LOW TEMPERATURE DISTILLATION COLUMN

PROBLEM TO BE SOLVED: To enhance heat insulation of a low temperature distillation column through a simple structure by suspending the distillation column from a bracket provided on an outer column through a heat insulating member using a holder disposed above. SOLUTION: Air gaps are defined as heat insulating chambers 1a-1c between an outer column 1 and a condenser 3 and between a distillation column 2 and a reboiler 4. These heat insulating chambers 1a-1c are sustained in vacuum state and filled with pearlite between the outer column 1 and the condenser 3. The heat insulating chamber 1c is filled with glass wool between the outer column 1 and the reboiler 4. When a low temperature distillation column is operated, the distillation column 2 is contracted thermally and the reboiler 4 moves upward. Consequently, the density of glass wool filling the heat insulating chamber 1c is varied slightly, but since a barrier wall member 8 prevents pearlite filling the heat insulating chamber 1b from flowing into the heat insulating chamber 1c, heat insulating performance of the heat insulating chambers 1a, 1b is ensured.