SRU Performance Evaluation Case Study

This is the final video in the SRU Optimization series, which describes how to optimize the performance of each individual process unit, and covers 2 case studies from past testing experiences at SRE. This is the final case study, where we’ll look at a testing job from about ten years ago at a refinery, and this is still a big client of ours to this day. So upon initial sampling we found that both feed streams had above threshold amounts of higher hydrocarbons (C2-C6), indicating over-circulation in the amine unit, and inadequate skimming operation of the SWS. The low quality feed streams (& high contaminants) caused low thermal conversions. High h/c content caused high CS2 formation. Poor hydrolysis, leading to 1.3% combined losses. And then their ADA signal was a little wonky from the inaccurate TGA readings. They were getting just under 96% recovery efficiency, with pretty much each stage underperforming. SRE engineers then built a simulation model of the plant on that first night of testing and were able to provide some good guidance the following day. We increased the RF co-firing for better destruction temp, we increased the converter 1 temp, while reducing converter 3’s temp. And finally we lowered the final condenser temperature to 130°C. The increased RF temperature lowered the ammonia and BTEX breakthrough and jumped the thermal conversion efficiency to 50%. Increased the converter 1 hydrolysis by nearly 10%. But, with the increased co-firing rates came elevated gas mass velocities in the condensers, this increases the risk of liquid sulfur carryover to the next stages. Therefore, it was recommended that all the tubesheet blanks be removed to bring the velocities back down to normal. And, since the CS2 formation was still high, we recommended they review the circulation rates in the amine unit and the skimming operation of the SWS unit to attempt to reduce hydrocarbons and BTEX to the SRU. So when we returned for the next set of quarterly testing, we found a much more accurate TGA, both feed streams were more optimized with less hydrocarbons, and the mass velocities dropped down into the normal range because they removed the tube blanks. This performance test, along with an incinerator optimization study, boosted the client’s recovery efficiency to well above the license, it improved the upstream unit’s operation, and the catalyst life was increased. This granted them huge savings in maintenance and fines, and greatly reduced their greenhouse gas emissions. It ended up being one of many examples of why testing and optimizing an SRU is often much more beneficial than some people might think. And that brings us to the end of this webinar. Thank you for attending, and if you liked this presentation – consider looking into our on-site training, where we can send an engineer to your location to provide a wide range of courses regarding SRU’s and amine sweetening units. There is just one cost per course, not per person. So now I will take the time to answer any of your questions. Thanks for watching! For more videos on sulfur recovery, subscribe to our page. Also visit our website http://sulfurrecovery.com/, and sign up for our monthly newsletter here: http://sulfurrecovery.com/Newsletter/