A device and method for on-line monitoring of particle concentration in liquid-solid two-phase flow based on turbidimeter

Abstract

The application discloses a kind of on-line monitoring device and method of particle concentration in liquid-solid two-phase flow based on turbidimeter, belong to liquid-solid two-phase flow particle concentration on-line measurement technical field.The device of the present application includes first turbidity sensor, second turbidity sensor, third turbidity sensor, liquid-solid sampling system, transmitter and computer processing system, first turbidity sensor is located in any position in liquid-solid two-phase flow, liquid-solid sampling system includes sampling pipeline, three-way valve, liquid-solid bed and vent valve, transmitter converts the light signal of sensor into turbidity value and then transmits data into computer, combined with the turbidity value of second and third turbidity sensors in liquid-solid bed under full bed and empty bed state, the particle concentration of local position in liquid-solid two-phase flow system can be obtained.The on-line monitoring device is not affected by the change of liquid-solid two-phase property in system, with the advantages of low cost, high precision, wide range of use and flexible and simple operation.

Description

Technical Field

[0001] This invention belongs to the field of online measurement technology of particle concentration in liquid-solid two-phase flow, and particularly relates to an online measurement device and method for solid particle concentration in liquid-solid two-phase flow systems where the properties of the liquid or solid phase may change. Background Technology

[0002] Liquid-solid two-phase flow systems are widely used in chemical, petroleum, pharmaceutical, food, and environmental protection industries. In particular, liquid-solid two-phase reactors are crucial reaction equipment, integrating multiple disciplines such as fluid mechanics, heat and mass transfer, physical chemistry, and chemical reaction kinetics. Fundamental research on liquid-solid multiphase systems is essential. In this research, the concentration of solid particles within the liquid-solid two-phase system is a key parameter affecting flow, mass transfer, and reaction within the system, directly influencing reactor performance. Therefore, real-time monitoring of particle concentration at local locations within the liquid-solid two-phase system is of great significance.

[0003] Liquid-solid fluidized bed reactors are a typical example of liquid-solid two-phase flow and are widely used in petrochemical, biological, and environmental fields. However, complex multiphase flows exist in liquid-solid fluidized bed reactors, particularly the complex interactions between flow, heat transfer, mass transfer, and reaction. This lack of theoretical guidance hinders the industrial-scale promotion and application of this type of reactor. Measurement techniques for particle concentration in multiphase flow systems vary significantly between laboratory research and industrial production. Currently, methods for measuring local particle concentration in chemical reactors mainly include sampling methods, conductivity methods, optical methods, CT, and ultrasound. Sampling methods are difficult to implement at constant velocity and are cumbersome, making online detection impossible. Conductivity methods utilize the conductivity of the liquid and solid phases, but changes in liquid phase composition and experimental temperature significantly affect conductivity properties. Reports on CT and ultrasound techniques for measuring particle concentration are limited, with applications currently confined to experimental studies in gas-solid fluidized bed reactors. Furthermore, these devices are very expensive, with high maintenance and commissioning costs, preventing large-scale industrial applications. Optical methods are characterized by ease of use, flexible measurement, minimal interference from external factors, and a wide measurement range, making them one of the effective methods for measuring local particle concentration in liquid-solid two-phase flows.

[0004] A turbidimeter is an optical measuring instrument based on the principle of light scattering and transmission in a turbid liquid-solid two-phase system. It is a typical instrument for measuring particle concentration using optical methods and is currently mainly used in wastewater treatment, chemical, metallurgical, pharmaceutical, chemical fiber, and fermentation industries to monitor the turbidity, i.e., the concentration of suspended particles, within the system. For measuring particle concentration in a liquid-solid fluidized bed reactor, the turbidity versus particle concentration calibration curve of the turbidimeter can be obtained based on the properties of the particles and the liquid phase, thus providing online particle concentration data. However, in industrial liquid-solid two-phase flow reactors, the liquid phase is mostly the reactant or product material, while the solid particles are the catalyst. As the reaction proceeds, the optical properties of the liquid product and the catalyst may change, leading to inaccurate turbidity versus particle concentration calibration curves obtained in the initial stage, making long-term online particle concentration measurement impossible.

[0005] Invention patent CN112816378A discloses a real-time online measurement method for aerosol concentration based on a turbidimeter. The method involves aerosol sampling, cooling, and water washing to obtain a liquid-solid suspension. The turbidity value of the suspension is then measured in real time. The mass concentration of particles in the aerosol is calculated by combining the total volume of cold water, sampling time, non-condensable gas flow rate, and water vapor fraction. However, this method is complex and cumbersome, and cannot meet the requirements for online monitoring of particle concentration in chemical processes, especially in liquid-solid two-phase fluidized bed reactors.

[0006] Invention patent CN102109455A discloses a method for local particle concentration in a liquid-solid two-phase system. This method receives infrared light reflected from solid particles, converts the optical signal into an electrical signal, and then obtains the particle concentration at a local location in the system by analyzing the relationship between the electrical signal and the particle concentration, thus achieving online measurement of particle concentration in the liquid-solid two-phase system. However, for industrial production systems, this method cannot adjust the relationship between the electrical signal and particle concentration. It is only applicable to the liquid and particle phases at the time of calibration. For systems where the liquid or particle phase changes during the reaction, accurate measurement is not possible. In such cases, the measuring instrument must be recalibrated using the changed liquid and particle phases after production has ceased before measurement and characterization can be performed. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide an online monitoring device and method for particle concentration in liquid-solid two-phase flow based on a turbidimeter. By using the device and method of this invention, not only can the online monitoring of particle concentration in liquid-solid two-phase flow system be realized, but the calibration curve of turbidity value and particle concentration can also be corrected to adapt to reaction systems where the properties of the liquid or particulate phases change. This avoids the need for recalibration of the testing instrument, which would cause the device to shut down, and greatly improves the simplicity and flexibility of particle concentration measurement in liquid-solid two-phase systems, especially in liquid-solid fluidized bed reactors.

[0008] The objective of this invention is achieved through the following means:

[0009] This invention provides an online monitoring device for particle concentration in a liquid-solid two-phase flow based on a turbidity meter. The online particle concentration monitoring device includes a first turbidity sensor, a second turbidity sensor, a third turbidity sensor, a liquid-solid sampling system, a transmitter, and a computer processing system. The first turbidity sensor is located at any position within the liquid-solid two-phase flow system. The liquid-solid sampling system includes a sampling pipeline, a three-way valve, a liquid-solid bed, and a vent valve. The vent valve is connected to the top of the liquid-solid bed via a pipeline, and the bottom of the liquid-solid bed is connected to the outlet I of the three-way valve via a pipeline. The liquid-solid two-phase flow system is connected to the inlet of the three-way valve via a pipeline, and the outlet II of the three-way valve is connected to a waste liquid pipeline. The second turbidity sensor is located at the bottom of the liquid-solid bed, and the third turbidity sensor is located in the upper middle part of the liquid-solid bed. The first, second, and third turbidity sensors are all connected to the transmitter, and the transmitter is connected to the computer processing system via a data transmission line.

[0010] Based on the above technical solution, the third turbidity sensor is further located at 1 / 2 to 4 / 5 of the height of the liquid-solid bed.

[0011] Based on the above technical solution, the transmitter further converts the optical signals detected by the first turbidity sensor, the second turbidity sensor and the third turbidity sensor into electrical signals or turbidity values ​​and then transmits them to the computer processing system.

[0012] Another aspect of the present invention provides the application of the above-described online monitoring device in detecting particle concentration in liquid-solid two-phase flow systems or gas-solid two-phase flow systems.

[0013] Based on the above technical solution, the optical properties of the liquid phase and / or solid phase in the liquid-solid two-phase flow system may or may not change over time.

[0014] Based on the above technical solution, the liquid phase in the liquid-solid two-phase flow system includes, but is not limited to, water, methanol, ethanol, tert-butanol, acetone, soluble salt solutions, etc.

[0015] Based on the above technical solution, the particle size of the solid phase particles is further 0.1 to 5000 μm.

[0016] Based on the above technical solution, the mass percentage concentration of the solid particles is further 0.001% to 60%.

[0017] The present invention also provides a method for detecting particle concentration in a liquid-solid two-phase flow system using the above-mentioned online monitoring device, which mainly includes the following steps:

[0018] For systems where the optical properties of the liquid phase and / or solid phase do not change, a series of standard curves of solid particle concentration versus voltage or turbidity value are first generated using a first turbidity sensor. Then, the voltage or turbidity value in the liquid-solid two-phase flow system is detected using the first turbidity sensor, substituted into the standard curves, and the particle concentration in the liquid-solid two-phase flow system is calculated.

[0019] For systems where the optical properties of the liquid and / or solid phases change, the turbidity and particle concentration of the solid phase in the liquid-solid two-phase flow system are detected by a liquid-solid sampling system, a second turbidity sensor, and a third turbidity sensor under full-bed and empty-bed conditions. Then, a series of standard curves of solid particle concentration versus voltage or turbidity values ​​generated by the first turbidity sensor are corrected. Finally, the voltage or turbidity value in the liquid-solid two-phase flow system is detected by the first turbidity sensor, and the corrected standard curves are substituted to calculate the particle concentration in the liquid-solid two-phase flow system.

[0020] Based on the above technical solution, further, for systems where the optical properties of the liquid phase and / or solid phase change, the method includes the following steps:

[0021] (1) Open the vent valve at the top of the liquid-solid bed and rotate the three-way valve at the bottom of the liquid-solid bed to connect the bottom of the liquid-solid bed with the liquid-solid two-phase flow system, so that the two-phase mixture in the liquid-solid two-phase flow flows into the liquid-solid bed. When the liquid-solid two phases in the liquid-solid bed reach more than 2 / 3 of the height of the liquid-solid bed, rotate the three-way valve to disconnect the liquid-solid bed from the liquid-solid two-phase flow system.

[0022] (2) After the particles in the liquid-solid bed have settled freely to the bottom of the bed, the turbidity value and particle concentration of the liquid-solid bed in the full-bed state and the empty-bed state are detected by the second turbidity sensor and the third turbidity sensor, respectively, and recorded as (N0, W0) and (N0, W0) respectively. f W f );

[0023] (3) Based on the turbidity and particle concentration obtained in step (2) under full bed and empty bed conditions, a series of standard curves of solid particle concentration and voltage or turbidity values ​​prepared by the first turbidity sensor are corrected. Then, the voltage or turbidity value in the liquid-solid two-phase flow system is detected by the first turbidity sensor, and the corrected standard curve is substituted to calculate the particle concentration in the liquid-solid two-phase flow system.

[0024] Based on the above technical solution, further, after the measurement is completed, the material in the liquid-solid bed is discharged through the three-way valve at the bottom of the liquid-solid bed, or a certain amount of liquid or gas is introduced through the vent valve to transport the liquid-solid two-phase flow back into the liquid-solid two-phase flow system.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) The online monitoring device for particle concentration in liquid-solid two-phase flow based on turbidimeter provided by the present invention has a simple structure, is easy to operate, and has low cost, and has great industrial application value.

[0027] (2) The online monitoring device and method for particle concentration in a liquid-solid two-phase flow based on a turbidimeter provided by this invention obtains particle concentration data under conventional conditions by utilizing the relationship between standard liquid and particles, as well as turbidity value and particle concentration. Furthermore, to overcome the possibility that the optical properties of the liquid or particle phase in the liquid-solid two-phase reactor may change, the original calibration curve of the first turbidity sensor is corrected by combining the turbidity values ​​of the liquid-solid bed under empty and full-bed conditions in the online sampling system. This effectively solves the problem of measurement deviation caused by possible changes in the properties of the liquid or particle phase in the liquid-solid two-phase system. It has advantages such as low cost, high accuracy, wide application range, and flexible and simple operation. Attached Figure Description

[0028] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0029] Figure 1 This is a schematic diagram of an online particle concentration monitoring device in a liquid-solid two-phase flow based on a turbidity meter according to the present invention, wherein 1-first turbidity sensor, 2-second turbidity sensor, 3-third turbidity sensor, 4-liquid-solid online sampling system, 5-transmitter, 6-computer processing system, 7-liquid-solid two-phase flow system, 201-sampling pipeline, 202-three-way valve, 203-liquid-solid bed, and 204-vent valve.

[0030] Figure 2 This is a schematic diagram of an online particle concentration monitoring device based on a turbidimeter in a liquid-solid two-phase flow, connected to a liquid-solid stirring system, as shown in Example 1. The components are: 1-first turbidity sensor, 2-second turbidity sensor, 3-third turbidity sensor, 4-liquid-solid online sampling system, 5-transmitter, 6-computer processing system, 7-liquid-solid two-phase flow system, 8-stirrer, 201-sampling pipeline, 202-three-way valve, 203-liquid-solid bed, and 204-vent valve. Detailed Implementation

[0031] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0032] Example 1

[0033] This embodiment provides an online monitoring device and detection method for particle concentration in a liquid-solid two-phase flow based on a turbidimeter. A schematic diagram of the device is shown below. Figure 1 As shown, the online particle concentration monitoring device includes a first turbidity sensor 1, a second turbidity sensor 2, a third turbidity sensor 3, a liquid-solid sampling system 4, a transmitter 5, and a computer processing system 6. The first turbidity sensor 1 is located at any position within the liquid-solid two-phase flow system 7. The liquid-solid sampling system 4 includes a sampling pipeline 201, a three-way valve 202, a liquid-solid bed 203, and a vent valve 204. The vent valve 204 is connected to the top of the liquid-solid bed 203 via a pipeline, and the bottom of the liquid-solid bed 203 is connected to the outlet I of the three-way valve 202 via a pipeline. The liquid-solid two-phase flow system 7 is connected to the inlet of the three-way valve 202 via the pipeline 201, and the outlet II of the three-way valve 202 is connected to a waste liquid pipeline. The second turbidity sensor 2 is located at the bottom of the liquid-solid bed 203, and the third turbidity sensor 3 is located at... In the upper middle part of the liquid-solid bed 203, the first turbidity sensor 1, the second turbidity sensor 2, and the third turbidity sensor 3 are all connected to the transmitter 5. The transmitter 5 is connected to the computer processing system 6 through a data transmission line. The transmitter 5 converts the reflected light signal into an electrical signal or turbidity value and transmits the data to the computer processing system 6. By combining the particle concentration and turbidity value of the second turbidity sensor 2 and the third turbidity sensor 3 in the liquid-solid bed 203 under full bed and empty bed conditions, the particle concentration at a local location in the liquid-solid two-phase flow system 7 can be obtained. This online particle concentration monitoring device can realize the online measurement and monitoring of the particle concentration at a local location in a liquid-solid two-phase flow system with changing physical properties. Moreover, this device and method can also be directly used for the online measurement of the local particle concentration in a gas-solid system.

[0034] For systems where the properties of the liquid and solid phases remain unchanged, the particle concentration at a local location in the system can be obtained using only the primary turbidity sensor and the original calibration curve. For systems requiring long-term measurements or where the properties of the liquid and solid phases change, the original calibration curve of the primary turbidity sensor needs to be calibrated. This mainly involves the following steps:

[0035] (1) Open the vent valve 204 at the top of the liquid-solid bed and rotate the three-way valve 202 at the bottom of the liquid-solid bed to connect the bottom of the liquid-solid sampling system 4 to the liquid-solid two-phase flow system 7, so that the two-phase mixture in the liquid-solid two-phase flow flows into the liquid-solid bed 203. When the liquid-solid two-phase mixture in the liquid-solid bed 203 reaches more than 2 / 3, rotate the three-way valve 202 to disconnect the liquid-solid bed 203 from the liquid-solid two-phase flow system 7.

[0036] (2) After the particles in the liquid-solid bed 203 have settled freely to the bottom of the bed, the turbidity value and particle concentration of the liquid-solid bed 203 under the conditions of a full bed and an empty bed are obtained by the second turbidity sensor and the third turbidity sensor, respectively, and are denoted as (N0, W0) and (N0, W0) respectively. f W f );

[0037] (3) Based on the turbidity value and particle concentration obtained in the full bed and empty bed states obtained in step (2), the calibration curve of the standard liquid phase and particles detected by the first turbidity sensor 1 before use is corrected, so as to calculate the particle concentration in the liquid-solid two-phase flow system 7 by the turbidity value obtained by the first turbidity sensor 1, and realize the real-time online measurement of the particle concentration in the liquid-solid two-phase system 7.

[0038] (4) After the measurement is completed, the material in the liquid-solid bed 203 is discharged through the three-way valve 202 at the bottom of the liquid-solid bed 203, or a certain amount of liquid or gas is introduced through the vent valve 204 to transport the liquid-solid two phases in the liquid-solid bed 203 back to the liquid-solid two-phase system 7.

[0039] The specific implementation process is as follows:

[0040] To ensure the accuracy of the test results, the present invention utilizes a liquid-solid stirring system to obtain a uniform liquid-solid two-phase flow system 7, such as... Figure 2 As shown. 10g of 260μm quartz sand particles and 390g of deionized water were added to a beaker. Stirring device 8 was turned on to mix the liquid and solid phases evenly. Based on the turbidity value detected by the first turbidity sensor (24900 FTU), the calculated result was 2.49% (the value detected by the first turbidity sensor was substituted into the standard curve). The particle mass concentration calculated based on the amount of added particles and liquid was 2.50%, with a relative error of -0.4%. After opening the vent valve 204, rotate the three-way valve 202 to allow the liquid-solid mixture to flow into the liquid-solid bed 203 through the sampling line 201. When the liquid and solid phases in the liquid-solid bed reach 2 / 3 of their length, quickly close the vent valve 204 and rotate the three-way valve 202 to disconnect the liquid-solid bed from the mixture to be tested. After the particles in the liquid-solid bed 203 have completely settled, the second turbidity sensor 2 and the third turbidity sensor 3 can obtain stable turbidity values ​​of 0 FTU and 450,000 FTU, respectively. Based on the above two turbidity values ​​and the particle concentration of quartz sand particles in the stacked state, the coefficient of the calibration curve of the first turbidity sensor 1 is corrected. The particle concentration value recalculated based on the corrected standard curve is 2.52%, with a relative error of 0.8%. The results show that the position of the system before and after correction is within ±1%, meeting the requirements for laboratory measurement and industrial applications.

[0041] Examples 2-5

[0042] The amount of quartz sand particles and deionized water added was adjusted according to the scheme of Example 1, and other conditions and operations were not adjusted. The measurement results are shown in Table 1 below.

[0043] Table 1. Effect of particle concentration on measurement results

[0044]

[0045] Examples 6-13

[0046] Following the scheme of Example 1, the quartz sand particles were replaced with larger glass beads (500 μm) and smaller microspherical titanium-silicon molecular sieve catalyst particles (median particle size of 80 μm). Liquid-solid mixed phases of different concentrations were prepared using the above two types of particles. Other conditions and operations were not adjusted. The measurement results are shown in Table 2 below.

[0047] Table 2. Influence of particle size on measurement results

[0048]

[0049] Examples 14-19

[0050] Following the scheme of Example 1, the deionized water in the liquid phase was replaced with CuCl2 and FeCl2 solutions of different mass concentrations, so that the liquid phase showed different degrees of blue and red. Other conditions were not adjusted. The measurement results are shown in Table 3 below.

[0051] Table 3. Effect of liquid phase solution on measurement results

[0052]

[0053] Examples 20-24

[0054] Following the scheme of Example 1, the quartz sand particles were replaced with titanium-silicon molecular sieve catalysts with different carbon deposition amounts, causing the white molecular sieve catalysts to turn into different degrees of gray or even black. Other conditions were not adjusted, and the measurement results are shown in Table 4 below.

[0055] Table 4. Influence of particle color on measurement results

[0056]

[0057] According to Examples 1-24 above, different types of particles and liquids are used. If only the first turbidity sensor is used without calibration curve correction, the measurement error is large for systems where the color of the liquid or particles changes, and the relative error can reach nearly 20%. However, the device and method proposed in this invention can achieve real-time calibration of the calibration curve, and accurate measurement can be achieved for different systems. The relative error can be controlled within ±2%, which meets the needs of experimental research and industrial applications.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The application of an online particle concentration monitoring device in detecting particle concentration in a liquid-solid two-phase flow system or a gas-solid two-phase flow system; The online particle concentration monitoring device includes a first turbidity sensor, a second turbidity sensor, a third turbidity sensor, a liquid-solid sampling system, a transmitter, and a computer processing system. The first turbidity sensor is located at any position within the liquid-solid two-phase flow system. The liquid-solid sampling system includes a sampling pipeline, a three-way valve, a liquid-solid bed, and a vent valve. The vent valve is connected to the top of the liquid-solid bed via a pipeline, and the bottom of the liquid-solid bed is connected to the outlet I of the three-way valve via a pipeline. The liquid-solid two-phase flow system is connected to the inlet of the three-way valve via a pipeline, and the outlet II of the three-way valve is connected to a waste liquid pipeline. The second turbidity sensor is located at the bottom of the liquid-solid bed, and the third turbidity sensor is located in the upper middle part of the liquid-solid bed. The first, second, and third turbidity sensors are all connected to the transmitter, and the transmitter is connected to the computer processing system via a data transmission line. The third turbidity sensor is located at 1 / 2 to 4 / 5 of the height of the liquid-solid bed; The transmitter converts the optical signals detected by the first, second, and third turbidity sensors into electrical signals or turbidity values, which are then transmitted to the computer processing system.

2. The application according to claim 1, characterized in that, The liquid phase in a liquid-solid two-phase flow system includes, but is not limited to, water, methanol, ethanol, tert-butanol, acetone, and soluble salt solutions.

3. The application according to claim 1, characterized in that, The particle size of the solid phase particles ranges from 0.1 to 5000 μm.

4. The application according to claim 1, characterized in that, The mass percentage concentration of solid particles is 0.001% to 60%.

5. A method for detecting particle concentration in a liquid-solid two-phase flow system using an online particle concentration monitoring device, characterized in that, The main steps include: For systems where the optical properties of the liquid phase and / or solid phase do not change, a series of standard curves of solid particle concentration versus voltage or turbidity value are first generated using a first turbidity sensor. Then, the voltage or turbidity value in the liquid-solid two-phase flow system is detected using the first turbidity sensor, substituted into the standard curves, and the particle concentration in the liquid-solid two-phase flow system is calculated. For systems where the optical properties of the liquid and / or solid phases change, the turbidity and particle concentration of the solid phase in the liquid-solid two-phase flow system are detected by a liquid-solid sampling system, a second turbidity sensor, and a third turbidity sensor under full-bed and empty-bed conditions. Then, a series of standard curves of solid particle concentration versus voltage or turbidity values ​​generated by the first turbidity sensor are corrected. Finally, the voltage or turbidity value in the liquid-solid two-phase flow system is detected by the first turbidity sensor, and the corrected standard curves are substituted to calculate the particle concentration in the liquid-solid two-phase flow system. The online particle concentration monitoring device includes a first turbidity sensor, a second turbidity sensor, a third turbidity sensor, a liquid-solid sampling system, a transmitter, and a computer processing system. The first turbidity sensor is located at any position within the liquid-solid two-phase flow system. The liquid-solid sampling system includes a sampling pipeline, a three-way valve, a liquid-solid bed, and a vent valve. The vent valve is connected to the top of the liquid-solid bed via a pipeline, and the bottom of the liquid-solid bed is connected to the outlet I of the three-way valve via a pipeline. The liquid-solid two-phase flow system is connected to the inlet of the three-way valve via a pipeline, and the outlet II of the three-way valve is connected to a waste liquid pipeline. The second turbidity sensor is located at the bottom of the liquid-solid bed, and the third turbidity sensor is located in the upper middle part of the liquid-solid bed. The first, second, and third turbidity sensors are all connected to the transmitter, and the transmitter is connected to the computer processing system via a data transmission line. The third turbidity sensor is located at 1 / 2 to 4 / 5 of the height of the liquid-solid bed; The transmitter converts the optical signals detected by the first, second, and third turbidity sensors into electrical signals or turbidity values, which are then transmitted to the computer processing system.

6. The method according to claim 5, characterized in that, For systems in which the optical properties of the liquid phase and / or solid phase change, the method includes the following steps: (1) Open the vent valve at the top of the liquid-solid bed and rotate the three-way valve at the bottom of the liquid-solid bed to connect the bottom of the liquid-solid bed with the liquid-solid two-phase flow system, so that the two-phase mixture in the liquid-solid two-phase flow flows into the liquid-solid bed. When the liquid and solid phases in the liquid-solid bed reach more than 2 / 3 of the height of the liquid-solid bed, rotate the three-way valve to disconnect the liquid-solid bed from the liquid-solid two-phase flow system. (2) After the particles in the liquid-solid bed have settled freely to the bottom of the bed, the turbidity value and particle concentration of the liquid-solid bed in the full bed state and the empty bed state are detected by the second turbidity sensor and the third turbidity sensor, respectively, and recorded as (N0, W0) and (N f W f ); (3) Based on the turbidity and particle concentration obtained in step (2) under full bed and empty bed conditions, a series of standard curves of solid particle concentration and voltage or turbidity values ​​prepared by the first turbidity sensor are corrected. Then, the voltage or turbidity value in the liquid-solid two-phase flow system is detected by the first turbidity sensor, and the corrected standard curve is substituted to calculate the particle concentration in the liquid-solid two-phase flow system.

7. The method according to claim 6, characterized in that, After the measurement is completed, the material in the liquid-solid bed is discharged through the three-way valve at the bottom of the liquid-solid bed, or a certain amount of liquid or gas is introduced through the vent valve to transport the liquid-solid two-phase flow back into the liquid-solid two-phase flow system.

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