Improvements in and relating to the Production of Forced Draught in the Furnaces of Steam Boilers.
Year: 1892

page_text: Date of Application, 1st Sept., 1892
Complete Specification Left, 30th June, 1893-Accepted, 5th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Production of Forced Draught
in the Furnaces of Steam Boilers.
We, ARCHIBALD HART MURRAY, and JAMES PATTERSON both of Champfleurie
in the Town and County of Linlithgow, Engineers, do hereby declare the nature of
our invention to be as follows:-
This invention has reference to and comprises new or improved constructions or
arrangements and combinations of the parts and special fittings connected with the
production of forced draught in the furnaces of steam boilers, and particularly
marine boilers, by heated air, and which will also cool or ventilate the stokeholes
of the steamships, and consume or lessen the emission of smoke from the funnels,
and reduce the amount of air heaters, work automatically, and have other
advantages over the means heretofore employed for producing forced draught in
such boilers.
As applied to the furnace of a marine steam boiler the improvements consist in
fitting an air heating box in a chamber formed at the base of the funnel, above the
usual uptake flue or smokebox. This heater would consist of a close box preferably
of cylindrical or rectangular shape having a series of vertical or angled tubes
secured at their ends in the upper and lower end plates of the box and through
which the waste gases from the furnace or furnaces would pass from the uptake
flue to the chimney, part of the gases also passing through a space round the box.
The base chamber below the funnel would be formed of rectangular or cylindrical
plates jointed by upper and lower flanges, so that one end of this chamber can be
detached, and the heater and its fittings removed on slide guide plates or wheels for
repair or otherwise when that is necessary, and the top of this chamber would be
bevelled up to meet and join the flange at the bottom of the funnel, while its lower
flange would be connected by angled or side plates leading down to the top of the
smokebox. The air to be heated would be drawn by a fan or fans from the stoke-
holes or other parts of the ship and forced through a pipe jointed to the one side of
the heater, and the air current would pass round the tubes of the heater and get
its temperature raised by the hot gases passing through said tubes. Or the heater
may be so arranged that the air would pass down through the tubes, and the hot
gases pass up round the tubes. The air thus heated would then pass out through
an exit orifice at the lower part of the opposite side and be conveyed by a vertical
or angled flue or flues heated by the waste gases in the uptake, to the firebox above
each furnace door where a horizontal plate would be fitted, with openings and
valve chambers. There would preferably be four openings and valves in each
front, from the central two of which the hot air would pass by a channel or
channels and be admitted to the furnace at or above the furnace door; while the
air would pass from the end chambers and valves by channels or ducts round cach
side of the furnace box through the dead plate and be admitted inside the closing
ashpit door, which would be fulcrumed or hinged at its upper end to close down
at an angle towards the bottom of the ashpit, and be secured or freed by a single
swivelling haudle and bolt in front, at the lower end. The valves would preferably
be oscillating butterfly valves, each fulcrumed to a fixed spindle at their centre
with levers on each spindle outside the valve box, and these levers would be jointed
to a horizontal rod operated by a hand lever fulcrumed on a centre stud with
eccentric action so as to oscillate and simultaneously open or close all the valves to
regulate and admit heated air to or shut same off from the furnace and ashpit. Or
by removing any of the fulcrum spindles the valve of such can be kept closed or
rendered inoperative. Segmental stops and pins on the levers would be fitted to.

page_text: determine the full open and shut positions of the valves. A fire brick arch would
be erected on the flame-bridge over the exit end of the back furnace flue leading
to the combustion uptake chamber, and be preferably built of two segmental blocks
jointed at the centre and angling and widening outwards beyond the end tube plate
and formed with a series of perforations or holes leading upwards and outwards
through which the heated gases would pass, and be also assisted to impinge on the
back plate of the uptake chamber. And a portable or removable vertical plate
would be fitted in the smokebox uptake in the front end of the boiler to protect
the ends of the stays from getting burnt by the hot ascending gases. A baffle
plate, bonnet, or overhanging cowl of firebrick or other heat resisting material
would be placed in the base of funnel a short distance above the tubular air heater,
being preferably carried on a vertical central hollow stem on and above the heater,
and this baffle plate which would extend to within a few inches of the annular
sides of funnel base would deflect and retard the upward passage of the gases
through the tubular heater, so that the latter may get the maximum amount of
heat from them. And the unconsumed gases would then pass by the annular
passage beyond the baffle plate to the funnel. One or more special vertical tubes
would be fitted in the heater with close bottom ends and extend above the baffle
plate. These tubes would be formed with a series of perforations at their lower
part within the heater for the admission of a portion of heated air from same,
which would be delivered into the funnel flue, above the said fireclay block, where
another small upper central baffle plate would preferably be fitted, so that the
heated air may be deflected and assist the uptake draught and prevent or lessen
the emission of smoke from the funnel. The ends of the ordinary heating tubes in
these forced combustion boilers would be fitted with internal ferrules made from a
compound of ganister, asbestos, porcelain or equivalent heat resisting materials,
and formed of a hollow trumpet or bellmouth shape at their outer extremity
covering the tube ends, so as to protect these from any impinging flames in the
combustion chamber, or from reduction of temperature by the cold air at the
entrance end of furnace when the doors are open and thus assist in preventing
the tubes getting damaged or becoming leaky.
One heater and its fittings will serve for a number of furnaces in single or
double ended return tubular boilers, the heater receiving the heat of the volume of
waste gases from the combined whole, the heater in this case being fitted in funnel
base in the centre over the double boiler, and have the heated air passed by
divisional central and side flues or ducts to the entrance end of each respective set
of furnaces and ashpits. In steam ships with two or more funnels one of our
improved heaters would be fitted in a base chamber below each funnel.
Dated the 31st. August 1802
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in and relating to the Production of Forced Draught
in the Furnaces of Steam Boilers.
We, ARCHIBALD HART MURRAY, and JAMES PATTERSON both of Champ-
fleuric, in the Town and County of Linlithgow, Engineers, do hereby declare
the nature of our invention, and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement in
writing, that is to say :-
This invention has reference to and comprises new or improved constructions or
arrangements and combinations of the parts and special fittings connected with the
production of forced and induced draught in the furnaces of steam boilers, and
particularly marine boilers by heated air, and which will also cool or ventilate the
stokeholds of the steamships, and consume, or lessen the emission of, smoke from

page_text: страх
in such boilers.
And in order that our said invention and the manner of performing or carrying
the same into effect or practice may be properly understood we have hereunto
appended an explanatory sheet of drawings, in which the same reference letters
are used to indicate corresponding parts in all the figures where shown:—
Figure 1 is a sectional elevation showing heater, inducing apparatus, bye-pass
connection with furnaces, funnel rake, engine room and stoke hold combined, as
constructed and arranged in accordance with our improvements.
Figure 2 is a front view of same partly in section.
Figure 3 is a sectional view, showing same, and internal fittings of combustion
chamber. And
Figure 4 is a front view corresponding to Figure 3.
Figure 5 is a plan view of heater, bye pass inducing pipe and pipes from fan.
Figure 6 is a detached sectional view showing the arrangement of the valves at
front of furnaces.
And
Figure 7 is a detached view of the base of funnel, showing the mode of working
when the heater is removed.
In these drawings the arrows indicate the direction of flow of the air currents,
and the darts that of the escaping heating gaseous products of combustion.
Referring to these drawings:-In carrying our improvements into practice as
applied to marine boilers we fit a moveable air heating box A in the base of smoke
funnels of steamships, and supply same with atmospheric air by means of fans or
other suitable blowing apparatus placed in any convenient position. The air is
heated in its passage through the heater A, to the temperature required for com-
bustion and thence is conducted forced and induced into the furnaces and ash pits,
through suitable metal trunk pipes or passages as shown at B B B Figure 1 and B,
Figure 2 and B B, Figure 3 and B, Figure 4 which trunk pipes or passages are
placed within the uptakes of smoke funnel. The forced and induced heated air is
distributed to the furnaces and ash pits, by the main transverse distribution pipes C,
in Figures 1, 2, 3 and 4, such air is then forced and induced through the furnaces
and boiler pipes into and through the uptake D, Figures 1, 2, 3 and 4, and into
and through the heater tubes, and up through and out of the smoke funnel E
Figures 1, 2, 3.
The heater is heated by the passage of the residual heat and waste gases, in
their exit through the heater pipes a and uptakes to the atmosphere.
The heater A is supplied with atmospheric air, by means of a fan, such as is now
in ordinary use, or any suitable blowing apparatus forcing the air into heater
through the passage pipe or trunk F, Figures 1, 3 and 5.
The heater A Figures 1 to 5 is constructed of mild steel or other suitable metal,
and is less in diameter than the base of the funnel and is filled with metallic
vertical tubes a which we prefer to be of 2 or 3 inches diameter the number being
governed by size of heater and the amount of air required for combustion.
The heater A, is preferably formed of circular or diagonal shape, as required,
and space will allow.
The heater rests on two horizontal metal beams G, Figures 1 and 3 which pass
through the chamber H, in base of funnel, the ends of these beams being supported
on the bulk heads, of the fore and after coal bunkers, of stoke hold, the beams
being flush with the bottom of the heater; and a sliding rail 1, Figures 1 and 3 is
riveted to top of beams, with metal lugs K, to bottom of heater secured by metal
cotters or pins to the beams.
.
On these beams G the heater A. is slid out of the heater chamber H when
necessary. A moveable vertical slip plate or valve L, Figure 1, on each side of
heater chamber H is used to shut the air out of the heater chamber when the
bye-pass (hereinafter described) is in use.
The heater when in position is held in place at top by two rolling stays M,

page_text: seaway.
WHICH
Counteracts HULICE reneves the strain on cotter and pins, in a
On top and in the centre of the heater is placed a metallic pipe N, Figures 1, 2, 3
and- 5 which forms the inducing apparatus. This inducing apparatus operates by
permitting a current of air from the fan or blower to pass up through pipe N,
thereby increasing the velocity of the gases in their passage up the funnel 1.
A cowl and sleeve O, Figures 1, 2, and 3 made of refractory material are fitted
around the same for the purpose of retarding the residual heat within the tubes of
the heater, and so producing a higher temperature in the heater. The sleeve and
cowl O, Figures 1 to 3 rest on top of the heater.
When for any purpose it becomes necessary to withdraw the heater from the
heater chamber H a door P, P, Figure 5, constructed for the purpose in the side
of the chamber at base of funnel, may be opened and by means of an ordinary
block and tackle, the heater A may be run out on its supporting beams G, and the
door closed, and while so removed a free and unimpeded passage for smoke and
gases is allowed through the funnel, and a forced draught still maintained through
the bye-pass hereinafter described. A. semicircular bye pass passage or chamber Q,
Figures 1, 2, 3 and 5, is constructed on the outside of the smoke funnel, parallel
with the heater chamber H which connects with chambers B and C, Figures 1, 2, 3
and 5 leading from the heater to the furnace, through which while the heater is
removed for any purpose the heated air is forced by the fan aforesaid, into and
through the passages B and C Figures 1 to 4 inside of the uptake and smoke box.
casings directly into the furnaces and ash pit, thus producing a constant current of
air which insures a combustion nearly equal to that which is obtained while the
heater is in place and use, a slight reduction of temperature and temporary loss of
.induction being the only difference.
1
"
In order to regulate the air to the furnaces and ash pits, through the bye pass Q
and passage or heater, there are placed at the lower part of the passage B, at the
crown of furnace front R, Figures 1 to 4, suitable and adjustable valves S, shown
particularly in detached view Figure 6 by which the air is admitted to furnaces
and ash pits through hollow air passages T, cast in the furnace fronts and which
are regulated as required to suit combustion, and these valves S may be operated
by levers S and a rod S¹ connected to a hand lever so as to simultaneously open or
close all the valves to regulate and admit heated air to or shut same off from the
furnaces and ash pits. The bye pass Q is fitted with a stop valve at Q and the i
pipe F with a corresponding valve at and a portable slip plate valve is fitted
at , with an induction pipe F³ fitted to same, as shown in Figure 7, to maintain
the induced draft up the funnel when the heater is removed.
The passage B to furnaces and ash pits, is constructed of mild steel plates or
other suitable metal.
The furnace fronts U, Figures 1 and 3 project considerably from boiler fronts,
and are connected with the said air passage to furnaces and ash pits.
Under the furnace doors are placed the ash pit doors V, Figures 1, 2, 3 and 4
which are opened when necessary to clean the asli pits, or when the boilers are used
under natural draught.
Above each of the furnace fronts in horizontal pipe passage or trunk B as shown
on Figure 4 small tapped doors B¹ are constructed, in order to obtain access to
valves S when required.
The bye pass Q, Figures 1 to 3 and 5, can when required, be used when the
heater is in position as well. as when removed, and a forced draught be still
maintained.
A fireproof arch, called the convection arch, is placed in the combustion
chambers of marine boilers, as shown at X, on Figure 3, and this arch is capable
of: withstanding intense intermittent heat, and is so placed for the purpose of
circulating the flame around the solid plate surfaces of the water spaces of the
combustion chamber, and thus obtain greater heat from the fuel consumed, and
these arches project considerably into the combustion chamber.

page_text: Fireproof felting or other nonconducting material may be used on outer side of
air trunks, pipes or passages B, Figures 1 to 4 to render them tight and capable of
retaining heat.
The joint of each boiler tube in the tube plate in combustion chamber is pro-
tected from injury by a fireproof ferrule W, Figure 3 which we make of a compound
of fire clay, gannister and plumbago.
These ferrules we prefer to make with a bell mouth extending beyond ends of
tubes into combustion chamber.
The invention above described, can be applied to land boilers, with the same
good result, as in marine boilers.
The heater described in the foregoing Specification may be used on land boilers,
built of any size, and operated in the same manner, as already described by means
of air forced by a fan or other apparatus.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
First. The herein described method of producing combined forced and induced
draught in marine boilers, consisting in fitting a removable heater with air heating
and inducing tubes and deflecting cowls in the base of funnel, and with air passages
leading to furnaces, substantially as set forth.
Second. In a forced draught apparatus for steam boilers the removable heater A
in combination with the air pipe from blower, and the pipe B conveying air to
furnace as herein described and for the purposes set forth.
22
Third. In a forced draught apparatus for steam boilers the "bye pass passage
passing around outside of funnel and forming a connection between pipe, from
blower and pipe B to furnace and fitted with adjustable valves as herein described
and for the purpose set forth.
Fourth. In a forced draught apparatus for steam boilers, the projecting furnace
front having air passages and regulating valves communicating with furnace and
ash pit as herein described and for the purpose specified.
Fifth. In a forced draught apparatus for steam boilers, the cowl placed above
heater and having a metallic pipe passing through it and making a connection into
funnel as herein described and for the purpose specified.
Sixth. In a forced draught apparatus for steam boilers, the convection arch of
refractory material at rear end of furnace and extending into combustion chamber
as herein described and for the purpose specified.
Seventh. In a forced draught apparatus for steam boilers, the tube ferrule of
refractory material in combination with the convection arch, as herein described
and for the purpose set forth.
Eighth. In a forced draught apparatus, the combination of the removeable heater
and the bye pass passage and the furnace front with its controlling valves, and the
cowl and the pipe as herein described and for the purpose specified.
Ninth. In a forced draught apparatus, the combination of the furnace front with
its controlling valves, and the convection arch and tube ferrules as herein described
and for the purpose set forth.
Dated the 29th June 1893