Limited time offer 20% OFF StudySoup Subscription details

Purdue - CHE 20500 - Class Notes

Created by: Phi Sigma Pi Purdue Elite Notetaker

Purdue - CHE 20500 - Class Notes

This preview shows pages 1 - 3 of a 7 page document. to view the rest of the content
background image ChE 20500 Exam 1 – Fall 2015 
 
Problem 1 
B = benzene, C
6 H 6   T = toluene, C 7 H 8   X = xylene, C 8 H 10     Points for part a (5 pts total):  
1 pt each for correct mix point, DC #1, DC #2, split point (4 pts) 
1 pt for correct symbology (y for vapor, x for liquid, 
𝒏̇ for flow).   
Part B (Degrees of Freedom Analysis Around DC #1) 
 5  
Unknowns ( 𝑛̇ 3 , 𝑛̇ 4 , 𝑦 4𝐵 , 𝑦 4𝑇 , 𝑦 4𝑥 1 pt  -3   Balances (Pick 3 of 4: X, B, T, total) 1 pt  -2  Extra Equations (90% X recovery in bottoms product #1, sum of mole fractions is 1 in 
stream 4) 2 pts  (1 for each) 
= 0 D.O.F. 
 
4 pts total for part (b) 
 
background image  
Part C (Molar Flow Rates out of DC #1) 
 
Start from the extra condition of 90% xylene recovered: 
𝑛̇ 3 𝑥 3𝑋 = 0.9𝑛̇ 2 𝑥 2𝑋   (5 pts 𝑛̇ 3 = 0.9𝑛̇ 2 𝑥 2𝑋 𝑥 3𝑋 = 𝟕𝟑. 𝟓 𝒎𝒐𝒍 𝒉 −𝟏   (1 pt)   
Then, a total mole balance on DC #1 can be written: 
𝑛̇ 2 = 𝑛̇ 3 + 𝑛̇ 4   (5 pts 𝑛̇ 4 = 𝑛̇ 2 − 𝑛̇ 3 = 𝟏𝟑𝟗. 𝟓 𝒎𝒐𝒍 𝒉 −𝟏   (1 pt)    12 pts possible for part (c) 
 
Part D (Calculation of Recycle Flow Rate, Bottoms #2 Composition) 
 
It is now necessary to calculate mole fractions in stream 4 to solve the remainder of the problem. 
 
Benzene Balance around DC #1: 
𝑛̇ 2 𝑥 2𝐵 = 𝑛̇ 4 𝑦 4𝐵   𝑦 4𝐵 = 𝑛̇ 2 𝑥 2𝐵 𝑛̇ 4 = 0.876 𝑚𝑜𝑙 𝐵/𝑚𝑜𝑙   
Xylene Balance around DC #1: 
𝑛̇ 2 𝑥 2𝑋 = 𝑛̇ 3 𝑥 3𝑋 + 𝑛̇ 4 𝑦 4𝑋   𝑦 4𝑋 = 𝑛̇ 2 𝑥 2𝑋 − 𝑛̇ 3 𝑥 3𝑋 𝑛̇ 4 = 0.053 𝑚𝑜𝑙 𝑋/𝑚𝑜𝑙   
Sum of mole fractions in stream 4 is 1: 
𝑦 4𝑇 = 1 − 𝑦 4𝑋 − 𝑦 4𝐵 = 0.071 𝑚𝑜𝑙 𝑇/𝑚𝑜𝑙   
5 pts awarded for using component balances to obtain the mole fractions of stream 4. 
 
Do a benzene balance on DC #2; remember that mole fractions in streams 6, 7, and 8 are equal: 
𝑛̇ 4 𝑦 4𝐵 = 𝑛̇ 6 𝑦 6𝐵   𝑛̇ 6 = 𝑛̇ 4 𝑦 4𝐵 𝑦 6𝐵 = 130.1 𝑚𝑜𝑙 ℎ −1    
5 pts awarded for obtaining the flowrate of stream 6. 
  
Now, perform a total mole balance at the split point: 
background image 𝑛̇ 6 = 𝑛̇ 7 + 𝑛̇ 8     𝑛̇ 8 = 𝑛̇ 6 − 𝑛̇ 7 = 𝟏𝟎𝟎. 𝟏 𝒎𝒐𝒍 𝒉 −𝟏   (2 pts)   
To calculate the mole fractions in the bottom stream, first perform a total mole balance on DC#2: 
𝑛̇ 4 = 𝑛̇ 5 + 𝑛̇ 6   𝑛̇ 5 = 𝑛̇ 4 − 𝑛̇ 6 = 9.4 𝑚𝑜𝑙 ℎ −1    
Now, perform a xylene balance on DC#2: 
𝑛̇ 4 𝑦 4𝑋 = 𝑛̇ 5 𝑥 5𝑋     𝑥 5𝑋 = 𝑛̇ 4 𝑦 4𝑋 𝑛̇ 5 = 𝟎. 𝟕𝟖𝟏 𝒎𝒐𝒍 𝑿/𝒎𝒐𝒍  (1 pt)  𝑥 5𝑇 = 1 − 𝑥 5𝑋 = 𝟎. 𝟐𝟏𝟗 𝒎𝒐𝒍 𝑻/𝒎𝒐𝒍  (2 pts)   
15 pts possible for part (d) 
 
Part E (Composition and Flow Rate of the Fresh Feed) 
 
Start with a total mole balance at the mix point: 
𝑛̇ 1 + 𝑛̇ 8 = 𝑛̇ 2   (5 pts 𝑛̇ 1 = 𝑛̇ 2 − 𝑛̇ 8 = 𝟏𝟏𝟐. 𝟗 𝒎𝒐𝒍 𝒉 −𝟏   (1 pt)   
Perform a xylene balance around the mixing point: 
𝑛̇ 1 𝑥 1𝑋 = 𝑛̇ 2 𝑥 2𝑋     𝑥 1𝑋 = 𝑛̇ 2 𝑥 2𝑋 𝑛̇ 1 = 𝟎. 𝟔𝟓 𝒎𝒐𝒍 𝑿/𝒎𝒐𝒍  (1 pt)   
Perform a benzene balance around the mixing point: 
𝑛̇ 1 𝑥 1𝐵 + 𝑛̇ 8 𝑦 8𝐵 = 𝑛̇ 2 𝑥 2𝐵     𝑥 1𝐵 = 𝑛̇ 2 𝑥 2𝐵 − 𝑛̇ 8 𝑦 8𝐵 𝑛̇ 1 = 𝟎. 𝟐𝟓 𝒎𝒐𝒍 𝑩/𝒎𝒐𝒍  (1 pt)   
Then, the sum of mole fractions is equal to 1: 
𝑥 1𝑇 = 1 − 𝑥 1𝐵 − 𝑥 1𝑋 = 𝟎. 𝟏𝟎 𝒎𝒐𝒍 𝑻/𝒎𝒐𝒍  (1 pt)   
5 pts awarded for using component mole balances to get the mole fractions. 
 
14 pts possible for part (e) 
 
 

This is the end of the preview. Please to view the rest of the content
Join more than 18,000+ college students at Purdue University who use StudySoup to get ahead
School: Purdue University
Department: Chemical Engineering
Course: Chemical Engineering Calculations
Professor: Bryan Stephen P Beaudoin
Term: Fall 2015
Tags:
Description: ChE 20500 Exam 1 – Fall 2015 Problem 1 B = benzene, C H 6 6 T = toluene, C 7 8 X = xylene, C H 8 10 Points for part a (5 pts total): 1 pt each for correct mix point, DC #1, DC #2, split point (4 pts) 1 pt for correct symbology (y for vapor, x for liquid, ???? for flow)
Uploaded: 05/09/2017
7 Pages 34 Views 27 Unlocks
  • Better Grades Guarantee
  • 24/7 Homework help
  • Notes, Study Guides, Flashcards + More!
Recommended Documents
Join StudySoup for FREE
Get Full Access to Purdue - CHE 20500 - Class Notes
Join with Email
Already have an account? Login here
×
Log in to StudySoup
Get Full Access to Purdue - CHE 20500 - Class Notes

Forgot password? Reset password here

Reset your password

I don't want to reset my password

Need help? Contact support

Need an Account? Is not associated with an account
Sign up
We're here to help

Having trouble accessing your account? Let us help you, contact support at +1(510) 944-1054 or support@studysoup.com

Got it, thanks!
Password Reset Request Sent An email has been sent to the email address associated to your account. Follow the link in the email to reset your password. If you're having trouble finding our email please check your spam folder
Got it, thanks!
Already have an Account? Is already in use
Log in
Incorrect Password The password used to log in with this account is incorrect
Try Again

Forgot password? Reset it here