DE9110546U1 - Device for uniform, closed coating of grains, such as seeds, using a rotor granulator with integrated fluid bed drying - Google Patents

Description

- 1 G 91 28 258.2

The subject of the invention is a device

for the uniform, closed processing of grains, such as seeds, using a rotor granulator with integrated fluid bed drying.

Roller granulators, as disclosed in the German patents 21 65 430 (TAKEDA), JP-PS 47-47794 and 46-22544, consist of a rotationally symmetrical housing as the stator and a pressure chamber firmly connected underneath, with a flat or curved disk rotating between them around the common vertical axis as the rotor. The rotor and stator are separated by an annular gap which is kept free of particles by the air flow from the pressure chamber. The flow of the grains is accelerated radially and tangentially by the rotor and additional deflectors attached to it and braked at the circumference of the stator, and thus mixed by their internal friction in a toroidal or spiral-ring-like movement around the entire circumference of the container and circulated to the rotor. This allows a gentle transfer of high kinetic energy to circulate the grains and to overcome increased friction during coating.

Also in the German patents 33 34 543 and 33 37 830 (FRUUND) devices for introducing drying air through an expandable annular gap and an air duct as a flat annular gap or sieve on the roller surface are described. By introducing the increased air flow, the pests are fluidly

ized and thereby disrupted their acceleration and decomposition. The consequences of insufficient mixing, floating and separation of grain layers should be avoided by additional ventilation on the rotor and on the stator wall, which also accelerate the grain circulation, but primarily disintegration

granules that are too large or too unstable. These components are intended to smooth out and improve the original shape and surfaces of grains, such as extrudates, and also to ensure uniform agglomerate sizes. However, grains and their coatings can be damaged by the increased abrasion.

EU-PS 0 228 633 (AliROMATlC) discloses a rotor granulator, the inner layering chamber of which is enclosed by a ring-shaped drying chamber. The lower edge of the vertical or inwardly inclined partition wall as

0 Stator forms an adjustable annular gap with the rotor as

Conveyor channel for outer grain layers to the drying room. The bottom of the stator, which is also hollow, forms a ring slot that directs compressed air against the axis and the rotor surface and into the conveyor channel. This is intended to transport grains

5 rejected by the Unlcikanle and the Naclitcilc from increased

Back pressure and delay or jamming of grains during conveyance into the drying room can be avoided.

It is the object of the invention to develop a rotor granulator which brings about a gentle, uniform, closed coating of grains, in particular of seeds.

The device of the invention is in
Protection claim L defined.
The subclaims claim the
alternative and preferred embodiment of this device.

The inventive design of the device as a rotor granulator is shown in the drawing with Fig. 1 and Fig. 2, as cross section A-A from Fig. 1. Not shown are the devices for drive, filling, infeed and suction as well as suitable recycling devices and auxiliary units.

The superiority of the device according to the invention is described by the following examples.

Example 1 for the flexible design (Fig. 1) of the rotor granulator with introduction of drying air through the ring screen surface in the deflection screen above the stator (IA) compared to a state-of-the-art roller granulator with a discontinuous profile from rotor to stator

and enlarged annular gap, with a low (IB) and an increased compressed air inlet (OC).

Test parameters:

Filling: 4 liters = 1.8 kg beet seeds (Beta vulg.) Spraying: 330 grams of aqueous suspension with approx. 40% by weight

the coating materials such as color pigments, methylcellulose and polyacrylates as binding agents, and fungicide for the analysis of the coating solution.

Spray rate: constant 330 grams/min with 2-material nozzle, diameter 2 mm, spray air pressure 2.4 bar

A. Rotor granulator as shown in Fig. 1 without additional rotor deflectors, max. stator diameter 315 mm, radius of curvature of rotor and stator 40 mm up to the deflection with 15° internal inclination, ring gap width 0.2 mm, compressed air 2 bar, rotor speed 300/min., ring screen area 48 cm², pressure loss of ring screen and bed 92 mm WS, blower capacity approx. 8 000 liters/min with 20 "C B. Rotor granulator with cylindrical wall and flat rotor, stator diameter 300 mm,

20 mm of the rotor edge angled up by 30 degrees, ring gap length 0.4 min, compressed air 2 bar, temperature 20 °C. Rotor speed 300/min

C. Rotoigranulator according to 1 B, increased introduction of compressed air at 4 bar and temperature 20 "C.

(sec) O 10 0 (sec) 15 15 (sec) 30 10 20 (sec) 60 15 15-20 (sec) 15 30 (sec) 60

Test result: 1 λ IB IC

After spraying starts

Circulation spirally to

separating according to

braked after

haltingly after

Spray break necessary after duration

Max. spraying time after breaks until stopping again (sec) IO

Covering of grains ++

Contamination housing

Self-cleaning +

(++ very good, + good, - bad, -- very bad) Product samples:

Active ingredient content (%) 95-99 57-200 70-135

Single grains:

Active ingredient distribution CV (%) 12-14 >70 >

The experiments 1 A-C show the advantageous results of the coating when introducing the warm air for drying according to the measures for its control combined with the continuous container shape of the invention compared to the introduction of the warm air through the enlarged air gap in a discontinuous container shape according to the state of the art.

The jagged surfaces of beet seeds create a favorable internal friction between all the seeds. With even circulation, they can almost completely absorb the spray quantity and thus only slightly disturb the mixing and circulation.

The coating of constant grain volumes was all carried out in such a constant spray quantity per time that with the air quantity regulated according to the invention until a small amount of grain escaped, a spiral circulation was achieved at low temperature in the container of Example IA for the entire duration.

and no blockage has yet occurred, in order to make the negative effects of air being introduced through the annular gap in the container even clearer according to the state of the art. The air flow caused by the course of the coatings with the circulation and the covering of the grains as well as the container contamination

The qualitatively presented results therefore show uniform circulation and coating only in example IA. In contrast, the container shape and introduction of the annular gap air in examples IB and IC hinders circulation and leads to partial over-moistening of the circuit. The grains graze

floating and slightly mixed, the blockages lead to irregular coating and contamination. While the only slightly dirty container wall in Example IA cleaned itself after the next batch was filled,

0 the container had to be stripped after tests 1B and 1C,

washed and dried.
The quantitative uniformity of the coatings in Examples 1 AC is demonstrated by analyses of the active ingredient distribution in samples and within a sample at its individual grains. The active ingredient distribution of samples of the coated

Batches show the dosage or abrasion received. The coefficients of variation CV characterize their individual grain distribution. They are calculated from the total deviations of the active ingredient concentrations of all individually analyzed grains and relativized to their mean value. CV < 30% are considered

satisfactory, < 15 % as in Example 1 λ as good.

Poorer distributions with higher CV values, such as in examples 1 B and 1 C, contain many grains with too high and too low active ingredient concentrations. Plants germinating from them are phytotoxic or their protective effect is compromised.

The achieved active ingredient contents of the samples from 1 Λ, with the narrow range of 95-99% of the target dosage, demonstrate the lowest losses due to abrasion and contamination of the container. In contrast, samples from 1 B contain 57-200 % and from 1 C 70-135% of the target dosage, which is too little active ingredient if the grains are not covered properly or too much if they are over-moistened.

Example 2; for the device according to the invention in a rotor granulator (Fig.l) as in Example 1Λ, with the introduction of heated drying air without ring gap scent (2B) to promote the coating quality,

and with additional low compressed air through the narrow annular gap (2A),

compared to the state of the art with the introduction of heated low (2D) and increased drying air (2C) through an enlarged annular gap.

Test parameters:

Filling: 4 liters = 3 kg cabbage seeds (Brassica) Spraying: 216 g suspension as in example 1 Spray rate: 220 to 240 g/min with 2-material nozzle, diameter 2 mm, spray air pressure 1.5 bar

Rotor speed 300/min, drying air temperature 40 °C

Annular gap (mm) Air pressure (bar)

30 warm air (approx. mVMin)

Pressure loss (now WS)

2A 2 B 2C 2D 0.2 0.2 0.4 0.4 2 0 2 4 6 6 90 100

Test results: 2A 2B 2C 2 D After spraying starts,

Circulation spiral + -&igr;- -

separating - - + +

Blockage to (sea) - 30 40

Total spray time (lake) 60 55 55 58 Product samples

Active ingredient content (%) 85 87 88 86 Single grains Active ingredient -

Distribution CV (%) 22 35 102 104 Residual moisture of the grains

after spraying (%) 7.2 8.0 9.1 8.6

Examples 2 A-D with constant short coating time illustrate the advantages of an application using increased

Hot air supply through the integrated controlled fluidized bed (A ₁ B) of the invention compared to the prior art with low (C) or increased (D) introduction of hot air only through the enlarged air gap.

0 The smooth surfaces of the cabbage seeds cause little internal

Friction and therefore promote floating separation. They can also only sorb a small amount of suspension and therefore show in a qualitative assessment of the coating process in examples C and D an insufficient mixing circulation as well as partial blockages. They cause the rapid transfer

moistening of the grain surfaces, the higher residual moisture of the coated samples, and poor active ingredient distributions with CV around 100%. In contrast, a constant mixing circulation is achieved in example B solely by the drying air introduced in a controlled manner according to the measures of the invention.

This results in a satisfactory active ingredient distribution with CV 35%, which is improved to CV 22% with the additional low compressed air through the narrow annular gap in example Λ and with the lower residual moisture of samples Λ and B, the result of the evenly circulated circulation and dried

net coating.

The active ingredient contents of the samples are, however, almost identical in all examples. While the losses in examples C and D are due to the over-moistening and contamination of the container with suspension, in examples A and B they are due to

on the other hand, from the abrasion of the dried coating from the smooth grain surfaces. Stronger binding agents would provide a remedy, but without the fluidized bed of the invention, these would lead to even faster total blockage and were therefore not used for the sake of uniformity of the examples.

Example 3 with the device of the invention in a Roiorgranulatoi (Fig.l), like Examples IA and 2

Test parameters as examples 2 A-D, but:

Filling: 4 liters = 2.2 kg unpolished carrot seeds Spraying: 317 g suspension as in examples 1 and 2 Spray rate: approx. 240 g/min, nozzle/pressure as in example 2

Test results: 3�Lgr; 3B 3C 3D After spraying starts

Circulation spiral to (lake) 3 8

separating after (Sec) O 0

braked to (sea) 45 55

Total spray time (sec) 80 80 80 80

Product sampleii: 3 Λ 3B 3C 3D

Active ingredient content (%) 102 88 70 61 Individual grains:

Active ingredient distribution CV (%) 21 26 37 33 Residual moisture of the grains

after spraying (%) 10.8 11.0 13.1 12.7

The rough surfaces of the polished carrot seeds in Example 3 cause a more uniform internal friction of the circulation and sorb the suspension better than cabbage seeds in Example 2.

However, in examples C and D, their lighter weight also increases the disadvantages of drying out due to the enlarged annular gap. The portion of the grains that is separated as a result of this floating up is increasingly coated and thus over-moistened, as the higher residual moisture levels show.

The resulting higher losses of active ingredient from samples C and D with only 60 to 70% of the desired dosage also occurred as contamination of the container wall. The poorer active ingredient distributions with CV of 33 and 37% compared to examples A and B with 21 and 26 % show the disadvantages of the state-of-the-art process. The device of the invention, on the other hand, also leads to a high level of process reliability. Drying is ensured by monitoring and regulating the supply of hot air. If the control is faulty and the temperature drops, the spraying is reduced.

and thus over-moistening and sticking of grains or free powder particles is prevented. If the amount of warm air or the warm air temperature increases, the spray quantity is increased accordingly, thus maintaining the safe product temperature and humidity.

If the spraying is interrupted, the specified final value of humidity and temperature is maintained, as is the case with the final drying of the product.

exceeded and immediate emptying is initiated. The control conditions "final temperature/final moisture reached" and at the same time "total coating quantity not reached" from a suitable dosing scale allow the liquid batch to be discharged separately under alarm.

A technical effect of the device of the invention is the simultaneous introduction of an increased amount of drying air laterally through the ring screen surface in the deflection screen of the granulator according to the invention directly above the stator for the expansion of the circulating bed of coated grains as a fluidized bed. This arrangement of the ring screen surface promotes the drying, circulation and mixing of the grains in the bed through increased introduction of drying air, and these measures prevent disruptions to the circulation, sticking of the grains and uneven, necessarily interrupted or too slow coating. The tests in the examples show that only with the device of the invention, even with different cone properties, can the coatings be carried out in a short time with the required quality and operational reliability without blockages and the need for additional cleaning. Thanks to the measures disclosed, the temperature and thickness and thus the circulation and mixing of the grains remain constant throughout the entire coating process. The consistently uniform formation and the control measures allow the coating to be carried out with gentle and even circulation and simultaneous drying of all grains until they are completely covered with the quantities of the coating agent specified for the product. Even better distribution of the active ingredients on the individual grains can be achieved over a longer coating period by lowering the drying temperature.

Claims (9)

-H- S c h u t &zgr; a &eegr; s &rgr; ti c h e 1. Device for the uniform, closed coating of grains, such as seeds, with a rotor granulator with integrated fluid bed drying, characterized in that its rotor (1) has a cross section of Centre at an angle of up to 45°, preferably 30°, to the plane and is curved upwards at the outer circumference with a radius of about 10 to 20% of its diameter up to a contact angle of 45°, and with a slater (2) whose cross-section slopes outwards and upwards at the same Radius or parabolically retracted, arched up to the upper edge angle of 5° to 20", preferably 15°, inclined inwards to the vertical axis of rotation, and with a reversing mirror placed thereon at the same angle, characterized in that the reversing mirror (5) is thickly above the stator (2) a thin-walled, rotationally symmetrical ring screen or ring gap surface (9) with a large free passage, and that this is surrounded on the outside by a horizontal air channel (10) with feed pipes (11) attached tangentially to its outer circumference. -Ij- 2. Device according to claim 1, characterized in that the ring sieve or ring gap surface (9) has a height of about half to three quarters of the circulated bed (7), a wall thickness of 0.5 to at most 1.0 mm and a hole or gap width smaller than the smallest cone diameter. mcsser and has a free cross-section of 35 to 50%. 3. Device according to claims 1 and 2, characterized in that the air-permeable cross-sections of the air supply (l 1) and the ring channel (lO) are larger than those of the ring sieve or ring gap surface (9), and that the warm air (12) is thereby evenly dammed in front of the sieve surface (9) in the ring channel (10) without any loss of flow, and that the pressure increase and the pressure loss of the warm air (12) from the sieve (9) and the sieve (8) are monitored and regulated by a measuring device (13). 4 .. Device according to claims 1 to 3, characterized in that on the surface of the roller (l) there are some deflectors (6) made of elastic, smooth, abrasion-resistant material with a dune-like low cross-section and facing the direction of rotation are glued or embedded in a backwards bent manner, or that the deflectors (G) are slightly raised printed knobs on the surface of the roller (l). 5. Device according to claims 1 to 4, characterized characterized in that the edge of the roller (1) is conical downwards, and that from its edge to the stator (2) the annular gap (3) has a constant width of 0.1 to 0.2 mm, and from the pressure chamber (4) air flows through with a maximum of 2 bar pressure and is thus kept free of particles. 6. Device according to claims 1 to 5, characterized in that one or more nickel-plated nozzles (16, 16') are arranged at an angle of 15 to 45 degrees to the plane and also to the tangent in the direction of the circulating bed (8) tightly on the inner free or outer running on the stator (2). surface are arranged in a directed manner. 7. Device according to claims 1 to 6, characterized in that a sensor (15) for measuring the temperature and/or humidity of the exhaust air in the open interior space is mounted directly on the side is arranged above the surface of the bed (8) and serves to regulate the spraying and drying. 8 ·. Device according to claims 1 to 7, characterized in that below the height of the slats (2) one or several dosing devices (17, 17') open onto the inner free or compressed air-supported nozzles in the stator wall (2) onto the surface of the non-expanded zone of the bed (8) running along there. 9. Device according to claims 1 to 8, characterized in that a flap (16) fitted in the slat wall (2) is automatically operated by a suitable mechanism for emptying the coated and dried product, or that, alternatively, a suitable Swivel mechanism of the entire rotory silo just above its center of gravity and is emptied by tilting around the transverse axis thus formed.