Claims
- 1. A method for introducing solid, liquid or gaseous fuel into a burning zone of a rotary kiln, by which method fuel is conducted through and primary air is conducted through at least two annular ducts arranged substantially concentrically with, and around, the fuel duct(s), the portion of air in one of the air ducts flowing substantially axially, whereas the portion of air in the second of the air ducts comprises air which has a rotary component about the centre axis of the burner of the rotary kiln, and the amount of primary air in the two portions being independently controlled, characterized in that the two portions of primary air are mixed at a lower velocity in a collecting duct into a single primary mixed airstream which is subsequently accelerated up to a desired, higher discharge velocity.
- 2. A method according to claim 1 wherein the mixed primary airstream is accelerated by a factor of between 5 and 12.
- 3. A method according to claims 1 or 2, wherein in the axial flow velocity of the primary air in the two air ducts range between 20 and 25 m/s, and that the mixed primary airstream is accelerated up to a flow velocity of between 160 and 200 m/s.
- 4. A method according to any one of claims 1 or 2, wherein air in the second air duct is caused to rotate about the centre axis of the burner by being directed past a number of oblique blades immediately upstream of the discharge end of the duct.
- 5. A burner for introducing solid, liquid or gaseous fuel into a burning zone of a rotary kiln, which burner comprises at least one duct for conducting the fuel and at least two annular ducts arranged outside substantially concentrically with, and around, the fuel duct(s) for conducting primary air, the air ducts being arranged to cause the portion of air in one of these air ducts to flow axially and the portion of air in the second air duct to flow with a rotary component about the centre axis of the burner of the rotary kiln, and means for independently controlling the amount of primary air in the two portions; characterized in that the primary air ducts discharge into a joint annular collecting duct for conducting the mixed primary air to an annular nozzle, and in that the flow area of the collecting duct decreases gradually in the axial direction of movement of the air.
- 6. A burner according to claim 5, wherein the flow area of the collecting duct decreases by a factor of between 5 and 12.
- 7. A burner according to claim 5 or 6, wherein the primary air ducts and controlling means are arranged so that the axial velocity of the flow in the primary air ducts ranges between 20 and 25 m/s, and in that the collecting duct is arranged so that the mixed primary airstream is accelerated up to a flow velocity of between 160 and 200 m/s.
- 8. A burner according to claim 7, wherein the collecting duct is made up of two concentric annular elements, of which the outermost element is configured as a frustocone which is convergent in the direction of flow with an angle of inclination of between 30 and 60° relative to the centre axis of the burner.
- 9. A burner according to any one of claims 5 to 6, wherein the second air duct is provided immediately upstream of the discharge end of said second air duct, with a number of oblique blades for giving the portion of air in the second air duct its rotary component.
- 10. A burner according to any one of claims 5 to 6, wherein the nozzle is made up of two concentric annular elements, of which at least one is formed as a frustocone so that the nozzle area can be varied through an axial displacement of the two elements relative to one another.
- 11. A method according to claim 4, wherein air in the second air duct is caused to rotate about the centre axis of the burner by being directed past a number of oblique blades immediately upstream of the discharge end of the duct.
- 12. A burner according to claim 7, wherein the second air duct is provided immediately upstream of the discharge end of the duct, with a number of oblique blades for giving the portion of air in the second air duct its rotary component.
- 13. A burner according to claim 8, wherein the second air duct is provided immediately upstream of the discharge end of the duct, with a number of oblique blades for giving the portion of air in the second air duct its rotary component.
- 14. A burner according to claim 7, wherein the nozzle is made up of two concentric annular elements, of which at least one is formed as a frustocone so that the nozzle area can be varied through an axial displacement of the two elements relative to one another.
- 15. A burner according to claim 8, wherein the nozzle is made up of two concentric annular elements, of which at least one is formed as a frustocone so that the nozzle area can be varied through an axial displacement of the two elements relative to one another.
- 16. A burner according to claim 9, wherein the nozzle is made up of two concentric annular elements, of which at least one is formed as a frustocone so that the nozzle area can be varied through an axial displacement of the two elements relative to one another.
Priority Claims (1)
Number |
Date |
Country |
Kind |
0244/97 |
Mar 1997 |
DK |
|
Parent Case Info
This is a continuation of copending International Application No. PCT/EP98/00145 filed Jan. 13, 1998.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2070761 |
Sep 1981 |
GB |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/EP98/00145 |
Jan 1998 |
US |
Child |
09/346518 |
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US |