Improvement in Furnaces.
Year: 1893

page_text: COMPLETE STOLERUATION.
Improvement in Furnaces.
We, HENRY PETERSEN, Inventor, residing at No. 70 Perry Avenue, and CARL
KROMPHARDT, Gentleman, of No. 60 North Canal Street, both of the City of
Chicago, in the County of Cook and State of Illinois, U.S.A. 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 is applicable to a variety of heating furnaces, but is intended
especially for use under steam-boilers, and we have therefore shown a furnace
adapted to such use, in the accompanying drawings.
The object of this invention is to effect a thorough combustion of the fuel and to
utilize low grade materials such as hard and soft coal screenings, tan-bark and other
substances.
To attain this object, the furnace is constructed with a view to a minute division
of the air currents, (which we supply under pressure, by a fan or fans or equivalent
device) and avoid the cutting of the fire into sections by dead air spaces on the
grate surface, the structure of the grates and their supports being such as to allow
the air to flow uniformly through the grate.
To burn finely powdered fuel, it is desirable to have the grate openings very
small, not merely to prevent the fuel from sifting through, but to divide the air
currents sufficiently to get at the best results in combustion. This invention is
intended to provide an ample aggregate area of minute openings for the inlet of air
in such a structure as shall, by its freedom from a tendency to warp under the heat
of the furnace, not to be liable to closure or choking or undue enlargement of the
air passages.
In order to enable others skilled in the art to which our invention pertains.
to make and use the same, we will now proceed to describe it, referring to the
accompanying drawings, in which—
Figure 1, is a longitudinal vertical sectional view of a steam boiler furnace
with our invention applied thereto.
Figure 2, is a sectional view of the fire-box or grate and its draught-pipes.
Figure 3, is a vertical cross sectional view, taken on line 3, 3, of Figure 2. And
Figure 4, is a plan view of Figure 2.
A, represents the air pipe leading from the fan A', or other means of supplying
air under pressure to the furnace. Across the back of the furnace is an air pipe B,
which for convenience of attachment of the parts is preferably made rectangular in
cross section as shown. The air pipe A, is broadened at its juncture with the air
pipe B, so that its mouth extends nearly the whole length of said pipe B. This is
done in order to secure a better distribution of the air blast. The upper side of
the pipe B, is provided with a number of openings b, to each of which is attached
an air tube C, extending longitudinally through the furnace. The tubes C, are
likewise provided with a number of openings c, to each of which is attached a
vertical tube D, preferably flared at its top so that the enlarged upper ends of the
tubes are in contact with each other, or nearly so. In the flared tops of said
tubes D, foraminous or perforated plates or gratings B, are set. The said gratings
or plates E, are made slightly smaller than the openings in the top of the flared
tubes D, so that a narrow opening is left between their edges and the sides of the
tube, as may be seen by reference to Figure 4. The openings through the plates D,
are preferably in the form of narrow slots not exceeding an eighth of an inch in
width, as this form of opening is more easily made sufficiently narrow by casting,

page_text: than a circular opening, and, being made wider at the top prevents the grating from
being choked.
While we do not desire to be confined to any precise width of opening in the
grate, we find by experience that a slot as narrow as an eighth of an inch, and in
some cases a sixteenth of an inch gives the best results.
°
To provide for clearing the air tubes and passages from the ashes which sift
through the grate from time to time, we provide an air eduction pipe F, at the front
portion of the furnace to which the air tubes C are connected in a manner similar
to their connection with the air induction pipe B. This pipe F, is extended to
some point outside of the furnace, as shown in Figure 4, and a valve G, of any
construction, which when opened will afford an unobstructed passage through the
pipe F, is attached to its outer end. This valve is usually closed, but is opened
occasionally to allow the air blast to blow through, and carry out any ashes which
may accumulate in the air-pipes.
As a further means for clearing the air tubes and passages of ashes and soot, the 1
openings c, in the tubes C, are provided with hinged doors c', which may be raised
and are usually kept in the positions indicated-by-continuous lines in Figures 2,
and 3, of the drawing, and when it is desired to force the accumulations from the
pipes C, they may be lowered so as to cover the openings c, therein, when the
draught will be forced the entire length of the pipes C, and out through 2
the eduction pipe F. As a still further means of clearing the pipes C, the
same may be provided on their lower surfaces and usually about their middles
with openings c³, which are provided with hinged dcors c³, to open and close
the same.
In order to supply the furnace with coal-screenings, dust or other kinds of fine 2
fuel, to the front of the furnace is secured a hopper or chute H, which is preferably
funnel-shaped in form, and has its lower end opening into the furnace or over the
grate, as at h¹.
Just below the lower end or opening of the chute H, and also in the front part
of the furnace is another air pipe A³, which leads from a fan A³, or other means of a
supplying air under pressure to the furnace, which forces the dust or screenings
from the chute H, and distributes it over the surface of the grate or fire-box.
If desired the furnace may be surrounded by a hollow wall or air chamber I
provided with perforations I' for allowing the forced draught to be delivered on to
the fuel above and below the level of the gratings or plates E. The hollow wall or
chamber I is supplied with air from the pipes C through the openings C₁ as.shown
in Figs. 1 and 2.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
.claim is :
First. In a furnace grate, a series of vertical tubes of polygonal cross section,
set closely together and with their tubular connections, forming air passages, the
upper ends of said tubes being provided with foraminous plates which, together
with the upper edges of said tubes, form the entire grate surface, substantially as
described.
Second. In a furnace grate, a series of flared tubes and tubular supports, together
forming air passages, said flared tubes baving their enlarged ends uppermost, in
combination with foraminous plates, set in the flaring ends of said tubes, and forming.
the grate surface, substantially as described.
Third. In a furnace grate, a series of flared tubes of polygonal section forming
air passages and having their larger ends uppermost and in close contiguity, in
- combination with foraminous plates set in the flared ends of said tubes; and having
air passages between the edges of said plates and the tube ends, substantially as:
described.
Fourth. In a furnace grate, the combination of a series of air tubes traversing
the furnace, having openings on their top surfaces, in which are affixed flared

page_text: vertical tubes, having their larger ends uppermost, and foraminous plates set in
the upper ends of said tubes and forming the grate surface, substantially as
described.
Fifth. In a furnace grate, a series of hollow chambers having foraminous covers
combined with an air-distributing conduit or conduits and air pipes leading from
said conduit or conduits to said hollow chambers, substantially as described.
Sixth. In a furnace grate, the combination of a series of air tubes traversing the
furnace, having openings on their top surfaces, which openings are provided with
hinged doors to open and close them, and in which are affixed vertical tubes having
foraminous plates set in their upper ends, said tubes and plates forming the grate
surface, substantially as described.
Seventh. In a furnace grate, the combination of a series of air tubes traversing
the furnace, having openings on their top surfaces, in which are affixed flared
vertical tubes, having their larger ends uppermost, and foraminous plates set in the
upper ends of said tubes, and forming the grate surface, and a chute or opening to
convey screenings or fuel to the grate and an air pipe to distribute the same
thereover, substantially as described.
Eighth. In a furnace grate, the combination of a series of air tubes traversing
the furnace, having openings on their top and lower surfaces, which openings are
provided with hinged doors to open and close them, and the upper openings having
affixed vertical. tubes having foraminous plates set in their upper ends, said tubes
and plates forming the grate surface, and a chute or opening to convey fuel to the
grate and an air pipe to distribute the same thereover, substantially as described.
Dated this 19th day of April 1893.
W. P. THOMPSON & BOULT,
Agents for the Applicants.