Improvements in Fire-grates for Steam Boiler and other Furnaces.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Fire-grates for Steam Boiler and other Furnaces.
I, MANUEL GROSSO, of 17, Calle de los Reyes Catolicos, Seville, in the Kingdom
of Spain, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to fire-grates for steam boiler and other furnaces whereby
they are adapted for the complete combustion of any kind of fuel, either large
or small, and allow scarcely anything to pass through the bars except the ashes
produced.
This object is attained by narrowing the necessary air-passages to the extreme
limit requisite for the combustion of the class of fuel to be burnt, but increasing
the development of the said air-passages, in such a manner that each particle
of fuel shall be surrounded by air, thus utilizing the greater portion of the
oxygen, by perfect contact with the fuel. It is necessary for this purpose, that
the solid bars, on which the fuel rests, shall in their shape combine the minimum
of surface with the maximum perimeter, and the necessary conditions of symmetry.
durability and facility in casting the said bars.
I obtain this result by making the bars of "cruciform" shape and so placing
them that the spaces separating them constitute a large number of air passages
of zigzag form, the projecting and receding angles and short straight lines of
which subdivide the air and distribute it between the surface of the grate and
the fuel, thereby tending to raise the latter and preventing clinker from adher-
ing to the bars of the grate and the consequent heating of the latter. This is
highly advantageous as I both increase the life of the bars and promote proper
combustion owing to the temperature of the air being raised by the heat which
it absorbs from the bars.
The access of the air is also provided for in an improved manner by the wide
separation of the lower parts with relation to the narrow spaces between the
top parts.
The low temperature at which the bars are kept and their "cruciform" shape
prevent their distortion and the rapid wearing away which occurs in other grates
and also facilitate the work of cleaning.
Experiments which I have made with these fire-grates have proved the correct-
ness of the above stated characteristics and have also resulted in a considerable
economy in fuel, due to the perfect combustion and to the small proportion, if
any, of small coal, which falls through into the ash-pit, in comparison with other
systems.
The arms of the crosses are made of conical shape, whereby the entrance of
the air and the falling of the ashes are facilitated.
In order to form a clear idea of the principle on which the special shape of
these bars is founded, it will be necessary to imagine an ordinary grate bar,
crossed by others of equal thickness, which are cut on each side diagonally to
the vertical line, until at the half of their thickness they disappear, this con-

page_text: stituting the transverse arm of the cross. In the longitudinal arms which are
equal to the former, the bars are cut at the intermediate point to the transverse
arms, and in the same conditions as aforesaid, by planes diagonal to the vertical,
but only through about one third of the thickness of the bar, thus producing a
cross, with arms of equal length and with a large entrance for air and an easy
exit for the ashes.
To constitute the grate it is only necessary to alternate the heads from left
to right, or vice versa, thus interlocking them and forming the zig-zag passages
hereinbefore referred to.
0~1
100
I, MANUEL GROSSO, of 17, Calle de los Reyes Catolicos, Seville, in the Kingdom
of Spain, 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:---
My invention relates to fire-grates for steam boiler and other furnaces whereby
they are adapted for the complete combustion of any kind of fuel, either large
or small, and allow scarcely anything, except ashes, to pass through the bars.
This object is attained by narrowing the necessary air-passages to the extreme
limit requisite for the combustion of the class of fuel to be burnt, but increasing
the development of the said air-passages, in such a manner that each particle
of fuel shall be surrounded by air, thus utilizing a greater proportion of the
oxygen than hitherto by bringing it into close contact with the whole of the
fuel. It is necessary for this purpose, that the solid bars, on which the fuel
rests, shall in their shape combine the minimum of surface with the maximum
perimeter, and the necessary conditions of symmetry, durability and facility
in casting the said bars.
I obtain this result by making the bars of "cruciform" shape and so placing
them that the spaces separating them constitute a large number of air passages
of zigzag form, the projecting and receding angles and short straight lines of
which subdivide the air and distribute it between the surface of the grate and
the fuel, thereby tending to raise the latter and preventing clinker from adher-
ing to the bars of the grate and the consequent heating of the latter. This is
highly advantageous as
both increase the life of the bars and promote proper
combustion owing to the temperature of the air being raised by the heat which
it absorbs from the bars.
The access of the air is also provided for in an improved manner by the wide
separation of the lower parts with relation to the narrow spaces between the
top parts.
The low temperature at which the bars are kept and their "cruciform" shape
prevent their distortion and the rapid wearing away which occurs in other grates
and also facilitate the work of cleaning.
Experiments which I have made with these fire-grates have proved the correct-
ness of the above stated characteristics and have also resulted in a considerable
economy in fuel, due to the perfect combustion and to the small proportion, if
any, of small coal, which falls through into the ash-pit, in comparison with other
systems.

page_text: The arms of the crosses are made of conical shape, whereby the entrance of
the air and the falling of the ashes are facilitated.
In the accompanying drawings:-
Figure 1 is a longitudinal elevation of one of the bars of my improved furnace
grate;
Figure 2 is a plan shewing four bars placed in position; and
Figure 3 is a transverse section on the line A B, Figure 1.
The arms of the crosses are, as shewn in Figures 1 and 3, made of conical shape,
whereby the entrance of the air and the falling of the ashes are facilitated.
These figures also shew the distance between the bars, and Figure 2 shews the
shape of the top portions of the solid bars of the grate, which, alternating and
located each within the adjacent bars on all sides, form the air-passages.
In order to form a clear idea of the principle on which the special shape of
these bars is founded, it will be necessary to imagine an ordinary grate bar,
crossed by others of equal thickness which are cut on each side diagonally to
the vertical line, until at the half of their depth they disappear at c, c, c, this
constituting the transverse arms d, e of the cross. In the longitudinal arms f, y
which are equal to the transverse arms the bars are cut at a point intermediate
of the transverse arnis and in the same conditions as aforesaid, by planes
diagonal to the vertical, but only through about one third of the depth of the
bar, thus producing a cross, with arms of equal length and with a large entrance
for air and an easy exit for the ashes through the interstices h, h, h.
To build up a grate it is only necessary to place the bars side by side with
the transverse arms of the crosses of one bar located between the transverse arms
of the adjacent bars thereby forming the zigzag passages herein before referred
to.
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:-
..I. A fire-grate for steam boiler and other furnaces constructed and arranged
substantially as hereinbefore described and illustrated in the accompanying
drawing.
2. The manufacture and use of fire bars of "cruciform" shape, at the top,
which bars when put together form a furnace grafe as described and illustrated
in the accompanying drawing.
G. F. REDFERN
Co.,
4, South Street, Finsbury, London, Agents for the Applicant.