Can anyone help me on determining the flow rate of argon?
Can anyone help me on determining the flow rate of argon?
(OP)
I am an intern at a steel mill. I very new to this, so bear with me. I currently have a project to size a flowmeter. I know the pressure upstream is around 200psig, this is coming from and Airliquide vessel outside the plant. Down stream we have a pressure regulator and it is regulated down to 80 psig. The headlosses for the system will take forever to determine. The temperature leaving the vessel is -20 degrees F and I am not sure what the temp is at the regulator. Please any help would be greatly appreciated.





RE: Can anyone help me on determining the flow rate of argon?
Heat gain/loss from piping to 80 psig regulator depends on flow rate, ambient temp, insulation, etc.
Look at http://webbook.nist.gov/chemistry/fluid/ for argon thermo physical properties.
I assume you want the temp of gas downstream of the 80 psig regulator.
Determine the process, look up the thermo physical properties.
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
You will also need to determine how accurate you need the flowrate measurement. A rough flowrate can be determined from a simple orifice plate, for +/- 0.5% you'll need a proper flow meter of some type of which there are several types to chose from, a meter tube with a machined orifice fitting or a turbine meter, or you could use a coriolis meter. You should have a straight place about equal to 20 x the pipe diameter to install a proper metering device.
You may be able to get an idea of the average flowrates by finding out how many times they are filling the tank and divide by the hours of operation, then apply some "factors".
If you still can't estimate the hi and lo flow rates, make a rough estimate of the lengths of pipe of various pipe diameters going from the vessel to the regulator, measure the temp at the tank and regulator and repost the answer here, or send me an e-mail if you like.
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RE: Can anyone help me on determining the flow rate of argon?
Good luck,
Latexman
RE: Can anyone help me on determining the flow rate of argon?
How often do is your argon delivered and in what quantity?
Divide the volume of delivered product by the number of minutes/hours between deliveries for a guesstimate.
Modify that by whether the argon is used continuously, like a continuous bleed into an atmosphere furnace, or unevenly in batches.
I've had similar situations, where the flow rates were total unknowns.
What I did was install a set of orifice flange unions, and a valved bypass on the straightest run of pipe I could find. I got a multivariable DP transmitter which takes a temperature reading from an RTD in addition to knowing the DP and static AP upstream of the orifice (I use Honeywell SMV, Rosemount makes one, too.) Rather than install a
thermowell and RTD for just a flowrate test, I configure the meter for a fixed gas temperature and buy 3 orifice plates sized to beta 0.75, 0.5 & 0.3 for the pipe diameter at the working pressure of the line.
Then I'd install the 0.75 plate and check flow rate. If the flow was down in the noise region, I'd go to bypass, swap to the 0.5 plate, and see what it looked like. If low on the 0.5 plate, I go to 0.3.
My assumption (not always valid) is that someone sized the pipe to maintain some reasonable flow rate, so I have a fair chance of hitting a readable flow somewhere over a range of 0.3 - 0.75 beta for a given pipe size.
I've done this 4 times so far and it's worked OK 3 times. The one time it didn't the flow rate was pitifully small for a 2" line, so I rigged a section of pipe with 3/4" line and got a reasonable flow rate from the 3/4" line.
I don't leave the multivariable in the line because it's a test tool. It's been replaced with 3 different flow meters: a rotameter, a vortex meter and a turbine meter, depending on service, but each of those flowmeters needs a flow range to be sized correctly.
Clamp-on ultrasonics might now be useable on gases, but when I did my projects, I couldn't hire anyone to measure gas flows with clamp-ons. Technology has likely changed over 5 years.
Dan
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
StoneCold
RE: Can anyone help me on determining the flow rate of argon?
Without getting heavy handed, you can make the assumption that the flow is isentalphic and not compressed. It has been correctly pointed out from Zapster's comment on isenthalpic flow that in the absence of throttling, heat loss is neglegable. Other assumptions are that the pipeline is perfectly level (no potential gradient), frictional losses are low (ideal fluid), efficient exit condition (unity for velocity coefficient) and isentropic flow (reversable). Then:
P1/rho1 + 1/2 v1^2 = P2/rho2 + 1/2 v2^2
set v1 = 0 (vessel very much larger than pipeline; this means the surface drop is small compared to fluid exiting the pipeline) and we would get the velocity of the fluid through the pipeline as:
v2 = sqrt(2[P1-P2]/rho) rho=fluid density
This is the Bernoulli Equation under all the stated assumptions, thus giving us stream velocity. Since the area of the pipeline bore is A=1/4(ID^2) then the volumetric flow of your stream is:
V' = v2 X A Volumetric Flow Rate
You have enough information to get stream velocity, but failed to state pipeline size and schedule. I cannot compute a final, approximate answer.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Can anyone help me on determining the flow rate of argon?
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Can anyone help me on determining the flow rate of argon?
I'd agree with the folks saying you should check your delivary records, but there's an even better way to get more accurate and time dependant data. You could chart the tank liquid level directly. Most, if not all of your industrial gas companies use something called "telemetry". What happens is there's an electronic box attached to the dP guage that's used to determine tank quantity. That box takes readings every 15 minuts or every few hours, depending on how it's hooked up. It then stores a large number of data points, on the order of thousands, and then when it is programmed to, it phone calls the industrial gas supplier and downloads that information to a database.
I'd suggest you ask your industrial gas provider for that information in EXCEL format and then you can plot the data over any period of time. It should be as easy as them pulling it down from their database and emailing it to you. They should also be able to correlate for you the liquid contents versus dP if they don't already have that in the database. Also, if the data they have is not taken in small enough time increments for what you need, you could ask them to set the telemetry to almost any time period you want and have them send you that data over any time interval. You could for example, ask them to have the telemetry record a data point as little as every 15 seconds. Just tell them what you want and they should be able to pull it down from a database or create a special one for you.
Anyway, talk to your industrial gas salesman for this type of information. He should be glad to send it to you, and if he doesn't, tell us what company it is you get the Argon from and I suspect someone here could "help you out" so to speak.
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
p1+rho*v1^2/2=p2+rho*v2^2/2
let v2 be negligible
p1=80psi
p2=0
Solving for v1 gives me p2-p1=-80psi
Can I just take the absolute value? To solve for v1 I would need a positive number under the square root. However, I end up with a negative number under the square. Please can anyone tell this is feasible?
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
P1*V1/T1=P2*V2/T2
(180+14.7)psia*24000scfh=(80+14.7)psia*V2 (neglect temperature change)
I end up with 900 scfm
Tell me, is this is a sufficient enough answer to size my flow meter?
Also, I am using scfm, do I need to convert to acfm to size my flow meter?
When converting to acfm, do you have to take into account that the fluid is argon?
Please any help will be greatly appreciated.
RE: Can anyone help me on determining the flow rate of argon?
2. The temperature change is 90 degrees, I wouldn't neglect that, not to mention phase change at some point.
3. Assuming the 24000 scfh is only accurate if both circuits after the "T" have equivalent losses.
4. With your bournoulli equation above, you need to solve for v2, v1 is the tank velocity which is assumed 0. That equation only applies if the mass flow rate at both points 1 and 2 are equal which, if I understand correctly, is not the case.
RE: Can anyone help me on determining the flow rate of argon?
Bernoulli across the orifice,
(note i left out the density variable on purpose)
1. If its gas before the meter and gas after the meter and the meter only loses 10-20 psi with no temperature change across the meter, yes I would assume an ideal gas to size the meter.
2. The temperature changed is 90 degrees from where? If it doesn't change 90 degrees across the meter its not relavent.
3. Why not assume flow can be controlled to be equal?
4. V1 is the flow upstream, V2 and downstream of the meter, V1 = V2 (assuming upstream and downstream piping is the same diameter). What is missing is the head loss of the flow across the orifice.
H1 + V1^2 + P1- Hlo = H2 + V2^2 + P2
assume pressure loss is 10-20 psi, T1 = T2, ideal gas
Same pipe diameter upstream and downstream, V1 = V2
Estimate orifice diameter first using ideal gas
for small pressure drop rho1 = rho2
Assume elevation upstream = elevation downstream
H1 = H2
V1^2 + P1- Hlo= V2^2 + P2
V1 = V2
P1 - Hlo = P2
=====================================================
Lee,
To estimate size the meter (an orifice plate with dP)
Use Bernoulli upstream of orifice and through (inside) the orifice
V1 = velocity upstream
V2 = velocity through orifice
H1 = H2
rho1 = rho2, small pressure drop
T1 = T2
H1+V1^2 + P1= H2 + V2^2 + P2
V1^2 + P1= V2^2 + P2
P1-P2 = V2^2-V1^2
then downstream
P2 - P3 = V3^2 - V2 + orifice flow recovery factor * (P2-P3)
iterate until you only have a small pressure drop
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RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
I believe it is a gas supply. It is supplied from a 6050 gallon vessel, which then flow through a vaporizer.
Big Inch
I dont believe I have access to an oriface plate. Unless I am not understanding something, are you referring to bernoulli's equation or is that the actual equation?
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
"I believe it is a gas supply. It is supplied from a 6050 gallon vessel, which then flow through a vaporizer."
If is flows through a vaporizor, then the tank must contain a liquid.
RE: Can anyone help me on determining the flow rate of argon?
Yes it does contain liquid in the vessel. Are you saying that I could have a two phase mixture on my hands. If pressure and temperature are small and the height doesn't change then, along a stream line it is constant. I still dont know what the velocity upstream or downstream. All I have is:
Outside (at the vessel)
Pressure after the vaporizer: 180 psig
Flow rate at the regulator: 24000 scfm(assumed from 48000/2)
Temp leaving vaporizer: -20 degrees below ambient
Inside (near the purging system)
Pressure regulated down to: 80 psig
Temp( Assuming Ambient): 70 F
Vessel Vaporizer Inside
_____ _ _ _
[ ] || || || (+100ft of piping)
[ ] || || || (elevation change of 15ft)
[ ] ||_||_|| (numerous elbows)
[___ ]---| |---0-----/ /-------0------= exit
P=180psig P=80psig
T=70F T=70F
Q=24000scfh Q=?
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
Try this:
Point 1:
P_1 = 180 psig T_1 = 70 F z_1 = 15 ft
Point 2:
P_2 = 80 psig T_2 = -20 F z_2 = 0 ft
For conservation of mass, m_dot_1 = m_dot_2; therefore, rho_1*A_1*v_1 = rho_2*A_2*v_2
Assuming A_1 = A_2, then v_1 = v_2*(rho_2/rho_1)
Plug everything into bournoulli:
P_1 + rho_1*{[v_2*(rho_2/rho_1)]^2}/2 + rho_1*g*z_1 = P_2 + rho_2*(v_2^2}/2
Look up or calculate the values for the densities and solve for v_2. Just be careful with units.
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
Thank you very much. Please excuse my ignorance and lack of experience.
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
Everything is always acfm, acfm acfm, unless you're writing up a report or selling the stuff. Then its acfm converted to scfm at the sales contract custody transfer conditions.
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RE: Can anyone help me on determining the flow rate of argon?
never assume anything?
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
you are an insult to injury
RE: Can anyone help me on determining the flow rate of argon?
correction :you add insult to injury
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
Convert 24000 scf/hr (scf @ 60oF (288.7 K, 14.73 psia) to cf/hr at at 70oF (294.3 K) and 80 psig (94.7 psia):
= (294.3/288.7) x (14.73/94.73) x 24000
= 3804 cf/hr at 70oF (294.3 K) and 80 psig (94.7 psia).
= 1.0567 cf/sec.
A 1" Sch 40 pipe has inside cross-section π(1.049)2/4 = 0.864 sq. inches = 0.006002 sq. ft.
Hence, linear flow rate
= 1.0567(cf/sec)/0.006002 sq. ft
= 176 ft/sec
RE: Can anyone help me on determining the flow rate of argon?
P1=(180+14.7)psia
T1=(70+460)R
Z=0
P2=(80+14.7)
T2=(70+460)R
Z2=15 ft
I got the density for the different pressures. Then, like insult said, used convervation of mass to be able to solve for V2.
P1+rho1*(rho2/rho1*V2)^2/2=P2+rho2*V2^2/2+rho2*g*Z2
I also used mathcad to check my calculations. I went through the calcualation several times. I dont see anything wrong, but I could be wrong.
RE: Can anyone help me on determining the flow rate of argon?
What is downstream of the 80 psig regulator??
*OK if 80 psig was measured with the regulator valve fully open, with max usage downstream.
RE: Can anyone help me on determining the flow rate of argon?
Is the pipe the same dimension at the 180 and 80 psi? If not, the bournoulli simplification won't be right. Also, I just realized that I omitted the head loss term in that equation so don't forget about that. Even without that term though, I don't think it should produce such a high velocity.
RE: Can anyone help me on determining the flow rate of argon?
P1=(80+14.7)psia
T1=(70+460)R
P2=14.7psia
T2=(70+460)R
Here, I just assumed A1=A2. Then let V2=(rho1/rho2*V1). I end up with 452 ft/s for V1.
RE: Can anyone help me on determining the flow rate of argon?
If you're trying to determine mass flow from the available information, you're not going to get there. You don't have enough info. Pressure drop and frictional flow calculations are nicely summarized in the Crane Paper #410 and many other references, but Bernoulli's doesn't work for frictional flow, it is only a conservation of energy equation.
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
This thread is getting too long and you still don't have the answer you need.
If you want to try to contact me directly, go to my webspace page, profiles tab and get my e-mail address. Send me a e-mail and I'll help you finish with this thing.
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RE: Can anyone help me on determining the flow rate of argon?
That's the point, the calculations above don't include head loss due to flow. The point is that you can't determine flow or pressure drop without considering frictional flow. Besides which, trying to determine flow rate from pressure drop in a pipeline is fraught with inaccuracies.
PS: How long does a thread need to be before it is "too long"?
RE: Can anyone help me on determining the flow rate of argon?
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RE: Can anyone help me on determining the flow rate of argon?
RE: Can anyone help me on determining the flow rate of argon?
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