GB990200A - A method of improving the dust collecting efficiency of wet electrostatic precipitators - Google Patents

Abstract

990,200. Electrostatic precipitators. METALLGESELLSCHAFT A.G. Aug. 22, 1962 [Aug. 23, 1961], No. 32321/62. Heading B2J. [Also in Division H2] Space charge which inhibits the efficiency of an electrostatic precipitator is reduced by means of an automatic voltage regulator which allows arc discharge to continue for a period before control is effected by reducing the voltage, the voltage being cut off for a period if the discharge continues despite the control. As shown in Fig. 1, potential for the precipitator 1 is supplied by a rectifier 2 powered from a transformer 3 the primary of which is driven from a potentiometer 10. The current taken by the primary of transformer 3 is monitored by current transformer 4 and transformer 15 which supplies a discriminating relay set 16 which is shown in detail in Fig. 2. The input to the relay set 16 is rectified to set up control voltages on the resistor chains r2 and r3, and r14 and r15. Should the voltage on chain r2, r3 rise above the rated value thyratron P1 fires to extinguish normally conducting thyratron P2. Slugged relay dl in the anode circuit of P2 releases after a given time to drive motor 9, Fig. 1, by way of control circuit 8 to set the potentiometer 10 to a value to reduce the current supplied. Should the current drawn by the precipitator rise to a value greatly in excess of the rated value the voltage on chain r14, r15 rises to fire thyratron P3 and extinguish normally conducting thyratron P4. Slugged relay d2 in the anode circuit of P4 releases, after a given time during which the consequent heavy discharge is allowed in the precipitator, and by means of control circuit 8 causes relay 12 to disconnect the supply to potentiometer 10. After a further fixed interval the relay 12 reconnects the supply with tubes P3, P4 and relay d2 restored to normal so that heavy discharge in the precipitator is repeated for as long as d2 takes to release a second time. This process is repeated a given number of times after which relay dl is allowed to control potentiometer 10 to reduce the supplied voltage. Switches bl, b2 are provided with a stabilized voltage supply from tubes P5, P6, in order to test the operation of tubes P1, P2, and P2, P3, respectively. The primary of transformer 3, Fig. 1, has an associated pulse transmitter 5 and a variable resistor 6 in circuit the functions of which are not disclosed. The discharge electrodes are preferably such as to have corona discharge points directed perpendicular at the collecting electrode and being spaced at regular intervals of 10 cms. The electrodes are 25 cms. apart.