LOI Thermprocess, a Tenova LOI Italimpianti company, is to supply a large pit-type furnace for the stress relieving of turbine shafts for installation at the ALSTOM plant in Birr, Switzerland. This is the second contract for a heat treatment furnace of this type to be awarded to LOI within the past six months. Another pit-type furnace is to be supplied to ALSTOM's US plant in Chattanooga, Tennessee.
The new furnace in Switzerland is due to be commissioned in mid-2010. The bottom section of the furnace is to have a maximum outside diameter of 6500 mm and the overall height of the unit will be 16,000 mm. The furnace will be used for treating rotors with weights up to 200 t and lengths up to 12,000 in a protective controlled atmosphere.
The large pit-type furnace consists of a fixed base with recirculation fans, four heated rings and a cover. The furnace is charged from above. For charging and discharging, the cover and, if necessary, the top one or two rings, are removed. The furnace is heated by low-maintenance electric heating elements (see illustration).
The new furnace is to be controlled by a Siemens S-7 400 PLC. A higher-level visualization system based on WinCC will also be used.