Salient features of IR dryers

• Approved by various prestigious installations throughout India.
• Indigenously designed to meet world standards.
• World class, reputed quality infrared emitters are used.
• Steel construction
• High intensity of IR radiation up to 600 KW / m2
• Gold or white coated reflectors.
• Quartz built sheet cover which is transparent to infrared radiation protects the emitters from splashes and easily cleanable.
• Air cooling enhances the life of the component.
• Air impingement and exhaust of vapours for increased efficiency.
• Compact, typically 0.5 m in the direction of sheet travel (inclusive of exhaust)
• Immediate 'on' and 'off' switching of emitters or Thyristorized (SCR) power regulator for step less power variation.
• Automatic safety interlocks against breakage in web, machine stoppage, blower failure etc.
• Trained service engineers for service backup.
• Readily available spares.

Constructional Features: The light weight IR Dryer is designed for optimum energy utilization and its pivoted design makes it suitable for installation in any position or direction. It can be swivelled at any angle to suit the sheet run even after installation. For ideal coating application, the frame has been designed in such a way that it can be totally enclosed to prevent any external airflow. The rugged steel construction prevents any cross sectional deformation and corrosion. The Short Wave IR Dryer can be applied to any existing machine without or no modification due to its compact size.

IR emitters: The IR Emitters are uniquely designed to facilitate universal mounting. The lamps are placed closer to give high heat intensity. The response to the 'On' and 'Off' switching is very quick as the shortwave IR energy is highly penetrable.

Gold Coated Reflector: Gold having a reflectivity of 99% makes the gold-coated reflectors at the back of the IR Emitters highly efficient. The sheet easily reflects the shortwave IR as not all the energy enters the sheet at once. The gold reflector reflects all the energy without being absorbed till it finally enters the sheet.

Gold Coated Reflector: Gold having a reflectivity of 99% makes the gold-coated reflectors at the back of the IR Emitters highly efficient. The sheet easily reflects the shortwave IR as not all the energy enters the sheet at once. The gold reflector reflects all the energy without being absorbed till it finally enters the sheet.

Air circulation System: There is a layer of air formation near the sheet which rapidly becomes saturated due to the moisture released from the sheet at this close distance. This prevents rapid evaporation. If this layer of air is replaced by fresh air, then only the evaporation becomes more rapid till this process absorbs all the heat radiated form the sheet. The maintenance of thermal efficiency, curl prevention and uncontrolled sheet temperature variation an efficient air management is essential. The blower situated at the bottom of the dryer pumps in fresh air from outside which is blown on the reflector and the gap between the reflector and the quartz plate. The air cools off the lamp seals and gold-plated reflector and the heated air moves up the top of the dryer and on the web by means of duct provided at the top. This air ventilation system helps in maintaining the heat build up by cooling the IR Emitters. The air can be made to travel parallel to the sheet and retrieved for the downstream side of the frame depending upon the application. The hot air is impinged on the sheet in the form of jet to break the surface tension of the water molecule to increase the rate of evaporation. The impinged air is blown on the web is such a velocity that it hits the boundary layer of air with great force and makes room for fresh hot air to move rapidly along the surface of the sheet. The vapour laden air is removed by means of exhaust to maintain low level of moisture near the dryer for higher efficiency of evaporation.

Front Plate: The quartz plates in front of the emitter prevents any splashes, withstand the thermal shock, prevents dust to lodge on the gold-plated reflector and controls the impinged air flow. The coating splatter can very easily be removed from the plate. It helps to reduce the maintenance and replacement cost to a large extent giving it an outstanding durability.

Process Control: The heater module can be powered to selectively remove specs of moisture profile by emitting variable amount of infrared energy across the sheet. It can also be powered to for incremental drying on paper machines or coating applications. The IR Emitters are placed closely to achieve higher heat density which has been optimized for maximum drying capacity with long service life. All the energy from the tungsten filament is converted into radiant energy peaking at the level of 1.2 micron range. The IR Dryer is provided with Thyristorized Power Regulator for step less variation in power accompanied by power savings. The power varies proportionally with the change in speed, gsm, solid and moisture content in the web.

Safety features of IR dryer:

• The break in paper web is detected by a break detector and the heating system gets switched off automatically.
• The speed sensors are fitted on the machine to automatically change the heat intensity.
• The Reflector temperature sensors continuously monitors the temperature of the Reflector and sounds an alarm when the threshold limit is jumped leading to tripping of the system.
• The air pressure in the duct is monitored for a fall below the pre-decided level at which the alarm is sounded and the system trips off.
• Emergency switch off

Other Application of Infrared Dryers in the paper industry

• It can be used for modifying the viscosity of the water so that more water is squeezed out in the press before the final press section.
• At the last stage of the paper machine, the efficiency of the steam cylinder is low due to reduced rate of evaporation at low moisture levels. It can be used as Booster at this stage as the efficiency of the IR heating is still very high and another compact IR Dryer can improve the speed remarkably.
• Edge Correction The IR cassettes can be used to direct extra heat on the edge to improve output when the edges of the paper are not dried properly and need to be trimmed.
• Correcting Moisture Profile To make the zone connected separately to a regulator, each zone heating about 75 mm to 150 mm width of paper.