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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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The Use Of A Gas Imaging Device For Detecting Fugitive Emissions In Chemical Plants
Michael Smylie
Environcorp
Since the early 1980s, federal and state regulatory agencies have supported the development and eventually required the implementation of leak detection and repair (LDAR) programs for control of fugitive emissions from a variety of industries. The currently required LDAR procedure (EPA Method 21) involves placing a gas sampling instrument probe at the surface of each piece of applicable equipment and measuring the volatile organic compound (VOC) concentration as the probe is moved along the surface of the equipment. If the measured VOC concentration is above the level defining a leak, the component must be repaired or replaced to reduce the concentration to an acceptable level.
Method 21 has several shortcomings. It does not provide mass emissions rates of detected leaks. In addition, Method 21 measures only the hydrocarbon drawn through its probe. In addition, the number of designated components in a chemical plant/refinery to be tested for leaks can be quite large, making leak detection monitoring very time consuming, manpower intensive, and expensive.
EPA is currently supporting several initiatives for the refining and chemical industries involving new technologies that may lead to better and more cost effective fugitive emission control within these industries. Optical gas imaging has emerged as a promising candidate technology.
This paper presents the results of field studies comparing the fugitive emissions leak control effectiveness using optical gas imaging technology to that which would be obtained using the current Method 21 protocol. Preliminary results indicate that the gas imaging system is able to identify high leakers while monitoring both regulated and unregulated components, and is able to do so at a rate three to 50 times faster than the monitoring rate using Method 21.