IMPROVEMENTS IN FURNACES FOR CHEMICAL PROCESSES
Year: 1879

page_text: LETTERS PATENT to James Mactear, of Glasgow, in the County of Lanark,
North Britain, Chemist, for the Invention of "IMPROVEMENTS IN FURNACES
FOR CHEMICAL PROCESSES."
Sealed the 25th May 1880, and dated the 28th November 1879.
PROVISIONAL SPECIFICATION eft by the said James Mactear at the Office
of the Commissioners of Patents on the 28th November 1879.
JAMES MACTEAR, of Glasgow, in the County of Lanark, North Britain, Chemist.
"IMPROVEMENTS IN FURNACES FOR CHEMICAL PROCESSES."
This Invention has for its object to obtain increased efficiency and economy in
the use of furnaces employed for chemical processes.
The improvements are applied to a furnace having a horizontal circular revolving
bottom made of iron, combined with firebrick or other suitable refractory material..
and formed with a raised rim round the outer edge. This furnace bottom which is
mounted on wheels and made to rotate by means of suitable gearing is covered by
a brickwork roof and is heated by one or more fires, the flames or fire gases being
in one modification admitted at one side into the space between the furnace bottom
and roof, and passing off by two outlets at the opposite side. At the part between
the outlets a set of stirrers are placed, consisting according to one modification of
blades or prongs fixed on the lower ends of vertical shafts driven by gearing at
their upper ends. Instead of rotating stirrers, stationary instruments may in some
cases be employed, such instruments being shaped like ploughs so as to cause the
materials to turn over in passing them. The furnace bottom is formed with a central
compartment consisting of a circular dish having a raised periphery or rim, and
from this central dish to the outer rim of the furnace bottom there extends a flat
or nearly flat firebrick or other suitable surface, which is divided into concentric
compartments by low circular ribs or division walls.
are,
.
The materials to be furnaced or heated are introduced 'into the central compart-
ment or dish by preference continuously and at a regular rate. When the materials
for example, chloride of sodium and sulphuric acid for making sulphate of soda,
the chloride of sodium may be fed in by means of a screw, and the sulphuric acid
be led in by a pipe. A stirrer or scraper projects down into the central dish, and
as the materials accumulate in that dish they overflow or spread over its edge or
'
Price 8d 1

page_text: rim into the next circular compartment of the furnace bottom. In a similar way
the materials overflow from each circular compartment into the next outer one,
finally reaching the outermost compartment from which the finished materials pass
down by one or more shutes, or discharge ducts into a stationary channel placed
beneath the rotating furnace bottom. The discharge ducts communicate with an
inverted chanuel piece attached to the underside of the furnace bottom and the
inner and outer sides of the inverted channel piece dip down into lute grooves in
the stationary channel piece below. Portions of the materials enter the lute grooves
or sand, or other suitable luting materials may be put therein so as to prevent the
entrance of air into the furnace or the egress of gases or vapors from the furnace.
The stationary channel may have one or more hopper-shaped shutes adapted to it
for discharging the sulphate or other materials into trucks or other receptacles.
The furnace bottom may be modified by making the dividing ribs or walls of
spiral or other suitable forms instead of circular.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Mactear in the Great Seal Patent Office on the 25th May
1880.
•
JAMES MACTEAR, of Glasgow, in the County of Lanark, North Britain, Chemist.
"IMPROVEMENTS IN FURNACES FOR CHEMICAL PROCESSES."
My Baid Invention has for its object to obtain increased efficiency and economy
in the use of furnaces employed for chemical processes.
My improvements are applied to a furnace having a borizontal circular revol-
ving bottom or hearth made of iron combined with firebrick or. other suitable
refractory material, and formed with a raised rim round the outer edge. In one
modification the flames or fire gases are admitted at one side into the space between
the furnace bottom or hearth and the roof, and pass off by two outlets at the
opposite side. At the part between the two outlets a set of stirrers are placed,
consisting, according to one modification, of blades or prongs fixed on the lower
ends of vertical shafts driven by gearing at their upper ends. Instead of rotating
stirrers stationary instruments may in some cases be employed, such instruments
being shaped like ploughs so as to cause the materials to turn over in passing
them.
The furnace bottom is formed with a central compartment consisting of a circular
dish, and from this central dish to the outer rim there extends a flat or nearly flat
firebrick or other suitable surface which is divided into concentric compartments
by low circular ribs or division walls.
The materials to be furnaced or heated are introduced into the central compart-
ment or dish, by preference continuously, and at a regular rate. When the materials
are, for example, chloride of sodium and sulphuric acid for making sulphate of soda,

page_text: the chloride of sodium may be fed in by means of a screw, and the sulphuric acid
be led in by a pipe. As the materials accumulate in the central dish they overflow
or spread over its edge or rim into the next circular compartment of the furnace
bottom. In a similar way the materials overflow from each circular compartment
into the next outer one, finally reaching the outermost compartment from which the
finished materials pass down by one or more shutes or discharge ducts into a
stationary channel placed beneath the rotating furnace bottom.
The furnace bottom or hearth may be modified by making the dividing ribs or
walls of spiral or other suitable forms instead of circular.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append three Sheets of explanatory
Drawings to be hereinafter referred to, and representing a furnace for chemical
processes as constructed with my improvements. In these Drawings the same
reference numerals are used to mark the same or like parts wherever they are
repeated.
Figure 1, on Sheet 1, of the accompanying Drawings is a plan of the furnace;
Figure 2, on Sheet 2, is a plan of the revolving furnace bottom or hearth, with
parts beneath indicated by dotted lines; and Figure 3, on Sheet 3, is a vertical
section.
The furnace bottom or hearth 4 which is of a generally flat form and circular in
plan is constructed with an iron framework which is mounted on wheels 5 and is
driven by means of a ring of spurteeth 6 with which there gears a pinion 7 on a
vertical shaft 8. This shaft 8 which serves also to drive the stirrers, as hereinafter
explained, receives its motion through bevil wheels 9 from a horizontal shaft
having on it a pulley 10 for a driving belt. The centre of the hearth 4 is occupied
by a castiron dish 11, which is shown as not lined, but which may in some cases
have a lining of firebrick or other refractory material if found desirable. From the
rim of the central dish 11 to the outermost rim 12 the surface of the hearth is
formed of or covered with firebrick or other suitable refractory material, and
is divided into concentric compartments 13, 14, 15, 16, by low circular walls
17, 18, 19.
The hearth is covered by a brickwork roof 20, the space between them forming
a reverberatory chamber, which is heated by means of a pair of furnaces 21,
communicating with the chamber by a single flue 22. From the inlet flue 22
the flames or fire gases pass over the hearth to the opposite side and leave the
chamber by two outlets 23 a little on each side of a point diametrically opposite
to the inlet flue 22. At the part between the two outlets 23 there is fixed a
framing 24 carrying vertical shafts 25 which have prongs or blades 26 for stirring
the materials on the hearth, these prongs or blades being shaped so as to scrape the
tops and sides of the division walls 17, 18, 19. The shafts 25 are geared together
by spur wheels 27 and are driven by a spur wheel 28 on the shaft 8.
The furnace is delineated with feeding apparatus suitable for supplying chloride
of sodium and sulphuric acid, but this apparatus may be modified if necessary for
other materials. The chloride of sodium is put into a hopper 29 from the bottom
of which it is moved by a screw 30 along a horizontal duct to a vertical pipe 31
above the centre of the furnace. The screw 30 is worked by means of reversed
cones 32 and a belt from the vertical shaft 8, and its relative speed can be altered
by shifting the belt on the cones. The sulphuric acid is supplied by a pipe 33.
The materials enter the central dish 11 and overflow into the concentric com-
partments 13, 14, 15, 16, in succession. The outermost compartment 16 is formed
with a number of descending discharge ducts 34, beneath which there is a stationary
annular channel 35. The discharge ducts 34 communicate with and have attached
to them an annular inverted channel piece 36, which forms a cover to the stationary
channel 35, its sides dipping down into lute grooves 37 formed upon the sides of
the stationary channel 35. Portions of the materials enter the lute grooves 37 or
sand or other suitable luting materials may be put therein so as to prevent the
entrance of air into the furnace, or the egress of gases or vapors therefrom. The

page_text: stationary channel 35 has fixed in connection with it one or more hopper-shaped
discharge boxes 38, fitted with bottom doors or valves, for periodically emptying
the sulphate or other materials into trucks or other receptacles. The outer rim 12
of the revolving hearth is beneath an annular plate 39 which is made up of separate
pieces and is supported on pillars, and which supports, or partly supports, the
roof 20, and this plate 39 is formed with a cylindrical flange which dips down
within a channel piece 40 fixed to the revolving hearth, suitable luting materials
being placed in the channel to prevent ingress or egress of air, or gas, or vapor.
Having thus particularly described my said Invention, and the manner of
performing the same, I have to state that I do not restrict myself to the precise
details herein described or delineated, but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is,-
The construction of furnace for chemical processes in which the materials to be
furnaced are supplied at or near the centre of a disk-like hearth or furnace bed,
which forms the bottom of a reverberatory chamber and rotates about a vertical
axis, and the surface of which is divided by low concentric, or spiral, or other
suitable ribs or walls, the materials overflowing or being moved gradually outwards,
or from each compartment to the next outer one, and from the outermost part into
a stationary channel, all substantially as hereinbefore described.
In witness whereof, I, the said James Mactear, have hereunto set my hand
and seal, this Fifth day of May, in the year of our Lord One thousand eight
1
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES MACTEAR. (L.S.)