Top-gas cleaning at blast furnaces: comparison of wet and dry systems

Efficient removal of the dust from blast furnace top-gas is essential for energy recovery in a top-gas recovery turbine. In most blast furnaces de-dusting is achieved by two-staged cleaning systems, comprising of a first separator – a dust catcher or a cyclone - and a second cleaning stage which is usually a scrubber. In a few blast furnaces dry cleaning systems have been realized in the past using a reverse air filter or an electrostatic precipitator. In recent years there has been a shift, especially in China, to totally dry cleaning systems using bag filters with pulse-jet cleaning systems. In this article the advantages and disadvantages of such dry de-dusting systems are discussed.