One of the largest power plants in New York City was experiencing low levels of air filtration, degrading its gas turbine output. After a three-year study to evaluate alternatives, it chose a Finnish supplier of air intake filters for gas utilities.
Astoria Energy is a combined cycle gas turbine plant, situated in Astoria in Queens, New York City. The site on which it sits is owned by the area’s Power Authority. Astoria Energy is made up of two separate power plants, Astoria Energy LLC and Astoria 2 LLC, but it is operated as one facility. The combined output of the Astoria Energy plant, which is equipped with four gas turbines and two steam turbines, is around 1200 MW, enough to serve 15-20% of the New York City customer load, around one million people. The Power Authority authorised the building of the first of the two plants to meet the electricity needs of schools, municipal buildings, hospitals and subways in New York City. The second natural gas fuelled plant was approved in 2008 and began operation in 2011. Filter quality Astoria Energy was having compressor fouling problems with the air filtration level they were using, sometimes experiencing a loss of up to 6 MW between gas turbine off-line washes. Improved intake air filtration in gas turbines reduces the need to stop turbines for periodic off-line washing. The off-line washing of fouled blades on compressors also costs energy companies money in terms of lost revenues due to down time and the associated labour costs for cleaning. Michael Stockstad, plant manager for Astoria Energy, explained that gas turbines use a very large amount of air so the quality of air coming in is extremely important for overall levels of cleanliness. He added that, not only does it improve the efficiency and life of the filters, but it also keeps a lot of the components clean. Intensive study In the search for a better intake air filtration level, the company decided to undertake an intensive three-year study, with the help of ENGIE Laborelec, which specialises in research and advice to customers in electrical power technology. One of the fields where the company is very active is air filtration optimisation. Arnaud Lambert of ENGIE Laborelec, who worked with Astoria Energy on the study, said that typically the filter is only a small part of the gas turbine, but the effect it can have on the core components can be huge. He added, “Production at the Astoria site is composed of four gas turbines which run more or less in the same way. We came to the site and the plant manager was quite open to test and to make a comparison of different filters. So, what we did over there was actually a like-for-like comparison of the four units, from different suppliers. At the end the goal was to evaluate the life cycle cost of each supplier and the return of experience in order to identify the best one.” Eagle Filters Astoria Energy installed four competing suppliers of intake air filters and rigorously studied their performance over the test period. Eagle Filters, a Finnish cleantech firm that designs and manufactures air intake filters for gas turbines was one of them. The company is a core holding of Loudspring, a company group that preserves natural resources and is headquartered in Helsinki.
Juha Kariluoto, CEO of Eagle Filters said, “Air impurities in gas turbines causes fuel efficiency to decrease up to 5% because of the effect these impurities have on compressor blades. By using ordinary OEM level filtration, the blades are too easily fouled. When these blades are fouled they need to be cleaned more often, so availability decreases due to periodical washing. In the end, power capacity can deteriorate by up to 10% due to fouling alone.” Energy savings During the test phase at Astoria Energy, the Eagle Filters’ TurboMaster EPA filters were able to provide a Heat Rate Improvement of approximately 1.5% while also providing an average output recovery / improvement of approximately 4 MW for one gas turbine. The estimated reduction in CO2 emissions using Eagle Filters in the test period was 2750 tons CO2e per year of use. By using Eagle Filters’ technology in all of their four gas turbine units, it is estimated that the CO2e reduction per year for Astoria Energy will be 11,000 tons, which is equivalent to the annual home energy use of 1,188 US homes, or the CO2 equivalent of 25,467 barrels of oil consumed. Following the study, Eagle Filters was selected as the preferred air intake filter supplier at the Astoria Energy plant and the company is now installing TurboMaster EPA filters on all four of their turbine units. As Michael Stockstad observed, “With these installed there was virtually no degradation of turbine output, resulting in significant efficiency improvements.” No washing need Astoria Energy has now installed 4224 filters supplied by Eagle Filters in all four units, and these filters are expected to provide clean air, free of urban and industrial pollutants and moisture to Astoria Energy for at least three years without the need for periodic washing of fouled compressor blades. Michael Stockstad doesn’t underestimate the important role that Eagle Filters played in providing clean air for the company’s gas turbines. He went on to say that:“Astoria Energy burns natural gas as its primary fuel and it is critical for keeping the lights on in New York City. I believe natural gas will play a significant role in the US energy market for many more years to come. Natural gas is a clean alternative to other fossil fuels and Eagle Filters will contribute to the overall efficiency of the Astoria project.”
