A dehydration bed is a process that uses adsorption to remove water from a substance. It consists of a cylindrical tower filled with a desiccant like calcium oxide or silica gel. Wet gas flows through the tower and water molecules adhere to the large surface area of the desiccant. The process involves repeated drying, heating, and cooling cycles using multiple towers to effectively dehydrate gas.

1. Dehydration bed

2. Assignment of
Chemical process
technology
Submitted by
Shoaib Sardar
SP10-BEC-047
Submitted to
Sir Wajih-Ur- Rehman

3. What is dehydration bed?
 Dehydration is a Process of removing water from a
substance or compound.
 Dehydration bed works on the principal of
adsorption.
 Desiccant is used in bed.
 It is a substance that absorb water and used to
remove moisture.
 It may be calcium oxide or silica gel.

4. Construction
 It is normally a cylindrical tower filled with solid
desiccant.
 Depth of desiccant vary from few feet to 30ft or
more.
 Diameter vary from few inch to 10 or 15ft.
 Bed height to diameter ratio higher than 2.5 is
desirable.

5. Process description
 Work on the principal of adsorption
 adsorption involves a form of adhesion b/w surface
of solid desiccant and water vapour.
 The desiccant is a solid, granulated drying ,which
have large effective surface area per unit weight
 because of a massive amount of microscopic pores
and capillary openings.
 A typical desiccant might have as much as 4 million
square feet of surface area per pound.

6. Process description
 Multiple desiccant bed are used to dry gas
 The number and arrangement may vary from two to
many towers.
 Three separate cycles must be performed gas
drying cycle, heating or regeneration cycle and
cooling cycle.
 The essential component of dehydration bed are

8.  Inlet gas separator, adsorption towers, A high-
temperature heater, a regeneration gas cooler, a
regeneration gas separator.
 In the drying cycle, wet inlet gas first passes
through an inlet separator where free
liquids, entrained mist, and solid particles are
removed.
 In the adsorption cycle, the wet inlet gas flows
downward through the tower.
 water molecules are adsorbed first in the top
and then in the lower layers.

9. Advantages
 Producing very low dew point
 Which are requried for cryogenic gas plant
 It is adaptable for very large changes
 A dry bed can handel high contact temperature.
disadvantage
 It is batch process
 High pressure drop
 Desiccant are sensitive to poisoning with liquids or
impurities in the gas

10. uses
In natural gas dehydration
In food industry
In oil industry
 used in Pharmaceutical
In production very low dew point