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
V = 400 L, k = 0.08 min⁻¹Q = 25 L/minCA0​ = 0.5 mol/LCA​ = ?

A liquid-phase first-order reaction A → B (k = 0.08 min⁻¹) runs in a 400 L continuous stirred-tank reactor (CSTR). The feed enters at 25 L/min with CA0 = 0.5 mol/L. The density is constant and the reactor is at steady state. Find the outlet concentration CA.

V = 400 LQ = 25 L/mink = 0.08 min⁻¹CA0 = 0.5 mol/L
CA = mol/L
2.Easy
τ = ?k = 0.25 min⁻¹X = 85%

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 85% conversion?

k = 0.25 min⁻¹X = 85%
τ = min
3.Medium
Q = 25 L/minX = 50%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 25 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 50% conversion of A.

Q = 25 L/mink = 0.4 min⁻¹X = 50%
V = L
4.Medium
Q = 100 L/minCA0​ = 2.5 mol/LCA​ = ?V = 200 L, k = 0.4 min⁻¹

A liquid-phase first-order reaction A → B (k = 0.4 min⁻¹) runs in a 200 L plug-flow reactor (PFR). The feed enters at 100 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 = 200 LQ = 100 L/mink = 0.4 min⁻¹CA0 = 2.5 mol/L
CA = mol/L
5.Hard
V = 150 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.25 min⁻¹) runs in a 150 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 = 150 LQ = 20 L/mink = 0.25 min⁻¹
X = %
6.Hard
V = 500 LQ = 100 L/minX = ?

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in a 500 L CSTR fed at 100 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 500 LQ = 100 L/mink = 0.15 min⁻¹
X = %

Answer key

  1. 1. CA = 0.2193 mol/L
  2. 2. τ = 22.67 min
  3. 3. V = 43.32 L
  4. 4. CA = 1.123 mol/L
  5. 5. X = 65.22 %
  6. 6. X = 42.86 %

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