August 2025 Volume 7

EQUIPMENT & TECHNOLOGY

ROTARY HEARTH FURNACE FOR STEEL & ALLOY HEATING By Arturo Arechavaleta

In normal operation, this rotary furnace operates at between 1040°C (1900°F) and 1200°C (2190°F). Rotation is driven by a central bearing system mounted at the hearth substructure and operated by a pinion gear motor drive. An encoder is included, and hearth rotation is possible in both forward and reverse mode. There is a sand seal to ensure sealing between the furnace and the rotary hearth. Optimal billet heating is achieved within a single automatic temperature control zone, and is delivered by four high-velocity nozzle-mix burners, each of which is equipped with a lightweight alumina-mullite burner tile, and spark plug. The burners are positioned to heat tangentially over the load and the configuration results in high gas circulation inside the chamber, providing better control during the heating and soaking process, the required temperature uniformity, and better heat transfer to the product. Additionally, variable excess air control is applied at cycles with lower temperatures, enabling the best possible circulation and re-entrainment with a very high velocity mixing, ultimately achieving homogeneous and excellent temperature uniformity without the need for circulating fans inside the furnace. For enhanced process stability, furnace pressure is controlled via a transmitter that automatically measures internal pressure and sends a signal to the PLC that compares actual pressure against the required level. The PLC then transmits a signal to the actuator motors in the flues, to adjust the motorized dampers for automatic control of the furnace pressure. For superior performance, NUTEC Bickley fabricates a high-temperature resistance multi louver with silicon carbide shaft dampers for this purpose. The single vertical door and the furnace walls and roof are insulated with NUTEC’s proprietary ceramic fiber HTZ MacroModules. These form a 25cm (10in) thick extremely efficient lining that provides excellent insulation and is characterized by long life coupled with low maintenance requirements. Another result is superior operational performance, with NUTEC insulation allowing faster heating and cooling cycles. The rotary hearth itself is insulated with 15cm (6in) of hard refractory backed up by 15cm of insulating firebrick and a layer of insulation board. For all further information, please contact: Arturo Arechavaleta – VP Metal

A substantial forging and machining facility in the US has placed a contract with NUTEC Bickley for a rotary hearth furnace that will be used to heat billets of carbon steel and stainless steel alloys. The gas-fired furnace has been designed to deliver production rates of between 910kg (2000lb) and 1360kg (3000lb) per hour, depending on the size of the billets. Placed vertically on the hearth, the furnace can handle billets 7.6cm (3in) to 20cm (8in) in diameter and 12.7cm (5in) to 51cm (20in) in height. The heated materials are ultimately forged into a variety of high-specification components, such as fittings, flanges, plates, blanks and rings. Arturo Arechavaleta, NUTEC Bickley’s VP, Metal Furnaces, said: “Our customer’s products are used in high-pressure environments, such as oil & gas, petrochemical and advanced industrial manufacturing, and so there is a constant demand for excellence, accuracy and reliability. Here at NUTEC Bickley, our technical team has made significant advancements in rotary hearth technology, and all the latest concepts and improvements are brought together in this project.”

Furnaces, NUTEC Bickley Phone: +52 81 8254 0633 Email: arturoarechavaleta@nutec.com

FIA MAGAZINE | AUGUST 2025 11