Formaldehyde Test Method Considerations at Proposed MACT Compliance Levels for Natural Gas-Fired Reciprocating Internal Combustion Engines and Gas Turbines

摘要

Maximum Achievable Control Technology (MACT) standards for gas turbines and reciprocating internal combustion (IC) engines have been under development since the mid-1990's. This effort will likely culminate with the U.S. Environmental Protection Agency (EPA) release of the proposed IC engine MACT standard and proposed gas turbine MACT standard in the fourth quarter of 2002. For natural gas-fired IC engines and gas turbines, EPA has focused on formaldehyde as the principal hazardous air pollutant (HAP) of concern for the MACT standards. Included within MACT proposals are measurement methods for initial compliance certification and/or ongoing compliance monitoring. In recent years, several methods have been used for measurement of formaldehyde from IC engines and gas turbines. Initial source characterization tests were completed using CARB Method 430. Sample matrix interferences and the desire for near-real time data resulted in the subsequent development of extractive Fourier transform infrared (FTIR) spectroscopy test methods. This was followed by a search for a lower cost, more accessible test method which culminated in application of a method derived from a pulp and paper industry test method based an acetylacetone wet chemistry and colorimetric spectroscopy. Formaldehyde test method interference issues and detection limits are especially important when considering the emissions standard likely to be proposed for gas turbines. This paper summarizes key technical issues from earlier research, as well as recent research results related to the application of CARB Method 430, extractive FTIR spectroscopy, and acetylacetone colorimetric methods for formaldehyde measurement from natural gas-fired IC engines and gas turbines. The paper will examine implications for the application of the test methods to these source categories, including consideration of how method-specific issues affect application of the test methods for MACT performance characterization and compliance monitoring.