Calculate CO2 Flow Rate from SCFD to lb/hr

[SuperG]

Well, it's been a while sinve I've had to do one of these calculations. Does anyone know what the mass flow rate of CO2 is in lbs/hr if you have 15 MMSCFD flow rate? It's in gaseous form and somewhere near 100-150 F...thanks!

 

[pmover]

superg,
an equation is: #'s/sec = 0.884 x SG x mmscfd
assuming 14.7 psia and 60°F for std measurement. - pmover

 

[SuperG]

Ah, that's interesting. So using sg=1.53, I get 73,036 lb/hr.

Here is another, I finally realized: SCFD X rho

This gets 15 MMSCFD x 0.115 lbs/cuft x day/24 hrs equals
71,875 lbs/hr.

Thanks for the help!

 

[TD2K]

Another way is to remember that 1 lbmole occupies 379.6 scf.

Thus, 15 MMscfd = 39,515 lbmole/day or 1,646.5 lbmole/hr. CO2 = 44.01 lb/lbmole so the flow is 72,461 lb/hr.

Pretty much the same answer. You can also use the ideal gas equation PV = nRT, P is the pressure, 1 atm. V is the volume, 15 MM ft3/day (at standard conditions of course), R is the gas constant, 0.73 atm ft3/lbmole deg F and T is the temperature, 520 deg R (at standard conditions, 60F). Solve for n, the number of moles and then multiply by the molecular weight to get the mass flow.

 

[oso]

What variations in the formulas must be introduced to actually calculate mass rates at pressures/temperatures different to standards?

 

[TD2K]

I'm not sure what you are asking.

Flowrates in SCFH (or any other similar units) are at 1 atm pressure and 60 deg F (usually, there are variations in which pressure base is used, especially in the pipeline business). If you use the ideal gas law (and I can't think of any gases that I've come across that vary significantly from ideal gas behavior at one atmosphere and 60F), you will determine the number of moles per time. Multiply by the molecular weight and you have mass per time. The actual operating pressure and temperature is not used unless you want to calculate the actual volumetric flow rate.

 

[KernOily]

Guys it's just the basics:

mass rate = density * volumetric rate

Then it's just a matter of keeping your units straight using the right conversions.

Use standard density if you want mass rate at 60° and 14.7 psia. Use your actual gas conditions if you want actual mass rate. That's all there is to it.

SuperG, just curious, do you work in West Texas or Colorado? Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com

 

[saidsaz]

a side note here , in TD2K response says there are variations in pressure basis for standard conditions , i recall variations are in temperature not pressure basis, i,e either 60 F or 32 F (NORMAL Vs STANDARD )while pressure is always 14.7 psi


cheers!

 

[quark]

oso!

To check mass flow first of all you have to compensate for pressure and temperature because the error can be as high as 14%. Compressibility factor is compensated for further refining measurement of flow rate.

Regards,