An Improved Process for Obtaining Carbonic Acid from Gas-mixtures in the Dry Way, and Apparatus therefor.
Year: 1895

page_text: Date of Application, 12th July, 1895
Complete Specification Left, 11th Apr., 1896-Accepted, 27th June, 1896
An Improved Process for Obtaining Carbonic Acid from Gas-mixtures
in the Dry Way, and Apparatus therefor.
I, Dr. Phil. Wilhelm RAYDT, of 195 Silberburgstrasse, Stuttgart, in the
Empire of Germany, Manufacturer, do hereby declare the nature of this invention
to be as follows:-
This invention relates to an improved process for obtaining carbonic acid from
gas mixtures in the dry way and to apparatus therefor.
The production of carbonic acid out of appropriate gas mixtures is up to the
present time, according to Ozouf, effected by the wet process in such a manner
that a mono-carbonate liquor is placed in mixing vessels provided with stirring
device or in so called towers or columns of various construction and brought into
intimate contact with a gaseous mixture obtained by combustion or otherwise and
thereby converted into bi-carbonate liquor. The bi-carbonate liquor is then
pumped into a separating vessel and by heating separated into carbonic acid and
mono-carbonate liquor, so that the absorption and separation takes place in a
continuous process.
This process more or less subject to variation, results, when carried out in
practice on a large scale, in many defects and difficulties, the radical obviation of
which is desirable in view and to the benefit of the largely developed industry of
manufacturing carbonic-acid. Especially inconvenient is found to be the necessity
of continually moving and transferring the liquor by suitable pumping devices
from one vessel into another, further the destructive action effected by the liquors
upon all bodies with which they come in contact whereby the said bodies as well
as the liquors become spoiled after a comparatively short time, not to speak of the
re-tightening of all connecting places continuously necessary and of other repairs.
All these defects intimately connected with the nature of the liquor treated are
altogether obviated by entirely giving up the use of liquors for the purpose in
view and by applying instead of such solutions the respective bodies in their solid,
dry condition,
In view of the fact that the principally or usually applied mono-carbonates soda
and potash in absolutely dry condition do not absorb carbonic acid, and that this
process of absorption takes place according to the following equation:
therefore at least 18 parts of water in liquid or gaseous form must always be
present in 106 parts of monocarbonate in order that the reaction above indicated
be obtained. If this is properly attended to and carried out in an easily regulatable
manner from the technical point of view the difficulties attending the use of mono-
carbonate in solid form are obviated.
The process therefore should be so carried out that the mono-carbonate is,-in
as finely a divided state as possible that is to say in pulverized form, and placed in
a closed vessel and in the presence of the amount of humidity necessary for the
conversion into bicarbonate-brought sufficiently long in contact with the carbonic

page_text: acid gas mixture, until the conversion of the mono-carbonate into bicarbonate has
taken place entirely or partially. Thereupon the conduit for the passage of the
said gas mixture is closed, and by simply heating the powdered bicarbonate the
carbonic acid is expelled or separated therefrom whereupon the remaining mono-
carbonate is again treated with the carbonic acid gas mixture and so forth. The
apparatus serving for this purpose may be of various form, provided only that due
care be taken that the gases come into intimate contact with the pulverized
substance, that the requisite amount of water in liquid or gaseous form is supplied,
and that a suitable heating and cooling is rendered possible.
The apparatus described hereinafter merely represents an example of a con-
structional form for carrying out this process. Several of these apparatus are or
may be connected to form one larger apparatus for continuous working.
The monocarbonate is placed in an air tightly closeable vessel, and spread out
upon horizontal hurdles or wicker work, the bottom of which latter is formed by a
wire net or screen. Above each hurdle a system of pipes is arranged, having
perforations through which a measured quantity of water can be sprinkled over the
contents of each hurdle. Below each hurdle a second system of pipes is provided
through which heating gases or water steam for the purpose of heating can be
passed and likewise cold water for the purpose of cooling.
On starting the process appropriate water-receptacles, one of which appertains
to each system of perforated pipes aforesaid, are filled by a suitable feed-pipe
arranged so as to communicate with the said water receptacles. After this feed
pipe has then been emptied, closed at the bottom and placed in communication
with a conduit for the passage of compressed carbonic acid or air, suitably arranged
discharge cocks are opened by a joint lever device and the measured quantity of
water is thus in a fine shower sprinkled over the mono-carbonate. Thereupon
the previously cooled gases of combustion or another carbonic acid gas mixture is,
by the aid of a ventilating or suction device drawn from below through a main
pipe into the carbonating vessel and passed off through a corresponding pipe
arranged at the top of said vessel. After the conversion into bicarbonate has
thus taken place entirely or partially, hot gases of combustion or water steam are
passed through the systems of perforated pipes aforesaid and thus the absorbed
carbonic acid is expelled by heating. After this process of separation or expulsion
has been finished, the whole apparatus is cooled down by the aid of cooling water,
which is passed through the system of cooling pipes aforesaid, or the cooling of the
apparatus may also be left to the cooling action of the outer air. Instead of
adding the necessary amount of water in liquid form to the monocarbonate, the
said quantity of water may, as already indicated also be introduced into the
apparatus in gaseous form either in connection with the carbonating gas mixture or
separately.
In order to obtain a continuous working operation, several carbonating vessels
must be suitably connected with one another.
In this case where for instance six carbonating vessels are arranged, the
operation is suitably effected in the following manner: The gases of combustion
are by the aid of a ventilator or suction device drawn in from one or a plurality of
coke-furnaces, arrive through a suitable passage, first into a purifier suitably filled
with limestone, where they discharge any impurities and heterogeneous admixtures
such as dust or sulphurous acid, then serve-after arriving in two of the carbonating
vessels charged with bicarbonate the heating pipe system of which vessels they
traverse to expel the carbonic acid, whereby the said heating gases lose a portion
of their heat, then pass through a cooler and through the washing apparatus of
purifier and thence enter two absorption-apparatus charged with mono-carbonate
to which they give off their carbonic acid entirely or partially and are ther
discharged into the atmosphere through a ventilator."
The carbonic acid expelled from the first mentioned two carbonating vessels i
cooled down in a separate cooler and freed from aqueous vapour and subsequently
passed through the washing tower or purifier into a gasometer. From this latte

page_text: the carbonic acid is then conveyed through a drying apparatus into a compressor
in order to be liquefied therein or it is used for other technical purposes. During
this process of continuous working, the fifth and sixth carbonating apparatus or
vessels are cooled down to the temperature necessary for receiving carbonic acid,
by the passage of a current of cooling water.
When the carbonic acid has been expelled from the first carbonating vessel the
connections are so reversed that now carbonic acid is developed in the second and
the third and absorbed in the fourth and fifth whilst the sixth and first are being
prepared for receiving carbonic acid by suitable cooling.
The constructional form of the different constituent apparatus and the whole
arrangement may of course be variously modified. Also other substances than
the carbonates mentioned may be used for the same purpose for instance carbonate
of lime, magnesite, soda-lime and in treating these latter the carbonic acid may
first be expelled by the heating process and subsequently be substituted again,
and again be expelled in pure form by heating; mixtures of suitable substance are
likewise applicable.
Dated this 12th day of July 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
An Improved Process for Obtaining Carbonic Acid from Gas-mixtures
in the Dry Way, and Apparatus therefor.
I, Dr. Phil. WILHELM RAYDT, of 195 Silberburgstrasse, Stuttgart, 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 :-
This invention relates to an improved process for obtaining carbonic acid from
gas mixtures in the dry way and to apparatus therefor.
The production of carbonic acid from appropriate gas mixtures has, up to the
present time, according to Ozouf, been effected by the wet process by placing
a mono-carbonate liquor in a mixing vessel provided with stirring device or in so
called towers or columns of various construction and bringing it into intimate
contact with a gaseous mixture obtained by combustion or otherwise and thereby
converting the said liquor into bi-carbonate liquor. The bicarbonate liquor is then
pumped into a separating vessel and by heating separated into carbonic acid
and mono-carbonate liquor, so that the absorption and separation takes place in a
continuous process.
This process more or less subject to variation results, when carried into practice
on a large scale, in many defects and difficulties, the radical obviation of which is
desirable in view and to the benefit of the largely developed industry of
manufacturing carbonic acid. Especially inconvenient is found to be the necessity
of continually moving and transferring the liquor by suitable pumping devices from
ove vessel into another, further the destructive action effected by the liquors upon
all bodies with which they come in contact whereby the said bodies as well as the
liquors become spoiled after a comparatively short time, not to speak of the
re-tightening of all joints or connections continuously necessary and of other
repairs. All these defects intimately connected with the nature of the liquor
treated are altogether obviated by entirely dispensing with use of liquors for the
purpose in view and by applying instead of such solutions the respective bodies in
their solid, dry condition."
In view of the fact that the principally or usually applied mono-carbonates, soda

page_text: and potash in an absolutely dry condition do not absorb carbonic acid, and that the
process of absorption takes place according to the following equation:
therefore at least 18 parts of water in liquid or gaseous form must always be present
in 106 parts of mono-carbonate in order that the reaction above indicated be
obtained. If this is properly attended to and carried out in an easily regulatable
manner from a technical point of view, the difficulties attending the use of
mono-carbonate in solid form are obviated.
The process therefore should be so carried out that the mono-carbonate is--in as
finely a divided state as possible that is to say in pulverized form, and placed in a
closed vessel and in the presence of the amount of humidity necessary for the
conversion into bicarbonate-brought sufficiently long in contact with the carbonic
acid gas mixture, until the conversion of the mono-carbonate into bicarbonate has
taken place entirely or partially. Thereupon the conduit for the passage of the
said gas mixture is closed, and by simply heating the powdered bicarbonate the
carbonic acid is expelled or separated therefrom, whereupon the remaining
mono-carbonate is again treated with the carbonic acid gas mixture and so forth.
The apparatus serving for this purpose may be of various form, provided only that
due care be taken that the gases come into intimate contact with the pulverized
substance, that the requisite amount of water in liquid or gaseous form is supplied,
and that a suitable heating and cooling is rendered possible.
The apparatus hereinafter described merely represents an example of a
constructional form for carrying out this process.
Figure 1 represents a vertical cross section of the apparatus.
Figure 2 an horizontal cross section on the line x-x of Figure 1.
Figure 3 a section on the line y-y of Figure 1, and
Figure 4 shows diagrammatically the combination of several apparatus
constructed according to Figure 1, to form one larger apparatus for continuous
working.
The mono-carbonate is placed in an air tightly closeable vessel A, Figure 1, and
spread out upon horizontal trays or wicker work a, the bottom of which latter is
formed by a wire net or screen. Above each tray a a system of pipes b is arranged,
having perforations through which a measured quantity of water can be sprinkled
over the contents of each tray. Below each tray a second system of pipes c
is provided through which heating gases or steam for the purpose of heating can be
passed and likewise cold water for the purpose of cooling.
On starting the process appropriate water-receptacles d one of which appertains
to each system of perforated pipes b are filled by a suitable feed-pipe e arranged so
as to communicate with the said water receptacles. After this feed pipe e has been
emptied, closed at the bottom and placed in communication with a conduit for the
passage of compressed carbonic acid or air, suitably arranged discharge cocks fare
opened by a joint lever device and the measured quantity of water is thus sprinkled
over the mono-carbonate in a fine shower. Thereupon the previously cooled gases
of combustion or another carbonic acid gas-mixture is, by the aid of a ventilating
or suction device drawn from below through a main pipe 9 into the carbonating
vessel A and passed off through a corresponding pipe / arranged at the top of said
vessel. After the conversion into bi-carbonate has thus taken place entirely
or partially, hot gases of combustion or steam are passed through the systems of
pipes c and thus the absorbed carbonic acid is expelled by heating. After this
process of separation or expulsion has been finished, the whole apparatus is cooled
down by the aid of cooling water, which is passed through the system of pipes c, or
the cooling of the apparatus may also be left to the cooling action of the outer air.

page_text: Instead of adding the necessary amount of water in liquid form to the mono-
carbonate, the said quantity of water may, as already indicated also be introduced
into the apparatus in gaseous form either in connection with the carbonating gas
mixture or separately.
In order to obtain a continuous working operation, several carbonating vessels A
must be suitably connected with one another.
In Figure 4 of the annexed drawing six apparatus A¹ to A are represented
diagrammatically together with the necessary accessories.
The gases of combustion are by the aid of a ventilator or suction device V drawn
in from one or a plurality of coke-furnaces C, arrive through a suitable passage,
indicated by dotted line, first into a purifier R suitably filled with lime-stone, where
they discharge any impurities and heterogeneous admixtures such as dust, sulphurous
acid, then serve-after arriving in two of the carbonating vessels A' A² charged
with bicarbonate, the heating pipe system (c Figure 1) of which vessels they
traverse to expel the carbonic acid, whereby the said heating gases lose a portion
of their heat, then pass through a cooler K¹ and through the washing apparatus or
purifier W, and thence enter two absorption-apparatus A3 A4 charged with
mono-carbonate, to which they give off their carbonic acid entirely or partially and
are then discharged into the atmosphere through the ventilator V.
The carbonic acid expelled from the two carbonating vessels A' and A², the path
of which is indicated by the full line, is cooled down in a separate cooler K2 and
freed from aqueous vapour and subsequently passed through the washing tower or
purifier W2 into a gasometer G. From this latter the carbonic acid is then
conveyed through a drying apparatus T into a compressor K in order to be liquefied
therein or it is used for other technical purposes. During this process of continuous
working, the carbonating apparatus or vessels A' and A are cooled down to the
temperature necessary for receiving carbonic acid, by the passage of a current of
cooling water taking the course indicated by the chain-dotted line.
When the carbonic acid has been expelled from the carbonating vessel A', the
connections are so reversed that now carbonic acid is developed in the vessels A²
and A³ and absorbed in A* and A' whilst A and A' are being prepared for receiving
carbonic acid by suitable cooling.
The constructional form of the different constituent apparatus and the whole
arrangement may of course be variously modified. Also other substances than the
carbonates mentioned may be used for the same purpose for instance carbonate of
lime, magnesite, soda-lime, and in treatment these latter the carbonic acid may
first be expelled by the heating process and subsequently be substituted again, and
again be expelled in pure form by heating; mixtures of suitable substances are
likewise applicable.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The process of producing carbonic acid from gas-mixtures, according to which
monocarbonate or other appropriate substances in a dry state, in the presence of
the required amount of humidity by passing gases of combustion or other gaseous
carbonic acid mixtures into, or bringing in contact with, the said substances, are
partly or wholly transformed into bi-carbonate or other carbonates, from which
subsequently the absorbed.carbonic acid is partly or entirely separated.
2. The apparatus for carrying out the process referred to in the first claim,
comprising a vessel or receptacle with trays, upon which the monocarbonate or
other appropriate substances are spread out; a pipe connection or system of pipes
with perforations through which a measured quantity of water can be supplied or
instead of such system of pipes a pipe conduit, through which the gaseous mixture
and steam can be supplied simultaneously or separately; and a second system of
pipes through which the heating by heating gases or steam, and the cooling by
water can be alternately effected.

page_text: 3. The combination of the devices, referred to in the second claim, in such
a manner that simultaneously a part of these devices can be utilized for receiving
carbonic acid, a second part for delivery carbonic acid, whilst a third part is
prepared for receiving carbonic acid by being cooled down.
Dated this 11th day of April 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.