ES2258324T3 - BURNER ASSEMBLY AND BURNER HEAD FOR FUEL / COMBURENT GASEOUS BLENDS. - Google Patents

Abstract

A burner assembly (1, 101) of the so-called complete premixing type comprises a supporting body (2) provided with means for delivering a fuel/comburent gaseous mixture to a burner head (3) provided with at least one gas-permeable wall (4, 104a,b) for delivering the gaseous mixture. In the burner head (3), a plurality of delivery sections (3a, 3b) are defined, which may be independently fed with respect to each other and which are separated in a fluid-tight manner upstream and at the gas-permeable wall (4, 104a,b). In addition to providing a high efficiency of combustion and achieving a reduction of noise, environmental impact, size and cost, the burner assembly (1, 101) of the invention achieves - the nominal power being the same - a significantly greater capacity of modulation with respect to that of a conventional aerated, blown or pre-mixed burner assembly. <IMAGE>

Description

Burner and burner head assembly for gaseous fuel / oxidizer mixtures.

Field of the Invention

The present invention relates to a set of burner of gaseous fuel / oxidizer mixtures and, respectively, to a combustion module and a boiler that includes the aforementioned burner assembly.

More specifically, the present invention is refers to a burner assembly of the complete premixed type for a civil use heating system, that is, a set of burner capable of combusting a gaseous mixture in which the fuel and the oxidizer are mixed previously (mixture stoichiometric or with a slight excess of air) according to a proportion adapted to ensure complete combustion of gas fuel.

Background of the invention

In the field of gas heating systems low power, such as boilers Combined or condensing boilers for domestic use, have known to use burner assemblies for a long time, which they comprise a burner head provided with a plurality of openings to distribute a gaseous mixture of fuel / oxidizer ignited by an ignition electrode. The mixture is sent to said head through a feeding medium suitable comprising a conduit, through which a gaseous oxidizer, usually air, and a gaseous fuel, generally gas, supplied by the distribution network public

A first type of burner assemblies widespread in the market includes the so-called "aerated" burner assemblies in which the air from the combustion is partially premixed with combustible gas upstream of the burner body (primary air) and partially injected downstream of it to complete the combustion (secondary air).

In British patent application GB 2 213 924A, an example of a burner body for assemblies is described airy Said burner body comprises a pair of sections independent that feed individually, respectively, with a gas / air gas mixture that includes only primary air and with a gas / air gas mixture that includes a smaller amount of air, or simply with gas without any added air. In in particular, said burner body is especially suitable for produce a marbled flame of various colors that is particularly nice from an aesthetic point of view.

However, in order to carry out a combustion as complete as possible, the burner assemblies aerated must necessarily operate with excess air considerable with respect to the stoichiometric relationship; saying Excessive air results in a series of inconveniences, such as practical impossibility of reducing the size of the burner body due to the consequent low flame density, the emission of a large amount of harmful gases, especially nitrogen oxides (NOx), and limited combustion efficiency.

As an alternative to burner assemblies aerated, and in the range of thermal powers above approximately 50 KW, the use of so-called "blown" burner assemblies, which have no body burner, and by means of which a flame is generated very turbulent independently supplying the gaseous fuel and combustion air to a mixing area that is located immediately upstream of the flame. Generally, the blown burner assemblies comprise for this purpose a plurality of nozzles to supply the gaseous fuel, around the which air is supplied at high speed by means of a blower.

Although blown burner assemblies have been widely widespread in the market, they have many undesirable inconveniences, among which are the high level of flame noise and a limited modulation capacity of the thermal power (not exceeding 3: 1) with respect to the requirements Current users.

In order to somehow overcome the drawbacks mentioned above, it was proposed, especially in low power heating systems for domestic use (en that is, for thermal powers not exceeding 50 - 60 KW) - the use of so-called premixed burner assemblies complete, comprising a current mounted mixing duct down or upstream of an air feed blower, and a gas supply duct.

In fact, said burner assemblies, which are fed with gas / air mixtures comprising the total amount of air necessary for combustion, ensure combustion substantially complete fuel gas also when used small burner bodies, and allow to achieve greater combustion efficiency, lower environmental impact, smaller sizes and a lower cost with respect to the sets airy

European patent application EP 0331037, for example, describes a complete premixed burner assembly capable of ensuring complete combustion of gaseous fuel, to reduce the production of nitric oxides.

Said burner assembly comprises a plurality of first burner bodies to supply a first gaseous fuel / oxidizer mixture that has a high fuel concentration, and a plurality of second bodies of burner located, respectively, between said first bodies of burner, to supply a second gaseous mixture of fuel / oxidizer that has a low concentration of fuel.

Said first and second burner bodies are fed independently by respective ducts of Supply and mixing.

European patent application EP 0 866270, for other part, describes a complete premixed burner assembly in which the combustion air is supplied by a blower and combustion gas is supplied in a regulated manner by from individual ducts to burner zones. To connect and disconnect gas supply to burner areas individual, open / close valves are available in the corresponding individual flue gas ducts.

However, also the burner bodies of Complete premixed mentioned above have some drawbacks that have not been overcome so far and that limit their distribution in the market.

A first drawback refers to its limited thermal power modulation capacity (which is typically in the environment of 5 - 6: 1) with respect to the current requirements of users (think only of, for example, combining boilers, where the energy necessary for the production of sanitary water hot grows continuously, where the energy needed to Domestic heating decreases continuously due to high insulation levels of modern homes).

A second drawback is related to the fact that the previous benefits of smaller and smaller sizes costs can be achieved, with the available components currently manufactured on a large scale, only for a limited range of thermal powers (not exceeding 50 - 60 KW), while the achievement of greater powers remains a feature of the sets of aerated or blown burner mentioned above.

Another different type of burner assemblies known in the art are the so-called "burners hybrids "that combine the characteristics of the burner "aerated" and those of a catalytic burner. The application of Japanese patent JP 60-026210 reveals a set of burner of this type comprising a mixing tube in gaseous communication with a sheet-shaped catalyst. The tube mixing is divided into two passages by a wall of partition so that, in operation, combustible gases injected into the defined passageways inside the tube mixed suck primary air from the edge of the opening of the themselves, whereby the mixture of gas and air flows into separate combustion parts in order to make it emitted towards and burned in a wire net.

Summary of the invention

The fundamental technical problem of this invention is to propose a low cost burner assembly and Easy manufacturing of the complete premixing type, on the one hand, to achieve a wide range of thermal power modulation and, on the other hand, to produce a thermal power comparable to the of aerated or blown burner assemblies.

According to a first aspect of the invention, said problem is solved by means of burner assemblies of Complete premixed defined in the attached claim 1.

Thanks to the presence of several sections of distribution of the complete premix, which are separated alternatively tightly to fluids and that can be independently feed, the burner assembly of the invention conveniently enables the achievement of a range of modulation of thermal power that is significantly more wide than that of aerated, blown or blower burner assemblies premixed prior art, said range being equal to the sum of the modulation ranges attainable for each section of distribution.

In addition, thanks to the presence of sections of distribution that can be fed independently, the burner assembly of the invention conveniently enables ensure said wide range of modulation of thermal power not only for those powers that until now could only be achieved by aerated or blown burners (powers between 100 and 120 KW), but also for reduced thermal powers (of a order between 20 and 30 KW) by simply selecting the size of the medium used to supply the gaseous mixture of fuel / oxidizer to each application section.

In fact, the total nominal thermal power of the burner assembly of the invention is almost equal to the sum of the individual thermal powers that can be produced independently for each of the distribution sections of the burner body

In addition, unlike the burner body of the aerated assemblies described in the GB patent application 2213924 mentioned above, such convenient features may be achieved without any derivation of the gaseous mixture of a distribution section to another, substantially avoiding this way the risk of undesirable flame returns in the section that It is not being fed.

Moreover, the burner assembly of the invention makes it possible to carry out the combustion of the mixture of fuel / oxidizer supplying this not only in the direction vertical and from bottom to top, as in the case of sets of aerated burner of the prior art, but also, supplying the fuel / oxidizer mixture laterally, or of top to bottom, to the benefit of its flexibility of use.

According to a first embodiment of the burner assembly of the invention, said gas permeable wall of the burner body consists essentially of a wall provided with a plurality of holes to distribute the mixture Fuel / oxidizer soda. Conveniently said wall perforated can be obtained by configuring and drilling a material suitable metal by means of forming operations conventional ones that can be carried out on a large scale and low cost.

According to an alternative embodiment, said Gas permeable wall of the burner body is constituted essentially by a sheet of suitable porous material permeable to the gases.

The use of a gas-permeable porous sheet allows, conveniently, to confine the combustion phenomenon of the gaseous fuel / oxidizer mixture substantially inside the sheet or, at most, immediately above it with the presence of free flames of reduced height that distribute regularly over the entire surface of the sheet.

In other words, and unlike the body of perforated wall burner, in which heat is transmitted to the heat exchanger located downstream of the set of essentially convection burner, in this case the heat is essentially radiant with a smaller convective component.

Therefore, thanks to the use of a sheet Gas permeable porous, it is possible to achieve a number of benefits important, among which are the following:

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Obtaining a homogeneous distribution of the heat of combustion on the entire surface of the lock;

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Achievement high temperatures, up to about 1000 ° C, on the wall gas permeable from the burner body;

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Achievement of a reduced pressure drop across the wall permeable to gas;

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Reduction of the distance between the primary heat exchanger, located downstream of the burner assembly, and burner body, without any danger of flame temperature reduction, if present, up to values such as to make incomplete combustion with the undesirable production of carbon monoxide.

The reduction of said distance makes it possible, to in turn, reduce the size of the combustion chamber and, therefore therefore, that of the boiler equipped with the burner assembly with with respect to the prior art boilers thereof power.

Preferably, the gas permeable porous sheet It is made of a porous ceramic suitable for this purpose, such as, for example, the ceramic available in the market with the name of "ceramic foam" (ECO CERAMICS, BEVERWIJK, The Netherlands).

According to the invention, the means for supply the gaseous fuel / oxidizer mixture to each burner body distribution section comprises at least a conduit in fluid communication with a respective blower and a respective gaseous fuel supply conduit.

Conveniently, the distribution sections of the burner body can be fed individually using Simple structurally small components and low cost, which are used both in the manufacture of burner assemblies and in other technical fields, such as personal computers, Copying machines, household appliances, etc.

That is, the burner assembly of the invention is especially simple from a point of view constructive, and has a reduced cost.

In an embodiment of the present invention especially convenient, the distribution sections of the Fuel / oxidizer gas mixture are arranged in series, and can be fed individually from feeding chambers respective coaxial

Beneficially, the burner body can have essentially cylindrical shape, so that it is inserted properly in the heat exchangers used in the annular water heating systems for civil use.

According to an alternative embodiment, the distribution sections of the gas mixture of fuel / oxidizer are arranged in parallel, and can be feed individually through feeding chambers respective located in the burner body upstream of said at least one gas permeable wall.

Preferably, the feeding chambers they are alternately divided gas tightly by at least a partition plate mounted on the burner body essentially along its entire length or width and that can extend vertically or horizontally.

According to another embodiment, the body of the burner comprises a couple of distribution sections that are substantially semi-cylindrical and longitudinally tapered, arranged coaxially in parallel with each other.

Conveniently, said embodiment of the body of the burner can be properly coupled with heat exchangers heat of water heating systems for civil use.

According to the invention, the set of burner of the present invention further comprises a means for intercept said at least one conduit of the gas mixture of fuel / oxidizer, said means being located upstream of the distribution sections of the gas mixture of fuel / oxidizer.

Beneficially, this makes it possible to prevent risk of an undesirable return of combustion gases from fuel into the burner assembly through any possibly not fed section of the burner body in case of obstruction of the gas elimination ducts located downstream of the burner assembly.

In an embodiment of the burner assembly of the invention, the interception means comprises a valve retention provided with a mechanical actuator that includes a spring suitable made of a metallic material with shape memory, such such as special nickel and titanium alloys available in the market.

Conveniently, it is possible to obtain, in this case, a so-called "infallible" interception system that It closes automatically in case of failure.

Preferably, the burner assembly of the invention further comprises an ignition electrode and a detector flame both located at a predetermined distance from the wall gas permeable from the burner body, and if necessary, close of a respective end of one of the respective sections of distribution.

In this way, the mixture distributed by one of The burner body sections are lit by the electrode of ignition, while the mixture distributed by the (s) contiguous section (s) is (are) lit (s) as a result of the flame produced by the first section without the presence of other electrodes of ignition.

In an embodiment of the invention, the sections distribution provided in the burner body are arranged parallel to each other, and are arranged essentially layered and to cloth, while the ignition electrode is located operatively to generate a spark of ignition on horseback same sections.

Conveniently, in this case it is possible to choose at will which distribution section should be turned on, thus making it possible to properly program the operating time and, consequently, the corresponding wear of the blowers designed to supply the gaseous fuel / oxidizer mixture. to the sections of
distribution.

In another embodiment of the invention, the blower or blowers are provided with a box-shaped body that is integral, at least partially, with the support body of the burner set. In this case, it is conveniently possible not only reduce the number of components and, consequently, the cost of the burner assembly, but also further reduce its size with with respect to the prior art sets thereof power.

Preferably, the burner assembly it also comprises a means for its detachable connection to a boiler.

In this way, it is conveniently possible install the burner assembly of the present invention in any type of boiler to replace a burner assembly blown aeration or pre-existing complete pre-mixed for the purpose to increase the modulation capacity of the same boiler and / or the range of thermal powers that can be achieved.

In a second aspect of it, the present invention refers to a combustion module adapted for its assembly in a gas boiler, comprising a burner assembly of the type described above.

In a third aspect thereof, the present invention relates to a gas boiler comprising an assembly of burner of the type described above.

Brief description of the drawings

Other features will become apparent and Benefits of the present invention by reading the following description detailed of a preferred embodiment, made by way of illustration and not of limitation, referring to the attached drawings, in those who:

- Figure 1 shows a perspective view, partially in section, of a first embodiment of the set of burner of the present invention;

- Figure 2 shows a perspective view enlarged, partially in section, of a second embodiment of the burner body of the burner assembly of figure 1;

- Figure 3 shows a perspective view enlarged, partially in section, of a third embodiment of the burner body of the burner assembly of figure 1;

- Figure 4 shows a perspective view, partially in section, of a fourth embodiment of a body of burner of the burner assembly of figure 1;

- Figure 5 shows a perspective view, partially in section, of a combustion module adapted to be mounted in a boiler, which incorporates a second embodiment of the burner assembly of the present invention;

- Figure 6 shows a perspective view enlarged, partially in section, of some details of the set of burner and combustion module of figure 5.

Detailed description of preferred embodiments

Referring to figures 1-4, in the they are generally indicated by numeral 1 a set of Complete premixed burner according to the invention.

The burner assembly 1 comprises a substantially parallelepiped box-shaped support body 2, adapted to support in a known manner " per se " an essentially tubular burner head 3, provided with at least one gas permeable wall which, in this example , is formed by a perforated wall 4 comprising a plurality of openings 5, adapted to distribute a gaseous fuel / oxidizer mixture.

Burner head 3 comprises a pair of structurally independent distribution sections 3a, 3b each other and separated upstream and into the perforated wall 4 of fluid tight way.

Preferably, and in order to improve the necessary fluid tightness between sections 3a, 3b of distribution in perforated wall 4, burner head 3 is provided with an unperforated area 40 adapted to divide the wall 4 perforated in two adjacent parts 4a, 4b, each part being in fluid communication with said distribution sections 3a and 3b, respectively.

Sections 3a, 3b of distribution are arranged in series with each other, and are in fluid communication with a suitable medium 6 adapted to independently feed each of them with respective gaseous mixtures of fuel / oxidizer.

The medium 6 is supported by the body 2 in box shape, and comprises an outer conduit 7 of larger diameter, which is defined by an unperforated part of head 3 of the burner and an inner duct 8 of smaller diameter, which extends coaxially inside the duct 7.

The coaxial ducts 7 and 8 mentioned above are in fluid communication with respective blowers 9, 10 adapted to supply a gaseous oxidizer, for example air A, and with respective ducts 11, 12 adapted to supply a gaseous fuel, for example natural gas G, which extend current under valves 13, 14 adapted to intercept and adjust the flow of gas supplied to head 3 of the burner.

Blowers 9 and 10, in turn, are provided with suction ducts 16, 17 in the form of a communication box fluid with a single air inlet opening 18 inside the body 2, and with box-shaped distribution ducts 19, 20 respectively connected to the outer conduit 7 and the conduit 8 inside of burner head 3.

In the example shown in Figure 1, the complete pre-mixed air and fuel current takes place below blowers 9 and 10 in ducts 19 and 20 of distribution and possibly also in coaxial ducts 7, 8 of burner head 3 3.

In an alternative embodiment, not shown in the drawings, the gaseous fuel can be supplied current above blowers 9 and 10 - in this case of the watertight type gas- thus achieving an entirely more homogeneous mixture between the combustible gas and the combustion air.

According to the invention, the conduit 20 of box-shaped distribution of blower 10 is provided with a suitable means, in this case a shutter valve 21, adapted to intercept the inner duct 8 of the head 3 of the burner.

Therefore, in the burner head 3 they are defined two coaxial power chambers that are constituted, respectively, by an annular space 15, which extends between coaxial ducts 7, 8 and through a chamber 38 cylindrical These feeding chambers are separated from each other. gas tightly by an annular partition plate 39, which is peripherally welded to unperforated area 40 of head 3 of the burner

In this way, a first fluid path is defined in the annular space 15, through which a first mixture of gas / air that feeds the distribution section 3a of the head 3 of the burner

A second fluid path through which a second gas / air mixture is adapted to feed independently and separately section 3b of distribution of burner head 3 and is also defined in conduit 8 inside and in cylindrical chamber 38.

The burner assembly 1 is also provided with an ignition electrode 22 and with a flame detector 23 supported at one end of the distribution section 3a, at a predetermined distance from wall 4 of head 3 of the burner.

Conveniently, burner assembly 1 is provided with a pair of coaxial tubular elements 24, 25, externally supported around burner head 3, adapted to protect the ignition electrode 22 and the detector 23 of accidental impact flame during installation.

Finally, the burner assembly 1 comprises a tab 66 adapted to enable its installation in a conventional boiler, not shown in the figure.

In the example shown, tab 26 is provided with a plurality of trapezoidal wings 27 which, in turn, are provided with respective seats 28 adapted to engage a clamp bolt -not shown- integral with the body of the boiler.

In use, the burner assembly 1 of the invention allows combustion of premixed mixtures of gas / air producing a thermal power that, according to the size and with the distributable flow of blowers 9, 10 and valves 13, 14, may be of the order of 20-30 KW, which is enough for single-floor heating, up to 100-120 KW, It can provide heating for a block of flats.

In both cases, the thermal power produced is it can modulate very easily and reliably in a range of up to 10: 1

Indeed, feeding section 3a of distribution of burner head 3 with the first mixture of fully premixed gas / air formed in conduit 19 of distribution of the blower 9 and flowing through the annular space 15 defined between ducts 7 and 8, it is possible to reach approximately 50% of the maximum nominal power modulating its value in a range of approximately 5: 1.

Conveniently, the distributed mix radially by section 3a of burner head 3 is ignited by electrode 22, while flame detector 23 indicates the current presence of combustion to the control panel electronic.

Beneficially, in this operational state the fluid tight division between sections 3a and 3b of distribution of burner head 3, which is secured upstream and in the wall 4 perforated by the sheet 39 of annular partition and, respectively, by the unperforated area 40, prevents unwanted bypass of the first gas / air mixture from section 3a to adjacent section 3b that is not in operation temporarily, thereby substantially reducing the risk of dangerous flashbacks.

Conveniently, in addition, the valve 21 of seal intercepts the conduit 8 inside the head 3 of the burner to prevent unwanted returns of gases from the combustion through adjacent section 3b, temporarily in operation, in case of accidental clogging of the duct gas removal from the boiler.

If the thermal power demanded to set 1 of burner is greater than 50% of the maximum nominal power, the second fully premixed gas / air mixture formed in the distribution duct 20 of the second blower 10 and flowing through the inner duct 8 and the cylindrical chamber 38 is supplied to the distribution section 3b of the burner head 3 for reach 100% of the maximum nominal power.

Also in this case, it is possible to carry out a power modulation in an additional 5: 1 similar range with respect to the adjustment range that can be carried out feeding the distribution section 3a to reach the range of 10: 1 total modulation mentioned above.

Conveniently, the distributed mix radially by section 3b of burner head 3 is lit by the flame already present near section 3a of contiguous distribution, and ignition electrode is not necessary additional some.

Figures 2-6 schematically show others embodiments of burner head 3 of burner assembly 1 according to the invention.

In the following description and in these figures, the elements of set 1 of structural equivalent burner or functionally to those previously illustrated by referring to the Figure 1 shall be indicated with the same reference numerals, and not They will be described again.

In the embodiment shown in Figure 2, the distribution sections 3a, 3b of burner head 3 are arranged in parallel with each other and can be fed individually by respective feed chambers 42, 43 defined upstream of the wall 4 perforated within essentially semi-cylindrical ducts 29, 30 arranged arranged and separated from each other in a gas tight manner by a sheet 31 of partition.

Conveniently, said partition plate is mounted vertically tightly, for example welded, in the burner head 3 in an unperforated area and substantially along the entire length of it.

Semi-cylindrical ducts 29, 30 are each one provided with a perforated side wall that defines the parts 4a and 4b, respectively of the perforated wall 4 so that the distribution sections 3a, 3b can distribute radially and out the first and second gas / air mixtures, respectively.

In this case, the fluid tight division desired between the distribution sections 3a and 3b of the head 3 of the burner is secured upstream and to wall 4 perforated by partition plate 31 and area 40 not perforated, respectively, thus preventing the unwanted deviation of the first gas / air mixture of the section 3a to adjacent section 3b when it is not temporarily in operation.

Similar to what was disclosed with reference to the first embodiment of burner assembly 1, the mixture of gas / air distributed by section 3a is ignited by the electrode 22 (not shown), while the gas / air mixture distributed by section 3b is ignited by the flame already present externally to the adjoining distribution section.

In the embodiment shown in Figure 3, the distribution sections 3a, 3b are arranged in parallel each other, and can be fed individually by the respective feed chambers 44, 45 that are defined upstream of the wall 4 perforated within two ducts 32, 33 essentially semi-cylindrical, respectively, superior e bottom, arranged coupled and separated in a gas-tight manner by a partition plate 34.

Conveniently, said partition plate is mounted horizontally tightly, for example welded, in burner head 3 in unperforated area 40 and substantially along its entire length.

Semi-cylindrical ducts 32, 33 are each provided with a perforated side wall that defines the parts 4a and 4b, respectively, of the perforated wall 4.

In this case, the fluid tight separation desired between the distribution sections 3a and 3b of the head 3 of the burner is secured upstream and on wall 4 perforated 4 by the partition plate 34 and, respectively, by the unperforated area 40, thus preventing deviation unwanted of the first gas / air mixture of section 3a to the contiguous section 3b when it is not in operation temporarily.

In this case, the gas / air mixture distributed by the bottom section 3a is ignited by electrode 22 (not sample), while the gas / air mixture distributed by the section 3b is ignited by the flame present externally to the distribution section below that tends to burn towards above.

In the embodiment shown in Figure 4, the head 3 of the burner body comprises a section 3a of radially internal distribution, and a distribution section 3b radially outer that are tapered longitudinally and arranged coaxially one inside the other.

Sections 3a, 3b of distribution have respective perforated parts 4a, 4b and 4c, arranged substantially cloth and parallel to each other, which constitute a equal number of parts of the perforated wall 4 of the head 3 of the burner.

Sections 3a, 3b of distribution can be fed individually by respective ducts 35, 36 coaxial that are tapered longitudinally and have a section essentially semicircular transverse that progressively decreases to as it approaches the free end of head 3 of the burner.

Therefore, in the burner head 3 they are defined two feeding chambers, which are formed, respectively, by a semiannular separation 37 adapted to feed the outer section 3b radially, and by a chamber 46 which is essentially shaped like a conical sector and that is defined inside the duct 36.

As you can see in Figure 4, both the semiannular separation 37 as chamber 46 have a section transverse that is progressively reduced as they approach the free end of burner head 3.

Conveniently, and in order to improve the required fluid tightness between sections 3a and 3b of distribution of the burner head 3, the inner part 4a radially perforated from wall 4 is separated from parts 4b and External 4c radially perforated by a pair of areas 40a and 40b not perforated to which the opposite side edges are welded of the inner duct 36.

In this case, the fluid tight separation between the distribution sections 3a and 3b of the head 3 of the burner is secured upstream and to perforated wall 4 through the inner conduit 36 and the unperforated areas 40a, 40be, respectively, thus preventing deviation unwanted of the first gas / air mixture of section 3a to the contiguous section 3b when it is not in operation temporarily.

In accordance with this embodiment and as shown in figure 4, the ignition electrode 22 and the detector 23 of flame are supported at a predetermined distance from wall 4 perforated near one end of the perforated part 4a of the section 3rd radially internal distribution.

In this way, during the operation, first turn on the gas / air mixture distributed by the section 3rd radially internal distribution, while mixing gas / air distributed by outdoor distribution section 3b radially it will be lit by the flame that is present externally to section 3a of adjacent distribution.

In an alternative embodiment, and depending on the specific application requirements, electrode 22 of ignition and flame detector 23 may be supported near a first end of the perforated parts 4b, 4c of section 3b of external distribution radially.

In this case, therefore, it will turn on first the gas / air mixture distributed by section 3b of radially external distribution, while the gas / air mixture distributed by section 3a of internal distribution radially will be lit by the flame that is present in section 3b of contiguous distribution

Referring to the attached figures 5 and 6, a combustion module 73 will now be described in accordance with the invention, adapted to equip a boiler of which only schematically shows the outer housing 74 in said figures.

Conventionally, said boiler comprises also a plurality of known components, not shown in the figures (hydraulic circuitry, circulation pump, control panel control, etc.) that are supported inside housing 74 below of combustion module 73.

The combustion module 73 shown in the figure 5 is especially compact, and conveniently allows to reduce the size of the boiler in which the module is mounted.

In this embodiment, combustion module 73 comprises a housing 75 substantially parallelepipedically within which a gas combustion chamber 76 is defined fuel, which is laterally insulated by panels 77 made of suitable heat insulating material, for example ceramic fibers, and which is provided with a top bell 78 for the extraction of combustion gases.

In addition, in this embodiment the housing 74 of the boiler is provided with an annular opening 85 that extends coaxially around bell 78, and that is adapted to allow air to enter the housing 74. In this way, combustion air A flows into a separation that is defined between the casing 75 in the form of a module 73 housing combustion and the outer casing 74 of the boiler, before entering into an air inlet opening 56 - which is formed laterally in the support body 102 of the assembly 101 of burner- and that is sucked into burner assembly 101.

Beneficially, and in order to prevent introduction of foreign bodies into set 101 of burner, the air inlet opening 56 is provided with a 58 protective cloth with the appropriate shape.

The combustion module 73 also comprises a gas-water heat exchanger 79, or primary exchanger, adapted to produce hot water primary space heating water, which comprises, in turn, a series of parallel tubes 80, which are supported in known manner not shown in the figures, in combustion gas chamber 76 current under a burner assembly 101 that will be described later.

The primary heat exchanger 76 is in fluid communication with a pair of ducts 81, 82 that distribute and they extract the primary water to and from the same exchanger. Sayings ducts are conventionally attached to opposite tubes 80 in the end of that series.

In addition, the heat exchanger tubes 80 79 primary are in fluid communication with each other through a pair of manifolds 91, 83 divided internally into a plurality of chambers for liquid distribution by means of a couple of baffles of which, in figure 5, you can only see the baffle labeled numeral 97 that divides manifold 83. Thanks to this provision, the primary water distributed to the primary heat exchanger 79 from conduit 81 of feed flows successively through tubes 80 following a zigzag path before reaching the extraction duct 82 and exit the exchanger 79.

Conveniently, heat exchanger 79 primary has, in this case, a very compact size although it has a suitable lateral liquid tube path to meet the thermal exchange requirements.

In this embodiment of the invention, the assembly 101 burner is supported on the base of the gas chamber 76 of combustion, and has a very large compactness. Indeed, in this case part of the burner head 3 is essentially integral with the support body 102 of the burner assembly 101, with a substantial reduction in both the sizes and the number of components of the same burner assembly. To this end, the body 102 support which, in this case, is substantially parallelepipedic, is properly shaped and has a plurality of cavities and fluid passageways, as will be described later.

Burner head 3 is provided with a pair of walls 4a, 4b permeable to gas, which are constituted, preferably, by respective porous plates 104a, 104b, which they have a parallelepipedic shape with a square base made of ceramic that has a predetermined gas permeability.

In an alternative embodiment, not shown in the figures and analogously to what was illustrated above, the walls gas permeable from burner head 3 may be constituted by metal plates perforated properly with a predetermined thickness and a shape similar to that of the plates Porous mentioned above.

Also in this case, the burner head 3 It comprises a pair of sections 3a, 3b of distribution, structurally independent and separated from each other so fluid tight upstream and in the plates 104a, 104b, mentioned before.

In this case, sections 3a, 3b of Burner head distribution 3 are arranged in parallel each other, and can be fed individually by cameras 48. 49 respective power, structurally independent and defined upstream of walls 104a, 104b permeable to gas.

The power chambers 48, 49 are integral with the support body 102 of the burner assembly 101, and are separated from each other in a gas tight manner by a sheet 50 of partition that extends vertically inside cavity 51 centrally formed in body 102.

Preferably, the partition plate 50 is integral with the support body 102 of the burner assembly 101, and extends into cavity 51 substantially along the entire length of the burner head 3.

In this embodiment, the watertight separation desired fluids between distribution sections 3a and 3b of the burner head 3 is secured upstream and in the porous plates 104a, 104b by the partition plate 50 and, respectively, by a deflector, essentially formed as a "T" inverted, which extends vertically from sheet 50 partition and is interposed between said porous plates.

In this way, the unwanted deviations of the gas / air mixture from one of the sections 3a, 3b to the next section when it is not Temporarily in operation.

Conveniently, and in order to obtain the necessary gas tightness upstream and in the plates 104a, 104b porous, a fisa 89 is interposed made of a material suitable, for example silicone, between the deflector 105 and the sheet 50 partition, where it is partially housed in a seat 90 of concordant coupling.

With particular reference to the figure 6, construction details will be described below of medium 6 adapted to independently supply the respective gaseous fuel / oxidizer mixtures at each section 3a, 3b distribution. Only for the purpose of simplifying the description, in the following description and in that figure, will refer only to those parts of the medium 6 adapted to feed section 3, understanding that the parts corresponding designed to feed section 3b are totally similar.

In this embodiment and in order to minimize both the number of components and the size of set 1 of burner, the blower suction duct 9 shown in the Figure 6 is essentially constituted by a passage 116, which is integral with the support body 102 of the assembly 101 of burner.

Preferably, the suction line 116 is in fluid communication with the input opening 56 of air.

Preferably, the supply line 11 of fuel gas to distribution section 3a is mounted on a respective wall 60, provided coaxially with a through hole housing the duct 11. The wall 60 is also provided with a plurality of slots 61 to make possible the circulation of air.

Beneficially, the perforated wall 60 transmits a predetermined pressure drop to the air flow therethrough and allows -in cooperation with a device that detects said pressure drop (not shown) -control the flow of the fuel gas G according to with the pressure drop and, therefore, depending on the air flow A sucked by the
blower 9.

Conveniently, the complete premixed air and from the combustible gas takes place, in this case, upstream of blower 9 -which, in this case, is the gas-tight type -which produces, in this way, a more complete mixing between the gas fuel and combustion air.

Conveniently, in addition, and in order to minimize both the number of components and the size of the set 1 of burner, blower 9 is provided with a respective body 109a in the form of a box that is, at least partially, integral with the support body 102 of burner assembly 101 and which is sealed by a respective cover 110a.

Conventionally, an electric motor 52 of blower drive 9 is supported outside the cover 110a which, in turn, is provided with a respective housing 54 of protection.

In this embodiment, and always in order to minimize both the number of components and the size of the set 1 of burner, blower distribution conduit 119 is consisting essentially of a properly formed conduit integral with the support body 102 of the assembly 101 of burner.

According to the invention, the conduit 119 of distribution of the blower 9 is provided with a means of adequate interception, in this case constituted by a valve 62 retention.

More specifically, valve 62 is adapted to intercept duct 119 downstream of blower 9 in one of its entrance openings 121 which constitutes, at the same time, a valve seat on which a shutter 64 of the valve 62.

As shown in greater detail in Figure 6, valve 62 comprises a valve body 63 that is at least partially, integral with the support body 102 of the assembly 101 of burner, inside said body 63 the shutter 64 is mounted which, in this case, is of the lid type and is peripherally provided with an O-ring 65 sealant.

In this embodiment, the valve body 63 62 is defined between the support body 102 of the assembly 101 of burner and cover 110a of body closure 109 a in the form of blower housing 9. Also in this case, said cover operates as Detachable cover adapted to seal the valve body 63 aforementioned. To this end, cover 110a is provided peripherally with a frisa 86 housed in a respective seat formed in the body 102.

In order to operate the shutter 64, the valve 62 is provided with a mechanical actuator, generally indicated in 66, which includes a rod 67 which is mounted so waterproof through cover 110a.

The rod 67 is rotatably mounted on the shutter 64 at a first end provided with a head Spherical 87a, the shutter 64 also having a washer 68 concordant at its opposite end.

The mechanical actuator 66 further comprises a torque of springs 69a, 69 that act against each other that act to close and open, respectively the opening 121, being made said springs of suitable metal materials. To this end, the springs 69a and 69 are interposed, respectively, between the shutter 64 and an inner wall of the cover 110a, and between a outer wall of cover 110a and washer 68.

Conveniently, the pressure drop that the gaseous fuel / oxidizer mixture experiences during your circulation through valves 62 can be reduced properly thanks to the presence of a spike 72, which has a predetermined height, which extends from cover 110a and which is adapted to act as a stop means for the shutter 64 to the distribution duct opening 110.

In this case, and as shown in Figure 6, the shutter 64 performs a translation movement at the opening and then a rotation movement as soon as it relies on the pin 72, thanks to its swivel connection with the rod 67.

At the end of the rod 67 race, and how it shown in continuous line in figure 6, the shutter 64 is will tip then in such a way that it interferes the least possible with the flow of the gaseous fuel / oxidizer mixture which is directed towards opening 121.

According to a preferred embodiment of the invention, the closing spring 69a is made of an elastic steel conventional, and is adapted to exert a first force predetermined, while spring 69 is made of a material suitable metal with shape memory, such as an alloy of nickel and titanium.

Thanks to the inherent characteristics of this shape memory material, spring 69 adapts conveniently to exert a force greater than spring 69a only above a predetermined temperature (or transition temperature), previously known and attainable having a suitable heating medium for the spring 69.

In the embodiment of Figure 6, said means of spring heating 69 is conveniently constituted by a pair of electrical cables 70, 71 adapted to allow circulation of a current with a predetermined value in it dock and, in this way, you achieve its heating by effect Joule.

Beneficially, the opening operations and Valve closure 62 can be easily controlled by the boiler control panel on which assembly 1 is mounted of burner, without any intervention of moving parts.

Finally, in this embodiment of set 1 of burner the gas / air mixture distributed by sections 3a and / or 3b can be turned on - choosing which section should be started first -thanks to a 123 ignition / flame detection set located substantially on horseback of said sections.

This allows, conveniently, to extend life useful of blowers 9, 10 programming the cycles properly operational sections 3a, 3b distribution.

In the embodiment shown in Figure 5, the set 123 comprises:

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a first isolated ignition electrode 124, which has a free end near the edge of the sheet 104a;

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 a insulated central electrode 125 or ground electrode, which it has a free end near the edge of the sheet 104b and is located opposite the free end of electrode 124 isolated with with respect to the deflector 105, intended to divide the plates 104a, 104b, and

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 a second isolated ignition electrode 126, which is shaped substantially "L" and is provided with an arm 126a end at a predetermined distance of the plates 104a, 104b, a baffle horse 105.

Conveniently, said electrodes are properly configured to have an extreme part of the same at a predetermined distance from the free surface of the plates 104a, 104b.

In this way, in operation, set 123 is conveniently capable of:

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produce a spark between the electrode 124 of isolated ignition and grounding electrode 125, a horse of the plates 104a, 104b, thus producing the ignition of the gas mixture coming from the sheet that is fed in the moment and at the same time

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detect the presence of combustion by middle of the isolated ionization electrode 126 that has its arm 126th end extending on horseback of the plates 104a, 104b and, of this way, being able to detect the presence of combustion Whatever the sheet in operation at the moment.

The different benefits that arise from the The present invention becomes apparent immediately from the disclosure. previously.

First, the burner assembly has all the benefits of efficiency, environmental impact, size and cost that are typical of burner assemblies of complete premixed.

Second, the burner assembly of the invention allows to achieve a power modulation range thermal that is significantly higher than the sets of Aerated or premixed prior art burner, and equal to the sum of the modulation ranges that can be achieved by each one of the distribution sections of your burner body.

In addition, the burner assembly of the invention allows to ensure the modulation range of thermal power previous not only for powers that could be reached until the moment only by aerated or blown burners (power of the order of 100 - 120 KW), but also for thermal powers reduced (of the order of 20 - 30 KW) simply by selecting the medium size adapted to distribute the gaseous mixture of fuel / oxidizer to each distribution section.

Finally, the burner assembly of the invention also allows combustion of the mixture to be carried out of fuel / oxidizer distributing this not only in the direction vertical and from bottom to top, as is the case with sets of aired prior art burner but also distributing the fuel / oxidizer mixture laterally or from top to bottom, all this to the benefit of its flexibility of operation.

Claims (17)

1. A set (1, 101) of burner that understands:

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 a support body (2, 102);

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 a burner head (3) supported by said body (2), which comprises at least one wall (4, 104a, b) gas permeable and a plurality of structurally distributed sections (3a, 3b) independent and separated from each other in a fluid tight manner upstream and in said at least one wall (4, 104a, b) gas permeable;

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a means (6) supported by said supply body (2, 102) regardless of a gaseous fuel / oxidizer mixture at each of the head distribution sections (3a, 3b) (3) of the burner;

characterized in that the burner assembly (1, 101) is of the complete premixed type, because the means of supply of the mixture fuel / oxidizer gas to each of the sections (3rd, 3b) distribution of the burner head (3) comprises, at less, a conduit (7, 8, 29, 30, 32, 33, 35, 36, 119) in fluid communication with a respective blower (9, 10) and a respective fuel supply line (11, 12) soda, and because it also includes a means of interception (21, 62) of said at least one conduit (7, 8, 29, 30, 32, 33, 35, 36, 119) supply of the gaseous mixture of fuel / oxidizer, said means (21, 62) of interception upstream of at least one of said sections (3a, 3b) of distribution and being adapted to prevent a return of combustion gases towards the assembly (1, 101) of burner. 2. A set (1, 101) of burner according with claim 1, wherein said at least one wall (4, 104a, b) gas permeable consists essentially of a wall (4) provided with a plurality of distribution holes of the gaseous fuel / oxidizer mixture. 3. A set (1, 101) of burner according with claim 1, wherein said at least one wall (4, 104a, b) gas permeable consists essentially of a sheet (104a, b) made of a suitable porous and permeable material gas. 4. A set (1, 101) of burner according with claim 1, wherein the sections (3a, 3b) of Fuel / oxidizer gas mixture distribution are arranged in series and can be fed individually by respective coaxial power chambers (15, 38). 5. A set (1, 101) of burner according with claim 1, wherein the sections (3a, 3b) of Fuel / oxidizer gas mixture distribution are arranged in parallel and can be fed individually by power chambers (42, 43, 44, 45, 37, 46, 48, 49) defined in the head (3) of the burner upstream of said at least one wall (4, 104a, b) gas permeable. 6. A set (1, 101) of burner according with claim 5, wherein the cameras (42, 43, 44, 45, 37, 46, 48, 49) feed are alternately separated from gas-tight manner by at least one plate (31, 34, 50) of partition. 7. A set (1, 101) of burner according with claim 6, wherein said at least one sheet (31, 50) partition is mounted vertically on said head (3) of the burner substantially over the entire length or width of the same. 8. A set (1, 101) of burner according with claim 6, wherein said at least one sheet (34) of partition is mounted horizontally on said head (3) of the burner substantially throughout its length. 9. A set (1, 101) of burner according with claim 1, comprising a pair of sections (3a, 3b) substantially semi-cylindrical and tapered distribution longitudinally arranged coaxially in parallel one within the other. 10. A set (1, 101) of burner according with claim 1, wherein the means (21, 62) of interception comprises a check valve provided with a mechanical actuator (66) that includes a spring (69) made of a suitable metallic material of the so-called memory type of shape. 11. A set (1, 101) of burner according with claim 1, further comprising an electrode (22, 124) of ignition located at a predetermined distance from said at least a gas permeable wall (4, 104a, b) of the head (3) of the burner. 12. A set (1, 101) of burner according with claims 5 and 11, wherein the sections (3a, 3b) of distribution arranged in parallel with each other, are arranged essentially side by side and coplanar, and in which the electrode (22, 124) of ignition is operatively located to generate a astride astride of said sections (3a, 3b) arranged Side to side. 13.A set (1, 101) of burner according with any one of the preceding claims, which further comprises a flame detector (23, 126) located at a predetermined distance of said at least one wall (4, 104a, b) gas permeable from the burner head (3). 14. A set (1, 101) of burner according with claim 1, wherein the blower (9, 10) is provided with a box-shaped body (109a) that is, at least partially, integral with the support body (102) of the assembly (1, 101) of burner. 15. A set (1, 101) of burner according with claim 1, further comprising a means (26) of detachable connection to a boiler. 16. A combustion module (73) of a gas boiler, comprising a box-shaped housing (75) in which a flue gas chamber (76) and a heat exchanger (79) mounted in said chamber (76), characterized in that it comprises, upstream of said heat exchanger (79), a burner assembly (1, 101) according to any one of claims 1-3, 5-7, or 10-15 . 17. A gas boiler comprising a set (1, 101) of burner according to any one of the claims 1 to 15.