Sulfur Recovery Chain

Question 1

Where does H2S come from in the refinery ?

Answer 1

• HDT units

- Conversion units without H2 (FCC, thermal cracking units)

Question 2

What are the steps in the sulfur recovery chain ?

Answer 2

1. Amine washing unit to purify H2S
2. Claus Unit to transform H2S into elementary sulfur
3. Tail gas treatment to have a total recovery of H2S > 99.5%

Question 3

What are the operating conditions of the amine washing unit

Answer 3

• Absorber : 40-45°C, 6 bar (high P, low T)

- Regenerator : 100-120°C, 2.2 bar (low P, high T)

Question 4

What are the reactions in the Claus unit ?

Answer 4

1. Combusion of 1/3 of H2S : H2S + 3/2 O2 -> SO2 + H20 + heat
2. Claus reaction : 2 H2S + SO2 ->

Question 5

What are the operating conditions of the burner in the Claus unit ?

Answer 5

• T = 1100-1200°C
• P = 0.8 bar
• H2S/SO2 ratio = 2

Question 6

What is the yield of the thermal stage of the Claus unit ?

Answer 6

60-70 %

Question 7

What are the operating conditions of the catalytic stage of the Claus unit ?

Answer 7

• T = 230°C
• Catalyst
• 2 reactors in series to control exoT

Question 8

What is the most common and efficient way to treat tail gas of the Claus unit ?

Answer 8

SCOT Process : turn SO2 back into H2S to recycle trhough the sulfur recovery chain