Acoustic monitoring system and method for flow velocity of flue gas at inlet of combined cycle waste heat boiler

Abstract

The invention belongs to the field of acoustic speed measurement, and particularly relates to a combined cycle waste heat boiler inlet flue gas flow velocity acoustic monitoring system and method, and the system comprises a pneumatic sound source device which is used for generating a pneumatic sound wave signal and transmitting the pneumatic sound wave signal into a flue gas pipeline; the sensor system is used for collecting pneumatic sound wave signals sent by the pneumatic sound source device and obtaining downwind propagation sound wave signals and upwind propagation sound wave signals through the pneumatic sound wave signals; the pneumatic sound wave signal processing system is electrically connected with the sensor system and is used for calculating the gas flow rate on a corresponding path according to the downwind propagation sound wave signal and the upwind propagation sound wave signal collected by the sensor system and displaying a measurement result; the sensor system is provided with one transmitter and two receivers, the propagation velocities of sound in downstream and countercurrent can be obtained at the same time, the influence of sound velocity change on a time difference method is avoided by using the principle that the sound velocity is different in downstream and countercurrent conditions, and the requirement for measuring the outlet flow velocity of the gas turbine is met.

Description

Technical Field

[0001] The invention belongs to the field of acoustic velocity measurement, and in particular relates to a system and method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler. Background Art

[0002] Gas flow rate measurement is mainly used in the industrial field, most typically in power plants. Gas turbines use natural gas as fuel, which reduces SO 2 The emission of pollutants such as NOX has the advantages of high efficiency, low emission and less environmental pollution, which has become a major trend in the development of the industry. The gas turbine and the waste heat boiler are connected through a transition flue. The gas turbine flue gas flow rate is crucial to the safe operation and heat exchange of the waste heat boiler. At present, the flow rate and flow field of the flue gas are mainly obtained through simulation, which has low accuracy and poor effect.

[0003] At present, the methods for measuring flow velocity are divided into non-contact measurement and contact measurement. Contact measurement mainly includes devices such as Pitot tube, Venturi tube, hot wire anemometer, etc., and non-contact measurement includes methods such as acoustic optics. In view of the high temperature, high back noise and high pressure of the gas turbine on-site environment, there is currently no method that can accurately measure the flue gas flow velocity. The contact measurement method is easy to be damaged in this environment, and the optical method has the problem of easy contamination of the lens and other reasons, and cannot accurately obtain the gas flow velocity. Based on this situation, this application proposes a combined cycle waste heat boiler inlet flue gas flow velocity acoustic monitoring system and method to achieve online measurement of flue gas flow velocity. Summary of the invention

[0004] The object of the present invention is to provide a combined cycle waste heat boiler inlet flue gas flow velocity acoustic monitoring system and method, so as to solve the technical problem that the non-contact measurement of flue gas flow velocity in the prior art cannot accurately obtain the gas flow velocity.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present application discloses a combined cycle waste heat boiler inlet flue gas velocity acoustic monitoring system, comprising: A pneumatic sound source device is used to generate a pneumatic sound wave signal and transmit the pneumatic sound wave signal to the flue gas duct; The sensor system is used to collect the pneumatic sound wave signal emitted by the pneumatic sound source device, and obtain the downwind propagation sound wave signal and the headwind propagation sound wave signal; The pneumatic acoustic wave signal processing system is electrically connected to the sensor system and is used to calculate the gas flow rate on the corresponding path based on the downwind acoustic wave signal and the headwind acoustic wave signal collected by the sensor system, and display the measurement results.

[0006] Preferably, the pneumatic sound source device includes a sound wave modulator and a variable frequency speed regulating motor, including the sound wave modulator and the variable frequency speed regulating motor being connected, and the sound wave modulator is sequentially connected with a gradually diverging nozzle and a sound waveguide, and the sound wave modulator transmits the pneumatic sound wave signal to the flue gas duct through the gradually diverging nozzle and the sound waveguide.

[0007] Preferably, the sensor system includes a sound-emitting sensor, a first receiving sensor and a second receiving sensor; the sound-emitting sensor is arranged on the sound waveguide tube, and the first receiving sensor and the second receiving sensor are arranged on the side wall of the gradually expanding section of the smoke duct on the opposite side of the sound-emitting sensor and are dispersed on both sides of the sound-emitting sensor, and a resonance cavity is installed between the first receiving sensor and the second receiving sensor and the side wall of the smoke duct, which is used to collect the downwind propagation sound wave signal and the headwind propagation sound wave signal emitted by the pneumatic sound source device; the sound-emitting sensor, the first receiving sensor and the second receiving sensor are all electrically connected to the sound wave signal processing system.

[0008] Preferably, the pneumatic acoustic wave signal processing system comprises: A filtering unit, used for filtering the pneumatic acoustic wave signals collected by the sensor system using high-order cumulative quantities to obtain filtered signals; A cross-correlation unit, used to obtain a cross-correlation function between filtered signals by adopting a generalized cross-correlation delay estimation method; and determine a delay time according to the cross-correlation function; The gas flow rate calculation unit is used to calculate the gas flow rate according to the delay time and display the measurement result.

[0009] In a second aspect, the present application discloses a method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler, comprising: The pneumatic sound source device generates a pneumatic sound wave signal; the sensor system collects the pneumatic sound wave signal emitted by the pneumatic sound source device; The acoustic wave signal processing system uses high-order cumulants to filter the pneumatic acoustic wave signals collected by the sensor system to obtain filtered signals; A generalized cross-correlation delay estimation method is used to obtain a cross-correlation function between the filtered signals; and a delay time is determined according to the cross-correlation function. Calculate the gas flow rate according to the delay time and display the calculation results.

[0010] Preferably, the sensor system comprises a sound-emitting sensor, a first receiving sensor and a second receiving sensor; The time delay from the sound sensor to the first receiving sensor is the delay time The time delay from the sound sensor to the second receiving sensor is the delay time , then the signals received by the sound sensor and the first receiving sensor are:

[0011]

[0012] Signal , Its third-order autocumulant and third-order cross-cumulant are defined as:

[0013]

[0014] The above formula uses the additivity of high-order cumulants and the property that the fourth-order cumulant of Gaussian noise is zero to simplify it to:

[0015]

[0016] Let τ2,τ3 be zero, and get a one-dimensional slice of the fourth-order cumulant:

[0017]

[0018] Replace τ1 with t to obtain the filtered signal of the sound sensor , the filtered signal of the first receiving sensor ; Similarly, the filtered signal of the second receiving sensor is obtained .

[0019] Preferably, the generalized cross-correlation delay estimation method is used to obtain the cross-correlation function between the filtered signals; and the delay time is determined according to the cross-correlation function, specifically including: The generalized cross-correlation expression is:

[0020] According to the Wiener-Khinchin theorem, the inverse Fourier transform of the cross-power spectrum function is the cross-correlation function, and the above formula is transformed into:

[0021] is the mutual power spectrum of the sound sensor and the first receiving sensor after high-order cumulant filtering; Filtered signal from acoustic sensor and the filtered signal of the first receiving sensor The cross power spectrum of is expressed as:

[0022] is the cross power spectrum of the sound sensor 1 and the first receiving sensor 2; Based on the PHAT weighting function of phase transformation, the generalized cross-correlation function is obtained:

[0023]

[0024] The independent variable corresponding to the peak point of the generalized cross-correlation function That is, the delay time from the sound sensor to the first receiving sensor ; Similarly, the delay time from the sound sensor to the second receiving sensor is obtained .

[0025] Preferably, the gas flow rate is calculated according to the delay time as follows: If the transmission from the sound sensor to the first receiving sensor is downstream, and the transmission from the sound sensor to the second receiving sensor is upstream, then:

[0026] In the formula, Indicates gas flow rate; Indicates the distance from the sound sensor to the first receiving sensor; Indicates the distance from the sound sensor to the second receiving sensor; Indicates the delay time from the sound sensor to the first receiving sensor, that is, the downstream delay time, Indicates the time delay from the sound sensor to the second receiving sensor, that is, the backflow delay time; It is the angle between the sound propagation direction and the gas flow direction.

[0027] In a third aspect, the present application discloses an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for acoustically monitoring the inlet flue gas flow velocity of a combined cycle waste heat boiler as described in any one of the above items when executing the computer program.

[0028] In a fourth aspect, the present application discloses a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the method for acoustically monitoring the inlet flue gas flow velocity of a combined cycle waste heat boiler as described in any one of the above items are implemented.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1) In the measurement state, the test process will not affect the original flow field inside the pipeline. The use of pneumatic sound source to generate sound overcomes the problem of low sound power. The sensor system simultaneously obtains and measures the downwind sound wave signal and the upwind sound wave signal. The gas flow rate is calculated based on the downwind sound wave signal and the upwind sound wave signal, and the calculation result is more accurate. 2) The sound-generating end uses a pneumatic sound source device, including a sound wave modulator and a variable frequency speed regulating motor. There is a gradually expanding nozzle behind the sound wave modulator. When working, the variable frequency speed regulating motor drives the moving disk shaft inside the sound wave modulator to rotate, continuously cutting off the air source channel, and the reciprocating cycle causes air flow disturbance, thereby forming continuous high-intensity sound pressure level sound wave energy; 3) The sensor system is set up with one transmitter and two receivers. This arrangement can simultaneously obtain the propagation speed of sound in the downstream and upstream, avoiding the influence of the sound speed change caused by temperature change on the time difference method.

[0030] 4) The receiving end arranges a resonant cavity and combines high-order cumulants to filter the background noise, effectively solving the influence of background noise on the delay result, and adopts the PHAT weighting function to make the result more accurate. The present invention uses the principle that the speed of sound is different in the case of downstream and upstream flow, and obtains the flow rate of the gas by measuring the speed of sound in the downstream and upstream flow, so as to meet the demand for gas turbine outlet flow rate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a schematic diagram of the system structure of the present invention; Figure 2 is a flow chart of the method of the present invention; Figure 3 It is a schematic diagram of the resonant cavity structure of the present invention; Figure 4 It is the cross-correlation function diagram of the present invention.

[0033] Wherein: 1-sensor 1; 2-sensor 2; 3-sensor 3; 4-acoustic waveguide; 5-aerodynamic sound source gradually expanding nozzle; 6-resonant cavity; A-aerodynamic sound wave signal processing system. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0037] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0038] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The present invention is further described in detail below in conjunction with the accompanying drawings: The purpose of the present invention is to overcome the disadvantage of the prior art that online measurement cannot be achieved, and to provide an acoustic monitoring system for the inlet flue gas velocity of a combined cycle waste heat boiler that is easy to operate, highly reliable and highly accurate. Figure 1 , the system comprises: Pneumatic sound source device: The pneumatic sound source device is installed on the side wall of the expansion section from the gas turbine outlet to the waste heat boiler inlet, and is used to generate pneumatic sound wave signals and transmit the pneumatic sound wave signals to the flue gas duct; Sensor system: The sensor system is installed on the side wall of the expansion section from the gas turbine outlet to the waste heat boiler inlet, and is used to collect the sound wave signal of the aerodynamic sound source and obtain the sound wave signal propagating along the wind and against the wind; Acoustic signal processing system: used to calculate the gas flow rate on the path corresponding to the acoustic signal based on the acoustic signal collected by the sensor system, and display the measurement results.

[0041] The use of a pneumatic sound source overcomes the problem of low sound power; the sensor system simultaneously obtains and measures the sound wave signal propagating along the wind and the sound wave signal propagating against the wind; the gas flow rate is calculated based on the sound wave signal propagating along the wind and the sound wave signal propagating against the wind; the propagation speed of sound in the downstream and upstream is obtained at the same time, avoiding the influence of the sound speed change caused by temperature change on the time difference method, and the calculation result is more accurate.

[0042] In some embodiments, the pneumatic sound source device includes a sound wave modulator and a variable frequency speed regulating motor, including the sound wave modulator and the variable frequency speed regulating motor are connected, the sound wave modulator is connected with a gradually expanding nozzle 5 and a sound waveguide 4 in sequence, and the sound wave modulator transmits the pneumatic sound wave signal to the flue gas duct through the gradually expanding nozzle 5 and the sound waveguide 4. The sound-generating end uses a pneumatic sound source device, including a sound wave modulator and a variable frequency speed regulating motor, and there is a gradually expanding nozzle behind the sound wave modulator. When working, the variable frequency speed regulating motor drives the moving disk shaft inside the sound wave modulator to rotate, continuously cutting off the channel of the air source, and cyclically causing airflow disturbance, thereby forming continuous high-intensity sound pressure level sound wave energy.

[0043] In some embodiments, the sensor system includes a sound sensor 1, a first receiving sensor 2 and a second receiving sensor 3; the sound sensor 1 is arranged on the sound waveguide 4, the first receiving sensor 2 and the second receiving sensor 3 are arranged on the side wall of the smoke duct on the opposite side of the sound sensor 1, and a resonance cavity 6 is installed between the first receiving sensor 2 and the second receiving sensor 3 and the side wall of the smoke duct, see Figure 3, used to collect the sound wave signals propagating along the wind and against the wind emitted by the pneumatic sound source device; the sound sensor 1, the first receiving sensor 2 and the second receiving sensor 3 are all electrically connected to the sound wave signal processing system. The sensor system includes a sound sensor installed at the sound waveguide and two receiving sound wave sensors installed on the opposite wall. The sensor uses a piezoelectric sensor, which is resistant to high temperature and has accurate measurement. The sound sensor is installed on the sound waveguide 4, and the receiving sensor is installed on the side wall of the flue gas duct of the opposite expansion section, and is dispersed on both sides of the sound sensor. The sound waves propagating along and against the flow are measured at the same time, and the result is more accurate; a one-transmitter and two-receiver arrangement is adopted, that is, one sound sensor and two receiving sensors, the sound sensor is arranged behind the pneumatic sound source, and the receiving sensor is arranged on the opposite furnace wall, and the sound velocity of the upstream and downstream is measured at the same time, and the gas flow rate is obtained by the time difference method. One of the important factors affecting the accuracy of sound wave velocity measurement is background noise. Since the receiving sensor is far from the sound source, the sound sensor is less affected by the background noise, while the receiving sensor is more affected by the background noise. Based on this, it is proposed to install a resonant cavity 6 before the receiving sensor to eliminate the noise. The resonant cavity 6 is a kind of reactive silencer. When the sound wave enters the resonator, only the sound wave near the natural frequency can enter the cavity through the diameter tube and reflect back and forth in the cavity, thereby achieving the effect of noise elimination. The receiving sensor is arranged after the diameter tube. The sound enters the resonant cavity to vibrate the diameter tube diaphragm, so that the piezoelectric sensor at the receiving end receives the sound wave signal.

[0044] In some embodiments, the pneumatic acoustic wave signal processing system comprises: A filtering unit, used for filtering the pneumatic acoustic wave signals collected by the sensor system using high-order cumulative quantities to obtain filtered signals; A cross-correlation unit, used to obtain a cross-correlation function between filtered signals by adopting a generalized cross-correlation delay estimation method; and determine a delay time according to the cross-correlation function; The gas flow rate calculation unit is used to calculate the gas flow rate according to the delay time and display the measurement result.

[0045] First, it is necessary to pre-process the signal received by the sensor and filter the received signal. Due to the complex structure and large size of modern power plant boilers, the acoustic signal will be significantly attenuated when it propagates in high-temperature flue gas for a long time; in addition, due to the large amount of hot background noise in the boiler, such as the combustion noise in the furnace, the jet noise of the burner and other mechanical noise, it will have a strong interference on the measurement result of the acoustic delay time; and due to the limitation of the process level, it is not possible to improve the measurement accuracy of the acoustic flight time by simply increasing the power of the sound device. Therefore, it is proposed to use high-order cumulants to filter the received sound signal. Then, the cross-correlation function between the filtered signals is obtained by the generalized cross-correlation algorithm; the delay time is determined according to the cross-correlation function, and the gas flow rate is obtained by measuring the sound velocity of the upstream and downstream by using the principle that the sound velocity is different in the downstream and upstream conditions, so as to meet the demand for gas turbine outlet flow velocity measurement.

[0046] The present application also discloses a combined cycle waste heat boiler inlet flue gas velocity acoustic monitoring method, see Figure 2 , the method comprising: S1: The pneumatic sound source device generates a pneumatic sound wave signal; the sensor system collects the pneumatic sound wave signal emitted by the pneumatic sound source device; S2: The acoustic wave signal processing system uses high-order cumulants to filter the pneumatic acoustic wave signals collected by the sensor system to obtain filtered signals; the filtering process effectively solves the influence of background noise on the time delay results; S3: using a generalized cross-correlation delay estimation method to obtain a cross-correlation function between the filtered signals; determining the delay time according to the cross-correlation function; S4: Calculate the gas flow rate according to the time delay and display the calculation results; use the principle that the speed of sound is different in the downstream and upstream conditions, and obtain the gas flow rate by measuring the speed of sound in the upstream and downstream conditions to meet the demand for gas turbine outlet flow rate measurement.

[0047] Furthermore, in some embodiments, the sensor system includes a sound sensor 1, a first receiving sensor 2, and a second receiving sensor 3; the time delay from the sound sensor 1 to the first receiving sensor 2 is the delay time The time delay from the sound sensor 1 to the second receiving sensor 3 is the delay time ; The signals received by the sound sensor 1 and the first receiving sensor 2 are respectively:

[0048]

[0049] Signal , Its third-order autocumulant and third-order cross-cumulant are defined as:

[0050]

[0051] The above formula uses the additivity of high-order cumulants and the property that the fourth-order cumulant of Gaussian noise is zero to simplify it to:

[0052]

[0053] Let τ2,τ3 be zero, and get a one-dimensional slice of the fourth-order cumulant:

[0054]

[0055] Replace τ1 with t to obtain the filtered signal of sound sensor 1 , the first receiving sensor 2 filtered signal Similarly, the filtered signal of the second receiving sensor 3 is obtained .

[0056] In some embodiments, the generalized cross-correlation delay estimation method is used to obtain the cross-correlation function between the filtered signals; and the delay time is determined according to the cross-correlation function, specifically including: The generalized cross-correlation expression is:

[0057] According to the Wiener-Khinchin theorem, the inverse Fourier transform of the cross-power spectrum function is the cross-correlation function, and the above formula is transformed into:

[0058] is the mutual power spectrum of the sound sensor 1 and the first receiving sensor 2 after high-order cumulant filtering; Filtered signal of sound sensor 1 and the filtered signal of the first receiving sensor 2 The cross power spectrum of is expressed as:

[0059] is the cross power spectrum of the sound sensor 1 and the first receiving sensor 2; Based on the PHAT weighting function of phase transformation, the generalized cross-correlation function is obtained:

[0060]

[0061] See also Figure 4 , the independent variable corresponding to the peak point of the generalized cross-correlation function That is, the delay time from the sound sensor 1 to the first receiving sensor 2 Similarly, the delay time from the sound sensor 1 to the second receiving sensor 3 is obtained .

[0062] In some embodiments, the gas flow rate is calculated according to the delay time as follows: If the transmission from the sound sensor 1 to the first receiving sensor 2 is downstream, and the transmission from the sound sensor 1 to the second receiving sensor 3 is upstream, then:

[0063] In the formula, Indicates gas flow rate; Indicates the distance from the sound sensor 1 to the first receiving sensor 2; Indicates the distance from the sound sensor 1 to the second receiving sensor 3; Indicates the downstream delay time, Indicates the backflow delay time; is the angle between the sound propagation direction and the gas flow direction. The distance between the sensors is known and can be obtained by making a velocity triangle.

[0064] [Example] In practical applications, since the sensors are in the same measurement environment, the noise has a certain correlation, and the sound reverberates in the acoustic waveguide. Based on this, the generalized cross-correlation algorithm can be used to obtain accurate delay time. The following is the principle of the generalized cross-correlation algorithm: The distance from the sound sensor 1 to the first receiving sensor 2 is The time delay from the sound sensor 1 to the first receiving sensor 2 is the delay time ; The signals received by the sound sensor 1 and the first receiving sensor 2 are: (1) (2) For sound signal, For time delay, , , is the background noise, For time The generalized cross-correlation expression is: (3) According to the Wiener-Khinchin theorem, the inverse Fourier transform of the cross-power spectrum function is the cross-correlation function. Formula (3) is transformed to obtain: (4) is the cross power spectrum of the sound sensor 1 and the first receiving sensor 2.

[0065] ω The frequency components of a signal represented in the cross power spectrum are directly related to the oscillation frequency of the signal.

[0066] 1) Filtering Due to the complex structure and large size of modern power station boilers, the acoustic signal will be significantly attenuated when it propagates in high-temperature flue gas for a long time; in addition, due to the large amount of thermal background noise in the boiler, such as the combustion noise in the furnace, the jet noise of the burner and other mechanical noise, it will have a strong interference on the measurement result of the acoustic delay time; therefore, it is necessary to filter the received signal. High-order cumulative quantity has a good filtering effect on background noise, and the steps are as follows: The signal received by the sound sensor 1 and the first receiving sensor 2 , For example, for , The third-order autocumulant and third-order cross-cumulant are defined as: (5) (6) Substituting equation (1) and equation (2) into equation (5) and equation (6) respectively, we can obtain: (7) (8) By using the additivity of higher-order cumulants and the property that the fourth-order cumulant of Gaussian noise is zero, equations (5) and (6) can be simplified as: (9) (10) It can be seen from equations (9) and (10) that the Gaussian component in the signal is suppressed. At this time, if τ2 and τ3 in equations (9) and (10) are set to zero, a one-dimensional slice of the fourth-order cumulant can be obtained: (11) (12) From equations (11) and (12), we can see that the one-dimensional slice of the fourth-order cumulant still retains the advantage of suppressing Gaussian noise. Equation (12) can be regarded as the time-delay form of equation (11). If τ1 in equations (11) and (12) is replaced by t, the resulting filtered signal is , .

[0067] 2) Cross-correlation processing Then, their cross-correlation function is calculated according to the generalized cross-correlation delay estimation method.

[0068] , The cross power spectrum of is expressed as: (13) Since sound waves will generate standing waves in the pipeline, the PHAT weighted function based on phase transformation can effectively solve the influence of standing waves in the pipeline on time delay. The obtained function is the generalized cross-correlation function. The peak point of the generalized cross-correlation function corresponds to the time That is the time delay.

[0069] (14) (15) is the PHAT generalized cross-correlation weighted function; the time delay from the sound sensor 1 to the first receiving sensor 2 is obtained by the generalized cross-correlation algorithm . This is the time taken for the sound wave to travel from the sound sensor 1 to the first receiving sensor 2. Similarly, the delay time from the sound sensor 1 to the second receiving sensor 3 is obtained. .

[0070] 3) Flow velocity measured by time difference method The time difference method calculates the gas flow rate by measuring the difference in the propagation time of sound waves in the downstream and upstream directions of the gas. Three acoustic sensors are fixed in the measurement area. The sound sensor at the sound-emitting end measures the signal, and then cross-correlates it with the first receiving sensor 2 and the second receiving sensor 3 at the two receiving ends. The time for the sound wave to propagate from the sound-emitting sensor 1 to the first receiving sensor 2 and the second receiving sensor 3 is calculated by the generalized cross-correlation function. , The distances between the sound sensor 1 and the first receiving sensor 2 and the second receiving sensor 3 are and , the sound from the sound sensor 1 to the first receiving sensor 2 is transmitted along the wind, and the speed is , the sound sensor 1 propagates to the second receiving sensor 3 against the wind, and the speed is , then the gas flow rate can be expressed as: (16) In the formula, Indicates gas flow rate m / s; Indicates the sensor distance m; , Represent the downstream and upstream propagation times respectively. It is the angle between the sound propagation direction and the gas flow direction.

[0071] In summary, in the present invention, when in the measuring state, the test process will not affect the original flow field inside the pipeline. The use of a pneumatic sound source to generate sound overcomes the problem of low sound power. The receiving end arranges a resonant cavity and combines high-order cumulative amounts to filter the background noise, effectively solving the impact of background noise on the delay results. The PHAT weighting function is used to make the results more accurate. The one-transmitter and two-receiver arrangement can simultaneously obtain the propagation speed of sound in the downstream and upstream, avoiding the impact of the sound speed change caused by temperature changes on the time difference method. The present invention uses the principle that the sound speed is different in the downstream and upstream conditions, and obtains the gas flow rate by measuring the sound speed of the downstream and upstream, meeting the demand for gas turbine outlet flow rate measurement.

[0072] The present application discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for acoustically monitoring the inlet flue gas flow velocity of a combined cycle waste heat boiler as described in any one of the above items are implemented.

[0073] The present application discloses a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler described in any one of the above are implemented.

[0074] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An acoustic monitoring system for the inlet flue gas velocity of a combined cycle waste heat boiler, characterized in that: include: A pneumatic sound source device is used to generate a pneumatic sound wave signal and transmit the pneumatic sound wave signal to the flue gas duct; A sensor system is used to collect the pneumatic sound wave signal emitted by the pneumatic sound source device, and obtain the downwind propagation sound wave signal and the headwind propagation sound wave signal through the pneumatic sound wave signal; The pneumatic acoustic wave signal processing system is electrically connected to the sensor system and is used to calculate the gas flow rate on the corresponding path based on the downwind acoustic wave signal and the headwind acoustic wave signal collected by the sensor system, and display the measurement results.

2. The combined cycle waste heat boiler inlet flue gas velocity acoustic monitoring system according to claim 1, characterized in that: The pneumatic sound source device comprises a sound wave modulator and a variable frequency speed regulating motor, wherein the sound wave modulator and the variable frequency speed regulating motor are connected, and a gradually diverging nozzle (5) and a sound waveguide (4) are sequentially connected to the sound wave modulator, and the sound wave modulator transmits the pneumatic sound wave signal to the flue gas duct through the gradually diverging nozzle (5) and the sound waveguide (4).

3. The combined cycle waste heat boiler inlet flue gas velocity acoustic monitoring system according to claim 2, characterized in that: The sensor system comprises a sound sensor (1), a first receiving sensor (2) and a second receiving sensor (3); the sound sensor (1) is arranged on a sound waveguide (4); the first receiving sensor (2) and the second receiving sensor (3) are arranged on the side wall of the flue gas duct at the expanding section opposite to the sound sensor (1) and are dispersed on both sides of the sound sensor (1); and a resonant cavity (6) is installed between the first receiving sensor (2) and the second receiving sensor (3) and the side wall of the flue gas duct for collecting the downwind propagation sound wave signal and the headwind propagation sound wave signal emitted by the pneumatic sound source device; the sound sensor (1), the first receiving sensor (2) and the second receiving sensor (3) are all electrically connected to the sound wave signal processing system.

4. The combined cycle waste heat boiler inlet flue gas velocity acoustic monitoring system according to claim 1, characterized in that: The pneumatic acoustic wave signal processing system comprises: A filtering unit, used for filtering the pneumatic acoustic wave signals collected by the sensor system using high-order cumulative quantities to obtain filtered signals; A cross-correlation unit, used to obtain a cross-correlation function between filtered signals by adopting a generalized cross-correlation delay estimation method; and determine a delay time according to the cross-correlation function; The gas flow rate calculation unit is used to calculate the gas flow rate according to the delay time.

5. A method for acoustic monitoring of flue gas velocity at the inlet of a combined cycle waste heat boiler, characterized in that: include: The pneumatic sound source device generates a pneumatic sound wave signal; the sensor system collects the pneumatic sound wave signal emitted by the pneumatic sound source device; The acoustic wave signal processing system uses high-order cumulants to filter the pneumatic acoustic wave signals collected by the sensor system to obtain filtered signals; A generalized cross-correlation delay estimation method is used to obtain a cross-correlation function between the filtered signals; and a delay time is determined according to the cross-correlation function. Calculate the gas flow rate according to the delay time and display the calculation results.

6. The method for acoustically monitoring the flue gas velocity at the inlet of a combined cycle waste heat boiler according to claim 5, characterized in that: The sensor system comprises a sound sensor (1), a first receiving sensor (2) and a second receiving sensor (3); The time delay from the sound sensor (1) to the first receiving sensor (2) is the delay time The time delay from the sound sensor (1) to the second receiving sensor (3) is the delay time , then the signals received by the sound sensor (1) and the first receiving sensor (2) are respectively: Signal , Its third-order autocumulant and third-order cross-cumulant are defined as: The above formula uses the additivity of high-order cumulants and the property that the fourth-order cumulant of Gaussian noise is zero to simplify it to: Let τ2,τ3 be zero, and get a one-dimensional slice of the fourth-order cumulant: Substituting τ1 for t, we get the filtered signal of the sound sensor (1) , the filtered signal of the first receiving sensor (2) ; Similarly, the filtered signal of the second receiving sensor (3) is obtained .

7. The method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler according to claim 5, characterized in that: The generalized cross-correlation delay estimation method is used to obtain the cross-correlation function between the filtered signals; Determine the delay time according to the cross-correlation function, specifically including: The generalized cross-correlation expression is: According to the Wiener-Khinchin theorem, the inverse Fourier transform of the cross-power spectrum function is the cross-correlation function, and the above formula is transformed into: is the mutual power spectrum of the sound sensor (1) and the first receiving sensor (2) after high-order cumulant filtering; Filtered signal from the acoustic sensor (1) and the filtered signal of the first receiving sensor (2) The cross power spectrum of is expressed as: is the cross power spectrum of the sound sensor 1 and the first receiving sensor 2; Based on the PHAT weighting function of phase transformation, the generalized cross-correlation function is obtained: The independent variable corresponding to the peak point of the generalized cross-correlation function That is, the time delay from the sound sensor (1) to the first receiving sensor (2) Similarly, the delay time from the sound sensor (1) to the second receiving sensor (3) is obtained .

8. The method for acoustically monitoring the flue gas velocity at the inlet of a combined cycle waste heat boiler according to claim 5, characterized in that: The specific calculation of the gas flow rate according to the time delay is: If the propagation from the sound sensor (1) to the first receiving sensor (2) is downstream, and the propagation from the sound sensor (1) to the second receiving sensor (3) is upstream, then: In the formula, Indicates gas flow rate; Indicates the distance from the sound sensor (1) to the first receiving sensor (2); Indicates the distance from the sound sensor (1) to the second receiving sensor (3); represents the time delay from the sound sensor (1) to the first receiving sensor (2), i.e., the downstream delay time, Indicates the time delay from the sound sensor (1) to the second receiving sensor (3), that is, the backflow time delay; It is the angle between the sound propagation direction and the gas flow direction.

9. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler as described in any one of claims 5 to 8 when executing the computer program.

10. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the method for acoustically monitoring the inlet flue gas velocity of a combined cycle waste heat boiler according to any one of claims 5 to 8.

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