Chemical Engineering Plant Design

Lecture 07 Recycle Streams and more in UniSim

Instructor: David Courtemanche

CE 408

Recycle Streams• Example 1 (note set “Linear Equations” posted on the Lecture 1 notes column):

• Flow sheet shows 1 minute basis

• A refers to n-octane and B refers to i-octane

• Feed is 120 mol of pure A

• Reactor yields 40% conversion for reaction A -> B

• Distillation produces top and bottom products that are 95% pure

• B is lighter (more volatile) than A

• Determine all of the unknown mole numbers indicated with question marks

• How many moles of product (95 mol%B, 5 mol % A) exit per mole of feed?

• Reactors in UniSim generate both a liquid and vapor stream – set vapor stream to 0 flow rate• This simulation uses a short cut distillation, could have used a splitter

• We are doing mass balances and are not concerned with number of stages or reflux ratio, etc