Improvement in or relating to Steam Boiler Furnaces.
Year: 1888

page_text: Date of Application, 13th Apr., 1888
Complete Specification Left, 7th Nov., 1888
Complete Specification Accepted, 14th Dec., 1888
PROVISIONAL SPECIFICATION.
Improvement in or relating to Steam Boiler Furnaces.
I JAMES WILLIAMSON of 16 Shakespeare Terrace, Sunderland in the County
of. Durham, Engineer do hereby declare the nature of this invention to be as
follows:-
My invention relates to the furnaces of marine and other internally fired boilers and
consists in an improved arrangement of combined fire-bridge and air heating chamber,
the objects of my invention being to obtain a more complete combustion of the smoke,
more equalized temperature or expansion of the bottom and top of the furnace tube or
flue and better utilization of the fuel.
My improved fire bridge and air heating chamber consists of a cylinder or drum
made of boiler plate and of smaller diameter than the furnace tube in which it is
placed with its axis in the longitudinal direction of the furnace tube and supported by
suitable bearers at the front and back ends. It is placed behind the grate and that
part of it projecting above the firebar carrier is filled in with a wall of fire brick at the
front, a suitable crossbearer being fitted into the cylinder or drum to carry the brick
wall. The part below the grate bar is left open for the entry of air, and may be fitted
with adjustable doors or their equivalent to regulate the supply of air to the cylinder
or drum, and an inclined plate may be fitted above the opening to prevent ashes falling
into the heating chamber.
The annular space between the heating chamber and the furnace tube is likewise
filled in with fire brick at the front end, leaving only an opening at the top for the
flame and smoke to pass over and an opening at the bottom covered by a plate or lid
for cleaning out the bottom of the furnace flue. The back end of the cylinder or
drum is filled in with a wall of perforated firebricks, and the shell of the cylinder is
perforated with holes and covered with a coating of fire clay in which corresponding
holes are formed. For the support or holding of the fireclay suitably shaped pieces of
iron may be riveted to the cylinder shell.
The smoke and flame from the grate which may be made shorter than is usual with
present arrangements, passes over and round the cylinder or heating chamber, and
brings the firebrick and fireclay to a high temperature.

page_text: The air entering the ashpit passes partly through the grate bars as usual and partly
into the heating chamber, through which it flows slowly and issues in fine jets through
the holes in the shell and end of the heating chamber and at a high temperature, and
being in this way intimately mixed with the smoke produces a complete combustion
of the fuel and corresponding economy.
In order to cause the flame and smoke to pass round and under the heating chamber,
obstructors or deflectors of firebrick may be arranged on the upper part and sides of
the heating chamber at or towards the back end of the heating chamber. The flame
passing under the heating chamber heats the bottom of the furnace tube and thereby
produces a more equal temperature and expansion of the top and bottom of the
furnace tube than is obtained with the ordinary arrangement of fire bridge.
Dated this 12th day of April 1888.

page_text: 1, JAMES WILLIAMSON of 16 Shakespeare Terrace, Sunderland in the County
of Durham 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 :-
:-
My invention relates to the furnaces of marine and other internally fired boilers
and consists in an improved arrangement of a combined fire bridge and airheating
chamber, the objects of my invention being to obtain a more complete combustion of
the smoke, more equalised temperature and expansion of the bottom and top of the
furnace tube or flue and a better utilisation of the fuel.
My improved firebridge and airheating chamber is shown on the two sheets of
drawings appended hereunto.
Fig. 1, sheet I shows a longitudinal section and fig. 2 a cross section of a single
flued boiler of the marine type with the firebridge and airheating chamber applied
thereto.
Fig. 3, sheet II shows a front view, fig. 4 a longitudinal section and fig. 5 a cross
section of the fire bridge and heating chamber on an enlarged scale.
Similar letters of reference denote similar parts on the different figures.
My improved firebridge and air heating chamber consists of a cylinder or drum a
made of boiler plate and of smaller diameter than the furnace tube 6 in which it is
placed with its axis in the longitudinal direction of the furnace tube behind the
grate and supported by suitable supports c c and d at the front and back ends. At
the front end the upper part of the cylinder a is cut away and the lower part supports a
cross plate or bearer e and the firebar carrier. Upon the plate e firebricks e¹ are
placed, as shewn the space between the cylinder and the flue tube being likewise
filled in with fire bricks e²e between the plate e and the supports e c'. The opening
between the supports c c is closed by a removable plate y fitted with a sight hole g₁
covered by glass.
The front end a¹ of the cylinder by preference is sloped at the top as shewn to
meet the brickwork e¹ on the plate e, but the cylinder also may be made without the
sloping part and continued up to the brickwork, the latter being in this case built
higher in the middle to close the front end of the cylinder a, so as to leave only the
annular segment 6' above the same for the passage of the flame.
The part of the cylinder a below the grate bar carrier is left open for the entry of
air, and may be fitted with adjustable doors or their equivalent to regulate the supply
of air to the cylinder or drum.
The back end of the cylinder is closed either by perforated firebricks or by a plate h
as shewn. This plate and the shell of the cylinder a are perforated with rows of holes ii
and coated with a layer of fire clay or its equivalent in which corresponding holes
are formed. For the support of the fireclay trough-shaped pieces of iron m m are
rivetted to the shell and backplate by rivets m'm or bars of H or girder section or

page_text: equivalent means may be used instead. On the drawing the rivets are shewn by
circles and the airholes in black. The air holes may be distributed evenly over the
entire surface of the cylinder a, or they may be more numerous at the front end
than at the back end, at the top than at the bottom, or vice versa, as may be required
to obtain the most perfect combustion in each boiler to which the arrangement is
applied. At the back end the upper part of the space between the shell a and flue
tube b is filled in with firebricks n as shewn on the drawing. A deflector k may be
placed into the annular space above the cylinder a near to the front end as shewn for
the purpose of directing the flame more to the bottom of the flue tube b.
The cylinder a may be concentric with the flue tube b as shown, or be placed
nearer to the top or bottom, and may be made longer than shewn on the drawing so
as to extend into the combustion chamber or firebox o (fig. 1) or it may be made
shorter than shewn on the drawings.
Instead of the plate e and brickwork e¹ being carried by the cylinder a, a fire-
bridge of the usual kind may be built in the flue and the cylinder a placed behind
the same, the firebridge being built with an opening below the grate bar carrier for
the admission of air to the cylinder.
"
The smoke and flame from the grate, which may be made shorter than is usual with
the ordinary arrangement, passes over and round the cylinder or heating chamber a
and brings the firebricks and fireclay to a high temperature. The air entering the
ashpit passes partly through the grate bars and partly underneath them into the
heating chamber, through which it flows slowly and issues in fine jets through
the holes in the shell and back, end of the heating chamber at a high temperature,
and being in this way intimately mixed with the smoke, produces a complete com-
bustion of the fuel and corresponding economy. The brickwork n on the back.end
of the cylinder causes the flame and smoke to pass round and under the heating
chamber and this action may be further assisted by applying the deflector k. The
flame passing under the heating chamber heats the bottom of the furnace tube and
thereby produces a more equal temperature and expansion of the top and bottom
of the furnace tube than is obtained with the ordinary arrangement of fire
bridge.
The arrangement of air heating cylinder and fire bridge may be used with forced
draught as well as with natural draught.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
Firstly. The insertion into the flues of internally fire boilers of cylindrical air
heating chambers with perforated shells and backs forming part of the firebridges
or placed behind the firebridges, substantially as hereinbefore described and for the
purpose set forth.
Secondly. The arrangement or construction of air heating and smoke consuming
apparatus for internally fired boilers substantially as heroinbefore described & illustrated
by the drawings.
Dotad this 4th day of Novambor 1994