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 = 250 L, k = 0.12 min⁻¹Q = 80 L/minCA0​ = 0.5 mol/LCA​ = ?

A liquid-phase first-order reaction A → B (k = 0.12 min⁻¹) runs in a 250 L continuous stirred-tank reactor (CSTR). The feed enters at 80 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 = 250 LQ = 80 L/mink = 0.12 min⁻¹CA0 = 0.5 mol/L
CA = mol/L
2.Easy
V = ?, k = 0.1 min⁻¹Q = 50 L/minX = 75%

A first-order liquid-phase reaction A → B with k = 0.1 min⁻¹ is carried out in a continuous stirred-tank reactor (CSTR) fed at 50 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 75% conversion of A.

Q = 50 L/mink = 0.1 min⁻¹X = 75%
V = L
3.Medium
Q = 5 L/minX = 70%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 5 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 = 5 L/mink = 0.25 min⁻¹X = 70%
V = L
4.Medium
Q = 40 L/minX = 70%V = ?, k = 0.1 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.1 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 = 0.1 min⁻¹X = 70%
V = L
5.Hard
V = 250 LV = 250 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.25 min⁻¹) runs in two equal CSTRs in series, each of 250 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 = 250 L (×2)Q = 20 L/mink = 0.25 min⁻¹
X = %
6.Hard
V = 2000 LV = 2000 LQ = 80 L/minX = ?

A first-order liquid-phase reaction (k = 0.2 min⁻¹) runs in two equal CSTRs in series, each of 2000 L. The feed rate is 80 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 2000 L (×2)Q = 80 L/mink = 0.2 min⁻¹
X = %

Answer key

  1. 1. CA = 0.3636 mol/L
  2. 2. V = 1500 L
  3. 3. V = 24.08 L
  4. 4. V = 481.6 L
  5. 5. X = 94.12 %
  6. 6. X = 97.22 %

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