Energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis

Abstract

The application discloses an energy-saving industrial gas furnace air-fuel ratio self-adaptive control system based on flue gas analysis, which comprises an industrial furnace body, a main air regulating valve, a main gas regulating valve, a piezoelectric jet micro-perturbation valve, a wideband flame detector, a near-field high-speed gas sampling probe, a TDLAS spectrum analyzer and a central controller. The central controller extracts the flame background noise frequency band, calculates the dynamic micro-perturbation frequency to drive the piezoelectric jet micro-perturbation valve to inject flow micro-perturbation, synchronously receives the instantaneous concentration signal, combines the space physical volume parameters of each section to calculate the dynamic transmission delay time, and generates a local reference signal containing a pure lag phase compensation angle. The orthogonal phase-locked demodulation module extracts the gradient variable and drives the correction of the main air regulating valve opening degree. The application compensates for the phase shift caused by time lag and suppresses the interference of sensor baseline drift, and realizes the adaptive convergence of the air-fuel ratio parameter to the extreme point of thermal efficiency.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for industrial furnaces and kilns, and specifically to an energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis. Background Technology

[0002] Industrial gas-fired furnaces are widely used thermal equipment in industries such as metallurgy, chemical engineering, and machinery manufacturing. During the operation of a gas-fired furnace, the mixing ratio of fuel gas and combustion air, i.e., the air-fuel ratio, directly determines the combustion state and thermal energy conversion efficiency inside the furnace. The accurate achievement of the air-fuel ratio depends primarily on whether the fuel supply system can stably, accurately, and controllably distribute the gas to the burner.

[0003] Existing industrial gas-fired furnace fuel supply systems typically employ a single main pipeline for direct gas supply, with gas delivered directly to the burner after passing through a single main gas regulating valve. This supply method suffers from insufficient fuel distribution accuracy and delayed supply response when dealing with continuous variable load operation of the gas-fired furnace. Because the existing main pipeline fuel supply structure cannot superimpose a controllable high-frequency micro-perturbation fuel component onto the base gas flow rate, when the furnace load dynamically changes, fuel supply can only be completed through coarse adjustments of the main gas regulating valve. This leads to abrupt changes in the fuel supply ratio at the burner inlet, causing combustion instability or fluctuations in thermal efficiency.

[0004] While some existing technologies connect bypass pressure regulators or premixing devices in parallel with the main gas supply pipeline, the bypass flow is usually fixed or only coarsely adjusted, lacking an adaptive fuel distribution adjustment mechanism based on flue gas composition feedback. Furthermore, the bypass supply system lacks a physical structural safety cross-sectional area boundary; if the electrical actuator fails, the bypass gas flow may become uncontrollable, posing a safety hazard of sudden fuel supply changes. In summary, existing industrial gas furnace fuel supply systems have the following shortcomings: First, the single-channel structure of the main pipeline makes it difficult to achieve high-frequency dynamic perturbation superposition of fuel flow, resulting in a delayed burner inlet ratio response; second, the bypass pressure regulator or premixing device lacks an adaptive adjustment mechanism linked to real-time flue gas composition feedback, failing to dynamically optimize fuel distribution based on actual combustion conditions; third, the bypass system lacks a physical structural safety cross-sectional area boundary, posing a safety hazard of uncontrolled bypass gas flow in the event of an electrical actuator failure. Therefore, there is an urgent need for a fuel supply and air-fuel ratio coordinated control system that can superimpose controllable high-frequency perturbations on the steady-state flow of the main pipeline, optimize based on flue gas feedback closed-loop, and possess physical safety limits. Summary of the Invention

[0005] To address the problems mentioned in the background technology, the present invention provides an energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis, comprising: an industrial furnace body, a burner, a main air supply duct, a main gas supply duct, a main air regulating valve, a main gas regulating valve, a piezoelectric jet micro-perturbation valve, a broadband flame detector, a near-field high-speed gas sampling probe, a TDLAS spectrometer, and a central controller.

[0006] The main gas supply pipeline is divided into an upstream section and a downstream section. A main gas regulating valve is connected between the upstream and downstream sections to regulate the basic gas flow cross-sectional area of ​​the main gas supply pipeline. A bypass gas pipe is installed in parallel outside the main gas supply pipeline. The two ends of the bypass gas pipe are respectively connected to the upstream and downstream ends of the section where the main gas regulating valve is located. A manual flow back pressure valve and a piezoelectric jet perturbation valve are installed sequentially on the bypass gas pipe along the fluid flow direction. The manual flow back pressure valve sets the maximum flow cross-sectional area boundary of the bypass gas pipe in terms of physical structure. The piezoelectric jet perturbation valve contains piezoelectric... The system includes a ceramic stacked actuator, a mechanical amplification mechanism, and a micro-throttling valve core. The piezoelectric ceramic stacked actuator receives a high-frequency drive signal to generate mechanical deformation. The mechanical amplification mechanism drives the micro-throttling valve core to perform high-frequency reciprocating motion within the fluid channel of the bypass gas pipe. This continuously changes the cross-sectional area of ​​the fluid channel of the bypass gas pipe, causing the gas flowing through the bypass gas pipe to be approximately converted into a high-frequency jet pulsating gas mass with a sinusoidal amplitude envelope within the short-stroke linear working range of the micro-throttling valve core. This gas mass then flows into the downstream pipe section, where a high-frequency micro-perturbation fuel component is superimposed on the base gas flow rate output by the main gas regulating valve.

[0007] The outlet end of the main air supply duct and the outlet end of the main gas supply duct are both connected to the fluid inlet of the burner. The main air regulating valve is installed on the main air supply duct. The control end of the main air regulating valve is electrically connected to the signal output end of the central controller to receive basic air flow regulation commands and execute corresponding valve opening actions.

[0008] The broadband flame detector is installed on the side wall of the industrial furnace body, and the detection end of the broadband flame detector is directly opposite the root outlet position of the burner. The signal output end of the broadband flame detector is electrically connected to the signal input end of the central controller, which is used to collect the light intensity pulsation signal at the location of the burner in real time and transmit the light intensity pulsation signal to the central controller.

[0009] The industrial furnace body has a burner wake zone in its inner cavity, which is located downstream of the main flame reaction zone. The near-field high-speed gas sampling probe is installed on the industrial furnace body, and the sampling end of the near-field high-speed gas sampling probe extends into the burner wake zone. The output end of the near-field high-speed gas sampling probe is connected to the gas inlet of the TDLAS spectrometer through a sealed gas guide pipe. The digital signal output end of the TDLAS spectrometer is electrically connected to the communication interface of the central controller for outputting the instantaneous concentration signal of the target flue gas.

[0010] The central controller is an industrial computing control unit containing a processor and memory. The central controller extracts the flame background noise frequency band based on the light intensity pulsation signal and calculates the dynamic perturbation frequency, generating the high-frequency drive signal and outputting it to the piezoelectric jet perturbation valve to dynamically adjust the frequency and amplitude of the high-frequency jet pulsating air mass. The central controller also calculates the dynamic transmission delay time based on the instantaneous concentration signal and the dynamic perturbation frequency and generates a local reference signal containing a pure hysteresis phase compensation angle. It extracts gradient variables through orthogonal phase-locked demodulation and outputs a basic flow rate adjustment command to the main air regulating valve based on the gradient variables to adjust the basic air flow rate of the main air supply duct, so that the fuel and air ratio supplied to the burner by the main air supply duct and the main air supply duct adaptively converges towards the thermal efficiency extreme point.

[0011] Preferably, the broadband flame detector integrates an ultraviolet (UV) photosensitive sensor, an infrared (IR) photosensitive sensor, a signal conditioning and amplification circuit, a high-speed analog-to-digital converter (ADC), and a digital signal fusion unit. The UV and IR photosensitive sensors are arranged side-by-side, with their detection fields of view jointly covering the root outlet of the burner. The UV and IR photosensitive sensors convert the captured UV and IR light signals into analog micro-current signals. The signal conditioning and amplification circuit performs anti-aliasing low-pass filtering and gain amplification on the analog micro-current signals, converting them into voltage fluctuation signals. The high-speed ADC performs equal-interval sampling on the voltage fluctuation signals and outputs discrete channel signals. The digital signal fusion unit uses preset hardware weighting coefficients to linearly sum the discrete amplitudes at the same time, generating and outputting a single-channel physical light intensity pulsation signal.

[0012] Preferably, the near-field high-speed gas sampling probe includes an outer probe tube, an inner probe tube, a negative pressure pump, a porous sintered metal filter head, and a cooling water jacket; the inner probe tube is nested inside the outer probe tube, and an annular cooling medium channel connecting the outer probe tube and the inner probe tube is formed between them, communicating with the cooling water jacket; the porous sintered metal filter head is installed at the inlet end of the inner probe tube located inside the burner wake region, and is used to intercept solid particles in the flue gas cloud; the exhaust end of the inner probe tube is connected to the suction port of the negative pressure pump, and the negative pressure pump establishes a continuous directional negative pressure flow field inside the inner probe tube, and its exhaust port is connected to the gas inlet of the TDLAS spectrometer through a sealed gas guide pipe.

[0013] Preferably, the main gas supply pipeline is divided into an upstream section and a downstream section, and the main gas regulating valve is connected between the upstream section and the downstream section; a manual flow back pressure valve and a piezoelectric jet perturbation valve are sequentially installed on the bypass gas pipe along the fluid flow direction, and the manual flow back pressure valve sets the maximum flow cross-sectional area boundary of the bypass gas pipe in terms of physical structure; the piezoelectric jet perturbation valve contains a piezoelectric ceramic stacked actuator, a mechanical amplification mechanism, and a micro-throttling valve core. The piezoelectric ceramic stacked actuator receives the high-frequency drive signal to generate mechanical deformation, and its physical displacement output end is connected to the input end of the mechanical amplification mechanism. The mechanical amplification mechanism drives the micro-throttling valve core set in the fluid channel of the bypass gas pipe to perform high-frequency reciprocating motion to continuously change the cross-sectional area of ​​the fluid channel of the bypass gas pipe.

[0014] Preferably, the signal frequency domain analysis module specifically includes a data buffer register, a discrete Fourier transform processor, and a characteristic frequency band memory; the signal output terminal of the broadband flame detector is connected to the signal input terminal of the data buffer register, the output terminal of the data buffer register is connected to the input terminal of the discrete Fourier transform processor, and the output terminal of the discrete Fourier transform processor is connected to the characteristic frequency band memory; the data buffer register performs time windowing truncation on the physical light intensity pulsation signal to extract discrete time domain data frames, the discrete Fourier transform processor performs discrete power spectral density estimation calculation on the discrete time domain data frames and performs spectral peak search logic to extract the center noise frequency and the corresponding harmonic frequencies, which are combined into the flame background noise frequency band and written into the characteristic frequency band memory.

[0015] Preferably, the frequency orthogonal synthesis module specifically includes a frequency offset calculation unit and a driving waveform generation unit; the signal receiving end of the frequency offset calculation unit is communicatively connected to a characteristic frequency band memory that extracts the flame background noise frequency band, the signal output end of the frequency offset calculation unit is connected to the driving waveform generation unit, and the power output end of the driving waveform generation unit is connected to a piezoelectric jet perturbation valve; the frequency offset calculation unit reads the flame background noise frequency band and performs frequency orthogonal isolation calculation to establish the dynamic perturbation frequency, and the driving waveform generation unit synthesizes a sinusoidal AC voltage waveform based on the dynamic perturbation frequency, amplifies it, and converts it into the high-frequency driving voltage signal, which is then output to the piezoelectric jet perturbation valve.

[0016] Preferably, the frequency offset calculation unit searches for candidate frequencies within a preset effective hardware operating frequency band. The candidate frequencies meet the condition of maintaining a safe isolation width from all frequency components within the flame background noise frequency band. The frequency offset calculation unit establishes the candidate frequency that meets the isolation width condition and has the smallest frequency value as the dynamic perturbation frequency. The alternating frequency of the high-frequency drive voltage signal output by the drive waveform generation unit is equal to the dynamic perturbation frequency, and the peak voltage of the high-frequency drive voltage signal is less than or equal to the voltage amplitude limiting threshold corresponding to the basic gas flow command.

[0017] Preferably, the digital quadrature phase-locked loop demodulation module includes a hardware phase-locked loop unit, a quadrature reference signal generator, a multiplier array, and a low-pass integral filter. The TDLAS spectrometer is connected to the signal input terminal of the digital quadrature phase-locked loop demodulation module, the frequency quadrature synthesis module is connected to the input terminal of the hardware phase-locked loop unit, the hardware phase-locked loop unit is connected to the quadrature reference signal generator, the quadrature reference signal generator is connected to the multiplier array, and the multiplier array is connected to the low-pass integral filter. The hardware phase-locked loop unit tracks the phase characteristics of the dynamic perturbation frequency signal to establish a high-frequency synchronous clock. The quadrature reference signal generator generates a sinusoidal reference waveform based on the high-frequency synchronous clock and combines it with the dynamic transmission delay time to generate a local reference signal containing a pure hysteresis phase compensation angle. The multiplier array performs a time-domain multiplication operation on the instantaneous concentration signal and the local reference signal to output a mixed-frequency modulation signal. The low-pass integral filter performs an integral filtering operation on the mixed-frequency modulation signal, extracts and outputs the gradient variable to the central controller for closed-loop optimization correction of the wind-fuel ratio.

[0018] The present invention, by adopting the above technical solution, can bring the following beneficial effects:

[0019] 1. This invention utilizes a parallel distribution structure of the main gas supply pipeline and the bypass gas pipeline, combined with the high-frequency reciprocating displacement drive of the piezoelectric jet micro-perturbation valve, to superimpose a controllable high-frequency micro-perturbation fuel component onto the basic gas flow rate in the main pipeline. This achieves dynamic distribution and micro-perturbation modulation of fuel supply, enabling the fuel supply at the burner inlet to possess the physical superposition characteristics of steady-state DC component and high-frequency AC component. This improves the uniformity and response accuracy of fuel supply, thereby effectively suppressing the sensor baseline drift component under dynamic load changes in industrial gas furnaces while reducing the dependence on absolute sensor calibration. This drives the main air regulating valve to track the actual highest thermal efficiency operating point in a closed loop.

[0020] 2. This invention utilizes a broadband flame detector to collect light intensity pulsation signals at the burner root, and then uses a signal frequency domain analysis module to perform power spectrum calculations to extract the background noise frequency band containing harmonics. Subsequently, a frequency orthogonal synthesis module is used to establish a dynamic perturbation frequency that maintains a safe isolation width from the noise frequency band. This achieves the active avoidance of the spectral masking effect of basic combustion noise on perturbation characteristic signals under complex physical backgrounds such as furnace turbulence and resonance. It ensures low attenuation physical transmission and high signal-to-noise ratio demodulation effect of weak high-frequency detection characteristics in non-steady-state environments, thereby ensuring the accurate setting of the bypass fuel perturbation supply frequency.

[0021] 3. This invention utilizes a manual flow back pressure valve to set the maximum flow cross-sectional area boundary of the bypass gas pipe in the physical structure, preventing excessive gas flow injection caused by electrical faults. At the same time, the central controller extracts the current basic flow command and dynamically calculates the transmission delay time in combination with spatial physical volume parameters, driving the orthogonal reference signal generator to generate a local reference signal containing phase compensation angle. This, together with the near-field high-speed gas sampling probe in the burner wake region, shortens the sampling path, realizing the compensation for phase shift caused by time lag when the flow rate changes due to macroscopic heat load switching, thereby suppressing the misalignment interference caused by phase-locked demodulation polarity judgment, and ensuring the convergence stability and execution accuracy of fuel supply parameters in the full load operating range. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall system structure and fluid pipeline layout of the present invention;

[0023] Figure 2 This is a block diagram of the internal functional modules and signal flow of the central controller of the present invention;

[0024] Figure 3 This is a cross-sectional view of the mechanical structure of the core front-end sensing and execution hardware of this invention;

[0025] Figure 4 This is the main flowchart of the wind-fuel ratio adaptive closed-loop control and extreme value optimization of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please refer to the appendix. Figure 1-4 This invention provides an energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis, comprising: an industrial furnace body 100, a burner 110, a main air supply duct 120, a main gas supply duct 130, a main air regulating valve 210, a main gas regulating valve 220, a piezoelectric jet perturbation valve 300, a broadband flame detector 400, a near-field high-speed gas sampling probe 510, a TDLAS spectrometer 520, and a central controller 600.

[0028] A burner 110 is installed on the side wall of the industrial furnace body 100. The outlet end of the main air supply pipe 120 and the outlet end of the main gas supply pipe 130 are both connected to the fluid inlet of the burner 110. The main air regulating valve 210 is installed on the main air supply pipe 120. The main gas regulating valve 220 is connected between the upstream and downstream pipe sections of the main gas supply pipe 130 and is used to regulate the basic gas flow cross-sectional area of ​​the main gas supply pipe 130. The control ends of the main air regulating valve 210 and the main gas regulating valve 220 are both electrically connected to the signal output end of the central controller 600 and are used to receive the basic flow regulation command sent by the central controller 600 and execute the corresponding valve opening action.

[0029] A bypass gas pipe is installed in parallel outside the main gas supply pipeline 130. The two ends of the bypass gas pipe are connected to the upstream end and the downstream end of the pipeline section where the main gas regulating valve 220 is located, respectively. A piezoelectric jet perturbation valve 300 is installed on the bypass gas pipe. The drive input end of the piezoelectric jet perturbation valve 300 is electrically connected to the drive output end of the central controller 600. The piezoelectric jet perturbation valve 300 is used to receive high-frequency drive signals and inject flow perturbation into the basic gas flow.

[0030] A broadband flame detector 400 is installed on the side wall of the industrial furnace body 100, and the detection end of the broadband flame detector 400 is directly facing the root outlet position of the burner 110. The signal output end of the broadband flame detector 400 is electrically connected to the signal input end of the central controller 600, which is used to collect the light intensity pulsation signal at the location of the burner 110 in real time and transmit the light intensity pulsation signal to the central controller 600.

[0031] The industrial furnace body 100 has a burner wake zone in its inner cavity, which is located downstream of the main flame reaction zone. A near-field high-speed gas sampling probe 510 is installed on the industrial furnace body 100, and the sampling end of the near-field high-speed gas sampling probe 510 extends into the burner wake zone. The output end of the near-field high-speed gas sampling probe 510 is connected to the gas inlet of the TDLAS spectrometer 520 through a sealed gas guide pipe. The digital signal output end of the TDLAS spectrometer 520 is electrically connected to the communication interface of the central controller 600 to output the instantaneous concentration signal of the target flue gas.

[0032] The central controller 600 is an industrial computing control unit that includes a processor and a memory. The central controller 600 integrates a signal frequency domain analysis module 610, a frequency quadrature synthesis module 620, and a digital quadrature phase-locked demodulation module 630.

[0033] A wideband flame detector 400 is installed on the side wall of the industrial furnace body 100. The wideband flame detector 400 integrates an ultraviolet photosensitive sensor 401, an infrared photosensitive sensor 402, a signal conditioning and amplification circuit 403, a high-speed analog-to-digital conversion module 404, and a digital signal fusion unit 405. The ultraviolet photosensitive sensor 401 and the infrared photosensitive sensor 402 are arranged side by side. The detection field of the ultraviolet photosensitive sensor 401 and the detection field of the infrared photosensitive sensor 402 together cover the root outlet position of the burner 110.

[0034] The root outlet of burner 110 is the initial ignition zone after fuel and air are mixed. The flame front in the initial ignition zone is affected by physical flow field disturbance and acoustic resonance of furnace space, resulting in high-frequency physical spatial position jitter and light intensity flicker. Spatial position jitter and light intensity flicker constitute the background macroscopic physical noise of the combustion process.

[0035] The industrial furnace body 100 is internally defined by a main flame reaction zone and a burner wake zone downstream of the main flame reaction zone. The burner wake zone is located in a physical space away from the strong turbulence center of the main flame reaction zone. The near-field high-speed gas sampling probe 510 penetrates the side wall of the industrial furnace body 100, and the sampling end of the near-field high-speed gas sampling probe 510 extends into the burner wake zone.

[0036] The near-field high-speed gas sampling probe 510 includes an outer probe tube 511, an inner probe tube 512, a negative pressure pump 513, and a porous sintered metal filter head 515. The inner probe tube 512 is nested inside the outer probe tube 511, and an annular cooling medium channel is formed between the outer probe tube 511 and the inner probe tube 512. The near-field high-speed gas sampling probe 510 also includes a cooling water jacket 514, which is connected to the annular cooling medium channel and is used to introduce liquid cooling medium into the annular cooling medium channel to reduce the surface physical temperature of the inner probe tube 512.

[0037] The porous sintered metal filter head 515 is installed at the air inlet end of the probe inner tube 512 located inside the burner wake region. The air inlet end of the probe inner tube 512 is directly facing the airflow discharge direction of the burner wake region. The exhaust end of the probe inner tube 512 is connected to the air extraction port of the negative pressure pump 513. The exhaust port of the negative pressure pump 513 is connected to the gas inlet of the TDLAS spectrometer 520 through a sealed gas guide pipe.

[0038] The main gas supply pipeline 130 is divided into an upstream section and a downstream section. The main gas regulating valve 220 is connected between the upstream section and the downstream section. The inlet end of the bypass gas pipe is connected to the upstream section, and the outlet end of the bypass gas pipe is connected to the downstream section.

[0039] A manual flow back pressure valve 304 and a piezoelectric jet perturbation valve 300 are sequentially installed on the bypass air pipe along the fluid advance direction. The manual flow back pressure valve 304 sets the maximum flow cross-sectional area boundary of the bypass air pipe in the physical structure to prevent electrical faults from causing excessive airflow jetting.

[0040] The piezoelectric jet perturbation valve 300 includes a piezoelectric ceramic stacked actuator 301, a mechanical amplification mechanism 302, and a micro-throttle valve core 303. The physical displacement output end of the piezoelectric ceramic stacked actuator 301 is connected to the input end of the mechanical amplification mechanism 302, and the displacement output end of the mechanical amplification mechanism 302 is connected to the micro-throttle valve core 303. The micro-throttle valve core 303 is disposed in the fluid channel of the bypass gas pipe.

[0041] The signal frequency domain analysis module 610 inside the central controller 600 specifically includes a data buffer register 611, a discrete Fourier transform processor 612, and a characteristic frequency band memory 613. The signal output terminal of the wideband flame detector 400 is connected to the signal input terminal of the data buffer register 611, the output terminal of the data buffer register 611 is connected to the input terminal of the discrete Fourier transform processor 612, and the output terminal of the discrete Fourier transform processor 612 is connected to the characteristic frequency band memory 613.

[0042] The frequency orthogonal synthesis module 620 inside the central controller 600 is communicatively connected to the characteristic frequency band memory 613. The output end of the frequency orthogonal synthesis module 620 is electrically connected to the drive input end of the piezoelectric jet perturbation valve 300. The frequency orthogonal synthesis module 620 specifically includes a frequency offset calculation unit 621 and a drive waveform generation unit 622. The signal receiving end of the frequency offset calculation unit 621 is connected to the characteristic frequency band memory 613, the signal output end of the frequency offset calculation unit 621 is connected to the drive waveform generation unit 622, and the power output end of the drive waveform generation unit 622 is connected to the piezoelectric jet perturbation valve 300.

[0043] The digital quadrature phase-locked demodulation module 630 inside the central controller 600 includes a hardware phase-locked loop unit 631, a quadrature reference signal generator 632, a multiplier array 633, and a low-pass integrating filter 634. The digital signal output terminal of the TDLAS spectrum analyzer 520 is connected to the signal input terminal of the digital quadrature phase-locked demodulation module 630. The synchronization signal output terminal of the frequency quadrature synthesis module 620 is connected to the input terminal of the hardware phase-locked loop unit 631. The signal output terminal of the hardware phase-locked loop unit 631 is connected to the quadrature reference signal generator 632. The quadrature reference signal generator 632 is connected to the multiplier array 633. The multiplier array 633 is connected to the low-pass integrating filter 634.

[0044] The above system achieves adaptive closed-loop optimization control of the wind-fuel ratio through the coordinated operation of various hardware modules and functional units. The specific operating mechanism and working steps of each link are as follows:

[0045] First, the overall closed-loop control and extreme value optimization process of the system is executed based on the above hardware architecture. The overall process includes the following steps:

[0046] Step S101: The central controller 600 receives the heat load demand command from the industrial furnace body 100. The central controller 600 outputs an initial flow regulation signal to the main air regulating valve 210 and the main gas regulating valve 220 according to the heat load demand command. The main air regulating valve 210 adjusts the flow cross-sectional area to establish the basic air flow rate, and the main gas regulating valve 220 adjusts the flow cross-sectional area to establish the basic gas flow rate. The basic gas flow rate in the main gas supply pipeline 130 flows into the downstream pipe section through the main gas regulating valve 220. The piezoelectric jet micro-disturbance valve 300 is in the initial standby state. The bypass gas pipe maintains the basic conduction cross-sectional area set by the manual flow back pressure valve 304. The burner 110 establishes a continuous combustion state based on the basic gas flow rate supplied by the main gas supply pipeline 130 and the basic air flow rate supplied by the main air supply pipeline 120.

[0047] Step S102: The wideband flame detector 400 collects the physical light intensity pulsation signal of the root area of ​​the burner 110 in real time. The wideband flame detector 400 transmits the physical light intensity pulsation signal to the signal frequency domain analysis module 610 inside the central controller 600. The signal frequency domain analysis module 610 performs power spectral density analysis on the physical light intensity pulsation signal and extracts the dominant frequency and harmonic frequency under the current combustion condition. The signal frequency domain analysis module 610 establishes the extracted dominant frequency and harmonic frequency as the flame background noise frequency band.

[0048] Step S103: The frequency orthogonal synthesis module 620 receives the flame background noise frequency band, calculates and outputs a dynamic perturbation frequency that avoids the flame background noise frequency band, and sends a high-frequency driving voltage signal containing the dynamic perturbation frequency to the piezoelectric jet perturbation valve 300. The piezoelectric jet perturbation valve 300 generates mechanical deformation according to the high-frequency driving voltage signal and drives the micro-motion throttle valve core 303 to move back and forth at high frequency, generating a sinusoidal flow perturbation in the bypass gas pipe. After the perturbation flows into the downstream pipe section through the bypass gas pipe, the corresponding high-frequency perturbation fuel component is superimposed on the basic gas flow of the downstream pipe section of the main gas supply pipeline 130, so that the actual gas supply flow field in the downstream pipe section is reconstructed into a physical superposition flow field containing steady-state DC component and high-frequency AC component.

[0049] Step S104: The near-field high-speed gas sampling probe 510 extracts flue gas samples in the burner wake region. The near-field high-speed gas sampling probe 510 delivers the flue gas samples to the TDLAS spectrometer 520 through a negative pressure micro-extraction structure. The TDLAS spectrometer 520 performs spectral absorption testing on the flue gas samples, obtains the instantaneous concentration signal of the target analytical gas, and sends the instantaneous concentration signal to the central controller 600.

[0050] Step S105: The digital orthogonal phase-locked demodulation module 630 synchronously receives the instantaneous concentration signal transmitted by the TDLAS spectrometer 520 and the high-frequency driving voltage signal output by the frequency orthogonal synthesis module 620. The digital orthogonal phase-locked demodulation module 630 performs phase-locked demodulation operation to obtain the gradient variable characterizing the relationship between combustion efficiency and air-fuel ratio.

[0051] Step S106: The central controller 600 determines the polarity and magnitude of the gradient variable. The central controller 600 compares the absolute value of the gradient variable with the preset dead zone threshold. If the absolute value of the gradient variable is greater than the preset dead zone threshold, the central controller 600 performs a step-increase or step-decrease numerical correction on the current basic flow regulation signal of the main air regulating valve 210 according to the polarity of the gradient variable. If the absolute value of the gradient variable is less than or equal to the preset dead zone threshold, the central controller 600 maintains the current flow regulation signal of the main air regulating valve 210. The main air regulating valve 210 changes the basic air flow according to the corrected flow regulation signal, and adjusts the fuel and air ratio supplied to the burner 110 by the main air supply pipe 130 and the main air supply pipe 120, so that the combustion state approaches the thermal efficiency extreme point. The system cyclically executes the above steps to realize the dynamic optimization control of the air-fuel ratio.

[0052] In the initial stage of executing the above-mentioned overall extreme value optimization process, the system first establishes an initial steady-state combustion environment through a basic operating condition tracking and steady-state energy supply ratio mechanism, which serves as the benchmark for subsequent perturbation and optimization. The execution steps of this mechanism are as follows:

[0053] Step S201: The central controller 600 receives the macro heat load command of the industrial furnace body 100 from the external input. The macro heat load command represents the target amount of heat energy output required by the industrial furnace body 100 in the current production process stage. The central controller 600 internally stores a steady-state operating condition tracking curve table, which records the open-loop control reference parameters corresponding to different heat load nodes.

[0054] Step S202: The central controller 600 queries the steady-state operating condition tracking curve table according to the macro heat load command, and parses out the basic gas flow command and basic air flow command corresponding to the current operating condition. The central controller 600 converts the basic gas flow command into an electrical signal and sends it to the main gas regulating valve 220. The main gas regulating valve 220 drives the valve core displacement according to the electrical signal, changes the flow cross-sectional area of ​​the main gas supply pipeline 130, and establishes the actual basic gas flow in the main gas supply pipeline 130.

[0055] In step S203, the central controller 600 synchronously converts the basic air flow command into an electrical signal and sends it to the main air regulating valve 210. The main air regulating valve 210 receives the electrical signal and drives the valve core to move, changing the flow cross-sectional area of ​​the main air supply duct 120 and establishing the actual basic air flow in the main air supply duct 120.

[0056] Step S204: The air in the main air supply duct 120 and the gas in the main gas supply duct 130 enter the burner 110. The burner 110 establishes an initial physical mixing ratio based on the ratio between the basic air flow command value and the basic gas flow command value.

[0057] In step S205, when the main air regulating valve 210 and the main gas regulating valve 220 execute the flow regulation command of the central controller 600, they adopt cross-limit interlock control logic. When the macro heat load command indicates that the heat load increases, the central controller 600 sets a time interlock delay and controls the main air regulating valve 210 to increase the valve opening before the main gas regulating valve 220. When the macro heat load command indicates that the heat load decreases, the central controller 600 sets a time interlock delay and controls the main gas regulating valve 220 to decrease the valve opening before the main air regulating valve 210.

[0058] In step S206, the main air regulating valve 210 and the main gas regulating valve 220 complete their action response, the burner 110 reaches the continuous combustion state, and an initial steady-state heating environment matching the macroscopic heat load command is established inside the industrial furnace body 100. The initial steady-state heating environment serves as the physical basis reference surface for subsequent high-frequency aerodynamic micro-perturbation superposition and extreme value optimization feedback control.

[0059] To address the need for high-frequency and precise detection of flue gas components, the aforementioned near-field high-speed gas sampling probe employs a near-field anti-diffusion sampling method to collect flue gas samples from the burner wake region, thereby preserving the frequency characteristics of perturbations in the flue gas. The corresponding sampling steps are as follows:

[0060] Step S301: The negative pressure pump 513 is started and a continuous directional negative pressure flow field is established inside the probe inner tube 512;

[0061] Step S302: The flue gas cloud containing dynamic perturbation frequency characteristics in the burner wake region is subjected to the pressure gradient of the directional negative pressure flow field and passes through the porous sintered metal filter head 515. The porous sintered metal filter head 515 intercepts solid particles in the flue gas cloud.

[0062] Step S303: The flue gas cloud containing filtered solid particles is accelerated into the probe inner tube 512 before the flue gas diffuses significantly;

[0063] Step S304: The probe inner tube 512 shortens the transmission path distance of flue gas from the combustion reaction generation location to the TDLAS spectrometer 520. The directional negative pressure flow field increases the flow velocity of the flue gas cloud in the sealed gas guide pipe, maintains the original high-frequency characteristics of flue gas cloud composition fluctuations, and the near-field anti-diffusion sampling structure in the burner wake region prevents dynamic micro-disturbance signals from undergoing hydrodynamic attenuation and signal smoothing in the large volume space of the industrial furnace body 100.

[0064] To address the need for collecting combustion background noise, the aforementioned broadband flame detector uses a dual-channel fusion approach combining ultraviolet and infrared radiation to acquire flame physical pulsation signals, ensuring wideband coverage and accuracy. The specific acquisition steps are as follows:

[0065] In step S401, the burner 110 maintains continuous combustion, the ultraviolet photosensitive sensor 401 captures the instantaneous change in light intensity in the ultraviolet band within the initial ignition zone in real time, and the infrared photosensitive sensor 402 simultaneously captures the instantaneous change in light intensity in the infrared band within the initial ignition zone.

[0066] In step S402, the ultraviolet photosensitive sensor 401 and the infrared photosensitive sensor 402 convert the captured ultraviolet light signal and infrared light signal into analog micro-current signals.

[0067] Step S403: The signal conditioning and amplification circuit 403 receives the analog micro-current signal and performs impedance matching, anti-aliasing low-pass filtering and linear gain amplification on the analog micro-current signal to convert the analog micro-current signal into a voltage fluctuation signal.

[0068] Step S404: The high-speed analog-to-digital converter module 404 receives the voltage fluctuation signal. According to the Nyquist sampling theorem, the high-speed analog-to-digital converter module 404 samples the voltage fluctuation signal at equal intervals at a discrete sampling frequency that is more than twice the highest effective frequency band of the flame pulsation, and outputs the ultraviolet channel digital signal and the infrared channel digital signal.

[0069] Step S405: The digital signal fusion unit 405 receives the ultraviolet channel digital signal and the infrared channel digital signal. The digital signal fusion unit 405 extracts the discrete amplitude of the ultraviolet channel digital signal and the infrared channel digital signal at the same time, and uses a preset hardware weighting coefficient to linearly add the discrete amplitude to generate a single-channel physical light intensity pulsation signal.

[0070] In step S406, the wideband flame detector 400 sends the physical light intensity pulsation signal to the signal frequency domain analysis module 610 inside the central controller 600. The physical light intensity pulsation signal serves as the original physical data source for subsequent extraction of the flame background noise frequency band.

[0071] After the acquired physical light intensity pulsation signal is input into the signal frequency domain analysis module, this module extracts and models the frequency domain characteristics of the background noise, providing input basis for subsequent perturbation frequency calculation. The specific execution steps are as follows:

[0072] Step S501: The signal frequency domain analysis module 610 receives the physical light intensity pulsation signal transmitted by the broadband flame detector 400. The data buffer register 611 performs time windowing truncation on the physical light intensity pulsation signal to extract discrete time domain data frames with a fixed time window length. During the time windowing truncation process, the data buffer register 611 uses the Hanning window function to smooth the data boundaries and suppress the spectral leakage phenomenon caused by discrete data truncation.

[0073] Step S502: The Discrete Fourier Transform processor 612 receives a discrete time-domain data frame. The Discrete Fourier Transform processor 612 performs discrete power spectral density estimation calculation on the discrete time-domain data frame, converting the discrete sequence in the time domain dimension into a discrete power spectral density array in the frequency domain dimension. The discrete power spectral density estimation calculation uses the following formula:

[0074]

[0075] In the formula, Representing the The normalized power spectrum estimate corresponding to each frequency index; This represents the total number of sampling points within a discrete-time data frame. Represents a discrete time series index; Representing the The amplitude of the digital light intensity pulsation signal corresponding to each sampling point is the value after being weighted by the Hanning window; Represents a discrete frequency index; Represents the imaginary unit; Represents the natural constant; in the above discrete power spectral density estimation calculation, the discrete Fourier transform processor 612 has performed a transform on the windowed data, and normalized it according to the Hanning window energy coefficient to ensure... The amplitude of the signal corresponds to the power spectral density of the physical light intensity pulsation signal;

[0076] Step S503: Discrete Fourier Transform processor 612 traverses the discrete power spectral density array, executes the spectral peak search logic, locates the extreme points in the discrete power spectral density array where the amplitude is greater than the preset energy threshold, and extracts the corresponding frequency coordinates as the center noise frequency.

[0077] Step S504: Discrete Fourier Transform processor 612 establishes the center noise frequency as the fundamental frequency and calculates the corresponding harmonic frequencies according to the positive integer multiple relationship. Discrete Fourier Transform processor 612 combines the fundamental frequency and the harmonic frequencies into a frequency set and defines the frequency set as the flame background noise frequency band.

[0078] Step S505: Discrete Fourier Transform processor 612 writes the flame background noise frequency band into the characteristic frequency band memory 613. The characteristic frequency band memory 613 stores the physical characteristic parameters of the background noise under the current combustion conditions and sends the flame background noise frequency band to the frequency orthogonal synthesis module 620 inside the central controller 600. The frequency orthogonal synthesis module 620 receives the flame background noise frequency band and uses it as the input parameter for subsequent frequency offset calculation.

[0079] Based on the extracted flame background noise frequency band, the frequency orthogonal synthesis module performs orthogonal frequency offset isolation calculation to generate dynamic perturbation frequencies that do not overlap with the background noise frequency band, thus avoiding signal interference. The specific calculation and output steps are as follows:

[0080] Step S601: The frequency offset calculation unit 621 inside the frequency orthogonal synthesis module 620 reads the flame background noise frequency band from the characteristic frequency band memory 613. The flame background noise frequency band includes the center noise frequency and the harmonic frequencies corresponding to the center noise frequency.

[0081] Step S602: Frequency offset calculation unit 621 performs frequency orthogonal isolation calculation. Frequency offset calculation unit 621 searches for candidate frequencies within a preset effective hardware operating frequency band. The candidate frequencies must meet the following constraints: For all All have The frequency offset calculation unit 621 establishes the candidate frequency that meets the isolation width condition and has the smallest frequency value, in order to reduce the mechanical fatigue loss of the piezoelectric jet perturbation valve and reduce high-frequency aerodynamic noise coupling, as the dynamic perturbation frequency. The frequency orthogonal isolation calculation adopts the following constraints:

[0082]

[0083] In the formula, Represents the dynamic perturbation frequency; This represents the highest order of harmonics contained within the frequency band of the flame's background noise. Represents the harmonic order variable; Represents the center noise frequency; This represents the preset security isolation bandwidth value;

[0084] Step S603: The frequency offset calculation unit 621 sends the dynamic perturbation frequency to the drive waveform generation unit 622. The digital-to-analog conversion circuit inside the drive waveform generation unit 622 synthesizes a sinusoidal AC voltage waveform based on the dynamic perturbation frequency. The power amplifier circuit inside the drive waveform generation unit 622 amplifies the sinusoidal AC voltage waveform and converts it into a high-frequency drive voltage signal.

[0085] Step S604: The drive waveform generation unit 622 outputs a high-frequency drive voltage signal to the piezoelectric jet perturbation valve 300. The alternating frequency of the high-frequency drive voltage signal is equal to the dynamic perturbation frequency. The high-frequency drive voltage signal is orthogonally separated from the flame background noise frequency band in the spectrum distribution.

[0086] Step S605: The piezoelectric ceramic stack inside the piezoelectric jet perturbation valve 300 receives a high-frequency driving voltage signal and generates mechanical deformation. The mechanical deformation drives the valve core of the piezoelectric jet perturbation valve 300 to move. The piezoelectric jet perturbation valve 300 generates a sinusoidal flow perturbation in the bypass gas pipe. After the perturbation flows into the downstream pipe section through the bypass gas pipe, the sinusoidal flow perturbation is superimposed on the basic gas flow rate of the downstream pipe section of the main gas supply pipeline 130. The fluctuation frequency of the sinusoidal flow perturbation is equal to the dynamic perturbation frequency.

[0087] After the generated high-frequency driving voltage signal is input into the piezoelectric jet perturbation valve, a high-frequency perturbation component is superimposed on the main gas flow rate through fluid dynamic coupling, thereby achieving the superposition of steady-state flow rate and perturbation signal. The specific operation steps are as follows:

[0088] Step S701: The main gas regulating valve 220 sets the basic flow cross-sectional area based on the basic gas flow command of the central controller 600. The main gas in the upstream pipe section flows through the main gas regulating valve 220 and forms a macroscopic steady-state gas flow. Part of the gas in the upstream pipe section is diverted into the bypass gas pipe and flows through the manual flow back pressure valve 304 to reduce pressure and throttle.

[0089] In step S702, the frequency orthogonal synthesis module 620 inside the central controller 600 reads the value of the basic gas flow command and generates a voltage amplitude limiting threshold corresponding to the basic gas flow command. The frequency orthogonal synthesis module 620 outputs a high-frequency drive voltage signal to the piezoelectric ceramic stacked actuator 301. The alternating frequency of the high-frequency drive voltage signal is equal to the dynamic perturbation frequency, and the peak voltage of the high-frequency drive voltage signal is less than or equal to the voltage amplitude limiting threshold. The piezoelectric ceramic stacked actuator 301 generates a high-frequency mechanical extension displacement synchronized with the dynamic perturbation frequency based on the inverse piezoelectric effect.

[0090] Step S703: The mechanical amplification mechanism 302 receives the high-frequency mechanical extension and retraction displacement and performs geometric displacement amplification. The mechanical amplification mechanism 302 drives the micro-motion throttle valve core 303 to perform high-frequency reciprocating motion in the fluid channel of the bypass air pipe.

[0091] Step S704: The high-frequency reciprocating motion of the micro-throttle valve core 303 continuously changes the cross-sectional area of ​​the fluid channel in the bypass gas pipe. The gas entering the bypass gas pipe is transformed into a high-frequency jet pulsating gas mass with a sinusoidal amplitude envelope by the periodic change of the cross-sectional area of ​​the fluid channel. The pulsation frequency of the high-frequency jet pulsating gas mass is consistent with the dynamic perturbation frequency.

[0092] Step S705: The high-frequency jet pulsating gas mass is injected from the outlet end of the bypass gas pipe and merges into the downstream pipe section. In the downstream pipe section, the high-frequency jet pulsating gas mass undergoes momentum exchange and mass mixing in the fluid dynamic dimension with the macroscopic steady-state airflow flowing through the main gas regulating valve 220.

[0093] Step S706: The actual air supply field in the downstream pipe section is reconstructed into a physical superposition flow field containing a steady-state DC fluid component and a high-frequency AC fluid component. The steady-state DC fluid component is used to maintain the macroscopic heat load of the industrial furnace body 100, and the high-frequency AC fluid component, as a characteristic physical signal for extreme value optimization, enters the burner 110 with the total airflow to participate in the chemical combustion reaction.

[0094] After the instantaneous concentration signal of the flue gas sample is obtained by the TDLAS spectrometer, the digital quadrature phase-locked loop demodulation module performs frequency conversion quadrature phase-locked loop demodulation processing to extract the gradient variable with the same frequency as the perturbation from the noisy signal. The specific processing steps are as follows:

[0095] Step S801: The TDLAS spectrometer 520 performs real-time spectral absorption detection on the flue gas cloud entering the internal optical chamber. In this embodiment, the target gas to be analyzed is oxygen or carbon monoxide. The TDLAS spectrometer 520 outputs an instantaneous concentration signal reflecting the content of the target flue gas components, and the digital quadrature phase-locked demodulation module 630 receives the instantaneous concentration signal.

[0096] Step S802: The hardware phase-locked loop unit 631 synchronously receives the dynamic perturbation frequency signal output by the frequency quadrature synthesis module 620. The hardware phase-locked loop unit 631 extracts and tracks the phase characteristics of the dynamic perturbation frequency signal and establishes a high-frequency synchronous clock inside the digital quadrature phase-locked demodulation module 630.

[0097] Step S803: The central controller 600 has pre-stored the spatial physical volume parameters of each segment from the piezoelectric jet perturbation valve 300 to the near-field high-speed gas sampling probe 510, including the bypass gas pipe volume, the downstream main gas supply pipe volume, and the flue gas transmission volume from the burner wake region to the sampling probe; the central controller 600 extracts the basic gas flow command and basic air flow command at the current moment, calculates the overall fluid volume flow rate of the system, and obtains the local fluid volume flow rate in the bypass gas pipe based on the design flow split ratio of the bypass gas pipe and the main gas supply pipe; the central controller 600 calculates the ratio of each segment's spatial physical volume parameter to the corresponding fluid volume flow rate and sums them to obtain the dynamic transmission delay time; the quadrature reference signal generator 632 generates a sine reference waveform based on a high-frequency synchronous clock, and performs phase offset adjustment on the sine reference waveform in combination with the dynamic transmission delay time to generate a local reference signal containing a pure hysteresis phase compensation angle;

[0098] Step S804: The multiplier array 633 receives the instantaneous concentration signal and the local reference signal. The multiplier array 633 performs a time-domain multiplication operation on the instantaneous concentration signal and the local reference signal, and outputs a mixed-modulation signal containing a DC bias component and a high-frequency carrier superposition component.

[0099] Step S805: The low-pass integral filter 634 receives the mixing modulation signal. The low-pass integral filter 634 performs integral filtering operation on the mixing modulation signal within a preset time constant period to filter out AC noise components higher than the dynamic perturbation frequency and physical background interference components that are not in sync with the dynamic perturbation frequency.

[0100] Step S806: The low-pass integral filter 634 extracts and outputs gradient variables reflecting the direction and degree of deviation of the current basic wind-fuel ratio from the point of highest thermal efficiency. The gradient variable extraction calculation uses the following orthogonal phase-locked integration formula:

[0101]

[0102] In the formula, The gradient variable representing the current time point; This represents the value of the integration time constant; An independent time variable representing the current calculation moment; The independent variable represents the integral interval; the integral interval is the time constant preceding the current time t. ,Right now ; This represents the instantaneous concentration signal value corresponding to the independent variable at that moment; Represents the value of the dynamic perturbation frequency; The pure time delay phase compensation angle represents the dynamic calculation of the central controller 600. Represents the sine function operator; Represents the constant pi; in the above pure time delay phase compensation angle Under the premise of accurately compensating for the transmission delay phase between perturbation injection and flue gas concentration response, the above orthogonal phase-locked integral formula extracts the maximum projection component of the gradient variable in the perturbation direction; if there is a residual phase error, the orthogonal component needs to be calculated to synthesize the complete gradient magnitude.

[0103] In step S807, the digital orthogonal phase-locked demodulation module 630 sends the extracted gradient variables to the core processing unit of the central controller 600. The central controller 600 determines the polarity of the gradient variables and determines the opening correction direction of the main air regulating valve 210. The central controller 600 determines the absolute value of the gradient variables and determines the opening correction step size of the main air regulating valve 210. The central controller 600 outputs the corresponding correction control signal to the main air regulating valve 210, driving the air-fuel ratio parameter of the industrial furnace body 100 to converge towards the thermal efficiency extreme point.

[0104] After obtaining the gradient variable, the central controller executes the extreme value optimization feedback-driven logic based on the variable to complete the step-by-step dynamic correction of the wind-fuel ratio, and finally achieves adaptive optimization steady state. The specific execution steps are as follows:

[0105] Step S901: The digital quadrature phase-locked demodulation module 630 transmits the extracted gradient variables to the central controller 600. The central controller 600 reads the numerical polarity and absolute value of the gradient variables. The numerical polarity of the gradient variables represents the direction in which the current basic air-fuel ratio deviates from the point of highest combustion thermal efficiency, and the absolute value of the gradient variables represents the relative distance between the current basic air-fuel ratio and the point of highest combustion thermal efficiency.

[0106] Step S902: The central controller 600 stores a preset optimization dead zone threshold and a single-step adjustment step size parameter. The central controller 600 compares the absolute value of the gradient variable with the optimization dead zone threshold.

[0107] Step S903: If the absolute value of the gradient variable is less than or equal to the optimization dead zone threshold, the central controller 600 determines that the current combustion state is in the thermal efficiency extreme point region. The central controller 600 maintains the current basic flow regulation command of the main air regulating valve 210, and the basic air flow in the main air supply duct 120 remains constant.

[0108] Step S904: If the absolute value of the gradient variable is greater than the optimization dead zone threshold and the polarity of the gradient variable is positive, the central controller 600 determines that increasing the air flow can improve the thermal efficiency. The central controller 600 adds a single-step adjustment step size parameter to the value of the current basic flow adjustment command and generates a first correction control signal. The central controller 600 sends the first correction control signal to the main air regulating valve 210. The main air regulating valve 210 increases the flow cross-sectional area and increases the basic air flow in the main air supply duct 120.

[0109] Step S905: If the absolute value of the gradient variable is greater than the optimization dead zone threshold and the polarity of the gradient variable is negative, the central controller 600 determines that reducing the air flow can improve thermal efficiency. The central controller 600 subtracts the single-step adjustment step size parameter from the value of the current basic flow adjustment command to generate a second correction control signal. The central controller 600 sends the second correction control signal to the main air regulating valve 210. The main air regulating valve 210 reduces the flow cross-sectional area and reduces the basic air flow in the main air supply duct 120.

[0110] In step S906, after the main air regulating valve 210 performs the cross-sectional area adjustment action, the mixing ratio inside the burner 110 changes, and the actual air-fuel ratio parameter inside the industrial furnace body 100 approaches the extreme point of thermal efficiency.

[0111] Step S907: The central controller 600 reads the dynamic transmission delay time generated in the frequency conversion orthogonal phase-locked demodulation mechanism of the near-field flue gas spectrum. The central controller 600 sets a parameter update cycle with a time length greater than the dynamic transmission delay time. The central controller 600 triggers the digital orthogonal phase-locked demodulation module 630 to output the latest gradient variable in a cyclic manner according to the parameter update cycle, and repeatedly executes the above numerical comparison and valve opening correction actions. When the industrial furnace body 100 is in a continuous variable load operation condition, a closed-loop adaptive optimization steady state of the air-fuel ratio parameter is established.

[0112] The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis described in this invention can be widely applied to the fuel supply of thermal equipment such as chemical-specific heating furnaces, energy-saving industrial drying furnaces, metal smelting furnaces, and heat treatment furnaces. In the chemical industry, chemical-specific furnaces such as pyrolysis furnaces and conversion furnaces have extremely high requirements for the stability and distribution accuracy of fuel supply. This invention, through a dual-path fuel distribution structure with main and bypass paths and a piezoelectric jet micro-perturbation supply mechanism, can effectively suppress fuel supply fluctuations in chemical-specific furnaces, energy-saving drying furnaces, and melting furnaces under variable load conditions, thereby achieving energy saving and consumption reduction.

Claims

1. An energy-saving industrial gas-fired boiler air-fuel ratio adaptive control system based on flue gas analysis, characterized in that, include: The industrial furnace body (100), burner (110), main air supply duct (120), main gas supply duct (130), main air regulating valve (210), main gas regulating valve (220), piezoelectric jet perturbation valve (300), broadband flame detector (400), near-field high-speed gas sampling probe (510), TDLAS spectrometer (520) and central controller (600); The main gas supply pipeline (130) is divided into an upstream section and a downstream section. The main gas regulating valve (220) is connected between the upstream section and the downstream section and is used to regulate the basic gas flow cross-sectional area of ​​the main gas supply pipeline (130). A bypass gas pipe is installed in parallel outside the main gas supply pipeline (130). The two ends of the bypass gas pipe are respectively connected to the upstream end and the downstream end of the pipeline section where the main gas regulating valve (220) is located. A manual flow back pressure valve (304) and a piezoelectric jet micro-perturbation valve (300) are installed on the bypass gas pipe in sequence along the fluid advance direction. The manual flow back pressure valve (304) sets the maximum flow cross-sectional area boundary of the bypass gas pipe in physical structure. The piezoelectric jet perturbation valve (300) includes a piezoelectric ceramic stacked actuator (301), a mechanical amplification mechanism (302), and a micro-throttling valve core (303). The piezoelectric ceramic stacked actuator (301) receives a high-frequency drive signal to generate mechanical deformation. Its physical displacement output end is connected to the input end of the mechanical amplification mechanism (302). The mechanical amplification mechanism (302) drives the micro-throttling valve core (303) located in the fluid channel of the bypass gas pipe to perform high-frequency reciprocating motion, so as to continuously change the cross-sectional area of ​​the fluid channel of the bypass gas pipe, so that the gas flowing through the bypass gas pipe is converted into a high-frequency jet pulsating gas mass with a sinusoidal amplitude envelope, and flows into the downstream pipe section, superimposing a high-frequency perturbation fuel component on the basic gas flow rate output by the main gas regulating valve (220). The outlet end of the main air supply duct (120) and the outlet end of the main gas supply duct (130) are both connected to the fluid inlet of the burner (110). The main air regulating valve (210) is installed on the main air supply duct (120). The control end of the main air regulating valve (210) is electrically connected to the signal output end of the central controller (600) to receive basic air flow regulation commands and execute corresponding valve opening actions. The broadband flame detector (400) is installed on the side wall of the industrial furnace body (100), and the detection end of the broadband flame detector (400) is directly facing the root outlet position of the burner (110). The signal output end of the broadband flame detector (400) is electrically connected to the signal input end of the central controller (600) for real-time acquisition of the light intensity pulsation signal at the location of the burner (110) and transmission of the light intensity pulsation signal to the central controller (600). The industrial furnace body (100) has a burner wake region in its inner cavity. The burner wake region is located downstream of the main flame reaction zone. The near-field high-speed gas sampling probe (510) is installed on the industrial furnace body (100), and the sampling end of the near-field high-speed gas sampling probe (510) extends into the burner wake region. The output end of the near-field high-speed gas sampling probe (510) is connected to the gas inlet of the TDLAS spectrometer (520) through a sealed gas guide pipe. The digital signal output end of the TDLAS spectrometer (520) is electrically connected to the communication interface of the central controller (600) to output the instantaneous concentration signal of the target flue gas. The central controller (600) is an industrial computing control unit containing a processor and memory. The central controller (600) integrates a signal frequency domain analysis module (610), a frequency orthogonal synthesis module (620), and a digital orthogonal phase-locked loop demodulation module (630). The central controller (600) extracts the flame background noise frequency band based on the light intensity pulsation signal and calculates the dynamic perturbation frequency, generating the high-frequency drive signal and outputting it to the piezoelectric jet perturbation valve (300) to dynamically adjust the frequency and amplitude of the high-frequency jet pulsating air mass. The controller (600) also calculates the dynamic transmission delay time and generates a local reference signal containing a pure hysteresis phase compensation angle based on the instantaneous concentration signal and the dynamic perturbation frequency. It extracts gradient variables through orthogonal phase-locked demodulation and outputs a basic flow regulation command to the main air regulating valve (210) based on the gradient variables to regulate the basic air flow of the main air supply duct (120), so that the fuel and air ratio supplied to the burner (110) by the main air supply duct (130) and the main air supply duct (120) adaptively converges towards the thermal efficiency extreme point.

2. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The broadband flame detector (400) integrates an ultraviolet photosensitive sensor (401), an infrared photosensitive sensor (402), a signal conditioning and amplification circuit (403), a high-speed analog-to-digital conversion module (404), and a digital signal fusion unit (405). The ultraviolet photosensitive sensor (401) and the infrared photosensitive sensor (402) are arranged side by side, and the detection field of the ultraviolet photosensitive sensor (401) and the detection field of the infrared photosensitive sensor (402) together cover the root outlet position of the burner (110). The ultraviolet photosensitive sensor (401) and infrared photosensitive sensor (402) capture ultraviolet and infrared light signals, respectively, and convert them into analog micro-current signals. The signal conditioning and amplification circuit (403) performs anti-aliasing low-pass filtering and gain amplification on the analog micro-current signals and converts them into voltage fluctuation signals. The high-speed analog-to-digital conversion module (404) samples the voltage fluctuation signals at equal intervals and outputs discrete channel signals. The digital signal fusion unit (405) uses preset hardware weighting coefficients to linearly add the discrete amplitudes at the same time to generate and output a single-channel physical light intensity pulsation signal.

3. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The near-field high-speed gas sampling probe (510) includes an outer probe tube (511), an inner probe tube (512), a negative pressure pump (513), a porous sintered metal filter head (515), and a cooling water jacket (514). The probe inner tube (512) is nested inside the probe outer tube (511), and an annular cooling medium channel connecting the probe outer tube (511) and the probe inner tube (512) is formed between them to connect the cooling water jacket (514). The porous sintered metal filter head (515) is installed at the air inlet end of the probe inner tube (512) located inside the burner wake region to intercept solid particles in the flue gas cloud; the exhaust end of the probe inner tube (512) is connected to the air inlet of the negative pressure pump (513), the negative pressure pump (513) establishes a continuous directional negative pressure flow field inside the probe inner tube (512), and its exhaust port is connected to the gas inlet of the TDLAS spectrometer (520) through a sealed gas guide pipe.

4. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The main gas supply pipeline (130) is divided into an upstream section and a downstream section, and the main gas regulating valve (220) is connected between the upstream section and the downstream section; The bypass duct is sequentially equipped with a manual flow back pressure valve (304) and a piezoelectric jet perturbation valve (300) along the fluid advance direction. The manual flow back pressure valve (304) sets the maximum flow cross-sectional area boundary of the bypass duct in terms of physical structure. The piezoelectric jet perturbation valve (300) includes a piezoelectric ceramic stacked actuator (301), a mechanical amplification mechanism (302), and a micro-throttle valve core (303). The piezoelectric ceramic stacked actuator (301) receives the high-frequency drive signal and generates mechanical deformation. Its physical displacement output end is connected to the input end of the mechanical amplification mechanism (302). The mechanical amplification mechanism (302) drives the micro-throttle valve core (303) located in the fluid channel of the bypass trachea to perform high-frequency reciprocating motion to continuously change the cross-sectional area of ​​the fluid channel of the bypass trachea.

5. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The design diversion ratio of the bypass gas pipe is 3%-15% of the total gas flow of the main gas supply pipeline. The manual flow back pressure valve (304) sets the initial back pressure according to the design diversion ratio, so that the piezoelectric jet micro-perturbation valve (300) maintains the basic conduction cross-sectional area of ​​the bypass gas pipe in the state of zero drive signal. The bypass gas pipe is equipped with a swirling mixing nozzle at its outlet. After the high-frequency jet pulsating gas mass is ejected through the swirling mixing nozzle, it forms a circumferential rotating flow field in the downstream pipe section. It exchanges momentum and mixes mass with the steady-state gas flowing through the main gas regulating valve (220), so that the actual gas supply flow field in the downstream pipe section is reconstructed into a physical superposition flow field containing a steady-state DC fuel component and a high-frequency AC fuel component.

6. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 5, characterized in that, A mechanical interlock protection structure is provided between the manual flow back pressure valve (304) and the piezoelectric jet perturbation valve (300). When the piezoelectric jet perturbation valve (300) is in an uncontrolled fully open state due to an electrical fault, the physical structure cross-sectional area boundary of the manual flow back pressure valve (304) will limit the bypass gas flow below the safety threshold. The piezoelectric ceramic stacked actuator (301) is composed of multiple piezoelectric ceramic sheets stacked in series along the axial direction. The mechanical amplification mechanism (302) is a flexible hinge displacement amplification mechanism with a displacement amplification factor of 5-20 times. The micro-motion throttle valve core (303) is a conical valve core with a valve core stroke range of 0.02mm-0.5mm. The surface of the micro-motion throttle valve core (303) is treated with a hard alloy coating to resist gas erosion and wear.

7. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The signal frequency domain analysis module (610) specifically includes a data buffer register (611), a discrete Fourier transform processor (612), and a characteristic frequency band memory (613); The signal output terminal of the broadband flame detector (400) is connected to the signal input terminal of the data buffer register (611), the output terminal of the data buffer register (611) is connected to the input terminal of the discrete Fourier transform processor (612), and the output terminal of the discrete Fourier transform processor (612) is connected to the characteristic frequency band memory (613). The data buffer register (611) performs time windowing truncation on the physical light intensity pulsation signal to extract discrete time domain data frames. The discrete Fourier transform processor (612) performs discrete power spectral density estimation calculation on the discrete time domain data frames and performs spectral peak search logic to extract the center noise frequency and the corresponding harmonic frequencies, which are combined into the flame background noise frequency band and written into the characteristic frequency band memory (613).

8. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The frequency orthogonal synthesis module (620) specifically includes a frequency offset calculation unit (621) and a driving waveform generation unit (622); The signal receiving end of the frequency offset calculation unit (621) is connected to the characteristic frequency band memory (613) that extracts the flame background noise frequency band, the signal output end of the frequency offset calculation unit (621) is connected to the drive waveform generation unit (622), and the power output end of the drive waveform generation unit (622) is connected to the piezoelectric jet perturbation valve (300). The frequency offset calculation unit (621) reads the flame background noise frequency band and performs frequency orthogonal isolation calculation to establish the dynamic perturbation frequency. The drive waveform generation unit (622) synthesizes a sinusoidal AC voltage waveform based on the dynamic perturbation frequency, amplifies it, and converts it into the high-frequency drive voltage signal, which is then output to the piezoelectric jet perturbation valve (300).

9. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 8, characterized in that, The frequency offset calculation unit (621) searches for candidate frequencies within a preset effective hardware operating frequency band. The candidate frequencies meet the condition of maintaining a safe isolation width with all frequency components in the flame background noise frequency band. The frequency offset calculation unit (621) establishes the candidate frequency that meets the isolation width condition and has the smallest frequency value as the dynamic perturbation frequency. The alternating frequency of the high-frequency driving voltage signal output by the driving waveform generation unit (622) is equal to the dynamic perturbation frequency, and the peak voltage of the high-frequency driving voltage signal is less than or equal to the voltage amplitude limiting threshold corresponding to the basic gas flow command.

10. The energy-saving industrial gas furnace air-fuel ratio adaptive control system based on flue gas analysis according to claim 1, characterized in that, The digital quadrature phase-locked demodulation module (630) includes a hardware phase-locked loop unit (631), a quadrature reference signal generator (632), a multiplier array (633), and a low-pass integral filter (634); The TDLAS spectrometer (520) is connected to the signal input terminal of the digital quadrature phase-locked demodulation module (630), the frequency quadrature synthesis module (620) is connected to the input terminal of the hardware phase-locked loop unit (631), the hardware phase-locked loop unit (631) is connected to the quadrature reference signal generator (632), the quadrature reference signal generator (632) is connected to the multiplier array (633), and the multiplier array (633) is connected to the low-pass integral filter (634). The hardware phase-locked loop unit (631) tracks the phase characteristics of the dynamic perturbation frequency signal to establish a high-frequency synchronous clock. The quadrature reference signal generator (632) generates a sinusoidal reference waveform based on the high-frequency synchronous clock and generates a local reference signal containing a pure hysteresis phase compensation angle by combining the dynamic transmission delay time. The multiplier array (633) performs time-domain multiplication of the instantaneous concentration signal and the local reference signal to output a mixed-frequency modulation signal. The low-pass integral filter (634) performs integral filtering operation on the mixed-frequency modulation signal, extracts and outputs the gradient variable to the central controller (600) for closed-loop optimization correction of the wind-fuel ratio.

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