Sediment monitoring instrument and metering calibration method thereof

Abstract

The invention discloses a sediment monitoring instrument and a metering calibration method thereof, relates to the technical field of water and soil loss observation, and solves the problem that a mature metering calibration method for the dynamic sediment monitoring capability of an existing sediment monitoring instrument is still unavailable at present, the sediment monitoring instrument comprises a rack shell, and a rack bin is arranged in the middle of the rack shell; a silt sample inlet is formed in one side of the top end of the rack bin, a silt sample discharge port is formed in the other side of the bottom end of the rack bin, a driving pump is connected between the silt sample discharge port and the silt sample inlet through a pipeline, stirring shafts are movably connected to the two sides of the rack bin in a penetrating mode, and double-helix stirring blades are installed at the positions, located in the rack bin, of the stirring shafts. The part, positioned outside the rack bin, of the stirring shaft is rotationally connected with a bearing seat on the upper surface of the rack shell. The sediment sample is always in a moving state, the complex scene in a field natural river channel can be simulated to a certain degree, and then the performance detection capacity of sediment monitoring equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of soil and water loss observation, in particular to a sediment monitoring instrument and a measurement and calibration method thereof. Background Art

[0002] One of the important tasks of soil and water conservation is soil erosion monitoring, and sediment monitoring is an important part of soil and water erosion monitoring. At present, sediment monitoring is mainly achieved through standard runoff plots and small watershed control stations. The measurement point method is mainly drying method monitoring. The sediment content measured by this method is relatively accurate, and the sampling and measurement costs are low. However, it can only obtain the average sediment content of a single precipitation and cannot reflect the soil erosion process. Based on this, soil and water conservation practitioners have designed and developed a large number of new technologies and methods for sediment monitoring. The current mainstream means include infrared, ultrasonic, gamma ray and other methods. Related sediment monitoring instruments include TES-91 sediment online monitoring system, XA2020A suspended sediment automatic measurement system, DF-NL01 runoff sediment monitor, SOLITAX sc suspended matter monitoring turbidity meter, SBJC-IV portable sediment measuring instrument, etc.

[0003] Since the monitoring principles of different methods are very different, it is difficult to directly calibrate or compare the various sediment monitoring equipment. Currently, mainstream sediment monitoring instruments need to be calibrated based on the results of the drying method. Since the drying method cannot reflect the changing process of sediment content, there is still no mature calibration method for the dynamic sediment monitoring capability of sediment monitoring instruments. Therefore, it does not meet the existing needs. In this regard, we propose a sediment monitoring instrument and its calibration method. Summary of the invention

[0004] The object of the present invention is to provide a sediment monitoring instrument and a metrological calibration method thereof, so as to solve the problem mentioned in the above background technology that the dynamic sediment monitoring capability of the current sediment monitoring instrument still has no mature metrological calibration method.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a sediment monitoring instrument and a metrological calibration method thereof, comprising a frame shell, a frame bin is provided in the middle position of the frame shell, a sediment inlet is provided on one side of the top of the frame bin, a sediment discharge port is provided on the other side of the bottom of the frame bin, a driving pump is connected between the sediment discharge port and the sediment inlet through a pipeline, a stirring shaft is movably connected through both sides of the frame bin, a double-helical stirring blade is installed at a position of the stirring shaft located inside the frame bin, a portion of the stirring shaft located outside the frame bin is rotatably connected to a bearing seat on the upper surface of the frame shell, and a driven sprocket is fixedly provided on the outer surface of the stirring shaft located outside the frame bin;

[0006] A motor is installed on one side of the stirring shaft, the output shaft of the motor is connected to a reducer through a coupling, the output shaft of the reducer is installed with a driving sprocket, and the driving sprocket and the driven sprocket are connected through a transmission chain.

[0007] Preferably, an oil seal is provided at the connection between the frame bin and the stirring shaft, the double helical stirring blade includes an outer spiral blade, an inner spiral blade and a connecting rod, the outer spiral blade and the inner spiral blade are coaxial, the inner spiral blade is close to the axis, and the outer spiral blade and the inner spiral blade are connected to the stirring shaft through a connecting rod.

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

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

[0010] Step 1: Combined with the size of the device, the water volume in the device at the predetermined water level can be known, and the sediment concentration can be obtained. The functional relationship between the sediment volume required to configure the sediment concentration can be determined, and the energy of stirring the sediment can be measured as the momentum of the water flow driven by the superposition blades, which can be simplified to the superposition of the flow velocity generated by the water body driven by the blades. The rack compartment is divided into a measuring compartment and two mixing compartments. The measuring compartment is located in the middle of the two mixing compartments. The measuring compartment and the mixing compartment are separated by a metal grid with an interval of 10 cm. A three-dimensional movable guide rail is set on the measuring compartment;

[0011] Step 2: Prepare dry soil required for different calibration sediment concentrations according to the measuring range of the sediment monitoring instrument to be tested, and use clean water to fully clean the rack bin to avoid residual sediment in the bin;

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

[0013] Step 4: Start the motor, add a certain amount of dry soil weighed from the mixing bin to prepare a water-sand mixture with a given sediment concentration, and keep the sediment particles in a suspended state under the action of hydraulic pressure;

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

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

[0016] Step 7: By comparing the time series characteristics of the data obtained by the instrument to be tested at the same sampling point under the same sediment concentration, its temporal stability can be evaluated;

[0017] Step 8: Calibrate the instrument based on the given sediment concentration and the actual data read by the instrument to be tested;

[0018] Step 9: After the test instrument is inspected and calibrated, empty the rack compartment and rewash it with clean water.

[0019] Preferably, the three-dimensional guide rail is equipped with a bearing sliding block module for supporting and guiding the components to move linearly in a given direction. There is a deeper contact area between the guide rail and the sliding block, which can improve the load-bearing capacity of the system. At the same time, there is a fixed lock on the sliding block, which can place the device to be tested in a fixed position to test the time stability of the instrument performance.

[0020] Preferably, the initial position is a liquid level of 32 cm from the top of the rack bin.

[0021] Preferably, the functional relationship formula between the amount of sediment required to configure the sediment concentration is:

[0022]

[0023] Where D is the sediment concentration; W soil V is the dry soil mass required to configure the sediment concentration; W is the amount of water in the device at the predetermined water level; soil is the bulk density of dry soil.

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

[0025] V=V1+V2+V3

[0026] V3 is the flow rate provided by the external circulation, which is equal to the ratio of flow rate to water flow area. Where Q is the flow rate and A is the water flow area;

[0027] V1 is the velocity of the water body pushed by the outer blade surface, and V2 is the velocity of the water body pushed by the inner blade surface. The formula is as follows:

[0028]

[0029] Where V t and V r are the tangential and radial flow velocities of the water along the outer and inner blade surfaces, respectively, and the relationship between the two can be obtained through the blade angle, V r =V t tanβ, β is the horizontal angle of the blade surface equal to:

[0030]

[0031] Where L is the wheelbase of the impeller, D1 and D2 are the diameters of the outer and inner impellers respectively, n is the number of blade turns, ω is the angular velocity of the impeller, and μ is the efficiency coefficient based on the conversion of blade surface proportional area, which can be obtained by the following formula:

[0032]

[0033] Where R1 and R2 are the radii of the outer and inner impellers, d is the impeller blade width, A1 and A2 are the water flow areas of the outer and inner impellers respectively, and A'1 and A'2 are the areas of the outer and inner impellers.

[0034] Preferably, the sediment particles are kept in a suspended motion state under the action of hydraulic pressure, and the critical flow velocity at this time can be obtained by Sha Yuqing's formula, which is:

[0035] V s =0.815d 2 / 5 w 1 / 5 R 1 / 5

[0036] Where d is the particle size of the sediment, R is the hydraulic radius of the device, and the ratio of the water flow area to the wetted perimeter λ is w is the sediment settling velocity:

[0037]

[0038] Where k is the sphere settlement correction factor, γ and γ s are the bulk densities of water and sediment respectively, g is the acceleration of gravity, and v is the kinematic viscosity coefficient of water.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The detection device of the present invention can be configured with uniform sediment samples that have been fully stirred, and the sediment samples in the device are always in motion, which can simulate the complex scenes in natural rivers in the wild to a certain extent, thereby improving the performance detection capability of sediment monitoring equipment. The calibration method supporting the device can perform real-time corrections on the equipment to be tested under different sediment concentrations to improve the detection accuracy of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0042] Figure 2 A top view of the present invention as a whole;

[0043] Figure 3 It is a schematic diagram of the partial internal structure of the rack bin of the present invention;

[0044] Figure 4 It is a schematic diagram of the partial structure of the double helical stirring blade of the present invention;

[0045] Figure 5 A three-dimensional schematic diagram of the sampling point layout of the present invention;

[0046] Figure 6 This is a plan view of the sampling point layout of the present invention;

[0047] Figure 7 A schematic diagram of the structure for determining the sampling depth of the present invention;

[0048] Figure 8 It is a box plot of the deviation of detection of different sediment concentrations, sampling depths and sampling groups of the present invention;

[0049] Fig. 9 Comparison chart of sediment concentration measured by turbidity meter and calibrated sediment concentration;

[0050] Fig.10 This is a curve diagram of the change in sediment uniformity and impeller speed in the device under different sediment concentrations. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0052] See also Figures 1 to 10 An embodiment of the present invention is as follows: a sediment monitoring instrument comprises a frame shell 2, a frame bin 1 is provided in the middle position of the frame shell 2, a sediment inlet 13 is provided on one side of the top of the frame bin 1, a sediment discharge port 12 is provided on the other side of the bottom of the frame bin 1, a driving pump 4 is connected between the sediment discharge port 12 and the sediment inlet 13 through a pipeline 3, an electromagnetic flowmeter is installed in the pipeline 3, the driving pump 4 is an electric centrifugal pump, both sides of the frame bin 1 are penetrated and movably connected with a stirring shaft 7, a position of the stirring shaft 7 located inside the frame bin 1 is installed with a double helical stirring blade 11, a portion of the stirring shaft 7 located outside the frame bin 1 is rotatably connected to a bearing seat 10 on the upper surface of the frame shell 2, and a driven sprocket 8 is fixedly provided on the outer surface of the stirring shaft 7 located outside the frame bin 1.

[0053] 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 installed with a driving sprocket 9. The driving sprocket 9 is connected to the driven sprocket 8 through a transmission chain.

[0054] An oil seal is provided at the connection between the frame bin 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 axis. The outer helical blade 1101 and the inner helical blade 1102 are both connected to the stirring shaft 7 through the connecting rod 1103.

[0055] A water injection port is provided on one side of the sediment discharge port 12, and a flow meter is provided on the water injection port.

[0056] A metrological calibration method for a sediment monitoring instrument comprises the following steps:

[0057] Step 1: Combined with the size of the device, the amount of water in the device at the predetermined water level can be known, and the sediment concentration can be obtained. The functional relationship between the amount of sediment required to configure the sediment concentration can be determined, and the energy of stirring the sediment can be measured as the momentum of the water flow driven by the superposition of the blades, which can be simplified to the superposition of the flow velocity generated by the blades driving the water body. The rack compartment is divided into a measuring compartment and two mixing compartments. The measuring compartment is located in the middle of the two mixing compartments. The measuring compartment and the mixing compartment are separated by a metal grid with a spacing of 10 cm. A three-dimensional movable guide rail is set on the measuring compartment. The three-dimensional guide rail is equipped with an instrument fixing frame. 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 deeper contact area between the guide rail and the slider, which can improve the load-bearing capacity of the system. At the same time, there is a fixed lock on the slider, which can place the equipment to be tested in a fixed position to test the time stability of the instrument performance;

[0058] Step 2: Prepare dry soil required for different calibration sediment concentrations according to the measuring range of the sediment monitoring instrument to be tested, and use clean water to fully clean the rack bin to avoid residual sediment in the bin;

[0059] Step 3: Open the valve corresponding to the water inlet at the bottom of the device and add water to the device until the liquid level stabilizes at the initial position marked in the rack bin. The initial position is 32 cm from the top of the rack bin and the water volume in the rack bin is 6 m 3 , then close the water injection valve;

[0060] Step 4: Start the motor, add a certain amount of dry soil weighed from the mixing bin to prepare a water-sand mixture with a given sediment concentration, and keep the sediment particles in a suspended state under the action of hydraulic pressure;

[0061] Step 5: Fix the instruments to be tested at different preset sampling points in the sediment testing chamber area, take readings and record them;

[0062] Step 6: Evaluate the spatial stability of the instrument under test by comparing the sediment data at different sampling points under the same sediment concentration;

[0063] Step 7: By comparing the time series characteristics of the data obtained by the instrument to be tested at the same sampling point under the same sediment concentration, its temporal stability can be evaluated;

[0064] Step 8: Calibrate the instrument based on the given sediment concentration and the actual data read by the instrument to be tested;

[0065] Step 9: After the test instrument is inspected and calibrated, empty the rack compartment and rewash it with clean water.

[0066] The functional relationship between the amount of sediment required to configure the sediment concentration is:

[0067]

[0068] Where D is the sediment concentration in kg / m 3 ; W soil V is the dry soil mass required to configure the sediment concentration, in kg; W The amount of water in the device at the preset water level, in m 3 ρ soil is the bulk density of dry soil, which is 2.65kg / m 3 .

[0069] The superposition formula of the flow velocity generated by the blade driving the water body is:

[0070] V=V1+V2+V3

[0071] V3 is the flow rate provided by the external circulation, which is equal to the ratio of flow rate to water flow area. Q is the flow rate, which is 50L / s, and A is the water flow area, which is 2m 2 , that is, V3 = 0.025m / s;

[0072] V1 is the velocity of the water body pushed by the outer blade surface, and V2 is the velocity of the water body pushed by the inner blade surface. The formula is as follows:

[0073]

[0074] Where V t and V r are the tangential and radial flow velocities of the water along the outer and inner blade surfaces, respectively, and the relationship between the two can be obtained through the blade angle, V r =V t tanβ, β is the horizontal angle of the blade surface equal to:

[0075]

[0076] Where L is the wheelbase of the impeller, which is equal to 850mm, D1=1470mm and D2=490mm are the diameters of the outer and inner impellers respectively, n is the number of blade turns, which is equal to 2, ω is the angular velocity of the impeller rpm / min, and μ is the efficiency coefficient based on the conversion of blade surface equal specific area, which can be obtained by the following formula:

[0077]

[0078] Where R1 = 735mm and R2 = 490mm are the radii of the outer and inner impellers, d is the impeller blade width equal to 50mm. A1 and A2 are the water flow areas of the outer and inner impellers respectively, and A'1 and A'2 are the areas of the outer and inner impellers.

[0079] The sediment particles remain in a suspended motion state under the action of hydraulic pressure. The critical flow velocity at this time can be obtained by the Sha Yuqing formula, which is:

[0080] V s =0.815d 2 / 5 w 1 / 5 R 1 / 5

[0081] Where d is the particle size of the sediment. The median particle size of the loess soil used in the experiment is d = 0.05 mm. R is the hydraulic radius of the device, which is equal to the ratio of the water flow area to the wetted perimeter λ. w is the sediment settling velocity:

[0082]

[0083] Where k is the correction factor for sphere settlement, which is equal to 0.75, γ and γ s are the bulk densities of water and sediment, respectively, taking 1t / m 3 and 2.65t / m 3 , g is the acceleration due to gravity, take 9.8m 2 / s, v is the kinematic viscosity of water, when the temperature is equal to 20℃, it is 1.01×10-6m 3 / s.

[0084] Based on the above formula, the lifting speed of sediment can be obtained as Device requirements V ≥ V s , at this time ω≥9.86rpm / min.

[0085] The stirring impeller is driven by two variable speed motors located on both sides through chains and bearings. The variable speed motor is connected to the PCL controller and controlled by the circuit. In order to meet the stirring impeller speed requirements, the selected motor rated power is 5kw, which can achieve a stirring impeller speed change within 0 to 100 rpm.

[0086] 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 spacing of 10 cm. While ensuring the safety of the instruments and equipment to be tested in the measuring chamber, the metal grid also plays a certain ballast role and improves the flow stability in the measuring chamber.

[0087] The device's measuring chamber is equipped with a three-dimensional movable guide rail, which can fix the equipment to be monitored at different positions and depths to test the spatial stability of the instrument's performance.

[0088] As shown in Table 1 below, after cleaning the instrument, water is added through the water inlet until the liquid level stabilizes at 32 cm from the top of the detection chamber. At this time, the volume of water inside the device is 6m 3 ; A total of 9 gradients were set in the experiment, and the sediment concentration range was 1 to 100 kg / m 3 .

[0089] Table 1 Sediment concentration configuration

[0090]

[0091] The sampling points in rack compartment 1 are arranged as follows Figure 5 and Figure 6 As shown in Figure 2, the deepest monitoring points of Group A and Group C are 1.6m from the top of the instrument, and those of Group B are 1.8m. Figure 7 As shown, the starting measurement position of h is at 1 / 2 height of the turbidity meter probe. The sampling depths of Group A and Group C are 30cm, 60cm and 90cm below the liquid surface; the sampling of Group B is set at 120cm below the liquid surface. Considering that the movement of the turbidity meter probe in the measuring chamber will disturb the sediment concentration in the surrounding area, thus affecting the experimental results, the turbidity meter is used to detect the sediment concentration at each sampling point, and the interval is 5 seconds. 3 readings are read continuously and recorded as one group. When the absolute deviation between a group of data is less than 5% of the current concentration, it is considered that the current sediment concentration has stabilized, and the mean of the group of data is calculated and recorded.

[0092] In order to establish a calibration method for sediment concentration and impeller speed, the relationship between the two under different sediment concentrations was analyzed and 1, 10, 20, 50, and 100 kg / m 3 , a total of five sediment concentration gradients, the impeller angular velocity is controlled in the range of 10-30rpm / min by the variable speed motor. Based on the acquired data, the following indicators are calculated to evaluate the uniformity of the instrument stirring sediment:

[0093]

[0094] Among them, SD and Mean are the standard deviation and mean of sediment measurements in different treatment groups, respectively, TI1 reflects the uniformity of the data; Test and Org are the sediment concentrations at the sampling point and the sediment concentrations in the experimental setting, respectively, and TI2 is the degree of deviation of the sampling data.

[0095] The paired sample Wilcoxon test was used to process the data of each sampling point in pairs to analyze whether there were significant differences in the sediment concentration data obtained at each sampling point. The Wilcoxon test is a non-parametric test and does not require the sample data to satisfy the normal distribution.

[0096] like Figure 8 As shown in the figure, the deviation and uniformity of sediment detection under different sediment concentrations, sampling depths and sampling groups are displayed. The horizontal line in the box plot is the median, the upper and lower borders are 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 the group; the data under the box plot is the corresponding uniformity.

[0097] Combined with Table 2 below, the results show that the deviation of sediment detection remains stable as the sediment concentration increases, from 1kg / m 3 0±4.41% becomes 100kg / m 3 The deviation of sediment concentration at different sampling depths was close, all less than 1%. When the sampling depth was 60 cm, the maximum deviation was -0.29±2.83%, and the minimum deviation was 0.04±2.02% when the sampling depth was 120 cm. The maximum sediment uniformity was 98.88% at this depth, and the minimum was 97.12% at 30 cm. The deviation of sediment concentration in group C was the smallest, 0.14±3.22%, and the maximum was -0.56±2.54% in group A. The sediment uniformity of each group was close, all between 97% and 98%. The differences between the sampling points were generally small, among which point A1 had the largest deviation, which was -0.95±3.83%, and point C3 had the smallest deviation, which was 0.01±2.21%; the uniformity of each sampling point was greater than 97%, among which point A3 had the highest uniformity of 98.94% and point C1 had the lowest uniformity of 97.01%.

[0098] Table 2. Deviation and uniformity of sampling data

[0099]

[0100]

[0101] The sediment concentration data of different sampling points were subjected to paired sample Wilcoxon test. The test results showed that the P-value was greater than or equal to 0.05, that is, at the significance level of alpha = 0.05, there was no significant difference in the sediment concentration of each sampling point.

[0102] Based on the above process, 0~100kg / m 3Turbidimeter measurement results of sediment concentration, experimental settings 1, 3, 5, 10, 20, 30, 50, 75, 100 kg / m 3 There are 9 sediment concentration gradients in total, and each gradient obtains 90 sets of sediment concentration values ​​measured by turbidity meters at different locations. The comparison between the two in the experiment found that: when the sediment concentration is less than 20kg / m 3 Within the range of 75 kg / m3, the measurement results of the turbidity meter are consistent with the calibration results. However, as the sediment concentration gradually increases, the measurement results of the turbidity meter are smaller than the actual value, and the difference is more obvious with the increase of the concentration. 3 The average value of 30 repeated measurements by the turbidity meter was 69.10±3.92kg / m 3 When the calibration concentration is 100kg / m 3 91.43±4.82kg / m 3 ,like Fig. 9 As shown, the sediment concentration measured by the turbidity meter can be calibrated using a linear equation.

[0103] like Fig.10 As shown in the figure, the experimental results of the change of sediment uniformity with the impeller speed under different sediment concentrations show that with the increase of the impeller angular velocity under different sediment concentrations, the uniformity of the sediment in the device increases, and the higher the sediment concentration, the more significant the change trend of uniformity. 3 When the impeller speed increases from 10 rpm / min to 30 rpm / min, the uniformity of sediment in the device increases from 23.45% to 98.76%, and when the sediment concentration is 1 kg / m 3 When the speed is 10 rpm / min, the uniformity changes only from 93.72% to 99.63%, which is a small change.

[0104] Based on the experimental results, a calibration method for the sediment detection instrument suitable for this device was developed, namely, the optimal impeller speed for different sediment concentrations to meet 95% sediment uniformity, as shown in Table 3 below.

[0105] Table 3. Measuring and calibrating setting method of impeller speed at different sediment concentrations

[0106]

[0107] The experimental results show that when the uniformity is 95%, the sediment concentration and the impeller speed are significantly positively correlated. The relationship between the two can be fitted by a logarithmic function. The R 2 Up to 98%

[0108] It will be apparent to those skilled in the art that the 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A sediment monitoring instrument, comprising a frame housing, characterized in that: A rack bin is provided in the middle of the rack shell, a sediment inlet is provided on one side of the top of the rack bin, a sediment discharge port is provided on the other side of the bottom of the rack bin, a driving pump is connected between the sediment discharge port and the sediment inlet through a pipeline, a stirring shaft is movably connected through both sides of the rack bin, a double-helical stirring blade is installed at the position of the stirring shaft located inside the rack bin, a portion of the stirring shaft located outside the rack bin is rotatably connected to a bearing seat on the upper surface of the rack shell, and a driven sprocket is fixedly provided on the outer surface of the stirring shaft located outside the rack bin; A motor is installed on one side of the stirring shaft, the output shaft of the motor is connected to a reducer through a coupling, the output shaft of the reducer is installed with a driving sprocket, and the driving sprocket and the driven sprocket are connected through a transmission chain.

2. A sediment monitoring instrument according to claim 1, characterized in that: An oil seal is provided at the connection between the frame bin and the stirring shaft. The double helical stirring blade comprises an outer helical blade, an inner helical blade and a connecting rod. The outer helical blade and the inner helical blade are coaxial, the inner helical blade is close to the axis, and the outer helical blade and the inner helical blade are connected to the stirring shaft through the connecting rod.

3. A sediment monitoring instrument according to claim 2, characterized in that: A water injection port is arranged on one side of the sediment discharge port, and a flow meter is arranged on the water injection port.

4. A metrological calibration method for a sediment monitoring instrument as claimed in any one of claims 1 to 3, characterized in that: The steps include: Step 1: Combined with the size of the device, the water volume in the device at the predetermined water level can be known, and the sediment concentration can be obtained. The functional relationship between the sediment volume required to configure the sediment concentration can be determined, and the energy of stirring the sediment can be measured as the momentum of the water flow driven by the superposition blades, which can be simplified to the superposition of the flow velocity generated by the water body driven by the blades. The rack compartment is divided into a measuring compartment and two mixing compartments. The measuring compartment is located in the middle of the two mixing compartments. The measuring compartment and the mixing compartment are separated by a metal grid with an interval of 10 cm. A three-dimensional movable guide rail is set on the measuring compartment; Step 2: Prepare dry soil required for different calibration sediment concentrations according to the measuring range of the sediment monitoring instrument to be tested, and use clean water to fully clean the rack bin to avoid residual sediment in the bin; Step 3: Open the valve corresponding to the water inlet at the bottom of the device, add water into the device until the liquid level stabilizes at the initial position marked in the rack compartment, and then close the water injection valve; Step 4: Start the motor, add a certain amount of dry soil weighed from the mixing bin to prepare a water-sand mixture with a given sediment concentration, and keep the sediment particles in a suspended state under the action of hydraulic pressure; Step 5: Fix the instruments to be tested at different preset sampling points in the sediment testing chamber area, take readings and record them; Step 6: Evaluate the spatial stability of the instrument under test by comparing the sediment data at different sampling points under the same sediment concentration; Step 7: By comparing the time series characteristics of the data obtained by the instrument to be tested at the same sampling point under the same sediment concentration, its temporal stability can be evaluated; Step 8: Calibrate the instrument based on the given sediment concentration and the actual data read by the instrument to be tested; Step 9: After the test instrument is inspected and calibrated, empty the rack compartment and rewash it with clean water.

5. The sediment monitoring instrument and the measurement and calibration method thereof according to claim 1, characterized in that: 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 deeper contact area between the guide rail and the slider, which can improve the load-bearing capacity of the system. At the same time, there is a fixed lock on the slider, which can place the device to be tested in a fixed position to test the time stability of the instrument performance.

6. A sediment monitoring instrument and a measurement and calibration method thereof according to claim 1, characterized in that: The initial position is that the liquid level is 32 cm from the top of the rack bin.

7. The sediment monitoring instrument and the measurement and calibration method thereof according to claim 1, characterized in that: The functional relationship between the amount of sediment required to configure the sediment concentration is: Where D is the sediment concentration; W soil V is the dry soil mass required to configure the sediment concentration; W is the amount of water in the device at the predetermined water level; soil is the bulk density of dry soil.

8. The sediment monitoring instrument and the measurement and calibration method thereof according to claim 1, characterized in that: The superposition formula of the flow velocity generated by the blade driving the water body is: V=V1+V2+V3 V3 is the flow rate provided by the external circulation, which is equal to the ratio of flow rate to water flow area. Where Q is the flow rate and A is the water flow area; V1 is the velocity of the water body pushed by the outer blade surface, and V2 is the velocity of the water body pushed by the inner blade surface. The formula is as follows: Where V t and V r are the tangential and radial flow velocities of the water along the outer and inner blade surfaces, respectively, and the relationship between the two can be obtained through the blade angle, V r =V t tanβ, β is the horizontal angle of the blade surface equal to: Where L is the wheelbase of the impeller, D1 and D2 are the diameters of the outer and inner impellers respectively, n is the number of blade turns, ω is the angular velocity of the impeller, and μ is the efficiency coefficient based on the conversion of blade surface proportional area, which can be obtained by the following formula: Where R1 and R2 are the radii of the outer and inner impellers, d is the impeller blade width, A1 and A2 are the water flow areas of the outer and inner impellers respectively, and A'1 and A'2 are the areas of the outer and inner impellers.

9. A sediment monitoring instrument and a measurement and calibration method thereof according to claim 1, characterized in that: The sediment particles remain in a suspended motion state under the action of hydraulic pressure. The critical flow velocity at this time can be obtained by the Sha Yuqing formula, which is: 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, and the ratio of the water flow area to the wetted perimeter λ is w is the sediment settling velocity: Where k is the sphere settlement correction factor, γ and γ s are the bulk densities of water and sediment respectively, g is the acceleration of gravity, and v is the kinematic viscosity coefficient of water.

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