Coal slurries are found in the forms of CWM (Coal Water mixture), COM (Coal Oil Mixture), Coal Solvent Mixture and Coal Methanol Mixture.
Basic requirements for slurry flowmeters are: no pocket to clog in the housing, no moving parts to wear and simple flow path to minimize pressure loss.
CWM can be easily measured by electromagnetic flowmeters.
Positive displacement meters modified to handle coal slurries have been proven succesful for COM flow measurements with good accuracy.
Coal Solvent Mixture in coal liquefaction plant is the most difficult fluid to measure because of high temperature and high pressure. A venturi with solvent purge seems to be the type available for the time being, although its accuracy is not satisfactory.
Coal Methanol Mixture may be handled by Micro Motion mass flow meter using Coriolis effect.
Other type flow maters such as ultrasonic wave and microwave have many technical problems to be solved before reaching practical stage.
