Improvements in the Production of and Apparatus for Obtaining Carbonic Acid Gas and Lime.
Year: 1891

page_text: Date of Application, 30th Dec., 1891-Accepted, 30th Dec., 1892
Improvements in the Production of and Apparatus for Obtaining
Carbonic Acid Gas and Lime.
I, HENRY CLAY BULL, of, 31, Poultry, in the City of London, in the County
of Middlesex, Engineer, 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 :-
My present invention has reference to the production of carbonic acid gas and
lime from carbonate of calcium, such as chalk or limestone, and has for its object,
more particularly, the production of these materials or matters in a pure or
suitable state for use in making mineral water, &c., and bleaching powder,
respectively; however, the products of the process, of course, may be used for any
other purpose for which they are suitable.
According to this invention, a carbonate of calcium, such as chalk or limestone,
is placed in upright retorts of iron or other suitable material, and subjected to
heat applied externally to such retorts. The retorts are placed in a suitable
furnace or chamber, such for instance as one of the Siemens regenerative type,
and fired by gaseous fuel. The calcium carbonate being thus subjected to heat,
carbonic acid gas is driven off, leaving lime only in the retorts. The gas driven off
is conducted through suitable pipes to a holder.
In some cases the carbonic acid may be washed and scrubbed before it is
conveyed to the holder, if deemed necessary.
The chalk or limestone employed in this process, may, with advantage, be
broken to pieces about the size of walnuts.
To illustrate and shew how my invention may be practically carried into effect,
I have annexed hereto drawings of an example of apparatus according to this
invention. It is to be stated, however, that the apparatus shewn constitutes
merely one example of means by which the invention may be carried out, and it
(the invention) is therefore not confined to the particular form and construction of
the apparatus given.
In these drawings,
Figure 1 is a longitudinal sectional elevation of the apparatus, whilst
Figure 2 is a cross section of same.
e is the furnace or chamber
Referring now to the figures, a are vertical retorts;
in which said retorts are disposed, e, e², being parts of ordinary gaseous fuel and
air regenerators; i are the conduit pipes by which the carbonic acid is conveyed
from the retorts a; o is a hydraulic main, such as is used in gas works, whereinto
the carbonic acid gas is delivered by the pipes i, and wherein a seal between the
space above the liquid in it, and the retorts a, is made.
Regarding the construction of the retorts a, they are of conical form, being
larger at the bottom than at the top, so that they can be easily discharged. At the
top they are provided with a charging door b, which may be of construction, for
convenience, similar to those used for closing ordinary gas retorts. Through this
door the calcium carbonate is charged into the retort. At the bottom, the retorts
are each fitted with a door hinged or otherwise suitably supported, and adapted
to move out of the way when open, in such a manner as to allow the lime to fall
cleanly out of the retorts when they are open. It will be observed that these
doors c have a false portion c¹, by which the charge of limestone or chalk in the
retorts is kept in such a position therein, that the heat within the furnace e will be
transmitted to the whole body of material at the bottom of the retorts.
Within the centre of each retort is provided a pipe d, perforated along the
entire length or depth of the retort, the upper end of which passes through the

page_text: sides of the top mouth piece b', and of which the pipes i are a continuation. This
perforated pipe d is coned or tapered in the manner shewn, to permit of the more
ready discharge of lime from the retorts.
The chamber or furnace e in which the retorts a are disposed, is supported
above the ground level as shewn, and lines of rails f are laid thereunder. In
connection with these, trucks or waggons such as are provided, by which the
lime discharged from the retorts a, is caught, and conveyed away for use in the
"Weldon" or other processes for making bleaching powder, or for any other
purpose.
In working the apparatus illustrated, the retort a may, with advantage be
charged and discharged successively, effecting thereby a continuous production of
carbonic acid and lime. The calcium carbonate (chalk or limestone), broken to a
size such as specified, is charged into the retorts through the top door b, so much
material being introduced as to nearly fill them. The top door is then closed and
the charge is subjected to the heat of the furnace. Carbonic acid gas is thereby
driven off, passing into the centre perforated tube d; and thence into the
hydraulic main o, and so on to a gas holder.
The material may be charged into the retorts by a tipping or equivalent trolley
of any known suitable kind running on rails on the top of or above the furnace e,
and having a convenient means of letting its contents into the retorts.
The object and effect of the central perforated tube d is, that the gases
expelled near the walls of the retort, will, or are caused to; pass directly inwards
through the material towards and into said tube; and these gases being very hot,
act as conveyors of heat from that portion of the charge next the retort. wall.to
the portions nearer and at the centre, and thereby aid largely in effecting..the
regular and rapid expulsion of the carbonic acid. Since carbonic acid gas is a
very poor conductor of heat, had the gas to rise up to the top of the charge in the
case of the absence of the central tube d, the process of the expulsion of carbónic
acid would be a very long one, relatively.
When all or nearly all the carbonic acid is expelled from the charge of a retort,
the bottom door c is dropped and the contents allowed to fall into the waggon or
truck below, and then carried away. The bottom door is then closed, the top
one opened, and a fresh charge of broken calcium carbonate introduced into the
retort. The top door b is then closed and the process, as above described,
repeated.
The carbonic acid gas produced by this process will be perfectly pure and can be
liquified in cylinders or other containing vessels for transportation.. It will. be
suitable for use in making high class mineral waters, aerated bread, and other
purposes. The lime obtained will also be of a very pure quality, and particularly
suitable for use in making bleaching powder by the "Weldon' process, and other
purposes.
The arrangement of upright vertical retorts affords great facilities for charging
and discharging, the labor and cost of these operations being by it reduced to a
minimum.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, it is to be stated in conclusion as
above specified that the invention is in no way confined to the particular form,
construction, or arrangement of the parts of the apparatus set forth, with
reference to and shewn in the drawings, since such parts may be constructed and
adapted to operate in different ways without departing from the spirit or
controlling features of the invention; but what is claimed in respect of this
invention is :-
1. Effecting the production or obtainment of carbonic acid gas, and lime, from
carbonate of calcium, by heating same in closed vertical retorts, the heat being
applied to said retorts externally, and collecting the carbonic acid gas 'thereby
driven off in said retorts, the residue, lime, being discharged from said retorts

page_text: subsequently to the expulsion or driving off of carbonic acid; substantially as and
for the purposes set forth.
2. In the production or obtainment of carbonic acid gas, and lime, from
carbonate of calcium, the employment of vertical retorts with charging and
discharging doors, and internal pipes by which the gases pass towards the inner
part of the charge, said retorts being disposed or arranged within a heating chamber
or furnace; substantially as set forth.
3. The apparatus for making carbonic acid gas, and lime, having its parts
arranged and constructed particularly as set forth with reference to and shewn in
the drawings.
L
1001
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicant's Patent Agents.