IMPROVEMENTS IN FURNACES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Hugh Martin, Junior, William
Martin and James Martin at the Office of the Commissioners of Patents
on the 1st February 1883.
HUGH MARTIN Junior, WILLIAM MARTIN and JAMES MARTIN all of Coatbridge
Iron Works, Coatbridge in the County of Lanark North Britain "IMPROVEMENTS
IN FURNACES
"
This Invention has reference to special improvements in and connected with
reverberatory furnaces used for the re-heating of iron, steel, and other analogous
or equivalent furnaces; whereby they are made very much more efficient, and
economical in the consumption of fuel, than such furnaces have been as heretofore
constructed.
The improvements consists essentially all as follows:-First, in fitting in and
along the back wall of the furnace, above the fuel grate and the bottom or hearth
of the heating chamber, a narrow deep cast-iron air-flue or duct, preferably made
rectangular in cross section and in two parts longitudinally bolted together, for the
admission and supply of heated air to the rear end of the furnace above the fire
grate as will be hereinafter explained; and at a convenient angle and height that
this iron flue will support the whole length of the back edge or side of the arched
roof. An inner facing of fire-brick is built in front of the metal flue to protect it
from melting by the action of the fire and heat and to form the back wall actually
exposed to the heat and flames; so that, when burnt away this back wall can be
more easily renewed than in the ordinary construction of furnaces without dis-
turbing the arched roof which is supported on the iron air-duct before-mentioned.
The air is admitted at the narrow open neck end of the said metal flue, so as to be
heated in passing through it by the heat of the furnace acting on the back wall,
and admitted by a lateral opening at the other end into a narrow close space of a
few inches across the whole rear end of the grate furnace, formed by a transverse
vertical brick wall built from the furnace bars right up to the arched roof, and
formed with narrow openings between the ends of the bricks, which break bond in
every row, so as to admit the air in a highly heated state through the interstices
of this hot wall into the rear end of the combustion fuel furnaces, and so ignite all
the smoke and gases rising from the coal or fuel being burnt therein, thus giving a
more perfect combustion and a much higher and more regular heat of the flame

page_text: and gases passing over the bridge and deflected down by the roof into the heating
chamber on to or through between the bars or blocks of metal being heated, or
reheated, therein.
A further improvement has reference to the use of steam, and to special means
or fittings for forcing heated air into the closed-in ash pit under the fire-grate of
such furnaces. And consists of a long broad shallow rectangular duct fitted longi-
tudinally in the brickwork below the hearth or bottom of the heating chamber,
and preferably below the front part so as to be highly heated, and thus heat the
air forced through it; and it is preferably strengthened by longitudinal vertical
webs or feathers to prevent the upper side bending in from the intense heat and
the weight of metal on the furnace hearth or floor. The inner discharge end of this
air heating duct opens right into the ash-pit below the inner end of the fire-grate;
while the outer extreme end is closed, but the air is admitted through a vertical or
lateral branch near this end, fitted with a double reverse conoidal vertical or lateral
induction tube, having a small jet of steam injected from a nozzle into its outer
open conoidal or trumpet end so as to draw in and force the air through the middle
contracted part into the wide induction part, and through the horizontal heating
duct into the close ash pit, and up through the grate bars and fire; and thus burn
the coal or fuel in the fire-place above by forced combustion. This arrangement
described, as applied to ordinary re-heating furnaces allows of the free admission
of the air to both of the longitudinal heating metal ducts very conveniently on
each side of the contracted neck or flue, and at that end of the furnace where this
flue conducts the waste gases from the lower part of the heating furnace to the
chimney.
These improvements have been described as applied to ordinary re-heating
furnaces, used for heating short bars or blocks of iron or steel, so as to roll or forge
these into long bars or plates of a smaller or thinner size; but it will be seen that
with very slight modifications they are equally applicable to many other re-heating
furnaces for other purposes such as those used for the heating of bars, and plates
for the making of rivets, spikes, and bolts and nuts, or plates for the making of
'skelps" and tubes, and all such like furnaces, which have their fuel combustion
furnace at the one end or side of a heating furnace, with long broad hot back wall
and hearth, which can be used as described for the heating of the air to be admitted
to the combustion chamber above the fire-grate and that forced into the ash pit
below, for producing forced combustion with heated air.
"