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The Role of Vacuum Tray Dryers

Views: 44     Author: Site Editor     Publish Time: 2022-07-10      Origin: Site

Vacuum Tray Dryers Introduction

Drying is a critical process in many industries, including pharmaceuticals, food processing, and chemicals. The quality and efficiency of drying can significantly impact the final product. Vacuum tray dryers have emerged as a reliable solution for gentle and controlled drying, preserving the integrity of delicate materials while achieving desired moisture levels.


Vacuum shelf dryer


Vacuum tray dryer


Vacuum shelf dryers

What is a vacuum tray dryer ?

Vacuum Shelf Dryers Consisting of a square or round vacuum chamber with customized fixed internal shelves; the wet material to be dried is loaded into pans or trays and manually placed on the shelves of vacuum shelf dryer. The top part of each shelf is flat with a coil jacket on the underside to circulate steam or liquid heating medium for the desired operating temperature.

Due to hundreds of various types of products and demands of inducing and controlling a vacuum environment, almost all aspects of a vacuum shelf drying machine mechanical design and ancillary support equipment can be customized to meet each individual process design needs.

The overall dimension of each vacuum chamber is driven by the required shelf surface area for drying. The shelf size, spacing between each shelf, and selected chamber geometry (square or round) will determine the overall chamber size.

Delicate, heat-sensitive materials are dried safely at extremely low drying temperatures. Operating under vacuum, the product is protected from oxidation and atmospheric contamination and released solvents are fully recovered.

vacuum tray dryer are specified for products requiring uniform, low-temperature drying with no agitation or compression. Among those products are pharmaceuticals, nutraceuticals, vitamin extracts, specialty food items, fine chemicals and glandular products.

Hywell machinery company have the two types of vacuum pan dryers; one is a square tray type vacuum dryer and the other is a circular vacuum dryer. The round shape vacuum dryer cannot load too many tray, so it is more suitable for drying less material per batch.  Specific using of circular shape vacuum dryer or square shape vacuum dryers, Hywell machinery's engineer will give recommendations according to material characteristics and single batch capacity.

The FZG vacuum shelf dryer is one of the more popular vacuum equipment that developed many years ago. But the drying speed of FZG vacuum pan dryer is relatively slow. Hywell has developed a new type high-efficiency vacuum shelf dryer;  the drying efficiency of high-efficiency vacuum dryer is very high and the drying time is 1/3 of the FZG series vacuum tray dryer.

Vacuum Tray Dryers Working Principle 

The working principle of vacuum tray dryers revolves around the process of evaporation. The material to be dried is spread evenly across the trays, and heat is applied to initiate evaporation. Simultaneously, a vacuum pump creates a low-pressure environment, facilitating the removal of evaporated moisture. This combination of heat and vacuum accelerates the drying process while minimizing the risk of heat damage or oxidation.

Vacuum Tray Dryers Advantages 

Gentle drying is a key benefit of vacuum tray dryers, making them suitable for heat-sensitive materials. Unlike conventional drying methods, such as hot air ovens or spray dryers, vacuum tray dryers operate at lower temperatures, reducing the risk of degradation or loss of volatile compounds. This advantage is particularly crucial for pharmaceuticals, herbs, and certain food products.

Vacuum Tray Dryers Applications

Industrial vacuum tray dryers are suitable for drying heat-sensitive raw materials that can decompose or polymerize or deteriorate at high temperatures. Industrial vacuum tray dryers are widely used in pharmaceutical, chemical, foodstuff, and electronic industries. Particularly Industrial vacuum tray driers are suitable for row materials that have the following requirements:

1. Thermal-sensitive raw materials that cannot be dried at high temperatures.

2. Raw materials that are easy to oxidize and dangerous.

3. Raw materials that solvent and toxic gases are needed to recover.

4. Raw materials that have special requirements for crystal shape.

5. Raw materials that have special requirements for the content of residual volatile.

Factors to Consider When Using Vacuum Tray Dryers

To achieve optimal drying results, several factors must be considered when using vacuum tray dryers. First, the material's physical and chemical properties, such as moisture content, particle size, and heat sensitivity, should be assessed. Additionally, the tray design, loading capacity, and uniformity of heat distribution play vital roles in the drying process. Understanding these factors helps in selecting the appropriate drying parameters.


Pan vacuum dryer


Vacuum drying machine


Shelf vacuum dryer

Vacuum Tray Dryers Video

Tips for Efficient and Effective Drying

To enhance the efficiency and effectiveness of drying with vacuum tray dryers, certain tips should be followed. Proper tray loading, ensuring adequate spacing between materials, and avoiding overloading are crucial for uniform drying. Adjusting temperature, vacuum level, and vacuum duration based on the specific material being dried is important. It is also advisable to monitor the drying progress regularly to ensure the desired moisture content is achieved.

Maintenance and Cleaning of Vacuum Tray Dryers

Regular maintenance and cleaning of vacuum tray dryers are essential to ensure optimal performance and prolong their lifespan. This includes periodic inspection of seals, gaskets, and filters to prevent any leaks or contamination. Cleaning the trays and chamber after each use helps remove any residual material and prevents cross-contamination. Lubrication of moving parts and calibration of temperature and vacuum sensors should also be part of the maintenance routine.

Common Challenges and Troubleshooting Tips

While vacuum tray drying machines offer many advantages, they can encounter certain challenges during operation. One common issue is uneven drying, which can be caused by improper tray loading or inadequate heat distribution. To address this, ensuring proper spacing between materials and optimizing heat distribution through tray design or using additional heat transfer aids can help. Another challenge is the formation of product clumps, which can be resolved by implementing intermittent shaking or stirring during the drying process.

Safety Precautions for Working with Vacuum Tray Dryers

Safety should always be a priority when working with vacuum tray dryers. Operators should be trained on proper usage and handling of the equipment, including understanding the risks associated with heat, vacuum, and potential chemical reactions. Personal protective equipment (PPE) should be worn, including heat-resistant gloves, safety goggles, and appropriate clothing. Regular inspection of electrical connections and grounding is essential to prevent any electrical hazards.

Comparison with Other Drying Methods

Vacuum tray dryers offer distinct advantages compared to other drying methods. Unlike hot air ovens, which can cause heat damage or oxidation, vacuum tray dryers provide gentle and controlled drying conditions. Spray dryers, on the other hand, are suitable for large-scale production but may not be ideal for heat-sensitive materials. Vacuum tray dryers strike a balance between efficiency, gentle drying, and versatility, making them a preferred choice in many industries.

Future Trends in Vacuum Tray Drying Technology

As technology advances, there are ongoing developments in vacuum tray drying. Efforts are being made to improve energy efficiency, reduce drying time, and enhance automation and control systems. Integration of advanced sensors and monitoring technologies allows for real-time process optimization and quality control. Additionally, the use of alternative heating methods, such as microwave or infrared, is being explored to further improve drying efficiency and product quality.


Gentle drying with a vacuum tray drying oven provides a reliable and efficient solution for various industries. By maintaining low temperatures and creating a vacuum environment, these dryers preserve the integrity of heat-sensitive materials while effectively removing moisture. Understanding the working principle, advantages, applications, and best practices of vacuum tray drying ensures optimal drying performance and high-quality end products.


Q1: Can vacuum tray dryers be used for drying liquid materials?

A: Vacuum tray dryers are primarily designed for drying solid materials. Drying liquid materials may require additional considerations and specialized equipment.

Q2: How long does it take to dry a product using vacuum tray dryers?

A: The drying time varies depending on factors such as the nature of the material, initial moisture content, and desired final moisture level. It is important to establish proper drying parameters through experimentation and monitoring.

Q3: Are vacuum tray dryers suitable for heat-sensitive pharmaceuticals?

A: Yes, vacuum tray dryers are widely used in the pharmaceutical industry for drying heat-sensitive materials, including active pharmaceutical ingredients (APIs) and granules.

Q4: Can vacuum tray dryers be used for large-scale industrial production?

A: Vacuum tray dryers are commonly used for laboratory-scale and small to medium-scale production. However, for large-scale industrial production, other drying methods such as rotary dryers or fluidized bed dryers are often more suitable due to their higher throughput capacity.

Q5: Are vacuum tray dryers suitable for drying heat-sensitive materials with volatile compounds?

A: Yes, vacuum tray dryers are well-suited for drying heat-sensitive materials with volatile compounds. The low-temperature and low-pressure environments inside the dryer help to preserve the integrity of these compounds, ensuring that the final product retains its desired properties.

Q6: What are some common indicators that the drying process is complete?

A: Several indicators can help determine the completion of the drying process. These include achieving the desired moisture content, observing the constant weight of the dried material, and verifying that the product meets specific quality parameters or specifications.

Q7: Can vacuum tray dryers be used for drying materials with high moisture content?

A: Vacuum tray dryers are generally more effective for materials with moderate moisture content. For materials with high initial moisture content, a pre-drying step or alternative drying methods may be necessary to reduce the moisture content to a level suitable for vacuum tray drying.

Q8: What safety precautions should be followed when operating vacuum tray dryers?

A: When working with vacuum pan dryers, it is important to follow safety precautions. These include wearing appropriate personal protective equipment (PPE), ensuring proper grounding of electrical connections, and being mindful of potential hazards associated with heat and vacuum. Additionally, operators should be trained in the safe operation and handling of the equipment.

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