1. Field of the Invention
The invention relates to a cooled trunnion ring for a converter, and more particularly to a trunnion ring that is arranged at a distance from the converter, encompasses the converter and is connected to a coolant supply station.
2. Description of the Prior Art
Converters used in steel production, when of a certain size or larger, are located in non-attached trunnion rings. When an increased demand is placed on converter vessel capacity, especially when refractory linings with high carbon content are used, the thermal load of the converter wall, like that of the trunnion ring, becomes ever greater. This thermal load also effects the trunnion ring arranged at a distance of approximately 100 to 200 mm from the converter.
In order to prevent the permissible limits for the vessel mantle from being exceeded and, at the same time, to reduce the thermal load of the converter trunnion ring, a cooling medium is customarily conducted in the space between the ring and the vessel mantle. Thus, an air cooling system for heatable metallurgical vessels equipped with non-attached trunnion rings is known from DE 39 27 928 A1. In this system, air ducts are arranged on the outer side of the trunnion ring, via which cooling air is conducted between the trunnion ring and the outer wall of the metallurgical vessel. The disadvantage of this air cooling system is that gaseous media have only a low capacity for extracting heat. Additionally, the air in this system is blown off, which is undesirable for environmental reasons.
It is also known to completely fill the trunnion ring with water for cooling purposes. Disadvantageously, the water supplied and extracted through the trunnion increases the weight of the trunnion ring. Furthermore, in the event of certain malfunctions, for example, a vessel break-out, the trunnion ring may also suffer damage, resulting in a dangerous convergence below the converter of liquid melt and uncontrollable quantities of water. Moreover, when high thermal loads are placed on the trunnion ring mantle, especially given the low flow speed of the cooling water, blistering occurs on the inner wall (the so-called "killing frost effect"). The negative consequence of this is that heat extraction is prevented at these locations.
In addition, filling the interior of the converter trunnion ring with water makes it inaccessible for the purpose of inspection and maintenance.