5. Will optimising the dryers, affect the drying efficiency?
Recirculation itself does not affect drying efficiency. Although, 25%LEL appears to be a high concentration it is actually very low as %vol. It is the air that achieves the drying which, for example, might reduce from 99.6% to around 99.2%vol – the difference is negligible.
Solvent content in recirculated air is almost negligible.
As part of the optimising process, EPM rebalance the dryers which can make a significant improvement to the drying efficiency and speed. The dryer nozzles should be at a given distance from the web and set to the correct nozzle velocity – not too high or too low. Web speed sometimes can be increased by up to 15% simply by rebalancing the dryers.
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