Improvements in Furnaces for Burning Cement, Lime, and the like, and for Smelting Ores.
Year: 1896

page_text: Date of Application, 30th Nov., 1896-Accepted, 13th Feb., 1897
COMPLETE SPECIFICATION.
Improvements in Furnaces for Burning Cement, Lime, and the like,
and for Smelting Ores.
I, ALBRECHT STEIN, of Wetzlar, in the Empire of Germany, Manufacturer, 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:-
This invention relates to the construction of a furnace which is designed for use for
burning cement, lime and the like, and also for smelting ores, the arrangement being
such that the inner lining of the furnace casing which is generally made of iron or
steel with a fire proof material such as fire clay or ganister &c. can be dispensed with.
A furnace according to this invention is formed internally with naked metal walls in
contra-distinction to the ordinary burning and smelting furnaces heretofore employed,
all of which require a solid lining or coating of fire-proof material inside the furnace
shaft. These walls would be liable to be destroyed by the burning or smelting
temperature obtaining in the furnace, if measures were not taken to provide
for efficient cooling of the furnace walls on the exterior of the furnace, and it is the
object of my invention while dispensing with the internal fire proof lining to effect
the cooling of the furnace walls.
.
The invention consists in providing the outside surface of the furnace with approxi-
mately vertical air passages or channels which may be of either open gutter shape, or
be closed externally, and designed to produce a strong circulation of air, and
consequently an effective cooling of the furnace casing.
In the accompanying drawings,
Figure 1 is an external elevation of a furnace with framing constructed according
to this invention.
Figure 2 is a cross section through the furnace, and
Figure 3 is a cross section of a modified form of the same.
The absence of any lining whatever on the internal surface of the furnace casing,
has, amongst others, the particular advantage of avoiding the frequent interruptions
of working which are caused by the occasional renewal and the necessary taking down
of the lining for the purpose of repair. As shown in the cross section in Figure 2
(and Figure 3) in the new mode of construction of burning or smelting furnace,
there is no lining whatever, so that the furnace wall A which is preferably made of
iron or steel, is enabled to come in direct contact internally with the charge or contents
of the furnace. Since the wall of the furnace has to withstand a teinperature acting
in its interior, such temperature being generally very high, the wall is formed on its
outer periphery in such a manner as to present a maximum amount of cooling surface.
This object is most advantageously effected by arranging on the outside of the wall a
suitable number of air passages or channels a, a, Figure 2. Through these passages
the natural current of air enters at the coolest point of the furnace, and in rising and
by assuming a higher temperature, produces a powerful draught in an upward
direction, and thus serves to effectively cool the wall of the furnace. This cooling
action is so great, that for example temperatures may be produced in the interior of
an iron furnace shaft constructed in this manner, which are far beyond the melting
point of iron, without however, the walls of the furnace being injuriously affected
thereby.
It is not necessary that the passages, such as those marked a in Figure 2, should

page_text: be arranged in uninterrupted series or succession around the furnace. Their
succession may also be interrupted as shewn in the cross section according to Figure 3.
In this case the enclosed air passages a' alternate with the gutter shaped passages a²,
which, on account of, the radiation of their surfaces also serve to cool the furnace
casing although not to such a degree as do the draught passages a¹. In fact instead
of completely closed in passages, mere gutters between ribs of suitable cross sectional
form may be employed. The dimensions and cross sectional shape of the air passages
thus formed, are not material to the invention, which in fact can be carried out in
most varied forms, so long as the object of cooling the furnace walls by means of
natural draught with the help of the peculiar construction of the exterior of the walls
is borne in mind.
. It is preferable to construct the furnace of superposed rings or tubular parts which
may if necessary be divided, and which are connected together in a suitable manner.
The most suitable material for these rings, or segments fitting together to form rings,
are iron or steel castings, but other materials may however be employed for this
purpose. The outer enclosing wall A' in Figure 2 outside of the passages a is
preferably made of a separate sheet metal shell or casing slipped on to the furnace.
The framing of the furnace, Figure 1, is formed in such a manner as to allow of
access of air on all sides so as to aid in cooling the walls of the furnace. In Figure 1,
B represents the charging tube; C the charge elevator; and D the staircase for giving
access to the charging platform.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
(1.) A burning or smelting furnace in which for the purpose of dispensing with a
lining of the shaft with fire-proof material, the furnace shell or casing (which is
preferably constructed of iron or steel castings and is formed of rings or segments of
rings) is provided on its exterior with closed or open channels passages or gutters, in
such a manner, that by means of the draught or current of air rising up in the same,
or it may be by radiation of the heat, there is produced, an effective cooling action for
the purpose of preserving and prevention from smelting and burning of the walls of
the furnace.
(2.) A burning or smelting furnace substantially as and for the purpose hereinbefore
described.
MARKS & CLERK,
18, Southampton Buildings, London, W,C., and
13, Temple Street, Birmingham, Agents.