Improvements in Smoke Consuming Furnaces for Boilers and for Air Heating Stoves.
Year: 1895

page_text: Date of Application, 1st June, 1895-Accepted, 6th July, 1805
COMPLETE SPECIFICATION.
Improvements in Smoke Consuming Furnaces for Boilers and for
Air Heating Stoves.
I, SAMUEL CLELAND DAVIDSON of Sirocco Engineering Works, Belfast,
Ireland, Merchant, do hereby declare, the nature of the said invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
This invention has reference to smoke consuming furnaces for boilers and for
air beating stoves wherein the heating of the. air is effected by admixture of the
products of combustion from the furnace.
The improvements consist in the construction of a brick lined or brick built
furnace with a number of fresh air inlet jets or orifices along the sides of the
fire consisting of nietal tubes attached to part of the metal framework enclosing
the brickwork and son arranged. that the air is delivered in jets at about 4 or
5 inches above and across; the surface: of the fuel burning therein whereby this
air gets thoroughly mixed with. the unconsumed hot gases arising from the fire
and as the air thus admitted is considerably heated in passing through these
tubes which from their position: get very hot it. readily combines with the said
gases and so completely effects their combustion that the smoke is very thoroughly
consumed: After this in the case of the boilers: the products of combustion play
against the underside of a boiler which. is preferably set so as to form the top
of the furnace, and the products of combustion after passing along the same to
its further end return through tubular flues extending from end to end of the
boiler and from thence to the chimney or in the case of what is termed water
tube boilers: amongst the tubes a considérable portion of which may be directly
over the fire and thence to the chimney.
In the case of air heating furnaces it is not so important as with boilers to keep
the products of combustion at a maximum high temperature, and a considerable
reduction in temperature of the same by a further additional dilution with fresh air
is usually more advantageous than otherwise. The furnace for this purpose is
therefore preferably arched over with firebrick above the level of the air inlet jets
at the sides, and in the upper part or crown of this arch a sufficient number of
hollow or perforated fire bricks are so built in that the products of combustion can
freely pass up through the same from the arched over furnace to another
preferably firebrick arched flue on the top! of the same through. each side of which
Alue another series of air inlet tubes or orifices are arranged to admit a further or
second supply of fresh air from the atmosphere: in the form of jets so as to
thoroughly mix with the upflowing jets of products of combustion from the furnace
below.. Complete combustion of any smoke. which may still be imperfectly con-
sumed will thus, be so thoroughly effected that when the fire gases. subsequently
pass from this, upper flue they should be perfectly free from the presence of smoke.
On their reaching the end of this upper flue they are admitted by an adjustable
door or slide damper into a flue through: which a separate supply of cold air is
being drawn by a fan or other air propelling device and the hot smokeless products
of combustion on mixing, therewith more or less heat up this air current according
to the relative volume of hot gases admitted: thereto through the adjustable door
or valve in the top or second combustion: chamber of the furnace. On- the top of
this second or top combustion chamber a chimney is constructed with a damper
valve in it which is intended to let away the smoke from the furnace when the fire
is being lighted up at the start and before the furuace has got sufficiently heated

page_text: up to cause the gases of the fuel to ignite with the fresh air jets from the sides, as
until this is the case more or less smoke accompanies the products of combustion ;
but when the sides and arched roof of the furnace and top flue have got sufficiently
hot to promicte the ignition of the gases the smoke is consumed so completely that
the products of combustion are then practically free from smoke and are then
suitable for admixture with air to raise its temperature for drying or other
purposes where admixture of comparatively smokeless gases from the furnace
having no detrimental effect on the material being dried or treated, such as in the
case of the drying of grain, bricks &c.
The accompanying drawings fully illustrate the manner in which the invention
is carried into effect.
Figures 1 to 4 illustrate the manner in which the invention can be carried into
effect in the case of an outside fired boiler in which the products of combustion
after leaving the furnace and passing along the bottom of the boiler return through
tubes which extend from end to end of the boiler and thence to the chimney.
Figure is a sectional elevation of the boiler and furnace, Figure 2 a cross
section taken through line 22 of Figure 1. Figure 3 is a plan and Figure 4 a
front elevation of the boiler complete.
A is the furnace or fireplace and B the fire bars. CC are metal tubes
ranged along each side of the fire and constituting air inlet orifices or jets for the
purpose of admitting fresh air into the furnace. These tubes C C are attached to
the cross bars P P which are part of the metal framework enclosing the brickwork.
The unconsumed hot gases arising from the fire get thoroughly mixed with air
issuing from the inlet tubes or orifices C C. This air is. considerably heated in
passing through the tubes or orifices CC which from their position in the furnace
of the boiler get very hot; consequently the air being already heated readily
combines with and effects the almost complete combustion of the hot gases from
the fire. The products of combustion then pass along the underside of the boiler
or drum R (which in this case forms the top or roof of the furnace A), enter the
tubes S S at the end of the drum R and pass through the same to the smoke box T
and thence to the chimney H. N N are pillars or upright columns to which are bolted
the front plates O O, the cross bars P and P1 (P carrying the air inlet tubes C C)
the end tie bar Q, the cover piates U U and the upper end bars or beams V V.
The drum R rests upon the end bars or beams V V by having suitably formed
plates W W fixed across its ends outside the bars or beams V V; they thus not
only support the drum R, but form a complete framing or binding for the outer
walls of the furnace. X is a trap or mud pocket for collecting any sediment which
may deposit in the inside of the drum and which may be blown off at intervals
through the blow off cock Y.
Figures 5 to 8 are views of a smoke consuming furnace in which the products of
combustion are first supplied with jets of fresh air to effect combustion in the
furnace and after passing from the furnace are further nixed with a second supply
of fresh air to complete combustion and are then passed, together with a further
supply of cold air by means of a fan or other air propelling device to the place
where the mixture of heated air and products of combustion is to be utilized for
drying or other purposes.
Figure 5 is a sectional elevation of the smoke consuming furnace, Figure 6 a
cross section taken through line 6 6 of Figure 5, Figure 7 a sectional plan taken
through line 77 of Figure 5 and Figure 8 a front elevation of the furnace.
A is the furnace or fireplace and B the firebars. CC are fresh air inlet tubes
or orifices formed along the sides of and admitting fresh air into the furnace. D is
a firebrick arch thrown across the furnace in the crown of which are a number of
holes or perforations E E to allow the products of combustion to pass freely
through into an arched flue F constructed with a damper G at one end. Through
each side of this fiue another series of air inlet tubes or orifices C' is arranged to
admit a further supply of fresh air to mix with the products of combustion. His
a smoke chimney mounted on the top of the flue F and constructed with a damper

page_text: valve J which is intended to be kept open only during the lighting up of the
fire to take away the smoke until the furnace gets sufficiently heated up to cause
the fuel gases to ignite with the fresh air jets and the quantity of smoke is
reduced to practically nothing. The valve J is then closed and the damper G
opened. The products of combustion then pass into a flue K through the inlet
opening L of which a separate supply of cold air is being passed to the outlet
opening M. This separate supply of cold air becomes mixed with the products of
combustion and gets more or less heated up according to the volume of hot gases
admitted through the damper G. The heated current of air and products of
combustion then passes through the opening M to the material to be dried. The
arrows indicate the flow of the current of cold air and the products of combustion
from the furnace. The framing or binding of the outer walls of the furnace is
carried out in a manuer similar to that shown in Figures 1 to 4, N N being the
pillars or upright columns to which are bolted the front plates OO of the furnace,
the cross bars P P carrying the air inlet tubes CC; the end bars QQ are also
bolted to the pillars N N thus forming a complete frame or binding for the outer
walls of the furnace.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed 1 declare that what I
claim is :-
1. In brick lined or brick built furnaces for air heating stoves or for boilers,
a series of air inlet orifices or jets along the sides and slightly above the surface
of the fire, and consisting of metal tubes attached to part of the metal framework
that encloses the brickwork to admit fresh and heated air immediately over the
fire to effect the combustion of the smoke and gases arising from the fire,
substantially as hereinbefore described and represented in the accompanying
drawings.
2. In brick lined or brick built furnaces for heating air by the direct admixture
therewith of the hot products of combustion free of smoke from a fire furnace,
a series of air inlet orifices or jets to admit fresh and heated air immediately over
the fire as referred to in Claim 1, in combination with a second combustion
chamber or flue into which the products of combustion from the fire furnace are
guided or directed and with a second series of air inlet orifices or jets to admit a
further supply of air to the second combustion chamber or flue whereby the com-
bustion of any smoke or gases that escape unconsumed from the primary furnace
chamber is completely effected before the products of combustion pass on to
become mixed with and heat a current of air, substantially as hereinbefore
described and represented in the accompanying drawings.
3. In brick lined or brick built furnaces for heating air by the direct admixture
therewith of the hot products of combustion free of smoke from a fire furnace, the
combination with the fireplace of a series of inlets to admit fresh and heated air
immediately over the fire, a second combustion chamber or flue into which the
products of combustion pass through holes provided for the purpose from the first
combustion chamber, a series of inlets to admit air to the second combustion
chamber or flue, a third chamber or flue into which the products of combustion
pass through an adjustable opening from the second chamber or flue, an inlet for
air to the third chamber or flue which air mixes with and becomes heated by the
products of combustion, and an outlet for the mixture of heated air and products
of combustion from the third chamber or flue, all substantially as and for the
purpose hereinbefore described and represented in the accompanying drawings.
Dated this 1st day of June 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.