Merkel diagram

Because the heat load, L, Ga and temperatures are known for an operating tower, its performance as represented by the number of transfer units, or tower characteristics can be determined. Solve Equation 9-129 for Ka V/L, or use the modified Merkel diagram, Figure 9-127. This is the number of transfer units operating in the tower. For relative comparison of Ka values see Figure 9-128. 

For purposes of distillation calculations, a rough diagram of saturated vapor and liquid enthalpy concentration lines can be drawn on the basis of pure component enthalpies. Even with such a rough diagram, the accuracy of distillation calculation can be much superior to those neglecting enthalpy balances entirely. Example 13.8 deals with preparing such a Merkel diagram. 

Merkel diagram. See Enthalpy-concentration chart MESH equations, 405 Methanol svnthesis. 580.585... 

---