Alternatively, the cone timer is used with slippery or slimy press cake that cannot be
dewatered to sufficient firmness to force the cone open.
Cone Timer panels are available from Vincent for a minimal cost.
Start Up
Check the inlet hopper first. Sometimes debris (or this owner's manual) ends up in the inlet
hopper. Before putting power to the screw press, it is advisable to bump the motor or even
rotate the screw by hand. This will prevent damage to the press in case tramp material has
been left in the press. Also, the screw may have shifted so as to hit the screen. (Minor
rubbing is normal; it will go away once there is material in the press.) To turn the screw by
hand, remove the fan guard on the motor and turn the fan blades. The screw of the press
turns in a counterclockwise direction, when viewed from the drive end of the press.
Check to make sure that compressed air is being supplied to the regulator and that the cone
can be opened and closed. Set the backpressure at a low level and/or start with the cone
open.
Start the press. Minor screw-to-screen rubbing is normal and will go away when
material is fed to the press.
Begin feeding material to the press. It's helpful to have someone watching the level
in the inlet hopper to ensure that the press isn't overloaded.
When material starts appearing at the discharge end, close the cone if it is open.
Increase backpressure on the cone until the moisture level in the press cake appears to
be as dry as you'd like. Continue monitoring the level in the inlet hopper as
increasing backpressure will influence throughput. You may need to increase screw
speed in tandem with increasing backpressure to get desired dryness and adequate
throughput. See the next section on screw speed.
Screw Speed (RPM)
In general, the slower the screw speed, the greater the dewatering. Longer residence time in
the screened area results from lower screw speed, which allows time for more thorough
dewatering. Unfortunately, it also means reduced throughput capacity.
A small change in screw speed, like 15%, will generally not result in a measurable change in
performance of the press. This is particularly true for the interrupted flight screws.
Continuous flighted screws show more reaction to changes in screw speed. In any case, it's
not going to be a linear relationship. That is, doubling the screw speed will not double the
throughput. And you do reach a point of diminishing returns.
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