Innovations in Total Reduced Sulphur Measurement Technologies
Funded through Round 2: Industrial Energy Efficiency in 2012, Global Analyzer Systems developed a Continuous Emission Monitoring System (CEMS) to measure total reduced sulphur (TRS) compounds in real-time, enabling the optimization of sulphur recovery unit (SRU) incinerators at sour gas plants.
Natural gas heats homes, supplies power, and provides an array of valuable products. Approximately one-third of all produced natural gas in Alberta is “sour gas”, meaning it contains measurable amounts of hydrogen sulfide (H2S), a dangerous compound with health and environmental impacts. Sour gas must be cleaned up before it can be used commercially, and this is defined by identifying “TRS” levels. TRS is defined as a gaseous mixture of pollutants that contain sulphur in its reduced state and includes compounds like H2S.
Reducing stack temperatures at gas processing plants can conserve fuel and lower greenhouse gas emissions. It is also a viable way to reduce emissions within the natural gas sector. However, lowering incinerator stack top temperatures at sour gas processing facilities requires an accurate method to ensure the TRS value does not exceed the compliance limits that were set to safeguard human health and the environment.
Because of its real-time, continuous monitoring of TRS compounds, the CEMS technology allows SRUs to operate at lower incinerator stack temperatures without exceeding emission limits. This reduces fuel consumption, lowers greenhouse gas emissions significantly, and enhances operational efficiency—all while maintaining compliance with strict environmental regulations. Global’s TRS CEMS is unique compared to existing technologies because it uses Global’s innovative sampling system. Historically, TRS has been measured by designing sampling programs where a sequence of manual grab samples are taken several different plant operating conditions and then run through a gas chromatograph for analysis. This technique has shown issues with accuracy due to sample loss and degradation over time, as well as issues with precision due to varying gas compositions over the integrated sample time. Global’s sampling system minimizes losses for an accurate measurement of TRS compounds.
Navigating Requirements for Innovative Technology Testing
Global faced a few challenges during this project. Namely, the CEMS continuously monitors the concentration of TRS through a new sampling technology that is much different than the approved manual reference method required by the province. There are many factors that affect the ability to draw a relative accuracy comparison including differences in the sample extraction techniques, the time it takes to analyze the samples and the skill level of the testers and quality of their equipment. To account for these factors, some modifications to the approved reference methodology were made to increase the accuracy of the reference method sampling. Even with modifications to the methodology, a performance evaluation of the TRS CEM System’s relative accuracy was challenging. Still, the system passed all the specified performance tests required by the provincial regulators.
In addition, Global successfully demonstrated that TRS levels in a high temperature SRU incinerator stack could be measured accurately and reliably in real-time. The project also demonstrated that the TRS CEMS could be used as a valuable tool for the successful reduction, and subsequent operation of a sulphur recovery incinerator stack at a reduced stack top temperature. The project found that reduction in stack temperature from 420 degrees Celsius to around 320 degrees Celsius resulted in significant savings— between 14,000 and 27,750 tonnes of emissions annually, depending on operational parameters.
What’s next?
During this project the TRS CEMS was successfully installed, certified and validated showing that it could continuously monitor TRS concentrations. The technology is derisked and commercialized, and regulators will now be able to ensure sufficient oxidation of TRS compounds when a stack top temperature reduction is assessed. Overall CEMS have gained wider adoption for monitoring TRS. Global continues to develop and market their technology while engaging regulators and industry stakeholders to facilitate smoother adoption and regulatory approval for future installations.