Flow and iron content measuring method and system for iron fine powder ore pulp pipeline transportation

Abstract

The invention discloses a method and a system for measuring flow and iron content of fine iron ore pulp. The method comprises the following steps of: sleeving two detection coils with the same parameters on a transportation pipeline of iron fine powder ore pulp in a front-and-back spaced manner, connecting the two detection coils into a detection module, and acquiring two similar detection signals with time delay of the two detection coils when the detection signals flow through the iron fine powder ore pulp by using the detection module; and measuring and detecting the flow and the iron content by utilizing the property that the iron concentrate pulp contains ferromagnetic substances in the two detection signals. According to the invention, the volume flow rate of the iron fine powder ore pulp in the pipeline transportation process and the content of iron elements in the ore pulp can be detected in real time, the iron fine powder ore pulp can be monitored in the transportation process, control, distribution and settlement are convenient, and the iron content of the iron fine powder ore pulp can be known in real time, so that the iron content of the iron fine powder ore pulp can be known approximately.

Description

Technical Field

[0001] The present invention relates to a pipeline transportation measurement method and system, and relates to a measurement method and system for the flow rate and iron content of iron ore concentrate pulp during pipeline transportation. Background Art

[0002] Iron ore concentrate is fine iron ore powder processed from iron ore through crushing, grinding, ore dressing, etc. Its transportation methods mainly include railway, highway, water transportation, and pipeline transportation. Except for pipeline transportation, there are dust problems during railway, highway, and water transportation. Of course, when the distance is very long and there is no long-term fixed-point supply, only railway, highway, and water transportation can be used.

[0003] Mixing iron ore concentrate with water and stirring it into iron ore concentrate pulp for pipeline transportation began to be studied at the end of the 20th century. For supplying long-term fixed-point steel enterprises, it has the advantages of low cost, large transportation capacity, high efficiency, the pipeline being buried underground without occupying arable land, being unaffected by climate conditions, and having no impact on the atmospheric environment by vehicle transportation.

[0004] The conveying flow velocity and flow rate of pipeline transportation are the basis for control, distribution, and settlement. Therefore, during the pipeline transportation of pulp, strict requirements are imposed on the accuracy of measuring and controlling the transportation flow rate. And the transported material being a solid-liquid mixed medium increases the difficulty of flow rate detection. So the research on pipeline flow rate detection is more urgent. Currently, there are mainly two detection methods for measuring the uniform flow velocity and flow rate of solid-liquid two-phase: contact type and non-contact type. Contact type flow rate detection equipment needs to be regularly maintained due to problems such as wear, consuming a lot of manpower and material resources. Non-contact type flow rate detection equipment is generally an electromagnetic flowmeter, but the physical characteristics of the liquid-solid two-phase flow in the transportation of iron ore concentrate pulp are much more complex than those of single-phase flow, resulting in a large detection error.

[0005] In addition to the flow rate detection of iron ore concentrate pulp, detecting the iron content in the iron ore concentrate flowing through within a certain period of time is even more difficult. Currently, in the actual production of steel mills, the detection of the iron content in iron ore concentrate needs to be sampled to the laboratory for further analysis. Although the detection results are relatively accurate, the process is rather cumbersome, the detection time is long, the detection cost is high, and it is difficult to detect how much iron the pulp flowing through contains during pipeline transportation of the pulp. Summary of the Invention

[0006] In order to solve the problems existing in the background art, the purpose of the present invention is to provide a measurement method and system for the flow rate and iron content of iron ore concentrate pulp, so as to realize real-time on-line detection of the volume flow rate and iron content of the pulp.

[0007] The technical solution adopted by the present invention is as follows: I. A measurement method for the flow rate and iron content of iron ore concentrate pulp: Two detection coils with the same parameters are sleeved on the transportation pipeline of iron ore concentrate pulp at a certain distance from each other. The flow rate and iron content are measured by utilizing the property that the iron ore concentrate pulp contains ferromagnetic substances, that is, the mechanism of ferromagnetic substances affecting the self-inductance coefficient L of the coil in the coil is used for flow rate and iron content measurement and detection.

[0008] When the iron ore concentrate pulp flows inside the transportation pipeline, since the flow of the iron ore concentrate pulp is not completely uniform during the flow process, it will bring about changes in the magnetic permeability inside the coil, thereby causing corresponding changes in the inductance and complex impedance of the coil. Connect the two detection coils to the detection module, and use the detection module to collect two similar and time-delayed detection signals of the two detection coils when the iron ore concentrate pulp flows through. The flow rate and iron content are measured and detected by utilizing the property that the iron ore concentrate pulp contains ferromagnetic substances in the two detection signals.

[0009] The method includes: Calculating the time delay between the two detection signals by using the coherent analysis processing method; At the same time, by measuring the distance between the two detection coils, combining the time delay and the distance to obtain the flow velocity of the iron ore concentrate pulp transported in the transportation pipeline, and then obtaining the volume flow rate of the iron ore concentrate pulp flowing in the transportation pipeline according to the cross-sectional area of the transportation pipeline; At the same time, the iron content in the iron ore concentrate pulp is obtained by processing according to the amplitude of the detection signal.

[0010] The iron ore concentrate pulp is composed of water and iron ore concentrate. Among them, the magnetic permeability μ of iron contained in the iron ore concentrate is much greater than the magnetic permeability of other substances in the pulp. For the inductance of the coil, for a certain coil, other parameters are unchanged. Therefore, the inductance of the coil will change correspondingly in real time according to the magnetic permeability of iron contained in the iron ore concentrate pulp flowing inside it. Since the magnitude of this change is determined by the iron in the iron ore concentrate pulp, the iron content in the iron ore concentrate pulp can be judged according to the magnitude of the detection signal.

[0011] Since the parameters of the two detection coils above the pipeline are the same, the influence changes caused by a certain section of iron ore concentrate pulp on the two detection coils are the same. Therefore, the waveforms of the two detection signals should be similar. Also, because the two detection coils are sleeved on the transportation pipeline at intervals, it takes a certain amount of time for the iron ore concentrate pulp to flow from the position of the previous coil to the position of the next coil. Therefore, there is a certain time delay between the waveforms of the two detection signals. The time required for the pulp to flow from the previous coil to the next coil can be known according to the time delay of these two signals, so as to calculate the flow velocity and flow rate.

[0012] The method for detecting and analyzing the time delay between two signals is a coherent analysis processing method, which is a method for studying the correlation, delay, and frequency characteristics between two signals.

[0013] The coherent analysis processing method of the method is specifically as follows: The output voltage U' of the bridge where one detection coil is located a0 The corresponding amplified effective value U a The time variable of is x ( t ) and the output voltage U' of the bridge where the other detection coil is located b0 The corresponding amplified effective value U b The time variable of is y ( t ) For the two detection signals that change with time x ( t ) and y ( t ) perform Fourier transform to obtain the frequency-domain signals: X(f)= ∫ ∞ -∞ x(t)e -j2πft dt Y(f)= ∫ ∞ -∞ y(t)e -j2πft dt Among them, X ( f ) and Y ( f ) respectively represent the frequency-domain signals corresponding to the two detection signals; f represents the frequency variable; t represents the time variable; e represents the natural constant, the base of the complex exponential, used to construct the complex sine basis function; j represents the unit imaginary number, j ²=-1; Then, calculate the power spectral density for the frequency-domain signals X(f) and Y(f) according to the following formula to obtain the power spectral density, which are respectively expressed as: S xx (f)=lim T→∞ ((|X T (f)| 2 ) / T) S yy (f)=lim T→∞ ((|Y T (f)| 2 ) / T) Among them, S xx (f) and S yy (f) respectively represent the power spectral densities corresponding to two detection signals, X T (f) and Y T (f) respectively represent the frequency-domain signals corresponding to two detection signals within the time period T, T represents the duration of the time period, and lim represents the "limit" operation; Next, calculate the cross-spectral density between the two detection signals according to the frequency-domain signals X(f) and Y(f) simultaneously: S xy (f) = lim T→∞ ((X T (f) • Y * T (f)) / T) Among them, S xy (f) represents the cross-spectral density between the two detection signals, Y * T (f) represents the complex conjugate of Y T (f), and * represents the complex conjugate calculation; Calculate the coherence function of the correlation between the two detection signals at frequency f according to the power spectral densities of the two detection signals respectively and the cross-spectral density between the two detection signals: C xy (f) = |S xy (f)| 2 / (S xx (f) • S yy (f)) Among them, C xy (f) represents the coherence parameter between the two detection signals; Finally, select the two detection signals related according to the coherence function, that is, when C xy (f) is within the preset correlation range, calculate the time delay between the two detection signals.

[0014] When C xy (f) is close to 1, it indicates that the two detection signals are completely correlated; When C xy (f) is close to 0, it indicates that the two detection signals are completely uncorrelated; When C xy (f) is close to -1, it indicates that the two detection signals are negatively correlated.

[0015] The coherence function C xy ( f ) The closer it is to 1, the higher the correlation between the two signals, and the closer it is to 0, the lower the correlation between the two signals. According to x ( t ) andy ( t ) The similarity of the two detection signals, and the lag signal y ( t ) is shifted forward by a time shift amount on the time axis τ to obtain a new signal y ( t + τ ). The above-mentioned coherence analysis method is continuously used to calculate x ( t ) and y ( t + τ ) the coherence function between the two signals C xy . When the value of the coherence function of the two signals is closest to 1, the correlation between the two signals is the highest. At this time, the corresponding time shift amount τ is x ( t ) and y ( t ) the time delay between the two signals. The delay time τ between the two signals is the time required for the pulp containing iron powder in the pipeline to flow from the previous detection coil to the next detection coil. Dividing the delay time τ by the distance between the two detection coils can calculate the flow rate of the pulp. Then multiplying the flow rate by the cross-sectional area of the pipeline can obtain the flow rate of the iron concentrate pulp.

[0016] The present invention is the first to propose detecting the flow rate of iron concentrate pulp by using the change of inductance value, and can simultaneously detect the flow rate and iron content information of iron concentrate pulp during pipeline transportation, realizing real-time detection during the transportation process of iron concentrate.

[0017] II. A measurement system for the flow rate and iron content of iron concentrate pulp: It includes a on-site measurement device and a remote measurement instrument, which are connected by wireless transmission communication. Among them: The on-site measurement device mainly consists of two identical detection coils sleeved on the transportation pipeline and arranged at intervals, and a detection module for collecting coil signals. The detection coils and the detection module are electrically connected; the detection module for collecting coil signals mainly consists of a module housing and a hardware circuit board inside the module housing. The hardware circuit board is connected to the detection coils, and an NRF wireless transmission module is installed on the hardware circuit board for transmitting data to the remote measurement instrument; the remote measurement instrument mainly consists of an NRF wireless reception module, a remote reception device, and a host computer; the remote reception device is internally provided with an NRF wireless reception module, the NRF wireless reception module and the NRF wireless transmission module are in communication connection, and the remote reception device is connected to the host computer; the transportation pipeline is used for transporting iron concentrate pulp, and the iron concentrate pulp contains ferromagnetic substances.

[0018] In the detection module for collecting coil signals, the hardware circuit board is built with an MCU and a bridge detection circuit, and the two detection coils are respectively connected to the bridge detection circuit on the hardware circuit board; first, the MCU is used to control the direct digital frequency synthesis technology DDS to generate a sinusoidal AC signal. After the sinusoidal AC signal is isolated from DC, high-order harmonics are filtered out by an RC filter; then, a power amplifier is used to amplify the sinusoidal AC signal to obtain an excitation signal, and the excitation signal is used to respectively excite the bridge detection circuits where the two detection coils are located, and two groups of differential signals U' a0 and U' b0 ; Then, an instrumentation amplifier is used to perform differential mode amplification on the two groups of differential signals respectively. After filtering out high-order harmonics and then performing gain amplification, an RMS conversion circuit is used to convert them into DC signals, and finally they are transmitted back to the MCU for ADC sampling processing, and finally two groups of detection signals U a and U b are obtained. The two groups of detection signals obtained are used for data transmission to a remote measuring instrument.

[0019] It includes two said bridge detection circuits, which respectively correspond to two detection coils; the two detection coils on the transportation pipeline are respectively connected to two identical bridge detection circuits. Each group of bridge detection circuits mainly consists of a fixed resistor, a variable resistor, and a balance coil. The detection coil and the fixed resistor are connected in series and then connected in parallel to the excitation signal U'0 to form one arm of the bridge, and the balance coil and the variable resistor are connected in series and then connected in parallel to the excitation signal U'0 to form another arm of the bridge. The lead-out end between the detection coil and the fixed resistor and the lead-out end between the balance coil and the variable resistor form a differential signal output end; wherein the resistance value of the fixed resistor is the impedance value of the detection coil when it is excited by the excitation signal in the hollow state, the maximum resistance value of the variable resistor is more than twice that of the fixed resistor, and the balance coil is a hollow coil with the same parameters as the detection coil.

[0020] The hollow state means that there is only air and no other substances in the coil.

[0021] The innovation of the present invention lies in introducing a bridge sampling circuit, thereby realizing high-precision acquisition of inductive coil signals. For the sampled signals, the time difference between the signals is accurately calculated by using the coherent analysis method, so as to obtain the flow information of the pulp transportation in the pipeline.

[0022] The present invention can detect in real time the volume flow rate of iron ore concentrate pulp during pipeline transportation and the content of iron elements in the pulp, which can help monitor the iron ore concentrate pulp during transportation, facilitate control, distribution and settlement, and can know in real time the iron content of the iron ore concentrate pulp, so as to roughly know how much iron can be smelted from it.

[0023] The beneficial effects of the present invention are as follows: The present invention can detect in real time the volume flow rate of iron ore concentrate pulp during pipeline transportation and the content of iron elements in the pulp, which can help monitor the iron ore concentrate pulp during transportation, facilitate control, distribution and settlement, and can know in real time the iron content of the iron ore concentrate pulp, so as to roughly know how much iron can be smelted from it.

[0024] Generally speaking, the present invention can effectively detect the changes in the volume flow rate and iron content during the pipeline transportation of iron ore concentrate pulp. The data of the detected volume flow rate can facilitate the staff to control, distribute and settle the size of the pulp flow rate. At the same time, it can detect negative situations such as pipeline scaling and leakage, which is convenient for early detection and early treatment; detecting the iron content can roughly judge how much iron can be smelted when transported into the steel plant furnace, which is related to economic benefits. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the composition of the flow rate and iron content measurement system of iron ore concentrate pulp; Figure 2 It is a schematic diagram of a double-bridge detection circuit; Figure 3 It is the circuit flow chart of the detection module; Figure 4 It is a detection signal data diagram.

[0026] In the figure: 1, 2, detection coils; 3, iron ore concentrate pulp; 4, transportation pipeline; 5, NRF wireless transmission module; 6, iron ore concentrate pulp flow rate and iron content detection module; 7, remote receiving device; 8, host computer; 9, 10, balance coils; 11, 12, fixed resistors; 13, 14, adjustable resistors. Detailed Embodiment

[0027] The following further describes the present invention in conjunction with the drawings and examples.

[0028] As Figure 1 shown, the specifically implemented system includes a field measurement device and a remote measurement instrument, which are connected by wireless transmission communication. Among them: The on-site measurement device mainly consists of two identical detection coils 1 and 2 sleeved on the transportation pipeline 4 and arranged at intervals, and a detection module 6 for collecting coil signals. The detection coils 1 and 2 are electrically connected to the detection module 6. The detection module 6 for collecting coil signals mainly consists of a module housing and a hardware circuit board inside the module housing. The hardware circuit board is connected to the detection coils 1 and 2, and a wireless transmission module 5 is installed on the hardware circuit board for transmitting data to a remote measuring instrument. The remote measuring instrument mainly consists of a wireless receiving module, a remote receiving device 7, and a PC host computer 8. The remote receiving device 7 is internally provided with a wireless receiving module. The wireless receiving module is wirelessly communication-connected to the wireless transmission module 5, and the remote receiving device 7 sends the received information to the PC host computer 8. The transportation pipeline 4 is used for transporting the iron ore concentrate pulp 3, and the iron ore concentrate pulp contains ferromagnetic substances.

[0029] The present invention utilizes the mechanism that the movement of ferromagnetic substances in an inductance coil will affect the change of inductance parameters. By measuring the voltages of two coils with a certain distance between them wound around the outer wall of the plastic pipeline for transporting the iron ore concentrate pulp, the flow rate measurement and iron content measurement of the transported iron ore concentrate pulp are realized. The specific introduction is as follows: When the iron ore concentrate pulp flows inside the pipeline, it will cause the magnetic permeability inside the coil to change. When the coil parameters are certain, there is a corresponding relationship between the magnetic permeability inside the coil and the inductance of the coil. The relationship between the coil inductance and the magnetic permeability of the medium inside the coil is: L = µN 2 A / l In the formula, A is the cross-sectional area of the coil perpendicular to the magnetic field induction intensity, L is the coil inductance, µ is the magnetic permeability, N is the number of turns of the coil, l is the coil length.

[0030] According to the above expression of inductance, the relationship between the complex impedance of the coil and the magnetic permeability can be obtained as: Z = R + jωL = R + jωμN 2 A / l In the formula, Z is the complex impedance of the coil, R is the coil resistance, j represents the unit imaginary number ( j 2 = -1), ω represents the angular frequency ( ω = 2π f ).

[0031] For a certain coil, the resistance, the number of turns, the cross-sectional area perpendicular to the magnetic induction intensity, and the coil length are all determined. Therefore, when the magnetic permeabilityµ When a change occurs, under the condition that the current frequency flowing through the coil is determined, the impedance ∣ Z ∣ of the coil only changes correspondingly with the magnetic permeability µ : |Z|=(R 2 +(ωL) 2 ) 1 / 2 = (R 2 +((ωμN 2 A) / l) 2 ) 1 / 2 A voltage measurement circuit / bridge detection circuit that realizes the change of the coil due to the change of the magnetic permeability µ is shown as Figure 2 follows.

[0032] As Figure 2 shown, the hardware circuit board includes two bridge detection circuits, corresponding to two detection coils 1 and 2 respectively; the two detection coils 1 and 2 on the transportation pipeline 4 are respectively connected to two identical bridge detection circuits, and the bridge detection circuits of the two detection coils 1 and 2 form a double-bridge detection circuit.

[0033] Each bridge detection circuit mainly consists of a fixed resistor 11 / 12, a detection coil 1 / 2, a variable resistor 13 / 14, and a balance coil 9 / 10, which respectively serve as one arm of the bridge. The detection coil 1 / 2 and the fixed resistor 11 / 12 are connected in series to the excitation signal U’0 to form one side of the bridge, and the balance coil 9 / 10 and the variable resistor 13 / 14 are connected in series to the excitation signal U’0 to form the other side of the bridge. The lead-out end between the detection coil 1 / 2 and the fixed resistor 11 / 12 and the lead-out end between the balance coil 9 / 10 and the variable resistor 13 / 14 form a differential signal output end for outputting the differential signal U’ a0 / U’ b0 ; where the resistance value of the fixed resistor 11 / 12 is the impedance value (the modulus of the complex impedance) of the detection coil 1 / 2 when there is no pulp in the pipeline under the excitation signal frequency; the maximum resistance value of the variable resistor 13 / 14 is 1.5 to 2 times that of the fixed resistor 11 / 12, which is used for zero adjustment of the bridge detection circuit; the balance coil 9 / 10 is an air-core coil with the same parameters as the detection coil 1 / 2 to balance the bridge.

[0034] In order to improve the sensitivity of the bridge circuit, a suitable fixed resistance value is matched. By analyzing the relationship between the bridge output sensitivity and the complex impedance through the formula, since the two bridge structures are the same, only one of the bridges needs to be calculated.

[0035] First, the condition for bridge balance: Z 11 / Z1 = Z13 / Z9 wherein, Z 11 and Z 13 are the complex impedances of the fixed resistor 11 and the adjustable resistor 13 in the figure respectively, Z1 is the complex impedance of the detection coil 1 in the figure when there is no iron concentrate pulp, and Z9 is the complex impedance of the balance coil 9 in the figure. In implementation, Z1 = Z9, Z 11 = Z 13 , and at this time U’ a0 = 0.

[0036] When the iron concentrate pulp flows through the pipeline, the complex impedance Z1 of the coil changes to Z1 + ΔZ1, and the output voltage U’ a0 is: U’ a0 = U’0 • ((Z1 + ΔZ1) / (Z 11 + Z1 + ΔZ1) - Z9 / (Z 13 + Z9)) wherein, U’0 is the phasor representation of the excitation signal (sinusoidal AC signal), and ΔZ1 represents the changed complex impedance of the detection coil 1; ΔZ1 is much smaller than Z1, and Z1 = Z9, Z 11 = Z 13 , and the above formula is transformed into: U’ a0 = U’0 • (ΔZ1Z 13 / ((Z 11 + Z1 + ΔZ1)·(Z 13 + Z9))) ≈ U’0 • (ΔZ1Z 13 / (Z 11 + Z1) 2 ) = U’0 • (ΔZ1 / Z1) · ((Z 11 / Z1) / (1 + (Z 11 / Z1)) 2 ) U a0 = |ΔZ1 / Z1| • |(Z 11 / Z1) / (1 + (Z 11 / Z1)) 2 | • U0 = δZ 1 • K • U0 wherein, U a0 is the modulus of U’ a0 , that is, the effective value of the sinusoidal AC signal represented by U’ a0 ; U0 is the modulus of U’0, that is, the effective value of the sinusoidal AC signal represented by U’0.

[0037] In the above formula δZ 1 = ∣ ΔZ 1 / Z $\Delta Z_1$ represents the relative change in the impedance of the detection coil 1, X = Z 11 / Z $n$ is the bridge arm ratio, then K =$|\Delta Z_1|$ X / (1 + X ) 2 $K$ is the bridge arm coefficient.

[0038] It can be seen from the above formula that the effective value of the output signal U’ a0 of the bridge circuit U a0 is related to the relative change in the impedance of the coil δZ $\Delta Z_1$, the bridge arm coefficient K $K$ and the excitation source U’ $E_0$. And the relative change in the impedance of the detection coil 1 δZ $\Delta Z_1$ reflects the sensitivity of the coil detection. Optimizing the parameters of the coil, such as the outer diameter, inner diameter, height, number of turns, etc., can improve the measurement sensitivity.

[0039] At this time, the effective values of the voltages of the two measured AC signals $U'$ a0 and $U'$ b0 are relatively small, which is not conducive to subsequent data analysis. Therefore, after processing these two voltage values through filtering, amplification, effective value conversion, etc., amplified effective values U a0 and U b0 corresponding to the changes of $U'$ a0 and $U'$ b0 are obtained. Utilizing the fact that the effective values U a and U b change as the iron ore pulp passes through the coil, the flow measurement of the conveyed iron ore pulp and the measurement of the iron content are realized. U a and U b

[0040] As Figure 3 shown, in the detection module 6 for collecting coil signals, the hardware circuit board has an MCU and a bridge detection circuit built in. The two detection coils 1 and 2 are respectively connected to the bridge detection circuit on the hardware circuit board; ​First, the MCU is used to control the direct digital frequency synthesis technology (DDS) to generate a sinusoidal alternating current signal. After isolating the direct current, the sinusoidal alternating current signal passes through an RC filter to filter out the high-order harmonics. Then, a power amplifier is used to amplify the sinusoidal alternating current signal to obtain a suitable excitation signal. The excitation signal is used to excite the bridge detection circuits where the two detection coils 1 and 2 are located, and two sets of differential signals U’ a0 and U’ b0 ; Then, an instrumentation amplifier is used to perform differential-mode amplification on the two sets of differential signals respectively. After filtering out the high-order harmonics and then performing gain amplification, a root-mean-square conversion circuit is used to convert them into direct current signals, and finally they are transmitted back to the MCU for ADC sampling processing, and finally the two sets of required detection signals U a and U b are obtained. The two sets of obtained detection signals are transmitted to a remote measuring instrument through a wireless communication module.

[0041] As Figure 3 shown, the circuit for collecting coil signals mainly includes an MCU control module, a DDS signal generation module, a bridge measurement module, a differential-mode amplification module, a signal amplification module, a root-mean-square conversion module, a wireless signal transmission module, and a power supply circuit module.

[0042] The method for measuring the flow rate and iron content of iron ore concentrate pulp in the present invention: The time delay between the two detection signals is calculated by using the coherent analysis processing method, specifically: The time variable of the amplified root-mean-square value corresponding to the output voltage U’ a0 of the bridge where the detection coil 1 is located is U a t1( x ), and the time variable of the amplified root-mean-square value corresponding to the output voltage U’ t of the bridge where the detection coil 2 is located is b0 t2( U b ). Fourier transforms are performed on the two detection signals y t1( t ) and x t2( t ) that change with time, and the frequency-domain signals are obtained: y t2( t ) to obtain the frequency-domain signals: X(f)= ∫ ∞ -∞ x(t)e -j2πft dt Y(f)= ∫ ∞ -∞ y(t)e -j2πft dt Among them, X(f) and Y(f) respectively represent the frequency-domain signals corresponding to two detection signals, f represents the frequency variable; t represents the time variable; e represents the natural constant, the base of the complex exponential, which is used to construct the complex sine basis function; j represents the unit imaginary number (j² = -1), which makes the basis function a complex number, so that the transformation result can represent the amplitude and phase; Then, the power spectral density is calculated for the frequency-domain signals X(f) and Y(f) according to the following formula to obtain the power spectral density, which is used to describe the energy distribution of the two signals at different frequencies, and is respectively expressed as: S xx (f) = lim T→∞ ((|X T (f)| 2 ) / T) S yy (f) = lim T→∞ ((|Y T (f)| 2 ) / T) Among them, S xx (f) and S yy (f) respectively represent the power spectral densities corresponding to the two detection signals, X T (f) and Y T (f) respectively represent the frequency-domain signals corresponding to the two detection signals within the time period T, T represents the duration of the time period, and lim represents the "limit" operation; Next, the cross-spectral density between the two detection signals is calculated simultaneously according to the frequency-domain signals X(f) and Y(f): S xy (f) = lim T→∞ ((X T (f) • Y * T (f)) / T) Among them, S xy (f) represents the cross-spectral density between the two detection signals, Y * T (f) represents the complex conjugate of Y T (f), and * represents the complex conjugate calculation; After obtaining the power spectral densities of the two detection signals respectively and the cross-spectral density between the two detection signals, the coherence function of the correlation between the two detection signals at the frequency f is calculated according to the power spectral densities of the two detection signals respectively and the cross-spectral density between the two detection signals. The coherence function is used to represent the correlation between the two signals, and the value of the coherence function is between -1 and 1: C xy (f) = |S xy (f)| 2 / (Sxx (f) • S yy (f)) Among them, C xy (f) represents the coherence parameter between two detection signals; Then make a judgment: When C xy (f) = 1 or close to it, it means that the two detection signals are completely correlated; When C xy (f) = 0 or close to it, it means that the two detection signals are completely uncorrelated; When C xy (f) = -1 or close to it, it means that the two detection signals are negatively correlated.

[0043] The coherence function C xy (f) the closer it is to 1, the higher the correlation between the two signals, and the closer it is to 0, the lower the correlation between the two signals.

[0044] According to x ( t ) and y ( t ) the similarity of the two detection signals, shift the lag signal y ( t ) forward by a time shift amount τ on the time axis to obtain a new signal y ( t + τ ), and continuously calculate the coherence function x ( t ) and y ( t + τ ) between the two signals using the above coherence analysis method. When the value of the coherence function of the two signals is closest to 1, the correlation between the two signals is the highest. At this time, the corresponding time shift amount C xy is τ the time delay between x ( t ) and y ( t ). The delay time between the two signals τ is the time required for the pulp inside the pipeline to flow from the previous detection coil to the next detection coil. Divide the delay time τ by the distance between the two detection coils to calculate the flow rate of the pulp. Then multiply the flow rate by the cross-sectional area of the pipeline to obtain the flow rate of the iron concentrate pulp.

[0045] The present invention first proposes to detect the flow rate of iron concentrate pulp by using the change of inductance value, and can simultaneously detect the flow rate and iron content information of iron concentrate pulp during pipeline transportation, realizing real-time detection during the transportation process of iron concentrate.

[0046] In specific implementation, by measuring the distance between two detection coils 1 and 2, and combining the time delay and distance, the flow velocity of the iron concentrate pulp 3 in the transportation pipeline 4 is obtained, and then multiplied by the cross-sectional area of the transportation pipeline 4 to obtain the volume flow rate of the iron concentrate pulp 3 flowing in the transportation pipeline 4; meanwhile, the detected signals collected U a or U b The magnitude is determined by the amount of ferromagnetic substances contained in the iron concentrate pulp. According to the relationship between the detected signal U a or U b and the iron content of the iron concentrate, the iron content in the iron concentrate pulp at the current moment can be obtained. The relationship between the detected signal U a or U b and the iron content of the iron concentrate needs to be calibrated offline, and then the calibration result is stored in the computer. When actually measured, when the detected signal U a or U b is obtained, the iron content level can be obtained according to the calibrated relationship.

[0047] Figure 4 are two detected signal U a and U b Data graphs changing with time. It can be seen that the waveforms of these two signals are similar and there is a certain time delay. The time delay between these two signals can be calculated by using the coherent analysis processing method τ , thereby calculating the flow velocity and flow rate; at the same time, by calculating the average value of the signal amplitude to judge the amount of iron content in the iron concentrate pulp, the larger the value of the detected signal U a or U b , it indicates that there are more ferromagnetic substances inside the detection coil, that is, the inductance value of the coil is larger and the iron content of the pulp is higher.

[0048] During on-site measurement, the flow rate and iron content detection methods of the aforementioned iron concentrate pulp are used, and the two detected signals U a and U bIt is sent to the remote PC host computer by wireless communication. The remote PC host computer processes the received data and performs a series of software operations such as saving, data table display, curve display, real-time flow rate calculation, and real-time iron content concentration calculation.

[0049] The above specific embodiments are used to explain the present invention rather than limit the present invention. Any modification and change made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

[0050] The above are only the preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made according to the structure, characteristics, and principles described in the scope of the present invention patent application are included in the scope of the present invention patent application.

Claims

1. A method for measuring the flow rate and iron content of iron concentrate slurry, characterized in that: Two detection coils (1, 2) with the same parameters are placed on a transport pipe (4) of an iron ore concentrate slurry (3) at a distance from each other, and the two detection coils (1, 2) are connected to a detection module (6). The detection module (6) is used to collect two similar and time-delayed detection signals of the two detection coils (1, 2) when the iron ore concentrate slurry (3) flows through the two detection signals, and the flow rate and iron content are measured and detected by using the property of the iron ore concentrate slurry (3) containing ferromagnetic substances.

2. The flow rate and iron content measurement method of an iron concentrate pulp according to claim 1, characterized in that: The method comprises: The time delay between two detection signals is calculated by using a coherent analysis processing method; At the same time, by measuring the distance between the two detection coils (1, 2), the flow rate of the iron ore concentrate slurry (3) in the transport pipeline (4) is obtained by combining the time delay and the distance, and then the volume flow rate of the iron ore concentrate slurry (3) in the transport pipeline (4) is obtained according to the cross-sectional area of the transport pipeline (4); At the same time, the iron content in the iron concentrate slurry is obtained by processing according to the amplitude of the detection signal.

3. A method for measuring the flow rate and iron content of iron concentrate pulp according to claim 1, characterized in that: The coherent analysis processing method of the method is specifically as follows: The output voltage U’ of the bridge where one of the detection coils (1) is located a0 The corresponding amplified effective value U a The time variable of which is x ( t ) The output voltage U’ of the bridge where the other detection coil (2) is located b0 The corresponding amplified effective value U b The time variable of which is y ( t ) For the two detection signals changing with time x ( t ) and y ( t ) perform Fourier transform to obtain the frequency-domain signals X(f) and Y(f); Then, the power spectrum density is calculated for the frequency domain signals X(f) and Y(f) according to the following formula to obtain the power spectrum density, which are expressed as: S xx (f)=lim T→∞ ((|X T (f)| 2 ) / T) S yy (f)=lim T→∞ ((|Y T (f)| 2 ) / T) Among them, S xx (f) and S yy (f) respectively represent the power spectral densities corresponding to two detection signals, X T (f) and Y T (f) respectively represent the frequency-domain signals corresponding to two detection signals within the T time period, T represents the duration of the time period, lim represents the limit operation; f represents the frequency variable; Next, the cross-spectral density between the two detection signals is calculated based on the frequency domain signals X(f) and Y(f) at the same time: S xy (f)=lim T→∞ ((X T (f)•Y * T (f)) / T) Among them, S xy (f) represents the cross-spectral density between two detection signals, Y * T (f) represents the complex conjugate of Y T (f), and * represents the complex conjugate calculation; The coherence function of the correlation between the two detection signals at frequency f is calculated based on the power spectral density of each of the two detection signals and the cross-spectral density between the two detection signals: C xy (f)= |S xy (f)| 2 / ( S xx (f)•S yy (f)) Among them, C xy (f) represents the coherence parameter between two detection signals; Finally, the two detection signals are correlated according to the coherence function, and the time delay between the two detection signals is calculated.

4. A flow rate and iron content measurement system for an iron ore concentrate pulp for implementing the method according to any one of claims 1-3, characterized in that: It includes an on-site measuring device and a remote measuring instrument, which are connected via wireless transmission communication, including: The on-site measuring device mainly comprises two identical detection coils (1, 2) which are sleeved on a transport pipeline (4) and arranged at intervals, and a detection module (6) for collecting coil signals, wherein the detection coils (1, 2) and the detection module (6) are electrically connected; the detection module (6) for collecting coil signals mainly comprises a module housing and a hardware circuit board in the module housing, wherein the hardware circuit board is connected to the detection coils (1, 2), wherein an NRF wireless transmission module (5) is additionally installed on the hardware circuit board for transmitting data to a remote measuring instrument; the remote measuring instrument mainly comprises an NRF wireless receiving module, a remote receiving device (7) and a host computer (8); the remote receiving device (7) has an NRF wireless receiving module built in, the NRF wireless receiving module and the NRF wireless transmission module (5) are communicatively connected, and the remote receiving device (7) is connected to the host computer (8); the transport pipeline (4) is used for transporting iron ore concentrate slurry (3), wherein the iron ore concentrate slurry contains ferromagnetic substances.

5. A measurement system for the flow rate and iron content of iron concentrate pulp according to claim 4, characterized in that, In the detection module (6) for collecting coil signals, the hardware circuit board has a built-in MCU and a bridge detection circuit, and the two detection coils (1, 2) are respectively connected to the bridge detection circuit on the hardware circuit board.

6. The measuring system for the flow rate and iron content of iron concentrate pulp according to claim 5, characterized in that, In the measurement system, first, the MCU is used to control the direct digital frequency synthesis technology (DDS) to generate a sinusoidal AC signal. After isolating the DC component of the sinusoidal AC signal, the high-order harmonics are filtered out by an RC filter. Then, a power amplifier is used to amplify the sinusoidal AC signal to obtain an excitation signal. The excitation signal is used to excite the bridge detection circuits where the two detection coils (1, 2) are located, and two sets of differential signals U’ a0 and U’ b0 ; Then, an instrumentation amplifier is used to perform differential mode amplification on the two sets of differential signals respectively. After filtering out the high-order harmonics and then performing gain amplification, an effective value conversion circuit is used to convert them into DC signals, and finally they are transmitted back to the MCU for ADC sampling processing, and finally two sets of detected signals U a and U b are obtained. The two sets of detected signals obtained are used for data transmission to a remote measuring instrument.

7. The measuring system for the flow rate and iron content of iron concentrate pulp according to claim 4, characterized in that It includes two said bridge detection circuits, corresponding to two detection coils (1, 2) respectively; the two detection coils (1, 2) on the transportation pipeline (4) are respectively connected to two identical bridge detection circuits.

8. A measuring system for the flow rate and iron content of iron concentrate pulp according to claim 7, characterized in that Each group of bridge detection circuits mainly consists of a fixed resistor (11 / 12), a variable resistor (13 / 14), and a balance coil (9 / 10). The detection coil (1 / 2) and the fixed resistor (11 / 12) are connected in series and then paralleled on the excitation signal U’0 to form one arm of the bridge. The balance coil (9 / 10) and the variable resistor (13 / 14) are connected in series and then paralleled on the excitation signal U’0 to form another arm of the bridge. The lead-out end between the detection coil (1 / 2) and the fixed resistor (11 / 12) and the lead-out end between the balance coil (9 / 10) and the variable resistor (13 / 14) form a differential signal output end.

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