Year: 1887

page_text: Date of Application, 16th Nov., 1887
Complete Specification Left, 17th Sept., 1888
Complete Specification Accepted, 16th Nov., 1888
I, THOMAS SNOWDON, of 91, Guildford Street, in the county of Middlesex, Engineer
do hereby declare the nature of this invention to be as follows:-
This invention has for object to ensure efficient combustion of fuel and utilisation
of the heat produced in steam boiler and other furnaces, whether worked by natural
or forced draught.
According to this invention, air is admitted to the combustion chamber through
hollow fire bars, the inner ends of which are carried by a support preferably in the
form of a water box or trough which is provided with means for supplying and
maintaining a constant height of water therein. This water box serves, together with
the air passing through the fire bars, to prevent these parts becoming excessively
heated. The hollow fire bars-which, in some cases, may be arranged in an inclined
attitude-may be in communication at their outer ends with an air box or chamber,
the upper part of which may, in some cases, form a dead plate. A fire bridge or
bridges may,
in some cases, be employed at the rear end of the fire bars. An adjust-
able sliding diaphragm is arranged below the fire bars, and the exit areas above and
below the fire bars for flame and products of combustion to the combustion chamber
are preferably so proportioned that air after passing upward through the fuel from
the front portion of the ash-pit, wholly or partially descends through the fuel at the
rear portion of the fire grate, and escapes below the fire bar support or trough. An
air tube or passage may be arranged below the fire bars for admitting an additional
supply of air to the lower part of the combustion chamber, such air aiding in effecting
the downward passage of the air and products of combustion through the fuel on
the rear portion of the fire grate. In the case of tubular boilers such as marine
boilers-baffle plates or dampers may be arranged at the smoke box end of the tubes
for the purpose of retarding the hot gases and products of combustion and thereby

page_text: more effectually utilising the heat thereof before they are allowed to escape to the
chimney or uptake. The baffle plates or dampers are preferably mounted, and
arranged in a manner resembling Venetian blinds, means being provided for
adjusting and regulating their position according to requirement.
Dated this 16th day of November 1887
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Steam Boiler and other Furnaces.
I, THOMAS SNOWDON late of 91. Guildford Street, in the County of Middlesex,
but now of 6 Great Ormond Street, in the same County, 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 :-
This invention has for object to ensure efficient combustion of fuel and utilization
of the heat produced in steam boiler and other furnaces, whether worked by natural
or by forced draught.
According to this invention, air is admitted to the combustion chamber through
hollow fire bars the inner ends of which are carried by a support preferably in the
form of a water box or trough which is provided with means for supplying and
maintaining a constant height of water therein. This water box serves, together
with the air passing through the fire bars, to prevent these parts becoming excessively
heated. The hollow fire bars which, in some cases, may be arranged in an inclined
attitude may be in communication at their outer ends with an air box or chamber the
upper part of which may in some cases, form a dead plate.
An adjustable sliding diaphragm is arranged below the fire bars, and the exit
areas above and below the fire bars for the passage of flame and products of
combustion to the combustion chamber are preferably so proportioned that air after
passing upward through the fuel from the front portion of the ash pit, wholly or
partially descends through the fuel at the rear portion of the firegrate, and escapes
below the fire bar support or trough.
An air tube or passage may be arranged below the fire bars for admitting an
additional supply of air to the lower part of the combustion chamber such air aiding

page_text: in effecting the downward passage of the air and products of combustion through the
fuel on the rear portion of the fire grate.
In the case of tubular boilers, such as marine boilers, baffle plates or dampers may
be arranged at the smoke box end of the tubes for the purpose of retarding the
passage of the hot gases and products of combustion and thereby more effectually
utilizing the heat thereof before they are allowed to escape to the chimney
or uptake.
The baffle plates or dampers are, preferably mounted and arranged in a manner
similar to venetian blinds, means being provided for adjusting and regulating their
position according to requirement.
In the accompanying two sheets of illustrative drawings Fig. 1 is a longitudinal
vertical section of a steam boiler of marine type provided with a furnace constructed
according to this invention. Fig. 2 is a transverse section on the line A. B Fig. 1.
1, 1, are hollow fire bars formed at their inner ends with upward extensions 2.
in which are openings 3 preferably in the form of slits for the passage of air. 4 is
a water box for supporting the inner ends of the fire bars; it is provided with a
loose fitting cover to admit of the ready escape of steam formed therein, and is
connected by a tube 5 with a tank provided with means such as a ball cock for
When the fire bars are
maintaining a constant height of water in the water box.
long a second water box, similar to the first, may be employed as shewn to support
them at or near their centres. The front ends of the hollow fire bars are clamped
between two plates 6 and 7 of which 7 rests at its ends upon the sides of the fire box,
and at its front end projects forward beyond the front of the boiler as shewn at 8 to
provide a support for an air box 9. This air box which is constructed without a
bottom and without an inner side as shewn rests upon the projecting portion of the
plate 7 and may be held to the front ends of the fire bars by through bolts 10 as
shewn. 11 is a tube for supplying air under pressure to the air box and means may
be provided for mixing water, spray or vapour with such air. The air may be drawn
(in the case of marine boilers) through the coal bunkers in order to remove the
explosive gases usually formed therein and utilize them for the production of heat.
The space between adjacent fire bars at their outer ends may if necessary be filled
with fire clay to prevent escape of air from the air box at these parts.
The plate 6
serves as a dead plate for fuel. 12 is a sliding diaphragm or draught regulator
arranged below the fire bars and provided with a handle 13 for adjusting its position
as required. 14 is a baffle plate arranged in the combustion chamber 15 beyond the
fire bars, to cause the air, flame and combustible gases entering the said chamber above
and below the fire bars to become well mixed and thus ensure perfect combustion.
In the case of boilers of the Lancashire or Cornish type, this baffle plate should be
arranged at a short distance, say two to three feet behind the rear ends of the fire
bars and is preferably so arranged in the flue that the exit area between it and the
sides of the flue increases from top to bottom. 16 is a passage for admitting air to
the combustion chamber 15; it may consist of a tube or tubes, or, as in the
example shewn, it may be formed by a plate 17 arranged to rest upon the sides of the
fire box.
18, 18, are baffle plates or dampers pivotted at the outer ends of the boiler tubes 19
and in the smoke box 20 for the purpose of retarding the passage of the hot gases and
products of combustion through such tubes, and thereby effectually utilize the heat
thereof. They are connected, preferably in sets, to rods one of which is shewn at 21
each of which is provided with a handle 22 for operating them. By arranging the
baffle plates 18 in sets, as shewn, each set may be adjusted independently and thus
enable the quantity of hot gases and products of combustion passing through each of
the several rows of tubes to be regulated according to requirement. These baffle
plates 18 are of considerable value in furnaces worked by forced draught.
By the use of the diaphragm or regulator 12 and by diminishing the exit area above
the fire bars, air after passing upward between the front ends of the fire bars, will be
caused to descend through the fuel on the rear part of the fire bars as indicated by
the arrows, whilst the air passing through the fire bars and escaping through the

page_text: openings 3 will issue in a direction opposite to that of the combustible gases and
become well mixed therewith.
The steam produced in the water box or boxes will be decomposed by the heat of
the furnace and its constituents mixed with the hot gases and products of combustion
will pass into the combustion chamber 15 where they will recombine with the
production of intense heat.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Providing in a steam boiler or other furnace, hollow fire bars having their inner
ends so formed with openings as to cause air forced along within the bars towards
their inner ends to issue in a direction opposite or approximately so to that of the hot
gases and products of combustion passing from and over the fuel on the grate, the
said fire bars being supported by a water box or boxes so constructed that steam
generated therein can escape in manner and for the purpose herein before described
with reference to the drawings annexed.
2. The use with the hollow firebars and water box or boxes, referred to in the
preceding claim, of the sliding diaphragm or draught regulator 12 arranged below
the firebars substantially as hereinbefore described and shewn in the drawings annexed
for the purpose set forth.
3. The arrangement of dampers in a smoke box in connection with rows or series
of flue tubes in the manner described with reference to and illustrated in figure 1 of
the drawings annexed for the purpose set forth.
4. My improved furnace for steam boiler or other purposes constructed arranged
and operating substantially as hereinbefore described with reference to and shewn in
the drawings annexed whether provided with the air passage 16 or not.
Dated this 17th day of September 1888.
THOS. SNOWDON.