Combustion monitoring and evaluation method for automatic combustion control system of f-class gas turbine

Abstract

This invention discloses a combustion monitoring and evaluation method for an automatic combustion adjustment system of an F-class gas turbine, comprising the following steps: Step 1, acquiring multiple Humming signals and multiple ACC signals from the gas turbine; Step 2, performing a filtering process on each Humming and ACC signal; Step 3, selecting and voting on the results of the first filtering based on set criteria to obtain qualified Humming and ACC signals; Step 4, performing a second filtering process on the qualified Humming and ACC signals to generate Humming control signals and ACC control signals; Step 5, combining the Humming control signals and ACC control signals with NO... X The corrected values ​​are analyzed to obtain combustion evaluation results. This invention can achieve advanced identification of combustion instability and can achieve NO... X Closed-loop control for emission reduction.

Description

Technical Field

[0001] This invention relates to the field of combustion monitoring and evaluation methods for gas turbines, specifically a combustion monitoring and evaluation method for an automatic combustion adjustment system of an F-class gas turbine. Background Technology

[0002] Currently, most heavy-duty gas turbines in operation in China use dry-type low-NOx burners suitable for natural gas fuel. Combustion adjustment technology is the most crucial control technology in gas turbine commissioning. Essentially, combustion adjustment involves adjusting the amount of fuel and air entering the combustion chamber to achieve stable and environmentally friendly combustion. Combustion adjustment is applied throughout all stages of the unit's operation, from ignition to full-load operation. Therefore, the quality of combustion adjustment directly affects the unit's thermal efficiency, the safe operation of combustion chamber components and thermal aisle components, and whether pollutant emissions meet standards.

[0003] Existing technologies, such as the automatic combustion control strategies of some F-class gas turbine original equipment manufacturers, use the ACC signal as a reference, analyzing the changing trends of the ACC signal value in different frequency bands to achieve automatic combustion control. This automatic combustion system uses combustion stability as the sole control objective and cannot effectively control NOx emissions. With some regions in China imposing more stringent NOx emission requirements on gas turbines, traditional combustion adjustment methods are no longer adequate to meet the new challenges. Summary of the Invention

[0004] This invention provides a combustion monitoring and evaluation method for an automatic combustion adjustment system of a Class F gas turbine, in order to solve the problem that existing combustion control strategies based on ACT signals cannot effectively control NOx emissions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The combustion monitoring and evaluation method for the automatic combustion adjustment system of a Class F gas turbine includes the following steps: Step 1: Acquire multiple Humming signals and multiple ACC signals generated during the combustion of the gas turbine; Step 2: Perform a filtering process on each Humming signal and each ACC signal obtained in Step 1 to remove interference signals and abrupt changes caused by interference; Step 3: Based on the signal reliability judgment criteria, select and vote on each Humming signal after the first filtering in Step 2, so as to select the Humming signal that best reflects the actual combustion pulsation from multiple Humming signals as the qualified Humming signal. Based on the same signal reliability judgment criteria, the ACC signals after the first filtering in step 2 are selected and voted on to select the ACC signal that best reflects the vibration of the combustion chamber cylinder block from multiple ACC signals as the qualified ACC signal. Step 4: Perform secondary filtering on the qualified Humming signal and qualified ACC signal obtained in Step 3 to smooth the Humming signal and ACC signal after voting, thereby generating the Humming control signal and ACC control signal respectively. Step 5: Combine the Humming control signal, ACC control signal, and NO signal obtained in Step 4 with the signal obtained during gas turbine operation. X The correction values ​​are compared with their corresponding threshold values ​​to obtain the combustion evaluation results of the gas turbine.

[0006] Furthermore, in step 2, a filtering algorithm based on the principle of inertial elements is used during the first filtering process.

[0007] Furthermore, in step 2, when the filtering algorithm based on the inertial link performs a filtering process, a dynamic filtering time constant is used to retain the sudden signal caused by combustion instability and remove the sudden signal caused by interference. The selection of the dynamic filtering time is calculated based on the rate of change and amplitude of the corresponding signal.

[0008] Furthermore, in step 3, when selecting a qualified signal from multiple Humming signals or ACC signals, if all signals are deemed qualified, the median value is selected as the qualified signal after voting; if there are only two qualified signals, the average of the two qualified signals is selected as the qualified signal after voting; if there is only one qualified signal, this qualified signal is selected as the specific value as the qualified signal after voting.

[0009] Furthermore, in step 4, a secondary filtering process is performed using an inertial link filtering algorithm based on dynamic time constant.

[0010] Furthermore, during the constant value analysis in step 5, if NO X If the correction value continuously exceeds the corresponding first threshold within a set time, and the Humming control signal and ACC control signal are respectively less than their corresponding first thresholds, then the analysis result indicates stable combustion and sufficient margin for NOx regulation. At this point, the NOx emission from the gas turbine can be activated. X The emission reduction control module adjusts NO in a closed loop according to a preset target value. X Emissions, up to NO X Emissions are adjusted to the preset target value.

[0011] Furthermore, during the setpoint analysis in step 5, if either the Humming control signal or the ACC control signal exceeds the corresponding second threshold, the analysis result indicates that combustion instability is occurring. At this point, the NO₂ level controlling the gas turbine combustion... X The emission reduction module exits control and activates the combustion stability control module to adjust combustion stability until the control signal that is greater than the corresponding second threshold returns to less than or equal to the corresponding second threshold.

[0012] Furthermore, during the constant value analysis in step 5, if NO X If the correction value remains below the corresponding third threshold for a set time, and the Humming control signal and ACC control signal are both below their respective third thresholds, then the analysis result indicates that combustion stability and NOx emissions meet the requirements, and there is a margin for improving the gas turbine's thermal performance. In this case, the gas turbine's NOx emissions will be... X The emission reduction control module exits and the performance optimization control module is activated, dynamically adjusting the gas turbine temperature control curve to improve the gas turbine's thermal performance.

[0013] This invention comprehensively considers the Humming signal, which reflects combustion pulsation, and the Acceleration Capacitor (ACC) signal, which reflects cylinder block vibration in the combustion chamber. It processes the Humming and ACC signals and then combines them with NO... X By performing setpoint analysis on the correction values ​​and their corresponding thresholds, it is possible to proactively identify combustion instability. Based on the setpoint analysis results, a multi-level gas turbine control strategy can be formed to achieve automatic combustion adjustment control of the gas turbine, enabling NO reduction under the premise of stable gas turbine combustion. X It enables closed-loop control for emission reduction and dynamic optimization of the thermal performance of gas turbine units. Attached Figure Description

[0014] Figure 1 This is a flowchart of the method according to an embodiment of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] like Figure 1 As shown in the figure, this embodiment discloses a combustion monitoring and evaluation method for an automatic combustion adjustment system of an F-class gas turbine, including the following steps: Step 1: Using a Humming sensor capable of measuring high-frequency changes in working fluid pressure within the combustion chamber and an ACC sensor capable of measuring high-frequency vibration signals in the combustion chamber cylinder block, multiple Humming signals and multiple ACC signals generated during combustion operation of the gas turbine are acquired. The Humming signal reflects the high-frequency pressure pulsation signal of the working fluid within the confined space of the combustion chamber, which typically reflects the "precursor" of combustion instability. The ACC signal, on the other hand, reflects the high-frequency vibration signal of the combustion chamber cylinder block caused by combustion instability, representing the "result" of combustion instability.

[0017] Since Humming and ACC signals are not reliable analog signals, their signal characteristics make them unsuitable for direct control. Therefore, this embodiment processes each Humming and ACC signal through subsequent steps to obtain control signals that meet the control requirements.

[0018] Step 2: Perform a filtering process on each Humming signal and each ACC signal obtained in Step 1 to remove interference signals and abrupt changes caused by interference.

[0019] In this embodiment, an inertial link filtering algorithm based on dynamic time constant is used in the first filtering process. This algorithm employs a dynamic filtering time constant to retain abrupt changes caused by combustion instability and eliminate abnormal abrupt changes caused by interference. The selection of the dynamic filtering time constant is calculated based on a function related to the rate of change and amplitude of the corresponding signal. Specifically, the dynamic filtering time constant is a function of the signal's rate of change and amplitude; a small time constant is used when the signal's rate of change is slow (or the signal amplitude is small); a large time constant is used when the rate of change is fast (or the signal changes significantly). The specific formula is as follows:

[0020] In the above formula: 1. and It is a constant 2. For signal reference value 3. Real-time value of the signal 4. Reference value for time constant Taking the filtering of the raw Humming signal as an example, assuming that the Humming signal changes rapidly (e.g., greater than 10 mbar / s) or its amplitude changes significantly (the absolute value of the deviation from the reference value is greater than 5 mbar), the time constant calculated according to the above formula... TThe time constant will increase (e.g., 10s). When the inertial link filtering algorithm with this time constant is used to filter the Humming signal, and according to the reliability judgment criterion, if the calculation result is within a reasonable threshold range, the signal is judged to be qualified; otherwise, the signal is judged to be unqualified. If the rate of change of the Humming signal is slow (e.g., less than 1mbar / s) or the amplitude change is small (e.g., <1mbar), then the calculated time constant will be... T It will become smaller (e.g., 2s).

[0021] The method for filtering the raw ACC signal is similar to that of Humming, only using different techniques. , , Constants.

[0022] Step 3: In this embodiment, a signal reliability judgment criterion is designed to select and vote on each Humming signal after the first filtering in Step 2, so as to select the Humming signal that best reflects the actual combustion pulsation from multiple Humming signals as the qualified Humming signal. The signal reliability judgment criterion includes, but is not limited to, the amplitude, rate, and reasonable upper and lower limits of signal change.

[0023] Based on the same signal reliability judgment criteria, the ACC signals after the first filtering in step 2 are selected and voted on to select the ACC signal that best reflects the vibration of the combustion chamber cylinder block from among the multiple ACC signals as the qualified ACC signal.

[0024] In this embodiment, when the Humming signal or ACC signal deviates significantly from the reference signal value, the change in amplitude is used as the criterion for judging signal reliability. Specifically, for example, when the Humming signal changes from 30 mbar to 100 mbar, the signal is judged to be unqualified.

[0025] In this embodiment, when the Humming signal or ACC signal changes rapidly, the rate is used as the criterion for judging the reliability of the signal. For example, when the ACC signal changes by more than 15 g / s, the signal is judged to be unqualified.

[0026] In this embodiment, when the reading of the Humming signal or the ACC signal exceeds the reasonable range, the reasonable upper and lower limits are used as the criteria for judging the reliability of the signal. For example, when the ACC is greater than 20g or the Humming is greater than 200mbar, or when the ACC and Humming readings are less than zero, the signal is judged to be unqualified.

[0027] When selecting a qualified signal from multiple Humming signals and ACC signals based on the signal reliability discrimination criteria through the above process, if multiple Humming signals or ACC signals are deemed qualified, the median value is selected as the corresponding qualified signal; if only two Humming signals or ACC signals are deemed qualified, the average value is selected as the qualified signal; if only one signal is qualified, the qualified Humming signal or ACC signal is selected as the specific qualified signal.

[0028] Step 4: Perform secondary filtering on the qualified Humming signal and qualified ACC signal obtained in Step 3 to smooth the qualified signals and meet the requirements of process control for their input signals. This generates Humming control signal and ACC control signal that can truly reflect the combustion pulsation and are smooth without sudden changes. In this embodiment, the secondary filtering uses the same inertial link filtering algorithm based on dynamic time constant as the primary filtering. The selection of the dynamic filtering time constant is the same as the principle of the primary filtering.

[0029] Step 5: Combine the Humming control signal, ACC control signal, and NO signal obtained in Step 4 with the signal obtained during gas turbine operation. X The correction values ​​are compared with their corresponding threshold values ​​to obtain the combustion evaluation results of the gas turbine.

[0030] The constant value analysis process is as follows: If NO X The correction value continuously exceeds the corresponding first threshold NOx_Setpoint1 (e.g., 30 mg / Nm³) within a set time (e.g., 30 seconds). 3 If the Humming control signal is less than the corresponding first threshold HumL1 and the ACC control signal is less than the corresponding first threshold ACCL1, then the analysis result indicates stable combustion and sufficient margin for NOx regulation. In this case, the NOx control of the gas turbine... X The emission reduction module adjusts NO in a closed loop according to the preset target value. X Emissions, up to NO X Emissions are adjusted to the preset target value.

[0031] If the Humming control signal is greater than the corresponding second threshold HumL2 or the ACC control signal is greater than the corresponding second threshold ACCL2, the analysis result indicates that combustion instability is occurring. In this case, the NO3-C of the gas turbine should be controlled. X Emission reduction module exit NO XThe emission reduction function activates the combustion stability control module to adjust combustion stability until the control signal (Humming control signal or ACC control signal) that is greater than the corresponding second threshold returns to less than or equal to the corresponding second threshold.

[0032] If NO X The correction value remains below the corresponding third threshold NOx_Setpoint3 (e.g., 27 mg / Nm³) for a set period of time. 3 If the Humming control signal is less than the corresponding third threshold HumL3 and the ACC control signal is less than the corresponding third threshold ACCL3, then the analysis result indicates that the combustion stability and NOx emissions meet the requirements, and there is a margin for improving the gas turbine's thermal performance. In this case, control the NOx emissions of the gas turbine. X Emission reduction module exit NO X The emission reduction function is activated, and the performance optimization module is controlled to increase the temperature before the first-stage stator blades of the gas turbine according to the gas turbine temperature control curve, while meeting the temperature tolerance range of the gas turbine unit's thermal passage components and NO. X While ensuring emissions compliance, maximize the thermal performance of the gas turbine.

[0033] In this embodiment, the Humming control signal, ACC control signal, and NO... X The correction values, corresponding to the first, second, and third thresholds, are selected based on the combustion pulsation characteristics, NOx emission characteristics, and thermodynamic performance of different units in the F-class gas turbine. That is, for each unit in the F-class gas turbine, the Humming control signal, ACC control signal, and NOx emission control signal are selected according to the actual operating conditions of that unit. X The specific values ​​of the first, second, and third thresholds corresponding to the correction value are used for value analysis.

[0034] Specifically, Humming control signal, ACC control signal, NO XThe first, second, and third thresholds corresponding to the correction values ​​are determined through combustion adjustment tests on specific units. Different setpoints may be used for different units, and the specific threshold values ​​are selected based on the specific combustion characteristics and equipment safety margins of the corresponding gas turbine unit. For example, for a certain 9F gas turbine unit in China, the combustion stability safety boundary of the unit was determined through combustion adjustment tests, and the selected first threshold group is [Humming < 28 mbar and ACC < 1.0 g]; the second threshold group is selected based on the unit's protection setpoint, which is usually required to be more stringent than the unit's protection setpoint to ensure that the protection action will not be triggered, so the selected second threshold group is [Humming > 43 mbar or ACC > 1.8 g]; the third threshold group is selected based on the unit's combustion stability margin and local pollutant emission limits, and the selected third threshold group for this unit is [Humming < 33 mbar and ACC < 1.8 g and NOx < 35 mg / m³]. 3 ].

[0035] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. These embodiments are merely descriptions of preferred embodiments and are not intended to limit the scope or concept of the invention. The specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. Such combinations, as long as they do not violate the spirit of the present invention, should also be considered as part of this disclosure. To avoid unnecessary repetition, the present invention will not further describe the various possible combinations.

[0036] This invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this invention and without departing from the design idea of ​​this invention, all modifications and improvements made by those skilled in the art to the technical solutions of this invention should fall within the protection scope of this invention. The technical content for which protection is sought in this invention has been fully described in the claims.

Claims

1. A method for monitoring and evaluating the combustion of an automatic combustion control system for a F-class gas turbine, characterized by, Includes the following steps: Step 1: Acquire multiple Humming signals and multiple ACC signals generated during the combustion of the gas turbine; Step 2: Perform a filtering process on each Humming signal and each ACC signal obtained in Step 1 to remove interference signals and abrupt changes caused by interference; Step 3: Based on the signal reliability judgment criteria, select and vote on each Humming signal after the first filtering in Step 2, and select the Humming signal that best reflects the actual combustion pulsation from multiple Humming signals as the qualified Humming signal; similarly, based on the signal reliability judgment criteria, select and vote on each ACC signal after the first filtering in Step 2, and select the ACC signal that best reflects the combustion chamber cylinder block vibration from multiple ACC signals as the qualified ACC signal; Step 4: Perform secondary filtering on the qualified Humming signal and qualified ACC signal obtained in Step 3 to smooth the Humming signal and ACC signal after voting, thereby generating the Humming control signal and ACC control signal respectively. Step 5, the Humming control signal, the ACC control signal and the NOx X correction value, and the threshold value corresponding to each correction value are analyzed to obtain the combustion evaluation result of the engine. When the value analysis in step 5, if NO X The correction value is continuously more than the corresponding first threshold value in the set time, and the Humming control signal and the ACC control signal are less than the corresponding first threshold value respectively, the analysis result is that the combustion is stable and has the margin of adjusting NO X The NO X Reduction control module of the engine is activated, and the NO X Emission amount is closed-loop adjusted according to the preset target value until the NO X Emission amount is adjusted to the preset target value. In the step 5 of the value analysis, if any one of the Humming control signal and the ACC control signal is greater than the corresponding second threshold value, the analysis result is that the combustion appears unstable signs, at this time the NO X The emission reduction module exits the control, and the combustion stability control module is activated to adjust the combustion stability until the control signal greater than the corresponding second threshold value returns to less than or equal to the corresponding second threshold value. When the value analysis in step 5, if NO X The correction value is less than the corresponding third threshold value for a set time, and the Humming control signal and the ACC control signal are less than the respective corresponding third threshold value, the analysis result is that the combustion stability and NO X The emissions meet the requirements, and have the margin to improve the thermal performance of the gas turbine, at this time the gas turbine NO X The emission reduction control module exits, and the performance optimization control module is activated, and the gas turbine temperature control curve is dynamically adjusted to improve the thermal performance of the gas turbine.

2. The method of claim 1, wherein the method is used for the F-class gas turbine automatic combustion control system. In step 2, the filtering process uses a filtering algorithm based on the principle of inertial elements.

3. The method of claim 1, wherein the method is used for the F-class gas turbine automatic combustion control system. In step 2, when the filtering algorithm based on the inertial link performs a filtering process, a dynamic filtering time constant is used to retain the sudden signal caused by combustion instability and remove the sudden signal caused by interference. The selection of the dynamic filtering time is calculated based on the rate of change and amplitude of the corresponding signal.

4. The method of claim 1, wherein the method is used for the F-class gas turbine automatic combustion control system. In step 3, when voting to select a qualified signal from multiple Humming signals or ACC signals, if all signals are deemed qualified, the median value is selected as the qualified signal after voting; if there are only two qualified signals, the average of the two qualified signals is selected as the qualified signal after voting; if there is only one qualified signal, this qualified signal is selected as the specific value as the qualified signal after voting.

5. The method of claim 1, wherein the method is used for the F-class gas turbine automatic combustion control system. In step 4, a secondary filtering process is performed using an inertial element filtering algorithm based on dynamic time constant.

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