Rotary Tube Furnaces

Every Harper rotary tube furnace is designed for the customer’s unique specifications. We bring innovative solutions to designs for continuous processing of advanced materials such as granular, powder, or particulate aggregates in high purity and specialty atmosphere environments at temperatures up to 3000°C.

See how our state-of-the-art Rotary Furnace designs offer the most advanced features for your production line. Click below for an interactive tour, or watch the video here.

Harper rotaries offer exceptional versatility, reliability and energy efficiency. Our designs include multiple patented features that enable better mixing, resulting in improved heat transfer and mass transfer. The absence of moving parts in the tube support system provides a simple, reliable, robust design that enhances scalability. Additionally, the tumbling action of the product within the tube results in high degrees of temperature uniformity and gas-solid contact, producing a more homogenous product, reducing processing times and increasing production rates.

Modern applications of advanced materials require the performance and safety that is only achieved by maintaining ultra-high purity powders. Harper’s rotary systems consider these high purity applications from beginning to end: material in-feed valves and feeder, high-heat reactor tube, product cooling tube, and material discharge valves and collection. We have the experience to engineer these components, whether they are specialty alloys, fused silica quartz, or technical ceramics such as alumina or silicon carbide, to achieve a chemically inert environment all while maintaining a gas-tight and dust-tight system for your advanced materials.

We also offer the unique ability to accommodate a variety of process atmospheres that others cannot. Our excellent seal designs and focus on atmosphere control includes system integration of atmosphere recycle systems, off-gas abatement systems, and controlled atmosphere mixing for tailored process control. These atmospheres include flammables and toxic gases – hydrogen, nitrogen, argon, air, oxygen, ethylene, methane, CO2, CO, chlorine gas.

Harper approaches the design of a rotary furnace and calciner as a complete system, with the ability to incorporate process control systems, gas treatment and handling, turnkey installation and complete field commissioning. Field service can incorporate control instrumentation integration and programming as well as process engineering optimization and support.

Harper Rotary Furnace Design Enhancements

  • Rotary Tube FurnaceRiffle flights – provide axial mixing for processing at a fixed average composition and are excellent for moderating exothermic reactions or continuous in-line mixing. Riffle flights enable similar benefits as standard continuous stirred tank reactors (CSTR), but in a continuous rotary tube format.
  • Helical flights – convey material without back-mixing. Utilized for processes that require narrow residence time distributions.
  • Cross Flow System – coarse, free-flowing material can be heated and reacted with through-flowing gas. Gas flows locally through the solid material path while globally flowing co-current, counter-current – or combinations thereof – to material flow, providing superior gas-solid contact.
  • Advanced Sealing System – patented rotary reactor sealing system provides optimal rotary tube furnace atmosphere integrity with minimal gas consumption

Harper Rotary Furnace Capabilities

  • Rotary FurnaceTemperatures to 3000°C
  • Tube diameters to 60 inches (1.5 meters)
  • Electrically heated or gas-, oil- or dual-fuel fired
  • Controlled atmospheres including flammables and toxic gases  – hydrogen, nitrogen, air, oxygen, ethylene, methane, CO2, CO, chlorine gas
  • Variety of tube material designs – alloys, mullite, alumina, silicon carbide, quartz, graphite
  • Process gas circulating and conditioning systems
  • Automatic material handling and return systems
  • Defined residence times
  • Advanced seal design
  • Automatic lubrication
  • Feed level detection

Typical Rotary Furnace Applications

  • Harper RotaryPyrolysis
  • Drying
  • Calcination
  • Reduction
  • Controlled oxidation
  • Carburization
  • Solid-solid reaction
  • Purification
  • Waste remediation

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