IMPROVEMENTS IN STEAM BOILERS
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by Charles Edwin Crighton at the
Office of the Commissioners of Patents, with his Petition, on the
28th April 1871.
I, CHARLES EDWIN CRIGHTON, of the Borough and County of New-
castle-upon-Tyne, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN STEAM BOILERS," to be as follows:-
This Invention has for its object to improve the construction of steam
boilers for land and marine engines, in order to economise the con-
sumption of fuel, generate steam more quickly, and entirely consume
the smoke. Within a boiler of cylindrical or other shape I have three
furnaces. Two of the furnaces (the outside ones in the plan accom-
panying this description) are for the firing of coal, the smoke and heat of
which when ignited pass through to a combustion chamber at the end of
the boiler, which combustion chamber is separated from the main com-
bustion chamber of centre furnace by a thick division of fire-clay or
querls. This division will when thoroughly heated add greatly to the
combustion of the smoke. The smoke and heat then return by a large
tube or flue back through the boiler to the centre furnace. The centre
furnace is of large enough arca to be equal to the two outside furnaces.

page_text: This furnace is intended to be fired with small quantities of coal and
the small cinders which fall through the fire-bars of the two outside
furnaces so as to keep a hot fire without much smoke. The flues of the
two outside furnaces return through the boiler, and are conducted to
the centre .furnace and so arranged as to supply above or below the fire-
bars of the centre furnace the heated gases (and smoke if unconsumed)
from the outside furnaces.
My object is that the centre furnace should be supplied with the
heated air and unconsumed smoke of the two side furnaces only,
thereby creating greater heat with less consumption of fuel, and more
perfect combustion of coal and gases, which by the present system are
now wasted and lost by the too direct and rapid communication with
the funnel.
I also intend by an arrangement of dampers to admit or shut out a
supply of atmospheric air in the door of centre furnace, so as to
regulate at will the draught of all the furnaces, but the great principle
is to close the door of centro furnace entirely from the outward air, and
by so doing necessitate its drawing from the flues connected with the
two side furnaces.
Again, when the door of centre furnace is open for the purpose of
firing or raking out ashes that the two side furnaces shall have direct
communication to the upper tubes and chimney by means of a door which
can be opened in the combustion chamber.
The Sheets of Drawings accompanying this are illustrative of a boiler
suitable for a marine engine of 120 horse-power, and may be more
particularly described by reference to the letters thereon.
A, A, two side furnaces; B, combustion chamber; C, fire-clay division
between side furnaces and centre furnace combustion chambers; D, D,
return flues from combustion chambers of side furnaces to the front of
centre furnace; E, E, connecting flues between return flues of side
furnaces and front of centre furnace with dampers to regulate draught
above or below fire-bars of centre furnace; F, centre furnace equal in
area to the two side furnaces with door to close, so as to prevent the
admission of atmospheric air and compel it to draw heated air, gases,
and smoke generated by the two side furnaces; G, main combustion
chamber of boiler divided by the fire-clay partition C from the two
smaller combustion chambers of the side furnaces. The fire-clay division
marked C is fitted with a damper, which on being opened gives direct

page_text: communication between the side furnaces and the main combustion
chamber, and thus diverts the current of heated air from its ordinary
course through the flues leading to centre furnace, thereby enabling all
three furnaces to be used in the ordinary manner; H, one hundred and
fifty or more ordinary boiler tubes through which the heat of the joint
furnaces, flues, &c. pass in the ordinary manner to the chimney or
funnel; I, smoke box doors and access for tubes; J, steam dome; K,
funnel.