Method for absorbing and separating cracking gas from preparation process of low carbon olefin

摘要

Disclosed is a method for absorbing and separating cracking gas from the preparation process of low carbon olefins, by introducing a primary absorbent (14) and a secondary absorbent (13) to a methane-removing tower, and absorbing and separating the same through countercurrent with respect to the feedstock of the methane-removing tower at an intermediate temperature under an intermediate pressure, so as to obtain a top fraction (12) mainly comprising hydrogen and methane and a bottom fraction (15) mainly comprising the absorbents and a fraction of C2 and above. The primary absorbent (14) is mainly a mixed fraction of Cn or Cn+ and the secondary absorbent (13) is mainly a mixed fraction of Cn' or Cn'+, wherein n and n' are independently 3, 4 or 5, with the provision that when the secondary absorbent (13) is a mixed fraction, n' is not 3.