Contents

• Total Reduced Sulfur Compliance Testing (RM15, RM16)
• Claus Sulfur Recovery Unit Feed Testing
• Sulfur Content of Hydrocarbon Streams
• Other Compliance Testing Services

Total Reduced Sulfur Compliance Testing (RM15, RM16)

The most common compliance testing done by Brimstone is measurement of Total Reduced Sulfur (TRS) from plant incinerators. Brimstone’s compliance testing gas chromatographic procedures follow ASTM E-260-73 protocol standards, and trace sulfur analytical methods are based on EPA Reference Methods 15 and 16. The analytical system is sensitive to sulfur compounds to below 0.1 ppmv, and speciation of sulfur compounds is inherent in this gas chromatograph testing system. Calibration for trace sulfur testwork is done using NIST/NBS-traceable permeation tube calibrator systems. During testing, all plant sample lines and valves are thoroughly purged, and connections are made to our sampling equipment, which are constructed of or lined with inert materials. These steps insure that all line-loss criteria are met. To preserve stability of the sample, drying tubes are used for most samples, and result in stream compositions measured on a dry basis. All gas samples are collected in clean, dry glass sampling containers, and are analyzed within one to two hours of sampling. Because of our experience with these processes, our review of the test data as it is generated allows reliable evaluation of the testwork. Results are available as they are generated, and this allows immediate corrections to the plant operation or test plan, avoiding wasted time and money and helping to ensure a successful test. The test report includes all analytical results and a detailed description of sampling, analytical, and calibration methods.

Claus Sulfur Recovery Unit Feed Testing

As a result of recent environmental compliance agreements between some refinery operators and the EPA, it has become necessary for them to routinely monitor the operating efficiency of their Claus units. This involves analysis of the amine acid gas and sour water stripper feed streams as well as the incinerator effluent gas. Brimstone has adapted conventional analytical methods to conform to Reference Method requirements, and now performs this testing in several states under the guidelines of various environmental agencies. Typically, feed gas testing takes place over a single day, allowing characterization of the feed stream compositions over a moderate period of time.  The amine acid gas and sour water stripper feed gases are tested several times each for H₂S content using sampling and analytical techniques based on EPA Reference Methods. To preserve stability of the feed gas samples, drying tubes are used and this results in stream compositions measured on a dry basis.  (Water contents of these water-saturated gas streams can be calculated separately based on stream temperatures and pressures.)  All gas samples are collected in clean, dry glass sampling containers, and are analyzed onsite within one to two hours of sampling. The analytical system used for Reference Method measurement of bulk H₂S utilizes an external H₂S standard, and therefore has specific capability for measuring only the H₂S concentration, and does not provide a comprehensive analysis of the inlet gas streams. Calibration and analysis for H₂S will be done using a certified H₂S calibration gas standard. Calibration runs will be made at the beginning and end of each workday. In addition, the measurement of H₂S in the sour water stripper gas stream requires determination of the NH₃ content, and certified NH₃ calibration standards are used for that analysis. The presence of ammonia in the sour water stripper feed complicates the analysis and requires specialized equipment and techniques.

Sulfur Content of Hydrocarbon Streams

In order to limit the SO₂ emissions from process heaters in refining and other processing facilities, emphasis has shifted somewhat from measuring the resulting SO₂ toward monitoring the total sulfur content of the fuel gas streams consumed in these heaters and burners. Brimstone has been able to adapt our trace sulfur analytical techniques for use as formal protocol methods that satisfy the requirements of the various environmental agencies involved. These new sampling and analytical techniques provide accurate and reliable speciation of the sulfur compounds at concentrations to as low as 0.1 ppmv. Specialized analytical systems used for trace sulfur species allow analysis of trace sulfur compounds even in the presence of relatively high concentrations of H₂S. The trace sulfur analytical system is sensitive to sulfur compounds to below 0.1 ppmv, and typical accuracy for trace sulfur analysis is ±6% relative. Calibration for trace sulfur test work is done using permeation tube calibrators. This portable, NIST/NBS-traceable system is highly accurate and reliable. It allows onsite generation of a wide variety of trace level sulfur standards over a wide range of concentrations.

Other Compliance Testing Services

Brimstone has participated in a number of special compliance projects that have involved the development and/or modification of test methods to meet unusual requirements. These include measurement of Total Reduced Sulfur (TRS) analysis in H₂S-rich Claus unit feed streams, compliance testing for hydrogen in fuel gas systems, and total sulfur content of incinerator effluent and other vent streams. Brimstone specializes in solving difficult analytical problems in support of the chemical processing industry and environmental agencies.