Dehydration bed


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Dehydration bed

  1. 1. Dehydration bed
  2. 2. Assignment of Chemical process technologySubmitted by Shoaib Sardar SP10-BEC-047Submitted to Sir Wajih-Ur- Rehman
  3. 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. 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. 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. 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
  7. 7.  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.
  8. 8. 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
  9. 9. usesIn natural gas dehydrationIn food industryIn oil industry used in PharmaceuticalIn production very low dew point