IMPROVEMENTS IN APPARATUS FOR FILTERING INTERCEPTING AND COLLECTING DUST FROM CURRENTS OF AIR
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Anthony Stevenson at the Office of
the Commissioners of Patents on the 1st August 1882..
ANTHONY STEVENSON of the City of Chester Millwright
IMPROVEMENTS IN
APPARATUS FOR FILTERING INTERCEPTING AND COLLECTING DUST FROM CURRENTS
OF AIR
In the grinding and subsequent operations of milling in the preparation of flour
and in other manufacturing processes where dust is formed it is found necessary to
adopt means by which the dust so formed may be intercepted or filtered and
collected either for its value or for the object of merely purifying the air in which
it is temporarily suspended.
The means by which I effect the object of this Invention are as follows:-
I cause the current of dust laden air to circulate or filter through a porous fabric
in one direction upon which the dust is deposited and at intervals. I cause it to pass
through the fabric in the opposite direction. The dust so intercepted is detached from
the fabric by suitable mechanical means further assisted by the reversals of the
current of air. In carrying out my invention I proceed in the following manner.
In the interior of a chamber or box supported by its lowest extremity I mount
a light open frame of wood or other suitable material upon which I stretch a porus
fabric the mesh of which will be proportioned to the degree of fineness or minute.
state of division of the particles of the dust which it is proposed to collect-This
frame with its fabric is free to move upon its lowest extremity through a small arc
of a circle at equal angles from the perpendicular The position of the frame is
such as to divide the chamber into two parts the frame forming a diaphragm.
The upper portion of the chamber is curved to the arc of the circle of which the
frame forms the radius when swinging upon its lowest extremity.
Into the two divisions of the chamber and consequently upon alternate sides of
the diaphragm are arranged passages or openings in communication with the source
of dust laden air and which may be opened or closed at pleasure by an attendant or
automatically by suitable mechanism operated by the mill or other machinery
at predetermined intervals-corresponding with the air inlets are provided outlets
for the purified air which are also opened and closed in the same manner as the
inlet orifices or which may be controlled by the movement of the diaphragm itself.

page_text: At the alternate sides of the diaphragm are also provided receptacles for receiving
the dust collected upon the diaphragin. The operation of the apparatus is as
follows supposing the air inlet orifice on the right hand of the diaphragm to be
open the outlet on this side would be closed on the left hand the outlet orifice
would be open and the inlet closed. A current of dust laden air is admitted to the
interior of the chamber through the open inlet orifice and finding no other exit
passes through the fabric of the diaphragm depositing its dust upon its surface the
purified air escaping through the open outlet on the left side. As the surface of the
fabric becomes charged or laden with dust the current of air is reversed to the left
side of the diaphragm the outlet valve on this side is now closed the inlet valve on
the right side is closed and the outlet valve opened The instant this takes place
the diaphragin which had previously been inclined from right to left is by the
pressure of the air on the opposite side suddenly blown or lifted over from left to
right, shaking off the dust which had been collected, by the concussion, into the
receptacle prepared for it and at the same time exposing a new intercepting or
filtering surface to the current of air. When this side in its turn becomes dust
laden the reversal of the current of air again takes place when the same operations
are repeated-A second modification of the above apparatus consists in causing the
dust laden air to filter through a fixed diaphragm the surfaces of which as they
become coated or clogged with dust are cleaned by a series of brushes or scrapers,
while to assist the cleaning operation the current of air is reversed from one side of
the diaphragm to the other so that, as the dust is being deposited upon one side the
air in passing through the fabric to the other side assists any mechanical cleaner
by blowing back fine particles which cannot be reached by the scraper or brushes
but which have been intercepted by the mesh of the fabric.
A third modification consists in passing the current of dust laden air through a
loosely hung or stretched fixed diaphragm upon which the dust is deposited on the
concave surface caused by the pressure of the air distending the fabric-at certain
intervals the current of air is reversed as above described when by its reversal the
.surface of the fabric in the diaphragm which was convex becomes concave and the
side upon which the dust had been deposited becomes convex-The shock thus
caused (similar to that produced in shaking carpets) has the effect of detaching the
intercepted dust from the fabric while the reversal of the current of air assists still
further in keeping the mesh clean and so fitted for continuous work