FIELD OF THE INVENTION
[0001] The present invention concerns a firebox for an apparatus, advantageously, but not
exclusively, using biomass or biofuel, of the type provided with a device to control
the exit of smoke and fumes from a combustion chamber, when the door of the apparatus
is in an open/closed condition. In particular the present invention concerns a firebox
provided with filter means able to limit to a minimum the emission into the atmosphere
of fine powders, carbon monoxide or other pollutants generated during combustion.
BACKGROUND OF THE INVENTION
[0002] A firebox is known for an apparatus for the combustion of biomass or biofuel in general,
connected to a fireplace, a stove, a boiler or similar, having a base structure conformed
to define at least a combustion chamber and a chimney for drawing the smoke. The combustion
chamber is open at least on one side through a loading or access aperture, hereafter
simply referred to as aperture, for example suitable to allow loading from outside
the chamber and/or the start of combustion and/or inspection.
[0003] The aperture may sometimes be selectively closed by means of a door or other similar
systems.
[0004] One drawback found in the state of the art is to guarantee, with the firebox functioning,
that the chimney is open when the door is open, so as to prevent a considerable outlet
of smoke from the aperture and thus prevent dangers for the operator. It must be remembered
that opening the door during combustion often causes an intense outlet of powders
and ash through the chimney.
[0005] It is known that, in the passage section of the chimney, a choking valve is provided,
for example a butterfly, normally disposed in a segment of the chimney near the combustion
chamber, which serves to choke the transit section of the chimney in order to adjust
the free portion of the section on each occasion.
[0006] A kinematic device is known, for example from the Italian patent
IT-B-1310551, which connects the door to the choking valve so that, when the door is in an open
condition, the choking valve too is completely open, and then returns to the desired
choking condition, once the door is closed.
[0007] It is also known to provide filter means, disposed in cooperation with the chimney,
to reduce to a minimum the emissions into the atmosphere of fine powders, carbon monoxide
or other pollutant elements.
[0008] It is also known to use, in cooperation with the chimney, a filter of the catalytic
type, which, to perform at its best, must operate at temperatures comprised between
250°C and about 450°C.
[0009] Moreover, known filters require frequent maintenance interventions to clean and regenerate
them, interventions which are normally complex and often require specialized personnel.
[0010] In particular, in applications where a choking valve is also provided, the filter
is disposed along the chimney in suitable zones to obtain the functioning in the above
temperature range. Very often these positions are difficult to access for operators,
further complicating maintenance interventions.
[0011] One purpose of the present invention is to obtain a firebox-chimney system for biomass
or biofuel in general, but not exclusively intended for this type of fuel, which is
both simple and economic to produce.
[0012] Another purpose is to obtain a firebox-chimney system which allows both a desired
and controlled choking of the section of the chimney, and a safe and controlled discharge
of the smoke when the door is open.
[0013] It is also a purpose to make a more complete filtering of the smoke exiting from
the chimney for the longest time possible.
[0014] The Applicant has devised, tested and embodied the present invention to overcome
the shortcomings of the state of the art and to obtain these and other purposes and
advantages.
SUMMARY OF THE INVENTION
[0015] The present invention is set forth and characterized in the independent claims, while
the dependent claims describe other characteristics of the invention or variants to
the main inventive idea.
[0016] In accordance with the above purposes, a firebox-chimney system according to the
present invention comprises a base structure conformed to define at least a combustion
chamber and a chimney for the smoke which is open, on one side, toward the combustion
chamber and, on the other side, toward the outside environment. The combustion chamber
is open on at least one side through an aperture which can be selectively closed by
means of a door.
[0017] According to the present invention, the chimney comprises at least a segment of flue
cooperating with the combustion chamber. The segment is provided with a first pipe
and a second pipe for the passage of smoke.
[0018] The first pipe is associated with choking means so as to choke, in a desired and
controlled manner on each occasion, the useful section for the smoke to pass, and
the second pipe is associated with filter means located, according to the direction
of the smoke from the combustion chamber toward the outside, before the first pipe
merges with the second pipe.
[0019] The choking means are associated with the position of the door, so that when the
door is open the choking means are automatically in a position to open the first pipe
and when the door is closed the choking means are automatically in a position to close
the first pipe.
[0020] In an advantageous form of embodiment, connection means are suitable to connect the
door with the choking means, so that when the door is open the choking means are automatically
in the condition of maximum opening. In this condition the maximum drawing of the
smoke through the chimney is guaranteed, avoiding peaks of powders and ash toward
the chimney and the exit of the smoke through the aperture.
[0021] According to one form of embodiment, the connection means are at least partly kinematic.
[0022] According to another form of embodiment, the connection means are at least partly
electric or electromechanical, so that the opening of the door drives a control and
command circuit which governs the opening of the choking means of the chimney.
[0023] In another form of embodiment it can be provided that the connection means can at
least be partly driven in a pneumatic mode.
[0024] In accordance with a first variant, the first pipe defines the proper channel for
the passage of the smoke, while the second channel is placed around the first, that
is, surrounding the first pipe, coaxially for example, to define a toric or circular
space.
[0025] In accordance with a second variant, the first pipe is associated with the second
pipe in the form of a by-pass, that is, one is extarnally adjacent to the other.
[0026] In accordance with a third variant, the first pipe and the second pipe are associated
in proximity to the combustion chamber.
[0027] According to the invention, in the case of the first variant cited, the filter means
are disposed inside the circular space.
[0028] In the case of the second variant, the filter means are present in the second pipe.
[0029] With the solution according to the third variant the filter means are found in an
accessible position in proximity to the combustion chamber.
[0030] Advantageously, therefore, the filter means are in a zone where the temperature of
the smoke always guarantees an operativeness between about 250°C and about 450°C,
and they do not influence the functionality of the choking means.
[0031] Therefore on the one hand it is possible to provided quicker and simpler intervention
steps with consequent reduction in maintenance costs, and on the other hand an optimum
operativity of the filter means is guaranteed and the complete drawing of the smoke
from the chimney is guaranteed when the door is open.
[0032] In one form of embodiment of the present invention, the filter means comprise a rapid
attachment mechanism, for example of the snap-in type, the bayonet or other type,
in order to promote the replacement or maintenance interventions.
[0033] In one form of embodiment, the snap-in attachment mechanism is made, with a first
connection part, on the filter means, and with a second connection part, on an internal
wall of the combustion chamber, in correspondence with the aperture of the chimney
toward the combustion chamber.
[0034] The first connection part and the second connection part are configured to cooperate
reciprocally on a common lying plane transverse to the direction defined by the path
of the smoke along the first pipe and the second pipe. The first connection part is
also suitable to cooperate tangentially in rotation with the second connection part
to selectively pass from an axially released condition to a condition where it is
axially engaged with the internal wall of the chamber.
[0035] In this way, the filter means can be selectively assembled and disassembled inside
the circular space, intervening from inside the combustion chamber and acting on a
simple snap-in attachment mechanism and performing a simple rotation operation and
axial insertion/extraction, without the risk of damaging the filter by dropping it
or through accidental knocks.
[0036] According to a variant, the snap-in attachment mechanism is of the bayonet type in
which the first part comprises two fins which protrude laterally from the filter means,
whereas the second part comprises two brackets attached to the internal wall and defining
with the latter respective housing seatings for the fins of the filter means.
[0037] According to a variant, the brackets are made directly by shaping the internal wall
of the combustion chamber.
[0038] Therefore the assembly of the filter means provides a first step of inserting the
filter means inside the annular space, with the fins in a position angularly offset
with respect to the brackets. Once a condition of complete insertion has been achieved,
the filter means are rotated with respect to their median longitudinal axis, until
the fins are taken inside the relative housing seatings.
[0039] With an inverse movement, that is, with a rotation and a subsequent axial extraction,
the filter means are easily disassembled from the annular space.
[0040] This solution also allows the final user to intervene directly in operations to replace,
regenerate and/or clean the tilter means, without needing the intervention of specialized
personnel.
[0041] According to another variant, the snap-in attachment mechanism is of the elastic
type, that is, with an elastic seal of the filter means when the latter are in position
inside the annular space.
[0042] According to the invention, when the door opens a suitable control and command system
drives the choking means which open the first pipe making the smoke, the powders and
the ash pass through the first pipe, whereas when the door closes the choking means
close the first pipe and the smoke, the powders and the ash transit, at least most
of them, through the filter means.
[0043] According to a variant, the filter means are at least partly of the mechanic type.
[0044] According to another variant, the filter means are at least partly of the catalytic
type,
[0045] According to a variant embodiment, the filter means are mechanical and/or mixed means,
so that there are mechanical means located toward the flame and catalytic means located
toward the exit of the chimney.
[0046] Moreover, in another variant the filter means are at least partly electrostatic.
[0047] In the case where the filter means are of the catalytic type, their position will
be such that the temperature of the smoke which passes through the filter means maintain
the filter means between about 250°C and about 450°C.
[0048] Positioning the filter means in proximity to the combustion chamber allows to provide
quicker and simpler intervention steps, with consequent reduction in maintenance costs
while an optimum operativity of the filter means is guaranteed, and also the complete
drawing of the smoke from the chimney, when the door is open.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] These and other characteristics of the present invention will become apparent from
the following description of a preferential form of embodiment, given as a non-restrictive
example with reference to the attached drawings wherein:
- fig. la and lb respectively show two possible forms of embodiment of the present invention;
- fig. 2 shows a front view of a firebox according to the present invention;
- fig. 3 shows a section from III to III in fig. 2;
- fig. 4 shows a plane view of the firebox in fig.2;
- fig. 5 shows a section from V to V in fig. 2;
- fig. 6 shows a three-dimensional and partially sectioned view of an enlarged detail
of the firebox in tig. 2, in a first operating condition;
- fig. 7 shows a three-dimensional and partially sectioned view of an enlarged detail
of the firebox in fig. 2, in a second operating condition;
- fig. 8 shows a three-dimensional and partially sectioned view of an enlarged detail
of the firebox in fig. 2, in a step of assembling/ disassembling the filter means.
[0050] To facilitate comprehension, the same reference numbers have been used, where possible,
to identify identical common elements in the drawings. It is understood that elements
and characteristics of one form of embodiment can conveniently be incorporated into
other forms of embodiment without further clarifications.
DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT
[0051] With reference to the attached drawings, the number 10 indicates in its entirety
a firebox for a chimney, a stove, a boiler or similar.
[0052] In the case of a chimney or a stove, given here as an example, the firebox 10 comprises
a base structure, or frame 11, having a conformation such as to define a combustion
chamber 12 and a chimney 13.
[0053] The combustion chamber 12 is open toward the outside through a loading or inspection
aperture 15; the aperture 15 can be selectively closed using a door 16, in this case
with a guillotine movement.
[0054] The chimney 13 is open and on one side faces toward the combustion chamber 12 through
an internal wall 17 and on the other side toward the external environment.
[0055] The chimney 13 comprises, at least in an initial part toward the combustion chamber
12, a first pipe 19 and a second pipe 20, which can be disposed one surrounding the
other, advantageously coaxial to each other, (fig. 1a) or adjacent in a by-pass configuration,
that is, not included one inside the other (fig. 1b): the first solution in which
they are advantageously coaxial is preferred, also aesthetically.
[0056] The first pipe 19 defines its own channel 19a for the passage of smoke.
[0057] In some forms of embodiment, the first channel 19 has a reduced diameter compared
to the second pipe 20.
[0058] The firebox 10 also comprises, a choking valve 21, for example a butterfly valve,
disposed in cooperation with the channel 19a, so as to allow the selective variation
of the useful section passage.
[0059] In some forms of embodiment, the choking valve 21 can be selectively driven using
actuator means 21a.
[0060] Advantageously, connection means are suitable to connect the door 16 with the choking
valve 21, so that when the door 16 is open, the choking valve 21 is in a condition
of maximum opening.
[0061] In variant embodiments, the connection means which drive the choking valve 21 in
connection to the door 16 can be a kinematism 22, as shown in fig. 2, connected to
the door 16 and also having, or not, partial adjustment means.
[0062] According to another variant, the connection means which drive the choking valve
21 can be an electric, electromechanical or pneumatic system which provides an opening/closing
sensor for the door 16 and in which, by means of a member, for example of the electric
suction type, said sensor pilots the closing/opening of the choking valve 21.
[0063] The firebox 10 also comprises a filter 23, which is associated, or not, with a mechanical
filter mean, for example a mesh.
[0064] The filter 23 is located, according to the direction of the smoke from the combustion
chamber 12 toward the outside as shown by the arrows F in figs. la and 1b, before
the first pipe 19 merges with the second pipe 20.
[0065] In Some forms of embodiment, the filter 23 is of the catalytic type. In this case,
the filter 23 has an alveolar conformation, that is a honeycomb conformation.
[0066] Merely to give an example, the filter 23 is suitable to filter both the fine powders,
for example PM1 and PM10, and also the volatile organic components, for example OGC,
and also to reduce the carbon monoxide (CO), all of which are generated during combustion.
[0067] According to the example embodiment, the filter 23 comprises a support ring 25 disposed
externally, and from which two attachment fins 26 branch off radially and in diametrically
opposite positions.
[0068] In a coordinated manner, on the internal wall 17 of the combustion chamber 12, the
firebox 10 comprises two attachment brackets 27 which are able to define respective
housing seatings suitable to couple the attachment fins 26. For example, the housing
seatings are open laterally to allow a lateral insertion of the attachment fins 26
inside them. In this case, the attachment brackets 27 are in a position near to the
opening zone of the drawing chimney 13 toward the chamber 12.
[0069] The attachment fins 26 and brackets 27 cooperate reciprocally on a common lying plane,
transverse, advantageously perpendicular, with respect to the direction of travel
of the smoke along the pipes 19, 20, in the example with respect to the median axis
of the chimney 13.
[0070] Moreover, the fins 26 are configured to cooperate tangentially in rotation with the
attachment brackets 27 in order to pass from a condition axially released from the
internal wall 17 to a condition axially engaged, that is, constrained, to the internal
wall 17 and vice versa.
[0071] Hereafter we will show the variant embodiment of the coaxial pipes 19, 20 (figs.
la and 2-8), in which the second pipe 20 is located around the first pipe 19, so that
a circular or toric space 20a for the passage of smoke is defined, distinct and separate
from the channel 19a. It can also be provided that the pipes 19 and 20 are not coaxial
with respect to each other, even though the second pipe 20 is located around or surrounding
the first pipe 19.
[0072] In this variant embodiment, the filter 23 is configured to be housed in the toric
space 20a, providing, to that end, a through aperture 23a, for example in a central
position, in which the first pipe 19 (fig. la) is housed. For example, the filter
23 has a cylindrical shape and a cross section substantially equivalent to the cross
section of the space 20a, so as to substantially occupy all the useful section for
the passage of the smoke.
[0073] In the by-pass variant in fig. 1b, the filter 23 is instead solid and its position,
cooperating with the whole section of the second pipe 20, intercepts all of the smoke
or a part of it, depending on the condition of the choking valve 21, which possibly
passes through the second pipe 20.
[0074] As schematically shown by the arrows L and R in fig. 8, the assembly or vice versa
the dis-assembly of the filter 23, in the space 20a according to the variant in fig.
la, or in cooperation with the whole section of the second pipe 20 as in the by-pass
variant in fig. 1b, occurs by means of two movements, that is, one linear (arrow L)
for the axial insertion of the filter 23 with respect to a longitudinal median axis
of the chimney 13, and one rotational (arrow R), rotating the filter 23 with respect
to the same median axis of the chimney 13, so as to cause the lateral insertion of
the attachment fins 26 into the respective housing seatings and to determine the cooperation
of the attachment fins 26 with the attachment brackets 27 in the axially engaged or
constrained condition. With the inverse movement, the axially released condition of
the filter 23 is obtained, for dis-assembly.
[0075] In particular, in the first variant of fig. 1a the filter 23 is thus correctly positioned
inside the space 20a, as in the second variant of fig. 1b the filter 23 is correctly
positioned inside the second pipe 20, carrying out, in each case, its functions of
filtering the smoke coming from the combustion chamber 12.
[0076] In this same operating condition of the filter 23, the smoke can only pass through
the space 20a, in the first variant, or through the second pipe 20 in the second variant,
and then through the filter 23 in a closed condition of the choking valve 21, or both
through the space 20a and through the channel 19a, in the first variant, or through
the second pipe 20 and through the first pipe 19 in the second variant, in a open
or semi-open condition of the choking valve 21.
[0077] It is clear that modifications and/or additions of parts may be made to the firebox
10 as described heretofore, without departing from the field and scope of the present
invention.
1. Firebox for a combustion apparatus, advantageously but not exclusively using biomass
or biofuel, comprising a base structure (11) defining a combustion chamber (12) and
a chimney (13) for the smoke, a door (16) being present, characterized in that said chimney (13) comprises at least a segment with a flue, cooperating with the
combustion chamber (12), said segment being provided with a first pipe (19) and a
second pipe (20) for the passage of the smoke, said first pipe (19) being associated
with choking means (21) and said second pipe (20) being associated with filter means
(23) located, according to the direction in which the smoke travels from the combustion
chamber (12) toward the outside, before the first pipe (19) merges with the second
pipe (20), said choking means (21) being associated, by means of connection means,
to the position of the door (16), so that, with the door (16) open, the choking means
(21) are automatically in a position of opening the first pipe (19) and with the door
(16) closed the choking means (21) are automatically in a position of closing the
first pipe (19), a snap-in attachment mechanism being provided to associate said second
pipe (20) to said filter means (23), comprising a first connection part (26) made
on said filter means (23) and a second connection part (27) made on an internal wall
(17) of the chamber (12), in correspondence with the aperture of the chimney (13)
toward said chamber (12), said first connection part (26) and said second connection
part (27) being configured to reciprocally cooperate on a common lying plane transverse
to the direction defined by the direction of travel of the smoke along the first pipe
(19) and the second pipe (20), said first connection part (26) being suitable to cooperate
tangentially in rotation with said second connection part (27) so as to selectively
pass from an axially released condition to a condition axially engaged with said internal
wall (17) of the chamber (12).
2. Firebox as in claim 1, characterized in that the connection means which associate the position of the door (16) to the position
of the choking means (21) at least partly consist of a kinematic mechanism.
3. Firebox as in claim 2, characterized in that the connection means which associate the position of the door (16) to the position
of the choking means (21) at least partly comprise electric or electromechanical detection
and/or command means.
4. Firebox as in claim 2, characterized in that the connection means which associate the position of the door (16) to the position
of the choking means (21) at least partly comprise pneumatic means.
5. Firebox as in any claim hereinbefore, characterized in that the filter means (23) comprise mechanical filter means.
6. Firebox as in any claim hereinbefore, characterized in that the filter means (23) comprises catalytic filter means.
7. Firebox as in any claim hereinbefore, characterized in that the filter means (23) comprise electrostatic filter means.
8. Firebox as in any claim hereinbefore, characterized in that it comprises a rapid attachment mechanism comprising a first part (26) made on said
filter means (23) and a second part (27) made on an inside wall (17) of the combustion
chamber (12), in correspondence with the aperture of the chimney (13) toward said
chamber (12).
9. Firebox as in any claim hereinbefore, characterized in that said second pipe (20) is disposed coaxial and external to said first pipe (19), said
first pipe (19) defining a channel (19a) for the passage of smoke and between said
first pipe (19) and said second pipe (20) a circular space (20a) for the passage of
smoke comes to be defined, said filter means (23) being provided inside said circular
space (20a) and being cylindrical in shape with a cross section correlated to the
cross section of said circular space (20a).
10. Firebox as in any claim hereinbefore, characterized in that the snap-in attachment mechanism is of the bayonet type and comprises two fins (26)
protruding laterally to said filter means (23), and two brackets (27) associated with
the internal wall (17) and defining therewith respective housing seatings for said
fins (26).
11. Firebox as in claim 10, characterized in that the brackets (27) are fixed to the internal wall (17) of the combustion chamber (12).
12. Firebox as in claim 11, characterized in that the brackets (27) are directly made by shaping the internal wall (17) of the chamber
(12).
13. Firebox as in any claim hereinbefore, characterized in that the choking means (21) are disposed transverse in the first pipe (19) so as to choke,
in a desired manner, the useful passage section of the channel (19a).
14. Firebox as in any claim hereinbefore, characterized in that the connection means comprise a kinematic connection member (22) suitable to connect
the door (16) with the choking means (21), so that an open condition of said door
(16) corresponds to an open condition of said choking means (21).