Reactor sizing (CSTR & PFR) worksheet with answers

Free printable Reactor sizing (CSTR & PFR) worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
τ = ?k = 0.08 min⁻¹X = 75%

A first-order liquid-phase reaction with k = 0.08 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 75% conversion?

k = 0.08 min⁻¹X = 75%
τ = min
2.Easy
τ = ?k = 0.25 min⁻¹X = 50%

A first-order liquid-phase reaction with k = 0.25 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 50% conversion?

k = 0.25 min⁻¹X = 50%
τ = min
3.Medium
QX = 75%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 75% conversion. How many times larger must a CSTR be than a PFR for the same feed rate, rate constant and conversion? Find the ratio VCSTR/VPFR.

X = 75%first order, same k and Q
VCSTR/VPFR =
4.Medium
Q = 10 L/minX = 75%V = ?, k = 0.4 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.4 min⁻¹ is carried out in a plug-flow reactor (PFR) fed at 10 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 75% conversion of A.

Q = 10 L/mink = 0.4 min⁻¹X = 75%
V = L
5.Hard
Q = 10 L/minX = ?V = 150 L

A first-order liquid-phase reaction (k = 0.08 min⁻¹) runs in a 150 L plug-flow reactor (PFR) fed at 10 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 150 LQ = 10 L/mink = 0.08 min⁻¹
X = %
6.Hard
V = 50 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.4 min⁻¹) runs in a 50 L CSTR fed at 20 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 50 LQ = 20 L/mink = 0.4 min⁻¹
X = %

Answer key

  1. 1. τ = 37.5 min
  2. 2. τ = 4 min
  3. 3. VCSTR/VPFR = 2.164
  4. 4. V = 34.66 L
  5. 5. X = 69.88 %
  6. 6. X = 50 %

Full step-by-step solutions: practise this topic on examproblems.com.