Gas Compressor Station Assessment

A gas compressor station, comprising five similar compressor units connected by an inlet and outlet header, is planned for offshore construction in Mexico. Each unit features three compressor stages that elevate the gas pressure from ambient levels to 95 bar. This substantial pressure increase is accompanied by a significant temperature rise, necessitating the installation of coolers after each stage. Additionally, scrubber vessels are positioned both before and after each stage.

Dynaflow Research Group (DRG) was engaged to provide analytical support and suggest reroute possibilities to enhance the structural integrity of the system and the connecting nozzles of scrubbers, compressors, and air coolers during the design phase.

Analysis

The assessment encompassed the entire compressor station, including the scrubber nozzles, compressor nozzles, and air cooler nozzles. To efficiently evaluate all nozzles, DRG developed a comprehensive spreadsheet to verify each nozzle against its allowable limits. This simultaneous analysis was crucial due to the system’s inflexibility and the impact of piping on all nozzles. Any modification to a nozzle at one end of the line would influence the nozzle at the opposite end. The simultaneous analysis enabled the identification of the optimal routing and support layout for all nozzles.

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Results

The initial design of the compressor station revealed that many nozzles and flanges were overstressed. DRG’s significant modifications, combined with the recommended support layout, effectively reduced pipe stress and nozzle loads to well within allowable limits. Most modifications aimed to increase the system’s flexibility to accommodate thermal expansion of the piping. These changes were implemented on the first compressor station and subsequently applied to all units. To support the sustained loads and accommodate large thermal deflections at multiple locations, DRG sized and installed appropriate hangers.

In conclusion, DRG’s involvement in the gas compressor station’s design phase resulted in enhanced structural integrity and optimal performance of the system. The comprehensive analysis and strategic modifications ensured that all components operated within safe stress limits, ultimately contributing to the station’s reliable and efficient operation. This case study underscores the importance of meticulous design and assessment in complex engineering projects, particularly in offshore environments.

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