Why is the pressure in the lower tower of the air separation equipment higher than that in the upper tower?

Upper tower and main condenser assembly in small air separation unit Assembly using wind, electric tools to cut away the test pressure blind, or head with aircraft methods to clean up the welding area; according to the chart processing bevel, the site preparation scaffolding must be safe and solid, welders should be in accordance with the provisions of T4734-22 qualified by examination, group positioning welding and formal welding are used for two people at the same time double-sided cross-weld...

Air cooling column start-up process