Subjecting Materials to Heat.
Year: 1888

page_text: Subjecting Materials to Heat.
I, CHARLES DENTON ABEL of No. 28 Southampton Buildings, Chancery Lane
in the County of Middlesex, Consulting Engineer and Patent Agent 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 invention relates to an improved construction of furnace for subjecting
granular or pulverulent materials to heat, either for roasting, calcining, drying, or
otherwise treating them, the essential feature of which furnace consists in the
arrangement of a set of horizontal slides of a stepped form having a to-and-fro motion
imparted to them and operating in combination with a series of fixed steps, in such
manner that as the granular or pulverulent material is fed on to the uppermost slide,
portion thereof is caused by the backward motion of the slide to fall upon the step
below it, while on the forward motion of the slide, this pushes the material that has
fallen on to the step on to the next slide below, and so on.
a
By this means the material will be made to pass downwards in thin cascades from
step to step to the bottom of the furnace, while the flame or hot gases are passing in
an upward direction in close contact therewith, the described action of the slides
being to cause the particles of the material to fall over and over each other, and thus
in continually presenting fresh particles to the action of the flame, to subject the whole
body of material in a very uniform manner to the required treatment.
Instead of arranging a set of reciprocating slides in combination with a set of fixed
steps, there may be substituted for the latter a second set of slides having a recipro-
cating motion in the contrary direction to that of the first named set.
The accompanying drawing shows the arrangement of furnace which I prefer to
employ in carrying out my invention.

page_text: Fig. 1 shews a side view of the furnace, Fig. 2 a longitudinal section on line A B
Fig. 3, Fig. 3 shows a plan, Fig. 4 a horizontal section on line CD Fig. 1, Fig. 5 a
cross section on line EF and Fig. 6 an end view.
The furnace consists of a gas producer A for generating the requisite carbonic
oxide gas for combustion in the furnace B, above which is arranged a preliminary
drying floor C.
The floor of the furnace consists firstly of a series of fixed stops d and secondly of
horizontally reciprocating slides balternating with the steps, which latter may however
be replaced by a second set of slides as above stated.
The slides to have a to and fro motion imparted to them simultaneously from a
water-pressure engine or other suitable motor K through connecting rods hand
levers, the motor engine being arranged in any suitable known manner for varying
the extent and speed of the motion imparted to the slides.
The material to be acted upon passes from the drying floor C into the charging
throat a at the bottom of which is situated the first slide so that as this moves
forward into the furnace it conveys the portion of material lying immediately upon it
through the opening between the wall of the throat and the step b, into the
furnace. On the backward motion of the slide, the material lying upon it will be
prevented from moving back with it by the back wall of the throat and consequently
the front portion of the material will be pushed over the edge of the slide and will fall
on to the step below. On the slide again advancing, it pushes the material lying
on the step d down on to the next slide and on this slide moving backward the
same action will take place as described with reference to b, a portion of the material
lying thereon being made to fall over on to the next step d', and so on.
u,
The material is consequently made to travel gradually from the charging throat a
successively from slide to step d, slide step , and so on, until it passes from the
last step, such as on to a plate e which also moves to and fro, and from which it
passes through the hopper finto the receptacle g.
By the forward motion of the slides bbb &c. the material is pushed in thin layers
from the steps d¹ d² &c. on to the following slides, while on the backward motion it is
prevented by the edge of the steps from moving backward, and consequently a portion
falls over the edge on to the next step, so that by this means the material is con-
tinuously turned over and over, so as to present always a fresh extended surface to
the action of the flame.
In order to prevent the material from passing down between the sides of the slides
and the walls of the furnace, the former are made to extend into grooves in the
latter.
The slides &c. consist of cast iron plates covered with fire clay slabs, and
they have on their undersides guide ribs with which they rest on rollers that can roll
upon fixed rails, so as to reduce frictional resistance. The steps d, d', & &c. are made
of fire clay resting upon cast iron bearers.
The gas producer A, which is of any suitable known construction, supplies carbonic
oxide gas through the openings into the furnace chamber, where it mixes with the
previously heated air and enters therewith into combustion so as to produce the
requisite heat for acting in the required manner upon the material to be treated.
The flames first. act with the greatest heat upon the material lying upon the lower-
most steps, whereby this is deprived of the last particles of moisture or gases to be
driven off.
The heating of the air supply is effected in flues n formed over the roof of the
furnace.
The horizontal part of the roof m terminates in a tongue o whereby the flames are
directed downward on to the material on the steps. From the tongue o the roof p
rises in an inclined direction to a second tongue 7 which again directs the flames
downwards on to the material before escaping through the passage into the space
below the drying floor, from which it finally escapes through the chimney s.
In order to prevent the expansion through heat of the tie rods that hold the side
walls of the furnace, these are formed tubular so as to have water circulated through

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them and they are furthermore protected by being enclosed in outer tubes as shewn
more clearly in the cross section at Fig. 7, where it are the tubular tie rods, enclosed
in the outer tubes and connected at their outer ends with circulating pipes u which
either communicate at their upper ends with open water tanks or they are
connected at top by a pipe and worm w¹ as indicated in dotted lines, the worm being
contained in a cooling tank.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is :-
1. A construction of furnace for drying, roasting, burning, or otherwise treating
materials by heat, wherein the bed of the furnace is formed of two sets of steps or
slides that have a to-and-fro motion relative to each other, whereby the material
charged on to the upper steps or slides is made to pass gradually downwards from
step to step, and is at the same time turned over and over so as to bring continually
fresh surfaces in contact with the flames or hot gases, substantially as herein
described.
2. In furnaces such as are referred to in the preceding claim, the combination of a
set of reciprocating horizontal slides such as with a series of fixed steps such as d,
so arranged that the material to be treated is first pushed forward upon the slides on
the backward motion hereof so as to fall in a thin layer on the next step below, and is
then pushed by the slides from the steps so as to fall in a thin layer on to the next.
slide below, whereby a continual change of the extended surface of the material
presented to the flames is effected, substantially as herein described.
3. The use for tying together the walls of the furnace, of tubular tie rods through
which water is made to flow, substantially as herein described.
Dated this Lith day of May 18SS
ABEL & IMRAY,
Agents for the Applicant.