A Process for Removing Carbonic Acid and Hydrogen Sulphide from Ammoniacal Liquor.
Year: 1897

page_text: Date of Application, 27th Apr., 1897-Accepted, 5th June, 1897
A Process for Removing Carbonic Acid and Hydrogen Sulphide
from Ammoniacal Liquor.
1, Dr. ALFRED FELDMANN, of 1° Dechanatstrasse, Bremen, in the Empire of
Germany, Manufacturer, 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 present invention relates to a process for removing carbonic acid and
hydrogen sulphide from the ammoniacal liquor of gas works, coke works and the
like prior to the further treatment.
The removal as heretofore effected, of the aforesaid ingredients of the crude
ammoniacal liquor takes place by the use of lime, the presence of which however
materially increases the difficulty of completoly dispelling the ammonia, whilst the
removal of the lime mud prior to the distillation by filtration occasions too much
wear of the filter cloths and consequently increases the cost of the process too much.
The removal of the ammonium sulphide by other chemicals, such as hydrated
ferric oxide, manganates, gas purifying material has not proved successful in
practice. The present process is based upon the observation that by heating the
gas liquor in distilling columns to a temperature of at least 94 to 97 degrees Centi-
grade a simultaneous and sufficiently complete removal of carbonic acid and
hydrogen sulphide will be effected. This is probably due to the fact that at the
stated temperature the ammonium carbonate is first dissociated, and that the freed
carbonic acid decomposes the ammonium sulphide with formation of hydrogen
sulphide. A further advantage of the process consists in the fact that when
carrying out the process it is possible to effect at the same time the removal of
tarry impurities of the ammoniacal liquor.
The process is carried out in a column apparatus of any construction. As an
example of such an apparatus, which has proved particularly suitable for the
present purpose, that represented in the accompanying drawing may be set forth.
This apparatus consists of a cylinder A in which several compartments f are
provided, these being connected with each other by the tubes g. Each compartment
carries moreover the tube i with the cap h. The gas liquor enters the column at a,
passes through the overflow pipes g to the collecting compartment D, and leaves
the column through the siphon tube which carries a thermometer at c. Through d
a sufficient quantity of steam is admitted into the column that the gas liquor flowing
off leaves the apparatus at a temperature of at least 94 degrees Centigrade to
97 degrees Centigrade. The steam or vapour admitted is condensed almost
completely in the first compartment above the collecting chamber. In consequence
of the stated heating, the hydrogen sulphide present in the gas liquor in the form
of ammonium sulphide is almost completely removed, whilst about three-fourths of
the carbonic acid present are removed and blown off at e together with the tarry
products.
In lieu of the direct steam or vapour the heating may also take place indirectly
by providing a heating coil in the collecting chamber.
The present process differs from the processes heretofore practised by the fact
that the dispelling of the hydrogen sulphide and the carbonic acid takes place
in a single operation and that in this case a higher temperature must be
maintained.

page_text: The advantages of the removal of the carbonic acid and of the hydrogen
sulphide from the ammoniacal liquor consist in the fact that in the treatment to
form concentrated ammoniacal liquor, which by the process heretofore used can
only be obtained with from 16 to 18 per cent. of ammonia, because with a higher
concentration there occur cumbersome separations of solid ammonium carbonate,
concentrations to any degree up to 30% ammonia can be obtained, which is of
great importance as regards the transport. In the treatment having for its object
to form spirit of sal-ammoniac it is possible to save from 50 to 60 per cent. of the
lime which is otherwise added, thereby materially facilitating the working and
decreasing the cumbersome residues of lime.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A process for removing carbonic acid and hydrogen sulphide from ammoniacal
liquors of gas works, coke works and the like, characterized by the feature that
the ammoniacal liquor is heated in distilling columns to a temperature of 94 to.
97 degrees Centigrade.
degrees Centigrade.
Dated this 27th day of April 1897
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.