IMPROVEMENTS IN OR RELATING TO THE COMBUSTION OF FUEL AND IN FURNACES THEREFOR
Year: 1880

page_text: LETTERS PATENT to Bristow Hunt, of Serle Street, Lincoln's Inn, in the County
of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN OR RELATING
TO THE COMBUSTION OF FUEL AND IN FURNACES THEREFOR." A communi-
cation from abroad by Clark Barnum Gregory, of Beverley, County of
Burlington, in the State of New Jersey, United States of America.
PROVISIONAL SPECIFICATION left by the said Bristow Hunt at the Office
of the Commissioners of Patents on the 2nd April 1880.
BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN OR RELATING TO THE COMBUSTION OF FUEL AND
IN FURNACES THEREFOR." (A communication from abroad by Clark Barnum
Gregory, of Beverly, County of Burlington, in the State of New Jersey, United
States of America.)
The object of this Invention is to provide for the complete combustion of the
gases evolved from the burning fuel on or in the grate of a fire place or furnace.
The Invention consists in the combination of a combustion chamber, a fuel
reservoir, and an inclined passage connecting the two with the casing of the
furnace, having air heating passages communicating with the contracted outlet of
the combustion chamber, in projecting opposing volumes of air in a horizontal
or nearly horizontal course into the heated products of combustion as the latter
pass in a vertical column through the contracted outlet of the combustion chainber,
and in certain details of construction as fully described hereinafter.
The side and back walls of the furnace are cach nade hollow so as to enclose
chambers communicating with each other through openings.
The front plate of the furnace has the usual ash pit opening and another
opening, both of these openings being provided with suitable doors.
On the inner side of the plate above the latter opening is formed a box enclosing
a chamber which communicates through openings in the inner shell of cach side
wall with the chambers within the same.
An inlet opening is formed in the front plate opposite the chamber enclosed by
the box and this opening is provided with suitable sliding doors, by adjusting
which the area of the inlet may be enlarged or diminished for a purpose explained
hereinafter.

page_text: The side and back walls of the furnace are lined with blocks of fine clay or
other refractory material, and attached to or forming part of these blocks are
transverse slabs of refractory material.
Secured to and projecting downward from the box is a plate above which is
another plate, the lower end of which is slotted so as to form a number of
fingers.
The latter plate is pivoted at the lower end so that its upper end may be moved
by means of a rod to one of two positions.
In the front plate above the upper end of the plates lastly mentioned is an
opening which is provided with a hinged lid or cover.
A reservoir is formed on the top of the furnace, this reservoir communicating
through an inclined passage with the combustion chamber which is bounded by
the upper of the two lastly mentioned plates, one of the said slabs, a back plate, a
horizontal grate, and a transverse grate bar, the latter being arranged between the
lower end of the said upper plate and the grate.
Two of the said slabs in connection with a removable cover plate enclose a
transverse chamber which communicates through openings with the chambers in
the side walls.
This transverse chamber communicates through an opening with a contracted
passage through which the products of combustion from the combustion chamber
are compelled to pass in order to reach the discharge passage formed by two of the
said slabs. The chamber in the back wall also communicates with the contracted
passage through an opening, the mouth of which is opposite or nearly opposite to
the mouth of the opening of the transverse chamber.
The width of the contracted passage should be such that volumes of air issuing
from the opposite openings will meet and mingle with each other, and the area
of the openings should be so proportioned in respect to the area of the passage,
that the combined volumes of air issuing from the said openings will be equal to the
volume of the products of combustion with which the air is brought into contact.
Access to the cover plate and to the interior of the transverso chamber is
provided for by hinging a section of the top plate of the furnace so that it can bo
opened when desired, an air space intervening between the said top plate and the
cover plato and serving to prevent the imparting of excessive heat to the top
plate.
The operation or action of the furnace is as follows:-
Fuel is introduced into the reservoir, until the combustion chamber, and the
inclined passage leading thereto are filled and the reservoir partly filled.
When the fuel is ignited the products of combustion pass through the said
contracted passage
and escape
from the discharge opening of the furnace.
Cold air enters the chamber in the said box and traverses the same and the
passages in the side walls, a portion of this air entering the transverse chamber
through the said openings, and the remainder entering the chamber in the back
wall through the said openings. The air becomes highly heated in its courso
through the chambers before it issues from the said openings into the contracted
passage, where it mingles with the products of combustion and causes the ignition
of all of the inflammable gases before they escape from the discharge opening.
Owing to the contraction of the said passage the volumes of air from the said
opposite openings meet each other, and thus insure the bringing of volumes of hot
air into contact with all parts of the products of combustion, thereby preventing
the passage of any of the gases without admixture with a sufficient supply of
oxygen to insure their thorough combustion.
Air for the draft may be permitted to enter the openings in the front plate, and
the cover of the uppermost opening therein may be opened so as to permit the
entrance of air at this point. When the upper one of the two said plates is in one
position, the air entering at the last referred to opening causes the ignition of the
fuel resting on the said plate, and the latter thus forms part of the effective grate
surface. When highly inflammable fuel is employed, however, the door controlling

page_text: this opening should be closed, or if allowed to remain open, the plate should be
adjusted to another position, so that a space shall interveno between the said
plates, through which space cold air circulates, and provents the excessivo heating
of the front plate of the furnace combustion of the fuel on the said plate in this
case being limited to the lower slotted portion of the latter.
The saine result may be attained by substituting for the said upper plate a
series of transverse pivoted soctions, these sections being independently adjustable,
so that the grate surface may be increased or diminished at pleasure.
The entrance of air into the chamber enclosed by the box is controlled by the
adjustment of the said sliding doors, care being taken to permit the entrance of such
an amount of air that the volume projected from the said opposing openings will
equal the volume of the products of combustion passing through the contracted
outlet of the combustion chamber.
The combustion chamber being always filled with a mass of incandescent fuel,
the volume of gases emanating therefrom and passing through the contracted outlet
must always be at a uniform or nearly uniform temperature, the introduction of
fresh fuel having no tendency to retard combustion or lower the temperature of the
gases, owing to the fact that such fresh fuel is introduced at a point comparatively
remote from that at which combustion takes place.
The fuel may be agitated when desired by inserting a suitable implement into
the spaces between the grate bar and the grate, or the lower end of the said upper
plate, and when the latter plate is in the position firstly referred to the fuel may
be further agitated by an implement inserted through the uppermost opening in
the front plate. The grate may also be agitated if necessary.
The structure is self contained and portable and can be applied directly to an
ordinary boiler furnace, the discharge opening of the furnace coinciding with the
usual feed opening of the boiler furnace, so that the volume of flame which issues
from the said opening shall pass directly into the chamber beneath the boilor.
By this means the Invention may be applied with facility to furnaces of the
usual construction, no change in the furnace being demanded except the removal of
the usual fire doors and the closing of the joints between the casing of the improved
furnace and the front plate of the old furnace.
Modified arrangement of the said air delivery openings in respect to the con-
tracted outlet of the combustion chamber may be used, and but one such opening
may be used in a furnace.
The arrangement of outlet and passages previously described is howevor preferred
owing to the fact that when the furnace is thus constructed the gases pass through
the outlet in a vertical column, and the opposing currents of air aro projected
thereinto in a horizontal or nearly horizontal course. By this means the draft acts
with equal force on both volumes of air, and the latter are therefore of uniform
strength. The introduction of the volumes of air in this direction moreover
insures the meeting and commingling thereof before they are carried up by the
products of combustion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Bristow Hunt in the Great Seal Patent Oflice on the 2nd October
1880.
BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex.
Gentleman. "IMPROVEMENTS IN OR RELATING TO THE COMBUSTION OF FUEL AND
IN FURNACES THEREFOR." A communication from abroad by Clark Barnum
Gregory, of Beverley, County of Burlington, in the State of New Jersey, United
States of America.
The object of this Invention is to provide for the complete combustion of the
gases evolved from the burning fuel on or in the grate of a fire-place or furnace.
The Invention consists in the combination of a combustion chamber, a fuel
reservoir, and an inclined passage connecting the two with the casing of the
furnace, having air heating passages communicating with the contracted outlet of
the combustion chamber, in projecting opposing volumes of air in a horizontal or
nearly horizontal course into the heated products of combustion, as the latter pass
in a vertical column through the contracted outlet of the combustion chamber, and
in certain details of construction, as fully described hereinafter.
On the accompanying Drawings, Figure 1 represents a longitudinal section of a
furnace constructed for carrying out the Invention; Figure 2, a sectional plan on the
line 1-2, Figure 1; Figure 3, n sectional plan on the line 3-4, Figure 1; Figure 4,
a longitudinal section of the furnace with some of the parts in a different position
from that shown in Figure 1; Figures 5 and 6, sectional diagrams illustrating
different forms of air supplying passages; and Figure 7, a view showing a modifica
tion of part of the furnace.
The side and back walls A, B, of the furnace are each made hollow so as to
enclose chambers a, b, communicating with each other through openings b¹.
The front plate D of the furnace has the usual ash-pit opening c, and an opening e¹,
both of these openings being provided with suitable doors.
On the inner side of the plate D above the opening c¹ is formed a box E enclosing
a chamber d, which communicates through openings in the inner shell of each
side wall A with the chambers a within the same.
An inlet opening e is formed in the front plate D opposite the chamber d, and
this opening is provided with suitable sliding doors e', by adjusting which the area
of the inlet may be enlarged or diminished for a purpose explained hereinafter.
The side and back walls of the furnace are lined with blocks of fire-clay or
other refractory material, and attached to or forming part of these blocks. are
transverse slabs g, h, and i, also of refractory material, the said slabs being arranged
in respect to each other, as shown in Figure 1.
Secured to and projecting downward from the box E is a plate m, above which
is a plate n, the lower end of which is slotted so as to form a number of
fingers n¹.
The plate n is pivoted at the lower end, so that its upper end may be moved by
means of a rod n² either to the position shown in Figure 1, or to that shown in
Figure 4.
In the plate D above the upper end of the plates m and n is an opening 8, which
is provided with a hinged lid or cover 8'.
A reservoir F is formed on the top of the furnace, this reservoir communicating
through an inclined passage G with the combustion chamber J, which is bounded
by the plate n, the slab g, the back plate f, a horizontal grate M, and a transverse
grate bar N, the latter being arranged between the lower end of the plate n and
the grate M.
The slabs and h in connection with a removable cover plate t enclose a
transverse chamber P, which communicates through openings p with the chambers a

page_text: in the side walls A. Tho chamber P communicates through an opening w with
a contracted passage a, through which the products of combustion from the
chamber J are compelled to pass in order to reach the discharge passage y. The
chamber b in the back wall B also communicates with the passage a through an
opening w, the mouth of which is opposite or nearly opposite to the mouth of the
opening w of the chamber P.
The width of the passage a should be such that volumes of air issuing from the
opposite openings w will meet and mingle with each other, and the area of tho
openings w should be so proportioned in respect to the area of the passage x that
the combined volumes of air issuing from the said openings will be equal to the
volume of the products of combustion with which the air is brought into contact.
Access to the plate t, and to the interior of the chamber P, is provided for by
hinging a section S of the top plate of the furnace so that it can be opened when
desired; an air space intervening between the said top plate and the plate t, and
serving to prevent the imparting of excessive heat to the plate S.
The operation or action of the furnace is as follows:-1
-Fuel is introduced into
the reservoir F until the chamber J and passage G are filled, and the reservoir
partly filled. When the fuel is ignited the products of combustion pass through
the contracted passngo x, and escape from the discharge opening y of the furnace.
Cold air enters the chamber d, and traverses the same, and the passages a in
the side walls A, a portion of this air entering the chamber P through the
openings p, and the remainder entering the chamber b through the openings 6¹
The air becomes highly heated in its course through the chambers before it issues
from the openings w into the contracted passage, where it mingles with the
products of combustion, and causes the ignition of all of the inflammable gases
before they escape from the discharge opening y.
Owing to the contraction of the passage a the volumes of air from the openings w
meet each other, and thus insure the bringing of volumes of hot air into contact
with all parts of the products of combustion, thereby preventing the passage of any
of the gases without admixture and a sufficient supply of oxygen to insure their
thorough combustion.
Air from the draft may be permitted to enter the openings c, c', and the cover
of the opening a may be opened so as to permit the entrance of air at this point.
When the plate n is in the position shown in Figure 1 the air thus entering at the
opening 8 causes the ignition of the fuel resting on the plate n, and the latter thus
forms part of the effective grate surface. When highly inflammable fuel is employed
however the door 8¹ should be closed, or if allowed to remain open the plate n
should be adjusted to the position shown in Figure 4, so that a space v shall interveno
between the plates m and n, through which space cold air circulates, and prevents
the excessive heating of the front plate of the furnace, combustion of the fuel on
the said plate n in this case being limited to the lower slotted portion n¹ of the
latter.
The same result may be attained by substituting for the plate na scries of
transverse pivoted sections, as shown in Figure 7, these sections being independently
adjustable, so that the great surface may be increased or diminished at pleasure.
The entrance of air into the chamber d is controlled by the adjustment of the
slides e, care being taken to permit the entrance of such an amount of air that
the volume projected from the openings w will equal the volume of the products of
combustion passing through the contracted outlet of the combustion chamber.
The chamber J being always filled with a mass of incandescent fuel, the volume
of gases emanating therefrom and passing through the outlet x must always be at
an uniform or nearly uniform temperature, the introduction of fresh fuel having
no tendency to retard combustion or lower the temperature of the gases owing to
the fact that such fresh fuel is introduced at a point comparatively remote from
that at which combustion takes place.
The fuel may be agitated when desired by inserting a suitable implement into
the spaces between the grate N and the grate M, or the lower end of the plate n,

page_text: and when the latter plate is in the position shown in Figure 1 the fuel may be further
agitated by an implement inserted through the opening s. The grate M may also
be agitated if necessary.
It will be observed that the structure shown in the Drawings is self contained
and portable, and can be applied directly to an ordinary boiler furnace, as shown
by the dotted lines in Figures 1 and 2, for instance, the discharge opening y of the
furnace coinciding with the usual feed opening of the boiler furnace, so that the
volume of flame which issues from the said opening y shall pass directly into
the chamber beneath the boiler.
By this means the Invention may be applied with facility to furnaces of the
usual construction, no change in the furnace being demanded except the removal
of the usual fire doors and the closing of the joints between the casing of the
improved furnace and the front plate of the old furnace.
Figure 5 shows a modified arrangement of the air delivery openings w in respect
to the contracted outlet x of the combustion chamber, and Figure 6 shows a furnace
in which but one such opening is used.
The arrangement of the outlet x and passages w, shown in Figures 1 and 4, is
preferred however owing to the fact that when the furnace is thus constructed the
gases pass through the outlet in a vertical column, and the opposing currents of air
are projected thereinto in a horizontal or nearly horizontal course. By this means
the draft acts with equal force on both volumes of air, and the latter are therefore
of uniform strength. The introduction of the volumes of air in this direction
moreover insures the meeting and commingling thereof before they are carried up
by the products of combustion.
Having now described the nature and object of the said Invention, together with
the manner in which the same is to be or may be performed or carried into
practical effect, I would remark in conclusion that I claim as the Invention
communicated to me by the above-named Clark Barnum Gregory,-
First. The combination in a furnace of the combustion chamber J having a grato
and contracted outlet, the fuel reservoir F, the inclined passago G connecting the
fuel reservoir and combustion chamber, and the casing of the furnace having an
air heating chamber or chambers communicating with the contracted outlet of tho
combustion chamber.
Second. The combination of the reservoir F with a furnace having an outer
casing, lining, and grate constructed and combined substantially as herein before
described, so as to form a combustion chamber J with a contracted vertical outlet x,
an inclined passage G connecting the reservoir and combustion chamber, and air
heating chambers terininating in opposite horizontal or nearly horizontal passages w
communicating with the vertical outlet x.
Third. The combination of the casing of the furnace and its lining blocks f with
the transverse slabs g, h, and i forming the contracted outlet of the combustion
chamber J and the passages w, w, communicating therewith.
Fourth. The combination of the front plate D having a valved opening c and
box E inclosing chamber d, the hollow side walls inclosing chambers a, the hollow
rear walls enclosing a chamber b and the transverse chamber P, the said chambers
communicating with each other and with the contracted outlet of the combustion
chamber.
Fifth. The combination of the plate n, the grate M, and the intervening grate
bar N.
Sixth. The combination of the inclined and grated plate n the inclined plate m
arranged in respect to the plate n, as herein before described, so as to form an
intervening space, and the front plate D having an air opening s located adjacent
to the upper ends of the said plates m and n, whereby a current of cold air is
caused to pass downward through the space between them and away from the
front plate.
Seventh. The combination in a furnace of the combustion chamber J, the fuel
reservoir F, the inclined passage G connecting the two, the plate n forming the

page_text: bottom of the said passage, and the front plate D having an openings at the top
of the said plate n.
Eighth. The combination of the side walls A having chambers a with the
transverse slabs gand h, and the cover plate t forming the transverse air
chamber P.
Ninth. The combination of the front plate D having an opening 8, the plate m,
and the plate n adjustable in respect to the said plate m, so as to vary the effective
grate surface.
Tenth. The combination of the transverso air chamber P with the hollow walls
of the furnace containing chambers communicating therewith, and the top plate of
the furnace arranged in respect to the casing of the air chamber, as hereinbefore
described, whereby a spaco is formed above the same.
Eleventh. The combination of the hollow side walls containing air chambers, as
herein before described, the transverse air chamber P having a detachable top
plate t, and the top plate of the furnace having a movable section S.
Each and all substantially as hereinbefore set forth or described, and as illustrated
on the accompanying Drawings.
In witness whereof, I, the said Bristow Hunt, have hereunto sot my hand
and seal, this Second day of October, in the year of our Lord One thousand
eight hundred and eighty.
BRISTOW HUNT. (L.S.)