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 = 0.3 min⁻¹Q = 25 L/minX = 75%

A first-order liquid-phase reaction A → B with k = 0.3 min⁻¹ is carried out in a continuous stirred-tank reactor (CSTR) fed at 25 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 = 25 L/mink = 0.3 min⁻¹X = 75%
V = L
2.Easy
V = ?, k = 0.15 min⁻¹Q = 20 L/minX = 75%

A first-order liquid-phase reaction A → B with k = 0.15 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 75% conversion of A.

Q = 20 L/mink = 0.15 min⁻¹X = 75%
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
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
Q = 40 L/minX = ?V = 200 L

A first-order liquid-phase reaction (k = 0.2 min⁻¹) runs in a 200 L plug-flow reactor (PFR) fed at 40 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 200 LQ = 40 L/mink = 0.2 min⁻¹
X = %
6.Hard
V = 250 LV = 250 LQ = 80 L/minX = ?

A first-order liquid-phase reaction (k = 0.15 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 = 0.15 min⁻¹
X = %

Answer key

  1. 1. V = 250 L
  2. 2. V = 400 L
  3. 3. VCSTR/VPFR = 2.987
  4. 4. VCSTR/VPFR = 2.485
  5. 5. X = 63.21 %
  6. 6. X = 53.64 %

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