AN IMPROVED FURNACE AND MEANS AND APPARATUS CONNECTED THEREWITH FOR CONSUMING SMOKE AND ECONOMISING HEAT
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by James Cambell Stevenson at the
Office of the Commissioners of Patents, with his Petition, on the
29th October 1873.
I, JAMES CAMBELL STEVENSON, of 26, Lord Street, Liverpool, in the
County of Lancaster, Sanitary Engineer, do hereby declare the nature
of the said Invention for "AN IMPROVED FURNACE AND MEANS AND APPARATUS
CONNECTED THEREWITH FOR CONSUMING SMOKE AND ECONOMISING HEAT," to be as
follows:
This Invention relates,―
Firstly. To preventing the emission of smoke generated in a furnace
by causing it to pass through the fire mixed with fresh oxygen, and
thereby consuming or burning the carbon..
And, Secondly. By a constant circulation, or travelling from and'
returning to the furnace of hot air, to economise or prevent the waste of
the heat generated by the furnace.
"

page_text: As instancing the way in which I carry out my said Invention I may
state that I connect one end of an iron chimney or smoke tube to the
top part of a furnace, and carry such chimney or tube downwards to a
level with the ash-pit beneath the fire-bars. The lower end of the smoke
tube is connected to and opens into a second tube for conveying fresh air
to the fire. A fan is fixed inside the smoke tube to draw the smoke
downwards in the tube, and drive it forward after passing the fan, until
the smoke enters the fresh air tube, and being carried along with the
current of fresh air which the fire attracts, enters the ash-pit, which is
closed by an air-tight door, and so through the fire-bars into the fire,
where the carbon is consumed. The fresh air tube connected with the
ash-pit descends and rises again, forming a syphon, so that the carbon
may not possibly escape by means of the fresh air tube, or if preferred I
place a valve opening inward to the upper part of the smoke tube
through which fresh oxygen may be drawn by the action of the fan, and
mix in its passage downwards with the carbon, and so direct into the
ash-pit and through the fire, this valve having a spring to close it
against the escape of carbon or the admission of too much oxygen. A
similar valve is attached to the mouth of the fresh air tube, so that the
admission of too much fresh air may not prevent the free circulation of
the smoke. The fire-bars may be horizontal, but by preference I fix
them so as to represent three sides of an octagon, by which means I
attain a larger surface for consuming the carbon.
To generate and economise heat I construct two chambers in the
furnace above the fire; the one in front I use for containing air to be
heated, which is driven in by a pump or fan, and passes from thence
through a number of iron tubes or a hollow passage horizontally to the
back chamber, from whence the air heated in its transit through the
tubes or passage passes by a tube to the oven, boiler, or other object to
be heated. After circulating around this object, the hot air is led by a
tube back to the pump or fan to be again driven in and through the
chamber, and tubes or passage to again receive the heat expended in its
circulating course. The tubes or hollow passage being directly over and
subject to the action of the fire conveys heat to the air during its passage
through.
As a further means of economising the heat I enclose the furnace and ·

page_text: leaving a space throughout between the furnace and casing; the air
contained in this space (supplied through suitable apertures in the
casing) becomes heated by the radiation from the furnace, and is drawn
through the valve into the smoke tube to feed the fire or into and
through the syphon tube, as the case may be.