In our Regenerative Caustic Treatment System, a naphtha current is added to aid in disulfide removal. Thus, the residual gas stream from the three-phase separation vessel of the oxidation section has the presence of hydrocarbons (Oxygen, nitrogen, and HC's). Which is the best destination for this stream in the refinery (Coking furnace firebox, flare, knockout fuel gas and knockout centrifugal compressor knockout drum, others)?Dec-2021
Saravana Perumal, UOP, firstname.lastname@example.org
Due to presence of oxygen, it is recommended to route residual gases (spent air) from caustic regeneration section to Coking Furnace Firebox. In general it is not recommended to route the oxygen containing gases to flare or to the fuel gas system, this is primarily the oxygen present in the spent air reacts with H2S in the fuel gas / flare gases results in the formation of elemental sulfur that may cause potential plugging issues.
syed mumtaz, Freelance Individual, email@example.com
Given the presence of both O2 and HC, the Coker furnace seems the desired desination to burn the HC off and consume O2. Flare KO drum addition means HC coming out of stack that may violate the local emissions standards and impact the surrounding communities. Fuel gas KO drum addition will impair the NG spec needed for the refinery burners, besides presence of O2 may cause formation of other compounds that can hinder flow through the orifice and the burners. Similar impacts can be expected with the compressor KO drum, O2 containing comppinds can deposit on the rotors and destabilize the compressor operation.