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 = 0.4 min⁻¹X = 50%

A first-order liquid-phase reaction with k = 0.4 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 50% conversion?

k = 0.4 min⁻¹X = 50%
τ = min
2.Easy
V = ?, k = 0.08 min⁻¹Q = 10 L/minX = 70%

A first-order liquid-phase reaction A → B with k = 0.08 min⁻¹ is carried out in a continuous stirred-tank reactor (CSTR) fed at 10 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 = 10 L/mink = 0.08 min⁻¹X = 70%
V = L
3.Medium
Q = 40 L/minCA0​ = 1.5 mol/LCA​ = ?V = 1000 L, k = 0.05 min⁻¹

A liquid-phase first-order reaction A → B (k = 0.05 min⁻¹) runs in a 1000 L plug-flow reactor (PFR). The feed enters at 40 L/min with CA0 = 1.5 mol/L. The density is constant and the reactor is at steady state. Find the outlet concentration CA.

V = 1000 LQ = 40 L/mink = 0.05 min⁻¹CA0 = 1.5 mol/L
CA = mol/L
4.Medium
Q = 40 L/minX = 70%V = ?, k = 0.5 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.5 min⁻¹ is carried out in a plug-flow reactor (PFR) fed at 40 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 = 40 L/mink = 0.5 min⁻¹X = 70%
V = L
5.Hard
V = 250 LQ = 5 L/minX = ?

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in a 250 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 = 250 LQ = 5 L/mink = 0.15 min⁻¹
X = %
6.Hard
Q = 5 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 5 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 150 LQ = 5 L/mink = 0.15 min⁻¹
X = %

Answer key

  1. 1. τ = 2.5 min
  2. 2. V = 291.7 L
  3. 3. CA = 0.4298 mol/L
  4. 4. V = 96.32 L
  5. 5. X = 88.24 %
  6. 6. X = 98.89 %

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