Refining method and system for preparing polymerization-grade propylene from refinery crude propylene

The invention discloses a refining method for preparing polymerization-grade propylene from refinery crude propylene. The refinery crude propylene is enabled to be subjected to the following steps sequentially: (1) carrying out dehydration, H2S removal and CO2 removal by using a solid caustic soda tower; (2) then, feeding the refinery crude propylene to a desulfuration mechanism for COS removal and H2S removal; (3) removing light components including CO and O2 by using a light component removing tower; (4) then, feeding the light component removed propylene to a molecular sieve for dehydration; (5) then, carrying out treatment with a methanol removal bed which is provided with an upper bed layer and a lower bed layer: enabling the propylene to enter the methanol removal bed from the lower part of the methanol removal bed and to be subjected to dehydration and methanol removal by a Selexsorb CD catalyst of the lower bed layer; enabling the methanol removed qualified propylene to continue to be subjected to CO2 removal by a Selexsorb COS catalyst of the upper bed layer until the propylene is qualified; and (6) feeding the propylene to an arsenic removal tank for arsenic removal. According to the refining method disclosed by the invention, the flow design is unique, the energy consumption is low, the refinery crude propylene can be subjected to complete refining and separating so as to obtain high-purity refined propylene, and the requirements of a continuous-method polypropylene process can be fully met.