Mercury Removal for Natural Gas Processing

[DoraeS]

Hi, I have gas treating plant with dehydration and mercury removal units. So fa r I only see the mercury removal unit located at the downstream of the Dehydration Unit. Does anyone know the reason? Is it because the Hg Removal Unit can receive "less" gas after dehydration? Thanks.

 

[TD2K]

It appears to be based on what is used to remove the mercury based on a quick look. The following was found in an online article written by someone at Bechtel.


LNG plants typically use activated carbon mercury removal technology, except in one plant where the PURASPEC mixed oxide adsorbent technology is used. The use of PURASPEC was to reduce pressure drop in the mercury removal bed. Another major advantage of this technology is the ability to operate in wet gas service compared to the activated carbon that must operate in a dry atmosphere.

As is common practice, the mercury removal bed was located downstream of the mole-sieve bed. During startup the bed became wet and later water evolved from the bed and moved downstream into the cold section of the plant. Attempts to dry the PURASPEC bed took much longer than in activated carbon beds. Locating the PURASPEC bed upstream of the dehydration bed has significant operational advantages. This learning was shared with the vendor, who has updated their recommendation to now include locating this bed upstream of the dehydration bed.