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 = 1500 L, k = 0.2 min⁻¹Q = 40 L/minCA0​ = 2.5 mol/LCA​ = ?

A liquid-phase first-order reaction A → B (k = 0.2 min⁻¹) runs in a 1500 L continuous stirred-tank reactor (CSTR). The feed enters at 40 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 = 1500 LQ = 40 L/mink = 0.2 min⁻¹CA0 = 2.5 mol/L
CA = mol/L
2.Easy
τ = ?k = 0.12 min⁻¹X = 75%

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 75% conversion?

k = 0.12 min⁻¹X = 75%
τ = min
3.Medium
Q = 80 L/minCA0​ = 1.5 mol/LCA​ = ?V = 150 L, k = 0.12 min⁻¹

A liquid-phase first-order reaction A → B (k = 0.12 min⁻¹) runs in a 150 L plug-flow reactor (PFR). The feed enters at 80 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 = 150 LQ = 80 L/mink = 0.12 min⁻¹CA0 = 1.5 mol/L
CA = mol/L
4.Medium
Q = 25 L/minX = 85%V = ?, k = 0.25 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.25 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 85% conversion of A.

Q = 25 L/mink = 0.25 min⁻¹X = 85%
V = L
5.Hard
V = 500 LV = 500 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.1 min⁻¹) runs in two equal CSTRs in series, each of 500 L. The feed rate is 20 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 500 L (×2)Q = 20 L/mink = 0.1 min⁻¹
X = %
6.Hard
V = 2000 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.5 min⁻¹) runs in a 2000 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 = 2000 LQ = 20 L/mink = 0.5 min⁻¹
X = %

Answer key

  1. 1. CA = 0.2941 mol/L
  2. 2. τ = 25 min
  3. 3. CA = 1.198 mol/L
  4. 4. V = 189.7 L
  5. 5. X = 91.84 %
  6. 6. X = 98.04 %

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