exporting gas from a platform
exporting gas from a platform
(OP)
Why is it essential to dehydrate gas before it is compressed and exported from the platform?
Also, what special considerations must be given to the design and operation of the gas export pipeline if the gas contains substantial amounts of carbon dioxide?
Also, what special considerations must be given to the design and operation of the gas export pipeline if the gas contains substantial amounts of carbon dioxide?





RE: exporting gas from a platform
As something is compressed, thermodynamics suggests it heat up. Compressing gas also makes it "sweat"; water vapor naturally condenses out of a gas volume being compressed. Therefore, yes it is natural to dehydrate a gas prior to compression, unless you're into exporting water and rusting out your containers!
Carbon dioxide compositions typically need metallugical considerations for pipeline design. The phenonema known as pitting is a natural form of pipeline failure with high content carbon dioxide. Valves on the pipeline, particularly ball types, sieze due to explosive decompression in the rubber elements of the "soft seat" design. The explosive decompression is the result of carbon dioxide (or equally free hydrogen, nitrogen during purging operations) migrating into the interstital voids of the rubber compound, then naturally "expanding" as the valve is blown down to ambient conditions. You need to address the equipment design to mitigate carbon dioxide content, you will NEVER eliminate these problems totally.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: exporting gas from a platform