High-concentration viscous solid waste refers to solid-liquid two-phase wastes or by-products with high solid content, high viscosity, and fine particles that occur during industrial production and municipal sewage treatment, because of poor fluidity under normal temperature and pressure. When high-pressure pipelines are transported, they are “non-sedimentation-like homogenous dense pastes†and thus are also known as dense pastes. They include coal industry-specific slime, dewatering sludge for water supply and drainage occupations, industrial sludge for professional production, and petrochemical occupations. Oil residue, sludge, etc., touched more than twenty occupations. As far as the above-mentioned dense pastes are concerned, the more commonly used harmless and capitalized disposal methods include burning, combustion power generation, land capitalization, landfill, etc. Which kind of harmless and capitalized disposal methods are all indispensable for transportation, and the newly-developed transportation technology is pipeline transportation. No matter whether it is still transported in the laboratory by pipelines at the industrial site, the flow rate is the critical parameter, and its size The power of the pipeline was determined. The interval L between the two receiving electrodes is a known constant and B is the known magnetic field strength, so εab is a monotonous function that changes with the change of the enthalpy. The instantaneous flow Q equals the velocity Ï… and the cross-sectional area of ​​the catheter S (constant) Product, so Q=K×εab , Coal slime conductivity test principle and method Where: Ï is the resistivity; U is the voltage at the two ends of the cylinder-shaped insulation cylinder filled with slime; U0 is the voltage at both ends of the fixed resistance; A is the cross-sectional area; L is the spacing between the two electrodes. Test data and analysis The conductivity change curve in Fig. 4 indicates that as the mass concentration of coal slime increases, its conductivity gradually decreases and intersects at one point when the mass concentration is 66%; the conductivity change curve of Fig. 5 indicates that the voltage increases. There is a gradual increase in conductivity, and the following conclusions can be obtained by analyzing Figure 4 and Figure 5: 1 Figure 4 The overall curve shows a downward trend, illustrating that the conductivity decreases with the increase of the mass concentration of the slime. When the mass concentration is lower than 63 At %, the conductivity is essentially parallel to the change in mass concentration at different voltages. It is necessary to clarify the linear relationship between conductivity and mass concentration and voltage. When the mass concentration is 63% to 66%, the conductivity and mass concentration must be determined. Linear relationship, but not linearly related to the voltage, there is still a certain downward gradient; when the mass concentration is greater than 66%, the conductivity decreases significantly with its addition, but the curve is more cluttered, it is not easy to determine the interconnection, will use the weighing method Conduct corresponding verification. 2 Figure 5 The overall curve shows an upward trend, illustrating the increase in conductivity with voltage Secondly, the data of the flow rate of the hot water flow meter was converted and integrated and compared with the weighing quality to analyze the data error. The results are shown in Table 1. This article, after measuring the electrical conductivity of the slime and the measurement of the flow of the hot water flowmeter's pipeline, arrived at the following conclusion: Dojin instrument display: After-sales and warranty All products supplied by Duo Qin Instrument (Shanghai) Co., Ltd.: All products are warranted for 2 years; Provide free telephone consultation, guide installation and commissioning services; Negotiate door-to-door installation, commissioning and other issues, and only charge reasonable travel expenses; Large amount can be free to guide the installation, commissioning; Dochin Instrument (Shanghai) Co., Ltd. Main products: electromagnetic flowmeter, vortex flowmeter, turbine flowmeter, ultrasonic flowmeter, V- cone flowmeter, metal rotor flowmeter, oval gear flowmeter, ultrasonic cold heat meter and (Explosion-proof type) quantitative control system and other products, your needs and satisfaction is always our pursuit, welcome to call the communication consulting. Grid,Fiberglass Grating,Grating For Support,Fiberglass Reinforced Plastic Grating JIZHOU ZHONGYI FRP CO., LTD. , https://www.jzzhongyifrp.com
The flow test of dense paste pipeline transportation is a problem that remains to be solved. In the pipeline transportation test, weighing method is usually used to measure, but the method testing process is cumbersome. The measurement of the hot water flow meter is not due to fluid density, viscosity, temperature, Changes in pressure, electrical conductivity, and Reynolds number, no spoilers, and no cavitation at high flow rates, have been widely used in fluid flow tests throughout the year. With the development of hot water meters, conductivity measurements are now available. Liquids with lower rate thresholds are not feasible when the concentration of dense pastes is high. The reason is that there is no accurate explanation in the existing literature. The author estimates that this may be related to too low conductivity when the concentration is too high. The use of a hot water flow meter to measure the flow rate of the slime-concentrated coal slurry during pipeline transportation and compare it with the measurement results of the weighing method to obtain the threshold value of conductivity and concentration of the coal slurry during pipeline transportation, which is the flow rate of hot water in the future. The meter is used to provide basis for flow measurement in other dense paste pipelines, and it also has important guiding significance for field application.
Test principle and test process
Hot water flow meter principle
This time, we used a different concentration of coal slime to conduct a pipeline test on a hydraulic and rheological test bench equipped with a hot water flowmeter ( magnetic flowmeter , vortex flowmeter , turbine flowmeter ) (test principle is shown in Figure 1). The hot water flow meter measures the flow of the conductive fluid in the pipeline according to the principle of electromagnetic induction. Therefore, the premise of using a hot water flow meter is that the fluid to be measured needs to be conductive, and the conductivity cannot be lower than the threshold (ie, the lower limit value). The threshold of the hot water flowmeter is between (5 x 10-6)S/cm and 10-4 S/cm. If the conductivity is lower than the threshold, an error or even an error will occur. According to the principle of electromagnetic induction (Figure 2) When the conductive fluid cuts the magnetic field lines in a magnetic field with a magnetic field strength of B, an induced electromotive force occurs between the two points a and b of the linear length L. 
In the formula: K is the instrument constant. Therefore, it is only necessary to measure εab to obtain the corresponding flow rate Q. 
In a custom-made cylindrical insulation cylinder, the slime is loaded and the resistivity of the coal slurry is measured by a reference resistance method. The voltage U1 of the fixed value resistor R and the voltage of the two ends of the insulating cylinder are measured separately. The resistance of the slime in the length of pipe is obtained from formula (3), and the resistivity of the slime is obtained by substituting formula (4). Then , the conductivity of the slime is obtained by k=1 /Ï, ie, 
The four-phase electrode reference resistance method was used to measure the resistivity of coal slime. The test circuit was planned as shown in Fig. 3. The test process was as follows: 1 It was the primary measurement of the inner diameter and length of the insulating barrel. The measurement of insulation barrel was made from different viewpoints using vernier calipers. The inside diameter and length are recorded, and the average value is taken. 2 Measure the room temperature and record. 3 Take appropriate amount of slime to participate in certain water, mix well, measure the moisture content with the moisture meter, and record that the moisture content is about 32%. With a good coal slurry into the insulating cylinder, and then connected
Test circuit.4 Use a multimeter to measure the voltage of the two ends of the 500 Ψ resistor and the two ends of the insulating barrel. After the voltage is stable, read and record. 5 Separate power supply voltage and coal slurry moisture content, repeat the above test process. 
Coal slime conductivity test data and analysis
According to the data obtained from the measurements, the mass concentration of coal slime is plotted as the abscissa, and the conductivity of the corresponding mass concentration of slime is used as the ordinate to draw the connection diagram between the coal slurry conductivity and the mass concentration (Figure 4). On the abscissa, the conductivity of the slime under the corresponding voltage is the ordinate, and the voltage and conductivity diagrams are plotted (Figure 5). 
Large and increased. The comparison of conductivity with mass concentration changes, the increase and decrease is small. When the mass concentration increases from 61.38% to 63.20 %, which is an increase of 1.82%, the conductivity increases. 0.03 mS/cm, and when the mass concentration increased from 63.20 % to 66.25 %, which is an increase of 3.05 %, the conductivity was less than 0 .01 mS/cm. Below 63.20 %, the change of conductivity is significant; when the mass concentration is 66.25 %, the conductivity is a stable value of 0.033 mS/cm.
2.2 hot water flow meter test data and analysis
Mainly analyze the reproducibility of the flow rate data of the hot water flowmeter. Figure 6 shows the three mass concentrations measured by the hot water flow meter when the flow rate in the pipe is 0.1 m/s (ie, the lower limit of the delivery flow of dense paste). Separate from the real-time data curve of 73%, 69%, 63% of the slime. It can be seen from the figure that when the concentration is high, the hot water flowmeter is difficult to measure the steady flow rate value, and when the concentration is low and the slime fluidity is very good. The measurement value is more stable. Figure 7 shows the 3 test curves of the hot water flowmeter when the mass concentration is 63%. It can be seen that the repeatability is outstanding, so the measurement results are reliable. Compared with the test results of coal slurry conductivity, it can be seen that When the mass concentration is lower than 63%, the conductivity is large, and the conductivity changes at different mass concentrations. Therefore, it is estimated that when the mass concentration is lower than 63% and the conductivity is higher than 0 .035 mS/cm, the hot water flow rate The meter is applied to coal slurry pipelines for high data accuracy. 
It can be analyzed through the conformity of the total flow and the weighing data after the integral of the hot water flowmeter. If the two are in good agreement, then the online measurement data of the hot water flowmeter shows that though the air bubble may be affected, the total flow can be accurately Measurement; if there is a large difference between the two, it is clarified that the hot water flowmeter is not suitable for the measurement of high-mass concentration slime. From Table 1, it can be seen that the error of the hot water flowmeter is greater when the mass concentration is 69%, 73%. Therefore, the measurement is inaccurate; when the mass concentration is 63%, the measurement error is small, and its measurement is clarified. The comparison test is consistent with the previous repetitive analysis, clarifying the use of mass concentration and conductivity to evaluate the measurement data of the hot water flowmeter. The accuracy is certainty.
1) The conductivity value of coal slime increases with the decrease of its mass concentration, and it is more significant with the change of the mass concentration in a certain scale. And the hot water flowmeter is not suitable for measuring the flow rate of the slime pipeline with higher quality concentration. However, when the concentration is measured at a lower concentration, the repeatability is outstanding, and the measurement result is accurate and reliable. The lower the concentration, the better the measurement effect.
2) Whether the hot water flow meter can be used in the flow measurement of dense paste pipeline is related to its conductivity and concentration. The greater the conductivity is, the better the measurement effect of the hot water flow meter is. When applied to the slime, the mass concentration is obtained. The upper limit value is 63%. When the lower limit of conductivity is 0 .035 mS/cm, the hot water flowmeter can be used to measure its flow.
3) After the study of coal slime, it can be estimated that when the hot water flow meter is used for pipeline transportation of red mud, calcium carbide mud, sludge, and other dense pastes, corresponding concentration and conductivity thresholds should also be provided. Can be obtained through tests. 
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