Process and apparatus for removing dust from gases

摘要

982,819. Removing dust from gases ; electrostatic separators. METALLGESELLSCHAFT A.G. April 9, 1963 [April 12, 1962], No. 14194/63. Headings B1R and B2J. A process for removing dust from gases comprises dividing a stream of gas into two partial streams which are treated with liquid in a gas washer saturating and cooling the partial streams to different temperatures or mixing the partial streams to produce a mist of condensed liquid in the gas and passing the mixed gas through a wet electrostatic precipitator divided into two or more separating fields of different intensity. The difference in temperature between the two partial streams is preferably more than 5 ‹C. and the washing liquid used to wash the partial streams may be at different temperatures and supplied in different quantities. As shown in Fig. 1, apparatus for carrying out the process comprises two Venturi-scrubbers 3, 31, the scrubber 3 being supplied with fresh water and scrubber 31 with recirculated water. The partial streams after passing through baffles 13, 131 are mixed and passed through perforated plates 14, 15 and an electrostatic precipitator having separating fields 4, 41 and 411 to an outlet 20. The Venturiscrubbers and the electrostatic precipitator are arranged in a cylindrical housing 2 with hemispherical ends. The fields 4, 41 and 411 have respectively spike electrodes 16, stellate electrodes 17 and thick round electrodes 18 of a cross-sectional area between 20 and 50 mm.2. The field 4 has a very strong discharge effect but the field 411 acts only as a condenser field. In a modified gas washing apparatus, Fig. 3, all the gas is passed through a first zone in a chamber 23 where it is sprayed with recirculated water. A partial stream of the gas is withdrawn through an outlet 29 and the remainder of the gas is washed with fresh water in the upper part of the chamber 23, leaving by an outlet 35 to be mixed with the gas withdrawn through outlet 29 and passed through an electrostatic precipitator.