Dielectric density measurement
Thread Content
The customer needs a gauge for online density measurement, to detect the density while the fluid is flowing in the pipeline, thereby determining whether all the moisture from the material has been removed. The density difference between the two media is approximately 0.1 m3/cubic meter. The flow rate can be controlled to meet the requirements; are there any good instruments or methods for this?
If it’s to measure density, of course an online density meter is used; of course, it’s also possible to take samples for analysis, which in that case eliminates the need for a density meter
Using a mass flow meter, it is possible to obtain both the flow rate and density values at the same time – is there any difficulty in that?
The accuracy of the mass flow meter may not be achievable; it’s unknown whether the density difference between the two media is 0.1 kg/m3 or 0.1 t/m3. A difference that small might not be detectable.
Thank you all; the density difference is 0.1 t/m3, sorry. The customer’s usage is as follows: the material produced at the beginning contains impurities and has a higher density, while the material produced later is purer and has a lower density. The material from the beginning needs to be reused; the material that comes out once the user detects stable density is the finished product. I want to conduct an online detection now; the accuracy isn’t very high, but it’s sufficient as long as it can detect obvious differences.
The solution proposed by a company is to use a differential pressure transmitter to measure the differential pressure in a tube at a fixed height. However, it is necessary to explore whether the differential pressure remains stable under liquid flow conditions.
The precision requirement is not high; mass flow meters are somewhat expensive. One solution proposed by some companies is to use differential pressure measurement
I have worked on similar projects; back then, mass flow meters were used, which allowed for accurate measurement of flow rate without the need for highly precise density measurements, and the client was quite satisfied. I personally think the differential pressure approach isn’t well-thought out; the flow state of the medium isn’t that stable, and things like bubbles being entrained or changes in flow velocity can all cause fluctuations in the differential pressure value. Moreover, measuring the differential pressure may require the use of heat tracing or diaphragm sealing; when the temperature differences between winter and summer are large, the density of the medium or isolating fluid changes, resulting in less accurate measurements.