IMPROVEMENTS IN THE APPLICATION OF FORCED DRAUGHT TO FURNACES
Year: 1885

page_text: We, JAMES PATTERSON, Engineer of 19 Hawthorn Street, in the City and
County of Newcastle upon Tyne, and MAGNUS SANDISON, Engineer of 34 Park
Road in the City and County of Newcastle upon Tyne do hereby declare the
nature of our said invention for IMPROVEMENTS IN THE APPLICATION OF FORCED
DRAUGHT TO FURNACES to be as follows:-
Our invention relates to certain improvements in the application of forced
draught to the furnaces of internally fired boilers, giving an efficient distribution
of the air through the fuel and affording great facility for firing and working the
fires, while the fireman is at no time exposed to air at a pressure greater than that
of the atmosphere; and is carried out as follows:
The mouth of the furnace is closed by a casing, or door-frame of cast or wrought
iron, or other suitable material, made practically air tight, thus shutting off the
furnace from the atmosphere. The supply of compressed air for the furnace is
admitted to the ashpit, not through the mouth of the furnace, but by a tube or
tubes quite separate and distinct therefrom thus making a simple arrangement of
doors for access to the fire and ashpit possible.
When the furnace is not the full length of the boiler, as in the single ended
return-tube marine boiler, or in the type of boiler known as the "admiralty type,"
the air is admitted through the water space of the boiler by a tube or tubes
from the shell to the furnace or flame-box bottom; or from the back of the boiler
to the flame-box back, and thence to the ashpit. A door or valve is provided to
regulate the supply of air to the fire, and may be placed in the lower part of
the bridge-plate.
In the double ended marine boiler, the arrangement is similar to the above, the
air being admitted to the under side of the furnace or flame box, by a tube or tubes
through the water space, from the shell to the furnace or flame box bottom. In
the type of boiler in which the furnace flue extends the full length of the boiler,
and fired at one end only, the air tube or tubes may be fitted through the water
space between the shell and the lower part of the furnace, or through the flue from
the back of the boiler to the bridge.

page_text: The casing closing the mouth of the furnace is provided with a door firing and a
door for drawing the ashes; these doors may be arranged, so that, when either is
opened the door or valve for regulating the supply of compressed air is closed,
or may be quite independent, a separate means being provided for working the
regulating door or valve, thus preventing the possibility of the issue of smoke or
flame at the mouth of the furnace.
A passage is provided in the casing or deadplate to admit a supply of air from
the ashpit to the top of the fire, this supply may be regulated by a valve or small
door.

page_text: Improvements in the Application of Forced Draught to
Furnaces.
We; JAMES PATTERSON, Engineer of 19 Hawthorn Street in the City and
County of Newcastle upon Tyne, and MAGNUS SANDISON, Engineer of 34 Park
Road in the City and County of Newcastle upon Tyne do hereby declare the
nature of our said invention for IMPROVEMENTS IN THE APPLICATION OF FORCED
DRAUGHT TO FURNACES and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :—
Our invention relates to certain improvements in the application of forced
draught to the furnaces of internally fired boilers, giving an efficient distribution
of the air through the fuel and affording great facility for firing and working the
fires, while the fireman is at no time exposed to air at a pressure greater than that
of the atmosphere, and is carried out as follows.
The mouth of the furnace is closed by a casing or door-frame of cast or wrought
iron or other suitable material made practically air tight thus shutting off the
furnace from the atmosphere. The supply of compressed air for the furnace is
admitted to the ashpit, not through the mouth of the furnace, but by a tube or
tubes quite separate and distinct therefrom, thus making a simple arrangement of
doors for access to the fire and ashpit possible.
When the furnace is not the full length of the boiler, as in the single-ended
return-tube marine boiler, or in the type of boiler known as the "admiralty" type,
the air is admitted through the water space of the boiler by a tube or tubes
from the shell to the furnace or flame-box bottom, or from the back of the boiler
to the flame-box back, and thence to the ashpit. A door or valve is provided to
regulate the supply of air to the fire and may be placed in the lower part of the
bridge-plate.
The casing closing the mouth of the furnace is provided with a door for firing
and a door for drawing the ashes; these doors may be arranged so that when
either is opened the door or valve for regulating the supply of compressed air is
closed, or may be quite independent, a separate means being provided for working
the regulating door or valve, thus preventing the possibility of the issue of smoke
or flame at the mouth of the furnace.
A passage is provided in the casing or dead-plate to admit a supply of air from
the ashpit to the top of the fire, this supply may be regulated by a valve or small
door.
In order to enable our invention to be fully understood we will proceed to
describe the same by reference to the accompanying drawings which represent the
invention as applied to a single-ended return-tube marine boiler; but we do not
restrict ourselves to the precise arrangement of the parts which may be varied to
suit special requirements without affecting the principal on which it operates. The
same letters are used on the different views to denote the same parts.
Fig. 1 represents a longitudinal-section and Fig. 2. a cross-section of a single-
ended return-tube marine boiler. The air-trunk K contains compressed air supplied
.

page_text: by a fan or other suitable mechanism. This compressed air passes by means of the
opening or openings L to the bottom of the flame box and thence to the ashpit or
ashpits. The supply of air to the furnace is regulated by the valve C which may
be worked from the opposite end of the boiler by means of the rod D. The
casing E closing the mouth of the furnace contains the doors F for firing and G for
drawing the ashes. The mechanism for opening the doors F and G may be
arranged in conjunction with that for working the valve C so that when either F
or G is opened, the valve C may be wholly or partially closed. Provision is made
in the deadplate H for admitting a supply of air over the fire, and in the back
bridge J for admitting a supply of air to the gases in the flamebox.
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is
1. In boilers, where forced draught is used, supplying the air to the furnaces
through a tube or tubes through the water space instead of the usual method of
supplying the air through the mouth of the furnace, all substantially as shown and
described.