Drying Equipment
A specialized heating chamber located immediately after the pad mangle reduces the moisture content of the wet fabric before high-temperature fixation. In continuous polyester dyeing, a thermosol pre-dryer utilizes infrared radiation to dry the fabric to a safe level where the dye particles can no longer migrate. This equipment prevents the surface defects that occur during rapid hot-air drying.
System Mechanism
The wet fabric enters the chamber where it is exposed to controlled infrared radiation from gas or electric emitters. This energy heats the water within the fabric, causing it to evaporate from both sides of the sheet without generating strong air currents. By avoiding high-velocity air, the thermosol pre-dryer minimizes the local temperature differences that drive capillary flow.
The fabric exits the chamber with a residual moisture content of about twenty to thirty percent, which is low enough to prevent dye migration during the subsequent hot-air fixation step.
Operational Control
Adjusting the power output of the infrared burners ensures the fabric exits the chamber with the target moisture level. Technicians mount non-contact infrared sensors at the chamber exit to monitor the surface temperature of the fabric. The thermosol pre-dryer is integrated with the main line drive to ensure the burners turn off or pivot away when the line stops.
Operators clean the burner faces regularly to prevent uneven heating zones across the fabric width.
Process Constraint
This equipment is expensive to install and maintain compared to standard hot-air dryers. The high temperatures involved can also cause heat-set defects in synthetic fabrics if the dwell time is not precisely controlled.
