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.

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1.Easy
τ = ?k = 0.5 min⁻¹X = 85%

A first-order liquid-phase reaction with k = 0.5 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 85% conversion?

k = 0.5 min⁻¹X = 85%
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
Q = 100 L/minX = 80%V = ?, k = 0.12 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.12 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 80% conversion of A.

Q = 100 L/mink = 0.12 min⁻¹X = 80%
V = L
4.Medium
Q = 40 L/minCA0​ = 1 mol/LCA​ = ?V = 50 L, k = 0.4 min⁻¹

A liquid-phase first-order reaction A → B (k = 0.4 min⁻¹) runs in a 50 L plug-flow reactor (PFR). The feed enters at 40 L/min with CA0 = 1 mol/L. The density is constant and the reactor is at steady state. Find the outlet concentration CA.

V = 50 LQ = 40 L/mink = 0.4 min⁻¹CA0 = 1 mol/L
CA = mol/L
5.Hard
V = 200 LQ = 40 L/minX = ?

A first-order liquid-phase reaction (k = 0.05 min⁻¹) runs in a 200 L CSTR fed at 40 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 200 LQ = 40 L/mink = 0.05 min⁻¹
X = %
6.Hard
V = 500 LQ = 10 L/minX = ?

A first-order liquid-phase reaction (k = 0.08 min⁻¹) runs in a 500 L CSTR fed at 10 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 500 LQ = 10 L/mink = 0.08 min⁻¹
X = %

Answer key

  1. 1. τ = 11.33 min
  2. 2. τ = 4 min
  3. 3. V = 1341 L
  4. 4. CA = 0.6065 mol/L
  5. 5. X = 20 %
  6. 6. X = 80 %

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