Process of and Apparatus for Distilling Ammonia.
Year: 1886

page_text: Process of and Apparatus for Distilling Ammonia.
P:
I, WILLIAM CUTHBERT WREN, residing at 39 Lee Avenue, Brooklyn; in the
County of Kings and State of New York in the 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 :-
The object of my invention is to convert the gas produced by the distillation of
aqua-ammonia, into a pure anhydrous ammonia entirely free from watery vapor,
without requiring the use of compression pumps or mechanical devices of any kind
which as is well known are now generally employed in this art. The pure liquid
ammonia produced by this process is capable of being stored in the receiver in
which the conversion takes place, from which it may be drawn off for various uses
to which it is adapted.
Heretofore as is well known, the aqua-ammonia of commerce has generally been
distilled into gas in a closed retort or still, such still having to sustain little or no
pressure and after this distillation at a vacuum the gas or vapor is cooled, and then
compressed into liquid form by and with the aid of a pump or other mechanical
compressor The accompanying drawing shows an elevation of the entire apparatus
employed by me in carrying out my process..
A represents the still in which the aqua ammonia is vaporized which is made of
steel or boiler iron plates riveted together, its vertical dimension being much greater
than the horizontal diameter. The still contains a coil, of, pipe 2, through which
steam is admitted as hereinafter described through the steam pipe 3. A stand
pipe 4 extends from the top of the still to a height of say forty feet above the base,
communication between the interior of the still and steam pipe being regulated
by a valve 5, placed in the pipe just above the top of the still., A glass gauge, 6, is
mounted on one side of the still communicating with the interior, in order that the
height of the aqua ammonia in the still may be readily ascertained. "A pressure
gauge 7 of ordinary construction is also, connected with the still. A number of
test cocks, 8, are inserted into the still placed in a vertical row near the bottom
for the purpose of detecting the presence of ammonia, before drawing off the waste
water and condensed steam through the cock, 9, the latter if desired being connected
to a drain or sewer.
B, represents a feed pump which must be capable of delivering aqua-ammonia
into the still under or against a pressure of 150 pounds to the square inch. The
suction end of this pump is connected by a hose or pipe 10 to a cylinder 11, or
other suitable vessel containing a supply of aqua-ammonia., The discharge end is
connected by 'a pipe 12, having a cock, 13, with the interior of the still,, near
the bottom thereof. The still and all its connections, must be strongly made to be
capable of withstanding a very heavy pressure.

page_text: C represents any ordinary form of steam boiler which supplies steam to the coil.
A coil of pipe D, is mounted on a framework E so that its upper section may be
connected by a horizontal pipe, 14, with the stand pipe, 4. Connected with this
coil is a discharge pipe 15, which enters the top of a receiving tank F and extends
nearly to the bottom thereof, a cock 16, being placed in the pipe, 15, just above the
top of the receiver. The receiver has a glass gauge, 17, and pressure gauge, 18, as
shown and a draw off cock, 19, near the bottom.
G represents a water pipe through which water may be forced by any suitable.
means. The pipe extends above the coil D. where it is provided with a perforated
sprinkler 20, through which water, is allowed to drip upon the coil; the water
running down on the outside of the coil and into a trough, 21, connected to a waste
pipe 22. The main water pipe extends to a point above the stand pipe where it
has a cock, 23, which may permit water to drip down upon the upper part of the
stand pipe, and run down into a trough 24, connected by a branch 25, to waste
pipe 22. The upper part of the stand pipe and the entire coil, D, thus act as
coolers.
}
r
In the operation of distilling the ammonia from the water to be afterward
· converted into liquid anhydrous ammonia, the aqua-ammonia is first pumped into
the still by the feed pump, B, from the cylinder in which it is stored until the still
is about two-thirds full, as indicated by the glass gauge. The cock 13, in the
ammonia supply pipe, the cock, 5, in the stand pipe and the cock 16 in the dis-
charge pipe are open, all the rest being closed.
When the still is sufficiently full, the cock in the steam pipe is opened and boiler
steam is admitted into the steam coil in the still. The effect of this is to evaporize
the ammonia which escapes as a gas into the steam pipe while the greater part of
the water remains in the still.
At this stage in the process, the ordinary and usual practice is to draw off the
ammoniacal gas, cool it, and then convert it into a liquid in a separate vessel by a
pump or other mechanical compressor.
Instead of this however I keep increasing the heat by the admission of more
steam, which necessarily increases the pressure, until all the ammonia is driven
froin the water. It is a well known fact that the affinity of water and ammonia
for each other decreases' with an increase in heat, and since the ammonia gas being
the lighter, is always on top, as the pressure increases, any amount of water or
watery vapor which may rise in the stand pipe is condensed before reaching the
great height to which the stand pipe is carried as well as by the effect of the water
dripping upon the outside of the stand pipe as before described, and falls back into
the still leaving the ammoniacal gas to pass to the coil D.
It is there cooled by the water which is sprinkled upon the coil, and is then
forced by gravity and the pressure from the still through the discharge pipe and
into the bottom of the receiver. In this receiver by means of the continuous
pressure from the still throughout the pipes, it is liquefied; the pressure required
to liquefy ammoniacal gas being about six and one half atmospheres. Since the
discharge pipe extends nearly to the bottom of the receiver, a very small quantity
of liquefied ammonia will cover the mouth of the pipe so that a syphon is formed
and thereafter the gas will liquefy much more rapidly and readily than if the
discharge pipe terminated near the top of the receiver.
When it is desired to stop working the apparatus and the ammonia has been
entirely separated from' the water in the still, a fact which can be ascertained by
the series of test cocks in the still, the cock, 16, in the discharge pipe is closed
which will prevent any expansion of the liquid in the receiver. The draw off cock
in the bottom of the still may then be opened to draw off the waste water, and the
steam shut off from the coil, which closes the operation. A new supply of aqua-
ammonia may then be admitted to the still and more steam to the coil, until the
pressure gauges show that the pressure in the still and that in the receiver equal
each other when the valve in the stand pipe and discharge pipe are opened and the
formerly described operation is repeated.

page_text: Distillation can be continued for a time with a continuous forcing of aqua
ammonia, into the still, until the glass gauge shows that too much liquid has been
admitted when the water may be drawn off from below the ammonia, to the
necessary extent.
If the pressure in the still during the operation should fall at any time below
that in the receiver, either from lack of heat, or the presence of too much cold
ammonia in the still, then the cock, 5, should be instantly closed and remain closed
until the pressure gauge indicates a restoration of the pressure in the still, so that
it exceeds that in the receiver.
When the receiver is full of ammonia, it may be drawn off into a separate tank
or cylinder until the latter is full or until the pressure therein equals that of the
receiver.
The pressure of the gas above the receiver also tends to force the liquid out of
such receiver until the separate vessel is full.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The process of converting aqua' ammonia, into liquid anhydrous ammonia,
which consists in first vaporizing aqua-ammonia cooling the vapor, and discharging
it into a receiver, the vapor being under constant pressure during the entire
operation, substantially as described.
2. An apparatus for the manufacture of anhydrous-ammonia consisting of a still
provided with a steam coil for heating, and means for a continuous liquid supply,
a pipe leading from said still to a receiver and a cooler, located between the still
and receiver, substantially as described.
3. In an apparatus for manufacturing anhydrous-ammonia, the combination of a
retort containing a vaporizing coil, a vertical stand pipe leading from the top of
the still, a cooling coil and a receiver connected with the cooling coil, substantially
as described.
.
4. In an apparatus for manufacturing anhydrous-ammonia, the combination of a
vaporizing still, a vertical stand pipe, a conveying and discharge pipe, a cooling
coil connected to the still and also to the discharge pipe, a receiver, and a water
pipe having an outlet above the cooling coil, substantially as described.
5. In an apparatus for manufacturing anhydrous ammonia, the combination of a
vaporizing still, a cooling coil, a receiver, a steam pipe connecting the still and
cooling coil, a water pipe connected to a sprinkler above the cooling coil, said pipe
having an outlet above the stand pipe, and a discharge pipe connecting the cooling
coil with the receiver, substantially as described.
6. In an apparatus, for manufacturing anhydrous-ammonia, the combination of a
vaporizing still, a vertical stand pipe, a cooling coil, a receiver, and a discharge pipe
connecting the cooling coil with the receiver and extending nearly to the bottom of.
said receiver, substantially as, and for the purpose set forth.
7. The combination with the vaporizing still, of the steam coil within such still,
the stand pipe, 4, the draw off cock at or near the bottom of the still, and the test
cocks, 8, substantially as described.
8. The combination with the vapor conveying pipes, of the water pipe G, the
waste pipe 22, the trough 24, and the branch pipe 25, substantially as described.
Dated thie 95th dow of Men 1996