Abstract: This paper briefly introduces the zoning and regional flow characteristics of simulated moving bed in the adsorption tower of PX adsorption separation unit, analyzes the importance of flow control valve in pumping loop and the specific requirements of the process for this valve, and proposes a specially designed double flow characteristic curve and a type selection scheme of the control valve with higher stability and wear resistance. The practical application effect of the pumping loop control valve manufactured using this scheme in the PX adsorption separation unit of a refining and petrochemical plant verifies the applicability and advantages of this type of control valve under this working condition.

Key words: paraxylene/PX, adsorption separation, simulated moving bed, pumping loop；control valve, double flow characteristic curve