Improvements in Apparatus for Controlling the Admission of Air to Furnaces.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Controlling the Admission of Air to
Furnaces.
I, GEORGE LANDER THIELL, of 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 Letters Patent No. 1058 granted to me on the 17th day of January 1893, I
show and describe apparatus wherein a diaphragm having one side thereof exposed
to the gases in the combustion chamber of a boiler furnace, and the ether to the
atmosphere, is connected by certain levers and rods to the damper lever, to operate
it. In such an arrangement the only power to operate the damper, is that
consequent upon change in the relative pressures of the gases in the combustion
chamber, and the atmosphere; and to obtain sufficient force to readily move the
damper with a very slight alteration in the said relative pressures, the diaphragm
has to be large, and large diaphragms are objectionable in many respects.
In the present invention I am enabled to reduce the size of the diaphragm, by
operating the damper directly by a steam or water motor, and only operate the
valve which controls the admission of steam or water to the motor, by means of
the diaphragm. With this arrangement, a small diaphragm only is required, or
one of sufficient power only, to operate the motor valve with a very slight variation
in the relative pressures of the gases and the air.
In the 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 partly sectional side view of an upright water tube boiler provided
with the present invention.
Fig. 2 is an enlarged exterior view of the apparatus alone, as seen from a point
removed 90 degrees from that taken in Fig. 1.
Figs. 3, 4, 5, 6 and 7 are details of the apparatus on a further enlarged scale.
Figs. 8 and 9 illustrate a modification in the construction of certain parts of the
apparatus, as hereinafter described.
Referring now to Fig. 1 of the drawings, A is an ordinary vertical water tube
boiler, and B the chimney damper, the movement of which under circumstances
hereinafter described, is the ultimate object of the invention.
Referring now particularly to Fig. 3 of the drawings, which is a sectional side
view of the principal parts of the apparatus, C is a box in two parts or sections,
having a suitable stand a whereby it is supported. In the present case, the
stand rests on a shelf (shown only in Fig. 1) projecting from the side of the
boiler.
Between the two parts or sections c and d of the box C, is a flexible
diaphragm D held in place by bolts e which also hold the two sections, c and d
together. This diaphragm may be made of any suitable material, but cotton duck
treated with rubber is preferred. Fig. 5 is a top view of Fig. 3 and Fig. 6 a
section of Fig. 3 taken on the dotted line x-x.
E and F are circular metallic plates secured, respectively, to the top and bottom
of the diaphragm D.
G is a stem held to the plates E and F, and
This stem passes through an aperture
nuts g.
also to the diaphragm D, by the
in the top section c of the box C,

page_text: 4
and its head is provided with a conar z naving an army extending laterany from
one side thereof.
The lower section of the box C is connected with the interior of the furnace
of the boiler A, or to the combustion chamber thereof, by a pipe H, shown only
in Figs. 1, 2, and 7. The nozzle k for the said pipe is, however, shown also in
Fig. 3.
I is a steam or water cylinder, erected, by preference, on the top of the section c
of the box C, and near to the centre thereof.
Jis a piston in the cylinder I having a rod K which passes through the cylinder
head m at the upper end of the cylinder.
The end of this piston rod is provided with an eye n or any other suitable
apppliance, whereby it is connected to a chain o, which passes over a pulley p, and
is attached to the damper lever q.
The length of this chain is such that when the piston J is at the bottom of the
cylinder I the damper is closed.
L is a weight seated on a plate on the piston rod K, and it is of such
size as to close the damper B when the piston J is not sustained by steam or
water. In other words, the closing of the damper is effected by the gravity of
the weight L.
In the present case, the damper B is weighted at one side so as to automatically
open when the chain o is slackened by the rise of the piston J in the cylinder I.
In some applications of this invention to boilers, the damper is opened by a system
of rods and levers, and in such cases, the force of the upwardly moving piston rod
is used to open the damper.
M is a valve chest having a nozzle s screwed into the wall of the cylinder I at a
point below the piston J.
This valve chest is bored out for the reception of the hollow cylindrical valve N
hereinafter more particularly described, and it has the nozzles a and into which
are screwed, respectively, the waste pipe c' leading to a sewer, and the steam or
water pipe d' which in the present case is intended for water and connected to the
service pipe of the water supply. These pipes are shown only in Fig. 2, but the
nozzles for them are illustrated in Fig. 4. The valve N has two annular grooves e¹
and which serve to bring into communication, under certain circumstances
hereinafter described, the ports g' and ' which lead to the nozzles a¹ and b¹, and
also to place the nozzles in communication with either of the ports g' or ' through
the medium of the apertures 92 and 2 leading into the interior of the valve N as
hereinafter described.
Fig. 4 shows the valve chest, and valve, as seen from a different point of
view.
The upper end of the valve N is slotted and in this slot is placed a lever O
fulcrummed at i¹ to a bracket j' projecting from the valve chest M. This lever
terminates in a yoke k' which straddles the collar i and is pivoted to the arm j
which is a part of the said collar.
P is a grooved pulley adapted to revolve on a stud m¹ projecting from an arm Q
which extends from a band R which is around the cylinder I. This grooved pulley
has a smaller flanged pulley S formed on its outer face and to this latter pulley is
attached a chain n¹ fastened to the upper end of a spiral spring T having its lower
end secured to the head of the stem G by means of an adjusting eye screwed into
the stem G.
Another chain o' leads from the grooved circumference of the pulley P to which
it is fastened, to an arm U on the piston rod K and situated immediately below
the weight bolding plate r..
.
Supposing the boiler to be in use, and the furnace door open so that the pressure
of the gases in the combustion chamber is equal to that of the air, the diaphragm D
assumes the elevated position shown in Fig. 3 and the valve N is raised.
The valve N being in its highest position, the port leading to the water
supply pipe d' is closed and the space below the piston J in the cylinder I is in

page_text: communication with the outlet or discharge pipe c¹ by means of the nozzle S, the
annular groove f¹, the aperture 2, the central passage in the valve N, the .
aperture, the annular groove e¹ and the port g'.
From this it will be seen that no water under pressure can remain under the
piston J to sustain it, and the piston is held down by the weight L and the
damper B kept closed by the chain o.
Upon the closing of the furnace door, the pressure in the combustion chamber
is reduced, and the diaphragm D consequently depressed, and in the depression
of the diaphragm the valve N is lowered until its head strikes the top of the
valve chest M. The port g' leading to the discharge pipe is thus closed, and
the port opened or uncovered by the valve N. Water entering the port h
passes to the annular groove e¹, thence through the aperture g, the central
channel of the valve N, thence through the aperture 2 to the annular groove f¹
and thence to the nozzle s leading to the underside of the piston J.
All
The piston is then raised by the incoming water and the damper opened. As
the piston rod K with its arm U rises, the chain o¹ is drawn which turns the
pulley P and effects the winding of the chain n¹ on the small pulley S. This
winding of the chain n' extends the spring T, and when the tension on the said
spring overcomes the resistance of the diaphragm, the diaphragm D is slightly
raised and by this motion, the flow of water to the cylinder 1. cut off.
further movement of the damper while the same relative pressures of gases and
air on the diaphragm are maintained, is thus prevented, as no more water can
enter the cylinder to elevate the piston, and that already therein cannot escape
until by a change in the relative pressures of the gases and air on the diaphragm,
the valve N is again moved.
For instance, should the fire require still more air, the pressure in the com-
bustion chamber becomes less, and the diaphragm is further depressed by the
practically increased pressure of the atmosphere. The depression of the diaphragm
causes the valve N to be again lowered, and the port / to be again uncovered
and this serves to admit more water to underneath the piston J and that device
is therefore further elevated which slackens the chain o' and the damper being
loaded is automatically opened. This further opening of the damper continues
until in the winding of the chain n' and the extension of the spring T, the down-
ward movement of the diaphragm is arrested and the valve N elevated so as to cut
off all further entrance of water as before described.
But should the fire require less air, instead of more, owing to the formation of
bare spaces on the grate bars, through which spaces air enters the furnace, the
pressure in the combustion chamber is increased, and the diaphragm raised which
causes the valve N to uncover the port g' which operation adinits of the escape of
water from under the piston J and that device being for the time unsupported by
water under pressure, it is lowered by the gravity of the weight L, and the damper
somewhat closed by the drawing of the chain o¹.
From the foregoing, it will be understood that owing to the elasticity of the
spring T which is an element of the connecting mechanism between the piston
rod K, and the diaphragm D, the valve N is so adjusted that the damper when
placed in a certain position is held thereat until a different ratio of pressures of the
gases and air, is established, when an adjustment of the damper is promptly
made, and the new position of the damper maintained, until another change is
required.
With
with the
Figs. 8 and 9 correspond with Figs. 3 and 4 except that the valve N is lifted
directly by the arm j, instead of by the lever O connected to the said arm.
this alternate construction, the valve N has a motion in common
diaphragm D, and the accurate adjustment of the damper by the operation of the
said valve as described, is not effected to the same extent.
It is applicable however for use in cases where a uniform quantity of fuel is
supplied to the furnace, as where the fuel consists of oil or gas, and the flow
controlled by valves or cocks. In such applications, the draft in the chimney must
:

page_text: be uniform notwithstanding changes in temperature of the air, velocity of the wind,
or in the density of the atmosphere.
To effect this uniform draft in the chimney, the valve chest M is provided with
the ports g and h¹ before described, but the valve N is furnished with annular
ports a, b and c³ which are in communication with the interior of the valve by
means of holes d³, e³, and ƒ³. It has also the annular groove f' and the aperture ²
before described.
Supposing the diaphragm D, and the valve N to be in the positions shown, the
discharge port g' is open, for the reason that the nozzle s is in communication with
the annular groove f¹, aperture 2, the central channel in the valve, the hole c³ and
the port 63 leading to the port g¹.
When the furnace door is closed, the diaphragm is depressed until the port c³ of
the valve N, comes into alignment with the port ', when water from the port /'
enters the port c³ and passes through the hole f³ into the central channel, thence
through the aperture 2, the annular groove f', and the nozzles to the under side.
of the piston which piston is then raised and the damper opened.
The upward movement of the piston continues until the tension on the spiral
spring T overcomes the pressure on the diaphragm D, when the valve N is raised
until the ports g' and ' are covered, and further movement of the piston is
prevented.
Should the draft in the chimney be suddenly increased by a gust of wind, the
diaphragm falls rapidly, and the valve N being moved down to its lowest position,
the port a comes in alignment with the port g', and through the medium of the
hole d³, water is discharged as before described from the under side of the piston J,
and the damper closed.
As soon as the gust of wind is over the diaphragm rises and water is admitted to
the cylinder to open the damper by means of the ports, holes, and channels before
described.
In some apparatus constructed as above described, I have used in connection
therewith a steam or water motor which is put in operation by the rise of steam
pressure in the boiler to a prearranged height, and which then so influences the
connecting mechanism between the flexible diaphragm which is subjected at its two
sides to the action of the air, and the gases in the combustion chamber and the
damper, that the damper is closed independently of the said diaphragm.
In the present invention, I dispense with such motor and adapt the diaphragm
itself to close the damper. I effect this result by cutting off all communication
between the space under the diaphragm, and the combustion chamber, and opening
the said space to the air. By this arrangement the pressures on the two sides of
the diaphragm are equalized, and the damper is closed by the same means that it
would be if the condition of the fire in the furnace required it.
In carrying out this second part of my invention, I employ a small box A³ in two
parts or sections, a³ and 62 and secure between them a flexible diaphragm B², see
Fig. 7 in which the said box is shown as attached to a seat c² formed as a part of
the valve shell C2 placed in and forming a part of the pipe H. On the diaphragm B²,
I place a loose plate D2 having a central upper projection d' turned to fit in a
guide in the upper section a². E is a lever fulcrummed at f' to a lug g' on the
section a² of the box A2, and between this lever and the top of the plate C³, is a
stem F³, the ends of which are pointed to reduce friction in any movement of the
parts.
A part of the shell C' is adapted as a valve chamber G' and provided with a
valve H which closes in its upward motion, against a seat . The upper end of
the stem k² of the valve H2 passes through an opening m² in the top of the
chamber G which opening is somewhat larger than the stem.
The top of the stem is hinged to the lever E2. I' is a valve on the stem ³ to
close the opening m² when the valve H2 is opened. The lower end of the said
stem is weighted, the weights n³ resting on a plate o into which the stem is
screwed.

page_text: Steam from the boiler is introduced to the lower part a² of the box A² and below
the diaphragm B' by means of a pipe J'.
The weights n² are approximately of such gravity as to be overcome and lifted
when the steam pressure on the under side of the diaphragm B² reaches the pre-
arranged height, and allow the valve H² to be drawn to its seat.
A very close
adjustment of the load on the valve B is, however, effected by the weight K"
adapted to slide on the lever E². All communication between the space under the
diaphragm D Fig. 3 and the combustion chamber being thus cut off by the closing
of the valve H2, and air admitted to the pipe H by the uncovering of the aperture m³,
an equilibrium of pressure on the diaphragm D is established and the damper is
closed, through the operation of the mechanism before described.
As soon
as the pressure in the boiler falls below the maximum limit, the
weight n² again opens the valve H, and the fire in the furnace is again regulated
by the automatic alteration in the position of the chimney damper before
described.
It would be possible to substitute an electric motor for the steam or water one
described, to operate the damper, and in such case the diaphragm stem G would be
required to make and break the electric circuit, instead of actuating the valve N,
and such substitution of electricity for steam or water is within the scope of the
present invention.
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. In combination with a furnace, and a damper which controls the combustion.
of fuel in the furnace, a motor to operate the said damper, a diaphragm one side of
which is exposed to the gases in the said furnace and the other to the air, and
means to connect the said diaphragm to the said motor whereby in the movement
of the said diaphragm consequent upon changes in the relative pressures on the two.
sides thereof, the said motor is either put into operation or stopped, substantially as,
and for the purpose specified.
2. In combination with a furnace, and a damper which controls the combustion
of fuel in the furnace, a steam or water cylinder baving a piston with a rod which
is connected to the said damper, valve mechanism to control the entrance of steam
or water to the said cylinder and to the piston therein, and also the discharge of
steam or water from the said cylinder, and a diaphragm having one side thereof
exposed to the gases in the furnace and the other to the atmosphere, adapted to
operate the said valve mechanism, substantially as, and for the purpose specified.
3. In combination with a furnace, and a damper which controls the combustion
of fuel in the furnace, a water cylinder having a piston therein connected to the
said damper, an arm on the said piston rod with a chain leading therefrom to the
periphery of a pulley, another pulley of smaller diameter attached to the first
having a chain connected by an elastic device to a diaphragm having one side
thereof exposed to the gases in the said furnace and the other to the atmosphere,
valve mechanism to control the entrance of water to, and the discharge of water
from, the said cylinder, and suitable mechanism to convey motion from the said
diaphragm to the said valve mechanism, substantially as, and for the purpose.
specified.
4. In combination with a boiler and a furnace, and a damper which controls the
combustion of fuel in the said furnace, a diaphragm one side of which is exposed to
the gases in the furnace and the other exposed to the atmosphere, connected by
means of suitable mechanism to the said damper, so that its movement influenced
by any change in the relative pressures of the gases and the atmosphere, will
operate the damper, a valve which when closed, cuts off the communicating passage
between the furnace and the said diaphragm, and a steam operated device to close
the said communicating valve, upon the steam pressure in the boiler rising to a
pre-arranged height, the whole operating to close the damper upon the steam

page_text: attaining the maximum pressure, independently of the pressure of the gases in the
furnace, substantially as specified.
5. In combination with a boiler, and a furnace, and a damper which controls the
combustion of fuel in the said furnace, a diaphragm having one side open to the
gases in the furnace by means of a pipe, and the other side exposed to the action of
the atmosphere, a valve situated in the said connecting pipe adapted when closed to
close the said connecting pipe to the gases and open it to the air, a weighted steam
operated diaphragm or valve connected to the said connecting valve, whereby in
the increase of steam pressure in the boiler to a pre-arranged tension, the said
weighted diaphragm is raised, and the connecting valve closed, and an equilibrium
of pressure on the two sides of the said diaphragm established, and the damper
closed, substantially as, and for the purpose specified.
6. In combination with a diaphragm having a space underneath it in com-
munication with the interior of a boiler furnace by means of a pipe, and its upper
surface exposed to the action of the atmosphere, mechanism to communicate the
motion of the diaphragm to the chimney damper, a valve in the said connecting
pipe, a steam operated diaphragm having a weighted lever connected to the
said connecting valve, and an air valve to admit air to the interior of the con-
necting pipe as the connecting valve is closed, whereby upon the steam in the
boiler rising to a pre-arranged height, all communication between the space under
the diaphragm and the interior of the furnace is stopped, and the said space
brought into communication with the air, substantially as, and for the purpose
specified.
Dated thie 25th day of January 1894
GEORGE LANDER THIELL.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.