噴霧乾燥造粒品の強度に及ぼす湿度の影響
1987 年 24 巻 9 号 p. 582-587
詳細
1987 年 24 巻 9 号 p. 582-587
A slurry feed composed of water, PVA and fine particles are sprayed in droplet form into a spray dryer, and the porous and spherical spray-dried products are recovered. However, the PVA binder is so hygroscopic that the strength of the products changes with relative humidity.
For the purpose of clarifying this phenomenon quantitatively, the specific surface area, hygroscopic moisture content and strength of the spray-dried products are examined experimentally and theoretically.
The conclusions obtained are summarized as follows:
1. The hygroscopic moisture content of the products is estimated by the total of the moisture adsorbed on the surface of constituent fine particles covered somewhat with PVA and the moisture adsorbed by PVA itself.
2. The strength of the products is measured under various conditions of relative humidity. The measured values are compared with the results calculated from the previously derived equation. As a result, it is found that the strength of the products can be estimated well by taking account the effect of the variation in humidity on binder strength in the derived equation.
