Monitoring and controlling moisture during carpet and textile drying

摘要

Industrial dryer/moisture control is usually performed by feedback type systems, i.e., sensors indirectly measure moisture content (MC) of the product after it leaves the dryer, or exhaust temperature from the last zone is used as an indicator of the existing MC. Such a control system is inherently weak because of the (open quotes)after-the-fact(close quotes) nature of the MC data. A feedback system may be improved by adding feedforward loops to handle disturbances to the system, e.g., variations in entering MC and feed rate. Such additions to the control system are expensive and require higher expertise for operating and maintaining. If the MC of the product could be measured inside the dryer, a control system could be offered that would be superior to feedback/feedforward types. This has not been possible up to this time because no MC sensor was capable of withstanding the atmosphere inside dryers. Moreover, the sample size would not have been large enough to be representative.