The invention provides a refined heavy-
hydrocarbon removal
system for recovering LNG / LPG / NGL from
petroleum associated gas, which comprises a
raw material associated gas inlet pipeline, an LPG cold box, a low-temperature separator and a refined removed heavy
hydrocarbon absorption
tower, wherein an outlet of a lower box of the LPG cold box is connected with the refined removed heavy
hydrocarbon absorption
tower by a pipeline, an outlet at the bottom of the refined removed heavy hydrocarbon absorption
tower is connected with a tower-bottom
liquid phase pipeline, an outlet at the top of the refined removed heavy hydrocarbon absorption tower is connected with a lower middle box of the LPG cold box by a pipeline, the lower middle box is connected with the low-temperature separator by a pipeline, the bottom of the low-temperature separator is connected with an absorbent
booster pump by a pipeline, and the absorbent
booster pump is connected with the refined removed heavy hydrocarbon absorption tower by a pipeline. By using the characteristic that the equilibrium constants of hydrocarbon substances at different temperatures and consisting of different components are different, the
system dilutes the heavy hydrocarbon content of associated gas, thereby achieving the purpose of reducing the heavy hydrocarbon content of
dry gas; the temperature of associated gas is reduced two times by using the cold box so as to meet different temperature requirements of absorption and separation; and due to the adoption of the absorption tower, the precision of heavy hydrocarbon removal is improved.