Sour Water Stripper – Fin Fans Case Study

A refinery in the United Kingdom reported heavy fouling and loss of efficiency of the  overhead Fin Fans at their Sour Water Stripper (SWS) Unit. This was causing deterioration in the level of performance of the fans. The reduction in exchanger duty had led to excess steam being sent to the sulphur units. Excess steam, especially when excess ammonia is in the system, leads to operational difficulties and corrosion of pipe work.

During maintenance cleaning of the fin fans, the refinery would need to keep the overheads on the Sour Water Stripper online to allow the process fluids to keep circulating. Conventional cleaning methods such as water blasting would have cooled the circulating medium in the tubes, thereby causing the deposition of ammonia salts. If the temperature in the tubes is reduced it can lead to ammonia blockages.

After working closely with the Operations Team to understand the issues and come up with a solution, ProDecon® was given the contract to perform the cleaning. ProDecon’s technique of using a specially modified inert crystal media, driven by compressed air, proved highly effective. The non-abrasive method effectively cleared out all of the detritus between the fins, but was gentle enough to ensure that there was no damage. Moreover, the overheads could be kept online, improving productivity, and avoiding the risk of internal plugging.

Customer Verified results

After the decontamination, the refinery was able to report that the improved efficiency of the fans was allowing for increased sulphur recovery. This had the knock-on effect of significantly reducing the amount of steam and ammonia that was passing downstream. As a result,

there were reduced levels of corrosion downstream. Additionally, a refinery engineer believes that, “one of the additional benefits of this performance increase is that it might lead to a reduction in the downtime of the SWS during the October turnaround. During that event, the refinery’s sour water will accumulate in tankage. If this volume can be reduced, this will limit the amount of tankage required and speed up the removal of the water after the event.”

“The results have exceeded our expectations; with our exchanger outlet temperature well under control……. their operation is much more stable” – A Client’s Treating Development Engineer stated.

ProDecon’s support positively impacted client’s plant efficiency and created forecasted environmental, schedule and subsequent commercial advantages.

Note ProDecon® are now also able to offer on-line treatment for prevention and removal of ammonia salt deposits. Click here for details of our AST process.