Category Archives for Design Considerations

Solid Bed Dehydrator – Desiccant Selection

No desiccant is perfect or best for all applications. In some applications the desiccant choice is determined primarily by economics. Sometimes the process conditions control the desiccant choice. Many times the desiccants are interchangeable and the equipment designed for one … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Moisture Content of Inlet Gas

An important variable that determines the size of a given desiccant bed is the relative saturation of the inlet gas. This variable is the driving force that affects the transfer of water to the adsorbent. If saturated gas (100% relative … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Pressure Drop

Towers are sized for a design pressure drop of about 5 psi through the desiccant. The pressure drop can be estimated by: Pressure drops of greater than approximately 8 psi are not recommended.

21. September 2009 by Jack
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Solid Bed Dehydrator – Bed Height to Diameter Ratio

In its simplest form, an adsorber is normally a cylindrical tower filled with a solid desiccant. The depth of the desiccant may vary from a few feet to 30 ft or more. The vessel diameter may be from a few … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Gas Velocities

Generally, as the gas velocity during the drying cycle decreases, the ability of the desiccant to dehydrate the gas increases. At lower actual velocities, drier effluent gases will be obtained. Consequently, it would seem desirable to operate at minimum velocities … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Cycle Time

Most adsorbers operate on a fixed drying cycle time and, frequently, the cycle time is set for the worst conditions. However, the adsorbent capacity is not a fixed value; it declines with usage. For the first few months of operation, … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Pressure

Generally, the adsorption capacity of a dry bed unit decreases as the pressure is lowered. If the dehydrators are operated well below the design pressure, the desiccant will have to work harder to remove the water and to maintain the … Continue reading

21. September 2009 by Jack
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Solid Bed Dehydrator – Temperature

Adsorption plant operation is very sensitive to the temperature of the incoming gas. Generally, the adsorption efficiency decreases as the temperature increases. The temperature of the regeneration gas that commingles with the incoming wet gas ahead of the dehydrators is … Continue reading

21. September 2009 by Jack
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