Improvements in Distillation and in Apparatus therefor.
Year: 1890

page_text: Date of Application, 5th Aug., 1890-Accepted, 18th Oct., 1890
COMPLETE SPECIFICATION.
Improvements in Distillation and in Apparatus therefor.
I ARTHUR WILLIAM ELLIS of 37 Queen Victoria Street in the City of London
Manufacturing Chemist, 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 improved apparatus for the distillation of liquids and.
an improved method of the application of indirect or enclosed steam thereto.
In the ordinary method of employing indirect steam it is usual to supply it by means
of a coil or its equivalent so arranged that it has a fall towards the outlet, which to
ensure circulation of the steam and for the escape of water of condensation superfluous
steam and air is more or less open to the atmosphere; thus there is a certain loss of
heat and, moreover on account of the fall usually given to this coil the depth of liquid
over the coil gradually increases towards the outlet and consequently uniform ebullition
does not take place along its entire length.
By my improvements I prevent this irregular and partial ebulition, and render
the whole of the upper surfaces of the pipes efficient by adopting the shape and
arrangement hereinafter described.
I avoid loss of heat by preventing the escape of steam from the outlets of the coils
and by causing the water of condensation to be returned to the boiler.
To effect this, the distillatory apparatus is placed at such a height above the
boiler supplying the steam that all the heating pipes, hereinafter called coils, with
which the still is provided (with the exception hereinafter mentioned) and the
outlets and fittings connected therewith have an uninterrupted fall to the main return
pipe Fig. 7. This pipe also has a fall to the boiler and enters it above the level
of the water and does not dip therein.
The form of still that I employ is that known as the tower or column still, as
shewn in elevation and in connection with the boiler, in Fig. 7 of the drawings
accompanying this Specification A being the lower portion, to which with regard to
the still itself, my improvements are confined, B, the upper portion, provided with
plates, trays or diaphragms, of any of the well known and suitable forms, or in lieu.
thereof coke or other suitable material, C the boiler, the main steam valve, & the
main steam supply pipe tttttt the steam inlet cocks u, u, u, u, u, u the outlet cocks
v, the main return pipe for water of condensation and the return valve.
In this
drawing F. 7 only 6 chambers are shewn but I do not confine myself to this number
as according to the requirements of the still the number may either be increased or
diminished.
This lower portion, of which Fig. 1 is a part elevation, with the upper cover and
coil removed; Fig. 2 a vertical section through D, D, Fig. 3 a plan of first chamber
(shewing coil), and Fig. 4 a plan of second chamber, I prefer to be square or
rectangular in shape & to consist of a receiving vessel a Figs. 1, 2, & 7, provided
with an outlet b, for spent liquid and an extra outlet Figs. 1 & over which is
superposed a series of chambers c, c, c, c Figs. 1, 2, & 7 communicating with each
other at opposite sides alternately, by the openings & Fig. 4, each chamber is
provided with a tray e Figs. 2, 3, & 4 to contain the liquid to be distilled and a steam
coil Figs. 2 & 3. The chambers are also provided with openings Figs. 1 & 2 for
the easy insertion or removal of the steam coils, with covers Figs. 1 & 2 and
stuffing boxes i Figs. 1, 2, 3, 4 & 7; the usual trial cocks, safety and vacuum valves
and guage glasses &c. are also provided but which for the purpose of this invention
it is unnecessary to describe.
I depart from the usual practice of providing openings of equal area between the
communicating chambers & 1 also avoid trays of equal depth.

page_text: These alternate openings d Fig. 4 are provided for the twofold purpose of permitting
the liquid undergoing distillation, which is supplied in a continuous & regular stream
from the upper portion of the still B Fig. 7 to flow or cascade over the lips Fig. 4
of each tray in succession, onto the one immediately, beneath, & also to allow of the
free upward passage of the vapours generated in each chamber; the direction of the
liquid is shewn in the drawings by an arrow thus → and the direction of the vapors
by an arrow thus.
If the distilling power of each tray is equal (as it is desirable that it should be) the
volume of vapour passing any tray above the lowest opening, is greater than that
immediately below it, & consequently if the area required at the top is furnished
indiscriminately to all the openings alike, the lower trays and coils must be
unnecessarily reduced in area & in distilling power. Again if the trays are all of
equal depth, the lower ones, having regard to the altered condition of the liquid as it
flows successively thereon cannot evaporate the same quantity, or do the same amount
of duty as those above them, for the reason pointed out in my Patent No. 13003 and
dated August 17th, 1889, that it is necessary in order efficiently to remove the last
trace of a volatile substance (in that case ammonia) that the supply of steam should be
proportionately increased as the liquid holding such matter in solution decreases in
strength.
This principle applies with considerably more force when indirect steam is employed,
in lieu of live or open steam, for whereas in the latter case the necessity for a pro-
portionately greater supply of heat in the lower chambers is only due to the fact that
the volatile portions of the liquid operated upon are gradually decreasing, (the density
of the liquid, in consequence of the admixture of condensed steam remaining approxi-
mately the same) it is not confined to this reason, when indirect steam is employed;
in this case the liquid operated upon not only continually decreases in the strength of
its volatile constituents but owing to the absence of water of condensation, its density
also increases as it descends from chamber to chamber, & its boiling point is raised.
1 therefore dispense with the openings in the first tray and provide in their place the
overflow pipes & Figs. 2 & 3 for the passage of the spent liquid to the receiving vessel
beneath.
l
These pipes should be raised above the bottom of the tray to a height corresponding.
with the depth of liquid desired to be retained in the tray say for example one inch
above the top of the coil; these pipes may dip into, and be scaled by the liquid
contained in the receiver, but in that case a third pipe Figs. 2 & 3 should also
be provided, this pipe should be raised a few inches above the liquid in the.
tray but should not dip into the liquid beneath. The outlet pipe for spent liquid &
Figs. 1, 2, & 71 dip into another pipe of larger diameter y Fig. 7 and cause it to be
constantly sealed to prevent the escape of steam. The second chamber I provide
with two openings & Fig. 4 one on each side of the short trough m Figs. 2 & 4
through which the inlet pipes n and outlet pipes o Figs. 2 & 7 pass alternately;.
these openings in a still of 6 feet square I make from 3 to 4 inches in width,
according to the consistency of the liquid and I increase the width of these openings,
one half inch in each of the succeeding chambers, that is to say, if the opening in the
second chamber is three inches the opening in the third chamber will be 3 inches
in. the fourth chamber 4 inches and so on. I also increase the depth of the second
tray and that of each succeeding tray, by one eighth of an inch, that is to say
supposing the liquid in the first tray to overflow at a height of one inch from the
top of the coil, I arrange that in the second tray it shall overflow at a height of
1 inch at the third at a height of 14 inch, and so on. With regard to the coils it is
most important that in whatever form they are arranged, a sufficient but not excessive
fall to the outlets o Figs. 2, 3 & 7 should be given, and permanently maintained.
With an insufficient fall the circulation of the steam is irregular and spasmodic and
an excessive fall occasions an unequal distillation by reason of the great difference.in
the depth of the pipes with the result that at the lowest part of the coil ebullition is
scarcely visible. I have found that a fall of about one inch in five feet of piping,
answers well, but with this fall in a coil or spiral of 50 feet, a convenient length for

page_text: the size of still above mentioned, the difference in level between the highest and lowest
point would be 16 inches, and the quantity of liquid necessary to cover it very
excessive for economical distillation. To avoid operating on such large quantities of
material and to ensure a rapid and regular ebullition over the whole surface of the
pipes I prefer to arrange them in the form of a "gridiron "Figs. 2 & 3, that is I
place a number of pipes parallel to each other and connect both ends of such pipes in
any suitable manner to two other pipes or cross pieces laid at right angles thereto,
one of these cross-pieces p Fig. 3 and Fig. 5 I call the inlet cross-piece to which at or
about the middle of its length is connected a short piece of pipe n Figs. 2, 3, & 7
(which I term the steam inlet) may be perfectly level, as the quantity of water of
condensation is here scarcely appreciable, but the outlet cross-piece Fig. 3 and
Fig. 6 I prefer to be so arranged that it has a fall at the bottom of inch each way
toward the middle, where the outlet pipe o Figs. 2, 3 & 7 is placed.
By this arrangement the gridiron proper being given one inch fall, in five feet,
toward the outlet, the whole of the piping of which it is composed, with the exception
of the inlet cross piece, bas the fall hereinbefore indicated and there is only the small
difference (supposing the pipes to be circular) of a little over one inch between the
highest and lowest point of the surface thereof; thus small quantities are acted upon
successively instead of a large bulk of liquid, and in consequence enormously increased
heating surfaces are obtained in a given space.
I prefer however that the pipes increase in the areas of their cross section from the
inlet cross-piece towards the outlet cross-piece; that is in place of ordinary cylindrical
pipes I prefer to employ pipes which are circular at the inlet end; but gradually
increase in their vertical diameter; while the horizontal diameter remains the same, or
nearly the same until they assume the shape of an oval at the outlet cross piece q
Fig. 3, and Fig. 6, the steam way of which is made to correspond; by this means,
while securing the necessary fall at the bottom of the pipes the upper heating surfaces
are level and equidistant throughout, from the surface of the liquid undergoing
distillation, hence a still more uniform & regular ebullition is ensured.
The most suitable depth of liquid that should be maintained above the coils, and
the pressure of steam to be employed, will of course vary, with the character of the
liquid undergoing distillation, but within limits the thinner the layer of liquid above
the coils and the greater the pressure of steam, the more rapid will be the distillation
but it is absolutely necessary that under no circumstances, must the depth of liquid be
so small, or the pressure & temperature of the steam so high as would admit of the
liquid operated upon assuming the spheroidal state. It is important for the more
perfect & successful working of this process that at the commencement of the opera-
tion, all air, as far as possible be expelled from the boiler, and the main pipes, coils
and fittings connected therewith; to do this effectually a certain amount of steain
must be allowed to pass also and it is better that this amount should be in excess of
rather than under, the quantity required; in order to avoid the inconvenience and loss
of heat that this escape of steam into the atmosphere would occasion, I proceed as
follows. At the highest point of the main steam supply pipes Fig. 7 I provide an air
cock a which is connected to the upper portion of the still B and at the highest point
of the main return pipe I also affix an air cock a¹ connected in the same manner.
Having expelled the air from the boiler by some suitable means (the main supply
valve Fig. 7, main return valve w, and the steam inlet cocks t, t, t, t, t, t, being
closed, and the air cocks & ¹, and outlet cocks u, u, u, u, u, u, being open), I
gradually and partially open the main steam valve r; the effect of this will be to
force the air contained in the upright part of the pipes immediately connected with
the boiler, and the horizontal pipe following it, together with some steam into the
upper portion of the still B Fig. 7 the air cock x is now to be closed; and the inlet
cocks t, t, t, t, t, t, commencing at the upper one, opened in succession giving a
sufficient interval between the opening of each to ensure as far as possible the complete
expulsion of the air from the coil which will enter the still through the air cock ¹.
The inclined portion of the main return pipe leading to the boiler now remains to

page_text: 5
be dealt with, but provided it is of moderate length the water of condensation formed
in the coils and connections above will in great measure have replaced the contained
air; but if this is insufficient this pipe should be provided with one or more small air
cocks in proportion to its length. When the air has been expelled, the air cock al is
to be closed and the return valve w opened; the circulation of steam will then
commence.
As a modification of the process, and in the construction of the apparatus herein-
before described, and in cases where a more thorough agitation of the liquid under
treatment is desirable. I adopt the arrangement shewn in Figures 8 & 9; Fig. 8 being
a vertical section & Fig. 9, a plan of one of the intermediate chambers. I cause the
steam & vapours generated in the first or lowest chamber (which is provided with a
gridiron as shewn in plan in Fig. 3 and in cross section Fig. 8), to pass through the
liquid contained in the second or intermediate chamber c Fig. 8 and I cause the
vapours generated in the third chamber to pass through the liquid contained in
the fourth chamber c2 Fig. 8, which arrangement I continue throughout the whole
series of chambers. I substitute for the rectangular openings d, d, Fig. 4 with which
each chamber in that case with the exception of the lowest chamber, is provided, two
overflow pipes k, k, Fig. 8 for the downward flow of liquid from chamber to chamber;
these overflow pipes must dip into and be sealed by the liquid contained in the
chamber beneath, and the lowest chamber should be provided with a communicating
pipe & Fig. 8. At the centre or at any convenient part of the tray e Figs. 8 & 9
forming the bottom of this intermediate chamber I provide a raised outlet t Fig. 8 for
the passage of the vapors generated in the chamber immediately beneath, over this
outlet is placed a cap or cover u Figs. 8 & 9 of sufficient size to allow a clear space
above and around such outlet equal to the area thereof. To this cap are affixed
several pipes Figs. 8 & 9 radiating from the centre, or a coil or coils, pierced. with
many small holes, or any other of the well known and suitable means of efficiently
distributing the steam and vapors through the liquid may be adopted.
I attach to the sides of each intermediate chamber an outlet pipe Figs. 8 & 9 for
the upward passage of steam and vapor, and I connect these to an upright pipes
Fig. 8 which gradually increases in diameter in proportion to the number of chambers
employed; this upright pipe is connected to the upper portion of the still B Fig. 7
immediately below the trays diaphragms, or their equivalents with which the still is
provided.
As a further modification, & one particularly applicable to small stills and where the
gridiron form of heating would be inconvenient, I substitute for the gridiron a series
of steam cases as shown in vertical section in Fig. 10 and in plan in Fig. 11. I make
thesc steam cases c Figs. 10, 11, & 12 of two or more plates connected together and
sufficiently strengthened by rivets Figs. 10, 11 & 12 or by other suitable means to
resist the required pressure of steam with which they are to be supplied. In the case
of square or rectangular steam cases c Figs. 10, 11, & 12 I bend the-upper plate to
the desired height in order to form the sides of the tray d Figs. 10, 11, & 12; but on
one side I bend it only sufficiently to retain the desired depth of liquid which depth
should gradually increase in each tray from the lowest tray upwards; these lower
sides of the trays form the lips Figs. 10, 11, & 12 over which the liquid falls into the
tray immediately beneath.
To the bottom plate of the steam cases I give an incline or fall toward the outlet
pipes o Figs. 10 & 12 for the better passage of water of condensation and I also
gradually reduce the area of the steam cases from the bottom one upwards in order
that the spaces between them & the casing of the still for the upward passage of steam
and vapor and the downward flow of liquid shall be proportionately increased. I
prefer to supply the steam to the highest steam case, by means of a bend e Figs. 10
& 11 passing through the sides of the still and I connect the steam cases with each
other at opposite sides alternately by means of short lengths of pipe ƒ ƒ ƒ· ƒ
Figs. 10 & 11:
The pipe for the return of water of condensation to-the-boiler-o-Fig. 10 connected

page_text: to the lower steam case may with advantage pass through a stuffing box affixed to the
bottom of the receiver a Fig. 10-it is. necessary that the trays be fixed and supported
by some suitable means in such a manner that their upper surfaces are level.
In adapting steam cases to larger stills, where on account of their combined weight,
it would be inconvenient first to connect a series together, and then place them in the
still, it is preferable that the inlet & outlet pipes of each should be connected to an
exterior main as in the case where the gridiron arrangement is used. In this case
the inlet pipe n Fig. 12 may with advantage be attached to the upper plate of the
steam case c Fig. 12 by means of a short bend; the form of the still may be the same
as in Figs. 1 & 2 with the exception that in place of the trays a narrow ledge h
Figs. 12 & 13 at two opposite sides of the still and at right angles to the opening g
Figs. 12 & 13 should be provided and upon which the steam cases can slide and he
supported in their position.
If it is thought desirable to give the liquid to be distilled a more lengthy passage
over the trays than that obtained in a thin sheet the trays may be so constructed that the
liquid flows in a zig-zag or circuitous channel; but this is of doubtful advantage as
the depth of the layer of liquid is necessarily increased, & as this method has been
long known I make no claim for its introduction.
By adopting the apparatus and process hereinbefore described the following
advantages are obtained.
I. A regular and uniform distillation of the liquid operated upon, for the reason
firstly, that the upper heating surfaces of the steam pipes or cases are level conse-
quently the layer of liquid above them is of the same depth throughout and offers
uniform resistance to the passage of bubbles of steam formed on the surface of the
pipes or cases, secondly, both the main supply pipe from and the main return pipe, to
the boiler being connected directly therewith, the pressure of steam is approximately
equal in all parts of the coils or cases, which is not the case in a continuous coil with
its outlet more or less open to the atmosphere.
II. Heat is more efficiently applied to the liquid and the last traces of volatile
matters are more easily recovered, for the reason that as the material operated upon
is reduced in volatile strength, and increases in density and boiling point, the layers
of liquid are reduced in depth, & consequently ebullition is more easily set up and
maintained.
III. Economy in fuel, for the reasons, firstly, that with the exception of a small
amount of heat lost by radiation from external pipes and fittings the whole of the
heat generated in the boiler is either utilized in the still or returned to the boiler.
Secondly, practically no cold or fresh feed water is required, for in exact proportion
to the amount of steam used, so is the equivalent proportion of water of condensation
returned automatically to the boiler at a high temperature. Thirdly, absence of
incrustation for the reason that provided the boiler were once filled with pure water it
would be continuously supplied with distilled water & no appreciable deposit could
take place.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is:-
I. The improved apparatus for use in the distillation of liquids substantially as
herein before described and shown in Figs. 1, 2, 3, 4, 5, 6, & 7 of the-drawings
accompanying this Specification.
II. The modifications of the said apparatus hereinbefore described and shewn in
Figs. 8, 9, 10, 11, 12, & 13.
III. In the process of distillation the application of indirect or enclosed steam to
each of a series of vessels or trays placed one above the other in the manner herein-
before described, the water of condensation being returned to the boiler substantially
as and for the purposes described.
IV. In the process of distillation the application of indirect or enclosed steam to
layers of liquid gradually decreasing in depth as the liquid increases in density.

page_text: V. In the process of distillation the application of indirect or enclosed steam to.
liquids contained in a series of trays provided with a gridiron arrangement of pipes,
the heating surfaces gradually increasing as the liquid operated upon becomes of
greater density.
VI. In the process of distillation the use of pipes increasing in sectional area
substantially as and for the purposes described.
VII. The combination of the apparatus hereinbefore described with the upper
portion of a still of any of the well known and approved forms.
Dated this Fifth day of August 1890.
ARTHUR W. ELLIS.