Oil and Water Interface Measurement


Thread Starter

Robert Chiou

Per my understanding, there are many technologies, dielectrical, capacitance, microwave, electrimagnetic wave and so on, could be use for the oil and water measurement. What is the difference between the above technologies?
I can't help you with this comparison because the range of devices and technologies is very wide and increasing. The first discriminator is the
expected % of oil in water. Below 3% you may consider turbidity meters. Above 3% density measurement by vibrating tube or fork is a recognised industry standard and should not be neglected, particularly as you should be
able to get good reliable references from end users; what the industry considers as a standard may be more comfortable than some emerging
technologies unless there are special circumstances to consider for the control of oil/water separators in hydrocarbon industry.
There are a limited number of technologies which are successful as dedicated density transducers in the hydrocarbon industry and at least one coriolis mass flow meter manufacturer now appears to have density measurement to the required standard for this application. Density is a well established technique so you should also get very good and reliable information on all the critical parameters such as line density measurement accuracy or resolution and the robustness of the measurement (suseptability to calibration drift) as well as other factors such as long term servicability, maintenance etc. Also look for the effects of coating, waxing, entrained solids such as sand and entrained gases if present.
Viscosity is a desireable measurement because of its very high sensitivity to change in process conditions. Viscosity is far less commonly used because of the previous problems of good process viscosity measurement but advances with the technologies and methodology mean that viscosity is now a viable option in tank and pipe. Again, seek good references from users as to the service and maintenance, accuracy etc. Visit www.solartron.com ; http://www.peek-measurement.com/density.html or http://www.frco.com/micromotion/ for examples of dedicated density measurement, density measurement from mass flow meters and viscosity
measurement. I suggest that apart from such as ASTM STandards and from publications from
ISA (including their instrument handbooks). You may be best advised to collect data from manufacturers and compare to be sure of current
advantages/benefits and ask them for references from users in industry and be sure to follow up these references. In many cases, because of the long established nature of the measurement, you may find end users in the oil industry more informed than manuafacturers.

Willem de Jong

The meaurement of the speed of sound is well suitable for measuring oil concentrations. We have the MP-130 sensor, which can be inserted in a tank. The sound velocity of oil is quite different than water (depending on temerpature also). The Rhosonics website gives some examples of sensors and explains the technique. www.rhosonics.nl Willem de Jong