Burner and Method of Operation

Abstract

The invention relates to particular burners, particularly to non-premixed or partially-premixed dual-fuel burners with flexibility to change the heat input from the two fuels. Accordingly, said burners may be used in applications that needs operation of a bummer in both single-fuel, and/or duel-fuel mode depending on furnace operation needs. The invention further relates to methods of operating the burners.

1 . A burner ( 1 ), comprising:
 a primary fuel conduit ( 20 ) comprising a primary fuel outlet ( 22 ) having a multiplicity of primary fuel exit holes ( 23 ) for supply of a primary fuel into an ignition chamber ( 25 ), wherein the wall surrounding the ignition chamber ( 25 ) comprises a plurality of bleed holes ( 28 ),   a main oxidant conduit ( 30 ) for supply of a main oxidant, comprising an intermediate annular conduit ( 35 ) in a downstream portion ( 5 ) of the burner, which intermediate annular conduit ( 35 ) is configured to allow splitting of the main oxidant, such that a first portion is introduced into the ignition chamber ( 25 ) via the plurality of bleed holes ( 28 ) to mix with the primary fuel, and a second portion is introduced into an oxidant section ( 33 ),   wherein at least in the downstream portion ( 5 ) of the burner ( 1 ), in which primary fuel outlet ( 22 ), ignition chamber ( 25 ), intermediate annular conduit ( 35 ) are present, the primary fuel conduit ( 20 ) is surrounded by the main oxidant conduit ( 30 ).   
     
     
         2 . The burner of  claim 1 , wherein the burner further comprises a secondary fuel conduit ( 40 ) for supply of a secondary fuel, having a secondary fuel outlet ( 44 ) at its downstream end,
 wherein the secondary fuel outlet ( 44 ) comprises a secondary fuel distribution plate ( 45 ) having a multiplicity of secondary fuel exit holes ( 48 ), and   wherein at least two sets of holes are located on different concentric diameters.   
     
     
         3 . The burner of  claim 1 , wherein the ignition chamber ( 25 ) is extending from the primary fuel outlet ( 22 ) to the intermediate annular conduit exit plane ( 56 ), wherein the wall surrounding the ignition chamber ( 25 ) comprises two sections, and wherein
 i) the first section has an outer diameter smaller than or equal to the outer diameter of the primary fuel conduit ( 20 ) and comprises a plurality of bleed holes ( 28 ), wherein the wall surrounding the first section comprises a plurality of bleed holes ( 28 ), and wherein the first section further comprises means allowing the main oxidant to additionally enter the ignition chamber ( 25 ) in flow direction,   ii) the second section has an inner diameter greater than the outer diameter of the primary fuel conduit ( 20 ), but the second section has an outer diameter smaller than the inner diameter of the intermediate annular conduit ( 35 ), and comprises a further plurality of bleed holes ( 28 ),   iii) the burner optionally further comprises a purge plate ( 73 ) with purge holes ( 32 ) present between the first section's outer diameter and inner diameter of the second section, and   iv) the burner optionally further comprises a purge plate ( 73 ) with purge holes ( 32 ) present between the outer diameter of the second section and inner diameter of the intermediate annular conduit ( 35 ).   
     
     
         4 . The burner of  claim 1 , wherein the ignition chamber ( 25 ) is extending from the primary fuel outlet ( 22 ) to the intermediate annular conduit exit plane ( 56 ), wherein the wall surrounding the ignition chamber ( 25 ) comprises two sections, wherein
 i) the first section is extending from the primary fuel outlet ( 22 ) to the primary fuel conduit end plane ( 24 ), wherein the primary fuel conduit wall ( 29 ) surrounding the section comprises a plurality of bleed holes ( 28 ), and   ii) the second section has an inner diameter greater than the outer diameter of the primary fuel conduit ( 20 ), but the second section has an outer diameter smaller than the inner diameter of the intermediate annular conduit ( 35 ), and comprises a further plurality of bleed holes ( 28 ), and   iii) the burner optionally further comprises an oxidant purge plate ( 73 ) with purge holes ( 32 ) that extends between the first section's outer diameter and the inner diameter of the second section.   
     
     
         5 . The burner of  claim 1 , wherein the ignition chamber ( 25 ) is extending from the primary fuel outlet ( 22 ) to the intermediate annular conduit exit plane ( 56 ), wherein the wall surrounding the ignition chamber ( 25 ) comprises at least two sections of annular conduits with increasing diameter, each of which comprises a plurality of bleed holes ( 28 ),
 wherein the wall surrounding the ignition chamber ( 25 ) comprises two or three sections of annular conduits with increasing diameter, each of which comprises a plurality of bleed holes ( 28 ).   
     
     
         6 . The burner of  claim 1 , wherein the ignition chamber ( 25 ) comprises an ignition cup ( 75 ) as well as an oxidant bleed cup ( 76 ),
 wherein the ignition cup ( 75 ) is comprised in a first section of the ignition chamber ( 25 ), and the oxidant bleed cup ( 76 ) is comprised in a second section of the ignition chamber ( 25 ), wherein the second section is located downstream of the first section.   
     
     
         7 . The burner of  claim 1 , wherein the burner further comprises one or more mechanical mixer plates ( 74 ), wherein each mechanical mixer plate ( 74 ) is located downstream of and adjacent to the said two sections. 
     
     
         8 . The burner of  claim 1 , wherein the ignition chamber ( 25 ) is positioned within the primary fuel conduit ( 20 ), and is extending from the primary fuel outlet ( 22 ) to the primary fuel conduit end plane ( 24 ), wherein the primary fuel conduit wall ( 29 ) is surrounding the ignition chamber ( 25 ) and comprises a plurality of bleed holes ( 28 ). 
     
     
         9 . The burner of  claim 1 , wherein the burner further comprises an ignition source ( 10 ) that terminates in the ignition chamber ( 25 ),
 wherein the ignition source ( 10 ) is a central ignition source having a central axis ( 15 ) and a conduit end plane ( 16 ),   wherein the main axis ( 2 ) of the burner ( 1 ) coincides with the central axis ( 15 ) of the ignition source ( 10 ),   wherein at least in said downstream portion ( 5 ) of the burner ( 1 ) the central ignition source ( 10 ) is surrounded by the primary fuel conduit ( 20 ), the main oxidant conduit ( 30 ) and the secondary fuel conduit ( 40 ).   
     
     
         10 . The burner of  claim 1 , wherein the main oxidant conduit ( 30 ) further comprises a swirler section ( 33 ), particularly wherein the intermediate annular conduit ( 35 ) is configured to allow splitting of the main oxidant into two portions, wherein a second portion is introduced into a swirler section ( 33 ),
 wherein the swirl angle is from 5 to 70 degrees.   
     
     
         11 . The burner of  claim 1 , wherein the burner ( 1 ) is configured in such a way that
 i) the velocity of the primary fuel is between 30 ft/s and 500 ft/s; and/or   ii) the velocity of the main oxidant is between 10 ft/s and 300 ft/s; and/or   iii) the velocity of the secondary fuel is between 30 ft/s and 500 ft/s.   
     
     
         12 . The burner of  claim 1 , wherein
 i) the outer diameter of the ignition source ( 10 ) is defined as D 2 , the diameter of the primary fuel exit holes ( 23 ) is defined as D 0 , wherein D 0 /D 2  is between 0.05 and 0.6; and/or   ii) the outer diameter of the ignition source ( 10 ) is defined as D 2 , the diameter of the purge holes ( 32 ) is defined as D 1 , wherein D 1 /D 2  is between 0.06 and 0.15.   
     
     
         13 . The burner of  claim 1 , wherein
 i) the outer diameter of the ignition source ( 10 ) is defined as D 2  and the inner diameter of the primary fuel conduit ( 20 ) is defined as D 3 , wherein D 3 /D 2  is from 1.5 to 5.0; and/or   ii) the outer diameter of the ignition source ( 10 ) is defined as D 2  and the inner diameter of the main oxidant conduit ( 30 ) is defined as D 4 , wherein D 4 /D 2  is from 2.0 to 12.0; and/or   iii) the inner diameter of the main oxidant conduit ( 30 ) is defined as D 4  and the innermost extension of the inner circle of secondary fuel exit holes is defined as D 8 , wherein D 8 /D 4  is from 1.1 to 1.4; and/or   iv) the inner diameter of the main oxidant conduit ( 30 ) is defined as D 4  and the outermost extension of the outer circle of secondary fuel exit holes is defined as D 9 , wherein D 9 /D 4  is from 1.6 to 2.5; and/or   v) the outer diameter of the ignition source ( 10 ) is defined as D 2 , the inner diameter of the oxidant bleed cup is defined as D 6 , and wherein D 6 /D 2  is from 1.5 to 6.0; and/or   
     
     
         14 . The burner of  claim 1 , wherein
 i) the outer diameter of the ignition source ( 10 ) is defined as D 2 , the diameter of the air premixing holes ( 27 ) is defined as P 0 , wherein P 0 /D 2  is between 0.02 and 0.2; and/or   ii) the outer diameter of the ignition source ( 10 ) is defined as D 2 , the inner diameter of the bleed holes ( 28 ) is defined as P 1 /D 2 ; wherein P 1 /D 2  is between 0.06and 0.5; and/or   iii) the distance between the primary fuel conduit wall ( 29 ) or wall of the ignition cup ( 75 ), respectively, and the intermediate annular conduit wall ( 37 ) is defined as L 4 , and the distance between the primary fuel conduit end plane ( 24 ) and the intermediate annular conduit end plane ( 36 ) is defined as L 1 , wherein L 4 /L 1  is between 0.7 and 1.1; and/or   iv) the inner diameter of the primary fuel conduit ( 20 ) is defined as D 3 , the distance between the primary fuel conduit end plane ( 24 ) and the intermediate annular conduit end plane ( 36 ) is defined as L 1 , the distance between the intermediate annular conduit end plane ( 36 ) and the main oxidant conduit end plane ( 38 ) is defined as L 2  and wherein (L 1 +L 2 )/D 3  is from 0.2 to 2.0; and/or   v) the inner diameter of the primary fuel conduit ( 20 ) is defined as D 3 , the length of the oxidant bleed cup is defined as L 01 , and wherein (L 01 )/D 3  is from 0.1 to 1.0; and/or   vi) the distance between the wall of the oxidant bleed cup ( 76 ) and the intermediate annular conduit wall ( 37 ) is defined as L 5 , and the distance between the primary fuel conduit end plane ( 24 ) and the intermediate annular conduit end plane ( 36 ) is defined as L 1 , wherein L 5 /L 1  is between 0.3 and 0.6; and/or   vii) the distance between the primary fuel conduit wall ( 29 ) or wall of the ignition cup ( 75 ), respectively, and the intermediate annular conduit wall ( 37 ) is defined as L 4 , and the inner diameter of the primary fuel conduit ( 20 ) is defined as D 3 , wherein L 4 /D 3  is between 0.2 and 0.6; and/or   viii) the inner diameter of the primary fuel conduit ( 20 ) is defined as D 3 , the primary fuel outlet ( 22 ) is recessed in upstream direction from the primary fuel conduit end plane ( 24 ) by a distance L 0 , and wherein L 0 /D 3  is from 0.2 to 2.0; and/or   ix) wherein the outer diameter of the ignition source ( 10 ) is defined as D 2 , the diameter of secondary fuel exit holes is defined as D 7  and wherein D 7 /D 2  is between 0.05 and 0.6; and/or   x) the distance between two rows of bleed holes ( 28 ) measured between their centers is defined as H and the inner diameter of the bleed holes ( 28 ) is defined as P 1 , wherein H/P 1  is from 1.25 to 2.5; and/or   xi) the ratio of the area of all bleed holes in one row to the surface area of cylinder of height, P 1  and inner diameter, D 2  is between 10% and 55%; and/or   xii) the oxidant purge plate ( 73 ) has a porosity (defined by the total open area on the plate that allows the air to flow divided by cross-section area of the plate) in the range of 1% to 8%; and/or   xiii) the primary fuel exit plate ( 72 ) has a porosity (defined by the total open area on the plate that allows the fuel to flow divided by cross-section area of the plate) in the range of of 4% to 25%; and/or   xiv) the secondary fuel distribution plate ( 72 ) has a porosity (defined by the total open area on the plate that allows the fuel to flow divided by cross-section area of the plate) in the range of 8% to 25%.   
     
     
         15 . A method for operating the burner ( 1 ) of  claim 1 , the method comprising the steps of:
 i) starting the burner,   ii) ramping up the burner in firing rate,   iii) starting the secondary fuel,   iv) further changing the flow rate of primary, secondary fuel and burner equivalence ratio as required by the process;   
     
     
         16 . The method of  claim 15 ,
 A) wherein step i) comprises starting the main oxidant, the ignition source, and the primary fuel,   and/or   B) wherein the burner ( 1 ) is operated in such a way that   i) during start-up, 100% of the total thermal power of the burner is provided by the primary fuel; and/or   ii) during normal operation, 0 to 70%, of the total thermal power of the burner is provided by the primary fuel, and the respective rest is provided by the secondary fuel.   
     
     
         17 . The method of  claim 15  wherein the burner ( 1 ) is operated in such a way that
 i) the volumetric flow rate of the ignition chamber oxidant is 5 to 25% of the total main oxidant flow rate; and/or 
 ii) the volumetric flow rate of oxidant is 1-10% of the total main oxidant flow rate and/or 
 iii) the equivalence ratio is between 1.0 and 0.25.