An Improved Method of Producing Ammonia.
Year: 1897

page_text: Date of Application, 1st Feb., 1897
Complete Specification Left, 26th Oct., 1897-Accepted, 22nd Jan., 1898
An Improved Method of Producing Ammonia.
I, CARL HERMANN MEHNER, of 5, Savigny Platz, Charlottenburg, in the Empire
of Germany, Doctor of Philosophy, do hereby declare the nature of this invention
to be as follows:
-
This invention relates to the well known production of ammonia from the
nitrogen of the air by bringing together atmospheric air and an incandescent
mixture of coal and an alkaline or earth-alkaline salt, preferably a carbonate,
whereby alkaline cyanide or earth-alkaline cyanide is formed which by treatment
with water vapour or steam is decomposed for developing ammonia with re-
formation of alkaline carbonate or earth-alkaline carbonate.
When carried out in the customary manner this method has certain defects.
Thus owing to the necessity for mixing the residue from the steaming with fresh
coal considerable time and work is spent. Moreover, the decomposition of the
cyanide within the reaction apparatus has also attendant defects. If, however,
the cyanide were removed from the reaction apparatus in order to pass it into a
special decomposing apparatus, the simple manufacture of ammonia would present
all the inconveniences and dangers of the manufacture of cyanide.
To obviate these and other inconveniences is the object of the aforesaid inven-
tion, which consists in modifying the method in such a manner that the cyanide
is obtained in the form of vapours, these vapours are conducted for the purpose
of condensation, over or through coal; the mixture thus consisting of condensed
cyanide and coal is treated with steam, thereby obtaining as a residue, a mixture
of coal and alkaline or earth alkaline carbonate which constitutes the product
started from in following operation.
In this manner the special mixing operation is dispensed with, and the decom-
position of the cyanide is rendered practicable outside the reaction chamber with-
out any need for removing it from the apparatus.
In the first part of the improved method the inventor avails himself of the well
known use of the electric furnace for producing cyanides from an alkali or an earth
alkali, or their carbonates, coal and nitrogen, employing an electric shaft furnace
provided with the electrodes in its lower part and conducting the air from above
to its charge which consists of a mixture of coal or coke and alkalies or earth
alkalies or their carbonates, and sinks gradually downward as the reaction proceeds.
According to this invention the cyanide vapours formed together with the gaseous
products are allowed to escape behind the zone of the electrodes, that is to say
within or directly below the zone of greatest heat through an air-tight passage
into a receiver which is filled with coal or coke and secured against the access of
air. In this receiver the cyanide vapours are allowed to condense in their passage
through the coal or coke. When the formation of cyanide discontinues and the
last cyanide vapours have been condensed, steam is conducted into the receiver or
condenser which is for this purpose provided with a steam inlet at a suitable point,
and the cyanide is decomposed into ammonia and alkaline or earth alkaline oar-
bonate. The former escapes together with the other gaseous products through a

page_text: discharge pipe provided for this purpose to the purifying and absorption apparatus,
whilst the latter remains behind mixed with coal (coke) and serves as a fresh charge
for the reaction furnace.
It is preferred to arrange the receiver above the furnace, so that the charge
obtained as described as residue in the condenser can be allowed to fall by its own
weight into the furnace on opening a slide or door.
Besides the advantage of obviating the inconveniences hereinbefore referred to,
the described method further possesses the special advantage of a very considerable
saving of heat. The raw materials used for the formation of ammonia' are very
cheap; the heat-which is here for the most part introduced as electrical energy-
alone is expensive and the amount of energy necessary to produce the high tem-
perature of the carbon is very great. As the very hot products of the reaction are
caused to pass over the coal or coke contained in the receiver a considerable portion
of the heat they carry with them is left behind in that part of the said coal or coke
first met with by them, which thus can be heated nearly up to the temperature of
the reaction before entering the' furnace.
-
For this reason it is preferred to conduct the operation in the receiver on thé
counter-current principle, that is to say, in such a manner that, in charging the
furnace from the receiver, at the point where the admission of the hot gases and
vapours into the latter takes place, there will always remain behind a quantity.
of the mixture of coal (coke) and regenerated alkaline or earth-alkaline carbonate,
as obtained in the development of ammonia, so that the hot current of gas and
vapours must first pass through part of said mixture before the cyanide vapours
are allowed to condense, so that condensation takes place only in the remoter
layers of the charge in the receiver. This may easily be obtained by imparting to
that portion of the receiver which communicates with the furnace such an initial
temperature as prevents condensation, and protecting it against cooling by radia,
tion. The portion of the mixture thus preliminarily heated is then passed into
the reaction furnace in order to charge the same, the layers following it take its
place, and a fresh quantity of coal (coke). is filled in at the top of the receiver.
It is also advisable to preliminarily heat the air to be conducted into the reaction
furnace, for which purpose use may also be made of the heat of the gases and
vapours passing from the reaction furnace, by conducting them, prior to their
passage into the receiver, through an air heating apparatus of any known con-
struction.
"
Dated this 1st day of Tintin 1007
3.
"
An Improved Method of Producing Ammonia.
"I, CARL HERMANN MEHNER, of No. 6, Savigny Platz, Charlottenburg, in the Empire
of Germany, Doctor of Philosophy, 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 the well known production of ammonia from gaseous
mixtures containing nitrogen, such as atmospheric air, producer gas and the like,
by bringing together said gaseous mixture with atmospheric air and an incan-
descent mixture of coal and an alkaline or earth-alkaline salt, preferably a car
L
35

page_text: bonate, whereby alkaline cyanide or earth-alkaline cyanide is formed which by
treatment with water vapour or steam is decomposed for developing ammonia with
re-formation of alkaline carbonate or earth alkaline carbonate.
When carried out in the customary manner this method has certain defects.
Thus owing to the necessity for mixing the residue from the steaming with fresh
coal considerable time and work is spent. Moreover the decomposition of the
cyanide within the reaction apparatus has also attendant defects. If, however,
the cyanide were removed from the reaction apparatus in order to pass it into a
special' decomposing apparatus, the simple manufacture of ammonia would present
all the inconveniences and dangers of the manufacture of cyanide. On the other
hand the above cyanide generating process is one which not only requires a high
temperature but also absorbs a large amount of heat, a great part of which is not
recovered with the known modes of carrying out the process.
To obviate these and other inconveniences is the object of the aforesaid invention,
which consiste in modifying the method in such a manner that the cyanide is
obtained in the form of vapours; these vapours are conducted for the purpose of
condensation, over or through coal; the mixture thus consisting of condensed
cyanide and coal is treated with steam, thereby obtaining as a residue, a hot
mixture of coal and alkaline or earth alkaline carbonate fit for being re-charged
into the furnace.
In this manner the special mixing operation is dispensed with, and the decom-
position of the cyanide is rendered practicable outside the reaction chamber without
any need for removing it from the apparatus, moreover a certain amount of heat
is saved.
:
In the first part of the improved method the inventor avails himself of the well
known use of the electric furnace for producing cyanides from an alkali or an earth
alkali, or their carbonates, coal and a gaseous mixture containing nitrogen, such
as air, producer gas and the like, employing an electric furnace provided with
the electrodes in its lower part, and conducting the said gaseous mixture from
above to its charge which consists in a mixture of coal or coke and alkalies or
earth alkalies or their carbonates, and sinks gradually downward as the reaction
proceeds. According to this invention the cyanide vapours formed together with
the gaseous products are allowed to escape behind the zone of the electrodes, that
is to say, within or directly below the zone of the greatest heat through an air-
tight passage into a receiver which is filled with coal or coke and secured against
the access of air. In this receiver the cyanide vapours are allowed to condense in
their passage through the coal or coke, When the formation of cyanide ceases
and the last cyanide vapours have been condensed, steam is conducted into the
receiver or condenser which is for this purpose provided with a steam inlet at a
suitable point, and the cyanide is decomposed into ammonia and alkaline or earth
alkaline carbonate. The former escapes together with the other gaseous products
through a discharge pipe provided for this purpose to the purifying and absorption
apparatus, whilst the latter remains behind mixed with coal (coke) and serves as a
fresh charge for the reaction furnace.
It is preferred to arrange the receiver above the furnace, so that the charge
obtained as described as residue in the condenser can be allowed to fall by its own
weight into the furnace on opening a slide or door.
Besides the advantage of obviating the inconveniences hereinbefore referred to,
the described method further possesses the special advantage of a very considerable
saving of heat. The raw materials used for the formation of ammonia are very
cheap; the heat-which is here for the most part introduced' as electrical energy-
alone is expensive and the amount of energy necessary to produce the high tem-
perature of the carbon is very great. As the very hot products of the reaction are
caused to pass over the coal or coke contained in the receiver a considerable portion
of the heat they carry with them is left behind in that part of the said coal or coke
first met with by them and which thus can be heated nearly up to the temperature
of the reaction before entering the furnace. Moreover the steaming process gene-

page_text: rates much heat a part of which is retained by the coal and thus saved for
re-heating.
For this reason it is preferred to conduct the operation in the receiver in such a
manner that, in charging the furnace from the receiver, at the point where the
admission of the hot gases and vapours into the latter takes place, there will always
remain behind a quantity of the mixture of coal (coke) and regenerated alkaline
or earth alkaline carbonate, as obtained in the development of ammonia, so that
the hot current of gas and vapours must first pass through part of said mixture
before the cyanide vapours are allowed to condense, so that condensation takes
place only in the remoter layers of the charge in the receiver. This may easily be
obtained by imparting to that portion of the receiver which communicates with the
furnace such an initial temperature as prevents condensation, and protecting it
against cooling by radiation. The portion of the mixture thus preliminary heated
is then passed into the reaction furnace in order to charge the same, the layers
following it take its place, and a fresh quantity of coal (coke) is filled in at the top
of the receiver.
It is also advisable to preliminary heat the air, producer gas or other like
gaseous mixture to be conducted into the reaction furnace, for which
purpose use may also be made of the heat of the gases and vapours passing from
the reaction furnace by conducting them, prior to their passage into the receiver,
through an air heating apparatus of any known construction.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I wish it understood
that I am aware that the use of the electrical furnace for producing ammonia from
air and other gaseous mixtures containing nitrogen, such as producer gas is known
and I do not claim such use per se, but what I claim is:-
The improvement in the manufacture of ammonia by exposing a mixture of coal
and alkali or alkaline-earth metal carbonate, to the heat of an electric furnace while
a gaseous mixture containing nitrogen; such as air, producer gas and the like is
caused to pass through the same, which consists in causing the cyanide vapours
produced to escape into a receiver charged with coal; causing them to condense
therein in contact with the coal, decomposing the condensed cyanide into ammonia
and alkali or alkaline earth metal carbonate by admitting steam into the con-
denser, and returning the residual mixture of alkali or alkaline earth metal car-
bonate and coal into the furnace, substantially as and for the purpose stated.
Dated this 26th dow of October 1897.
HASELTINE, LAKE & Co.,
46, Southampton Buildings, London, W.C., Agents for the Applicant.