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Difference between revisions of "Air Dryers"
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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 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. | ||
* Heat of compression, which can only be used with an oil free compressor. | * Heat of compression, which can only be used with an oil free compressor. | ||
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==Membrane dryer== | ==Membrane dryer== | ||
Membrane dryer refers to a dehumidification membrane that removes water vapor from compressed air. | Membrane dryer refers to a dehumidification membrane that removes water vapor from compressed air. | ||
Typically, the compressed air is first filtered with a high-quality | Typically, the compressed air is first filtered with a high-quality [[Coalescing Filters|Coalescing Filter]]. This filter removes liquid water, oil and particulate from the compressed air. The water vapor–laden air then passes through the center bore of hollow fibers in the membrane bundle. At the same time, a small portion of the dry air product is redirected along the outside surface of the fibers to sweep out the water vapor which has permeated the membrane. The moisture-laden sweep gas is then vented to the atmosphere, and clean, dry air is supplied to the application. The membrane air dryers are designed to operate continuously, 24 hours per day, 7 days per week. Membrane air dryers are quiet, reliable and require no electricity to operate. | ||
Some dryers are non-porous, which means they only permeate water vapor. Non-porous membranes' drying power is only a function of flow rate, pressure. The sweep flow is strictly controlled by an orifice and is not a function of temperature. | Some dryers are non-porous, which means they only permeate water vapor. Non-porous membranes' drying power is only a function of flow rate, pressure. The sweep flow is strictly controlled by an orifice and is not a function of temperature. | ||
Porous membranes are modified nitrogen membranes and pass air as well, usually changing the composition of the compressed air by reducing the oxygen content. The only maintenance required is changing the prefilter cartridge twice a year. The performance of porous membranes are dependent on temperature as well as operating pressure and flow. | Porous membranes are modified nitrogen membranes and pass air as well, usually changing the composition of the compressed air by reducing the oxygen content. The only maintenance required is changing the prefilter cartridge twice a year. The performance of porous membranes are dependent on temperature as well as operating pressure and flow. | ||