GB418551A - Apparatus for the electrical precipitation of suspended materials from gases - Google Patents

Abstract

<PICT:0418551/III/1> <PICT:0418551/III/2> Apparatus for the electrical precipitation of <PICT:0418551/III/3> <PICT:0418551/III/4> suspended particles in gases comprises in combination a casing containing one or more discharge electrodes suspended transversely to the path of the gas through the casing, and mounted on insulators which are outside the path of the gas, a permeable collecting electrode positioned to the rear of each discharge electrode and also transverse to the flow of the gas and spray nozzles for projecting a fluid or gaseous medium on to the collecting electrode to remove deposited matter. The removal of deposited material may be effected automatically in accordance with the pressure difference existing between the opposite faces of a collecting electrode. Flushing means may also be provided for the discharge electrodes, in which case the current may be cut off during operation. In the arrangement shown in Fig. 1, the gases pass through the concentric discharge and collecting electrodes 18 and 8, the former consisting of a series of rods suspended from ring 19 and mounted on insulators 21 placed in recesses 6 in the casing. The lower edge of the collecting electrode dips into a water seal, and rotating spray pipes 10 flush the collecting electrode. In an alternative form of construction, the discharge electrode ring is placed outside the collecting electrode which is arranged to rotate. Fixed sprays are used to flush the electrodes, shields being provided to prevent contact of the flushing medium with the discharge electrodes. Fig. 4 shows an arrangement in which the gases are passed horizontally through a casing 49 containing a series of discharge and collecting electrodes 52, 58, 63 and 66. The discharge electrodes consist of permeable metallic screens suspended from insulators 53 and 64 and held at their lower edges of additional insulators arranged out of the gas stream. The collecting electrodes consist of a series of corrugated members, the corrugations on adjacent member being disposed at right angles to each other, and sprays 60 and 68 wash these electrodes. The insulators are kept dry and clean by passing a portion of the cleaned gas through a pan 70 and heat-exchanger 72 into the chambers housing the insulators. In a modified arrangement, deflector plates are provided inside the casing to direct the gases through the discharge electrodes and sprays are also provided to wash these electrodes, in which event the current supply is interrupted. Means may be provided so that only one discharge electrode is cleaned at a given time. The insulators supporting the discharge electrodes are placed in separate housings, and are hollow to allow the circulation of, for example, heated oil to keep them dry. In the construction shown in Fig. 13, the gases pass upwards through a series of washer hurdles 112 and 113 followed by ceramic tiles 114, sprayed by nozzles 116, and acting as a gas washer, then through a series of tiles 117 constituting a moisture eliminator. Finally the gases pass through a permeable discharge electrode 120 suspended from insulators 122, which are kept dry by a current of gas through passages 125 and 126. The collecting electrode comprises a series of tiles 128 washed by sprays 130. As shown in Fig. 15, the ceramic tiles may be of cylindrical form with a spiral web or vane 132 inside the cylinder. Specifications 125,681, 167,939, [both in Class 1 (i)], and 364,491 are referred to.