Abstract: The influence of the feeding position and the number of trays on the energy consumption of the propylene fractionator was explored. Based on the control of the optimal feeding position variables，ProII process simulation and Origin data fitting were applied to obtain a certain feed composition and the expression of the reboiler load and the number of trays. The results showed that the thermal load of the propylene fractionator decreased with the increase of the number of trays，and the decreasing amplitude gradually decreased and finally reached a extreme value. Combined with the cost of utility and equipment，the work can provide certain theoretical support for the specific plan for the new-built or reformed propylene fractionator. When the old factory is reconstructed，the purpose of capacity expanding or reducing energy consumption can be achieved by optimizing the feeding position or increasing the number of trays.

Key words: propylene fractionator, process simulation, energy saving, capacity expansion