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Tray Dryer vs Vacuum Tray Dryer

May 18, 2022

Tray and tunnel dryers as well as spray, drum and freeze dryers are used in food drying processes. Wet chemicals, powders and APIs can be dried with ease using tray dryers.


A simple tray dryer is a box-shaped cabinet with shelves stacked one on top of another with a series of trays on top. Unlike an oven, which may have heaters mounted in the bottom of the cabinet or on the walls, a tray dryer draws heat from circulating warm air. One or more fans blow the heated air across the trays.


The best tray dryers are those that allow you to adjust the airflow over the trays. The material to be dried is spread out on a tray that may be attached to the paper. Disposable paper is used as a pallet liner to reduce cleaning time and avoid contamination. Trays are usually supported by wire mesh or perforated steel layers.


The latest tray dryers use strategically placed deflectors to drive air from one tray in opposite directions through the trays above, thus achieving the same temperature throughout a well-insulated cabinet.


Air flowing through the trays in opposite directions maintains uniformity of flow and helps maintain consistent temperatures. The air can also be reheated before passing from one shelf to the next. Each shelf loses some heat (latent heat of vaporization of water expelled from the solid material) as the air passes through.


In a tray dryer, hot air is continuously circulated to remove moisture from the material in the tray by forced convection. Moist air is removed from the cabinet and discharged at the same time.


After wet granulation, drying is usually used. This is the process of breaking down the tablet mixture into granules by turning it into a paste with water. Granulation improves the homogeneity and flow of the material during the tablet pressing process.


Tray Dryer

Applications of tray dryer

Use it to dry viscous materials.
Can dry crystalline or granular materials.
Wet materials, pastes, powders and chemicals can be dried using it.
Tray dryers can be used to dry a variety of micro devices.


Vacuum Tray Dryer

The vacuum tray dryer is mainly used for drying high quality, temperature sensitive and oxygen sensitive items. It is ideal for drying hygroscopic materials with very low residual moisture. For lumpy, sticky or low porosity products, the vacuum drying cabinet is often the only option.


The vacuum dryer is shaped like a box, with trays loaded and unloaded through a door with a vacuum seal around the edges, similar to a regular tray dryer. The trays are placed on top of multiple heating plates that are stacked one on top of the other.


Since the trays are placed directly on the heating plates, their surfaces should be as smooth as possible for efficient heat transfer.

The heat required for drying is provided by the hot water, steam or oil flowing inside the heating plates.

Circulating fluid can also be used to heat the cabinet walls to prevent water condensation.

The heating plate indirectly heats the water. The heating plates provide indirect preheating. The dryer is preheated at atmospheric pressure prior to loading the material.


Only after all individual product trays have reached the same temperature is the cabinet emptied and drying begins.

The heating temperature of the vacuum dryer can be considerably higher than that of the air dryer, ranging between 800°C and 1100°C. In some systems, temperature and vacuum profiles can be automatically programmed.


Are you seeking excellent processing equipment?

Huoshi is one of the top manufacturers of vacuum tray dryers. For more information about the difference between tray dryer and vacuum tray dryer, welcome to contact us at +86 139 0117 1712 or write to us at hsjx@innovation4food.com. We will be happy to help you out!