Improvements in the Construction of Ammonia Stills.
Year: 1888

page_text: Date of Application, 12th Nov., 1888
Complete Specification Left, 6th Aug., 1889-Accepted, 14th Sept.,
1889
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Ammonia Stills.
I GEORGE EDWARD DAVIS of 301 Great Clowes Street, Manchester in the County
of Lancaster, Chemical Engineer and Consulting Chemist, do hereby declare the nature
of this invention to be as follows
My invention relates to those forms of stills known as column stills, in which the
ammoniacal liquid is treated in thin layers, with a current of steam, whilst moving
down a succession of trays or plates of which the still is partly constructed.
In the usual form of still, the steam issues from a short neck upon each tray or
plate and passes under a circular cap covering this neck, & passes out of serrations
around the periphery of the cap, through the liquid undergoing treatment.
One part of my invention relates to the construction of the aforesaid caps in order
to render their action more effective. In a circular cap, it is the periphery only
that is effective, and it is from the periphery alone that the steam escapes, so that to a
very great extent the length of the contour line of the cap determines the efficiency
of the still; all other things being equal. I therefore construct the caps covering
each neck of such a form that the outer edge in plan, is a deep sinuous curve, and
thus possesses a longer contour than any circular cap could possibly have, and the
whole of this outer edge is serrated so that the steam escapes the whole way round
the contour line. Stops are also cast upon the plate in order to compel the liquid to
travel the sinuous path, from the inlet to the outlet of each plate.
The other part of my invention relates to the method of building the column still so
as to reduce its cost very considerably.
I construct the still in one column containing six of the aforesaid trays and caps
for the purpose of liberating the volatile ammonia, and six similar trays and caps for
liberating the non-volatile ammonia, and between them is placed the lime box, through
which the steam from the lower tray is conducted by means of a pipe of wide bore.
In certain cases the lime box is placed much nearer to the top of the still, so as to
have fewer trays above it and more below it, while in other cases, such as when for
instance alkali waste is employed to decompose gas water, the lime box may be placed
with all the trays below it.
This arrangement in a single column reduces the cost very considerably and occupies
only one half the ground space required by stills of the ordinary construction.
The spent water after having been denuded of its ammonia is allowed to escape from
the lower part of the still by means of the U pipes mentioned in my specification
No. 15540 Nov. 14th 1887.
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1
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L1000
COMPLETE SPECIFICATION.
Improvements in the Construction of Ammonia Stills.
1, GEORGE EDWARD Davis, of 301, Great Clowes Street, Manchester, in the County
of Lancaster, Chemical Engineer and Consulting Chemist, do hereby declare the
nature of the said 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 those forms of stills known as column stills in which the
ammoniacal liquid is treated in thin layers with a current of steam whilst moving
down a succession of trays or plates of which the still is partly constructed and
consists partly of improvements based on my former invention described in the
Specification of my Letters Patent dated November 14 A.D. 1887, No. 15540.

page_text: In one of the forms of still referred to in the said Specification the steam issues
from a short neck upon each tray and passes under a circular cap covering this neck
and emerges from serrations around the periphery of the cap through the liquid
undergoing treatment.
One part of my invention relates to an improved construction of the aforesaid caps
in order to render their action more effective. In a circular cap it is the periphery
only that is effective. It is from the periphery alone that the steam escapes and so
comes in contact with the liquid undergoing treatment so that, to a very great
extent, all other things being equal, the length of the contour line of the cap determines
the efficiency of the still.
Another part of my invention relates to the building of a column still so as to
reduce its cost very considerably.
In order to enable my invention to be fully understood I will describe how it
may be carried into practice by reference to the accompanying drawing, in which
Figure 1 is a plan of one of the trays or plates of a column still showing my improved
construction of cap applied thereto.
Figure 2 is a sectional view of one of the trays, and
Figure 3 is an elevation partly in section of a complete column still constructed
according to my invention.
According to my invention I construct the caps A covering each neck a of such a
form that the outer edge in plan is represented by a deep sinuous curve, as clearly
shown at Figure 1 of the accompanying drawing, and the whole of this contour line
is serrated to allow of the escape of the steam and gases from underneath. A section
of one of these caps is shown at A, Figure 3, of the accompanying illustration
covering the short neck a before mentioned. Stops S are also cast upon the trays
or plates upon which the caps A rest as shown in Figure 1 in order to compel
the liquid to travel the sinuous path from the inlet to the outlet of each tray or
plate 6.
I construct the still in one column M in which a certain number of the aforesaid
trays and caps (preferably six) are employed for liberating the volatile ainmonia;
the said trays and caps are placed at the top or upper part of the still. A sufficient
number of similar trays and caps (also preferably six) are placed at the bottom of
the column M for liberating the fixed ammonia after it has been displaced from its
acid combinations by means of lime. Between these two series of trays and caps is
placed the liming vessel L through which the steam and gases are conducted from
the lower trays by means of the pipe B of wide bore thus heating the milk of lime
on its passage through it, the pipe bringing the liquor into the liming chamber I.
from the trays above and the overflow pipe D conducting the liquor from the liming
chamber into the trays below. The milk of lime is forced into the liming chamber
at the pipe G by any well known means such as by the aid of a hand-pump, steam-
pump or injector, and the lime is further heated and kept in agitation by the fixed
steam pipe E.
In certain cases, such as for example when the ammoniacal liquid' to be distilled
contains but little free ammonia, the line chamber Lis placed much nearer to the top of
the still so as to have a fewer number of trays above it and more below it, while in
some other cases, such as, for example, when alkali waste is to be used in the place
of lime, the liming chamber may be placed with all the trays below it.
The foregoing arrangement in a single column reduces the cost very considerably
and as it only occupies one half the ground space of the ordinary double column
still, it enables plant to be erected in places wherein the double column still could
not be erected, and, moreover, this method of construction does away with the
necessity of syphon seal pipes, except those by which the spent water is enabled to
leave the still at F.
The spent water, after having been denuded of its ammonia, is allowed to escape
from the lower part of the still by means of the U pipes shewn at F, Figure 3, in the
same manner as is described in my said former specification No. 15540, dated
November 14th 1887.

page_text: In order to lessen the number of joints in my improved still and so to reduce the
danger of leakage I prefer to cast the cylinder, tray, central neck, dip pipe and
stops all in one piece as is shown in Figure 2, but the method of casting the
cylinder as a separate portion and independent of the tray and its accessories may
also be adopted.
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 improved column still hereinbefore described and illustrated in the accom-
panying drawing and having each separate tray and cylinder cast in one piece or
separately as herein before described.
(2) The construction and use in connection with column stills of serrated caps, the
contour lines of which are sinuous, as is hereinbefore described.
(3) The employment of a gas and steam pipe, such as is shown at B of the accom-
panying drawing, running through the lime-vessel to carry the steam and gases from
the lower trays to the upper trays heating the milk of lime on its passage, substan-
tially as herein before described.
(4) The employment of the overflow pipe D for the purpose of carrying the
limed liquor from the lime-vessel to the trays below, substantially as hereinbefore
described.
Dated the
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.