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 = 0.25 min⁻¹Q = 100 L/minX = 75%

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 100 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 = 100 L/mink = 0.25 min⁻¹X = 75%
V = L
2.Easy
V = ?, k = 0.12 min⁻¹Q = 50 L/minX = 70%

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 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 = 0.12 min⁻¹X = 70%
V = L
3.Medium
QX = 85%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 85% 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 = 85%first order, same k and Q
VCSTR/VPFR =
4.Medium
Q = 50 L/minX = 80%V = ?, k = 0.3 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.3 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 80% conversion of A.

Q = 50 L/mink = 0.3 min⁻¹X = 80%
V = L
5.Hard
Q = 5 L/minX = ?V = 50 L

A first-order liquid-phase reaction (k = 0.2 min⁻¹) runs in a 50 L plug-flow reactor (PFR) fed at 5 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 50 LQ = 5 L/mink = 0.2 min⁻¹
X = %
6.Hard
V = 400 LV = 400 LQ = 10 L/minX = ?

A first-order liquid-phase reaction (k = 0.12 min⁻¹) runs in two equal CSTRs in series, each of 400 L. The feed rate is 10 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 400 L (×2)Q = 10 L/mink = 0.12 min⁻¹
X = %

Answer key

  1. 1. V = 1200 L
  2. 2. V = 972.2 L
  3. 3. VCSTR/VPFR = 2.987
  4. 4. V = 268.2 L
  5. 5. X = 86.47 %
  6. 6. X = 97.03 %

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