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Minimizing desiccant bed degradation
How Pall is helping Oil and Gas sector achieve on-spec sales gas quality for water content
Wet hydrocarbon gas enters the top of the adsorption tower and flows downward through the adsorbent where the water is adsorbed. The essentially dry hydrocarbon gas exits at the bottom and is ready for processing or sale. Common adsorbent materials include molecular sieves, silica gels and activated alumina in desiccant operations.
To maintain their effectiveness, desiccants must be protected from free water and liquid hydrocarbon contamination to achieve their anticipated 3 to 5 year life. Free water causes long term fracturing and dusting of the desiccant granules, while hydrocarbons burn onto the granules during regeneration, progressively reducing moisture removal capability.
What makes adsorbent dehydration so critical for Oil and Gas plants?
1. Protection from desiccant bed degradation:
Due to foreign material such as glycol, amine, lube oil, corrosion inhibitors and solids, there is desiccant bed degradation which coats and plugs the pores of the adsorbent, preventing access to the large interior surface.
In such a case, you can use High efficiency SepraSol™ Plus liquid/gas coalescers and Medallion™ HP liquid/gas coalescers which provide 99.999% removal at 0.3 microns per the DOP test and 1 ppb downstream as per the modified ANSI/CAGI-400-1999 test procedure.
This will improve your dehydration productivity and reliability with effective liquid and solid removal upstream of the desiccant beds and will protect against bed degradation and capacity loss.
2. Protection from bed damage:
Bed damage is largely caused due to large ingression of liquid water, causing the bed to
fracture. You can protect against introduction of slugs of water by capturing these slugs upstream of the desiccant beds. For this, we recommend:
- The SepraSol Plus liquid/gas coalescer assembly has a dual sump provision that accepts most slugs without bypass or loss of removal efficiency.
- Pall’s full element oleophobically treated SepraSol Plus coalescers also recover very quickly, minimizing the pressure drop across the assembly
3. Protection from damage due to downstream process equipment:
This is mainly caused due to entrainment of desiccant fines in the dry gas stream. We recommend using the Dry Gas Particulate Filter (DGPF) which removes desiccant fines and other contaminants from the dry hydrocarbon gas stream before it enters the pipeline, compressor, or catalyst bed.