Atmosphere rotary furnace

The rotating structure moves powder through the heated tube. Suitability has to be judged against powder flow behaviour, particle size and the intended thermal treatment.

Please provide the material, target temperature, feed rate and gas requirement. Our engineering team confirms the tube, the heating system and the gas-sealing arrangement from that information.

Selection check: when a rotary furnace fits, and when it does not

It fits when: the material is a powder or a granulate and no saggar is needed; every particle has to be exposed to the same temperature, which means continuous tumbling; the material agglomerates or fuses when it sits in a static pile; in- and outfeed should be continuous and automatic.

It does not fit when: the parts are flat, long or fragile — tumbling destroys them; the material is highly abrasive and low contamination is required — the tube liner and the lifters wear, and the liner material has to be assessed up front; dust emission limits are strict and no off-gas treatment is planned.

The one-line test: if the material is loose — powder or granulate — a rotary furnace belongs in the discussion. If it is a whole part, it does not.

How the specification is fixed: work back from the material

1. Tube diameter and fill ratio. Fill ratio is normally taken as 10–20 % of tube volume. This is an industry rule of thumb; the actual figure depends on flow behaviour and angle of repose. Too high and the bed stops turning, which turns a rotary furnace back into a static one. Too low and capacity is wasted.
2. Rotation speed and residence time. Speed is variable-frequency controlled, and residence time results from speed, tube inclination and length together. If the process needs hours, all three have to be combined — turning the speed knob alone will not do it.
3. Liner material. It touches the product directly. Choose by abrasiveness and by whether metal contamination matters.
4. In- and outfeed screws. Inclined screws are what make the process continuous. Screw angle and sealing decide leakage and air ingress.

Common questions

Q: What fill ratio should we actually use? Start from the 10–20 % range and confirm the value with a flow test on your own material. A high angle of repose and poor flow mean taking the lower end.

Q: Will the gas flow carry powder out of the tube? Yes, and this is a common issue with rotary furnaces. The answer is a dust collection or settling stage at the outlet, sized against the powder loss you can accept.

Q: Can it run under vacuum? Vacuum is listed for this model, so yes — but the sealing arrangement and the tube's pressure resistance have to be designed for it. A standard atmospheric model cannot simply be re-labelled.