Downshot burner

Abstract

A burner outlet set for a downshot firing burner is described comprising a first outlet array having at least one primary outlet, and at least one vent air outlet disposed either side of the primary outlet in an array direction of the first outlet array; second and third outlet arrays each comprising an array of secondary air outlets, respectively disposed either side of the a first outlet array. A burner system with a plurality of such burner outlet sets, a burner arch configured for downshot firing and having one or more such burner sets, and a combustion furnace with one or more such arches are also described.

1 . A burner outlet set for a downshot firing burner comprising:
 a first outlet array comprising at least one primary outlet, and at least one vent air outlet disposed either side of the primary outlet in an array direction of the first outlet array;   second and third outlet arrays each comprising an array of secondary air outlets, respectively disposed laterally either side of the a first outlet array,   
     
     
         2 . A burner outlet set thus comprises a first outlet array disposed in an elongate first array direction and comprising at least one primary outlet with at least one vent air outlet disposed either side of the primary outlet, and paired second and third outlet arrays each comprising a plurality of secondary air outlets respectively disposed in elongate second and third array directions that are laterally spaced either side of the first outlet array. Typically the second and third outlet arrays are even laterally spaced either side of the first outlet array. Typically the second and third outlet arrays and arrayed in elongate array directions generally parallel to the first array direction. Typically each of the first, second and third outlet arrays extend in elongate array directions to the same longitudinal extent. 
     
     
         3 . A burner outlet set in accordance with  claim 1  wherein each primary outlet is a square or rectangular outlet disposed with a median line direction parallel to and for example coincident with the array direction of the first outlet array. 
     
     
         4 . A burner outlet set in accordance with  claim 1  or  claim 2  wherein each vent air outlet is a square or rectangular outlet disposed with a median line direction parallel to and for example coincident with the array direction of the first outlet array. 
     
     
         5 . A burner outlet set in accordance with any preceding claim wherein each secondary air outlet is a square or rectangular outlet disposed with a median line direction parallel to and laterally spaced from the array direction of the first outlet array. 
     
     
         6 . A burner outlet set in accordance with any preceding claim wherein each primary outlet is associated with exactly one secondary outlet in the second array and exactly one secondary outlet in the third array. 
     
     
         7 . A burner outlet set in accordance with  claim 6  wherein each vent air outlet is associated with exactly one secondary outlet in the second array and exactly one secondary outlet in the third array. 
     
     
         8 . A burner outlet set in accordance with  claim 7  wherein each outlet in the first array is transversely aligned with exactly one secondary outlet in the second array and exactly one secondary outlet in the third array. 
     
     
         9 . A burner outlet set in accordance with any preceding claim wherein a first outlet array comprises at least one primary/vent outlet module consisting exactly of a single primary outlet and a single vent air outlet disposed either side of the primary outlet. 
     
     
         10 . A burner outlet set in accordance with any preceding claim wherein a first outlet array comprises at least one primary/vent outlet module consisting exactly of a pair of primary outlets and a single vent air outlet disposed either side of the primary outlet. 
     
     
         11 . A burner outlet set in accordance with  claim 9  or  10  wherein a first outlet array comprises exactly one said primary/vent outlet module. 
     
     
         12 . A burlier outlet set in accordance with  claim 9  or  10  wherein a first outlet array comprises exactly two of the said primary/vent outlet modules disposed adjacently. 
     
     
         13 . A burner outlet set in accordance with any preceding claim wherein each primary outlet is provided with a wedge shaped bluff-body stabilizer. 
     
     
         14 . A burner outlet set in accordance with  claim 13  wherein the bluff body stabilizer is slitted and located in a position withdrawn into its outlet. 
     
     
         15 . A burner outlet set in accordance with any preceding claim wherein each primary outlet is a square or rectangular slot provided with four ignition teeth located at the corners of the square or rectangular slot. 
     
     
         16 . A burner system comprising a plurality of burner outlet sets in accordance with any preceding claim. 
     
     
         17 . A fuel combustion system comprising:
 a pulverous solid fuel supply source;   a transport gas supply source to supply comburant gas as a transport gas;   a mixing module configured to entrain fuel from the fuel supply within the transport gas;   a transport conduit to transport the fuel entrained in the transport gas;   a separator configured to separate the mixture of fuel and transport gas into a relatively fuel rich primary stream and a relatively fuel depleted vent air stream;   a primary conduit to convey the primary stream to primary outlets of a burner outlet set in accordance with any preceding claim;   a vent air conduit to convey vent air to vent air outlets of a burner outlet set in accordance with any preceding claim;   a secondary air supply system including a secondary conduit to convey secondary air to the secondary air outlets of a burner set of a burner outlet set in accordance with any preceding claim.   
     
     
         18 . A burner arch configured for downshot firing of fuel in a combustion chamber of a combustion apparatus having at least one burner outlet set in accordance with one of  claims 1  to  15  disposed on the burner arch whereby combustion of the fuel is supported in the vicinity of the burner set during use, 
     
     
         19 . A combustion apparatus comprising:
 a combustion chamber;   at least one burner arch configured for downshot firing of fuel in the combustion chamber;   at least one burner outlet set in accordance with one of  claims 1  to  15  disposed on the burner arch whereby combustion of the fuel is supported in the vicinity of the burner set during use.   
     
     
         20 . A combustion apparatus in accordance with  claim 19  further configured for the supply of overfire air to the combustion chamber in that each burner set is provided in association with at least one outlet or series of outlets for overfire air. 
     
     
         21 . A combustion apparatus in accordance with  claim 20  wherein each burner set is provided in association with at least one outlet or series of outlets for overfire air respectively provided at each of first and second levels respectively below and above a flame zone within the combustion chamber. 
     
     
         22 . A combustion apparatus in accordance with  claim 21  wherein a first overfire air outlet or series of outlets is provided above and closely adjacent to a hopper knuckle of the combustion chamber, and wherein a second overfire air outlet or series of outlets is above and closely adjacent to the burner arch. 
     
     
         23 . A combustion apparatus in accordance with  claims 19  to  22  further comprising:
 a pulverous solid fuel supply source; 
 a transport gas supply source to supply comburant gas as a transport gas configured to entrain fuel from the fuel supply within the transport gas; 
 a transport conduit to transport the fuel entrained in the transport gas; 
 a separator configured to separate the mixture of fuel and transport gas into a relatively fuel rich primary stream and a relatively fuel depleted vent air stream; 
 a primary conduit to convey the primary stream to the primary outlets; 
 a vent air conduit to convey vent air to the vent air outlets; 
 a secondary air supply system including a secondary conduit to convey secondary air to the secondary air outlets.