Patent ID: 8444910

Claim:
Shaft furnace comprising: a device for charging an upper section of the shaft furnace with raw materials, which due to gravity descend inside the shaft furnace while an atmosphere prevailing within the shaft furnace causes part of the raw materials to melt and/or to be reduced, a system for injecting a process gas through at least two different channels into a lower section of the shaft furnace, the system comprising a control device controlling the injection via adjustable process variables, such adjustment of the process variables at least in part determining the atmosphere prevailing within the shaft furnace, whereby the control device is set in a way as to dynamically modulate the process gas in a manner that the process variables pressure p and/or volume flow {dot over (V)} are varied at least intermittently within a time span of ≦40 s and whereby the process gas is injected into the shaft furnace through the at least two different channels, a first process variable serving to control the process-gas component being injected along the first channel is dynamically modulated and a second process variable serving to control the process-gas component being injected along the second channel is dynamically modulated, the first and the second process variables are identical process variables modulated differently or the first and the second process variables are mutually different but subjected to identical modulation, and whereby the first and the second process variables are periodically modulated with an identical cycle time T while their relative phase is shifted by a specific value.