Ave’s = 700, Std Dev’s = 100, USL’s=1000, DNS’s = 3σ
Fraction of Samples
1000
800
600
400
200
0
–200
–400
–600
–800
–1000
0.4000
0.3500
0.3000
0.2500
0.2000
0.1500
0.1000
0.0500
0.0000
–ppm Light Key in Bottoms (Tray Temp) ppm Heavy Key in Distillate
Figure 7.1 Quality performance in distillation column.
Std Dev’s = 100, USL’s = 1000, Bott DNS = 4σ, Dist DNS = 2σ
Fraction of Samples
1000
800
600
400
200
0
–200
–400
–600
–800
–1000
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
–ppm Light Key in Bottoms (Tray Temp) ppm Heavy Key in Distillate
Figure 7.2 High tray temperature in distillation column.
Optimizing Product Quality Performance ◾  61