Improvements in the Refining of Asphalt.
Year: 1898

page_text: Complete Specification Left, 15th Feb., 1898-Accepted, 9th Apr., 1898.
Improvements in the Refining of Asphalt.
I, WALTER SCOTT WILKINSON, of 1204 Charles Street North, Baltimore, Mary-
land, United States of America, Gentleman, 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:
;
This invention relates to improvements in the refining of asphalt, particularly
such as obtained from the well known Pitch Lake in the Island of Trinidad, con-
sisting of an emulsion containing a large percentage of salts, hydro-carbons,
earthy matter, and non-bituminous organic matter.
The methods heretofore universally adopted for refining or preparing such
asphalt for use as a base for asphaltic paving cements have employed fire heat,
applied either directly or through partially protecting surfaces of fire brick, to
the vessel containing such asphalt and the material thereby invariably produced
has been one inferior in all essential qualities to that produced by my process.
Crude asphalt is a very poor conductor of heat, and is therefore a difficult sub-
stance through which to diffuse heat. It can be stirred or agitated only with great
difficulty, and it contains a large percentage of water, which must be eliminated,
and about twenty-six per cent. of inorganic matter in suspension which it is desir-
able to retain evenly distributed throughout the mass. It becomes a question
therefore as to how with the least amount of fuel, and in shortest possible time,
this water can be driven off, and 'the inorganic matter retained in suspension, with-
out injuring the desiccated mass by heat. The foregcing conditions require, a
greater area of heating surface to a given quantity of asphalt than has heretofore
been allowed. This greater area I have discovered can be readily provided by the
use of sets or groups of steam pipes, passing through the body of asphalt to be
refined, contained, together with the pipes, in an open vessel which may be of any
desired dimensions, the number of groups and the consequent heating surfaces
being proportionately increased. The steam employed, which is generated in a
boiler of suitable form, is preferably conducted through jacketted pipes to the
heating pipes, and, after passing through them and in its passage distributing
its heat thoroughly and evenly through the mass of asphalt, is condensed and
returned to the boiler in the form of water. During this operation the asphalt is
agitated by jets of compressed air or by mechanical or other suitable means. This
operation brings almost every portion of the asphalt into contact with the heated
surfaces of the steam pipes, thereby breaking down the emulsion, setting free and
producing a rapid evaporation of the water from the asphalt, and at the same time
keeping the mass so mixed as to prevent the inorganic matter from settling, and
carrying down with it, valuable asphalt. The safety valve of the boiler being
set for a pressure which will afford the desired temperature, the surfaces of the
steam pipes are never heated to a temperature which will injure asphalt in the time
required to prepare it for use by this process, and therefore no coke is formed. By
the use of steam and the employment of a sufficient amount of heating surface, the
time required to refine at any one time a given amount of asphalt, can be reduced to
not over twelve hours.

page_text: In the accompanying drawings I have illustrated a type of apparatus adapted to
conveniently carry into practice the process described and in which alone my inven-
tion resides.
Of these drawings, Figure 1 is a view in side elevation of the entire apparatus.
Figure 2 is a transverse vertical section through the tank or kettle represented in
Figure 1, in the plane of the dotted line x-x of Figure 3. Figure 3 is a longi-
tudinal view otherwise similar to Figure 2, of the said tank, the section being
supposed in the plane of the dotted line y-y of Figure 2; and Figure 4 is a frag-
mentary or perspective detail of one of the perforated injection pipes and its
feeder.
A represents a boiler of any preferred character employed for the generation of,
preferably, high pressure steam, and B a furnace operating in connection with said
boiler.
C is an iron tank or kettle within which the crude asphalt is subjected to the
action of the steam from the boiler. This tank may be of any preferred construc-
tion, but is conveniently of that represented in Figures 2 and 3, in which it is
assumed to be incased in brick, the walls being formed with an inclosed air
space, c, and the upper opening of the tank (for it is necessarily an open tank)
being conveniently surmounted and inclosed by a splash board c. The tank is
supported upon framework or upon brickwork such as D, Figure 1, or otherwise.
E are the groups of steam pipes arranged within the tank, at such distances apart as
to admit of the introduction between and among them of the crude asphalt. Through
these pipes steam is caused to circulate, they being preferably continuously supplied
with high pressure steam from the boiler A, conveniently through a steam
conduit a, which leads from said boiler and is conveniently in connection with the
said various gangs of transverse feed pipes e, or other preferred connection. All
of the groups are connected preferably through transverse discharge pipes e* with
an outlet pipe e² for the water of condensation, which conveniently leads to a
chamber from which the condensed water may by means of a pump G, be
returned to the boiler through the return pipe g. Other means for returning this
water may, of course, be resorted to.
H is a series of suitable perforated injection pipes located in the bottom of the
tank, preferably below the steam pipes, and in communication through a series of
feeders h with an air supply pipe I, leading from an air pump J operated by a blow-
ing engine K, which together with the force pump G is conveniently supplied
through the pipe k with steam from a boiler not shown.
It will be observed that the arrangement of the various pipes where they lead
into the tank is not the same in all the figures; the difference, however, is one of
mere detail, and resorted to for clearer general illustration.
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 I make no
claim upon the apparatus as such, and the details of the apparatus shown may be
varied at the will of the constructor, but what I claim is:
The process of refining natural asphalt, which consists in subjecting it in an open
tank or vessel, in its crude state and under agitation, to the action of steam heat
disseminated throughout it, substantially as and for the purposes set forth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.