We have a Coriolis flow meter installed in a wet natural gas, the flow meter has 2 analog outputs, 1 of them to flow measurement, and the second one is to density measurement. However, we are having problem with the density measurement, the customer is saying that the output is always fixed at a constant value? Could you help me?
Expert’s answer: Can I implement a Coriolis as a gas density meter?
The standard Coriolis solution as a gas density meter is an excellent device for flow measurement with a good level of accuracy for your application. Just keep in mind that the Coriolis flow meter works based on the natural frequency of a system.
The tubes are constantly excited at a specific resonance frequency. So, as soon as you have a difference of mass, you have a corresponding change in the resonance frequency. Finally, the flow meter will use the frequency change to calculate the density of the fluid.
When you have a gas flow measurement you won’t experience changes in the mass of the tubes because the compressibility of the gas makes up too small a mass of your flow meter. This means that you’ll have a constant density in your output. However, you can find excellent solutions for gas density measurement on the market with different principles.
For example, the vendor Micro motion has two solutions on the market, such as a gas density meter (GDM) and a specific gas meter (SGM), these devices can measure the actual density and the specific gravity of the gas flow. However, you can find other solutions. One such solution is the Nanomass from Endress+Hauser, but it comes with a lot of limitations and requirements for this kind of density.
Usually, the density meter requires a specific installation and pressure and they are installed in a bypass. So, it’s really strange that a company would sell a standard Coriolis flow meter for gas density measurement. You can find out the accuracy of liquid and slurry in the manual, but not the accuracy for gas.
My recommendation is to install a density gas measurement solution and keep your Coriolis flow meter. In the end, both devices will send you different information about your process.
Below, you have a list of density gas meters on the market:
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