Improvements in the Manufacture of Chlorine.
Year: 1890

page_text: Date of Application, 1st May, 1890
Complete Specification Left, 2nd Feb., 1891-Accepted, 14th Mar., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorine.
WC, GEORGE EDWARD DAVIS, of 32, Blackfriars Street, Manchester, in the
County of Lancaster, Chemical Engineer, and ALFRED ROLAND DAVIS, of
32, Blackfriars Street, Manchester, in the County of Lancaster, Chemical
Engineer, do hereby declare the nature of this invention to be as follows:-
In the Specification of our application for Provisional Protection for improve-
ments in the preparation of chlorine, filed on April 28th of this year, we showed
how the last traces of nitrogen compounds mixed with the chlorine, were absorbed
in sulphuric acid, and we further stated that the sulphuric acid after having under-
gone this operation, was used to decompose a subsequent batch of salt. We also
described how the water of the reaction flowed away from the first nitric acid
tower; holding a quantity of hydrochloric acid gas in solution.
We have found by experiment that the water of the reaction may absorb as much
as thirty per centum of the hydrochloric acid, and the total water introduced into,
and formed in the process may at times be capable of dissolving and taking away
out of the process nearly one half of the hydrochloric acid produced from the salt.
Our present invention relates to a modification of the method of conducting the
process aforesaid, so that the whole of the hydrochloric acid employed is caused to
remain in the process until it is converted into chlorine.
In carrying out our invention, we cause the sulphuric acid that has been passed
down the absorbing tower, to enter the first nitric acid tower, at a point below
where the action of the nitric acid on the hydrochloric acid is completed, and where
an excess of hydrochloric acid is present. The result of this arrangement is that
the sulphuric acid combines with the water of the aqueous hydrochloric acid and
the hydrochloric acid gas is liberated and passes on with the main body of gases
to be decomposed as we have already described in our previous Specification
aforesaid.
The sulphuric acid thus weakened by the absorption of the water set free in the
process, runs away from the bottom of the tower, containing only traces of hydro-
chloric acid gas in solution and must be concentrated to proper strength for
decomposing the salt or for absorption of the last traces of nitrous fumes again in
the sulphuric acid tower.
The before mentioned improvements are very effective as the heat of the reaction
of the water of the liquid muriatic acid upon the sulphuric acid enables the weak
sulphuric acid to leave the tower almost entirely free from hydrochloric acid gas,
so that no difficulty arises in its concentration, but if at any time hydrochloric acid
gas is found therein we make provision for condensing the same during the con-
centration in a suitable condenser. The hydrochloric acid gas or air or both of
them may be taken hot into the tower and so assist in keeping the absorption of the
hydrochloric acid gas at the lowest possible limit.
A further advantage to be derived from working as described, is the elimination
and utilization of any nitrogen compounds present in the sulphuric acid, or which

page_text: may accidentally find their way downward from that portion of the tower above
where the sulphuric acid is introduced.
Dated this First day of May 1890.
GEORGE EDWARD DAVIS.
ALF. R. DAVIS.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Chlorine.
We, GEORGE EDWARD DAVIS, nad ALFRED ROLAND DAVIS, both of
32, Blackfriars Street, Manchester, in the County of Lancaster, Chemical
Engineers, 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 Specification of our application for Provisional Protection for "Improve-
ments in the preparation of chlorine," No. 6-416, filed on April 28th 1890, on which
our present improvements are ba ed we showed how the last traces of nitrogen
compounds mixed with the chlorine were absorbed in sulphuric acid, and we further
stated that the sulphuric acid, after having undergone this operation, was used to
decompose a subsequent batch of salt.
We also described how the water of the reaction flowed away from the first nitric
acid tower holding a quantity of hydrochloric acid gas in solution.
We have found in practice that the water of the reaction may absorb as much as
thirty per centum of the hydrochloric acid, and the total water introduced into, and
formed in the process may at times be capable of dissolving and taking away out of
the process nearly one half of the hydrochloric acid produced from the salt. Our
present invention relates to a modification of the method of conducting the process
aforesaid so that the whole of the hydrochloric acid employed may be caused to
remain in the process until it is converted into chlorine.
In carrying out our invention we cause the sulphuric acid that has been passed
down the absorbing tower marked (in the drawing accompanying our Specification
aforesaid numbered 6-416 and dated April 28th 1890, to enter the first nitric acid
tower B at a point below where the action of the nitric acid upon the hydrochloric
acid is completed and where an excess of hydrochloric acid exists, and the result of
this arrangement is that the sulphuric acid combines with the water of the aqueous
hydrochloric acid, and the hydrochloric acid gas is liberated, and a portion of it
reacts upon the nitrogen oxides present in the sulphuric acid forming chloronitrous
gas which passes on with the main body of gases, to be decomposed as we have
already described in our previous Specification numbered 6416 and dated April 28th
1890 aforesaid.
It will be noted that by applying the improvement above described to our
invention the subject of our Patent 6416% more beneficial results are obtained
though our former invention may be successfully worked as described.
The sulphuric acid thus weakened by the absorption of the water set free in the
process, runs away from the bottom of the tower 13, containing only traces of
hydrochloric acid gas in solution and this weak sulphuric acid must be concentrated
by evaporation to the proper strength for decomposing the salt or for absorption
of the last traces of nitrous finnes again in the sulphuric acid tower C.
The before mentioned improvements are very effective as the heat of the reaction
of the water of the liquid hydrochloric acid upon the sulphuric acid enables the
weak sulphuric acid to leave the tower almost entirely free from hydrochloric acid
gas, so that no difficulty arises in its concentration, but if at any time hydrochloric
acid gas is found therein we make provision for condensing the same during the
concentration in any well known manner in a suitable condenser. The hydrochloric
acid
gas or air, or both of them, may with advantage be taken hot into the tower

page_text: and so assist in keeping the absorption of the hydrochloric acid gas at the lowest
possible limit. A further advantage to be derived from working as described is the
elimination and utilization of any nitrogen compounds present in the sulphuric acid
or which may escape from that portion of the tower above where the sulphuric acid
is introduced.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we are aware that attempts
have been made to liberate hydrochloric acid gas from a solution in water by
mixing the aqueous solution with sulphuric acid in a concentrated state as was done
by Isham Baggs and published in his Specification No. 3296 of 1866, but we make
no claim to this reaction as being our invention. We also make no claim to the
process herein described for manufacturing chlorine wherein the sulphuric acid that
has done duty in the absorbing tower is admitted into the first nitric acid tower at
a point below where the action of the nitric acid upon the hydrochloric acid gas is
completed in order to separate the water formed during the reactions from any
hydrochloric acid that it may have absorbed but what we claim is :-
The process of manufacturing chloronitrous gas by acting upon an aqueous
solution of hydrochloric acid with nitro sulphuric acid in the presence of air in a
tower packed with suitable material, substantially as is herein described.
Dated the 20th day
20th day of a
T
ww
1001
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.