Improvements in or relating to Furnace Doors.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to Furnace Doors.
I, JAMES STUART LETHEM, of 76, Bignor Street, Cheetham, Manchester, in the
County of Lancaster, Engineer, do hereby declare the nature of this invention
to be as follows:-
The object of my invention is to supply air to furnaces through the furnace
door and to regulate the supply thereof in such a manner as to lessen the produc-
tion of smoke and to obtain a more perfect and economical combustion of the
fuel.
For the purposes of my invention I attach to the outside of the furnace door a
chamber provided with openings in front for the admission of air through the
same.
In the chamber I fix vertical partitions which divide it into passages along
which the air is guided to suitable openings in the door proper, each passage in
the outer chamber leading to a corresponding aperture or opening in the door.
I prefer that the apertures or openings in or near the top and bottom of the
outer chamber should be permanently open and that the central or intermediate
apertures should be in the form of a grid provided with a slide or louvres for
opening and closing the same, but in some cases all the apertures in the outer
chamber may be provided with slides or louvres or other equivalent device for
opening or closing purposes.
Through these apertures in the door the air passes into a second chamber formed
by a box attached to the inside of the door.
This inner chamber is also divided by vertical partitions into passages corres-
ponding with the openings in the door, and at the open end of these passages
nearest to the fire the air is for the most part discharged into the furnace, although
I may also distribute a portion of the air through slots or openings in the floor
of the passages.
To these passages I give a certain outwardly curved or radiating direction so
as to discharge or distribute the air, not only centrally into the furnace, but also
to direct it laterally to the right and left, with the object of spreading the air over
the entire breadth of the furnace.
To effect this lateral distribution of the air in a fan-like form I give such a
direction to certain of the passages that the air passing through the same will
have a long run and be guided and discharged towards the right side of the
furnace and similarly, I arrange an equal number of passages so as to discharge
air towards the left, and the remaining passages to discharge the air centrally into
the furnace or approximately so.
I also give a general downward direction to all the air passing through the door,
by sloping the roof and floor of the inner chamber downwards towards the fire.
Thus the air is distributed to the right, to the left, and centrally and an equi-
librium is maintained in the air so discharged. I have found that this method
of directing the air is more effective in preventing smoke, and causing or assisting
the more equal combustion of the fuel all over the grate than when the air

page_text: admitted through the door merely passes centrally over the grate, I have also
found it to be more economical in practice.
;
It will be obvious that when the fire is ignited in the furnace, the walls, roof
floor and partitions of the inner chamber attached to the door become very hot,
and I have found it an advantage to utilize this to the fullest extent in heating
the air passing through and to increase the heating surface I introduce at the
inner or terminal ends of the said passages midfeathers and sometimes also hori-
zontal cross-pieces all of which extend for some distance into the passages, so that
the said passages are sub-divided both vertically and horizontally towards their
terminal ends giving them a cellular appearance, and a greatly extended heating
surface is thus provided and when the fire is ignited a considerably increased
temperature is imparted to the air before it is discharged into the furnace, whereby
a more perfect combustion is obtained smoke is prevented or reduced and a con-
siderable economy in the consumption of fuel is effected.
Alternatively, instead of sub-dividing the passages at their terminal ends I may
in some cases shorten the passages of the inner chamber and attach to their ends
tubular nozzles through which the air is passed into the furnace, and I give to
these nozzles an outwardly curved or radiating direction similarly to the sub-
divided passages, as above described, for the same purposes of distributing and
heating the air. In such case the air distributed would be raised to a higher
temperature, but at the same time the amount of air discharged would be reduced.
In certain cases I may also dispense with the outer chamber of the door, having
air apertures or openings in the latter fitted with a slide, or slides, or louvres, or
the like, and the same may be opened or shut by any suitable device to be worked
by hand or by automatic mechanism.
I may also in some cases when desirable introduce a steam jet or other appliance
to force steam or air through the door to assist in the combustion of the fuel.
Dated this 8th day of Santamaahan 1907
GEO. DAVIES & SON,
Agents for the Applicant, 4, St. Ann's Square, Manchester.
I, JAMES STUART LETHEM, of 76, Bignor Street, Cheetham, Manchester, in the
County of Lancaster, Engineer, 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:-
The object of my invention is to supply air to furnaces through the furnace
door, and to regulate the supply thereof in such a manner as to lessen the produc-
tion of smoke, and to obtain a more perfect and economical combustion of the
fuel.
The nature of my said invention and the manner in which the same is to be
performed or carried into practical effect will be readily understood on reference
to the annexed sheet of drawings and the following explanation thereof.
Fig. 1 on the drawings is a front elevation of a furnace door made according to
iny invention, the front grating and slide being removed, and Fig. 2 is a similar
view of the door with the front grating and slide affixed thereto.
Fig. 3 is a horizontal section of the same through the line A-B in Fig. 1.
Fig. is a vertical section thereof through the line C-D in Fig. 2, and Fig. 5
an elevation of the inner side thereof.
For the purposes of my invention I cast or otherwise attach to the outside of

page_text: the furnace door a a projecting chamber 6 provided with openings c in front for
the admission of air through the same (see Figs. 1, 3 and 4).
In this chamber b I cast or fix vertical partitions e which divide it into passages
along with the air is guided through suitable openings in the door proper.
In front of these openings I may fix a grid f (see Fig. 2) which is opened
or closed by the means of a slide g or I may employ louvres or other equivalent de-
vice for opening and closing purposes, and in some cases I propose to make ad-
ditional openings or to carry some or all the vertical openings c above or below (or
both above and below) the grid f so that certain of the apertures or certain portions
thereof shall always be open to admit air.
Through the apertures in the door a the air passes into a second chamber
formed by a box attached to the inside of the door. This inner chamber is also
divided by vertical partitions e* into passages corresponding with the openings
through the door, and at the open end of thegg passages nearest to the fire the
air is for the most part discharged into the furnace although I may also dis-
tribute a portion of the air through slots or openings in the floor of the passages
(see Figs. 3 and 4).
To these passages I give a certain outwardly curved or a radiating direction
(see Fig. 3) so as to discharge or distribute the air not only centrally into the
furnace, but also to direct it laterally to the right and left with the object of spread-
ing the air over the entire breadth of the furnace. To effect this lateral distribu-
tion of the air in a fan-like form I give such a direction to some of the inner
passages that the air passing through the same will have a long run and be
guided and discharged towards the right side of the furnace, and similarly, I
arrange an equal number of the passages so as to discharge air towards the left,
and the remaining passages to discharge the air centrally into the furnace or
approximately so, as seen at Fig. 3.
I also give a general downward direction to all the air passing through the door
by sloping the roof and floor of the inner chamber or box h downwards towards
the fire as shown at Fig. 4.
Thus the air is distributed to the right, to the left, and centrally, and an equi-
librium is maintained in the air so discharged.
I have found that this method of directing the air is more effective in pre-
venting smoke, and causing or assisting the more equal combustion of the fuel all
over the grate, than when the air admitted through the door merely passes centrally
over the grate, I have also found it to be more economical in practice
It will be obvious that when the fire is ignited in the furnace, the walls, roof,
floor, and partitions of the inner chamber h attached to the door become very
hot, and I have found it an advantage to utilize this to the fullest extent in heat-
ing the air passing through, and to increase the heating surface I introduce at the
inner or terminal ends of the passages mid feathers k (Fig. 3) and sometimes also
horizontal cross-pieces all of which extend some distance into the passages, so
that the said passages are subdivided both vertically and horizontally towards
their inner or terminal ends giving them a cellular appearance as shown at Fig. 5,
and a greatly extended heating surface is thus provided; and when the fire is
ignited a considerably increased temperature is imparted to the air before it is
discharged into the furnace, whereby a more perfect combustion is obtained,
smoke is prevented or reduced, and a considerable economy in the consumption
of fuel is effected.
Alternatively, instead of sub-dividing the passages at their terminal ends I
may in some cases shorten the passages of the inner chamber and attach to their
ends tubular nozzles through which the air is passed into the furnace, and I
give to all or to certain of these nozzles an outwardly curved or radiating direc-
tion similar to the direction given to the sub-divided passages, as above described,
and for the same purposes.
By the use of nozzles the air distributed would be raised to a higher tempera-
ture but the amount of air discharged into the furnace would be reduced.

page_text: In certain cases I may also dispense with the outer chamber of the door, having
merely air apertures or openings in the latter fitted with a grid and slide, or
louvres or the like, and the same may be opened or shut by an excentric and cross
handle m as shown or by any suitable device to be worked by hand or by auto-
matic mechanism.
I may also in some cases, when desirable, introduce a steam jet or other appliance
to force steam or air through the door to assist in the combustion of the fuel.
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:-
First The improvements in or relating to furnace doors for the more efficient
introduction heating and distribution of air to the furnace constructed and
applied substantially as herein before described and illustrated by the drawings
annexed.
Secondly: A furnace door slotted, with an inner box or chamber divided by
upright partitions into vertical passages to which an outwardly curved or radiat-
ing direction is given for the purposes as stated.
Thirdly; A furnace door, slotted, with an inner box or chamber divided into
passages, the said passages sub-divided towards their terminal ends by vertical
midfeathers or horizontal cross pieces or by both, for the purpose of providing a
large heating surface.
Fourthly In combination, a furnace door, slotted, with a inner box or chamber
divided by upright partitions into vertical passages to which an outwardly curved
or radiating direction is given, the said passages being subdivided towards their
terminal ends by vertical midfeathers, or horizontal cross pieces, or by both.
:
Fifthly A furnace door, slotted, with an outer box or chamber divided by
upright partitions into vertical passages for the purpose of maintaining a pro-
portion in the quantity of air passed through the door towards the right side,
centre, and left side of the furnace or approximately so.
Sixthly: A furnace door, slotted, with an outer box or chamber divided by
upright partitions into vertical passages, in combination with an inner box or
chamber divided by upright partitions into vertical passages to which an outwardly
curved or radiating direction is given.
Seventhly In combination, a furnace door, slotted, with an outer box or
chamber divided by upright partitions into vertical passages, in combination with
an inner box, or chamber divided by upright partitions into vertical passages to
which an outwardly curved or radiating direction is given, the said passages sub-
divided towards their terminal ends by vertical midfeathers or horizontal cross
pieces, or by both.
GEO. DAVIES & SON,
Agents for the Applicant, 4, St. Ann's Square, Manchester.