The belt itself usually has two layers; one provides linear strength and the other comes into contact with the substance it is transporting. The belts are typically made of rubber, plastic, mesh, cotton or silicone.
Wet materials are carried through conveyor dryers on conveyor belts at the appropriate speed and are dried right on the belt. Conveyor dryers can handle unique shapes and particle sizes including granules, gels, pastes, flakes, slurries, solids and large items. The conveyor belt can be changed to accommodate the material; for example, wheat germ would travel on a solid rubber belt whereas strips of seaweed could be dried on a metal mesh belt for maximum heat absorption.
Conveyor dryers are almost always continuous dryers because the looped belt does not require any stoppage time for loading or set-up; products can be placed on the belt at one end, travel through the dryer and then removed at the other end. This process is beneficial for many industries and has applications in the food, agricultural, apparel, lumber and chemical industries, setting wet ink on screen-printed apparel, curing treated lumber, turning wet paste into dry grains and drying paper.
Though conveyor dryers typically use the belts themselves as drying surfaces, there are other options. Some belts are equipped with hooks for items that cannot be in contact with a flat surface because they require coating. The items hang from the belt and are dipped or sprayed in the finish before entering the dryer. Most dryers are rectangular and made of a strong metal like stainless steel.
The conveyor belt runs through the center, and inside the housing are the heat sources directed towards the belt. The size and shape of conveyor dryers varies depending on its application. For screen-printing, a 52 inch conveyor belt is sufficient to cure ink on a t-shirt while other materials take days to travel through a dryer hundreds of feet long. Another factor is what kind of method is used to achieve evaporation and remove moisture.
The most common way is an air dryer in which hot air comes into direct contact with the substance or items. Infrared dryers use thermal energy from a certain wavelength to dry from the inside out, and fluid bed dryers require a belt with a permeable surface to support the materials as heated gas fills the space. These main methods of drying can be used in combination with a conveyor belt to eliminate batch drying and speed up the process.