Improvements in Steam Boiler Furnaces.
Year: 1899

page_text: Date of Application, 25th July, 1899-Accepted, 26th Aug., 1899
COMPLETE SPECIFICATION.
Improvements in Steam Boiler Furnaces.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23, Southampton Buildings, in the
County of London, Patent Agent, do hereby declare the nature of this invention
(a communication to me from William De Lancey Walbridge, Gentleman, of
Ocean Avenue, Seabright, New Jersey, in the United States of America) and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
The invention has reference to improvements in steam boiler furnaces and
particularly to down draft furnaces, that is to say;-Those in which the air
necessary for the combustion of the fuel or the maintenance of the fire is con-
ducted to the fuel from above and the products of combustion are carried away
from below.
The object of the present invention is to produce a more thorough combustion
and a higher heat than has been obtainable with the furnaces hitherto proposed.
These results are accomplished by a peculiar distribution or arrangement of the
air supply orifices or tubes relative to the furnace and to the charging openings
thereof.
The invention consists, therefore, in the combination with the supporting
grate for the fuel, of a series of air supply tubes or orifices arranged at the top of
the furnace and contiguous with the front and side walls of the same, and a series
of air tubes or orifices arranged intermediate of the tubes at the side walls and
preferably adjacent to the charging openings.
The invention also embodies other novel features of construction used in con-
nection with those just set forth, as fully pointed out in the following specification
and claims and illustrated in the accompanying drawings, in which:
Fig. 1 represents a front elevation of a boiler and furnace embodying the inven-
tion, part of the same being broken away.
Fig. 2 is a side elevation of the same.
Fig. 3 is a sectional plan.
Fig. 4 is a vertical section on the line 4-4, Fig. 6.
Fig. 5 is a sectional plan with the covers of the air orifices and the coal open-
ings removed.
Fig. 6 is a vertical section on the line 6-6, Fig. 4.
Fig. 7 is a section on the line 7-7, Fig. 4.
Fig. 8 is a vertical section of a modified form.
Similar letters and numerals of reference designate corresponding parts through-
out the several views of the drawings.
Referring to the drawings, the letter A designates the furnace which is built
substantially rectangular in cross section with front and rear walls 1 and 2 and
with side walls 3; said furnace being located substantially in front of the head
of the boiler B. The grate 4 may be of any construction commonly used in
boiler furnaces, but, preferably, a rocking grate provided with mechanism 5 for
actuating the several grate bars is employed. The air necessary for effecting
the combustion of fuel (generally bituminous coal) is introduced into the furnace
from above through tubes 'a, which are so arranged as to effect the distribution

page_text: of the air supply in jets at the most favorable points for reducing a uniform
and complete combustion and to prevent clinkering at the walls of the furnace,
and also to prevent caking in the mass of the fuel. If desired, the rear wall
may be outwardly and downwardly inclined, to insure a proper downward feed
of the fuel while being consumed.
Referring now particularly to Figures 5, 6 and 7 of the drawings, the letters b
designate the charging openings for fuel, which are arranged at the top of the
furnace and in the longitudinal direction of the same, that is, transversely to
the boiler, and are preferably placed equidistant apart. The air tubes a are
arranged contiguous to the front and side walls of the furnace A, and on three
sides of the charging openings. These tubes may open directly to the atmosphere,
but, in practice, it is preferred to conduct the air necessary for combustion
through a suitable flue or flues 6 located exterior to the front wall 1 of the furnace
and communicating at their upper ends with a horizontal chamber or chambers 7
located at the top of the furnace and communicating with all the tubes a. The
air in passing through the flues 6 and the chambers 7 is warmed. The products
of combustion pass from near the bottom of the furnace through a passage or
passages 8 into the usual combustion chamber 9, and, in the present example,
where a return tubular boiler is shown, the gases, after passing through the
boiler tubes, are conducted upwardly to the chimney through the uptake 10 and
suitable flues (not shown). The quantity of air supplied to the tubes a is
regulated by means of suitable gates 11 located at the air inlets 12 of the flues (i.
The fuel is introduced into the furnace through the charging openings b, pre-
viously described, and the chimney draft induces currents of air to pass through
the openings 12, flues' 6 and chambers 7, and from the latter, through the tubes a,
which said tubes form streams or jets of air directed against the fuel contiguous
with the front wall, with the side walls and at points intermediate of all the walls.
The action of each jet is to supply air against a particular point of the fuel, and
in view thereof, the combustion of fuel gradually rises vertically along the paths
of the downward jets of air, with the result that vertical holes or openings are
formed in the fuel along the lines of air supply. The coal adjacent to such open-
ings naturally moves laterally, and, consequently, the body of the fuel is being
continually broken up or agitated, and caking or packing is positively prevented.
The tubes located adjacent to the sides of the charging openings, and which are
designated by the reference letters a', serve to break up the fuel between the end
walls of the furnace. The number of such tubes can be increased or decreased
by increasing or decreasing the number of the charging openings.
d
The charging openings 6 are closed by suitable doors c, which are preferably
hinged, and the portions of the chambers 7 above the tubes a and a¹ are closed
by removable plates d, so that air can be fed directly to the tubes from above
without passing through the flues G. The plates & laterally adjacent to the charg-
ing openings may be provided with side flanges e to form a hopper or guide
for the fuel when it is delivered to said charging openings. Near the lower end
of the furnace and at the front of the same is formed a series of openings f closed
by doors g, which said openings are intended essentially for cleaning out the
furnace. The doors g may be provided with openings closed by adjustable draft
slides h for the purpose of admitting air through the openings f, if desired,
The ash pit door i is so fitted as to close the ash pit substantially against the
ingress of air, but air may be admitted through the ash pit door if circumstances
so require.
j
An air distributor 7, Figures 6 and 7, such for instance as a perforated clay or
iron tube, is preferably arranged at the rear of the furnace, wall 2 and above the
passages 8 through which the products of combustion enter the combustion
chamber, so as to introduce. air in a divided condition into the flame emanating
from said passages. The supply of air to the distributor may be regulated, or
entirely shut off, by a usual form of draft slide or slides located at one or both
ends of the distributor.

page_text: While the improvements are shown embodied in a furnace adapted for return
ubular boilers, it is of course, evident that the same furnace, with slight modifi-
cations, is adapted for use with other forms of boilers, such for instance as water
tube boilers of various types, upright boilers, marine boilers, and the ordinary
fire flue boilers.
It is also evident that the charging openings may be located at the front of the
furnace, instead of at the top of the same.
In place of the grate 4 as a fuel support, a hearth 4* may be used, as shown
in Fig. 8, said hearth being closed against ingress of air into the furnace from
below. The ashes may be raked from the hearth through the doors or openings f.
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:
1. In a down draft boiler furnace, the combination of a support for fuel, a series
of air supply tubes arranged at the top of the furnace and contiguous with the
front and side walls of the same to direct jets of air downwardly through the fuel,
and a series of air tubes arranged intermediate of the tubes at the side walls for
the same purpose, substantially as described.
2. In a down draft boiler furnace, the combination of a support for fuel, a series
of charging openings for the furnace, a series of air tubes arranged adjacent to
the front and side walls of the furnace to direct jets of air downwardly through
the fuel, and a series of air tubes arranged intermediate of the charging openings
for the same purpose, substantially as described.
3. In a down draft boiler furnace, the combination of a support for fuel, a
series of charging openings located at the top of the furnace, a series of air tubes
arranged at the top of the furnace adjacent to the front and side walls of the same
to direct jets of air downwardly through the fuel, and a series of air tubes
arranged adjacent to the charging openings for the same purpose, substantially
as described.
4. In a down draft boiler furnace, the combination of a support for fuel, a
series of charging openings located at the top of the furnace, a series of air tubes
arranged adjacent to the front and side walls of the furnace to direct jets of air
downwardly through the fuel, a series of air tubes arranged intermediate of the
charging openings for the same purpose, air flues and chambers arranged adjacent
to the walls and top of the furnace, and means for regulating the supply of air
to said flues and chambers, substantially as described.
5. In a down draft boiler furnace, the combination of a support for fuel, a
series of air supply tubes arranged at the top of the furnace adjacent to the front
and side walls of the same, and said tubes being adapted to direct jets of air
downwardly through the fuel, a series of air tubes arranged intermediate of the
air tubes at the side walls for the same purpose, an air chamber or chambers
above the lines of tubes with which chambers said tubes communicate, and
removable plates forming part of the enclosure of said air chamber or chambers,
substantially as described.
D 6. In a down draft boiler furnace, the combination of a support for fuel, a
series of charging openings located at the top of the furnace, a series of air tubes
arranged adjacent to the front and side walls of the furnace to direct jets of air
downwardly through the fuel, a series of air tubes arranged intermediate of the
charging openings for the same purpose, an air chamber or chambers with which
0 said tubes communicate, and removable plates forming part of the enclosure of
said chamber or chambers and provided with upwardly extending flanges adjacent
to the charging openings, substantially as described.
7. In a down draft boiler furnace, the combination of a support for fuel, a series
of charging openings for the furnace, a series of air tubes arranged adjacent to
5 the front and side walls of the furnace to direct jets of air downwardly through
the fuel, a series of air tubes arranged intermediate of the charging openings for

page_text: the same purpose, an opening or openings provided with doors and regulators,
and a passage or passages 8 leading through the rear wall of the furnace to the
combustion chamber and located at or near the bottom of the furnace, substan-
tially as described..
8. In a down draft boiler furnace, the combination of a support for fuel, a
series of air supply tubes arranged at the top of the furnace and contiguous with
the front and side walls of the same to direct jets of air downwardly through the
fuel, a series of air tubes arranged intermediate of the tubes at the side walls
for the same purpose, a passage or passages through the rear wall of the furnace
communicating with the combustion chamber and located near the bottom of the
furnace, and an air distributor located back of the furnace wall, substantially
as described.
9. In a down-draft boiler furnace, the combination of a support for fuel, a
series of air supply tubes arranged at the top of the furnace and contiguous with
the front and side walls of the same to direct jets of air downwardly through
the fuel, a series of air tubes arranged intermediate of the tubes at the side walls
for the same purpose, and a plurality of contracted passages 8 located near the
bottom of the furnace and passing through the rear wall of the same to com-
municate with the combustion chamber, substantially as described.
10. In a down draft boiler furnace, the combination of a support for fuel, a
series of air tubes arranged at the top of the furnace contiguous with the front
and side walls of the same to direct jets of air downwardly through the fuel, a
series of air tubes arranged intermediate of the tubes at the side walls for the
same purpose, a rear wall 2 for the furnace having a downwardly and outwardly
inclined inner wall, and a passage or passages through the rear wall of the
furnace communicating with the combustion chamber and located near the
bottom of the furnace, substantially as described.
11. In a down draft boiler furnace, the combination of a hearth closing off
the ingress of air to the furnace from below, a series of air supply tubes arranged
at the top of the furnace and contiguous with the front and side walls of the
same to direct jets of air downwardly through the fuel, and a series of air tubes
arranged intermediate of the tubes at the side walls for the same purpose, sub-
stantially as described.