Flow bed granulator

Description

[0001] The invention relates to a fluidized bed granulator for the production of urea-containing granules, a granulation plant with such a fluidized bed granulator, a method for the production of a urea-containing granule and the use of the fluidized bed granulator according to the invention for the production of a urea-containing granule.

[0002] In light of global population growth, the development of flexible and efficient fertilizers is of great and increasing importance. This involves not only the fertilizer itself, i.e., its chemical composition, but also its processing into transportable containers and its application to the field. Of paramount importance here is undoubtedly the granulation into uniform particles of consistent size and texture. Key parameters include low dust formation, strength, low aggregation tendency, homogeneous size, storability, and stability. Fluidized bed granulation is an established granulation technique that exhibits improved particle properties compared to, for example, prilling and pastillation techniques.

[0003] An example of the production of urea-containing fertilizer granules by means of fluidized bed granulation can be found in WO 2010 / 060535 A1, e.g. in paragraphs

[0025] -

[0035] , Figure 1or US 4,701,353 A, DE 31 16 778 A1 and US 4,219,589 A.

[0004] A very large proportion of global fertilizer production consists of urea-based fertilizers. This water-soluble fertilizer breaks down in the soil into ammonium salts or nitrates and represents an important base fertilizer. This urea-based fertilizer can be combined with other elements such as potassium, phosphates, or sulfur compounds.

[0005] The use of urea-sulfur fertilizer in agriculture has been known for some time. In such fertilizer mixtures, both nitrogen and sulfur can be supplied to the plant simultaneously, thus saving steps and costs associated with applying a separate fertilizer. In combination with urea, this allows, for example, the early supply of nitrogen to sown plants via the urea and sulfur in subsequent growth phases.

[0006] For this reason, urea-sulfur fertilizers with a homogeneous distribution of urea and sulfur are becoming increasingly important. Examples can be found, for instance, in US 4,330,319 A.

[0007] Modern granulation plants for urea-containing fertilizer granules enable production volumes ranging from 2,000 to 4,000 tons per day. These production volumes necessitate a correspondingly sized fluidized bed granulator. In a typical fluidized bed granulator, the granule discharge is located on one narrow side, and the granule / seed inlet is on the opposite side. This generally poses no problem in the technical implementation of smaller fluidized bed granulators (up to approximately 30 m²).

[0008] To transport the granules into the screening / milling circuit, a coarse screen is often installed at the fluidized bed granulator outlet to separate large agglomerates or oversized particles. This is followed by at least one bucket elevator, which conveys the granules upwards within the granulation building to the screens. From this highest point in the granulation plant, the solid material then preferably reaches all subsequent process steps and equipment solely by gravity. From the screens, approximately 30% of the granules, for example, return to the inlet side of the fluidized bed granulator via inclined chutes as seed material / return. The inlet side is opposite the outlet side, with each forming a narrow side of the fluidized bed granulator. The inclination of these chutes is designed to allow the product to flow freely while preventing it from falling, thus ensuring a uniform product flow.This results in the building height increasing by a factor of 1.2 to 1.7 due to the external bridging of the horizontal distance between the granule discharge side and the seed inlet side. Consequently, not only does the bucket elevator conveying the granules upwards become taller, but so does the entire building, creating a significant amount of unused volume. Therefore, with the current design, the building housing the fluidized bed granulator becomes progressively taller as the length of the granulator increases.

[0009] US 5,695,701 A discloses a fluidized bed granulator for rewetting agglomeration, in which the introduced particles are moistened to adhere to one another upon contact in the fluidized bed. The moistening medium required for rewetting is introduced via a longitudinally centrally arranged tube with atomizing nozzles, so that the particles in the fluidized bed are homogeneously wetted with the moistening liquid.

[0010] US Patent 7,128,936 B1 discloses the use of combined fluidized bed dryers and fluidized bed coolers for rewetting agglomeration, wherein the starting material for granulation is sprayed onto the outer surface of a rotating steel cylinder, from which the agglomerated powder is flung off while being dried with hot air. Downstream of the granulator, the hot agglomerated powder is first further dried in a fluidized bed using hot air and then cooled with cooling air.

[0011] German patent DE 43 16 320 A1 describes a device for dehydrating sodium perborate tetrahydrate in a fluidized bed. The interior of the fluidized bed dryer is divided into four zones with different air temperatures by weirs. In the two middle zones, plate-shaped contact surfaces oriented parallel to the conveying direction are provided as heat exchangers, which supply a portion of the heat energy required for dehydration, thus reducing the temperature and quantity of the air supplied for fluidization as well as the exhaust air losses.

[0012] EP 2 832 439 A1 discloses a coated fluidized bed granulator and an exemplary setup.

[0013] EP 1 581 333 B1 discloses a fluidized bed granulator in a compact design for the granulation of nitrate-containing particles.

[0014] EP 0 900 589 A1 discloses an energy-saving fluidized bed granulator and a method in which the recycling of product particles can be dispensed with.

[0015] The present invention aims to provide a fluidized bed granulator that does not exhibit the disadvantages of the prior art described above. The granulation building should also have a compact design with minimal unused space, even with high production volumes of urea-containing granules and thus very long fluidized bed granulators.

[0016] The object of the invention is achieved by a fluidized bed granulator for the production of urea-containing or nitrate-containing granules according to claim 1. Advantageous embodiments are described in the dependent claims.

[0017] The problem is further solved by a granulation plant according to claim 19 and a method for producing a urea-containing granulate according to claim 23. Advantageous embodiments are described in the dependent claims.

[0018] Furthermore, the invention includes the use of the fluidized bed granulator according to the invention for the production of a urea-containing granulate.

[0019] The fluidized bed granulator according to the invention for the production of urea-containing or nitrate-containing granules comprises at least: a granulator interior with granulator interior walls, comprising at least a first granulator side wall, a second granulator side wall, a granulator front wall extending transversely to the granulator side walls, and a granulator rear wall also extending transversely at the end of the granulator interior opposite the granulator front wall; a horizontally arranged perforated plate bounding the granulator interior downwards; at least one seed inlet opening and at least one granule outlet opening; wherein the at least one granule outlet opening is arranged at a distance in front of the granulator rear wall.

[0020] According to the present invention, at least one deflection device is provided in the interior of the granulator, which causes the flow of the granules within the granulator to be deflected such that the granule particles are deflected at least once in one direction, deviating from their initial flow direction towards the granule outlet opening. The deflection device further comprises at least two deflection plates, a first deflection plate of which extends, optionally at a distance beside the granule outlet opening, approximately in the flow direction of the granule particles, and a second deflection plate which extends in front of the granule outlet opening approximately transversely to the flow direction of the granule particles.

[0021] The granule outlet opening can be surrounded on two or three sides by deflection plates, with no deflection plate or a deflection plate with an opening arranged opposite the granulator rear wall.

[0022] According to a preferred embodiment of the present invention, the at least one granule outlet opening is arranged within the perforated plate.

[0023] According to a preferred embodiment of the present invention, at least one deflection device is provided in the interior of the granulator, which causes multiple flow deflections of the granule particles in the interior of the granulator, deviating from their initial flow direction towards the granule outlet opening.

[0024] According to a preferred embodiment of the present invention, at least one deflection device is provided in the interior of the granulator, which causes a flow deflection of the granule particles in the interior of the granulator by a total of about 180° deviating from their initial flow direction towards the granule outlet opening.

[0025] According to a preferred embodiment of the present invention, the deflection device comprises at least one deflection plate which extends approximately in the flow direction of the granule particles or at an acute angle to the flow direction of the granule particles and is arranged at a distance from the granulator side walls.

[0026] According to a preferred embodiment of the present invention, the deflection device comprises at least two deflection plates which are arranged at an acute angle or a right angle to each other or parallel to each other.

[0027] Instead of individual deflection plates that form an acute angle or a right angle to each other and thus initially shield the granule outlet opening from granule particles flowing in the original direction and effect the deflection, one can, for example, also provide an arc-shaped deflection plate that is shaped in such a way that it shields the granule outlet opening on one, two or three sides, but which has an opening at least on the side facing the rear wall of the granulator, so that deflected granule particles are directed from there into the granule outlet opening.

[0028] The fluidized bed granulator according to the invention comprises at least one granulator chamber with walls. The walls of the granulator chamber comprise at least a first side wall (preferably as the long side of the fluidized bed granulator), a second side wall (preferably as the long side of the fluidized bed granulator), a front wall (preferably as the short side or narrow side), and a rear wall (preferably as the short side or narrow side). A perforated plate is arranged within the granulator chamber, preferably horizontally above the chamber floor. Spray nozzles are preferably arranged in, above, or on the perforated plate. Alternatively, the spray nozzles can also be arranged separately from the perforated plate, for example, above the perforated plate or laterally within the granulator chamber (for example, on the side walls).The spray nozzles are preferably connected to atomization gas supply lines and melt supply lines for feeding the urea-containing fertilizer melt. For the purposes of this invention, the term "urea-containing fertilizer melt" also includes (within the limits of technical purity and with a water content of typically 1 wt.% to 10 wt.%) pure urea melts or urea solutions, or pure urea melts or urea solutions with a granulation additive such as formaldehyde, polyvinylamines, polyethylene vinyls (e.g., polyethyleneamine), polyethyleneimines, carboxylic acids, and / or aldehydes. Optionally, the atomization gas supply lines and melt supply lines can also be implemented as a combined line.For the purposes of this invention, the term "atomization gas supply line" comprises gas supply lines which, together with the melt to be granulated from the melt supply lines, produce finely dispersed melt droplets ("atomized" droplets) in the spray nozzles. For the purposes of this invention, the term "atomization" does not refer to the disintegration or decomposition of the melt droplets into individual atoms, but rather to the generation of small melt droplets, preferably in the range of 1 to 200 µm. For the purposes of this invention, the term "melt" comprises concentrated solutions, suspensions, emulsions, or dispersions, preferably with a proportion of the component to be dissolved in the urea-containing melt of greater than 0.5 wt.% to 50 wt.%, particularly preferably less than 30 wt.%.Furthermore, one or more seed inlet openings and one or more granule outlet openings are included, the distance between the seed inlet opening(s) and the granule outlet opening(s) defining an (imaginary) granule flow direction. The term "seed inlet opening" describes one or more openings or feeds through which smaller particles (smaller than the desired granule size) are introduced into the fluidized bed granulator as seed particles. The seed particles are sprayed with melt droplets via the spray nozzles. This "accretion" causes the seed particles to grow continuously. Preferably, at the microscopic level, the particles appear "raspberry-like" due to this growth, consisting of a core with molten, solidified (crystallized) droplets.

[0029] The fluidized bed granulator according to the invention is characterized in that the granule outlet opening is arranged at a distance from and in front of the granulator's rear wall. As a result, unlike in a conventional fluidized bed granulator, the granules are not discharged at the end of the granulator interior furthest from the seed inlet opening, but are instead deflected by a suitable deflection device in a direction deviating from the main flow direction and fed to the granule outlet opening in an area which, viewed in the flow direction, is located at a distance in front of the granulator's rear wall.

[0030] Furthermore, the granule outlet opening is arranged within the perforated plate. In the embodiment according to the invention, the granule outlet opening is surrounded, for example, by deflector plates, preferably U-shaped, with no deflector plate or a deflector plate with an opening being provided opposite the granulator rear wall. The deflector plates cause the granule particles in the fluidized bed to flow around and then be redirected, first past the granule outlet opening and then, with the flow direction reversed, within the deflector plates into the granule outlet opening. This allows the granule discharge to be arranged within the interior of the granulator. This surprisingly reduces the distance between the granule discharge (granule outlet opening) and the return / seed inlet (seed inlet opening) of the fluidized bed granulator by approximately 20–50%.The relocated granule discharge reduces the required height of the bucket elevator and the building height of the granulation building accordingly.

[0031] Preferably, the granulator interior includes a fluidizing gas supply line, as well as spray nozzles arranged in or on the perforated plate with supply lines for molten material and supply lines for atomizing gas. The supply lines for molten material and atomizing gas can be individual or combined. The fluidizing gas supply line allows the introduction of an air or gas flow, which creates a fluidized bed of granule particles above the perforated plate from below.

[0032] Preferably, the granulator interior above the perforated plate comprises growth zones and cooling zones. Preferably, spray nozzles are arranged in the perforated plates in the growth zones as described above, while the cooling zones lack spray nozzles or optionally have fewer spray nozzles than the growth zones. Alternating between growth and cooling zones allows for control of particle growth and temperature distribution. This is particularly useful for preventing biuretization at high temperatures.

[0033] In a preferred embodiment, two seed inlet openings are arranged in the area of ​​the granulator's front wall. Depending on the size of the fluidized bed granulator, additional seed inlet openings can be arranged on the first and second granulator side walls. Optionally, further seed inlet openings at other locations are also possible within the scope of the invention. A third and a fourth seed inlet opening in conjunction with a growth zone are particularly preferred.

[0034] The additional seed entry openings allow for control and additional temperature monitoring of the growth process of the granule particles.

[0035] Preferably, the granule outlet opening is arranged within the perforated plate and does not touch the granulator back wall.

[0036] In a further preferred embodiment, the deflection plates (8.1, 8.1+i with i = 0, 1, 2, 3, ...) are arranged in a U-shape or enclosing the granule outlet opening. The term "U-shaped or enclosing" also includes a round, rounded, straight, or angular arrangement of the deflection plates. Exemplary geometries include a rectangular or square arrangement in which the side opposite the granulator rear wall is missing or has an opening for the passage of the granules.

[0037] Furthermore, partitions are preferably arranged between the growth zones and cooling zones; these partitions preferably include perforations. The perforations are particularly preferably arranged in the lower region adjacent to or following the perforated plate.

[0038] In a further preferred embodiment, the deflection plate is designed as part of a partition. This embodiment also includes a section of the partition that does not have a passage opening for the granule particles.

[0039] Preferably, the granule outlet is arranged within a cooling zone. The invention further comprises a granulation system in which the granule outlet of the fluidized bed granulator is connected, via a coarse screen for separating coarse lumps and oversized granule agglomerates, to a conveying device, for example, one or two downstream bucket elevators or other conveying elements. For the purposes of this invention, the term "connected" includes other intermediate components such as fluidized bed coolers. The conveying device enables the further transport of the cooled granules upwards within the granulation building to a screening device preferably located there. The screening device enables the separation of the granule particles into particles within the preferred size range (e.g., often 2 mm to 4 mm for urea-containing particles), particles smaller than the preferred size range, and particles larger than the preferred size range.Preferably, particles larger than the preferred size range are crushed in a crusher or grinder and, together with particles smaller than the preferred size range, are returned as seed particles to the granulator interior via the seed inlet opening(s). The return of the seed particles preferably occurs solely by gravity to minimize the equipment required for seed particle transport. For this purpose, chutes are used, for example, whose angle of inclination is greater than the angle of repose of the granules. This arrangement essentially determines the height of the granulator building.

[0040] In a preferred embodiment, the conveying device is arranged, viewed in the direction of granule flow, at a distance of 20 to 80% of the total length of the first or second granulator side wall from the outer edge of the first or second granulator side wall. The inventive design of the granulation system allows the conveying device to be arranged centrally with respect to the longitudinal side of the fluidized bed granulator. The expression "arranged at a distance of 20 to 80% of the total length of the first or second granulator side wall from the outer edge of the first or second granulator side wall" means, within the meaning of the invention, that the conveying device is arranged from the front wall of the granulator at a distance of 20% to 80% of the total length of the first or second granulator side wall.With an exemplary side length of 20 m for the first or second granulator side wall, the conveying device is positioned outside the granulator interior, next to the first or second granulator side wall, at a distance of 4 m (20%) to 16 m (80%) from the granulator front wall. This more centralized positioning of the conveying device and the downstream screening unit allows for a reduction in the overall height of the granulation building, as the distance to be traversed from the conveying device to the seed inlet opening via the inclined chutes is reduced. The term "positioned" refers to the center of the conveying device's base.

[0041] In an alternative embodiment, the granule outlet, preferably via a coarse screen for separating coarse lumps and oversized granule agglomerates, is either connected to a separate fluidized bed cooler or is not connected to any separate fluidized bed cooler. Particularly preferably, the granule outlet is not connected to any separate fluidized bed cooler. In this embodiment, the fluidized bed granulator and the fluidized bed cooler are combined in the fluidized bed granulator according to the invention.

[0042] Preferably, the perforated plate of the fluidized bed granulator has inclined openings; particularly preferably, the inclined openings have an angle of 20° to 60° to the surface of the perforated plate. For the purposes of the invention, the term "inclined openings" encompasses openings, cutouts, cavities, protrusions, indentations, and similar elements arranged on the perforated plate, whether attached to, arranged on, or obtained by deformation of the perforated plate, which allow the airflow to be deflected from its vertical propagation by means of a simple, flat, optionally annular, opening. The inclined openings preferably have a maximum diameter of 1 mm to 3 mm.

[0043] Preferably, the inclined openings are inclined in different directions, particularly preferably along a granule flow direction, and especially preferably along the granule flow direction around the deflection plates towards the granule outlet opening. The arrangement of differently inclined openings supports the guidance of the granule particles through the fluidized bed granulator and along the deflection plates into the granule outlet opening.

[0044] The invention further comprises a process for producing a urea-containing or nitrate-containing granulate, comprising at least the following steps. In a first step, a urea-containing and / or nitrate-containing melt, or a concentrated urea-containing solution, is provided. Preferably, the melt also contains a weight fraction of 1 to 5 wt.% water; more preferably, the remaining weight fractions comprise urea, elemental sulfur, granulation additives, emulsifying additives, and / or ammonium sulfate. In a subsequent step, the urea-containing melt is sprayed into a fluidized bed granulator filled with fluidized granule particles as described above. In a further step, the urea-containing and / or nitrate-containing melt is granulated to obtain a urea-containing or nitrate-containing granulate.The melt droplets solidify on the surface of the fluidized particles when they are deposited, resulting in urea- or nitrate-containing granules.

[0045] Preferably, the urea-containing melt used in the process according to the invention contains ammonium sulfate, elemental sulfur, ammonium nitrate, trace elements, granulation additives, emulsifying additives, and / or mixtures thereof. Particularly preferably, the urea-containing melt contains 2 wt.% to 30 wt.% sulfur, and more preferably, 5 wt.% to 20 wt.% sulfur. For the purposes of the invention, the term "urea-containing fertilizer melt" also includes (within the limits of technical purity and with a water content of generally 2 wt.% to 10 wt.%) pure urea melts or urea solutions, or pure urea melts or urea solutions with a granulation additive such as formaldehyde, polyvinylamines, polyethylene vinyls (e.g., polyethyleneamine), polyethyleneimines, carboxylic acids, and / or aldehydes.

[0046] The invention further comprises the use of a fluidized bed granulator according to the invention as described above for the production of a urea-containing granulate, particularly preferably a urea-containing granulate containing elemental sulfur and / or ammonium sulfate.

[0047] The invention is described in more detail below with reference to the figures. The figures are not to scale and do not limit the invention to the embodiments shown therein.

[0048] They show: Figure 1 a schematic top view of a fluidized bed granulator according to the state of the art; Figure 2 a schematic top view of an exemplary fluidized bed granulator according to the invention; Figure 3 a further schematic top view of the fluidized bed granulator according to the invention; Figure 4 a further schematic top view of an alternative embodiment of the fluidized bed granulator according to the invention; Figure 5another preferred schematic top view of the fluidized bed granulator according to the invention; Figure 6 a schematically simplified side view of a fluidized bed granulator according to the state of the art; Figure 7 a corresponding schematically simplified side view of a fluidized bed granulator according to the invention.

[0049] Figure 1Figure 1 shows a schematic top view of a conventional fluidized bed granulator according to the prior art, comprising at least one granulator interior 1 with granulator interior walls 1a bounding this granulator interior. The granulator interior walls 1a comprise at least a first approximately vertical granulator side wall 1a.1, preferably inclined upwards slightly away from the center line of the fluidized bed granulator and bounding the granulator interior along a first longitudinal side; a second approximately vertical granulator side wall 1a.2, preferably inclined upwards slightly away from the center line of the fluidized bed granulator and bounding the granulator interior along its second longitudinal side; and a preferably approximately vertical granulator front wall 1a.3, which preferably extends transversely to the two granulator side walls and connects them, and a preferably approximately vertical granulator rear wall 1a.4, which extends at a distance from and preferably parallel to the granulator front wall and is thus opposite the granulator front wall. Thus, the fluidized bed granulator shown in the exemplary embodiment has a granulator interior that is preferably rectangular in plan view, although it could optionally also be square. For the sake of simplicity, the term "longitudinal side" is used in the present application, which corresponds to the extent of the fluidized bed granulator in the conveying direction of the granule particles in the granulator interior, which are in the . Figures 1 and 2as indicated by the arrow. The granulator front wall 1a.3, which is located on the side where the non-compliant granule particles enter the granulator interior, and the granulator rear wall 1a.4, which is located on the side where, in a conventional fluidized bed granulator, the granule particles exit the granulator interior, thus run transversely and perpendicular to the main conveying direction of the granule particles.

[0050] The granulator interior 1, in which the fluidized bed of granule particles is generated, is bounded at the bottom by a perforated plate 2, which is generally horizontal and, as shown, can extend, for example (but not necessarily), over the entire length and width of the granulator interior 1. Above this perforated plate 2, a fluidized bed of granule particles is thus generated in an approximately cuboid or trough-shaped volume. Several spray nozzles 5, usually spaced apart from one another, are mounted in, above, or on the perforated plate; these nozzles can, for example, be arranged in rows. The spray nozzles 5 are connected to atomization gas supply lines and melt supply lines (not shown).Furthermore, one or more seed inlet openings 3 are provided above the perforated plate 2, and one or more granule outlet openings 4 are provided in the perforated plate 2, the distance between the seed inlet opening 3 and the granule outlet opening 4 defining an (imaginary) granule flow direction (I) (see arrow). The perforated plate 2 is supplied from below with the fluidizing medium, for example, air (not shown). The seed inlet opening 3 allows smaller granule particles (smaller than the desired granule size) to be introduced as seed particles into the fluidized bed granulator. Viewed in the flow direction, the granulator interior also preferably includes one or more partition walls 7, which are spaced apart from each other and extend transversely across the granulator. The seed inlet openings 3 can be located on the front wall 1a.3 of the granulator and / or on the first side wall 1a.1 and / or the second granulator side wall 1a.2, viewed in the direction of granule flow, are each arranged between a first and a second partition wall 7.

[0051] The seed particles are exposed to molten droplets via the spray nozzles 5 and the supply lines (not shown) for the melt 6a and for atomizing air 6b. This exposure ("accretion") causes the seed particles to grow continuously. At the microscopic level, the particles preferably appear "raspberry-like" due to this growth from a core of molten, solidified (crystallized) droplets. The perforated plate 2 comprises growth zones (2a, 2ai, with i = 1, 2, 3, ...) and cooling zones (2b, 2bi, with i = 1, 2, 3, ...). In the growth zones (2a, 2a i , with i = 1, 2, 3, ...) spray nozzles 5 are arranged; in the cooling zones, spray nozzles are absent (2b, 2b i , with i = 1, 2, 3, ...) or, if applicable (not shown), there are fewer spray nozzles 5 than in the growth zones (2a, 2a i , with i = 1, 2, 3, ...). The alternation between growth zones (2a, 2a i , with i = 1, 2, 3, ...) and cooling zones (2b, 2b i , with i = 1, 2, 3, ...)This enables control of particle growth and temperature distribution. This is particularly useful for preventing the formation of biuret at high temperatures. Furthermore, partitions 7 are arranged between the growth zones 2a and cooling zones 2b in the direction of flow; preferably, the partitions include passage openings (not shown). These can be, for example, slots in the area of ​​the underside of the partitions 7, which are formed, for instance, by the partitions 7 terminating above the perforated plate 2, thus providing passage openings for the granule particles in the flow direction from one zone to the next.

[0052] Figure 2 Figure 1 shows a schematic top view of a fluidized bed granulator according to the invention. The basic structure corresponds to that described above. Figure 1The described structure of a conventional fluidized bed granulator and its previously described features will therefore not be repeated here. By comparing the two Figures 1 and 2 It can be seen that in the fluidized bed granulator according to the invention, the granule discharge opening is arranged at a distance in front of the granulator rear wall 1a.4. Thus, the shortest imaginary distance between the granule discharge opening 4 and the seed inlet opening 3 and the granulator front wall 1a.3 is shorter in the solution according to the invention than in the conventional fluidized bed granulator according to the invention, for the same size of the fluidized bed granulator. Figure 1 , since in the latter case the granule discharge opening 4 is located in the area of ​​the granulator rear wall 1a.4 and is therefore, as seen from the seed inlet opening 3, practically at the longitudinally opposite end of the fluidized bed granulator.

[0053] Furthermore, the granule outlet opening 4 is arranged within the perforated plate 2 and does not touch the granulator rear wall 1a.4. The granule particles discharged there then fall downwards through the granule outlet opening in the perforated plate 2, for example through a corresponding chute. Subsequently, the different granule particle sizes are separated from one another in a manner known per se using conveying devices and sieves, and granule particles that do not meet the required specification are returned to the seed inlet opening 3. These details are described in Figure 2 not shown.

[0054] In the embodiment according to the invention, the granule outlet opening 4 is surrounded, for example, in a U-shape, by several deflection plates 8, 8.1, 8.2, 8.3, wherein either no deflection plate 8 or (not shown) a deflection plate 8 with an opening is provided on the side opposite the granulator rear wall 1a.4. The deflection plates 8, 8.1, 8.2, 8.3 cause the granule particles in the fluid bed to flow around and then be deflected, first past the granule outlet opening 4 and then, with the flow direction reversed, within the deflection plates 8, 8.1, 8.2, 8.3 into the granule outlet opening 4. This reduces the distance between the granule discharge (granule outlet opening 4) and the return / seed inlet (seed inlet opening 3) of the fluid bed granulator by, for example, approximately 20–50%.The relocated granule outlet opening 4 reduces the height to be overcome by the conveying device and the building height of the granulation building accordingly, since the return of the non-compliant granule particles to the seed inlet opening 3 takes place in an area above the fluidized bed granulator, and the overall height of the necessary equipment is reduced in the solution according to the invention. This aspect will be explained later with reference to the schematic diagrams. Figures 6 and 7 explained in more detail.

[0055] Figure 3 Figure 1 shows another schematic top view of a fluidized bed granulator according to the invention. The basic structure corresponds to that shown in Figure 2. Figure 2The described structure is shown. A conveying device 9 is arranged on the first granulator side wall 1a.1. Alternatively, the conveying device 9 can be arranged on the second granulator side wall 1a.2. As a further alternative, a conveying device can be arranged on each of the two granulator side walls 1a.1 and 1a.2. The flow direction F of the granule particles is indicated by the arrows in the Figure 3 schematically indicated. In contrast to state-of-the-art fluidized bed granulators, this allows, as described above, a significantly more compact design, especially with regard to the building height of the granulation building.

[0056] Figure 4 Figure 1 shows another schematic top view of an alternative embodiment of the fluidized bed granulator according to the invention. The basic structure corresponds to that shown in Figure 2. Figure 3The described structure is used. However, the granule outlet opening 4 is located adjacent to the first granulator side wall 1a.1 and the conveying device 9 within the perforated plate 2. This arrangement reduces the transport distance to the conveying device 9. Alternatively, a conveying device and a granule outlet opening 4 can be located adjacent to the second granulator side wall 1a.2. Another alternative embodiment has two granule outlet openings, each with a conveying device, located adjacent to the first granulator side wall 1a.1 and the second granulator side wall 1a.2, respectively.

[0057] Figure 5Figure 1 shows another preferred schematic top view of the fluidized bed granulator according to the invention. On the perforated plate 2, schematically enlarged inclined openings 2c are indicated compared to their actual size. On the installed perforated plate, the openings are, for example, 1 mm to 3 mm in size. For the sake of clarity, only some inclined openings 2c are shown. The flow direction of the air G or the fluidizing medium is indicated by the black arrow. The arrangement of the inclined openings 2c assists in directing the flow direction F of the granule particles.

[0058] The following is described with reference to the schematic side views according to the Figures 6 and 7A significant advantage of the fluidized bed granulator design according to the invention is explained. In both illustrations, the granulator front wall 1a.3 and the granulator rear wall 1a.4 can be seen, between which the granule particles entering the granulator interior 1 at the seed inlet opening 3 are conveyed in the flow direction (longitudinal direction) towards the granule outlet opening 4. Because in the conventional device according to Figure 6 Since the granule outlet opening 4 is located at the end of the granulator interior 1, the granule particles must travel the entire distance through the granulator interior before reaching the granule outlet opening 4. Consequently, the schematically simplified conveying device 9 is located there, which must have a sufficient height to allow the non-compliant granule particles to be returned as seed to the seed inlet opening 3 via the sieves located above the fluidized bed granulator.

[0059] In contrast, in the solution according to the invention, the granule outlet opening 4 and thus also the conveying device 9 extending from it are located in a rather central area of ​​the granulator side wall, at a considerable distance from the granulator rear wall 1a.4, so that the distance over which the non-compliant granule particles must be guided back to the granulator front wall 1a.3 and the seed inlet openings 3 arranged there is considerably shorter and, accordingly, the height of the conveying device 9 and the granulation building can also be significantly reduced. Reference symbol list

[0060] 1 Granulator interior 1a Granulator interior walls 1a.1 First granulator side wall 1a.2 Second granulator side wall 1a.3 Granulator front wall 1a.4 Granulator rear wall 2 Perforated plate 2a i Growth zone 2b i Cooling zone 2c Inclined openings 3 Seed inlet opening(s) 4 Granule outlet opening(s) 5 Spray nozzles 6a Melt supply lines 6b Atomizing gas supply lines 7 Partitions 8 i Deflection device / deflection plates 9 Conveyor device F Flow direction of granule particles G Flow direction of air or fluidizing medium

Claims

1. Fluidized bed granulator for production of urea-containing or nitrate-containing granulates, comprising at least: - a granulator interior (1) having granulator interior walls (1a), at least comprising a first granulator side wall (1a.1), a second granulator side wall (1a.2), a granulator front wall (1a.3) extending transversely to the granulator side walls, and a granulator back wall (1a.4) also extending transversely at an opposite end of the granulator interior (1) from the granulator front wall; - a horizontally arranged perforated plate (2) delimiting the granulator interior (1) toward the bottom; - at least one seed entry opening (3) and at least one granulate exit opening (4); characterized in that - at least one granulate exit opening (4) is arranged at a distance in front of the granulator back wall (1a.4), wherein at least one deflection device (8, 8.1, 8.2, 8.3) is provided in the granulator interior (1), which causes a deflection of the flow of the granulate particles in the granulator interior (1) in such a way that the granulate particles are deflected at least once in a direction deviating from their initial flow direction towards the granulate exit opening (4), and the deflection device comprises at least two deflection plates (8, 8.1, 8.1+i with i = 0, 1, 2, 3, ...), of which a first deflection plate extends, if necessary at a distance, next to the granulate exit opening (4) generally in the flow direction of the granulate particles, and a second deflection plate extends in front of the granulate exit opening (4) approximately transversely to the flow direction of the granulate particles.

2. Fluidized bed granulator according to claim 1, characterized in that at least one granulate exit opening (4) is arranged within the perforated plate (2).

3. Fluidized bed granulator according to claim 1 or 2, characterized in that the at least one deflection device (8, 8.1, 8.2, 8.3) causes a multiple deflection of the flow of the granulate particles in the granulator interior (1) that is different from their initial flow direction toward the granulate exit opening (4).

4. Fluidized bed granulator according to one of claims 1 to 3, characterized in that the at least one deflection device (8, 8.1, 8.2, 8.3) causes a deflection of the flow of the granulate particles in the granulator interior (1) by a total of approximately 180° deviating from their initial flow direction towards the granulate exit opening (4).

5. Fluidized bed granulator according to one of claims 1 to 4, characterized in that at least one deflection plate (8, 8.1, 8.1+i with i = 0, 1, 2, 3, ...) of the deflection device extends generally in the flow direction of the granulate particles or at an acute angle to the flow direction of the granulate particles and is arranged at a distance from the granulator side walls (1a.1, 1a.2).

6. Fluidized bed granulator according to one of claims 1 to 5, characterized in that at least two deflection plates (8, 8.1, 8.1+i with i = 0, 1, 2, 3, ...) of the deflection device form an acute angle or a right angle with each other or are arranged parallel to each other.

7. Fluidized bed granulator according to one of claims 1 to 6, characterized in that the granulator interior (1) above the perforated plate (2) is divided, preferably by partition walls (7) extending in the transverse direction, into growth zones (2a) and cooling zones (2b) as viewed in the flow direction.

8. Fluidized bed granulator according to one of claims 1 to 7, characterized in that a second seed entry opening is arranged in the granulator front wall (1a.3) and / or additional seed entry openings are arranged in the first side wall (1a.1) and / or the second side wall (1a.2) of the granulator.

9. Fluidized bed granulator according to claim 8, characterized in that the further additional seed entry openings according to claim 8 are arranged in connection with a growth zone (2a2, 2a3, etc.).

10. Fluidized bed granulator according to one of the preceding claims, characterized in that the granulate exit opening (4) is arranged within the perforated plate (2) and does not touch the granulator back wall (1a.4).

11. Fluidized bed granulator according to one of the preceding claims, characterized in that the deflection plates (8.1, 8.1+i with i = 0, 1, 2, 3, ...) are arranged in a U-shape or such that they ensheath the granulate exit opening (4).

12. Fluidized bed granulator according to one of claims 7 to 11, characterized in that the partition walls (7) arranged between the growth zones (2a) and cooling zones (2b) have passage openings.

13. Fluidized bed granulator according to claim 5, characterized in that at least one deflection plate (8) is designed as portion of a partition wall (7).

14. Fluidized bed granulator according to one of the preceding claims, characterized in that the granulate exit opening (4) is arranged within a cooling zone (2bi).

15. Fluidized bed granulator according to one of the preceding claims, characterized in that the perforated plates have inclined openings (2c), wherein the inclined openings (2c) preferably form an angle of 20° to 60° to the surface of the perforated plate (2).

16. Fluidized bed granulator according to claim 15, characterized in that the inclined openings (2c) are inclined in different directions, preferably along a flow direction of the granulate particles, particularly preferably along the flow direction of the granulate particles around the deflection plates (8) in the direction of the granulate exit opening (4).

17. Fluidized bed granulator according to one of the preceding claims, characterized in that one or both of the granulator side walls (1a.1 and 1a.2) are arranged vertically.

18. Fluidized bed granulator according to one of the preceding claims, characterized in that one or both of the granulator side walls (1a.1 and 1a.2), as viewed in a vertical direction, are arranged in an inclined manner from the center line of the fluidized bed granulator outward.

19. Granulation plant with a fluidized bed granulator according to one of the preceding claims, characterized in that the granulate exit opening (4) is connected to a conveying device (9), preferably via a coarse screen.

20. Granulation plant according to claim 19, characterized in that the conveying device (9) is connected to a downstream screening device (10).

21. Granulation plant according to one of claims 19 or 20, characterized in that the conveying device (9) is arranged in the flow direction of the granulate particles at a distance of 20% to 80% of the total length of the first granulator side wall (1a.1) or the second granulator side wall (1a.2), preferably with respect to the outer edge of the first granulator side wall (1a.1) or the second granulator side wall (1a.2).

22. Granulation plant according to one of claims 19 to 21, characterized in that the granulate exit opening (4) is connected first to a coarse screen followed by a separate fluidized bed cooler or is connected to no separate fluidized bed cooler.

23. Process for production of a urea-containing or nitrate-containing granulate, comprising at least the following steps: - providing a urea-containing and / or nitrate-containing melt; - spraying the urea-containing and / or nitrate-containing melt into a fluidized bed granulator according to one of claims 1 to 18; and - granulating the urea-containing or nitrate-containing melt and obtaining a urea-containing and / or nitrate-containing granulate.

24. Process according to claim 23, characterized in that the urea-containing and / or nitrate-containing melt contains one or more substances selected from the group comprising ammonium sulfate, elemental sulfur, ammonium nitrate, trace elements, granulation additives, emulsification additives, and / or mixtures thereof.

25. Use of a fluidized bed granulator according to one of claims 1 to 18 for production of a urea-containing and / or nitrate-containing granulate, preferably a urea-containing granulate containing elemental sulfur and / or ammonium sulfate.