The refuse matter and garbage of large cities is in the main composed
of animal and vegetable offal of the kitchens; of the sweepings of
warehouses, manufactories, saloons, groceries, public and private
houses; of straw, sawdust, old bedding, tobacco stems, ashes, old
boots, shoes, tin cans, bottles, rags, and feathers; dead cats, dogs,
and other small animals; of the dust and sweepings of the streets, the
condemned fruit, vegetables, meat, and fish of the markets, all of
which compose a mass of the most obnoxious and unhealthy matter that
can be deposited near human habitations.
The inventor of the furnace shown in the accompanying engravings aims
to produce a change of form and of chemical nature and a great
reduction in bulk of all such refuse and garbage within the limits of
the city where it accumulates, without screening, separating,
preparing, or mixing, without the expense of using other fuel, without
any offensive odors being generated in the operation, and to produce
an entirely unobjectionable residuum or product that may be made
useful.
[Illustration: Fig. 1.--FOOTE'S FURNACE FOR BURNING GARBAGE.]
As a rule organic matter largely preponderates in the refuse, being as
high in some instances as 94 per cent. There is always more than
enough to generate sufficient heat to fuse the earthy or inorganic
portion, which is mainly composed of sand, clay, and the alkalies from
the coal and vegetable ashes, etc.
By producing a high degree of heat in the combustion of the organic
portion of the refuse with a forced blast or forced draught, the
non-combustible elements are fused, and form a vitreous slag, which is
entirely inodorous and unobjectionable, and which may be utilized for
many purposes.
The upper section or cone of the consuming furnace is built of boiler
iron, and lined with fire brick resting upon an iron plate, which is
supported by iron columns.
The hearth is made of fire brick, and is in the form of an inverted
cone, being smaller at the bottom and larger at the top, as shown in
Fig. 2.
The sides of the hearth are perforated near the bottom with arches for
the tuyeres or blast pipes, and also in front for the special blast
pipe and the tapping hole. The top of the furnace is closed with an
iron plate, provided with a circular opening, through which the hopper
enters the top of the furnace.
At the left in the larger engraving is seen an elevator, operated by a
steam engine, for conveying the garbage and refuse to a platform,
whence it is projected into the furnace by an inclined plane or chute.
Gas or smoke conductors convey the gas from the top of the furnace to
the furnace of the boiler and to the heating oven, where it is used in
heating air, which is conveyed through the iron pipes passing through
the heating oven into a wind box, from which it enters the furnace at
several points near the bottom by means of the tuyere pipes.
[Illustration: SECTION OF FURNACE.]
The consumption of the garbage is effected near the bottom of the
furnace, where the air is forced in, and is continued as long as the
blast is applied, and while burning at the base it is continually
sinking down at the top, so that it is necessary to keep filling all
the time. The odoriferous gases and the hot products of such
combustion are forced upward through the superimposed mass, and escape
to the fires of the boiler and heating oven, and, being largely
composed of carbonic oxide and the hydrocarbon gases distilled from
the animal and vegetable offal of the garbage, are thoroughly
consumed; and it is said that by this means not only are all the
offensive odors destroyed, but the heat generated is utilized for
making steam and heating the air used for blast.
The refuse in its descent through the high furnace is exposed to the
drying action of the hot gases of distillation and the hot products of
combustion, its temperature increasing in its descent the nearer it
approaches the tuyeres, and becomes completely desiccated and
combustible when it reaches the blast. The high heat in this way
obtained by the combustion of the organic portion melts all of the
inorganic portion, forming a vitreous slag or glass, which may be
allowed to run continuously, or by closing the tap may be allowed to
accumulate, and can be drawn off at intervals. If there is an adequate
supply of clay and sand in the refuse to combine with the ashes, the
slag will run hot and free. The combination of silex or alumina and an
alkali in proper portions always yields a fusible, easy-running
compound.
The molten slag, as it runs from the furnace, may be discharged into
tanks of cold water, which will pulverize or granulate it, making it
like fine sand, or as it pours over a runner, through which it flows,
if struck with a forcible air or steam blast it will be spun into fine
thread-like wool.
The furnace once lighted and started may be kept running day and night
continuously for days, months, or years, if desired; but if it becomes
necessary to stop at any time, the tuyere pipes may be removed and the
holes all stopped with clay, so as to entirely shut off the supply of
air, and it will then hold in fire for many days, and will be in
readiness to start again at any time the pipes are replaced and the
blast turned on.
This furnace is the invention of Mr. Henry R. Foote, of Stamford,
Conn.
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