Improvements in or relating to Furnaces.
Year: 1896

page_text: Date of Application, 15th Oct., 1896
Complete Specification Left, 15th July, 1897-Accepted, 15th Nov., 1897
Improvements in or relating to Furnaces.
I, THOMAS EDWARD CADDY of 9 Wycliffe Street, New Basford, in the Borough of
Nottingham, Engineer do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in boiler or like furnaces, and it has for its
object the provision of means for introducing heated air over the front of the fire, in
order to assist in consuming the smoke.
The consumption of the smoke may be best attained by introducing air at the front
of the furnace, either through openings in the front plate or door, or by leaving the
latter partly open. The introduction of air however at the same temperature as the
atmosphere has a very injurious effect on the crown plates of a boiler flue, and also
reduces the efficiency of the boiler materially.
In carrying out this invention, on each side of the interior, and at the front of the
furnace, is a tube of suitable diameter, bent into a coil or other convenient form, the
said tube or coil being preferably formed so as to fit up to the walls of the furnace,
and its several parts or members disposed to the best advantage for taking up the
heat from the furnace fire.
One end of the coil is connected to or is passed through an opening formed in the
front plate of the furnace, and the said end of the coil, or opening in the front plate,
may be provided with either a sliding or other suitable form of door, or a circular or
rectangular regulator of the hit and miss variety, by means of which the amount of
air admitted to the coil is regulated.
The inner or delivery end of the coil is placed so as to deliver the air in the best
position for mingling with the smoke and the outlet may be made in the form of a
slit, which slit is placed horizontally in order to spread the current of hot air over as
large a space as possible.
The area of the slit is preferably equal to or in excess of that of the tube, in order
to permit of the free passage of the air through the latter.
With this arrangement the air admitted to each coil is first heated and then
delivered into the furnace, where it will efficiently assist in the consumption of the
smoke, without having an injurious effect on the crown plates of a boiler, on account.
of its being heated before coming into contact with them.
The coils are preferably arranged so that they are not actually in contact with the
fire, but are heated by radiation therefrom, and for this purpose they are placed near
the furnace door and extend for a short distance within it. It may however in some
cases be necessary in order to obtain greater heating capacity, to change the position
of the coils so as to bring them in direct contact with the fire.
One or more coils may be employed as desired, in the former case I carry the tube
from one side over the top of the furnace and down the other side, and back again, to
and fro a suitable number of times according to the heating capacity required.
In a boiler furnace in which an arched baffle plate is employed to protect the boiler
front, the tube or coil may be disposed between the said plate and the walls
of the flue, in place of the brickwork usually employed, or in conjunction
therewith.

page_text: The coils may be formed by one piece of tubing bent into the required shape, or
built up of one or more members, in the latter case the members inay be cast into
the required form; or part of the coil may be cast and part be formed of bent or
straight tubing.
In an alternative arrangement, a hollow casing provided with baffle plates arranged so
as to form a tortuous passage for the air may be employed instead of a bent tube or coil,
but I preferably employ the latter arrangement as it presents a greater exterior
heating surface to the fire.
The air may be drawn through the bent tube, coil, or casing by the ordinary
draught, but if preferable a current may be induced therein by employing a fine
steam jet which is directed into the outer end of the coil, or opening in the
casing.
In this case the arrangement employed for regulating the admission of air may be
modified to admit the jet or steam pipe.
When a steam .jet is employed it will be seen that a forced draught may be obtained
above the fire grate, whilst there may be only an ordinary draught in the ashpit. Or
the forced draught above the grate may be worked in connection with a forced draught
in the ashpit.
Dated this 15th day of October 1896.
BOULT & WADE,
Agents for the Applicant.
I THOMAS EDWARD CADDY, of 9, Wycliffe Street, New Basford, in the City of
Nottingham, 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 relates to improvements in boiler or like furnaces, and it has for its
object to provide means for introducing heated air over the front of the fire in order
to assist in consuming the smoke.
The consumption of the smoke it is found may be attained by introducing air at
the front of the furnace, either through openings in the front plate or door, or by
leaving the latter partly open. The introduction of air however at the same
temperature as the atmosphere has a very injurious effect on the crown plate of a
boiler flue, and also reduces the efficiency of a boiler materially.
The invention will be best understood by reference to the accompanying drawings
in which.
Fig. 1. is a front view partly in section showing my intention applied to a boiler
furnace, the doors of which latter are removed.
Fig. 2. is a cross section taken on the line X X of Fig. 1.
Like letters indicate like parts throughout the drawings.
According to this invention, on each side of the interior and at the front of the
furnace A, is a tubular coil B provided with an air passage of suitable section and
area.
Each coil B is provided with a flange B¹ which is bolted to the dead plate C of the
furnace at points C¹ on each side of the plate, openings C² being formed in the plate
at these points, to admit air to the interior of the coils.
Each coil B is preferably carried from the flange B¹ up to the crown of the flue,
then back again towards the dead plate, and then up again to the crown of the boiler
as shown.

page_text: At the latter point or end B2 of each coil, openings D are formed to allow the air to
escape into the furnace.
Each coil B is connected to a short curved casing E provided with a flange which
is bolted at C¹ on the underside of the dead plate C and directly under the flange B¹
of the coil as shown. The outer end of this casing is preferably enlarged and is fitted
with a grating F which is closed by a second sliding grating F", the two gratings
forming a rectangular regulator of the "hit-and-miss" type.
With the foregoing arrangement, air is admitted by the regulator F F¹, through
the casing E, into the coil B where it is heated in its passage and is then delivered
by the openings D into the furnace, where it will efficiently assist in the consumption
of the smoke without having an injurious effect on the crown plates of the boiler, on
account of its being heated before coming into contact with them.
The coils B B are preferably so arranged that they are not actually in contact with
the fire but are heated by radiation therefrom, and for this purpose they are placed
as shown near the front of the furnace and extend for a short distance within it.
It may however in some cases be necessary in order to obtain greater heating
capacity to change the position of the coils so as to bring them in direct contact with
the fire.
If desirable one coil may be employed instead of two as shown, and in this case I
carry the coil from one side, over the top of the furnace to the other side, and back
again two or more times.
In a boiler furnace in which an arched plate is employed in the interior of the
furnace in connection with brickwork, to protect the boiler front, the coil or coils may
be disposed between the said plate and the walls of the flue, in place of the brickwork
usually employed.
The coil B may be formed of one piece of tubing bent into the required shape,
or be built up of one or more members as shown, bolted together by bolts G.
The air may be drawn through the coils B B by the ordinary draught, but if
preferred a current may be induced thereon by employing a steam jet in each
casing E; these jets are delivered through nozzoles H placed in the casing E which
are connected by a pipe H¹ provided with a stop cock H2 to the steam space in the
boiler.
When a steam jet is employed a forced draught may be obtained above the fire
grate either with or without a forced draught in the ashpit.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
'
(1) In a furnace the employment of a coil such as B placed within the furnace for
heating and delivering air over the fire substantially as described.
(2) In a furnace the combination with a coil such as B of a steam delivery nozzole
such as H substantially as and for the purpose described.
(3) In a furnace the combination with a dead plate C of a coil such as B placed
within the furnace and an exterior casing such as E substantially as described."
(4) The combination and arrangement of parts constituting the complete apparatus
for heating air and delivering it over the fire substantially as described and illustrated
in the accompanying drawings.
Dated this 14th day of July 1897