SPRAY NOZZLE FOR PRODUCING A UREA-SULFUR FERTILIZER

Abstract

A spray nozzle for production of urea fertilizer granules and/or urea-sulfur fertilizer granules has a conveying channel and an atomizing gas channel. The conveying channel has at least one separating pin and the atomizing channel has at least one swirl element. The swirl element has inserts, cutouts and moving and fixed elements. The disclosure also sets out a fluidized bed granulator with a spray nozzle for production of a urea-sulfur fertilizer, a process for producing a urea-sulfur fertilizer, and the use of the spray nozzle for production of fertilizer granules.

Claims

1.-18. (canceled)

19. A spray nozzle for production of urea fertilizer granules and/or urea-sulfur fertilizer granules, the nozzle comprising: a conveying channel, and an atomizing gas channel, the conveying channel comprising a separating pin, the atomizing channel comprising a swirl element, wherein the swirl element comprises inserts, cutouts, and moving and fixed elements, and wherein the conveying channel and the atomizing gas channel are planar to one another and form a common exit opening.

20. The spray nozzle of claim 19 wherein the conveying channel has two crossing separating pins.

21. The spray nozzle of claim 19 wherein the separating pin comprises cylindrical, angular and/or conical inserts and/or rods and/or wires.

22. A fluidized bed granulator comprising at least one spray nozzle according to claim 19 disposed atop a perforated plate.

23. A process for producing a urea-sulfur fertilizer, comprising: providing a melt containing urea and elemental sulfur; spraying the melt and atomizing gas into a fluidized bed granulator with a spray nozzle; and obtaining granules in the fluidized bed granulator; wherein the spray nozzle comprises a conveying channel and an atomizing gas channel, wherein the conveying channel comprises a separating pin and the atomizing channel comprises a swirl element, and wherein the melt is introduced via the conveying channel at a pressure of about 0.5 bar to 7 bar.

24. The process of claim 23 wherein the spray nozzle is maintained at a temperature in the range from 1° C. to 10° C. above the crystallization temperature of the melt.

25. The process of claim 23 wherein the melt is introduced via the conveying channel at a flow rate of about 50 kg/h to 600 kg/h.

26. The process of claim 23 wherein atomizing gas is introduced via the atomizing channel at a flow rate of about 50 kg/h to 400 kg/h and/or is introduced at a pressure of about 0.1 bar to 2 bar.

27. The process of claim 23 wherein the melt is obtained by continuously mixing a urea-containing melt and an elemental sulfur-containing melt.

28. The process of claim 23 wherein the granules contain about 2% by weight to 30% by weight of sulfur.

29. The process of claim 23 wherein the melt contains an additive which is amphiphilic with respect to urea and elemental sulfur.

30. The process of claim 29 wherein the amphiphilic additive comprises anionic, cationic or nonionic surfactants.

31. The process of claim 30 wherein the amphiphilic additive comprises salts and esters of fatty acids, SDS, AOT, lignin and/or lignosulfonates and/or mixtures and/or derivatives thereof.

32. The process of claim 23 wherein the melt is free of any additive that is amphiphilic with respect to urea and elemental sulfur.

33. The process of claim 23 wherein the melt contains a granulating auxiliary.

34. The process of claim 33 wherein the granulating auxiliary is formaldehyde or a formaldehyde-free granulating additive.

35. The process of claim 34 wherein the formaldehyde-free granulating additive comprises a combination of at least one polymer or oligomer containing amino groups and at least one functionalized polyvinyl compound

36. The process of claim 35 wherein the formaldehyde-free granulating additive comprises a combination of polyethyleneimine and polyvinyl alcohol.

37. The process of claim 34 wherein the formaldehyde-free granulating additive comprises: a combination of at least one polymer or oligomer containing amino groups and at least one functionalized polyvinyl compound; and/or a compound selected from the group of the aliphatic dicarboxylic acids and anhydrides, the aliphatic tricarboxylic acids and anhydrides, the aromatic dicarboxylic acids and anhydrides; and/or an aliphatic C.sub.2-C.sub.8 dialdehyde.

Description

[0057] The invention is further elucidated in detail by the figures that follow. The figures do not restrict the scope of protection of the invention, but serve merely for illustration. The figures are not true to scale.

[0058] The figures show:

[0059] FIG. 1: a schematic cross section through the spray nozzle of the invention,

[0060] FIG. 2: a schematic top view of the spray nozzle of the invention and

[0061] FIG. 3: a further schematic cross section of the spray nozzle of the invention disposed within the perforated plate.

[0062] FIG. 1 shows a schematic cross section through the inventive spray nozzle (4) comprising a conveying channel (5) and an atomizing gas channel (6). The spray nozzle (4) is characterized in that the conveying channel (5) has at least one separating pin (7), for example in the form of a tube mounted in the atomizing channel (6). The atomizing channel (6) has at least one swirl element (8). The melt (1) is divided in the region of the separating pin (7) and swirled, preferably in a turbulent manner. This swirling surprisingly increases the homogeneity of the melt (1). The atomizing gas (9) is guided through the spray nozzle (1) via the atomizing channel (6). The swirl elements (8) mounted in the atomizing channel (6) increase the turbulence of the atomizing gas (9) passed through, for example air. If oxygen-sensitive granules are to be produced, rather than air, it is also possible to use gases/gas mixtures composed of noble gases, especially argon, nitrogen or carbon dioxide. The mixing of melt (1) and atomizing gas is effected outside the exit area (3) of the spray nozzle (4). This mixing of the melt outside the spray nozzle (4) ensures particularly uniform particle growth.

[0063] FIG. 2 shows a schematic top view of the inventive spray nozzle (4), restricted to the atomizing channel (6) and conveying channel (5). The separating pins (7) are in a crossed arrangement.

[0064] FIG. 3 shows a further schematic cross section of the inventive spray nozzle (4) arranged in the perforated plate (10). The spray nozzle comprises a conveying channel (5) and an atomizing gas channel (6). The conveying channel (5) comprises two crossing separating pins (7); the atomizing channel (6) comprises swirl elements (8). The melt (1) and the atomizing gas (9) mix outside the planar exit opening (3), where they meet the granule particles (12) present in the fluidized bed (not shown) in the form of microdroplets (11). The granule particles (12) grow to their ultimate size (not shown) by virtue of the addition of the microdroplets (12) and are subsequently removed from the fluidized bed granulator interior (2) (not shown).

LIST OF REFERENCE NUMERALS

[0065] (1) melt

[0066] (2) fluidized bed granulator interior

[0067] (3) exit area

[0068] (4) spray nozzle

[0069] (5) conveying channel

[0070] (6) atomizing channel

[0071] (7) separating pin

[0072] (8) swirl element

[0073] (9) atomizing gas

[0074] (10) perforated plate

[0075] (11) melt droplets

[0076] (12) granule particles