[0001] This invention relates to an improved burner for a solid fuel-fired steel construction
boiler.
[0002] Known and available on the market are solid fuel-fired steel construction boilers
for civil heating applications which comprise a space portion of vertically elongate
shape, delimited by longitudinal side walls, a bottom and a cover lined with an interspace
containing water to be heated, as well as . front and rear faces also provided, at
least partially, with a similar interspace.
[0003] Said space portion is subdivided into an upper zone and a lower zone, and a burner
is provided at the subdivision between the two zones; the upper zone is intended for
containing the fuel which is loaded from a door provided in the front face, whilst
in the lower zone, there occurs the development of the flame issuing from said burner
and conveyance of the flue gases toward a smoke box located at the rear face and provided
with a connection to the chimney. Located on the front face is a combustion air metering
unit which comprises an electric fan controlled by an automatic regulating circuit,
and a distribution chamber whence primary air flows out toward the top of the upper
zone of the boiler, whilst secondary air flows out at the burner to complete the combustion.
[0004] The boiler just described has considerable virtues and advantages; however, the burners
proposed up to the present time have failed to provide fully satisfactory characteristics,
but accumulated work experience has allowed the development of an improved burner
which the present patent is directed to protect.
[0005] It is the aim of this invention to provide an improved burner for solid fuel-fired
steel construction boilers, wherein no state of dangerous deformations is encountered
in operation, and which can provide optimum mixing of the products of combustion promoted
by the primary air with the secondary air.
[0006] Within the above aim, it is an object of the invention to provide a burner whereby
the combustion temperature can be pushed to very high values so as to decrease the
excess air and further improve the performance level.
[0007] Another object of the invention is to provide a burner which has those parts which
are most liable to wear out of low cost and readily removable, thereby the damage
is limited to a minimum with the replacement thereof at the end of a useful life cycle.
[0008] The proposed aim, and the mentioned objects, are achieved by an improved burner for
a solid fuel-fired steel construction boiler, according to the invention, said boiler
comprising a space portion lined with an interspace containing water to be heated,
subdivided into an upper fuel-containing zone and lower zone wherein the development
of the flame and conveyance of the flue gases generated from a burner situated at
the subdivision between said upper and lower zones take place, and provided at the
front face with a combustion air metering unit which comprises a distribution chamber
supplied from an electric fan whence primary air flows out toward the top of the upper
zone whilst secondary air flows out at the burner, characterized in that it comprises
a refractory stone block laid in a substantially horizontal plane to delimit the upper
and lower zones of the boiler space portion, provided on the top face with a housing
which has the bottom formed at a substantially center location with a hole adapted
to put into communication said upper and lower zones of the boiler space portion,
and adapted to contain, resting on the bottom at the periphery of the hole, at least
one body formed from a refractory material having at the space portion directly overlying
the hole means of holding the overlying embers, the housing bottom and surface of
said body intended to rest on said bottom being configured to define, on coming into
contact, a ducting opening in correspondence with the hole and communicating with
the air distribution chamber for conveying secondary air.
[0009] Further features and advantages will be apparent from the description of two preferred
but not exclusive embodiments of the invention, as shown by way of illustration and
not of limitation in the accompanying drawings, where:
Figure 1 is a partly exploded view of a first embodiment of the invention;
Figure 2 is a fragmentary sectional view of a boiler incorporating a burner of the
type shown in Figure 1, taken on the plane II-II of Figure 3;
Figure 3 is a section taken on the plane III-III of Figure 2;
Figure 4 is a partly exploded view of a first variation of the invention; and
Figure 5 is a detail view of a fire bar provided in the variation of Figure 4.
[0010] With reference to the cited Figures 1,2,3, generally indicated at 1 is the burner,
which is supported on shelves 2 extending from the walls 3 of the boiler space portion
lined with the interspace or jacket of water 4 to be heated so as to delimit the upper
zone 5a of said space portion containing the fuel, which in the figure is represented
by firewood pieces but could indifferently be coal or any other solid fuel, separating
it from the lower portion 5b wherein the flame development and conveyance of the flue
gases toward a smoke box , not shown in the figure and located at the rear face, take
place; provided in a known manner at the front face is a combustion air metering unit
which comprises the distribution chamber 6 supplied from the electric fan 7, whence
primary air flows out toward the top of the upper zone 5a whilst secondary air is
delivered to the burner 1 as explained hereinafter.
[0011] The burner 1 comprises the refractory stone block 8, with a refractory material 8a
filling at the edges thereof and which has at the top face the housing 9, at the bottom
whereof there is provided the-elongate hole 10 which communicates the upper zone 5a
with the lower zone 5b of the boiler space portion.
[0012] Resting on the bottom of the housing 9, at the edges of the hole 10, are the fire
bars formed from a refractory material 11 and 12 which have on the face confronting
said hole a plurality of facing serrations: clearly visible in Figure 1 are those
of the fire bar 11, respectively indicated at 13,14,15,16, and owing to the particular
choice of the sectional view taken on the plane III-III, also in Fig. 3, a serration
indicated at 15 is visible in elevation; identical and, as mentioned, confronting
them, are the serrations of the fire bar 12, one of which, shown in side elevation,
is visible in Figure 3 and is indicated at 17.
[0013] As is apparent from the drawing figures, the serrations of the fire bars protrude,
without coming into mutual contact, into the space portion overlying the hole 10 with
surfaces which, extending substantially from the edges of said hole, have an inclined
lower portion as at 13a and a substantially vertical upper portion as at 13b, thereby
a means of holding the overlying embers is provided.
[0014] At the face resting on the bottom of the housing the fire bars 11 and 12 have a series
of throughgoing transverse slots: clearly visible in Figures 1 and 2 are those of
the fire bar 12, respectively indicated at 18,19,20,21,22, and the slot 20 is also
visible in the sectional view of Figure 3; as regards the fire bar 11, visible in
Figure 1 are the outlets of the slots 23,24,25,26,27, and the slot 25 is fully visible
in the sectional view of Figure 3.
[0015] The aforesaid slots in the fire bar 12 are in communication with the longitudinal
recess 28, and those in the fire bar 11 with the like recess 29, said recesses 28
and 29 are located to correspond with the holes 28a,29a, respectively, formed in the
block 8 facing holes such as 6a in communication with the distribution chamber for
the combustion air 6.
[0016] In this way, the resting of the fire bars 11 and 12 on the bottom of the housing
9 results in the formation of a ducting at the longitudinal recesses and cross slots
wherethrough secondary air, entering the holes 28a,29a, reaches from the distribution
chamber 6 the space portion directly overlying the hole 10.
[0017] Thus, in the space portion defined by the serrations of the fire bars 11 and 12 and
the hole 10 there is defined a form of pre-chamber where the gas produced by the combustion
of primary air with the fuel overlying the burner, still loaded with combustible substances,
enter from above and combine with the secondary air which is advantageously pre-heated,
to provide a complete combustion which, together with the possibility of pushing much
higher the flame temperature thanks to the contribution afforded by the very refractory
material which has been adopted for the burner construction, ensures optimum performance.
[0018] In addition to this feature, it should be noted that the burner is configured so
as not to develop dangerous deformations, and that those parts of it which are more
liable to wear out, i.e. those in direct contact with the embers, have been formed
of fire bars which are replaceable,with a very simple operation that any user can
carry out, and at very low cost.
[0019] With reference to Figures 4 and 5 a variation of the burner will now be described;
this variation again includes the refractory stone block 8 with housing 9 provided
at the bottom with the hole 10 adapted to put in communication the upper and lower
zones of the boiler space portion, and at the edges of the hole 10 there are laid
onto the flat bottom of the housing the two fire bars 30 and 31 of refractory material
which have, similarly to what has been described for the fire bars 11 and 12, the
surface intended to rest onto the bottom formed with throughgoing cross slots 32,33,34,35,36
for the fire bar 30, in communication with longitudinal recesses such as 37 intended
for arranging themselves at the holes 28a,29a formed in the block 8 for admitting
secondary air at the burner.
[0020] The embers holding means overlying the hole 10 with which the fire bars 30 and 31
are equipped in this variation comprises a metal grid which is constructed in several
parts to avoid dangerous deformations, and is accordingly formed by the round cross-section
rods 38 and 39, intended to arrange themselves in corresponding alignment at the axis
of the hole 10 following resting of the cross-pieces 38a,38b and 39a,39b with which
they are provided in the cutouts 40,41, 42,43 of the fire bar 30 and confronting cutouts
44, 45,46,47 of the fire bar 31.
[0021] The invention described herein is susceptible to many other modifications and variations,
all of which fall within the purview of the inventive concept: thus, as an example,
the fire bars inserted into the housing provided in the refractory stone block may
be replaced with a monolithic body, or a series of modular elements, and the secondary
air conveying ducting may be formed, at least in part, on the bottom of said housing.
[0022] In practicing the invention, all of the details may be replaced with other, technically
equivalent elements; further, the materials used, as well as the shapes and dimensions,
may be any ones.
1. An improved burner for a solid fuel-fired steel construction boiler, said boiler
comprising a space portion lined with an interspace or jacket containing water (4)
to be heated, subdivided into an upper fuel-containing zone (5a) and a lower zone
(5b) where the flame development and conveyance of the flue gases which are generated
in a burner (1) located at the separation between said upper and lower zones (5a,
5b) take place, and provided at the front face with a combustion air metering unit
which comprises a distribution chamber (6) supplied from an electric fan (7) whence
primary air flows out toward the top of the upper zone (5a) whilst secondary air flows
out at the burner (1), characterized in that it comprises a refractory stone block
(8) laid in a substantially horizontal plane so as to delimit the upper zone (5a)
and lower zone (5b) of the boiler space portion, provided on the top face with a housing
(9) which has the bottom formed at a substantially center location with a hole (10)
adapted to put into communication said upper and lower zones (5a, 5b) of the boiler
space portion, and is adapted to contain, resting on the bottom at the periphery of
the hole (10), at least one body (11,12,30,31) formed from a refractory material provided
at the space portion directly overlying the hole with a means of holding the overlying
embers (13-16,38-39b),the housing (9) bottom and surface of said body (11,12,30,31)
intended to rest on said bottom being configured to define, when brought into contact,
a ducting (28,29) opening at the hole (28a,29a) and communicating with the air distribution
chamber (6) for conveying secondary air.
2. A burner according to Claim 1, characterized in the fact that the refractory stone
block (8) has a substantially parallelepipedal shape and is supported on shelves (2)
extending from walls (3) and faces of the boiler space portion.
3. A burner according to one or more of the preceding claims, characterized by the
presence of a filling of a refractory material (8a) between the refractory stone block
(8) and at least the walls (3) of the boiler space portion.
4. A burner according to one or more of the preceding claims, characterized in that
the housing (9) provided in the refractory stone block (8) is adapted to contain two
fire bars (11,12,30,31) formed from a refractory material and resting on the flat
bottom at the edges of an elongate hole (10), provided with a means (13-16) of holding
the overlying embers consisting of confronting serrations (13-16) which protrude monolithically
therefrom, without coming into contact, in the space portion directly overlying said
hole (10), extending substantially from the edges of the hole (10) with a surface
which has an inclined lower portion (13a) and a substantially vertical upper portion
(13b), each of said fire bars (11,12,30,31) being further provided, at the face resting
on the housing bottom, with throughgoing cross slots (18-27), communicating with a
longitudinal recess (28,29) located at a hole (28a,29a) formed in the refractory stone
block (8)_communicating with the combustion air distribution chamber (6) for admission
of secondary air.
5.A burner according to one or more of the preceding claims, characterized in that
the housing (9) provided in the refractory stone block (8) is adapted to contain two
fire bars (11,12,30,31) formed from a refractory material resting on the flat bottom
at the edges of an elongate hole (10), provided with a means of holding the overlying
embers consisting of a metal grid (38-39b) adapted to rest in special cutouts (40-47)
formed at the edge adjacent to the hole of the top surface thereof, each of said fire
bars (30,31) being also provided, at the face resting on the bottom of the housing
(9), with throughgoing cross slots (32-36) communicating with a longitudinal recess
(37) located at a hole (28a,29a) formed in the refractory stone block (8) communicating
with the combustion air distribution chamber (6) for admission of secondary air.
6. A burner according to one or more of the preceding claims, characterized in that
the metal grid comprises a plurality of a round cross-section rods (38,39) adapted
to arrange themselves aligned at the longitudinal axis of the underlying hole (10),
each of which is provided with at least two crosspieces (38a,38b,39a,39b) resting
in the fire bar cutouts (40-47).
7. An improved burner for a solid fuel-fired steel construction boiler, characterized
in that it comprises one or more of the features described and/or illustrated.