FLUID-BED GRANULATOR SYSTEM WITH COATING MATERIAL TO PREVENT DUST BUILDUP IN THE AIR SYSTEMS OF UREA GRANULATION PLANTS

Abstract

A fluid-bed granulator system may include a fluid-bed granulator, a scrubber unit, and a connection-duct between an air vent opening of the fluid-bed granulator and the scrubber unit. An inner surface of the connection-duct may be at least partially coated with an anti-adhesion layer. The system may further include a granulator space inside the fluid-bed granulator, a perforated plate disposed inside the granulator space, spray nozzles disposed at the perforated plate, a fluidization air inlet, supply lines for atomization air connected to the spray nozzles, supply lines for a liquid melt connected to the spray nozzles, a granulation seeds inlet, a granulator outlet opening, and an air vent opening. A disclosed urea granulation plant may utilize the fluid-bed granulator system.

Claims

1.-14. (canceled)

15. A fluid-bed granulator system comprising: a fluid-bed granulator; a scrubber unit; and a connection-duct between an air vent opening of the fluid-bed granulator and the scrubber unit, wherein an inner surface of the connection-duct is at least partially coated with an anti-adhesion layer.

16. The fluid-bed granulator system of claim 15 comprising: a granulator space inside the fluid-bed granulator; a perforated plate disposed inside the granulator space; spray nozzles disposed in, on, or beside the perforated plate; a fluidization air inlet; supply lines for atomization air connected to the spray nozzles; supply lines for a liquid melt connected to the spray nozzles; a granulation seeds inlet; a granulator outlet opening; and an air vent opening.

17. The fluid-bed granulator system of claim 15 wherein the anti-adhesion layer comprises an organic silicon compound.

18. The fluid-bed granulator system of claim 15 wherein at least 10% of the inner surface of the connection-duct is coated with the anti-adhesion layer.

19. The fluid-bed granulator system of claim 15 wherein a cleaning nozzle is disposed inside the connection-duct.

20. The fluid-bed granulator system of claim 19 wherein the cleaning nozzle is disposed at a location within 2% to 90% of an in-duct distance between an air vent opening and the scrubber unit inside the connection-duct.

21. The fluid-bed granulator system of claim 19 wherein the cleaning nozzle is disposed in a vertical section of the connection-duct.

22. The fluid-bed granulator system of claim 15 wherein the anti-adhesion layer comprises an organic silicon compound that is comprised of polyalkylsilicone compounds, polyarylsilicone compounds, polyallylsilicone compounds, and/or mixtures or derivatives of alkyl-, aryl- and allyl silicone compounds.

23. The fluid-bed granulator system of claim 22 wherein the organic silicon compound is comprised of polyalkylsiloxane, polymethylsiloxane, polydimethylsiloxane, polymethylphenylsiloxane, perfluoroalkylsilane, perfluoroalkylsiloxane, and/or mixtures or derivatives thereof.

24. The fluid-bed granulator system of claim 23 wherein the organic compound comprises polymethylsiloxane.

25. The fluid-bed granulator system of claim 15 wherein the anti-adhesion layer has a thickness of 0.5 μm to 1000 μm.

26. The fluid-bed granulator system of claim 15 wherein the perforated plate is at least partially coated with the anti-adhesion layer.

27. The fluid-bed granulator system of claim 15 wherein a cleaning nozzle is disposed inside the connection-duct, wherein the cleaning nozzle is disposed in a horizontal section of the connection-duct.

28. A urea granulation plant comprising the fluid-bed granulator system of claim 15.

29. A method comprising: utilizing the fluid-bed granulator system of claim 15 to produce fertilizer granules containing ammonia compounds, nitrates, phosphates, urea, elemental sulfur, ammonia sulfate, urea-ammonia sulfate (UAS), and/or mixtures thereof.

Description

[0037] The invention is further described in the following figures. The figures are meant for illustrative purpose only and do not restrict the scope of protection. The figures are not true to scale.

[0038] FIG. 1 shows a fluid-bed granulator system according to the state of the art,

[0039] FIG. 2 shows a fluid-bed granulator system according to the invention and

[0040] FIG. 1 shows a fluid-bed granulator system according to the state of the art comprising a fluid-bed granulator (14) with a granulator space (1) inside the fluid-bed granulator (14) and a perforated plate (2) located inside the granulator space (1). Spray nozzles (3) are located on or above the perforated plate (2), a fluidization air inlet (15) is located below the perforated plate (2). Multiple supply lines for atomization air (4) and supply lines for a liquid melt (5) are connected to the spray nozzles (3). The granulator further comprises a granulation seeds inlet (6), preferably in connection with a not shown product sieve or crusher, a granulator outlet opening (7) and an air vent opening (8). The fluid-bed (17) is formed by the corresponding granular particles (16) utilizing the fluidization air from below the perforated plate (2). The fluidization air flow is indicated by arrows labeled (II), the flow direction of the fluid bed granular particles (16) is indicated by arrows labeled (I). The fluid-bed (17) is preferably divided by one or more separating walls (22). The fluid-bed granulator system further comprises a scrubber unit (9) and a connection-duct (10) between the air vent opening (8) and the scrubber unit (9). Preferably, the scrubber unit (9) comprises at least one (not shown) dust scrubber and one ammonia scrubber (not shown). A connection-duct (10) connects the fluid-bed granulator (14) with the scrubber unit (9) via the vent opening (8) and the scrubber opening (23). A cleaning nozzle (13) is located near the vent opening (8) at (d.sub.i), prohibiting the adhesion, caking and blocking of the inner connection-duct (10) by urea dust in this area by spraying water in the direction of the air vent opening (8). However, part of the water and urea dust clusters may drop into the fluid-bed (17). This may disturb the homogeneous particle grow and air flow. The water flow will lead to large scale agglomeration inside the fluid-bed granulator, thereby obstructing proper operation of the fluid bed-granulator.

[0041] FIG. 2 shows a fluid-bed granulator system according to the invention. The principal setup is identical with the fluid-bed granulator system setup described in FIG. 1. However the inner surface of the connection-duct (10) is at least partially coated with an anti-adhesion layer (11) comprising an organic silicon compound. The anti-adhesion layer (11) prohibits or reduces the adhesion, caking and blocking of urea dust in the connection-duct. Therefore, the cleaning nozzle (13) can be either omitted or be placed more remote to the air vent opening (8) at (d.sub.i), preferably in a vertical section of the connection-duct (10). This before mentioned positioning of the cleaning nozzle or nozzles (13) omits the need to spray water near the air vent opening (8). Simultaneously, the amount of water and urea dust clusters dropping back into the fluid-bed (17) is significantly reduced, leading to longer/extended operation cycles and better product quality. In addition the cleaning nozzle (13) can be used to quench the hot air stream originating from the granulator space (1) of the fluid-bed granulator (14). Therefore the temperature of the before mentioned hot air stream can be reduced before entering the scrubbing unit (9), omitting or reducing additional quenching steps.

REFERENCE SIGNS

[0042] (1) granulator space

[0043] (2) perforated plate

[0044] (3) spray nozzles

[0045] (4) supply lines for atomization air

[0046] (5) supply lines for a liquid melt

[0047] (6) granulation seeds inlet

[0048] (7) granulator outlet opening

[0049] (8) air vent opening

[0050] (9) scrubber unit

[0051] (10) connection-duct

[0052] (11) anti-adhesion layer

[0053] (12) inner surface of the connection-duct

[0054] (13) cleaning nozzle

[0055] (14) fluid-bed granulator

[0056] (15) fluidization air inlet

[0057] (16) granular particles

[0058] (17) fluid-bed

[0059] (22) separating walls

[0060] (23) scrubber opening

[0061] (d.sub.0) relative in-duct distance at the air vent opening

[0062] (d.sub.i) relative in-duct distance at a given point, e.g. position of the cleaning nozzle

[0063] (d.sub.100) relative in-duct distance at the scrubber opening

[0064] (I) flow direction of the granules

[0065] (II) flow direction of fluidization air