Benfield Gas Sweetening System SCSR-07
Case In Brief
- In August 1999, Gas processing plant had been established in the south-west of Matrouh governorate in order to treat the raw natural gas production of field to reach pipeline quality and sales gas specification. Gas sweetening system aimed at reducing sour gas content of CO2 and H2S to be less than 3% and 4 ppm respectively.
- In 2014, Reboilers had suffered from various leaks that lead to repetitive costly shutdowns.
- In September 2015, Absorbers’ monitoring indicated high pressure drop and high vibrations within the pump, which forced a bypass mode for both trains.
- In November 2015, Shell experts started investigating the problem to come up with the root cause for the problem and reasonable solution.
Challenge
- Difficulties mainly involved different phases and types of deposited hard scales and deposits within the system. Chemicals used must be inert with system components and critical appendices to avoid their failure.
- Nevertheless, sufficient dissolution capacity and high efficiency of the proposed chemical cleaning agent is fundamental for the success of this job due to the limited capacity of the free volumes within the system and their ratio to the volume of scale.
- These crucial conditions made it very difficult for any existing cleaning chemical to meet the required specs.
Solution
- SCS had developed a new proprietary cleaning agent (SCSR-07) specially formulated for the targeted problem and conditions.
- Compatibility tests for all system components, along with QA/QC procedure, had affirmed the quality of the product. Based on this, a definitive plan was constructed for the safe execution of the job.
Results
- The job execution yielded an outstanding result as all contaminants were removed from the system, which brought it back to its perfect operable conditions. Hence, treated gas can comply with designated sales specs.
- A valuable award was granted from Shell to SCS team for their efforts and high-standard results.
DIAGNOSIS AND ANALYSIS
In January 2016, participants from Cairo University, UOP have started a comprehensive investigation which lasted for a period over six months. It Included inspection, detailed analysis of failed packing, scale analysis and corrosion testing.
Diagnosis included XRD and XRF analysis to examine their mineralogical composition and structure. The results were as following.
Mainly, they were facing a composition of vanadium pentoxide, Potassium carbonate contaminants not filtered properly, and corrosion byproducts like iron carbonate, iron sulfide and nickel sulfide.
JOB DETAILS
Different combinations and formulas were tested to ensure delivering the best cleaning agent for the targeted problem. Benfield system was disintegrated into seventeen loop sections to be cleared separately. Roughly speaking, about 500 cubic meters of chemicals were used in chemical cleaning job and it efficiently achieved the desired goal.