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Show O E M s will provide viable control for selected gas turbines. Retrofit kits are available to convert newer lean-burn reciprocating engine models to clean burn design. For these engines, large N O x reductions are possible but the retrofit costs are significant because of the amount of equipment upgrade necessary. For older lean-burn reciprocating engines, retrofit kits are not available and controls are limited to selected field adjustments and minor equipment modifications that can result in moderate N O x reductions. The population of rich-burn naturally aspirated engines is candidate for retrofit of N S C R and PSC conversion, both resulting in significant N O x reduction levels. Most retrofit controls are likely to increase emissions of C O and T U H C . Add on catalysts can result in net reduction in C O and T U H C as well as NOx. Table 11. Anticipated NOx reduction performance and impact on efficiency of field adjustment and minor equipment modification options Control Approach Ignition retard* Increased A/F Ratio6 Derate* Charge Air Cooling Applicable Engine Models Atmospheric Engines Turbocharged Engines Atmospheric Engines Turbocharged Engines All Engines Atmospheric Engines'* Turbocharged Engines' N O , Reduction Efficiency (%) 15 to 25 25 to 30 45 to 55 20 to 30 10 to 30 20 to 30 5 to 35 Loss in Efficiency (%) * 3 2.0 to 2.5 -10 to-13 2.5 to 3.0 3 0 0 Comments Based on 4-5 degrees retard Based on 4-5 degrees retard 15 in. H g w/ intercooler, 25 hp gain 10% manifold pressure increase 80-10% reduction in torque Manifold temperature to 100°F Manifold temperature to 100 °F a- Requires low cost field adjustments b- Requires equipment modifications and upgrades Source of data: Reference 3 Acknowledgements This work was performed for the Gas Research Institute, Chigaco IL under Contract No. 5091-254- 2209 from September 1991 to July 1992, and under the overall direction of Mr. Robert Lott and Kathleen Locke, GRI's project managers. i-^ H °? 2. r' f' 12 1-4 |