Rotary kiln and method for burning carbonate-containing material, in particular limestone or dolomite

Patent metadata

Field	Value
Publication number	US-12253309-B2
Application number	US-202218280343-A
Country	US
Kind code	B2
Filing date	Mar 7, 2022
Priority date	Mar 5, 2021
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

The present invention relates to a rotary kiln for burning carbonate-containing material, in particular limestone or dolomite, including a rotary tube with an inlet end for the feeding of the material to be burned and an outlet end for the discharging of the burned material, the rotary tube having an inlet zone at its inlet end and an outlet zone at its outlet end wherein a preheating zone and a combustion zone are arranged between the inlet zone and outlet zone, the rotary kiln being characterized according to the invention in that in the inlet zone of the rotary tube at least one projection is provided, the at least one projection having at least one sliding surface inclined to the longitudinal axis of the rotary tube for conveying the material to be burned from the inlet zone into the preheating zone. The present invention further relates to a method for burning carbonate-containing material, in particular limestone or dolomite.

First claim

The invention claimed is:

1. A rotary kiln for burning carbonate-containing material comprising:
a rotary tube comprising:
an inlet end for feeding of material to be burned;
an outlet end for discharging of burned material;
an inlet zone at the inlet end;
an outlet zone at the outlet end; and
a preheating zone and a burning zone arranged between the inlet zone and outlet zone,

wherein a plurality of projections are provided in the inlet zone of the rotary tube, each projection of the plurality of projections having at least one sliding surface inclined to a longitudinal axis of the rotary tube for conveying the material to be burned from the inlet zone into the burning zone, and
wherein the plurality of projections are arranged in a row as a group in such a way that respective sliding surfaces of the projections form a common sliding surface for the material to be burned.

2. The rotary kiln according to claim 1 , wherein the at least one sliding surface of at least one of the plurality of projections has an inclination to the longitudinal axis of the rotary tube from 15° to 70°.

3. The rotary kiln according to claim 1 , wherein at least one of the plurality of projections contains a refractory material, the refractory material being concrete.

4. The rotary kiln according to claim 1 , wherein at least one of the plurality of projections has a prismatic geometry.

5. The rotary kiln according to claim 1 , wherein at least one of the plurality of projections has a height extending in a radial direction of the rotary tube of 100 mm to 500 mm,
and/or at least one of the plurality of projections has a length extending substantially parallel to the longitudinal axis of the rotary tube of 100 mm to 2000 mm,
and/or at least one projection of the plurality of projections is attached by metallic anchoring to an inner side of the rotary tube.

6. The rotary kiln according to claim 1 , wherein the common sliding surface formed by the plurality of projections extends substantially over an entire length of the inlet zone.

7. The rotary kiln according to claim 6 , wherein the common sliding surface for the material to be burned is provided by 3 to 9 projections.

8. The rotary kiln according to claim 6 , wherein the plurality of projections are formed substantially identically to one another, such that a common sliding surface is formed with a substantially constant slope,
and/or the plurality of projections are arranged in rows in a stepped form as a group along the inlet zone.

9. The rotary kiln according to claim 1 , wherein 2 to 8 projections or groups of projections are arranged in the row over a circumference of the rotary tube.

10. The rotary kiln according to claim 1 , wherein the rotary tube has at least one further projection in the preheating zone.

11. The rotary kiln according to claim 1 , wherein a plurality of further projections are provided in the preheating zone, the further projections being arranged as groups substantially parallel to the longitudinal axis of the rotary tube, wherein, optionally, the further projections arranged adjacent to one another in a circumferential direction, each belonging to adjacent groups of further projections, are arranged offset from one another in the longitudinal direction of the rotary tube in such a way that spiral-shaped transport paths are formed for the material to be burned.

12. The rotary kiln according to claim 1 , wherein the rotary tube has at least one additional projection in the outlet zone, in order to prevent the formation of clusters in the burned material.

13. The rotary kiln according to claim 1 , wherein a plurality of additional projections are provided in the outlet zone, the additional projections being arranged as groups in a circumferential direction of the rotary tube.

14. A method for burning carbonate-containing material comprising:
introducing the carbonate-containing material into the rotary tube of a rotary kiln according to claim 1 ,
burning the carbonate-containing material, the carbonate-containing material moving through the rotary tube from the inlet zone and the burning zone to the outlet zone, the rotary tube rotating in a direction of rotation, and
conveying the carbonate-containing material from the inlet zone into the preheating zone, in that the carbonate-containing material rests at least partially on the common sliding surface of the plurality of projections, which is inclined to the longitudinal axis of the rotary tube, and slides, driven by gravity, in a direction of the preheating zone.

15. The rotary kiln according to claim 1 , wherein at least one of the plurality of projections is a straight prism with a triangular base.

16. The rotary kiln according to claim 1 , wherein at least one of the plurality of projections has a height extending in a radial direction of the rotary tube of 140 mm to 400 mm,
and/or at least one of the plurality of projections has a length extending substantially parallel to the longitudinal axis of the rotary tube of 150 mm to 1000 mm,
and/or at least one projection of the plurality of projections is attached by a welded metallic anchoring to an inner side of the rotary tube.

17. The rotary kiln according to claim 6 , wherein the common sliding surface for the material to be burned is provided by 4 to 8 projections.

18. The rotary kiln according to claim 1 , wherein 3 to 7 projections or groups of projections are arranged in the row over a circumference of the rotary tube.

19. The rotary kiln according to claim 1 , wherein a plurality of additional projections are provided in the outlet zone, the additional projections being arranged as groups in a circumferential direction of the rotary tube and offset from one another in the longitudinal direction of the rotary tube.

20. The rotary kiln according to claim 1 , wherein there are substantially no gaps between individual projections of the plurality of projections in the row, such that the common sliding surface is substantially continuous.

Assignees

• Lhoist Rech Et Developpement Sa

Inventors

• Kaczinski Carsten

Classifications

• F27M2003/03

  Calcining · CPC title

• F27B2007/165

  forming a helical lifting projection · CPC title

• C04B2/10

  Preheating, burning calcining or cooling (decarbonation during burning of cement raw materials C04B7/43; {obtaining CaO or MgO otherwise than by thermal decomposition of the corresponding carbonates C01F11/02, C01F5/02}) · CPC title

• Y02P40/40

  Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills · CPC title

• F27B7/162 Primary

  the projections consisting of separate lifting elements, e.g. lifting shovels · CPC title