# Data: Heat of vaporization of propane

One of the olf columns in your plant failed. You have been putting together jury-rigged system to separate propane fron n-butane. The column you have found is empty, so within reason you can put in as many stages as needed. It is equipped with a partial condenser and a total reboiler. The column is restricted to a maximum pressure of 800,0 kPa, which means that refrigerator is needed. You have a source of refrigerator, but output is limited to 6000.0 kW. Freed is a saturated liquid at 800.0 kPa that is 56.0 mol% propane. Unless stated otherwise distillate should be 99.9 mol% propane, and bottoms should be 1.0 mol% propane or less. You have more feed available that can be processed.

a) generate a y-x graph at 800.0 kPa from the DePriester chart. From the depriester chart find the boiling points of propane at 800.0 kPa (set Kp=1) and n-butane at 800.0 kPa (set K(n-b)=1). The boiling range for the complete y-x diagram lies between these two temperature. Pick a temperature between the two boiling points, find Kp and K(n-b), calculate X(n-b)=(Kp-1)/(Kp-Kb), Xp=1-X(n-b), and Y(n-b)-K(n-b)X(n-b). Doing this for five to ten temperatures generates the y-x graph.

b) if you built a system with a very large number of stages (like N greater than 100) estimate the kmol/h of 99.9mol% distillate that can be produced and kmol/h of feed processed (bottoms less or equal to 1 mol% propane).

c) Repeat part b for 90.0mol% pure propane distillate and 1% or less propane in the bottoms for a saturated liquid feed.

d) if the required purity of the bottoms stream is changed to 10.0 mol% propane, repeat part b (distillate is 99.9% mol% propane).

e) repeat part b for a 99.9 mol% pure propane distillate and 1% or less propane in the bottoms if the feed is a saturated vapor that is 56.0 mol% propane.

f) epeat part b for a 99.9 mol% pure propane distillate and 1% or less propane in the bottoms if the feed is a saturated vapor that is 66.0 mol% propane.

Data: Heat of vaporization of propane at 800 kPa is 18,800 KJ/Kmol, and for butane at 800 kPa is 22,600 KJ/Kmol