Selection of flow meters for crystallizable substances
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Dear Haihao friends! When measuring phenol (which crystallizes easily at 40°C), turbine flowmeters are currently being used; process measures are taken to keep the temperature of phenol at 60°C, but the flowmeters tend to get clogged frequently. So, what type of flowmeter would be more suitable in such a situation? Thank you!
The melting point of phenol is 40–42°C; what you can do is increase heating and improve insulation to prevent crystallization, thus avoiding blockages.
Both pipelines and turbine flowmeters are equipped with insulation jackets, but the results are not very satisfactory.
The turbine flowmeter has a relatively small blade gap; try using a target flowmeter instead.
All differential pressure types are not suitable, as crystallization affects pressure measurement. It is recommended to use an electromagnetic flowmeter. 60% of what comes out of our crystallizer is in crystal form, and we’ve never had any problems using electromagnetic flowmeters.
If the conductivity of the medium meets the requirements, an electromagnetic flowmeter can be chosen.
Phenol is an organic compound with relatively low conductivity, and it cannot be measured using an electromagnetic flowmeter.
If the measurement accuracy requirements are not high, consider using a wedge-type heat tracing and strive to make it as good as possible
The Wv series fully-jacketed vortex flow meters could be considered; they perform excellently with sulfur gas, and after being in use for 3 years, no crystalline condensate has ever occurred.
How about ultrasonic waves, with constant temperature heating?
For low flow rates, you might consider using a metal float; adding weight and insulation will suffice. It can be used continuously with no major issues – the main advantages are its low cost and ease of maintenance. Flow meters of the vortex type tend to have problems when made in China, and it’s difficult to fix them when they break down. The same goes for ultrasonic flow meters; it’s better not to consider domestic versions of these either