IMPROVEMENTS IN STEAM BOILERS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by John Griffiths Hughes at the Office
of the Commissioners of Patents on the 10th September 1878.
"f
JOHN GRIFFITHS HUGHES, Engineer, of Sunderland, in the County of Durham.
IMPROVEMENTS IN STEAM BOILERS."
My Invention relates to improvements in steam boilers having for their object
obtaining an increased amount of real heating surface, economizing the consumption
of fuel by utilizing the gases, and converting them into flame, and securing greater
strength and durability, combined with simplicity of construction and safety in the
use of the boiler.
In carrying out my Invention in order to effect these objects I employ a
horizontal cylinder or shell, which forms the main body of the boiler. Within this
cylinder or shell I arrange two furnace tubes, which are turned upwards at their
extremities from the furnace mouth, and connected to two returning tubes. These
last-mentioned tubes at their extremity converge inwardly, and are connected to
one backward junction tube situate parallel with the two return tubes, and over
the furnace tubes. This junction tube then passes through the back end of the
cylinder or shell, and then through a cistern with an upward turn into the chimney
branch.
I also employ two malleable iron air-conducting cases attached to the front
end of the shell, and working in perpendicular guide rods over the furnace doors.
The air-conducting apparatus consists of a case or shell (open on the under side
to collect the air), which is allowed to drop down over the fire-door after the
furnace has been fired, the door being retained in any desired position by guides
on the case. The air enters the case through small holes in the horizontal plate on
which the case rests. These holes may be varied to any desired extent in their
amount of opening by a regulator plate or other means.
. In operating with my improved steam boiler I proceed in the following
manner:-The furnaces are stoked alternately with this object, that while the
unconsumed smoke is passing from the furnace, and into the return tube it will be
met at the junction of the two returning tubes by heated air and flame from the
other clear furnace fire, and will be consumed while passing through the backward
ID 71

page_text: junction tube. By this process the whole of the carbonic gas is consumed in the
tubes, and not allowed to escape into the chimney.
The air-conducting apparatus is used simultaneously with the firing of the
furnace in the following manner, viz.:-When one furnace has been stoked the case
is drawn down over the furnace mouth, the furnace door being left partially open
until the fire has cleared, when the door is to be closed and the case drawn up
if necessary. This process is continued consecutively with the alternate firing.
The advantage derived is the regulating the supply of oxygen, and directing an
eddying current of air over the fire immediately after stoking, and thereby materially
aiding rapid.combustion.
The cistern surrounding the end of the junction tube at its upward bend into
the chimney branch I employ as a hot well, thereby gaining the double advantage
of increased heating surface by surrounding the tube almost to the base of the
chimney, and of supplying "feed" water to the boiler at boiling point.
The general advantages of my Invention are as follows, viz.:-The economizing
of fuel by the complete combustion of the carbonic gas, the increased amount of
real heating surface obtained by the free combustion space in the large tubes, and
by covering the heated surface to its limit, the sanitary advantage in the heat
passing into the chimney at the back of the boiler instead of over the stoke-hole,
increased strength and durability from the absence of small tubes with greater
simplicity in construction combined with greater safety (the tubes being at liberty
to expand and contract without straining), and the facility the construction affords
for effective cleaning and repairs.