Furnaces in Steam Ships.
Year: 1887

page_text: Furnaces in Steam Ships.
I, JAMES RODGER THOMSON of the firm of James and George Thomson, Engineers
and Shipbuilders, Clydebank, Dumbartonshire, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :--
This invention relates to improved means for promoting forced combustion in
boiler furnaces on board ship the improvements having also for object the cooling and
ventilating of the stoke holds and spaces wherein the boilers and uptakes are placed
and the heating of air supplied under pressure to the furnaces while obviating the
danger attendant on the employment of some of the ordinary forced draught arrange-
ments in which no provision is made for preventing the overflow of flame into the
stoke hold on opening the furnace doors, and the inconvenience and expense occasioned
in other arrangements by the use of regulating valves for closing off the supply of
air under pressure when firing.
Under ny invention the stoke hold is made practically air tight and air is supplied
to and maintained in it in excess of the atmospheric pressure by means of a blower or
blowers. The air so forced into the stoke hold is led through passages or conduits
formed by casings covering the "upiakes" of the several boilers or passing over any
heated parts of the boiler room and enclosing the lower part of the chimney stack or
stacks the passages leading back to the under sides of the fire grates or other points
discharging into the furnaces.
In the accompanying drawings figures 1 and 2 are longitudinal and transverse
vertical sections of the stoke hold A of a vessel to which the invention is shown
applied, the blowers B B being fitted to discharge air into the stoke hold which is
enclosed and is practically air tight, and figure 3 is a detailed section of part of one
of the boiler furnaces.
A casing C is formed around the uptakes at the ends of the several boilers D and is
connected to a casing E formed around the lower end of the stack F while from the
casing E air passages or conduits G having branches g provided with valves are led

page_text: to the several boiler furnaces the ash pits at H being enclosed; and the air from the
stoke hold which enters the casings C at the bottom as indicated by the arrows and
absorbs heat in passing up around the uptakes and by contact with the stack or
chimney in the casing E is discharged under the fire grates or at any other suitable
point in the furnaces. By this means radiation of heat into the stoke hold from the
highly heated parts of the boilers is prevented whilst the air in the stoke hold is
constantly drawn off to the furnaces and replaced by fresh air from the blowers ample
ventilation and cooling of the stoke hold being ensured.
Provision may be made by means of valves or dampers such as g' for partially or
wholly closing off the air supply from any or all of the boiler furnaces, but as the air
pressure within the hold is equal to a greater than that within the furnaces no
provision is required for proventing the outflow of flaine from the furnaces on opening
the furnace doors for firing or cleaning. Dampers I centred on the bridges of the
furnaces and operated by levers i are or may be provided to close the ends of the
furnaces of the boilers (which in the present case are double-ended) and prevent cold
air from the stoke-hold being carried through the furnaces and thus damaging the
boiler tubes when they are being cleaned.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :
-
In conjunction with means for maintaining in the stoke hold of a steam ship a
pressure of air in excess of atmospheric pressure air conduits covering enclosing or
traversing the heated parts of the boilers uptakes and chimney stack and discharging
into the boiler furnaces substantially as and for the purposes set forth.
Datad this Twenty sixth Day of March 1887