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 = 10 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 10 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 = 10 L/mink = 0.2 min⁻¹X = 85%
V = L
2.Easy
V = ?, k = 0.12 min⁻¹Q = 50 L/minX = 75%

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 75% conversion of A.

Q = 50 L/mink = 0.12 min⁻¹X = 75%
V = L
3.Medium
QX = 95%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 95% 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 = 95%first order, same k and Q
VCSTR/VPFR =
4.Medium
Q = 80 L/minX = 70%V = ?, k = 0.25 min⁻¹

A first-order liquid-phase reaction A → B with k = 0.25 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 = 0.25 min⁻¹X = 70%
V = L
5.Hard
V = 1000 LV = 1000 LQ = 50 L/minX = ?

A first-order liquid-phase reaction (k = 0.1 min⁻¹) runs in two equal CSTRs in series, each of 1000 L. The feed rate is 50 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 1000 L (×2)Q = 50 L/mink = 0.1 min⁻¹
X = %
6.Hard
V = 100 LV = 100 LQ = 25 L/minX = ?

A first-order liquid-phase reaction (k = 0.12 min⁻¹) runs in two equal CSTRs in series, each of 100 L. The feed rate is 25 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 100 L (×2)Q = 25 L/mink = 0.12 min⁻¹
X = %

Answer key

  1. 1. V = 283.3 L
  2. 2. V = 1250 L
  3. 3. VCSTR/VPFR = 6.342
  4. 4. V = 385.3 L
  5. 5. X = 88.89 %
  6. 6. X = 54.35 %

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