Improvements in the Production of Carbonic Acid.
Year: 1892

page_text: Date of Application, 5th Dec., 1892
Complete Specification Left, 2nd Oct., 1893—Accepted, 4th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Production of Carbonic Acid.
We, SAMUEL WALKER, of Lower Fazeley Street, Birmingham, in the County
of Warwick, Manufacturer and SIDNEY STUART WALKER, of Woodside, Knowle,
in the County of Warwick Mechanical Engineer do hereby declare the nature of
this invention to be as follows:-
Our said invention has for its object the rapid and economical-production of
carbonic acid and consists of the improved process or processes hereinafter described
for obtaining it from the carbonates of the alkaline earths and other carbonates,
the oxides and hydrated oxides of which will combine with the free carbonic acid
contained in furnace gases. We prefer however to use carbonate of lime for the
purpose of carrying our invention into effect.
We take carbonate of lime or mixed carbonates of the alkaline earths or the
other carbonates hereinbefore indicated preferably in a state of fine division which
we introduce into a retort preferably circular in cross section, this retort is
provided with an Archimedian screw by the rotation of which the material in the
retort is made to pass from one end to the other.
Or the retort may be inclined or various other methods may be employed for
causing the material to travel from one end of the retort to the other.
The retort being heated a current of steam or a current of gas inert with respect
to the carbonates is passed through the retort; the carbonate gives up its carbonic
acid and falls out at the distant end of the retort in the form of quicklime, when
carbonate of lime has been used, or hydrated quicklime or a mixture of these.
Or an exhaust or partial vacuum may be formed in the retort with like
effect.
The carbonic acid and excess of steam or other gases is passed through water in
which may be dissolved such chemicals as will absorb any impurity which an
examination of the gas may show to be present. An apparatus similar to the
scrubber which is used in the manufacture of coal gas may be employed for this
purpose. The carbonic acid thus obtained may be conducted to and stored in a
holder from whence it may be pumped and compressed into a liquid form or used
for any purpose to which it is applicable.
The quicklime or hydrated quick-lime or mixture of these may where found
necessary be treated with water or steam to effect its complete hydration and the
hydrated quick-lime is exposed to the gases given off by the combustion of
carbonaceous matter whereby the said hydrated quicklime is converted into
carbonate of lime which may be treated in the way hereinbefore described for the
recovery of carbonic acid therefrom.
Instead of ensuring the complete hydration of the quick-lime after it has passed
from the retort by the employment of steam or water before exposing it to the
furnace gases, the hydration may be effected by mixing steam with the furnace
gases to which the quick-lime is exposed.
According to a modification of our invention we heat the carbonate of lime with
carbon and so produce carbonic oxide; this on being passed through heated
metallic oxides is converted into carbonic acid the metallic oxide employed being
reduced to a lower degree of oxidation or reduced to the metallic state.
Dated this 5th day of December 1892.
W. T. WHITEMAN,
Agent for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in the Production of Carbonic Acid.
We, SAMUEL WALKER, of Lower Fazeley Street, Birmingham, in the County
of Warwick, Manufacturer, and SIDNEY STUART WALKER, of Woodside, Knowle,
in the County of Warwick, Mechanical Engineer, do hereby declare the nature of
our invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
Our invention has for its object the rapid and economical production of carbonic
acid and consists of the improved process or processes hereinafter described for
obtaining it from the carbonates of the alkaline earths and other carbonates,
preferably those the oxides and hydrated oxides of which will absorb the free
carbonic acid contained in furnace gases. We prefer however to use for the
purpose of carrying our invention into effect carbonate of lime, such as, marble,
limestone or natural or artificial chalk.
We take carbonate of lime or mixed carbonates of the alkaline earths or the
other carbonates hereinbefore indicated and introduce it or them into a retort
which may either be vertical or horizontal, but we prefer to use a vertical retort.
When a horizontal retort is employed it may be furnished with an Archimedian
screw by the rotation of which the material in the retort is made slowly to pass
from one end to the other. Or the retort may be inclined or other methods
may be employed for causing the material to travel from one end of the retort
to the other.
The retort being set in a furnace and heated, a current of steam or a current of
gas inert with respect to the carbonates is passed through the retort; the carbonate
gives up its carbonic acid and the caustic lime when carbonate of lime has been
used falls out of or may be removed from the retort.
The current of gas we prefer to use in place of a current of steam to wash
out from the heated retort the carbonic acid liberated from the chalk is
'carbonic oxide.
The carbonic acid and steam or other gases are passed through water in which
may be dissolved such chemicals as will absorb any impurity which an examination
of the gas may show to be present. Apparatus similar to the scrubber which is
used in the manufacture of coal gas may be employed for this purpose. Or an
apparatus similar to a gas purifier may be employed in conjunction with solid
absorbents. The carbonic acid thus obtained may be conducted to and stored in a
gas holder from whence it may be pumped and compressed into a liquid form or
used for any purpose to which it is applicable.
The quicklime is treated with water to effect its hydration and the hydrated
quicklime is exposed to the gases given off by the combustion of carbonaceous
matter whereby the said hydrated quicklime is converted into carbonate of lime
which may be treated in the way hereinbefore described for the recovery of
carbonic acid therefrom.
According to a modification of our invention we heat the carbonate of lime with
carbon and so produce carbonic oxide; this on being passed through heated
metallic oxides is converted into carbonic acid the metallic oxide employed being
reduced to a lower degree of oxidation or reduced to the metallic state.
When we heat a mixture of carbonate of lime and carbon we prefer to use either
wood charcoal or coke mixed with the carbonate of lime.
In converting the carbonic oxide into carbonic acid by passing it over or through
heated metallic oxides we prefer to use for that purpose peroxide of iron either
native, that is, haematite or artificial peroxide of iron or oxide of copper. In the
former case the haematite may be in the form of coarse powder; in the latter cases
peroxide of iron or oxide of copper in the form of scales as it is known in

page_text: commerce may be employed. The reduced metals may, as is well known, be readily
reoxidised and used over again.
Having now particularly described and ascertained the nature of our invention
and in what manner the same is to be performed we declare that we claim as our
invention of, "Improvements in the production of carbonic acid."
First. Heating carbonate of lime or other earthy carbonate or carbonates which
by heat give off the whole or part of their carbonic acid and the oxides of which
when cooled will readily absorb carbonic acid or mixtures of these carbonates, in a
retort in conjunction with a current of steam or other gas or vapour which
can be condensed at ordinary temperatures or tenperatures slightly lower than
ordinary temperatures or which can be removed by absorption or oxidation,
whereby a current of approximately pure carbonic acid may be obtained
substantially as herein before described.
Secondly. Heating a mixture of carbonate of lime or the other carbonates herein-
before referred to with carbon so as to obtain a current of carbonic oxide, passing
the current of carbonic oxide so obtained over or through heated metallic oxide
preferably peroxide of iron or oxide of copper thereby oxidising the said carbonic
oxide and producing carbonic acid substantially as herein before described.
Thirdly. The series or cycle of processes herein before described whereby
carbonate of lime or the other carbonates employed may be used over and over
again for the production of carbonic acid.
Dated the Thirtieth day of September 1893.
SAMUEL WALKER.
SIDNEY STUART WALKER.