gas burner apparatus with pre-mixing

Abstract

A gas burner apparatus with pre-mixing includes a mixing device for mixing an air/gas mixture which is intended to be conveyed to the intake section of a fan unit whose delivery is conveyed to a combustion head of the burner. The mixing device including a plurality of ducts, each of which has a region in the form of a Venturi duct with contiguous portions which are convergent/divergent, with respect to the direction of flow, and with a restricted duct cross-section defined between the convergent portion and the divergent portion, there being conveyed in each convergent portion an air flow which is intended to be mixed with a gas flow which is introduced into the duct at the restricted cross-section, the air/gas mixture being conveyed through the divergent portion of the duct to the intake section of the fan unit. Each duct of the plurality is defined by the engagement of at least a first and a second mutually separate burner region along a mutual engagement profile, there being carried on each of the burner regions corresponding, separate portions of each of the ducts, at least a first fluid-tight sealing element being provided between the burner regions along the engagement profile in order to prevent gas and/or air from being drawn in with respect to the ducts. The at least first sealing element is interposed between the burner regions at the restricted cross-section of each of the Venturi ducts of the plurality of ducts; the at least first sealing element has through-holes which define the restricted cross-section of the corresponding Venturi duct in at least some of the plurality of ducts, as a result of the engagement of the burner regions along the engagement profile and is interchangeable with at least a second sealing element which has corresponding through-holes, whose overall size for the relevant cross-sections is different from the overall size for the cross-sections relating to the corresponding holes of the first sealing element, so as to vary the overall cross-section defined by the plurality of holes of the ducts, with at least the first element being interchanged with at least the second sealing element, and consequently to control the burner in accordance with the thermal power required and/or the flow resistances which exist in the ducts for supplying the air/gas mixture to the burner.

1 . A gas burner apparatus with pre-mixing comprising mixing device for mixing an air/gas mixture which is intended to be conveyed to the intake section of a fan unit, whose delivery is conveyed to a combustion head of the burner, the mixing device comprising a plurality of ducts, each of which has a region in the form of a Venturi duct with contiguous portions which are convergent/divergent, with respect to the direction of flow, and with a restricted duct cross-section defined between the convergent portion and the divergent portion, there being conveyed in each convergent portion an air flow which is intended to be mixed with a gas flow which is introduced into the duct at the restricted cross-section, the air/gas mixture being conveyed through the divergent portion of the duct to the intake section of the fan unit, each duct of the plurality being defined by the engagement of at least a first and a second mutually separate burner region, along a mutual engagement profile, there being carried on each of the burner regions corresponding, separate portions of each of the ducts, at least a first fluid-tight sealing element being provided between the burner regions along the engagement profile in order to prevent gas and/or air from being drawn in with respect to the ducts, the at least first sealing element is interposed between the burner regions at the restricted cross-section of each of the Venturi ducts of the plurality of ducts,
 in that the at least first sealing element has through-holes which define the restricted cross-section of the corresponding Venturi duct in at least some of the plurality of ducts, as a result of the engagement of the burner regions along the engagement profile,   and in that at least the first sealing element is interchangeable with at least a second sealing element which has corresponding through-holes, whose overall size for the relevant cross-sections is different from the overall size for the cross-sections relating to the corresponding holes of the first sealing element ( 20 ), so as to vary the overall cross-section defined by the plurality of holes of the ducts, with at least the first element being interchanged with at least the second sealing element, and consequently to control the burner in accordance with the thermal power required and/or the flow resistances which exist in the ducts for supplying the air/gas mixture to the burner.   
     
     
         2 . A burner apparatus according to  claim 1 , wherein at least the first sealing element and second sealing elements which are mutually interchangeable are of annular shape and the through-holes which are provided in each corresponding sealing element are provided so as to be circumferentially and angularly spaced apart from each other. 
     
     
         3 . A burner apparatus according to  claim 1 , wherein the holes which are provided in the first sealing element all have the same predetermined size for the cross-section and the holes which are provided in the second sealing element all have the same predetermined size for the cross-section, which is different from that provided in the first sealing element. 
     
     
         4 . A burner apparatus according to  claim 3 , wherein the holes in the first sealing element are provided so as to be equal in number to the holes of the second sealing element. 
     
     
         5 . A burner apparatus according to  claim 1 , wherein each hole of the first element has a size for the cross-section that is equal to that of the cross-section of each hole of the second sealing element, and the total number of holes of the first element is different from the total number of holes of the second sealing element. 
     
     
         6 . A burner apparatus according to  claim 1 , wherein the holes which are provided in the first sealing element and second sealing element are regularly spaced apart from each other with a predetermined angular interval. 
     
     
         7 . A burner apparatus according to  claim 1 , wherein there is provided, by means of the holes of the corresponding sealing element, the passage for the flow of air which is drawn into the burner, with corresponding second, separate holes being provided in the sealing elements and defining the cross-section of passage of the gas flow which is introduced into the restricted cross-section of each Venturi duct. 
     
     
         8 . A burner apparatus according to  claim 7 , wherein there is provided, for each sealing element, a hole for the passage of gas in a position adjacent to a corresponding hole for the passage of intake air. 
     
     
         9 . A burner apparatus according to  claim 1 , wherein there are provided, in each of the sealing elements, a plurality of third through-holes which define the cross-section of passage, at the engagement profile of the burner regions, of ducts which are capable of conveying flows of the air/gas mixture which are supplied from the delivery side of the fan unit in the direction of the burner head. 
     
     
         10 . A burner apparatus according to  claim 9 , wherein the third holes are circumferentially arranged in each of the sealing elements, alternating with the holes for the passage of the intake air.