Improvements in the Manufacture of Sulphuric Acid.
Year: 1895

page_text: Date of Application, 17th Jan., 1895
Complete Specification Left, 18th Nov., 1895-Accepted, 17th Jan., 1896
Improvements in the Manufacture of Sulphuric Acid.
I, ULRICH FREDERIC BENKER of 115 Rue Martre, Clichy, (Seine) France,
Chemical Engineer, do hereby declare the nature of this invention to be as
follows:-
In the manufacture of sulphuric acid, and particularly when such manufacture is
carried on on a forced scale, it is found that the Gay-Lussac towers allow yellow
vapours of greater or less strength to escape.
It is usually supposed that this disadvantage results from the towers having
become overcharged, and it has been attempted to remedy it either by a more
copious watering or irrigation, or by increasing either the number or the dimensions
of the said towers, but a satisfactory result has nevertheless not been obtained.
The cause of the aforesaid loss is to be found in the wrong composition of the gases
entering the Gay-Lussac towers. These gases contain too much hyponitrous acid,
and for which the absorbing capacity of sulphuric acid at 60° Bé. is almost nil when
this acid is carried over or along by the great volume of such gases.
Now, if a properly proportioned quantity of moist sulphurous acid be injected
by means for instance of an injector constructed for this purpose either into the
last chamber of the series, or into the last portion of a large chamber situated
before the Gay-Lussac tower, the yellow vapours issuing from these towers,
disappear at once, and the content or percentage strength of the acid flowing off
from the towers becomes increased to a very considerable extent.
In a large apparatus the daily saving effected by this means may amount to from
150 to 250 kilogs. of nitrate, and the consumption of this substance becomes
extremely small. I have reason to suppose :-(1) That the slight reaction that,
takes place anew in the last portion of the apparatus, whilst giving time to the
nitrogen dioxide formed by the reduction of the hyponitrous acid, to become
re-oxidized to nitrous acid which is the only substance that is stable in the presence
of sulphuric acid, prevents fresh formation of hyponitrous acid, notwithstanding
the excess of oxygen present in the gases, and (2) that the period during which the
mixture remains in the drum or chamber of the series enables this reaction to
become completed, which would be but very imperfectly produced in the Gay-Lussac
tower for want of time.
Improvements in the Manufacture of Sulphuric Acid.
I, ULRICH FREDERIC BENKER, of 115 Rue Martre, Clicby, (Seine) France,
Chemical 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
0 in and by the following statement :-
In the manufacture of sulphuric acid, and particularly when such manufacture is

page_text: carried on on a forced scale, it is found that the Gay-Lussac towers allow yellow
vapours of greater or less strength to escape.
It is usually supposed that this disadvantage results from the towers having
become overcharged, and it has been attempted to remedy it either by increasing
the flow of the sulphuric acid in the tower, or by increasing either the number or
the dimensions of the said towers, but a satisfactory result has nevertheless not
been obtained. The cause of the aforesaid loss is to be found in the wrong
composition of the gases entering the Gay-Lussac towers. These gases contain
too much hyponitric acid, for which the absorbing capacity of sulphuric
acid at 60° Bé. is almost nil when this acid is carried over or along by a great 1
volume of such gases.
Now, I have discovered that if a suitable quantity of moist sulphurous acid be
injected by means for instance of an injector constructed for this purpose, either
into the last chamber of the series, or into the last portion of a large chamber
situated before the Gay-Lussac towers, the escape of yellow vapours from these
towers will disappear at once, and the content or percentage strength of the nitrous
acid contained in the acid flowing off from the towers will become increased to a
very considerable extent. In practice, the quantity of moist sulphurous acid to be
injected as described, will vary considerably; it is determined by the colour of the
gases that issue from the last lantern or spying glass beyond the Gay-Lussac
towers, and which pass from a yellow color to white when the apparatus is working
well and the proper quantity of moist sulphurous acid is being used.
The injecting apparatus is preferably made of regulus of lead containing about
10% of antimony. It is provided with a damper or register for regulating the
quantity of the sulphurous acid gas to be injected, and with a small water pressure
gauge for controlling the suction. A cover adapted to be simply laid upon the
apparatus, allows of the ready removal of the plate or carrier that supports
the injector cones, which are two in number in order not to agitate the sulphurous
acid gas too much.
The cock which supplies the steam to the injector, and which may be of gun
metal, ends in a platinum point which acts to cause the steam passing therethrough
to issue in the form of a fine thread or jet of small volume.
The construction and arrangement of the cover is such as to allow of very easily
inspecting the interior of the apparatus, of rapidly cleaning the cones, and even,
in case of wear, of replacing them, as well as the plate or carriage by which they
are held in position, without scarcely interrupting the working of the suction
producing or injecting device.
In the accompanying drawings,
Fig. 1 is a horizontal section, Fig. 2 a longitudinal vertical section, and Fig. 3 a
cross section, showing an injector suitable for carrying out my invention.
a is the body of the injector in the form of a rectangular box or casing into
which steam is delivered in the form of a fine jet by a gun-metal cock b provided
with a fine platinum nozzle c. d is a branch pipe for supplying sulphurous acid
gas to the box or casing a wherein it becomes moistened by the steam issuing from
the nozzle c. As an excess of humidity of the gas would be injurious, by lowering
too much the degree of the acids of the last chamber, the supply of steam through
the nozzle c must be suitably regulated. d' is a damper or register for controlling
the flow of gas through the pipe d. a¹ are a pair of cones arranged opposite the
steam nozzle c, these cones being carried by a plate a². The box or casing a is
also provided with a pipe e for a water pressure gauge; a cover ƒ having a
handle g; a pipe for discharge of water of condensation; and wrought-iron
flanges i for attaching the apparatus to the chamber into which the sulphurous acid
gas is to be injected.
In a large apparatus, the daily saving effected by my invention may amount to
from 150 to 250 kilogs. of nitrate, and the consumption of this substance becomes,
comparatively, extremely small.
I have reason to suppose:-1, That the slight re-action that takes place anew in

page_text: the last portion of the apparatus, whilst giving time to the nitrogen dioxide formed
by the reduction of the hyponitric acid, to become re-oxidized to nitrous acid,
which is the only substance that is stable in the presence of sulphuric acid, prevents
fresh formation of hyponitric acid, notwithstanding the excess of oxygen present
in the gases; and (2) that the period during which the mixture remains in
the last drum or chamber of the series, enables this reaction to become
completed, which would be but very imperfectly done in the Gay-Lussac tower
for want of time.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
In the manufacture of sulphuric acid, injecting moist sulphurous acid into the
last chamber of the series of chambers used in such manufacture, or into the portion
of a large chamber serving as the last chamber of the series, substantially as herein
described for the purpose specified.
Dated thin 10th d
1005
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.