Patent attributes
To decrease capital costs of crack gas treatment of the olefin plant, a method for separation of olefins reduces the units for catalytic hydrogenation. In the method, olefins having three carbon atoms are separated from olefins having four carbon atoms. Crude gas is precompressed (1), precooled and dried (2), and passed into a C3/C4 separation stage (6) comprising a C4 absorber, operating at full crude gas pressure, and a depropanizer, operated at a pressure of 8 to 12 bar. In the C3/C4 separation stage, the olefins are separated into a fraction having at most three carbon atoms (C3−), and a fraction having at least four carbon atoms (C4+). The fraction having at most three carbon atoms is completely compressed (1) and passed to the catalytic hydrogenation (4); the fraction having at least four carbon atoms is passed out for further processing (7). The catalytic hydrogenation (4) yields a fraction having at least two carbon atoms (C2−), which is passed on to the low-temperature separation, and a fraction having three carbon atoms (C3), is passed to further processing (8).
