Analyzing Computer Simulation Results by Graphical Techniques

4 Analyzing Computer Simulation Results by Graphical Techniques 

A prime application of graphical methods in modern distillation technology is for analyzing the results of computer simulations. Several of the graphical construction rules can be bent in order to benefit from computer accuracy and to reduce effort. Johnson and Morgan (28) described several key considerations their work is expanded here using the author s experience. 

It has been the author s experience that an x-y diagram is the most useful graphical technique for analyzing computer simulation results. The x-y diagram is capable of 

The x-y diagram should be examined for pinching both for design conditions and for some deviations (variation in feed temperature, feed composition, errors in relative volatility, etc,), For deviations, a simple construction (e,g, a q-line with a slightly different slope) on the design conditions x-y diagram is usually sufficient. When the threat of a pinched region is detected, a more detailed analysis (e.g., a computer run for the deviated conditions) is warranted. 

Identifying mislocated feed points The feed point should be where the g-line intersects the equilibrium curve. This rule works well for binary distillation (Sec, 2,2,5), but not so well for multicomponent distillation (Sec, 2.3.7). In Fig, 2,22 it works well the x-y diagram 

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