What are the core components of the roller mill for malt crushing in the brewery?
The roller mill is a critical component in the brewing process. Then what are the core components of the roller mill? How the roller mill make the influence of the finished beer? Let’s check it out!
(1) Material of grinder roll The roller of the grain mill is a cold and hard cast iron made by a centrifugal casting process. The surface of the roller has extremely high hardness. The diameter of the roller is approximately 250 mm, and the diameter cannot be too small, otherwise the grain-containing angle (the angle of containing grain formed on the surface of the roller) is too small, and the crushing ability decreases.
(2) Surface treatment of grinder roll The surface of the roller is divided into two types, one is a flat roller and the other is a drawing roller. For a multi-roller mill using a vibrating screen, the first pair and the second pair of rolls are mostly flat rolls, and others are drawing rolls.
The roller slotting is not parallel to the roller axis. They have a certain edge inclination angle (sloped groove), which enhances rolling until shearing occurs. The taper of the two rollers is always the same, between 4% and 14%.
(3) The speed of the roller The speed of the smash-to-roller is different, the rotational speed of the driving wheel is high, and the rotational speed of the driven wheel is low. The drawing roller speed ratio is approximately 2.5:1; the flat roller speed ratio is approximately 1.25:1.
The rotation speed of the roller is: pre-rolling roller, 400-420r/min; wheat roller, 400r/min; coarse roller, 380-440r/min. Roller length is usually 0.8-1m; particularly small crusher is 0.4m; extra large crusher can reach 1.5m.
(4) Roller clearance The roller gap is steplessly adjusted between 0-2.5mm. The gap of the four-roll mill is generally: the pre-roll gap is 1.5-1.5mm, and the coarse-grain roller gap is 0.3-0.6mm.
Roller parallelism adjustment: The parallelism of the rollers is a prerequisite for uniform comminution. When adjusting the shredder, check the parallelism of the roll by inserting a feeler gauge or a card that must be inserted vertically into the shredder.
(5) Roller drive One roller is fixedly mounted and runs on a conveyor belt, and the other roller is fixed on a spring and operates together. If a hard object appears, it will not seriously damage the roller. In modern shredding systems, some shredders are equipped with individually driven rollers.
The capacity of modern mills can be as high as 14t/h, and one pot can be finished in one hour. The power requirements of the fine crusher are: 2.3-2.5 kw for the lauter tun crusher and 3.3-3.8 kw for the filter crusher.