The core equipment of vacuum distillation is the vacuum tower and its vacuum pumping system. The principle of vacuum distillation is the same as that of atmospheric distillation, and the key is that the vacuum equipment is used at the top of the vacuum tower, so that the pressure at the top of the tower is reduced to several thousand pa. The role of the vacuum equipment is to continuously pump away the non-condensing gas (mainly cracked gas and leaked air) and blown water vapor generated in the tower to ensure the vacuum requirement of the decompression tower. The vacuum pumping equipment of the decompression tower is commonly used as a steam ejector (also known as steam ejector pump) or a mechanical vacuum pump (mechanical vacuum pump). Among them, mechanical vacuum pumps are only used in some dry vacuum distillation towers and small refinery vacuum towers, and steam ejectors are widely used.