Wort Separation Device Outputs

The previous lesson outlined the principles of wort separation, and how Darcy’s Law can be applied to describe the governing parameters of filtration flow rate. We are now going to look at the three most common wort separation devices and identify the key differences in their design and mode of operation.

For the duration of the lesson, we will assume we are processing 10 t of grist, with the following operational data:

Table: Design and operational parameters for 10 t of grist

Darcy Variable

 

Lauter Tun

Mash Tun

Mash Filter

 

Tun diameter  (m)

8

5

20 (58 chambers)

 

Grain bed loading  (kg / m²)

200

500

30

 

Cycle time (min)

144

288

110

 

Brews per day

10

5

13

 

Milling system

Wet / six-roll dry

Two / four-roll dry

Hammer

Q

Wort flow rate (hL/h)

889.2

378

1522.9

K

Bed permeability (m²) 

3.084 x 10-11

9.72 x 10-11

      3.525 x 10-13

K

Relative permeability

87

275

1

DP

Maximum limit (bar)

0.1

0.1

0.3

A

Filtration surface area (m²) 

50

20

330

Mash Water  (L/kg)

3.3

2.5

2.7

Sparge water L/kg

4.0

5.0

2.8

Malt modification

Less well

Well

Less well

Mash temperature (˚C)

76

65

76

µ

Wort viscosity (mPa.s)

1.25

1.85

1.65

L

Grain bed depth (m)

0.5

1.0

0.05

There is a lot to digest here!  Worry not; we are going to work through this one step at a time.

The highlighted bottom half of the table refers to the variables of Darcy’s Law. We have already covered these in the previous teaching lesson, but as a refresher, Darcy’s Law is:

                                             straight Q equals left parenthesis straight K cross times DP cross times straight A right parenthesis divided by left parenthesis straight mu cross times straight L right parenthesis

So, anything that we can do to increase K, DP, A and anything that we can do to decrease μ, L will give us a higher flow Q.

Let us now find out how these variables affect the design and operation of the lauter tun, the mash tun and mash filter. We will consider one device at a time.

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