JP4113746B2 - Spray drying / granulation method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spray drying and granulating method and apparatus.
[0002]
[Prior art]
Currently, the spray drying method and equipment are required for a high-purity product and a high-mix low-volume production method for products such as pharmaceuticals, fine ceramics, etc. Has increased.
[0003]
When producing high-purity products with a high-mix low-volume production method, it is necessary to frequently switch the varieties, so it is indispensable to quickly and completely clean the solid adhering to the walls of the drying chamber each time. Met. This means that it takes a long time for cleaning when efficiently producing a variety of products in small quantities, and if high purity and high quality are required for the product quality, the solid matter attached at the time of quality switching is removed. This is because it must be thoroughly cleaned.
However, it is extremely difficult to completely clean the solid adhering to the inner wall of the drying chamber, and furthermore, when the product is harmful to the human body, the product cannot be directly touched, so that the cleaning is extremely difficult.
[0004]
In addition, when there is a demand for production of high-purity products and high-mix low-volume production, the composition separation of products, which was not considered as a problem in the past, has become a problem due to the demand for high-purity products. .
[0005]
In order to solve the above problems, the present inventors, as an example of a spray drying apparatus, have a single bag-shaped or cylindrical heat resistance and good quality as shown in FIG. There has been proposed a spray drying method and apparatus which are formed of a peelable porous membrane so that dry exhaust gas passes from the inside to the outside of the spray drying chamber formed of the porous membrane (see Japanese Patent No. 1947599). As a result, fine powder with a small particle size is not entrained in the gas and discharged outside the device body as in the past, so composition separation does not occur, and frequent varieties associated with the high-mix low-volume production system When switching, it was possible to quickly and easily clean and remove the adhering fine powder, and as a result, it was possible to improve the quality and purity of the product fine powder.
[0006]
Further, the fine powder obtained by the spray drying apparatus is, for example, spray-dried with a slurry obtained by mixing water, a binder, or the like with the fine powder, so that it is excellent in moldability and fluidity and is a uniform spherical granulated powder. The spray granulation apparatus is used.
[0007]
Conventionally, the spray granulator has been installed separately from the spray dryer. However, when producing high-purity products in a space-saving and high-mix low-volume production method, the spray dryer is used as a spray granulator. As a result, in the case of products of the same quality, it is not necessary to completely clean the adhered solid content on the inner wall of the drying chamber, so that high-mix low-volume production can be performed efficiently.
[0008]
However, when the above-described spray granulation is performed with the spray drying apparatus shown in FIG. 5, the enclosed hot air passes from the surface of the porous film forming the spray drying chamber to the outside air. There is a problem that powder finer than the filtration size leaks to the outside, and the internal pressure of the spray drying chamber is likely to fluctuate due to adhesion of fine powder to the porous membrane, etc., so the internal pressure of the spray drying chamber can be held on the positive pressure side. It was indispensable in securing the volume of the spray drying chamber.
[0009]
This makes it difficult for swirling flow to occur in the spray drying chamber, and also tends to cause a temperature difference between the upper and lower sides of the spray drying chamber, so the residence time of the dried granulated material is short, and the moisture inside the droplets moves rapidly to the outside. Since it is in a rapidly dried state, there is a problem that voids are likely to be generated inside the dried product (granules) to be a product, and the bulk density is significantly reduced. In particular, in the case of powder having a high specific gravity or coarse particles having a size of 100 μm or more, the falling speed is high, and this tendency is remarkable.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of such problems of the prior art, and the object of the present invention is that composition separation does not occur at the time of spray-drying, and frequent varieties associated with a high-mix low-volume production system. Even when switching, the adhering fine powder can be washed and removed quickly and easily, and at the time of spray granulation, the residence time of the dried granulated product can be sufficiently secured. Even with coarse particles of 100 μm or more, the bulk density of the dried granulated product can be increased, and the yield decreases due to the adhesion of the spray particles to the drying chamber wall during spray granulation, and the adhered spray particles peel off. There is no generation of irregular shaped powder that occurs, and furthermore, spray drying process and spray granulation process can be performed in the same drying chamber in products of the same component system, so that space saving of the apparatus and quality improvement of the product, And to provide a spray drying and granulating method and apparatus which can contribute to purification.
[0011]
[Means for Solving the Problems]
That is, according to the present invention, there is provided a spray drying / granulation method capable of obtaining a powder in which solid particles are agglomerated by spraying and drying a solid particle dispersion solution in a spray drying chamber. The chamber is composed of a bag-like or cylindrical heat-resistant and well-peelable porous membrane, and at the time of spray drying, the solid particle dispersion solution is sprayed into the spray drying chamber, and the solid particle dispersion solution is heated with hot air. By removing the solvent and drying, and passing only the dry exhaust gas portion of the powder gas containing the powder in which the dried solid particles are aggregated, through the porous membrane constituting the spray drying chamber, The total amount of the powder can be obtained in the spray drying chamber, and at the time of spray granulation, the internal pressure of the spray drying chamber is changed from approximately 0 to a negative pressure while maintaining the volume of the spray drying chamber. And controlling the powder gas By pivoting in the drying chamber, spray drying and granulation method characterized by capable of granulating a powder of predetermined particle size are provided.
At this time, the internal pressure of the spray drying chamber at the time of spray granulation is preferably −200 to +20 Pa.
[0012]
Further, according to the present invention, the spray drying chamber formed of a single bag-shaped or cylindrical heat-resistant and well-peelable porous membrane and the predetermined shape of the spray-drying chamber are maintained substantially. A drying chamber holder, a sprayer for spraying the solid particle dispersion solution into the fine droplets in the spray drying chamber, hot air introducing means for introducing hot air to dry the micro droplets in the spray drying chamber, and the spray drying chamber The powder part in the powder gas is separated from the dry exhaust gas, the exhaust gas is exhausted to the outside of the spray drying chamber, the exhaust means detachably disposed in the spray drying chamber, and the pressure in the spray drying chamber Pressure adjusting means for adjusting, and at the time of spray drying, the dry exhaust gas is passed from the inside of the spray drying chamber formed by the porous membrane to the outside, and at the time of spray granulation, the exhaust means The internal pressure of the spray drying chamber is changed from almost 0 to a negative pressure by the pressure adjusting means. Spray drying and granulating apparatus according to claim is provided to control the.
[0013]
At this time, in the present invention, it is preferable that the side wall of the spray drying chamber is detachably disposed on the side surface of the spray drying chamber during spray granulation, and the drying chamber holder is the spray drying chamber. It is preferable to hold it detachably.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the spray drying / granulation method of the present invention, in the case of spray drying, the dispersion of solid particles sprayed by a sprayer is performed in a spray drying chamber formed of a bag-like or cylindrical heat-resistant and well-peeled porous film. Powder (fine powder) in which dried solid particles are aggregated by instantaneously heating and drying the solution (stock solution) with hot air at an inlet gas temperature (for example, 120 to 280 ° C.) blown from the hot air introduction means It becomes.
The powder largely sinks to the bottom of the spray drying chamber due to its own weight, and only the dry exhaust gas portion of the powder gas containing the powder is passed through the porous membrane constituting the spray drying chamber. Thus, the total amount of the powder can be obtained in the spray-drying chamber.
[0015]
At this time, the separation of the powder and the dry exhaust gas by the porous membrane is usually performed by passing a powder gas containing the powder through the fabric of the fibers constituting the porous membrane, so that only the powder in the powder is contained. A wide range of powders having a particle size of 0.1 μm to several mm can be separated.
[0016]
In the spray drying / granulation method of the present invention, when spray granulation is performed, the internal pressure of the spray drying chamber is controlled from almost 0 to a negative pressure while maintaining the volume of the spray drying chamber, In addition, by introducing the powder gas as a swirl flow, the residence time of the dried granulated product can be sufficiently secured, so even if the powder has a high specific gravity or coarse particles of 100 μm or more, The bulk density can be increased, and there is no reduction in yield due to the adhesion of spray particles to the drying chamber wall during spray granulation, and there is no generation of irregularly shaped powder caused by peeling of the adhered spray particles.
[0017]
Furthermore, the spray drying / granulation method of the present invention can perform the spray drying process and the spray granulation process in the same drying chamber in the same component-based product, thus saving the space of the apparatus and improving the quality of the product. It can contribute to high purity and high purity.
[0018]
Next, the spray drying / granulating apparatus of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a spray drying / granulating apparatus according to the present invention, and is a schematic sectional view showing an embodiment at the time of spray drying. FIG. 2 shows an embodiment at the time of spray granulation. It is a schematic sectional drawing.
As shown in FIGS. 1 and 2, the spray drying / granulating apparatus of the present invention is substantially spray-dried formed of a single bag-shaped or cylindrical heat-resistant and well-peelable porous film. Chamber 2, drying chamber holders 20, 22, and 24 that hold the predetermined shape of spray drying chamber 2, sprayer 3 that sprays the solid particle dispersion solution into the fine droplets in spray drying chamber 2, and spray drying chamber 2. The hot air introduction means 4 for introducing hot air for drying the microdroplets inside, the powder portion in the powder gas in the spray drying chamber 2 is separated from the dry exhaust gas, and the dry exhaust gas is exhausted outside the spray drying chamber 2. The exhaust means 40 is detachably disposed in the spray drying chamber 2 and has a pressure adjusting means (not shown) for adjusting the pressure in the spray drying chamber 2.
[0019]
Here, when spray drying, the spray drying / granulating apparatus of the present invention, as shown in FIG. 1, is a spray drying chamber formed of a bag-shaped or cylindrical heat-resistant and well-peeled porous film. 2, the solid particle dispersion solution (raw solution) sprayed by the sprayer 3 is instantaneously heated and dried by hot air having an inlet gas temperature (for example, 120 to 280 ° C.) blown from the hot air introducing means 4. A powder (fine powder) in which the dried solid particles are aggregated is obtained.
The powder largely sinks to the bottom of the spray drying chamber 2 due to its own weight, and only the dry exhaust gas portion of the powder gas containing the powder passes through the porous membrane constituting the spray drying chamber 2. By doing so, the total amount of the powder can be obtained in the spray-drying chamber.
In addition, when spray-drying, it is drive | operated so that the internal pressure of the spray-drying chamber 2 may be + 200- + 2000Pa.
[0020]
Further, when spray granulation is performed, the spray drying / granulating apparatus of the present invention, after switching from the first product recovery unit 16 (see FIG. 1) to the second product recovery unit 18, as shown in FIG. The exhaust means 40 is connected to the exhaust port 8 of the product recovery unit 18, and the internal pressure of the spray-drying chamber 2 is adjusted by the pressure adjusting means based on the measurement result of the differential pressure gauge 50 so that the internal pressure changes from approximately 0 to a negative pressure. By controlling, dry exhaust gas is introduced into the spray-drying chamber 2 as a swirl flow (see arrow in FIG. 2).
As a result, the dried granulated product and the sprayed granule fall slowly while being conveyed in the swirling flow of the dry exhaust gas, and are spray granulated while being in contact with the sprayed granule.
[0021]
Here, the spray drying chamber 2 is engaged with the holding frame 10 at the upper, middle, and lower portions of the spray drying chamber 2 by the drying chamber holders 20, 22, and 24 respectively disposed on the holding frame 10.
Thereby, even if it is a case where the inside of the spray-drying chamber 2 becomes a negative pressure, the spray-drying chamber 2 can be hold | maintained to a defined shape.
The spray drying chamber 2 is suspended from the inside of the holding frame 10 and can be moved up and down by an elevator 30.
[0022]
Moreover, it is preferable that the side wall 12 which suppresses passage of dry exhaust gas can be detachably arrange | positioned at the holding frame 10. FIG.
By making the side wall 12 have a heat insulating structure using a heat insulating material or the like, heat dissipation of the spray drying chamber 2 can be prevented, and a temperature difference between the upper and lower sides can be suppressed.
Thereby, since it is possible to prevent moisture inside the droplets from rapidly moving to the outside, the inside of the dry powder as a product can be made dense, and the bulk density can be improved.
[0023]
Although the atomizer 3 is not specifically limited, It is preferable to select and use the atomizer 25 (rotary spray disk) shown in FIGS. 1-2 and the spray nozzle 26 shown in FIGS.
In the case of the apparatus shown in FIGS. 3 to 4, the solid particle dispersion solution (raw solution) sprayed by the spray nozzle 26 is brought into countercurrent contact with the hot air blown from the hot air introducing means 4 in the spray drying chamber 2. Thus, heat can be exchanged efficiently.
[0024]
The exhaust means 40 includes a cyclone 42, a bag filter 44 and an exhaust fan (blower) 46. The exhaust fan (blower) 46 is controlled by the pressure adjusting means based on the measurement result of the micro differential pressure gauge 50 so that the internal pressure of the spray drying chamber 2 changes from approximately 0 to a negative pressure (preferably −200 to +20 Pa). ing.
[0025]
In the present invention, if the continuous operation is performed, the pressure loss increases due to the adhesion / deposition of the powder to the porous membrane, and the operation must be stopped at the end. Therefore, it is necessary to appropriately remove the powder. It is essential.
In the present invention, since the spray drying chamber is formed of a bag-like or cylindrical porous film having good peelability, the adhered powder can be quickly and easily caused by mechanical vibration or air injection (pulsed air) from the opposite side. The fine powder adhering to can be washed and removed.
[0026]
Further, in the present invention, since the spray drying chamber is formed of a bag-like or cylindrical porous film having good peelability, the spray drying chamber can be easily replaced, and is frequently associated with a high-mix low-volume production system. Switching between varieties and complete cleaning of the spray drying chamber can be performed easily.
[0027]
The porous film used in the present invention must be excellent in heat resistance and exfoliation from the powder.
That is, the hot air temperature introduced into the spray-drying chamber is usually about 120 to 280 ° C. at the inlet temperature and 70 to 150 ° C. at the outlet temperature. It is always easy to adhere and accumulate, and it needs to be well peelable for continuous use.
[0028]
Furthermore, the porous membrane used in the present invention separates the target powder from the dry exhaust gas.
The type of porous membrane having such a function is not particularly limited, but is usually a mesh-like (surface filtration) membrane having good releasability from powder and a heat resistant filter cloth (strength material) A combination membrane with a woven fabric or a non-woven fabric) is used.
Examples of the mesh film include polytetrafluoroethylene [PTFE] (trade name: Teflon) film, polytrifluoride ethylene film, and the heat-resistant filter cloth, for example, polyimide, heat-resistant nylon, polyester, Those made of aramid can be suitably used.
[0029]
【Example】
The present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
(Example)
After adjusting the slurry (slurry concentration: 65%) obtained by adding 2.0 mass% binder PVA (207) to the barium titanate material using the spray drying / granulating apparatus shown in FIG. Granulated powders were produced by spraying the slurry in the spray drying chamber 2 adjusted with the internal pressure of the drying chamber of 2.0 to +2.0 mmAq).
The hot air temperature was 200 ° C., the rotation speed of the atomizer 25 was 5000 rpm, and the slurry spray amount was 100 kg / hour.
Next, the relationship between the bulk density in the obtained granulated powder and the internal pressure of the drying chamber is shown in FIG.
Further, FIG. 7 shows the change over time in the single weight of the molded product (number of samples: 150) when the granulated powder having a bulk density of 1.53 kg / l was molded by rotary press.
[0030]
(Comparative example)
After adjusting the slurry (slurry concentration: 65%) in which 2.0% by mass of binder PVA (207) is added to the barium titanate material using the spray drying / granulating apparatus shown in FIG. The granulated powder was produced by spraying the slurry.
The hot air temperature was 200 ° C., the rotation speed of the atomizer 25 was 5000 rpm, and the slurry spray amount was 100 kg / hour.
Next, the relationship between the bulk density in the obtained granulated powder and the internal pressure of the drying chamber is shown in FIG.
Furthermore, the time-dependent change (number of samples: 250) of a molded object single weight when shape | molding by rotary press using the obtained granulated powder with a bulk density of 1.46 kg / l is shown in FIG.
[0031]
(Discussion)
As shown in FIG. 6, in an Example, by spraying a slurry in the spray-drying chamber 2 adjusted with the internal pressure of the drying chamber of -20- + 20Pa (-2.0- + 2.0mmAq), it is a comparative example. As compared with the above, the bulk density of the granulated powder can be improved and the bulk density of the granulated powder is significantly improved as the pressure in the spray drying chamber is reduced.
[0032]
Next, since the granulated powder obtained in the Examples has little change in single weight during continuous molding, it can be continuously molded without adjusting the molding conditions.
[0033]
【The invention's effect】
As described above, the spray drying / granulation method and apparatus of the present invention does not cause composition separation during spray drying, and can quickly and easily adhere fine powder even when frequently changing varieties associated with a high-mix low-volume production system. In addition, it is possible to increase the bulk density of the dried granulated product even when it is a powder having a high specific gravity or a coarse particle of 100 μm or more, and spray granulation. There is no reduction in yield due to spray particles sticking to the inner wall of the drying chamber at the time, generation of irregularly shaped powder caused by peeling of the fixed spray particles, and further space saving of equipment and higher product quality and purity. Can contribute.
[Brief description of the drawings]
FIG. 1 shows an example of a spray drying / granulating apparatus of the present invention, and is a schematic sectional view showing an embodiment at the time of spray drying.
FIG. 2 shows an example of a spray drying / granulating apparatus of the present invention, and is a schematic sectional view showing an embodiment at the time of spray granulation.
FIG. 3 is a schematic sectional view showing another embodiment of the spray drying / granulating apparatus of the present invention and showing an embodiment at the time of spray drying.
FIG. 4 is a schematic sectional view showing another embodiment of the spray drying / granulating apparatus of the present invention and showing an embodiment during spray granulation.
FIG. 5 is a schematic sectional view showing an example of a spray drying apparatus.
FIG. 6 is a graph showing the relationship between the bulk density of the obtained granulated powder and the internal pressure of the drying chamber.
FIG. 7 is a graph showing the time-dependent change in the single weight of the molded product (number of samples: 150) when the granulated powder having a bulk density of 1.53 kg / l obtained in Example is used to form by rotary pressing. .
FIG. 8 is a graph showing the change over time in the single weight of a molded body (number of samples: 250) when molded by rotary press using granulated powder with a bulk density of 1.46 kg / l obtained in a comparative example. .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Spray drying chamber, 3 ... Sprayer, 4 ... Hot-air introduction means, 6 ... Product outlet, 8 ... Exhaust port, 10 ... Holding frame, 12 ... Side wall, 14 ... Product recovery part, 16 ... 1st product recovery part ( (For spray drying), 18 ... second product recovery section (for spray granulation), 20, 22, 24 ... drying chamber holder (clamp), 25 ... atomizer, 26 ... spray nozzle, 30 ... elevator, 40 ... exhaust Means 42... Cyclone 44. Bag filter 46. Exhaust fan (blower) 50.

Claims (5)

A spray drying / granulation method capable of obtaining a powder in which solid particles are aggregated by spraying and drying a solid particle dispersion solution in a spray drying chamber,
The spray drying chamber is composed of a bag-like or cylindrical heat-resistant and well-peelable porous membrane,
At the time of spray drying, the solid particle dispersion solution is sprayed into the spray drying chamber, the solvent is removed from the solid particle dispersion solution with hot air and dried, and the powder containing the powder in which the dried solid particles are aggregated By passing only the dry exhaust gas portion of the gas through the porous membrane constituting the spray drying chamber, the total amount of the powder can be obtained in the spray drying chamber, and
At the time of spray granulation, the internal pressure of the spray drying chamber is controlled from almost 0 to a negative pressure while maintaining the volume of the spray drying chamber, and the powder gas is swirled in the spray drying chamber. A spray drying / granulating method characterized in that a powder having a predetermined particle diameter can be granulated. The spray drying / granulating method according to claim 1, wherein an internal pressure of the spray drying chamber at the time of spray granulation is -200 to +20 Pa. A spray-drying chamber formed of a substantially single bag-like or cylindrical heat-resistant and well-peelable porous membrane; and
A drying chamber holder for holding a predetermined shape of the spray drying chamber;
A sprayer for spraying the solid particle dispersion solution into fine droplets in the spray drying chamber;
Hot air introduction means for introducing hot air to dry the microdroplets into the spray drying chamber;
An exhaust means detachably disposed in the spray drying chamber for separating a powder portion in the powder gas in the spray drying chamber from the dry exhaust gas and exhausting the dry exhaust gas to the outside of the spray drying chamber;
Pressure adjusting means for adjusting the pressure in the spray drying chamber;
Have
At the time of spray drying, the dry exhaust gas is passed from the inside of the spray drying chamber formed by the porous membrane to the outside, and
At the time of spray granulation, the spray drying / granulating apparatus is characterized in that the exhaust means and the pressure adjusting means control the internal pressure of the spray drying chamber from almost 0 to a negative pressure. The spray-drying / granulating apparatus according to claim 3, wherein a side wall of the spray-drying chamber is detachably disposed on the side surface of the spray-drying chamber during spray granulation. The spray drying / granulating apparatus according to claim 3 or 4, wherein the drying chamber holder detachably holds the spray drying chamber.

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