in parallel, concurrently, and/or in a distributed environment, and with program code stored locally or remotely for access by single or multi-processor machines. In addition, in some embodiments the order of operations may be rearranged without departing from the spirit of the disclosed subject matter.

[0060] Processor device 304 may be a special purpose or a general-purpose processor device. As will be appreciated by persons skilled in the relevant art, processor device 304 may also be a single processor in a multi-core/multiprocessor system, such system operating alone, or in a cluster of computing devices operating in a cluster or server farm. In an exemplary embodiment, processor device 304 may be connected to a communication infrastructure 306, for example, a bus, message queue, network, or multi-core message-passing scheme.

[0061] In an exemplary embodiment, processing unit 300 may also include a main memory 308, for example, random access memory (RAM), and may also include a secondary memory 310. In an exemplary embodiment, secondary memory 310 may include a hard disk drive 312, and a removable storage drive 314. In an exemplary embodiment, removable storage drive 314 may include a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory, or the like. In addition, removable storage drive 314 may read from and/or write to a removable storage unit 318 in a well-known manner. In an exemplary embodiment, removable storage unit 318 may include a floppy disk, magnetic tape, optical disk, etc., which may be read by and written to by removable storage drive 314. As will be appreciated by persons skilled in the relevant art, removable storage unit 318 may include a computer usable storage medium having stored therein computer software and/or data.

[0062] In alternative implementations, secondary memory 310 may include other similar means for allowing computer programs or other instructions to be loaded into processing unit . Such means may include, for example, a removable storage unit 322 and an interface 320. Examples of such means may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM, or PROM) and associated socket, and other removable storage units 322 and interfaces 320 which allow software and data to be transferred from removable storage unit 322 to processing unit 300.

[0063] In an exemplary embodiment, processing unit 300 may also include a communications interface 324. Communications interface 324 may allow software and data to be transferred between processing unit 300 and external devices. In an exemplary embodiment, communications interface 324 may include a modem, a network interface (such as an Ethernet card), a communications port, a PCMCIA slot and card, or the like. Software and data transferred via communications interface 324 may be in the form of signals, which may be electronic, electromagnetic, optical, or other signals capable of being received by communications interface 324. These signals may be provided to communications interface 324 via a communications path 326. In an exemplary embodiment, communications path 326 may carry signals and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an RF link or other communications channels.

[0064] In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as removable storage unit 318, removable storage unit 322, and a hard disk installed in hard disk drive 312. Computer program medium and computer usable medium may also refer to memories, such as main memory 308 and secondary memory 310, which may be memory semiconductors (e.g. DRAMs, etc.).

[0065] In some exemplary embodiment, computer programs (also called computer control logic) may be stored in main memory 308 and/or secondary memory 310. Computer programs may also be received via communications interface 324. Such computer programs, when executed, enable processing unit 300 to implement the present disclosure as discussed herein. In particular, the computer programs, when executed, may enable processor device 304 to implement the processes of the present disclosure. Accordingly, such computer programs represent controllers of processing unit 300. Where the present disclosure is implemented using software, the software may be stored in a computer program product and loaded into processing unit 300 using removable storage drive 314, interface 320, and hard disk drive 312, or communications interface 324.

[0066] Embodiments of the present disclosure may also be directed to computer program products including software stored on any computer useable medium. Such software, when executed in one or more data processing devices, causes a data processing device(s) to operate as described herein. An exemplary embodiment of the present disclosure may employ any computer useable or readable medium. Examples of computer useable mediums include, but are not limited to, primary storage devices (e.g., any type of random access memory), secondary storage devices (e.g., hard drives, floppy disks, CD ROMS, ZIP disks, tapes, magnetic storage devices, and optical storage devices, MEMS, nanotechnological storage device, etc.).

[0067] It should be noted that performing steps of method 200 as mentioned above may lead to the control of combustion instability in the combustion chamber of the gas turbine and at the same time may prevent the increase of NOx production. This method is tested on a burner with a real scale in the working conditions of the machine. The results show a significant reduction in the range of vibrations. It should be mentioned that in this case, the valves used only to regulate the flow rate and there is no need to cause fluctuation in the fuel flow rate. Therefore, a normal control valve is enough to do this. This may greatly reduce the complexity of the system from the point of view of hardware and software.

[0068] This method can be used in hydrogen burners. One of the proposed methods to reduce pollution that has been noticed in recent years is the use of hydrogen as a fuel. According to the existing technology, hydrogen is used in combination with natural gas as a fuel, which may lead to a significant reduction in pollution. The issue of instabilities caused by fluctuation (along with other problems of hydrogen burning burners) is of more importance because adding hydrogen to natural gas increases the humming potential. In order to ensure the effectiveness of the proposed method, this method was used in different mixing percentages of hydrogen and natural gas. The results in this case also show that the change in fuel injection rate is significantly effective and its effectiveness is more in comparison with pure gas fuel. [0069] In order to ensure the correctness of the function of changing the fuel injection rate in reducing fluctuation, this case was tested in a set of combustion chamber in real scale. For this purpose, a complete chamber including burner, liner and other parts was made in full scale. Also, a test stand has been developed for this purpose. Combustion chamber test was done in the real temperature and pressure conditions of the machine. The results show that very small changes in the fuel flow rate (less than 5% change in the flow rate) lead to a significant reduction in the range of pressure changes so that the combustion chamber assembly is completely away from the criticality threshold. The results of a sample of the tests is shown in FIG. 4. FIG. 4 shows the test results in two modes before (the left column at each frequency) and after (the right column at each frequency) changing the fuel flow rate. The results clearly show the reduction of the pressure fluctuation range due to fuel flow stirring. As explained above, by implementing the proposed method (applying changes in the main fuel flow rate and keeping the pilot fuel flow rate constant), the NOx pollutant output from the combustion chamber has not changed either.

[0070] As discussed, the method used based on the active changes of the fuel flow rate between different channels of a burner has a significant effect in reducing the range of pressure fluctuation and increasing the stability of the combustion chamber in natural gas fuel and various combinations of hydrogen and natural gas. At the same time, this method may lead to a reduction in the range of pressure fluctuation and an increase in the stability of the combustion chamber, it may also prevent the increase of production of NOx. Compared to existing methods, this method has fewer fuel injection channels and much simpler control system hardware and software. At the same time, it has a good performance and this has been proven by making a test rig and testing in the operating conditions of the machine. [0071] While the foregoing has described what may be considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.

[0072] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0073] The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0074] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0075] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective spaces of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0076] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and/or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.