Method of Combusting Particulate Solid Fuel with a Burner

Abstract

A method of combining oxygen and fuel in a burner to produce a flame whereby an outer oxidant flow is discharged through an outer oxidant outlet of the burner; a flow of conveyor-gas propelled particulate solid fuel is discharged with a fuel discharge velocity through a fuel outlet of the burner arranged coaxially with respect to the outer oxidant outlet and spaced radially inwardly therefrom; and a first inner oxidant flow is discharged with an inner oxidant discharge velocity, which differs from the fuel discharge velocity, through an inner oxidant end outlet of the burner arranged coaxially with respect to said fuel outlet and spaced radially inwardly therefrom; and whereby a second inner oxidant flow, having a higher oxygen concentration than the conveyor gas is injected into the fuel-conducting passage and mixed with the fuel flow inside said fuel-conducting passage so as to obtain, upstream of the fuel outlet and upstream of the inner oxidant end outlet, an oxygen-enriched conveyor-gas propelled particulate solid fuel flow having an oxygen content of at least 21% vol O 2 .

1 - 15 . (canceled) 
     
     
         16 . A method of combining oxygen and fuel in a burner to produce a flame, said method comprising:
 supplying an outer flow of oxygen-containing oxidant to an outer oxidant-conducting passage of the burner, conducting said outer oxidant flow through said outer oxidant-conducting passage and discharging said outer oxidant flow with an outer oxidant discharge velocity from said outer oxidant-conducting passage through an outer oxidant outlet of the burner,   supplying a fuel flow to a fuel-conducting passage of the burner, conducting said fuel flow through said fuel-conducting passage and discharging said fuel flow with a fuel discharge velocity from said fuel-conducting passage through a fuel outlet of the burner arranged coaxially with respect to the outer oxidant outlet and spaced radially inwardly therefrom,   supplying a first inner flow of oxygen-containing oxidant to an inner oxidant-conducting passage of the burner, conducting said first inner oxidant flow through said inner oxidant-conducting passage and discharging said first inner oxidant flow with an inner oxidant discharge velocity from said inner oxidant-conducting passage through an inner oxidant end outlet of the burner arranged coaxially with respect to said fuel outlet and spaced radially inwardly therefrom,   
       characterized in that:
 the fuel flow is a flow of conveyor-gas propelled particulate solid fuel, 
 a second inner oxidant flow, having a higher oxygen concentration than the conveyor gas, is supplied to the burner and is injected into the fuel-conducting passage and mixed with the fuel flow inside said fuel-conducting passage so as to obtain, upstream of the fuel outlet and upstream of the inner oxidant end outlet, an oxygen-enriched conveyor-gas propelled particulate solid fuel flow having an oxygen content of at least 21% vol O 2 , 
 the fuel discharge velocity differs from the inner oxidant discharge velocity so as to promote mixing between the fuel flow and the inner oxidant flow downstream of the inner oxidant end outlet. 
 
     
     
         17 . The method of  claim 16 , whereby, at the fuel outlet, the oxygen-enriched conveyor gas has an oxygen content of at least 28% vol O 2 , preferably of at least 32% vol O 2 . 
     
     
         18 . The method of  claim 16 , wherein each of said first and second inner oxidant flows has an oxygen content of at least 50% vol O 2 , preferably of at least 80% vol O 2  and more preferably of at least 90% vol O 2 . 
     
     
         19 . The method of  claim 16 , wherein the outer oxidant flow is an air flow. 
     
     
         20 . The method of  claim 16 , wherein the outer oxidant flow has an oxygen content of at least 50% vol O 2 , preferably of at least 80% vol O 2  and more preferably of at least 90% vol O 2 . 
     
     
         21 . The method of  claim 16 , whereby the conveyor gas is air. 
     
     
         22 . The method of  claim 16 , whereby the conveyor gas contains combustion effluent gas, steam and/or CO 2 . 
     
     
         23 . The method of  claim 16 , whereby the particulate solid fuel is selected from pulverized coal, pet coke, particulate biomass and mixtures thereof. 
     
     
         24 . The method of  claim 16 , whereby the second inner oxidant flow is injected into the fuel-conducting passage at multiple points of injection along the length of the fuel-conducting passage of the burner. 
     
     
         25 . The method of  claim 16 , wherein the fuel flow is mixed with the first inner oxidant flow before being mixed the said outer oxidant flow. 
     
     
         26 . The method of  claim 16 , wherein at least 35%, preferably at least 50% and more preferably at least 65% of the total oxygen supply to the burner is supplied to the burner through the outer oxidant flow. 
     
     
         27 . The method of  claim 16 , wherein the first inner oxidant discharge velocity is equal to or greater than the outer oxidant discharge velocity. 
     
     
         28 . The method of  claim 16  to produce heat in a combustion zone of a furnace. 
     
     
         29 . The method of  claim 28 , wherein the furnace is select from the group consisting of: tunnel kilns and furnaces, passage kilns, boilers, rotary kilns and furnaces and tunnel furnaces. 
     
     
         30 . The method of  claim 28  in the production of hydraulically setting binder.