Thru-Air Dryers and Heat Setters

There are two designs of thru-air dryers and heat setters. There is the horizontal conveyor belt design system; and the perforated drum or multiple drum design system. Both are designed to dry and/or thermally bond fibrous web structures. Drying is required on fibrous web structures that have been mechanically bonded by high pressure water jets or steel needles. It is also required when the fibrous web structure is chemically bonded and a certain percentage of the latex solution is water that must be removed. This is accomplished by heat and air. The heat comes from either gas fired burners, steam heated radiators, or an oil heated system. The circulating air thru the individual heated chambers is supplied into the heated chamber from circulating fans and can be either a thru air design where the air passes thru the fibrous structure, or an air impingement design where the air is blown on both sides of the structure when the material is not air permeable. In the products where the fabric is stable and dry, the heated air will heat set the fibers in order to reduce or eliminate shrinkage of the finished material following treatment processes.