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 = 0.3 min⁻¹X = 50%

A first-order liquid-phase reaction with k = 0.3 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 50% conversion?

k = 0.3 min⁻¹X = 50%
τ = min
2.Easy
τ = ?k = 0.12 min⁻¹X = 60%

A first-order liquid-phase reaction with k = 0.12 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 60% conversion?

k = 0.12 min⁻¹X = 60%
τ = min
3.Medium
Q = 100 L/minX = 60%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 100 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 60% conversion of A.

Q = 100 L/mink = 0.4 min⁻¹X = 60%
V = L
4.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 =
5.Hard
V = 2000 LQ = 25 L/minX = ?

A first-order liquid-phase reaction (k = 0.05 min⁻¹) runs in a 2000 L CSTR fed at 25 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 2000 LQ = 25 L/mink = 0.05 min⁻¹
X = %
6.Hard
V = 800 LV = 800 LQ = 25 L/minX = ?

A first-order liquid-phase reaction (k = 0.08 min⁻¹) runs in two equal CSTRs in series, each of 800 L. The feed rate is 25 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 800 L (×2)Q = 25 L/mink = 0.08 min⁻¹
X = %

Answer key

  1. 1. τ = 3.333 min
  2. 2. τ = 12.5 min
  3. 3. V = 229.1 L
  4. 4. VCSTR/VPFR = 2.164
  5. 5. X = 80 %
  6. 6. X = 92.11 %

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