Desiccant Dryer

A desiccant dryer for the plastic resin is a piece of essential equipment in the plastic industry, which you can use to remove the water or moisture content in the plastic resin.

The thing which sets apart a desiccant dryer from other plastic dryers is the desiccant. The desiccant dryer makes use of desiccant to eliminate the moisture content from plastic resins.

The other names of desiccant dryers include twin tower dryers, regenerative dryers, and adsorption dryers.

The air within a desiccant dryer or dehumidifying dryer moves in the cycle across the dryer or drying hopper. It maintains lower humidity levels throughout. When drying takes place, the dryer plays a crucial role in collecting moisture from the plastic resin and depositing it to desiccant before releasing it to the ambient air.

To produce plastic products in the process, moisture content may exist in raw materials (different types of plastics).

It is a significant factor that influences the quality of the final product. Therefore, removing the water contained in the raw materials is very important for protecting the end quality.

You can use the desiccant dryer to dry all kinds of resin, polyester, polyurethane, PVC, and much more. A desiccant dryer for plastic resin provides an opportunity to extend the material’s shelf life and slow down the aging process.

The desiccant dryer has multiple types that exist in the market. The working principle of all of us alike. The main difference among other plastic dryers or desiccant dryers is that they make use of hot dry air compared to ambient air in eliminating the moisture content from plastic resin.

The system works in the form of a closed loop. It does not allow the air to escape from the system and get mixed with ambient air. Instead, the desiccant dryer circulates air through a plastic resin to make it completely dry.

The working principle of the desiccant dryer is as follows:

• At first, the air through the hopper moves to the dryer and later to the heat-exchanging device to cool.
• Next, the distributor causes the air to make its way through the chamber containing the desiccant.
• Now the desiccant plays its part and takes up all the moisture air contains, thus making it dry.
• This dry air then moves towards the blower, and from the blower, it gets distributed from the pipe located at the bottom of the desiccant dryer hopper.
• When the moisture content within a desiccant exceeds a certain level, you need to regenerate the desiccant.
• The dew point meter measures the amount of moisture content periodically and displays it in real time.

To use desiccant again, you need to remove the moisture content through desiccant through a process known as regeneration. You can do this either by using hot air or by employing compressed dried air. It is essential to keep your desiccant dryer operational.

• In regeneration, the heater raises the air temperature and makes it hot.
• This hot air then with the help of a blower forced through the desiccant
• The air absorbs the excess moisture content from the desiccant and exists in ambient air
• To cool the hot desiccant, ambient air is utilized before employing it in the process of drying
• The honeycomb wheel rotor keeps rotating throughout the process periodically to switch containers

Desiccant dryer plays a significant role in injection molding or extruding. The desiccant dryers are lined with a desiccant material that removes the moisture from the materials to bring their moisture content down to an appropriate level before entering into the mold cavity. Injection molders depend on the desiccant drying process to ensure that their products have an acceptable moisture level when they enter the mold.

A desiccant dryer is a new type of dryer widely applied to injection molding. It has the following advantages:

• Reduce the drying time, shorten process working time;
• New mold can be used directly without baking, improving production efficiency;
• Saves energy consumption
• Ensure the molding quality, Reduce moisture content.
• Decrease heat shrinkage and enhance productivity.
• If the plastic resin is not dried, polymers react with moisture and decrease molecular weight when heated at high temperatures.

Desiccant dryer plays a more significant role in the plastic resin extrusion process. The main reason for using a desiccant dryer in extrusion is to control the moisture content of the different plastic resins.

Extruding is the process of molding plastic pellets into a plate or sheet. It removes water vapor to reduce plastic resin brittleness, swelling, and deterioration due to weathering.

Several different types of desiccant materials exist in the market. The widely used desiccant materials include silica gel, molecular sieve, and activated alumina. The cost of these materials varies from one another. The cost of the desiccant also depends on various factors. Some of the main factors include:

• How strong the material exhibits the adsorption ability?
• The regeneration temperature associated with desiccant material
• The pore volume associated with desiccant
• Aperture size and void fraction of chosen desiccant material
• Environmental conditions it can bear, including temperature level, humidity level

If the desiccant material has a large pore size and greater pore volume, its adsorption ability increases, holding a large amount of moisture content.

The cost of silica gel desiccant with a 99.80 percent purity level lies in the range of $3.10 to $3.30 per for 5000 to 60,000 pieces.

The price of a molecular sieve with a 99.9 percent purity level and a diameter of 1.7 to 3.2 lies in the range of $1.06 to $1.80 per kilogram.

On the other hand, the price of activated alumina with 93 percent purity and a size of 1 to 6 mm lies in the range of $0.80 to $1.00 per kilogram.

You can choose anyone, but the most widely used desiccant material in the desiccant dryer is honeycomb wheel silica gel.

The quantity of plastic resin that you can dry using your desiccant dryer depends on multiple factors. Some of the main factors are as follows:

• Size of desiccant dryer that you are using for your plastic resin drying
• Desiccant material used in your desiccant dryer for drying purposes
• Type of plastic resin that you are drying with your desiccant dryer
• Level of moisture content in your plastic resin
• Desiccant dryer efficiency

The life associated with desiccant dryers depends on multiple variables. Some of the main variables that play a significant role in driving your desiccant dryer are as follows:

• The characteristics of materials used in the manufacturing of your desiccant dryer
• Environmental conditions in which desiccant dryer is used
• If the proper maintenance requirements during the operation of the desiccant dryer are followed or not
• The frequency of usage of your desiccant dryer
• If Timely replacement of desiccant material and filter is carried out or not

All these factors significantly affect the life associated with desiccant dryers. Suppose you change the desiccant material timely and monitor the dew point and drying temperature during the operation of your desiccant dryer. In that case, this will add up to the life of the desiccant dryer because everything remains under control.

In general, the desiccant dryer lasts from 5 to 15 years. Life can be elongated if appropriately maintained. The energy associated with desiccants also affects the life related to desiccant dryers.

Usually, in non-heated desiccant dryers, the desiccant may last up to 5 years, while in heated dryers, the life of the desiccant lies in the range of 2 to 3 years.

If you change the filter timely, then it helps you prevent the desiccant material from contamination. This will also add up to the life of the desiccant dryer.

The time when to replace your desiccant material dramatically affects the efficiency and effectiveness of your desiccant dryer. If the desiccant material is in good condition, it absorbs more excellent moisture content and thus speeds up the drying process.

The life of the desiccant material depends on several parameters. Some of the main parameters are as follows:

• The dew point temperature within your desiccant dryer
• Contaminants that are present in the system affect the effectiveness of desiccant material
• The humidity level in which desiccant material is operating
• How many cycles to which desiccant material is exposed
• The chemical composition of the material you are going to dry with your desiccant material
• The type of system in which you operate your desiccant material

In general, if you use the desiccant material in the open system, the life associated will be 2 to 3 years. On the other hand, if you operate desiccant material in a closed system where it gets subjected to heating and cooling, the life associated will lie in the range of 1.5 to 2 years.

If you properly maintain the dew point and humidity level for your desiccant material, you can experience a longer lifetime.

Seral types of desiccants exist. Some of the widely used desiccant materials are as follows:

• Molecular Sieve
• Silica Gel
• Clay
• Cao
• CaSO₄

When selecting the desiccant material, you need to focus on the following considerations. These considerations are listed below:

• The capacity of adsorption in low concentrations of water
• Rate of adsorption of particular desiccant material
• Capacity for water
• Separation by molecular sizes
• The capacity of adsorption at higher temperatures

The characteristics of the desiccant as mentioned above materials are listed in the table below:

The most commonly used desiccant material in several industries is Silica Gel. It is non-toxic and has the characteristic of insolubility. Silica gel have not only high moisture adsorption capacity, but you can regenerate it in dryers effectively. Another characteristic that cannot be overlooked is the maintenance of dew points within a desiccant dryer.

So it is recommended that you use silica gel as a desiccant material in your desiccant dryer.

The dew point is a measure of the amount of water vapor in the air. The dew point of dry air is the temperature below which water vapor condenses. If the dew point is not adequately controlled, it may lead to condensation on cold surfaces. For this reason, the dew point must be kept as low as possible.

This is used to maintain humidity at ideal levels in industrial processes in industrial applications, which is necessary for high-end products.

In a desiccant dryer, the moisture-adsorbing material helps remove water from the air, thus improving efficiency. Entering the desiccant dryer from the bottom, the air first passes through a primary desiccant dryer containing large loads of adsorbent material, which removes a large amount of water vapor from the air.

Absorbents, for example, silica gel and calcium chloride, attract moisture based on their chemical or physical properties. Silica gel is the renowned desiccant material that controls the dew point at an optimum level in the desiccant dryer.

The most recommended dew point in desiccant dryers is -30^0, but in ideal conditions, you can reach out to -40⁰. Dew point requirement also varies depending on the type of plastic resin you are drying and the moisture content level inside the material.

The maintenance of your desiccant dryer is most important. You can increase the efficiency of your desiccant dryer and the life associated with your desiccant dryer by following proper maintenance requirements.

There are several easy ways to keep your desiccant dryer running efficiently.

• It is good to replace your desiccant every few years as the effectiveness will decline over time.
• The desiccant dryer should be placed in a well-ventilated place and avoid direct sunlight to make it not reach a high temperature.
• Replace the filter to avoid contamination of the desiccant material
• The desiccant dryer should be cleaned regularly. It would help if you cleaned any accumulations of mildew mold. This could be a simple wipe with a damp cloth, or a spritz of vinegar, rubbing alcohol, or hydrogen peroxide. If your closet smells musty or seems sticky, open the door and let it air out for a while to try to eliminate the musty smell as much as possible.
• You should inspect your desiccant dryer periodically for signs of damage and deterioration. Also, check to see if loose wires lose or broken fans or belts of blowers.
• Do not store the device in areas that are extremely hot or cold. If you live in a humid region, adding more desiccant back into the housing will be helpful to prevent moisture from building up inside.

There are several reasons why you should choose a desiccant dryer. Some of the main reasons are as follows:

At the industrial level, a desiccant dryer improves the end quality of products and reduces multiple defects, including bubble formation in plastic resin and drooling.

A desiccant dryer prevents surface streaks or playing in the products.

This also saves network equipment from frequent failures due to extensive damage caused by moisture. A desiccant dryer can save up to 80% of the energy used in the dehumidification process.

The desiccant dryer is designed for excessive moisture removal that will prolong the life of any desired product.

It can remove water by 100% and make it thoroughly dried. More convenient for working on-site, its drying time is shorter, saving you more time.

Desiccant dryer plays a vital role in reducing bacteria and so on. In addition, this kind of product has the function of sterilization and has a good decontamination effect.

You can use the desiccant dryer to recycle plastic scrap so that you can reprocess it into new plastic products.

Several components make up a desiccant dryer. The main components are as follows:

• Process heater
• Process blower
• Air-to-air aftercooler
• Return air filter
• Honeycomb rotor
• Drying hopper
• Regeneration filter
• Regeneration blower
• Regeneration heater

Several components make up a desiccant dryer. The main components are as follows:

• Process heater
• Process blower
• Air to air aftercooler
• Return air filter
• Honeycomb rotor
• Drying hopper
• Regeneration filter
• Regeneration blower
• Regeneration heater

13  What’ are desiccant dryer solutions from Yushine?

Yushine dryer solutions offer you three different types of dehumidifying or desiccant dryers. These types are as follows:

Yushine dryer solutions offer you three different types of dehumidifying or desiccant dryers. These types are as follows:

2-in-1 Desiccant Dryer

This system is capable of performing 2 functions which is why it is known as 2 in 1 desiccant dryer. It follows the working principle of dehumidification followed by drying.

3-in-1 Desiccant Dryer

The 3-in-1 desiccant dryer can perform 3 functions simultaneously. These functions include dehumidification leading to drying and two-step conveying coming along with a single unit.

Honeycomb Rotor

This type of desiccant dryer uses a honeycomb rotor wheel to keep the dew point below -40⁰, which ensures an air volume supply of up to 4000 m³ / hr. This device also comprises of filter that keeps the desiccant in good condition.

All of the above-listed desiccant dryers also come with temperature and dew point monitors that provide you with real-time metering of these parameters to remain efficient.

Desiccant dryers with conveying also known as 3 in 1 desiccant dryers. They have a compact design and save your space because of transferring feature. They are movable because they come along with wheels in the foundation.

The desiccant dryer can carry out three functions, including drying, dehumidifying, and two-step conveying.

They provide a down blow of air in cyclone form; this prevents heat loss and increases the efficiency of the desiccant dryer. Desiccant dryer with conveying feature has two structures, including an airtight structure and a semi-open structure. You can choose anyone depending on your needs.

You can process highly hygroscopic materials, including PA, PBT, PC, or PET. It can maintain a low dew point and comes along with a microprocessor for better control over operational parameters, including humidity and dew point temperature.