Hot-Wall Retort Furnaces up to 1100 °C

They are perfectly suited for various heat treatment processes requiring a defined protective or a reaction gas atmosphere with a slight overpressure.

Process Control

Function and equipment

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These gas tight retort furnaces are equipped with direct or indirect heating depending on temperature. They are perfectly suited for various heat treatment processes requiring a defined protective or a reaction gas atmosphere with a slight overpressure. These compact models can also be laid out for heat treatment under vacuum up to 600 °C. The furnace chamber consists of a gas tight retort with water cooling around the door to protect the special sealing. With the corresponding safety technology, retort furnaces are also suitable for applications under reaction gases, such as hydrogen or, in combination with the IDB package, for inert debinding or for pyrolysis processes.

Different model versions are available depending on the temperature range: 

Models NRA ../06 with Tmax 600 °C

  • Heating elements located inside the retort
  • Retort made of 1.4571 (X6CrNiMoTi 17-12-2)
  • Air circulation fan  and baffle for directed gas flow
  • Insulation made of mineral wool
  • Furnace temperature control with measurement inside the retort

Models NRA ../09 with Tmax 900 °C

  • Design like models NRA ../06 with following differences:
    • Outside heating with heating elements around the retort
    • Retort made of 1.4828 (X15CrNiSi 20-12)
    • Multi-layer refractory insulation and micro-porous panel material
    • Furnace temperature control with measurement outside the retort

Models NR ../11 with Tmax 1100 °C

  • Design like models NRA ../09 with following differences:
    • Retort made of 1.4841 (X15CrNiSi 25-21)
    • Without gas-circulation  and baffles
    • Welded support brackets

Standard Equipment

  • Compact design with integrated control and gas supply (up to retort furnace NR(A) 700/..)
  • Exclusive use of insulation materials without categorization according to EC Regulation No 1272/2008 (CLP). This explicitly means that alumino silicate wool, also known as “refractory ceramic fiber” (RCF), which is classified and possibly carcinogenic, is not used.
  • Swivel door hinged on right side
  • Open cooling water system
  • Control divided into several heating zones
  • Temperature uniformity up to +/− 8 °C according to DIN 17052-1 in the empty work space see page 85
  • Gas supply system for one non-flammable protective or reaction gas with flow meter and magnetic valve
  • Defined application within the constraints of the operating instructions
  • NTLog Basic for Nabertherm controller: recording of process data with USB-flash drive
  • Controller P570

Additional equipment

  • Upgrade for other non-flammable gases
  • Mass flow controller MFC
  • Process controls H3700, H1700 (PLC) including remote maintenance module
  • Temperature control as charge control with temperature measurement inside and outside the retort
  • Indirect and/or direct cooling
  • Heat exchanger with closed-loop cooling water circuit for door cooling
  • Oxygen sensor and dew point sensor
  • Parallel swing door or electric bayonet catch
  • Retort, made of 2.4633 for Tmax 1150 °C
  • External switchgear with or without cabinet cooling
  • Charge support or custom-built charging trolley
  • Temperature uniformity optimized according to DIN 17052 or AMS2750G to +/− 5 °C in empty work space
  • Process control and documentation via VCD software package or Nabertherm Control Center (NCC) for monitoring, documentation and control

Technical specifications

  NRA ../06 NRA ../09 NR ../11
Tmax in °C 600 900 11001
Atmosphere circulation
Operation with non-flammable protective gas
Operation with air/oxygen2
Operation with flammable gas3 5
Inert debinding IDB3
Low vacuum < 10 mbar4
Fine vacuum > 10-3 mbar4
High vacuum < 10-4 mbar4 5
Retort Heating outside/inside6 outside outside
1Up to 1150 °C with 2.4633 as retort material without a circulation fan
2Increased wear on the retort and the attachments
3Only in connection with the corresponding safety package
4Up to 600 °C vacuum operation; 650 °C with 2.4633 as retort material without a circulation fan
5Only if heated from the outside
6Only available from size NRA 300/06 on

 

Model Outer dimensions1 in mm Work space dimensions in mm Useful volume Connected1
  W D H w d h in l load in kW
NR(A) 20/.. 11002 1600 1700 225 400 225 20 34
NR(A) 40/.. 12002 1600 1900 325 400 325 40 34
NR(A) 80/.. 12002 2000 1900 325 750 325 80 44
NR(A) 100/.. 14002 1800 2100 450 500 450 100 64
NR(A) 160/.. 14002 2100 2100 450 800 450 160 74
NR(A) 300/.. 2200 3100 2600 590 900 590 300 157
NR(A) 400/.. 2200 3400 2600 590 1200 590 400 187
NR(A) 500/.. 23003 3300 2700 720 1000 720 500 217
NR(A) 700/.. 23003 3500 2700 720 1350 720 700 287
NR(A) 1000/.. 23003 3600 2800 870 1350 870 1000 307
1Outer dimensions and connected load of models NR ../11
2Outer dimensions plus separate switchgear with gas supply package for flammable gases or PLC control
3Outer dimensions plus separate switchgear

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What furnace is the right choice for this specific process? This question cannot always be answered easily. Therefore, we have set up our modern test center which is unique in respect to size and variety. A representative number of furnaces is available for tests for our customers.