Recovery of the substantial crude oil reserves in central California has been restricted by stringent state regulations limiting the NOx emissions from steam generators used to enhance the recovery process. These regulations specify that emissions reductions below a baseline level are required when certain ambient NO2 triggering levels are exceeded. There have been no comprehensive test programs aimed at defining baseline emissions from steam generators or the effects of design parameters on those emissions. There have, however, been many individual tests of steam generators that have been performed primarily to comply with licensing requirements and these show that NOx emissions from standard 15 MW (50 × 106 Btu/hr) generators vary by a factor of five, from 160 to 825 cm3/m3 NOx, corrected to 3 percent O2. Clearly, this indicates a need to identify an established baseline to which emissions levels from alternative configurations may be compared.

The study described in this paper entailed compilation of all available test results and analysis of these to 1) define the NOx emissions baseline, 2) delineate the effects of several design variables on emissions, and 3) address the effectiveness of field tested NOx reduction techniques and equipment. From these results, the 15 MW (50 × 106 Btu/hr) steam generator with a conventional burner was observed to be the most common configuration. The type of burner and steam generator were found to be relatively unimportant, probably because of similarities in design between manufacturers. The generator capacity was of greater importance. Steam generators with 6 MW (20 × 106 Btu/hr) nominal capacity exhibited NOx emissions exceeding the 15 MW (50 × 106 Btu/hr) conventional burner levels, as did 15 MW (50 × 106 Btu/hr) generators equipped with low excess air burners (designed for high thermal efficiency). Field test results from two NOx reduction methods were also analyzed. Ammonia injection into the combustion products showed significant effect on NOx emissions; current technology low NOx burners were characterized by emissions near conventional burner levels.

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