Method for converting hot driving into cold driving of air separation system

The invention discloses a method for converting hot start-up into cold start-up of an air separation system, and relates to the technical field of oxygen production. According to the method, two sets of air separation unit molecular sieves are used and communicate with each other through an air pipeline, a communicating valve is arranged on the air pipeline, and an air separation unit in a maintenance state is set as a maintenance unit; the other set of running air separation unit is set as a running unit and is used for ensuring cold energy recovery and cooling of the air separation system; according to the technical key points, air of other operating units is used for heating, purging and cooling a maintenance unit, liquid oxygen is backflushed after the liquefaction temperature is reached, so that the unit is in a cold standby state, when oxygen and nitrogen need to be supplied, the purity of oxygen and nitrogen of products can reach the standard only by starting an air compressor for 2 hours, and the ener