Improvements in the Method of and Means for Promoting Combustion in Furnaces.
Year: 1894

page_text: Date of Application, 23rd Apr., 1894-Accepted, 16th June, 1894
Improvements in the Method of and Means for Promoting
Combustion in Furnaces.
I, JOHN BLACK DAVIDS, of North Dartmouth, in the County of Bristol and
State of Massachusetts, U.S.A., Gentleman, 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 relates more particularly to methods of promoting combustion
under the boilers of steam vessels.
The method ordinarily employed of promoting combustion under such boilers,
is to construct the fire-room, so that it can be tightly closed, and forcing air into
said room, and thus through the fire, in such quantity as to give the required
combustion. This method renders it impossible for the firemen to sustain life
longer than a few minutes at a time, because of the condensed air, and the great
heat. The object of this invention, is, to render the firing of such boilers, more
endurable, and less risky to the lives of the firemen.
The accompanying drawing illustrates my invention, in which
Fig. 1, represents a front elevation of a fire-box, boiler, and smoke-stack,
provided with my improvements, and having a portion of the-fire-box broken away,
to more fully show a portion of the construction.
Fig. 2, represents a side elevation of the same, showing the fire-box, and smoke-
stack in longitudinal section.
Similar letters refer to similar parts in the several views.
The letter a, represents a smoke-stack to a boiler, having an air tight chamber c,
around the outside of its base.
d, represents a circular partition, secured to the bottom of the chamber c, and
extending nearly to the top of said chamber. e, represents tubes of varying
heights, which are secured in that portion of the wall of the smoke-stack, enclosed
by the chamber c, and extend upward along the inside of the same, preferably
having their ends h, inclined inward towards the centre of the flue. The tubes e,
instead of extending upward inside of the smoke-stack, may be connected with the
top of the chamber c, and extend upward on the outside of the stack, and enter it
at the required point.
9, represents a pipe resting on the chamber c, and provided with the holes s, near
its base, and sufficiently large in diameter to leave an air-space, between it, and the
outside of the smoke stack a. k, represents an air-pipe, leading from an air-pump
or air-reservoir (not shown) and having its end o, projecting under the grate of the
fire-box f, where it is provided with a series of perforations p. 1, represents an
air-pipe, branching from the pipe k, and leading into the chamber c.
The pipe 1, is supplied with the valve m, and the pipe k, is supplied with the
valve n, located between the junction of the pipes k, and l, and the fire-box f.
The pipe k, is further supplied with the openings q, which are adapted to be
closed by the slide r.
In operation, air is forced through the pipes k, and 1, by an air-pump, or other
suitable means. The air which passes through the pipe l, enters the chamber c,
and passes thence, into the tubes e, and out at their upper ends. The strong blast
of air, issuing from the upper ends of the tubes e, causes a partial vacuum below
them, which the air, still below, rushes to fill, and thus a strong upward current of
air is created in the stack, and a strong draft is obtained. The draft is further
assisted by the air issuing from the perforated end o, of the pipe k. When coal is
added to the fire, the blast from the perforations p, is shut off, by the valve n, in

page_text: order to prevent the flame from issuing from the door of the fire-box. When no
increased draft is desired, the valves m, and n, are both closed.
When it is desired to reduce the temperature of the fire-room, the valve is
opened, so as to admit a supply of cool air to the bottom of the fire-room.
The pipe or casing 9, serves to check the radiation of heat from the smoke-
stack a; and the holes s, are provided, so that there may be a free circulation of
air between them. The circular partition d, serves to distribute the air, entering
the chamber c, from the pipe 1, equally, to all the tubes e.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I déclare that what I
-claim is-
1st. In combination with a smoke-stack to a steam boiler, the annular chamber c,
secured at the base of said smoke-stack; the tubes e, extending upward to varying
heights and connecting the interior of said chamber, with the interior of said
smoke-stack; and means for forcing air into said chamber c, substantially as shown
and described.
2nd. In combination with the fire-box, and smoke-stack to a steam boiler, the
pipe k, leading from an air-reservoir, containing air under pressure, and having
openings q, opening into the fire-room, adapted to be closed at certain times;
and having the branch o, provided with the valve n, and perforations p, extending
into the fire-box, beneath the grate, and having the branch 1, provided with
the valve m, extending into the chamber c; whereby the blast of air through
said pipe, may be directed wholly below the fire, or wholly into the smoke-
stack, or wholly into the fire-room, or divided between said points, or shut off
entirely from all or any one of said points, as and for the purpose specified.
Dated this 11th day of April 1894.
JOHN BLACK DAVIDS.