CONTINUOUSLY SELF-CLEANING DRUM FILTER

FILTRE A TAMBOUR A AUTONETTOYAGE CONTINU

English Abstract

A continuously self-cleaning filter consists of a rotating drum filter, an
oscillating high-pressure air nozzle to remove cake and particles from the
filter mesh; the means to drive the drum filter and the oscillating nozzle;
and
a chute to catch the material dislodged from the filter mesh and to direct it
to
a receiving tank.
To accomplish this, water, containing dirt particles, droplets of free
oil or metal particles, oil or other contaminants encapsulated in bentonite
clay, is directed onto the inner surface of the drum filter mesh, at the
lowest
point of its rotation, where substantially all of the water passes through the
filter mesh, while the particles or cake are trapped in the filter mesh and
travel to the top of the drum filter rotation, where they are blown out of the
filter mesh by compressed air, onto a receiving chute, and thereby directed to
a receiving tank. The clean water is collected in a separate receiver.
To this end, one end of the filter drum is solid and fixed rotatably on
essentially a horizontal axle, the other end of the drum has a circular
opening
through which the solids bearing water is introduced and the filtered cake
removed by the chute.

Claims

CLAIMS
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A device for continuously cleaning a drum filter comprising:
a. a hollow-bore oscillating air nozzle assembly having a first end and
a second end, the first end having a nozzle orifice, the second end attaching
to an air supply hose.
b. a means of effecting an oscillating movement of the air nozzle
assembly, such means comprising a connecting rod, a rocker arm and a
motor-driven cam ring.
c. a means of collecting the cake, solid particles or oil droplets from
the filter mesh and directing it to a receiving tank or collector.
2. An air nozzle assembly, as in claim 1, such assembly being fixedly
attached to a rocker arm.
3. A rocker arm as in claim 2, pivotally attached to the drum filter
support frame.
4. A means, as in claim 1, of connecting the rocker arm to the cam ring
comprising a connecting rod having two ends, the first end fixedly attached to
the rocker arm of claim 3, the second end freely engaging the cam ring.
5. A chute as in claim 1, fixedly attached to the drum filter support
frame, which extends through the opening of the annular drum end and

Description

CA 02257332 1998-12-21
FIELD OF THE INVENTION
The invention herein described relates to a rotary drum filter, one end
of which is solid, the other end being annular; such drum being rotatable
around a horizontal, or nearly horizontal, axis; having as oscillating
compressed-air nozzle directed at the outer surface of the filter mesh at the
top of its rotation; a water-delivery pipe extending into the opening of the
annular drum end which directs the water onto the inner surface of the filter
mesh at the bottom of its rotation, and a chute extending upwards through
the opening in the annular drum end and extending to, but not touching, the
solid drum end

CA 02257332 1998-12-21
PRIOR ART
Drum filters are generally known, but have several drawbacks. Their
primary purpose in many cases is to de-water a solids/liquid combination, the
purpose being to achieve a consistency of water content of the solids, in, for
example, sewage treatment, or pulp and paper manufachlring. Many also use
the filtered water to cleaa the filter mesh. Since the purpose of the present
invention is to remove, from the water, contaminants such as dirt and metal
particles, oil droplets, or oil, dirt, and metal particles encapsulated in
bentonite clay, it is self-defeating to clean the filter mesh with water. Many
drum filters incorporate a mechanical scraper to clean the cake from the
mesh. The present invention eliminates the need for such a device.
A drum filter which uses compressed air as a partial cleaning method is
described in Canadian Patent # 2,005,432. In that instance, compressed air
exiting a fixed nozzle is directed at the filter mesh to only prevent dust
from
resettling on the filter surface after it has already been cleaned by a
mechanical scraper.
Other known rotary-dmm filters incorporating compressed air direct
the compressed air from a plurality of nozzles toward the filter mesh from the
inside of the drum to dislodge dry cake. Such a device using fixed nozzles is
impractical to remove wet, heavy cake, such as is formed by the process of
encapsulation using a bentonite clay, since the quantity and pressure of the
air
required is prohibitively high for practical applications.

CA 02257332 1998-12-21
SUMMARY
The object of the present invention is to overcome the
aforementioned drawbacks by providing an air nozzle which oscillates back
and forth over the width of the filter mesh, describing an arc, essentially at
right angles to the direction of rotation of the filter, directing compressed
air
onto the outer surface of the filter mesh as it rotates, thereby dislodging
the
cake and particles from the inside surface of the filter mesh.
Another object of the present invention is to provide a catchment
system for the cake or particles dislodged from the filter mesh by the
compressed air. This consists of a chute extending upwards and into the
~ a interior of the drum end, and positioned below the arc of the oscillating
nozzle, such that it captures the cake or particles dislodged from the filter
mesh and directs it toward a receiver.
Still another object of the invention is to provide a means of driving
the oscillating nozzle, such means being a motor-driven cam ring, a
connecting rod and a rocker arm.
The invention, as exemplified by a preferred embodiment, is
described with refcrence to the drawings in which Figure I, a front view,
shows a drum filter (4); a framework to support it (6); an axle and bearing
attached to the rear, solid end of the drum (8); a drive motor ( 10); a drive
o'IO belt {12); a cam ring ( 14); a cam ring drive pulley ( 16); an
oscillating air
nozzle ( 18); a pivot pin (20); connecting rod (22); annular shaped front drum
end (24); a liquid delivery pipe {26). The filter mesh (28) is depicted by the

CA 02257332 1998-12-21
crosshatched area The cake receiving chute (30) has been omitted from
Figure I for the sake of clarity but is shown in Figure II, a side elevation.
Figure III is a rear view of the drum filter showing the fiamc (6); the axle
and
bearing (8); the drum pullcy (32); drive motor (10); drive belt (12); and cam
ring ( 14).
As the drum filter rotates continuously, on essentially a horizontal
axis, the water to be filtered is directed onto the inner surface of the
filter
mesh at the bottom of the filter drum's rotation. The water passes through
the filter mesh to a receiving tank below, leaving the cake and particles
! d entrapped in the filter mesh. At the top of the drum rotation, the
particles
and cake are blown out of the filter mesh, from the outside, by the force of
the compressed air issuing from the oscillating nozzle ( 18). The cake and
particles drop onto the receiving chute (30) and slide down it into a
receiver.
Although only a single embodiment of the present invention has been
described and illustrated, the present invention is not limited to the
features of
this embodiment, but includes all variations and modifications within the
scope of the claims.
It is contemplated that the continuously self-cleaning filter can be
used to clean fluids other than water.
,~ 4 It is further contemplated that the oscillating nozzle may have more
than one orifice.
It is still further contemplated that the oscillating nozzle could be
driven by means other than a cam ring.

CA 02257332 1998-12-21
SUMMARY OF THE DRAWINGS
Figure I is a perspective front view showing the drum opening. The
chute has been omitted for clarity and is shown in Figure lI, which is a side
elevation. Again, for clarity, the drum pulley is sectional and the drive belt
is
not shown.

Representative Drawing