WCA September 2010

Furnaces and heat treatments

Recirculation furnace A recirculation furnace for multi-wire steel cord plants, developed by CPA Wire Technologies, is said to set “new standards regarding energy consumption, achievable wire qualities and environmental pollution.” The heat treatment of iron and steel wire in multi-wire continuous wire plants, such as soft annealing, tempering, patenting and diffusion annealing, is mainly carried out in gas heated furnaces. All common methods have the disadvantage that energy losses are high, and only a small proportion of the consumed energy is actually used for heating the wires. The unused energy difference is released into the environment as hot exhaust gases, an excessive and unnecessary energy consumption in addition to other disadvantages such as heat treatment costs, environmental pollution, high space requirement and complicated processing. CPA Wire Technologies’ new furnace has been designed to prevent these disadvantages and to reduce energy consumption by up to 40%. The furnace series was launched under the brand name CPA AEOX Industrial Furnaces. CPA Wire Technologies has developed a turbo system for guiding the gases via recirculating air fans through two chambers: the wires are heated in the upper chamber and the process cycle is closed in the lower chamber. The ratio of the heating process is significantly improved by convection, since at high flow velocities of the hot gas the heat-transfer coefficient ( α ) is increased many times over. This results in a significantly increased heat efficiency of the hot gas. As a further energy-saving measure the turbo continuous wire furnaces are provided with gas-heated recuperation burners in which the combustion air is pre-heated by the already hot exhaust gases. The pressure in the furnace chamber and the furnace atmosphere are controllable and adjustable within very narrow ranges. The temperature distribution and the temperature variations in the furnace are very consistent, even for 60-wire plants. The CPA turbo recirculation furnace is highly controllable, and said to produce between 25% and 100% of the rated capacity without any quality problems. The turbo furnaces are especially well insulated against heat loss, so emission losses via the external furnace walls are very small and the indoor climate is hardly affected. After leaving the recuperation burners the exhaust gases are led through heat exchanging devices to use the residual heat for heating up baths, for example. In CPA’s steel cord plants, for instance, the turbo recirculation furnace is integrated in an ecologically and economically optimised system and is applied as an austenitization furnace together with the newly developed CPA AEOX convection film cooling system with two-phase soaking furnace as a patenting plant. As an integrated part of a galvanic brass plating plant, the CPA plant is said to require 40% less energy than conventional patenting and brass plating lines. AEOX energy-optimised XFlow furnace ❍ ❍

CPA Wire Technologies GmbH – Austria Email : wiretec@cpa.at

Website : www.cpa.at

Horizontal chamber furnaces Horizontal chamber furnaces from ILES are available in two series with maximum working temperatures of 500°C or 700°C. They are designed for stress-relieving, tempering, structural hardening, ageing and annealing of non-ferrous materials. The main characteristic of these plants is high thermal efficiency, achieved by thermal insulation using several layers of the

latest ceramic fibres at differentiated density, and mass-less specially-formed wire heating elements placed directly in the air circuit. A patented vitrifying system, and the special design of the internal deflector and high-revolution fan for air circulation, maintain a temperature uniformity of ±5°C inside the treatment chamber. The furnaces can be supplied with several options, including: Protective atmosphere • Timer •

Variable fan/fans rotation speed • Protection against over-heating • Moveable external roller plane with rapid clutch device • on the furnace Fixed external roller plane • Double external roller plane with motorised movement • Thermal cycle automation (no operator required) • 4/6/8/12-post external storage units, with loading system and automated thermal cycles. This storage system saves • energy, working the plant during the night or over the weekend The standard equipment for all the models includes an operator panel, PLC, microprocessor temperature controllers and EDP network connectivity. Horizontal chamber furnace from ILES ❍ ❍

ILES Srl – Italy Fax : +39 0373 750110

Email : info@iles.it

Website : www.iles.it

68

Wire & Cable ASIA – September/October 2010