Appala Boilers.
Year: 1885

page_text: Appala
Boilers.
WILLIAM HUTCHINSON Steel Works Manager, Millfield House, Ettingshall,
Wolverhampton, and CHRISTOPHER THOMPSON Engineer, 9 Elmwood Street
Sunderland Co Durham do hereby declare the nature of our invention for
CONTROLLING THE DRAUGHT OF FIRING BOILERS and in what manner the same is
to be performed, to be particularly described and ascertained in and by the.
following statement:―
The invention relates to applying the action of furnace doors of firing Boilers,
when opening and shutting to give motion to levers, rods, and chains for moving
dampers to control and regulate the current of air to the furnace and through the
flues of firing Boilers. In almost all firing boilers where stoking or firing is being
done by hand and where the furnace doors open for the admission of fuel, a large
volume of cold air rushes in as soon as the doors are opened which rapidly cools
the highly heated surfaces of the furnace tube and combustion chamber and the
tubes and surfaces of the Boiler round their sides and bottom flues also the
economiser and main culvert on its way to the chimney.
The cold air acting on the highly heated furnace flue causes the plates to contract,
causing a very great strain at the joints, and starting the tube to leak. The
alternate expansion and contraction of the flue by the beating and cooling causes
the plates to crack across the rivet holes, weakens the tube, effects considerable.
destruction and endangers the safety of the boiler.
A considerable amount of fuel is lost or wasted when the furnace doors are open,
the cold air rushes in, carries away the gases uncombined to the chimney, filling
the flues and passages, through the economiser with soot and making much smoke,
besides lowering the temperature in the flues which further retards combustion,
when the doors are shut, and by this loss of heat, the force of the draught is
considerably reduced.
From 1500 to 2500 cubic feet of cold air per minute rushes through the doorway
of the furnace of an ordinary Lancashire Boiler when the doors are opened for
stoking and a further quantity will pass up through between the fire Bars during
the process of cleaning the grate. This enormous quantity of air carries off an
equivalent of heat, equal to the difference between the atmosphere and the flue,
which loss means the loss of a large quantity of fuel.
The object of this invention is to apply the action of the furnace door when
opening or shutting to give communication to levers Rods, chains or springs to

page_text: dampers, that will close and shut off the draught when the furnace door is being
opened and prevent the cold air rushing through the flues and to open and admit
the circulation of hot gases when the doors are being closed thereby preventing the
serious loss of fuel and the destruction to the Boiler flues.
There are several ways in which the said action of furnace door in opening and
shutting may be employed to give motion to dampers and several methods and
positions in which the damper may be placed to work by the said action some of
which are shewn on the accompanying drawings.
Drawing No 1 shews the motion of doors applied to dampers in different forms
and positions and different form of Boilers.
Fig. No 1 shews elevation of part of a battery of firing Boilers one part in
section and with front wall removed shewing position of damper.
The arrow shewing the line of current of gases round the boiler passing through
damper to flue underneath the boiler when damper is open, and with front of
furnace in position shewing connections with door to damper when door is shut
also lever and connection to door and damper when door is open.
Fig. No 2 is a side view of part of Boiler with wall removed and shewing
damper A.
Fig. No 3 is a plan with part of boiler removed shewing damper A.
Fig. N° 5 is the front elevation of a single flued firing boiler and Fig. No 4 plan
of same the damper A is shewn in this case to be placed in the flue at the back
extreme end of the boiler the damper being of simple wing type turning on a
central vertical pivot the motion from the door to the damper being through levers
and chains on the top of damper spindle which comes up through the brickwork is
fixed a chain pulley with a small chain passing round it one end leading round
another pulley to a lever on a vertical spindle at one side in front of the Boiler,
and another lever connects with rod to a joint on the furnace door, the other end
of the chain passes over a small pulley, with a small weight (W) at the end
serving the purpose of keeping the chain tight between the lever and pulley when
the furnace door is being opened which gives motion to the lever and allows the
weight to draw forward the chain which gives motion to the damper and closes
the aperture, and on shutting the door the lever draws the chain back and turns
the damper open to allow the gases to pass on to the chimney.
Drawing No 2 shews the dampers placed in the main tubes near the exit and
motion given to it by rod passing under the fire grate through stop wall of the
bridge and coupled to joint on damper, the other end of rod coupled to lever which
receives motion from attachment on the door when opening and closing the damper
and like the other can be regulated to open a portion of the stroke or can be
detached at any time and used as an ordinary damper.
Fig. N° 6 is the front elevation of half a boiler.
Fig. No 7 is a section through tube shewing position of damper A full open.
Fig. N° 8 shews plan in part section one tube with damper full open and furnace
door shut, and the other tube with door open, and damper shut.
Drawing No 3 shews a very simple method of arranging and fixing the dampers
to firing boilers and an efficient method of communicating motion to them from the
action of the door and also for being very ready and handy for the use of the
attendant for opening and closing to increase or diminish the action of the draught
which may be done immediately and without disarranging the motion in connection
with the door.
Fig. No 9 is the front elevation of an ordinary Lancashire Boiler with the right
hand furnace door open with levers in position part of the front wall removed
shewing position of damper frame with the damper shut. The left hand tube
shows the furnace door shut with portion of brickwork removed, shewing the
damper full open.
Fig. N° 10 is a side elevation of part of front end of boiler with part of side
wall removed shewing the damper frame as being a portion of the boiler supports
and with the damper full open.

page_text: Drawing No 4 shews details of damper gear on large scale which will readily be
understood.
Fig. No 11 is a block which is secured in the brickwork by side of the Boiler
with a lever B working on a pin G secured in the block, the lever B is bored at
right angles to receive a double motion joint piece C the other end of lever receives
an ordinary joint & rod to connect with lever K on the spindle of damper A the
double joint is fitted with a small block with square hole through it to receive
rod D of an easy fit to slide freely, the rod is hinged at one end to the furnace
door by an ordinary joint of a loose fit 2 stop blocks E & F with thumb screws
are secured on rod D on each side of joint block C a short connecting red H with
an ordinary joint at each end connects lever B and lever K on damper spindle M.
N is a block built in the wall to support the end of the spindle which is connected
to lever K. A is the damper which is supported on a spindle and enclosed in a
frame, the damper being made rather longer on one side of the axis than the other
causing it to have a heavy side, this side being fixed downwards causes the damper
when free to remain in this position which is the position when closed, when the
furnace door is shut as shewn on drawing N° 3 and Fig. N° 9 the damper is full
open.
The block E is secured by the thumbscrew on rod D close up to block in double
joint C which keeps the damper open the damper being rather heavier on the long
side keeps the double joints up to the block E and when the door opens motion is
given to rod D which moves towards the lever and allows the damper to turn on
its axis and shut.
In case of any interruption with the damper which is nearly balanced the
block F with thumbscrew is secured on the bar D on the opposite side of double
joint presses on the lever and closes the damper after the door has been open a
few inches.
The blocks E & F can be secured on the rod D in any position to allow the
damper being kept shut, till the doors is nearly closed.
The holes in the quadrant on block for lever B are to receive a pin which
answers as a stop when required and for regulating the amount of opening that is
required at any time so that the damper can be regulated without trouble to close
within an inch if necessary or remain full open when the doors are open or when
the doors are shut a light circulation of air is necessary sometimes when cleaning
the fire grate to carry off the dust when the furnace door is open which can be got
by placing the pin in the proper hole in the quadrant.
This arrangement of damper can be applied to any double flued firing boiler in
present use at a very small cost.
Having now particularly described and ascertained the nature of our invention
and in what manner the same may be performed we declare that what we
claim is
1st The application of the action of furnace doors of Firing Boilers when being
open or shut to give motion to levers, rods, springs or chains for opening or closing
dampers in their tubes or flues and
2nd For the arrangement of dampers with their mode of communicating the
motion as shewn on the accompanying drawings and as further described herein.
Dated this 17th day of December 1885
WILLIAM HUTCHINSON.
CHRISTOPHER THOMPSON.