Facilities emitting 25,000 metric tons of CO2e annually are required by the EPA to report annual GHG emissions per EPA mandate 40 CFR Part 98, and Subpart W pertains to all aspects of the natural gas industry, including offshore production, onshore production, onshore gas processing, transmission, underground storage, liquefied natural gas (LNG) storage, LNG import and export, and natural gas distribution.
There are a number of different applications ranging from high flows for the blown-down vent stack to the very low flow rates found in compressor seal leakage. Many of the emission sources are from venting and fugitive emissions. The EPA estimates that fugitive and vented greenhouse gas emissions in petroleum and natural gas facilities are the second-largest source of human-made methane emissions in the United States. While some GHG sources can be estimated or modeled a large number of different sources make calculating GHG emissions very complex. Over the long term, direct measurement of the GHG emissions will be simpler requiring much less time and manpower than performing all the necessary calculations. In addition, obtaining an exact measurement of the natural gas leakage loss will provide the operator with valuable information to help increase the performance of their operations.
SAGE thermal flow meters are ideally suited for direct measurement of GHG emissions. The very low flow rates in small pipe sizes can easily be measured using SAGE’s flow body designs which range from ¼ inch to four inches. The higher flows in the larger pipe sizes can easily be handled with the insertion probe. The high turndown capabilities and the excellent resolution provide the most accurate flow measurements over a broad range of flow rates. Particularly of importance is the in-situ calibration verification which permits the user to verify that the operating performance of the SAGE insertion thermal mass flow meters meets the performance when the unit was originally calibrated. The ability to simply perform this test without removing the flow meter from the pipe is of utmost importance to the user.
With the EPA now requiring emitters to report annual GHG emissions, flow meters are being scrutinized to find the best ways to measure and report data. Mass flow meters are becoming the preferred choice to monitor and measure GHG emissions. One of the primary advantages of thermal mass flow meters have over volumetric meters is that the meter measures mass flow. The SAGE products are state-of-the-art as Sage was the first to bring to market a digitally-driven sensor, a graphic display, and onsite calibration verification. The SAGE meter is the only TMFM which provides a convenient, in-situ and in-line calibration check that assures the flow meter retains the original NIST traceable calibration and is accurate.
To read the Sage Metering white paper “Greenhouse Gas Emissions Monitoring Using Thermal Mass Flow Meters” visit Sage GHG Emissions White Paper.
For more information on PART 98— Subpart W—Petroleum and Natural Gas Systems