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 = 0.12 min⁻¹Q = 20 L/minX = 60%

A first-order liquid-phase reaction A → B with k = 0.12 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 60% conversion of A.

Q = 20 L/mink = 0.12 min⁻¹X = 60%
V = L
2.Easy
V = ?, k = 0.2 min⁻¹Q = 40 L/minX = 70%

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 70% conversion of A.

Q = 40 L/mink = 0.2 min⁻¹X = 70%
V = L
3.Medium
Q = 80 L/minX = 70%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 70% conversion of A.

Q = 80 L/mink = 0.4 min⁻¹X = 70%
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 = 1500 LQ = 5 L/minX = ?

A first-order liquid-phase reaction (k = 0.05 min⁻¹) runs in a 1500 L CSTR fed at 5 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 1500 LQ = 5 L/mink = 0.05 min⁻¹
X = %
6.Hard
V = 2000 LQ = 100 L/minX = ?

A first-order liquid-phase reaction (k = 0.3 min⁻¹) runs in a 2000 L CSTR fed at 100 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 2000 LQ = 100 L/mink = 0.3 min⁻¹
X = %

Answer key

  1. 1. V = 250 L
  2. 2. V = 466.7 L
  3. 3. V = 240.8 L
  4. 4. VCSTR/VPFR = 2.485
  5. 5. X = 93.75 %
  6. 6. X = 85.71 %

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