Method for operating a multi-gas burner and a multi-gas burner

Abstract

The invention relates to a method for operating a multi-gas burner having at least one burner lance with a first, second and third nozzle and having a first, second and a third feed chamber. It is provided according to the invention that for high-calorific operation air is fed via the first nozzle, O 2 -depleted gas via the second nozzle and the high-calorific combustion gas via the third nozzle into the combustion chamber, where they are combusted. Furthermore the invention relates to a multi-gas burner for operation with a low-calorific and a high-calorific combustion gas.

1 . Method for operating a multi-gas burner in low-calorific operation with a low-calorific combustion gas and in a high-calorific operation with a high-calorific combustion gas, wherein the multi-gas burner has
 at least one burner lance with a first, a second and a third nozzle,   a first, a second and a third feed chamber which are each connected in terms of flow to a respective nozzle and   a combustion chamber, into which the at least one burner lance projects,   characterised in that   in a high-calorific operation air is fed via the first nozzle and simultaneously O 2 -depleted gas via the second nozzle and a high-calorific combustion gas via the third nozzle into the combustion chamber, where they are reacted, in particular combusted, the air and the O 2 -depleted gas being used as oxygen carriers for the combustion and   in a low-calorific operation air is fed via the first nozzle as an oxygen carrier for the combustion and simultaneously a low-calorific combustion gas is fed via the second nozzle into the combustion chamber, where they are reacted, in particular combusted.   
     
     
         2 . Method according to  claim 1 ,
 characterised in that   an outer nozzle is selected as a first nozzle, a central nozzle as a second nozzle and an inner nozzle as a third nozzle.   
     
     
         3 . Method according to  claim 1 ,
 characterised in that   the multi-gas burner is operated in low-calorific operation with a λ value in the range of from approximately 1.05 to approximately 1.2.   
     
     
         4 . Method according to  claim 1 ,
 characterised in that   the multi-gas burner is operated in high-calorific operation with a λ value of from approximately 1.4 to approximately 2.0, wherein approximately 15% to 30% of the oxygen provider comes from the O 2 -depleted gas.   
     
     
         5 . Method according to  claim 1 ,
 characterised in that   the λ value in low-calorific operation and the λ value and the mix of O 2 -depleted gas in high-calorific operation are set in such a way that the hot gases have an O 2  content of less than 10%.   
     
     
         6 . Method according to  claim 1 ,
 characterised in that   the quantity of the combustion gas, the λ value and the composition of the oxygen carrier for the combustion from air and O 2 -depleted gas are set in such a way that a flame temperature of 1300° C. is not exceeded.   
     
     
         7 . Method according to  claim 1 ,
 characterised in that   a recirculated process gas from a grinding operation, in particular a grinding plant for solid fuels, is used as O 2 -depleted gas.   
     
     
         8 . Method according to  claim 1 ,
 characterised in that   coke furnace gas is used as high-calorific gas and blast furnace gas as low-calorific gas.   
     
     
         9 . Multi-gas burner for a low-calorific operation with a low-calorific combustion gas and for a high-calorific operation with a high-calorific combustion gas, having
 a combustion chamber,   at least one burner lance, with a first, a second and a third nozzle,   a first, second and third feed chamber which are each connected in terms of flow to a respective nozzle for feeding gases into the combustion chamber,   wherein the nozzles terminate with one end in the combustion chamber and with another end in a respective feed chamber,   wherein the combustion chamber has a burner muffle in the region of the end of the nozzles,   wherein the first feed chamber is designed for feeding of an oxygen carrier for combustion and   wherein the third feed chamber is designed for feeding of the high-calorific combustion gas,   characterised in that   the second feed chamber is designed for feeding of the low-calorific combustion gas and O 2 -depleted gas and   a feed unit for feeding the low-calorific combustion gas and the O 2 -depleted gas into the second feed chamber, which is designed to introduce either the low-calorific combustion gas or the O 2 -depleted gas, in dependence upon the operating mode of the multi-gas burner, into the second feed chamber.   
     
     
         10 . Multi-gas burner according to  claim 9 ,
 characterised in that   the first nozzle is an outer nozzle, the second nozzle is a central nozzle and the third nozzle is an inner nozzle of the burner lance,   the first nozzle is connected in terms of flow to the first feed chamber,   the second nozzle is connected in terms of flow to the second feed chamber,   the third nozzle is connected in terms of flow to the third feed chamber.   
     
     
         11 . Multi-gas burner according to  claim 9 ,
 characterised in that   a control unit is provided which is designed, during low-calorific operation, to introduce air into the first feed chamber, the low-calorific combustion gas into the second feed chamber and to block the feed to the third feed chamber,   and the control unit is designed, during high-calorific operation, to introduce air into the first feed chamber, O 2 -depleted gas into the second feed chamber and the high-calorific combustion gas into the third feed chamber.   
     
     
         12 . Multi-gas burner according to  claim 9 ,
 characterised in that   a ratio of the cross-sectional areas of the first to the second to the third nozzle is dependent upon the λ values used, the low-calorific and high-calorific combustion gas and/or the respective stoichiometric air requirement, and lies in particular in the region of approximately 4.5-4.9:6.0-6.4:1.   
     
     
         13 . Multi-gas burner according to  claim 9 ,
 characterised in that   a plurality of burner lances are provided and each first nozzle is connected in terms of flow to the first feed chamber, each second nozzle to the second feed chamber and each third nozzle to the third feed chamber.   
     
     
         14 . Processing plant,
 having a multi-gas burner according to  claim 9  and a thermal process, wherein recirculated process gas from the thermal process is used as O 2 -depleted gas.