Optimization Senior Manager
12:20 - 12:45
Thursday, 19 September 2019
S1.8 ELNG Success Story – Plant Turndown Ratio
The Egyptian LNG facility is operated by Egyptian LNG (ELNG), consisting of two LNG trains owned by Shell, Petronas, EGas and Engie. Both trains utilize the ConocoPhillips Optimized Cascade® LNG process with a nameplate capacity of 3.6 MTPA. Train 1 was brought online in May 2005 with Train 2 following in October 2005.
Since mid-2013, ELNG encountered severe supply limitations and frequent feed gas interruptions, due to national grid demands. Several challenges were incurred with maintaining only one train online with stable operation at very low feed gas rates, when available. Other challenges incurred were maintaining plant readiness for the offline train, as well as both trains during periods with no feed gas supply. For example, 60 feed gas interruptions occurred from January 2014 to December 2016, with each interruption requiring a shutdown and restart. Although each train was contractually designed to achieve 35% turndown of feed rates (around 225 MMSCFD), the turndown achievable proved much higher, around 13% and lower (90 MMSCFD). The two-trains-in-one approach employed for the refrigeration turbine/compressor strings helped minimize efficiency losses at high turndown.
Since mid-2018, the feed gas rates have been increased from around 13% with frequent interruptions to around 35% with substantially less interruptions and by sustaining the plant available during the feed gas shortage, we were be able to retain the asset and people capabilities for readiness to any future feed increase.
This paper focuses on how the high turndown capability, coupled with the ability to achieve rapid shut downs and restarts, allowed ELNG to sustain facility operation with sufficient revenue to justify remaining online with full staffing throughout the time period of severe feed gas supply limitations and frequent interruptions, mid-2013 to early-2018. During that period there were 705 on-stream days producing 3.1 million m3 of LNG equivalent (21 cargos). The paper will further outline operations at high turndown during this time frame, with a focus on the associated economics and key challenges incurred. Some of the key challenges discussed are equipment thermal cycling, corrosion under insulation, maintaining offline equipment and piping with conditions that facilitate rapid restarts, and maintaining core competencies for the operations and maintenance staff.