GB1128813A - Improvements in or relating to electro precipitation - Google Patents

Abstract

1,128,813. Electrostatic precipitators. LODGE-COTTRELL Ltd. 28 April, 1966 [8 May, 1965], No. 19513/65. Heading B2J. Dust is removed from dust-laden sulphur dioxide containing gas, by oxidation of the sulphur dioxide followed by electrostatic precipitation. As described, a small portion of the gas, which is derived from a boiler plant 12, 14, Fig. 1, is removed by an off take (27, Fig. 4) from the main gas stream and after preliminary precipitation at 32 and cooling by an air injector 44 controlled by a thermostat, it then passes through a vanadium pentoxide catalytic reactor 34. This produces sulphur trioxide which is passed through a main electrostatic precipitator 18 with the remainder of the gas. The gas is heated at 16 prior to its entry into the precipitator. The off-take 27 has ports 29 arranged in the direction of gas flow, and a gas distributor 31, Figs. 6, 7 provides communication between lines 28 and 24, Fig. 1. The proportion of gas passing through the reactor 34 is controlled by an apparatus of the kind described in Specification 1,093,617 together with a control device as described in Specification 859784, and this is used to provide a constant potential difference between the precipitator electrodes Ec, ED. If the desired value is obtainable without conversion of SO 2 a valve 30 is closed and the reactor is thus temporarily out of service. In a second embodiment gas passes from a valve 130 Fig. 8 to an oil burner 154, where it is heated to above its reaction temperature, filtered at 156 and cooled 'by an injector 144 and fed to a reactor 134. The plant may be modified by omitting a fan 36, by arraying alternative line connections shown dotted in Figs 1 and 8, leaving out thermostatic control of the reactor 34, inserting a small filter in the line 40 and a smaller precipitator 32. The control apparatus may be modified as described in Specification 1,093,617 or a system of potential difference control may be used as described in Specification 832,342. In the second embodiment the oil burner may be replaced by an indirect heat exchanger supplied with hot gas from a previous part of the plant, the filter 156 may be located upstream of the burner 154. In this case a further small filter is provided in advance of the reactor 134.