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 = 0.12 min⁻¹X = 95%

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 95% conversion?

k = 0.12 min⁻¹X = 95%
τ = min
2.Easy
V = 100 L, k = 0.1 min⁻¹Q = 50 L/minCA0​ = 2.5 mol/LCA​ = ?

A liquid-phase first-order reaction A → B (k = 0.1 min⁻¹) runs in a 100 L continuous stirred-tank reactor (CSTR). The feed enters at 50 L/min with CA0 = 2.5 mol/L. The density is constant and the reactor is at steady state. Find the outlet concentration CA.

V = 100 LQ = 50 L/mink = 0.1 min⁻¹CA0 = 2.5 mol/L
CA = mol/L
3.Medium
Q = 50 L/minX = 70%V = ?, k = 0.15 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.15 min⁻¹ is carried out in a plug-flow reactor (PFR) fed at 50 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 70% conversion of A.

Q = 50 L/mink = 0.15 min⁻¹X = 70%
V = L
4.Medium
Q = 10 L/minX = 80%V = ?, k = 0.15 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.15 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 80% conversion of A.

Q = 10 L/mink = 0.15 min⁻¹X = 80%
V = L
5.Hard
V = 500 LQ = 5 L/minX = ?

A first-order liquid-phase reaction (k = 0.25 min⁻¹) runs in a 500 L CSTR fed at 5 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 500 LQ = 5 L/mink = 0.25 min⁻¹
X = %
6.Hard
Q = 20 L/minX = ?V = 150 L

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in a 150 L plug-flow reactor (PFR) fed at 20 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 150 LQ = 20 L/mink = 0.15 min⁻¹
X = %

Answer key

  1. 1. τ = 158.3 min
  2. 2. CA = 2.083 mol/L
  3. 3. V = 401.3 L
  4. 4. V = 107.3 L
  5. 5. X = 96.15 %
  6. 6. X = 67.53 %

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