Material
to be dewatered is delivered to the extruder
feed hopper. It accumulates
until a pre-determined level is reached, at
which time a load sensor signals the extruder
computer, initiating the dewatering cycle
described below.
While
in the forward compressions cycle (see
below), the top of the ram box seals the
bottom of the feed hopper.
Upon commencement of a new cycle, the hydraulically powered ram fully retracts. As
the ram face passes beneath
the hopper, the hopper bottom is exposed, allowing a new batch to drop into
the charging chamber (see above). Once the ram has fully retracted, the
logic system initiates the next forward cycle of ram movement.
The
extruder discharge plenum, which was wide
open during the previous forward compression
cycle to permit
discharge of dewatered solids, now partially closes. Its separate hydraulic
system accumulator remains charged, maintaining pressure on the plenum
in this position until additional solids are compressed, dewatered and ready
for discharge.
As
the compression cycle begins, the ram face
passes the forward edge of the feed hopper
and the top surface
of the ram box once again seals the feed hopper bottom. During the ram's
forward movement, newly charged
wet material is pressed with progressively increasing force into previously
compressed partially dewatered
material that is restricted from further forward movement by the partially
closed discharge plenum.
Liquid
extraction occurs as the ram pressure increases
in programmed steps, causing liquids to be
expelled through small perforations in the
walls, roof and floor of the dewatering chamber. These
perforations are of an
outwardly tapered self-relieving design which acts to prevent plugging and
impairment of liquid extraction.
Expelled liquid can be collected in a trough positioned beneath the extruder. this
flow may be directed to a sump or pump box for delivery to a holding
tank or other disposition.
As
each programmed level of ram pressure is
reached the ram's forward movement is restrained
temporarily to permit full evacuation of liquid from the innermost section of the dewatering
chamber. This patented, time interval managed compression technique is the key to producing
a uniformly dry discharge product.
As
the ram nears the end of its forward travel,
pressure within the dewatering and extrusion
chambers reaches the maximum desired level
for effective liquid expulsion. Pressure
sensors acting in concert
with the extruder control system cause the discharge plenum to open fully,
permitting ejection of dewatered
solids into a container. Control of plenum opening is modulated by pressure
sensing from within the
dewatering chamber. The cycle is now complete and the ram box retracts
to begin a new dewatering cycle.
To learn more about the High Density Extruder and how it can work in
your waste handling application, please contact us at
800-253-0532
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