CN201130136Y

CN201130136Y - Apparatus for measuring particle size distribution of discrete particles

Info

Publication number: CN201130136Y
Application number: CNU2007200750605U
Authority: CN
Inventors: 苏明旭; 蔡小舒; 薛明华; 尚志涛; 唐荣山
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2007-09-27
Filing date: 2007-09-27
Publication date: 2008-10-08
Anticipated expiration: 2017-09-27

Abstract

The utility model discloses a measuring device for particle size distribution in a discrete state, which relates to the technical field of ultrasonic measurement; what is to be solved is the technical problem of non-contact measurement of particle size distribution in a discrete state; the measuring device includes the use of complex wave number, objective function , distribution function and other calculation formulas to optimize the computer for calculating the particle size distribution, the signal processing circuit connected to the computer, the pulse wave transmitting/receiving circuit connected to the signal processing circuit, the broadband transducer connected to the pulse wave transmitting/receiving circuit, and the transducer device On the outside of the test board; the device is controlled by a computer, and the transmitting circuit sends out a pulsed electrical signal, which triggers the transducer to emit sound waves. Amplification and high-speed analog-to-digital conversion are transmitted to the computer for processing; the utility model has the characteristics of realizing complete non-contact measurement and online measurement of high-concentration and high-attenuation particle two-phase flow.

Description

Apparatus for measuring particle size distribution of discrete particles

技术领域technical field

本实用新型涉及超声测量技术，特别是涉及一种利用超声多次反射信号测量处于离散状态颗粒的粒度分布及其浓度的技术。The utility model relates to ultrasonic measurement technology, in particular to a technology for measuring particle size distribution and concentration of particles in a discrete state by using ultrasonic multiple reflection signals.

背景技术Background technique

对分散状态颗粒的粒度大小和浓度进行测量，在涉及两相流动的动力、化工、医药、环保、水利、材料等领域中具有广泛应用背景。与现有测量方法如筛分法、显微镜法、全息照相法、电感应法、沉降法等比较，超声法往往具有自动化程度高，能进行快速且准确的测量。同时由于超声波具有宽的频带范围，强穿透能力，可在有色甚至不透明的物质中传播并具有测量速度快，超声波传感器价格低且耐污损，特别适合作在线检测。The measurement of particle size and concentration of dispersed particles has a wide application background in the fields of power, chemical industry, medicine, environmental protection, water conservancy, materials and other fields involving two-phase flow. Compared with existing measurement methods such as sieving method, microscope method, holographic method, electric induction method, sedimentation method, etc., ultrasonic method often has a high degree of automation and can perform fast and accurate measurement. At the same time, because ultrasonic has a wide frequency range and strong penetrating ability, it can propagate in colored or even opaque substances and has fast measurement speed. Ultrasonic sensors are low in price and resistant to fouling, and are especially suitable for online detection.

现有的超声法颗粒测量手段中，采用穿透式或反射式对超声信号的测量，均需要超声波在待测对象中进行传播。在对高浓度和高衰减物质的测量过程中，超声波的传播声程有限，使得测量信号存在信噪比过小缺点，甚至不能检测到有效声信号，测量过程不能得以实现。In the existing ultrasonic particle measurement methods, the measurement of ultrasonic signals by means of penetration or reflection requires the propagation of ultrasonic waves in the object to be measured. In the process of measuring high-concentration and high-attenuation substances, the sound path of ultrasonic waves is limited, so that the signal-to-noise ratio of the measurement signal is too small, and even effective acoustic signals cannot be detected, and the measurement process cannot be realized.

同时现有多数方法采用了单一频率的超声波，没有注意到颗粒粒度和超声谱的关系，而超声谱(阻抗谱，衰减谱，速度谱)和颗粒粒度关系是非常密切的。At the same time, most existing methods use ultrasonic waves of a single frequency, without paying attention to the relationship between particle size and ultrasonic spectrum, and the relationship between ultrasonic spectrum (impedance spectrum, attenuation spectrum, velocity spectrum) and particle size is very close.

实用新型内容Utility model content

针对上述现有技术中存在的缺陷，本实用新型所要解决的技术问题是提供一种能实现完全的非接触测量，能对离散状态颗粒粒度分布的测量装置。Aiming at the defects in the above-mentioned prior art, the technical problem to be solved by the utility model is to provide a measuring device capable of realizing complete non-contact measurement and particle size distribution in discrete states.

为了解决上述技术问题，本实用新型所提供的一种对离散状态颗粒粒度分布的测量装置，包括进行数据处理的计算机，连接计算机的信号处理电路，连接信号处理电路的脉冲波发射/接收电路，连接脉冲波发射/接收电路的宽带换能器，换能器设于测试板外侧；所述装置由计算机控制，发射电路发出脉冲电信号，经触发换能器发出声波，超声波在测试板壁面一次以上反射后再由换能器接收，并经过信号处理电路的信号放大、高速模数(A/D)转换传输给计算机进行数据处理得到颗粒粒度分布；计算机设有用于显示测量结果的曲线和数据的屏幕。In order to solve the above-mentioned technical problems, a kind of measuring device for particle size distribution in discrete state provided by the utility model includes a computer for data processing, a signal processing circuit connected to the computer, a pulse wave transmitting/receiving circuit connected to the signal processing circuit, The broadband transducer connected to the pulse wave transmitting/receiving circuit is set outside the test board; the device is controlled by a computer, the transmitting circuit sends out a pulse electric signal, and the transducer is triggered to send out sound waves, and the ultrasonic wave is once on the wall of the test board After the above reflection, it is received by the transducer, and the signal is amplified by the signal processing circuit, and the high-speed analog-to-digital (A/D) conversion is transmitted to the computer for data processing to obtain the particle size distribution; the computer is equipped with curves and data for displaying measurement results screen.

进一步的，所述宽带换能器采用窄脉冲信号激励；脉冲信号越窄，包含的频谱信息就越丰富。Further, the broadband transducer is excited by a narrow pulse signal; the narrower the pulse signal, the richer the spectrum information contained.

进一步的，所述信号处理电路设有高速A/D转换单元和信号放大单元。Further, the signal processing circuit is provided with a high-speed A/D conversion unit and a signal amplification unit.

进一步的，所述宽带换能器为自发自收宽带换能器。Further, the broadband transducer is a self-generating and self-receiving broadband transducer.

进一步的，所述计算机设有用于保存测量结果的硬盘；供以后分析使用。Further, the computer is provided with a hard disk for saving measurement results; for later analysis.

进一步的，所述测试板为管道的侧壁。Further, the test board is the side wall of the pipeline.

进一步的，所述测试板选择其特征阻抗与颗粒样品的特征阻抗之比大于10，所述测量板特征阻抗和样品必须选择具有很大差异的物质(如不锈钢和水Z_钢/Z_水≈30)。Further, the ratio of the characteristic impedance of the test board to the characteristic impedance of the particle sample is greater than 10, and the characteristic impedance of the measurement board and the sample must be selected to have a very different material (such as stainless steel and water Z _steel /Z _water ≈ 30 ).

进一步的，所述测试板为探头凹槽一侧的反射板，反射板外侧设宽带换能器(压电片)，并由电缆线连接脉冲波发射/接收电路；宽带探头以法兰形式和管道连接或插入管道中作在线检测。Further, the test board is a reflection plate on one side of the probe groove, and a broadband transducer (piezoelectric sheet) is arranged on the outside of the reflection plate, and the pulse wave transmitting/receiving circuit is connected by a cable; the broadband probe is in the form of a flange and The pipeline is connected or inserted into the pipeline for online detection.

利用本实用新型提供的对离散状态颗粒粒度分布测量的装置，由于采用间接测量的方法，通过对多次超声反射信号的反射回波幅度和相位的测量，利用样品和标定物质的对比，计算得出颗粒样品中复声特性阻抗(与声速和声衰减有关)，并根据这些声特性阻抗谱再计算得出对高浓度和高衰减颗粒两相流的颗粒粒度分布及浓度。本实用新型提供的方法整个检测过程中声波不在样品中传播，无须穿透被测介质，不仅实现了完全的非接触测量，而且非常适合对于高浓度、高衰减样品的检测。Utilize the device for measuring the particle size distribution of the discrete state provided by the utility model, due to the indirect measurement method, through the measurement of the reflected echo amplitude and phase of multiple ultrasonic reflection signals, using the comparison between the sample and the calibration substance, the calculated The complex acoustic characteristic impedance (related to sound velocity and sound attenuation) in the particle sample is calculated, and the particle size distribution and concentration of high-concentration and high-attenuation particle two-phase flow are calculated based on these acoustic characteristic impedance spectra. The method provided by the utility model does not transmit sound waves in the sample during the whole detection process, and does not need to penetrate the measured medium, which not only realizes complete non-contact measurement, but also is very suitable for the detection of high-concentration and high-attenuation samples.

附图说明Description of drawings

图1是本实用新型实施例对离散状态颗粒粒度分布测量的装置的结构示意图；Fig. 1 is the structural representation of the device for measuring the particle size distribution of discrete state particles in the embodiment of the present invention;

图2是本实用新型实施例中多次反射信号的曲线示意图；Fig. 2 is a schematic diagram of curves of multiple reflection signals in an embodiment of the present invention;

图3是本实用新型实施例中多次反射信号的谱和粒度之间关系的曲线示意图；Fig. 3 is the schematic diagram of the curve of the relationship between the spectrum and granularity of multiple reflection signals in the embodiment of the present invention;

图4是本实用新型实施例中测量探头的结构示意图。Fig. 4 is a schematic structural diagram of the measuring probe in the embodiment of the present invention.

具体实施方式Detailed ways

以下结合附图说明对本实用新型的实施例作进一步详细描述，但本实施例并不用于限制本实用新型，凡是采用本实用新型的相似结构及其相似变化，均应列入本实用新型的保护范围。The embodiments of the present utility model are described in further detail below in conjunction with the accompanying drawings, but the present embodiments are not intended to limit the present utility model. All similar structures and similar changes of the utility model should be included in the protection of the utility model. scope.

本实用新型实施例的理论模型和反演技术计算：如图1所示，换能器4发射超声波在板5内多次反射，对其分别在待测样品(指由颗粒和液体连续介质构成的混合物)和标定物质中进行测试，其反射系数有如下关系：Theoretical model and inversion technology calculation of the embodiment of the present utility model: as shown in Figure 1, transducer 4 emits ultrasonic waves and is reflected multiple times in plate 5, respectively to them in the sample to be tested (referring to be made of particle and liquid continuous medium) The mixture) and the calibration substance are tested, and the reflection coefficient has the following relationship:

${((\frac{{R R}_{s the s}}{{R R}_{c c}}))}^{n no} = = \frac{{M m}_{s the s}}{{M m}_{c c}} exp exp [[i i (({θ θ}_{s the s} - - {θ θ}_{c c}))]]$

其中，R_s和R_c分别为对样品和标定物质进行测试时的反射系数，n为反射次数(反射次数增加可以削弱测量信号误差影响，但具体次数视装置和信号而定)；M和θ分别为反射回波的幅度和相位，借助标定物质(如蒸馏水)换算出待测样品中的反射系数R_s。Among them, R _s and R _c are the reflection coefficients when testing samples and calibration materials, respectively, and n is the number of reflections (increasing the number of reflections can weaken the influence of measurement signal errors, but the specific number depends on the device and signal); M and θ are the amplitude and phase of the reflected echo respectively, and the reflection coefficient R _s in the sample to be measured is converted by means of a calibration substance (such as distilled water).

${Z Z}_{s the s} = = {Z Z}_{b b} ((\frac{11 + + {R R}_{s the s}}{11 - - {R R}_{s the s}}))$

其中Z_b表示壁面的声学阻抗，Z_s表示复数形式的含颗粒样品的声学特性阻抗，有：Where Z _b represents the acoustic impedance of the wall, Z _s represents the acoustic characteristic impedance of the particle-containing sample in complex form, as follows:

κ＝Z_s/ωρ_s κ=Z _s /ωρ _s

这里ω为声波角频率，ρ_s为样品密度，高浓度颗粒两相体系中复波数κ按照声波动理论：Here ω is the angular frequency of the acoustic wave, ρ _s is the sample density, and the complex wave number κ in the high-concentration particle two-phase system is according to the acoustic wave theory:

${κ κ}^{22} = = {ω ω}^{22} {k k}_{a a}^{* *} \times \times \frac{ρ ρ [[{ρ ρ}^{' '} ((11 - - φ φ + + φS φS)) + + ρS ρS ((11 - - φ φ))]]}{{ρ ρ}^{' '} {((11 - - φ φ))}^{22} + + ρ ρ [[S S + + φ φ ((11 - - φ φ))]]}$

式中：φ为颗粒浓度，ρ和ρ′分别为连续介质和颗粒密度，k_a ^*为绝热压缩系数，S与浓度，粒度和物性有关。In the formula: φ is the particle concentration, ρ and ρ′ are the continuum medium and particle density respectively, k _a ^* is the adiabatic compressibility coefficient, S is related to the concentration, particle size and physical properties.

同样复波数与声衰减系数和声速，κ＝ω/c-jα，c为声速，j为虚数单位，α为声衰减系数；将公式：κ＝ω/c-jα中复波数按实部(与声速c有关)或虚部(与衰减α有关)分离，根据超声衰减谱和粒度之间关系，可将测量数据和事先设想颗粒系的理论衰减谱误差设为目标函数进行优化；可对设定的不同频率计算超声衰减系数α_theory(f_i)，同样前述测量装置中采用宽带换能器发射接收超声信号，测量超声反射系数和复阻抗Z_s，由公式Z_s＝ωρ_s/κ，换算得复波数和超声衰减系数α_meas(f_i)(注意该超声衰减系数实际由测量值经换算得，故又可称实验测得超声衰减系数)，据此，由理论和实验超声衰减谱构造如下的误差目标函数：The same complex wave number and sound attenuation coefficient and sound velocity, κ=ω/c-jα, c is the sound velocity, j is the imaginary number unit, and α is the sound attenuation coefficient; Formula: the complex wave number in κ=ω/c-jα is pressed by real part ( related to the sound velocity c) or the imaginary part (related to the attenuation α), according to the relationship between the ultrasonic attenuation spectrum and the particle size, the measurement data and the theoretical attenuation spectrum error of the pre-conceived particle system can be set as the objective function for optimization; Calculate the ultrasonic attenuation coefficient α _theory (f _i ) at different frequencies. Similarly, the aforementioned measurement device uses a broadband transducer to transmit and receive ultrasonic signals to measure the ultrasonic reflection coefficient and complex impedance Z _s . The formula Z _s = ωρ _s /κ, Converted complex wave number and ultrasonic attenuation coefficient α _meas (f _i ) (note that the ultrasonic attenuation coefficient is actually converted from the measured value, so it can also be called the experimentally measured ultrasonic attenuation coefficient). Construct the following error objective function:

$E E. = = \sqrt{\frac{{Σ Σ}_{i i = = 11}^{{N N}_{f f}} {((\frac{{α α}_{meas meas} (({f f}_{i i})) - - {α α}_{theory theory} (({f f}_{i i}))}{{α α}_{theory theory,, i i}}))}^{22}}{{N N}_{f f}}};;$

当该误差越小，表明理论衰减值和实验值吻合得越好。这样，可以按照最优化理论进行优化。为计算颗粒粒度分布，需要将颗粒粒度分布采用某一或一组函数形式进行描述，可采用Rosin-Ramma函数，正态分布或对数正态分布等；上述3种函数分布均包含一个名义尺寸参数和分布宽度参数，它们在优化时称待定参数，如得以确定，即可完全获得颗粒粒度分布。在进行优化时，事先人为设定初始参数，计算出理论超声衰减和初始目标函数，按照最优化的理论中的Davidon-Fletcher-Powell(DFP)方法，在初始参数附近唯一地确定局部最优解，为获得全局最优解，重新设定初始值并最终选择目标函数最小的解为最终求解结果。同时，为避免出现非物理解情况(如待定参数为负)，可以采用罚函数手段。在获得求解参数后，带入颗粒粒度分布参数函数计算颗粒粒度分布(频率分布和累计分布)；本实用新型除了采用DFP(Davidon-Fletcher-Powell)方法之外，还可用最速下降法(Steepest Descent method)和模拟退火法(Simulated Annealing method)等优化方法。The smaller the error, the better the agreement between the theoretical attenuation value and the experimental value. In this way, optimization can be carried out according to the optimization theory. In order to calculate the particle size distribution, the particle size distribution needs to be described by a certain function or a group of functions, such as Rosin-Ramma function, normal distribution or lognormal distribution, etc.; the above three function distributions all include a nominal size Parameters and distribution width parameters, which are called undetermined parameters during optimization, if determined, the particle size distribution can be fully obtained. When optimizing, the initial parameters are artificially set in advance, the theoretical ultrasonic attenuation and the initial objective function are calculated, and the local optimal solution is uniquely determined near the initial parameters according to the Davidon-Fletcher-Powell (DFP) method in the optimization theory , in order to obtain the global optimal solution, reset the initial value and finally select the solution with the smallest objective function as the final solution result. At the same time, in order to avoid non-physical understanding (such as the undetermined parameter is negative), a penalty function can be used. After obtaining the solution parameters, bring in the particle size distribution parameter function to calculate the particle size distribution (frequency distribution and cumulative distribution); the utility model can also use the steepest descent method (Steepest Descent) except using the DFP (Davidon-Fletcher-Powell) method. method) and simulated annealing method (Simulated Annealing method) and other optimization methods.

如图1所示，本实用新型实施例所提供的一种对离散状态颗粒粒度分布测量的装置，包括进行数据处理的计算机1，连接计算机1的设有高速A/D转换单元和信号放大单元的信号处理电路2，连接信号处理电路2的脉冲波发射/接收电路3，连接脉冲波发射/接收电路的自发自收宽带换能器4，为很好的触发宽带换能器，采用了窄脉冲信号激励，脉冲信号越窄，包含的频谱信息就越丰富；宽带换能器4设于管道壁5的外侧；装置由计算机1控制，发射电路3发出脉冲电信号，经触发换能器4发出声波，声波在壁面5多次反射后再由换能器4接收，6为待测颗粒样品(和许多现有测量手段不同，本实用新型研究超声波仅在测量板内传播，不通过待测颗粒对象，因此信号受高浓度高衰减颗粒削弱影响极小，为确保多次反射，测量板特征阻抗应选用和样品具有很大差异的物质，如不锈钢和水Z_钢/Z_水≈30，所述测试板选择其特征阻抗与颗粒样品的特征阻抗之比大于10；)，并经过信号放大单元、高速A/D转换单元传输给计算机1处理，由公式：As shown in Figure 1, a kind of device for the particle size distribution measurement of discrete state provided by the embodiment of the present utility model, comprises the computer 1 that carries out data processing, is connected with computer 1 and is provided with high-speed A/D conversion unit and signal amplifying unit The signal processing circuit 2 of the signal processing circuit 2 is connected to the pulse wave transmitting/receiving circuit 3 of the signal processing circuit 2, and the self-generating and self-receiving broadband transducer 4 connected to the pulse wave transmitting/receiving circuit is used to trigger the broadband transducer well. Pulse signal excitation, the narrower the pulse signal, the richer the spectrum information contained; the broadband transducer 4 is arranged outside the pipeline wall 5; Send out sound waves, and the sound waves are received by the transducer 4 after multiple reflections on the wall surface 5, and 6 is the particle sample to be measured (different from many existing measurement methods, the utility model researches that the ultrasonic wave only propagates in the measurement plate, and does not pass through the to-be-measured Particle objects, so the signal is minimally affected by the weakening of high-concentration and high-attenuation particles. In order to ensure multiple reflections, the characteristic impedance of the measurement plate should be selected from a material that is very different from the sample, such as stainless steel and water Z _steel / Z _water ≈ 30, so The test board selects the ratio of its characteristic impedance and the characteristic impedance of the particle sample to be greater than 10;), and transmits to the computer 1 through the signal amplification unit and the high-speed A/D conversion unit for processing, by the formula:

${(\frac{R_{s}}{R_{c}})}^{n} = \frac{M_{s}}{M_{c}} \exp [i (θ_{s} - θ_{c})],$ $Z_{s} = Z_{b} (\frac{1 + R_{s}}{1 - R_{s}})$ 和κ＝Z_s/ωρ_s； ${(\frac{R_{the s}}{R_{c}})}^{no} = \frac{m_{the s}}{m_{c}} \exp [i (θ_{the s} - θ_{c})],$ $Z_{the s} = Z_{b} (\frac{1 + R_{the s}}{1 - R_{the s}})$ and κ=Z _s /ωρ _s ;

换算得反射系数和复声特性阻抗谱(随频率不同而改变频域信号)，按照复波数的计算公式：The converted reflection coefficient and complex sound characteristic impedance spectrum (the frequency domain signal changes with the frequency), according to the calculation formula of the complex wave number:

${κ κ}^{22} = = {ω ω}^{22} {k k}_{a a}^{* *} \times \times \frac{ρ ρ [[{ρ ρ}^{' '} ((11 - - φ φ + + φS φS)) + + ρS ρS ((11 - - φ φ))]]}{{ρ ρ}^{' '} {((11 - - φ φ))}^{22} + + ρ ρ [[S S + + φ φ ((11 - - φ φ))]]};;$

将复波数按实部(与声速c有关)或虚部(与衰减α有关)分离，并根据谱和粒度之间关系分析，将测量数据和设想粒度的理论谱的误差设为目标函数进行优化，经公式：κ＝ω/c-jα；计算得理论超声衰减谱，并和实验数据换算超声衰减谱构造目标函数： $E = \sqrt{\frac{Σ_{i = 1}^{N_{f}} {(\frac{α_{meas} (f_{i}) - α_{theory} (f_{i})}{α_{theory, i}})}^{2}}{N_{f}}};$ The complex wave number is separated according to the real part (related to the sound velocity c) or the imaginary part (related to the attenuation α), and according to the analysis of the relationship between the spectrum and the particle size, the error between the measured data and the theoretical spectrum of the assumed particle size is set as the objective function for optimization , through the formula: κ=ω/c-jα; calculate the theoretical ultrasonic attenuation spectrum, and convert the ultrasonic attenuation spectrum to the experimental data to construct the objective function: $E. = \sqrt{\frac{Σ_{i = 1}^{N_{f}} {(\frac{α_{meas} (f_{i}) - α_{theory} (f_{i})}{α_{theory, i}})}^{2}}{N_{f}}};$

采用DFP优化方法，求解分布函数参数并计算得颗粒粒度分布；计算机设有用于显示测量结果的曲线和数据的屏幕。本实用新型除了采用DFP(Davidon-Fletcher-Powell)方法之外，还可用最速下降法(Steepest Descentmethod)和模拟退火法(Simulated Annealing method)等优化方法。The DFP optimization method is used to solve the distribution function parameters and calculate the particle size distribution; the computer is equipped with a screen for displaying the curve and data of the measurement results. In addition to the DFP (Davidon-Fletcher-Powell) method, the utility model can also use optimization methods such as steepest descent method (Steepest Descent method) and simulated annealing method (Simulated Annealing method).

在本实用新型实施例中，也可以对多次信号的幅度(即M_S)的对数作线性拟合(如图3)，并按R_S/R_c＝exp(斜率_S-斜率_c)，计算反射系数，消除了由于换能器发射功率变化引起的测量误差。由 $Z_{s} = Z_{b} (\frac{1 + R_{s}}{1 - R_{s}})$ 进一步计算声特性阻抗Z_s。按公式Z_s＝ρ_sc，如果平均密度已知，则由c＝Z_s/ρ_s可获得声速；如果声速可测，则由ρ_s＝Z_s/c换算平均密度。In the utility model embodiment, also can do linear fitting (as shown in Figure 3) to the logarithm of the amplitude (ie M _S ) of multiple signals, and press R _S /R _c =exp (slope _S -slope _c ) , to calculate the reflection coefficient, which eliminates the measurement error caused by the change of the transducer transmission power. Depend on $Z_{the s} = Z_{b} (\frac{1 + R_{the s}}{1 - R_{the s}})$ Further calculate the acoustic characteristic impedance Z _s . According to the formula Z _s = ρ _s c, if the average density is known, the sound velocity can be obtained from c = Z _s /ρ _s ; if the sound velocity can be measured, the average density can be converted from ρ _s = Z _s /c.

如图4所示，本实用新型另一实施例采用宽带探头，将测量部件做成探头形式，在探头凹槽的一侧设反射板7，反射板外侧设宽带换能器8，并由电缆线9连接脉冲波发射/接收电路；宽带探头以法兰形式和管道连接或插入管道中作在线检测，对时域信号作快速傅立叶变换得超声幅值相位谱，以中心频率10MHz宽带换能器为例，其在-6dB内衰减包含频率范围约5～15MHz，为反演提供了丰富的频谱信息，此时由于仅仅使用了单个换能器，使得装置结构简化。As shown in Figure 4, another embodiment of the utility model adopts a broadband probe, and the measuring part is made into a probe form, and a reflector 7 is arranged on one side of the probe groove, and a broadband transducer 8 is arranged on the outside of the reflector, and is connected by a cable Line 9 is connected to the pulse wave transmitting/receiving circuit; the broadband probe is connected to the pipeline in the form of a flange or inserted into the pipeline for online detection, and the time domain signal is fast Fourier transformed to obtain the ultrasonic amplitude phase spectrum, and the center frequency is 10MHz. For example, its attenuation within -6dB covers a frequency range of about 5-15MHz, which provides rich spectrum information for inversion. At this time, only a single transducer is used, which simplifies the structure of the device.

本实用新型实施例的对离散状态颗粒粒度分布测量的原理，包括以下步骤：The principle of measuring the particle size distribution of the discrete state particles in the embodiment of the present invention comprises the following steps:

1)多次反射法测量样品和标定物质：由收/发换能器发射的单个窄脉冲信号多次反射后所述收/发换能器采集多次超声反射信号，对离散状态颗粒的样品和标定物质进行测量；1) Measurement of samples and calibration substances by multiple reflection method: After multiple reflections of a single narrow pulse signal emitted by the receiving/transmitting transducer, the receiving/transmitting transducer collects multiple ultrasonic reflection signals, and the samples of discrete particles and calibration substances for measurement;

2)计算反射系数和声特性阻抗：在数据处理的计算机中由公式：2) Calculate reflection coefficient and acoustic characteristic impedance: in the computer of data processing by formula:

${(\frac{R_{s}}{R_{c}})}^{n} = \frac{M_{s}}{M_{c}} \exp [i (θ_{s} - θ_{c})]$ 和 $Z_{s} = Z_{b} (\frac{1 + R_{s}}{1 - R_{s}}),$ 利用样品和标定物质的对比，计算出颗粒样品中的反射系数和复声特性阻抗(与超声频率有关，可换算声速和声衰减)； ${(\frac{R_{the s}}{R_{c}})}^{no} = \frac{m_{the s}}{m_{c}} \exp [i (θ_{the s} - θ_{c})]$ and $Z_{the s} = Z_{b} (\frac{1 + R_{the s}}{1 - R_{the s}}),$ Using the comparison between the sample and the calibration substance, calculate the reflection coefficient and complex acoustic characteristic impedance in the particle sample (related to the ultrasonic frequency, and can convert the sound velocity and sound attenuation);

3)计算颗粒粒度分布、浓度：在数据处理的计算机中由公式：3) calculate particle size distribution, concentration: in the computer of data processing by formula:

和κ＝ω/c-jα；即根据声特性阻抗谱、复波数计算得出对高浓度颗粒两相流的颗粒粒度分布及浓度；将测量数据和设想粒度的理论谱的误差设为目标函数进行优化，经公式：κ＝ω/c-jα；计算得理论超声衰减谱，并和实验数据换算得超声衰减谱构造目标函数： $E = \sqrt{\frac{Σ_{i = 1}^{N_{f}} {(\frac{α_{meas} (f_{i}) - α_{theory} (f_{i})}{α_{theory, i}})}^{2}}{N_{f}}};$ and κ=ω/c-jα; that is, the particle size distribution and concentration of high-concentration particle two-phase flow are calculated according to the acoustic characteristic impedance spectrum and complex wave number; the error between the measured data and the theoretical spectrum of the assumed particle size is set as the objective function For optimization, the formula: κ=ω/c-jα; calculate the theoretical ultrasonic attenuation spectrum, and convert the experimental data to obtain the ultrasonic attenuation spectrum to construct the objective function: $E. = \sqrt{\frac{Σ_{i = 1}^{N_{f}} {(\frac{α_{meas} (f_{i}) - α_{theory} (f_{i})}{α_{theory, i}})}^{2}}{N_{f}}};$

按照DFP方法进行优化确定待定参数，可以在初始参数附近得局部最优解，为获得全局最优求解，应重新设定初始值并最终选择目标函数最小的结果极为最终求解结果。同时，为避免出现非物理解情况(如参数为负数)，可以采用罚函数手段。在获得待定参数后，带入颗粒粒度分布参数函数计算颗粒粒度的频率分布和累计分布。本实用新型除了采用DFP(Davidon-Fletcher-Powell)方法之外，还可用最速下降法(Steepest Descent method)和模拟退火法(Simulated Annealing method)等优化方法。According to the DFP method to optimize and determine the undetermined parameters, the local optimal solution can be obtained near the initial parameters. In order to obtain the global optimal solution, the initial value should be reset and the result with the smallest objective function should be finally selected as the final solution result. At the same time, in order to avoid non-physical understanding (such as negative parameters), a penalty function can be used. After the undetermined parameters are obtained, the particle size distribution parameter function is used to calculate the frequency distribution and cumulative distribution of the particle size. In addition to adopting the DFP (Davidon-Fletcher-Powell) method, the utility model can also use optimization methods such as steepest descent method (Steepest Descent method) and simulated annealing method (Simulated Annealing method).

4)测量结果以曲线和数据的形式直接显示在计算机屏幕上，同时保存在硬盘上供以后分析使用。4) The measurement results are directly displayed on the computer screen in the form of curves and data, and are saved on the hard disk for later analysis.

本实用新型所述计算机包括单板机、单片机、可编程微处理器和DSP(数字处理芯片等。The computer described in the utility model includes a single-board computer, a single-chip microcomputer, a programmable microprocessor and a DSP (digital processing chip, etc.).

Claims

1. A measuring device for particle size distribution in a discrete state is characterized in that it includes a computer for data processing, a signal processing circuit connected to the computer, a pulse wave transmitting/receiving circuit connected to the signal processing circuit, and a pulse wave transmitting/receiving circuit connected to the signal processing circuit. The broadband transducer of the circuit, the transducer is arranged on the outside of the test board;

The device is controlled by a computer, and the transmitting circuit sends out a pulsed electrical signal, which triggers the transducer to send out sound waves, and the ultrasonic wave is reflected by the wall of the test board for more than one time and then received by the transducer, and the signal is amplified by the signal processing circuit, and the high-speed modulus Convert and transmit to computer for data processing to obtain particle size distribution;

The computer is equipped with a screen for displaying curves and data of the measurement results.

2. The device for measuring particle size distribution of discrete particles according to claim 1, characterized in that the broadband transducer is excited by a narrow pulse signal.

3. The device for measuring particle size distribution of discrete particles according to claim 1, wherein the signal processing circuit is provided with a high-speed analog-to-digital conversion unit and a signal amplification unit.

4. The device for measuring the particle size distribution of discrete particles according to claim 1, wherein the broadband transducer is a self-generating and self-receiving broadband transducer.

5. The device for measuring the particle size distribution of discrete particles according to claim 1, wherein the computer is provided with a hard disk for saving the measurement results.

6. The device for measuring particle size distribution of discrete particles according to claim 1, wherein the test plate is a side wall of a pipeline.

7. The device for measuring the particle size distribution of discrete particles according to claim 1, characterized in that the ratio of the characteristic impedance of the test plate to the characteristic impedance of the particle sample is selected to be greater than 10.

8. The device for measuring particle size distribution in a discrete state according to claim 1, wherein the test board is a reflector on one side of the probe groove, and a wide-band transducer is arranged on the outside of the reflector, and is connected by a cable Connect the pulse wave transmitting/receiving circuit; the broadband probe is connected to the pipeline in the form of a flange or inserted into the pipeline for online detection.