4 replies to this topic

[KHAQAN ALI KHAN]

Hi, Trace amounts of mercaptans in gaseous LPG in storage spheres is found. I intend to find a Solvent/Scavenger solution that can selectively remove mercaptans (in ppm) from LPG. I have studied some literature and found some adsorbent beds related to the same problem for power industry but I have to remove it from my storage as recycling or reprocessing is not an option. Kindly suggest any additive for this purpose which is also not harmful for LPG consumption sources Regards, Khaqan

[RockDock]

That is interesting. I have heard of KOH beds that could possibly be used. The best solution would be to prevent this problem from happening in the first place. I know that doesn't solve your present problem, but have you addressed the underlying cause of this?

 

I suspect that you Caustic unit is not performing well. 

[Zauberberg]

This is commonly done via dedicated adsorbent beds for Mercaptan (and sometimes, water) removal. You should contact UOP, BASF/Grace, or CECA and provide them with contamination levels, species, product specification, inflow/outflow rates, and operating conditions, in order to obtain preliminary design and cost. There are several ways of regeneration of adsorbent depending on site conditions. Those I have seen usually employed Nitrogen and electric heater for regeneration because the relative volume of adsorbent beds is quite small when compared to larger process units.

 

If you receive LPG somewhere from offsite location and store it in your area, the adsorbent beds are normally located in the unloading line (from the trucks/containers towards the tank) so that the product entering storage sphere can be made on-spec. Obviously, once the contents of the storage spheres are contaminated there is no point to place the beds upstream of the vessels, but rather downstream in the pumpout line - or you can consider recycling.

 

http://adsorbents.bi...ce_removal.aspx

http://www.cecachemi...com/en/contact/

http://www.uop.com/p...ts/natural-gas/

[Zauberberg]

if this contamination is one-time event (i.e. it happened now and never expected to occur again), you might as well try to sell the contaminated product in the local market (for those users who can tolerate the current contamination levels), or simply dispose of the off-spec product. Investment in adsorbent beds may not be justified for a single case.

[P.K.Rao]

Mercaptans are usallay added to LPG for easy identification of leakages in domestic use because they have a very foul smell and can be easily identified by common non technical persons. If the LPG is meant for domestic use, a few ppm of mercaptans will not matter. If it is meant for industrial use and mercaptans are required to be  absent,totally, then they have to be removed.. Puraspec (www.matthey.com) has adsorbent material which can remove mercaptans if it is necessary for long term use.

If you need a small canister type equipment  which can be placed in the loading line to remove mercaptans at a few ppm level, please contact me at pkrao2012@yahoo.com

Mercaptan scavengers are also available but they will convert mercaptans to another sulfur compound which may a leave a residue during use.

Edited by P.K.Rao, 06 March 2015 - 04:04 AM.