A flame detection system for a multi-nozzle burner and its detection method

Abstract

The present invention discloses a flame detection system for a multi-nozzle burner and its detection method, belonging to the technical field of electrical capacitance tomography (ECT). The sensor is composed of an electrode array distributed at the bottom of the burner nozzle. The electrode layout and sensitive field distribution are optimized. The capacitance data of the measured area is collected by using the capacitance sensor. Specifically, a voltage signal is applied to one electrode, and the remaining electrodes are grounded to obtain the capacitance values between each pair of electrodes; the above process is repeated for each electrode, and the capacitance values between all independent pairs of electrodes are measured in turn. The data acquisition system converts these capacitance values into digital signals recognizable by a computer, and then an image of the dielectric constant distribution in the combustion chamber is inversely obtained through an image reconstruction algorithm. The present invention has the characteristics of low cost, fast detection speed, high sensitivity, non-invasiveness and flexible detection method, and is suitable for real-time monitoring and imaging of the combustion chamber flame in industrial scenarios.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical capacitance tomography, and particularly relates to a flame detection system for a multi-nozzle burner and a detection method thereof. Background Art

[0002] The wide application of petrochemical and biomass fuels covers multiple industrial fields such as electric power, metallurgy, chemical industry, transportation, and food, becoming the main energy conversion form at present and in the future. The combustion process involves complex physical and chemical reactions. As the core area of combustion, the flame directly reflects the combustion conditions and contains key information on stability, thermal efficiency, and pollutant emissions. Accurately measuring the flame characteristic parameters is the key way to deeply understand the essence and laws of combustion and is also the basis for the optimal design of industrial combustion systems.

[0003] Currently, the flame detection methods in burners can be classified into optical method, thermal method, acoustic method, and electrical method according to the working principle. The optical method uses a photodetector to monitor the flame. This method can provide intuitive image information, but the optical components are easily affected by dust in the harsh industrial environment, resulting in unstable detection results. In addition, the optical method has high requirements for environmental light conditions and is not applicable to some specific industrial environments. The digital image method captures and analyzes the flame image through a camera. Although it can provide rich visual information, it is sensitive to noise, has low measurement accuracy, and is difficult to accurately identify the flame boundary in a complex background. The acoustic method uses the sound signal generated by the flame for monitoring. This method is simple and low-cost, but it has poor effects in a high-noise environment and cannot provide detailed flame distribution information.

[0004] Electrical capacitance tomography (ECT) is a non-invasive online detection technology for multiphase flows. It uses a capacitance sensor to collect capacitance data of the measured area and graphically displays the dielectric constant distribution of the measured area through the mapping relationship between capacitance values and dielectric constants. The number of electric dipoles generated by electronic polarization, ionic polarization, and orientation polarization in the flame may significantly change the dielectric constant distribution of the flame, and the degree of ionization is related to the combustion intensity at different positions in the flame. Therefore, the dielectric constant of the flame is closely related to the combustion intensity. Various charged particles are generated in the flame, including positive ions (such as CH 3 + , H 3 O + , NO + , H 2 O + ), and negative ions (such as free electrons). The concentration and position of these charged particles affect the dielectric constant distribution of the flame. Therefore, it is feasible to use electrical capacitance tomography (ECT) to reflect the combustion intensity distribution in the flame.

[0005] Although electrical capacitance tomography (ECT) technology has the characteristics of low cost, fast detection speed, high sensitivity, non-invasiveness, and flexible detection methods, and is suitable for flame monitoring and imaging in combustion chambers in industrial scenarios, the electrodes of traditional ECT sensors are often evenly arranged in a closed circular pipeline, which limits its application in multi-nozzle burners. The structure of multi-nozzle burners is complex, and the design of traditional ECT sensors is difficult to adapt to this special structure, thus affecting the detection accuracy and effect. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a flame detection system and its detection method for a multi-nozzle burner, which can achieve efficient and accurate detection of the flame distribution in the multi-nozzle burner, and has the characteristics of convenient operation, high detection efficiency, high detection accuracy, non-invasiveness, and flexible detection methods.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a flame detection sensor for a multi-nozzle burner, including a plurality of independent electrodes. Among them, the plurality of independent electrodes are distributed on the base of the multi-nozzle burner in the form of an electrode array. When a voltage signal is applied to one of the independent electrodes, the remaining independent electrodes are grounded. Mark the independent electrode to which the voltage signal is applied and the remaining grounded independent electrodes as the current electrode pair, and sequentially apply voltage signals to each independent electrode to obtain the capacitance value between the corresponding electrode pairs of each independent electrode;

[0009] Invert the dielectric constant distribution map of the combustion chamber according to the capacitance value, and determine the flame distribution characteristics through the dielectric constant distribution map.

[0010] In the second aspect, the present invention provides a flame detection method for a multi-nozzle burner, including:

[0011] Step 1: Apply a voltage signal to an independent electrode in the electrode array of the flame detection system through a signal generator, and the remaining independent electrodes are grounded. The capacitance measurement module measures the capacitance value between the independent electrode to which the voltage signal is applied and other independent electrodes, and records it as the current electrode pair. Repeat the above process, sequentially apply voltage signals to each independent electrode, and measure the capacitance values between all independent electrode pairs;

[0012] Step 2: The signal conversion circuit of the data acquisition and processing device converts the measured capacitance value into a digital signal recognizable by a computer, amplifies it through a signal amplification circuit and sends it to the visualization image reconstruction unit; the visualization image reconstruction unit calculates the electric field sensitivity matrix, and calculates the sensitivity field of each layer under the corresponding electrode pair channel through finite element simulation software;

[0013] Step 3: Use the image reconstruction algorithm in the visualization image reconstruction unit to inversely obtain the image of the dielectric constant distribution in the combustion chamber;

[0014] Step 4: Determine the flame distribution in the multi-nozzle burner by analyzing the image reconstruction results.

[0015] In a third aspect, the present invention provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the foregoing flame detection system for a multi-nozzle burner and its detection method.

[0016] In a fourth aspect, the present invention provides a computer-readable storage medium, on which executable instructions are stored, and when the instructions are executed by a processor, the processor can be caused to implement the foregoing flame detection system for a multi-nozzle burner and its detection method.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. Non-invasive: It does not need to contact the flame and will not interfere with the combustion process, and is applicable to various industrial environments;

[0019] 2. High detection efficiency: Using capacitance tomography technology, the data acquisition speed is fast, and the flame state can be monitored in real time;

[0020] 3. High detection accuracy: By optimizing the electrode layout and advanced image reconstruction algorithm, the accuracy of the detection results is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of a flame detection system for a multi-nozzle burner according to the present invention;

[0022] Figure 2 It is a flowchart of a flame detection method for a multi-nozzle burner according to the present invention.

[0023] Reference Signs:

[0024] 1. Multi-nozzle burner; 2. Burner metal base; 3. Arc electrode; 4. Connecting wire; 5. Data acquisition and processing device; 6. Visualization image reconstruction unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be further described below with reference to the drawings and embodiments.

[0026] The present invention provides a flame detection sensor for a multi-nozzle burner, and the sensors are distributed at the bottom of the burner nozzles.

[0027] Such as Figure 1As shown in the figure, the flame detection system includes a multi-nozzle burner 1, a data acquisition and processing device 5, and a visualization image reconstruction unit 6 that are connected in sequence. Among them, the multi-nozzle burner 1 includes a flame detection sensor, and the flame detection sensors are distributed in the form of an electrode array on the burner metal base 2. The electrode array includes a plurality of independent electrodes. When a voltage signal is applied to one of the electrodes, the remaining electrodes are grounded. Mark the electrode to which the voltage signal is applied and the remaining grounded electrodes as the current electrode pair. By applying voltage signals to each independent electrode in sequence, the capacitance values between the corresponding electrode pairs of each independent electrode can be obtained. By optimizing the electrode layout, it is ensured that the electrodes can effectively cover the key areas inside the burner, improving the detection accuracy. The data acquisition and processing device 5 is connected to the electrode array of the flame detection sensor through a connection line 4, and is used to generate excitation and detection signals for the electrode array, and sequentially collect the capacitance values between the electrode pairs. The data acquisition and processing device 5 includes a signal generator, a capacitance measurement module, a signal conversion circuit, a signal amplification circuit, and a signal acquisition circuit.

[0028] The visualization image reconstruction unit 6 is connected to the data acquisition and processing device 5, and is used to receive the digital signal and inversely obtain an image of the dielectric constant distribution in the combustion chamber through an image reconstruction algorithm. The visualization image reconstruction unit 6 includes a computer, which has the capabilities of signal acquisition and image reconstruction, and is used to process the digital signal sent by the data acquisition and processing device, and inversely obtain an image of the dielectric constant distribution in the combustion chamber through an image reconstruction algorithm.

[0029] Furthermore, the electrode array adopts an asymmetric arc layout. The radian of the electrode array is the same as the curvature of the nozzle outlet, and the axial coverage range of the electrode array is 1 / 4 to 1 / 3 of the circumference of the nozzle outlet.

[0030] As Figure 2 shown in the figure, on the other hand, the present invention proposes a flame detection method according to the above detection system. The detection method sequentially realizes the reconstruction of the flame distribution in the multi-nozzle burner through the steps of data acquisition, information processing, image reconstruction, and data analysis, and specifically includes the following steps:

[0031] Step 1: Data acquisition;

[0032] A voltage signal is applied to one of the electrodes in the electrode array of the flame detection sensor by the signal generator, and the remaining electrodes are grounded. The capacitance measurement module measures the capacitance value between the electrode to which the voltage signal is applied and the other electrodes. Mark the electrode to which the voltage signal is applied and the remaining grounded electrodes as the current electrode pair. By repeating the foregoing process, the capacitance values between the corresponding electrode pairs of each independent electrode can be obtained, and the capacitance values between the corresponding electrode pairs of each independent electrode are measured.

[0033] Step 2: Information processing;

[0034] The signal conversion circuit of the data acquisition and processing device converts the measured capacitance value into a digital signal recognizable by a computer, amplifies it through the signal amplification circuit and sends it to the visualization image reconstruction unit. The computer in the visualization image reconstruction unit calculates the electric field sensitivity matrix, divides it into L layers evenly along the Z direction by the finite element simulation method, and sequentially runs to calculate the sensitivity fields of each layer corresponding to the electrode pair channels.

[0035] Step 3: Image reconstruction;

[0036] The computer in the visualization image reconstruction unit inversely obtains the image of the dielectric constant distribution in the combustion chamber by using an image reconstruction algorithm (such as the Landweber iterative algorithm or the Tikhonov regularization method).

[0037] Step 4: Data analysis;

[0038] By analyzing the image reconstruction results, the flame distribution in the multi-nozzle burner is determined. The image reconstruction results clearly show the significant contrast difference between the flame position and other regions, providing the shape of the flame existence position.

[0039] In a preferred embodiment, by optimizing the electrode layout, it is ensured that the electrodes can effectively cover the key areas in the burner, improving the detection accuracy. Specifically, the number and layout of the electrodes in the electrode array can be adjusted according to the structure of the actual burner to adapt to different types of burners. In a preferred embodiment of the present invention, the electrode array adopts an arc-shaped electrode design. This arc-shaped electrode can better adapt to the geometry of the multi-nozzle burner, thereby obtaining a more uniform electric field distribution and higher sensitivity. The design of the arc-shaped electrode takes into account the hydrodynamic characteristics inside the burner, enabling the electrodes to more effectively capture the dielectric constant changes generated by the flame. For example, in a specific embodiment, the electrode array can be composed of 9 arc-shaped electrodes. Among them, the central nozzle is the key observation object, and 3 arc-shaped electrodes are arranged. Each electrode is not connected, and the remaining nozzles are each arranged with an arc-shaped electrode, jointly constituting the sensor electrode array. These electrodes are evenly distributed at the bottom of the burner nozzle, forming a circular or arc-shaped electrode array. This electrode layout method can realize three-dimensional image reconstruction and has good measurement accuracy in reflecting the position information of the measured working medium. At the same time, the non-invasive arrangement method of the electrodes simplifies the sensor installation and maintenance process.

[0040] The data acquisition and processing device converts the measured capacitance value into a digital signal recognizable by a computer and sends it to the visualization image reconstruction unit. The computer in the visualization image reconstruction unit calculates the electric field sensitivity matrix and, through the finite element simulation method, calculates the sensitivity fields of all grids under the corresponding electrode pairs. Specifically, the electric field sensitivity matrix S represents the sensitivity of the capacitance value between electrode pairs to the change in the dielectric constant of the medium and can be calculated through the finite element analysis method.

[0041] In a specific embodiment, the finite element simulation method can be used to calculate the electric field sensitivity matrix. By establishing a three-dimensional model inside the burner, setting the electrode positions and boundary conditions, the simulation software can calculate the electric field distribution under each electrode pair, thereby obtaining the electric field sensitivity matrix S.

[0042] The computer in the visualization image reconstruction unit uses an image reconstruction algorithm (such as the Landweber iterative algorithm or the Tikhonov regularization method, etc.) to inversely obtain an image of the dielectric constant distribution inside the combustion chamber. Specifically, the goal of the image reconstruction algorithm is to solve for the dielectric constant distribution of the medium through the known capacitance value and sensitivity matrix. The commonly used image reconstruction algorithms are as follows:

[0043] Landweber iterative algorithm: Initially set the dielectric constant distribution ; iteratively calculate through the sensitivity matrix S and the capacitance measurement value C , being the iteration step size, and repeat the calculation until the convergence condition is met.

[0044] Tikhonov regularization method: construct the objective function , where is the identity matrix; is the regularization parameter; by solving the minimization problem , obtain the optimal dielectric constant distribution.

[0045] In a specific embodiment, the Landweber iterative algorithm can be selected as the image reconstruction algorithm. Initially set the dielectric constant distribution to be a uniform distribution, and update the dielectric constant distribution through multiple iterations until the preset convergence condition is reached. During the iteration process, an appropriate step size factor α can be set to ensure the convergence speed and stability of the algorithm.

[0046] In a third aspect, the present invention provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the foregoing flame detection method for a multi-nozzle burner.

[0047] Fourthly, the present invention provides a computer-readable storage medium, on which executable instructions are stored. When the instructions are executed by a processor, the processor can implement the foregoing flame detection method for a multi-nozzle burner.

[0048] The specific embodiments described above further elaborate on the object, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flame detection system for a multi-nozzle burner, characterized in that: It comprises a plurality of independent electrodes, wherein: The multiple independent electrodes are evenly distributed at the bottom of the burner nozzle to form an arc-shaped electrode array, the electrode array adopts an asymmetric arc layout, the arc of the electrode array is the same as the curvature of the nozzle outlet, and the axial measurement coverage range of the electrode array is 1 / 4 to 1 / 3 of the circumference of the nozzle outlet; when a voltage signal is applied to one of the independent electrodes, the remaining independent electrodes are grounded, and the independent electrode applied with the voltage signal and the remaining grounded independent electrodes are marked as the current electrode pair, and the voltage signal is applied to each independent electrode in turn to obtain the capacitance value between the electrode pairs corresponding to each independent electrode; A combustion chamber dielectric constant distribution diagram is obtained by inverting the capacitance value, and flame distribution characteristics are determined by the dielectric constant distribution diagram.

2. A flame detection system for a multi-nozzle burner according to claim 1, characterized in that: The measured capacitance value is converted into a digital signal recognizable by a computer through a data acquisition and processing device, and sent to a visualization image reconstruction unit to obtain an image of the dielectric constant distribution in the combustion chamber.

3. A flame detection system for a multi-nozzle burner according to claim 2, characterized in that: The data acquisition and processing device includes a signal generator, a capacitance measurement module, a signal conversion circuit, a signal amplification circuit, and a signal acquisition circuit.

4. A flame detection system for a multi-nozzle burner according to claim 2, characterized in that: The computer in the visualization image reconstruction unit calculates the electric field sensitivity matrix, calculates the sensitivity field of all grids under the corresponding electrode pair through finite element simulation software, and obtains the image of the dielectric constant distribution in the combustion chamber through inversion using the image reconstruction algorithm.

5. A flame detection system for a multi-nozzle burner according to claim 4, characterized in that: The image reconstruction algorithm includes a Landweber iterative algorithm or a Tikhonov regularization method.

6. A flame detection method for a multi-nozzle burner, applied to a flame detection system for a multi-nozzle burner according to any one of claims 1 to 5, characterized in that: include: Step 1: A voltage signal is applied to an independent electrode in the electrode array of the flame detection system through a signal generator, and the other independent electrodes are grounded. The capacitance measurement module measures the capacitance value between the independent electrode to which the voltage signal is applied and other independent electrodes, and marks them as the current electrode pair. The above process is repeated, and the voltage signal is applied to each independent electrode in turn, and the capacitance value between all independent electrode pairs is measured; Step 2: The signal conversion circuit of the data acquisition and processing device converts the measured capacitance value into a digital signal recognizable by a computer, amplifies it through a signal amplification circuit and sends it to a visualization image reconstruction unit; the visualization image reconstruction unit calculates the electric field sensitivity matrix, and calculates the sensitivity field of the corresponding electrode to each layer under the channel through finite element simulation software; Step 3: In the visualization image reconstruction unit, an image of the dielectric constant distribution in the combustion chamber is obtained by inverting using an image reconstruction algorithm; Step 4: Determine the flame distribution in the multi-nozzle burner by analyzing the image reconstruction results.

7. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the flame detection method for a multi-nozzle burner as described in claim 6.

8. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by the processor, the processor can implement the flame detection method for a multi-nozzle burner as described in claim 6.

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