Question

A stream of carbon dioxide (CO2) at 120 F and 100 psig is fed to a process at a rate of 100 ft3/h.
i. Assuming ideal gas behavior, calculate the density (lbm/ft3) and the mass flow rate of CO2 (lbm/min).
ii. Is the ideal gas equation of state a good approximation for the given conditions.

Answer 1

i) feed rate = 100 ft³/h

100 ft³ = 2831.68 liter thus feed rate = 2831.68 L/h

first calculate mole of CO₂

Use ideal gas equation for calculation of mole of gas

Ideal gas equation

PV = nRT             where, P = atm pressure= 100psig = 6.8046 atm,

V = volume in Liter = 2831.68 L

n = number of mole = ?

R = 0.08205L atm mol^-1 K^-1 =Proportionality constant = gas constant,

T = Temperature in K = 120F = 322.039 K

We can write ideal gas equation

n = PV/RT

Substitute the value

n = (6.80462831.68)/(0.08205322.039) = 729.22 mole

molar mass of CO₂ = 44.01 gm then 729.22 mole = 729.22 44.01 = 32093 gm = 70.75 lbm

density = mass/volume = 70.75/2831.68 = 0.024985 lbm/ft³

mass flow rate = 70.75 lbm/h = 70.75 lbm/60 miute = 1.179 lbm/min

ii) yes ideal gas equation of state a good approximation for the given conditions.

for calculation of density we require mass of gas and for calculation of mass we require mole of gas if pressure, volume and tempreture is known we can calculate mole of gas.