Improvements in Process of Extraction of Carbonic Acid Gas from Bicarbonates.
Year: 1891

page_text: Date of Application, 1st June, 1891-Accepted, 1st Aug., 1891
COMPLETE SPECIFICATION.
Improvements in Process of Extraction of Carbonic Acid Gas from
Bicarbonates.
4.
I, Dr. EDWARD. LUHMANN Andernach-on-Rhine Chemist, 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:-
The process in use up to the present time for extracting carbonic acid gas from
carbonate solutions which consisted in decomposing the said solutions, and thus
creating escape of the gases by boiling these liquids, is so far defective that it is in
the highest degree useless in practice for industrial purposes, since it is impossible
to attain a complete decomposition of same, and consequently the residue or waste
liquor can only be regenerated with the greatest difficulty and in an incomplete
fashion. This is more especially so in the case of the decomposing of bicarbonate
salts, which are used in obtaining carbonic acid by ebullition for the purpose of
extracting the superfluous carbonic acid, and by regenerating the residue. liquor
after same has been cooled by means of fresh quantities of carbonic acid since
neither the complete extraction of the carbonic acid, nor the complete transformation.
of the material into mono-carbonate, has been obtained by methods employed up to
the present time.
i
As a result of a series of experiments carried out on a large commercial scale, I
have ascertained that the giving up and re-absorption of carbonic acid, takes place
to its maximum extent with the least possible heat and absorption of power, when
the ebullition of the bicarbonate or protocarbonate (the salts intermediate in com-
position between the mono and bicarbonate salts) salts is carried out in two stages
in such a way as to allow the main part of the carbonic acid to, be freed from the
boiling solution under ordinary atmospheric pressure, whilst the residue liquor thus
obtained is introduced into a vessel or boiler to be heated therein under a medium
pressure, thus transforming the residue of bicarbonate or protocarbonate salts into
mono-carbonates by the extraction of further quantities of carbonic acid by means
of a powerful creation of steam accompanying the ebullition.
t
It has mainly been ascertained by a series of extensive experiments that although
the decomposition of the bicarbonate liquor and of the carbonate salts in their
different stages takes place with greater difficulty under high than under low
pressure still this is fully compensated by maintaining the constant powerful creation
of steam in the boiler containing the salt solution. This is very important for the
easy and rapid production of carbonic acid from the solution and should be observed
in the boiling not only of the bicarbonate solution under atmospheric pressure, but
also in the further boiling under higher pressure of the mono-carbonate, residue
solution.
"The process subject of this Specification is advantageous, not only in consequence
of the effective and complete fashion in which both the decomposition and the
regeneration take place on a large scale, but more especially because the necessary
concentration of the liquor takes place during the reaction and the, regeneration,
and also in consequence of the steam which is produced at the time of the
concentration in the boiler being utilized again for the purpose of heating the
bicarbonate salt brine.
The disposition is shewn in the accompanying drawing,
«is a boiler, used for
boiling therein the bicarbonate salt liquor under pressure. This liquor is carried
to the absorption tower "b" of usual construction by means of a pipe " which
allows same to pass through a cooling coil or apparatus and a collecting pipe"."
This absorption tower may be filled with fragments of coal or any other suitable
material, presenting large surfaces, and in this way the solution is made to run over
..

page_text: 10.
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and down this filling material of the tower, which greatly increases the circuit it
has to traverse, whilst the carbonic acid coming from the washing cylinder traverses
the tower in the opposite direction. This carbonic acid is being produced in the
ordinary way and enters the washing cylinder "c" at the lower part of same by the
pipe. This cylinder being filled with fragments of marble whilst these are
continuously kept moist by arfine shower of water.coming from the reservoir"
The carbonic acid which is thus freed of any impurities, enters the absorption
apparatus,"" by means of the pipe. "" in the opposite direction to the solution
which enters same at the top part. The solution has thus a great absorbent-power
and forms a bicarbonate or a protocarbonate salt, it passes. through the pipe ""
into the vessel "n" and is thence carried into the boiling apparatus "k" by means
of a pump "p" and a pipe "2"
This boiling apparatus "" is heated by means of the steam emanating from the
boiler "a" which leaving the dome of same passes through the pipe
22
emerging
in the boiling apparatus through a series of pipes and thus entering the solution of
same. The steam here heats and decomposes the solution to such an extent that it
gives up most of its carbonic acid which becomès mixed with that. carried away
with the steam resulting from ebullition. The carbonic acid which is thus freed
passes through pipe "" into a cooler supplied from a reservoir "w" by means
of the pipe and thence into the collecting vessel " "where the condensed
water is collected whilst the carbonic acid is conducted by means of pipe "s" to a
gasometer, not shewn in the drawing. The condensing water from vessel. "
$ is
allowed to run into tank "" so as to maintain a uniform concentration of the
solution. This is absolutely necessary under all circumstances as otherwise the
solution would become so dense as to be unable to retain the salt in solution. but
would throw it off and clog the pipes.
The hot solution coming from the boiling yat "" which runs out of same into
the vessel "" through the pipe "m is not yet freed of all the bicarbonate or
protocarbonate salts which it holds in solution. It is still to a certain extent
undecomposed and would not only, if used again in that state, hamper the pro-
duction of carbonic gas to a great extent, but it would be very difficult to regenerate
this impure residue-solution into bicarbonate or protocarbonate salts, that is to say
that the small absorbent power of this impure solution would greatly impede the
further processes. To avoid this the impure solution is taken up by the pump "p"
by means of p.pes "ee" and pumped into boiler "a." It has been necessary up
to the present time to continue the boiling for extracting purposes so as to maintain
a concentration of the solution without however effecting the decomposition of the
remaining parts of bicarbonate or protocarbonate salts, but it is now possible to
discontinue the further heating immediately after the separation of the bicarbonate
or protocarbonate salts obtained by the first boiling process without steam; and also
to attain the necessary concentration of the brine, as well as the complete extraction
of all the superfluous carbonic acid in a boiler under medium pressure, this at the
same time producing steam under a given suitable pressure which can be utilized
for heating and other purposes: The great advantages of this process are that it
permits of a complete and thorough utilization of the heat generated, whilst
facilitating the processes throughout.
Having now particularly described and ascertained the nature of my invention
and the special way in which the same is to be carried out in practice I claim:
1. The construction and use of an apparatus for the extraction of, carbonic acid
gas from carbonate solutions by ebullition in two stages and under different pressures
substantially as described.
2. In an apparatus mainly as described and claimed, in Claim 1. The use of two
boiling vessels in which liquid is kept under different pressures. substantially as
described:
3. In an apparatus constructed for the purpose of extracting carbonic acid gas
from carbonate solutions in two stages, the process and means of utilizing steam

page_text: generated by the boiler or vessel in which the liquid is under higher pressure for the
purpose of heating and boiling the solution of the low pressure boiler substantially
as described.
4. In an apparatus for the purpose referred to in above Specification and claimed
in the previous claims, the disposition and construction by which the concentration
of the solution is kept constant consequent to the uninterrupted flow of the liquids
in their two stages substantially as described.
5. In an apparatus essentially as set forth in the above Specification a combina-
tion by means of which the steam produced in the high pressure boiler is used for
heating purposes of the first stage boiler with utilization of the gases and steam
emanating therefrom produced in the solution holding boiler substantially as
described.
Dated this 20th day of May 1901
F. FANTA,
85, Gresham Street, E.C., Agent for Applicant.