Improved Method for the Manufacture of Anhydrous Ammonia, and for the Utilisation thereof for the Production of Cold or Work or of both Cold and Work together.
Year: 1886

page_text: Improved Method for the Manufacture of Anhydrous Ammonia,
and for the Utilisation thereof for the Production of Cold
or Work or of both Cold and Work together.
I, AUGUST OSENBRUCK, of Hemelingen, near Bremen in the German Empire,
Engineer, 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 :-
In the working of ammonia-absorption apparatus it is a great drawback that the
ammonia employed for the production of cold has to be separated by distillation
from an aqueous solution, because, in this operation, a greater or less quantity of
water has unavoidably to be condensed together with the ammonia vapours. The
poorer the solution is in ammonia, the higher will be the temperature required for
driving off the ammonia and the larger will be the proportion of water contained in
the condensation-product. The refrigerating action of the same will be deteriorated
thereby while the consumption of fuel for its preparation will be increased,
consequently, the useful work of the machine is reduced. This disadvantage is
still further increased by the fact that, according to the degree of percentage of
water contained in the liquid ammonia during its evaporation at low temperature,
aqueous liquid ammonia will collect in a quicker or slower degree in the lower
tubes of the evaporating apparatus of the generator, so as to fill these tubes and
thereby to deprive the apparatus of a corresponding evaporating surface, until, by
this accumulation, a complete cutting off of the lower tubes from the absorption-
vessel is effected, and, in consequence hereof, the imprisoned gases under pressure
force the accumulated liquid over into the other vessel where it interferes with the
action by causing alteration in the liquid level.
In order to avoid these inconveniences and to effect a more economical, reliable
and effective working of the absorption machine, I employ glycerine as the
absorption-liquid which, at a low temperature, becomes saturated with ammonia.
As is well known, the boiling temperature of glycerine is, according to its larger or
smaller percentage of water, very high above that of water, while the separation of
ammonia from a glycerine solution having, for instance, 10 per cent, of water, (the
boiling temperature of which is about 138° C.), will be effected already at a
temperature of about 70° C. with a generation of pressure of about 8 atmospheres.

page_text: A simultaneous distillation of glycerine or water with the ammonia is therefore
quite impossible and, consequently, a perfectly pure anhydrous ammonia will be
converted into the liquid condition and, consequently, will be vaporised in the
evaporating pipes of the generators, and the useful effect of the machine will even
then remain constant, (not taking into account an unavoidable increase of fuel
and cooling water consumption), when the ammonia percentage of the glycerine
contained in the distilling vessel is considerably below that of the saturation
degree, because, in order to effect its separation, the boiling temperature of glycerine
need never be reached.
It having been rendered possible to avoid the loss of ammonia heretofore
experienced by the use of a specially constructed stuffing box so that the motor
engine provided with such stuffing box will work for years with one and the same
charge of anhydrous ammonia, the use of ammonia for the production of motive
power is rendered feasible. This application can be effected in two different ways.
A. Either by first evaporating the volatile body from the above described
solution and then condensing the same, such liquid being then evaporated under
a suitable pressure above that of the atmosphere for the purpose of producing cold,
after which it is caused to act in the cylinder of a motor engine so as to produce
an amount of work corresponding to its pressure and quantity, and lastly it is
again absorbed.
B. Or by direct employment of the elastic pressure of the ammonia vapour
separated from the glycerine solution in the distilling apparatus, such pressure
being applied in the cylinder of a motor engine for the production of work after
which the vapour is again absorbed.
In the case of the mode of operating described under A there is provided,
between the discharge pipe of the evaporating tubes of the generator of an ammonia
absorption machine and the absorption-vessel, a motor engine in such manner that
the ammonia vapour passing from the evaporating tubes in the first instance
performs work by expansion in the cylinder of the motor before passing into the
absorption-vessel.
According to the mode of operating described under B an arrangement is
employed as shewn on the accompanying diagram drawing in which A indicates a
generator of pressure of any suitable form and heated in any convenient manner
for the reception and separation of the solution of glycerine and ammonia, B the
working cylinder or cylinders of a motor engine, C a closed absorption vessel of
any suitable construction in which glycerine poorer in ammonia than in the
vessel A is contained, into which the discharge pipe of the working cylinder or
cylinders of the motor engine is made to dip in a suitable manner in order to effect
the absorption of the cooled and expanded gases. For the reception and conducting
away of the absorption-heat, the vessel is provided with a suitable water refri-
gerating arrangement X. D is a closed absorption vessel communicating with the
absorption vessel C at top through a pipe Y in which the absorption liquid is
reduced to the requisite temperature below that of the water by direct evaporation
of liquid anhydrous ammonia in the coil Z. G is a suction and force pump which
forces the cold saturated solution of glycerine and ammonia into the interior of the
pipe of the heat regenerator F and forces it from this back into the pressure
generator A. The hot solution of glycerine and ammonia impoverished by the
evaporation of ammonia in the pressure generator is caused to pass from the latter
through the pipe 1 into the outer jacket of the heat regenerator F in the same
proportion as saturated solution of ammonia and glycerine is fed into the pressure
generator through the pump G.
It will be understood that all radiation of heat from the outer surface of the
heat regenerator is avoided by suitable enclosure with a bad conductor of heat.
The solution cooled by passage through the apparatus F is, if necessary, cooled still
farther by being passed through the coil H of the cooling apparatus E through
which cold water is made to flow before it passes through the pipe 2 into the
absorption vessel C.

page_text: My above described invention is equally applicable with any absorption liquid
other than glycerine, the boiling point of which is above 100° C.
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
The method of separating anhydrous ammonia from an absorption-liquid boiling
at above 100° Cent. such as glycerine, at a temperature below such boiling point,
and utilising the vapours of greater or less pressure obtained by this means, before
being again absorbed, and in continuous circulation, according to one or other of the
following three modes of operating:
1. By liquefying the vapours for the purpose of producing cold in re-evaporating.
2. By first liquefying the vapours for producing cold by their evaporation and
afterwards converting the vapours of low pressure produced bereby into work.
3. By converting the expansive force of the vapours first produced into work.
Dated this sixteenth day of Tenuer 1886
ABEL & IMRAY,
Agents for the Applicant.