Those hollow rolls are used in many industries such as :
Plastic industry …
The purpose of this roll is either to evaporate the remaining water or to maintain the temperature of the product by injection of steam under pressure through the cast iron lining.
The treated product is progressively dehydrated when passing on the dryer roll.
In the paper and food industry, the water is evaporated when the product passes on the rotating drum. The product is then removed either thanks to a blade or to a combination of other rollers in the manufacturing line afterwards.