IMPROVEMENTS IN OR APPLICABLE TO STEAM GENERATORS
Year: 1881

page_text: LETTERS PATENT to Seth Dawson and James Dawson, both of Mossley, in
the County of Chester, Engineers, for an Invention of "IMPROVEMENTS IN OR
APPLICABLE TO STEAM GENERATORS."
PROVISIONAL SPECIFICATION left by the said Seth Dawson and James
Dawson at the Office of the Commissioners of Patents on the 8th January
1881.
SETH DAWSON and JAMES DAWSON, both of Mossley, in the County of Chester,
Engineers. "IMPROVEMENTS IN OR APPLICABLE TO STEAM GENERATORS."
Our Invention relates to boilers or steam generators of the class having internal
flues, and has for its object to promote a more perfect combustion of the fuel or of
the products thereof, and thereby to prevent or lessen the emmission of smoke, and
at the same time to increase the practical efficiency of the boilers as generators of
steam. When applying our Invention, say, for example, to a Lancashire," boiler
we mount a cylindrical water heater within each flué. Each water heater is less
in diameter than the flue to a suitable extent, so that an annular space for the
passage of the gases from the furnace is left between the exterior of the heater
and the inner surface of the flue. The said heater extends from the rear end of the
boiler or thereabouts to within such a distance from the bridge as that there shall
be a space to serve as a combustion chamber between the end of the heater and
the bridge. The heater may be either concentric or excentric in disposition with
relation to the flue. Within the heater is a passage for the flow of air. Air is
conveyed to the rear end of the heater by means of a pipe which extends through
the boiler seating. When the boiler is at work a current of air is drawn in
through the said pipe, and flowing through the said passage issues into the com-
bustion chamber, and meeting with the gases flowing over the bridge aids in
effecting their combustion. We prefer to apply a self-acting valve or regulartor
to the air pipe. In one arrangement we connect the regulartor valve or damper
with the furnace door in such a manner as that when the door is opened to fire
the furnace the said regulator is opened to admit air. The closing of the regulator
ID 31

page_text: is gradually effected by means of a ratchet-wheel, which is actuated by means of
a lever and pawl which receives motion from the engine. If preferred the regu-
lator may be opened by hand, and also any other suitable self-acting regulator
may be employed. We may extend the air pipe through the heater, leaving
space for the flow of heated gases through the passage in the heater, so that the
air would be highly heated in its progress to the combustion chamber, and in some
cases we may apply more than one air pipe to a single heater. The said heater is
connected with the economiser or with the pipe conveying the feed water and also
with the boiler, so that the feed water is caused to flow through the heater on its
way to the interior of the boiler. We prefer to connect the front end of the heater
with the stop valve on the feed pipe at the front of the boiler. In some cases the
arrangement may be used without the air inlet pipe or pipes, the heated gases
flowing through the passage in the heater.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Seth Dawson and James Dawson in the Great Seal Patent Office
on the 8th July 1881.
SETH DAWSON and JAMES DAWSON, both of Mossley, in the County of Chester,
Engineers. "IMPROVEMENTS IN OR APPLICABLE TO STEAM GENERATORS."
Our Invention relates to boilers or steam generators of the class having internal
flues, and has for its object to promote a more perfect combustion of the fuel or of
the products thereof, and thereby to prevent or lessen the emission of smoke, and
at the same time to increase the practical efficiency of the boilers as generators of
steam. When applying our Invention, say, for example, to a "Lancashire" boiler,
we mount a cylindrical water heater within each flue. Each water heater is less
in diameter than the flue to a suitable extent, so that an annular space for the
passage of the gases from the furnace is left between the exterior of the heater and
the inner surface of the flue. The said heater extends from the rear end of the
boiler or thereabouts to within such a distance from the bridge as that there shall
be a space to serve as a combustion chamber between the end of the heater and
the bridge. The heater may be either concentric or excentric in disposition with
relation to the flue. Within the heater is a passage for the flow of air. Air is
conveyed to the rear end of the heater by means of a pipe which extends through
the boiler seating. When the boiler is at work a current of air is drawn in through
the said pipe, and flowing through the said passage issues into the combustion
chamber, and meeting with the gases flowing over the bridge aids in effecting their
combustion. We prefer to apply a self-acting valve or regulator to the air pipe.
The said heater is connected with the economiser or with the pipe conveying the
feed water, and also with the boiler, so that the feed water is caused to flow through
the heater on its way to the interior of the boiler.

page_text: In order that our Invention may be fully understood we have attached hereunto'
a Drawing made to a scale of about three quarters of an inch to the foot, and
marked with letters of reference, the said Drawing representing a vertical longi-
tudinal section of a steam generator having our Invention applied thereto. In the
said Drawing a is the ordinary internal flue of a "Cornish" boiler, or it may be
one of the flues of a boiler of the ordinary "Lancashire" type; b is the furnace,
and c is the bridge. Within the portion of the flue a which extends from the
bridge to the rear end of the boiler we mount the cylindrical water heater d. The
said heater consists of a cylindrical shell & provided with annular shaped ends d¹,
in which are fixed the two ends of an inner tube or air flue e. The said heater is
mounted upon blocks which rest upon the lower sides of the flue a, so as to leave
the space immediately below the heater free from obstruction, or is otherwise
suitably mounted or secured in position. In the example the heater is represented
as being concentric with the flue, but if considered to be more advantageous the
heater may be nearer the top or the bottom of the flue. It will be seen that the
space left between the exterior of the heater and the flue is annular in cross section,
and is greatly restricted as compared with the ordinary open flue, so that the draft
through the flue will be much intensified, and also the flames and the intensely
heated gases will be caused to extend lower down the flue instead of flowing only
in contact with the crown of the flue as is usual. We are thus enabled to increase
the practical efficiency of the internal flue as a heat absorbing medium. We expect
that the intensified draft will in most cases be sufficient to prevent the accumu-
lation of soot or dust to any great extent in the lower part of the flue, but in order
to provide for the removal of such accumulations we have provided a rake f, which
can be pushed forwards below the heater by means of a rod g, so that the soot or
dust can be propelled out of the flue. Any suitable method for clearing the flue
may be adopted in lieu of the one indicated. The rear end of the air flue e is
connected with an elbow pipe h, which extends upwards through the back flue.
A current of air is inducted into the said pipe by the draught, and flowing through
the air flue in the direction indicated by the arrows passes out of the front end of
the said air flue, and meets the gases immediately after their passage over the bridge,
and aids in effecting their combustion, thereby preventing or lessening the formation
or emission of smoke. Above the inlet mouth of the air pipe h is suspended a cone i.
which is carried by one arm of a lever k, which is mounted upon a fulcrum at l.
The other arm of the said lever is connected with a piston which is contained in a
regulator cylinder m. The said piston is so suitably fitted or provided with passages
and a valve or valves as that it is capable of moving quickly in one direction, but
is caused to move slowly in the other direction, as in the case of similar apparatus
employed to regulate the closing of dampers or air passages. Upon the fulcrum of
the lever is mounted a second lever m which is connected by means of a rod and
lever o with a vertical shaft p which is attached to the hinge pin of the furnace
door, or of one of the doors, or to the door in such a manner as that when the door
is opened for firing, the said shaft is caused to turn upon its axis, and thereby to
move the lever n in the indicated direction. When so moved a stud upon the
lever n transmits the movement to the lever k, and the cone i is thereby raised,
whereby the mouth of the pipe h is opened for the inlet of air. When the furnace
door is closed the lever n leaves the lever k, and the regulator m permits the cone
to be slowly lowered until the mouth of the pipe h is again closed, as will be well
understood. Any other suitable apparatus may be employed to control the
lowering of the said cone or to otherwise effect the slow closing of the air inlet
opening, or the inlet of air may be regulated by hand. We may convey the air
from the pipe h to the front end of the water heater through a pipe which would
be mounted within a flue in the heater in such a manner as that a portion of the
heated gases from the furnace would flow through the heater and outside the said
air pipe, whereby the air would be delivered at the front end of the heater in a
ighly heated condition, and would in consequence be more efficient in its action as
promoter of combustion; and also we may convey the air through more than

page_text: one pipe or passage extending through the heater. The water heater is connected
with the boiler in any suitable manner. In the example a pipe r which is
connected with the front end of the heater passes through the space below the fire
bars, and is connected at 8 with the stop valve or pipe which conveys the water
into the boiler. An inlet pipe t conveys the feed water from the economiser or
from the feed pump or feed apparatus as the case may be. In some cases we may
dispense with the air supply pipe h and permit the flames and gases from the
furnace to flow partly through the passage or flue e, or through two or more flues
or tubes substituted therefor, and partly through the space between the exterior of
the heater and the shell of the internal flue of the steam generator.
Having now fully set forth and indicated the nature of our said Invention and the
manner in which we carry or propose to carry the same into practical effect, we
would have it to be understood in conclusion that we claim,―
First. The combination of parts forming the apparatus applied to a steam
generator to heat the feed water and promote the combustion of the gases
generated in the furnace, substantially as set forth and indicated hereinbefore, and
in and by the accompanying Drawing.
Secondly. The water heater mounted within the back internal flue, and the
passage or passages conveying air to the front end of the said heater, substantially
as and for the purpose or purposes set forth and indicated.
And, Lastly. The water heater formed with a passage or with passages for the
flow of air or gases, and mounted within the back internal flue of a steam generator,
substantially as set forth and indicated.
In witness whereof, we, the said Seth Dawson and James Dawson, have
hereunto set our hands and seal, this Sixth day of July, in the year of our
Lord One thousand eight hundred and eighty one.
Signed, sealed, and delivered in
the presence of
EDWARD K. DUTTON,
41, John Dalton St.,
Manchester.
(Agent for the Patentees).
(L.S.)
SETH DAWSON.
JAMES DAWSON. (L.S.)