유동층 상압 건조법에 의한 실리카 에어로겔 분말의 합성 및 최적화 연구

Abstract

To overcome the problems in the large-scale and cost effective production of silica aerogel powders, the present research was carried out using a cheap precursor, such as water glass, through via fluidized bed drying instead of via furnace drying. The optimum conditions on dropping time of chemicals fed and spindle rotational speed in the synthesis of hydrogel were 10sec and 250～300rmp, respectively. Silica aerogel powders with low tapping density could be easily synthesized and bring about reduced drying time with dehydration process. The effects of various fluidized bed drying parameters, such as bead/gel ratio, bead size, superficial gas velocity and bed temperature, on the physical properties and yield of aerogel powders have been investigated in terms of tapping density and yield of silica aerogel powders obtained. The silica aerogel powders with tapping density of 0.08～0.09g/cm3 and yield as high as 90% have been synthesized by systematic optimizations of the fluidized bed drying parameters; bead/gel weight ratio of 3～5, bead size of 0.2mm, superficial gas velocity of 3.3×10-2Nm/s, and bed temperature of 200℃. We anticipate that the optimization study will do much for solving the problems in the continuous production of silica aerogel powders.