Atmospheric gas burner with a combustion producing low amounts of nitrogen and carbon oxides

Abstract: A gas burner, comprises a burner body (1) including, at a fuel gas inlet (3), at least a Venturi tube (10), for supplying therethrough a high amount of air to be admixed with the fuel gas, said gas burner further comprising a combustion head (20) having a central flame driving hole row (21), and suitable to prevent said flame from detaching therefrom.

Description: BACKGROUND OF THE INVENTION The present invention relates to an atmospheric gas burner with a combustion producing low amounts of nitrogen and carbon oxides. A very important problem which at present occurs in gas burners is that of reducing the emission of nitrogen oxides (NOx) and carbon oxides (CO) occurring during the combustion, because of the small amount of air which is mixed with the fuel gas. Moreover, in the flame modulating types of systems, the combustion head tends to over-heat, mainly as the pressure of the mixture to the burner decreases to minimum values, thereby will occur very high emissions of nitrogen oxides and carbon oxide. Another drawback is that prior gas bruners do not always provide a good combustion of the air/ gas mixture, with a consequent decrease of the burning efficiency and an increase of combustion polluting agents. The document FR-A-2102802 discloses a wall boiler including burner elements made of a drawn sheet metal and including an inlet duct for the inlet of a fuel fluid tapering with an elongated tip provided with distributing means transforming a circular fluid jet into a flame front. This document does not include any particular burning hole arrangement. The document GB-A-1078951 discloses a gas burner in which the rows of burner holes are constituted by a plurality of ribbon burners and in which the flame holes or ports constitute a ladder burning assembly interconnecting the rows or groups of rows for transmitting the flame from one row or group of rows to an adjacent row or group of rows. This burner construction does not provide any central row of holes operating as pilot-flame holes. SUMMARY OF THE INVENTION According, the aim of the present invention is to overcome the above mentioned drawbacks, by providing a gas burner, of the atmospheric type, specifically designed to provide a combustion generating low amounts of nitrogen oxides and carbon oxide, and which is specifically designed to greatly increase the air amount which is admixed with the fuel gas, so as to reduce the generation of combustion polluting materials. Within the scope of the above mentioned aim, a main object of the present invention is to provide a gas burner, of the atmospheric type, in which the flame is prevented from moving away from the combustion head, thereby providing an optimal combustion performance under any conditions. Yet another object of the present invention is to provide a gas burner the combustion head of which is prevented from overheating, even in the case in which there is used a flame modulation system, thereby preventing nitrogen or carbon oxides from being emitted. Yet another object of the present invention is to provide such a gas burner, of the atmospheric type, geerating low amounts of nitrogen and carbon oxides and which, because of its specifically designed construction, is very reliable and safe in operation. According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a gas burner, of an atmospheric type, having the features of the main claim. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the present invention will become more apparent hereinafter from the following detailed disclosure of some preferred embodiments thereof, which are shown, by way of an indicative example, in the accompanyiond drawings where: Figure 1 is a schematic elevation view illustrating a gas burner having an U-shaped inlet; Figure 2 is a cross sectional view substantially taken along the line II-II of Figure 1; Figure 3 is another cross-section view substantially taken along the line III-III of Figure 1; Figure 4 illustrates a gas burner, having a rectilinear inlet, extending in two arms; Figure 5 is another cross-section view taken along the broken line V-V of Figure 4; Figure 6 is a top plane view of the gas burner shown in Figure 4; Figure 7 shows the combustion head of the gas burners; and Figure 8 is another cross-sectional view illustrating, on an enlarged scale, the detail of the burner combustion head. DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the number references of the above mentioned figures, the gas burner, of the atmospheric type, providing a combustion with low amounts of nitrogen oxides and carbon oxides, according to the present invention, comprises a burner body, indicated at 1 in Figure 2 and at 2 in Figure 4, which bodies are provided with differently shaped fuel gas inlets. More specifically, in Figure 1 the fuel gas inlet, indicated at the reference number 3, extends with an U-shape, whereas the fuel gas inlet of the burner shown in Figure 4, and indicated at the reference number 5, extends, after a starting rectilinear portion, in two split arms 6. The main feature of the present invention is that, at the fuel gas inlets 3 and 5, there is provided at least a Venturi pipe or tube 10, which is provided for allowing the supplying of a high amount of air to be admixed with the fuel gas. In particular, there are provided one or more Venturi tubes, so as to provide an aeration of 120%, with a full or complete mixing between air and gas. The inlets extend in a per se known manner and converge to a combustion head, generally indicated at the reference number 20, which is obtained from the particular configuration of the sheet metal elements defining the side surfaces of the bodies of the burner. In particular, the combustion head 20 is provided with a central hole row 21, the holes of which are delimited by a central recess 22 arranged between two side hole rows 23, arranged at the top of regions 24 in which the fuel gas is emitted. The central hole row 21 has the very important function to drive the flame in a continuous and safe way, so as to prevent the flame from moving away or detaching from the burner, thereby always providing very good combustion conditions. In operation, the central hole row provides a continuous pilot flame, adjoining the elongated holes 23 of the side regions 24, where the combustion proper is performed. With the disclosed construction, by providing a comparatively high supplying of air into the mixture, there are greatly reduced the nitrogen and carbon oxide rates, as generated from the combustion. Moreover, the high amount of air supplied to the mixture, prevent the combustion head from overheating, even if the burner is used in flame modulation system, under a low operation pressure condition. From the above disclosure it should be apparent that the invention fully achieves the intended aim and objects. In particular, the fact is to be pointed out that a gas burner has been provided which is particularly suitable for heating systems and/or for producing hot water for hygienic and sanitary use. In practicing the invention, the used materials, provided that they are compatible to the intended use, as well as the contingent size and shape, can be any, depending on requirements.

Claims: A gas burner, of an atmospheric type, with a combustion producing low amounts of nitrogen and carbon oxides, comprising a burner body (1) including, at a fuel gas inlet (3), a Venturi tube (10), for supplying therethrough a high amount of air to be admixed with the fuel gas, and a combustion head (20) having a central flame driving hole row (21), characterized in that the holes of said central hole row (21) are delimited by a central recess arranged between two side hole rows (23) arranged at the top of side regions (24) in which a fuel gas is emitted, said central hole row (21) providing a continuous pilot flame adjoining the elongated holes of said side regions (24) where the combustion proper is performed, in that said central hole row (21) is arranged at a raised position with respect to the holes of said side regions (24), and in that said Venturi tube (10) supplies an amount of primary air of 120% of the air stoichiometrically required for combustion. A gas burner according to Claim 1, characterized in that the fuel gas inlet (3) extends with an U-shape. A gas burner according to one or more of the preceding claims, characterized in that said fuel gas inlet (3) extends with a rectilinear portion (5) and is branched into two split arms (6). A gas burner according to one or more of the preceding claims, characterized in that said central flame driving hole row (21) is provided with restricted cross-section holes, with respect to the combustion holes, defined through said side regions (24) adjoining said central row (21).

Inventors: FERROLI DANTE, FERROLI, DANTE, FERROLI, DANTE C/O FERROLI S.P.A.
Applicants: FERROLI SPA, FERROLI S.P.A.
Application year: 1993
Main classification: F23D14
IPC codes: F23D14