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Drying System

Types of drying equipment

Types odrying equipmentf

Types of hot-air nozzles

  1. Jet type
    • Large heat transfer coefficient because of strong power to break air laminar film
    • Powerful to push substrates at high wind velocity
  2. Positive-pressured air floating type
    • Ordinary air floating type
    • Nozzles are alternately installed on both sides of substrates
    • Correlation between minimum tension of substrates and wind velocity at the nozzles, substrate width and drying time (EPC becomes ineffective)
  3. Negative-pressured air floating type
    • Substrates can be fed for single side
    • Some substrates may get finely wrinkled
  4. Negative-pressured nozzle + roll type
    • Substrates can be fed for single side
    • As substrates are fed on rolls, wind velocity at the nozzles can be set in a wide range
    • As substrates are received on the rolls, they do not easily curl
  5. Punching hole type
    • Wind can softly blow against substrates
    • Full punching type may cause drying unevenness in lateral direction as the return route of air is not fixed
  6. Parallel flow type
    • Small coefficient of heat transfer
    • Easy maintenance because of sufficient space around substrates
    • Lateral unevenness may occur
    • Greater risk is expected when using flammable solvent, because dried solvent gas flows in laminae

Features of drying equipment

  1. Roll support
    • As the hot-air drying system and substrate feeding system are separately operated, conditions for drying and the tension of feeding can be set in a wide range
    • As rolls contact substrate, substrate may receive unfavorable influence from heated rolls
    • Wrinkles may occur in lateral direction as strains are not easy to relax (especially edge parts)
    • Maintenance for rolls is required (dirty rolls easily scratch products)
  2. Air floating
    • As hot-air drying system section also works for feeding substrates, the range of wind velocity at the nozzle (drying capacity) may sometimes be limited
    • As it is an air support system, substrates of weak elasticity and large strain may be flattened
    • Cleanness in the drying zone is jeopardized as the hot-air system is installed in both upper and lower sections
  3. Conveyor support
    • As it continuously receives substrates, it can also feed substrates of weak elasticity
    • Conveyor produces dust and cleaning can be troublesome
    • Conveyor joints may be transcribed on products
    • Wrinkles may occur as strains of substrates are harder to relax
    • Additional energy is required for heating conveyor
  4. Super clean system
    • It can combine roll support type and air floating, or independently meet clean specifications of nozzle class 100 installed in the dryer
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