94

MODERN PAPER-MAKING

amount of stock, and consuming time and power, the charge is let down to
the refiner chest, the stuff is immediately started on its way to the machine,
and the beater is refilled.

The refiner usually consists of a cone-shaped shell or case (Fig. 30) on the
inside of which are set, longitudinally, bars similar to those in a beater plate,
with knees or zigzag formation. An internal conical rotor fitted with straight
bars is mounted on a shaft so arranged that the bars may.be brought into close
contact with the bars on the inside of the outer shell. Li some refiners there
is also a disc with corresponding blades on the rotor disc. The central rotor is

FIG. 31.—THE MASCOT RJEHNER

[Masson, Scott and Co. Ltd.

adjustable by a hand-wheel and traversing gear, which moves the shaft and
cone into the outer cone, bringing all the bars on the rotor and disc into contact.
The illustrations clearly show the arrangement of bars.
When properly set, stock that is clear passes readily through the machine
without being cut or injured; larger or uncleared fibres, knots of stuff, etc., are
caught by the bars and rubbed out or cut before they can pass through.
The stuff enters at the small end of the cone, and is discharged from a
pipe on the circumference of the disc. It is obvious that the action can be
made more drastic, though at a very great expenditure of power. The rotor
may be pressed harder against the outer cone, when the refiner takes on the
action of a beater with extreme cutting characteristics, especially as the stuff is
at a much lower consistency than in die beater. To overcome this difficulty
concentrators are sometimes used to extract water from the stock before it
enters the refiner. After passing through the refiner in a highly concentrated
condition, the stock and the extracted Vater are again mixed together. Under
these conditions there is no doubt that fibrillation takes place with some fibres,