Sediment monitoring instrument and metrological calibration method thereof

Abstract

The application discloses a kind of silt monitoring instrument and its metrological calibration method, it is related to water and soil loss observation technical field, solve the current silt monitoring instrument's dynamic silt monitoring capability Current still there is no mature metrological calibration method problem, including rack shell, rack shell's middle position is equipped with rack bin, the side of the top of rack bin is equipped with silt sample inlet, the other side of the bottom of rack bin is equipped with silt sample outlet, silt sample outlet and silt sample inlet are connected with drive pump by pipeline, the both sides of rack bin are all connected with stirring shaft through activity, the position of stirring shaft in the inside of rack bin is all installed with double helix stirring blade, the part of stirring shaft outside the outside of rack bin is rotatably connected with bearing seat on the upper surface of rack shell.The silt sample of the application is always in motion state, can simulate complex scene in field natural riverway to a certain extent, and then improve the performance detection capability of silt monitoring equipment.

Description

Technical Field

[0001] This invention relates to the field of soil and water conservation monitoring technology, specifically to a sediment monitoring instrument and its calibration method. Background Technology

[0002] One of the key tasks of soil and water conservation is soil erosion monitoring, and sediment monitoring is a crucial component of this monitoring. Currently, sediment monitoring is primarily achieved through standard runoff plots and small watershed control stations, with the oven-drying method being the main measurement method. This method provides relatively accurate sediment content measurements and has low sampling and measurement costs, but it only obtains the average sediment content of a single rainfall event and cannot reflect the soil erosion process. Therefore, soil and water conservation professionals have designed and developed numerous new technologies and methods for sediment monitoring. Current mainstream methods include infrared, ultrasonic, and gamma-ray methods. Related sediment monitoring instruments include the TES-91 online sediment monitoring system, the XA2020A automatic suspended sediment measurement system, the DF-NL01 runoff sediment monitor, the SOLITAXsc suspended solids turbidimeter, and the SBJC-IV portable sediment measuring instrument.

[0003] Because the monitoring principles of different methods are quite different, it is difficult to directly calibrate or compare various sediment monitoring devices. Currently, mainstream sediment monitoring instruments all require metrological calibration based on the results of the drying method. Since the drying method cannot reflect the change process of sediment content, there is still no mature metrological calibration method for the dynamic sediment monitoring capability of current sediment monitoring instruments. Therefore, it does not meet the current needs. In response, we propose a sediment monitoring instrument and its metrological calibration method. Summary of the Invention

[0004] The purpose of this invention is to provide a sediment monitoring instrument and its calibration method, in order to solve the problem mentioned in the background art that there is currently no mature calibration method for the dynamic sediment monitoring capability of sediment monitoring instruments.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a sediment monitoring instrument and its calibration method, comprising a frame housing, a frame compartment located in the middle of the frame housing, a sediment inlet located on one side of the top of the frame compartment, a sediment outlet located on the other side of the bottom of the frame compartment, a drive pump connected between the sediment outlet and the sediment inlet via a pipe, a stirring shaft movably connected through both sides of the frame compartment, a double-helix stirring blade installed on the stirring shaft inside the frame compartment, a portion of the stirring shaft outside the frame compartment being rotatably connected to a bearing seat on the upper surface of the frame housing, and a driven sprocket fixedly mounted on the outer surface of the stirring shaft outside the frame compartment;

[0006] An electric motor is installed on one side of the stirring shaft. The output shaft of the electric motor is connected to a reducer through a coupling. The output shaft of the reducer is equipped with a drive sprocket. The drive sprocket and the driven sprocket are connected by a transmission chain.

[0007] Preferably, the connection between the frame compartment and the stirring shaft is provided with an oil seal. The double helical stirring blade includes an outer helical blade, an inner helical blade and a connecting rod. The outer helical blade and the inner helical blade are coaxial, and the inner helical blade is close to the shaft center. Both the outer helical blade and the inner helical blade are connected to the stirring shaft through the connecting rod.

[0008] Preferably, a water inlet is provided on one side of the sediment discharge port, and the water inlet is equipped with a flow meter.

[0009] A metrological calibration method for a sediment monitoring instrument includes the following steps:

[0010] Step 1: Based on the dimensions of the sediment monitor, the water volume inside the sediment monitor at the predetermined water level can be determined, and the sediment concentration can be obtained. The functional relationship between the sediment volume required to configure the sediment concentration is determined. The energy of stirring the sediment is measured as the momentum of the water flow driven by the superimposed blades, which is simplified to the superposition of the flow velocity generated by the blades driving the water body. The frame chamber is divided into a measuring chamber and two mixing chambers. The measuring chamber is located in the middle of the two mixing chambers. The measuring chamber and the mixing chamber are separated by a metal grid with a 10cm interval. A three-dimensional moving guide rail is set on the measuring chamber.

[0011] Step 2: According to the measurement range of the instrument to be tested, prepare dry soil required for different calibration sediment concentrations, and thoroughly clean the frame chamber with clean water to avoid sediment residue in the chamber;

[0012] Step 3: Open the valve corresponding to the water inlet at the bottom of the sediment monitor, add water to the sediment monitor until the liquid level stabilizes at the initial position marked in the frame compartment, and then close the water inlet valve;

[0013] Step 4: Start the motor and add the weighed and measured amount of dry soil into the mixing chamber to prepare a water-sand mixture with a given sediment concentration. The sediment particles remain suspended under the action of hydraulic force.

[0014] Step 5: Fix the instrument to be tested at different preset sampling points in the sediment detection chamber area, take readings and record them;

[0015] Step 6: Evaluate the spatial stability of the instrument by comparing sediment data at different sampling points under the same sediment concentration;

[0016] Step 7: Evaluate the temporal stability by comparing the time series characteristics of data acquired by the instrument at the same sampling point under the same sediment concentration;

[0017] Step 8: Based on the given sediment concentration and the actual data read by the instrument under test, calibrate the instrument under test;

[0018] Step 9: After the testing and calibration of the instrument is completed, empty the rack compartment and rinse it with clean water.

[0019] Preferably, the three-dimensional guide rail is equipped with a bearing sliding block module for supporting and guiding the component to move linearly in a given direction. There is a deep contact area between the guide rail and the slider to improve the system's load-bearing capacity. Simultaneously, the slider has a locking mechanism to place the instrument under test in a fixed position and verify the time stability of the instrument's performance.

[0020] Preferably, the initial position is 32cm from the top of the rack compartment.

[0021] Preferably, the functional relationship between the required sediment concentration and the amount of sediment is as follows:

[0022]

[0023] in The concentration of sediment; The required mass of dry soil to achieve this sediment concentration; This refers to the amount of water in the device at the predetermined water level. It is the bulk density of dry soil.

[0024] Preferably, the formula for the superposition of the flow velocities generated by the blades driving the water body is:

[0025]

[0026] in The flow rate provided for external circulation is equal to the ratio of flow rate to water surface area. Where Q is the flow rate and A is the cross-sectional area;

[0027] The velocity of the water body propelled by the outer leaf surface, The velocity of the water flow driven by the inner blade surface is given by the following formula:

[0028]

[0029]

[0030] in and These are the tangential and radial velocities of water flow along the outer and inner blade surfaces, respectively, and the relationship between the two is obtained through the blade angle. , The horizontal angle of the leaf surface is equal to:

[0031]

[0032]

[0033]

[0034]

[0035] in The impeller's wheelbase. and The diameters of the outer and inner impellers are respectively, and n is the number of blade revolutions. Let be the angular velocity of the impeller. The efficiency coefficient based on the conversion of equal leaf surface area is obtained from the following formula:

[0036]

[0037]

[0038] in and The radii of the outer and inner impellers, The width of the impeller blades. and These are the water passage areas of the outer and inner impellers, respectively. and This refers to the area of ​​the outer and inner impellers.

[0039] Preferably, the sediment particles remain suspended under hydraulic action. The critical velocity in this case is obtained using the Sha Yuqing formula, which is:

[0040]

[0041] in The particle size of the sediment The hydraulic radius of the device is the ratio of the water-passing area to the wetted perimeter λ. , For sediment settling velocity:

[0042]

[0043] in Here, d is the sediment settling correction factor for the sphere, and d is the particle size of the sediment. and The bulk density of water and sediment are respectively. It is the acceleration due to gravity. The kinetic viscosity coefficient of the water body.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] The detection device of this invention can be configured with a fully stirred, uniform sediment sample, and the sediment sample in the device is always in motion, which can simulate the complex situation in a natural river channel in the wild to a certain extent, thereby improving the performance detection capability of sediment monitoring equipment. The calibration method of the device can correct the device under test in real time under different sediment concentrations, so as to improve the detection accuracy of the device. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0047] Figure 2 This is a top view of the entire invention;

[0048] Figure 3 This is a partial internal structural diagram of the rack compartment of the present invention;

[0049] Figure 4 This is a partial structural schematic diagram of the double-helix stirring blade of the present invention;

[0050] Figure 5 This is a three-dimensional schematic diagram of the sampling point layout of the present invention;

[0051] Figure 6 This is a schematic diagram of the sampling point layout of the present invention;

[0052] Figure 7 This is a schematic diagram of the structure for determining the sampling depth in this invention;

[0053] Figure 8 Box plot showing the deviation of the detection of different sediment concentrations, sampling depths, and sampling groups in this invention;

[0054] Figure 9 A comparison graph of sediment concentration measured by a turbidimeter and the calibrated sediment concentration;

[0055] Figure 10 The graph shows the variation of sediment uniformity and impeller speed in the device under different sediment concentrations. Detailed Implementation

[0056] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0057] Please see Figures 1 to 10An embodiment of the present invention provides a sediment monitoring instrument, comprising a frame housing 2, a frame compartment 1 located in the middle of the frame housing 2, a sediment inlet 13 located on one side of the top of the frame compartment 1, and a sediment outlet 12 located on the other side of the bottom of the frame compartment 1. A drive pump 4 is connected between the sediment outlet 12 and the sediment inlet 13 via a pipe 3. An electromagnetic flow meter is installed in the pipe 3. The drive pump 4 is an electric centrifugal pump. A stirring shaft 7 is movably connected through both sides of the frame compartment 1. Double spiral stirring blades 11 are installed on the stirring shaft 7 inside the frame compartment 1. The part of the stirring shaft 7 outside the frame compartment 1 is rotatably connected to a bearing seat 10 on the upper surface of the frame housing 2. A driven sprocket 8 is fixedly installed on the outer surface of the stirring shaft 7 outside the frame compartment 1.

[0058] A motor 5 is installed on one side of the stirring shaft 7. The motor 5 is a three-phase asynchronous motor. The output shaft of the motor 5 is connected to a reducer 6 through a coupling. The output shaft of the reducer 6 is equipped with a drive sprocket 9. The drive sprocket 9 and the driven sprocket 8 are connected through a transmission chain.

[0059] An oil seal is provided at the connection between the frame compartment 1 and the stirring shaft 7. The double helical stirring blade 11 includes an outer helical blade 1101, an inner helical blade 1102 and a connecting rod 1103. The outer helical blade 1101 and the inner helical blade 1102 are coaxial, and the inner helical blade 1102 is close to the shaft center. Both the outer helical blade 1101 and the inner helical blade 1102 are connected to the stirring shaft 7 through the connecting rod 1103.

[0060] A water inlet is provided on one side of the sediment discharge port 12, and a flow meter is provided at the water inlet.

[0061] A metrological calibration method for a sediment monitoring instrument includes the following steps:

[0062] Step 1: Based on the dimensions of the sediment monitor, the water volume inside the monitor at the predetermined water level can be determined, and the sediment concentration can be obtained. The functional relationship between the required sediment volume and the desired sediment concentration can be established. The energy of agitating the sediment is measured as the momentum of the water flow driven by the blades, simplified to the superposition of the flow velocities generated by the blades driving the water body. The frame is divided into a measuring chamber and two mixing chambers, with the measuring chamber located in the middle of the two mixing chambers. The measuring chamber and the mixing chambers are separated by a 10cm interval metal grid. A three-dimensional moving guide rail is installed on the measuring chamber, and an instrument mounting frame is mounted on the three-dimensional guide rail. The three-dimensional guide rail is equipped with a bearing sliding block module to support and guide the components to move linearly in a given direction. There is a deep contact area between the guide rail and the slider to improve the system's load-bearing capacity. The slider also has a locking mechanism to place the instrument under test in a fixed position and verify the time stability of the instrument's performance.

[0063] Step 2: According to the measurement range of the instrument to be tested, prepare dry soil required for different calibration sediment concentrations, and thoroughly clean the frame chamber with clean water to avoid sediment residue in the chamber;

[0064] Step 3: Open the valve corresponding to the water inlet at the bottom of the sediment monitor, add water to the sediment monitor until the liquid level stabilizes at the initial position marked in the frame compartment. The initial position is when the liquid level is 32cm from the top of the frame compartment and the water volume in the frame compartment is 6m³. Then close the water inlet valve.

[0065] Step 4: Start the motor and add the weighed and measured amount of dry soil into the mixing chamber to prepare a water-sand mixture with a given sediment concentration. The sediment particles remain suspended under the action of hydraulic force.

[0066] Step 5: Fix the instrument to be tested at different preset sampling points in the sediment detection chamber area, take readings and record them;

[0067] Step 6: Evaluate the spatial stability of the instrument by comparing sediment data at different sampling points under the same sediment concentration;

[0068] Step 7: Evaluate the temporal stability by comparing the time series characteristics of data acquired by the instrument at the same sampling point under the same sediment concentration;

[0069] Step 8: Based on the given sediment concentration and the actual data read by the instrument under test, calibrate the instrument under test;

[0070] Step 9: After the testing and calibration of the instrument is completed, empty the rack compartment and rinse it with clean water.

[0071] The functional relationship between the required amount of sediment and the desired sediment concentration is as follows:

[0072]

[0073] in Sediment concentration, in kg / m³ 3 ; The required dry soil mass for this sediment concentration is expressed in kg. The volume of water in the device at the predetermined water level, in meters (m). 3 ; The bulk density of dry soil is taken as 2.65 kg / m³. 3 .

[0074] The formula for the superposition of the flow velocities generated by the blades driving the water is:

[0075]

[0076] in The flow rate provided for external circulation is equal to the ratio of flow rate to water surface area. Where Q is the flow rate, which is 50 L / s, and A is the cross-sectional area, which is 2 m². 2 ,Right now ;

[0077] The velocity of the water body propelled by the outer leaf surface, The velocity of the water flow driven by the inner blade surface is given by the following formula:

[0078]

[0079]

[0080] in and These are the tangential and radial velocities (m / s) of the water flow along the outer and inner blade surfaces, respectively, and the relationship between the two is obtained through the blade angle. , The horizontal angle of the leaf surface is equal to:

[0081]

[0082]

[0083]

[0084]

[0085] in The impeller's wheelbase is 850mm. =1470mm and 490mm represents the diameter of the outer and inner impellers respectively, and n is the number of blade turns, which equals 2. The impeller's angular velocity is expressed in rpm / min. The efficiency coefficient based on the conversion of equal leaf surface area is obtained from the following formula:

[0086]

[0087]

[0088] in 735mm and 490mm is the radius of the outer and inner impellers. The impeller blade width is 50mm. and These are the water passage areas of the outer and inner impellers, respectively. and This refers to the area of ​​the outer and inner impellers.

[0089] When sediment particles remain suspended under hydraulic pressure, the critical velocity is obtained using the Sha Yuqing formula:

[0090]

[0091] in The median particle size of the loess soil used in the experiment is the particle size of the sediment. , The hydraulic radius of the device is equal to the ratio of the water-passing area to the wetted perimeter λ. , For sediment settling velocity:

[0092]

[0093] in The correction factor for sphere settlement is 0.75. and , respectively, are the bulk densities of water and sediment, taken as 1 t / m³ and 2.65 t / m³, respectively, where d is the particle size of the sediment. For gravitational acceleration, take 9.8m. 2 / s, Let be the kinematic viscosity coefficient of the water body, taken as 1.01 × 10⁻⁶ m when the temperature is equal to 20°C. 3 / s.

[0094] Based on the above formula, the velocity of the mud and sand can be calculated as follows: Equipment Requirements ,at this time

[0095] .

[0096] The agitator impeller is driven by two variable-speed motors located on both sides, via chains and bearings. These motors are connected to a PCL controller and controlled by a circuit. To meet the impeller speed requirements, a 5kW rated motor was selected, allowing the impeller speed to vary from 0 to 100 revolutions per minute.

[0097] The measuring chamber is located in the middle of the two mixing chambers. The measuring chamber and the mixing chamber are separated by a metal grid with a 10cm interval. While ensuring the safety of the instruments and equipment under test in the measuring chamber, the metal grid also plays a certain role in ballasting and improving the flow stability in the measuring chamber.

[0098] The measuring chamber of the device is equipped with a three-dimensional moving guide rail, which can fix the instrument under test at different positions and depths to verify the spatial stability of the instrument's performance.

[0099] As shown in Table 1 below, after cleaning the instrument, water is added through the water inlet until the liquid level stabilizes at 32cm from the top of the detection chamber. At this point, the volume of water inside the device is 6m³. 3 The experiment included nine gradients, with sediment concentrations ranging from 1 to 100 kg / m³. 3 .

[0100] Table 1 Sediment Concentration Configuration

[0101]

[0102] Sampling point deployment within rack bay 1, as follows Figure 5 and Figure 6 As shown, the deepest point of the monitoring sampling points in groups A and C is 1.6m from the top of the instrument, while that in group B is 1.8m. The sampling depth is as follows. Figure 7 As shown, the initial measurement position of h is at 1 / 2 the height of the turbidimeter probe. The sampling depths of groups A and C are 30cm, 60cm, and 90cm below the liquid surface, respectively. Group B adds a sampling depth of 120cm below the liquid surface. Considering that the movement of the turbidimeter probe in the measurement chamber will disturb the sediment concentration in the surrounding area and thus affect the experimental results, when using the turbidimeter to detect sediment concentration at each sampling point, a 5-second interval is maintained, and three readings are continuously taken and recorded as one group. When the absolute deviation between the data of a group is less than 5% of the current concentration, the current sediment concentration is considered to be stable. The mean of the data of the group is calculated and recorded.

[0103] To establish a calibration method for the relationship between sediment concentration and impeller speed, the relationship between the two under different sediment concentrations was analyzed. Five sediment concentration gradients (1, 10, 20, 50, and 100 kg / m³) were set, and the impeller angular velocity was controlled within the range of 10–30 rpm / min using a variable-speed motor. Based on the acquired data, the following indicators were calculated to evaluate the uniformity of sediment mixing by the instrument:

[0104]

[0105]

[0106] in and The values ​​represent the standard deviation and mean of sediment measurements for different treatment groups. This reflects the uniformity of the data; and These represent the sediment concentration at the sampling points and the sediment concentration set in the experiment. This represents the degree of deviation in the sampled data.

[0107] The paired-samples Wilcoxon test was used to process the data from each sampling point in pairs to analyze whether there were significant differences in the sediment concentration data obtained from each sampling point. The Wilcoxon test is a non-parametric test and does not require the sample data to meet a normal distribution.

[0108] like Figure 8 As shown, the deviation and uniformity of sediment detection under different sediment concentrations, sampling depths, and sampling groups are displayed. In the box plot, the horizontal line is the median, the upper and lower borders are the 1 / 4 and 3 / 4 quantiles respectively, and the dots are outliers. The data on the box plot are the mean and standard deviation of the deviation under that group; the data below the box plot is the corresponding uniformity.

[0109] Based on Table 2 below, the results show that the deviation of the sediment detection remains stable with the increase of sediment concentration, decreasing from 1 kg / m³. 3 The value of 0 ± 4.41% at that time became 100 kg / m 3 The sediment concentration at the sampling depth was 0±1.13%; while the sediment uniformity showed an increasing trend, increasing from 95.58% to 98.88%. The deviation of sediment concentration at different sampling depths was relatively close, all less than 1%. The largest deviation was -0.29±2.83% at a sampling depth of 60cm, and the smallest deviation was 0.04±2.02% at a sampling depth of 120cm. The sediment uniformity was also the largest at this depth, at 98.88%, and the smallest at 97.12% at 30cm. Among the different sampling groups, group C had the smallest deviation of sediment concentration, at 0.14±3.22%, while group A had the largest, at -0.56±2.54%. The sediment uniformity of each group was relatively close, all between 97% and 98%. The differences between the sampling points were generally small, with the largest deviation at point A1 (-0.95±3.83%) and the smallest deviation at point C3 (0.01±2.21%). The uniformity of each sampling point was greater than 97%, with the highest uniformity at point A3 (98.94%) and the lowest at point C1 (97.01%).

[0110] Table 2. Deviation and uniformity of sampled data

[0111]

[0112] Paired-samples Wilcoxon test was performed on the sediment concentration data from different sampling points. The test results showed that the P-value was greater than or equal to 0.05, meaning that there was no significant difference in sediment concentration among the sampling points at the significance level of alpha=0.05.

[0113] Based on the above process, turbidimeter measurement results for sediment concentrations ranging from 0 to 100 kg / m³ can be obtained. The experiment set up nine sediment concentration gradients: 1, 3, 5, 10, 20, 30, 50, 75, and 100 kg / m³. For each gradient, a total of 90 sets of sediment concentration values ​​measured by the turbidimeter were obtained at different locations. Comparison of the two measurements revealed that within the sediment concentration range of less than 20 kg / m³, the turbidimeter measurement results were consistent with the calibration results. However, as the sediment concentration gradually increased, the turbidimeter measurement results were lower than the actual values, and the difference became more pronounced with higher concentrations. When the calibrated sediment concentration was 75 kg / m³, the average value of 30 repeated turbidimeter measurements was 69.10 ± 3.92 kg / m³. When the calibrated concentration was 100 kg / m³, the average value was 91.43 ± 4.82 kg / m³. Figure 9 As shown, the sediment concentration measured by the turbidimeter can be calibrated using a linear equation.

[0114] like Figure 10 As shown in the experiment, the uniformity of sediment under different sediment concentrations varies with the impeller speed. The results indicate that, with increasing impeller angular velocity, the uniformity of sediment within the device increases at different sediment concentrations, and the higher the sediment concentration, the more significant the change in uniformity. At a sediment concentration of 100 kg / m³, the uniformity of sediment within the device increases from 23.45% to 98.76% as the impeller speed increases from 10 rpm / min to 30 rpm / min. However, at a sediment concentration of 1 kg / m³, the uniformity only increases from 93.72% at 10 rpm / min to 99.63%, showing a relatively small change.

[0115] Based on the experimental results, a calibration method for the sediment detection instrument applicable to this device was proposed, namely, the optimal stirring impeller speed for different sediment concentrations to achieve 95% sediment uniformity, as shown in Table 3 below.

[0116] Table 3. Calibration and setting methods for impeller speed measurement at different sediment concentrations.

[0117]

[0118] Experimental results show that at 95% uniformity, there is a significant positive correlation between sediment concentration and impeller speed. This relationship can be fitted using a logarithmic function, and the R² of the fitted model is [value missing]. 2 Reaching 98%

[0119] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method of metrological calibration of a sediment monitoring instrument, characterized in that, The sediment monitoring instrument, including a rack shell, a rack bin is arranged in the middle of the rack shell, stirring shafts are movably connected to both sides of the rack bin, double helix stirring blades are installed at positions of the stirring shafts inside the rack bin, the double helix stirring blades include outer helix blades, inner helix blades and connecting rods, and the outer helix blades and the inner helix blades are coaxial; The method comprises the following steps: Step one: according to the size of the sediment monitoring instrument, the water quantity in the sediment monitoring instrument at the predetermined water level is known, the sediment concentration is obtained, the functional relationship between the sediment quantity required for configuring the sediment concentration is determined, the energy for stirring the sediment is measured as the momentum of the water flow driven by the stacked blades, the flow velocity generated by the blades driving the water body is simplified as the superposition, the rack bin is divided into a measuring bin and two stirring bins, the measuring bin is located in the middle of the two stirring bins, the measuring bin and the stirring bins are separated by a metal grid with a spacing of 10 cm, and a three-dimensional moving guide rail is arranged on the measuring bin; Step two: according to the range of the instrument to be detected, dry soil required for different calibration sediment concentrations is prepared, and the rack bin is washed with clean water to avoid residual sediment in the bin; Step three: the valve corresponding to the water inlet at the bottom of the sediment monitoring instrument is opened, water is added to the sediment monitoring instrument until the liquid surface is stable at the initial position marked in the rack bin, and then the water inlet valve is closed; Step four: the dry soil with a certain weight is added from the stirring bin to configure a water-sediment mixture with a given sediment concentration under the action of water force, and the sediment particles are kept in a suspended state of motion; Step five: the instrument to be detected is fixed at different sampling points in the sediment detection bin area, readings are taken and recorded; Step six: the spatial stability of the instrument to be detected is evaluated by comparing the sediment data of the instrument to be detected at different sampling points under the same sediment concentration; Step seven: the time sequence characteristics of the data obtained by the instrument to be detected at the same sampling point under the same sediment concentration are compared to evaluate the time stability of the instrument to be detected; Step eight: based on the given sediment concentration, the instrument to be detected is calibrated combined with the actual data read by the instrument to be detected; Step nine: after the detection and calibration of the instrument to be detected are completed, the rack bin is emptied and washed with clean water; The formula for the flow velocity superposition generated by the blades driving the water body is: V = V1 + V2 + V3 where V3 is the flow rate provided by the external circulation, equal to the flow rate divided by the wetted area, where Q is the flow rate and A is the wetted area. V1 is the flow velocity of the outer blade surface driving the water body, and V2 is the flow velocity of the inner blade surface driving the water body, and the formula is as follows: ； where V t and V r are the tangential and radial velocity of the water flow along the outer and inner blade surface, respectively, and their relationship is obtained through the blade angle, V r = V t tan β, β being the horizontal angle of the blade; The sediment particles are kept in a suspended state of motion under the action of water force, and the critical flow velocity is obtained through the formula of Sha Yujing: V s = 0.815d 2 / 5 w 1 / 5 R 1 / 5 where d is the sediment particle size, R is the hydraulic radius of the device, the ratio of the cross-sectional area to the wetted perimeter λ, and w is the sediment settling velocity; V ≥ V s .

2. The method of metrological calibration of a sediment monitoring instrument according to claim 1, characterized in that: One side of the top end of the rack bin is provided with a sediment sample inlet, the other side of the bottom end of the rack bin is provided with a sediment sample outlet, the sediment sample outlet and the sediment sample inlet are connected through a pipeline, and a drive pump is arranged between the sediment sample outlet and the sediment sample inlet, the part of the stirring shaft outside the rack bin is rotatably connected with the bearing seat on the upper surface of the rack shell, and a driven sprocket is fixedly arranged on the outer surface of the stirring shaft outside the rack bin; One side of the stirring shaft is provided with an electric motor, the output shaft of the electric motor is connected with a speed reducer through a shaft coupling, the output shaft of the speed reducer is provided with a driving sprocket, and the driving sprocket and the driven sprocket are connected through a transmission chain. The connection between the rack bin and the stirring shaft is provided with an oil seal; the inner spiral blade is close to the shaft center, and the outer spiral blade and the inner spiral blade are connected with the stirring shaft through connecting rods; one side of the silt sampling port is provided with a water injection port, and the water injection port is provided with a flowmeter.

3. A method of metrological calibration of a sediment monitoring instrument according to claim 2, characterized in that: The three-dimensional moving guide rail is equipped with a bearing sliding block module for supporting and guiding linear movement of components in a given direction; the guide rail and the sliding block have a deep contact area for improving the carrying capacity of the system, and the sliding block has a fixed lock for placing the instrument to be detected at a fixed position to test the time stability of the instrument performance.

4. The method of metrological calibration of a sediment monitoring instrument according to claim 3, characterized in that: The initial position is that the liquid level is 32 cm from the top of the rack bin.

5. A method of metrological calibration of a sediment monitoring instrument according to claim 4, characterized in that: The functional relationship formula between the amount of silt required to configure the silt concentration is: ； where D is the sediment concentration; W soil is the dry soil mass required to configure the sediment concentration; V W is the water volume in the device at the predetermined water level; p soil is the bulk density of the dry soil.

6. A method of metrological calibration of a sediment monitoring instrument according to claim 5, characterized in that: β is the horizontal angle of the blade surface: ； Where L is the shaft distance of the impeller, D1 and D2 are the diameters of the outer and inner impellers respectively, n is the number of blades, ω is the angular velocity of the impeller, and μ is the efficiency coefficient based on the equal-area conversion of the blade surface, which is obtained by the following formula: ； ； where R1 and R2 are the radii of the outer and inner impellers, A1 and A2 are the flow areas of the outer and inner impellers, respectively, and A'1 and A'2 are the areas of the outer and inner impellers, respectively.

7. A method of metrological calibration of a sediment monitoring instrument according to claim 6, characterized in that w is the sedimentation velocity of silt: ； where k is the correction coefficient of sphere sedimentation, d is the particle size of sediment, γ and are the bulk densities of water and sediment, g is the acceleration of gravity, and v is the kinematic viscosity of water.

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