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 = 0.2 min⁻¹X = 85%

A first-order liquid-phase reaction with k = 0.2 min⁻¹ runs in a CSTR at steady state. What space time τ is needed to reach 85% conversion?

k = 0.2 min⁻¹X = 85%
τ = min
2.Easy
V = ?, k = 0.2 min⁻¹Q = 40 L/minX = 85%

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 40 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 = 40 L/mink = 0.2 min⁻¹X = 85%
V = L
3.Medium
Q = 10 L/minX = 75%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 10 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 = 10 L/mink = 0.1 min⁻¹X = 75%
V = L
4.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 =
5.Hard
V = 400 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.25 min⁻¹) runs in a 400 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 = 400 LQ = 20 L/mink = 0.25 min⁻¹
X = %
6.Hard
Q = 100 L/minX = ?V = 150 L

A first-order liquid-phase reaction (k = 0.5 min⁻¹) runs in a 150 L plug-flow reactor (PFR) fed at 100 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 150 LQ = 100 L/mink = 0.5 min⁻¹
X = %

Answer key

  1. 1. τ = 28.33 min
  2. 2. V = 1133 L
  3. 3. V = 138.6 L
  4. 4. VCSTR/VPFR = 2.485
  5. 5. X = 83.33 %
  6. 6. X = 52.76 %

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