Improvements in the Method of Refining Vegetable Oils.
Year: 1893

page_text: Date of Application, 6th June, 1893-Accepted, 8th July, 1893
COMPLETE SPECIFICATION.
Improvements in the Method of Refining Vegetable Oils.
I, GEORGE WASHINGTON SCOLLAY, Chemist, a citizen of the United States,
of No. 100 Maiden Lane, in the City of New York, in the County and State of
New York, United States of America, do hereby declare the nature of my
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My present invention relates to the refining of vegetable oils and it consists of
certain novel methods pointed out in the concluding claims.
For the purpose of enabling others skilled in the art to understand my invention
and to practice it in the manner at present preferred by me, I will describe how it
may be applied in the purification of linseed oil; but it will be understood that my
invention may be employed in the purification of other analogous oils and that
various modifications may be adopted without departing from the spirit and without
exceeding the scope of the claims.
It is a well known fact that continued boiling of crude linseed oil, or linseed oil
from which the mucilage, etc., has been removed causes it to grow darker and
darker. I have, however, discovered that the first effect of raising linseed oil to
the boiling point is to discharge the yellow color or a portion of it and to separate
whatever mucilage, etc. are present; that if the temperature be reduced below the
effective point when this result is accomplished a white or lighter oil is obtained
from which the precipitated mucilage (if any there be) may be separated in the
well-known ways; but if the temperature be continued longer at the effective point
the oil grows darker and darker. The experience which I have thus far obtained
seems to teach that the briefest exposure of the oil to the effective temperature
(which is about boiling point) accompanied by the most rapid rise of temperature to
and fall of temperature from this point produces the whitest oil, so that I am led
to believe that the desired changes are effective almost, if not quite, instantaneously
when the proper temperature is reached, and that the deteriorating effects begin
immediately thereafter if the temperature be continued. Whether these deductions
from the facts observed be true or not, certain it is that a brief exposure of the oil
to about the boiling temperature causes more or less of the color to be discharged,
while further exposure to such heat will make the oil darker; and if the
mucilage, etc. have not been removed these will, at the same time, be separated.
The principal feature of my present invention as I now understand it, therefore,
consists of heating the oil to the effective temperature, thereby discharging more or
less of the natural color of the oil and separating the mucilage, if it contains any,
and then reducing it below thee ffective temperature before the natural color of the
oil has been all recovered. In this way an oil of improved color will be obtained,
whether that so treated be crude oil, or oil from which the mucilage, etc. has been
eliminated. Any suitable means of accomplishing this result may be employed, the
invention being of methods of treatment independent of the apparatus or appliances
used.
As I have before observed I have obtained the best results by a rapid rise and
fall of temperature to and from the boiling point. As to avoid boiling over heat
must be cautiously applied to crude linseed oil in an open vessel, I prefer to confine
the oil during treatment, subject to a pressure high enough to overcome this
difficulty. Heat may then be applied as rapidly as desired.
As an illustration of how my invention may be practiced in refining linseed oil, I
will now describe the manner in which I at present prefer to work it, although it
will be understood that my invention may be worked in other ways.
A tank containing oil to be refined is located at a suitable elevation and from

page_text: this tank a small pipe-having say, a calibre of one inch-leads downward and
passes through a sand-bath or other device for maintaining an even or regulated
temperature. The oil leaving the tank in a continually flowing stream is, while
under pressure, heated in passing through the sand-bath to a temperature, say, from
615 to 690° F. Leaving the sand-bath the high heat is rapidly given up to the
surrounding atmosphere or to other cooling media and the oil is led to the settling
tanks where it is preferably kept at about 150 F. until the mucilage, etc. have
settled, when the refined oil is drawn off. If the oil is discharged into the settling
tank before its temperature has fallen below 212 F. the steam generated by the
elimination of water from the mucilage will not have been condensed before it has
had an opportunity to escape. By regulating the bore of the pipe, the length of
pipe exposed to heat and the rate of flow of the oil through the pipe, the time
during which the oil is exposed to the heat of the sand-bath and the rapidity of its
rise and fall can all be regulated as experience may direct.
By the term "effective temperature" I mean the temperature at which the
changes described take place.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The method of refining linseed and analogous oils, consisting in heating the oil
to the point where the natural color of the oil is discharged and then reducing the
temperature before the natural color of the oil has been recovered.
2. The method of refining crude linseed and analogous oils, consisting in heating
the oil to the point where the natural color of the oil is discharged and the
mucilaginous and other impurities separated and then reducing the temperature
before the natural colour of the oil has been recovered.
3. The method of refining linseed and analogous oils, consisting in heating the
oil while under pressure to the point where the natural color of the oil is discharged
and then reducing the temperature before the natural color of the oil has been
recovered.
Dated this 6th day of June 1893.
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicant's Patent Agents.