Random Packing Calculations

Rating or sizing calculations with Random 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.

The pressure drops and flood point for KOCH-GLITSCH packing using the RATEFRAC algorithm are calculated using the KOCH-GLITSCH method.

Packings formerly available from the Norton Company now are owned by Koch-Glitsch, LP. The pressure drops for these former Norton packings are calculated by the method of Norton Co. or Tsai. Flood point is calculated by the method of Eckart if not supplied by the user. HETP (Height Equivalent to a Theoretical Plate) may be supplied or calculated by the Frank "rule-of-thumb". For Norton high performance packings, efficiencies and capacities are based on Norton correlations.

Data for several types of random packing are available. For other types of packing, a packing factor (surface per unit volume) must be supplied. No factors are published for the Tsai correlation, so Norton factors are used.

Calculation Mode

In Rating calculations, the column diameter is fixed and parameters such as pressure drop and approach to flooding, are calculated.

In Sizing mode, the column diameter is normally calculated by an approach to flooding. If IMTP packing is selected, the diameter may be calculated from an approach to "efficient velocity". In addition, you may specify a maximum pressure drop. The diameter will be determined by whichever is limiting. By default, the maximum velocity is calculated and multiplied by the approach to obtain the design value. Alternatively the design value may be specified directly.

Theoretical Stages

The number of theoretical stages is set by the See Number of Trays in the Column Main Window. By default, the HETP (Height Equivalent to a Theoretical Plate) is calculated by Frank’s method. Alternatively, you may define the packing height or the HETP. The unknown parameter is calculated from:

 HETP = Height / Number Of Packed Stages

However, Frank method for HETP is not applicable to KOCH-GLITSCH packings.

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.

References

1. Tsai, T. C., Packed Tower Program has Special Features, 1985, Oil & Gas J., 83(35), Sept., 77.

2. Perry, R. H., and Chilton, C. H., 1984, Chemical Engineer's Handbook, 6th Ed., Chapt. 18, McGraw-Hill, N.Y.

3. Vital, T. J., Grossell, S. S., and Olsen, P. I., Estimating Separation Efficiency, 1984, Hydrocarbon Processing, Dec., 75-78.

4. Bolles, W. L., and Fair, J. R., Improved Mass-transfer Model Enhances Packed-column Design, 1982, Chem. Eng., July 12, 109-116.

5. Intalox High-performance Separation Systems, 1987, Norton Bulletin IHP-1.

6. Frank, O., 1977, Chem. Eng., 84(6), Mar. 14, 111-128.

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

Norton Company, Norton packings, and Norton method are wholly owned by Koch-Glitsch, LP.

RATEFRAC ® is a registered trademark of Koch-Glitsch, LP