Improvements in Kilns or Furnaces for Burning Cement and similar Materials.
Year: 1893

page_text: Date of Application, 11th Nov., 1893-Accepted, 16th Dec., 1893
COMPLETE SPECIFICATION.
Improvements in Kilns or Furnaces for Burning Cement and similar
Materials.
I, CARL BRENTANO, of Münchenstein, near Basle, Switzerland, Director_of_the
Münchenstein Portland Cement Works, Brentano and Company, 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 kilns or furnaces for burning the materials from which
Portland and other cement and the like are manufactured, the object of the inven-
tion being to burn such materials as quickly and equably as possible and in a
continuous manner. The said furnace or kiln is especially intended to effect the
burning of the raw material in masses of a globular shape of, say, from 50 m/m
to 60 in diameter, the object of this globular form being to cause the material
to be burnt to pass automatically into and through the furnace, and to ensure its
being burnt in as short a time, as equably, and with as small an expenditure of fuel
as possible.
The new furnace or kiln comprises a single shaft and flue around which latter
are arranged store chambers into which the material to be burnt is placed in the
form of balls and from which it rolls through suitable channels or passages into
open sided tubes arranged in the flue, whereby the said material will be heated
prior to entering the furnace proper. These open sided tubes are arranged in such
a manner that they will only slightly interfere with the draught of the furnace.
In the accompanying drawing,
Figures 1 and 2 are vertical sections at right angles to each other of my new
furnace or kiln ; and,
Figure 3 is a transverse section on the line a-x of Figures 1 and 2:
Figure 4 is a horizontal section of half the combustion chamber on the
lines y-y; and,
Figure 5 is a horizontal section of half the fusion chamber on the lines -.
The furnace or kiln proper is somewhat in the form of a cupola and the flue or
shaft which is placed upon it has advantageously a height of from 15 to 20 m. in
order to obtain a sufficient draught. This cupola has within it the chamber A in
which the preliminary heating takes place, the combustion chamber B, the fusion
or calcination chamber C and the cooling chamber D. E is the store chamber or
hopper which is placed to one side of the chamber for the preliminary heating and
serves for the reception of the material to be burnt.
The raw material in globular masses is carried by means of hopper-waggons a to
the store hopper E (only one of which is shewn in Figure 2) from whence it can
roll automatically through closed tubes c, c into the chamber A. for the preliminary
heating or rather into the tubes b, b arranged in the latter. These tubes of which
nine are shewn in the drawing are open at the top and bottom, of any desired cross
section, preferably round, and of a length corresponding to the diameter of the
furnace (about 3 or 4 metres). The object of these tubes b, b is to retain the balls
of raw material to be subjected to the preliminary heating in the most intimate
contact possible with the gases which are passing off from the fusion chamber of
the furnace without interfering with the draught of the latter, as is the case when
the part of the kiln in which the said tubes are located is completely filled with the
raw material. By the present method of construction so much free space is left
round the tubes b, 6 that a very sharp draught is caused through the preliminary
heating space A. The tubes b, b which form the preliminary heater are as herein-
before stated formed with open sides in order to allow of the passage of the gases
of combustion, and to permit the latter to give up their heat to the masses of raw

page_text: material. In practice the tubes are advantageously made of wrought iron bars
held together by hoops, the intervals between the said bars being so adjusted that
the globular masses of raw material cannot fall through. This construction of the
preliminary heater thus allows of the production of the sharp draught necessary
for the most perfect possible combustion of the fuel and the highest possible yield
of the furnace.
From the tubes b, b the heated balls of raw material roll onto the inclined
planes fo, foff of the arch of the furnace k and through the arches i, i of the
combustion chamber B onto the inclined planes f¹, f' under the arches i, i whence
they can roll into the furnace proper. By the time the balls reach the planes f¹, fl
they are heated to a red hot condition by the gases of combustion arising from the
chamber C. As the balls pass into the chamber C they are strewn over with fuel
at g, g, the fuel being inserted by means of shovels through the doors h, placed
opposite each other under the arch k. In proportion as the mass, perfectly calcined
and cooled in the chamber D, is pulled out from above the grate o, the whole con-
tents of the furnace sink whereby the empty space caused at g, g is again filled
with red hot balls of raw material which slide automatically from the inclined
planes, and, as described above, receive an addition of fuel at g, g and so on.
As a consequence of this an automatic downward movement of the raw material
takes place in the preliminary heating chamber A, the tubes b, b connected with it,
and in the combustion chamber B so that the said spaces are kept constantly filled
with raw material. The charging of the furnace is thus effected automatically,
provided the store hopper E is properly supplied.
The four openings 1, 1 in the combustion chamber serve for the observation of
the process, and the openings m, m in the fusion or calcination chamber C serve
the
purpose of allowing the heated masses of cement to be knocked off the walls
of the chamber when they adhere to it. In order that the knocking off in question
may be easily effected, the body of the furnace if so built up as to consist in cross
section of four flat segments (see section Figure 5) and the openings m, m are so
situated that the whole wall of the furnace may be accessible through them.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. A shaft furnace which is automatically charged for burning continuously
globular masses of the raw material of cement or the like, the said furnace being
characterized by the arrangement in connection with the preliminary heating
chamber of a store hopper or hoppers E, out of which the raw material runs
automatically through closed tubes c into open tubes b, b in the preliminary heating
chamber A wherein the raw material is brought into as intimate contact as possible
with the gases escaping from the fusion or calcination chamber without any great
interference with the draught so that as perfect a combustion as possible of the fuel
in the said fusion or calcination chamber and as large a furnace yield as possible
are obtained substantially as described.
2. A furnace or kiln, provided with means for automatically charging the same
for effecting the continuous treatment of the raw material of cement, constructed
and arranged substantially as described and shewn in the accompanying drawing.
Dated this 11th day of November 1893.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.