Rotary Hearth Furnaces
Rotary hearth furnaces are continuous in their nature, and are used to heat up semi-finished products for subsequent rolling, forging, pressing, and extrusion in series production with variable composition of the charges to be heated up. They are most frequently used in pipe rolling mills; lower-capacity furnaces are then mainly used to preheat sections for drip forging, ring forging, and similar processes. The furnaces used, as rule, for smaller-sized charges to be heated up (where lower capacities suffice) can be conceived as plate-shaped furnaces that can act as an optimum replacement for chamber preheating furnaces within continuous manufacturing processes.
The advantages of the rotary hearth furnaces lie in their arrangement in space:
- versatility for a wide spectrum of materials and various subsequent technological processes
- charge loading/unloading operations can be performed from one place
- charge passage speed can be adjusted over a wide range
- variability of the heat-up temperature curves, depending on the size and composition of particular charges and furnace capacity
- furnaces can be used over a broad range of capacities
- highly efficient operation, using the waste heat from exhaust fumes
The optimum type of heating system can be selected, depending on the particular furnace working conditions and in respect of the outgoing fumes’ heat capacity.
The following options apply:
- combustion air preheating in a central recuperator
- recuperative burners
- combustion system with regenerative burners
The last-mentioned option can conveniently be used within reconstructions of existing rotary hearth furnaces, mainly where the objective is to increase the furnace capacity and simultaneously reduce the specific heat consumption.