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 = 0.2 min⁻¹Q = 20 L/minX = 90%

A first-order liquid-phase reaction A → B with k = 0.2 min⁻¹ is carried out in a continuous stirred-tank reactor (CSTR) fed at 20 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 = 20 L/mink = 0.2 min⁻¹X = 90%
V = L
2.Easy
τ = ?k = 0.08 min⁻¹X = 80%

A first-order liquid-phase reaction with k = 0.08 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 80% conversion?

k = 0.08 min⁻¹X = 80%
τ = min
3.Medium
QX = 80%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 80% conversion. How many times larger must a CSTR be than a PFR for the same feed rate, rate constant and conversion? Find the ratio VCSTR/VPFR.

X = 80%first order, same k and Q
VCSTR/VPFR =
4.Medium
QX = 70%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 70% conversion. How many times larger must a CSTR be than a PFR for the same feed rate, rate constant and conversion? Find the ratio VCSTR/VPFR.

X = 70%first order, same k and Q
VCSTR/VPFR =
5.Hard
Q = 25 L/minX = ?V = 250 L

A first-order liquid-phase reaction (k = 0.08 min⁻¹) runs in a 250 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 = 250 LQ = 25 L/mink = 0.08 min⁻¹
X = %
6.Hard
Q = 25 L/minX = ?V = 400 L

A first-order liquid-phase reaction (k = 0.12 min⁻¹) runs in a 400 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 = 400 LQ = 25 L/mink = 0.12 min⁻¹
X = %

Answer key

  1. 1. V = 900 L
  2. 2. τ = 50 min
  3. 3. VCSTR/VPFR = 2.485
  4. 4. VCSTR/VPFR = 1.938
  5. 5. X = 55.07 %
  6. 6. X = 85.34 %

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