Patented CARBOJET® gas injection technology that can improve the productivity of heat treatment furnaces without the use of circulation fans will be introduced by Linde for the first time at Heat Treat 2015, booth #248.

The gas mixing technology is ideal for upgrading a variety of furnaces including roller hearth, pusher, rotary-retort and pit furnaces. Ultra-high-speed injection of a gas or gas mixture through special CARBOJET lances improves gas and atmosphere flows and circulation. This includes both the better mixing of the injected gases with the furnace atmosphere, and better movement of gas flows within the furnace.

“CARBOJET® technology has already proven successful in many heat treatment operations in Europe because rapid gas injection and homogenous mixing are hallmarks of process efficiency and product quality,” stated Grzegorz Moroz, program manager, heat treatment and atmospheres, Linde.

Specific advantages will depend on the type of heat treatment furnace. In continuous furnaces, for example, CARBOJET gas-injection technology offers a variety of benefits including: improved carbon transfer and homogenisation, more intensive heat transfer with improved convection, better residue burn off at front of furnace, reduced soot formation, better cooling zone performance and quicker conditioning when switching atmospheres.

Benefits at a Glance

• For roller hearth furnaces: With lances positioned at the inlet, improved heat transfer offers potential to increase productivity by 10%. Minimises soot formation, improves reproducibility of gas analysis. Potential to increase productivity in cooling zone up to 35%.

• For rotary-retort furnaces: Better atmosphere mixing, minimises formation of soft spots, increases throughput, longer retort life. Offers potential to increase output of bulk goods by about 20%.

• For pit furnaces: Atmosphere circulation fan could be eliminated, uniform heating and more uniform carburising, annealing, nitriding leads to up to 20% more efficient use of furnace space and productivity gain; can eliminate vibration damage to heating elements, furnace lid design extends lid life up to three times longer.

The nitrogen supply system for the CARBOJET system can also be equipped with a Linde-designed safety solution used to purge flammable atmosphere furnaces to satisfy National Fire Protection Association (NFPA) safety requirements for furnaces (NFPA 86).