JPS5826966B2 - Particle size adjustment method in continuous granulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the adjustment of the particle size value of produced particles in a continuous granulation method using a fluidized bed.

A continuous granulation method using a fluidized bed will be briefly explained using the system diagram shown in FIG.

1 is a granulation tank with a fluidized bed 5 for granulation in the lower part of the tank;
At the top there are a spray nozzle 2 for spraying the raw liquid material from the pump 6 and a spray nozzle 3 for spraying the binder from the pump 7.

The powdered raw material particles from the spray nozzle 2 and the binder from the spray nozzle 3 fall into a fluidized bed, and in the fluidized state, the powdered raw materials become cores and gradually increase the particle size, resulting in granulation. will be carried out.

9 is a fluidizing gas generation furnace, and this gas is fed into it from below the fluidized bed; 31 is a shifter that receives generated particles from the fluidized bed and sorts them according to particle size; and 16 is a fluidizing gas discharged. This is a cyclone for gas cleaning when

One of the characteristics of this continuous granulation method using a fluidized bed is that it has a high production rate of particles of a desired diameter.

In other words, the diameter distribution curve, ie, the distribution curve of the amount of particles relative to the particle diameter, has a sharp lognormal distribution with a peak at the required particle diameter.

This means that the fluidized bed must be able to adjust the particle size during the particle production process.

However, no technique for controlling particle size has been established to date.

For example, there is a method of controlling the amount of liquid material supplied by detecting the moisture content in the layer of a liquid material (r binder) added to powdered solid particles in a fluidized bed, but it has not yet been possible to achieve stable control over a wide range. , and is not suitable for large-capacity continuous granulation.

Moreover, the supply amount of binder can be controlled by timer or 0N-O.
The accuracy of FF control is even worse, and continuous operation may not even be possible.

In the present invention, this particle size adjustment is performed using two operating factors: (1) the difference between the fluidizing gas temperature and the temperature inside the fluidized bed, Δt (2);
This was determined by the binder spray flow rate F.

Figure 1 shows the device.

Here, 23 and 24 are controllers that indicate the feeding temperature of the fluidized bed 5 and the fluidizing gas, respectively, 25 and 26 are their detection ends, and 2T is an indicator of the temperature difference between the two locations and adjustment using this as a signal. The flow rate of the binder pump 7 is controlled by a meter, and 21 is a spray compressor connected to the binder spray nozzle 3.

An example of such a method and its effects will be described below.

This was carried out using a granulation tank with a diameter of 500M (Fig. 1) under the following conditions for microorganisms.

a) Raw material liquid material microbial cell slurry (water content 80 to 83% WB) b) Binder microbial cell slurry (water content 80 to 83% WB) C) Fluidization conditions air flow velocity in the bed in terms of empty column 110 = 1. 1 (m/se
c) d) Temperature in the fluidized bed 65 ('C) e) Fluidizing gas temperature 120 ('C) f) Temperature difference △t 55 ('C) Here, the conditions of C) to f) are based on the above operating factors. (1) is specified, and the above numerical values correspond to the curve mallow in FIG.

The results of the experiment conducted by changing the operating factors (1) and (2) are shown in the second
It is shown as the curves in Figures A-D.

Here, the numerical values of the operating factors are as shown in the following table, and the collapse curve is also in a stable state 20 hours after the start of operation.

Note that curve O shows that obtained by the conventional method.

Curve sign △t'CF (A/Hr) A 55 4 A 55 6 Curve sign △t'c F (n/Hr) C 5
8 4 Engineering 58 5 In other words, it can be seen that the operating factors (1) and (2) act as follows.

For example, if the operating factor (1) is Δt=55('C),
Compared to the shape of the diameter distribution when the operating factor (2) is F = 4 (A/Hr), the shape of the diameter distribution when F = 6 (l/Hr) shows that the amount of particles with a particle diameter of 500 to 999 [μ] has decreased. , particle size 210
The amount of particles of ~499 [μ] increases, forming a sharp peak, and tends to shift toward smaller particle sizes.

This tendency is the same when the operating factor (1) is Δt=58('C), and F=4(A/Hr') to 5(#/H
r ), the distribution shifts toward smaller particle sizes.

Also, change the manipulation factor (1) from △t=5!5('C) to △t=
When the temperature increases to 58 (° C.), the distribution shifts toward larger particle diameters, as can be seen from the comparison between curve A and curve A for F=4 (n/Hr).

In this way, as the value of Δ of the operating factor (1) increases, or as the F value of the operating factor (2) decreases, the particle size distribution in the fluidized bed shifts toward larger particle sizes.

The opposite is also true.

These two operating factors can be used independently or in parallel, but as an operation to increase the uniformity of particle diameters, one standard value is set for △t, and △t is smaller than this reference value. When the particle size is changed, set F to dog, and when it becomes small, set F to small, and when changing the particle size, set △ corresponding to that diameter.
It is effective to select a reference value for t.

By utilizing the granulation effect characteristics based on these operating factors as described above, the particle size distribution within the fluidized bed can be freely set, and a product with a desired particle size can be stably obtained.

The conventional method shown by curve O was carried out under the following conditions.

(a) Raw material microbial cell powder (b) Binder microbial cell slurry = (moisture content 80-83% WB) (c)
Fluidization conditions bed air column equivalent air flow velocity uo = 1.1 (m/5ec)
(a) Temperature inside the fluidized bed: 63°C (e) Temperature of fluidizing gas: 120°C This curve shows that the distribution range of particle diameters produced is wide and the production rate of particles of the required particle size is low.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a fluidized bed continuous granulation device using the method of the present invention, and FIG. 2 is a particle size distribution curve using the present invention and a conventional method. 1... Granulation layer, 2... Raw material spray nozzle, 3...
・Binder spray nozzle, 4... Current plate (for fluidizing gas), 5... Granulation fluidized bed, 9... Fluidizing gas generator, 21... Compressor, 23... Fluidized bed temperature Indicating controller, 24...Fluidization gas temperature indicating controller,
25...Fluidized bed temperature detection end, 26...Fluidized gas temperature detection end, 27...Temperature difference indicator between the fluidized bed and the fluidized gas.

Claims (1)

[Claims] 1. In the process of granulation using a fluidized bed, the difference between the temperature at which the fluidizing gas is introduced and the temperature inside the fluidized bed is detected, and the particle size of the generated particles is controlled by adjusting the binder spray flow rate based on this. Particle size control method in granulation.