GB383547A - Methods of and apparatus for electrically removing entrained particles from gas streams - Google Patents

Abstract

<PICT:0383547/III/1> <PICT:0383547/III/2> <PICT:0383547/III/3> <PICT:0383547/III/4> <PICT:0383547/III/5> <PICT:0383547/III/6> <PICT:0383547/III/7> In a process for the electrical separation of suspended particles from gases, alternate fields of high and low concentration are established between the discharge and collecting electrodes, the latter being maintained at a uniform potential, and the field of high concentration is maintained in a substantially uniform condition, for example by cleaning the electrodes. In the arrangement shown in Fig. 1, the collecting electrodes consist of plates 2 spaced apart to clear the pipes or rods 3 which project into the gas passages to form the terminals of the highly concentrated field. Half-round bars or pipes 3<1> are similarly arranged adjacent the side walls of the casing 1 which also act as collecting electrodes. These bar-type electrodes are arranged opposite the discharge electrodes 10, and their upper ends slide in glands 4 and have anvil-heads 5 supported by springs 6 (see Fig. 4). The lower ends are flattened and secured in a channel into which the lower edges of plates 2 also extend. They may be made of metal or of asbestos cement composition, concrete or other semi-conducting material, and are cleaned by hammers 15 actuated by rocker shafts 14. The plates 2 may be cleaned less frequently and if required by hammers 32, operated by shafts 31, striking the anvils 33. The electrodes 3 may also be cleaned by rotation against spring-pressed scrapers 16, Fig. 6 or brushes 17, Fig. 7. In cases where the necessary electrical conditions cannot be maintained by these methods, the electrode surfaces are flushed with washing liquids as shown in Fig. 8, a stream of low pressure water being delivered by a pipe 19 to the interior of the electrode 3a. The water spills over and forms a film down the outside of the electrode. This arrangement is particularly useful where it is desired to conserve the heat content of hot gases. The application of the process to a precipitator in which the main collecting electrodes 23 are corrugated is shown in Fig. 11, the subsidiary collecting electrodes 25 being opposite the discharge electrodes. An arrangement for a pipe treater is shown in Fig. 12. The field between the discharge electrodes and the subsidiary portions of the collecting electrode is maintained as near as possible to the value at which a sparkover would occur if the electrode surfaces were free from deposits. Any deposit on the discharge electrodes may be removed by known means.