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 = 80 L/minX = 60%

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 80 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 = 80 L/mink = 0.2 min⁻¹X = 60%
V = L
2.Easy
V = ?, k = 0.12 min⁻¹Q = 5 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 5 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 = 5 L/mink = 0.12 min⁻¹X = 70%
V = L
3.Medium
Q = 25 L/minX = 90%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 25 L/min. The density is constant and the reactor is at steady state. Find the reactor volume V in litres for 90% conversion of A.

Q = 25 L/mink = 0.1 min⁻¹X = 90%
V = L
4.Medium
QX = 60%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 60% 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 = 60%first order, same k and Q
VCSTR/VPFR =
5.Hard
Q = 80 L/minX = ?V = 800 L

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in an 800 L plug-flow reactor (PFR) fed at 80 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 800 LQ = 80 L/mink = 0.15 min⁻¹
X = %
6.Hard
V = 500 LV = 500 LQ = 20 L/minX = ?

A first-order liquid-phase reaction (k = 0.08 min⁻¹) runs in two equal CSTRs in series, each of 500 L. The feed rate is 20 L/min, the density is constant and the reactors are at steady state. Find the overall conversion X in percent.

V = 500 L (×2)Q = 20 L/mink = 0.08 min⁻¹
X = %

Answer key

  1. 1. V = 600 L
  2. 2. V = 97.22 L
  3. 3. V = 575.6 L
  4. 4. VCSTR/VPFR = 1.637
  5. 5. X = 77.69 %
  6. 6. X = 88.89 %

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