Flexible Aerogel Blanket in Cryogenic Applications
While cryogenic applications comprise only a small part of the industrial insulation market, insulating cryogenic piping and equipment presents particular technical challenges not seen in above- or below-ambient applications. The temperature threshold for cryogenic temperatures is generally accepted as being at or below -100° F. (-74° C), while absolute zero—the theoretical temperature at which molecular motion comes most closely to ceasing—marks the effective lower boundary at -460° F (-273° C).3 The extreme temperature differential (ΔT) between normal ambient conditions (T1) and piping and equipment (T2) operating at cryogenic temperatures presents 3 primary challenges to any insulation: extreme heat transfer requiring significant insulation thickness, strong vapor drive to the cold face, and significant contraction within the vessel or piping containing the cryogenic liquid. These performance demands limit the number of suitable insulation materials. Flexible aerogel blanket, however, is suited to match these challenges.
ASTM C1728-13 provides 3 classifications for flexible aerogel blanket, distinguishing aerogel blanket by Type as determined by maximum use temperature, with further distinction by Grade and Category as a function of the thermal conductivity test configuration and respective thermal conductivity results. For cryogenic service, ASTM Type I, Grade 1, Category B blanket is recommended. This aerogel blanket is commonly manufactured with a composite of polyester and glass-fiber reinforcement, with an integral vapor barrier membrane. In this configuration, flexible aerogel blanket provides the lowest thermal conductivity available among traditional cryogenic insulation materials, providing significant reduction in total insulation thickness while satisfying thermal demands and condensation control.