Abstract: An annular gap washer for scrubbing a gas stream with a liquid, especially for the scrubbing of blast furnace gases with water such that the adjustment of the width of the annular gap controls the pressure at the head of the blast furnace, comprises the usual housing or duct with a tapering configuration and a body axially movable in this duct and with a tapering configuration so that the annular gap is formed between this body and the duct wall. According to the invention, the base angles of the body and the duct walls are different such that the gap converges in the direction of flow of the gases, thereby reducing vibrations or oscillation of the body without interfering with scrubbing efficiency.

Abstract: An apparatus for cleaning the exhaust gas of a high-pressure blast furnace comprises a coarse-particle separator, a prewasher and a differential-pressure annular gap washer traversed in succession by the gases. The exhaust gases can be passed through a main duct provided with an expansion turbine or through a bypass duct around the expansion turbine. The expansion turbine unit controls the back pressure at the blast furnace while a separate control circuit is provided to operate the differential-pressure washer with optimum efficiency. A quick-closing valve in the turbine-supply line and a quick-opening valve in the bypass line permits rapid switchover, a pressure-control valve in the bypass line maintains a constant backpressure at the blast furnace when the expansion turbine unit is shut down.