Improvements in Apparatus for Controlling the Draft in Chimneys.
Year: 1893

page_text: Date of Application, 17th Jan., 1893-Accepted, 18th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in Apparatus for Controlling the Draft in Chimneys.
I, GEORGE LANDER THIELL, of Number 1440 Aisquith Street, in the City of
Baltimore and State of Maryland, United States of America, Manufacturer, do
hereby declare the nature of my invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the
following statement :-
In all furnaces and the combustion chambers of boilers, there is a certain pressure,
below that of the atmosphere, which effects the greatest economy in the combustion
of fuel in the said furnace; and the object of the present invention is to auto-
matically maintain that pressure by means of the chimney damper, using primarily
as a force or means of effecting the necessary movement of the damper, any excess
in pressure of the gases or the atmosphere caused by the disturbance of or change
in the relative pressures of the gases and the atmosphere which is sought to be
maintained.
In carrying out this invention, I employ a diaphragm one side of which is open
to the atmosphere, and the other in communication with the combustion chamber
of the boiler. With this diaphragm I use a combination of devices whereby its
movement, effected by the relative pressures of the air and gases, is communicated
to the damper in the chimney, as will hereinafter fully appear.
In the further description of the said invention which follows, reference is made
to the accompanying drawings forming a part hereof and in which,-
Figure 1 is a side view of a land or stationary boiler provided with the present
invention, the brick setting of the boiler, and certain parts of the invention, being
shown in section.
Figs. 2 and 3 are enlarged details of the invention.
Referring to the drawings, A is the boiler and B the brickwork setting. C is the
furnace and D the combustion chamber or smoke box, separated from the furnace
by the bridge wall a.
E is the stack or chimney in which is swung the damper F.
G is a circular box consisting of the upper and lower sections, represented
respectively by b and c. The sections b and c are flanged where they are united, and
between the flanges is secured a flexible diaphragm d impervious to air, and
preferably formed of rubber or thin sheet metal which may be corrugated if
desired.
The lower section c is provided with a stand e whereby it is supported from the
top of the boiler setting, or from any other fixed body which is at a convenient
distance from the chimney E.
To the upper face of the diaphragm and centrally thereof, is attached a stem f
which leads through an opening in the upper section b, of the box, and is jointed to
a horizontal arm H having its fulcrum in a stand h. From the horizontal arm H
leads a vertical arm I, and its end is connected by a link J to the damper
lever j.
The lower section c of the box G is connected with the interior of
the combustion chamber D by a pipe K, and the upper section is in communica-
tion with the outer air by means of a pipe L which, to prevent the entrance of dust
thereto, is turned down. Air may, however, be admitted around the stem ƒ and
the annular opening guarded against the entrance of dirt by a hood k, or both air
passages may be used, as shown in the drawing.
The horizontal arm H is provided with a weight O to counter-balance the gravity
of the stem f, and counteract the tendency of the diaphragm to sag in the centre
by its own weight.
Supposing the damper to be in the position which at the time gives the proper

page_text: draft to secure the greatest economy in fuel; and that by either opening the
furnace doors, or by the admission of too much air through the bed of coal to the
furnace, the pressure in the combustion chamber is raised above that stated,
the differential pressure on the diaphragm is changed and the diaphragm elevated
by the increased pressure below it, which movement, through the medium of the
levers and arms described, is communicated to the damper and that device is some-
what closed. The closing of the damper checks the draft, or in other words retards
the entrance of air to the furnace, until by the combination of the oxygen of the
air with the gases in the furnace, the pressure in the combustion chamber is again
reduced, when a reverse action of the diaphragm and damper takes place.
Supposing however, that the pressure in the combustion chamber should become
too low to effect thorough combustion of the gases, there not being sufficient air or
oxygen to properly combine with them, the diaphragm is depressed by the
practically increased pressure of the atmosphere, and the damper opened which
increases the draft, and more air is drawn through the fire.
From the foregoing it will be seen that the draft to produce proper combustion
is regulated entirely by the relative pressures of the gases in the combustion
chamber, and the atmosphere.
It is evident that a piston working in a cylinder could be used in some cases
instead of a diaphragm confined in a box, and I desire it to be understood that
wherever the word diaphragm occurs in the description of my invention, it is used
as a term synonymous with a piston operating in a cylinder.
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 :-
:-
1. As means for operating a damper in a chimney, a movable body subjected
at one side to the pressure of the gases in the furnace or combustion chamber, and
at the other side to the atmosphere, substantially as specified.
2. In combination with the combustion chamber of a furnace, and a chimney in
communication therewith, a movable tight body having one side thereof subjected
to the products of combustion from or in communication with the said furnace,
and the other side open to the exterior air, a damper situated in the chimney and
means to connect the said movable body to the said damper, substantially as, and
for the purpose specified.
3. In combination with a furnace and the chimney, a damper in the chimney, a
box containing a diaphragm one side of which is in. communication with the outer
air, and the other with the interior of the furnace, and means substantially as
described whereby the movement of the diaphragm is communicated to the said
damper, substantially as specified.
Dated this 23rd day of December 1892.
Witnesses:
GEO. E. TAYlor.
Wм. T. Howard.
GEORGE' LANDER THIELL.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.