From the selection table, you can find the flowmeters used in the slurry containing particle fibers: differential pressure flowmeters include elbows, wedge-shaped tubes, electromagnetic flowmeters, Doppler ultrasonic flowmeters, vortex flowmeters, Target flowmeter, Coriolis mass flowmeter, etc. According to the usage conditions and the measurement performance of various flowmeters, electromagnetic flowmeters are the first choice for measuring slurry flow, unless the measured slurry is non-conductive or contains ferromagnetic particles, and the measurement pipeline system is not allowed to be cut off to access the flow sensor. choose another flowmeter. According to reports, many years of application experience in measuring the flow rate of coal-water slurry with a pulverized coal content of up to 65% are considered to be the best electromagnetic flowmeter.
Differential pressure flowmeters can be used to measure slurry. In addition to elbows, wedge-shaped tubes and annular tubes, the differential pressure sensor can also be used for circular orifice plates and eccentric orifice plates when the solid phase is small. Venturi tubes are also used for measurement. .
Doppler ultrasonic flowmeter can be measured without cutting off the pipe and clamping an ultrasonic transducer (probe) outside the pipe, but the measurement accuracy is not high.
Vortex flowmeter can only measure solids containing a small amount of powder, and the solid content is large or fibrous will cause noise and cannot be used.
The target flowmeter is used for liquid flow such as heavy oil or residual oil containing pulverized coal, and the strain target flowmeter is used.
The experience of Coriolis mass flowmeter applied to slurry measurement is generally suitable for its straight-tube measuring tube, but there is not much application experience.
The choice for large flow measurement of liquids in closed pipelines
The large flow mentioned here does not refer to the "relatively large flow" when the flow velocity of a certain pipe diameter is high, but the large flow of the absolute value of the flow. Since the flow velocity of the liquid transported by the pipeline has a certain range, the economical flow velocity of the low viscosity liquid is usually 1~3m/s. Therefore, the "large flow" measurement mentioned here refers to the measurement of the large pipeline flow.
Generally speaking, the flowmeter with pipe diameter below DN300 is called small and medium pipe diameter flowmeter, the one above DN300~ DN400 is called large pipe diameter flowmeter, and the one above DN1200 is called extra large pipe diameter flowmeter. Usually, the liquid flow measurement of extra-large diameter pipes is mainly water, and in addition to water, there are petroleum products. Generally, large-diameter flowmeters include differential pressure flowmeters, electromagnetic flowmeters, ultrasonic flowmeters and insertion flowmeters. There are also positive displacement flowmeters and turbine flowmeters for DN300~DN500.
1. Installation conditions
The installation conditions are mainly based on whether the measurement method can allow the pipe flow to be cut off and the operation to be suspended, whether it is allowed to drill holes on the pipe, and whether it is allowed to cut off the pipe flow to install the flow sensor.
If the flow sensor is allowed to cut off the pipe flow, electromagnetic flowmeters, ultrasonic flowmeters with measuring pipe sections, positive displacement flowmeters and turbine flowmeters can be selected.
Extrapolation transducer ultrasonic flowmeters and insertion flowmeters can be selected if drilling holes in the pipeline are allowed.
If the above requirements are not allowed, you can only choose an ultrasonic flowmeter with an external clip-on transducer.
2. Measurement accuracy requirements
For custody transfer requiring high measurement accuracy and non-conductive liquids, ultrasonic flowmeters with measuring pipe sections, multi-channel ultrasonic flowmeters, vortex flowmeters, and electromagnetic flowmeters can also be selected for conductive liquids.
For the control ratio, the differential pressure Venturi tube and the external clamping transducer ultrasonic flowmeter can be selected with lower measurement accuracy requirements. Optional insertion flowmeter with low measurement accuracy requirements.
3. Pressure loss (pumping energy cost)
The pumping energy cost of large flow measurement accounts for a considerable proportion of the flow measurement operating cost, pressure loss and (pumping energy cost) such as differential pressure Venturi, positive displacement flowmeter and turbine flow count. The smaller is the insertion flowmeter, and the one without pressure loss is the electromagnetic flowmeter.