rajeshkolappan40
Petroleum
please explain difference between mass flow and volume flow?
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rajeshkolappan40
Petroleum
thanks 25362
con you explain where we can measure the MASS flow & where we can measure VOLUME flow?
con you explain where we can measure the MASS flow & where we can measure VOLUME flow?
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We can almost never measure the mass flow. The Coriolis meter is advertised as a "mass flow meter", but it is not really--if you give it an accurate fluid analysis then it can infer fluid density form the vibration of the instrument. Once it has calculated a "density" it can infer a volume flow rate from the displacement of a series of tubes at right angles to each other.
With other flow meters you are determining a volume flow rate at standard conditions and using the STP conditions you can convert the indicated pressure, and temperature to a volume flow rate.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
With other flow meters you are determining a volume flow rate at standard conditions and using the STP conditions you can convert the indicated pressure, and temperature to a volume flow rate.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
Compositepro
Chemical
Coriolis meters measure both mass flow and density directly by sensing different aspects of the vibrational response of the flow tube. Density change will change the resonant frequency, while flow shifts the phase between the two ends of the flow tube.
CompositePro, that is sometimes true in a plant where the makeup of the fluid stream is tightly controlled. In field conditions where the mix of components change from moment to moment, it is not even close. The density inference is absolutely dependent on having a fixed and known fluid composition. In field conditions where water rate can change by an order of magnitude from one minute to the next the Coriolis meter density is never very close.
Those meters measure vibration and displacement and infer a density and momentum. They in no way "measure density and mass flow directly". Not even close. Just like a turbine meter infers a flow from a rotational velocity or a dP meter infers a volume flow from a pressure, temperature, and a differential pressure, Coriolis meter infer a flow from parameters that can be influenced by things other than the fluid flow in a pipe. They often do an OK job of giving you numbers that are related to the flow, sometimes they do a very good job, other times they are really expensive random number generators. Regardless of the marketing literature, they are not magical.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
Those meters measure vibration and displacement and infer a density and momentum. They in no way "measure density and mass flow directly". Not even close. Just like a turbine meter infers a flow from a rotational velocity or a dP meter infers a volume flow from a pressure, temperature, and a differential pressure, Coriolis meter infer a flow from parameters that can be influenced by things other than the fluid flow in a pipe. They often do an OK job of giving you numbers that are related to the flow, sometimes they do a very good job, other times they are really expensive random number generators. Regardless of the marketing literature, they are not magical.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
Yes, coriolis meters are not perfect, but they are not that bad either. Maybe it's that field versus plant thing. We use them in a plant environment. We always calibrated them with water, and then use them to measure liquids or gases. They usually do an excellent job. I've found their achilles heel is mixed phase flow, like gas and liquid two phase flow. As long as the flow is single phase, they are fine, but hit them with liquid and gas at the same time and they crash!
Good luck,
Latexman
Need help writing a question or understanding a reply? forum1529
Good luck,
Latexman
Need help writing a question or understanding a reply? forum1529
People keep putting them on wellsites. I had one installed 6 ft after a choke which dropped the pressure from 10,000 psig to 1,000 psig. The well made 20 MMCF/d of 1.3 BTU/SCF gas, 300 bbl/d of 40 API condensate, and 1,200 bbl/d of water ON AVERAGE. Problem was many of the constituents of the 1.3 BTU/SCF were liquid upstream of the choke and boiled off some distance downstream of the choke. There was no way to reliably determine the phase change point, but my intuition said it was farther than 6 ft. The other issue was that there was no snapshot in time that the well made 20 MMSCF/d, 300 bbl/d condensate, or 1,200 bbl/d water for more than a few nano seconds. The numbers were averages of a very broad range of values. Also, the heating value and the API changed from minute to minute. My client wanted to know why his high dollar MicroMotion was 40-80% off from his custody transfer meter and the sum of the tank volumes and run tickets.
In other words the meter only gave him meaningful numbers for those few nano seconds per month when the flow matched the averages. In a plant, you can put them on single-phase flow streams that only change density with pressure and temperature and get decent, repeatable results. But there are 50 other technologies that will do as well in that service.
Nothing does a good job with unknown and varying mixtures of fluids, but Emerson has been touting the Coriolis as just such a meter ever since they bought MicroMotion by claiming that the "measure density directly". Saying it a million times does not make it true.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
In other words the meter only gave him meaningful numbers for those few nano seconds per month when the flow matched the averages. In a plant, you can put them on single-phase flow streams that only change density with pressure and temperature and get decent, repeatable results. But there are 50 other technologies that will do as well in that service.
Nothing does a good job with unknown and varying mixtures of fluids, but Emerson has been touting the Coriolis as just such a meter ever since they bought MicroMotion by claiming that the "measure density directly". Saying it a million times does not make it true.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
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Above postings plus the followng link explain uses and limitations of mass flow meters:
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