Improvements relating to the Preparation of Chlorine.
Year: 1890

page_text: Date of Application, 3rd May, 1890
Complete Specification Left, 2nd Feb., 1891-Accepted, 7th Mar., 1891
PROVISIONAL SPECIFICATION.
Improvements relating to the Preparation of Chlorine.
We, GEORGE EDWARD DAVIS, of 32, Blackfriars Street, Manchester, in the
County of Lancaster, Chemical Engineer, and ALFRED ROLAND DAVIS, also of
32, Blackfriars Street, Manchester, in the County of Lancaster, Chemical Engineer,
lo hereby declare the nature of this invention to be as follows:-
In our Specification, describing the details of our improvements 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 undergone this operation
was used to decompose a subsequent batch of salt. We also stated that the water
formed during the reactions ran away from the first nitric acid tower holding in
solution a quantity of hydrochloric acid gas.
We have found by experiment that the water so running away from the tower
may contain as much as 30 per centum or even 50 per centum of the hydrochloric
acid entering the tower, which reduces the efficiency of the process very
materially.
Our present invention relates to a method for treating this aqueous solution,
in order that the hydrochloric acid gas may be retained in the process until its
conversion into chlorine.
In carrying out our invention we provide in addition to the apparatus described
in our Specification aforesaid, a tank or partially closed receptacle made of any
suitable inaterial and placed at a convenient level, so that the aqueous solution of
acid running from the first nitric acid tower and the sulphuric acid running from
the absorbing tower can be conducted into it. These two liquids on mixing evolve
a considerable quantity of gas and care must be taken to make the mixture
continuously and regularly so that the proper dilution with atmospheric air is not
interfered with. The gases liberated by the intermixture pass out of the tank and
are conducted into the nitric acid tower at a suitable heiglit, by means of pipes or
other channels provided for the purpose. We prefer to make the tank or other
receptacle with a diaphragm dividing its lower section into two chambers, the smaller
of which serves as a mixing chamber, from which the commingled liquids overflow
into the second or larger chamber, where they are subjected to the action of the
current of gases coming from the salt-cake, or other hydrochloric acid producing
apparatus. In cases where the said current of gases contains no oxygen or less
than is necessary to complete the reactions, we find it is a good method to pass such
strong gas, directly into the tower, and to force the necessary air through the
liquid acids contained in the above described tank or receptacle, which may if
found advantageous be heated in any convenient manner. The air current displaces
the hydrochloric acid gas and is carried forward with it into the nitric acid tower.
The diluted acid running from the tank or other receptacle is then concentrated
for use over again in the absorbing tower, or for use in decomposing a subsequent
batch of salt.
As an alternative process for dealing with the water set free by the reactions, as
well as for utilizing the drying powers of the sulphuric acid used in absorbing the
last traces of nitrous compounds from the chlorine, we construct a tower packel
with suitable material for the purpose of a drying tower, through which the gases
from the salt-cake or other hydrochloric acid producing apparatus are passed. The
sulphuric acid that has done duty in the sulphuric acid absorber is divided into two
streams or portions, and one of these portions is run down the drying tower, wherein
the water contained in the hydrochloric acid gas is arrested and combines with the

page_text: acid flowing down the tower. The weak acid flowing away from the tower is then
concentrated for use over again in the abuching tower, or for decomp sing a fresh
charge of chloride. The secon 1 portion of alphuric acid from the absorber is run
into the tank or receptacle above der bel together with the reous hydrochloric
neid running from the first nitric acid tower, where the rections proceed as already
described, and the employment of a eurent of air to disengage the hydrochloric
acid gas from the diluted acid in the tank or receptacle together with the heating
process if necessary is in every way as applicable to this process, as to the one
already described."
Dated this Third day of May 1890I
GEORGE E. DAVIS.
ALF. R. DAVIS.
COMPLETE SPECIFICATION.
improvements relating to the Preparation of Chlorine.
We, GEORGE EDWARD DAVIS, and ALFRIÐ ROLAND DAVIS, both of 32, Black-
friars Street, Manchester, in the County of Lama-ter, Chemical Engineers, do
hereby declare the nature of this invention, nmd in what manner the same is to be
performed, to be particularly described und n-certained in and by the following
statement:--
In our Specification describing the details of our improvements in the preparation of
chlorine No. 6416 filed on April 28th 1890 on which thee our present improvements
are based we showed how the last traces of nitrog a compounds mixed with the
chlorine were absorbed in sulphuric acid and we further statel that the sulphurie
acid after having undergone this operation was usd to decompose a subsequent
batch of salt.
We also stated that the water formed during the reactions ran away from the
first nitric acid tower holding in solution a quantity of hydrochloric acid gas. The
process described in our Specification 6416 nay he worked so as to give beneficial
results but its efficiency may be materially increased by employing the improvements
hereinafter set forth.
Our present invention relates to a method for treating the aqueous solution
of hydrochloric acid above referred to in order that the said hydrochloric acid may
be retained in the process until its conversion into chlorine.
In carrying out our invention we provide in addition to apparatus described in
our previous Specification No. 6416 aforesaid, a tank shown at II in the drawing
accompanying this Specification, or partially closed receptacle made of any suitable
material and placed at a convenient level, so that the aqueous solution of acid
running from the first nitric acid tower B and the sulphuric acid running from the
absorbing tower (may be conducted into it. These two liquids on mixing evolve
a considerable quantity of gas and care must be taken to make the mixture
continuously and regularly so that the proper dilution with atmospheric air is not
interfered with by a sudden and too copious evolution of gas. The gases liberated
by the intermixture pass out of the tank and are conducted into the nitric acid
tower B at a suitable height by means of pipes I or other channels provided for the
purpose. The tank or other receptuele may with advantage be provided with a
diaphragm dividing its lower section into two chambers as shown in the drawing,
the smaller of which I serves as a mixing chamber from which the commingled
liquids overflow into the second or larger chamber where they are subjected to
the action of the current of gases coming from the salt cake or other hydrochloric
acid producing apparatus. In cases where the said current of gases contains no
oxygen or less than is necessary to complete the re-actions, we find it is a good
method to pass such strong gas directly into the tower and to force the necessary
air through the liquid acids contained in the above described tank or receptacle by
means of the pipe P, the contents of which may when found advantageous be heated
in any convenient manner. The air current displaces the hydrochloric acid gas

page_text: and is carried forward with it into the nitric acid tower. The diluted acid
running from the tank or other receptacle at T is then concentrated for use over
again in the absorbing tower or for use in decomposing a subsequent batch
of salt.
As an alternative process for dealing with the water set free by the reactions
as well as for utilizing the drying powers of the sulphuric acid used in absorbing
the last traces of nitrous compounds from the chlorine, we construct a tower packed
with suitable material for the purpose of a drying tower shown in the drawing
accompanying this Specification through which the gases from the salt-cake or
other hydrochloric acid producing apparatus, are passed. The sulphuric acid that
has done duty in the sulphuric acid absorber C is divided into two streams or
portions, and one of these portions is run down the drying tower wherein the water
contained in the hydrochloric acid gas is arrested and combined with the sulphuric
acid flowing down the tower. The weak acid flowing away from the tower is then
concentrated for use over again in the absorbing tower C or for decomposing a fresh
charge of chloride. The second portion of sulphuric acid from the absorber C is
run into the tank H or receptacle above described together with the aqueous hydro-
chloric acid running from the first nitric acid tower B where the reactions proceed
as already described and the employment of a current of air to disengage the
hydrochloric acid gas from the diluted acid in the tank H or receptacle together
with the heating process before described if necessary is in every way as applicable
to this alternative process, as to the one already described.
When the sulphuric acid from the absorbing tower C is treated in either of
the ways described above the nitrogen compounds which it contains are evolved
in combination with chlorine as chloro-nitrous gases the behaviour of which
in the nitric acid tower or towers has been described in our Specification 6416
of 1890.
We do not claim as our invention the evolution of hydrochloric acid gas from
an aqueous solution of the same by bringing it in contact with strong sulphuric
acid, but what we do claim is :-
1. The utilization of the aqueous hydrochloric acid running from the first nitric
acid tower B in the process described in our previous Specification No. 6416 of
April 28th 1890, by treating it with the sulphuric acid running from the absorbing
tower C, substantially as is herein described, and
2. The use of the alternative process herein described in which the nitrous
sulphuric acid running from the absorbing tower C is split up into two streams,
one of which portions is run down a drying tower through which the hydrochloric
acid gas and air coming from the salt cake or other hydrochloric acid producing
apparatus is made to pass while a second stream is run into the tank A or other
receptacle together with the aqueous hydrochloric acid running from the first
nitric acid tower B in the manner and for the purpose substantially as is herein
described.
3. The use of the process for removing the nitrogen compounds from the
sulphuric acid that has been employed to remove the last traces of these from the
chlorine by acting upon a part of the said sulphuric acid with hydrochloric acid
gas in a drying tower and upon the other part with the liquid hydrochloric acid
running from the first nitric acid tower in a closed vessel, substantially as is herein
described.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.