PM2.5 and ultrafine particulate matter emissions from natural gas-fired turbine for power generation

Abstract

The generation of electricity from natural gas-fired turbines has increased more than 200% since 2003. In 2007 the South Coast Air Quality Management District (SCAQMD) funded a project to identify control strategies and technologies for PM2.5 and ultrafine emissions from natural gas-fired turbine power plants and test at pilot scale advanced PM2.5 technologies to reduce emissions from these gas turbine-based power plants. This prompted a study of the exhaust from new facilities to better understand air pollution in California. To characterize the emissions from new natural gas turbines, a series of tests were performed on a GE LMS100 gas turbine located at the Walnut Creek Energy Park in August 2013. These tests included particulate matter less than 2.5 μm in diameter (PM2.5) and wet chemical tests for SO2/SO3 and NH3, as well as ultrafine (less than 100 nm in diameter) particulate matter measurements. After turbine exhaust was diluted sevenfold with filtered air, particle concentrations in the 10–300 nm size range were approximately two orders of magnitude higher than those in the ambient air and those in the 2–3 nm size range were up to four orders of magnitude higher. This study also found that ammonia emissions were higher than expected, but in compliance with permit conditions. This was possibly due to an ammonia imbalance entering the catalyst, some flue gas bypassing the catalyst, or not enough catalyst volume. SO3 accounted for an average of 23% of the total sulfur oxides emissions measured. While some of the SO3 is formed in the combustion process, it is likely that the majority formed as the SO2 in the combustion products passed across the oxidizing CO catalyst and SCR catalyst.The 100 MW turbine sampled in this study emitted particle loadings of 3.63E-04 lb/MMBtu based on Methods 5.1/201A and 1.07E-04 lb/MMBtu based on SMPS method, which are similar to those previously measured from turbines in the SCAQMD area (FERCo et al., 2014), however, the turbine exhaust contained orders of magnitude higher particles than ambient air.