答案:压降大,有效湿容量低。High pressure drop and low effective wet capacity主要成分为SiO2,颗粒状硅胶有坚硬的玻璃状的外表。Mainly composed of SiO2, granular silica gel has a hard glass appearance适当的条件下,可使气体露点达-60℃~-70℃。Under appropriate conditions, the dewpoint of gas can reach -60℃ ~ -70℃对极性物质的选择性很强。Strong selectivity to polar substances