PDF

Excel

1. Basic Math and Excel Skill
2. Koch-Glitsch Software
3. Have a Computer
4. Have a Desire

You get to know how to select the best type of packings for a packed column

Overview

Types of Packing
The principal requirement of a packing are that it should:
Provide a large surface area: a high interfacial area between the gas and liquid.
Have an open structure : low resistence to gas flow
Promote uniform liquid distribution on the packing surface
Promote uniform vapor gas flow across the column cross-section.
Many diverse types and shapes of packing have been developed to satisfy these requirements. Thay can be divided into two broad classes:

1.Packing with a regular geometry: such as stacked rings, grids and proprietary structured packings.
2.Random packings: rings, saddles and proprietary shapes, which are dumped into the column and take up a random arrangement.

The advantage of structured packings over random packing is their low HETP and low pressure drop

In this part you learn how to reach a good estimation of column diameter using Excel sheet
Determination of the packing height

Overview

Height Equivalent to a Theoritical Plate (HETP) definition

The optimum number of equilibrium stages (or theoritical plates or trays) to perform a required separation is determined in many cases with a thermodynamical simulation program.

To determine the height of a packed column bed, when the number of equilibrium stages is fixed, the height of packing to achieve the same separation as one equilibrium stage is required. This height is called HETP (Height Equivalent to a Theoritical Plate).

HETP determination

The HETP is determined experimentally in laboratory or pilot plant tests. It is a function, among others, of packing type, vapor and liquid densities, liquid viscosity and surface tension, vapor and liquid loading.

Few generalised methods for calculating HETP are available in published literature. Consult a packing manufacturer to obtain reasonable estimates of packing requirements and HETP for a
particular service.

Generally HETP values range from 300 to 900 mm but can be as high as 1500 mm (e.g. glycol stripper).

Column height estimation

The height of a packed column takes account of:
1. the packing height,
2. the space required for the disengagement of the vapor at the top of the column to minimise the liquid carry-over,
3. the retention liquid volume required at the bottom of the column to control the liquid discharge and to prevent the gas carry-through in the liquid,
4. the space required for the feed stream, when the column has a stripping and a rectifying section,
5. the space for location of liquid distributors and redistributors.
Packing height determination is described in previous paragraphs.

Height determination of the bottom part is identical to the height determination of the bottom part of a trayed column.

Height determination of the top part and of the feed part of the column follows the same rules described for trayed columns. However this value must be increased by the space required for liquid distributors location (15 to 45 cm above the packing).

In this part you learn the followings:
1. Become familiar with the environment of KG Tower software
2. Know how to Calculate diameter of the tower using KG Tower
3. Know how to Calculate other charachteristic of the disigned tower using KG Tower