GAS CONDENSATE MERCAPTAN REMOVAL TECHNOLOGY

«DEMERUS GASCOND» process

Application area

DEMERUS GASCOND is used for low molecular weight mercaptan removal from gas condensate by transforming them into disulfides. Application of heterogeneous KSM-X catalyst eliminates the possibility of total sulfur content increase in purified gas condensate by disulfides.

Assignment 

Alkaline extraction of mercaptans contained in gas condensate, with the following oxidation of mercaptides to disulfides (disulfide oil).

Technology description

Schematic diagram of gas condensate sweetening:

Mercaptan removal from gas condensate

Stable gas condensate passes two stages of alkaline extraction of mercaptans. Firstly gas condensate is fed into the mixer M-101. It is mixed with an alkaline extractant dosed by pump P-101A/B from the bottom of settler D-102. The mixture of gas condensate and alkaline extractant is supplied to the first stage settler D-101. Gas condensate separated from the extractant flows from the top of D-101 into mixer M-102. It is mixed with regenerated extractant and supplied to the second stage settler D-102. During the interaction of feed with extractant in the static mixers chemisorption of mercaptans occurs with the formation of hydrocarbon‑insoluble mercaptides according to reaction (1):

RSH + КОН = RSК + H2O (1)

Purified from mercaptans stable gas condensate from the top of D-102 is removed from the unit.

Extractant saturated with mercaptides is removed from the bottom of D‑101 by phase interface level, heated in heat exchanger T-101 to 60 ÷ 70°C and supplied through the dispenser to the bottom of regenerator R-101. Air under pressure of 0.5 MPa is also supplied to the line before the inlet of R‑101. Mercaptides contained in the extractant are oxidized by atmospheric oxygen to disulfides on the surface of KSM-X according to reaction (2):

2RSК + 0.5 O2 + H2O → RSSR + 2КOH (2)

Exhaust air and regenerated extractant with disulfides are removed from the top of R-101 to settler D-103. From the bottom of D-103 regenerated extractant with disulfides is fed with pump P-102A/B through cooler E-102 to disulfides separator D-104. Disulfide oil from the top of D-104 is removed by the phase interface level to a storage tank.

Settled from disulfides regenerated extractant from the bottom of D-104 is returned to the second stage mixer M-102 for mercaptans removal from feed gas condensate.

Advantages

Technology «DEMERUS-GASCOND» using heterogeneous KSM-X catalyst has the following essential advantages:

  • Maximum extraction of mercaptans;
  • Obtaining of disulfides concentrate;
  • Catalyst lifetime warranty – 8 years.