Structured Packing Calculations

Rating or sizing calculations with Structured Packings are based on the total vapor entering, and the total liquid leaving, the total height equivalent of a theoretical stage. The column may be divided into a number of packed sections to model the use of different packing types or characteristics.

Data for 12 types of Sulzer packings and 27 types of packings from Koch-Glitsch, LP are available. Information on the packings and their suitability for various applications is available from your nearest SimSci Office.

Theoretical Stages

The number of theoretical stages is set by the See Number of Trays in the Column Main Window. You must define the packing height or the HETP (Height Equivalent to a Theoretical Plate). The other is calculated from:

 HETP = Height / Number Of Packed Stages

Pressure Profile

The pressure drops across the condenser, reboiler and stages for which no packing calculations are requested are specified in the Column Pressure Profile Window. As calculations approach convergence, the pressure profile is updated based on the calculated pressure drop across the packing. This is repeated until both the column calculations and the pressure profile are converged.

Applicability

Accuracy of the calculated capacity is within 10% and that of the pressure drop within 20%. However, accuracy may be reduced if the correlations are used outside the range over which the they were derived. These ranges are shown below:

Gas density 0.05 - 60 kg/m3

Liquid density 400 - 1100 kg/m3

Liquid viscosity 0.05 - 2 cP

Liquid surface tension 2.1 - 72 mN/m

F-factor 0.05 - 5

Specific liquid load 0 - 20 m3/m2-hr

Pressure (capacity) 0.01 - 20 bar

Pressure drop 0.01 - 2 bar

The maximum recommended gas load corresponds to a pressure drop of 3 mbar/m.

References

1. Spiegel, L., and Meier, W., Correlations of Performance Characteristics of the Various Mellapak Types (Capacity, Pressure Drop and Efficiency), 1987, Paper presented at the 4th Int. Symp. on Distillation and Absorption, Brighton, Eng. (Sulzer Chemtech Document No. 22.54.06.40). 

2. Separation Columns for Distillation and Absorption, 1991, Sulzer Chemtech Document No. 22.13.06.40.  

Full details of the calculation method can be found in the PRO/II Reference Manualr.