An Improved Method or Process for the Extraction of Naphthaline and other Hydrocarbons from Coal-tar and similar Substances.
Year: 1893

page_text: Date of Application, 6th Sept., 1893
Complete Specification Left, 6th June, 1894-Accepted, 7th July, 1894
PROVISIONAL SPECIFICATION.
An Improved Method or Process for the Extraction of Naphthaline
and other Hydrocarbons from Coal-tar and similar Substances.
I, FRANK WILLIAM CLARK, of Illawarra, South Norwood Hill, in the County
of Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
4
My invention relates to the treatment of coal-tar and similar substances, and has
for its object the extraction of bydrocarbons such as naphthaline and benzol.
For this purpose, I mix coal-tar, or preferably the product or distillate obtained
in the process of separating pitch from coal-tar, with naphtha or other suitable light
hydrocarbon, and I pass the mixture through an evaporator which is maintained at
a sufficiently high temperature to drive off the spirit containing the naphthaline and
other hydrocarbons, which are conveyed by a suitable carrier, such as air or other
gas, into a condenser, the pitch or the other hydrocarbons remaining in the
evaporator being drawn off into suitable vessels or receptacles, and the spirit con-
taining the naphtbaline and other hydrocarbons from the condenser being collected
in other vessels or receptacles.
I sometimes use coal-gas as the carrier for conveying the naphthaline and other
hydrocarbons from the evaporator, in which case the coal-gas enriched by the
admixture therewith of the naphthaline and other hydrocarbons, instead of being
passed through a condenser, may be conducted through a suitable pipe or main to
the place or places where it is to be used for lighting or other purposes.
In carrying my invention into practice, I sometimes employ an apparatus which
comprises an evaporator wherein the liquid to be distilled flows through inclined
tubes surrounded by a heating medium, and also a condenser and means for
circulating a carrier, such as air, through the said evaporator and condenser for
the purpose of conveying the vapor or spirit from the evaporator to the
condenser.
I find it advantageous to carry on my improved method or process of treating
coal-tar or the like, by the aid of such apparatus, as follows, viz. :—I take naphtha
or other light hydrocarbon, produced by means of such apparatus or in any other
convenient manner, and I mix the naphtha or other light hydrocarbon with the
coal-tar, or product of the same, in such proportion as will impart the required
degree of fluidity to the tar or the like. I then introduce small streams of the
mixture into the tubes of the evaporator at their higher end and, at the same time,
apply to the evaporator sufficient heat to drive off the naphthaline or other hydro-
carbon which it is desired to extract from the tar or the like. The circulation of
the air or other carrier through the evaporator and condenser is maintained so that
the naphthaline or other hydrocarbon vapor is carried by the air or other carrier
into the condenser, in which it is condensed by cooling or by pressure or by both
combined. The liquefied naphthaline or other hydrocarbon is then drawn off from
the condenser into suitable vessels or receptacles.
I can, however, carry on my improved method or process by means of any other.
suitable apparatus.
Dated the 6th day of September 1893.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant

page_text: COMPLETE SPECIFICATION.
An Improved Method or Process for the Extraction of Naphthaline
and other Hydrocarbons from Coal-tar and similar Substances.
I, FRANK WILLIAM CLARK, of Illawarra, South Norwood Hill, in the County
of Surrey, Engineer, 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 :-
My invention relates to the treatment of coal-tar and similar substances, and has
for its object the extraction of hydrocarbons such as naphthaline and benzol.
. For this purpose, I take coal-tar, or the product or distillate obtained in the
process of separating pitch from coal-tar, and I mix or dilute the same with naphtha
or other suitable material, such as a light hydrocarbon or spirit, and pass the
mixture through an evaporator which is maintained at a sufficiently high
temperature to volatilize or drive off the spirit or other diluent together with the
naphthaline and other hydrocarbons which it is desired to extract from the tar_or
the like. The volatilized hydrocarbons are conveyed from the said evaporator by
means of a suitable carrier, such as air or other gas, into a condenser, the pitch or
other residue being drawn off from the evaporator into suitable vessels or receptacles,
and the distillate containing the naphthaline and other desired compounds, being
drawn off from the condenser and collected in other vessels or receptacles.
In some instances, I heat the said condenser to such a temperature that only the
heavier or less volatile hydrocarbons conveyed into the same will be condensed
therein; and I provide for conveying the lighter or more volatile hydrocarbons by
means of the aforesaid carrier into another condenser, in which these hydrocarbons
are condensed and from which they are drawn off into suitable vessels or
receptacles; or the second condenser is heated to a lower temperature than the first
condenser, so that some of the hydrocarbons conveyed into it will remain
uncondensed therein and will be conveyed by the said carrier from the second
condenser to a third condenser, and so on; the various compounds extracted from
the tar or the like, and also the naphtha or other liquid or diluent previously mixed
with the tar or the like, may thus be separately condensed and collected.
The air or other carrier is preferably circulated continuously through the
evaporator and condenser or condensers, as described in the Specification of former
Letters Patent granted to me and dated 1st March 1893, No. 4510, the said
condenser, or the last of the series of condensers, being provided with a loaded or
spring valve which is suitably adjusted to regulate or control the flow of the air or
other carrier into the evaporator in such a manner as to maintain the desired low
pressure or vacuum in the evaporator and the desired higher pressure in the
condenser or condensers.
I sometimes use coal-gas as the carrier for conveying the volatilized naphtha or
other diluent and the naphthaline and other hydrocarbons from the evaporator, in
which case the coal-gas enriched by the admixture therewith of the vapor of the
said compounds, instead of being passed through a condenser, may be conducted
through a suitable pipe or main to the place or places where it is to be used for
lighting, enriching or other purposes.
In carrying my invention into practice, I sometimes employ an apparatus such as
I have described in my said former Specification, comprising an evaporator wherein
the liquid to be distilled flows through inclined tubes surrounded by a heating
medium, and also a condenser or condensers, and means for circulating a carrier,
such as air, through the said evaporator and condenser or condensers for the
purpose of conveying the vapor or spirit from the evaporator to the said condenser
or condensers.

page_text: I can, however, carry on my improved method or process by means or any other
suitable apparatus if desired.
In treating coal-tar by my improved method or process, I find it advantageous
to proceed as follows, by the aid of the apparatus described in my said former
Specification, that is to say :-I mix with the coal-tar, naphtha or any other
suitable diluent, such as a light hydrocarbon or spirit produced as described in my
said former Specification or in any other convenient manner, in such proportions as
to impart the required degree of thinness or fluidity to the tar. I then introduce
small streams of the mixture into the tubes of the evaporator at their higher end,
and, at the same time, apply to the evaporator sufficient heat to drive off the
naphtha or other diluent together with the naphthaline, benzol and other compounds
.which it is desired to extract from the tar. The circulation of the air or other
carrier through the evaporator and condenser is maintained as described in my
said former Specification, so that the vapor of the naphtha, naphthaline, benzol and
other hydrocarbons is conveyed by the air or other carrier into the condenser, in
which it is condensed by cooling or by pressure or by both combined.
liquefied naphtha, naphthaline and other hydrocarbons are, from time to time,
drawn off from the said condenser into suitable vessels or receptacles, the pitch
eliminated from the mixture, or the residue containing the pitch, being, at suitable
intervals, drawn off from the evaporator into other vessels or receptacles.
The
The distillate obtained by this process is useful for carburetting air or enriching
gas, and for the production of dyes, and for other purposes.
When the naphtha or other diluent and the various compounds extracted from
the tar are to be broken up and separately collected, the mixture of tar and naphtha
or other diluent is passed through an evaporator to eliminate the pitch, but, instead
of the whole of the volatile products being condensed in a single condenser as above
set forth, a series of condensers is employed and sufficient heat is applied to the
first condenser of the series to prevent the condensation therein of the lighter or
more volatile of the hydrocarbons whilst permitting the condensation of the heaviest
or least volatile of the said hydrocarbons; the vapor from this condenser is then
conveyed into another condenser heated to a lower temperature, in which a lighter
hydrocarbon is condensed; and so on, the air or other carrier being circulated
through the series of condensers and being forced from the last condenser of the
series through a loaded valve into the evaporator. I am thus enabled to break up
or separate and collect the various hydrocarbons extracted from the tar, and also
the naphtha or other material previously used for diluting the tar.
In treating the product or distillate obtained in the process hitherto adopted for
eliminating pitch from coal-tar, I proceed in substantially the same manner as that
above described with reference to the coal-tar, using sufficient naphtha or other
diluent to impart the requisite degree of thinness or fluidity to the said product or
distillate. The heavier or less volatile products remaining in the evaporator are
drawn off therefrom at suitable intervals, whilst the more volatile products are
conveyed into a condenser or condensers and collected either together or separately
as may be desired.
It is obvious that, if desired, I can apply to the evaporator just a sufficient
degree of heat to drive off some of the lighter hydrocarbons together with the
naphtha or other substance used for diluting the tar or the like, leaving all the
other heavier hydrocarbons to be drawn off from the evaporator with the pitch,
if any.
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:-
First. The extraction of hydrocarbons from coal-tar by first mixing the tar,
before or after the elimination of the pitch therefrom, with a suitable diluent, such
as naphtha, and then subjecting the mixture to distillation.
Second. The herein described method or process, consisting in mixing coal-tar,

page_text: *before or after the elimination of the pitch therefrom, with a suitable diluent, such
as naphtha, and then passing the mixture through an evaporator and conveying the
vapor from the said evaporator by means of a suitable carrier, such as air or other
gas, into a condenser or condensers, for the purposes above specified.
Third. The herein described method or process which consists in mixing coal-
tar, before or after the elimination of the pitch therefrom, with a suitable diluent,
such as naphtha, and then passing the mixture through an evaporator and breaking
up or separating and collecting the volatile products by condensation in a series of
condensers maintained at different degrees of temperature.
Fourth. The modification of my invention wherein coal or other gas is passed
through the evaporator to take up the volatilized naphtha, naphthaline and other
hydrocarbons, and the enriched gas is then conducted through a suitable pipe or
main, substantially as, and for the purpose, above specified.
Dated the 5th day of June 1894
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.