Improvements in Steam Boiler and other Furnaces.
Year: 1893

page_text: Date of Applic-tion, 19th Dec., 1893
Complete Specification Left, 19th Sept., 1894-Accepted, 20th Oct., 1894
PROVISIONAL SPECIFICATION.
Improvements in Steam Boiler and other Furnaces.
I, EDMUND HOWL, of The Quarries, near Dudley, in the County of Stafford,
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates chiefly to the manner in which I construct and arrange
steam boiler and other furnaces for employment with a forced or induced draught,
although my improvements are in part applicable to ordinary draught furnaces.
The object of my invention is to construct a furnace of few and simple parts that
can be readily fitted within, or withdrawn from, a boiler or other furnace tube,
and with which a forced or induced draught may be employed, the lower portion of
the furnace tube being at the same time left clear to allow of any deposit in the
same (such as cinder, or flue-dust) beyond the bridge, being expeditiously removed
by an operator in the stoke hole by means of the usual cleaning rods and brushes,
and also to allow of admission of air behind the specially arranged fire bridge as
hereinafter described.
In carrying my invention into effect I construct the fire grate of my improved
furnace, in a number of parts or sections, butting together and secured by longitudinal
bolts. The upper or fire side of the grate consists of a preferably solid surface of metal
having a number of ribs or projections formed thereon. The underside of the grate
I form into longitudinal chambers or conduits for the conveyance of the air necessary
for combustion, such air being preferably forced or induced and admitted to the furnace
in the manner hereinafter described. Each section of the furnace is supported by two
or more legs or brackets resting on the lower portion of the furnace tube, but so
situated as to leave the central part of the lower portion of the tube clear and free from
obstruction, and arranged to avoid any clamping action on the grate sides due to
expansion and contraction. I sometimes arrange the aforementioned legs that they
may rest on balls or rollers interpolated between the bottom of the legs and the
inner surface of the furnace tube.
The innermost section of my improved furnace 1 form suitably for carrying
and supporting the furnace bridge, which consists of fire brick or other
incombustible material built up from the upper surface of such innermost section.
This section is supported by legs or brackets resting upon the lower portion of
the tube, giving a clear central passage beneath the fire bridge, which allows of
the admission of air from the front end of the furnace, to the back of the
bridge to set up a secondary combustion, thus securing the utmost heating value
from the fuel and preventing the discharge of smoke from the furnace.
The inner or fire bridge end of the air chambers or conduits, herein before
described, is closed, but the front ends are open and form bell mouth-pieces for the
admission of air, and for the application of steam-jet or other draught inducing
appliances. The mouthpieces and the dead plate, (the latter raised above the
body of the fire grate) are preferably in one and the same casting, the face of
the mouth-piece being thus approximately flush with the face of the boiler or
furnace. I provide a binged or other door or damper to cover the lower part
of the furnace front or mouth, and vary the extent of the opening of the same to
regulate the admission of air passing under the fire bridge for the secondary
combustion herein before described. I sometimes inject a supplementary supply of
air at or near the bridge, through two conducting pipes laid one on either side
of the tube immediately under the air conduits. Such supplementary air supply
may be natural, induced, or forced, by steam jet or otherwise, the said pipes
heing so placed that they do not interfere with the cleaning of the furnace tube.

page_text: The upper part of the furnace mouth is provided with the usual fire door and the
fuck is fed on to the fire grate by ordinary hand firing. I sometimes employ
mechanical stokers, either of the sprinkling, coking, or other type, and fit the same
in the usual and ordinary manner to the mouth of my improved furnace.
The air is admitted through the fire grate from the conduits or chambers, by
méaus of inlets formed in the ribs or projections on the surface of the fire grate,
hereinbefore described. Such inlets are not formed at right angles to the surface
of the grate, but at some other angle, preferably about 45 degrees, in order that the
inlets may not become choked by fuel or clinker. Although I preferably arrange
the inlets to be all at the same angle in relation to the surface of the fire grate,
yet I prefer to place them in different planes in relation to each other but arranged
alternately at right angles. By this means I obtain a thorough distribution of the
air amongst the fuel spread over the grate.
The longitudinal bolts for securing the grate segments together pass beneath the
grate surface and are thus out of contact with the fire. I provide for the expansion
and contraction of the bolts and furnace-sections by inserting spring washers under
the nuts, at one or both ends of the bolts. Such washers, which are preferably of
the Grover type, allow of slight alteration in the length of the bolts or furnace
sections, on their expansion or contraction.
Instead of forming the fire grate and the air chambers or conduits in one complete
casting or series of sectional castings, I sometimes form the grate separately from
the chambers or conduits, the grate sections with their projecting ribs being made
as single plate castings, which may be readily renewed as they become burnt by
the continued action of the fire, the air conduit sections remaining permanently
intact and undamaged.
I do not limit the application of my invention to any one size or type of boiler
or other furnace, but modify its parts and the arrangement of the same to suit
particular requirements without departing from the essential features of my
invention.
Dated this 16th day of Donnmhan 1002
MARKS & CLERK,
18, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Steam Boiler and other Furnaces.
I, EDMUND HOWL, of The Quarries, near Dudley, in the County of Stafford,
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 chiefly to the manner in which I construct and arrange
steam boiler and other furnaces for employment with a forced or induced draught,
although my improvements are in part applicable to ordinary draught furnaces.
The object of my invention is to construct a furnace of few and simple parts
that can be readily fitted within or withdrawn from, a boiler furnace tube, and
with which a forced or induced draught may be employed, the lower portion of
the furnace tube being at the same time left clear to allow of any deposit in the
same (such as cinder or flue dust) beyond the bridge, being expeditiously removed
by an operator in the stoke bole by means of the usual cleaning rods and brushes,
and also to allow of admission of air for secondary combustion behind the specially
arranged fire bridge as hereinafter described.
Referring to the two accompanying sheets of explanatory drawings,
Figure 1 (Sheet 1) is a longitudinal section and Figure 2 a cross section repre-
senting the application of my invention to a Cornish, Lancashire, or like boiler
furnace.

page_text: Figure 3 represents in cross section a modified form of my improved fire
grate.
On Sheet 2, Figure 4 is a longitudinal section and Figure 5 a cross section of a
portion of a boiler furnace showing my fire grate as arranged for the introduction
of a heated secondary air supply beyond the furnace bridge.
Figure 6 illustrates in cross section a-modified form of the grate.
The same reference letters in each view indicate the same parts.
In carrying my invention into effect I construct the fire grate of
my improved
furnace in a number of parts or sections such as A Figures 1 and 4. The upper or
fire side of the grate consists of a preferably solid surface of metal having a
number of ribs or projections such as A¹ Figures 2, 3, 5 and 6 formed thereon. The
underside of the grate I form into longitudinal chambers or conduits such as A³ for
the conveyance of the air necessary for combustion, such air being preferably forced
or induced and admitted to the furnace in the manner hereinafter described. Each
section of the furnace is supported by two or more legs or brackets resting on the
lower portion of the furnace tube, but so situated as to leave the central part of
the lower portion of the furnace tube clear and free from obstruction, and arranged
to avoid any clamping action on the grate sides due to expansion and contraction. I
sometimes make such legs or brackets entirely in the one piece with its grate section,
making it of the required length to suit the particular diameter of furnace tube in
which the grate is employed; such form or type of leg or bracket is shown at A³ in
the right hand half section of Figure 6. I prefer, however, to make the legs or
brackets with adjustable screw feet such as B in Figures 1 to 6 inclusive, in order.
that they may be fitted within tubes of varying diameters. I sometimes provide
balls or rollers between the underside or feet of the legs or brackets and the inner
surface of the furnace tube.
The innermost section C of my improved furnace I form suitably for carrying
and supporting the furnace bridge D' which consists of fire brick or other incom-
bustible material built up from the upper surface of the section C. This section
is supported by its side legs or brackets as illustrated, and thus a clear central
passage is provided beneath the fire bridge which allows of the admission of air
from the front end of the furnace, to the back of the bridge to set up a secondary
combustion, thus securing the utmost heating value from the fuel and preventing
discharge of smoke from the furnace. I preferably employ a rear bridge such
as X Figure 1 to cause thorough admixture of the air and furnace gases, a
passage Z being provided under the bridge to give access to the flue clearing rods
aud appliances. The mouth of the passage Z is closed by a suitable door such
as Y, arranged for opening and closing from the front end of the boiler by chains
and rods or other ordinary like operating appliances.
The inner or fire bridge end of the air chambers or conduits A³ is closed, but the
front ends are open into the bell mouth pieces such as E attached to the front
plate of the boiler or furnace. Air is admitted into the mouth piece E, and the
steam jet such as F or other draught inducing appliance when such is employed is
applied to the same as shown at Figures 1 and 4. I provide a hinged or other
door or damper as G to cover the lower part of the furnace front or mouth, and
vary the extent of the opening of the same to regulate the admission of air
passing under the front fire bridge for the secondary combustion hereinbefore
described.
Instead of conducting the supplementary or secondary air supply along the lower
portion of the turnace tube as herein before described and as illustrated in Figure 1,
I sometimes conduct it along the separate chambers or conduits as A' Figures 4, 5
and 6. These chambers or conduits are preferably formed in the casting with the
furnace grate sections and preferably have mouth pieces El with steam jets as F',
or other draught inducing appliances if required. At the fire brilge end I provide
a hinged or other suitable door as H, common to all the conduits, that may be
operated by the rud J froin the front of the boiler or furnace for the regulation of
the secondary air supply.

page_text: The upper part of the furnace tube mouth is provided with a fire door preferably
of the balanced swing "Martin " or other smoke preventing type as illustrated at
Figure 1. The door plate W is perforated, and has a blank baffle V. Adjustment
of the door for the subsidiary air supply over the fire, is effected by means of the
articulated latch U. Upon a plate T secured in the recess of the boiler front
plate, is fitted the hood S to provide for the admission of a further supply of air
over the fire, when so required. I sometimes employ mechanical stokers, of the
sprinkling, coking, or other type, and fit the same in the usual and ordinary manner
to the mouth of my improved furnace.
Ι
The air is admitted through the fire grate from the conduits or chambers A³ by
means of inlets formed in the ribs or projections A'. Such inlets are not formed at
right angles to the surface of the grate, but at some other angle, preferably
about 45 degrees, in order that the inlets may not become choked by fuel or clinker.
Although I preferably arrange the inlets to be all at the same angle in relation to
the surface of the fire grate, yet I prefer to place them in different planes in
relation to each other, but arranged alternately at right angles. By this means I'
obtain a thorough distribution of the air amongst the fuel spread over the fire
grate.
The longitudinal bolts K for securing the grate segments together pass beneath
the grate surface and are thus out of contact with the fire. I provide for the
expansion and contraction of the bolts and furnace sections by inserting spring
washers under the nuts, at one or both ends of the bolts. Such washers, which are
preferably of the Grover type, allow of slight alteration in the length of the bolts
and furnace sections, on their expansion or contraction. I sometimes attach the
various sections or segments of the furnace grate together, by forming male and
female or other suitable joint faces, secured by means of joint bolts and nuts such
as Q Figure 1. To prevent leakage or escape of air from the conduits, I employ
asbestos or other suitable insertion material between the joint faces of the grate
sections.
"
Instead of forming the fire grate and the air chambers or conduits in one
complete casting or series of sectional castings, I sometimes form the grate
separately from the chambers or conduits, in the manner shown at the right hand
half section at Figure 3, and the left hand half section at Figure 6. The grate
sections with their projecting ribs are then made as single plate castings, which may
be readily renewed as they become burnt by the continued action of the fire, the
air conduit sections remaining permanently intact and undamaged.
When applying a steam jet draught inducing appliance I preferably superheat
the steam before allowing it to issue from the jets such as F, by means of the
superheater L. This superheater is carried or suspended within the furnace tube
of the boiler and consists of two pipes arranged one within the other, in such a
manner that the steam on its way to the jets is caused to travel along the inner
tube and through the space between the inner and outer tubes, and thus becomes
superheated by its contact with the heated external pipe of the super-heater L.
I do not limit the application of my invention to any one size or type of boiler,
or other furnace, but modify its parts and the arrangement of the same to suit
particular requirements without departing from the essential features of my
invention.
Having now particularly described and ascertained the nature of my said
invention, and in what mauner the same is to be performed, I declare that what
I claim is :-
1. In steam boiler and other furnaces the method of supplying a forced or
induced draught, by means of independent or separate air conduits formed imme-
diately beneath the surface of the grate, and inlets or passages formed through ribs
or projections from the surface of the grate, substantially as hereinbefore described
and as illustrated in the accompanying drawings.
2. In steam boiler aud other furnaces the method of conveying a supplementary

page_text: forced or induced air supply to support a secondary combustion by means of air
conduits separate from or cast with the grate, the said air conduits discharging air
beyond the fire bridge and controlled by a valve operated from the front,
substantially as bereinbefore described and as illustrated in the accompanying
drawings.
3. The construction of a fire grate for boiler and other furnaces having ribs or
projections on its upper side with passages or inlets for admitting a forced or
induced draught of air from independent conduits, or passages, cast or formed on its
underside, substantially as hereinbefore described and as illustrated in the accom-
panying drawings.
4. An improved fire grate for boiler and other furnaces having independent air
couduits or chambers on its lower side and projecting ribs with air inlets or
passages on its upper side, and formed from lengths or sections connected together
by means of bolts on the underside of the grate out of contact with the fire,
substantially as hereinbefore described and as illustrated in the accompanying
drawings.
5. An improved fire grate for boiler and other furnaces, consisting of lengths
or sections bolted together, and supported by legs or brackets resting upon the
underside of the furnace tube, in such a manner as to provide a clear passage
or thoroughfare along the central part of the lower portion of the tube,
substantially as hereinbefore described and as illustrated in the accompanying
drawings.
Laad k
LDIE
www
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents for the Applicant.