IMPROVEMENTS IN FURNACES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office of
the Commissioners of Patents on the 20th September 1877. A communication
from abroad by Emile Malétra, of Paris, in the Republic of France.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN FURNACES." A communication from abroad by
Emile Malétra, of Paris, in the Republic of France.
This Invention relates to a peculiar arrangement of portable furnace upon wheels,
whereby important advantages are obtained.
In carrying out this Invention, the truck or carriage upon which the furnace is
mounted is formed by three or any other convenient number of cast-iron girders,
connected by two or more I irons and suitable bolts. On the ends of the girders
are secured the supports of journals, upon which four travelling wheels turn, and
the supports of an axle, upon which a fifth or central wheel is fitted. This wheel
does not bear upon the ground at the same time as the four others, which are
arranged two at each end of the carriage, such central wheel being supported at a
short distance from the ground at the centre of the framework of the carriage, so as
to enable the whole of the apparatus to be turned round as on a pivot, whenever it is
desired to change the direction in which the furnace is travelling, by raising the
entire apparatus by means of screw jacks or other suitable appliances and placing
blocks or wedges underneath it, the four wheels at the extremities offering no
impediment to the performance of this operation.
The solid parts of the furnace, constructed of fire-bricks, comprise two or more
fire-places or combustion chambers between the external walls, provided with the
necessary apertures, which fire-places are separated by a low wall supported by the
central one of the cast-iron girders, and are each provided at different elevations
with the necessary fire-bars. These fire-places are covered by an inclined arch
extending from the front to the back of the furnace, properly so called, where the
external wall forming a bridge is provided with a cylindrical passage, through which
the gases resulting from the combustion escape. An iron frame supports the whole
of the brick work or masonry of the furnace, and binds it securely to the frame of
the carriage.

page_text: The Invention is particularly applicable to furnaces having a rotating sole or
hearth, and used in metallurgical operations or for chemical purposes, such, for
example, as what are known as "revolvers," for manufacturing soda.
The portable furnace possesses the following advantages:-
1st. When a furnace is worn out it may be replaced immediately by another,
constructed in readiness, upon a carriage or truck near at hand, and the masonry or
brickwork of which, being already dry, may be brought within a few hours to the
temperature required in order to work the revolver without any appreciable loss of
time.
2nd. When the revolver is in need of repair, the facility for removing the furnace
affords means for readily obtaining access to the cylinder, and enables the workmen
to enter it much sooner than would otherwise be possible by allowing it to cool
more rapidly, and greatly diminishing the inconvenience to the workmen by
obviating the necessity for passing through the ash-pit of the furnace.
3rd. According to the mode of construction hitherto adopted, the outlet of the
furnace is necessarily brought as near as possible to the entrance of the revolver
in order to leave less passage for cold air between the two parts, but the expansion
resulting from the heat has the effect of bringing the parts into closer proximity
and rendering it necessary to cut away the brick work forming the ring on one side
or the other in order to prevent the surfaces from coming into contact. The neces-
sity for this operation, which cannot be effected without shaking and impairing
the solidity of the structure, is entirely obviated by the employment of the portable
furnace which admits of being drawn back as required.
4th. An important advantage of the portable furnace is the facility which it
affords for experiments on the means employed for heating, that is to say, for trying
furnaces constructed on different systems.
5th. As the portable furnace is capable of being removed when required, the
revolver may be taken out and replaced by another previously prepared.