Sulfur Recovery Engineering (SRE) clients often ask about Key Performance Indicators for their Sulfur Recovery Units.
It is difficult to identify KPIs for the SRU without compositional analysis and feed stream data. If you think about it, the data that you see from the DCS – flows, temperatures and air demand analyzer (ADA) info – are all directly related to what is actually coming into the SRU.
Things to look at are inlet flows to the SRU, temperature differentials across the catalytic converters, and the concentrations reported by your tail gas analyzer. It is important to note that these data points are dependent on the compositional analysis of feed streams. SRE can provide our clients with this analysis, and recommends that a Performance Evaluation and Optimization be conducted periodically as part of any SRU routine maintenance program.
If your crude or gas wells change frequently, it is recommended that feed streams are tested more regularly as operating parameters may need to be adapted in order to compensate for varying acid gas quality or contaminants. For example, if the H2S content in the amine acid gas drops significantly (i.e. a drop in sulfur loading) then the combustion air requirements, the converter bed temperature profile, and the measured ADA concentrations will all change as well.
In a refinery, it is important to do regular sampling of both the amine acid gas and the sour water stripper acid gas to determine their respective compositional analysis, especially if the source of crude supplying the refinery is constantly changing. Some SRE clients have us come to site and conduct this analysis on a quarterly basis.
Here is the short list of SRU KPIs to monitor for performance and optimization that we consider important:
- Flow rates of the amine acid gas, sour water stripper acid gas and air (main, trim and total) to the SRU;
- Amine Acid Gas H2S, CO2, & hydrocarbons content;
- Sour Water Stripper Acid Gas, Ammonia (NH3), H2S, H2O content;
- Differential temperature across the first and second converter (i.e. the maximum bottom bed temperature of the converter minus the outlet temperature from the reheater);
- H2S and SO2 concentrations from the ADA;
- Stack Emissions.
Regular reviews of your SOPs, PMO plan and other operating manuals will ensure that you are up to date with the most efficient operating procedures.