Abstract: Disclosed is a method and apparatus for calibrating and recalibrating a photometric measurement instrument which supervises the presence of dust in a particular location as produced by a process during which dust is developed on an irregular basis. The method is characterized in that the calibration is initiated upon the detection of a condition in which dust concentration is expected to be low. In a steel-making process, such a condition occurs upon termination of the blowing phase of a converter. In the case of smoke in a flue, such a condition occurs when there is an absence of gas flow in the flue.

Abstract: The dust removal plant is comprised of a fan with adjustable guide vanes and a ring gap scrubber with adjustable gap width. A first feedback loop controls the scrubber operation through gap width control for maintaining a constant residual dust content of the gas as discharged, a second feedback loop keeps the pressure constant at the scrubber intake by adjusting the guide vanes. Both feedback loops reduce the power consumption of the fan for periods of low dust development. The apparatus is explained with reference to cleaning of smoke gas discharged from a blowing steel converter.