IMPROVEMENTS IN THE PRO- DUCTION OF AMMONIA ANHYDRIDE
Year: 1876

page_text: LETTERS PATENT to Farnham Maxwell-Lyte, of 14, Essex Street, Strand, in
the County of Middlesex, for the Invention of "IMPROVEMENTS IN THE PRO-
DUCTION OF AMMONIA ANHYDRIDE."
Sealed the 1st June 1877, and dated the 13th December 1876.
PROVISIONAL SPECIFICATION left by the said Farnham Maxwell-Lyte at
the Office of the Commissioners of Patents on the 13th December 1876.
FARNHAM MAXWELL-LYTE, of 14, Essex Street, Strand, in the County of Middle-
"IMPROVEMENTS IN THE PRODUCTION OF AMMONIA ANHYDRIDE"
sex.
My Invention relates to the production of liquified ammonia anhydride on a
commercial scale for various purposes, and consists in certain improvements in the
process of producing liquified ainmonia gas, whereby the same is obtained in an
absolutely anhydrous condition.
My Invention consists, first, in the application and employment of quicklime for
the purpose of absorbing the last traces of aqueous vapor contained in the
ammonia. This dehydration by means of quicklime may either be a continuation
of the process of distillation, or preferably it may constitute a separate and distinct
operation, and be effected in combination with other means for conducing to the
same result. In the first case the ammonia distilled in any of the ordinary
apparatus now in use for the purpose is received from the ordinary condensing coil,
and preferably passed through a special cooler, wherein almost all the aqueous
vapor is condensed; the ammonia gas is then passed over quicklime contained in
a suitable vessel. The quicklime abstracts from the ammonia gas the last traces of
water which it contains, and the ammonia gas is finally condensed to a liquid state
in a properly constructed vessel by the application of artificial cold and its own
pressure, whereby it may be obtained in a really anhydrous condition.
When the dehydration of the ammonia is effected at a separate operation from
the distillation I may render the ammonia anhydrous by a process which I term a
second rectification, with or without the use of quicklime to assist in removing the
last traces of water. This process constitutes the second feature of my Invention,
and consists in distilling or rectifying the ammonia at a temperature below that at
which any but insignificant traces of aqueous vapor can pass off with the ammonia.
Price 4d1

page_text: I take the ammonia still containing aqueous ainmonia as it comes from the still and
allow it to evaporate in a suitable vessel maintained at a inoderate temperature,
say, for instance, 15° to 20° cent., or about that of the atmosphere. At such
temperatures but insignificant quanities of aqueous vapor accompany the aminonia
anhydride. This evaporating vessel is hermetically connected with another receiving
or condensing vessel maintained in a much lower temperature. By thus establish-
ing a difference of temperature in the two vessels the ammonia is evaporated in the
one and passes over to the other, where it is liquified by the low temperature and
its own pressure, the water remaining in the evaporator. If perfect dehydration is
desired a quick lime drying vessel is interposed between the evaporator and the
condenser to abstract the last traces of water that may be contained in the am-
monia, which is then received in the condenser in a perfectly anhydrous condition.
My Invention consists, thirdly, in effecting this second rectification by esta-
blishing a difference of pressure in the evaporator and condenser instead of a
difference of temperature, as above described, or in employing both methods in
combination with or without the use of quicklime. In this case I interpose a
suitable forcing pump between the evaporator and receiver or condenser, and by
pumping I establish a difference of pressure between the evaporator and the con-
denser, whereby the ammonia anhydride alone is evaporated and transferred from
the evaporator to the condenser (leaving the aqueous ammonia behind), and is
there liquified by its own pressure. This operation is greatly facilitated by
combining the employment of the pump with the method previously described
under the third head of the Invention, or by interposing between the evaporator
and the pump, first, a vessel artificially refrigerated to condense the greater part of
the aqueous vapor passing off with the ammonia; and, secondly, a quicklime
drying vessel to absorb the last traces of such vapor which may have passed the
cooler uncondensed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Farnham Maxwell-Lyte in the Great Seal Patent Office on the 12th
June 1877.
FARNHAM MAXWELL-LYTE, of 14, Essex Street, Strand, in the County of Mid-
dlesex. "IMPROVEMENTS IN THE PRODUCTION OF AMMONIA ANHYDRIDE."
My Invention relates to the production of liquefied aminonia anhydride on a
large scale in an economical manner, so as to render it available commercially for
various purposes, and relates to certain improvements in the process of producing
liquefied ammonia gas, whereby the same is obtained in a sufficiently anhydrous
condition to admit of its advantageous employment for motive and other purposes.
My Invention relates, first, to the application and employment of quicklime in
the process of dehydrating aminonia gas, as herein after described, for the purpose
of absorbing the last traces of aqueous vapour contained in the ammonia, having
previously condensed the chief part of the said aqueous vapor by passing the gas
through a worm or suitable condenser. This dehydration by means of quicklime
may either be effected in the course of the distillation, or it may constitute a
separate and distinct operation. In the first case the ammonia distilled in any of
the ordinary apparatus now in use for the purpose, but which must be so con-
structed as to be tight and strong enough to support the pressure of the gas in all
its parts, is received from the retort or generator and passed through a cooler or
water condenser, wherein the greater part of the aqueous vapor is condensed, but
care must be taken that the temperature and pressure in this said condenser should
not be sufficient to effect the reduction of the ammonia gas to the liquid state; the
ammonia gas is then passed over quicklime contained in a suitable vessel. The
quicklime abstracts from the ammonia gas the last traces of water which it contains,
and the ammonia gas is finally condensed to a liquid state in a properly constructed.

page_text: vessel by the application of artificial cold and the pressure exerted by the tension
of its own vapour.
The dehydration of the ammonia may be effected by means of a second recti-
fication, with or without the use of quicklime, to assist in removing the last traces
of water. This process constitutes the second feature of my Invention, it relates to
a method of so distilling or rectifying the ammonia that the temperature is kept
below that at which any but insignificant traces of aqueous vapor can pass off.
I take the liquefied ammonia gas still containing aqueous ammonia and allow it
to evaporate in a suitable vessel maintained at a relatively low temperature, say,
for instance, 15° to 20° centigrade, or about that of the atmosphere; at such
temperatures ammonia anhydride evaporates rapidly, while but insignificant
quantities of aqueous vapour accompany it. This evaporating vessel is hermetically
connected with another receiving or condensing vessel maintained artificially at a
much lower temperature. The whole apparatus must be made of sufficient strength
to support the tension of the gas. By thus establishing a difference of temperature
in the two vessels the nummonia evaporates in the one and passes over to the other,
where it becomes liquefied by the low temperature and its own pressure, the water
remaining behind for the most part as aqueous ammonia in the evaporator. To
obtain these conditions the evaporator or generator may conveniently be immersed
in a current of water or in a large vessel of salt water maintained at ordinary
temperatures by a current of plain water flowing through or around it, while the
condenser is artificially kept cool and maintained at a lower temperature than the
evaporator. If perfect dehydration is desired a quicklime drying vessel may be
interposed between the evaporator and the condeser to abstract the last traces of
water that may be contained in the aminonia, which is then received and becomes
liquefied in the condenser in a perfectly anhydrous condition.
My Invention relates, thirdly, to a method of effecting this second rectifi-
cation by establishing differences of pressure in the evaporator and condenser
instead of differences of temperature as above described, or in employing both
methods in combination with or without the use of quickline. In this case I
interpose a suitable suction and forcing pump, or equivalent apparatus, between the
evaporator and receiver or condenser, and by pumping I establish a difference of
pressure between the said evaporator and the condenser. By this means the
ammonia anhydride evaporates and is rectified, becoming tranferred from the
evaporator to the condenser (leaving the aqueous ammonia which it may have con-
tained behind), and is there liquefied by its own pressure. In this case no
differential temperature between the evaporator and the condenser is required, but
both may be immersed in the same bath of water, which tends to maintain them
always at equal temperatures. The operation may be varied and rendered more
complete by the employment of the said pump with the method previously
described under the second head of the Invention, and interposing between the
evaporator and the pump, first, a vessel artificially refrigerated to condense the
greater part of the aqueous vapor passing off with the ammonia; and, secondly, a
quicklime drying vessel to absorb the last traces of any such aqueous vapour as may
have passed the cooler uncondensed.
Having now described the nature of my Invention, and the manner in which it
is to be performed, I declare that what I claim as my Invention to be protected by
the herein-before in part recited Letters Patent is,―
First. The use for effecting the dehydration of ammonia of the conjoined methods
of partially condensing the aqueous vapor carried over mechanically, or otherwise,
with the gas by passing the same through a condenser maintained at a temperature
low enough to effect its condensation, but not low enough to condense ammonia
anhydride itself to a liquid state, and the subsequent absorption of any remaining
aqueous vapor that may be contained in the gas by passing it over or through
quicklime placed in a suitable vessel, substantially as herein described.
Second. The use of the process of rectification applied substantially as herein
described to crude liquefied but still moist ammonia in close vessels under the

page_text: pressure of the tension of its own vapor, the operation being conducted at such
relatively low temperatures as to avoid as far as is practicable the volatilization
of any water or aqueous solution of ammonia that may be contained in the crude
liquid ammonia, while the requisite difference of temperature is at the same time
maintained between the evaporator and the condenser, so as to effect a process of
distillation and recondensation of the rectified ammonia anhydride, a lime
desiccator being in cases where it is advisable interposed between the generator or
evaporator and the condenser.
Third. The use of the process of rectification applied substantially as herein.
described to crude liquefied but still moist ammonia by means of differences of
pressure in the evaporator and the condenser, such differences being established by
the interposition of an exhausting and forcing pump, or equivalent apparatus,
between the evaporator and the condenser, either with or without the interposition
of a quicklime desiccator.
In witness whereof, I, the said Farnham Maxwell-Lyte, have hereunto set
my hand and seal, this Eleventh day of June, in the year of our Lord One
thousand eight hundred and seventy-seven.