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Harper International pusher plate tunnel kilns - are designed to meet the most exacting material processing requirements.  Harper engineering teams marry process knowledge and extensive process engineering capabilities with a history of tunnel kiln design experience.  The Harper advanced technology center and interdisciplinary team of chemical and mechanical engineers and materials scientists are available to explore, develop and scale up new processes to meet the requirements of the most demanding processes. 

Harper specializes in tunnel kilns designed to meet processes requiring precise control of temperature and atmosphere.   Multiple temperature and atmosphere control zones enable tailoring kiln design to meet specific temperature vs. atmosphere requirements.  Multiple temperature control zones as well as control of temperature above and below the load provide optimal temperature uniformity.  Modular construction facilitates modification of the kiln tunnel to accommodate adjustments in process or production rate.

Delicate pressure control within the tunnel kiln provides control of the atmosphere flow path in the kiln facilitating evacuation of volatiles and optimizing atmosphere uniformity.  Harper’s unique gas curtain technology provides zone-to-zone atmosphere definition under specific conditions.  Harpers unique stripping chamber design provides optimal isolation of internal tunnel kiln chamber environment from ambient as well as efficient purging of ambient atmosphere entrained within the load entering the kiln without the use of mechanical doors and seals.

• Temperatures to 2800ºC
• Excellent temperature uniformity
• Electrically heated, Gas fired, or Dual heating systems
• Controlled Atmosphere

• Oxidizing
• Neutral                  
• Reducing

• Nitrogen
• Hydrogen
• Inert Gas

• Purity Control Monitoring

• Multiple atmospheres
• Corrosive atmosphere designs

• Chlorine
• Fluorine

• Sulfur
• Binder removal

• Off-gas handling and treating systems
• Defined residence times and capacity
• Testing and prototyping facilities
• Process modeling and scale up
• Automatic material handling and return systems
• Automatic loading and unloading systems
• Complete systems and turnkey installation

• Energy Efficient Design
• Multi-Zone Temperature and Atmosphere control
• Modular Design
• Process gas circulation and conditioning systems           
• Variable length and width to accommodate product size and capacity
• PLC based instrumentation for process control and data acquisition
• Flow control systems for atmosphere control

• Sintering
• Calcination
• Oxide Reduction
• Carbonization
• Solid-solid reaction
• Gas-solid reaction
• Purification
• Metalizing

• Advanced Ceramics
• Tungsten Carbide
• Soft ferrites
• Nuclear Fuel
• Capacitors, Varistors, Thermistors
• Oxygen Sensors
• Rare earths
• Powedered Metals
• Solid oxide fuel cells
• Solar Cells
• Steatites
• Lighting Phosphors
• Color Phosphors

Harper manufactures a wide range of continuous tunnel kiln designs including:

• Roller Hearth Kilns
• Mesh Belt Kilns
• Car Tunnel Kilns
• Walking Beam Kilns
• Carpet Hearth Kilns
• Harper Hearth

Twin Hearth Pusher Plate Tunnel Kiln with closed loop automation and return conveyor system.

Controlled Atmosphere Pusher Plate Tunnel Kiln with automation and return conveyor system.

Controlled Atmosphere Twin Hearth Pusher Plate Tunnel Kiln with integral multi-zone control binder burn off oven.

GRAPHITE PUSHER THERMAL SYSTEM

The graphite element pusher furnace is used to produce a variety of powders and parts at temperatures up to 3000º C in a precisely controlled atmosphere.  Specially designed heating elements can have a life of 3 to 5 years.  The latest technological advances such as the use of modular carbon-graphite insulation assure you of lower operating cost and greater furnace efficiency. 

(Greater furnace efficiency at temperatures up to 3000º C) 

NEW GRAPHITE HARPER HEARTH  SYSTEM (pdf)

A major innovation in graphite systems technology, the heart of this patented new system is The Harper Hearth Load Carrier.  This reduces load thermal mass, improves temperature uniformity and redistributes compressive stress and wear surfaces away from potentially corrosive/erosive environments.  The Graphite Harper Hearth has energy recuperation and single point access that significantly improve process economics over existing ultra-high temperature pusher and other furnace technologies.  Applications include gas-solid and solid-solid chemical reactions and pressureless sintering at temperatures up to 3000º C.