Process Simulation And Diagnosis Of The Propylene Fractionating Tower For The Lanzhou Petrochemical Company

After two major transformations focusing on improving the handling capacity , although the handling capacity of the propylene rectifying tower of LanZhou Petrochemical Company is enhanced , there are still some troubles existing in the propylene rectifying tower . With the feed composition and load varying, to ensure the propylene composition in the tower top stream reaches 99.6mol% , the propylene composition in the tower bottom stream often exceeds the design target . Here after analyzing the problems existing in the propylene rectifying tower ,simulation calculations aiming at various operating conditions were carried out using ASPEN PLUS11.1.In this paper, one propylene tower operating conditions were simulated before it was rebuilded . Two propylene tower operating conditions were simulated. The operating conditions were simulated when the propane in feed increase from 3.445mol%～10mol% .In all operating conditions, the optimal overhead produced quantity and the reflux ratio were confirmed. The tower top and tower kettle propylene constant were gained when reflux ratio and tower top collection changed. The effect of temperature of tower top condenser was simulated , the conclusion that the temperature of tower top condenser was less than 45℃was discovered .The part hydrodynamics was simulated of the tray . The following conclusions were gained:1. The reflux ratio and overhead produced quantity are sensitive to the proper operation of the propylene tower . The propylene composition in top and bottom stream can all achieve the design target if the reflux ratio and overhead produced quantity are properly regulated.2. The feed location is major impact on the tower . For feed conditions meeting design , the perfect feed location lie between 135～150 tower tray .3. The fluid discharge in stripping section is greater than the fluid discharge in rectifying section . Because the diameter of DA-406 is smaller than DA-406A , using DA-406 as stripping section and DA-406A as rectifying section is...