Harper Tunnel Kilns

Pusher plate tunnel kilns

Photo - Pusher Plate Tunnel Kiln with purge chambers

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 our interdisciplinary team of chemical engineers, 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 tunnel kiln 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. Harper's 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.

Harper manufactures a wide range of continuous tunnel kiln designs:

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

Photo - Tunnel Kiln with atmosphere control

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

Photo - Pusher Tunnel Kiln combining binder removal and sintering

Capabilities
• 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

Features
• 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

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

Materials Processed
• Advanced Ceramics
• Tungsten Carbide
• Soft Ferrites
• Nuclear Fuel
• Capacitors, Varistors, Thermistors
• Oxygen Sensors
• Rare Earths
• Powdered Metals
• Solid Oxide Fuel Cells
• Solar Cells
• Steatites
• Lighting Phosphors
• Color Phosphors

Greater furnace efficiency at temperatures up to 3000ºC

Greater furnace efficiency at
temperatures up to 3000°C

Photo - High Temperature Graphite Pusher Tunnel Kiln

Graphite Pusher Thermal System

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

New graphite Harper hearth system

Photo - Harper Hearth technology for energy efficiency and high purity application

New Graphite Harper Hearth

A major innovation in graphite systems technology, the heart of this patented new system is the Harper Hearth Load Carrier.
It 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 3000ºC.