INDUSTRIAL EXPERIMENTS ON PULSE CORONA SIMULTANEOUS REMOVAL OF NOX AND SO2 FROM FLUE-GAS

The corona-induced simultaneous removal of NO, and SO2 from the flue gas is based on the application of narrow voltage pulses to an electrode structure similar to that of an electrostatic precipitator. The free electrons of the corona discharge, having energy up to 20 eV, originate active radicals which lead to the transformation of NO, and SO2 into their acids which can be neutralized to salt particulate by adding to the gas a basic compound such as ammonia and calcium hydroxide. The process has been investigated with a test rig installed in the slipstream of the flue gas duct of a coal thermal power plant. The experiments were performed with three reactor modules of different geometries having a nominal gas flow rate of 1000 Nm3/h. The voltage pulses, generated with a fast switching experimental device, had a rise front of less than 400 ns and a repetition frequency up to 300 Hz. The test results have confirmed the physical feasibility of the process. Under initial concentrations of NO, and S02 between 400 and 530 ppmV, the removal efficiency was 50–60– for NO, and about 80– for SO2 at an energy input to the gas of 12-14 Wh/Nm3 when ammonia was injected in the flue gas. Using hydrated lime instead resulted in a less suitable basic compound. Further experiments are necessary to assess the effect of different electrode geometries of the reactor, the efficiency of the process attainable with an improved coupling of narrow pulse power set to the reactor, and the practical ways for integrating the DeNOx, and DeSO2 corona process with the solid particle collection system. © 1990 IEEE