Field of the Invention
The invention relates to a furnace charging construction and in particular to a new and useful throat stopper for shaft furnaces, in particular blast furnaces with two hoppers, of which the upper hopper is rotatable via a drive device and to a method of operating the furnace charging construction.
Most of the known devices for introducing and distributing the charges for the burdening of blast furnaces are built on what is called the McKee principle. In this arrangement with two bells, a large bell in the lower region and a smaller bell in the upper region, the two bells being arranged one above the other, the upper hopper is rotatable.
The McKee throat stopper has the advantage, among others, that its overall height is relatively small, an advantage which is significant with respect to maintaining the lumpiness of the charged material. A disadvantage of this type of stopper, which may be termed a single-chamber stopper because the upper hopper is not formed as a sluice chamber, consists in that the sealing of the lower distributor bell relative to the sluice chamber wall constitutes a problem in particular because of the relatively large seal elements. This seal is, for one thing, under heavy stress due to wear by the abrasive charge material, but, for another, it is also problematical because of possible deformations due to uneven gas temperature distribution over the cross section of the furnace. As soon as a leak occurs at any point of the seal, dust particles are entrained with the outflowing gases due to the high pressure in this zone, and they will very soon increase the leaks. This source of dust constitutes an unacceptable environmental pollution, not to mention the fact that the seal elements must be replaced frequently.
To remedy this situation, it has been proposed before to design a throat stopper of this kind in such a way that the lower large bell need no longer from a gasproof seal. This is done in that the rotary distributor closed by the bell is disposed in a tightly closed envelope.