EA040458B1 - DEVICE FOR GRANULATION OF UREA - Google Patents

Description

The technical field to which the invention belongs

The invention relates to a fluid bed granulator. In particular, the granulator is suitable for granulating urea or urea-containing liquids such as urea melt. The granulator is, for example, suitable for forming urea granules or carbamide-containing granules. Urea granules (which may include additives such as ammonium salts) are mainly used as a fertilizer and can, for example, also be used in cattle feed and to reduce NO _x emissions.

State of the art

The invention relates to a fluid bed granulator. During operation of such a granulator, a stable fluid bed of particles is formed in one or more granulation compartments by supplying a fluidization gas, often air, through the fluidization plate. This plate is located at the bottom of said compartments and has a plurality of openings for fluidizing gas. During operation of the apparatus, a granulating liquid (eg, a urea melt, eg, containing more than 90 or more than 95 wt.% urea, eg, containing less than 5 wt.% water) is fed into the fluidized bed through nozzles in the fluidizing plate. The nozzles also supply a secondary gas, often air, the gas being used in the nozzles, for example, to atomize the granulation liquid as a spray jet or to drive particles through a film of the granulation liquid, the film being formed by the nozzle. In each compartment of the granulator, the nozzles are generally arranged in ordered rows in the fluidization plate. During operation, the fluidization gas passes through the holes in the fluidization plate and thereby fluidizes the particles in the granulation compartments and removes the heat of crystallization. Thus, there are three supply systems below the fluidization plate: a fluidization gas supply system, a granulating liquid (eg, carbamide smelt) supply system, and a secondary gas supply system.

In the present invention, the fluidization gas and the secondary gas are supplied separately, for example at different temperatures, different flow rates and/or different pressures, and they are both, for example, air. In a preferred embodiment, the temperature of the fluidization gas is up to 50°C (the minimum temperature is, for example, ambient temperature), and the temperature of the secondary gas is, for example, at least 60°C or at least 100°C and, for example , up to 150°С. In the invention, the preferred high temperature of the secondary gas, preferably secondary air, can be advantageously used to prevent solidification of the urea melt as the preferred granulation liquid in the parts of the granulation liquid supply manifold of the granulator according to the invention which are located within the secondary gas space.

EP 2055373 (also published as US 2012/0282361) describes a granulator comprising a granulation module having a bottom floor with a perforated plate at its bottom, an upper air supply pipe for supplying air to the bottom floor, and spray nozzles for spraying the granulating liquid. Nozzles are located at the center of the air outlets in the air supply pipes, each branching off from a lower air supply pipe and each having an opening in the lower ceiling to force air into the granulation module. In FIG. 1 of document EP 2055373 schematically shows a granulator with spray nozzles connected to a horizontal granulating liquid supply line which runs intensively through an upper air supply pipe to supply air for fluidization. In EP 2055373 the fluidization air is at 44°C and therefore relatively cold (Table 2), so there is a risk in the receiver according to EP 2055373 of the granulation liquid cooling and solidifying, or alternatively the granulating liquid on the inlet of the granulator according to EP 2055373 must be very warm.

The STAMI UREA LAUNCH FINISH Granulation Design document states that Stamicarbon's urea granulation technology uses a fluid bed granulator in which the urea melt is fed through a plurality of spray nozzles to form a film. A continuous flow of secondary air enters through the air supply annulus provided around each spray nozzle and is responsible for leading the seed/pellets through the urea melt film. The fluid bed granulator is divided into a plurality of granulation sections in which the carbamide melt is fed through nozzles and a series of cooling sections in which the formed granules are cooled. The fluidization air is distributed to the granulation and cooling sections to hold the fluidized bed and remove the generated heat of crystallization.

Coming of age, Nitrogen & Methanol, No. 272, Nov-Dec 2004, pp. 37-43, XP001212587, mentions that Stamicarbon's granulator for the fluidized bed urea granulation process includes a series of receiving manifolds located along the granulator. These receivers are located under the fluidization plate and each contains

- 1 040458 an air receiver pipe with a melt receiver pipe located coaxially inside the air receiver pipe.

The purpose of the present invention is to provide an improved fluid bed granulator.

The essence of the invention

In a first aspect, the invention relates to a fluid bed granulator for granulating urea or urea-containing liquids, the granulator comprising a granulator chamber, the granulator chamber comprising: bottom wall, top wall, fluidization gas inlet, secondary gas inlet, outlet for product solids, an exhaust gas outlet, and optionally an inlet for seed particles, wherein the granulator chamber comprises a plurality of granulation compartments that are arranged in series along the length of the granulator, the granulator further comprising a granulating liquid inlet and a granulating fluid supply manifold liquid, wherein the granulating liquid supply manifold comprises a granulating liquid receiver and a plurality of risers, wherein the granulating liquid receiver is connected to said granulating liquid inlet and to a plurality of risers. said risers, wherein the granulator chamber further comprises a fluidization plate and at least a separating plate in said granulation compartments, wherein the separating plate is spaced from the fluidizing plate in the vertical direction and placed below the fluidizing plate, with the separating plate located between said bottom wall and said fluidization plate, wherein said granulator chamber comprises a first space between said top wall and said fluidization plate, a second space between said fluidization plate and said separating plate, and a third space between said separating plate and said bottom wall, wherein each of said first, second and third spaces has a chamber, wherein said granulator is configured to retain a fluidized bed of particles during operation in said first p space, and wherein said first space chamber comprises said product solids outlet, said exhaust gas outlet, and optionally said seed particle inlet, wherein said second space chamber comprises said fluidizing gas inlet, and wherein the fluidization plate comprises openings for passage of said fluidizing gas from said second space to said first space, wherein said chamber of said third space contains said secondary gas inlet, wherein the granulator comprises a plurality of nozzles in said granulator compartments for feeding said granulating liquid into said first space, wherein at least one of said nozzles comprises a nozzle inlet for said secondary gas and a nozzle inlet for said granulating liquid wherein said granulator comprises a secondary gas channel that extends from the secondary gas hole in said separation plate through said second space to said secondary gas injector inlet, said granulating liquid supply manifold being partly located in said third space and partly in said second space, wherein at least one of said risers is at least partially located within said secondary gas conduit, said riser extending through said secondary gas opening or connected to said receptacle at said secondary gas opening .

The invention also relates to a method for granulating carbamide carried out in such a granulator, the method comprising supplying a melt of urea in the form of granulating liquid to an inlet for granulating liquid and through a granulating liquid supply manifold, including a receiver and risers, supplying fluidization gas to a fluidizing gas inlet, and supplying secondary gas to a secondary gas inlet in a granulator, and withdrawing granulate through a granulate outlet, and holding a fluidized bed of granules in the first space, and supplying granulating liquid to the first space with a nozzle.

Brief description of the drawings

In FIG. 1 schematically shows an example of a granulator according to the invention.

In FIG. 2 is a schematic representation of an example of a granulator according to the invention; and in FIG. 2A is an overview view, and FIG. 2B is an enlarged fragment in cross section.

In FIG. 3 is a schematic representation of an example of a granulator according to the invention.

In FIG. 4 is a schematic representation of an example of a granulator according to some embodiments of the invention.

In FIG. 5 is a schematic representation of an example of a granulator according to the invention.

In FIG. 6 schematically shows granulators; and in FIG. 6A shows a granulator according to the invention, and FIG. 6B and 6C are cross-sectional views.

- 2 040458

In FIG. 7 is a schematic representation of a prototype granulator not in accordance with the invention.

In FIG. 8 is an isometric view of an example of a granulator according to the invention.

Detailed description

The granulator of the invention has a specific configuration of the spaces used for supplying the fluidization gas and for supplying the secondary gas to the granulator, and has a specific configuration of the granulating liquid supply manifold. Such a configuration makes it possible, for example, to facilitate cleaning of the granulator. Additional advantages of the invention are discussed below in the detailed description.

One difference of the granulator according to the invention is that it comprises a granulation liquid feed manifold which is partly located in a third space with a secondary gas inlet. This provides the advantage that a relatively large volume of relatively hot secondary gas in the third space heats the granulating liquid in said portion of the granulating liquid supply manifold.

In a preferred embodiment, the granulating liquid receiver is located in the third space, and an inlet for the granulating liquid is provided in the chamber of the third space. In this preferred embodiment, the receiver, in particular, is located entirely within the third space. The advantage is that the granulation liquid in the receiver comes into indirect heat exchange contact with the relatively hot secondary gas in the third space, whereby heat losses are reduced.

An example of a fluid bed granulator (1) is shown in FIG. 1, 2, and 3. In the following general description, reference numerals to elements shown in the drawings are for convenience only; these reference positions do not limit the invention or the claims.

The invention relates to a fluid bed granulator (1) for granulating urea or urea-containing liquids. The granulator contains a chamber (2) of the granulator. The chamber (2) of the granulator contains a bottom wall (3), an upper wall (4), an inlet (5) for gas for fluidization, an inlet (6) for secondary gas, an outlet (7) for solid particles of the product, an outlet ( 8) for exhaust gas and optionally an inlet (9) for seed particles. The chamber (2) of the granulator contains a plurality of compartments (A, B) for granulation, which are arranged in series along the length of the granulator. The granulator (1) further comprises an inlet (10) for granulating liquid and a collector (11) for supplying granulating liquid. The granulating liquid supply manifold (11) contains a granulating liquid receiver (12) and a plurality of risers (13). The receiver (12) of the granulating liquid is connected to the inlet (10) for the granulating liquid and to a plurality of said risers (13). The chamber (2) of the granulator additionally contains a plate (14) for fluidization and a separating plate (15) in at least the indicated compartments (A, B) for granulation. The separation plate (15) is at some distance from the fluidization plate (14) in the vertical direction and is placed below the fluidization plate (14). The separating plate (15) is located between said bottom wall (3) and said fluidization plate (14).

The chamber (2) of the granulator additionally contains the first space (21) between the specified top wall (4) and the specified plate 14 for fluidization, the second space (22) between the specified plate (14) for fluidization and the specified separation plate (15) and the third space ( 23) between said separation plate (15) and said bottom wall (3). Each of said first, second and third spaces has a camera. The granulator is configured to hold the fluidized layer of particles during operation in the specified first space (21). The chamber of said first space (21) contains said outlet (7) for solid product particles, said outlet (8) for exhaust gas, and optionally said inlet (9) for seed particles. The chamber of the specified second space (22) contains the specified inlet (5) for gas for fluidization. Plate (14) for fluidization contains holes (16) for the passage of the specified gas for fluidization from the specified second space (22) to the specified first space (21). The chamber of said third space (23) contains said inlet (6) for secondary gas.

The granulator additionally contains in said compartments (A, B) of the granulator a plurality of nozzles (17) for supplying said granulating liquid into said first space (21). At least one of said nozzles (17) comprises a nozzle inlet (18) for said secondary gas and a nozzle inlet (19) for said granulating liquid. The granulator contains a channel (20) for secondary gas, which passes from the hole (25) for secondary gas in the specified separation plate (15) through the specified second space (22) to the specified inlet (18) of the nozzle for secondary gas. The granulating liquid supply manifold (11) is partly provided in said third space (23) and partly in said second space (22). At least one of said risers (13) is at least partially provided within said channel (20) for secondary gas. Said riser (13) passes through said hole (25) for secondary gas or is connected to said receiver (12) at said hole (25) for secondary gas.

- 3 040458

In particular, the granulator is suitable for granulating urea or urea-containing liquids.

The chamber (2) of the granulator is often box-shaped and may also be, for example, oval when viewed from above. The chamber is typically rectangular in shape, eg has a horizontal length greater than (eg, at least 2 times) its width in the perpendicular horizontal direction. The chamber (2) of the granulator contains a bottom wall (3), an upper wall (4) and side walls. The bottom wall is, for example, a metal plate or a concrete floor. Chamber (2) of the granulator contains the first space (21). The chamber of the granulator contains a plurality of compartments (A, B) for granulation. Compartments for granulation are arranged sequentially in the direction of the length of the granulator and, as a rule, provided in the specified first space (21).

The chamber (2) of the granulator, in particular the first space (21), further preferably comprises at least one cooling compartment (C) located downstream of said granulation compartments. The compartments are separated from each other by a divider, such as a baffle (26), wherein the divider is, for example, a plate attached to the side wall, and the first space, for example, includes holes located between the dividers and the plate (14) for fluidization and between the separators and the top wall, to ensure the movement of particles. The use of a plurality of compartments arranged in series, separated by such separators, provides a more controlled residence time of the particles in the granulator. In operation, particles in the fluidized bed move from the upstream compartment to the downstream compartments and substantially to the granulate outlet (7) through which the formed particles are discharged. Too small granules are optionally reused, for example, as seeds; too large granules in the granulate material are optionally crushed (generally outside the granulator) and the crushed granules, for example, are reused. In some embodiments, too small granules and/or (crushed) too large granules are not reused.

The granulator (1) further comprises an inlet (10) for granulating liquid and a collector (11) for supplying granulating liquid. In a urea plant, the inlet is for example a urea melt containing, for example, at least 90 wt.%, or at least 95 wt.%, or at least 98 wt.% urea; and typically containing a granulating additive such as formaldehyde. The melt may also contain biuret. The granulating liquid may, for example, also contain a mixture of urea, optionally biuret and an additive, or essentially consist of it (for example, at least 90 wt.%), and the additive is, for example, an ammonium salt. The granulating liquid typically contains less than 5 wt% or less than 2 wt% water.

The granulation process carried out in the granulator, for example, is based on the evaporation of water and/or cooling of the granulation liquid to allow the granulation liquid to solidify and the particles to grow. For example, cooling is provided by fluidization gas and/or secondary gas. In an exemplary embodiment of the granulation process, the granulating liquid, preferably a urea melt, solidifies in the granulator, and in particular on the granules. In embodiments where the nozzles are film-forming spray nozzles, the granulation may include layer-by-layer growth of the granules.

The granulation liquid inlet is, for example, connected to the (section outlet) evaporation section of the urea plant, for example, to a vacuum evaporation stage or stages.

The granulator, in particular the space for granulation, contains an outlet (8) for exhaust gas (usually in the upper wall or near the top and/or, as a rule, at the end located downstream in the direction along the length), the outlet (7) for product solids and optionally an inlet (9) for seed particles. The granulate outlet (7) and the optional seed inlet (9) are usually located at opposite ends of the granulator chamber (2), with the ends opposite each other in the length direction of the granulator. An outlet (7) for the granulate is provided, for example, in said compartment (C) for cooling.

Chamber (2) of the granulator additionally contains an inlet (5) for fluidization gas and a separate inlet (6) for secondary gas. Thus, the fluidization gas (eg, air) and secondary gas (eg, air) may have different temperatures, flow rates, compositions, and/or pressures during operation.

Chamber (2) of the granulator additionally contains a plate (14) for fluidization. The fluidization plate forms the bottom of the compartments (A, B) for granulation and optional compartment (C) for cooling. The fluidization plate (14) has openings (16) for passing the fluidization gas into the first space (21), in particular into the granulation compartments (A, B) and the optional cooling compartment (C). Thus, the granulator is configured to

- 4 040458 retention fluidized bed of particles during operation in the specified first space (21). The chamber of the first space (21) contains an outlet (7) for product solids (i.e. granules), an outlet (8) for off-gas (for off-gas corresponding to fluidization gas and secondary gas) and optionally an inlet ( 9) for seed particles, herein the first space chamber is, for example, provided with side walls and/or top walls of granulation compartments (A, B) and optional cooling compartment (C) and fluidization plate (14). The first space (21) is located between the upper wall (4) and the fluidization plate (14), respectively. The fluidization plate (14) is, for example, arranged as a horizontal plate and optionally slightly inclined (eg up to 10° or up to 2°), in particular in the lengthwise direction.

The separating plate (15) is often arranged as a horizontal plate, but may also be slightly inclined (for example up to 10° or up to 2°), in particular in the lengthwise direction, for example so that the highest part of the plate is closer to outlet (8) for gas than the lowest part of the plate. This can be used to facilitate cleaning of, for example, insoluble biuret, which can be flushed to the underside of the plate and easily removed. The fluidization plate (14) and the separating plate (15) are often arranged as parallel plates, but they can also be slightly inclined to each other, for example at an angle of up to 10° or up to 5°. If the separation plate is tilted, it is preferable to also tilt the fluidizing plate so that it is parallel to the inclined separation plate in order to optimize the gas flow.

The granulator contains in the compartments (A, B) of the granulator a plurality of nozzles (17) for supplying the granulating liquid into the first space (21). The nozzles are, for example, film forming spray nozzles or spray nozzles, but other types of nozzles can also be used in the granulator of the invention. In some embodiments, the granulator compartments contain a plurality of drain channels for supplying granulating liquid into the first space, for example, through nozzles (17). Preferably, the nozzles pass through an opening in the fluidization plate. Preferably, each nozzle has a granulation liquid nozzle outlet that protrudes from the fluidization plate into the first space. The nozzles are typically provided at specific intervals in the lengthwise direction, these intervals being determined by the layering mechanism. In some embodiments, the nozzles are mounted on a fluidization plate within the first space. However, each nozzle preferably passes through an opening in the fluidizing plate, and the size of each nozzle, for example, does not exceed the width of the opening at least at the atomizing end of the nozzle. Advantageously, in some embodiments, the fluidization plate can be easily removed (eg, for cleaning) by moving the plate upwards, and the nozzles do not block such movement. The fluidization plate has, for example, one hole for each nozzle.

At least one nozzle (17), preferably a plurality of nozzles (for example, more than 10 or more than 30 nozzles), or even all nozzles, contains a secondary gas inlet (18) and additionally contains a separate nozzle inlet (19) for granulating liquid. The inlet (18) of the secondary gas nozzle is connected to the inlet of the chamber (6) of the secondary gas granulator. The inlet (19) of the granulating liquid nozzle is connected to the inlet (10) for the granulating liquid of the granulator through the granulating liquid supply manifold (11).

In the fluidized bed granulator of the invention, the granulating liquid supply manifold (11) comprises a granulating liquid receiver (12) and a plurality of risers (13), wherein the granulating liquid receiver (12) is connected to the granulator granulating liquid inlet (10) and a plurality of risers ( 13).

In addition, the chamber (2) of the granulator contains a dividing plate (15) in at least the specified compartments (A, B) for granulation. The separation plate (15) is at some distance from the fluidization plate (14) in the vertical direction and is placed below the fluidization plate (14) in the granulator chamber. Thus, the separation plate (15) is located between the bottom wall (3) and the fluidization plate (14). In some embodiments, the implementation of the separation plate (15) is not in the compartment (C) for cooling (see, for example, Fig. 3).

The granulator chamber (2) in addition to the first space (21) respectively contains a second space (22) between the fluidization plate (14) and the separating plate (15) and a third space (23) between the separating plate (15) and the bottom wall (3 ). Each of the first, second and third spaces has a chamber (formed by said pair of plates and/or wall and side walls of the granulator).

The chamber of the second space (22) contains an inlet (5) for fluidization gas, for example, in the side wall, and if the granulator is box-shaped, for example, in the long side

- 5 040458 wall parallel to the direction along the length. The third space chamber (23) contains a secondary gas inlet (6) in, for example, a side wall, and if the granulator is box-shaped, for example, in a long side wall parallel to the length direction, as shown in FIG. 8 showing the side walls (27).

The granulator contains a channel (20) for secondary gas, which passes from the hole (25) for secondary gas in the separation plate (15) through the second space (22) to the inlet (18) of the nozzle for secondary gas. Thus, during operation, the secondary gas enters the granulator chamber to the inlet (6), passes through the third space (23), through the hole (25) for the secondary gas and through the channel (20) for the secondary gas connected to the specified hole ( 25) and enters the inlet (18) of the injector (17). The secondary gas conduit (20) is preferably arranged as a straight vertical pipe connecting the secondary gas port (25) and the injector inlet (18), which are located on the same vertical line, such as a straight line at an angle from 85 to 95° or at an angle of 90°, perpendicular to the horizontal plane or at such an angle to the separation plate (15), i.e. at an angle to the vertical in this range for at least one direction in the horizontal plane.

In addition, during operation, the fluidizing gas enters the granulator chamber at the fluidizing gas inlet (5), passes through the second space (22), and then through one of the plurality of holes (16) in the fluidizing plate into the first space ( 21).

In the granulator of the invention, the granulating liquid supply manifold (11) is partly provided in the third space (23), i.e. under the separating plate (15). This first part contains the inlet (10) for granulating liquid or receives the granulating liquid from the inlet (10) for granulating liquid and is located in particular in front of risers (13) (for granulating liquid). The other second part of the granulating liquid supply manifold (11) is provided with risers (13), the risers (13) being at least partially provided in the second space (22).

In order to cover the vertical distance between the part of the manifold (11) for supplying granulating liquid under the dividing plate (15) and the inlet (19) of the nozzle, inside the channel (20) for the secondary gas, at least partially, at least one of these risers is provided (13) (for granulating liquid). The riser (13) passes through the secondary gas hole (25) of the secondary gas channel (20), in a less preferred embodiment, the riser is connected to the receiver (12) at this hole (25) for the secondary gas. The riser (13) is located at one end (upper end) connected to the inlet (19) of the nozzle. The hole (25) for the secondary gas is preferably the lower hole of the channel (20) for the secondary gas, or the channel (20) is, for example, a pipe passing through the hole (25) and having a lower end in the third space (23) and under separating plate (15).

Thus, the granulating liquid enters the granulating liquid inlet (10) into the granulating liquid supply manifold (11), flows through the receiver (12), and moves up the riser (13) to the injector inlet (19). The riser (13) is, for example, a pipe, and during operation, the granulating liquid is inside it, and the secondary gas is outside, since the riser is at least partially provided inside the channel (20) for the secondary gas. For example, riser (13) and conduit (20) for secondary gas are concentric pipes. The riser pipes are preferably at least as long as the secondary gas pipes, and in some embodiments they are even longer.

The riser pipes preferably span at least the vertical distance between the separation plate and the fluidization plate. Each riser pipe is preferably connected to only one nozzle. The granulating liquid supply manifold preferably comprises a series of splitters (e.g. pipe connections) for splitting the granulating liquid into separate nozzle streams and/or for separating a first granulating liquid stream entering only one nozzle from a second granulating liquid stream entering a plurality of nozzles. nozzles. An example of such a splitter is a connection between a receiver and a separate riser, for example as shown in FIG. 1. At least some of these splitters, preferably each of these splitters, are located below the separation plate. The pipes or conduits for the granulating liquid located in the second space preferably consist of pipes or conduits for the flows of the granulating liquid entering only one nozzle. In some embodiments, these connections or splitters for the granulation liquid streams entering the individual nozzles are located directly below the granulation liquid inlet in a particular nozzle, i. below the inlet of the nozzle, and the corresponding splitters (eg pipe connections) differ from each other only in the position in the vertical direction and not in the direction of length and/or width.

The configuration of the granulation liquid supply manifold and the second and third spaces advantageously provides a simpler design than known granulation liquid receivers of granulators. In addition, in some embodiments, the pellet supply manifold

- 6 040458 rubbing liquid can be advantageously completely provided in the granulator chamber or granulator housing. This provides a simpler design and less weight of the granulator. The number of wall protrusions (inlets, outlets and pipes) can be reduced and thereby reduce the weakening of the walls of the granulator and eliminate or at least reduce the need for structures that increase the strength of the walls.

The configuration has a particular advantage in cleaning the granulator. To clean the granulator, the first large pieces (solid particles) are usually removed from the first space (21). Thereafter, the first space (21) is further cleaned with water (or other solvent) to dissolve any remaining solids (eg urea). As a result, contaminated water and particles of urea (or other solid particles) enter the second space (22) through holes (16) in the fluidization plate (14). In the configuration of the present invention, the second space (22) is much larger and/or much easier to clean than, for example, the prior art granulators mentioned above herein. In particular, risers (13) are easily provided within the secondary gas conduit (20). Thus, in some embodiments, the second space (22) preferably does not contain any equipment components, except for the channels (20) for the secondary gas, since these equipment components (if any) could interfere with the cleaning of the lower part of the second space (i.e., the separating plate (15)) or block access to it. In contrast, in prior art urea granulators, a urea receptacle is often provided in the fluidization gas space, as well as typically a secondary gas supply receptacle; these receivers interfere with cleaning.

An additional advantage is that, since the granulation liquid supply manifold is at least partially provided in the space containing the secondary gas during operation (third space), the secondary gas being hot, in order to maintain the temperature of the granulation liquid above the curing temperature before nozzles require a less thick layer of thermal insulation; its thickness can be even smaller, since during operation the risers are screened with hot secondary gas.

In addition, the smaller branching of the supply manifold provides greater convenience when wrapping the thermal insulation around the manifold, and in particular the risers. In particular, in some attractive embodiments, the urea supply manifold is completely integrated into the secondary gas space. The advantage is that the urea melt remains molten at a higher temperature throughout its journey to the nozzles.

Advantageously, the granulation configuration of the invention provides a total pressure drop in the system upstream of the granulating liquid and/or secondary gas nozzles that is significantly less than the pressure drop in the spray nozzles, for example provides a total pressure drop in the channels for granulating liquid and/or secondary gas , which is less than at least 90% or even at least 95%. This localization of the pressure drop, mainly in the nozzles, advantageously contributes to a more uniform distribution of the supplied secondary gas (eg air) and/or granulating liquid, for example urea-containing melt.

The configuration of the present invention allows for easy cleaning, for example by hand, after removing the fluidization plate. The configuration also allows the use of a (semi)automatic cleaning system, for example by spraying a cleaning liquid such as water into the second space. It is expected that no urea deposits will form inside the secondary gas passage since the passage is not connected to the second space, but flushing of the passages is possible if necessary.

In the present invention, the fluidization gas and the secondary gas are supplied separately, for example at different temperatures, different flow rates and/or different pressures, and they are both, for example, air. In some embodiments, the fluidization gas has a temperature below 70°C, eg 5 to 50°C, and the secondary gas has a temperature, eg above 100°C, eg 140 to 150°C. The secondary gas, for example, has a temperature of at least 20° C. or at least 50° C. higher than the fluidization gas temperature. This provides the advantage of preventing solidification of the granulating liquid, such as carbamide fusion, flowing in the granulating liquid supply manifold (11), in particular in the risers (13).

In a preferred embodiment, the secondary gas conduit is the first pipe, and the riser or portion of the riser provided in the secondary gas conduit is the second pipe, the first pipe surrounding the second pipe in the cross section of the pipes in a horizontal plane at at least one position vertically, and preferably in all vertical positions of the riser or part of the riser which is provided in the secondary gas duct. The pipes may have any cross-sectional shape in the horizontal plane, such as circular, polygonal (particularly the shape of simple polygons such as square, pentagon and hexagon) or other shapes.

In an exemplary embodiment, the secondary gas conduit and the riser (or the portion of the riser that is provided in the secondary gas conduit) are provided as concentric pipes. Cross sections to the horizon

- 7 040458 tal plane of the first and second pipes do not necessarily have the same center in at least one vertical position. The secondary gas conduit is preferably an outer pipe and the riser (or part of the riser) is an inner pipe whose diameter is smaller than that of the outer pipe. The outer tube preferably completely surrounds the inner tube in a cross section in a horizontal plane for at least part of the length of one of the tubes. An example of such pipes is shown in Fig. 1.

In a preferred embodiment, the granulator contains at least one divider (26) dividing the first space into zones so that these zones form compartments (A, B) for granulation. The second space is divided or not divided between granulation compartments, preferably the second space is divided into compartments by dividing walls so that each compartment has a fluidization gas inlet. The third space (for secondary gas) is divided or not divided between said granulation compartments. Preferably, the third space is divided into compartments by partition walls so that each compartment has a fluidization gas inlet. An optional fourth space (for granulation liquid) is divided or not divided between said compartments. Preferably, the optional fourth space is divided into compartments by dividing walls such that each compartment contains one or more granulating liquid inlets. Said dividing walls preferably correspond to the dividers of the first space, so that the granulation compartment has a corresponding compartment of the second space, and the third space, and optionally also the fourth space.

In FIG. 1 is a schematic side view of an example of a granulator according to the invention. In the figures, L indicates length, H indicates height, and W indicates width. In FIG. 1 the nozzles (17) are shown only in the compartment (A) of the granulator, and as a rule they are also provided in the compartment (B). Two nozzles (17A, 17B) are located at some distance from each other in the direction along the length. Each injector actually corresponds to a plurality of injectors. In preferred embodiments, the nozzles are arranged in rows across the width of the granulator, with the rows spaced apart in the lengthwise direction. The manifold (12) extends in the lengthwise direction in the third space (23) (as shown) and, for example, includes branches in the transverse direction for each row of nozzles, the branches having elevations for each individual nozzle. In alternative embodiments of the present invention, the nozzles are arranged in a plurality of rows in the length direction, with the rows spaced apart in the width direction, and the receptacle comprises a plurality of branches, with each branch extending in the length direction and connected to the nozzles of one such a row with the help of risers, while the branches themselves are located at some distance from each other in the direction along the width. In yet other embodiments, the chamber of the third space (23) is provided with a plurality of holes (10) for granulating liquid spaced from each other in the direction along the length, and the receiver contains a plurality of branches extending in the direction along the width.

In FIG. 1 shows an example of a preferred embodiment, wherein the receiver (12) is vertically spaced from the separation plate (15) and the riser (13) passes through the secondary gas opening (25) into the third space (23). The advantage is that the relatively hot secondary gas (6) surrounds the entire receiver (12) in such a way that cooling of the granulating liquid (eg urea melt) in the receiver is prevented. As shown in FIG. 1, the receptacle (12) is also preferably spaced vertically from the separation plate (15). In addition, the wall of the riser (13) is at some distance from the wall of the channels (20) for the secondary gas. Thus, the secondary gas (6) located in the secondary gas channels (20) and preferably completely surrounding the risers (13) can advantageously reduce the cooling of the granulation liquid in the riser. Since a plurality of risers (13) are used, the walls of the risers through which heat exchange is carried out have a large area relative to the receiver (12).

This design of the receiver (12) has the advantage of preventing the granulating liquid in the barrel (as well as the receiver and risers) from being cooled by the colder fluidizing gas. The fluidization gas inlet (5) and the secondary gas inlet (6) are shown small and shown in the front wall (wall that is parallel to the width), but essentially each of them can independently be a large hole, in particular , in the side wall (which is parallel to the length), and in particular the side wall of each granulation compartment, may be provided with such an inlet for fluidization gas and/or secondary gas, where the optional cooling compartment may, for example, have an inlet for gas for fluidization in the side wall.

In FIG. 2 schematically shows an example of a granulator. In FIG. 2A, the fluidization gas flow is shown schematically by a dotted line extending from the fluidization gas inlet (5) and then passing through the first space (21) around the secondary gas holes (25) and through the holes (16) in the plate (14) for fluidization in the first space (21), in particular in the department

- 8 040458 leniya (A, B) granulator. The granulating liquid flows through the granulating liquid inlet (10), and then passes through the granulating liquid supply manifold (11), including through the receiver (12) (which includes branches in the width direction), and then through the risers ( 13) to the inlet (19) of the injector. The secondary gas flow is also schematically shown as a dotted line from the secondary gas inlet (6) and then through the third space (23) and through the secondary gas port (25), through the secondary gas channels (20) to the inlet (19) Nozzles for granulating liquid. The receiver (12) is located in the upper part of the third space (23) directly below the separation plate (15), but the secondary gas can bypass the receiver into the channels (20) for the secondary gas.

In FIG. 2A shows an example of a preferred feature that a granulating liquid receptacle (12) is provided in a third space (23) (in particular, that the receptacle is located entirely within the third space) and that the third space chamber contains an inlet (10) for the granulating liquid. This preferred feature is also shown in FIG. 1.

In FIG. 2A shows an example of embodiments, wherein the receiver (12) is positioned close to the separation plate (15) and the riser (13) is connected to the receiver (12) at the secondary gas port (25). In this embodiment, the receiver (12) is close to the separation plate (15), which is not preferred because the fluidization gas is often colder than the secondary gas. In particular, it is preferable that the receiver (12) and the separation plate (15) are separated from each other by some distance in a vertical position (as shown in Fig. 1).

In FIG. 2B is an enlarged view perpendicular to the length of a portion of the granulator shown in FIG. 2A showing how the risers are connected to the receptacle at the secondary gas port.

In FIG. 3 schematically shows an example of a preferred feature that the granulator contains one or more optional compartments (C) for cooling. In this cooling compartment, the fluidization plate (14) is, for example, a horizontal plate, but preferably inclined downwards towards the granulate outlet (7), shown as plate (14A). The plate (14), for example, is curved (at an angle) down to the outlet (7), as shown in the alternate plate configuration (14B). The fluidization gas is fed into the cooling compartment (C), in particular into its first space (21), through holes (16) in the plate (14). The inclination of the fluidization plate (14) has the advantage of increasing the height of the bed, while also increasing the volume of the bed and advantageously increasing the residence time.

In addition, as shown in FIG. 3, the granulating liquid is fed through the fourth space (24), which is an optional feature independent of the cooling compartment (C). This fourth space (24) is provided with an optional second spacer plate (24A) which has holes for the lower end of the riser (13) or through which the risers pass. The fourth space (24) provides a simple implementation of the receiver (12) and the distribution of liquid over the risers. However, with a longer residence time of liquid urea in the fourth space (24), more biuret may form, which is undesirable.

Accordingly, in FIG. 3 shows an exemplary embodiment, wherein the separating plate (15) between the second space and the third space is the first separating plate, and the granulator further comprises a second separating plate (24A) between the first separating plate (15) and the bottom wall (3). Thus, a third space is provided between the first separation plate and an optional second separation plate (24A) and a fourth space (24) is provided between the second separation plate (24A) and the bottom wall. The fourth space has a chamber, and this chamber contains an inlet (10) for the granulating liquid. The second separating plate (24A) contains holes (24B) through which risers (13) pass. Thus, the fourth space is connected by holes (24B) to the inlet (19) of the nozzle for granulating liquid and, accordingly, the fourth space provides a receiver (12) of granulating liquid.

In FIG. 3 also shows an example of an independent preferred feature in that the granulator further comprises one or more cooling compartments. In FIG. 3, the cooling compartment is located downstream of the granulation compartments and contains a granulate outlet. The fluidization plate of the granulation compartments is the first fluidization plate, and the cooling compartment comprises a top wall and a second fluidization plate. The top wall and the fluidization plate form a first cooling space therebetween. The granulator is configured to hold the fluidized bed of particles in said first cooling space during operation. Meanwhile, the second fluidization plate is provided with a plurality of holes and thus allows the fluidization gas to pass from the second space (22) to the first cooling space. At least a portion of the second fluidization plate is below said first fluidization plate, such as a second fluidization plate

- 9 040458 contains a downward slope and/or downward bends. It is preferable not to place the separating plate (15) under the second fluidizing plate, thereby providing space for such a slope or bend.

In FIG. 4 schematically shows an embodiment, with the receiver (12) located below the bottom wall (3) and each riser (13) passing through an opening (3A) in the bottom wall (3). Therefore, the risers (13) have a bottom hole in the holes (3A) or pass through these holes (3A). This provides a simple design. However, the thermal insulation of the receiver (12) may be thinner than shown in FIG. 1, 2 and 3.

Accordingly, in FIG. 4 shows an exemplary embodiment, wherein the granulating liquid receiver (12) is provided outside the granulator chamber (2), while the risers (13) extend (vertically) through the secondary gas openings (25), through the third space (23) and through the openings ( 3A) for risers (13) in the third space chamber. Holes (3A) are generally provided in the chamber (2) of the granulator. Holes (3A) are preferably provided in the bottom wall (3). Such an arrangement advantageously provides good access to the third space and access to the receiver.

In FIG. 5 schematically shows an exemplary embodiment, wherein the first granulator compartment (A) comprises a first granulation liquid supply manifold (11) for the first granulation liquid, and the second granulator compartment (B) comprises a second granulation liquid supply manifold (11A) different from the first one, which can be used to spray a second granulating liquid with a different composition. The first granulating liquid is, for example, urea (containing, for example, less than 1.0 wt.% ammonium salts or less than 0.10 wt.% ammonium salts). The second granulating liquid supply manifold (11A) has a dedicated granulating liquid inlet, for example with a mixing module (10A) for mixing the urea melt (U) or other type of granulating liquid with the second stream. The second stream contains, for example, one or more selected from the group consisting of ammonium salts, additives, trace elements, sulfates, phosphates and nitrates. The second stream is, for example, urea sulfate mixture (UAS), containing, for example, 10-50 wt.% ammonium sulfate. The second granulating liquid is, for example, a melt of a mixture of urea with ammonium salts, such as ammonium urea nitrate or ammonium urea sulfate (containing, for example, at least 10 wt.% ammonium salt), and preferably the first liquid is, for example , carbamide melt.

In principle, any granulation compartment can be provided with such a mixing module. Preferably, the granulation fluid supply manifolds, more preferably the mixing modules, or at least some of them have a metering module, such as a control valve, for fine control of the additive flow rate. In a particularly preferred embodiment, the granulator comprises at least two compartments, an upstream first compartment and a downstream (for particles) second compartment having separate feed manifolds, and the first compartment feed manifold contains a mixing module. In this way, for example, a higher concentration of a component such as an additive (eg ammonium salt) can be achieved in the liquid sprayed in the first compartment compared to the liquid sprayed by the nozzles in the second compartment. Thus, there may be a high concentration of urea in the outer layers of the granules. This distribution can provide a high critical relative humidity of the formed granules.

In FIG. 5 shows an exemplary embodiment wherein the granulator comprises a plurality of granulation liquid manifolds, each having an inlet for granulating liquid. Each collector contains a receiver and risers. The at least two granulation compartments preferably have separate granulation liquid collectors. The granulator preferably comprises at least two manifolds that are not connected to or provided in the same granulator compartment. In a preferred embodiment, the granulator comprises first and second granulation compartments, wherein the first granulation compartment comprises said first granulation liquid collector and does not contain said second granulation liquid collector, and wherein the second granulation compartment contains said second granulation liquid collector and does not contain said the first collector of the granulating liquid. Each manifold is preferably connected to a separate granulation compartment. Each granulation compartment is preferably connected to a separate distributor. For example, the granulator has a granulation liquid collector dedicated to one granulation compartment, and the nozzles of this compartment are not connected to another granulation liquid collector. The advantage is that different granulation liquid collectors can use the same third space (23) for secondary gas supply and can use the same secondary gas. In this way, a simple design of the secondary gas supply system is obtained even when different granulation liquids are used. However, the third space (23) can also advantageously be divided into compartments, each compartment having a separate secondary gas inlet.

- 10 040458

The granulator preferably includes a granulation liquid supply line connected to at least one, but not all, of the preferred plurality of granulation liquid manifolds, and an additive supply mixer connected to the granulation liquid supply line to mix the additive into the granulation liquid in the supply line.

In FIG. 6 is a schematic top view (in the length L and width direction W) of an example of a granulator according to the invention (FIG. 6A) and a front view in the height H direction and in the width W direction of the first embodiment (FIG. 6B) and the second embodiment ( Fig. 6C). In a preferred embodiment of the invention, the receiver (12) includes, for example, a shaft and branches that are provided inside the chamber (2). The barrel extends in the length direction and in the middle of the granulator in the width direction. An example is shown in FIG. 6A. The branches extend in a widthwise direction on opposite sides of the stem, optionally on both sides above the stem (FIG. 6C). Thus, it is an advantage that a short residence time of the granulating liquid is achieved (due to the short middle passage for the granulating liquid between the inlet (10) and the riser (13) and therefore to the inlets (19) of the nozzles. Short residence time and short the middle duct are particularly advantageous in preventing or reducing the formation of biuret when the granulating liquid is urea Biuret formation occurs rapidly in hot concentrated urea solutions at high temperature In particular, the location of the receiver under the separation plate (15) allows for an advantageous configuration shown in Fig. 6A.

In FIG. 7 shows a prototype of a granulator not in accordance with the invention, whereby an enclosing trough (32) is used to supply the secondary gas from the inlet (31). An independent feature is that the receiver shaft extends beyond the granulator chamber (2) on one side of the granulator in the lengthwise direction, while the shaft is provided with branches extending in the width direction on one side. The branches run, for example, in the space inside the granulator chamber directly below the fluidization plate. These branches are provided with risers. In FIG. 7 branches with female trays (32), for example, are located directly below the fluidization plate. If the prototype granulator shown in FIG. 7 be modified by replacing the enclosing tray (32) with secondary gas channels according to the invention, as in the granulator embodiment of the invention shown in the modified FIG. 7 will result in a less preferred embodiment compared to the embodiment shown in FIG. 6A, since the average length of the granulating liquid flow in FIG. 6A is shorter.

In FIG. 8 is an isometric view of an example of a granulator according to the invention. Sidewalls (27) are shown; in the example shown, one side wall includes a gap for the inlet (5) for the fluidization gas, as well as a gap for the inlet (6) for the secondary gas. The receiver (12) is located inside the third space (23) in the same way as shown in FIG. 1.

In a preferred embodiment (an example of which is shown in FIG. 8), the receptacle (12) is connected to a conduit for supplying a cleaning fluid (such as water and/or steam). For example, the receiver, in particular the inlet (10) for the granulating liquid, is connected to the supply line (28) of the cleaning fluid, and the supply line is preferably connected to the supply channel through the valve. The supply channel is, for example, an inlet (29) for steam. The receiver preferably also has an inlet connected (preferably through a valve, and, for example, through a cleaning fluid supply line (28) to a drying gas supply channel, which is preferably for drying air, for example, to a gas supply channel (30). The gas supply channel (30) is, for example, in turn connected to a secondary gas (eg secondary air) outlet of the second space (22). In an alternative embodiment, the gas supply conduit (30) may be connected to any source of gas, for example to the secondary gas duct (6) or to the first space (21) for receiving gas for fluidization from the inlet (5) or to some or other duct for fluidization gas. The connections are, for example, independently provided with a three-way valve or, for example, comprise a tee with valves. Thus, the granulator can be switched between a first configuration in which the receiver (12) only receives granulating liquid, a second configuration in which the receiver (12) only receives a cleansing fluid (e.g. steam), and a third configuration in which the receiver (12 ) only accepts secondary gas from the inlet (6). Thus, the granulating liquid supply manifold (11), including the receiver (12) and riser (13), can first be flushed with a cleaning fluid (for example, water and/or steam) and then dried with a drying gas (for example, secondary gas ) for, thus, the collector (11) supply of granulating liquid. In some embodiments, the gas supply conduit (30) and the cleansing fluid supply line (28), for example, have separate connections to the receiver.

The invention also relates to a urea plant comprising a fluid bed granulator as described herein. Urea plant

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Claims (7)

additionally contains, for example, a high-pressure urea synthesis section operating at a pressure of at least 100 bar (for example, 110-160 bar), a regeneration section, including a low-pressure regeneration section (for example, 1-10 bar) and optionally a medium pressure regeneration section (operating at a pressure of, for example, 15-60 bar) located between the synthesis section and the low pressure regeneration section, and an evaporation section located downstream of the regeneration section, which is designed to evaporate water from the urea solution to obtain a urea smelt. The granulating fluid supply manifold of the granulator is connected to the urea melt outlet in the evaporation section. The high pressure synthesis section includes, for example, a high pressure reactor, a high pressure stripper (eg using CO2 as stripping gas or using thermal stripping) and a high pressure carbamate condenser, eg located in an isobaric loop. The stripper has an outlet to the regeneration section. The urea formation reaction is based on the reaction of NH3 and CO2 at high pressure to produce ammonium carbamate and dehydrate it to urea and water. The evaporation section contains, for example, one or more successive stages of (vacuum) evaporation and operates, for example, at a pressure below 1 bar abs. In the regeneration section(s), the urea solution is, for example, subjected to heat to decompose ammonium carbamate and remove ammonia from the urea solution, and thus purify the urea solution. After condensation, the ammonia and CO ₂ gases removed are returned to the synthesis section. The invention also relates to a process for granulating, preferably urea, carried out in the granulator described, and more preferably in the urea plant described. The method includes, for example, supplying a granulating liquid, for example, as described above, preferably melting carbamide, to the granulating liquid inlet (10) and through the granulating liquid supply manifold (11), including a receiver (12) and risers (13) , supplying gas for fluidization to the inlet (5) for fluidization gas and supplying secondary gas to the inlet (6) for secondary gas of the granulator and extracting the granulate from the outlet (7) for granulate, while preferably the gases described in this document. The method, as a rule, additionally includes holding in the first space (21) a fluidized bed of granules and supplying the granulating liquid to the first space using nozzles (17). The nozzles are, for example, atomization nozzles that use a secondary gas to atomize the granulation liquid. In a further embodiment, the nozzles are, for example, film nozzles, providing a film of granulation liquid from the first outlet of the nozzle, while the secondary gas is passed through a separate outlet (for example, annular) surrounding the first outlet, to conduct particles of the fluidized bed through specified film. The reference numbers used in the present description and claims are for purposes of illustration and to facilitate understanding of the drawings only. These reference numbers do not limit the claims and the invention. One skilled in the art will appreciate that in the construction shown in FIG. 1, 2, 4, 5, 6 and 8, a cooling compartment can also be used, optionally including an inclined fluidization plate and/or an inclined separation plate. In at least the construction shown in FIG. 1, 2, 3, 4, 6 and 8, it is also possible to use two or more granulation liquid collectors and a mixing module. In at least the construction shown in FIG. 1, 2, 3, 5 and 6, the side wall construction shown in FIG. 8. CLAIM 1. Fluidized bed granulator (1) for granulating urea or carbamide-containing liquids, containing a granulator chamber (2), wherein the granulator chamber (2) contains: bottom wall (3), top wall (4), gas inlet (5) for fluidization, an inlet (6) for secondary gas, an outlet (7) for solid particles of the product and an outlet (8) for exhaust gas, while the chamber (2) of the granulator contains a plurality of compartments (A, B) for granulation located sequentially in the direction along the length of the granulator, and the granulator (1) additionally contains an inlet (10) for granulating liquid and a collector (11) for supplying granulating liquid, while the collector (11) for supplying granulating liquid contains a receiver (12) for granulating liquid and a plurality of risers (13), wherein the granulating liquid receiver (12) is connected to said granulating liquid inlet (10) and to a plurality of said risers (13), with In addition, the chamber (2) of the granulator additionally contains a plate (14) for fluidization and a separating plate (15), at least in the indicated compartments (A, B) for granulation, and the separating plate (15) is spaced from the plate (14) for fluidization in a vertical - 12 040458 board and is placed below the plate (14) for fluidization, while the separating plate (15) is located between the specified lower wall (3) and the specified plate (14) for fluidization, and the specified chamber (2) of the granulator contains the first space (21 ) between said upper wall (4) and said fluidization plate (14), a second space (22) between said fluidizing plate (14) and said separating plate (15), and a third space (23) between said separating plate (15) and said bottom wall (3), wherein each of said first, second and third spaces has a chamber, wherein said granulator is configured to hold a fluidized layer of particles during operation in said first space (21), and at the same time the chamber of said first space (21) contains the specified outlet (7) for solid particles of the product and the specified outlet (8) for the exhaust gas a, moreover, the chamber of the specified second space (22) contains the specified inlet (5) for the gas for fluidization, and the plate (14) for fluidization contains holes (16) for the passage of the specified gas for fluidization from the specified second space (22) into said first space (21), wherein said chamber of said third space (23) contains said inlet (6) for secondary gas, wherein the granulator contains a plurality of nozzles (17) in said compartments (A, B) of the granulator for supplying said granulating liquid into said first space (21), wherein at least one of said nozzles (17) comprises an inlet (18) of a nozzle for said secondary gas and an inlet (19) of a nozzle for said granulating liquid, wherein said granulator contains a channel (20 ) for the secondary gas, which passes from the hole (25) for the secondary gas in the said separation plate (15) through the said second space (22) to said inlet (18) of the secondary gas injector, wherein said granulating liquid supply manifold (11) is partly located in said third space (23) and partly in said second space (22), and at the same time at least one of said risers (13) is located at least partially inside said channel (20) for secondary gas, wherein said riser (13) passes through said hole (25) for secondary gas or is connected to said receiver (12 ) at the indicated outlet (25) for secondary gas. 2. The granulator according to claim 1, in which the specified channel for the secondary gas is a first pipe, and the specified riser or part of the specified riser, located in the specified channel for the secondary gas, is a second pipe, and the specified first pipe surrounds the specified second pipe in cross section in the horizontal plane at at least one vertical position. 3. A granulator according to claim 1 or 2, wherein said granulating liquid receiver is located in said third space, and said chamber of said third space contains said granulating liquid inlet. 4. A granulator according to claim 3, wherein said granulating liquid receiver is spaced from said separation plate in a vertical direction, and wherein said riser passes through said secondary gas port in said separation plate. 5. The granulator according to claim 3 or 4, in which the specified receiver of the granulating liquid contains a shaft and branches, and the specified shaft extends in the direction along the length of the granulator, while these branches extend in the width direction of the granulator outward from the specified shaft on opposite sides of the specified shaft, and said sides are located opposite each other in the width direction so that the specified shaft is located essentially in the center of the specified third space in the width direction, and each of these branches is connected to a plurality of these risers. 6. A granulator according to claim 1 or 2, wherein said separation plate between said second and third spaces is a first separation plate, said granulator further comprising a second separation plate (24A) between said first separation plate and said bottom wall, wherein said third space is provided between said first and second separating plate, wherein a fourth space (24) is provided between said second separating plate and said bottom wall, said fourth space having a chamber, said chamber of said fourth space containing said inlet (10) for granulating liquid, wherein said second separating plate contains an opening (24B) through which one of said risers (13) passes and thus connects said fourth space with said inlet (19) of the nozzle for granulating her liquid so that the specified fourth space creates the specified receiver (12) granulating liquid. 7. Granulator according to any one of claims 1 to 6, wherein the riser (13) and the channels (20) for the secondary gas are concentric pipes. -