Improvements in and appertaining to Effecting and Maintaining Combustion in Secondary Chambers of Boiler and other Furnaces, and in Apparatus therefor.
Year: 1890

page_text: Date of Application, 21st Oct., 1890-Accepted. 10th Jan.,
1891
COMPLETE SPECIFICATION.
Improvements in and appertaining to Effecting and Maintaining
Combustion in Secondary Chambers of Boiler and other Furnaces,
and in Apparatus therefor.
A communication from abroad by ALLAN MASON, of Brooklyn, Kings County, Now
York, and JOHN WILSON, of New York, in the County and State of New York,
both in the United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street, Manchester both in
the County of Lancaster & 323 High Holborn in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention 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 boiler and other furnaces, in which one or more secondary
combustion chambers are employed with the objects of a more effective application of
the heat than is obtained with a single combustion chamber, and further to supply
sufficient additional fire in the secondary chamber to reheat and reignite the uncon-
sumed gases carried over from the primary chamber at, or as nearly as possible to,
the point where the temperature and heat yielding properties of the said gases
become too low or exhausted for combustion without this additional artificial force,
heat or flame, and by thus consuming the unconsumed gases to maintain the same or
nearly the same temperature in the return flues, so long as the said gases or reinforced
products of combustion, exercise any heating effects on the water or other material to
be heated or vaporized.
The invention is especially designed for the greater and more economical generation
of steam in marine and other boilers through the instrumentality of a secondary com-
bustion chamber at the rear or opposite end from the primary furnace chamber and
communicating with it to receive and consume the unconsumed gases and return the
heat products through the upper portion of the boiler, but it is also designed generally.
for all similar or other furnaces in which secondary combustion may be advan-
tageously utilized. The invention consists of the combination, in a boiler or other
furnace, of a primary combustion chamber and a secondary combustion chamber
respectively located at the extremities of a material part of the heating portion of the
furnace; an injector apparatus furnishing a continuous supply of fuel elements into
said primary chamber; means for continuously supplying fuel elements to the
secondary chamber, and burner apparatus in said secondary chamber; and when
desired for separately supplying it with and burning other and like fuel independently
of the fuel supplied to the primary chamber, as hereinafter fully described, reference
being made to the accompanying drawing which illustrates apparatus suitable for.
carrying the invention into effect.
4
A method will first be described of maintaining combustion in secondary chambers:
by means of hydrocarbon fuel, steam and air, injected into a retort in the primary.
chamber, there expanded vaporized and gasified, and a portion of the resultant com-
bustible products carried into, ignited, and burned in the secondary chamber, reference
being made to the accompanying drawing, Figures 1 and 2:—
Figure 1 is a horizontal section of a boiler furnace, showing an auxiliary fire in the
secondary chamber maintained by the vapor or gas of any hydrocarbon fuel, air, and.
steam generated and combined in a retort in the primary chamber and which also.
supplies the combustibles burned in said primary chamber, and
Figure 2 a longitudinal sectional elevation on line ax of Figure 1.
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page_text: "
fail of complete combustion in the first chamber, it being supposed that, sufficient
room being provided, the heat of the primary chamber would be sufficient for effecting
such combustion, but it is found that such method is a failure practically, although it
may work at times and under some circumstances, but generally the gases are too
much chilled to ensure continuous combustion, and, when extinguished by fall of
temperature or other causes, fail to relight even when considerable increase of
temperature takes place, hence an auxiliary fire in the secondary chamber is found an
imperative necessity for practical efficiency. A fire made by intermittent supplies of
fuel through the ordinary fire door will not do, because, when the door is opened, it
stops the draught in both fires besides admitting cold air in great excess, and therefore
materially interferes with both fires; if a fan blower is used to urge the main fire as
is commonly the case with marine boilers, the door cannot be opened without first
stopping the fan. The fan also interferes with magazine feeders and other automatic
stokers for the auxiliary fire by forcing more or less gas out through them.
This system has been contrived to overcome these difficulties, and to secure a
reliable and uniform auxiliary fire adapted to ensure effectual combustion of the
unconsumed gases from the main fire, and it comprises the continuous and
unobstructed forced supply of the elements of combustion, to the continually closed
secondary chamber in addition to the gases entering it from the main furnace, and in
such manner as to accelerate the natural draught of the main furnace, and to
be alike available with a forced draught thereto; the arrangement being such that the
same is controllable at the front where the main fire is tended, so that the apparatus
is applicable to and detachable from ordinary furnaces constructed with secondary
chamber without change or permanent attachment.
The apparatus which it is preferable to use is substantially as follows:-
In the boiler furnace represented in the drawing, a indicates the main or primary
combustion chamber and 6, the secondary chamber, both having the customary fire
door and the usual system of fire tubes e, communicating between them, and also
the return system of tubes f, connecting the secondary chamber with the smoke flue g.
In this example a retort k, is shown located in the first combustion chamber with oil,
steam and air inlets h, i, and j, to more effectually combine, vaporize and gasify the
several elements by causing them to mix therein and together traverse the retort
which is a pipe suitably coiled and made to discharge rearwardly from the furnace
door or thereabouts.
With the retort k, for combining and gasifying the elements consisting of oil,
steam and air, to be employed in the main furnace, will be employed gas burners t, in
the secondary furnace with a branch or branches w, of the retort extending through
one or more of the fire tubes into it and supplying the burners t, with gas generated
in said retort which also supplies the main chamber a, with its fuel through the
issue j', and thus enables both fires to be fed by one set of injector apparatus by a
simple contrivance of the same; but a separate retort may be employed with each
chamber, if desired.
Another application of the invention consists in maintaining a fire in the primary
chamber either by injecting fuel elements as oil steam and air into the said chamber,
or by an ordinary coal fire, and by a separate injecting apparatus, injecting a con-
tinuous forced supply of other fuel elements as oil or comminuted coal or both, to the
secondary chamber, and by burning them therein with or without an auxiliary fire of
coal, maintaining combustion in the secondary chamber. Apparatus suitable for
carrying this application of the invention into effect is illustrated in Figures 3 to 6
of the accompanying drawing..
Figure 3 is a longitudinal sectional elevation of a boiler furnace showing the
application of an auxiliary hydrocarbon fire in the secondary combustion chamber
for effectual combustion of the gases entering said chamber from the front or primary
chamber in which, in this instance, is represented apparatus for the use of hydro-
carbon fuel and steam.
Figure 4 a horizontal section of a similar furnace in which the auxiliary fire of

page_text: the secondary chamber is supported in part by hydrocarbon fuel and in part by coal
slack, pulverized coal or culm, both introduced with air, the fire in the front furnace
being of coal or other fuel as preferred.
Figure 5 a longitudinal sectional elevation of a similar furnace, in which the
auxiliary fire in the secondary chamber is maintained with coal slack, pulverized coal
or culm, blown in and burned on a coal fire, which, being an ordinary fire made on
a coal grate to begin with, is subsequently maintained and continued by the supply of
coal slack, pulverized coal or culm, the fire in the front furnace being produced in
this instance with hydrocarbon fuel injected with steam and air.
Figure 6 is a top view of a burner for oil on an enlarged scale.
The apparatus which it is preferred to use is available to some extent at the option
of the constructor and for different forms of the combustibles to be used, but what is
claimed is substantially as follows,
In the boiler furnace represented in the drawing, a indicates the main or primary
combustion chamber, and 6, the secondary chamber both having the customary fire
door C, and ash pit door d, with the usual system of fire tubes e, communicating
between them, also the return system of tubes f, connecting the secondary chamber
with the smoke flue g.
In Figures 3 and 5, is represented an injecting apparatus for the use of oil, steam
and air, for combustion in the main furnace; h, being a steam nozzle, i an air inlet
funnel and an oil feeding tube, one or more of the latter being used to deliver oil
on the upper surface of the steam nozzle which may have a groove or grooves to
conduct the oil off the end of the nozzle suitably to mix and atomize or vaporize with
the steam and air, the steam nozzle to be suitably connected with the boiler, and the
oil pipe or pipes to be connected with any source of supply with suitable regulating
cocks or other devices and all being suitably connected with the furnace through the
fire door of the first couibustion chamber.
With this method of producing combustion in the main chamber a an auxiliary
fire is provided for in the secondary chamber b, by a series of oil burners n, supplied
with oil and air through the ash pit and one or more of the fire tubes e, by the pipes o,
and I, and any approved means of igniting them with which may also be burned coal
slack to be forced in through a pipe or pipes m, by a fan p, or other means or the
coal slack may be used with an ordinary coal fire q to begin with, and be afterwards
maintained by the injected coal slack, pulverized coal, or culm alone.
The advantages of these systems of maintaining combustion in secondary
combustion chambers may be summarized as follows;
It is well known that, as the products of combustion from the main chamber pass
along the flues or other passages of a furnace, their heating effects decrease as they
proceed the decrease being caused by radiation, exhaustion condensation, etcetera.
The object is to maintain approximately the same temperature throughout all the
flues and passages, and this is effected by supplying sufficient flame by means of an
auxiliary fire of coal, oil, etcetera (burned separately or in combination in any suitable
form or manner that may be deemed desirable) to ignite and reinforce the gases and
products of combustion at or as nearly as possible at the point of exhaustion.
An equal temperature is thus kept up about every part of the boiler and thus con-
densation of the steam, etcetera, are prevented on its way from the initial contact
with or exposure to the heat to the point most remote therefrom. These methods and
apparatus are such that while producing more uniform heat and apparently not
admitting of any neutral point, foaming by the upward rush of unvaporized material
is prevented. By these means too the water etcetera are vaporized so much more rapidly,
and so much less heat is required in the primary chamber that a great saving of
time and fuel is effected and wear of the exposed surface of the boiler is prevented.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. The improved method of effecting secondary combustion in a boiler or other

page_text: furnace through the instrumentality of an auxiliary fire in a secondary combustion
chamber which consists of injecting oil, air and steam into a pipe retort located in
and subject to the heat of the primary furnace chamber, passing the same
unobstructedly along and mixing, expanding, vaporizing and gasifying them therein
and discharging the resultant products partly and preferably mainly in the primary
chamber and partly in said secondary chamber substantially as described.
2. The combination in a boiler or other furnace of the primary combustion chamber
and the secondary combustion chamber respectively located at the extremities of a
material part of the heating portion of the furnace, injector apparatus furnishing a
continuous supply of fuel elements as oil, steam and air into said primary chamber,
separate injector apparatus of fuel elements as oil or comminuted coal to the secondary
chamber and burner apparatus in said secondary chamber separately supplied with
and burning other or like fuel independently of the fuel supplied to the primary
chamber, substantially as described.
3. The improved method of producing and utilizing heat in a boiler or other like
furnace consisting of producing a fire in the ordinary furnace chamber, introducing
the heated products thereof into a locally separate secondary combustion chamber of
said boiler or other furnace and separately introducing and burning therein a con-
tinuous forced supply of other fuel elements in combination with the products from
the primary chamber after being partially cooled while passing from the primary
to the secondary chamber substantially as described.
Dated this 20th day of October 1890
WM. P. THOMPSON & Co.,
Agents for the Applicant.