SolidsWiki - User contributions [en]

Heatless Dryers

2012-08-04T13:50:15Z

Helal:

Heated Dryers

2012-08-04T13:48:52Z

Helal:

Gas Dryers

2012-08-04T13:46:00Z

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Filter Dryers

2012-08-04T13:44:53Z

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Freeze Dryers

2012-08-04T13:43:35Z

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Fluidized Bed Dryers

2012-08-04T13:42:16Z

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Contact Fluidizer Dryers

2012-08-04T13:40:34Z

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Disc Dryers

2012-08-04T13:39:06Z

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Counterflow Dryers

2012-08-04T13:35:24Z

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Continuous Dryers

2012-08-04T13:10:46Z

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Continuous Band Dryers

2012-08-04T13:08:56Z

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Conical Screw Dryers

2012-08-04T13:07:32Z

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Conical Dryers

2012-08-04T13:05:38Z

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Classifying Dryers

2012-08-04T10:00:43Z

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Centrifugal Dryers

2012-08-04T09:59:17Z

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Cascading Rotary Dryers

2012-08-04T09:56:10Z

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Infrared Dryers

2012-08-04T09:53:37Z

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Tray Dryers

2012-08-04T09:51:50Z

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Vertical Dryers

2012-08-04T09:50:32Z

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Microwave Dryers

2012-08-04T09:48:06Z

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Carousel Dryers

2012-08-04T09:45:28Z

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Brazing Furnaces

2012-08-04T09:41:34Z

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Batch Tray Dryers

2012-08-04T09:36:55Z

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Sludge Dryers

2012-08-04T09:33:30Z

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Vacuum Band Dryers

2012-08-04T07:53:29Z

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Vacuum Dryers

2012-08-04T07:52:24Z

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Horizontal Band Dryers

2012-08-04T07:50:33Z

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Band Dryers

2012-08-04T07:49:08Z

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Ball Dryers

2012-08-04T07:47:47Z

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Auto Dryers

2012-08-04T07:45:48Z

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Automated Batch Dryers

2012-08-04T07:45:04Z

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Active Freeze Dryers

2012-08-04T07:38:20Z

Helal:

Apron Dryers

2012-08-04T07:29:01Z

Helal:

Dispersion Dryers

2012-08-04T07:04:35Z

Helal:

[[Category:Drying]]{{Knoppen}}
<noinclude></noinclude>
[[File:Dispersion_Dryers_1.jpg|thumb|200px|right|Dispersion Dryers]]
[[File:Dispersion_Dryers_2.jpg|thumb|200px|right|Dispersion Dryers]]
The '''Dispersion Dryers''' are used for drying applications of wet cakes, pastes, sludges and production of powders from aqueous suspension. Due to the dewatering mechanism, these dryers provide effective solutions and converted to either filter cakes, pastes or sludges. These air dispersion dryers are chosen on the basis of wet deed cake particle size distribution of final powder and drying curve. The range of air dispersion dryers generally includes spray dryers, rotary dryers, flash dryers, spin flash dryers, vibrated fluid bed dryers and fluid bed dryer.

==Features==
* Smooth functionality
* Easy operation
* Durable performance

==Spin Flash Dryers==
If the wet cake is a paste or sludge, the [[Spin Flash Dryers]] are the most suited for drying application. The dryer is fitted with a mechanical agitator which helps to disperse the wet cake without any need for back mixing of the dry powder. the feeding system includes a feed tank with agitator and a screw feeder for feeding into the drying unit. The heart of drying process is cylindrical drying chamber, where the drying air enters the air distributor. The tangential air distributor of special design introduces the air as an intense swirl flow. the simple spin flash dryer is designed to handle materials that can be suspended directly in air. The drying process usually is completed in 0. 5 - 2 sees, and the final moisture is generally in the constant rate drying zone. Various types of spin flash dryers designs are available based on uniform / non uniform particle size of the feed / product. the feeding of cake is through specially designed paddle mixer / screw conveyor with / without rotary injector depending on rheology of feed material. For difficult to handle feed materials part of dried powder can be re-cycled. Spin flash dryers are suited for filter cakes, semi dried powders.

==Rotary Dryers==
The [[Rotary Dryers]] that are classified as direct or indirect (air heating method), current or counter current (material air contact). While using the dryers the material should be dried and uniformly dispersed over the entire cross-section. These dyers can also be customized based on the properties of the material.

==Features==
* Material is Passage through heated air
* Dryer is driven through a girth gear and tyre arrangement
* Minimum air leakage

==Advantages==
* Low operating costs
* Low maintenance costs
* Ideally suited for high volumes
* High thermal efficiency

These dryers are used to handle following material

* Sand
* Clays
* Maize germs
* Coal
* Ore
* Industrial sludge

==Fluid Bed Dryers==
The [[Fluid Bed Dryers]] are known for single stage operation and extensively used to convert solutions, suspensions, and slurries into dry powder within a few seconds without any intermediate handling. The high speed of the process and controlled temperature ensure the optimum efficiency of the process.

==Features==
* Easy to install
* High functionality
* Optimum performance
* Smooth operation

==Spray Dryers==
The [[Spray Dryers]] offer an effective and efficient method of removal of surface or on bound moisture from a feed product. Spray dryers are pneumatic driers having very low residence time within the equipment, thus flashing off the moisture from the feed. They are used for efficient drying of moist powders. Slurry, filter cakes, granules, etc. They operate on varying throughput rates from few hundred kilograms per hour to hundreds of tons per hour. Low temperature dehumidified air could be used for heat sensitive products to hot gases with temperature up to 500 - 600 deg. C. for temperature resistant products. spray drying equipment comprises of the feeding section normally a screw feeder, rotary valve, vibratory feeder, etc. Which feeds the wet product in a controlled fashion into the throat of the flash drier, where it is mixed with hot air produced by a hot air generator or heat exchanger

==Flash Dryers==
The [[Flash Dryers]] offer an effective and efficient method of removal of surface or on bound moisture from a feed product. Flash dryers are pneumatic driers having very low residence time within the equipment, thus flashing off the moisture from the feed. They are used for efficient drying of moist powders. Slurry, filter cakes, granules, etc. They operate on varying throughput rates from few hundred kilograms per hour to hundreds of tons per hour. Low temperature dehumidified air could be used for heat sensitive products to hot gases with temperature up to 500 - 600 deg. C. For temperature resistant products. Flash dryers comprises of the feeding section normally a screw feeder, rotary valve, vibratory feeder, etc. Which feeds the wet product in a controlled fashion into the throat of the flash drier, where it is mixed with hot air produced by a hot air generator or heat exchanger.

==Vibrating Fluid Bed Dryers==
The [[Vibrating Fluid Bed Dryers]] are used for fluidization of materials which are difficult to handle in a static fluid bed dryer.

==Physical Properties==
These materials are often characterized by having one or more of the following physical properties:

* Wide particle size distribution
* Low strength of wet or dry particles
* Stickiness or thermo plasticity of the particles
* Pasty properties of the wet feed

In the vibrated fluid bed dryer, the material is easily transported through the dryer by the combined effect of fluidization and vibration. The fluidization velocity can be judiciously selected, to minimize entertainment of the smaller particles, to avoid gas bubbling m the fluid bed thereby minimizing attrition. The residence time can be adjusted, by varying the bed height, through the overflow weir position. A cooling section can also be provided, by partitioning of the plenum chamber.

Typical products handled:

* Salt
* Milk products (used as a secondary dyer)
* Chemicals
* Tea

Fluid bed dryer is suited for powder, granules with average particle size 50 - 2000 microns. If the feed material is sticky and having wide particle size distribution. Vibro fluid bed dryer is the most suited, where vibration helps the movement of solids and drying.

==Operations==
* Material is easily transported through the dryer due to fluidization and vibration
* Fluidization velocity can be judiciously selected to minimize entertainment of the smaller :particles
* Minimize entertainment avoid gas bubbling m the fluid bed thereby minimizing attrition.
* Residence time can be adjusted by varying the bed height, through the overflow weir position.
* Provided with cooling section by partitioning of the plenum chamber.

==Advantages==
* Well suited for constant
* Well suited for failing rate drying
* By preheating the air, the residual moisture can be reduced
* Can fluidized well the solids having a well defined particle size

==Laboratory Spray Dryer==
The [[Laboratory Spray Dryers]] follow some basic principles.

==Principle==
A peristaltic pump delivers liquid from the sample container to the 2 fluid nozzle mounted on the drying chamber. Compressed air from the inbuilt compressor is also supplied to the nozzle, resulting in atomization of the liquid into a fine spray. Air from the blower is heated by an electrical air heater and blown through the drying chamber. Due to the large surface area, drying is very rapid, resulting in a sharp drop in temperature. The dry powder particles are separated from the air in the cyclone separator and collected in the glass collection bottle. The exhaust air is directed through a flexible ss hose into the atmosphere. A bag filter can be provided for secondary powder collection.

==Construction==
* The blower, electrical air heater, air compressor and the pump are placed in a stainless steel panel, with free and easy access
* The air entering the panel is filtered through a fine cloth filter
* The chamber and cyclone are of borosilicate glass with clamp fillings, designed for easy assembly and removal
* The peristaltic pump is mounted on the front of the panel with easy accessibility

==Operations==
The dryer has ease of operations. The inlet air temperature is precisely controlled by the inlet temperature pid controller. The panel includes:

* Inlet temperature controller
* Outlet temperature indicator
* On/off switch and indicator for blower
* On/off switch and indicator for heater
* On/off switch and indicator for air compressor
* On/off switch and indicator for feed pump
* Pump speed control with lcd display
* Compressed air pressure control with lcd display of air pressure.

==Video==
<youtube>14K2VeAXiCo</youtube>

Impingement Ovens

2012-08-04T06:51:09Z

Helal:

Air Impingement Dryers

2012-08-04T06:46:50Z

Helal:

Vibrating Fluid Bed Dryers

2012-08-04T06:25:37Z

Helal:

Fluid Bed Dryers

2012-08-04T06:23:00Z

Helal:

Compressed Air Dryers

2012-08-04T03:08:46Z

Helal:

[[Category:Drying]]{{Knoppen}}
<noinclude></noinclude>
[[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.
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.
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]]
* [[Refrigerated Dryers]]
* [[Deliquescent 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.

==Characteristics==
* A regenerative desiccant dryer typically delivers a dew point of between −40 °F(−40 °C) and −100 °F (−73 °C)
* A refrigerated dryer delivers a dew point not lower than approximately 35 °F (2 °C)
* A deliquescent dryer delivers a dew point suppression that fluctuates with air temperature. Typically this suppression is 20 °F
:below the compressed air temperature.

==Refrigerated Dryer==
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 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.

==Deliquescent Dryer==
A deliquescent dryer typically consists of a pressure vessel filled with a hygroscopic media that absorbs water vapor. The media gradually dissolves—or deliquesces—to form a solution at the base of the pressure vessel. The liquid must be regularly drained from the vessel and new media must be added. The media is usually in tablet or briquette form.
Deliquescent dryers have no moving parts and don't require electrical power for operation. Common applications therefore often involve remote, hazardous, or mobile worksites. Deliquescent dryers are used for removing water vapor from compressed air, natural gas, and waste gases such as landfill gas and digester gas.
The performance of a deliquescent dryer, as measured by outlet dew point, is highly dependent on the temperature of the air or gas being processed, with cooler temperatures resulting in better performance.

==Desiccant Dryer==
The term [[Desiccant Dryers]] refers to a broad class of dryers. Other terms commonly used are regenerative dryer and twin tower dryer, and to a lesser extent [[Absorption Dryers]].
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:

* 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.
* Heat of compression, which can only be used with an oil free compressor.

==Membrane Dryer==
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 [[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.
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.
Membrane air dryers depress the incoming dew point. Most dryers have a challenge air dew point and pressure specification. So if the inlet dew point is lower than the specified challenge air then the outlet dew point is even lower than specified. For example, a dryer could be rated at a −40 °F dew point with a challenge of +70 °F dew point and 100 psig. If the incoming air has an inlet dew point of only 32 °F, the outlet dew point will be somewhat less. Pressure also plays a role. If the pressure is higher than the rated specification then the outlet dew point will be lowered. This lowering of the outlet dew point is due to the longer residence time that the air has inside the membrane. Using the spec above, an operating pressure of 120 psig will yield a lower outlet dew point than specified. The extent of the improvement is dependent on the nature of the membrane and could vary among manufacturers.
Dew point suppression is not a feature of refrigerated dryers, as they chill the incoming air to a fixed temperature, usually 35 °F. So a lower dew point challenge will not yield a dew point lower than 35 °F.
Membrane air dryers are used in pneumatic components, spray painting, laser plenum purge, air bearings, air spindles, medical equipment, air guns and pneumatic brakes for vehicles and trains.

==Usages==
* Drying air for use in commercial or industrial processes that demand dry air
:*Telecomm industry (pressurizes its underground cables to repel moisture and avoid shorts
:* Paintin
:* Pneumatic tool
:* Pneumatic control systems
:* Feed air for Zeolite type Oxygen and Nitrogen generators
* Truck and Train Air brake systems.

==Video==
<youtube>OajNMRIv868</youtube>

Air Dryers

2012-08-04T03:07:06Z

Helal:

[[Category:Drying]]{{Knoppen}}
<noinclude></noinclude>
[[File:Air_Dryers_1.jpg|thumb|200px|Right|Air Dryers]]
[[File:Air_Dryers_2.jpg|thumb|200px|Right|Different Parts of Air Dryers]]
'''Air Dryer''' is a device for removing water vapor from compressed air. [[Compressed Air Dryers]] are commonly found in a wide range of industrial and commercial facilities.

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.

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]]
* [[Refrigerated Dryers]]
* [[Deliquescent 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.

==Characteristics==
* A regenerative desiccant dryer typically delivers a dew point of between −40 °F(−40 °C) and −100 °F (−73 °C)
* A refrigerated dryer delivers a dew point not lower than approximately 35 °F (2 °C)
* A deliquescent dryer delivers a dew point suppression that fluctuates with air temperature. Typically this suppression is 20 °F below the compressed air temperature.

==Refrigerated dryer==
Refrigeration dryers employ two heat exchangers, one for air-to-air and one for air-to-refrigeration. However, there is also a single TRISAB heat exchanger that combines both functions. The compressors used in this type of dryer are usually of the hermetic type and the most common gas used is R-134a. 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 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.
Some manufacturers are marketing compressors with built-in refrigeration dryers, but these have had a mixed acceptance in the market.
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.

==Deliquescent dryer==
A deliquescent dryer typically consists of a pressure vessel filled with a hygroscopic media that absorbs water vapor. The media gradually dissolves—or deliquesces—to form a solution at the base of the pressure vessel. The liquid must be regularly drained from the vessel and new media must be added. The media is usually in tablet or briquette form.

Deliquescent dryers have no moving parts and don't require electrical power for operation. Common applications therefore often involve remote, hazardous, or mobile worksites. Deliquescent dryers are used for removing water vapor from compressed air, natural gas, and waste gases such as landfill gas and digester gas.

The performance of a deliquescent dryer, as measured by outlet dew point, is highly dependent on the temperature of the air or gas being processed, with cooler temperatures resulting in better performance.

==Desiccant dryer==
The term [[Desiccant Dryers]] refers to a broad class of dryers. Other terms commonly used are regenerative dryer and twin tower dryer, and to a lesser extent [[Absorption Dryers]].

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:
* 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.
* Heat of compression, which can only be used with an oil free compressor.

==Membrane dryer==
[[Membrane Dryers]] refer to a dehumidification membrane that removes water vapor from compressed air. 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.

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.

Membrane air dryers depress the incoming dew point. Most dryers have a challenge air dew point and pressure specification. So if the inlet dew point is lower than the specified challenge air then the outlet dew point is even lower than specified. For example, a dryer could be rated at a −40 °F dew point with a challenge of +70 °F dew point and 100 psig. If the incoming air has an inlet dew point of only 32 °F, the outlet dew point will be somewhat less. Pressure also plays a role. If the pressure is higher than the rated specification then the outlet dew point will be lowered. This lowering of the outlet dew point is due to the longer residence time that the air has inside the membrane. Using the spec above, an operating pressure of 120 psig will yield a lower outlet dew point than specified. The extent of the improvement is dependent on the nature of the membrane and could vary among manufacturers.

Dew point suppression is not a feature of refrigerated dryers, as they chill the incoming air to a fixed temperature, usually 35 °F. So a lower dew point challenge will not yield a dew point lower than 35 °F.

Membrane air dryers are used in pneumatic components, spray painting, laser plenum purge, air bearings, air spindles, medical equipment, air guns and pneumatic brakes for vehicles and trains.

==Usages==
* Drying air for use in commercial or industrial processes that demand dry air
:*Telecomm industry (pressurizes its underground cables to repel moisture and avoid shorts
:* Paintin
:* Pneumatic tool
:* Pneumatic control systems
:* Feed air for Zeolite type Oxygen and Nitrogen generators
* Truck and Train Air brake systems.

==Video==
<youtube>QKBnamODCb8</youtube>
<youtube>gUUYYyF2wyg</youtube>

Belt Dryers

2012-08-04T03:04:42Z

Helal:

Air Dryers

2012-08-04T02:58:43Z

Helal:

[[Category:Drying]]{{Knoppen}}
<noinclude></noinclude>
[[File:Air_Dryers_1.jpg|thumb|200px|Right|Air Dryers]]
[[File:Air_Dryers_2.jpg|thumb|200px|Right|Different Parts of Air Dryers]]
'''Air Dryer''' is a device for removing water vapor from compressed air. [[Compressed Air Dryers]] are commonly found in a wide range of industrial and commercial facilities.

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.

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]]
* [[Refrigerated Dryers]]
* [[Deliquescent 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.

==Characteristics==
* A regenerative desiccant dryer typically delivers a dew point of between −40 °F(−40 °C) and −100 °F (−73 °C)
* A refrigerated dryer delivers a dew point not lower than approximately 35 °F (2 °C)
* A deliquescent dryer delivers a dew point suppression that fluctuates with air temperature. Typically this suppression is 20 °F below the compressed air temperature.

==Refrigerated dryer==
Refrigeration dryers employ two heat exchangers, one for air-to-air and one for air-to-refrigeration. However, there is also a single TRISAB heat exchanger that combines both functions. The compressors used in this type of dryer are usually of the hermetic type and the most common gas used is R-134a. 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 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.
Some manufacturers are marketing compressors with built-in refrigeration dryers, but these have had a mixed acceptance in the market.
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.

==Deliquescent dryer==
A deliquescent dryer typically consists of a pressure vessel filled with a hygroscopic media that absorbs water vapor. The media gradually dissolves—or deliquesces—to form a solution at the base of the pressure vessel. The liquid must be regularly drained from the vessel and new media must be added. The media is usually in tablet or briquette form.

Deliquescent dryers have no moving parts and don't require electrical power for operation. Common applications therefore often involve remote, hazardous, or mobile worksites. Deliquescent dryers are used for removing water vapor from compressed air, natural gas, and waste gases such as landfill gas and digester gas.

The performance of a deliquescent dryer, as measured by outlet dew point, is highly dependent on the temperature of the air or gas being processed, with cooler temperatures resulting in better performance.

==Desiccant dryer==
The term [[Desiccant Dryers]] refers to a broad class of dryers. Other terms commonly used are regenerative dryer and twin tower dryer, and to a lesser extent [[Absorption Dryers]].

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:
* 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.
* Heat of compression, which can only be used with an oil free compressor.

==Membrane dryer==
[[Membrane Dryers]] refer to a dehumidification membrane that removes water vapor from compressed air. 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.

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.

Membrane air dryers depress the incoming dew point. Most dryers have a challenge air dew point and pressure specification. So if the inlet dew point is lower than the specified challenge air then the outlet dew point is even lower than specified. For example, a dryer could be rated at a −40 °F dew point with a challenge of +70 °F dew point and 100 psig. If the incoming air has an inlet dew point of only 32 °F, the outlet dew point will be somewhat less. Pressure also plays a role. If the pressure is higher than the rated specification then the outlet dew point will be lowered. This lowering of the outlet dew point is due to the longer residence time that the air has inside the membrane. Using the spec above, an operating pressure of 120 psig will yield a lower outlet dew point than specified. The extent of the improvement is dependent on the nature of the membrane and could vary among manufacturers.

Dew point suppression is not a feature of refrigerated dryers, as they chill the incoming air to a fixed temperature, usually 35 °F. So a lower dew point challenge will not yield a dew point lower than 35 °F.

Membrane air dryers are used in pneumatic components, spray painting, laser plenum purge, air bearings, air spindles, medical equipment, air guns and pneumatic brakes for vehicles and trains.

==Usages==
* Drying air for use in commercial or industrial processes that demand dry air
:*Telecomm industry (pressurizes its underground cables to repel moisture and avoid shorts
:* Paintin
:* Pneumatic tool
:* Pneumatic control systems
:* Feed air for Zeolite type Oxygen and Nitrogen generators
* Truck and Train Air brake systems.

==Video==
<youtube>QKBnamODCb8</youtube>
<youtube>gUUYYyF2wyg</youtube>

Air Dryers

2012-08-04T02:56:34Z

Helal:

[[Category:Drying]]{{Knoppen}}
<noinclude></noinclude>
[[File:Air_Dryers_1.jpg|thumb|200px|Right|Air Dryers]]
[[File:Air_Dryers_2.jpg|thumb|200px|Right|Air Dryers]]
'''Air Dryer''' is a device for removing water vapor from compressed air. [[Compressed Air Dryers]] are commonly found in a wide range of industrial and commercial facilities.

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.

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]]
* [[Refrigerated Dryers]]
* [[Deliquescent 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.

==Characteristics==
* A regenerative desiccant dryer typically delivers a dew point of between −40 °F(−40 °C) and −100 °F (−73 °C)
* A refrigerated dryer delivers a dew point not lower than approximately 35 °F (2 °C)
* A deliquescent dryer delivers a dew point suppression that fluctuates with air temperature. Typically this suppression is 20 °F
:below the compressed air temperature.

==Refrigerated dryer==
Refrigeration dryers employ two heat exchangers, one for air-to-air and one for air-to-refrigeration. However, there is also a single TRISAB heat exchanger that combines both functions. The compressors used in this type of dryer are usually of the hermetic type and the most common gas used is R-134a. 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 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.
Some manufacturers are marketing compressors with built-in refrigeration dryers, but these have had a mixed acceptance in the market.
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.

==Deliquescent dryer==
A deliquescent dryer typically consists of a pressure vessel filled with a hygroscopic media that absorbs water vapor. The media gradually dissolves—or deliquesces—to form a solution at the base of the pressure vessel. The liquid must be regularly drained from the vessel and new media must be added. The media is usually in tablet or briquette form.

Deliquescent dryers have no moving parts and don't require electrical power for operation. Common applications therefore often involve remote, hazardous, or mobile worksites. Deliquescent dryers are used for removing water vapor from compressed air, natural gas, and waste gases such as landfill gas and digester gas.

The performance of a deliquescent dryer, as measured by outlet dew point, is highly dependent on the temperature of the air or gas being processed, with cooler temperatures resulting in better performance.

==Desiccant dryer==
The term [[Desiccant Dryers]] refers to a broad class of dryers. Other terms commonly used are regenerative dryer and twin tower dryer, and to a lesser extent [[Absorption Dryers]].

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:
* 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.
* Heat of compression, which can only be used with an oil free compressor.

==Membrane dryer==
[[Membrane Dryers]] refer to a dehumidification membrane that removes water vapor from compressed air. 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.

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.

Membrane air dryers depress the incoming dew point. Most dryers have a challenge air dew point and pressure specification. So if the inlet dew point is lower than the specified challenge air then the outlet dew point is even lower than specified. For example, a dryer could be rated at a −40 °F dew point with a challenge of +70 °F dew point and 100 psig. If the incoming air has an inlet dew point of only 32 °F, the outlet dew point will be somewhat less. Pressure also plays a role. If the pressure is higher than the rated specification then the outlet dew point will be lowered. This lowering of the outlet dew point is due to the longer residence time that the air has inside the membrane. Using the spec above, an operating pressure of 120 psig will yield a lower outlet dew point than specified. The extent of the improvement is dependent on the nature of the membrane and could vary among manufacturers.

Dew point suppression is not a feature of refrigerated dryers, as they chill the incoming air to a fixed temperature, usually 35 °F. So a lower dew point challenge will not yield a dew point lower than 35 °F.

Membrane air dryers are used in pneumatic components, spray painting, laser plenum purge, air bearings, air spindles, medical equipment, air guns and pneumatic brakes for vehicles and trains.

==Usages==
* Drying air for use in commercial or industrial processes that demand dry air
:*Telecomm industry (pressurizes its underground cables to repel moisture and avoid shorts
:* Paintin
:* Pneumatic tool
:* Pneumatic control systems
:* Feed air for Zeolite type Oxygen and Nitrogen generators
* Truck and Train Air brake systems.

==Video==
<youtube>QKBnamODCb8</youtube>
<youtube>gUUYYyF2wyg</youtube>

Continuous Tray Dryers

2012-08-03T09:02:39Z

Helal:

Pneumatic Dryers

2012-08-03T08:42:37Z

Helal:

Refrigerated Air Dryers

2012-08-02T13:00:45Z

Helal:

Refrigerated Air Dryers

2012-08-02T12:59:29Z

Helal:

After Cooling Dryers

2012-08-02T12:58:01Z

Helal:

Adsorption Dryers

2012-08-02T12:56:32Z

Helal:

Belt Dryers

2012-08-02T12:55:30Z

Helal: