Separation Process: please show steps: 2. (10 points) Suppose a saturated liquid

Question

Separation Process:

please show steps:

2. (10 points) Suppose a saturated liquid feed of a benzene (B)toluene (T) mixture (50 mol% B) to a column is to be separated into a high purity distillate that is has a mole fraction of B equal to 0.9999 with a bottoms product mole fraction of 0.10. You may take the relative volatility to be BT = 2.49 at the temperature that the column is operated. You are also given the reflux ratio to be 10.0, assuming a total condenser. Use a graphical solution up to 95 mol% B and then use the Kremser equation for the rest of the calculation 3. (10 points) Another configuration possible in distillation is that of stripping or absorption towers. In stripping towers, the feed is supplied near the top of the column. The feed is usually saturated liquid and the overhead product vapour rises to the top plate, which enters a condenser with no reflux or liquid returning to the column. The vapour is acting to remove the more volatile component from the liquid as it flows down (hence the term "stripping tower"). The bottoms product will have a high concentration of the less volatile component Again, using the benzene (B)/toluene (T) system, at a given pressure of 101.3 kPa, a liquid feed at its boiling point consisting of 70 mol% B is fed at 500 kmol/h, with the bottoms product flow rate being about 75 kmol/h and having only 10 mol% benzene and the rest toluene. The same relative volatility as that in question 2 can be assumed i) Calculate the overhead vapour flow rate and composition as well as the number of ii) What would be the number of ideal stages if the Murphree efficiency of 60% was

Explanation / Answer

2.in this question what should we calculate was not given properly

3.

a)let us rewrite the overall given data once again

liquid flow rate at inlet(L)=500

at outlet=75

say vapour flow rate(G) need to calculate and its fraction is y1 and y2

inlet concentration (sayx2)=0.7

outlet concentration (sayx1)=0.1

we have one direct formula in absorption or we can also derive by writing the operating line equation and this is given as (L/G)=[(y1-y2)/(x1-x2)]

in this question equilibrium relation is not provided

the value of y1 is 0 because the feed entered at its boiling point.

so if we have the that equilibrium relation we can solve using the above relation.

and now the number of trays can be calculated from

N+1=[log((xD/1-xD)*(1-xW/xW))]/log(relative volatility)

whre N is Number of theoritical stages

xD is molefraction of distillate (top product)

xW is molefraction of residue (bottom product)

N+1 is stages including reboiler

and this the way to find number of stages

b) murphree efficiancy=[number of ideal stages/number of real stages]

number of ideal stages=murphree efficiancy*number of real stages.

now i hope you are feeling happy to solve this question

please upvote and comment if you have any querries regarding this i will try to solve those doubts.

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