Contactless Web Turning, Drying and Cooling

Transcription

1 Developments of the ModuleDryer System for Converting and Paper Applications Contactless Web Turning, Drying and g, y g Cooling

2 Background Increased production and product quality is a key goal of any converter and paper maker, and is often constrained by existing machine configurations. Drying is often a fundamental shortcoming of any machine A unique drying and cooling system was developed to meet increasing quality and production requirements ModuleDryer simultaneously turns and dries the sheet with superior web stability and high drying rates. The ModuleDryer reduces open draws, gives shorter machine lenghts and more capacity within the same available length. The ModuleDryer will also cool the web in the same enclosure as the dryer

3 ModuleDryer The ModuleDryer development combines traditional technology which has been adapted to form a new concept in sheet drying and cooling. This includes: Non Contact Sheet Turning Non Contact Flotation Drying and Cooling Infrared Drying in conjunction with traditional Floatation Drying

4 Air Turn Non-contact sheet turning established technology (Spooner has > 300 Installations). Recent developments include enhanced spreading features turning of porous webs.

5 Air Flotation High drying performance is required together with stable non-contact flotation and high h energy efficiency. i High Performance Compact Dryer gives shorter machine lengths by combining air flotation and air impingement nozzles and operates at high air velocities and air temperatures. This gives 32% more drying compared to traditional systems. stems

6 Some Disadvantages of Traditional Coating Line Each coater station is different Wasteful of factory space Complicated machine framing Many web path rolls and associated drives Complicated ddrive and dtension control system Problematic web path for runnability and web feeding

7 The Module Dryer Concept Airturn Section with AirCap Off-machine coater Air Flotation Dryer (SpoonerFloat or HPC) Airturn Section with AirCap Pre-Heat Section Tension Control Air Cooling Section Position for Back Coat Position for Top Coat Drive or Cooling Cylinders

8 The Module Dryer Concept On- Machine Coater Hockey Stick Configuration

9 ModuleDryer Layouts

10 Key Components of the ModuleDryer - Air Turn Conventional Air Turn cannot be used for high performance and consistent drying A conventional air turn relies upon the generation of a cushion of air to offset the tension component within the running web Drying is limited i dby cushion to nozzle pressures.

11 Recirculating Airturn Flotation Nozzle Return Air Gap RCAT

12 RCAT Cushion Pressure Profile Flotation Nozzle Return Air

13 Tension Indication No moving parts Independent of machine width Very accurate Broad operating range Air Turn is a Transducer Flotation Nozzle Return Air

14 Key Components Recirculating Air Turns Recirculating air turns developed to ensure: Non contact turning at specified web tensions. Ensure heating / drying performance is achieved. Air required for web support travels in a radial manner into recycle and generates a neutral effect ect on CD moisture profile.

15 Key Components of the ModuleDryer - Air Flotation

16 Air Flotation Air Flotation Dryers are installed after one or two sided d coating stations to provide quick coating moisture removal & stable non-contact flotation. High Performance Compact (HPC) air flotation dryers are in operation with proven water evaporation rates exceeding 140 kg/m 2.hr. The HPC gives an increase of 32 % over the conventional flotation system. The HPC can produce an effective evaporation rate which is 5-10 times greater than contact cylinders.

17 Air Flotation Nozzles Spooner Float (SF) HPC (32 % increased Drying v SF)

18 High Performacne Air Flotation Gas or steam heating 70 to C air temperature Air velocity up to 80 m/sec Evaporation rates exceeding 140 kg/m 2.hr Excellent performance at low tension

19 Key Components of the ModuleDryer Air Caps The change of angle in a stable non contact manner is achieved by the recirculating i air turn. Equal drying rates to both sides of the sheet are often required: Impingement air cap gives opposing heat and mass transfer to match that of the recirculating i air turn. Flotation characteristics and web clearance must remain unaffected.

20 Beta Site Module Dryer

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22 Conclusion ModuleDryer technology has fast become an established technology that brings significant ifi benefits to converting and paper producers. Complete understanding of the individual components is required in order to integrate them successfully into a complete, drying system. The ModuleDryer provides high stability, contactless flotation while achieving uniform, high performance drying. This results in improved machine runability with reduced downtime and web breaks.