Problem statements
Problem1
We have a stream containing 15% ethane, 20% propane, 60% i-butane and 5% n-butane at 50 F and
atmospheric pressure and a flowrate of 100 lbmole/hr. This stream is to be compressed to 50 psia and
then cooled to 32 F.The resulting vapor and liquid are to be separated as the two product streams. What
are the flow rates and compositions of these two streams?
Problem2
1 mol/sec of methane is used as fuel for fire heater. If stoichiometric reactant is fed to heater,compute
the necessary heat rate that must be supplied to ash stream .Also calculate the resulting temperture of
methane air mixture prior to combustion. Given that air and methane are available at 50 C. Air is to be
preheated to 400 C.Both are at 2 atm. Approximate the composition of air as 20/80 mixture of oxygen
and nitrogen.
Problem3
Flash Distillation A mixture of 40 mol% benzene and 60 mol% toulene is being flashed distilled at a rate of
10 mol/sec. They are at 1 atm total pressure.The liquid product should not contain more than 30 mol%
benzene. Calculate amount and composition of top and bottom product.
Problem4
In flash unit operation,chlorobenzene and water is fed at the rate of 987.5 g/s and 617.2 g/s respectively.
Pressure is maintained at 1 bar. If water is immiscible with chlorobenzene , find the temperature of feed
stream, avg. molecular weight of feed, top and bottom product. Vapor fraction for chlorobenzene is 0.5
Problem5
Compute the bubble temperature at 18 bar of following hydrocarbon mixture assuming the mixture inlet
temperature 25 C and flowrate 30 mol/sec. Given composition at 5 bar as:
methane .05
ethane .1
propane .15
i-butane .1
n-butane .2
n-pentane .4
Problem6
Compute the dew point temperature at 1.5 bar of following hydrocarbon mixture assuming the mixture
inlet temperature 25 C and flowrate 30 mol/sec.
given composition at 5 bar as:
methane .05
ethane .1
propane .15
i-butane .1
n-butane .2
n-pentane .4
Problem7
A continuous fractionating unit is to be designed to separate 8333.33 g/sec of a mixture of 40% benzene
and 60% toulene into an overhead product containing 97% benzene and bottom product containing 98%
toulene . Take reflux ratio as 3.5 .The feed is at its bubble point of 95 C and at a pressure of 1 atm.
Calculate the moles of bottom and overhead product and determine the no. of ideal stage and feed plate
position.
Problem8
A gas mixture of air 4 mol/s and hydrogen sulfide 2 mol/sec is to be absorbed by water so that 99% of H2S
is recovered from the bottom stream. Water enters the absorber in 1st tray at 298 K at 1 atm pressure
and gas feed enters plate no. 10 at same temperature and pressure.Find the molar flowrate of water to
recover 99% of H2S at bottom.