Design, development, installation and commissioning of long distance cryogenic transfer lines

A long distance cryogenic transfer line,100m long, was designed and commissioned to interconnect six distantly located Liquid Nitrogen (LN2) storage Dewars, using super insulated pipes. Various technical aspects such as the pressure drop, the cool down time, heat-in-leak analysis and different insulation types were studied in detail for the realization of this transfer line. A novel approach was adopted for the theoretical calculation of cool down time. The same was also determined experimentally and compared. Vent valves were installed along the line at appropriate locations to relieve excess pressure and facilitate free flow of LN2 during the initial cool down. Safety measures like pressure relief valves and rupture disks were provided to avoid excess pressure build up in closed sections. Since its commissioning, 10,00,000 litres of LN2 have been transferred successfully with about 84% transfer effectiveness and the performance of transfer line was found to be in-line with our analysis.