Improvements in Furnace Bars and Forced Draught Apparatus for Steam Generators.
Year: 1892

page_text: Date of Application, 20th Apr., 1892-Accepted, 21st May, 1892
COMPLETE SPECIFICATION.
Improvements in Furnace Bars and Forced Draught Apparatus for
Steam Generators.
I, JOHN GEORGE KINCAID of Clyde Foundry, Greenock, Renfrewshire,
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 the construction and arrangement of the bars in the
furnaces of steam generators and to the conjunction with them of apparatus for the
supply to the furnace as required of a forced draught of partially heated air and
of heated air and steam the invention having for its object to promote
combustion of the fuel used and to diminish or prevent smoke.
The improvements are illustrated by the several figures on the accompanying
sheet of drawings
Figure 1 being a longitudinal section,
Figure 2 a horizontal section on planes above and below the furnace bars,
Figure 3 a transverse section and
Figure 4 an end elevation of the furnace of a horizontal return tubular steam
boiler of the marine type with the invention applied thereto.
As shewn by these figures the improved apparatus consists of two air trunks or
mains A laid at the sides parallel to the length of the furnace and below the
furnace bars these trunks being in front of the furnace connected to branch_pipes B
leading to a fan, blower pump or other apparatus for forcing air. The fire
bridge C at the inner end of the furnace is made hollow and in the hollow part
there is situated a pipe or tube D whose ends are connected to the trunks A and
the upper surface of which tube is perforated with holes. Within each air trunk a
pipe E is contained the outer end of which is connected by a cock and branch E'
to the steam space of the boiler whilst its inner end is terminated in a nozzle E' at
a point where the trunk itself is connected to one end of a pipe F which is bent
upwards and has its other end returned through the upper part of the bridge Can
inclined opening G being made in the bridge in front of the said pipes so as to
direct the steam and air current to strike the fire grate at its outer end near the
dead plate.
Within the furnace there is laid crosswise from one trunk A to the other a
series of communicating pipes H each of which is perforated with a row of holes at
the front and has a furnace bar I hung upon it. The upper end of each furnace
bar is curved or hook shaped as shewn by Figure 1 to fit over its corresponding
pipe H and it has at intervals throughout its length flat parts made upon it the
flat parts of one bar being opposite the curved parts y of the next in series. Each
bar I has a tail or leg the lower end of which enters into a slot made in a bar Jor
is connected to the said bar which at its inner end is hung by a link L from the
under part of the bridge C whilst at its outer end it is connected to one arm of a
bell crank M centred on a bar or pin N below the level of the furnace door. By
operating the crank M, the bar J is reciprocated so as to cant the tail or leg of
each furnace bar I from its vertical position and cause the flat surfaces of the
bars to leave the horizontal and assume an inclined position which has the effect of
breaking up the body of fuel or clinker on the furnace hearth and at the same time
of uncovering the rows of holes in the pipes H immediately underneath so that the
forced draught (which in its passage through the trunks A and pipes H is partially
heated) is discharged into the furnace. The perforations being under the squares
lischarge the forced air over the corresponding round on the next bar in the series

page_text: further supply of air from the stokehole with it. When the bar J is operated so as
to bring the tails or legs of the furnace bars I to their vertical position the flat
parts of the series of bars then lie horizontal while by the same action the rows
of holes in the pipes H are in a manner closed or covered over acting as the closing
of a damper would do in the fire which is then in a condition to be cleaned.
In addition to the support afforded to the pipes D, H by connecting their ends
to the air trunks A they are further stayed or supported by two rods w passed
through the furnace from the firing end to the back of the bridge C and fastened
to same by screwed ends and nuts. At the sides of the furnace and parallel to its
length there are also supported by the said rods to two wing bars or plates Q the
rods passing through lugs made in same and serving to keep the end tubes H
equidistant from one another. Lugs made on the wing bars may for the like
purpose be situated between all the tubes H or separate washers may be strung on
the rods w. The bars or plates Q are perforated with holes and where they curve
round the rods w the pipes H are also perforated so allowing a portion of the air
passing through them to be directed from the sides on to the gaseous products of
combustion.
When charging the furnace with green coal should there be any emission of
smoke the cocks u in the ends of the steam pipes E are partially opened and small
currents of steam are discharged through the nozzles E³ into the pipes F which
currents of steam induce the air currents into and through the said pipes and in
conjunction with them are discharged through the opening G into the furnace the
combined currents having the effect of preventing smoke from the green fuel.
When the fresh fuel has been sufficiently heated the steam is then turned off the
fire bars I are moved into the position shewn and partially heated air is then dis-
charged into the furnace and at the bridge through the pipes H wing bars Q and
pipe D smokeless combustion being thereby supported.
Although the invention is described and illustrated as applied to furnace bars
laid across the furnace, it can also be applied to bars laid lengthway of the furnace
and the system is equally applicable to boilers with underbuilt furnaces and to
furnaces of any type whatever.
With this improved apparatus as compared with the use of ordinary furnace bars
it is found that the lowest quality of fuel may be used firing is less frequent and
nothing but thoroughly burnt ashes gets through the grate so that an undoubted
economy is thereby effected.
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. A furnace bar constructed as hereinbefore described with reference to the
drawings annexed.
2. The combination of furnace bars constructed as described with perforated
tubes for the supply of a forced and induced air draught the bars being supported
on said tubes and operated to open and close the perforations substantially as set
forth with reference to the accompanying drawings.
3. The combination of the air trunks A, pipes H and D, hollow bridge C and
wing bars Q substantially as described with reference to the appended drawings.
4. The combination of the air trunks A steam pipes E and return pipes F,
substantially as set forth with reference to the accompanying drawings.
5. The general arrangement and combination of the apparatus hereinbefore
described with reference to the annexed drawings.
Dated this Nineteenth day of April 1892.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.