Draught in Steam-boiler and other Furnaces.
Year: 1888

page_text: 1
[Communicated from abroad by GILMAN WELD BROWN, of West Newbury, and
CHARLES DELL MOSHER, of Amesbury, both in Massachusetts, United States
of America, Manufacturers.]
Draught in Steam-boiler and other Furnaces.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings in the County of Middlesex, do hereby declare the nature of
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 has for its object to provide simple and effective means for creating
draft through the furnaces of marine and other boilers, and it consists first in a rotary
fan or blower located at a suitable point in the flue or passage through which the
products of combustion pass from a furnace; said blower having hollow blades formed
to permit the continuous passage of air, the arrangement being such that cool external
air is admitted to and passes through said blades, which are thereby protected from
the intense heat to which they are subjected. The invention also consists in
certain details of construction, all of which we will now proceed to describe and
claim.
Of the accompanying drawings forming a part of this specification, Figure 1
represents a front elevation of a portion of the flue or passage between the furnace
and smoke stack of a steam boiler. Fig. 2 represents a section on line a a, Fig. 1.
Fig. 3 represents a perspective view of a portion of an improved fan, and a
portion of the flue casing. Fig. 4 represents a sectional view of one of the fan
blades.
The same letters of reference indicate the same parts in all the figures.
11

page_text: through a steam boiler from the furnace to the stack of a steam boiler. In the
casing d, connecting said tubes and stack, we place a rotary fan, the blades cc of
which are hollow, their inner ends opening to the external air through slots c¹ in a
frusto conical diaphragm f, which is attached to the bases of the blades and to the
shafte which rotates the fan. The outer ends of said blades open into the casing d so
that outside air passing through the blades mingles in said casing with the products
of combustion in said casing and passes to the stack. The outer side of the casing d
has an opening d¹, the margin of which is in the closest possible proximity to the outer
edge of the diaphragm f, so as to prevent as fully as possible the admission of outside
air into the casing around said diaphragm without being in contact with said diaphragm,
which, of course, rotates with the fan and prevents outside air from passing into the
casing d between the fans.
The shafte which rotates the fan is journaled in bearings i i, one of which projects
into the diaphragm f and supports said shaft close to the hub or spider ; to which the
blades c are attached. Said shaft may be rotated by any suitable means, and is here
shown as provided with a crank k adapted to be connected with an engine of any
suitable type. The shafte has a longitudinal passage m, which is open at one end to
the outside air and communicates with an air space s between the inner side of the
hub n and a cap n² attached to the blades c. The air space s communicates with the
air passages in the fans through openings in the bases of the fans. Air is thus caused
to pass continually through the hub of the fan to protect said hub from the heat to
which it is subjected.
I prefer to cover the blades with asbestus paper p, or other suitable non-conductor
of heat, suitably secured to said blades as a means for additionally protecting the
blades from the heated products of combustion. The exposed surface of the cap n
may also be protected by asbestus paper p', as shown in Fig. 2.
It will be seen that the rotation of the fan creates a draft in the casing d, while the
constant passage of cool air through the blades of the fan prevents said blades from
being injured by the heat. My improvement therefore makes the use of a fan
practicable as a means for forcing a draft, furnishes a simple and comparatively inex-
pensive substitute for the complicated, expensive, and dangerous forced draft systems
now in use.
It is obvious that the form and arrangement of the fan and its diaphragm ƒ may be
variously modified without departing from the spirit of my invention.
I do not limit myself to a fan arranged in close proximity to an opening in the flue
casing and provided with a diaphragm as shown, for the fan may in some cases be
placed within the flue or stack at a distance from the casing and receive air into its
blades through the hollow shaft which rotates the fan.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me by
my foreign correspondent I declare that what I claim is
1st. The combination with a flue or conduit for the products of combustion from a
boiler furnace, of a rotary fan within said flue, having hollow blades and connections
between said blades and the atmosphere outside of the flue whereby cool air is enabled
to pass through the blades, as set forth.
2nd. The combination with a flue or conduit for the products of combustion from a
boiler furnace, of a rotary fan within said flue, having hollow blades and connections
between said blades and the atmosphere outside of the flue whereby cool air is
enabled to pass through the blades, a shaft supporting said fan, and a motor
connected with said shaft outside of the flue whereby the shaft and fan are rotated, as
set forth.
3rd. The combination with a flue or conduit for the product of combustion from a
boiler furnace, of a rotary fan within said flue, baving hollow blades and connections
between said blades and the atmosphere outside of the flue whereby cool air is enabled
to pass through the blades, a crank shaft supporting said fan, and an engine connected
directly with the crank of said shaft outside of the flue, as set forth.

page_text: 4th. A rotary fan having hollow blades containing air passages, and a diaphragm
secured to the fan as a means for preventing air from passing between the blades,
said diaphragm having openings for the admission of air to said air passages, as set
forth.
5th. A rotary fan having hollow blades containing air passages, and a diaphragm
arranged to prevent air from passing between the blades, said diaphragm having
openings for the admission of air into the blades, combined with a casing having an
opening coinciding with said diaphragm, as set forth.
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.
Agents for the Applicant.