GAS TURBINE AND METHOD FOR CONTROLLING A CONNECTION AIR VOLUME FOR THE GAS TURBINE

Abstract

Gas turbine (100), comprising the following: a compressor (1) configured to compress air; a combustion device (2) configured to burn a fuel mixed with the air compressed by the compressor (1) to produce a combustion gas; a turbine (3) configured to be driven by the combustion gas produced by the combustion device (2); a heat exchanger (5) configured to cause the fuel to be supplied to the combustion device (2) to be heated by cooling air drawn from the compressor (1) to be supplied to the turbine (3); a dispensing valve (6) configured to control a volume flow of cooling air; a first sensor (7, 8) that is configured to measure a state value related to the fuel; a second sensor (9, 10) configured to measure a state value related to the cooling air; and a control computer (11) which is configured to control an opening degree of the dispensing valve (6), wherein the control computer (11) stores data on reference values ​​and dead zones, which contain the corresponding set of reference values ​​for each of the measured values ​​of the first sensor (7, 8) and the second sensor (9, 10), and then, when a measured value measured by the first sensor (7, 8) and a measured value measured by the second sensor (9, 10) have changed so far from the corresponding reference value that they fall out of the corresponding dead zone, controls the dispensing valve (6) in such a way that the changed measured values ​​are brought close to the corresponding reference values.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to a gas turbine and in particular to a gas turbine in which a fuel to be supplied to a combustion device is heated by heat exchange between the fuel and a cooling air drawn from a compressor, and a method for controlling the volume of the bleed air therefor. 2. Description of the related area

[0002] In a gas turbine, a fuel mixed with compressed air (which has been compressed by a compressor) is burned in a combustion unit to produce a combustion gas as a high-temperature working fluid, and the turbine is driven by this combustion gas. In some gas turbines of this type, the fuel supplied to the combustion unit is heated by heat exchange between the fuel and compressed air from a compressor to improve the system thermal efficiency by reducing the required fuel flow rate to the combustion unit to produce a combustion gas at a desired temperature (see JP-2014-047657-A and similar documents).

[0003] EP 3 246 545 A1 discloses a method for operating a stabilizing heat exchanger of a gas turbine engine, which provides thermal communication between cooling air as a heat source and fuel as a heat sink in order to counteract supercritical fluid vibrations.

[0004] US Patent 2014 / 0131027 A1 discloses a heat exchange arrangement for a gas turbine engine. The arrangement includes a first line for an engine component cooling fluid and a second line for a second fluid. The arrangement further includes a heat exchange section in which the fluids flowing through the first and second lines are in a heat exchange relationship. A valve is provided that is configured to moderate the mass flow of one of the fluids through the heat exchange section. SUMMARY OF THE INVENTION

[0005] In a gas turbine where compressed air drawn from a compressor is used for cooling, if the fuel is heated by heat exchange between the fuel and the cooling air supplied to the turbine, not only can the system efficiency be improved, but the volume flow rate of the cooling air can also be reduced due to a decrease in the cooling air temperature. In this case, the performance of the gas turbine can be further enhanced by equipping the turbine with a tap valve capable of controlling the volume flow rate of the cooling air and by controlling the tap valve according to the temperature of a high-temperature part of the turbine that is to be cooled by the cooling air.

[0006] However, the properties of the fuel are not necessarily stable, and the temperature of the cooling air undergoing heat exchange with the fuel can change significantly. Such a change in the cooling air temperature leads to a change in the temperature of the high-temperature section of the turbine, and consequently, the opening degree of the discharge valve constantly changes. This can result in an unstable volume flow of the cooling air.

[0007] It is an object of the present invention to provide a gas turbine that can prevent or reduce an oversensitive change in the opening degree of a bleed valve that controls the volume flow of cooling air used to heat a fuel, and a method for controlling the bleed air volume therefor.

[0008] To solve the aforementioned problem, a gas turbine with the features of claim 1 and a method for controlling a bleed air volume for a gas turbine with the features of claim 4 are provided. Advantageous embodiments are defined in the dependent claims.

[0009] According to the present invention, it is possible to prevent an oversensitive change in the opening degree of the dispensing valve that controls the volume flow of the cooling air used to heat the fuel. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram of an example of a gas turbine according to a first embodiment of the present invention; Fig. 2 is a flowchart that represents a procedure for controlling a tap valve of the gas turbine according to the first embodiment of the present invention, which serves to improve understanding of the invention but is not covered by the scope of protection of the claims; Fig. Figure 3 is a model diagram illustrating changes over time of a fuel state value and a cooling air state value to explain a timing of the control of the dispensing valve in the gas turbine according to the first embodiment of the present invention; Fig. Figure 4 is a flowchart representing a procedure for controlling a dispensing valve of a gas turbine according to a second embodiment of the present invention; and Fig. Figure 5 is a model diagram illustrating changes over time of a fuel state value and a cooling air state value to explain a timing of the control of the dispensing valve in the gas turbine according to the second embodiment of the present invention. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0010] In the following, embodiments of the present invention are described with reference to the accompanying drawings. First design gas turbine -

[0011] Fig. Figure 1 is a schematic diagram of an example of a gas turbine according to a first embodiment of the present invention. It should be noted that the first embodiment shown in the description serves to illustrate the invention and to facilitate understanding of the technical teaching. However, this embodiment is not covered by the scope of amended claim 1. In the present embodiment, a gas turbine combustion device is simply referred to as a combustion device. A gas turbine 100, which is in Fig. Figure 1 shows a compressor 1, a combustion device 2, a turbine 3, a load device 4, a heat exchanger 5, a dispensing valve 6, first sensors 7 and 8, second sensors 9 and 10 and a control computer 11.

[0012] Compressor 1 compresses air A, which is drawn in through an air inlet, to produce and deliver compressed high-pressure air C. Combustion device 2 burns fuel mixed with the compressed air C from compressor 1 to produce a high-temperature combustion gas H, and feeds the combustion gas H to turbine 3. Turbine 3 is driven by the combustion gas H produced by combustion device 2. The compressor and turbine 3 are coaxially connected, and the load device 4, e.g., a generator or pump, is connected to either compressor 1 or turbine 3. Rotational power obtained from turbine 3 is used partly to power compressor 1 and partly to power load device 4. After driving turbine 3, the combustion gas H is released as exhaust gas E.

[0013] The heat exchanger 5 is arranged along a fuel line (fuel line system) 12, which connects a fuel source (not shown) and the combustion device 2, and effects a heat exchange between the fuel flowing in the fuel line 12 and bleed air flowing in the bleed line (bleed line system) 13. The bleed line 13 connects an intermediate stage or outlet of the compressor 1 to an intermediate stage or inlet of the turbine 3. The bleed air flowing in the bleed line 13, after being drawn from the compressor 1, heats the fuel flowing in the fuel line 12, causing its temperature to decrease accordingly, and is then supplied to a high-temperature section of the turbine 3 as cooling or sealing air.In contrast, the fuel flowing in fuel line 12 experiences an increase in temperature due to the heat input from the bleed air flowing in bleed line 13 and is then supplied to the combustion device 2.

[0014] The dispensing valve 6 is a valve device that controls the volume flow of the cooling air and is arranged between the heat exchanger 5 and the turbine 3 along the dispensing line 13. It should be noted that it may be sufficient for the dispensing valve 6 to be arranged along the dispensing line 13, or alternatively, the dispensing valve 6 can be arranged between the heat exchanger 5 and the compressor 1 along the dispensing line 13. The dispensing valve 6 is actuated in response to a signal from the control computer 11, and the opening degree of the dispensing valve 6 is controlled by the control computer 11 to regulate the volume flow of the dispensed air.

[0015] The first sensors 7 and 8 are configured to each measure a state value related to the fuel. This state value includes a fuel flow rate Ff, a fuel temperature Tf, and the like. In the present embodiment, the first sensor 7 is a thermometer, while the first sensor 8 is a flow meter. In the illustrated configuration, both the first sensor 7 and the second sensor 8 are arranged between the heat exchanger 5 and the combustion unit 2 along the fuel line 12 to measure the fuel-related state values ​​after the heat exchange between the fuel and the bleed air in the heat exchanger 5 has been completed.It should be noted that both the first sensor 7 and the first sensor 8 can alternatively be arranged upstream of the heat exchanger 5 along the fuel line 12. Although in the present embodiment the flow measuring device is used as the first sensor 8 to measure the fuel flow rate Ff, the fuel flow rate Ff can alternatively be estimated, for example, from the opening degree of a fuel flow control valve 14 arranged in the fuel line 12. The opening degree of the fuel flow control valve 14 can be measured via an opening measuring device and can also be known from an instruction value of the control computer 11 for the fuel flow control valve 14.Although the fuel flow rate Ff, the fuel temperature Tf, and the opening degree of the fuel flow control valve 14 can all be measured in one possible configuration, it is not necessary to measure all of them as state values ​​related to the fuel. It may be sufficient to measure at least one of the above values. Alternatively, in another possible configuration, the fuel pressure can be measured as a state value related to the fuel using a pressure gauge located in the fuel line 12.

[0016] The second sensors 9 and 10 are configured to each measure a state value related to the cooling air, i.e., the bleed air. This state value includes a cooling air volume flow rate Fa and a cooling air temperature Ta. In the present embodiment, the second sensor 9 is a thermometer, while the second sensor 10 is a flow meter. In the illustrated configuration, the two sensors 9 and 10 are arranged between the heat exchanger 5 and the turbine 3 along the bleed line 13 to measure the state value related to the cooling air after the heat exchange between the fuel and the cooling air in the heat exchanger 5 has been completed. It should be noted that both the second sensor 9 and the second sensor 10 can alternatively be arranged upstream of the heat exchanger 5 along the bleed line 13.Although in the present embodiment the flow measuring device is used as the second sensor 10 to measure the cooling air volume flow rate Fa, the cooling air volume flow rate Fa can alternatively be estimated, for example, from the opening degree of the dispensing valve 6, which is arranged in the dispensing line 13. The opening degree of the dispensing valve 6 can be measured using an opening measuring device and can also be known from an instruction value of the control computer 11 for the dispensing valve 6. Although the cooling air volume flow rate Fa, the cooling air temperature Ta, and the opening degree of the cooling air volume flow control valve 14 can all be measured in one possible configuration, it is not necessary to measure all of these as the state values ​​related to the cooling air. It may be sufficient if at least one of the above-mentioned values ​​is measured.Alternatively, in another possible configuration, the pressure of the cooling air can be measured as a state value related to the cooling air using a pressure gauge located in the bleed air line 13.

[0017] The control computer 11 is a control unit for controlling the opening degree of the dispensing valve 6 and has the function of controlling not only the dispensing valve 6 but the entire gas turbine 100. The control computer 11 is equipped with a memory and a central processing unit (CPU), and the memory contains data about a reference value such as a0 or b0. Fig. 3 and a dead zone that is in Fig. 3, specified by a1 and a2 or b1 and b2, is stored, containing the reference value set for the measured values ​​of each of the first sensors 7 and 8 and the measured values ​​of each of the second sensors 9 and 10. Here, it is assumed that the reference values ​​a0 and b0 and the limits of the dead zones a1 and a2 and b1 and b2, where a1 < a0 < a2 and b1 < b0 < b2, are set for each operating condition, e.g., part-load operation or full-load operation. Additionally, the control computer 11 loads a program stored in memory into the CPU and controls the dispensing valve 6 such that whenever at least one of the measured values, which contains the measured values ​​of the first sensors 7 and 8 and the measured values ​​of the second sensors 9 and 10, has changed so far from the corresponding reference value that it falls out of the corresponding dead zone, the changed measured value is brought close to the corresponding reference value.It should be noted that the control computer 11 also has a general function to control the fuel volume flow control valve 14 according to a start-up time schedule or a load instruction for the gas turbine 100. - Dispensing valve control method -

[0018] Fig. Figure 2 is a flowchart illustrating a procedure for controlling a tap valve of the gas turbine according to the first embodiment of the present invention. It should be noted that the first embodiment described in the description serves to illustrate the invention and facilitate understanding of the technical teaching. However, this embodiment is not covered by the scope of amended claim 1. Fig. Figure 3 is a model diagram illustrating changes over time of a fuel state value and a cooling air state value to explain the timing of the control of the dispensing valve in the gas turbine according to the first embodiment of the present invention. After loading the program into the CPU and starting the control, which is in Fig. As shown in Figure 2, the control computer 11 receives input measurement signals from the first sensors 7 and 8 and the second sensors 9 and 10. In step 11, it first determines whether the fuel state value a falls within the corresponding dead zone. The dead zone defines a range that is set for the fuel state value a and contains the reference value a0. The dead zone extends from the lower limit a1 to the upper limit a2, that is, a1 < a0 < a2. The fuel state value a is the measured value of each of the first sensors 7 and 8. In the present embodiment, it is determined whether, for example, the fuel temperature Tf and the fuel volume flow rate Ff fall within the corresponding dead zone, and it is determined that the fuel state value a falls out of the corresponding dead zone if the fuel temperature Tf and / or the fuel volume flow rate Ff falls out of the corresponding dead zone.It should be noted that alternatively, it can be determined that the fuel state value a falls out of the corresponding dead zone only if both the value of the fuel temperature Tf and the value of the fuel volume flow rate Ff fall out of the corresponding dead zone.

[0019] If the fuel state value a falls into the corresponding dead zone, the control computer 11 determines in step 12 whether the cooling air state value b falls into the corresponding dead zone. As in the case with the fuel state value a, the dead zone defines a range that is set for the cooling air state value b and that contains the reference value b0. The dead zone extends from the lower limit b1 to the upper limit b2, that is, b1 < b0 < b2. The cooling air state value b is the measured value of each of the second sensors 9 and 10. In the present embodiment, it is determined whether, for example, the cooling air temperature Ta and the cooling air volume flow rate Fa fall into the corresponding dead zone, and it is determined that the cooling air state value b falls out of the corresponding dead zone if the cooling air temperature Ta and / or the cooling air volume flow rate Fa falls out of the corresponding dead zone.It should be noted that, alternatively, it can be determined that the cooling air condition value b only falls out of the corresponding dead zone if both the cooling air temperature value Ta and the cooling air volume flow rate value Fa fall out of the corresponding dead zone. Furthermore, the sequence of steps S11 and S12 can be reversed.

[0020] If, as a result of the determinations in steps S11 and S12, it is found that both the fuel state value a and the cooling air state value b fall into the corresponding dead zones, the control computer 11 retains the current opening degree of the dispensing valve 6 and returns the control to step S11. Meanwhile, in step 13, if the fuel state value a and the cooling air state value b have changed so far from the corresponding reference values ​​that they fall out of the corresponding dead zones, the control computer 11 changes the opening degree of the dispensing valve 6 and returns the control to step S11. In step 13, the opening degree of the dispensing valve 6 is changed such that the fuel state value a and the cooling air state value b that have changed so much that they fall out of the corresponding dead zone is brought close to the corresponding reference value. For example, ifIf the fuel temperature Tf has risen to such an extent that it falls out of the corresponding dead zone, the opening degree of the dispensing valve 6 is reduced to decrease the cooling air volume flow Fa and thereby reduce the fuel temperature Tf. If, for example, the cooling air temperature Ta has decreased to such an extent that it falls out of the corresponding dead zone, the opening degree of the dispensing valve 6 is increased to increase the cooling air volume flow Fa and thereby increase the cooling air temperature Ta.

[0021] In the case of the example of Fig. 3. The fuel state value a falls out of the corresponding dead zone during a period from t1 to t2. Additionally, the cooling air state value b falls out of the corresponding dead zone during a period from t3 to t4, and both the fuel state value a and the cooling air state value b fall out of their respective dead zones during a period from t4 to t5. Afterward, the cooling air state value b returns to its corresponding dead zone at time t5, and only the fuel state value a falls out of its corresponding dead zone during a period from t5 to t6. Both the fuel state value a and the cooling air state value b fall into their respective dead zones before time t1, during a period from t2 to t3, and after time t6.In this case, before time t1, during a period from t2 to t3 and after time t6, the opening degree of the tap valve 6 is maintained, while the opening degree of the tap valve 6 is controlled for compensation during the periods from t1 to t2 and from t3 to t6. - Beneficial effects -

[0022] According to the present embodiment, an improvement in system thermal efficiency can be achieved by heating the fuel via heat exchange between the fuel and the cooling air drawn from the compressor 1 and supplied to the turbine 3. Additionally, the temperature of the cooling air used to cool the turbine 3 is reduced by the heat exchange between the fuel and the cooling air, thus allowing a reduction in the cooling air flow rate. This enables the performance of the gas turbine to be appropriately improved by controlling the opening degree of the draw-off valve 6 in accordance with the temperature of the high-temperature part of the turbine 3 that is to be cooled.

[0023] In particular, in the present embodiment, dead zones are provided for the fuel state value a and the cooling air state value b for controlling the dispensing valve 6 based on the fuel state value a and the cooling air state value b. Accordingly, even if a fluctuation in the temperature change of the high-temperature part of the turbine 3 occurs due to unstable fuel properties, the opening degree of the dispensing valve 6 does not change in an overly sensitive manner. Thus, an overly sensitive change in the opening degree of the dispensing valve 6 can be prevented in order to reduce fluctuations in the volume flow of the cooling air. - Method for controlling the volume flow of bleed air -

[0024] The reference value and dead zone data, which contain the reference value, are determined in advance for both the fuel state value and the cooling air state value. When the fuel state value and the cooling air state value have changed so far from the corresponding reference value that they fall out of the corresponding dead zone, the dispensing valve is actuated such that the changed state value is brought closer to the corresponding reference value. Using this method prevents an oversensitive change in the opening degree of the dispensing valve, which controls the volume flow of the cooling air used to heat the fuel, as described above. Although in the first embodiment, as well as in the second embodiment described below, it is assumed that the method described above is implemented by the control computer 11, the same or similar advantageous effects can be achieved, for example, by...This can also be achieved by manually operating the dispensing valve 6 by an operator in a control room, provided it is possible to monitor the fuel state and cooling air state values. In this case, the control computer 11 does not necessarily need to be able to control the dispensing valve, as in . Fig. 2 is shown. Second embodiment

[0025] Fig. Figure 4 is a flowchart that represents a procedure for controlling a dispensing valve of a gas turbine according to a second embodiment of the present invention. Fig. Figure 5 is a model diagram illustrating changes over time of a fuel state value and a cooling air state value to explain a timing of the control of the dispensing valve in the gas turbine according to the second embodiment of the present invention. Fig. 4 and Fig. 5 correspond Fig. 2 or Fig. 3. The present embodiment differs from the first embodiment in that the control of changing the opening degree of the dispensing valve 6 is only carried out when both the fuel state value a and the cooling air state value b have fallen out of the corresponding dead zones, and has a similar hardware configuration to the first embodiment.

[0026] After the program is loaded into the CPU and the control system is started, which is in Fig. As shown in Figure 4, the control computer 11 receives inputs of measurement signals from the first sensors 7 and 8 and the second sensors 9 and 10 and, in step 21, first determines whether the fuel state value a falls into the corresponding dead zone. If the fuel state value a falls outside the corresponding dead zone, the control computer 11 determines, in step 22, whether the cooling air state value b falls into the corresponding dead zone. If, as a result of the determinations in steps S21 and S22, it is found that the fuel state value a and / or the cooling air state value b fall into the corresponding dead zones, the control computer 11 retains the current opening degree of the dispensing valve 6 and returns the control to step S21.Meanwhile, in step 23, if both the fuel state value a and the cooling air state value b have changed so far from their respective reference values ​​that they fall out of their respective dead zones, the control computer 11 changes the opening degree of the dispensing valve 6 and returns the control to step S21. The individual processes carried out in steps S21, S22, and S23 are analogous to the processes carried out in steps S11, S12, and S13, respectively. Fig. 2 will be carried out similarly.

[0027] In the case of the example of Fig. 5 falls as in the case of the example of Fig. 3. The fuel state value a falls out of the corresponding dead zone during a period from t1 to t2. Additionally, the cooling air state value b falls out of the corresponding dead zone during a period from t3 to t4, and both the fuel state value a and the cooling air state value b fall out of their respective dead zones during a period from t4 to t5. Afterward, the cooling air state value b returns to its corresponding dead zone at time t5, and only the fuel state value a falls out of its corresponding dead zone during a period from t5 to t6. Both the fuel state value a and the cooling air state value b fall into their respective dead zones before time t1, during a period from t2 to t3, and after time t6. In this case, the opening degree of the dispensing valve 6 is maintained before time t4 and after time t5, while the opening degree of the dispensing valve 6 is controlled for compensation during the periods from t4 to t5.

[0028] The present embodiment can also achieve advantageous effects similar to those of the first embodiment. Since the opening degree of the dispensing valve 6 is only changed when both the fuel state value a and the cooling air state value b fall out of their respective dead zones, the change in the opening degree of the dispensing valve can also be reduced compared to the first embodiment. The first or the second embodiment can be chosen for use, as appropriate. Variations

[0029] While in Fig.1. Since a single-shaft gas turbine is represented as a gas turbine according to one embodiment of the present invention, the same or similar advantageous effects can be achieved when the present invention is applied to other types of gas turbines. For example, the present invention is also applicable to a twin-shaft gas turbine comprising a high-pressure turbine connected to a compressor and a low-pressure turbine separate from the high-pressure turbine and connected to a load device 4, and in this case, too, the same or similar advantageous effects can be achieved. Additionally, in one embodiment of the present invention, the control mode according to the first embodiment and the control mode according to the second embodiment can be provided, for example, as a first mode and a second mode, respectively, wherein the control mode of the dispensing valve 6 is manually controlled, for example.They can be switched between by means of a switching process.

Claims

[1] Gas turbine (100) comprising the following: a compressor (1) configured to compress air; a combustion device (2) configured to burn a fuel mixed with the air compressed by the compressor (1) to produce a combustion gas; a turbine (3) configured to be driven by the combustion gas produced by the combustion device (2); a heat exchanger (5) configured to cause the fuel to be supplied to the combustion device (2) to be heated by cooling air drawn from the compressor (1) to be supplied to the turbine (3); a dispensing valve (6) configured to control a volume flow of cooling air; a first sensor (7, 8) that is configured to measure a state value related to the fuel; a second sensor (9, 10) configured to measure a state value related to the cooling air; and a control computer (11) which is configured to control an opening degree of the dispensing valve (6), wherein the control computer (11) stores data on reference values ​​and dead zones, which contain the corresponding set of reference values ​​for each of the measured values ​​of the first sensor (7, 8) and the second sensor (9, 10), and then, when a measured value measured by the first sensor (7, 8) and a measured value measured by the second sensor (9, 10) have changed so far from the corresponding reference value that they fall out of the corresponding dead zone, controls the dispensing valve (6) in such a way that the changed measured values ​​are brought close to the corresponding reference values. [2] Gas turbine (100) according to claim 1, wherein the state value relating to the fuel includes a fuel volume flow rate and / or a fuel temperature and / or an opening degree of a volume flow control valve configured to control the fuel volume flow rate. [3] Gas turbine (100) according to claim 1, wherein the state value relating to the cooling air includes a cooling air volume flow rate and / or a cooling air temperature and / or an opening degree of the tap valve (6). [4] Method for controlling a bleed air volume for a gas turbine (100) comprising: a compressor (1) configured to compress air, a combustion device (2) configured to burn a fuel mixed with the air compressed by the compressor (1) to produce a combustion gas, a turbine (3) configured to be driven by the combustion gas generated by the combustion device (2), a heat exchanger (5) configured to cause the fuel to be supplied to the combustion device (2) to be heated by heat exchange between the fuel and cooling air drawn from the compressor (1), and a dispensing valve (6) configured to control a volume flow of cooling air, the method comprising the following: Determine in advance data on reference values ​​and dead zones that include the corresponding set of reference values ​​for both a state value related to the fuel and a state value related to the cooling air, and Operating the dispensing valve (6) in such a way that a state value that has changed is brought close to the corresponding reference value when the state value relating to the fuel and the state value relating to the cooling air have changed so far from the corresponding reference value that they fall out of the corresponding dead zone.

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