Extraction Cascade with Backmixing

The relative inflow and outflow contributions for each phase of any stage n of the cascade is shown in Fig. 3.34. 

Allowing for the additional backmixing flow contributions, the component balance equation for the two phases in stage n of the cascade are now 

Although more complex in form, the resulting model equations provide no major additional difficulty, and solution is also easily obtained. Multistage extraction with backmixing is covered in the simulation example EQBACK. 

---

Figure 3.38. Multistage extraction cascade with backmixing of both phases.

Figure 3.39. Stage n of a multistage extraction cascade with backmixing.

The standard equations for a stagewise extraction cascade with backmixing as developed in Sec. 3.3.1.5 are... 

COLCON - Extraction Cascade with Backmixing and Control... 

Five stage countercurrent extraction cascade with backmixing Equilibrium stage model... 

Dynantics of Heat Exchangers, Simple Batch Extraction, Multi-Solute Batch Extraction, Multistage Countercurrent Ctiscade, Extraction Cascade with Backmixing, Countercurrent Extraction Cascade with Reaction, Absorption with Chemical Reaction, Membrane Transfer Processes... 

Assuming the liquid phases remain immiscible, the modelling approach for multicomponent systems remains the same, except that it is now necessary to write additional component balance equations for each of the solutes present, as for the multistage extraction cascade with backmixing in Section 3.2.2. Thus for component j, the component balance equations become... 

The full model is described in Section 3.3.1.5 and consists of a countercurrent stagewise extraction cascade with backmixing in both phases. 

---