JPH0613091B2 - Spray drying fluidized granulation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a spray drying method in which a fluidized granulation apparatus is incorporated in one tank.

[Prior art and its problems]

Conventionally, an apparatus has been used in which a raw material powder is supplied and a binder liquid is sprayed in a fluidized tank to continuously produce a granulated product, but granulation is performed by utilizing the agglomeration phenomenon of the powder moisture. Therefore, the range is said to be 5 to 15% in the case of a relatively wide range such as granulation of powdered milk, and 5 to 8% in the case of amino acid-containing substances such as soy sauce and various extracts. However, in an actual device, if the moisture (moisture) is low, the progress of granulation is slow, and if the moisture is high, the device may adhere or form a dumpling, and the appropriate range is very narrow.
The milk powder content is within a few percent and the amino acid-containing material content is within 1%, and a high degree of control is required.

Further, as a method of producing a granulated product from a liquid raw material, a combination of a spray drying device and a fluidized granulation device is considered, and the following two types of devices have already been proposed, but they have some problems. .

As one of them, FIG. 4 shows a spray-drying apparatus in which a fluidized bed section is built in one tank. However, this known one
Since the spray drying nozzle n also functions as a binder spray nozzle for fluidized granulation, the water content of the dried product cannot be sufficiently lowered during spray drying. This is because the fluidized granulation cannot be granulated unless the dried product contains a certain amount of water. (In FIG. 4, each reference numeral is the same as that in the embodiment of the present invention.) Therefore, the relationship of the arrangement between the spray drying unit 2 and the fluidized granulation unit 3, the spray angle of the nozzle, and the spraying are performed. The optimum range is remarkably narrow due to the complicated selection of liquid viscosity, concentration, drop diameter, temperature and flow rate of hot air and flowing air.

Since the spray-dried dried product is in a so-called incompletely dried state as described above, its dried particles easily adhere to the inner wall of the tank, causing thermal denaturation or increased adhesion, which makes operation impossible. The problem remains.

Further, the degree of granulation was almost determined under the drying conditions, and it was impossible to control the size of the granulated particles to be large or small.

On the other hand, as shown in FIG. 3, a spray dryer X and a fluidized granulator Y provided in separate tanks have already been used. However, this conventional device requires high equipment cost and running cost. In FIG. 3, O is a product outlet.

Further, in the spray drying apparatus, in order to transport it to a subsequent apparatus, it must be sufficiently dried, and in many cases, the exhaust temperature and the humidity inside the tank must be lowered. For this reason,
It is necessary to supply the secondary cold air Z into the tank, and the auxiliary equipment such as a blower and a wet scrubber that has a large capacity is required as a post-treatment equipment for introducing the secondary cold air.

Further, since the fluidized granulation device is provided with the bag filter device F, the detergency is deteriorated.

On the other hand, JP-A-55-111834 and JP-A-55-11
As in No. 1833, a continuous granulating apparatus in which a stock solution spray nozzle, a binder spray nozzle, and a fluidized bed are contained in one tank has already been proposed.

However, in this prior art, the stock solution sprayed from the stock solution spray nozzle is dried by the hot air from the fluidized bed, so the stock solution reaches the binder nozzle without being sufficiently dried. Therefore, it collides with the rising hot air from the fluidized bed and diffuses, and a large amount of undiluted solution particles adhere to the inner wall of the tank. Further, the undiluted solution from the actual solution nozzle disturbs the granulation action below the binder nozzle, and significantly impairs the granulation efficiency.

[Means to solve the problem and its action]

In order to solve the above-mentioned problems of the prior art, the present invention comprises a spray-drying unit 2 including a cylindrical portion 2a for drying the stock solution sprayed from the stock solution supply sprayer 4 in the upper part of the tank with hot air and a cone part 2b arranged therebelow. The nozzle 5 for spraying the binder liquid in the lower part of the tank and the fluidized granulation part 3 having the fluidized bed 3a on the bottom surface are formed, and the spray drying part 2 is positioned near the upper end of the cone part 2b for drying. Using the hot air and the spray drying fluidizer provided with the granulation air discharge port 8, the hot air supplied to the spray drying unit 2 is supplied from above the spray drying unit 2 and descends in the tank.
Before reaching the fluidized granulation section 3, the stock solution is separated from the dried particles and discharged from the hot air and granulation air outlet 8 to the outside of the tank, while flowing to the fluidized granulation section 3 from the fluidized bed 3a. The layer granulation air is supplied, and the dry particles separated from the hot air are granulated with the binder liquid. On the other hand, the granulation air together with the dry hot air falling from the spray-drying unit 2 is hot air and the granulation air discharge port 8 It is an invention of a spray-drying fluidized granulation method in which the powder is discharged from the tank to the outside of the tank.

According to the present invention, the dry hot air falling from the spray drying section 2 does not reach the fluidized granulation section 3 by the above method. Therefore, the binder liquid in the fluidized granulation section 3 can be granulated without being affected by the dry hot air in one tank, and thus sufficient granulation efficiency can be ensured.

Further, fine particles of the undiluted solution do not adhere to the wall surface in the tank.

And the binder for fluidized granulation of the present invention, starch,
In addition to dextrin, HPC, CMC, MC, etc., water or undiluted solution (co-liquid) used for spray drying is used. Especially for powdered milk and amino acid-containing products, the co-liquid is preferably used to reduce heat energy. Measured.

Further, the degree of granulation can be adjusted by adjusting the amount and concentration of the binder added and adjusting the residence time in the fluidized granulation section.

[Explanation of Examples]

 Examples of the present invention will be described below.

In FIG. 1 and FIG. 2, 1 indicates the whole device of the present invention,
The upper part is the spray-drying unit 2, and the lower part is the fluidized granulation unit 3. The spray-drying unit 2 is composed of a cylindrical portion 2a and a cone portion 2b. 4 is, for example, a pressure nozzle, a two-fluid nozzle,
A stock solution sprayer such as a rotary disk sprayer, and 5 are granulation binder solution supply nozzles such as a two-fluid nozzle. 6 is a hot air blower for spray drying, 7 is a blower for fluidized bed air, 8 is a hot air outlet from the spray drying section 2 and the fluidized granulation section 3, and the cone section 2b is provided at the lower end of the cylindrical section 2a of the spray drying section 2. It is annularly arranged at the upper end of.

9 is a first cyclone that collects fine powder from hot air exhaust,
The fine powder product recovered by the first cyclone is returned to the fluidized granulation section 3 from the recovered fine powder supply port 15. Reference numeral 9a is an exhaust fan of the first cyclone 9.

Reference numeral 10 denotes a drying and cooling device for the product taken out from the fluidized granulation section 3, and a well-known horizontal fluidized drying device is used as an example thereof, and hot air 11 and cold air 12 are blown from the lower surface of the floor surface 13.

Reference numeral 14 is a second cyclone for treating the exhaust of the product drying / cooling device 10, and the exhaust is combined with that of the first cyclone 9 and discharged to the outside of the system. Further, the fine powder product recovered by the second cyclone is returned to the recovered fine powder supply port 15. 1
As mentioned above, 5 is a recovery fine powder supply port.

The operation will be described below.

First, in the spray drying unit 2, the stock solution is atomized from the stock solution supply nozzle 4, and the droplets are dried by the hot air blown from the hot air blower 6 to become fine powder. Then, while the fine powder is being dried, it descends the cylindrical portion 2a and reaches the cone portion 2b. The hot air for drying is discharged to the outside from the hot air outlet 8, and as shown in the examples described later, the dried material does not need to maintain a water content of about 7%, for example, and the dried particles are about 4% which is easy to handle as powder. And dried. This means that the degree of dryness of the particles to be fluidized and granulated can be markedly higher than that of the conventional fluidized bed built-in type granulation method shown in FIG. Helps prevent the adherence of.

Next, in the fluidized granulation unit 3, the granulating binder liquid is sprayed from the granulating binder liquid supply nozzle 5 to granulate. In this case, the granulation degree can be appropriately changed by changing the supply rate of the granulating liquid.

The granulation air from the fluidized granulation section is exhausted from the hot air outlet 8. FIG. 6 shows the above state, where h is dry hot air, m is air for granulation, g ₁ is dry particles, and G ₂ is granulated particles.

Regarding the granulation of the amino-containing raw material, the experimental results comparing the conventional spray dryer with a fluidized bed using the binder liquid nozzle for granulation shown in FIG. 4 and the method of the present invention will be described below.

As shown in FIG. 2, the apparatus used for this comparative experiment uses a tank having a diameter of the cylindrical portion 2a of 2200 mm, a height of the cylindrical portion 2a of 3000 mm, and a height of the cone portion 2b of 1900 mm. Comparison was made between the case where the nozzle 5 was used (the present invention) and the case where the nozzle 5 was not provided (conventional example).

Conventional example: Spray drying unit 2 Hot air inlet temperature T ₁ : 200 ° C. Outlet temperature T ₂ : 95 ° C. Undiluted solution supply rate: 30 kg / h Undiluted solution concentration: 40% Moisture at the end of drying: 5-7% Fluid granulation unit 3 temperature wind inlet temperature T _3: 70 ° C. outlet temperature T _4: 60 ° C. in a fluidized bed granulating binder solution feed rate: without supplying granulation liquid temperature without supplying fluid tank water: about 4% for the present invention: spray drying Part 2 hot air inlet temperature T ₁ : 210 ° C. outlet temperature T ₂ : 95 ° C. undiluted solution supply rate: 30 kg / h undiluted solution concentration: 40% moisture at the end of drying: about 4% fluidized granulation part 3 warm air inlet temperature T ₃ : 85 ° C. Outlet temperature T ₄ : 50 ° C. Binder liquid supply rate for fluidized granulation: 1.8 kg / h Granulating fluid temperature: 40% Moisture in fluidized tank: Approx. 4% In the above experimental results, the average particle diameter in the case of the conventional example 100-1
Granules of 50 microns could be collected, but the collection rate is about 30
%, And the remaining about 70% of the raw material adhered to the cone portion and the fluidized bed upper portion and could not be recovered. The recovery rate under other conditions was even worse. On the other hand, in the case of the method of the present invention, the dried product hardly adheres to the lateral wall surface and the average particle size
A 0 micron granulated product could be obtained with a recovery rate of about 90%.

Further, by reducing the binder flow rate, it was possible to obtain a granulated product having an average particle size of 100 microns with a recovery rate of about 90%.

As shown in FIG. 5, in the method of the present invention, a rotary stirrer 16 may be provided in the fluidized granulation section 3 to crush large granulated particles to obtain granulated particles having a more uniform particle size.

[Effects of the Invention] Since the fluidized granulation section 3 is provided with the fluidized granulation nozzle 5 separately from the stock solution supply sprayer 4, the fine particles of the stock solution are incompletely dried in the spray drying section cone section 2b in a high-moisture state. There is no need to leave it. Therefore, the fine particles are dried in a wide drying range, do not adhere to the wall surface in the tank, and are granulated with the binder liquid in the fluidized bed granulation section in the next stage.

Therefore, the recovery rate of the granulated product can be improved.

The granulation degree in the fluidized granulation section 3 can be adjusted independently of the drying section in the upper part by adjusting the supply rate of the binder liquid for granulation.

In the method of the present invention, the temperature of exhaust gas can be lowered as a whole and the temperature of hot air can be raised, so that a large granulated product can be produced with a small amount of heat energy. Further, unlike the granulator separate type, it is not necessary to completely dry fine powder with a spray dryer, and secondary cold air is not required.

Even if the raw material has a narrow moisture range and is suitable for granulation such as amino acid-containing material, continuous granulation can be performed under relatively wide operating conditions.

Before the hot air reaches the fluidized granulation section, it is discharged out of the tank at least near the upper end of the cone section 2b of the spray drying section 2 above the fluidized granulation section 3, and the stock solution is separated from the dried dry particles. It does not coexist with the air for fluidized bed granulation of the granulation section 3. Therefore, the fluidized granulation section 3 can replace the optimum amount and temperature of the granulating air for the granulation with the binder liquid and the water content of the highly dried dry particles with the optimum quality and amount of the binder liquid. Thus, the most efficient granulation can be performed regardless of the inside of one tank.

[Brief description of drawings]

FIG. 1: Flow sheet drawing of the method of the present invention. FIG. 2: Cross-sectional view of the method of the present invention compared with a conventional example. FIG. 3: Skeleton diagram of a conventional example (separated granulator). FIG. 4: Conventional example. Skeleton diagram of (spray dryer with fluidized bed), Fig. 5: Another embodiment of the device of the present invention provided with a rotary disk sprayer and a rotary stirrer. Fig. 6: Explanatory diagram showing the action of the method of the present invention, 1: Apparatus for carrying out the method of the present invention, 2: Spray drying section, 2a: Cylindrical section 2b: Cone section, 3: Fluidization granulation section, 3a: Fluidized bed, 4: Stock solution supply sprayer, 4a: Stock solution 5: Binder for granulation Liquid supply nozzle, 5a: binder liquid, 6: hot air blower for drying, 7: fluidized bed air blower, 8: hot air outlet for drying, 9: first cyclone, 10: product take-out tank 11: hot air blower for product recovery , 12: Cold air blower for product recovery, 13: Floor surface, 1 : 2nd cyclone, 15: recovery dried material supply port, 16: rotary agitator (Fig. 5) n: spray drying nozzle (Fig. 4) o: product outlet, F: bag filter device (Fig. 3) h : Hot air (Fig. 6), m: air for granulation (Fig. 6), g ₁ : dry particles, G ₂ : granulated particles.

Front page continuation (72) Inventor Masaaki Okawara 3847 Ikebe-cho, Midori-ku, Yokohama-shi, Kanagawa Okawara Kakoki Co., Ltd. (56) Reference JP-A-55-111833 (JP, A) JP-A-55-111834 ( JP, A)

Claims (6)

[Claims] 1. A spray-drying section 2 comprising a cylindrical portion 2a for hot-air drying a stock solution sprayed from a stock solution supply sprayer 4 and a cone section 2b arranged below the tank, and a binder solution at the bottom of the tank. A spraying nozzle 5 and a fluidized granulation part 3 having a fluidized bed 3a on the bottom surface are formed, and the hot air for drying and the granulation air discharge port 8 are located near the upper end of the cone part 2b of the spray drying part 2. The hot air supplied to the spray drying unit 2 is supplied from above the spray drying unit 2 and descends in the tank to dry the stock solution before reaching the fluidized granulation unit 3. Separated from the dry particles, the hot air and the air for granulation 8 are discharged to the outside of the tank, and the fluidized granulation section 3 is supplied with air for fluidized bed granulation from the fluidized bed 3a to separate from the hot air. Dry particles are granulated with binder liquid, while granulation air is atomized A spray-drying fluidized granulation method, characterized in that hot air and granulation air outlet 8 are discharged to the outside of the tank together with the dry hot air falling from the drying section 2. 2. The spray drying fluidized granulation method according to claim 1, wherein the stock solution supply sprayer 4 is a pressure spray nozzle. 3. The spray drying fluidized granulation method according to claim 1 or 2, wherein the stock solution supply sprayer 4 is a two-fluid spray nozzle. 4. The spray drying fluidized granulation method according to any one of claims 1 to 3, wherein the stock solution supply sprayer 4 is a rotary disk type sprayer. 5. The spray drying fluidized granulation method according to claim 1, wherein the fluidized granulation section 3 is provided with a rotary stirrer. 6. The spray-drying fluidized granulation method according to claim 1, wherein the nozzle 5 for supplying the binder liquid for granulation is a two-fluid spray nozzle.