IMPROVEMENTS IN BOILER AND OTHER FURNACES
Year: 1881

page_text: LETTERS PATENT to Arthur William Lovell Reddie, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Patent Agent, for an
Invention of "IMPROVEMENTS IN BOILER AND OTHER FURNACES." A com-.
munication from abroad by Wright Duryea, of Glen Cove, in the State of
New York, United States of America.
PROVISIONAL SPECIFICATION left by the said Arthur William Lovell
Reddie at the Office of the Commissioners of Patents on the 14th April
1881.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. "IMPROVEMENTS IN BOILER
AND OTHER FURNACES." [A communication from abroad by Wright Duryea, of
Glen Cove, in the State of New York, United States of America.]
In steam boiler furnaces steam is often supplied in moderate quantities above
the grate for the purpose of being decomposed and mingled with the gaseous
products of the fuel for more economical working.
The steam so used however before it is injected into the boiler is in many cases
passed through a superheater for raising it to such a temperature that it will be
more readily decomposed on entering the furnace, and even when so superheated
the steam and the gaseous products of the fuel are hurried out of the furnace
before they are properly mixed and are in a condition to produce the most perfect
and economical combustion, and the object of this Invention is to dispense with a
separate superheater for the steam injected into the furnace and to retain the
steam and gaseous products of the fuel within the furnace until they shall be
thoroughly commingled and in a condition to combine and produce more nearly
perfect combustion, thereby effecting an economy of fuel.
To this end the Invention consists essentially in the combination with a furnace
of a hanging bridge of brick (or it may be a water leg) projecting below the top
of the furnace, and near the end at which the products of combustion escape from
the furnace, and a pipe or pipes for injecting steam into the said furnace. The

page_text: injected steam is retained for a time within the furnace by the hanging bridge
over the fire, and becomes highly heated and thoroughly mixed with the gaseous
products of the fuel, producing very perfect combustion.
The Invention also consists in a novel construction of the hanging bridge for
marine boilers where the furnaces are in cylindrical flues in the boiler. This
bridge is made of firebricks arranged in an annular form, and it has an excentric
passage through it.
-
The Invention also consists in the combination with a furnace of a transverse
bridge in the front part thereof forming between the front and the top of the
furnace communicating upward and rearward passages, a pipe for injecting steam
into said rearward passage or passages, and a hanging bridge depending from the
top of the furnace, near the exit end thereof.
Where the transverse bridge in the front of the furnace is employed the steam
injected into the rearward passage or passages tends to produce a vacuum in the
upward passage or passages, and the smoke and gaseous products of the fuel are
drawn up through said upward passage or passages and thoroughly commingled
with the steam injected into the furnace, after which the commingled steam and
gaseous products of the fuel are retained in the furnace by the hanging bridge at
the rear thereof, until the steam is decomposed and the mixture raised to a
temperature suitable for economical combustion.
It will thus be seen that instead of the steam and gaseous products of the fuel
being hurried out of the furnace they are retained in the chamber immediately
over the fire, and are there mingled and heated to such a degree that a very perfect
combustion is secured and a corresponding economy of fuel is effected.
It will be understood from the above description that the bridge or arch at the
front of the furnace forming communicating upward and rearward passages may be
omitted, as the hanging bridge at the rear of the furnace would perform its proper
functions whether the transverse bridge or arch were in the front of the furnace
or not, but it may be preferable in some cases to use both the hanging bridge at
the rear of the furnace and the transverse bridge or arch at the front thereof, as it
is believed that when combined a greater economy of fuel is secured.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur William Lovell Reddie in the Great Seal Patent Office on
the 13th October 1881.
"
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. IMPROVEMENTS IN BOILER
AND OTHER FURNACES." A communication from abroad by Wright Duryea, of
Glen Cove, in the State of New York, United States of America.
In steam boiler furnaces steam is often supplied in moderate quantities above the
grate for the purpose of being decomposed and mingled with the gaseous products
of the fuel for more economical working.
The steam so used however before it is injected into the boiler is in many cases
passed through a superheater for raising it to such a temperature that it will be
more readily decomposed on entering the furnace, and even when so superheated
the steam, and the gaseous products of the fuel are hurried out of the furnace before
they are properly mixed and are in a condition to produce the most perfect and
economical combustion.
The object of this Invention is to dispense with a separate superheater for the
steam injected into the furnace, and to retain the steam and gaseous products of
the fuel within the furnace until they shall be thoroughly commingled and in a
condition to combine and produce more nearly perfect combustion, and thereby
effect an economy of fuel.
To this end the Invention consists essentially in the combination with a furnace
of a hanging bridge of brick (or it may be a water leg)-projecting below the top of
the furnace and near the end at which the products of combustion escape from the
furnace, and a pipe or pipes for injecting steam into the said furnace. The injected
steam is retained for a time within the furnace by the hanging bridge over the fire,
and becomes highly heated and thoroughly mixed with the gaseous products of the
fuel, producing very perfect combustion.
The Invention also consists in a novel construction of the hanging bridge for
marine boilers where the furnaces are in cylindrical flues in the boiler. This bridge
is made of fire bricks arranged in annular form, and it has an excentric passage
through it.
The Invention also consists in the combination with a furnace of a transverse
bridge in the front part thereof forming between the front and the top of the
furnace communicating upward and rearward passages, a pipe for injecting steam
into said rearward passage or passages, and a hanging bridge depending from the
top of the furnace near the exit end thereof.
Where the transverse bridge in the front of the furnaces is employed the steam
injected into the rearward passage or passages tends to produce a vacuum in the
upward passage or passages, and the smoke and gaseous products of the fuel are
drawn up through said upward passage or passages and thoroughly commingled
with the steam injected into the furnace, after which the commingled steam and
gaseous products of the fuel are retained in the furnace by the hanging bridge at
the rear thereof until the steam is decomposed and the mixture raised to a temperature
suitable for economical combustion.
In the accompanying Drawing Fig. 1 represents a longitudinal section of an
ordinary return tubular boiler and furnace embodying the Invention; Fig. 2 repre-
sents a transverse section thereof upon the dotted line x, x, of Fig. 1; Fig. 3
represents a similar section upon the dotted line y, y, of Fig. 1; Fig. 4 represents a
longitudinal vertical section of a locomotive boiler also embodying the Invention;
Fig. 5 represents a longitudinal vertical section of a marine boiler embodying the

page_text: Invention; Fig. 6 represents a transverse section upon the dotted line 2, 2, of Fig. 5;
Fig. 7 represents a longitudinal vertical section of a furnace also embodying the
Invention; and Fig. 8 represents a transverse section on the line 2, 2, of Figure 7.
Similar letters of reference designate corresponding parts in all the Figures.
Referring first to Figures 1, 2, and 3, A represents an ordinary return tubular
boiler set in brickwork in the usual way; B designates the grate of the furnace;
C is the back connection; and D the chimney.
E is the ordinary bridge wall at the back of the grate B, and behind this bridge
wall is a hanging bridge F projecting downwards from the bottom of the boiler,
and preferably extending below the top of the ordinary bridge wall E. The manner
of constructing the bridge wall F is clearly shewn in Figure 2, which represents
it as consisting of a brick arch extending from one side to the other of the furnace,
and extending upon each side of the boiler. It will be clearly understood that no
smoke or other product of combustion can pass out of the furnace and reach the
back connection C unless it passes under the hanging bridge F. If desirable the
bridge F might be formed by a water leg placed transversely of and communicating
with the boiler. The steam is injected into the furnace above the level of the
underside of the bridge F by means of pipes a, a, upon opposite sides of the furnace,
as shewn clearly in Fig. 3.
It will thus be seen that the portion of the furnace above a horizontal plane
coincident with the lower edge of the bridge F will constitute in practical effect a
chamber in which the steam will be retained immediately over the fire and held in
the furnace a sufficient length of time to become highly heated and mingled with
the gaseous products of the fuel. The mixture of steam and gas is burned, and 'a
very perfect combustion obtained.
It is a known fact that every one hundred and sixty pounds of air at a tempera-
ture of about thirty two degrees (32°) Fahrenheit contains about one pound of
water, and for every additional twenty seven degrees (27°) imparted to the air it will
hold about an additional pound of water. It is also known that there is an affinity
between oxygen, carbon, and hydrogen, and it is believed that the steam is first
absorbed by the air and gaseous product of the fuel on the principle of saturation,
as above set forth, and this brings the gaseous products of the fuel into intimate
contact with the steam under a temperature favourable to the decomposition of
water, and hence the fire is supplied with oxygen under the grate and also over
the whole fire surface of the boiler or other furnace.
In connection with the hanging bridge F there may also be arranged a bridge F¹
transversely across the furnace near the front thereof and over the fire door, as
clearly seen in Figures 1 and 3, thus forming between said bridge and the front of
the furnace an upward passage s, and between the top of the said bridge and the
under side of the boiler a rearward passage s', which is in communication with the
said upward passage s.
When the bridge F¹ is used, steam must be injected into the rearward passage 8'
by means of jet pipes or nozzles a¹ (see Figure 1), which produces a rearward blast or
current in the rearward passage s'. The smoke and gaseous products of combustion
are thereby drawn through the upward passage 8, and become thoroughly
commingled with the steam entering by the jet pipes or nozzles a¹. The mixture
then passes rearwards through the passage s¹, and is retained in the furnace by the
hanging bridge F until highly heated.
Referring now to Fig. 4, G represents a boiler of the locomotive type, and G¹ the
furnace thereof in which are the grate b, and the fire door c; F is the bridge
which depends from the upper part of the furnace and near the rear end thereof,
and as here represented consists of a water leg. The steam is introduced into the
furnace G¹ through a pipe a above the fire door c, and the space in the upper part
of the furnace above the dotted line coincident with the underside of the hanging
bridge F constitutes a chamber similar to that previously explained and serving a
like purpose.
Referring now to Figures 5 and 6, H represents the furnaces of a marine boiler

page_text: Just
of a type in common use, they being arranged in three cylindrical flues; H¹ is the
back connection, and H2 the chimney or smoke stack; I is the ordinary bridge wall
at the rear of each furnace; d, designates the grates, and e, the fire doors.
back of the bridge-wall in each furnace is an annular bridge J, which is composed
of a series of fire bricks of a form adapted to support each other. In the bridge J
is a hole J, which is excentric to the flue in order to make the upper part of this
annular bridge as deep as possible, and so to retain a large quantity of steam
entering through the jet pipes a¹, and gas in the furnace. The several bricks
forming the bridge J, may be inserted singly through manholes O and placed
in position, and thus provision is afforded for applying the bridge to boilers already
in place in steam ships.
In the front of the furnace H are communicating upward and rearward
passages s, s¹, similar to those described in connection with Figures 1, 2, and 3, but
in this case the passages are all formed in bridges or arches F2 of circular form,
inserted in the front of each furnace above the grate d and around the fire door.
The bridges or arches F2 may be of fire clay or other suitable material, and have
each a number of rearward passages s', into which project jet pipes or nozzles a', as
seen in Fig. 5. The purpose which the passages 8, 8' serve in increasing the
economy of the boiler has been previously described in connection with Figures 1, 2,
and 3.
Referring now to Figures 7 and 8, K represents a furnace which may be for
any kind of heating; L is the ordinary bridge wall; and M the escape flue or
chimney.
In the upper front part of the furnace and above the fire door f, is arranged a
transverse bridge N containing upward passages s, and communicating rearward
passages s¹.
Steam may be injected through the pipe a¹ into said rearward
passages s¹, and by the effect of the incoming steam the gaseous products of
combustion are drawn up from the surface of the fire up through the upward
passages s, and carried rearwards with the steam through the passages 8¹.
Just back of the bridge wall L and near the back end of the furnace is a hanging
bridge F, similar to those previously described and for a like purpose.
In all the modifications of the Invention which are here shewn, it will be clearly
seen that instead of the steam and gaseous products of the fuel being hurried out
of the furnace they are retained in the chamber immediately over the fire, and are
there mingled and heated to such a degree that a very perfect combustion is secured
and a corresponding economy of fuel is effected.
It will be understood from the above description that the bridge or arch at the
front of the furnace forming communicating upward and rearward passages may be
omitted, as the hanging bridge at the rear of the furnace would perform its proper
functions whether the transverse bridge or arch were in the front of the furnace or
not; but it may be preferable in some cases to use both the hanging bridge at the
rear of the furnace, and the transverse bridge or arch at the front thereof, as it is
believed that when combined a greater economy of fuel is secured.
"
Having now described the nature of the said Invention of "Improvements in
Boiler and other Furnaces as communicated to me by my foreign correspondent,
and having explained in what manner the same may be carried into effect, I wish it
to be understood that I claim,―
First. The combination with a furnace of a hanging bridge projecting below the
top of the furnace near the back end thereof, and under which the products of
combustion must pass to escape from the furnace, and a pipe or pipes for injecting
steam into the furnace in front of said bridge, substantially as and for the purpose
specified.
Second. The combination with a furnace-grate and bridge-wall of a hanging
bridge projecting below the top of the furnace behind said bridge-wall, and under
which the products of combustion must pass to escape from the furnace, and a pipe
or pipes for injecting steam into the furnace in front of said hanging bridge,
substantially as and for the purpose specified.

page_text: Third. The combination with a steam boiler having one or more cylindrical flues
in which are furnaces of pipes for injecting steam into each furnace above the fire
door, and an annular bridge fitting in each flue in rear of the furnace therein,
substantially as and for the purpose specified.
Fourth. The combination with a furnace of a bridge extending across the upper
front part of the furnace forming communicating upward and rearward passages,
a pipe or pipes for injecting steam into said rearward passage or passages, and a
hanging bridge projecting downwards from the top of the furnace near the back
end thereof, substantially as and for the purpose specified.
In witness whereof, I, the said Arthur William Lovell Reddie, have hereunto
set my hand and seal, the Twelfth day of October, in the year of our Lord
One thousand eight hundred and eighty one.
ARTHUR W. L. REDDIE. (L.S.)