Certain Improvements in Furnace Fire Bars.
Year: 1897

page_text: Date of Application, 1st Jan., 1897
Complota Specification Loft 1st Oct. 1897-Accepted. 6th Nov.. 1897
PROVISIONAL SPECIFICATION.
Certain Improvements in Furnace Fire Bars.
I, EDWARD PROSSER DAVIS, of 17, Lenton Road, The Park, Nottingham, in
the County of Nottingham, Iron Master, do hereby declare the nature of this
Invention to be as follows:-
This Invention has reference to those fire bars which are made hollow or
Chambered so as to convey heated air behind the furnace bridge to ignite the
furnace gases and complete the combustion. Each of the said furnace bars is
sometimes cast of an enclosed hollow section and sometimes the bars are made of
a trough or other section so that when two or more of the bars are placed together
side by side they form the passages for conveying the heated air behind the furnace
bridge as aforesaid.
Heretofore the hollow or chambered parts of the bars through which the air
passes as aforesaid have usually been made parallel or approximately parallel so
that the passages have been of about the same cross sectional area throughout.
Or the said passages have been made taper so that the sectional area of the air
chamber or passages is reduced in the direction in which the air travels along the "
bar.
According to this Invention I make the fire bar of such a shape that the
sectional area of the air chamber or passage gradually increases in the direction
in which the air travels, that is to say, in an ordinary boiler furnace I make the
sectional area of the chamber or hollow smallest near the fire door where the air
first enters the bar the area of the chamber or hollow gradually increasing in
the direction of the bridge the largest sectional area being where the heated air
leaves the chamber or hollow of the bar. Thus the sectional area of the bar and
air chamber gradually deepen from the front end towards the back.
When two or more bars are fixed end to end lengthwise of the grate they may
be so shaped that their ends fit one into the other the whole gradually increasing
in area towards the outlet end at the fire bridge.
By gradually increasing the area of the air passages as aforesaid there is more
space for the expansion of the air when heated and for any further supply of air
that may be taken from the ashpit into the said passages through side or bottom
openings in the bars in addition to what may enter through the open end of the
bar. This enables the bars to convey a larger quantity of heated air to the back
of the bridge without increasing the depth of the bars along the whole length of
the fire grate. The increased area at the discharging end of the bars also
prevents any blow pipe action by the heated air or gases issuing therefrom which
sometimes causes local heating and damage to the boiler plates.
Any usual or convenient form of damper arrangements may be used at the fire
bridge end of the bars operated by a rod passing through the ash pit to the front

page_text: of the furnace so that the flow of heated air from the bars may be stopped off when
necessary.
11 L
01-L
C D
1000
'
Certain Improvements in Furnace Fire Bars.
I, EDWARD PROSSER DAVIS, of 17, Lenton Road, The Park, Nottingham, in
the County of Nottingham, Iron Master, 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 reference to those fire bars which are made hollow or
chambered so as to convey heated air behind the furnace bridge to ignite the
furnace gases and complete the combustion. Each of the said furnace bars is
sometimes cast of an enclosed hollow section and sometimes the bars are made of
a trough or other section so that when two or more of the bars are placed together
side by side they form the passages for conveying the heated air behind the furnace
bridge as aforesaid.
Heretofore the hollow or chambered parts of the bars through which the air
passes as aforesaid have usually been made parallel or approximately parallel so
that the passages have been of about the same cross sectional 'area throughout.
Or the said passages have been made taper so that the sectional area of the air
chamber or passages is reduced in the direction in which the air travels along the
bar
According to this Invention I make the fire bar of such a shape that the
sectional area of the air chamber or passage gradually increases in the direction
in which the air travels, that is to say, in an ordinary boiler furnace bar I make the
sectional area of the chamber or hollow smaller near the fire door where the air
first enters the bar the area of the chamber or hollow gradually increasing in
the direction of the bridge the largest sectional area being where the heated air
leaves the chamber or hollow of the bar. Thus the sectional area of the bar
and air chamber gradually deepen from the front end towards the back.
On the accompanying drawing Fig. 1 is a longitudinal sectional elevation and
Fig. 2 is a cross section on Line X X of Fig. 1 of a furnace fire bar constructed
and arranged in accordance with this Invention; Fig. 3 shews a slightly modified
form of the said fire bar; Fig. 4 is a side elevation partly in section of another
form of the fire bar constructed and arranged in accordance with this Invention;
Fig. 5 is a cross section of the same on line Y Y of Fig. 4; Fig. 6 is a longitudinal
section and Fig. 7 is a cross section shewing two of my improved bars arranged
end to end lengthwise of the grate.
The same letters of reference indicate the same or corresponding parts in all
the figures of the drawing.
In the example of my Invention illustrated by Figs. 1 and 2 the fire. bar A is
cast of a rectangular tubular form in cross section as shewn by Fig. 2 the air
entering the chamber or passage at the fire door end a¹ and passing along the
inside of the bar and leaving the same at the end behind the smoke bridge B.
It will be seen that the depth of the bar A gradually increases from the air inlet
end a to the air outlet end a² in the direction which the air travels the largest
sectional area being at where the heated air leaves the chamber of the hollow bar.

page_text: By gradually increasing the area of the passage through the bar as aforesaid
there is more space for the expansion of the air when heated and also, as herein-
after described, for any further supply of air that may be taken from the ash
pit in the said passage through side or bottom openings in the bars in addition
to what may flow through the end a¹ of the bar. This enables the bars to convey
a larger quantity of heated air to the back of the bridge B without increasing the
depth of the bars along the whole length of the fire grate. The increased area
at the discharging end of the bars also prevents any blow-pipe action of the
heated-air or gases issuing therefrom which sometimes causes local heating and
damage to the boiler plates.
Fig. 3 shews a similar bar to Fig. 1 but made with a bottom opening a³ to
admit air from the ash.pit.
Figs. 4 and 5 shew my present Invention applied to firebars of the kind
described in the Specification of my Letters Patent No. 13349 of A.D. 1896, tliat
is to say, they are so constructed that when placed side oy side in the furnace they
form an air chamber e between the bars by whien the air is heated and conveyed
behind the bridge these chambers having inverted V-shaped or inclined bottom
air inlet openings at a into the ash pit through which air enters the chambers
and impinges on the upper parts of the bars and the dust, can fall from the
chambers into the ash pit. It will be seen that according to my present Inven-
tion these fire bars are made to gradually deepen towards the outlet end a² so that
the area of the passage e between the bars A A will be gradually increased in the
direction in which the air is flowing as above described.
1
When two or more of the said bars such as A3 A4 (Fig. 6) are made to taper
towards the fire bridge end as above described and fixed end to end lengthwise of
the grate their meeting ends may fit one into the other as at a the whole gradu-
ally increasing in area towards the outlet end a² at the fire bridge as above
described.
Any usual or convenient form of damper arrangements may be used at the
fire bridge end a² of the bars operated by a rod passing through the ash pit to the
front of the furnace so that the flow of heated air from the bars may be stopped off
when necessary.
These damper arrangements being well known and forming
no part of my Invention are not illustrated on my drawing.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:-
Furnace fire bars made with air chambers or air passages to convey heated air
behind the furnace bridge the sectional area of said air chambers or air passages
gradually increasing from the fire door end towards the bridge substantially as
and for the purposes hereinbefore described with reference to the accompanying
drawing.
Tel : 0041 1. of Cantoni 1907
CHARLES BOSWORTH KETLEY,
Agent for the Applicant.