There are three basic types of desiccant dryers used by plastics processors:
The first two types use desiccant beads and the third type uses a pure crystalline molecular sieve desiccant that is grown onto a substrate.
WHITEPAPER: Troubleshooting Guide for Wheel Dryers
The simple troubleshooting tips in this whitepaper will help to keep your wheel dryer up and running at peak performance.
The purpose of the desiccant, in all case, is to remove moisture from the process air stream. If the desiccant is doing its job and the heaters and blowers are working as designed, the dew point of the process air is reduced to -40 degrees. This is required for many of the engineering grade materials in use today.
It is important to avoid contamination of the desiccant:
Desiccant beads break down faster because:
Desiccant wheels work longer and more efficiently:
It's time to replace desiccant beads when:
Replacement of desiccant beads can be a labor-intensive job:
NOTE: Smaller twin tower dryers (up to 50 lb./hr. throughput) offer ready-made desiccant cartridges, making replacement far easier.
Multi-bed Carousel Dryers use less desiccant than dual bed dryers but:
Desiccant wheel replacement should be considered when:
Desiccant wheel replacement:
Wheel/Rotor Dryers provide the longest lasting desiccant medium on the market today and therefore require the lowest frequency of replacement than any other type of desiccant dryer. The wheel technology does not employ desiccant beads, but pure molecular sieve desiccant that is permanently bonded to the air-passing corrugations of the wheel element. These corrugations are less likely to trap dust and the desiccant cannot break down over time, so desiccant life is greatly enhanced. If/when the desiccant stops performing its moisture absorbing task, the wheel assembly itself, complete with desiccant medium and its cylindrical enclosure, and on some models, its end caps and drive system, is replaced as a complete unit. This complete replacement assures the user of a 100% restoration of drying capability, with no concerns over quantity of desiccant or even the rotation of the assembly.