IMPROVEMENTS IN EVAPORATING LIQUIDS, AND IN THE APPARATUS TO BE EMPLOYED THEREIN
Year: 1872

page_text: LETTERS PATENT to Robert Andrew Robertson, Manager for James
Duncan, Engineer, of Clyde Wharf, Victoria Docks, in the County
of Essex, for the Invention of "IMPROVEMENTS IN EVAPORATING LIQUIDS,
Sealed the 30th July 1872, and dated the 15th March 1872.
PROVISIONAL SPECIFICATION left by the said Robert Andrew
Robertson at the Office of the Commissioners of Patents, with his
Petition, on the 15th March 1872.
I, ROBERT ANDREW ROBERTSON, Manager for James Duncan,
Engineer, of Clyde Wharf, Victoria Docks, in the County of Essex, do
hereby declare the nature of my said Invention for "IMPROVEMENTS IN
EVAPORATING LIQUIDS, AND IN THE APPARATUS TO BE EMPLOYED THEREIN," to be
as follows:-
This Invention relates to an improved method of producing evaporation
in vacuum pans or vessels for evaporating liquids, and is more especially
applicable to the evaporation of cane juice and other saccharine liquids.

page_text: According to my Invention I substitute for the air pumps or other
exhausting apparatus usually employed in connection with vacuum
evaporating pans or vessels an exhausting apparatus, known as the
Siemens' steam jet exhauster, and described in the Specification No. 3255,
A.D. 1870. Other exhausting apparatus the action of which depends
upon the induction action upon air or vapour of a jet or jets of steam,
may be used when the exhaust from the said apparatus is employed in
the manner herein-after described.
In carrying out my Invention I propose to connect the steam
exhauster or ejector, whether of the Siemens' construction or otherwise,
to the vacuum evaporating vessel in such a manner as that the steam,
air, and vapour which are exhausted from the evaporating vessel shall
after mixing with the exhausting steam jet or jets of the exhauster pass
along with such steam through heating coils or tubes situate in the
lower part of the evaporating vessel to which the exhauster is applied, or
shall pass through the heating coils or tubes of one or more of a series
of evaporating vessels, so that the heat of the combined stream of steam,
hot air, and vapour shall be utilized in effecting the process of
evaporation.
It is proposed in some cases to combine a condenser with the
evaporating vessel and steam jet exhauster or ejector in such a manner
that the steam or vapour from the evaporating vessel shall pass into it,
and be either wholly or partially condensed before reaching the steam
jet exhauster or ejector, leaving the air and any remaining vapour only
to be acted upon by the exhauster, the heat of the combined stream of
steam, air, and vapour being utilized as before described for boiling
or evaporating.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Andrew Robertson in the Great Seal
Patent Office on the 5th September 1872.
Patent Office on the 5th September 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERTS
ANDREW ROBERTSON, Manager for James Duncan, Engineer, of Clyde
Wharf, Victoria Docks, in the County of Essex, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of March, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Andrew Robertson, Her special
license that I, the said Robert Andrew Robertson, my executors,
administrators, and assigns, or such others as I, the said Robert
Andrew Robertson, my executors, administrators, or assigns, should
at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN EVAPORATING LIQUIDS, AND IN THE APPARATUS
TO BE EMPLOYED THEREIN," upon the condition (amongst others) that I, the
said Robert Andrew Robertson, my executors or administrators, by an
instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert Andrew Robertson, do
hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that
is to say:
This Invention relates to an improved method of producing evapora-
tion in vacuum pans or vessels for evaporating liquids, and is more.
especially applicable to the evaporation of cane juice and other
saccharine liquids.
According to my Invention I substitute for the air pumps or other
exhausting apparatus usually employed in connection with vacuum.
evaporating pans or vessels an exhausting apparatus, known as Siemens'
steam jet exhauster, and described in the Specification No. 3255,
A.D. 1870. Other exhausting apparatus the action of which depends
upon the inductive action on vapour of a jet or jets of steam may be
used when the exhaust from the said apparatus is employed in the
manner hercin-after described.

page_text: In carrying out my Invention I propose to connect the steam
exhauster or ejector, whether of the Siemens' construction or otherwise,
to the vacuum evaporating vessel in such a manner as that the steam,
air, and vapour which are exhausted from the evaporating vessel, should,
after mixing with the exhausting steam jet or jets of the exhauster, pass
along with such steam through heating coils or tubes situate in the
lower part of the evaporating vessel to which the exhauster is applied,
or shall pass through the heating coils or tubes of one or more of a
series of evaporating vessels, so that the heat of the combined stream of
steam, hot air, and vapour shall be utilised in effecting the process of
evaporation.
It is proposed in some cases to combine a condenser with the
evaporating vessel and steam jet exhauster or ejector in such a manner
that the steam or vapour from the evaporating vessel shall pass into it,
and be either wholly or partially condensed before reaching the steam
jet exhauster or ejector, leaving the air and any remaining vapour only
to be acted upon by the exhauster, the heat of the combined stream of
steam, air, and vapour being utilized as before described for boiling or
evaporating.
And in order that my said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose'
shall refer to the several Figures on the annexed Sheets of Drawings,
the same letters of reference indicating corresponding parts in all the
Figures.
Figure 1 (Sheet 1) of my Drawings represents a longitudinal vertical
section of a sugar evaporating vacuum pan with my improvements
applied thereto, and Figure 2 is a corresponding end elevation of the
same.
A is the pan, by preference of a cylindrical form closed air-tight, and
having an outlet B at the top for the exhaustion of the air and the
withdrawal of the vapours of evaporation. Round this outlet mouth-
piece B there is place da cylindrical baffle plate C, which is secured to
and is dependent from the chamber or dome D. This dome is provided
outlet F leading direct
with an air-tight lid or cover E, and has a lateral
into one end of a steam jet exhauster G, by preference a Siemens' steam
jet exhauster as shown in my Drawings. a is the annular steam jet of
the exhauster, into which live steam, that is to say, steam under pressure

page_text: from any generator) is conveyed by the branch pipe b; c is a conical
regulator worked by the spindle and hand wheel d and screw e for
adjusting the size of the annular orifice of the Siemens' jet. The
opposite end of the body of the steam jet exhauster G is secured to a
pipe or conduit H by preference made to widen or expanded down-
wards, which conduit is secured at its lower end to the top of a chamber
at I, formed outside the end of the pan A.; a somewhat similar chamber
I¹ is also formed outside the opposite end of the pan, and into these two
chambers open the ends of a number of heating tubes or coils K, K,
extending horizontally from end to end of the vacuum pan A, at the
lower part thereof so as to be always covered by the syrup or other
liquid to be evaporated. The chamber I is subdivided by a diaphragm
or horizontal partition i, which is attached to or formed on the front
plate or cover, or otherwise arranged, its object being to separate one,
two, or more of the upper rows of tubes K from the lower ones as
herein-after explained; L, L, are pipes for the escape of the condensed
steam which may collect in the bottoms of the chambers I, I'; M is the
main discharge aperture of the pan. In using this apparatus the steam
is turned on and the jet started, whereupon an exhausting action is
instantly commenced behind the jet, to which consequently the air and
vapour from the interior of the vacuum pan rush as shown by the
arrows, such air and vapour being then directed along with the live
steam issuing from the annular jet through the body of the exhauster,
and down the pipe or conduit H into the upper part of the chamber I,
whence it passes through the two upper ranges of tubes K into the
chamber I', and returns once more through the liquid in the pan by the
lower ranges of tubes K back into the lower part of the chamber I, and
finally escapes to a chimney by the outlet N.
Figure 3 (Sheet 2) represents a side elevation and partial section of
an evaporating pan in combination with a condenser and steam jet
exhauster supposed to be placed, as is frequently the case, on a floor in a
building at such a height from the ground that the condensing water in
which the vapour from the pan has been condensed can be discharged
against the vacuum without the aid of a pump. Figure 4 is a corres-
ponding plan of the same arrangement.
A is the evaporating pan
which I have here shewn of an oval or egg-shape, but which may be of
a cylindrical or any other suitable form; B is the outlet for the air and
vapours of evaporation from the pan A. This outlet is provided with

page_text: an annular baffle plate and chamber or dome D similar to that herein-
before described and fitted with an air-tight cover E; O is a pipe which
connects the chamber D with the condenser P, and extends into the
interior of the latter to within a short distance of the bottom thereof;
Q is the injection pipe, and R the discharge outlet for the condensing
water. The air and vapours of evaporation from the pan A pass through
the pipe O into the condenser, where they become partially condensed
before reaching the steam jet exhausters G, G, leaving only the air and
any remaining vapour to be acted upon by the exhausters, from which
such air and vapours pass through the jet pipes S into the coils T in the
pan A for the purpose of heating the contents thereof as in the before-
described arrangements. I propose to apply this mode of exhausting
and producing evaporation in vacuum evaporating pans or vessels not
only to single pans or vessels but also to combinations of such pans, two
of which combinations are herein-after described.
Figure 5, Sheet 2, is a side elevation; Figure 6, an end view; and
Figure 7, a plan shewing two vacuum evaporating pans of a similar
construction to that shewn on Sheet 1, arranged to work in connection
with one another, and having the same letters of reference.
The action of this arrangement is as follows :—In pan A into which
the liquor to be evaporated is first drawn or run a vacuum equal to say a
column of mercury of three to four inches is maintained by the steam
jet exhauster G, and by means of exhauster G¹ as high a vacuum as is
found to be practicable is maintained in the pan A¹, which obtains its.
supply of liquor for evaporation from the pan A in an already partially
concentrated state, and completes the concentration to the desired point.
The exhausters G, G³, direct their combined streams of air, steam, and
vapour by the pipe H' into one conduit H. leading to the pan A' through
the heating tubes of which they pass and repass first, and then pass by
the conduit N¹ to the heating tubes of the pan A¹, after traversing
which the air and any remaining vapor may either be utilized for
heating purposes, or allowed to escape into the atmosphere. I propose
also in some cases to pass the vapours given off by the liquor evaporated
in the pan A through the heating coils or tubes of the pan A¹ before
they reach the exhauster G, and to pass the vapour from the liquor in
the pan A¹ through a suitable liquor heater, or if found desirable through
a condenser before reaching the exhauster G¹, by which means the work
to be done by the exhausters will be much reduced. In this arrange-

page_text: ment the combined streams of air, vapour, and steam from the two
exhausters will be utilized in the pan A.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent, is,-
First. The application and use to and in the forming of a vacuum or
partial vacuum in a vacuum evaporating pan of a Siemens' steam jet
exhauster or exhausters, substantially as herein-before described.
"
Second. The application and use of a Siemens' or other steam jet
exhauster or exhausters for producing a vacuum or partial vacuum in an
evaporating vessel when the live steam of the jet and the air and vapour
exhausted from the pan are directed through heating coils or tubes in
the same or in one or more adjoining pans, substantially as and for the
purpose herein-before described.
Third. The combination of a condenser with a vacuum evaporating
vessel or pan, or combinations of such pans, and one or more steam jet
exhausters or ejecters, substantially as and for the purpose specified.
In witness whereof, I, the said Robert Andrew Robertson, have
to this my Specification set my hand and seal, this Fourteenth
day of August One thousand eight hundred and seventy-two.
ROBERT ANDREW ROBERTSON. (L.s.)