Flame detection system for multi-nozzle burner and detection method thereof

Abstract

The invention discloses a flame detection system for a multi-nozzle burner and a detection method of the flame detection system, and belongs to the technical field of electrical capacitance tomography (ECT). The sensor is composed of an electrode array distributed at the bottom of a burner nozzle, electrode layout and sensitive field distribution are optimally designed, capacitance data of a measured area are collected by a capacitance sensor, and specifically, capacitance values between electrode pairs are obtained by applying a voltage signal to one electrode and grounding other electrodes; and repeating the process on each electrode, and sequentially measuring the capacitance values between all the independent electrode pairs. The data acquisition system converts the capacitance values into digital signals which can be identified by a computer, and then an image of dielectric constant distribution in the combustion chamber is obtained through inversion of an image reconstruction algorithm. The method has the characteristics of low cost, high detection speed, high sensitivity, non-invasiveness and flexible detection mode, and is suitable for real-time monitoring and imaging of the flame of the combustion chamber in an industrial scene.

Description

Technical Field

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

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

[0003] At present, the flame detection methods in burners can be divided into optical, thermal, acoustic and electrical methods according to their working principles. 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 harsh industrial environments, resulting in unstable detection results. In addition, the optical method has high requirements for ambient light conditions and is not suitable for certain 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 under complex backgrounds. The acoustic method uses the sound signal generated by the flame for monitoring. This method is simple and low-cost, but it does not work well in high-noise environments and cannot provide detailed flame distribution information.

[0004] Capacitance tomography (ECT) is a non-invasive multiphase flow online detection technology that uses a capacitive 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 the capacitance value and the dielectric constant. The number of electric dipoles generated by electronic polarization, ionization 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 reflect the combustion intensity distribution in the flame by using electrical capacitance tomography (ECT).

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

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

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

[0008] In a first aspect, the present invention provides a flame detection sensor for a multi-nozzle burner, comprising a plurality of independent electrodes, wherein the plurality of independent electrodes are distributed on a multi-nozzle burner base 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, the independent electrode to which the voltage signal is applied and the remaining grounded independent electrodes are marked as a current electrode pair, and a voltage signal is applied to each independent electrode in turn to obtain a capacitance value between the electrode pairs corresponding to each independent electrode;

[0009] 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.

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

[0011] 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 the other independent electrodes, and records it as the current electrode pair. Repeat the above process, apply the voltage signal to each independent electrode in turn, and measure the capacitance value 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 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;

[0013] 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;

[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 comprising: 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 aforementioned flame detection system and detection method for a multi-nozzle burner.

[0016] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned flame detection system and detection method for a multi-nozzle burner.

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

[0018] 1. Non-invasive: No need to contact with flames, will not interfere with the combustion process, suitable for various industrial environments;

[0019] 2. High detection efficiency: It adopts capacitance tomography technology, with fast data acquisition speed and can monitor the flame status in real time;

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

[0021] Figure 1 This 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 The present invention is a flowchart of a flame detection method for a multi-nozzle burner.

[0023] Reference numerals:

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

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] The invention provides a flame detection sensor for a multi-nozzle burner. The sensor is distributed at the bottom of the burner nozzle.

[0027] like Figure 1As shown, the flame detection system includes a multi-nozzle burner 1, a data acquisition and processing device 5 and a visual image reconstruction unit 6 connected in sequence; wherein, the multi-nozzle burner 1 includes a flame detection sensor, and the flame detection sensor is distributed on the burner metal base 2 in the form of an electrode array, and 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, and the electrode to which the voltage signal is applied and the remaining grounded electrodes are marked as the current electrode pair. By applying a voltage signal to each independent electrode in sequence, the capacitance value between the electrode pairs corresponding to each independent electrode can be obtained. By optimizing the electrode layout, it is ensured that the electrodes can effectively cover the key areas in the burner and improve the detection accuracy; the data acquisition and processing device 5 is connected to the electrode array of the flame detection sensor through a connecting line 4, and is used to generate excitation and detection signals for the electrode array, and sequentially collect the capacitance values ​​between each electrode pair. 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 visual image reconstruction unit 6 is connected to the data acquisition and processing device 5, and is used to receive the digital signal and obtain an image of the dielectric constant distribution in the combustion chamber through an image reconstruction algorithm. The visual image reconstruction unit 6 includes a computer, which has signal acquisition and image reconstruction capabilities, and is used to process the digital signal sent by the data acquisition and processing device, and 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 arc 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] like Figure 2 As shown, on the other hand, the present invention proposes a flame detection method according to the above detection system, which realizes the reconstruction of the flame distribution in the multi-nozzle burner through data acquisition, information processing, image reconstruction and data analysis steps in sequence, and specifically includes the following steps:

[0031] Step 1: Data collection;

[0032] A voltage signal is applied to one electrode in the electrode array of the flame detection sensor through a signal generator, and the other 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. The electrode to which the voltage signal is applied and the other grounded electrodes are marked as the current electrode pair. By repeating the above process, the capacitance value between the electrode pairs corresponding to each independent electrode can be obtained, and the capacitance value between the electrode pairs corresponding to each independent electrode can be 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 the computer, which is amplified by the signal amplification circuit and sent to the visualization image reconstruction unit. The computer in the visualization image reconstruction unit calculates the electric field sensitivity matrix, which is evenly divided into L layers along the Z direction by the finite element simulation method, and then runs the calculation of the sensitivity field of each layer under the channel of the corresponding electrode pair in sequence.

[0035] Step 3: Image reconstruction;

[0036] The computer in the visualization image reconstruction unit uses an image reconstruction algorithm (such as the Landweber iterative algorithm or the Tikhonov regularization method) to invert and obtain an image of the dielectric constant distribution in the combustion chamber.

[0037] Step 4: Data analysis;

[0038] The flame distribution in the multi-nozzle burner is determined by analyzing the image reconstruction results. The image reconstruction results clearly show the significant contrast difference between the flame position and other areas, and provide the shape of the flame location.

[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 and improve the detection accuracy. Specifically, the number and layout of 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 electrode design. This arc electrode can better adapt to the geometric shape of the multi-nozzle burner, thereby obtaining a more uniform electric field distribution and higher sensitivity. The design of the arc electrode takes into account the fluid dynamics inside the burner, so that the electrode can 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 electrodes, wherein the central nozzle is used as the key observation object, and 3 arc electrodes 3 are arranged, each electrode is not connected, and the remaining nozzles are each arranged with an arc electrode 3, which together constitute a sensor electrode array. These electrodes are evenly distributed at the bottom of the burner nozzle to form a ring or arc 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 fluid. At the same time, the non-invasive arrangement of 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 visual image reconstruction unit. The computer in the visual image reconstruction unit calculates the electric field sensitivity matrix and calculates the sensitivity field of all grids under the corresponding electrode pair through the finite element simulation method. Specifically, the electric field sensitivity matrix S represents the sensitivity of the capacitance value between the electrode pairs to the change of the dielectric constant of the medium, which can be calculated by the finite element analysis method.

[0041] In a specific embodiment, a 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 position 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) to invert and obtain an image of the dielectric constant distribution in the combustion chamber. Specifically, the goal of the image reconstruction algorithm is to solve the dielectric constant distribution of the medium through the known capacitance value and sensitivity matrix. Commonly used image reconstruction algorithms are as follows:

[0043] Landweber Iteration Algorithm: Initial Setting of Dielectric Constant Distribution ; Iterative calculation through sensitivity matrix S and capacitance measurement value C , is the iterative step size, and the calculation is repeated until the convergence condition is met.

[0044] Tikhonov Regularization Method: Constructing the Objective Function ,in, is the identity matrix; is the regularization parameter; by solving the minimization problem , and obtain the optimal dielectric constant distribution.

[0045] In a specific embodiment, the Landweber iterative algorithm can be selected as the image reconstruction algorithm. Initial setting of dielectric constant distribution In order to achieve uniform distribution, the dielectric constant distribution is updated 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, comprising: 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 aforementioned flame detection method for a multi-nozzle burner.

[0047] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned flame detection method for a multi-nozzle burner.

[0048] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in 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 plurality of independent electrodes are distributed on the multi-nozzle burner base in the form of an electrode array, when a voltage signal is applied to one of the independent electrodes, the other independent electrodes are grounded, the independent electrode to which the voltage signal is applied and the other grounded independent electrodes are marked as a current electrode pair, and a voltage signal is applied to each independent electrode in turn to obtain a 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 1, characterized in that: The plurality of independent electrodes are evenly distributed at the bottom of the burner nozzle to form a ring-shaped or arc-shaped electrode array.

5. 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.

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

7. A flame detection system for a multi-nozzle burner according to claim 4, characterized in that: 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 coverage range of the electrode array is 1 / 4 to 1 / 3 of the circumference of the nozzle outlet.

8. A flame detection method for a multi-nozzle burner, 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.

9. 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 any one of claim 8.

10. 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 any one of claim 8.

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