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Show NOx REDUCTION USING PLASMA MODIFIED GASES S. J. BORTZ, D.H. HELFRITCH RESEARCH-COTTRELL 1306 E. EDINGER STE. B SANTA ANA CA. 92705 v. T. WOLFENDEN SOUTHERN CALIFORNIA GAS 555 W. FIFTH ST. LOS ANGELES CA. 90013-1011 ABSTRACT --3 A post combustion NOx control process is currently under development by ResearchCottrell which reduces NOx emissions by utilizing the pyrolysis products of hydrocarbons and/or other gases. The process, which has been named PYRONOx, involves frrst creating the radical species in a plasma torch. The radicals are then rapidly mixed with the flue gases, which under the correct conditions can generate high levels of NOx reduction through a series of reactions similar to reburning or thermal DeNOx. This paper presents theoretical and experimental results from the development of the PYRONOx process documenting the efficiency of the plasma torch in creating the desired radicals, the results of experiments optimizing rapid mixing between the plasma and flue gases and the NOx reductions obtained over a range of operating conditions. INTRODUCTION Research-Cottrell is currently in the process of developing a new method of post combustion NOx control, the PYRONOx process, which uses natural gas and\or other gases as the feedstock and electric power for operation. Southern California Gas, together with Research-Cottrell, is co-sponsoring the development. The PYRONOx process was originally discovered during experiments using a plasma generated with a microwave cavity. Tests were conducted injecting a mixture of steam and hydrocarbon gases through the microwave cavity and into a flue gas stream at a flue gas temperature of between 300 F and 400 F. The results of these tests are summarized in figure 1, which show the flue gas NO concentration resulting after the injection of the plasma modified gas. Using steam alone no measurable NO reduction was observed, however using a mixture of steam and methane about a 10% reduction was observed and using a mixture of acetylene and steam almost complete destruction of NO was observed. From these test results it was theorized that the plasma modified hydrocarbons initiated a series of reactions simil~ to rebuming as shown below: 1 |