Drying Equipment | Plastics Technology

Resin dryers provide simple, fast and effective drying for molding and extrusion. A variety of types are available, providing quality drying performance for nearly any application.   Some of the most common types include: 

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• Hot air dryers: No desiccant
• Compressed air dryers: No membrane or with low dew point membrane
• Desiccant bed/dehumidifying: Single- or multiple-bed type
• Desiccant wheel/dehumidifying: Rotary wheel
• Vacuum-type dryer: Heat and vacuum are used to remove material moisture

Dryers are available for molders and extruders processing as little as one pound per hour to over 6,000 pounds an hour.

Options range from small, energy-efficient portable units to large central systems. Many drying solutions feature a compact design with integrated conveying, ensuring dried material is delivered directly to the process machine.

Dryer types

Hot air dryer: These simple systems are the most economic resin dryers. Using a single-pass process, these dryers pull atmospheric air through a filter and through the heater, pushing the heated air through a drying hopper and exhausting it back into the atmosphere.

Ambient air is heated and introduced into the drying hopper. Surface moisture is removed from non-hygroscopic materials. Non-hygroscopic materials are typically dried at 180º F or less. For hygroscopic materials the air heats the pellet, and internal moisture is brought to the surface, allowing it to dry. The maximum hot air temperature is driven by the material’s softening (not melting) temperature. This type of dryer is not typically used for hygroscopic materials unless there are small quantities used from a sealed bag of resin. 

Compressed-air/dehumidifying/membrane dryer: Primarily used for low-throughput applications and small machine applications due to the amount of compressed air required. High pressure compressed air is expanded to produce higher volumes of low-pressure air. The expanded air is passed through a heater and then enters the drying hopper. Heated wet air is discharged from the drying hopper into the atmosphere. 

Non-membrane versions lower the plant dew point air (to process) by 40ºF to 50ºF. Compressed plant air typically provides approximately 0 to +15º F dew point air. In cases where the central compressed air system is equipped with a central compressed air dryer, this may reduce the compressed air dew point enough (0 to -15º F) to allow proper drying without the use of an additional membrane on the dryer. 

Membrane versions run compressed air through a membrane, which removes moisture from the air. Compressed air dryers which use a membrane can produce -40°F air or better.

Some applications may require a HEPA filter on the air outlet of the drying hopper to capture any exhaust dust particles and prevent them from entering the atmosphere.

Desiccant bed/dehumidifying dryer: This type of dryer uses a desiccant material (e.g., beads) to absorb moisture. As beads become saturated, they go through a regeneration process to remove moisture which will allow the desiccant to regenerate and allow moisture to be absorbed again into the beads (the process of adsorption).  Extremely hot air (400 to 800°F) is passed over the desiccant to release the moisture they’ve absorbed from the airstream. However, the beads must be cooled before returning to the drying process to avoid melting the resin with a temperature spike when the bed is put online for processing.

Multiple-bed desiccant technology can use one or two blowers. The blower(s) provide process, cooling and regeneration air, utilizing a switching valve to direct air through the desiccant beds.

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Desiccant wheel rotor type (honeycomb) dryer: Desiccant wheel dryers provide a different type of desiccant drying. They are far more efficient, more compact, and require less maintenance. Traditional dehumidifying dryers use a large volume of molecular sieve (in pellet form) composed of at least 30% clay. This desiccant bead tends to degrade over time. The desiccant wheel design is completely different. It is constructed from a pure molecular sieve impregnated onto a durable media. This material is formed into a reinforced honeycomb structure.

Desiccant wheel dryers provide stable, extremely reliable dew point in nearly any ambient condition. Stable process temperatures mean no bed spikes. These dryers go from cold start to drying in minutes. They can achieve higher-than-average process air flows using minimal energy due to low pressure drop across the rotor. Large surface area to volume ratio of desiccant provides faster adsorption and desorption conditioning of the desiccant. The honeycomb has a thin layer of desiccant that uniformly absorbs moisture. At regeneration, the absorbed moisture is easily evaporated off the media, this allows the dryer to deliver effective continuous drying as the rotary wheel slowly rotates.

A wheel dryer operates through three simultaneous processes: drying, regeneration and cooling:

• In the drying loop, humid air from the drying hopper passes through a filter, cooler and blower to the desiccant wheel, extracting moisture from the process air before returning to the drying hopper.
• The regeneration process removes moisture from the desiccant wheel using a separate filter, blower and heating chamber, expelling hot, moist air external to the dryer.
• Cooling follows regeneration, where a portion of low dew point, cooled air is directed to the desiccant wheel (before the heater) enhancing its moisture absorption for the next drying cycle.

The horizontal dryer is a machine for the efficient dewatering and drying of materials such as plastic sheets, films, and PET flakes. It separates moisture from the material by centrifugal force generated by high-speed rotation, ensuring that the moisture content is reduced to the desired level.

Our plastic dewatering machine is made of high-quality materials with sturdy and durable structure, high corrosion resistance, low maintenance cost, and long service life. The appearance of the equipment can be customized according to customers‘ needs, which can better meet customers’ production requirements.

Features of Plastic Chips Dryer Machine

• The machine is suitable for a wide range of applications, such as PET bottles, PP/PE/PVC/ABS flakes, and so on.
• Reasonable design, low noise, and easy to maintain, you can easily open the body to remove the screen impurities inside the dryer.
• Good dewatering effect, able to control the moisture in the plastic material below 3%-5%.
• It can be used with a drying tube to control moisture at 0.5%-1%.
• The screen, rotor, and body are made of high-quality stainless steel, which makes the horizontal dryer sturdy and durable.
• In addition to dewatering, it also removes fine debris such as plastic sand.

Application Of Horizontal Dryer

Plastic flake dewatering machines are widely used in a variety of plastic recycling lines, including film pelletizing lines, hard washing and pelletizing lines, and PET bottle flake washing lines. It is capable of efficiently dewatering and drying different types of plastic materials, whether it is soft plastic film, rigid plastic flakes, or PET bottle flakes, the centrifugal dryer plays a key role in the production process, ensuring that the dryness of the material meets the needs of subsequent processing, and improves the efficiency and product quality of the entire production line.

Working Principle of Horizontal Dewatering Machine

The working principle of the horizontal dryer is based on the centrifugal force generated by the high-speed rotation to separate water or moisture from the plastic material. In operation, the plastic enters the rotating drum of the plastic chips dryer machine after which the motor is activated, causing the drum to rotate at high speed. This high-speed rotation generates an extremely strong centrifugal force. Through perforations or openings in the surface of the drum, the extruded moisture is effectively separated along with the centrifugal force, resulting in a drier plastic material.

Working Video of Horizontal Dryer

Importance Of Plastic Dryer Machine

The use of dehydrators in recycled plastic pellet production lines and plastic recycling washing lines is critical for the following reasons:

• Reduction of smoke and pollution: In a film granulating line, if moisture is not effectively removed, the subsequent pelletizing process may generate a large amount of smoke and increase environmental pollution.
• Reduced energy consumption: The dewatering machine reduces production costs by initially removing water from the plastic material, reducing heating time and energy consumption during subsequent pelletizing.
• Improved pellet quality: the horizontal dryer ensures that the material reaches the proper level of dryness before entering the pelletizer, avoiding unsmooth pellet surfaces and internal porosity, thus guaranteeing consistency in the final product.
• Ensure the quality of recycled flakes: the moisture content of recycled sheets must be less than 3%-5%. The dewatering machine can effectively control the moisture and ensure uniform and stable quality of the sheet.

Specifications

The model of our plastic chips dryer machine is SL-550, the output is kg/h and the filter pore size is 4mm. In addition, we have a variety of models and appearances to choose from, and we can also provide customized services.

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Plastic Flake Dewatering Machine Export Cases