EPA Validates ATOM Instrument FGA-1000 for Increased Safety
Pursuant to the regulatory standard US EPA 40 CFR Part 60.18 Subpart Ja, the addition of Total Sulfur analyzers was mandated to monitor certain refinery flares to verify emissions compliance. The standard includes emission limitations applicable to both current and new process units such as catalytic cracking units, coking units, delayed coking units, fuel gas combustion devices, and sulfur recovery plants.[1]
ATOM was initially approached by a multinational refinery that processes crude oil and other feedstocks with a global refining capacity of over 2 million barrels of oil per day to determine if the ATOM-patented Excimer UV Fluorescence technology, featuring the widest dynamic range on the market, could effectively make the required flare measurements within a single calibration range. After installation in their refinery allowed the customer to determine that measurement linearity mandated by the new Ja rule could easily be met over the intended flare analysis range of 0-50%/vol. H2S, the customer selected the FGA-1000 as the preferred instrument for this application within all of their refineries.
Utilizing a single calibration range reduces instrument calibration costs when compared with using multiple calibration standards to characterize the concentration versus instrument response curve. Additionally, it reduces the required time needed for calibration, which in turn increases analyzer up time. Since the rule stipulates analyzers used for compliance of flare emission require both calibration and daily validation using hazardous H2S gas at concentrations that can be as high as 100% in some flares, safety risks and the potential impact to the workforce are important considerations. These safety concerns are compounded when the number of calibration gases needed to define or characterize analytical linearity increase, for some instruments requiring as many as 5-6 calibration standards.
After several years of using the FGA-1000 within their refineries for the intended flare measurement, the customer wondered with such a wide dynamic range, could safety risks associated with running high concentrations of poisonous H2S gas for calibration and daily validation of analyzer accuracy be reduced. Toward that end, the customer submitted an application to the EPA seeking to obtain an Alternate Monitoring Plan (AMP). Before considering approval, the EPA required verifiable demonstration of instrument linearity over a 0-100% range. An independent, third-party laboratory ran tests at their facility using certified H2S standards at seven different concentrations and collected data was sent to the EPA. Twenty analyses at each concentration were averaged where the concentrations used for the test were 0, 12.5, 25, 37.5, 50, 75 and 100%/vol. with the data being used to create the above graph.
After submitting all test data and obtained results to the EPA, they determined that the ATOM FGA-1000 total sulfur analyzer incorporating Excimer UV Fluorescence (EUVF) technology for monitoring flare gas emissions demonstrated acceptable linearity over the specified range for the AMP to be obtained. As a result, the EPA approved the requested Alternate Monitoring Plan, allowing the span concentration required by the majority of the referenced customer flares to be reduced from 50% (500,000 ppm) to just 0.5% (5,000 ppm). This hundred-fold reduction represents the minimum allowable span range in accordance with the Subpart Ja rule, providing a substantial decrease in potential safety hazards and risk associated with H2S toxicity for this customer.
