JPH072210B2 - Granulation control method for hygroscopic powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention produces a granule or powder having a desired particle size by flowing a powder having high hygroscopicity and adding a binder solution to the powder. The present invention relates to a method for controlling a granulating device for the purpose.

[Conventional technology]

In the case of a fluidized bed granulator which fluidizes the raw material powder in a hot air stream and attaches and agglomerates the powder particles while adding the binder liquid to the fluidized bed, it is a powder that can maintain an appropriate fluidized state. The water content of the granules has a certain range depending on its properties, and when the water content exceeds the upper limit, the flow is rapidly slowed to form a lump. Further, when the water content increases, the flow stops and the powder and granules are solidified into agglomerates, which makes the operation of the granulator impossible.

In the conventional granulating apparatus of this type, a method of detecting the exhaust temperature or the exhaust humidity to control the hot air temperature or the addition rate of the binder is used, and in the case of the batch system, the hot air temperature and the air volume are kept constant. A common method is to set a binder addition time with a timer while controlling. On the other hand, in the granulation operation of hygroscopic powder, the range of water content that can maintain proper flow is very narrow. For example, in the case of amino acid-containing seasonings, this upper limit is about 3% DB, and in the case of powdered soy sauce, it is 5%. It is about% DB, and when the water content exceeds this value, the flow state deteriorates rapidly and the flow stops in an extremely short time.

[Problems to be solved by the invention]

In the conventional control method of the granulating apparatus as described above, such a minute change in water content cannot be detected as a change in exhaust temperature or humidity, and in the case of batch operation, the back filter built in the main body is used. Since the amount of hot air supplied is not constant due to clogging, etc., it is possible to avoid the risk of the powder and granules inside the equipment clogging and clogging due to operations such as adding binder liquid and repeating intermediate drying. For this reason, it was inevitable to operate it with a considerably low water content.

As described above, since the conventional method cannot detect an increase in the water content that causes poor flow, the flow state must always be visually monitored, and the water content must be observed at a low level. However, there is a problem that the particle growth rate is slow, and accordingly, a long granulation time is required, and it is difficult to improve the product yield for a desired particle size.

The present invention has been made to solve the above problems, and by controlling the water content of the granulated material, poor flow of the granulated material does not occur during operation, and the particle size is stable in continuous operation. It is an object of the present invention to provide a method for controlling granulation of hygroscopic powder, which is capable of obtaining the above product, shortening the granulation time, and improving the product yield.

[Means for solving problems]

The granulation control method according to the present invention, the moisture content of the granulated material in the flow by the infrared moisture meter attached at a proper position of the flow chamber through the detection tube, without contacting while sending air from the detection tube. Direct and continuous detection with high accuracy, and based on this detection value, through the moisture controller, adjust the rotation speed of the binder supply pump to increase or decrease the binder addition speed, etc. The water content is controlled.

[Action]

In the present invention, since the flowing granules are continuously maintained at an appropriate water content, the generation or flow of agglomerates in the granules during operation may be stopped and solidified. There is no. Further, the growth time of the particles to obtain a uniform particle size, that is, the control of the rate of increase of the water content of the granulated material during the granulation operation, and the water content at the end of the granulation operation to obtain the desired average particle size. Perform rate control accurately.

[Embodiment] FIG. 1 is a schematic view showing the overall structure of a hygroscopic powder granulating apparatus according to an embodiment of the present invention, and (1) shows a granulating apparatus for accommodating and treating a granulated object. The main body, (2) is a binder liquid spray nozzle, (3) is an infrared absorption moisture meter, and a detection tube (4)
The water content of the powder or granules flowing in the granulator main body (1) during the granulation step is continuously detected without contact. (5) is a moisture controller that operates according to the output signal detected by the absorption moisture meter (3) to infrared rays, (6) is a speed setting device that is set by the control output of this moisture controller,
Reference numeral (7) is a binder supply pump that operates according to the setting of the speed setting device (6), which increases or decreases the supply amount of the binder liquid to the binder liquid spray nozzle (2). (8) is a blow-in fan that takes in external air and blows it to the heat exchanger (9),
(10) controls the amount of steam supplied to the heat exchanger (9) by detecting the outlet temperature of the heat exchanger (9) and operating the control valve (11) by the output signal according to the deviation from the setting. Temperature controller, (12) is a hot air chamber to which hot air from the heat exchanger (9) is fed from an opening provided in the lower part of the granulator main body (1), and (13) is this hot air chamber (12). ) And a fluidized granule, which is provided with a large number of holes penetrating the granulated material, (14) collects fine powder scattered from the inside of the granulator main body (1) and again in the fluidized bed. A back filter (15) for discharging the air to the outside is an exhaust fan for discharging the air cleaned by the back filter (14) to the outside.

FIG. 2 is a sectional view showing the details of the infrared absorption moisture meter (3), the detection tube (4) and the mounting portion of the granulator main body (1) to which they are mounted in FIG. ,
(4a) is a main purge pipe, (4b) is a sub-purge pipe, and purge air is supplied from an air source (not shown).

In the granulation control device according to the present invention having the above-described structure, as shown in FIG. 2, the granulation device is passed from the hot air chamber (12) through a large number of through holes (13a) provided in the gas dispersion plate (13). Hot air of a predetermined temperature adjusted by the temperature controller (10) is pressure-fed into the flow chamber (1a) of the main body (1) into the flow chamber (1a) of the main body (1) of the granulating device, and the hot air inside Keep the granulate in a fluidized state. On the other hand, the purging air supplied from the main purge pipe (4a) provided in the detection tube (4) passes through the detection tube (4) and enters the above-mentioned flow state in the vicinity of the opening of the granulator main body (1). In order to spray the granules that have been ground, the powder and granules move substantially along the opening without entering the detection cylinder (4). Further, the air for purging from the sub-purge pipe (4b) eliminates the powder or granules that tend to adhere to the bottom of the detection pipe (4).

Therefore, since the infrared absorption moisture meter (3) apparently maintains a constant state even when the powder or granule is flowing, it is irradiated with infrared rays to emit light according to the water content of the measured object. Energy is absorbed by the object to be measured, and the requirement as a measuring surface for measuring the amount of attenuation of light reflected and returned comes to be satisfied. That is, the condition that the measurement distance is constant and the surface to be measured is stable, which is necessary for the measurement of the infrared absorption moisture meter, can be satisfied by the action of the purge air even in the case of flowing particles.

Under the above stable measurement conditions, the moisture content of the granulated substance detected by the infrared absorption moisture meter (3) is converted into a predetermined signal and input to the moisture controller (5), The speed setter (6) is actuated by the amount of deviation from the detected water content with respect to the desired set value according to the type of granulated material, and is determined by the output of this speed setter (6). The binder liquid spray nozzle (2), in which the binder liquid supply pump (7) rotates, that is, the flow rate of the binder liquid and the atomizing air are mixed and atomized.
The granules are granulated while being sprayed to flow the granules at a predetermined temperature and water content.

Experiments were carried out on fluidized bed granulation of hygroscopic powders such as powdered soy sauce and amino acid-containing seasonings by the granulation control method according to the present invention described above, and as a result, the growth rate of particles was Regardless of the amount of solid content in the solution,
It depends only on the water content of the powder. The amount of solid content in the added binder liquid affects the strength of the particles, and if the amount of addition is small, the ratio of pulverization during finish drying increases. Therefore, for example, the particles after finishing drying are sieved with a sieve of 100 mesh, and the yield of the particles on this sieve is compared. The yield of the product is better when the granulation operation is performed by the above method. It was possible to understand the correlation between the above granulation conditions and the results.

That is, by appropriately setting the water content of the powder at the end of the addition of the binder or the rate of increase of the water content at the time of the addition of the binder, the product particle size can be arbitrarily controlled, and accordingly, the desired particle size can be obtained. It was found to be obtained with an increased yield of diameter product.

FIG. 3 and FIG. 4 are diagrams showing the experimental results based on the above-mentioned examples in the batch type granulator, and FIG. 3 shows an operation example of powdered soy sauce, in which the amount of binder liquid added is the same. In the diagram comparing the yields of the granules on the 100 mesh sieve when only the operation moisture content was changed, a clear correlation was shown between the water content and the yield on the 100 mesh sieve. By increasing the water content by 2% DB, the yield could be improved by 35%.

Fig. 4 shows an operation example of an amino acid-based seasoning, in which the conventional method and the method according to the present invention are used for the granulation and water content, and the yield of the granulated material on a 100 mesh screen, respectively, on the abscissa. By setting the water content at the end of the operation to 2.8% DB just before the flow failure, the operation time and the addition amount of the binder solution can be reduced to about 1 / compared with the conventional method. It was reduced to 2, but conversely the yield on the 100% sieve was 18%.
I was able to improve.

The operating conditions in the above experiment are as follows.

Equipment used: Batch type fluid bed granulator (built-in stirrer) Fluidized bed area: 0.2m ² Hot air temperature: 80 ℃ Fluid air speed: 0.82m / sec Binder: 2.0% potato starch Binder speed: (Conventional method ) 1.0-48 minutes, 70 g / mm for 5 minutes spraying, 1 minute intermediate drying (cycle spraying) 2.48-60 minutes, 110 g / mm (continuous spraying) (method according to the invention) 1. Maximum binder addition rate 110 g / mm 2. Moisture controller setting 2.8% DB In the above example, an example in which hot air is blown from the gas dispersion plate (13) provided in the lower part of the granulator main body (1) to flow the granules will be described. However, even when the granulated material is fluidized by a mechanical stirrer or the like provided in the granulator main body (1), the same effect as that of the above-described embodiment can be obtained.

〔The invention's effect〕

As described above, the present invention detects the water content of a flowing granulated substance directly and continuously with high accuracy by an infrared absorption moisture meter, and based on the detected value, the granulated substance during granulation While maintaining the state of water content appropriate for the granules, it was configured so that the rate of increase of the water content can be freely controlled, so that the desired particle size can be obtained by continuous automatic operation without obstructing the flow state. The product can be stably obtained, and in addition to shortening the granulation time, the product yield can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram schematically showing an apparatus according to a granulation control method according to an embodiment of the present invention, and FIG. 2 is a detailed view of a main part of a moisture content detection unit in FIG. 1, FIG. 3 and FIG. FIG. 4 is a diagram showing experimental results according to the present invention. In the figure, (1) is the granulator main body, (1a) is the flow chamber,
(1b) is an opening, (2) is a binder liquid spray nozzle, (3)
Is an infrared absorption moisture meter, (5) is a moisture controller, (6) is a speed setting device, (7) is a binder supply pump, (8) is a blowing fan, and (10) is a temperature controller. The same reference numerals in the drawings denote the same parts.

Claims (1)

[Claims] 1. An agglomerate contained in a fluidized chamber is fluidized by means of compressed air or a stirrer, and a binder is added to the fluidized agglomerate to aggregate / granulate the powder particles. In the method, the moisture content of the fluidized granulated product is directly and continuously contacted with air by the infrared absorption moisture meter attached to the flow chamber through the detection tube while pressure-feeding air from the detection tube. Detected, and through the moisture controller based on this detected value, by adjusting the speed of the binder supply pump, the addition rate of the binder solution from the binder solution spray nozzle is increased or decreased to the above water content ratio. Characterized by obtaining granules or powders having a desired particle size while maintaining the value of the above-mentioned water content so that the granulation rate of the particles closely related to each other is most efficiently obtained and the granulation proceeds in a short time. Granulation control method for hygroscopic powder.