DEVICE AND METHOD FOR THE THERMAL TREATMENT OF A MINERAL FEEDSTOCK

Abstract

The present invention relates to apparatus for thermal treatment of a mineral starting material, wherein the apparatus comprises a calciner, wherein the calciner comprises at least a first calciner section and a second calciner section, wherein the first calciner section is arranged vertically, wherein the second calciner section is arranged at an incline, wherein the second calciner section has an angle ? between the horizontal and the flow direction of the second calciner section, wherein the angle ? is between 20? and 80?, wherein the first calciner section has a first hydraulic diameter d.sub.h,1, wherein the second calciner section has a second hydraulic diameter d.sub.h,2, wherein the second hydraulic diameter d.sub.h,2 is less than or equal to the first hydraulic diameter d.sub.h,1 multiplied by the sine of the angle ?.

Claims

1-17. (canceled)

18. An apparatus for thermal treatment of a mineral starting material, comprising: a calciner, including at least a first calciner section and a second calciner section, wherein the first calciner section is arranged vertically, wherein the second calciner section is arranged at an incline, wherein the second calciner section has an angle ? between the horizontal and a flow direction of the second calciner section, wherein the angle ? is between 20? and 80?, wherein the first calciner section includes a first hydraulic diameter d.sub.h,1, wherein the second calciner section includes a second hydraulic diameter d.sub.h,2, wherein the second hydraulic diameter d.sub.h,2 is less than or equal to the first hydraulic diameter d.sub.h,1 multiplied by the sine of the angle ?.

19. The apparatus of claim 18, wherein the first calciner section and the second calciner section are configured to have a gas stream flow through them from bottom to top.

20. The apparatus of claim 18, wherein the first calciner section is arranged below the second calciner section.

21. The apparatus of claim 18, further comprising a third calciner section, wherein the third calciner section is arranged vertically, and above the second calciner section.

22. The apparatus of claim 18, wherein the second calciner section includes a first starting material feed, wherein the first starting material feed is arranged in the lower 20% of the second calciner section, wherein the first starting material feed supplies starting material into the gas stream of the second calciner section from above or into the gas stream of the second calciner section from the side.

23. The apparatus of claim 23, wherein the second calciner section includes a second starting material feed, wherein the second starting material feed is arranged in a middle region of the second calciner section, wherein the second starting material feed supplies starting material into the gas stream of the second calciner section from above or into the gas stream of the second calciner section from the side.

24. The apparatus of claim 18, wherein a second fuel feed for a solid fuel is arranged at an upper end of the second calciner section.

25. The apparatus of claim 18, wherein the lower side of the second calciner section is stepped.

26. The apparatus of claim 18, wherein the lower side of the second calciner section includes a moving grate.

27. The apparatus of claim 18, wherein the second calciner section includes an angle ? between the horizontal and the flow direction of the second calciner section, wherein the angle ? is between 30? and 70?.

28. The apparatus of claim 18, wherein the second calciner section is arranged below the first calciner section and a controllable bypass is arranged parallel to the second calciner section.

29. A process for operating an apparatus for thermal treatment of a mineral starting material, wherein the process is performed in an apparatus comprising a calciner having a vertical first calciner section and an inclined second calciner section, comprising: passing a gas stream through the first calciner section and the second calciner section, wherein the hydraulic diameter is four times a quotient of the Froude number flow cross section perpendicular to the flow direction divided by the flow circumference, wherein the Froude number at any point in the second calciner section is equal to or greater than a minimum Froude number in the first calciner section.

30. The process of claim 29, wherein the calciner is operated with an atmosphere comprising less than 25% nitrogen, preferably comprising less than 15% nitrogen, more preferably comprising less than 10% nitrogen, particularly preferably comprising less than 5% nitrogen.

31. The process of claim 29, wherein the Froude number in the second calciner section is greater than 0.7 and smaller than 9.

32. The process of claim 29, wherein second calciner section starting material is supplied from at least two positions via a first second starting material feed and a second starting material feed which are spaced apart from one another along the flow direction.

33. The process of claim 29, wherein a solid fuel with a chunk size of at least 90% of the mass of the fuel of more than 50 mm, is supplied in the second calciner section.

34. The process of claim 29, wherein an atomizable fuel is supplied in the first calciner section and starting material is supplied via a first starting material feed in the first calciner section.

Description

[0038] The apparatus according to the invention is more particularly elucidated hereinbelow with reference to a working example shown in the drawings.

[0039] FIG. 1 Apparatus for thermal treatment of a mineral starting material

[0040] FIG. 2 First exemplary calciner

[0041] FIG. 3 Second exemplary calciner

[0042] FIG. 4 Third exemplary calciner

[0043] FIG. 5 Fourth exemplary calciner

[0044] All illustrations are purely schematic, not to scale and are only used to elucidate the features of the invention.

[0045] FIG. 1 shows an apparatus for thermal treatment of a mineral starting material, for example a plant for production of cement clinker. The plant comprises a preheater 100, a calciner 110, a rotary kiln 120 and a cooler 130. The material, for example raw meal made from limestone is applied at the top, passes through the plant in the recited sequence and may be withdrawn from the cooler 130 as clinker. The gas flow is passed from the rotary kiln 120 into the calciner 110 and from there into the preheater 100 in countercurrent to the material stream.

[0046] Therefore in the following four exemplary calciner embodiments shown the gas stream enters from below from the direction of the rotary kiln 120 and flows upwards. The calciner 110 in each case has at least one cyclone separator not shown in the exemplary embodiments at the upper end.

[0047] In the following, identical reference numerals are used for identical elements and the differences between embodiments are elaborated in the description.

[0048] FIG. 2 shows a first calciner section 10 arranged vertically, thereabove a second calciner section 20 inclined at an angle of 45? and thereabove a third calciner section 30 arranged vertically. The first calciner section 10 has a first fuel feed 12 for an atomizable fuel, for example coal dust, and a first first starting material feed 14, by means of which starting material from the preheater 100 is supplied. The combustion of the fuel in the first calciner section 10 forms energy which is used for the deacidification of the starting material, thus generating CO.sub.2. In the second calciner section 20 a solid fuel is supplied from above through the second fuel feed 22, for example via a screw, and said fuel is then burnt on the inclined surface of the second calciner section 20. Combustion residues, for example metal constituents of the fuel, fall through the first calciner section 10 and may then be withdrawn therebelow. The second calciner section 20 further comprises a first second starting material feed 24, by means of which starting material from the preheater may likewise be added. Arranged above the second calciner section 20 is a third calciner section 30 which comprises a third fuel feed 32 and a first third starting material feed 34.

[0049] As indicated in FIG. 2 the cross section of the second calciner section 20 is smaller than the cross section of the first calciner section 10. For example the cross section is about 30% smaller than the cross section of the first calciner section 10, which corresponds to the sine of 45?.

[0050] In the second embodiment of the calciner 110 shown in FIG. 3 the second calciner section 20 comprises, additionally to the first embodiment shown in FIG. 2, a second second starting material feed 26 which makes it possible to achieve better uniformization of the energy consumption and thus of the temperature in the second calciner section 20.

[0051] In the third embodiment of the calciner 110 shown in FIG. 4, the second calciner section 20 has steps 21 for the combustion of a solid fuel. The steps 21 may be level as in the example shown but the steps 21 may also be inclined in the flow direction or counter to the flow direction.

[0052] The fourth embodiment of the calciner 110 shown in FIG. 5 has a markedly different construction. The gas stream is initially split and only a substream is passed through the second calciner section 20. A further substream flows past the second calciner section via a bypass and a flow control valve 42 and is recombined with the gas stream exiting the second calciner section 20 and then passed into the first calciner section 10.

LIST OF REFERENCE NUMERALS

[0053] 10 First calciner section [0054] 12 First fuel feed [0055] 14 First first starting material feed [0056] 20 Second calciner section [0057] 21 Steps [0058] 22 Second fuel feed [0059] 24 First second starting material feed [0060] 26 Second second starting material feed [0061] 30 Third calciner section [0062] 32 Third fuel feed [0063] 34 First third starting material feed [0064] 40 Bypass [0065] 42 Flow control valve [0066] 100 Preheater [0067] 110 Calciner [0068] 120 Rotary kiln [0069] 130 Cooler