Four-Roller Dry Mill Flashcards
(22 cards)
What is the primary use of a four-roller mill?
Used in medium-sized breweries with mash tuns and possibly lauter tuns.
How many stages of comminution does a four-roller mill have?
Two stages.
What is the typical mill gap for the first set of rollers in a four-roller mill?
1.3-1.9 mm.
What is the gap range for the second set of rollers in a four-roller mill?
0.25-1 mm.
What is the grist production rate of a four-roller mill per mm of roller length?
2-6 kg/h.
What is the diameter of the rollers in a four-roller mill?
300 mm.
At what rpm does the first set of rollers in a four-roller mill operate?
210-230 rpm.
What is the operating rpm of the second set of rollers in a four-roller mill?
280 rpm.
What types of malts can a four-roller mill process?
- Well-modified base malts
- Over-modified base malts
- Speciality malts.
Can a four-roller mill effectively mill raw barley?
No.
How is grain fed into the four-roller mill?
By gravity, using a feed roller or feed plate.
What is the advantage of a four-roller mill over a two-roller mill?
Gives a more complete crush.
What additional feature do more sophisticated four-roller mills have?
Screens between the pairs of rollers.
What type of screens can four-roller mills use?
- Rotary screens with beaters
- Reciprocating flat screens.
Which type of screen achieves greater throughput in four-roller mills?
Reciprocating screens.
What is the purpose of the plate below each crushing roller in a four-roller mill?
To keep the space below the rollers full of grist.
What is the function of the five-roller mill?
Increases the number of milling stages for better particle size distribution control.
How does the five-roller mill compare to the six-roller mill in terms of rarity?
Less common than the six-roller mill.
What is the role of the first pair of rollers in a five-roller mill?
To crush the grain.
What happens to the grist after being screened in a five-roller mill?
It is crushed between the second pair of rollers.
Why does roller two in a five-roller mill wear more rapidly?
It completes twice the amount of work.
What type of mill is the five-roller mill a predecessor of?
The six-roller mill.
