Improvements in Obtaining Carbonic Acid Gas from Mixtures with other Gases, Obtaining and Utilising the Residual Gases or otherwise, and in the Production of Carbonates of Ammonia.
Year: 1888

page_text: Date of Application, 22nd Oct., 1888
Complete Specification Left, 22nd July, 1889-Accepted, 24th Aug., 1859
PROVISIONAL SPECIFICATION.
Improvements in Obtaining Carbonic Acid Gas from Mixtures with
other Gases, Obtaining and Utilising the Residual Gases or
otherwise, and in the Production of Carbonates of Ammonia.
I, CARL FRIEDRICH CLAUS of Suffolk House Cannon Street, London, E.C.,
Chemist do hereby declare the nature of my said invention to be as follows:-
I treat the gases containing the carbonic acid in a series of scrubbers or washers or
analogous apparatus with gaseous or liquid ammonia, whereby the carbonic acid is
absorbed by the ammonia and carbonate or sesquicarbonate of ammonia is formed,
whilst the residual gases pass away out of the scrubbers.
If the residual gases are applicable for useful purposes, then I convey the same into
gas holders for further use, for instance if the gas mixture consists of carbonic acid
and hydrogen, the hydrogen would be conveyed into the Gas holder.
A Gas mixture as obtained by heating carbonic oxide and steam to a high tempera-
ture would be of that composition. In a like manner carbonic acid and nitrogen may
be obtained separately.
The carbonate or sesquicarbonate of ammonia formed as above stated, I heat in the
manner which will be described hereafter and I obtain thereby carbonic acid gas in
the free state, which is collected in gas holders for use, and at the same time if desired
a solution of sesquicarbonate of ammonia as will be seen by the following description,
may be obtained.
The aforesaid process is modified according to whether carbonic acid is the only
product to be obtained, or whether both carbonic acid and the residual gases are to be
utilised separately and also whether a solution of sesquicarbonate of ammonia is to be
obtained at the same time or not.
In the case when Carbonic acid only is to be obtained without the simultaneous
production of sesquicarbonate of ammonia, I make use of any fuel gases or products
of combustion, such as limekiln-gas or other furnace gases, but I prefer to use those
free from soot or tarry matter, such as those for instance which arise from the
combustion of gaseous fuel.
Should the gases to be used however contain these impurities 1 remove the same
by washing before proceeding to operate for the extraction of carbonic acid. Any
sulphurous acid which the gases may contain I remove also previously by washing
the gases with water in a scrubber filled with limestone, or by similar means or
by, a preliminary treatment in a scrubber by means of aminonia liquor. When this
ammonia liquor has become saturated with sulphurous acid the ammonia is liberated
therefrom with lime and used again and again for the same purpose.
not.
After the fuel gases have been freed from these impurities they are conducted through
a series of scrubbers or washers. Any number of these scrubbers may be used for
this purpose, it is however not well to use less than two. I will assume for the
purpose of this description that four are being used. The passage of the gases
through the series of scrubbers is effected either by means of fans, exhausters or
by chimney draught according to whether the residual gases are to be utilised or
If they are to be utilised then an exhauster drives them into the gas holder.
The gases pass into the bottom of the first scrubber, ascend it and issue from the
top through a pipe which conveys them to the bottom of the second scrubber and so
forth until they pass out of tho last one. Into the second of the scrubbers free
ammonia is admitted either in, the gaseous state or as liquid ammonia. Down the
last, that is in this case, the fourth scrubber, water is showered by means of any
of the well known liquor distributors. The water running through the scrubber
arresis any free or carbonate of ammonia which might otherwise escape and be

page_text: lost. To prevent however more completely the possibility of any ammonia
escaping from the fourth scrubber a lead lined additional scrubber is used the
packing of which (coke or pebbles) is kept moistened with sulphuric acid, which
arrests any ammonia.
All the scrubbers are filled with coke or other porous material. The liquid collecting
on the bottom of the fourth scrubber is pumped by a continuously working pump on
to the top of the third scrubber and is made to trickle through by means of a distributor.
From thence it passes in a like manner through the rest of the scrubbers until it
arrives at the bottom of the scrubber at which the gases first enter. Thus the
passage of the liquor is from the last scrubber towards the first, whilst the gases
travel from the first scrubber towards the last.
The Gases in their passage become gradually poorer and poorer in carbonic acid
whilst the Liquor in its passage becomes gradually stronger in per centage of
ammonia or of carbonate of ammonia. The liquor in passing the second scrubber
that is the one into which free ammonia is admitted either in the gaseous or liquid
state as will be more fully described hereafter, contains there considerable quantities of
free ammonia, which as it goes nearer to the scrubber in which the gas is richest in
carbonic acid, is gradually converted into carbonate. At the bottom of the first
scrubber the liquor should contain principally sesqui carbonate of ammonia and the
flow of gas through the scrubbers is so regulated that all the ammonia liquor issuing
from the first scrubber is of that nature.
The flow of water on the last scrubber and consequently of the liquor through the
scrubbers should be so regulated that when arrived at the bottom of the first it does
not contain less than two per cent, of nor much more than eight to ten per cent, of
ammonia.
If carbonic acid only is to be produced by this process then five per cent. of ammonia
in this liquor is the most useful per centage. In the case however where sesqui
carbonate of ammonia is to be produed at the same time and when such sesqui
carbonate of ammonia is to be available for purposes not forming any part of this
process then the liquor may be worked up to eight or ten per cent. of ammonia.
If Carbonic Acid in a pure form is the only object to be attained by this process and
the composition or purity of the residual gases leaving the last scrubber is of no con-
sideration I make a bye pass of a portion of the gases before they enter the first
scrubber and convey that portion into the bottom of the last scrubber or a small
portion of the gases may be admitted into each scrubber the object being that the
excess of carbonic acid may assist to arrest the escape of free ammonia from the
last scrubber.
The liquor which collects at the bottom of the first scrubber is constantly and as
fast as it collects there conveyed away by a continually working pump into another
part of the plant distinct from the scrubbers in which the carbonic acid is separated
from the ammonia by heating the solution of carbonate_ or sesqui carbonate of
ammonia.
This plant consists of firstly the condensing scrubber secondly the washing scrubber
and thirdly the heating apparatus.
The Liquor from the first gas scrubber if not sufficiently cold is first passed thro'
suitable coolers (Liebig's Coolers will answer the purpose). It then passes down
the condensing scrubber and from thence into the heating apparatus. The con-
densing scrubber is similar in construction & arrangement to an ordinary gas scrubber
and so is also the washing scrubber. From the bottom of the condensing scrubber
the liquor runs into the heating apparatus. This consists preferably of a number of
shallow closed tanks one placed above another a space being left between each two of
them and the whole set being enclosed in an air-tight casing or heating chamber.
Different constructions of heating vessels may be used but with less advantage.
These shallow tanks are further fitted with connection pipes which convey the gases
liberated in the lowest one to the next one above it and so on to the uppermost one,
from whence they pass into the condensing scrubber. By means of the same (or
similar) connecting pipes the liquor runs from the condensing scrubber in the

page_text: opposite direction to the bottom tank of the heating apparatus traversing in a zig
zag way all the intervening tanks.
Steam or hot gases are conveyed into the heating chamber above referred to, by
means of which the liquor flowing through the closed tanks is heated in such a
manner that the topmost one acquires a temperature of about 180 to 190° F. the
temperature in the lowest one being about 200° F.
The effect of the heating is that the greatest part of the carbonic acid (about #)
passes away in the free state or accompanied with only a small quantity of ammonia.
It enters into and ascends the condensing scrubber where most of the ammonia is
taken up by the cold liquor coming from the first gas scrubber & passes along with
the descending liquid back into the heating apparatus. The free carbonic acid now
passes forward towards the gas holder, but passos previously through the washing
scrubber wherein the last trace of ammonia is washed out by means of water & finally
through a lead lined acid scrubber filled with a porous material saturated with sulphuric
acid and thence to the gasholder.
The liquor from the washing scrubber is lifted by a continually working pump into
the condensing scrubber and travels thence along with the first scrubber liquor into
the heating apparatus. From the bottom of the heating apparatus, the liquor which
contains now principally free ammonia, may be passed through water cooled pipes and
used again for absorbing fresh' quantities of carbonic acid gas in the gas scrubbers.
But since by the constant use of wash waters in the two washing scrubbers described
the liquor would soon become too diluted for useful application, I therefore prefer the
following method of using it over again, viz. :-I convey it by means of another con-
tinually working pump to the top of another scrubber or tower which I call the
distilling tower. It is made to trickle down and descend this tower or scrubber whilst
a current of steam, superheated steam, hot air or hot fuel gases is caused to ascend in
the same and to issue from a pipe in the top. The flow of the liquor and the current
of steam, heated air or gases is so regulated, that when the liquor arrives at the bottom
of the distilling tower, it is perfectly free from any volatile ammonia. The spent liquor
after being cooled is used instead of water for washing in the two washing scrubbers
above mentioned. In time sulphite and sulphate of ammonia accumulates in this
liquor from which I free the same by distillation with lime and analogous alkaline
substances.
The ammonia which has in the distilling tower been expelled from the liquor passing
down it, is after being cooled in a suitable cooling apparatus passed into the second
scrubber.
In the case when carbonic acid only is to be obtained, or when carbonic acid and
the residual gases are both to be utilised but without simultaneous production of sesqui
carbonate of ammonia the same quantity of ammonia is continually circulated through
the scrubbers and the ammonia regenerating apparatus, in a continuous cycle. No
ammonia needs to be added to the stock thus circulating and no ammonia is taken out
of this circulation.
But if at the same time sesqui carbonate of ammonia is to be produced and it and
the carbonic acid are to be employed in the manufacture of bi-carbonate of soda by
the ammonia soda process then the ammonia taken out of circulation for this purpose
in the form of sesqui carbonate is constantly supplemented by the free ammonia
obtained in that process by the decomposition of chloride of ammonium (also resulting
in that process) by lime, magnesia or other means.
The fuel gases or other gas mixtures, such as hydrogen and carbonic acid, nitrogen
and carbonic acid or hydrogen, carbonic oxide and carbonic acid if they issue from
their sources in a heated state should be cooled down before entering the gas scrubbers
to the temperature of the air. This may be done by applying the heat contained
therein for heating the air chamber of the heating apparatus. After passing the
heating apparatus, they are further cooled by any suitable cooling apparatus. But
I utilise their heat also by employing them instead of steam in the distilling
apparatus.

page_text: If the residual gases are to be utilised as for instance hydrogen gas, it is essential
that they should be, when leaving the last gas scrubber, in as great state of purity as
is practicable, all the carbonic acid accompanying them should be removed therefrom
and be taken up by ammonia in the preceding scrubbers. No excess of carbonic acid
is therefore admitted into the bottom of the last scrubber to ensure the ammonia to be
thoroughly neutralised thereby, but on the contrary a sufficient excess of free ammonia
(is admitted into the scrubber to ensure the presence of a large excess of ammonia in
the second or third scrubber.
If by the combination of the carbonic acid with the free ammonia an amount of,
heat is produced, which would tend to volatilise some ammonia from the liquor and to
drive it forward towards the last scrubber or if the proper absorption of the carbonic
‘acid' by the ammonia is endangered thereby, suitable means are applied to cool either
the gases or the liquors passing from one scrubber to the other.
I wish it to be understood that I apply the process or processes herein referred to,
to such gas mixtures only, which I have mentioned above and not to the gas mixture
obtained by the distillation of coal for illuminating purposes.
It now remains to be described in which manner sesqui carbonate of ammonia
may be obtained simultaneously with carbonic acid.
In the foregoing description of the process of treating the liquor in the heating
apparatus it was said that a certain portion of the ammonia leaves the heating apparatus
together with the carbonic acid and passes into the condensing scrubber in which it is
condensed and returned to the heating apparatus. Now when it is the object of
obtaining sesqui carbonate of ammonia as an essential bye product I do not run the
solution of sesqui carbonate of ammonia, when arrived at the bottom of the condensing
scrubber, back into the heating apparatus but cause it to pass into receptacles from which
after being cooled it is drawn and used in the ammonia soda process. I also employ
a higher temperature in the heating vessels than stated in the former case, in order to
leave less ammonia in the liquor passing out of the heating vessel. With some little
practice a temperature may be arrived at, at which so much ammonia only is left in
the liquor, that to one equivalent of sesqui carbonate, of ammonia obtained as a
saturated solution, one equivalent or more if desired of free carbonic acid may be passed
on to the gas holder.
In the measure as ammonia is removed from circulation the ammonium arising
from the decomposition of chloride of ammonia (resulting from the ammonia soda
process) is admitted into the scrubbers and the flow of gases containing carbonic acid
through the scrubbers is also so regulated that the ammonia so admitted may issu
from the first scrubber as a solution of sesqui carbonate.
Dated 2nd of October 1888
CARL FRIEDRICH CLAUS.
COMPLETE SPECIFICATION.
or
Improvements in Obtaining Carbonic Acid Gas from Mixtures with
other Gases, Obtaining and Utilising the Residual Gases
otherwise, and in the Production of Carbonates of Ammonia.
I, CARL FRIEDRICH CLAUS Suffolk House Cannon Street, Chemist, do hereby
declare the nature of my said invention and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:-
I treat the gases containing the carbonic acid in a series of scrubbers or washers
or analagous apparatus with gaseous or liquid ammonia whereby the carbonic acid is
absorbed by the ammonia and carbonate or sesquicarbonate of ammonia is formed
whilst the residual gases pass away out of the scrubbers.
If the residual gases are applicable for useful purposes, then I convey the same
into gasholders for further use, for instance if the gas mixture consists of carbonic
gas holder.
acid and hydrogen the hydrogen would be conveyed into the

page_text: A gas mixture as obtained by heating carbonic oxide and steam to a high
temperature would be of that composition.
In a like manner carbonic acid and nitrogen may be obtained separately.
The carbonato or sesquicarbonate of ammonia, formed as above stated, I treat in
the manner which will be described hereafter and I obtain thereby carbonic acid
gas in the free state, which is collected in gas-holders for use, and at the same time
if desired a solution of sesquicarbonate of ammonia as will be seen by the following
description, may be obtained.
The aforesaid process is modified according to whether carbonic acid is the only
product to be obtained, or whether both carbonic acid and the residual gases are to be
utilised separately and also whether a solution of sesquicarbonate of ammonia is to be
obtained at the same time or not.
In the case when carbonic acid only is to be obtained without the simultaneous
production of sesquicarbonate of ammonia, I make use of any fuel gases or products
of combustion, such as limekiln gas or other furnace gases, but I prefer to use those
free from soot or tarry matter, such as those for instance which arise from the
combustion of gaseous fuel.
Should the gases to be used however contain those impurities I remove the same
by washing before proceeding to operate for the extraction of carbonic acid. Any
sulphurous acid which the gases may contain I remove also previously by washing
the gases with water in a scrubber filled with limestone, or by similar means or by
a preliminary treatment in a scrubber by means of ammonia liquor. When this
ammonia liquor has become saturated with sulphurous acid the ammonia is liberated
therefrom with lime and used again and again for the same purpose.
After the fuel gases have been freed from these impurities they are conducted
through a series of scrubbers or washers. Any number of these scrubbers may be
used for this purpose, it is however not well to use less than two.
I will assume
for the purpose of this description that four are being used.
The passage of the gases through the series of scrubbers is effected either by means
of fans, exhausters or by chimney draught according to whether the residual gases
are to be utilised or not. If they are to be utilised then an exhauster drives them
into the gasholder.
The gases pass into the bottom of the first scrubber, ascend it and issue from the.
top through a pipe which conveys them to the bottom of the second scrubber and
so forth until they pass out of the last one. Into the second of the scrubbers free
ammonia is admitted either in the gaeous state or as liquid ammonia.
Down the last,
that is in this case, the fourth scrubber, water is showered by means of any of the well
known liquor distributors. The water running through this scrubber arrests any free
or carbonate of ammonia which might otherwise escape and be lost. To prevent how-
ever more completely the possibility of any ammonia escaping from the 4th scrubber
a lead lined additional scrubber is used the packing of which (coke or pebbles) is
kept moistened with sulphuric acid, which arrests any ammonia passing into it.
All the scrubbers are filled with coke or other porous material. The liquid
collecting on the bottom of the 4th scrubber is pumped by a continuously working
pump on to the top of the third scrubber and is made to trickle through by means of a
distributor. From thence it passes in a like manner through the rest of the scrubbers
until it arrives at the bottom of the scrubber at which the gases first enter. Thus
the passage of the liquor is from the last scrubber towards the first, whilst the gases
travel from the first scrubber towards the last.
The gases in their passage become gradually poorer and poorer in carbonic acid
whilst the liquor in its passage becomes gradually stronger in percentage of ammonia
or of carbonate of ammonia. The liquor, in passing the second scrubber that is the
one into which free ammonia is admitted, either in the gaseous or liquid state as will
be more fully described hereafter, contained there considerable quantities of free
ammonia, which as it goes nearer to the scrubber in which the gas is richest in
carbonic acid, is gradually converted into carbonate.

page_text: At the bottom of the first scrubber the liquor should contain principally sesqui-
carbonate of ammonia and the flow of gas through the scrubbers is so regulated that
all the ammonia liquor issuing from the first scrubber is of that nature. The flow of
water on the last scrubber and consequently of the liquor through the scrubbers
should be so regulated, that when arrived at the bottom of the first it does not contain
less than 2% of, nor much more than, 8 to 10% of ammonia.
If carbonic acid only is to be produced by this process, then 5% of ammonia in this
liquor is the most useful per centage. In the case however when sesquicarbonate of
ammonia is to be produced at the same time, and when such sesquicarbonate of
ammonia is to be available for purposes not forming any part of this process, then
the liquor may be worked up to 8 or 10% of ammonia.
If carbonic acid in a pure form is the only object to be attained by this process
and the composition or purity of the residual gases leaving the last scrubber is of
no consideration, I make a byepass of a portion of the gases before they enter the
first scrubber and convey that portion into the bottom of the last scrubber; or a
small portion of the gases may be admitted into each scrubber, the object being
that the excess of carbonic acid may assist to arrest the escapo of free ammonia
from the last scrubber.
The liquor which collects at the bottom of the scrubber is constantly and as fast
as it collects there conveyed away by a continually working pump into another part
of the plant, distinct from the scrubbers, in which the carbonic acid is separated from
the ammonia by heating the solution of carbonate or sesqui-carbonate of ammonia.
This plant consists of, firstly the condensing scrubber, secondly the washing scrubber
and thirdly the heating apparatus.
The liquor from the first gas scrubber if not sufficiently cold is first passed through
suitable coolers (Liebig's coolers will answer the purpose). It then passes down
the condensing scrubber and from thence into the heating apparatus. The condensing
scrubber is similar in construction and arrangement to an ordinary gas scrubber and
so is also the washing scrubber. From the bottom of the condensing scrubber the
liquor runs into the heating apparatus. This consists preferably of a number of
shallow closed tanks, one placed above another a space being left between each two
of them and the whole set being enclosed in an airtight casing or heating chamber.
Different constructions of heating vessels may however be used but with less
advantage. These shallow tanks are further fitted with connection pipes which convey
the gases liberated in the lowest one to the next one above it and so on to the upper-
most one, from whence they pass into the condensing scrubber. By means of the
same (or similar) connecting pipes the liquor runs from the condensing scrubber in
the opposite direction to the bottom tank of the heating apparatus, traversing in a
zigzag way all the intervening tanks.
Steam or hot gases aro conveyed into the heating chamber above referred to by
means of which the liquor flowing through the closed shallow tanks is heated in such
a manner, that the topmost one acquires a temperature of about 180 to 190° F. the
temperature in the lowest one being about 200° F.
The effect of the heating is that the greatest part of the carbonic acid. (about 3)
passes away in the free state or accompanied with only a small quantity of ammonia.
It enters into and ascends the condensing scrubber, where most of the ammonia is
taken up by the cold liquor coming from the first gas scrubber and passes along with
the descending liquid back into the heating apparatus.
The free carbonic acid now passes forward towards the gasholder, but passes
previously through the washing scrubber wherein the last trace of ammonia is washed
out by means of water, and finally through a lead lined acid scrubber filled with a
porous material saturated with sulphuric acid and thence to the gasholder. The
liquor from the washing scrubber is lifted by a continually working pump into the
condensing scrubber and travels thence along with the first scrubber liquor into
the heating apparatus. From the bottom of the heating apparatus, the liquor which
contains now principally free ammonia may be passed through water-cooled pipes,

page_text: and used again for absorbing fresh quantities of carbonic acid gas in the gas scrubbers.
But since by the constant use of wash-waters in the two washing scrubbers described,
the liquor would soon become too diluted for useful application. I therefore prefer
the following method of using it over again-videlicet, I convey it by means of
another continually working pump to the top of another scrubber or tower which I
call the distilling tower. It is made to trickle down and descend this tower or
scrubber whilst a current of steam, superheated steam, hot air or hot fuel gases is
caused to ascend in the same and to issue from a pipe in the top. The flow of the
liquor and the current of steam, heated air, or gases is so regulated that when the
liquor arrives at the bottom of the distilling tower, it is perfectly free from any
volatile ammonia. The spent liquor after being cooled is used instead of water
for washing, in the two washing scrubbers above mentioned. In time sulphite and
sulphate of ammonia accumulates in this liquor from which I free the same by
distillation with lime or analogous alkaline substances.
The ammonia which has in the distilling tower been expelled from the liquor
passing down it, is (after being cooled in any suitable cooling apparatus) passed
into the second scrubber.
In the case when carbonic acid only is to be obtained or when carbonic acid and
the residual gases are both to be utilized, but without the simultaneous production of
sesquicarbonate of ammonia, the same quantity of ammonia is continually circulated
through the scrubbers, and the ammonia regenerating apparatus, in a continuous
cycle. No ammonia needs to be added to the stock thus circulating and no ammonia
is taken out of this circulation.
But if at the same time sesquicarbonate of ammonia is to be produced and it
and the carbonic acid are to be employed in the manufacture of bicarbonate of soda
by the ammonia soda process, then the ammonia taken out of circulation for this
purpose in the form of sesquicarbonate is constantly supplemented by the free
ammonia obtained in that process by the decomposition of chloride of ammonium
(also resulting in that process) by lime magnesia or other means.
The fuel gases or other gas mixtures such as hydrogen and carbonic acid, nitrogen
and carbonic acid or hydrogen, carbonic oxide and carbonic acid if they issue from
their sources in a heated state should be cooled down before entering the gas scrubbers
to the temperature of the air. This may be done by applying the heat contained
therein for heating the air chamber of the heating apparatus. After passing the
heating apparatus, they are further cooled by any suitable cooling apparatus. But
1 utilise their heat also by employing them instead of steam in the distilling
apparatus.
If the residual gases are to be utilised as for instance hydrogen gas, it is essential
that they should be, when leaving the last gas scrubber, in as great state of purity as
is practicable, all the carbonic acid accompanying them should be removed thereform
and be taken up by ammonia in the proceeding scrubbers. No excess of carbonic
acid is therefore admitted into the bottom of the last scrubber to insure the aminonia
to be thoroughly neutralised thereby, but on the contrary a sufficient excess of free
ammonia is admitted into the scrubber to insure the presence of a large excess of
ammonia in the second or third scrubber..
If by the combination of the carbonic acid with the free ammonia an amount of
heat is produced, which would tend to volatilize some ammonia from the liquor and
to drive it forward towards the last scrubber or if the proper absorption of the carbonic
acid by the ammonia is endangered thereby, suitable means should be applied to cool
either the gases or the liquors passing from one scrubber to the other.
I wish it to be understood that I apply the process or processes herein referred to
to such gas mixtures only which I have mentioned above and not to the gas mixture
obtained by the distillation of coal for illuminating purposes.
It now remains to be described in which manner sesquicarbonate of ammonia may
be obtained simultaneously with carbonic acid.
In the foregoing description of the process of treating the liquor in the heating
apparatus it was said that a certain portion of the ammonia leaves the heating apparatus

page_text: together with the carbonic acid and passes into the condensing scrubber in which
is condensed and returned to the heating apparatus. Now when it is the object of
obtaining sesquicarbonate of ammonia as an essential bye product I do not run the
solution of sequicarbonate of ammonia, when arrived at the bottom of the condensing
scrubber back into the heating apparatus but cause it to pass into receptacles from 5
which after being cooled, it is drawn and used in the Ammonia Soda process I also
employ a higher temperature in the heating vessels than stated in the former case,
in order to leave less ammonia in the liquor passing out of the heating vessel.
With some little practice a temperature may be arrived at, at which so much
ammonia only is left in the liquor, that to one equivalent of sesquicarbonate of
ammonia obtained as a saturated solution, one equivalent or rather more, if desired,
of free carbonic acid may be passed on to the gasholder.
In the measure as ammonia is removed from circulation the ammonia arising from
the decomposition of chloride of ammonium (resulting from the Ammonia Soda
process) is admitted into the scrubbers and the flow of gases containing carbonic acid
through the scrubbers is also so regulated that the ammonia so admitted may issue
from the first scrubber principally as a solution of sesquicarbonate.
Having now particularly described and ascertained the nature of my said inven
tion and in what manner the same is to be performed 1 declare that what 1
claim is-
1. The obtaining of carbonic acid gas by abstracting the same from mixtures of
carbonic acid with other gases in a series of scrubbers by means of free ammonia
either in the gaseous or liquid form, dissolving or washing out the carbonate or
sesquicarbonate of ammonia formed by water in these scrubbers and heating such
solutions so as to liberate again the carbonic acid in a pure state, substantially as
described.
II. The continuous cyclical process by which the same quantity of ammonia is
used again and again repeatedly substantially as described.
III. When ammonia is supplied to the scrubbers, resulting from the ammonia soda
process, the obtaining of strong solutions of sesquicarbonate of ammonia, by absorbing
the gases leaving the heating apparatus hereinbefore mentioned into water and
obtaining carbonic acid at the same time; substantially as described.
IV. Effecting the heating of the sesquicarbonate of ammonia solution obtained in
the scrubbers by means of the waste heat of fuel gases to be operated upon for the
extraction of carbonic acid, substantially as described.
V. Distilling of the ammonia from the liquor, leaving the heating apparatus by means
of hot fuel gases or steam being passed through the liquor, whilst descending a towe
or scrubber substantially as described.
VI. The use of the residual gases obtained by the removal of carbonic acid from
mixture of gases, substantially as described.
CARL FRIEDRICH CLAUS.