A tray dryer is used in a number of settings like a laboratory or an industry where certain products like drugs, powders, chemicals, or granules need to be dehydrated.
The working principle behind this instrument is simple and all tray dryers, exporters, and manufacturers are required to follow certain specifications for the manufacturing of these instruments.
All of these will be discussed below in detail.
The Working Principle behind Tray Dryers
A tray dryer has a set of trays that are held in a cabinet by placing them one over the other in a stack and has a source of heated air flow connected to it. In certain indirect tray dryers, the wet product does not come in contact with the air.
Instead, it comes in contact only with a heated wall. The airflow in a direct tray dryer is heated by either gasoline, diesel, or biofuels made from products like rice husk. The temperature inside it is controlled by a thermostat and maintained between 50°C to 70°C.
The uniformly circulated heated air and the constant temperature conditions work on the product and dehydrate it. The forced convection of the hot air removes the moisture and this moisture is simultaneously removed, at least partially, from within the dryer cabinet to aid in the continued dehydration of the wet product.
If the humidity inside the cabinet reaches saturation levels, there will be no more dehydration of the wet product that happens. This is why the moisture-laden hot air has to be simultaneously removed.
For the purpose of even circulation of the hot air, there are fans placed inside the tray dryer cabinet. These fans can circulate the air at about 2 to 5 meters per second. This air picks up the moisture in the surface of the product and carries it away with it.
Due to capillary action, the water from the interiors of the product automatically moves to the surface of the product and is carried away by the continuous airflow inside the cabinet. This process is cyclically repeated until the entire product is dehydrated thoroughly.
The entire process is quite rapid. Since the contact is minimal, the moisture picked up in one rotation of the hot air is very small. Due to this, about 80% or 90% of the same air can be reintroduced with the remaining 10% of air being fresh and free from moisture. Once the product is completely dehydrated, it is emptied from the trays at the dumping station.
Specifications of Tray Dryers
All tray dryer exporters and their manufacturers are expected to follow the Good Manufacturing Practice (GMP) standards. A tray dryer should be made with the dimensions of 70mmx70mmx3mm thick s.s 304 angles.
The heating tube must be of 1 kW each and the total load of a 24-tray dryer should be 6 kW. Air should be circulated uniformly with a power of 1 H.P. The dimensions of the trays should be 32”x 16”x 1/4” and should contain 24 trays. Each rack should have wheels to help slide them in and out.
Advantages of Tray Dryers
When both tray dryers and exporters follow these specifications, the advantages are many. There is efficient fuel consumption as the tray dryer becomes easy to use. This, in turn, decreases labor costs.
The separation provided by the trays also makes it possible to segregate the product into batches. The only disadvantages are the cost and time it takes to do its work.
Hence, the advantages of a tray dryer outweigh its disadvantages, making this very useful in dehydrating large amounts of substances.