New gas turbine combustor supports emissions limits.
The LE IV combustor uses dry, low-nitrogen oxides (DLN) technology to reduce emissions from the Allison 501K industrial gas turbine to 25 parts per million or less (corrected to 15 percent oxygen) -- levels that are expected to meet pending federal emissions regulations. GRI is funding similar efforts with other manufacturers of turbines commonly used at pipeline compressor stations and industrial power generation sites.
"The advantage of a DLN approach is one of cost-savings and better emissions control," said Todd Linville, director of industrial engine sales for Allison, a unit of Roll-Royce and a leading designer. builder and marketer of turbine engines.
"The DLN approach enables turbine operators to reduce emissions without incurring additional expenses associated with water injection of selective catalyst reduction technologies. Companies using the latter approaches face higher maintenance costs as well as related expenses for replacement and disposal of catalysts and for ammonia use and disposal," he said.
ANR Pipeline Co. sees the LE IV as a way to increase the operating efficiency of its pipeline compressor stations. ANR retrofitted the LE IV combustor package on a 4-megawatt Allison unit at its Woodstock, IL Compressor Station. Since April, the unit has logged more than 1,000 hours of operation and is meeting nitrogen oxides (NOx) and carbon monoxide (CO) guaranteed limits without adversely affecting turbine horsepower or fuel consumption.
Without the Allison DLN technology, Illinois regulations would require ANR to achieve emissions compliance by limiting operation of the Woodstock turbine to certain hours.
"Before installation of the LE IV combustor, we had to curtail use of the turbine for natural gas transmission by almost 50 percent," said Keith Darnell. lead engineer-field Services Department for ANR. "With the Allison product, our operation is freed up 100 percent. The high-efficiency, dry low-NOx turbine, operating a majority of the time, means lower total emissions and reduced cost for moving customer-owned gas."
Paul Bautista, GRI program team leader, Distributed Power Generation, said GRI's work with Allison is one of three DLN projects the research agency has developed so turbine manufacturers can offer their customers a least-cost solution to meeting emissions requirements for turbines under 20 megawatts, a size commonly used at pipeline compressor stations and industrial power generation sites.
"GRI joint funding of these efforts has given manufacturers an added incentive to pursue the less capital-intensive dry low-NOx control approach," Bautista said.
The Allison combustor features a dual operating mode. During the pilot mode of operation, fuel is directly injected into the combustor's liner where it is consumed in a diffusion flame reaction. During higher power operation, the fuel and air are uniformly premixed in fuel-lean proportions to control NOx formation. In addition, optimum engine performance is maintained by the dry, lean-mixed combustion technology as it suppresses NOx formation in the turbine's combustion section.
An added advantage of the LE IV combustor is its ability to lower emissions without any adverse affect on engine performance and operations, according to GRI. The combustor is available as either a retrofit or as an option on a new engine.
Bautista said GRI is currently working with Allison, the U.S. Department of Energy, Southern California Gas Co. and the Santa Barbara County Air Pollution Control District to develop a combustor than can reduce NOx levels to 9 ppm in an effort to meet more stringent air quality regulations in California. Field testing of this combustor is targeted for late 1997 with commercialization in 1998. GRI is already soliciting candidates for test host sites, he said.
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|Publication:||Pipeline & Gas Journal|
|Date:||Oct 1, 1996|
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