An Improved Process and Apparatus for the Separation of Carbonic Acid Gas from the Products of Combustion or other Mixed and less Soluble Gases.
Year: 1895

page_text: Date of Application, 9th Apr., 1895
Complete Specification Lef, 9th Jan., 1896-Accepted, 15th Feb., 1896
PROVISIONAL SPECIFICATION.
An Improved Process and Apparatus for the Separation of Carbonic
Acid Gas from the Products of Combustion or other Mixed and
less Soluble Gases.
We, HERBERT SAMUEL ELWORTHY, of 19, Hill Road, Bandra, Bombay, in
the Empire of India, Analytical Chemist, and PHILIP DURHAM HENDERSON, of
89, Philbeech Gardens, S.W., Gentleman, do hereby declare the nature of this
invention to be as follows:-
This process depends upon the great solubility of carbon dioxide in water, and
the much lower solubility of the other products of combustion.
In working with combustion gases we first pass them through any suitable form
of oxidizing furnace.
By this means the carbon monoxide present is at once converted into dioxide.
When the metallic oxide is exhausted it may be regenerated by passing air over it.
The gases may then be passed through a small scrubbing apparatus of the usual
well-known kind to remove sulphur dioxide, and thence either to a gas holder, or
direct to a compression pump, by which it is forced into a vessel of water, this
water being kept in a constant state of agitation. There are two ways in which this
absorption may be worked. Either a large absorption apparatus, similar to a boiler
shell, may be fitted with an agitator, and filled to about three-fourths of its.
capacity with water, and then the gases to be separated are forced in till the
pressure rises to the full working pressure for which the apparatus was designed,
and the impure, or less soluble gases from the surface may then be blown off.
When these have been driven off, the pure carbon dioxide, which is disengaged
from the water by the lowering of the pressure, which liberation may also be
assisted by the formation of a partial vacuum in the absorber, may be sent into a
gas holder, or direct to a compression pump, being dried if preferred, on its way to
the compressor, by passing it over dry carbonate of potash, or other siccative
substance. By attaching the compressor direct, by means of suitably arranged
pipes, to the absorbing vessel, or first to the dryer and thence to the absorbing
vessel the vacuum may be produced by the compressor itself, and no other air pump
will be required. Instead of blowing off the gases as above described the water,
when fully charged with gas, may be drawn off into a separate vessel, the pumping
of gases into the absorber being continued until all the water is driven out.
separate vessel, not being under pressure, but in free communication with the gas
holder, the carbon dioxide is at once liberated, and passes into the holder. The
escape of the gas may be hastened by causing the water to pass through a spraying
jet, as it runs from the absorber, and this jet may be caused to impinge on the side
of the separator.
The
Instead of the above apparatus, however, we prefer to use the one described
below.
A strong cylindrical metallic vessel, suitable for a working pressure of 150 to
200 pounds per square inch, is constructed. One end of this shell is rivetted, but the
other is removeable, and bolted on. The vessel is fitted with water and pressure
gauges, and safety valves, as used for boilers. This vessel is mounted horizontally
on suitable supports, and is fitted with a series of partitious, so constructed, that the
water which is pumped in at one end, passes first through a line of holes, arranged
at about two-thirds the height of the first partition, and thence falling into the next

page_text: compartment, passes under the second partition, and then again through holes i
the third partition, as in the first one, and so on to the end of the series, these
partitions being placed preferably about 6 inches apart. Finally, after passing all
the partitions, the water is driven out through a suitably arranged valve, into the
separating vessel.
Between each of the above described partitions, a revolving disc, preferably made
of wire gauze, and mounted on a central shaft, extending from end to end of the
absorbing vessel, is arranged, the system being driven by any suitable motor, at a
slow rate of speed.
The absorbing vessel is kept about two-thirds full of water, which is continually
pumped in at one end and drawn off at the other. In like manner, the mixed gases,
which are to be separated, are pumped in at the opposite end of the absorber,
and passing throught the upper water openings of one dise, come in contact with
the first revolving disc, and thence pass through openings placed near the top of
the said disc, and so on alternately, the soluble gases being dissolved out of the
mixture of gases, so that by the time the gas reaches the other end of the absorber
nothing but waste gases remain, which are blown away through a suitable valve.
The water which is highly charged with the carbon dioxide, is constantly drawn
off from the absorber, into an expansion or separation vessel, the water being
allowed to rush out of the absorber, through a jet of any suitable form, and thus
either becoming finely sprayed, or driven forcibly against the side or top of the
separator, the gas is rapidly disengaged from the water, and taken either to the
gas holder, or direct to the compressor, if preferred, through an intermediate
drying vessel. A slight vacuum may also be maintained in the separating vessel,
in order to further facilitate the liberation of the gas, though this is not of great
advantage, as the water, from which the gas has been liberated, is at once sent
back, by means of the pump, into the absorber, there being an advantage in using
the water over again, as long as possible.
With this apparatus, the absorbing process is continuous, and not intermittent,
so that for a given amount of work, a much smaller apparatus is required.
Dated this 9th day of April 1895.
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicants.
An Improved Process and Apparatus for the Separation of Carbonic
Acid Gas from the Products of Combustion or other Mixed and
less Soluble Gases.
We, HERBERT SAMUEL ELWORTHY, of 19, Hill Road, Bandra, Bombay, in
the Empire of India, Analytical Chemist, and PHILIP DURHAM HENDERSON, of
32, Fopstone Road, S.W., Gentleman, 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, and accompanying
drawing, that is to say :-
The improved process depends upon the great solubility of carbon dioxide in
water, and the much lower solubility of the other products of combustion.
In working with combustion gases, for the purpose of separating the carbon
dioxide present in them, we first pass them through any suitable form of oxidizing
furnace, for instance a furnace containing some form of metallic oxide, over which
the gases are passed.
By this means the carbon monoxide present is at once converted into dioxide.
When the metallic oxide is exhausted, it, may be regenerated by passing air
over it.

page_text: The gases may then be passed through a small scrubbing apparatus of the usual
well-known kind, to remove sulphur dioxide and thence either to a gas holder,
or direct to a compression pump, by which they are forced into a vessel of
water, this water being kept in a constant state of agitation, so that the soluble
carbonic dioxide is absorbed. There are several ways in which this absorption.
may be effected.
Either a large absorption apparatus, similar in construction to a boiler shell,
may be fitted with an agitator, and filled to about two-thirds of its capacity with
water, and then the gases to be separated are forced in until the pressure rises to
the full working pressure for which the apparatus is designed, the carbon dioxide
being absorbed, and the impure, or less soluble gases on the surface may then be
blown off through a regulating valve.
When these have been driven off, the pure carbon dioxide which is dis-
engaged from the water by the lowering of the pressure, (which liberation may
be assisted by the formation of a partial vacuum in the absorber) may be sent
into a gas holder, or direct to a compression pump, being, if preferred, dried
on its way, by passing it over carbonate of potash, or other suitable siccative
substance.
Instead of blowing off the gases as above described, the water when fully
charged with gas, may be drawn off into a separate vessel, the pumping of gases
into the absorber being continued until all the water is 8 driven out.
The
separate vessel not being under pressure, but in free communication with the
gas-holder, the carbon dioxide is at once liberated, and passes into the holder.
The escape of the gas may be hastened by causing the water to pass through
a spraying jet, as it runs from the absorber, and this jet of spray may be
caused to impinge on the side of the separator, or against a transverse perforated
plate.
Instead of the above apparatus, however, we prefer one of the forms of
apparatus described below, and illustrated in Figures 1, 2, 3, and 4 of the
accompanying drawing.
In Figure 1, which is a longitudinal section through the apparatus, a is a strong
cylindrical metallic vessel, suitable for a working pressure of 100 to 300 pounds
(more or less) per square inch. One end 6 of the shell is rivetted, but the other c
is preferably removable and bolted on as shewn. The vessel is fitted with water
and pressure gauges, and safety valves, as ordinarily used for boilers (but not shewn
in the drawing), and is mounted horizontally on suitable supports, and is fitted with
a series of transverse partitions, d, d¹, d², so constructed that the water that is
pumped in at one end at e, (taking the course indicated by feathered arrows)
passes first through a slot f, or a line of holes, arranged at about two-thirds of
the height of the first partition d, shewn separately in Figure 2, and thence
falling into the next compartment, passes under the second partition d', shewn
separately in Figure 3, and then again through slots for holes in the third
partition d, as in the first one, and so on to the end of the series, these partitions
being placed preferably about six inches apart. Finally after passing all the
partitions the water is driven out through a suitably arranged pipe g and valve,
into the separating vessel.
Between each of the above described partitions, is arranged a revolving disc d'
(shewn separately in Figure 4) preferably made of wire gauze, and mounted on a
central shaft, extending from end to end of the absorbing vessel a, the shaft
being driven by any suitable motor, at a moderate rate of speed.
The absorbing vessel a is kept about two-thirds full of water, which is continually
pumped in at one end at e and drawn off at the other end at g.
In like manner the mixed gases that are to be separated, (taking the course
indicated by plain arrows) are pumped in at the opposite end of the absorber at k,
and passing through the upper water openings fof one disc d, come in contact
with the first revolving disc d', and thence pass over the top of the second
partition d', where they come in contact with the second revolving disc d, and so

page_text: on alternately, the soluble gases being dissolved out of the mixture of gases, so
that by the time the other end of the absorber is reached nothing but waste gases
remain, which are either blown away through a suitable pipe and valve, or
utilized in the manner hereinafter to be described.
The water, which is highly charged with the carbon dioxide, is constantly drawn
off from the absorber, into an expansion or separation vessel shewn in section in
Figure 5, in which m is a cylindrical vertical chamber closed above and below,
and provided with a safety valve, or pressure regulating valve at n. A transverse
perforated plate is shewn at o, and another near the bottom at p, the space
between them being filled with large pieces of flint or coke. The water is
allowed to rush out of the absorber, through a jet of any suitable form, and
thus either becoming finely sprayed, or driven forcibly against the side or top
of the separator, or the perforated plate o, the gas is rapidly disengaged from
the water, and taken either to the gas holder, through an outlet pipe & or direct
to the compressor, and if preferred it may be passed through an intermediate
drying vessel. A slight vacuum may also be maintained in the separating vessel,
in order to further facilitate the liberation of the gas, though this is not of
great importance, as the water, from which the gas has been liberated, passes out
through the outlet pipe t, and is at once sent back, by means of the pump, into the
absorber a (Figure 1), there being an advantage in using the water over again, as
long as possible.
Instead of passing the charged water direct to the separator, as above described,
it may be first passed through a suitable motor, and thus whilst returning a certain
amount of the energy used in its compression, and being made to do useful work,
the gas is at the same time most effectually disengaged from the water, and both
are then sent into the separating vessel.
The forms of absorbing apparatus described may be varied more or less.
For instance, the absorbing vessel a may be packed with any of the ordinary
materials, used for gas scrubbers such as coke, flints, or plates, or slabs, or any
other suitable material, or materials. The vessel (which is preferably arranged
vertically instead of horizontally) has a false bottom, a short distance from the
true bottom, and against this the materials are supported, nearly filling the
vessel. The inlet pipe for the mixed gases, and the outlet pipe for the water
are placed on the outer side of the false hottom, and a baffle plate is placed between
the two pipes, so as to prevent the mixed gases from being sucked into the water
pipe.
The upper end of the vessel is closed with a cover having a manhole for charging,
and cleaning it, and the cover is also fitted with an inlet pipe for the water, and an
escape valve for the waste gases. Near the other end of the vessel, above the false
bottom, another manbole is placed, for the purpose of facilitating the removal of
the contents, whenever necessary.
Water is pumped in at the top, and the mixed gases at the bottom, and as the
water passes through the materials, contained in the vessel, it becomes more and
more highly charged with the gases which are flowing in the opposite direction.
Finally when it reaches the other end, it is saturated, or nearly so, with carbonic
acid gas, and is then drawn off into the separator, or into the motor above
described. The gases, on the other hand, passing in the other direction through
the materials, part with their soluble constituents, and arrive at the upper end
freed from the carbon dioxide. They are then either blown off into the air, or
treated as bereinafter to be described.
In this modified form the revolving shaft and discs are omitted.
Two or more of these absorbing vessels may be used, either working as a
battery, in series, or as found best for the particular purpose for which the gas is
required. The nearly pure carbonic acid gas from the first absorbing vessel, may
he sent into a second one, after passing through the separator, so as to obtain a gas
of very high purity.
As ordinary combustion gases only contain from 14 per cent. to 18 per cent. of

page_text: their volume of carbonic acid gas, in some cases we prefer to enrich them by passing
a certain quantity of pure carbon dioxide through the furnace along with the air,
and by the incomplete combustion thus produced, obtain a gas very rich in carbonic
oxide, which after passing through the oxidizing furnace above described, contains.
from 30 per cent. to 35 per cent. of carbonic acid gas, and in this way saving a large
amount of work in pumping inert gases.
In order to economise the power required for compressing the gas, the waste.
gases escaping from the absorbing vessels may be sent into a suitable motor
cylinder, and the power thus obtained may be utilized for any required purpose.
It can, of course, be used to compress another portion of the mixed gases, or to.
compress the purified gas, or for pumping the water into the absorbing apparatus,
or working the agitator, or other similar work.
The waste gases after doing work in the motor cylinder, are at a very low
temperature, due to their expansion, and the work that they have done, and they
may now be utilized for various cooling purposes. If required they may be sent
into any of the ordinary forins of refrigerating apparatus, to form ice, or to cool
water. They may also be used to cool the absorption water, or the combustion
gases, before these latter are sent into the absorption apparatus. The absorption
water may be cooled either in the absorption apparatus itself, a suitable arrangement
of pipes for this purpose being placed in the absorber, or preferably before going
into the absorber.
Where the process is used in alkali, or other chemical works, the gases may
be used for cooling solutions of crystallizable salts, so as to facilitate their
crystallization. In alkali works, they may also be utilized for cooling the chloride.
of lime chambers, so as to facilitate the absorption of chlorine by the lime.
The waste gases may be dried in any suitable manner, before sending into the
motor cylinder, so as to avoid as far as possible the formation of snow.
We do not claim the separation of carbonic acid gas from the products of
combustion, by making use of its greater solubility in water, but
Having now particularly described and ascertained the nature of our said inven-.
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. In the method of separating carbonic-dioxide from other products of com-
bustion, by means of its greater solubility, the improved process, consisting in first
passing the products of combustion through an oxidizing furnace, and thence to a
compression pump, by which they are forced under pressure into a vessel of water,
means being provided to effect the intimate contact of the gas with the water, the
carbon dioxide being thereby absorbed and the impure or less soluble gases being
blown off from the vessel, and the carbon dioxide being liberated from the water by
lowering the pressure and sent to a gas holder or to a compression pump by which
it is compressed for use, substantially as described.
2. In combination with the process described and claimed in Claim 1, the
method of enriching the combustion gases by passing carbon dioxide together
with the air through the furnace in which they are produced, and by the incomplete
combustion thus produced, obtaining gases very rich in carbonic oxide, which are
passed through an oxidizing furnace so as to convert the carbonic oxide to carbon
dioxide, substantially as described.
3. In combination with the processes described in Claims 1 and 2, the absorbing
apparatus, consisting of a sufficiently strong vessel, containing an agitator and
partly filled with water, into which the gases to be separated are forced under
sufficient pressure, the carbon dioxide being absorbed by the water, and the impure
or less soluble gases being blown off through a valve, the carbon dioxide being then
liberated from the water by reducing the pressure, substantially as described.
4. The modified absorbing apparatus, consisting of a strong cylindrical horizontal
vessel provided with pressure and water gauges, a central revolving shaft carrying
discs, transverse partitions having holes or slots near their upper edge, and other

page_text: transverse partitions having passages at their upper and lower edges, an inlet
opening at one end through which water is pumped in and an outlet opening at
the other end through which the water is drawn off, an inlet opening at one end
through which the gases are pumped in and an outlet opening at the other end
through which the waste or insoluble gases are forced out, all substantially as
described and illustrated.
5. The modification of the absorbing apparatus claimed in Claim 4, in which
modification the revolving shaft and transverse discs are omitted, and the vessel is
filled with fragments of material through which the water and gas are forced in
opposite directions, substantially as described.
6. In combination with absorbing apparatus of the kinds described, the separating
vessel into which the water charged with carbon dioxide is forced, and the pressure
removed so that the gas escapes from the water and passes to a gas holder or to a
pump, whilst the water is discharged, and can be reused, all substantially as
described and illustrated.
7. In combination with the absorbing apparatus described, and the separating
vessel described in Claim 6 the use of a motive power engine arranged between the
absorber and the separator, and made to do useful work by the expansion of the gas,
substantially as and for the purpose described.
Dated this 7th day of October 1895.
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicants.