144 MODERN PAPER-MAKING

Obviously the ideal conditions for a mill would be to work with a system
whereby no excess whitewater would accrue. The flow diagram shown
on p. 143 indicates where the water enters the system at the wet end. By
using a closed whitewater system it is possible in many cases to eliminate almost
entirely the use of fresh water. The whitewater flow diagram shows the scheme
of a closed whitewater system, where whitewater is used for cleaning the
strainers, killing froth, and for cleaning the wire. The use of whitewater for

[Reiss Engineering Co.
FIG. 4.1.—SPECIAL BENDS AND PIPES OF ROTOR WHITEWATER CIRCULATION SYSTEM, TO CAUSE THE WATER TO SPIN THROUGH
THE PIPES SPIRALLY, AND THUS KEEP THE DISCHARGE OPENING CLEAR
this purpose makes it necessary to find special devices, which are needed to
do all this work with the same efficiency as if fresh water were used. This
system, which has been developed -successfully, is known as the British Rotor
Whitewater Circulation Plant, and it makes it possible to utilise whitewater
from the save-all trays and suction boxes—before it is used for diluting the
stuff—for cleaning the strainer, killing froth, and cleaning the wire.
. The principal object of this plant is to prevent the accumulation of fibre
and loading in the pipes, and also to avoid choking the holes in spray-pipes,
and further to prevent the fine fragments of fibre and loading which have
passed through the meshes of the wire and are floating suspended in water
from clustering together. This object is achieved by installing circular bends
in the piping, which give a strong spinning or spiral motion to the water
in the pipes, which keeps all the fibre and loading in suspension; Fig, 41
shows this device. The spray-pipes are of a similar construction, and have at
each end devices which create this spiral motion. The advantages which will