Particle drying process state diagnosis system and method based on fusion of ultrasound, pressure and electrical tomography

Abstract

A particle drying process state diagnosis system based on fusion of ultrasound, pressure and electrical tomography comprises a multi-mode sensor module which integrates various sensors, synchronously collects acoustic, pressure and dielectric / conductivity distribution signals, and suppresses signal interference through frequency band separation filtering. And the data fusion processing module is used for analyzing and processing the acquired signals and establishing a dynamic correlation model of the void ratio, the humidity, the flow state and the flow pattern. And the real-time regulation and control module is used for adaptively regulating the inlet temperature, the wind speed and the particle retention time of the fluidized bed according to the multi-dimensional parameters output by the model so as to realize online optimization control of the drying process. Through a multi-physical-quantity complementary collaborative diagnosis mechanism, the defects of a single imaging mode are overcome, the accuracy of state diagnosis and the effectiveness of regulation and control in the particle drying process are effectively improved, and a reliable monitoring and control means is provided for the industrial particle drying process.

Description

Technical Field

[0001] The present invention relates to measurement methods and process control, and particularly to a system and method for diagnosing the state of a particle drying process based on the fusion of ultrasonic, pressure, and electrical tomography. Background Art

[0002] The fluidized bed particle drying process mainly involves fluidizing solid particle preparations with hot air to enable full contact between the particles and the hot air, thereby completing the evaporation of moisture. It is mainly applied in the pharmaceutical, chemical, energy, and food industries and belongs to a typical multiphase flow system. There are many adjustable variables involved in the process, among which particle humidity is an important parameter of the process. The quality of the final product of the process is closely related to the operating conditions of the fluidization process, the gas-solid flow state and gas-solid concentration distribution inside the reactor, and the change of flow patterns, etc. To design an industrial particle fluidized dryer and perform performance prediction and large-scale design on existing reactors, it is necessary to conduct online detection of key parameters for the above complex flow characteristics. However, currently, the optimization and control of fluidized bed drying reactors still rely on the experience of operators and a single experiment. The process detection in this field far from meets the requirements of industrial process optimization and process control.

[0003] In recent years, well-known companies in the international pharmaceutical field, including AstraZeneca in Sweden, Pfizer in the United States, GSK in the United Kingdom, etc., pharmaceutical equipment development enterprises such as Glatt and GEA in Germany, and DowDuPont in the United States have all begun to focus on the research of process detection of fluid flow in the particle drying process, and use non-invasive measurement tools, such as electrical tomography technologies (capacitance, resistance, microwave, etc.) to conduct visualization research on internal flow, etc., but it is still limited to single-modal test research.

[0004] Electrical tomography technology is a process parameter measurement technology developed in recent years and has gradually begun to be applied in fields such as chemical engineering, energy, food, and oil and gas. Compared with traditional measurement means, electrical tomography technology has the advantage of being non-invasive and can directly image the internal distribution of the fluid. Common electrical tomography technologies include Magnetic Resonance Imaging - MRI, Electrical Resistance Tomography - ERT, Electrical Capacitance Tomography - ECT, Microwave Tomography - MWT, etc.

[0005] Electrical capacitance tomography is a visualization measurement technique that infers the distribution of the dielectric constant in the space of the measured medium based on the capacitance values measured between each pair of electrodes around the measured area. Due to its characteristics such as simple structure, non-radiation, fast imaging speed, and low cost, it is often applied to the monitoring of oil pipeline flow and fluidized bed particle flow.

[0006] Resistance capacitance tomography is a visualization measurement technique that infers the distribution of the conductivity in the space of the measured medium based on the current measured between each pair of electrodes around the measured area. Due to its characteristics such as simple structure, non-radiation, fast imaging speed, and low cost, it is often applied to the monitoring of oil-water two-phase pipeline flow and the inside of reactors.

[0007] Microwave tomography is a non-contact measurement technique. Its principle is to irradiate the object to be measured with microwaves, and then reconstruct the complex dielectric constant distribution of the object based on the measured values of the external scattering field of the object, so as to infer the concentration distribution of the object. The complex dielectric constant can usually be expressed as: ε = ε’ - iε”, where the real part has the same meaning as the real dielectric constant, the imaginary part can be equivalently characterized as the conductance of the dielectric, ε is the complex dielectric constant, ε’ is the real part of the dielectric constant, ε” is the imaginary part of the dielectric constant, and i is the imaginary unit. At room temperature, the imaginary part of the complex dielectric constant of water is relatively large, about 40, while the values of common granular media such as river sand and pulverized coal under dry conditions are all less than 1. Using this feature and combining the real part information of the complex dielectric constant, the humidity distribution of the medium can be calculated based on microwave tomography.

[0008] The multi-modal tomography fusion technology refers to the method of measuring a certain object simultaneously with multiple imaging methods, such as the fusion of ECT and ERT. This technology can achieve the functional complementarity of different measurement methods.

[0009] Monitoring and regulating the multiphase flow characteristics inside the fluidized bed particle drying system can directly reflect whether the system design is reasonable and whether it can meet the requirements of large-scale and continuous production in the industrial process. In order to effectively detect and regulate the fluidized bed particle drying process, advanced measurement methods and visualization measurement means are needed to effectively detect the reaction process, optimize the process operation parameters, balance the system operation parameters and particle state parameters in the granulation process, and provide on-line detection methods and means for the particle preparation process.

[0010] So far, there is still a lack of effective process diagnosis and flow state measurement tools to measure the above parameters. The reaction end point is determined by multiple “differential methods”. Most of the actually operating fluidized bed dryers are in a “black box” state. It is difficult to effectively reveal the gas-solid flow characteristics and the regulation mechanism of the reaction process from the root cause of the problem, and thus it is impossible to effectively monitor the internal process, resulting in problems such as low system operation efficiency and high energy consumption.

[0011] Most of the existing fluidized bed particle drying control schemes are based on the measurement of single variables such as system pressure, humidity, and temperature. The acquisition of particle flow state information is limited, and it is difficult to accurately control the flow regime and flow pattern of the particle drying process. The application of electrical capacitance tomography in the fluidized bed particle drying process is relatively common. For example, ECT and MWT have been applied to the monitoring of the particle drying process. The design of CN1569322A is the fusion of a single capacitance sensor and a pressure signal respectively, while WO / 2009 / 030876 uses a single capacitance sensor to obtain the parameter changes in the fluidized bed particle drying process. ZL200510122587.4 combines two imaging modes of ECT and ERT, but is only limited to the measurement of process parameters, without process regulation, and does not fuse ultrasonic, pressure, and electrical capacitance tomography for testing.

[0012] At present, the defects of capacitance tomography measurement applied to the fluidized bed particle preparation process: when the humidity of the object to be measured is relatively high, it will exceed the range of the data acquisition system. In addition, at this time, the electrical properties of the measured substance are close to those of a conductor, and charges cannot be stored, so capacitance measurement cannot be carried out. Therefore, the ECT device cannot measure substances with relatively high humidity. The defects of microwave tomography measurement: the imaging rate is slow, up to 30 frames per second at most. The defects of electrical resistance tomography: when the particle humidity is low, the conductivity is extremely low, and current signals cannot be obtained.

[0013] It should be noted that the information disclosed in the above background art section is only used for understanding the background of the present application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0014] The main object of the present invention is to overcome the defects existing in the above background art, and provide a system and method for diagnosing the state of a particle drying process based on the fusion of ultrasonic, pressure, and electrical capacitance tomography.

[0015] To achieve the above object, the present invention adopts the following technical solutions:

[0016] A system for diagnosing the state of a particle drying process based on the fusion of ultrasonic, pressure, and electrical capacitance tomography, comprising:

[0017] A multi-modal sensor module, integrating ultrasonic sensors, pressure sensors, and electrical capacitance tomography sensors, for synchronously collecting acoustic signals, dynamic pressure fluctuations, and dielectric / conductivity distribution signals of particles during the fluidized bed drying process. Among them, the electrical capacitance tomography sensors include at least two of capacitance tomography (ECT) sensors, electrical resistance tomography (ERT) sensors, and microwave tomography (MWT) sensors, and signal cross-interference is suppressed by frequency band separation filtering;

[0018] A data fusion processing module, configured to perform humidity inversion analysis on the acoustic signal, extract flow state characteristics from the dynamic pressure signal, perform image reconstruction on the dielectric / conductivity distribution signal to obtain the particle concentration distribution, and establish a dynamic correlation model of void fraction, humidity, flow state and flow pattern through multi-modal data collaborative fusion;

[0019] A real-time regulation module, based on the multi-dimensional parameters output by the dynamic correlation model, adaptively adjusts the inlet temperature, wind speed and particle residence time of the fluidized bed to achieve online optimal control of the drying process;

[0020] Among them, the measurement blind area of electrical capacitance tomography in high humidity scenarios is compensated by ultrasonic signals, the detection failure of resistance tomography for low conductivity particles is compensated by microwave tomography, and the flow state identification ability is enhanced by the time-frequency analysis of pressure signals, forming a collaborative diagnosis mechanism with complementary multi-physical quantities; preferably, the multi-modal sensor module is arranged non-intrusively along the longitudinal direction of the fluidized bed.

[0021] Furthermore, the electrical capacitance tomography sensor includes a capacitance tomography (ECT) sensor and a microwave tomography (MWT) sensor, where:

[0022] The electrodes of the ECT sensor are made of copper sheets with a thickness of 0.3 - 0.5 mm, fixed on the surface of the non-conductive material along the outer wall of the fluidized bed with pressure-sensitive tape, and the electrode coverage rate is 80%;

[0023] The working frequency range of the MWT sensor is 10 kHz - 500 kHz, and the complex dielectric constant distribution of particles is measured through the microwave scattering field;

[0024] The outer layer of the electrical capacitance tomography sensor is coated with a grounded flexible copper sheet as an electromagnetic shielding layer with a thickness of 0.3 - 0.5 mm.

[0025] Furthermore, the arrangement method of the multi-modal sensor module is:

[0026] The ultrasonic sensor is fixed on the side wall of the top of the fluidized bed through NPT threads, and the working frequency band is 100 - 500 Hz, used to capture particle collision sound signals;

[0027] The pressure sensors are respectively installed at the top and bottom of the fluidized bed, and the dynamic pressure fluctuation is measured through the pressure difference;

[0028] The electrical capacitance tomography sensors are evenly distributed circumferentially along the outer wall of the same cross-section of the fluidized bed, and the electrode spacing is adaptively adjusted based on the diameter of the fluidized bed.

[0029] Furthermore, the signal separation unit of the data fusion processing module includes:

[0030] A low-pass filter with a cut-off frequency of 2 kHz is used to extract the low-frequency components of the pressure signal and the ultrasonic signal;

[0031] A cascaded high-pass filter with a cut-off frequency of 10 kHz is used to separate the high-frequency signals of electrical capacitance tomography;

[0032] The signal separation unit suppresses the cross-interference of multimodal signals through frequency band isolation.

[0033] Furthermore, the image reconstruction unit of the electrical capacitance tomography sensor is configured as follows:

[0034] Reconstruct the porosity image of the particle concentration distribution based on electrical capacitance tomography (ECT);

[0035] Calculate the imaginary part of the complex dielectric constant based on the inversion algorithm of microwave tomography (MWT) and correlate the particle humidity distribution;

[0036] Fuse the imaging data of ECT and MWT to generate a multi-parameter dynamic distribution map.

[0037] Furthermore, the fluidized bed reactor is made of plexiglass or plastic with a thickness of 0.3 - 0.8 cm, and the cross-section is conical or rectangular; the width of the outer shielding copper sheet of the electrical capacitance tomography sensor is 2 - 3 cm greater than the electrode height and is isolated from the outer wall of the fluidized bed by a plexiglass plate with a thickness of 0.5 cm.

[0038] Furthermore, the real-time regulation module is configured as follows:

[0039] Based on the porosity, humidity, and fluidization state parameters output by the dynamic correlation model, adjust the inlet temperature, wind speed, and particle residence time of the fluidized bed in real time;

[0040] Capture the fluidization state evolution through the imaging rate of hundreds of frames per second of electrical capacitance tomography, and trigger the regulation instruction in combination with the time-frequency analysis result of the pressure signal.

[0041] Furthermore, the system also includes a temperature sensor installed at the outlet of the fluidized bed to monitor the humidity of the fluidizing air; the data fusion processing module establishes a quantitative mapping relationship between the porosity, fluidization wind speed, inlet / outlet temperature, and fluidization state change through multimodal fusion.

[0042] A method for diagnosing the state of the particle drying process using the system includes the following steps:

[0043] (a) Synchronously collect the dielectric / conductivity distribution signals through the electrical capacitance tomography sensor, and generate the particle concentration and humidity distribution maps using the image reconstruction algorithm;

[0044] (b) Collect the particle collision sound signals through the ultrasonic sensor, and invert the change of particle humidity in combination with the spectrum analysis;

[0045] (c) Measure the differential pressure fluctuations in the fluidized bed through a pressure sensor and extract the fluidization characteristic parameters;

[0046] (d) Input the concentration, humidity, and fluidization data into the dynamic correlation model to generate a multi-dimensional parameter mapping relationship;

[0047] (e) Based on the model output, adjust the operating parameters of the fluidized bed in real time to optimize the drying efficiency and particle quality.

[0048] Furthermore, the image reconstruction algorithm in step (a) includes:

[0049] Perform capacitance-dielectric constant inversion on the ECT signal to calculate the void fraction distribution;

[0050] Analyze the imaginary part of the complex dielectric constant of the MWT signal and correlate the humidity gradient;

[0051] Correct the measurement blind area of ECT in high-humidity scenarios and the signal loss of ERT in low-conductivity scenarios through data fusion.

[0052] The present invention has the following beneficial effects:

[0053] The present invention integrates multi-modal collaborative measurements of ultrasonic, pressure, and electrical capacitance tomography sensors, preferably arranged non-invasively along the longitudinal direction of the fluidized bed, effectively suppressing signal cross-interference and optimizing the process control ability. It fuses the humidity inversion of ultrasonic signals, the extraction of fluidization characteristics of pressure signals, and the reconstruction of dielectric / conductivity distributions of electrical capacitance tomography to accurately decouple multi-dimensional parameters such as particle concentration, humidity, and fluidization, significantly improving the imaging accuracy and data integrity. The system utilizes the high frame rate characteristics of electrical capacitance tomography to capture the dynamic evolution of the medium distribution, combines the time-frequency analysis of ultrasonic and pressure signals, and realizes complementary measurements in high and low humidity scenarios (such as ultrasonic compensation for the failure of ECT in high humidity and MWT compensation for the signal loss of ERT in low conductivity), covering key parameters such as multiphase flow distribution, velocity, and pressure, eliminating the detection blind area of non-conductive phases in traditional single-sensor solutions, and reducing environmental noise interference through multi-modal data fusion. Finally, with high spatio-temporal resolution online monitoring and adaptive control, the system overcomes the deficiencies of existing technologies that rely on single experiments or empirical control, provides real-time and multi-dimensional fault diagnosis and optimization control means for the fluidized bed drying process, significantly improves the operation efficiency and energy consumption management level, and meets the requirements of large-scale and intelligent industrial processes.

[0054] Compared with the prior art, the technical advantages of the present invention are mainly as follows:

[0055] (1) It can eliminate the mutual interference of ultrasonic / pressure / electrical imaging systems. Compared with the traditional multi-sensor hierarchical arrangement scheme, the fusion structure proposed by the present invention is more conducive to process control.

[0056] (2) Better imaging effects can be obtained. Compared with traditional single-modal imaging, by fusing ultrasonic and pressure information, the limitations of single-modal measurement information can be compensated, and the density, humidity, and temperature information cannot be decoupled, thereby improving the imaging accuracy.

[0057] (3) The deficiencies of previous single-modal imaging are overcome. Utilizing the relatively fast characteristics of electrical resistance tomography, fusing ultrasonic and pressure sensing information can capture the rapid changes in the medium distribution, making the measurement results more continuous. The multi-modal integration of electrical, ultrasonic, and pressure sensing technologies synchronously obtains multi-dimensional information such as the medium distribution, dynamic pressure, and flow rate, while traditional solutions only obtain a single physical quantity; the multi-modal sensor solution has advantages over single-sensing technologies in terms of time resolution and spatial resolution; in terms of data integrity, multi-sensing fusion covers parameters such as the distribution, velocity, and pressure of multiphase flow, eliminating the detection blind area of non-conductive phases; the anti-interference ability reduces the influence of noise through multi-modal data fusion, while traditional single-sensing solutions are vulnerable to environmental noise.

[0058] (4) The deficiencies of previous process measurement and control schemes based on single-modal and pressure signal fusion are overcome. Using the measurement method provided by the present invention for process control, more abundant flow information can be provided, providing a powerful test means for process fault diagnosis and control.

[0059] Other beneficial effects in the embodiments of the present invention will be further described below. Description of the Drawings

[0060] Figure 1 It is an ultrasonic / pressure / electrical resistance imaging fluidized bed particle drying system according to an embodiment of the present invention.

[0061] Figure 2 It is a cross-sectional view of a fluidized bed reactor according to an embodiment of the present invention.

[0062] Figure 3 It is a top view of a fluidized bed reactor according to an embodiment of the present invention.

[0063] Figure 4 It is an ultrasonic / pressure / electrical resistance imaging fusion measurement scheme according to an embodiment of the present invention.

[0064] Figure 5 It is a cross-sectional view of a sensor of an alternative scheme according to an embodiment of the present invention. Detailed Embodiments

[0065] The following provides a detailed description of the embodiments of the present invention. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its applications.

[0066] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be for a fixing purpose or for a coupling or communicating purpose.

[0067] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0068] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0069] Refer to Figures 1 to 4, an embodiment of the present invention provides a system for diagnosing the state of a particle drying process based on the fusion of ultrasonic, pressure, and electrical tomography, which is used for a fluidized bed reactor 1. The fluidized bed reactor 1 has a feed inlet 9 and a sampling outlet 8. The system includes a multimodal sensor module, a data fusion processing module, and a real-time regulation module. The multimodal sensor module integrates an ultrasonic sensor 3, a pressure sensor 4 (including an upper pressure measuring port 41 and a lower pressure measuring port 42), and an electrical tomography sensor 2, and is used to synchronously collect the acoustic signal, dynamic pressure fluctuation, and dielectric / conductivity distribution signal of the particles during the fluidized bed drying process. The electrical tomography sensor 2 includes at least two of a capacitance tomography (ECT) sensor, a resistance tomography (ERT) sensor, and a microwave tomography (MWT) sensor, and suppresses signal cross-interference through band separation filtering. The data fusion processing module is configured to perform humidity inversion analysis on the acoustic signal, extract fluidization characteristics from the dynamic pressure signal, perform image reconstruction on the dielectric / conductivity distribution signal to obtain the particle concentration distribution, and establish a dynamic correlation model of void fraction, humidity, fluidization state, and flow pattern through multimodal data collaborative fusion. The real-time regulation module adaptively adjusts the inlet temperature, wind speed, and particle residence time of the fluidized bed based on the multidimensional parameters output by the dynamic correlation model to achieve online optimal control of the drying process. Among them, the measurement blind area of electrical tomography in a high-humidity scenario is compensated by ultrasonic signals, the detection failure of resistance tomography for low-conductivity particles is compensated by microwave tomography, and the fluidization state identification ability is enhanced by combining the time-frequency analysis of pressure signals, forming a collaborative diagnosis mechanism with complementary multi-physical quantities. Preferably, the multimodal sensor module is arranged non-invasively along the longitudinal direction of the fluidized bed.

[0070] In some embodiments, the electrical tomography sensor includes a capacitance tomography (ECT) sensor and a microwave tomography (MWT) sensor, where: the electrodes of the ECT sensor are made of copper sheets with a thickness of 0.3 - 0.5 mm, and are fixed on the surface of the non-conductive material along the outer wall of the fluidized bed with pressure-sensitive tape, and the electrode coverage rate is 80%; the working frequency range of the MWT sensor is 10 kHz - 500 kHz, and the complex dielectric constant distribution of the particles is measured through the microwave scattering field; the outer layer of the electrical tomography sensor is coated with a grounded flexible copper sheet as an electromagnetic shielding layer with a thickness of 0.3 - 0.5 mm.

[0071] In some embodiments, the arrangement method of the multimodal sensor module is as follows: the ultrasonic sensor 3 is fixed to the side wall of the top of the fluidized bed through NPT threads, and the working frequency band is 100 - 500 Hz, and is used to capture the particle collision sound signal; the pressure sensors are respectively installed at the top and bottom of the fluidized bed, and the dynamic pressure fluctuation is measured through the pressure difference; the electrical tomography sensors are evenly distributed circumferentially along the outer wall of the same cross-section of the fluidized bed, and the electrode spacing is adaptively adjusted based on the diameter of the fluidized bed.

[0072] In some embodiments, the signal separation unit of the data fusion processing module includes: a low-pass filter with a cut-off frequency of 2 kHz for extracting the low-frequency components of the pressure signal and the ultrasonic signal; a cascaded high-pass filter with a cut-off frequency of 10 kHz for separating the high-frequency signals of electrical capacitance tomography; and the signal separation unit suppresses the cross-interference of multi-modal signals through frequency band isolation.

[0073] In some embodiments, the image reconstruction unit of the electrical capacitance tomography sensor is configured to: reconstruct the porosity image of the particle concentration distribution based on electrical capacitance tomography (ECT); calculate the imaginary part of the complex dielectric constant based on the inversion algorithm of microwave tomography (MWT) and correlate the particle humidity distribution; and fuse the imaging data of ECT and MWT to generate a multi-parameter dynamic distribution map.

[0074] In some embodiments, the fluidized bed reactor is made of plexiglass or plastic with a thickness of 0.3 - 0.8 cm, and its cross-section is conical or rectangular; the width of the outer shielding copper sheet of the electrical capacitance tomography sensor is 2 - 3 cm greater than the electrode height and is isolated from the outer wall of the fluidized bed by a plexiglass plate with a thickness of 0.5 cm.

[0075] In some embodiments, the real-time regulation module is configured to: based on the porosity, humidity, and flow regime parameters output by the dynamic correlation model, adjust the fluidized bed inlet temperature, wind speed, and particle residence time in real time; capture the flow regime evolution through the imaging rate of hundreds of frames per second of electrical capacitance tomography and trigger the regulation instruction in combination with the time-frequency analysis result of the pressure signal.

[0076] In some embodiments, the system further includes a temperature sensor (through temperature measurement port 7) installed at the fluidized bed outlet for monitoring the humidity of the fluidizing air; the data fusion processing module establishes a quantitative mapping relationship between the porosity, fluidization wind speed, inlet / outlet temperature, and flow regime changes through multi-modal fusion.

[0077] An embodiment of the present invention further provides a method for diagnosing the state of the particle drying process using the system, including the following steps:

[0078] (a) Synchronously collect the dielectric / conductivity distribution signals through the electrical capacitance tomography sensor and generate the particle concentration and humidity distribution maps using the image reconstruction algorithm;

[0079] (b) Collect the particle collision sound signals through the ultrasonic sensor 3 and invert the change of particle humidity in combination with spectrum analysis;

[0080] (c) Measure the differential pressure fluctuation of the fluidized bed through the pressure sensor and extract the flow regime characteristic parameters;

[0081] (d) Input the concentration, humidity, and flow regime data into the dynamic correlation model to generate a multi-dimensional parameter mapping relationship;

[0082] (e)Regulate the operating parameters of the fluidized bed in real time based on the model output to optimize the drying efficiency and particle quality.

[0083] In some embodiments, the image reconstruction algorithm in step (a) includes:

[0084] Perform capacitance-dielectric constant inversion on the ECT signal to calculate the void fraction distribution;

[0085] Analyze the imaginary part of the complex dielectric constant of the MWT signal to correlate the humidity gradient;

[0086] Correct the measurement blind area of ECT in high-humidity scenarios and the signal loss of ERT in low-conductivity scenarios through data fusion.

[0087] The present invention proposes a method for monitoring the fluidized bed drying process based on the fusion of ultrasonic pressure and tomography, which uses the fusion of multiple sensor information to measure the same process or object. Through the fusion of images, ultrasonic and pressure signals, the distribution of key parameters of the reaction process is obtained, realizing the collaborative complementarity of different measurement methods, and then realizing the effective regulation of the process. Aiming at the need for the regulation of the fluidized bed particle drying process, according to the time-varying information of particle humidity and concentration in the reaction process, ultrasonic, pressure and electrical tomography are fused, and through data fusion analysis, the reaction process is detected, and then the reaction process is effectively regulated.

[0088] The specific embodiments of the present invention are further described below.

[0089] An ultrasonic / pressure / electrical imaging system for measuring the changes of key parameters and the flow pattern identification method of the fluidized bed particle drying process with different humidities in different frequency ranges.

[0090] Figure 1An ultrasonic / pressure / electrical imaging fluidized bed particle drying system is shown, including an integrated scheme of sensors for the fluidized bed drying process based on ultrasonic / pressure / electrical imaging. The system includes a fluidized bed drying reactor 1, an electrical capacitance tomography sensor 2, an ultrasonic sensor 3, a pressure sensor 4, a data acquisition system 5, and a computer display system 6. The temperature sensor, the pressure sensor 4, and the ultrasonic sensor 3 are all fixed to the side wall of the fluidized bed with NPT threads; the electrical capacitance tomography sensor is wrapped around the side wall of the acrylic fluidized bed with pressure-sensitive tape. During measurement, the electrical capacitance tomography frequency range is 10KHz to 500kHz, and the acquisition frequencies of the ultrasonic and pressure signals are based on 100 - 500Hz. Instead of using the traditional arrangement of nested single imaging sensors inside and outside, the present invention arranges them on the same cross-section of the fluidized bed drying equipment. When separating multi-modalities in data acquisition, a low-pass filter with a cut-off frequency of 2kHz is selected. First, the original signal is low-pass filtered to extract the low-frequency modality, and the remaining signal is cascaded with a high-pass filter with a cut-off frequency of 10kHz to separate the high-frequency modality, thereby reducing the mutual interference between the measurement signals of each modality. Therefore, the design of this system meets the requirements of anti-interference.

[0091] In the specific implementation process, the electrical capacitance tomography system measures the flow state distribution in the process of preparing fluidized bed particles, and obtains the void fraction (concentration) information distribution of the measurement area by processing the gray-scale data of the reconstructed image; the temperature and humidity sensors at the outlet of the fluidized bed obtain the humidity of the fluidizing air at the outlet. Through multi-modal fusion, the corresponding relationships among the void fraction, the fluidized bed wind speed, the particle residence time, the inlet temperature, the outlet temperature, and the flow state are established.

[0092] The pipeline of the fluidized bed reactor is made of non-conductive materials with a thickness of 0.3 - 0.8 cm, and plastics, plexiglass, etc. are often used. The cross-section is conical, and the diameter varies according to the specific reaction process. The electrical sensors are all placed on the outer wall of the pipeline. The sensors are made of excellent-performance metals such as copper sheets, with a thickness of 0.3 - 0.5 mm and a height of 5 - 8 cm. The width of the electrodes depends on the number of electrodes, and the cross-sectional area coverage of the pipeline is controlled to be 80%. An organic glass plate with a thickness of 0.5 cm is installed outside the electrodes. A flexible rectangular copper sheet with a thickness of 0.3 - 0.5 mm is coated on the outer wall of the organic glass plate, and its width is required to be 2 - 3 cm greater than the electrode height. During measurement, the outermost copper sheet is grounded and used as an outer shield. The pressure sensors are arranged at the bottom and top of the reactor, and the pressure fluctuation information of the reactor is obtained by measuring the pressure difference. The ultrasonic sensors are arranged at the top of the reactor, and the humidity information of the particles is obtained through the sound signal.

[0093] According to different times of the reaction process, combined with the temperature and humidity sensors, the images obtained by fusing the electrical capacitance tomography reconstruction are used to obtain the concentration distribution, humidity distribution, and flow state changes during the reaction process.

[0094] The present invention can be used for multiphase flow measurement in the preparation process of fluidized particle drying, and is particularly suitable for measurement and process control in the reaction process with changing particle humidity.

[0095] The present invention can provide a fluidized bed particle drying preparation process superior to a single imaging mode. Preferably, the multimodal sensor module is arranged non-invasively along the longitudinal direction of the fluidized bed. See Figure 5 , and preferably, a plurality of electrical capacitance tomography sensors are evenly distributed circumferentially on the outer wall of the same cross-section of the fluidized bed and located in the same cross-section. The flow parameter distribution during the reaction process can be obtained simultaneously, and then the concentration and humidity distribution information can be obtained.

[0096] Generally, ECT also has the function of measuring the humidity of the medium, such as WO / 2009 / 030876. However, when the humidity of the measured medium in the pipe flow is relatively high or fluctuates greatly, it will exceed the measurement range of ECT, and the measurement result of pure ECT can no longer meet the imaging requirements. At this time, the humidity change of the particles can be obtained by using the ultrasonic signal for particle collision information. In addition, the flow pattern and flow state changes inside the reactor can be obtained by combining the spectral analysis of the pressure signal and the ultrasonic signal. The above ultrasonic / pressure / electrical imaging fusion measurement scheme is shown in Figure 4 .

[0097] Engineering applications often require the ability to optimize control or fault diagnose the operating equipment online. The process is as follows: First, the measured results are analyzed and processed to give the control scheme to be implemented, and then the specific implementation is carried out through feedback regulation. This requires that the sensor used has as fast a sampling rate as possible and is sensitive to the changes in the flow in the measured area. Since the electrical imaging rate can reach several hundred frames per second and can capture the coherent evolution process of the fluid flow pattern, the application of the present invention can achieve real-time measurement of the flow.

[0098] Figure 1 The embodiment shown uses a reactor with a circular cross-section. In other embodiments, a reactor with a square or rectangular cross-section structure can also be used, and the number of ultrasonic / pressure / electrical imaging sensors remains unchanged. As Figure 5 shown, the number of electrodes of the electrical capacitance tomography sensor is 12 electrodes, and the electrode coverage rate is 80% (the ratio of the total surface area covered by the electrode sheet to the total inner surface area of the sensor in the measurement area. Coverage rate = (total area of the electrode sheet / total inner surface area of the sensor measurement area) * 100%). Other numbers of electrodes can be 8 to 20, such as 16 electrodes in the rectangular area in the figure, and the electrode coverage rate is 60% to 80%.

[0099] Compared with the prior art, the technical advantages of the present invention are mainly as follows:

[0100] (1) The mutual interference of the ultrasonic / pressure / electrical imaging systems can be eliminated. Compared with the traditional multi-sensor hierarchical arrangement scheme, the fusion structure proposed by the present invention is more conducive to process control.

[0101] (2) Better imaging effects can be obtained. Compared with traditional single-modal imaging, by fusing ultrasonic and pressure information, the limitations of single-modal measurement information can be made up for, the density, humidity and temperature information cannot be decoupled, and thus the imaging accuracy can be improved.

[0102] (3) The deficiencies of previous single-modal imaging are overcome. Utilizing the faster characteristics of electrical resistance tomography, fusing ultrasonic and pressure sensing information can capture the rapid changes in the medium distribution, making the measurement results more continuous. The multi-modal integrated electrical, ultrasonic and pressure sensing technologies can synchronously obtain multi-dimensional information such as the medium distribution, dynamic pressure and flow velocity, while the traditional solutions only obtain a single physical quantity; the multi-modal sensor solution has advantages over the single-sensing technology in terms of time resolution and spatial resolution; in terms of data integrity, the multi-sensing fusion covers parameters such as the distribution, velocity and pressure of multiphase flow, eliminating the detection blind area of non-conductive phases; the anti-interference ability reduces the influence of noise through multi-modal data fusion, while the traditional single-sensing solution is vulnerable to environmental noise.

[0103] (4) The deficiencies of previous process measurement and control schemes based on single-modal and pressure signal fusion are overcome. Using the measurement method provided by the present invention for process control, more abundant flow information can be provided, providing a powerful test means for process fault diagnosis and control.

[0104] In summary, the present invention proposes a system for diagnosing the state of a particle drying process based on the fusion of ultrasonic, pressure and electrical resistance tomography. By integrating ultrasonic sensors, pressure sensors and electrical resistance tomography sensors (at least two of ECT / ERT / MWT), preferably non-invasively arranged in the same horizontal section to achieve synchronous acquisition of multi-modal signals. The system uses frequency band separation filtering to suppress signal interference, inversely calculates the particle humidity through ultrasonic signal spectrum analysis, extracts the flow state characteristics through time-frequency analysis of the pressure signal, reconstructs the dielectric / conductivity distribution by electrical resistance tomography to obtain the concentration information, and combines multi-modal data fusion to establish a dynamic correlation model of void fraction, humidity, flow state and flow pattern. Aiming at the inherent defects of electrical resistance tomography, ultrasonic signals are used to compensate for the measurement blind area of ECT in high-humidity scenarios, and MWT signals are used to compensate for the detection failure of ERT in low-conductivity particles, combined with pressure signals to enhance the flow state identification ability, forming a multi-physical quantity complementary mechanism. The real-time control module adaptively adjusts the inlet temperature, wind speed and particle residence time of the fluidized bed based on the multi-dimensional parameters output by the model to achieve online optimization control of the drying process. The system significantly improves the imaging accuracy and anti-interference ability through high spatio-temporal resolution monitoring and multi-modal collaborative decoupling, covers multi-phase flow distribution, velocity and pressure parameters, overcomes the detection blind area of non-conductive phases in traditional single-sensing schemes, and provides an efficient and low-consumption real-time fault diagnosis and intelligent control means for the fluidized bed drying process.

[0105] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several alternatives or modifications can be made to these described embodiments, and these alternative or modified forms should all be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. Without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope of protection of the patent application.

Claims

1. A particle drying process state diagnosis system based on the fusion of ultrasound, pressure and electrical tomography, characterized in that: include: A multimodal sensor module, integrating an ultrasonic sensor, a pressure sensor and an electrical tomography sensor, for synchronously collecting acoustic signals, dynamic pressure fluctuations and dielectric / conductivity distribution signals of particles during fluidized bed drying, wherein the electrical tomography sensor includes at least two of an electrical capacitance tomography (ECT) sensor, an electrical resistance tomography (ERT) sensor and a microwave tomography (MWT) sensor, and suppressing signal cross-interference through frequency band separation filtering; A data fusion processing module is configured to perform humidity inversion analysis on the acoustic signal, extract flow characteristics on the dynamic pressure signal, reconstruct an image of the dielectric / conductivity distribution signal to obtain particle concentration distribution, and establish a dynamic correlation model of porosity, humidity, flow state and flow type through collaborative fusion of multimodal data; A real-time control module, based on the multi-dimensional parameters output by the dynamic correlation model, adaptively adjusts the inlet temperature, wind speed and particle residence time of the fluidized bed to achieve online optimization control of the drying process; Among them, ultrasonic signals are used to compensate for the measurement blind spots of electrical tomography in high humidity scenes, microwave tomography is used to compensate for the detection failure of resistance tomography in low conductivity particles, and the flow state identification capability is enhanced by combining the time-frequency analysis of pressure signals to form a collaborative diagnosis mechanism with complementary multiple physical quantities; preferably, the multimodal sensor module is arranged non-invasively along the longitudinal direction of the fluidized bed.

2. The diagnostic system according to claim 1, characterized in that The electrical tomography sensor includes an electrical capacitance tomography (ECT) sensor and a microwave tomography (MWT) sensor, wherein: The electrodes of the ECT sensor are made of copper sheets with a thickness of 0.3 to 0.5 mm and fixed with pressure-sensitive tape along the non-conductive material surface of the outer wall of the fluidized bed; The operating frequency range of the MWT sensor is 10kHz to 500kHz, and the distribution of the complex dielectric constant of particles is measured through the microwave scattering field; The outer layer of the electrical tomography sensor is coated with a grounded flexible copper sheet as an electromagnetic shielding layer, and the thickness is 0.3-0.5 mm.

3. The diagnostic system according to claim 1 or 2, characterized in that: The multimodal sensor module is arranged as follows: The ultrasonic sensor is fixed to the top side wall of the fluidized bed through NPT threads. The operating frequency range is 100-500 Hz and is used to capture the particle collision sound signal. Pressure sensors are installed at the top and bottom of the fluidized bed to measure dynamic pressure fluctuations through pressure difference; The electrical tomography sensors are evenly distributed along the circumference of the outer wall of the same cross section of the fluidized bed, and the electrode spacing is adaptively adjusted based on the diameter of the fluidized bed.

4. The diagnostic system according to any one of claims 1 to 3, characterized in that: The signal separation unit of the data fusion processing module includes: A low-pass filter with a cutoff frequency of 2kHz is used to extract the low-frequency components of the pressure signal and the ultrasonic signal; Cascaded high-pass filter with a cutoff frequency of 10kHz for separating high-frequency signals for electrical tomography; The signal separation unit suppresses cross-interference of multi-modal signals by frequency band isolation.

5. The diagnostic system according to any one of claims 1 to 4, characterized in that: The image reconstruction unit of the electrical tomography sensor is configured as follows: Reconstruction of void fraction images of particle concentration distribution based on electrical capacitance tomography (ECT); The imaginary part of the complex dielectric constant is calculated based on the inversion algorithm of microwave tomography (MWT) and correlated with the particle humidity distribution; The imaging data of ECT and MWT were fused to generate multi-parameter dynamic distribution maps.

6. The diagnostic system according to any one of claims 1 to 5, characterized in that: The fluidized bed reactor is made of organic glass or plastic with a thickness of 0.3 to 0.8 cm and a conical or rectangular cross section; the outer shielding copper sheet of the electrical tomography sensor is 2 to 3 cm wider than the electrode height and is isolated from the outer wall of the fluidized bed by an organic glass plate.

7. The diagnostic system according to any one of claims 1 to 6, characterized in that: The real-time control module is configured as follows: Based on the porosity, humidity and flow parameters output by the dynamic correlation model, the fluidized bed inlet temperature, wind speed and particle residence time are adjusted in real time; The flow evolution is captured by electrical tomography at an imaging rate of hundreds of frames per second, and control instructions are triggered by combining the time-frequency analysis results of the pressure signal.

8. The diagnostic system according to any one of claims 1 to 7, characterized in that: The system also includes a temperature sensor installed at the fluidized bed outlet for monitoring fluidizing air humidity; the data fusion processing module establishes a quantitative mapping relationship between void fraction, fluidizing air velocity, inlet / outlet temperature and flow state changes through multi-modal fusion.

9. A method for diagnosing the state of a particle drying process using the system according to any one of claims 1 to 8, characterized in that: The following steps are involved: (a) The dielectric / conductivity distribution signals are collected synchronously by the electrical tomography sensor, and the particle concentration and humidity distribution maps are generated by the image reconstruction algorithm; (b) Collect particle collision sound signals through ultrasonic sensors and invert the particle humidity changes by combining spectrum analysis; (c) measuring the pressure difference fluctuation of the fluidized bed by means of a pressure sensor and extracting the characteristic parameters of the flow state; (d) inputting the concentration, humidity and flow state data into the dynamic correlation model to generate a multi-dimensional parameter mapping relationship; (e) Based on the model output, the fluidized bed operating parameters are adjusted in real time to optimize the drying efficiency and particle quality.

10. The method according to claim 9, characterized in that The image reconstruction algorithm in step (a) includes: Perform capacitance-dielectric constant inversion on the ECT signal and calculate the void fraction distribution; The MWT signal is analyzed by the imaginary part of the complex dielectric constant and correlated with the humidity gradient; Data fusion is used to correct the measurement blind area of ​​ECT in high humidity scenarios and the signal loss of ERT in low conductivity scenarios.

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