Improvements in Apparatus for Refining Fats and Oils.
Year: 1897

page_text: Date of Application, 11th June, 1897-Accepted, 8th Jan., 1898
COMPLETE SPECIFICATION.
Improvements in Apparatus for Refining Fats and Oils.
We, JAMES DAVIDSON, Grain Merchant, of Australian Joint Stock Bank Chambers,
George Street, and CHARLES GRAHAM HEPBURN, Patent Agent, of corner of King
and Elizabeth Streets, both in Sydney, in the Colony of New South Wales, do
hereby declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
-
In the refining of fats and oils, and especially in the refining of tallow, filtering
by known methods is a slow and imperfect process. Fats must be rendered to the
liquid form to undergo filtration, and as they should not, for well known reasons,
be run whilst still hot into barrels or other packages, they are usually cooled off
in tanks before being packed.
It has been suggested to effect filtration by passing the oil or fat through a
centrifugal machine of the hydro-extractor class having a fabric lining such as mole-
skin in the basket; and it has also been suggested to blow cool air through the
liquefied fat for the purpose of cooling it.
With a view to improving these operations, we have devised the apparatus
illustrated in the accompanying drawings. A long series of experiments was made
to test the suitability of various substances for filtering media, sand, charcoal,
cork shavings, vegetable-fibre, hemp, cotton-waste, and cotton-wool being used
with lining bands of various fabrics, all with unsatisfactory results, though in some
cases a limited success was attained. Sawdust was however found to suit substan-
tially all requirements and to have a high efficiency.
The apparatus consists essentially of a filtering bed of sawdust carried in a
centrifugal basket the rotation of which forms the filtrate through the sawdust;
and a cooler arranged to receive the spray of filtrate from the basket and reduce
its temperature.
In the annexed sheet of explanatory drawings, Fig. 1 is a vertical sectional
elevation of our apparatus, and Fig. 2 a horizontal section through same on line
below rim of monitor.
I is the bed plate, 2 pillars, 3 monitor casing, 4 rim of monitor, 5 perforated
metal shell of basket 6, 7 bottom plate of basket, 8 flange of basket, 9 spring wire
lining of basket, 10 fabric lining, 11 spring retaining rings for fabric 10, 12 saw-
dust filtering bed, 13 spindle of basket, 14 holding down nut, 15 driving belt, 16 fast
pulley on spindle 13, 17 guide pulleys, 18 filtrate pipe, 19 cooler, 20 water supply,
21 water discharge from cooler 19, 22 drain_tap.
The rotating basket 6, which is usually made of woven wire, is lined internally
with a band 10 of any textile substance which will allow fluid fats and oils to
pass through it freely, but will retain fine particles of sawdust. This band should
have a bottom piece sewn into it, which will lie on the bottom 7 of the basket
and be fastened down by screwing on the nut 14, a hole being made to allow the
end of the spindle 13 to pass through. By this construction unfiltered liquid is
prevented from passing to the basket shell.. In operation there is a tendency for
the wash of the feed to undermine the wall of sawdust, and when the sawdust wall

page_text: becomes thinned in this way unfiltered liquid is liable to work its way along the
bottom of the basket and escape unfiltered. The covering of the bottom of the
basket as described ensures the passing of all filtrate through the fabric lining.
When the basket is made of perforated plates as shown at 5 it is advisable to
place a piece of open wire cloth or woven wire 9, such as is used in woven wire
mattresses, between the fabric lining 10 and the shell 6 of the basket, in order
that the filtrate may pass freely to the perforations. The band 10 is held in place
by a pair of spring rings 11 to which its upper and lower edges are attached by
sewing.
The basket so lined is charged with a sufficiency of sawdust to form a thick
filtering bed. The quantity will depend on the capacity of the basket; we have
obtained maximum advantages when the thickness of the sawdust bed or belt
averaged six inches to one foot. A white sawdust must be used, as the coloring
matters of dark sawdust wash out and stain the fat or oil under treatment; a dark
sawdust might however be used if first washed and decolorised.
When the basket is rotated at its normal running speed, the sawdust will heap
itself up around the periphery by centrifugal action as indicated in the drawing.
It is not necessary to keep the sawdust bed of uniform thickness from top to bottom.
There is no novelty in the mounting of the monitor 3, or of the basket 6, or in
the arrangement of the driving mechanism.
The cooler consists, of an annular water chamber, with a diaphragm to direct the
circulation, and is placed in the space between the basket and the monitor. A
water service 20 enters it. at one side of the diaphragm-which is a cross vertical
partition and the inflow pipe is led to the bottom. On the other side of the
diaphragm, at the top of the chamber, the outflow pipe is connected. Water sent
into the cooler makes a complete course through it before finding egress. The
inner wall of the cooler is made of corrugated metal in order to obtain a maximum
surface. The drain cock 22 is provided for emptying the cooler when necessary.
The rotation of the basket induces a powerful air current in the space between
the basket and the cooler. The fine spray of fat or oil thrown off by the basket
becomes considerably cooled by the action of this draught before it reaches the
wall of the cooler. Owing to the finely divided form of the spray a very rapid
cooling is obtained, every particle of the filtrate being exposed to the action of the
air current and to contact with the wall of the cooler.
In operation the fat heated sufficiently high to make it freely liquid, or the
oil to be refined, is poured in a stream into the middle of the basket, which is kept
At the same time
rotating at a peripheral speed of 1500 to 4000 feet per minute.
cold water is supplied continuously to the water chamber. The centrifugal
action due to the rotation of the basket forces the fluid fat or oil through the
sawdust at a rapid rate, at the same time compacting the sawdust. The solid and
glutinous and other matters capable of being filtered out are retained by the
sawdust whilst the purified fat or oil is thrown off by the basket in the form of a
spray which falls upon the corrugated wall of the water chamber 19 forming a
film thereon and dripping off into the bottom of the monitor, whence it passes to the
packages through the pipe 18. This operation is continued until the filtering
media become clogged and incapable of passing a sufficient volume of fluid, when
the machine is brought to rest and a spare basket substituted, the spent filters
being meantime replaced or cleaned. If the surface layer of the sawdust only
becomes gluey it may be freed by harrowing it, which is done by holding a chisel
or piece of wood or metal lightly in contact with it, traversing vertically, whilst
the basket is in motion. In the refining of badly made tallow many and various
impurities are extracted; very often a considerable quantity of glue-like substances
are present and the filtering substances become clogged very quickly unless the
precaution is taken of first re-rendering the fat and allowing it to settle in tanks
and drawing it off from the top for treatment. The lowermost layers are poor in
pure fat and are more troublesome to refine than the purer and lighter fluid. The
fabric band 10 will usually be found to be fouled before the sawdust.

page_text: When fats are being treated the water supply to the chamber 19 should be so
regulated by the inflow cock that the fat will be a little above solidifying tempera-
ture as it passes from the pipe 18 into the packages. To clean off any solidified
fat, hot water may be run into the chamber 19.
It is evident that said filtering apparatus is usable without the cooler.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. In the refining of fats and oils, forcing the same in a liquid condition through
a filtering bed of sawdust by centrifugal action, substantially as described.
2. For use in the refining of fats and oils, a centrifugal basket having a filtering
bed or belt of sawdust which is retained therein by a fabric lining, substantially
as described.
3. In a centrifugal machine of the hydro-extractor class, the combination with
the perforated basket of a belt of sawdust 12 forming a filter bed which is retained
in said basket by a lining 10, backed up (if necessary) by an openwork packing 9,
substantially as described for the purpose set forth.
4. In a centrifugal fat and oil filter of the kind described, the combination
with the rotating basket of an annular water chamber surrounding the same, for
cooling the spray of filtrate thrown off by said basket, substantially as described.
5. For use in cooling liquid fats and oils, the employment of a centrifugal
basket from the periphery of which said fats or oils are thrown in a fine spray
across an air space on to the wall of an annular cooler, the rotation of said basket
causing air to circulate in said air space and thereby cool said spray, substanțially
as described.
G. For use in the refining of fats and oils, the improved apparatus arranged or
operating substantially as herein described, and comprising a centrifugal basket
having a filtering bed of sawdust, which is retained therein by a fabric lining,
and an annular water chamber having its inner wall corrugated for the reception
of the filtrate issuing from the basket; a space being provided between the basket
and the annular chamber wherein air circulates and promotes the cooling of the
fats or oils.