Sinclair 3HDS Absorption System PDF

# Absorption System ## Overview: The purpose of the #3 Hydrogen Desulfurization (HDS) Unit is to produce distillate product. This unit uses a blend of light distillate, medium distillate, light cycle oil, light coker gas oil, and mixed gas oils from various locations in the refinery. The Absorptio...

# Absorption System ## Overview: The purpose of the #3 Hydrogen Desulfurization (HDS) Unit is to produce distillate product. This unit uses a blend of light distillate, medium distillate, light cycle oil, light coker gas oil, and mixed gas oils from various locations in the refinery. The Absorption System receives sour hydrogen gas from the #3 HDS Reaction and Separation System. Amine absorption technology is used to remove the toxic hydrogen sulfide impurities from the sour gas. This allows the sweetened hydrogen to be compressed and returned to the Reaction and Separation System to be used in the catalytic hydrotreating process. Lean methyldiethanolamine (MDEA) is filtered, removed of water, and used as a solvent to absorb the hydrogen sulfide from the gas stream, resulting in "rich amine". The sweet hydrogen stream, free of acid gas, is provided as feed to the #3 HDS Compression 1 and 2 System. The rich amine is sent to the Amine Regeneration Unit (ARU) #1/#2 or ARU #3/4 to be regenerated and reused. ## Lean Amine Subsystem ### Overview: The main objective of the Lean Amine Subsystem is to prepare the lean amine for use as a solvent in the #3 HDS Absorber. This is accomplished by filtering debris from the lean amine stream to prevent foaming. - Lean methyldiethanolamine (MDEA) enters the subsystem from the Reformer or Coker Lean Amine Header, depending on the line-up. It flows through the Particulate Filter (13PV-2321A/B/C). - **Purpose**: Vessels 13PV-2321A/B/C contain filter baskets that remove any suspended solid particles from the lean amine to protect downstream equipment and extend the life of the Coalescer (13PV-2320). - The filtered lean amine exits the Particulate Filter and splits into two streams. A portion of the filtered lean amine is routed through the Coalescer. - **Purpose**: The Coalescer uses a bed of coal to remove any dissolved contaminants that may otherwise cause foaming of the amine solution. - Lean amine exits the Coalescer and is routed through the Particulate Filter After Carbon Bed (13PV-2322A/B). - **Purpose**: Vessels 13PV-2322A/B contain finer micron filtering media than 13PV-2321A/B/C. These filters further remove any debris from the lean amine. This prevents any Coalescer fines from entering the amine circuit, in order to protect downstream equipment. - If needed, condensate can be pumped by the Condensate Pumps East/West (13P-107/108) from the Condensate Pot (13PV-2315) to the inlet of 13PV-2322A/B. - The remaining lean amine exiting 13PV-2321A/B/C is routed to the suction of the Absorber Lean Solvent Pump West/East (13P-109/110) on flow control. It combines with the lean amine exiting 13PV-2322A/B. The combined lean amine stream is pumped by 13P-109/110 to the #3 HDS Absorber (13PV-2306) as a solvent. ## #3 HDS Absorber ### Overview: The Absorption Subsystem receives sour hydrogen gas from the Reaction and Separation System. Amine absorption technology is used to remove the toxic hydrogen sulfide from the sour hydrogen. This allows the hydrogen to be compressed and returned to the Reaction and Separation System to be used in the catalytic hydrotreating process. - Sour gas containing mainly hydrogen, hydrogen sulfide (H2S), and ammonia (NH3) enters the subsystem from the top of the Effluent Cold Separator (13PV-2318) in the #3 HDS Reaction and Separation System. It is fed to the bottom of the #3 HDS Absorber (13PV-2306) and flows upward - **Purpose**: The #3 HDS Absorber is a 15 tray absorption column that uses amine absorption technology to remove H2S from the hydrogen stream. - Methyldiethanolamine (MDEA) is pumped by the Absorber Lean Solvent Pump West/East (13P-109/110) to the top of the absorber, on flow control. It is known as "lean amine" because it is free of acid gas. - **Purpose**: Due to its affinity for hydrogen sulfide, MDEA is used as a solvent to absorb toxic hydrogen sulfide from the gas stream. As the lean amine flows down through the trays in the absorber, it contacts the counter-flowing gas stream. The hydrogen sulfide in the gas stream, known as the "solute," transfers from the gas phase to the aqueous phase, where it reacts with amine. This results in amine that is rich in hydrogen sulfide, known as "rich amine". - The sweetened hydrogen, free of H2S, exits through the top of the absorber to the Recycle Hydrogen Knock Out (KO) Drum (13PV-2314) in the #3 HDS Compression 1 and 2 System. The hydrogen is compressed and returned to the Reaction and Separation System to provide a hydrogen-rich feed to the Distillate HDS Reactor West/East (13PV-2301/2302). - Recycle hydrogen can be sent to the #2 HDS Fuel Gas Manifold on pressure control. It is mixed with hydrogen bleed from the Train 1 and Train 2 High Pressure Separators (21PV-2636/2637) in the Hydrocracker Unit. - Rich amine, containing the hydrogen sulfide that was absorbed from the sour gas feed, exits the bottom of the tower on level control. It is mixed with a portion of rich amine exiting the top of 13PV-2306. - A portion of the rich amine from 13PV-2306 is sent to the Amine Decanter (13PV-2307). - **Purpose**: The Decanter is a vertical separation vessel used to separate any vapor from the rich amine to prevent damage to the downstream pump and other equipment. - The #3 HDS Absorber is equipped with an internal water boot that collects any sour water present in the feed streams. - Sour water can be drained from the bottom of the absorber and combined with the drains from 13PV-2314, the Particulate Filter (13PV-2321A-C), and the Particulate Filter After Carbon Bed (13PV-2322A/B). The combined stream is routed to the decanter feed to be separated. - Sour gas exits the top of the decanter to the Flare Header. - Rich amine liquid is pumped by the Decanter Pump (13P-111) from 13PV-2307 to the Rich Amine Header. Depending on the line up, the rich amine can be routed to either the #1/2 ARU or #3/4 ARU for regeneration. ## Rich Amine Header - The bulk of the rich amine is routed to the Rich Amine Header. This allows the rich amine to be sent to the Amine Regeneration Unit (ARU) #1/2 or ARU #3/4 to be regenerated, depending on the line up. It is mixed with rich amine from the Recycle Gas Absorbers (25PV-2867 and 21PV-2720) and from the Reformer Rich Amine Header. - A portion of the rich amine can be sent to the Amine Settler (5PV-1615) or to the Medium Pressure Fuel Gas Contactor (5PV-2243). - A portion of the rich amine from 13PV-2306 is sent to the Amine Decanter (13PV-2307). - **Purpose**: The Decanter is a vertical separation vessel used to separate any vapor from the rich amine to prevent damage to the downstream pump and other equipment. - The #3 HDS Absorber is equipped with an internal water boot that collects any sour water present in the feed streams. - Sour water can be drained from the bottom of the absorber and combined with the drains from 13PV-2314, the Particulate Filter (13PV-2321A-C), and the Particulate Filter After Carbon Bed (13PV-2322A/B). The combined stream is routed to the decanter feed to be separated. - Sour gas exits the top of the decanter to the Flare Header. - Rich amine liquid is pumped by the Decanter Pump (13P-111) from 13PV-2307 to the Rich Amine Header. Depending on the line up, the rich amine can be routed to either the #1/2 ARU or #3/4 ARU for regeneration. ## Legend | Color | Description | |---|---| | Purple | Lean Amine | | Yellow | Rich Amine | | Blue | Hydrogen | | Green | Sour Water |