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 = 0.5 min⁻¹X = 60%

A first-order liquid-phase reaction with k = 0.5 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 60% conversion?

k = 0.5 min⁻¹X = 60%
τ = min
2.Easy
V = ?, k = 0.4 min⁻¹Q = 50 L/minX = 95%

A first-order liquid-phase reaction A → B with k = 0.4 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 95% conversion of A.

Q = 50 L/mink = 0.4 min⁻¹X = 95%
V = L
3.Medium
Q = 50 L/minX = 70%V = ?, k = 0.15 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.15 min⁻¹ is carried out in a plug-flow reactor (PFR) fed at 50 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 = 50 L/mink = 0.15 min⁻¹X = 70%
V = L
4.Medium
Q = 80 L/minX = 75%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 80 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 = 80 L/mink = 0.4 min⁻¹X = 75%
V = L
5.Hard
V = 250 LV = 250 LQ = 80 L/minX = ?

A first-order liquid-phase reaction (k = 0.4 min⁻¹) runs in two equal CSTRs in series, each of 250 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 = 250 L (×2)Q = 80 L/mink = 0.4 min⁻¹
X = %
6.Hard
Q = 25 L/minX = ?V = 1000 L

A first-order liquid-phase reaction (k = 0.1 min⁻¹) runs in a 1000 L plug-flow reactor (PFR) fed at 25 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 1000 LQ = 25 L/mink = 0.1 min⁻¹
X = %

Answer key

  1. 1. τ = 3 min
  2. 2. V = 2375 L
  3. 3. V = 401.3 L
  4. 4. V = 277.3 L
  5. 5. X = 80.25 %
  6. 6. X = 98.17 %

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