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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
V = 500 L, k = 0.15 min⁻¹Q = 5 L/minCA0​ = 1 mol/LCA​ = ?

A liquid-phase first-order reaction A → B (k = 0.15 min⁻¹) runs in a 500 L continuous stirred-tank reactor (CSTR). The feed enters at 5 L/min with CA0 = 1 mol/L. The density is constant and the reactor is at steady state. Find the outlet concentration CA.

V = 500 LQ = 5 L/mink = 0.15 min⁻¹CA0 = 1 mol/L
CA = mol/L
2.Easy
V = ?, k = 0.15 min⁻¹Q = 5 L/minX = 70%

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 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 = 0.15 min⁻¹X = 70%
V = L
3.Medium
QX = 75%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 75% 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 = 75%first order, same k and Q
VCSTR/VPFR =
4.Medium
QX = 70%same Q, k and X as the CSTR

A first-order liquid-phase reaction must reach 70% 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 = 70%first order, same k and Q
VCSTR/VPFR =
5.Hard
V = 2000 LQ = 40 L/minX = ?

A first-order liquid-phase reaction (k = 0.5 min⁻¹) runs in a 2000 L CSTR fed at 40 L/min. The density is constant and the reactor is at steady state. Find the conversion X in percent.

V = 2000 LQ = 40 L/mink = 0.5 min⁻¹
X = %
6.Hard
V = 400 LV = 400 LQ = 80 L/minX = ?

A first-order liquid-phase reaction (k = 0.15 min⁻¹) runs in two equal CSTRs in series, each of 400 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 = 400 L (×2)Q = 80 L/mink = 0.15 min⁻¹
X = %

Answer key

  1. 1. CA = 0.0625 mol/L
  2. 2. V = 77.78 L
  3. 3. VCSTR/VPFR = 2.164
  4. 4. VCSTR/VPFR = 1.938
  5. 5. X = 96.15 %
  6. 6. X = 67.35 %

Full step-by-step solutions: practise this topic on examproblems.com.