The invention relates to a method and a
system for preparing high purity gas by a rectification method. According to the method disclosed by the invention, a target gas
raw material is firstly processed by a light component removal
tower to remove light component impurities and then is processed by a heavy component removal
tower to remove heavy component impurities; obtained purified gas is compressed into compressed gas; the compressed gas is at least divided into two parts which are respectively used as heat sources of a
tower kettle
reboiler of the light component removal tower and a tower kettle
reboiler of the heavy component removal tower; the two parts of compressed gas are condensated into liquid to be converged and stored; the stored liquid is divided into three parts; two parts of the stored liquid are respectively used as a
cooling medium of a tower top condenser of the light component removal tower and
reflux of the heavy component removal tower after being respectively subjected to throttling expansion; and the third part of the stored liquid is recovered as a product. The
system disclosed by the invention comprises the light component removal tower, the tower top condenser of the light component removal tower, the heavy component removal tower, a compressor, the tower kettle
reboiler of the light component removal tower, the tower kettle reboiler of the heavy component removal tower, a
liquid storage tank and a connecting pipeline. The method and the
system which are disclosed by the invention have the advantages that equipment is simple; energy is saved; the method and the system are flexible to operate and have wide application; the system is easy to maintain; and the method and the system have few requirements on public works.