Inwardly burning surface stabilized gas premix burner

Abstract

The burner ( 100 ) comprises a cylindrical porous substrate ( 110 ); and an end cap ( 130 ) at a first end of the cylindrical porous substrate ( 110 ). The cylindrical porous substrate ( 110 ) is provided for flow of a premix of combustible gas and air from the outside of the cylindrical porous substrate ( 110 ) through the pores of the cylindrical porous substrate ( 110 ) to an interior cavity ( 140 ), for the combustible gas to be combusted on the inner surface of the cylindrical porous substrate ( 110 ) thereby generating hot gas. The burner has an opening ( 182 ) at the second end of the cylindrical porous substrate ( 110 ) to exit the hot flue gas out of the interior cavity ( 140 ). The cylindrical porous substrate ( 110 ) has a higher permeability section ( 170 ), located at the opening ( 182 ) at the second end. The higher permeability section ( 170 ) has a lower resistance to gas flow than other sections of the cylindrical porous substrate ( 110 ).

1 - 15 . (canceled) 
     
     
         16 . A burner comprising,
 a cylindrical porous substrate;   an end cap at a first end of the cylindrical substrate;   wherein the cylindrical porous substrate and the end cap enclose an interior cavity;   wherein the cylindrical porous substrate is provided for flow of a premix of combustible gas and air from the outside of the cylindrical porous substrate through the pores of the cylindrical porous substrate to the interior cavity,   for the combustible gas to be combusted on the inner surface of the cylindrical porous substrate thereby generating hot gas;   wherein the burner has an opening at the second end of the cylindrical porous substrate, for allowing the hot gas to exit the interior cavity;   wherein the cylindrical porous substrate has a higher permeability section,   wherein the higher permeability section is located at the opening at the second end;   and wherein the higher permeability section has a lower resistance to gas flow than other sections of the cylindrical porous substrate.   
     
     
         17 . A burner as in  claim 16 , wherein the higher permeability section comprises or consists out of an annular section of the cylindrical porous substrate. 
     
     
         18 . A burner as in  claim 16 ,
 wherein the cylindrical porous substrate comprises a first porous substrate present over the full height of the cylindrical porous substrate;   wherein outside the higher permeability section of the cylindrical porous substrate the inner side of the first porous substrate is covered with a second porous substrate;   and wherein in the higher permeability section when the burner is in use combustion occurs on the inner surface of the first porous substrate.   
     
     
         19 . Burner as in  claim 16 ,
 wherein the cylindrical porous substrate comprises a first porous substrate;   wherein the inner side of the first porous substrate is covered with a second porous substrate;   wherein the second porous substrate is a woven, knitted or braided fabric comprising stainless steel fibers;   and wherein the higher permeability section is provided by differences in the structure of the fabric compared to outside the higher permeability section.   
     
     
         20 . Burner as in  claim 18 , wherein the second porous substrate is a textile fabric comprising yarns, and wherein the yarns comprise a plurality of metal fibers in the cross section of the yarns. 
     
     
         21 . Burner as in  claim 18 , wherein the second porous substrate is a weft knitted fabric; and wherein the weft direction of the weft knitted fabric is provided in the circumferential direction of the cylindrical porous substrate. 
     
     
         22 . Burner as in  claim 18 , wherein the second porous substrate is a weft knitted fabric; and wherein the weft direction of the weft knitted fabric is provided in the axial direction of the cylindrical porous substrate. 
     
     
         23 . Burner as in  claim 16 ; wherein the cylindrical porous substrate has a higher porosity in the higher permeability section than in other sections of the cylindrical porous substrate. 
     
     
         24 . Burner as in  claim 23 , wherein the cylindrical porous substrate comprises or consists out of a perforated plate; and wherein in the higher permeability section, the higher porosity is provided by means of a higher number of perforations per unit of surface area and/or by larger perforations of a larger cross sectional area. 
     
     
         25 . Burner as  claim 16 , wherein the burner comprises a flange at the second end of the cylindrical porous substrate, and wherein in use, hot flue gas exits the interior cavity via the central opening in the flange. 
     
     
         26 . Burner as in  claim 25 , wherein the flange is attached to the cylindrical porous substrate at the inner side of the cylindrical porous substrate. 
     
     
         27 . Burner as in  claim 16 , wherein the end cap comprises perforations for the passage of premix combustible gas and air through the end cap to the inside of the interior cavity, for the premix combustible gas to be combusted inside the interior cavity. 
     
     
         28 . Burner as in  claim 27 ,
 wherein the end cap comprises perforations in a first area around the centre point of the end cap;   wherein the first area has a diameter of less than 60% of the diameter of the end cap;   wherein the end cap comprises perforations in a second area, wherein the second area is located outside the area around the centre point of the end cap; with diameter more than 75% of the diameter of the end cap; and   wherein the end cap is not perforated in the area between the first area and the second area.   
     
     
         29 . Burner as in  claim 16 , wherein the end cap is connected onto the cylindrical porous substrate at the outer side of the cylindrical porous substrate. 
     
     
         30 . Heating device for heating a fluid, wherein the heating device comprises at least two burners as in  claim 16 .