The demands and requirements of the thermal process, such as temperature and productivity, are decisive for the furnace design.
We distinguish between continuously and batch-wise operated furnaces. In large-scale continuous furnaces, the charging material is transported through the furnace at constant speed or step by step and also heated at the same time.
The differences between the large-scale furnaces and the small and medium-sized furnace plants are the dimensions of the charging material and the performance capacity. These furnace types are used for reheating of semi-finished products (slabs, blocks, billets, etc.) for subsequent hot forming or heat treatment. Due to fast heating and cooling rates it is possible to produce types of steel which have high demands to the temperature-time-curve. In general the performance capacities of continuous furnace systems are higher compared to industrial furnaces with batch-type operation.
Walking beam furnaces
The ANDRITZ Metals Germany (former ANDRITZ Maerz) flat flame burner has been designed according to energy optimization and emission reduction considerations. This burner can be operated with all fuels and with preheated air. The following values were achieved during combustion of natural gas GPL: NOx relating to 5% O2 in the exhaust gas =< 200 mg/Nm³ (at an air preheating temperature of 500° C and a furnace chamber temperature of 1,270° C).
ANDRITZ Metals Germany furnace technology is the result of continuous development. Thus, we are in a position to customize furnace systems optimally to meet increasing customer requirements and to produce environmentally friendly plants, also considering high availability and highest quality achievement as well as energy optimization. The large-scale furnace plants of ANDRITZ Metals Germany are characterized by good sealing of the furnace doors, as well as an automatic descaling and a special rider system. Together with the technically perfect process handling, best results can be achieved in terms of energy efficiency, temperature uniformity within the furnace, reduced skid marks on the material, and low scale formation and decarburization.
The material in the form of pipes is heat-treated in special large-scale walking beam furnaces. The temperatures in the hardening furnace range from 800-1,050° C and in the tempering furnace from 500-800° C. Typical furnace capacities are 15-60 t/h. The furnace is heated by high-speed burners (operated with preheated air) or recuperative burners.
The material in the form of slabs is heated to temperatures of up to 1,320° C in large-scale pusher-type furnaces. Typical furnace capacities range from 100 to 300 t/h. The furnace is heated by a combination of side burners, roof, and regenerative burners.
The material in the form of slabs is heated in large-scale walking beam furnaces to temperatures up to 1,300° C. Typical furnace capacities are 100-450 t/h. The furnace is heated by a combination of side burners, roof, and regenerative burners.
