JP3939368B2 - Method for adjusting air flow rate adjuster in gas turbine control - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a combustion control method for a gas turbine, and more particularly to a combustion control method for a gas turbine having a premixed combustion type combustor.
[0002]
[Prior art]
First, a general structure of a gas turbine having a premixed combustion type combustor will be described with reference to FIGS. FIG. 9 is a side view of a gas turbine having a premixed combustion type combustor, and FIG. 10 is an explanatory view of the main part of the gas turbine.
[0003]
As shown in FIG. 9, a plurality of combustors 35 are arranged adjacent to the compressor 48 in the circumferential direction of the gas turbine. The combustion gas generated in the combustor 35 is exhausted as exhaust gas 9 through the exhaust part 2 after rotating the turbine provided in the turbine part 47. The temperature of the exhaust gas 9 is measured by a plurality of temperature sensors 11-1 and 11-7 arranged in the circumferential direction of the gas turbine.
[0004]
Further, as shown in FIG. 10, the combustor 35 is located between the first stage combustion chamber 36, the second stage combustion chamber 3, and the first stage combustion chamber 36 and the second stage combustion chamber 3. A swirler 4 provided on the upstream side of the combustion chamber 3, a fuel nozzle 37 provided adjacent to the swirler 4, and an air flow rate adjuster 5 are provided. Here, the swirler 4 premixes fuel and air.
[0005]
Next, the operation of the gas turbine will be described. Fuel 6 is supplied from the fuel nozzle 37 to the swirler 4, and compressed air 7 for combustion is supplied from the compressor 48 to the swirler 4, and the fuel 6 and air 7 are premixed by the swirler 4 and pre- The mixed fuel 6 and air 7 are burned in the second stage combustion chamber 3.
[0006]
The combustion gas 8 generated in the second stage combustion chamber 3 flows into the turbine 1, drives the turbine 1 and the compressor 48, and then is discharged as exhaust gas 9. In addition, the turbine 1 and the compressor 48 are connected so that the respective shaft centers are on the same straight line.
[0007]
In the operation of the gas turbine, the ratio of the flow rate of the fuel 6 to the flow rate of the air 7 in the swirler 4, that is, the fuel-air ratio (= fuel amount / air) so that a high output can be efficiently obtained and the NOx value becomes low. Amount) need to be adjusted.
[0008]
FIG. 11 is a relationship diagram between the fuel-air ratio and the NOx concentration or CO concentration. In a premixed state, there is a so-called low NOx fuel-air ratio range 49 in which both the NOx concentration and the CO concentration are low. Therefore, if the fuel / air ratio can be adjusted to be within the low NOx fuel / air ratio range 49, the gas turbine can be operated at low NOx.
[0009]
Hereinafter, a control device that is a criterion for achieving such operation will be described with reference to FIG. FIG. 12 is a block diagram of a conventional gas turbine combustion control system.
[0010]
The controller 10 is installed so that the fuel-air ratio between the fuel 6 and the air 7 supplied to the swirler 4 can be set within the low NOx fuel-air ratio range 49 (see FIG. 11). A fuel command signal 13 for receiving a temperature signal detected from each of the temperature sensors 11-1 to 11-13, that is, a temperature output signal 12, calculating an average temperature of these temperatures and commanding increase / decrease in the flow rate of the fuel 6. Are output to the fuel flow rate adjuster 14 and the function generator 15 for air flow rate adjustment, respectively.
[0011]
The fuel flow rate adjuster 14 increases and decreases the supply flow rate of the fuel 6 from the fuel nozzle 37 (see FIG. 10) to the swirler 4 based on the fuel command signal 13 and adjusts the flow rate. That is, since the flow rate of the air 7 with respect to the flow rate of the fuel 6 is determined from the relationship of the low NOx fuel / air ratio range 49, the opening degree of the air flow rate adjuster 5 is determined by the opening degree command signal 16 from the function generator 15 based on this. And the supply flow rate of the air 7 from the compressor 48 (see FIG. 10) to the swirler 4 is increased or decreased.
[0012]
FIG. 13 is a right side view of FIG. The number of temperature sensors such as thermocouples is equal to or greater than the number of combustors 35 (see FIG. 10), for example, as shown in FIG. It arrange | positions at equal intervals in the circumferential direction. That is, the 13 temperature sensors 11-1 to 11-13 each measure the temperature of the exhaust gas 9 (see FIG. 10) discharged from the exhaust section 2, and the temperature output signal 12 (see FIG. 12) is controlled by the controller. 10 (see FIG. 12).
[0013]
FIG. 14 is a relationship diagram between the temperature sensor and the exhaust gas temperature. For example, when the exhaust gas temperature is normal as shown in the line 50 or when there is a partial decrease as shown in the line 51, the 13 temperature sensors 11-1 to 11-13 are The temperature output signals 12 corresponding to the exhaust gas temperatures are output to the controller 10, respectively.
[0014]
Next, the operation of the above-described gas turbine combustion control apparatus will be described with reference to FIG. A fuel command signal 13 corresponding to the load is output from the controller 10 to the fuel flow rate adjuster 14 and the function generator 15. The flow rate of the fuel 6 is adjusted by the fuel flow rate adjuster 14 based on the fuel command signal 13, and then supplied from the fuel nozzle 37 (see FIG. 10) to the swirler 4. On the other hand, the opening command signal 16 is output to the air flow rate adjuster 5 from the function generator 15 that has received the fuel command signal 13.
[0015]
By adjusting the opening degree of the air flow rate adjuster 5 based on the opening degree command signal 16, the flow rate of the air 7 is adjusted and supplied from the air flow rate adjuster 5 to the swirler 4. The fuel 6 and air 7 supplied to the swirler 4 are premixed within a low NOx fuel-air ratio range 49 (see FIG. 11) and at a constant fuel-air ratio set by the controller 10, and are subjected to second stage combustion. Combustion is performed in the chamber 3 in a low NOx combustion state, and combustion gas 8 is generated. The combustion gas 8 flows into the turbine 1 and drives the turbine 1 and the compressor 48 (see FIG. 10), and then is discharged from the exhaust unit 2 as the exhaust gas 9.
[0016]
Further, the 13 temperature sensors 11-1 to 11-13 measure the temperature of the exhaust gas 9 in the exhaust section 2, and the measured temperature output signal 12 of each exhaust gas 9 is output to the controller 10. . The controller 10 calculates the median value of the temperature output signals 12 from the 13 temperature sensors 11-1 to 11-13, and outputs the fuel command signal 13 based on the median value. Is adjusted to be within the low NOx fuel-air ratio range 49 (see FIG. 11).
[0017]
Here, the air flow rate adjusters 5 are respectively installed over the total number of the plurality of combustors 35 (see FIG. 10), and the opening adjustments of the air flow rate adjusters 5 are performed all at once or individually. It is configured to be able to do. As described above, the air flow rate adjuster 5 is provided in order to suppress the NOx to a predetermined amount with respect to the output of the gas turbine and to keep the combustion state of the plurality of combustors 35 in good condition. It is set to adapt to the characteristics.
[0018]
[Problems to be solved by the invention]
However, each of the plurality of combustors of the gas turbine has individual differences in the manufacturing process, and the deterioration and wear of parts over time of the combustor differ, so that the combustion stability varies. Furthermore, by arranging a plurality of combustors in the circumferential direction, a drift occurs in the combustion air, and the combustion stability varies. In addition, the combustion stability varies slightly depending on the temperature and humidity of the combustion air, and the amount of heat generated by the fuel and changes in the components.
[0019]
Therefore, it is important to adjust the air flow regulator in consideration of the individual difference of each combustor during trial operation or confirmation operation after periodic inspection so that operation with a stable combustion state with a low NOx value is possible. Become. However, in the conventional technique, the adjustment of the air flow rate adjuster changes the set value of the function generator of the air flow rate adjuster individually each time, and therefore requires a lot of labor and time.
[0020]
An object of the present invention is to provide a combustion control method for a gas turbine that eliminates the disadvantages of the prior art and enables the air flow regulator to be adjusted in a short time and efficiently.
[0021]
[Means for Solving the Problems]
(1) In a combustion control method for a gas turbine, which is a premixed combustion method and has a combustor equipped with an air flow rate adjuster for adjusting the amount of air flowing into the premixing section, the amount of air flowing into the premixing section is , To be able to change arbitrarily manually.
[0022]
(2) In (1), an adder capable of adding a bias signal for changing the opening is provided to the opening command signal for adjusting the air flow rate in the air flow adjuster so that the adder can be operated manually.
[0023]
(3) In (1), the influencing factors related to the combustion of the gas turbine are constantly monitored, and the manual operation of the amount of air flowing into the premixing section is excessive, causing an abnormality that hinders the operation of the gas turbine. If so, the air flow regulator can be immediately and automatically activated in a direction that stabilizes the combustion of the gas turbine.
[0024]
[Action]
In the present invention, an adder capable of manually adding a bias signal to the opening command signal to the air flow rate adjuster output from the function generator in response to the signal from the controller is provided. Or, while measuring the influence factors related to each characteristic of the combustor, the opening command signal can be adjusted manually to change the opening of the air flow adjuster, so the air flow adjuster can be adjusted easily can do.
[0025]
In addition, two adders are provided, and the opening command signal can be adjusted manually by a plurality of combustors. It can be adjusted well.
[0026]
Furthermore, even when combustion becomes unstable due to an excessive change in the opening command signal by manual operation, this unstable state can be captured immediately by constantly measuring influencing factors such as temperature sensors. Since the opening degree of the air flow adjuster can be automatically adjusted so as to shift to the stable combustion side, the air flow adjuster can always be adjusted safely and reliably.
[0027]
That is, in the present invention, the adjustment of the air flow adjuster corresponding to the variation in the combustion stability of the combustor due to individual differences of the combustor, etc. is performed safely and reliably so that the combustion instability does not occur efficiently in a short time. Can be implemented.
[0028]
【Example】
An embodiment of the present invention will be described with reference to FIGS. 1 is a block diagram of a gas turbine combustion control system of this embodiment, FIG. 2 is a longitudinal sectional view of a combustor of this embodiment, FIG. 3 is a partially enlarged view of FIG. 2, and FIG. 4 is an individual combustion in this embodiment. FIG. 5 is a state diagram of input influence factors of FIG. 4, FIG. 6 is a logic diagram of influence factors input of all the combustors in this embodiment, and FIG. 7 is an input influence factor of FIG. FIG. 8 is a logic diagram of another influence factor input in this embodiment. In addition, the same code | symbol is attached | subjected to the code | symbol of these figures, and the same part as FIGS.
[0029]
In FIG. 1, an influencing factor 17 is a factor that affects the unstable combustion of each combustor 35 (see FIG. 10). The influencing factor 17 includes the temperature of the exhaust gas 9 in the exhaust section 2 and the second stage combustion. The temperature of the combustion gas 8 in the chamber 3, the combustor metal temperature in the second stage combustion chamber 3 and the swirler 4, the NOx concentration or CO concentration in the combustion gas 8 and the exhaust gas 9, and the second stage combustion chamber 3 There is a combustion vibration.
[0030]
That is, when unstable combustion occurs in the combustor 35, it becomes particularly unstable at the swirler 4 part that requires fine adjustment of the fuel-air ratio, and the temperature of the exhaust gas 9 in the exhaust part 2 and in the second stage combustion chamber 3. The temperature of the combustion gas 8, the combustor metal temperature in the second stage combustion chamber 3 or the swirler 4, and the combustion vibration in the second stage combustion chamber 3 tend to fluctuate, and in the combustion gas 8 or the exhaust gas 9 There is a tendency for the NOx concentration to drop sharply or for the CO concentration to rise sharply. Therefore, by measuring the influencing factors 17 by the individual combustors 35, it is possible to reliably grasp unstable combustion of the individual combustors 35.
[0031]
The measuring instrument 18 measures the influence factor 17 and outputs a measuring instrument signal 19 according to the measured value. When the influence factor 17 is the temperature of the exhaust gas 9, the measuring instrument 18 is a temperature sensor 11-1 to 11-13 (see FIG. 13) disposed in the exhaust unit 2.
[0032]
When the influence factor 17 is the temperature of the combustion gas 8, the measuring device 18 is a temperature sensor 38 provided in the second stage combustion chamber 3 of each combustor 35 as shown in FIG. When the influence factor 17 is the combustor metal temperature, the measuring device 18 is provided with a temperature sensor 39 provided in the second stage combustion chamber 3 of each combustor 35 or the combustor metal of the swirler 4 as shown in FIG. It is. Note that thermocouples are used for the temperature sensors 38 and 39.
[0033]
Further, when the influential factor 17 is NOx concentration or CO concentration in the combustion gas 8 or the exhaust gas 9, the measuring device 18 burns into the second stage combustion chamber 3 of each combustor 35 as shown in FIG. The number of gas analyzers 40 is equal to or more than the number of the vessels 35. In addition, the gas analyzer 40 is similarly installed in the discharge unit 2 (see FIG. 9) (not shown). When the influence factor 17 is the combustion vibration of the second stage combustion chamber 3, the measuring instrument 18 is a strain gauge 41 provided in the second stage combustion chamber 3 of each combustor 35 as shown in FIG. .
[0034]
Thus, the temperature 18 of the combustion gas 8, the combustor metal temperature, the combustion gas 8 component, and the combustion vibration, which are the influencing factors 17 for the individual combustors 35, are measured by the measuring device 18 provided in each combustor 35. It can be measured by using it. On the other hand, the temperature of the exhaust gas 9 and the components of the exhaust gas 9 can be measured in the individual combustors 35 by the measuring device 18 provided in the same number or more as the number of the combustors 35.
[0035]
In FIG. 1, the monitor relay 20 compares a measured value based on the output signal 19 from the measuring instrument 18 with an allowable value 21, and when the measured value exceeds the allowable value 21, a bias amount reference according to the measured value. A value signal 22 is output.
[0036]
The monitor relay 20 is a monitor relay 42 as shown in FIG. 4 when the influence factor 17 is the temperature of the exhaust gas 9, the temperature of the combustion gas 8, the combustor metal temperature, or the combustion vibration. That is, the difference between the maximum value and the minimum value of the measuring instrument signal 19 (see FIG. 1) from the temperature sensors 11-1 to 11-13, 38, 39, or the strain gauge 41 is taken. As shown in FIG. 5, when the allowable value 21 is exceeded, the bias amount reference value signal 22 is output from the monitor relay 42.
[0037]
Moreover, in the above-mentioned case, the influence factor 17 to the combustor 35 is intended for each combustor 35, whereas FIG. 6 shows a case where it is expanded to the total number of combustors 35. In this case, the monitor relay 20 is the monitor relay 44.
[0038]
That is, the fluctuation ranges of a plurality of measuring instrument signals 19 input from the temperature sensors 11-1 to 11-13, 38, 39, or the strain gauge 41 are measured by all the combustors 35, and any one of these is allowed. When the value 21 is exceeded, the bias reference value signal 22 is output from the monitor relay 44. For example, as shown in FIG. 7, when the fluctuation range 45 of the measuring instrument signal 19 from the temperature sensor 11-1 exceeds the allowable value 21, the bias amount reference value signal 22 is output from the monitor relay 44.
[0039]
Further, when the influence factor 17 is NOx concentration or CO concentration, the monitor relay 20 is a monitor relay 46 as shown in FIG. That is, when the NOx concentration measured by the gas analyzer 40 is rapidly decreased or the CO concentration is rapidly increased and the value of the NOx concentration or the CO concentration exceeds the allowable value 21, the monitor relay 46 outputs a bias amount reference value signal 22.
[0040]
In FIG. 1, a function generator 23 is for calculating a bias coefficient, calculates a bias coefficient based on the fuel command signal 13 from the controller 10 in the reference control, and outputs a bias coefficient signal 24. The bias coefficient is calculated based on the fuel command signal 13, and the opening degree of the air flow rate adjuster 5, that is, the flow rate of the air 7 to be adjusted is set according to the flow rate of the fuel 6.
[0041]
The multiplier 25 receives the bias amount reference value signal 22 from the monitor relay 20 and the bias coefficient signal 24 from the function generator 23, multiplies the bias amount reference value and the bias coefficient, and biases the value to the bias value. This is output as a quantity signal 26.
[0042]
The adders 27, 29 and 30 are installed between the function generator 15 for the air flow rate adjuster and the air flow rate adjuster 5. Here, the adder 29 applies the same bias amount to the air flow rate adjusters 5 of all the combustors manually operated to the open amount of the air flow rate adjuster 5 based on the opening command signal 16 from the function generator 15. The adder 30 has a function of arbitrarily adding a bias amount to the individual air flow adjusters 5 of the plurality of combustors.
[0043]
The adder 27 has a function of adding a bias amount of the opening degree of the air flow rate adjuster 5 based on the bias amount signal 26 from the multiplier 25, and the sum of these bias amounts is the air flow rate adjuster. As the opening amount signal 28 of 5, the opening of the air flow rate adjuster 5 is adjusted in the opening direction or the closing direction.
[0044]
During the test operation of the gas turbine or the confirmation operation after periodic inspection, the premixed combustion method is adopted due to individual differences in the combustors 35 (see FIG. 10) or the influence of air drift to the plurality of combustors 35. In the combustion section, it is difficult to adjust the fuel-air ratio, and it is necessary to adjust it while driving.
[0045]
For adjustment, first, during load operation, the fuel command signal 13 is temporarily locked so as not to fluctuate, and then the adders 27, 29, and 30 are opened to the adders 27, 29, and 30 by manual operation. The bias is gradually increased in the increasing direction or decreasing direction, and the influence on the combustibility is grasped. That is, the state quantity change of the influence factor on the combustion is measured, and when the opening degree of the air flow rate adjuster 5 is operated in the increasing direction, if the situation exceeds the allowable value, the combustion is considered unstable and the addition is performed. A bias is applied by the device 27 so that the opening of the air flow rate adjuster 5 is in the closing direction to adjust the fuel / air ratio to be increased, and the combustion is shifted to the stable side.
[0046]
On the other hand, when the abnormality of the NOx concentration or the combustor metal temperature increases when the opening degree of the air flow adjuster 5 is operated in the decreasing direction, the air flow adjuster is added to the adder 27. A bias is applied so that the opening degree of 5 is in the opening direction, the fuel / air ratio is adjusted to be lowered, and the combustion is stabilized.
[0047]
The opening degree change by manual operation of the air flow rate adjuster 5 is performed by inputting an external bias signal 31 to the adder 29 when a bias is simultaneously applied to the air flow rate adjusters 5 of all the combustors. . Further, the opening degree change by manual operation of the air flow rate adjuster 5 of each combustor 35 is performed by arbitrarily inputting the bias signal 32 to the adder 30 only from the combustor as the target.
[0048]
By installing the adders 29 and 30, it is possible to apply a bias freely beyond the normal control. By these operations, the limits of combustion stability and combustion instability in the operating state for each combustor. Therefore, after the adjustment, the air flow rate adjuster 5 is set to the optimum reference opening.
[0049]
In addition, the bias signals 31 and 32 are added by adding manual bias switches 33 and 34, specifically by manual operation, in a stepwise manner or continuously at a certain ratio with respect to time. 29, 30 and the air flow rate adjuster 5 can be operated regardless of the normal control setting.
[0050]
【The invention's effect】
According to the present invention, in the premixed combustion part of the gas turbine combustor adopting the premixed combustion method, the adjustment of the combustion air during the operation of the gas turbine is manually performed for all the combustors. In addition, since a bias can be applied to the control command signal via an adder, the combustion control of the gas turbine can be performed efficiently in a short time.
[0051]
Also, for excessive adjustment of combustion air, it is possible to measure influential factors related to combustion, catch the case where the value of the influential factor exceeds the allowable value as abnormal combustion, and automatically shift to normal combustion. Therefore, the combustion air can be adjusted safely and reliably.
[Brief description of the drawings]
FIG. 1 is a block diagram of a gas turbine combustion control system according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a combustor according to an embodiment of the present invention.
FIG. 3 is a partially enlarged view of FIG. 2;
FIG. 4 is a logic diagram of influence factor input for individual combustors in one embodiment of the present invention.
FIG. 5 is a state diagram of input influence factors in FIG. 4;
FIG. 6 is a logic diagram of influence factor input of all the combustors in one embodiment of the present invention.
7 is a state diagram of input influence factors in FIG. 6. FIG.
FIG. 8 is a logic diagram of another influence factor input in one embodiment of the present invention.
FIG. 9 is a side view of a gas turbine having a premixed combustion type combustor.
FIG. 10 is an explanatory diagram of a main part of the gas turbine.
FIG. 11 is a relationship diagram between the fuel-air ratio and the NOx concentration or CO concentration.
FIG. 12 is a block diagram of a conventional gas turbine combustion control system.
13 is a right side view of FIG. 9. FIG.
FIG. 14 is a relationship diagram between a temperature sensor and an exhaust gas temperature.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Turbine, 2 ... Exhaust part, 3 ... Second stage combustion chamber, 4 ... Swirler, 5 ... Air flow regulator, 6 ... Fuel, 7 ... Air, 8 ... Combustion gas, 9 ... Exhaust gas, 10 ... Controller 11-1 to 11-13, 38, 39 ... temperature sensor, 12 ... temperature output signal, 13 ... fuel command signal, 14 ... fuel flow regulator, 15 ... function generator, 16 ... opening command signal, 17 ... Influencing factors, 18 ... measuring instrument, 19 ... measurement value signal, 20, 42, 44, 46 ... monitor relay, 21 ... tolerance, 22 ... bias amount reference value signal, 23 ... function generator, 24 ... bias coefficient signal, 25 ... multiplier, 26 ... bias amount signal, 27, 29, 30 ... adder, 28 ... opening amount signal, 31, 32 ... bias signal, 33, 34 ... manual bias switch, 35 ... combustor, 36 ... 1 stage Eye combustion chamber, 37 ... fuel nozzle, 40 ... gas analyzer, 1 ... strain gauges, 43, 45 ... change width, 47 ... turbine unit, 48 ... compressor, 49 ... low NOx fuel-air ratio range, 50, 51 ... diagram.

Claims (3)

A premixed combustion method, an adjustment method of an air flow rate adjuster in the control of a gas turbine having a plurality of combustors equipped with an air flow rate adjuster for adjusting the amount of air flowing into a premixing section,
Commissioning or leave temporarily locked so as not to change the fuel command signal when checking operation after periodic inspection, the commissioning or during the confirmation operation while changing the amount of air flowing into the premixed portion manually The air flow rate adjustment in the gas turbine control is characterized in that the limit of the combustion stability and the combustion instability in the operation state is determined, and based on this result, the reference opening degree of the air flow rate adjuster is set. How to adjust the machine . 2. An adder capable of adding a bias signal for changing an opening to an opening command signal for adjusting an air flow in the air flow adjuster so that the bias signal for changing the opening can be manually operated. Adjustment method of air flow rate adjuster in gas turbine control . Influencing factors related to the combustion of the gas turbine are constantly monitored, and when the operation of the amount of air flowing into the premixing section by the manual operation is excessive and an abnormality that hinders the operation of the gas turbine occurs, the gas The method of adjusting an air flow rate regulator in gas turbine control according to claim 1, wherein the air flow rate regulator can be automatically operated immediately in a direction in which the combustion of the turbine is stabilized.

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