4. Case study 2: cold-end process of an ethylene plant

This case aims to illustrate how the new refrigeration model can be used to estimate the power demand in a multi-level cascade cycle. A second aim is to illustrate the performance of the proposed optimization model in minimizing the net power demand.

The complex refrigeration cycle in the ethylene-propylene cascade refrigeration cycle from the cold-end process of an ethylene plant is selected for analysis. Case study data are given in Table 6. Figure 6(a) shows the process flow diagram of the ethylene-propylene cascaded refrigeration cycle. Figure 6(b) shows the refrigeration cycle matched against the grand composite curve of the stream data presented in Table 6. Table 7 gives the corresponding cascaded refrigeration cycle details, including two propylene cooling levels in the upper cycle and three ethylene cooling levels in the lower cycle.
