The Litoral-A field is a big oil and gas field in the Gulf of Mexico. Since the accident in the deep part of the Gulf of Mexico several years ago, Petroleos Mexicanos (Pemex) has been developing fields in the shallow part of the Gulf.
The Litoral-A field is in the Bay of Campeche where the local water depth is 26 metres. In order to boost the current oil and gas production, the platform design is aimed at improving the flexibility of the Litoral Processing Centre and reduce flare gas using high pressure compression. The platform is to be capable of increasing the gas pressure to 85bar.
The supplier approached Bronswerk Heat Transfer at an early stage with the challenge of the project to find a solution for this situation and produce a design which would permit safe and reliable cooling in a tight space.
The problem was to ensure that the required flow of cooling air could be 'pressed' through the finned tube bundle. We were looking for a way to achieve an efficient solution given the situation. Smaller bundle space means higher air velocity and whence a higher pressure drop for a given air flow. An increased number of layers, to bring the required cooling surface area within the limited plot area, also increases the pressure drop. The resulting pressure drop on the airside was far higher than is common in air-cooled cooler applications and higher pressure drop means higher driving power and a higher noise level.
The only feasible solution would be to employ a fan which delivered an optimal volume flow and static head within the constraint of maximum permissible power (in other words: highest efficiency). Also, the noise produced by that fan should stay below the maximum permissible noise level.
Although the coolers have more rows of finned tubes, the total height of the coolers is reduced by 0.6 metres. Even the weight of the coolers is 15,000 kg less than with the conventional fans.
The other main benefits are not only for the smaller cooler but also for the overall project:
- The ability to provide a suitable module on an existing platform without modifying the platform structure.
- Maintaining the weight of the module below the maximum crane lift capacity to avoid the need for a heavier crane.
- Fewer fans, so fewer E-power connection points and cables, and fewer components requiring maintenance.
- No self-induced vibrations from the fans to the structure.
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