Sedimentation tanks

Question 1

What principle do sedimentation tanks work on?

Answer 1

Sedimentation tanks work on the principle that trub is denser than wort so sediments by gravity

Question 2

What is the typical depth of wort in older sedimentation tank designs?

Answer 2

1.0-1.5 m

Question 3

How long does it typically take for trub to fully settle in older sedimentation tanks?

Answer 3

Around one hour

Question 4

At what time is clarified wort drawn off from the sedimentation tank?

Answer 4

After approximately 40 mins

Question 5

What device is often used in conjunction with sedimentation tanks to collect the wort?

Answer 5

A decanter centrifuge

Question 6

What is a significant risk associated with the long residence time in sedimentation tanks?

Answer 6

Producing DMS (dimethyl sulfide)

Question 7

What modern version of the sedimentation tank is mentioned?

Answer 7

Meura Clarisaver

Question 8

What does Stokes’ law relate to?

Answer 8

The sedimentation of solid material in liquids

Question 9

What is the equation representing Stokes’ law?

Answer 9

V = (d²(ρ - L)g) / (18n)

Question 10

What do the variables in Stokes’ law represent? (List the variables and their meanings)

Answer 10

• V = velocity of the trub particles
• d = diameter of the sphere
• ρ = particle density
• L = medium density
• n = viscosity of medium
• g = gravitational force

Question 11

Which factors can be influenced in the brewery to affect sedimentation according to Stokes’ law?

Answer 11

• Diameter of the sphere (floc size)
• Medium density (gravity)
• Medium viscosity (β-glucans and temperature)

Question 12

What is the most significant factor in Stokes’ law affecting the velocity of trub particles?

Answer 12

Particle diameter, as it is squared in the equation

Question 13

How can we maximize particle size to improve sedimentation?

Answer 13

By ensuring an effective boil and minimizing shear forces

Question 14

What effect does increasing wort viscosity have on the settling rate of trub?

Answer 14

It reduces the velocity of the trub particles

Question 15

What is the relationship between wort gravity and settling rate of trub?

Answer 15

The higher the wort gravity, the slower the settling rate of trub

Question 16

What common practice is discouraged to avoid increasing wort viscosity during cooling?

Answer 16

Cooling the wort too quickly

Question 17

What materials can be added to increase the density of trub particles?

Answer 17

• Kieselguhr
• Kettle finings
• PVPP

Question 18

True or False: Overdosing kettle finings and PVPP can increase trub density.

Answer 18

False