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Difference between revisions of "Compressed Air Dryers"
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* Please start editing this page after the /noinclude | * Please start editing this page after the /noinclude | ||
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[[File: | [[File:Compressed_Air_Dryers.jpg|thumb|right|200Px|Compressed Air Dryers]] | ||
'''Compressed Air Dryers''' are commonly found in a wide range of industrial and commercial facilities. The [[Air Dryers]] are used to remove water vapor from compressed air. | '''Compressed Air Dryers''' are commonly found in a wide range of industrial and commercial facilities. The [[Air Dryers]] are used to remove water vapor from compressed air. | ||
The process of air compression concentrates atmospheric contaminants, including water vapor. This raises the dew point of the compressed air relative to free atmospheric air and leads to condensation within pipes as the compressed air cools downstream of the compressor. | The process of air compression concentrates atmospheric contaminants, including water vapor. This raises the dew point of the compressed air relative to free atmospheric air and leads to condensation within pipes as the compressed air cools downstream of the compressor. | ||
Excessive water in compressed air, in either the liquid or vapor phase, can cause a variety of operational problems for users of compressed air. These include freezing of outdoor air lines, corrosion in piping and equipment, malfunctioning of pneumatic process control instruments, fouling of processes and products, and more. | Excessive water in compressed air, in either the liquid or vapor phase, can cause a variety of operational problems for users of compressed air. These include freezing of outdoor air lines, corrosion in piping and equipment, malfunctioning of pneumatic process control instruments, fouling of processes and products, and more. | ||
There are various types of compressed air dryers. Their performance characteristics are typically defined by the dew point. | There are various types of compressed air dryers. Their performance characteristics are typically defined by the dew point. | ||
* [[Regenerative Desiccant Dryers]], often called [[Regens]] or [[Twin Tower Dryers]] | * [[Regenerative Desiccant Dryers]], often called [[Regens]] or [[Twin Tower Dryers]] | ||
* [[Refrigerated Dryers]] | * [[Refrigerated Dryers]] | ||
* [[Deliquescent Dryers]] | * [[Deliquescent Dryers]] | ||
* [[Membrane Dryers]] | * [[Membrane Dryers]] | ||
Water vapor is removed from compressed air to prevent condensation from occurring and to prevent moisture from interfering in sensitive industrial processes. | Water vapor is removed from compressed air to prevent condensation from occurring and to prevent moisture from interfering in sensitive industrial processes. | ||
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==Refrigerated dryer== | ==Refrigerated dryer== | ||
Refrigeration dryers employ two heat exchangers, one for air-to-air and one for air-to-refrigeration. | Refrigeration dryers employ two heat exchangers, one for air-to-air and one for air-to-refrigeration. The goal of having two heat exchangers is that the cold outgoing air cools down the hot incoming air and reduces the size of compressor required. At the same time the increase in the temperature of outgoing air prevents re-condensation. | ||
Most manufacturers produce "cycling dryers". These store a cold mass that cools the air when the compressor is OFF. When the refrigeration compressor runs, the large mass takes much longer to cool, so the compressor runs longer, and stays OFF longer. These units operate at | |||
Most manufacturers produce "cycling dryers". These store a cold mass that cools the air when the compressor is OFF. When the refrigeration compressor runs, the large mass takes much longer to cool, so the compressor runs longer, and stays OFF longer. These units operate at lower dew points, typically in the 35–40 °F range. When selected with the optional "cold coalescing filter", these units can deliver compressed air with lower dew points. | |||
Commonly a coalesing prefilter is installed immediately upstream of a refrigerated dryer to remove lubricating oil and other contaminants that have the potential to foul the dryer's heat exchangers. | Commonly a coalesing prefilter is installed immediately upstream of a refrigerated dryer to remove lubricating oil and other contaminants that have the potential to foul the dryer's heat exchangers. | ||
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The compressed air is passed through a pressure vessel filled with an absorbent media such as activated alumina, silica gel, molecular sieve or other desiccant material. The desiccant can bring the dew point of the water vapor in the air down to −40 °C (−40 °F) or below. This means that the air will not condense (deposition) water until it is cooled to −40 °C (−40 °F). In practice, two cylinders with desiccant are used; one is drying the air, while the other vessel is being regenerated. The switching of the vessels and the regeneration sequence is typically done automatically via solenoid operated valves. | The compressed air is passed through a pressure vessel filled with an absorbent media such as activated alumina, silica gel, molecular sieve or other desiccant material. The desiccant can bring the dew point of the water vapor in the air down to −40 °C (−40 °F) or below. This means that the air will not condense (deposition) water until it is cooled to −40 °C (−40 °F). In practice, two cylinders with desiccant are used; one is drying the air, while the other vessel is being regenerated. The switching of the vessels and the regeneration sequence is typically done automatically via solenoid operated valves. | ||
The regeneration of the desiccant vessel can be during three different methods: | The regeneration of the desiccant vessel can be during three different methods: | ||
* Heatless "pressure-swing" drying, which uses part of the dry compressed air coming from the other vessel to dry the desiccant in the vessel being regenerated at lower pressure. | * Heatless "pressure-swing" drying, which uses part of the dry compressed air coming from the other vessel to dry the desiccant in the vessel being regenerated at lower pressure. | ||
* [[Heated Dryers|Heated dryer]], which uses a hot air blower, so there is no loss of compressed air. | * [[Heated Dryers|Heated dryer]], which uses a hot air blower, so there is no loss of compressed air. | ||