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 = ?, k = 0.1 min⁻¹Q = 100 L/minX = 90%

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 100 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 90% conversion of A.

Q = 100 L/mink = 0.1 min⁻¹X = 90%
V = L
2.Easy
V = ?, k = 0.25 min⁻¹Q = 10 L/minX = 95%

A first-order liquid-phase reaction A → B with k = 0.25 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 95% conversion of A.

Q = 10 L/mink = 0.25 min⁻¹X = 95%
V = L
3.Medium
Q = 100 L/minCA0​ = 2.5 mol/LCA​ = ?V = 250 L, k = 0.5 min⁻¹

A liquid-phase first-order reaction A → B (k = 0.5 min⁻¹) runs in a 250 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 = 250 LQ = 100 L/mink = 0.5 min⁻¹CA0 = 2.5 mol/L
CA = mol/L
4.Medium
Q = 20 L/minX = 60%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 20 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 60% conversion of A.

Q = 20 L/mink = 0.1 min⁻¹X = 60%
V = L
5.Hard
V = 250 LV = 250 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.3 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 = 0.3 min⁻¹
X = %
6.Hard
V = 100 LV = 100 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in two equal CSTRs in series, each of 100 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 = 100 L (×2)Q = 20 L/mink = 0.15 min⁻¹
X = %

Answer key

  1. 1. V = 9000 L
  2. 2. V = 760 L
  3. 3. CA = 0.7163 mol/L
  4. 4. V = 183.3 L
  5. 5. X = 95.57 %
  6. 6. X = 67.35 %

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