Site Conversion and Field Performance of an Ultra-Low Emissions Combustion System for the MS7EA Gas Turbine

Increasingly restrictive emission regulations for gas turbines are driving key technology decisions across the United States and Europe. For example, in Texas, United States, regulations are forcing permit holders in certain non-attainment areas to ratchet down industrial oxides of nitrogen (NOx) emission levels by over 80% by 2008. Improvements today in the technology of lean pre-mix combustion for gas turbines can result in reduction of NOx and carbon monoxide (CO) emissions to ultra-low levels without using Selective Catalytic Reduction (SCR’s) or Oxidation Catalysts (OCAT’s); and often provides the end user with the most cost effective solution to addressing these requirements. This paper describes the demonstrated current field performance of a dry, lean-premixed combustion system developed for direct replacement in MS7E/EA gas turbines previously configured with either the OEM’s DLN-1 combustion system or converted from a standard diffusion combustion system. The LEC-III^® combustion system, developed by Power Systems Mfg. LLC (PSM), owned by Alstom, has proven sub-4ppm NOx and single digit CO emissions levels over the entire premix load operating range with natural gas fuel, from full load down to below 55% of full load conditions in customer machines. A recent conversion effort completed by PSM in 2006 & 2007 now has five gas turbines currently operating at a Texas industrial power producer operating at below 4ppm NOx with the LEC-III system. The conversion scope will also be detailed. Dynamic pressure sensing instrumentation was installed on each combustion chamber to measure and record combustion dynamic oscillations or “noise” to optimize fuel splits within each combustor. Rugged construction and performance optimization enable the dynamics to be maintained within acceptable limits to ensure extended service intervals of over 16,000 equivalent fired hours. Detailed field-installed emissions results are provided for this Frame 7E/EA LEC-III site. Finally an overview of PSM’s Combustion Technology Roadmap (CTR) will be discussed, which leverages their high-pressure, high-airflow test rig to evaluate technology improves with the objective of achieving guaranteed LEC-III combustion system NOx emissions below 3ppm NOx with low levels of CO.