Method and device for detecting characteristics of bubbles in up-flow gas-liquid-solid reactor

Abstract

The invention provides a method and device for detecting bubble characteristics in an up-flow gas-liquid-solid reactor, and the method comprises the steps: arranging at least one hydrophone on the liquid level of the reactor, and collecting a local sound signal generated by the breaking of bubbles at the corresponding position of the liquid level in the reactor through each hydrophone; performing feature extraction on the local sound signals to obtain feature parameters used for describing a bubble breaking process; and determining bubble characteristics according to the characteristic parameters. The method is suitable for detection of bubble parameter characteristics in the up-flow gas-liquid-solid reactor, and has good accuracy.

Description

Technical Field

[0001] This invention relates to the field of reactors, and in particular to a method and apparatus for detecting bubble characteristics in an upflow gas-liquid-solid reactor. Background Technology

[0002] Upflow gas-liquid-solid reactors utilize the driving force of rising bubbles to enhance liquid-phase turbulence, enabling mixing of the gas-liquid-solid three phases and promoting heat and mass transfer. They are simple in structure and have high heat and mass transfer efficiency, making them particularly suitable for strongly exothermic reactions, including Fischer-Tropsch synthesis and residue hydrogenation. Currently, most bubble parameter detection in reactors relies on optical imaging and conductivity probes. However, most industrially used reactors are not visually observable, and even with viewing windows, the visible range is very limited, making optical imaging methods difficult to apply to industrial production. Conductivity probes provide very limited bubble information, and obtaining the average bubble size across the entire bed requires a high-density probe arrangement within the reactor, significantly impacting fluid flow.

[0003] Therefore, it is of great significance to develop a detection method suitable for upflow gas-liquid-solid reactors that can comprehensively obtain the bubble characteristics of the entire bed. Summary of the Invention

[0004] Therefore, the present invention proposes a method and apparatus for detecting bubble characteristics in an upflow gas-liquid-solid reactor, which can improve the problems existing in the aforementioned prior art.

[0005] This invention provides a method for detecting bubble characteristics in an upflow gas-liquid-solid reactor, comprising:

[0006] At least one hydrophone is placed on the liquid surface of the reactor, and each hydrophone collects the local acoustic signal generated by the bursting of bubbles at the corresponding position on the liquid surface of the reactor.

[0007] Feature extraction is performed on the local acoustic signal to obtain feature parameters that describe the bubble breakup process;

[0008] Based on this characteristic parameter, the bubble characteristics during liquid surface breakage are determined.

[0009] In one embodiment, the characteristic parameters include sound pressure characteristic amplitude, sound signal center frequency, sound signal characteristic frequency, and sound source characteristics of peak shape;

[0010] The envelope of the local acoustic signal is obtained.

[0011] For each envelope peak, the energy of the acoustic signal within that envelope peak is calculated, and the corresponding peak value of the acoustic signal is determined as the characteristic amplitude of the sound pressure.

[0012] For each envelope peak, the spectrum of the acoustic signal within that envelope peak and the center frequency of the acoustic signal are calculated using a Fast Fourier Transform.

[0013] The characteristic frequency of the acoustic signal is obtained by averaging the spectrum of all envelope peaks within the measurement time.

[0014] Identify the high-amplitude portion at a fixed frequency in each spectrum;

[0015] The sum of the amplitude values ​​of all high-amplitude components is divided by the sum of all amplitude values ​​at a fixed frequency to obtain a proportion, which is determined as the sound source characteristic of the peak shape.

[0016] In one embodiment, the bubble feature includes bubble size;

[0017] The size of the bubble is determined based on the characteristic amplitude of the sound pressure and the characteristic frequency of the sound signal.

[0018] The bubble size is positively correlated with the characteristic amplitude of the sound pressure, and negatively correlated with the characteristic frequency of the sound signal.

[0019] In one embodiment, the bubble feature includes a bubble frequency;

[0020] The frequency of the bubble is detected based on the center frequency of the acoustic signal.

[0021] In one embodiment, the bubble feature includes a bubble rising velocity;

[0022] The surface tension of the liquid phase inside the reactor was detected based on the sound source characteristics of the peak shape.

[0023] The rising speed of the bubble is determined based on the surface tension of the liquid phase and the size of the bubble.

[0024] In one embodiment, prior to feature extraction from the local acoustic signal, the method further includes:

[0025] The local acoustic signal is preprocessed to remove noise.

[0026] In one embodiment, one or more preprocessing methods, such as smoothing, differentiation, Fourier transform, and wavelet transform, are used to remove noise.

[0027] In another aspect, the present invention provides a device for detecting bubble characteristics in an upflow gas-liquid-solid reactor, employing the aforementioned method for detecting bubble characteristics in an upflow gas-liquid-solid reactor. The device comprises:

[0028] At least one hydrophone is placed on the surface of the reactor liquid, and each hydrophone is used to collect the local acoustic signal generated by the bursting of bubbles at the corresponding position on the surface of the reactor liquid.

[0029] A signal processing device is used to extract features from the local acoustic signal to obtain feature parameters describing the bubble breakage process; and to determine the bubble characteristics when the liquid surface breaks based on the feature parameters.

[0030] In one embodiment, when the at least one hydrophone is multiple hydrophones, the multiple hydrophones are evenly arranged on the surface of the reactor liquid in a horizontal direction.

[0031] In one embodiment, each hydrophone employs an acoustic emission sensor, and

[0032] All acoustic wave sensors have the same frequency response characteristics, with a frequency response range of 1Hz to 10MHz.

[0033] The advantages of this invention are:

[0034] This invention proposes a method for detecting bubble characteristics in an upflow gas-liquid-solid reactor. It employs a hydrophone array to obtain local acoustic signals generated by bubble breakage at different locations on the liquid surface within the reactor. Through multi-sensor data fusion, it effectively detects the acoustic emission of bubble characteristics within the reactor. Simultaneously, it extracts features from these local acoustic signals, acquiring multiple characteristic parameters describing the bubble breakage process, such as the characteristic amplitude of the sound pressure, the center frequency of the sound signal, the characteristic frequency of the sound signal, and the source characteristics of the peak shape. These multiple characteristic parameters are then used to detect bubble characteristics. The more parameters present, the more detailed the signal characterization, and consequently, the more detailed the bubble characterization, thus improving the accuracy of bubble characteristic detection. This method is applicable to the detection of bubble parameter characteristics in upflow gas-liquid-solid reactors and exhibits good accuracy.

[0035] To provide a better understanding of the above and other aspects of the present invention, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0036] Figure 1 A schematic diagram illustrating the overall flow of a method for detecting bubble characteristics in an upflow gas-liquid-solid reactor according to an embodiment of the present invention is shown.

[0037] Figure 2 Draw a schematic diagram of the hydrophone array;

[0038] Figure 3 Draw Figure 1 A detailed flowchart of step S2;

[0039] Figure 4 Plot the relationship between bubble diameter and sound pressure characteristic amplitude;

[0040] Figure 5 Plot the relationship between bubble diameter and the characteristic frequency of the acoustic signal;

[0041] Figure 6A schematic diagram of a device for detecting bubble characteristics in an upflow gas-liquid-solid reactor according to an embodiment of the present invention is shown.

[0042] In the attached figures, the following labels are used:

[0043] 10-Reactor;

[0044] 20- Hydrophone;

[0045] 30 - Signal processing device;

[0046] 40 - Signal amplification device;

[0047] 50 - Signal acquisition device. Detailed Implementation

[0048] Please refer to Figures 1-6 , Figure 1 A schematic flowchart illustrating the overall process of a method for detecting bubble characteristics in an upflow gas-liquid-solid reactor according to an embodiment of the present invention is shown. Figure 2 Draw a schematic diagram of the hydrophone array. Figure 3 Draw Figure 1 A detailed flowchart of step S2 is provided. Figure 4 Plot the relationship between bubble diameter and sound pressure characteristic amplitude. Figure 5 Plot a graph showing the relationship between bubble diameter and the characteristic frequency of the acoustic signal. Figure 6 A schematic diagram of a device for detecting bubble characteristics in an upflow gas-liquid-solid reactor according to an embodiment of the present invention is shown.

[0049] like Figure 1 As shown in some embodiments, a method for detecting bubble characteristics in an upflow gas-liquid-solid reactor is disclosed. Generally, it involves collecting and analyzing local acoustic signals generated by the breakage of bubbles after they rise to the liquid surface using an immersive hydrophone, extracting acoustic signal characteristic quantities to characterize the bubble features within the reactor. This detection method will be described in detail below.

[0050] A method for detecting bubble characteristics in an upflow gas-liquid-solid reactor, comprising the following steps:

[0051] Step S1: Place at least one hydrophone on the liquid surface of the reactor, and each hydrophone collects the local acoustic signal generated by the bursting of bubbles at the corresponding position on the liquid surface inside the reactor.

[0052] In this embodiment, an invasive hydrophone is used to collect local acoustic signals generated when bubbles rise to the liquid surface and break apart inside the gas-liquid-solid reactor.

[0053] In some embodiments, the gas-liquid-solid reactor uses solid particles with a diameter of less than 1 mm, a particle-to-liquid ratio ρs / ρl of not more than 3, and a solid mass content of not more than 20%.

[0054] Specifically, at least one hydrophone is placed on the liquid surface of the reactor, and each hydrophone collects the local acoustic signal generated by the bursting of bubbles at a corresponding position on the liquid surface inside the reactor. The specific number of hydrophones is determined according to the actual situation.

[0055] like Figure 2 As shown, when multiple hydrophones are used, they are preferentially and uniformly arranged on the surface of the reactor liquid in the horizontal direction to form a hydrophone array. The correlation of signals between different hydrophone channels is used to capture behaviors such as overlapping and breaking of bubbles, and to obtain local acoustic signals generated by bubble breaking at different positions on the surface of the reactor liquid, thereby improving detection accuracy.

[0056] Furthermore, in some embodiments, each hydrophone specifically employs an acoustic emission sensor, and all acoustic sensors have the same frequency response characteristics, with a frequency response range of 1Hz to 10MHz. Acoustic emission sensors are more effective at capturing high-frequency signals (corresponding to small bubbles).

[0057] Furthermore, in practice, the local acoustic signals acquired by hydrophones contain a great deal of noise. Therefore, noise removal methods are crucial. In some embodiments, the local acoustic signal is preprocessed to remove noise before feature extraction, thereby improving the accuracy of subsequent analysis. For example, one or more preprocessing methods such as smoothing, differentiation, Fourier transform, and wavelet transform can be used to remove noise, but the preprocessing methods of this invention are not limited to these. Smoothing can improve the signal-to-noise ratio of the analyzed signal; commonly used methods include moving average smoothing and Savizky-Golay polynomial smoothing. Differentiation is a commonly used spectral preprocessing method that can eliminate baseline drift, enhance spectral band features, and overcome spectral band overlap. Fourier transform enables the conversion between spectral domain functions and time domain functions. It achieves smoothing and denoising of the acoustic spectrum, data compression, and information extraction by decomposing the original acoustic spectrum into a superposition of many sine waves of different frequencies. Wavelet transform can decompose the signal into multiple scale components according to different frequencies and apply corresponding sampling step sizes to different scale components, thereby enabling focusing on any part of the signal.

[0058] Step S2: Extract features from the local acoustic signal to obtain feature parameters that describe the bubble breaking process.

[0059] In this embodiment, after acquiring the local acoustic signal generated by the breaking of bubbles on the liquid surface in the reactor through a hydrophone, the feature of the local acoustic signal is further extracted to obtain feature parameters that describe the bubble breaking process.

[0060] Specifically, the characteristic parameters of the bubble breakup process mainly include the characteristic amplitude of sound pressure, the characteristic frequency of the sound signal, and the source characteristics of the peak shape. (See also...) Figure 3 As shown, firstly, the envelope of the local acoustic signal is obtained (step S21); after obtaining the envelopes of the several local acoustic signals, the energy of the acoustic signal within each envelope peak is calculated, and the corresponding peak value is determined as the sound pressure characteristic amplitude (step S22). Simultaneously, for the acoustic signal within each envelope peak, the spectrum of the acoustic signal within the envelope peak and the center frequency of the acoustic signal are calculated using a Fast Fourier Transform. The center frequency is the frequency component with the most concentrated energy in the acoustic signal (step S23); and the spectrum of all envelope peaks within the measurement time is averaged to obtain the characteristic frequency of the acoustic signal (step S24). For the peak-shaped sound source characteristics, it is the proportion of high characteristic amplitude components at a fixed frequency in the acoustic signal. Specifically, the high amplitude portion at a fixed frequency is identified in each spectrum obtained in step S23. In some embodiments, a threshold is set or other feature extraction algorithms are used to identify the high amplitude portion at a fixed frequency in each spectrum. Then, by summing the amplitude values ​​of all high-amplitude components and dividing by the sum of all amplitude values ​​at a fixed frequency, a proportion is obtained, which can then be used to determine the peak-shaped sound source characteristics (S25).

[0061] Step S3: Determine the bubble characteristics based on the feature parameters.

[0062] In this embodiment, after obtaining the characteristic parameters of the bubble breaking process by extracting local acoustic signal features, the bubble characteristics at the time of liquid surface breaking are further determined based on the characteristic parameters.

[0063] Specifically, the characteristics of broken bubbles on the liquid surface include gas size (e.g., bubble diameter), bubble frequency, and bubble rise speed.

[0064] Regarding bubble size, based on the characteristic that the diffusion velocity of the airflow generated by bubble breakage is positively correlated with the bubble radius, the bubble size is detected according to the characteristic amplitude of the sound pressure level and the characteristic frequency of the sound signal. Specifically, the bubble size is positively correlated with the characteristic amplitude of the sound pressure level and negatively correlated with the characteristic frequency of the sound signal. For example... Figure 4 , Figure 5 The diagram shows the changes in sound pressure characteristic amplitude and sound signal characteristic frequency with bubble size. It can be seen that as bubble size increases, the sound pressure characteristic amplitude gradually increases, while the sound signal characteristic frequency gradually decreases. This is because as the bubble size increases, the pressure difference between the inside and outside of the bubble decreases, ΔP = 4σ / r0, and the pressure difference between the inside and outside of the bubble decreases, ΔF = (4σ / r0)·4πr0. 2The increase in the gas flow diffusion velocity leads to a larger velocity amplitude at the liquid film edge, which in turn increases the characteristic amplitude and decreases the characteristic frequency of acoustic emission during bubble breakage. This further demonstrates the feasibility and accuracy of the bubble parameter characteristics in the upflow gas-liquid-solid reactor.

[0065] Regarding bubble frequency, when a bubble vibrates in water, it generates sound waves, and the frequencies of these sound waves correspond to the bubble's vibration frequency. Therefore, by analyzing the sound signal, the bubble's frequency information can be extracted. The center frequency of the sound signal is the frequency component with the most concentrated energy in the sound signal; specifically, the bubble frequency is detected based on this center frequency of the sound signal.

[0066] The rising velocity of a bubble is a complex parameter influenced by multiple factors, primarily bubble size and liquid surface tension. According to Stokes' law, the rising velocity of a bubble in water is proportional to the square of its diameter. However, this law applies only to bubbles with smaller diameters and lower Reynolds numbers.

[0067] Liquid surface tension reflects the intermolecular forces at the liquid surface, significantly influencing bubble formation and movement. Higher surface tension helps maintain bubble stability, reducing deformation and breakage during ascent. It also affects bubble size distribution. Generally, increased surface tension may lead to larger bubble diameters, as greater surface tension requires more energy to overcome and form new bubble surfaces. Bubble ascent velocity is influenced by both buoyancy and drag. Liquid surface tension indirectly affects bubble resistance and ascent velocity by influencing bubble shape and stability. Specifically, increased surface tension may result in a more stable spherical bubble shape, reducing shape drag; lower drag leads to higher ascent velocity. However, a larger bubble diameter may also result in greater viscous drag, affecting ascent velocity. Therefore, in practice, the ascent velocity is determined based on the combined effect of liquid surface tension and bubble size. For the liquid surface tension within the reactor, it can be detected using the characteristic frequencies of the acoustic signal obtained above. When the surface tension coefficient of the liquid phase increases, the pressure difference between the inside and outside of the bubble increases, the gas phase flow velocity increases, and the amplitude of the sound signal when the bubble breaks up increases. The surface tension of the liquid phase in the reactor can be detected by using the peak-shaped sound source characteristics.

[0068] In summary, the method for detecting bubble characteristics in an upflow gas-liquid-solid reactor disclosed in this invention uses a hydrophone array to obtain local acoustic signals generated by bubble breakage at different positions on the liquid surface within the reactor. Through data fusion from multiple sensors, the acoustic emission detection of bubble characteristics within the reactor is effectively achieved. Simultaneously, feature extraction is performed on this local acoustic signal to obtain multiple characteristic parameters describing the bubble breakage process, such as the characteristic amplitude of the sound pressure, the center frequency of the sound signal, the characteristic frequency of the sound signal, and the source characteristics of the peak shape. Then, bubble characteristics (size, frequency, rising velocity, etc.) are detected based on these multiple characteristic parameters. The more parameters, the more detailed the signal characterization, and thus the more detailed the bubble characterization, improving the accuracy of bubble characteristic detection. This method is applicable to the detection of bubble parameter characteristics in upflow gas-liquid-solid reactors and has good accuracy. This detection method is suitable for solid particles with a diameter less than 1 mm, a particle-to-liquid ratio ρs / ρl not exceeding 3, and a solid mass content not exceeding 20%.

[0069] In addition, corresponding to the embodiments of the aforementioned detection methods, the present invention also provides embodiments of a device for detecting bubble characteristics in an upflow gas-liquid-solid reactor.

[0070] For details, please refer to [link / reference]. Figure 6 The device shown is a detection device for bubble characteristics within the upflow gas-liquid-solid reactor, the device comprising:

[0071] At least one hydrophone 20 is arranged on the liquid surface of the reactor 10, and each hydrophone is used to collect the local sound signal generated by the bursting of bubbles at the corresponding position on the liquid surface in the reactor.

[0072] The signal processing device 30 is used to extract features from the local acoustic signal to obtain feature parameters that describe the bubble breaking process; and to determine the bubble characteristics when the liquid surface breaks based on the feature parameters.

[0073] In addition, such as Figure 2 As shown, when multiple hydrophones are used, the multiple hydrophones 20 are preferentially and uniformly arranged on the liquid surface of the reactor in the horizontal direction to form a hydrophone array. The correlation of signals between different hydrophone channels is used to capture behaviors such as overlapping and breaking of bubbles, and to obtain local acoustic signals generated by bubble breaking at different positions on the liquid surface in the reactor, thereby improving the detection accuracy.

[0074] Furthermore, in some embodiments, each hydrophone specifically employs an acoustic emission sensor, and all acoustic sensors have the same frequency response characteristics, with a frequency response range of 1Hz to 10MHz. Acoustic emission sensors are more effective at capturing high-frequency signals (corresponding to small bubbles).

[0075] In addition, further reading Figure 6As shown in some embodiments, a signal amplification device 40 and a signal acquisition device 50 are further provided between the hydrophone 20 and the signal processing device 30. The signal amplification device 40 is coupled to the hydrophone, receives the local sound signal acquired by the hydrophone and performs signal amplification processing; the signal acquisition device 50 is coupled to the signal amplification device 40 and the signal processing device 30, and transmits the local sound signal to the signal processing device 30 after filtering and preprocessing.

[0076] This detection device is simple, safe, environmentally friendly, and suitable for online detection in industrial production processes. It uses a hydrophone array and multi-sensor data fusion to effectively detect bubble characteristics (especially bubble size) in the reactor, filling a gap in the field of gas-liquid-solid reactor detection.

[0077] Furthermore, those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of each module of the device for detecting bubble characteristics in the upflow gas-liquid-solid reactor described herein can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0078] In summary, although this application has been disclosed above with reference to embodiments, it is not intended to limit this application. Those skilled in the art to which this application pertains can make various modifications and refinements without departing from the spirit and scope of this application. Therefore, the scope of protection of this application is determined by the claims.

Claims

1. A method for detecting bubble characteristics in an upflow gas-liquid-solid reactor, characterized in that, include: At least one hydrophone is placed on the liquid surface of the reactor, and each hydrophone collects the local acoustic signal generated by the bursting of bubbles at the corresponding position on the liquid surface of the reactor. Feature extraction is performed on the local acoustic signal to obtain feature parameters that describe the bubble breaking process; Based on the aforementioned feature parameters, the bubble characteristics are determined.

2. The method according to claim 1, characterized in that, The characteristic parameters include sound pressure characteristic amplitude, sound signal center frequency, sound signal characteristic frequency, and peak shape sound source characteristics; The envelope of the local acoustic signal is obtained, and the energy of the acoustic signal within each envelope peak is calculated. The corresponding peak value of the acoustic signal is determined as the sound pressure characteristic amplitude. For each envelope peak, the spectrum of the acoustic signal within the envelope peak and the center frequency of the acoustic signal are calculated by fast Fourier transform. The characteristic frequency of the acoustic signal is obtained by averaging the spectrum of all envelope peaks within the measurement time. In each spectrum, the high-amplitude portion at a fixed frequency is identified; the amplitude values ​​of all high-amplitude portions are added together and then divided by the sum of all amplitude values ​​at the fixed frequency to obtain a proportion, which is determined as the sound source characteristic of the peak shape.

3. The method according to claim 2, characterized in that, The bubble feature includes the bubble size; The bubble size is detected based on the characteristic amplitude of the sound pressure and the characteristic frequency of the sound signal. The bubble size is positively correlated with the sound pressure characteristic amplitude, and the bubble size is negatively correlated with the sound signal characteristic frequency.

4. The method according to claim 2 or 3, characterized in that, The bubble feature includes bubble frequency; The frequency of the bubble is detected based on the center frequency of the acoustic signal.

5. The method according to claim 3, characterized in that, The bubble feature includes the bubble rising speed; The surface tension of the liquid phase inside the reactor is detected based on the sound source characteristics of the described peak shape; The rising speed of the bubble is determined based on the surface tension of the liquid phase and the bubble size.

6. The method according to claim 1, characterized in that, Before performing feature extraction on the local acoustic signal, the method further includes: The local acoustic signal is preprocessed to remove noise.

7. The method according to claim 6, characterized in that, Noise is removed by employing one or more preprocessing methods, such as smoothing, differentiation, Fourier transform, and wavelet transform.

8. A device for detecting bubble characteristics in an upflow gas-liquid-solid reactor, characterized in that, The method for detecting bubble characteristics in an upflow gas-liquid-solid reactor according to any one of claims 1-6, wherein the apparatus comprises: At least one hydrophone is placed on the surface of the reactor liquid, and each hydrophone is used to collect the local acoustic signal generated by the bursting of bubbles at the corresponding position on the surface of the reactor liquid. A signal processing device is used to extract features from the local acoustic signal to obtain feature parameters describing the bubble breakage process; and to determine the bubble characteristics when the liquid surface breaks up based on the feature parameters.

9. The apparatus according to claim 8, characterized in that, When the at least one hydrophone is multiple hydrophones, the multiple hydrophones are evenly arranged on the surface of the reactor liquid in a horizontal direction.

10. The apparatus according to claim 8, characterized in that, Each hydrophone uses an acoustic emission sensor, and all acoustic sensors have the same frequency response characteristics, with a frequency response range of 1Hz to 10MHz.

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