Improvements relating to the Manufacture of Sulphuric Acid, and to Apparatus therefor.
Year: 1894

page_text: Date of Application, 29th June, 1894
Complete Specification Left, 12th Mar., 1895-Accepted, 13th Apr., 1895
Improvements relating to the Manufacture of Sulphuric Acid, and to
Apparatus therefor.
I, ALFRED STAUB, of 32 Leipziger Landstrasse, Bettenhausen, near Cassel,
in the Empire of Germany, Doctor of Philosophy, do hereby declare the nature
of this invention to be as follows:-
My invention relates to the manufacture of sulphuric acid and to apparatus
therefor. The sulphuric acid is manufactured by bringing together sulphurous
This invention has
acid gas and nitrous acid gas in the presence of air and water.
for its object the production of sulphuric acid without the use of leaden chambers
or the like, the direct production of a concentrated sulphuric acid free from nitrous
acid, and the combination of the several operations to obtain a cycle.
For this purpose I cause the said gases to pass slowly and under pressure through
a system of narrow passages in the upward direction, while the liquid flows through
these passages in the opposite direction.
Under these conditions I obtain an extremely intimate contact of the agents,
and the retardation due to the friction between the gases and the liquid gives rise
to a very considerable pressure whereby the molecules of the gases are brought
very close together so that on the whole way only liquid and dense gas will act
upon each other by a multiplicity of contacts which are continually changing and
greatly promote the reaction. As the introduction of steam necessary in the
leaden-chamber process is dispensed with, much less heat is developed, so that the
sulphuric acid produced cannot for any length of time remain in the vaporous
state, but is rapidly condensed, this condensed acid being at the same time filtered
as it were from the mixture of gases by the walls of the numerous passages.
Owing to the extremely intimate contact of the substances, much less oxygen is
required in the form of air than in the leaden chamber process, so that the volume
of gas is correspondingly less.
According to my invention I use columns which are filled from the bottom to the
top with material capable of withstanding acid so that a very large number of
narrow passages extend through the whole column. As such a filling material the
well-known substances may be used; it is however expedient, in order to effect as
uniform a division of the gases and liquid as practicable to employ perforated
grate or sieve shaped plates made for instance of burnt clay and piled up, or better
still short and narrow clay pipes which are placed upright and alternated. This
filling material bears below upon a perforated bottom; into the space below this
bottom the gases are introduced, and the column has at its top an opening for the
outlet of the gases which have not been used. Each column is provided at the top
with a device for distributing the liquid which is to descend through the column,
and at the bottom with an outlet for the acid formed.
I preferably make the column of burnt clay and fill it densely and regularly,
from the bottom up to the outlet for the gas, with small thin pipes which preferably
also consist of burnt clay. The small pipes are piled up regularly so that the pipes
of every following layer alternate with those of the layer below. Accordingly the
column possesses throughout its height an extremely great number of small narrow
channels which are regularly connected with each other, and the gases are again and
again compelled to deviate from the straight path, to divide again and again into
.

page_text: uniformly fine currents and to mix again. The liquid trickling from above is
obliged to do the same, so that the gases and liquid are brought in very intimate
and continually changing contact with each other. The outlet for the gases is
controlled in such a manner that the latter obtain a very slow upward movement,
which in conjunction with the multiple resistance offered to the gases by the small
pipes gives rise to a considerable pressure of the gases. This pressure not only
brings the molecules of the gases closer together but also promotes their intimate
contact with the liquid.
In order to still further retard the movement of the gases and increase their
pressure the small pipes may be provided in their interior with broad flat
projections which are arranged obliquely and alternate with each other. Such
projections partly retard the gases and partly impart to them a helical movement.
For the same purpose the small pipes may be provided with a helical wall.
If a uniform mixture of sulphurous acid gas and nitrous acid gas is caused to
pass in conjunction with air through such a column and water is caused to flow down
in the latter, the water will absorb sulphurous acid and a weak acid is produced. If
nitrous acid gas alone passes and sulphuric acid, suitably of 50 per cent, and more,
flows down, the latter absorbs the nitrous acid. If sulphurous acid gas with air
passes through the column, and sulphuric acid containing nitrous acid flows down
sulphuric acid is formed and the nitrous acid passes over into the current of gas.
These three operations rendered possible by the column may be so combined that
in a continuous working a highly concentrated sulphuric acid may be produced free
from nitrous acid, the nitrous acid being used again in the process.
For this purpose several columns are combined to form a battery, so that the
gases from the upper part of one column are conducted into the lower part of the
next column, the fresh sulphurous acid gases mixed with air being conveyed into
the first column and the battery supplied at a suitable point with nitric acid at the
beginning of the process and when necessary also during the same, while strong
sulphuric acid which contains nitrous acid is distributed through the front columns.
As the. sulphurous acid gas is here in excess, sulphuric acid will be rapidly formed
which is added to the said acid and strengthens the same. On the other hand the
nitrous acid passes over into the gases which thus, the further they advance, become
poorer and poorer in sulphurous acid gas, and richer in nitrous acid gas, until a
point is reached where the excess of the former disappears. The gases pass in this
state into the following columns wherein water is caused to flow down which rapidly
absorbs the sulphurous acid so that an aqueous solution of sulphurous acid and
nitrous acid gas act upon each other and form again sulphuric acid which however is
too weak for absorbing nitrous gas, therefore the latter remains in the current of gas.
In a following column this weak acid caused to pass down to absorb the remainder
of the sulphurous acid which is oxidized to form sulphuric acid. Now the current
of gas consists substantially of nitrous acid and air. In order to obtain the latter,
strong sulphuric acid taken from the battery at a suitable point is distributed
through the last columns, this absorbs the nitrous acid gas so that the current of
gas leaving the last column will be free from acid. The solution of nitrous acid in
sulphuric acid as obtained in the last columns is again distributed through the
front columns. By properly regulating the process it is possible to obtain in
the first columns strong sulphuric acid free from nitrous acid and to raise the
concentration in the first column to 66 degrees.
Suppose a battery to be composed for instance of five columns, each filled with
small pipes. Large pipes connect the columns with each other so that the fresh
gases pass below into the battery and the spent gases pass above from the saine.
With such a battery of five columns the operation is preferably effected in such
a manner that through the first column passes down the acid from the fifth column,
through the second column the acid from the fourth, through the third the water,
through the fourth acid from the third, and through the fifth a portion of the acid
from the first; or else that through the first column descends acid from the fifth
and likewise through the second column acid from the fifth through the third water,
i

page_text: through the fourth the acid from the third, and through the fifth column the acid
from the fourth.
The foregoing statements will enable any expert to adapt the present invention
to particular requirements, arrange the number of columns and provide for, the
distribution accordingly.
Dated this 20th der of June 1891
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements relating to the Manufacture of Sulphuric Acid, and to
Apparatus therefor.
I, ALFRED STAUB, of 323 Leipziger Landstrasse, Bettenhausen, near Cassel,
in the Empire of Germany, Doctor of Philosophy, 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:—
This invention relates to the manufacture of sulphuric acid by bringing together
sulphurous acid gas and nitrous acid gas in the presence of air and water. It
comprises improvements in the process and apparatus used therefor and has for its
object to do away with the use of leaden chambers or the like, to produce a
concentrated sulphuric acid free from nitrous acid, and to so combine the several
operations that a cycle is obtained.
For this purpose. the said gases are caused to pass slowly and under pressure
through a system of narrow passages in the upward direction, whilst the liquid is
caused to flow through these passages in the opposite direction.
Under these conditions not only an extremely intimate contact of the agents is
obtained, but the retardation due to the friction between the gases and the liquid
gives rise to a very considerable pressure whereby the molecules of the gases are
brought very close together so that on the whole way only liquid and dense gas
will act upon each other by a multiplicity of contacts which are continuously
changing, whereby the reaction is greatly promoted. As the introduction of
steam necessary in the leaden-chamber process is dispensed with, much less heat is
developed, so that the sulphuric acid produced is hindered from remaining in the
vaporous state for any length of time, but is rapidly condensed, this condensed acid
being at the same time filtered as it were from the mixture of gases by the walls of
numerous passages. Moreover, owing to the extremely intimate contact of the
substances, much less oxygen is required in the form of air than in the leaden-
chamber process, so that the volume of gas is correspondingly less.
In carrying out the present invention, columns are used which are composed of a
casing constructed with acid resisting material and so filled from the bottom to the
top with material capable of withstanding acid, that an infinity of narrow passages
extend through the whole column. As such filling material the well-known
substances, for instance coke may be used; but I prefer, in order to effect as
uniform a distribution of the gases and liquid as practicable, to employ perforated,
grate- or sieve-shaped plates made for instance of burned clay and piled up so that
the openings of each alternate with those of the preceding and following ones, or short
and narrow clay pipes which are placed upright and alternated. This filling material
rests below upon a perforated or grate like bottom, and the gases are introduced
into the space below said bottom, whilst the column has at its top an opening for
the exit of the gases that have not been used. Moreover, the column is provided
at the top with a device for distributing the liquid which is to descend through the
column, and at the bottom with an outlet for the sulphuric acid formed.

page_text: On the annexed sheet of drawings:
Fig. 1 is a diagram showing in vertical section a column filled with small narrow
tubes of burnt clay, and
Fig. 2 a vertical section through several layers of filling tubes, drawn on a larger
scale for illustrating the distribution of the gases.
Figs. 3 and 4, which are likewise drawn on a larger scale represent two modified
forms of filling tubes.
Fig. 5 is a diagram, partly in vertical section, showing a plant in which for
instance five columns are combined into a battery for obtaining a cycle resulting
in the production of concentrated sulphuric acid free from nitrous acid.
With regard to Fig. 1, a is the casing, preferably constructed with burnt clay,
b the perforated bottom for the filling material c to rest upon, d the gas inlet, e the
gas outlet, the outlet for the acid formed, and g the liquid distributing device.
The filling material consists in this instance in short narrow pipes of uniform
length and width open at both ends and consisting of burnt clay, with which the
casing a is filled closely and regularly up to the outlet for the gases. As more
clearly seen from Fig. 2, these pipes are piled up in upright position and so that
the tubes of every following layer are shifted to those of the layer below. By this
arrangement the column is uniformly divided throughout its height into an extremely
great number of small narrow channels connected with each other, whereby the
gases are again and again compelled to deviate from the direction imparted to
them. by entering a layer of tubes, to divide again and again into uniformly fine
currents, and to mix again, as indicated by arrows in Fig. 2. The liquid trickling
from the device 9 is obliged to do the same, so that the gases and liquid are
brought in very intimate and continually changing contact with each other.
The outlet e for the gases that have not been used in forming sulphuric acid, is
controlled in such a manner that the gases obtain a very slow speed, which in
conjunction with the multiple resistance offered to them by the liquid and the
filling pipes c, rises to a considerable pressure of the gases. This pressure not
only brings the molecules of the gases closer together, but also promotes their
intimate contact with the liquid.
In order to still further retard the movement of the gases and increase their
pressure, the small filling pipes c may be provided in their interior with broad flat
projections which are arranged obliquely and alternate with each other, as shown
in Fig. 3. Such projections partly retard the gases and partly impart to them a
helical movement. For the same purpose the small pipes may be provided with
inner helical walls c³, as represented in Fig. 4.
If a uniform mixture of sulphurous acid gas and nitrous acid gas is caused to
pass in conjunction with air through such a column, and water is caused to flow
down in the latter, the water will absorb sulphurous gas and a weak sulphuric acid
is produced by reaction with part of the nitrous acid gas. If nitrous acid gas
alone is caused to pass through the column and sulphuric acid, suitably of 50 per
cent. and more, to How down, the latter absorbs the nitrous acid. If sulphurous
acid gas mixed with air is caused to pass through the column, and sulphuric acid
containing nitrous acid to flow down, concentrated sulphuric acid is formed, the
nitrous acid passing over in the current of gas.
These three operations rendered possible by the column may be so combined that
in a continuous working a highly concentrated sulphuric acid may be produced free
from nitrous acid, the latter being used again in the process in the manner described
hereafter.
For the above purpose several columns such as described are so combined to
form a battery that the gases leaving one column at the top are conducted down
into the lower part of the next column. The fresh sulphurous gas mixed with air
is conveyed in the first column, which is simultaneously supplied with strong
sulphuric acid containing nitrous acid. At the beginning of the process and when
necessary during the same the battery may be supplied at a suitable point with
nitric acid for developing nitrous acid gas. As in the first column the sulphurous

page_text: gas is in excess, an energetical formation of sulphuric acid takes place which unites
with the sulphuric acid flowing down through the column and strengthens the same.
On the other hand, the nitrous gas passes over into the gases which thus the
further they advance, become poorer and poorer in sulphurous acid gas and richer
in nitrous gas, until a point is reached where the excess of the former disappears,
when the gases are caused to pass through a column which is supplied with water
instead of with sulphuric acid. The water rapidly absorbs the sulphurous acid
from the gas mixture so that the mixture of nitrous acid gas and air is in contact
with an aqueous solution_of_sulphurous-acid, whereby-sulphuric acid-is-produced.
The latter is, however, too weak for absorbing nitrous gas, therefore the latter
remains in the current of gas. In a following column this weak acid is caused to
pass down to absorb the remainder of the sulphurous acid gas from the gas current,
wherchy again sulphuric acid is produced. Now the current of gas consists
substantially of nitrous acid and air. In order to obtain the former, strong
sulphuric acid taken from the battery at a suitable point is distributed through the
last columns; this acid absorbs the nitrous acid gas so that the current of gas
leaving the last column will be free from acid gases. The solution of nitrous acid
in sulphuric acid thus obtained in the last column serves as the sulphuric acid
containing nitrous acid the front columns are to be supplied with. By properly
regulating the process it is possible to obtain in the front columns strong sulphuric
acid free from nitrous gas and to raise the concentration in the first column to
66 degress.
In the diagram Fig. 5 a battery is shown composed of five columns a¹, a², a³, a+
and a, all filled with small pipes c and communicating with each other in the
manner stated, by large pipes h1, h2, h3, h. The fresh mixture of sulphurous gas
and air enters the first column a¹ through the gas inlet d, and the spent gases leave
the battery through the outlet e of the fifth column a³.
With such a battery of five columns the operation is preferably effected in such
a manner that through the first column a¹ passes down the acid from the fifth
column a, through the second column a² the acid from the fourth column aª,
through the third column a³ water, through the fourth column a' the weak acid
from the third column a³, and through the fifth column as a portion of the strong
acid from the first column a¹. Or through the first column a' may descend acid
from the fifth column a' and likewise through the second column a², through
the third column a³ water, through the fourth column a' the weak acid from
the third column a³ and through the fifth column as the acid from the fourth
column a*.
The foregoing statement will enable any expert to adapt the present invention
to particular requirements, arrange the number of columns and provide for the
distribution accordingly.
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 I am
aware that in combination with the leaden-chamber process columns or towers
have already been used for the purpose of recovering the nitrogen compounds
present in the gas current leaving the chambers, and of expelling said compounds
from the sulphuric acid produced in the chambers, and I do not broadly claim the
use of same, but what 1 claim is :-
1. The improved process of producing sulphuric acid which consists in causing
sulphurous and nitrous gases mixed with air to pass slowly and under pressure
through one or more columns provided with numerous small passages from the
bottom to the top and causing simultaneously water to flow through these passages,
substantially as described.
2. The improved process of producing sulphuric acid which consists in causing
sulphurous and nitrous gases mixed with air to pass slowly and under pressure
through one or more columns provided each with numerous small passages from the
bottom to the top, causing simultaneously water to flow through these passages,

page_text: and absorbing the remaining nitrous and sulphurous gases from the issuing gaseous
current by passing the same slowly and under pressure through one or more
similar columns through which sulphuric acid is caused to flow, substantially as
described.
3. The improved process of producing sulphuric acid which consists in causing
sulphurous and nitrous gases mixed with air to pass slowly and under pressure
through one or more columns provided with numerous small passages from the
bottom to the top causing simultaneously water to flow through these passages,
absorbing the remaining nitrous and sulphurous acid gases from the issuing gaseous
current by passing the same slowly and under pressure through one or more
similar columns through which sulphuric acid is caused to flow, and utilizing the
solution of nitrous acid in sulphuric acid obtained in the last named columns for
preparing the said mixture of sulphurous and nitrous gas with air by causing the
said solution to pass through one or more other similar columns through which a
mixture of sulphurous gas and air is caused to pass slowly and under pressure the
sulphuric acid being thereby freed from nitrous acid and concentrated, substantially
as described.
4. A column for producing sulphuric acid consisting in an acid resistant casing
provided with gas inlet at the bottom, gas outlet at the top, acid outlet at the
bottom, and liquid distributing device at the top, and being filled with small tubes
of burnt clay arranged in layers so as to alternate with each other, or their
described equivalent, substantially as and for the purpose stated.
5. A battery so composed of a number of columns such as defined by Claim 4
that each preceding column communicates at its top with the bottom part of the
following one, substantially as and for the purpose stated.
Dated this 12th day of March 1895.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.