Flow measurement at high viscosities

Paul Boughton

A Swiss chemical company has installed Krohne Optimass Coriolis mass flowmeters for batching various media into a fluid mixer.

In the past the company dosed the reactants one after the other using a weighing cell in the mixer. Now it is possible to feed multiple educt at the same time through ring pipelines to the mixer.

The new process saves time and eliminates unnecessary measuring errors. For the chemical company there are numerous other advantages in using the Optimass flowmeter. The straight tube construction means that the instrument is not influenced by the very high viscosity levels found in this particular application.

The straight tube design also means that there are no pressure losses. The measurement accuracy of the flowmeter is considerably below 1 per cent. Alongside this mass flowmeter the chemical company has also installed electromagnetic flowmeters manufactured by Krohne.

Krohne chose the single straight tube layout for its Coriolis flowmeters some time ago since this design feature offers considerable advantages over mass flowmeters with curved or twin tube layouts.

Curved-tube, ring-tube and twin-tube layouts with flow dividers have proved to be unreliable in many applications where Coriolis flowmeters are specified. In twin-tube instruments, viscous, non-Newton, shear sensitive media and fluids containing solids can cause high pressure losses. Abrasive media wear down flow dividers and pipe bends.

Palm oil, cellulose and other materials containing fibre can accumulate in the flow divider and cause blockages.

The principle advantages of the straight tube design are: lower pressure losses; less abrasion wear; qualified for high flow volumes; wide measuring range; no blockage risk. Straight-tube meters are also easy to clean, self draining and suitable for measuring high-viscosity media. These are just some of the advantages of a short measuring tube with a large inner diameter.

For more information, visit www.krohne.de


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