DE10146778B4 - Process and fluidized-bed plant for the production of compact solid particles - Google Patents

Abstract

Continuously operated process for the production of compact solid particles, in particular of built-up granules, in a fluidized bed, in which a circulating particle movement is superimposed by a positively guided material flow in the direction of the material discharge, wherein
- The fluidized bed in several areas (7) an air supply (I) from below in each case an adjustable Fluidisierungsmittelstrom (1) for maintaining the fluidized bed and for drying or cooling of the fluidized bed material is fed;
- Each area (7) is associated with a corresponding area in the process space (II), which in turn has areas (16) with an increased flow velocity of the acted upon with the material to be treated Fluidisierungsmittelstroms (1);
- The raw material (2) is supplied to the areas (16) with increased flow velocity of un th and in the flow direction of Fluidisierungsmittelstroms;
- The material from the areas (16) with increased flow rate of the fluidized bed (9) is supplied from above;
- A portion of the material of the fluidized bed (9) in the respective area (16) with increased flow velocity again ...

Description

The The invention relates to a method and the associated fluidized bed system for the production of compact solid particles.

Fluidized bed plants for the treatment of different materials are well known. For example, according to the DD 119 304 known to spray liquids by means of nozzles on a fluidized bed. The fluidized-bed system consists of an apertured fluidized bed, to which drying and fluidizing air is supplied from below.

To are different versions both with regard to the design of the fluidized bed plant as well as the feed of the spraying material known. The fluidized bed system can be both round and be formed rectangular as a gutter or as a fluidized bed apparatus. The spraying of the in the fluidized bed existing material with appropriate materials can be applied from the top to the fluidized bed (top-spray) or from below the fluidized bed into it (bottom-spray) or from the side. The spray liquid can as a solution, Suspension, emulsion, melt, or as any other pumpable and atomizable liquid system available.

From the DE 197 00 029 A1 is a fluidized bed apparatus is known in which the regulation of the material properties of the final product is carried out by means disposed over the distributor plate internals. The internals of specially designed weirs influence the material circulation in the fluidized bed and thus influence the material properties of the materials to be produced. In this case, an agglomeration of the individual material particles is expressly desired.

From the EP 0 163 836 B1 a process for the production of granules is known in which the nuclei of the fluidized bed are produced by internal products. By integrating dust collectors in the fluidized bed apparatus, dusts and fine particles are returned to the liquid-wetted area of the fluidized bed. These materials form corresponding agglomerates in the fluidized bed.

at The plants described mainly produce wanted agglomerates. The agglomerates have a rough surface texture and roundness the individual particle is not fully developed. In the production of solid Product forms, it is necessary in many cases, well-defined Produce particle structures. For many applications prove Granules advantageous by the build-up granulation in the Fluidized bed can be produced. For these granules is especially focused on a compact structure with very good roundness and smooth particle surface Added value.

To produce these special material features, the use of riser tubes in batch apparatus for coating, for example, tablets according to the U.S. 3,089,824 . US 3,241,520 and US 3,253,944 known. From the US 3,241,520 is a series connection of many individual apparatuses known in which the discharge material of the previous stage is the entry material in the next stage. The described coating process is here dissected into individual apparatuses. The system is very complex and has a complicated geometry.

The applicant has already filed an earlier application for coating (coating) particles in continuous process control in accordance with the DE application 101 30 334 proposed. The coating material is applied continuously in at least two different areas on the fluidized bed.

From the DE 38 08 277 A1 a device for fluidized bed spray granulation with only one spray nozzle is known, which is concentrically enclosed by an annular zigzag sifter and an attached at the junction of the inflow return duct. The suction of the spray nozzle is supported by a collar-shaped cross-sectional constriction at the outlet of the return duct. With the known device, a fluidized bed granulation with classified discharge is sought, in which the relatively coarse, regardless of the size of the apparatus already grown almost to desired size granules not with decreasing, but participate with increasing frequency in the screening process to exclude malfunction.

Also you know from the DE 36 09 133 A1 already an apparatus for the production and treatment of pellets, which is characterized by a rotating rotor disk in the region of the fluidized bed tank. In the prior art device, starting from a powdery mass, a pellet is produced by an agglomeration process. For this purpose, the powder particles are sprayed with a liquid (film-coated), which causes the sticking together of the powder particles. This moist agglomerate or the moist powder particles are conveyed by a riser against a rotating disc, which generates a circulation of the solids flow. This mechanical stress causes a "kneading effect" of the agglomerated particles and a "compression". This results in compact and dense particles. With the out DE 36 09 133 A1 Prior art device, it is not possible compact granules predominantly or exclusively by spraying granulation of a liquid raw material. Furthermore, circulating the moist fluidized bed mass through the rotor causes caking on the rotor disk, which limits the process stability and thus the plant availability. A continuous process is out of the question DE 36 09 133 A1 previously known device therefore not possible.

The The object of the present invention is a method and the fluidized bed plant for the production of compact solid particles so to design that according to the application cases by a build-up granulation or coating (Coaten) manufactured end product with defined Particle structures under avoidance of agglomeration effects arises.

Corresponding the method according to the invention The object is achieved with the features of claim 1 and the associated device according to the characteristics of claim 6 solved. Advantageous embodiments of the method and the device are in the subclaims specified.

By the application of the material to be treated in one area with a higher one flow rate and in conjunction with a particle circulation between it Area and the fluidized bed becomes an agglomeration of the material avoided. By the particle circulation and by the structure of a arise expanding area due to the higher flow rates defined particle structures while avoiding agglomeration effects.

By the arrangement of built-in parts in the process space of the fluidized bed plant over the Nozzles of the spray system will equalize the Granulation achieved. supports This is on the one hand by the arrangement of the mounting parts in one Distance over the fluidized bed floor and on the other hand by the larger opening ratio of the gas passage openings the fluidized bed below the mounting parts with respect to the other gas passage openings the fluidized bed floor. In the upward air currents in The built-in parts are to be granulated or coated Particles dispersed as far as possible in the air stream, so they as Single particles with liquid sprayed can be. The liquid evaporated, the granules grow, or it forms a closed shell from coating material around the particles. It arises under avoidance of agglomeration effects a final product with a defined Particle structure. By arrangement of several, in the length of Fluid bed floor mounted components is the grain size of the material to be produced affected.

By Setting the distance of the lower edge of the mounting parts of the Fluidized bed floor, the opening ratio the gas passage openings of the arranged below the components fluidized bed and the height and the diameter or the width of the built-in parts in dependence on the Solid particles to be produced is the material formation in the Fluidized bed and in the built-in components so influenced that undesirable agglomeration effects be avoided as far as possible and the products to be produced have a well-defined particle structure according to the requirements.

The Invention is based on embodiments explained in more detail. In the accompanying drawings demonstrate:

1 a schematic sectional view of the fluidized bed plant according to the invention in a rectangular design,

2 a variant according to 1 .

3 a cross section according to 1 with built-in components,

4 a cross section according to 1 with rectangular built-in components,

5 another variant according to 1 ,

The production of the products in granular form takes place by fluidized bed granulation (build-up granulation, storage) in a substantially horizontally oriented fluidized bed 9 , The fluidized-bed plant for the production of compact solid particles consists of a fluidized-bed floor provided with gas passage openings 8th , via a supply air chamber 7 a spray system 13 associated with corresponding nozzles. In the process room II the fluidized bed plant are above the area of the nozzles of the spray system 13 fixtures 10 arranged to delimit the Bedüsungsbereiches whose respective lower edge of the surface of the fluidized bed 8th is spaced and their respective upper edge at a distance above the surface of the fluidized bed 9 ends, or until the relaxation room III the fluidized bed plant protrudes. The distance between the lower edge of the built-in parts 10 from the fluidized bed floor 8th , the opening ratio of the gas passage openings of the under the built-in parts 10 arranged fluidized bed floor 8th and the height and the diameter or the width of the built-in parts 10 are variably adjustable depending on the solid particles to be produced. According to the technical conditions, it is possible the built-in parts 10 to be arranged in a predetermined angle to the vertical.

The below the built-in parts 10 fluidized bed floor 8th is provided with gas passage openings whose opening ratio is greater than in the remaining area of the fluidized bed 8th , The built-in parts 10 have the same in the fluidized bed 9 Ruling conditions a round, rectangular, square or polygonal cross section.

In the continuous coating of powdery to fine-grained solid particles separating plates are on the ceiling of the fluidized bed plant 24 arranged in the relaxation room III the fluidized bed plant in the area between each two built-in parts 10 protrude and above the built-in parts 10 end up.

The mode of action of the fluidized-bed plant according to the invention is the following:
For the production of compact solid particles in granular form by fluidized bed granulation is a liquid raw material 2 over the nozzles of the spray system 13 into the vortex layer 9 brought in. The in the process room II Particles contained by an upward air flow 1 whirled. This flow not only serves to form the fluidized bed 9 itself, but at the same time it forms the drying or cooling agent, depending on whether the drying of a liquid, which is present as a solution, suspension or emulsion, or a crystallization o. Ä. To bring about, in which the liquid raw material is present as a melt or the like. The supplied air flow passes through a supply air housing I in the fluidized bed plant. The supply air housing I is in several supply air chambers 7 divided to set a directional flow or different amounts of air can. The delimitation of the supply air housing I from the process room II is through the fluidized bed floor 8th formed to equalize the air flow over the apparatus cross section and to prevent passage of the fluidized bed mass into the supply air housing I serves. In the case of build-up granulation by thermal drying in the fluidized bed 9 An atomization of the liquid raw material takes place 2 on the in the fluidized bed 9 contained particles. On the surface of which evaporates the liquid, and the solid of the injected raw material 2 remains adhered to the particles, resulting in almost cup-like grain growth.

The vaporized liquid is removed from the process space with the now cooled fluidizing agent II over the relaxation room III and the separation room IV from the fluidized bed system as exhaust air 5 dissipated. As a result of intensive mixing and particle movement in the fluidized bed 9 For the formation of abrasion and thus comes from fine dust, a dedusting of the exhaust air flow is necessary, both externally outside the actual fluidized bed plant and in an integrated within the fluidized bed separation chamber IV can be done. Combinations of both variants are also conceivable in which a preliminary separation takes place in the fluidized-bed plant and, downstream of this, a fine-material separation takes place outside the fluidized-bed plant.

In the 1 is an internal filter 11 indicated, which has a cleaning mechanism 12 , for example by compressed air 4 if necessary or timed cleaned. The thereby separated dust falls into the fluidized bed 9 back where it is used as a granulation germ, the liquid raw material 2 is used up. Alternatively or in parallel, granulation germs can 3 be supplied from the outside. These can be obtained by grinding a partial stream of the finished product 6 or obtained by oversize separation.

Farther is also the same time or alternatively the introduction of foreign material conceivable from other processes, if, for example, a starting grain with wrapped in another component shall be. This process is called coating, coating or encapsulation denotes and represents a special case of build-up granulation.

If germs are introduced from the outside into the fluidized bed plant, in most cases a pressure separation between the interior of the fluidized bed plant and the environment is necessary. This is done for example by a rotary valve 14 or by a double flap system. In other cases, the entry can also be open. The discharge of the finished product 6 can be done in different ways. In the embodiment, the material discharge takes place via a speed-adjustable rotary valve 15 , Depending on the speed and chamber volume, a defined volume flow from the fluidized bed 9 withdraws and thereby ensures the pressure. Other variants can be the most diverse Wehreinbauten at the end of the fluidized bed 9 represent. For example, an overflow weir makes it very easy to keep the fluidized bed height constant.

Within the fluidized bed system are by the arrangement and design of fixtures in the form of built-in parts 10 optimal process conditions for the granulation set. The built-in parts 10 affect the homogenization of granulation. Under each built-in part 10 a nozzle is arranged through which granulation or coating liquid is injected. The built-in parts 10 have a distance from the fluidized bed floor 9 so that the solid particles of the fluidized bed 9 due to the higher flow velocity in the built-in parts 10 aspirated, led upwards and thereby by the spray liquid in the spray area 16 be overwhelmed. In the upward air currents in the built-in parts 10 For example, the particles to be granulated or coated are largely dispersed in the air stream, so that they can be sprayed with liquid as individual particles. The liquid evaporates, the granules grow, or it forms a closed shell of coating material around the particles.

The fluidized bed floor 8th has in the area under the built-in parts 10 a higher aperture ratio than in the rest of the range. This leads to higher flow velocities in the built-in components 10 , This flow rate depends on the particle size and density.

In technically interesting fluidized bed plants of this type are usually several nozzles side by side across the width of the fluidized bed 8th Installed. The built-in parts 10 can then be designed as internals with rectangular cross-section and capture all the nozzles, which are arranged side by side. In 5 such an arrangement is shown.

After passing through the built-in parts 10 the solid particles fall outside the built-in parts 10 in the area of particle circulation 17 on the fluidized bed floor 9 and become again from the upward gas flow of the built-in parts 10 detected. So the process is repeated over the length of the fluidized bed 9 several times until the particles are sufficiently large or the coating layer is formed sufficiently thick.

The positively driven material flow serves to achieve even granules. Agglomeration between the particles is avoided, especially as long as they are fine-grained. In the case of the coating, high quality standards are achieved. Closed coating surfaces or the application of a solid matrix on the particles are possible. In the case of the coating is usually oriented to external dust filter. The low-level dust can be easily removed from the system and used elsewhere, without the product quality of the final product in the case of return to the fluidized bed 9 to diminish.

In 2 is a rectangular fluidized bed plant for the continuous granulation of solids-containing liquid via a spray system 13 is entered. Above each nozzle of the bottom-spray spray system 13 is a built-in part 10 at a certain distance above the fluidized bed floor 8th arranged. The one from the cyclone separators 21 recycled dust 19 gets into the spraying area 16 under the built-in part 10 introduced and serves as a seed material for the granulation to be carried out. This from the cyclone separators 21 supplied material is together with egg nem part of the material from the fluidized bed 9 through the gas flow in the installation part 10 aspirated and dispersed in the gas stream and with liquid raw material 2 through the spray system 13 sprayed. The dusty exhaust air 18 returns to the cyclone separators 21 and is dedusted there. The grown particles become with the air flow 1 from the built-in part 10 discharged and get over the particle circulation 17 back into the fluidized bed 9 outside the built-in parts 10 , Upon reaching a corresponding particle size, the material is on the Granulataustrag 20 discharged. If the material particles have not yet reached the required size, they will be replaced by those in the installation part 10 prevailing gas flow sucked and in the built-in part 10 further aggravated. The about the granulate discharge 20 discharged material is in a known, with classifying air 23 operated zig-zag sifter 22 classified. The finished product is via the rotary valve 15 discharged while the dusty exhaust air 18 a cyclone separator 21 is supplied.

In the 5 is a fluidized bed system with rectangular geometry for continuous coating of powdered to fine-grained solid particles shown. An integrated separation system for accumulating dust is dispensed with, because this deteriorates the coating quality. Dust gets in the air 5 discharged from the fluidized bed plant and deposited outside. The special feature of this variant are the dividers 24 between the coating areas. This will cause the exhaust air 18 purposefully guided and arrives as exhaust air 5 out of the plant. The dividers 24 avoid a gas movement and thus a particle movement in the longitudinal direction of the fluidized bed 9 , The dividers 24 extend down to the area of the upper edge of the built-in parts 10 and are over the entire width of the fluidized bed 9 educated.

1

airflow

2

raw material

3

granulation nuclei

4

compressed air

5

exhaust

6

finished product

7

supply air

8th

Fluidised bed

9

fluidized bed

10

fitting

11

filter

12

Cleaning mechanism

13

spray system

14

rotary

15

rotary

16

spraying region

17

particle circulation

18

exhaust

19

Dust recycling

20

Granulataustrag

21

cyclone

22

Zigzag classifier

23

classifying air

24

Divider

I

air supply casing

II

process space

III

relaxation room

IV

separating chamber

Claims (11)

Continuously operated process for the production of compact solid particles, in particular of built-up granules, in a fluidized bed, in which a circulating particle movement is superimposed by a positively guided material flow in the direction of the material discharge, wherein - the fluidized bed in several areas ( 7 ) an air supply ( I ) from below in each case an adjustable fluidizing agent flow ( 1 ) is supplied to maintain the fluidized bed and to dry or cool the fluidized bed material; - every area ( 7 ) a corresponding area in the process space ( II ), which in turn has areas ( 16 ) with an increased flow velocity of the fluidizing agent flow applied to the material to be treated ( 1 ) having; - the raw material ( 2 ) into the areas ( 16 ) is supplied with increased flow velocity from un th and in the flow direction of the Fluidisierungsmittelstroms; - the material from the areas ( 16 ) with increased flow velocity of the fluidized bed ( 9 ) is supplied from above; A part of the fluidized bed material ( 9 ) into the respective area ( 16 ) is returned with increased flow rate, so that between the fluidized bed ( 9 ) and the respective area ( 16 ) creates a particle circulation; and - the other part of the material is continued in a positively-guided flow in the direction of material discharge. Process according to claim 1, wherein the starting materials pure liquids, Solutions, Melt, solids or gases are. The method of claim 1 or 2, wherein the discharge of the final product with or without a classifying discharge. Process according to claims 1 to 3, wherein the process takes place in a separation chamber ( IV ) deposited material ( 19 ) the areas ( 16 ) is supplied. Process according to Claims 1 to 4, in which the fluidized bed ( 9 ) Granulation germs ( 3 ). Fluidized-bed plant for the production of compact solid particles, in particular of built-up granules with - one of several chambers ( 7 ) existing supply air housing ( I ), at the bottom of which feeds for introducing a fluidizing medium for maintaining the fluidized bed and for drying or cooling the fluidized bed material are arranged such that for each chamber a respective fluidizing agent flow ( 1 ) can be adjusted, whereby a directed flow can be generated; A fluidized bed arranged above the supply air housing ( 8th ) provided with gas passage openings for equalizing the fluidizing medium; A spraying system opening from below through the fluidized bed into the fluidized bed ( 13 ), which consists of several spray nozzles for feeding a raw material ( 2 ) consists; - an arrangement of installations ( 19 ) over the area of the nozzles of the spray system ( 13 ) in the process room ( II ) of the fluidized bed plant for influencing the material properties of the products to be produced, their respective lower. Edges from the surface of the fluidized bed ( 8th ) are spaced and their respective upper edges terminate at a distance above the surface of the fluidized bed, wherein the distance of the built-in parts ( 10 ) from the fluidized bed ( 8th ) as well as the height and the diameter or the width of the built-in parts ( 10 ) are variably adjustable and the opening ratio of the gas passage openings of the fluidized bed ( 8th ) below the built-in parts ( 10 ) is larger than in the remaining area of the fluidized bed ( 8th ); - A above the fluidized bed in the fluidized bed opening solid material feed; and a material discharge arranged downstream of the process space for the end product ( 6 ) Fluidized bed installation according to claim 6, in which the upper edges of the built-in parts ( 10 ) in the relaxation room ( III ) of the fluidized bed plant protrude. Fluidized bed installation according to claim 6 or 7, in which the built-in parts ( 10 ) have a round, rectangular, square or polygonal cross-section. Fluidized bed installation according to claim 8, wherein in the case of a rectangular cross section of the built-in parts ( 10 ) several, across the width of the fluidized bed ( 9 ) arranged nozzles of the spray system ( 13 ) un below the respective installation part ( 10 ) are arranged. Fluidized bed installation according to claim 6 to 9, in which at the ceiling of the fluidized bed plant separating plates ( 24 ) are arranged, which extend over the entire width of the fluidized bed plant and in the relaxation room ( III ) of the fluidized bed plant in the area between each two built-in parts ( 10 ) and above the built-in parts ( 10 ) end up. Fluidized bed installation according to claim 6 to 10, wherein the dust return lines ( 19 ) of the fluidized bed downstream cyclone separator ( 21 ) in a below the built-in parts ( 10 ) with increased flow velocity ( 16 ).