Sinclair ARU 1&2 Amine Regeneration System Module PDF

## Overview: Environmental regulations limit the amount of hydrogen sulfide (H2S) that may be present when burning fuel gas in the Sinclair Refinery. The Amine Regeneration Unit (ARU) #1/#2, located in the Reformer Complex, provides a solution of methyldiethanolamine (MDEA) to remove harmful acid g...

## Overview: Environmental regulations limit the amount of hydrogen sulfide (H2S) that may be present when burning fuel gas in the Sinclair Refinery. The Amine Regeneration Unit (ARU) #1/#2, located in the Reformer Complex, provides a solution of methyldiethanolamine (MDEA) to remove harmful acid gases in the fuel gas streams. The amine is then regenerated. ### Amine Regeneration System The Amine Regeneration System is the final step in the ARU #1/#2. It receives rich amine, "rich" in hydrogen sulfide and carbon dioxide, from the Gas Contacting System. **The main objective of this system is to regenerate the rich amine so it can be reused as a solvent. Stripping technology is used to reverse the reactions that occurred in the Gas Contacting System, resulting in amine free of acid gases, known as "lean" amine. Hydrogen sulfide is recovered and provided as feed to the Sulfur Recovery Unit #1/#2.** ### Rich Amine Subsystem The Rich Amine Subsystem receives rich amine from the Gas Contacting System. Rich amine contains, or is "rich" in, sour gases such as hydrogen sulfide and carbon dioxide. The purpose of this subsystem is to separate and heat the rich amine, so it can be regenerated downstream. This is accomplished using a separation vessel and heat exchanger. Absorption technology is also used to remove any acid gases from the entering sour gas. - **Lean amine, free of acid gases, is pumped by the Amine #1/#2 Contactor Feed Pump East/South (5P-117/155) to the top of the scrubber.** ### Lean Amine Subsystem: The purpose of the Lean Amine Subsystem is to prepare the regenerated amine stream to be reused as a solvent for the absorption process. This is done by cooling and filtering the lean amine. Fresh amine can be provided to ensure the minimum lean amine strength is met. - **Nitrogen enters the subsystem from the Plant Nitrogen Header. It can be sent to the Nitrogen Header or through a filter.** ### Amine Regeneration Units #1 & #2 The Amine Regeneration Units #1 and #2 are nearly identical. Therefore, the information in this module applies to both units. Differences in process flow have been noted. Lines/valves that apply to only ARU #2 are tagged in blue. ## Rich Amine Depending on the line up, amine, rich in absorbed hydrogen sulfide (H2S) and some carbon dioxide (CO2), can be sent from the ARU Gas Contacting System to the ARU #1/#2 or ARU #3/#4. When the Gas Contacting System is lined up to the ARU #1/#2, rich amine is sent to the Amine Settler #1/#2 (5PV-1615/2248) from the HDS Stripper Contactor (5PV-1605), Medium Pressure Fuel Gas Contactor (5PV-2243) and the Fuel Gas Contactor (5PV-1604), as well as from the DEA Contactor (8PV-1701) in the Cat Poly Feed Treatment System. ### Rich Amine Settler - **Purpose:** The Rich Amine Settler is a three-phase separation vessel that removes lighter hydrocarbons from the rich amine before it is sent to the downstream regenerator. - **The entering rich amine undergoes a pressure reduction in the vessel, causing the light hydrocarbons to flash into vapour. Underflow and overflow baffles separate the floating liquid hydrocarbons from the rich amine.** - **Rich amine can be added to the Amine Settler feed stream from the #3 HDS Absorber (13PV-2306) in the #3 HDS Absorption System and the Rich Amine Settling Tank (5PV-2244) in the Gas Contacting System.** - **Rich amine can be pumped by the #2 Amine De-Inventory Pump (5P-158) from the De-Inventory Tank (5V-2258) to the rich amine feed stream. The De-Inventory Tank was removed and will be replaced in the future.** - **The sour overhead gas stream from the #2 HDS Wash Water Surge Drum (5PV-2213) in the #2 HDS Reaction System can be sent to the Amine Settler Scrubber #1/#2 (5PV-2236/2257).** ### Amine Settler Scrubber - **Purpose:** The Amine Settler Scrubber acts as an absorption column within the Amine Settler. It uses absorption technology to remove or "scrub" harmful hydrogen sulfide and carbon dioxide from the sour gas. ## Lean Amine - **Lean amine, free of acid gases, is pumped by the Amine #1/#2 Contactor Feed Pump East/South (5P-117/155) to the top of the scrubber.** - **Due to its high affinity for hydrogen sulfide, methyldiethanolamine (MDEA) is used as a solvent to absorb hydrogen sulfide, and some CO2, from the sour gas. As the lean amine flows down through the scrubber's internal packing, it contacts the counter-flowing gas stream. The H2S and CO2 in the sour gas stream, known as the "solute," transfers from the gas phase to the aqueous phase, where it reacts with amine. This results in rich amine, which falls down to the bottom of the amine settler.** - **Sweetened off-gas, free of hydrogen sulfide, exits the top of the Amine Settler Scrubber and can be sent to the Flare Header.** - **Rich amine is pumped by the Rich Solvent Pump East/West (5P-150/145) and South/North (5P-151/152) from the bottom of the Amine Settler to the Amine Regenerator #1/#2 Feed/Bottoms Exchanger (5EX-1647/2250).** - **Lean amine from the #1 ARU Amine Filter East/West (5PV-2291/2292) ties into the suction of the Rich Solvent Pumps.** - **If needed, the Rich Solvent Pumps can be bypassed and the mixed rich and lean amine stream can be routed directly to 5EX-1647/2250.** ## Amine Regenerator - **The Amine Regenerator is a 20 tray tower that uses stripping technology to remove the acid gases, such as hydrogen sulfide (H2S) and carbon dioxide (CO2), from the rich amine.** - **Because the reactions that take place between the amine and acid gases in the Gas Contacting System are reversible, the Amine Regenerator is able to thermally dissociate, or break apart under the presence of heat, the acid gases from the amine.** - **Preheated rich amine is sent from the Amine Regenerator #1/#2 Feed/Bottoms Exchanger (5EX-1647/2250) to tray #17 of the Amine Regenerator #1/#2 (5PV-1603/2252).** - **Rich amine is routed from the Amine Regenerator #1/#2 to the shell side of the Amine Regenerator Reboiler #1/#2 (5EX-1648/2253). It is heated by steam flowing through the tube side of the exchanger.** - **Heated and vaporized rich amine is returned to the Amine Regenerator, below tray #1.** - **The vapor rises up the column, contacting the downward-flowing liquid stream. The reboiler provides the heat and vapor that is required to drive off the acid gases from the amine.** - **Regenerated amine, free of acid gases, exits the bottom of the Amine Regenerator to 5EX-1647/2250 to be cooled. The regenerated amine is known as "lean" amine.** ## Further Processing - **Sour gas and water vapor, containing H2S and CO2, exit the top of the tower to the shell side of the Amine Regenerator #1/#2 Overhead (OH) Condenser (5EX-1650/2256). The OH gas stream is cooled by tube side cooling water.** - **The condensed overhead stream flows into the Amine Regenerator #1/#2 Overhead Accumulator (5PV-1611/2255).** - **Acid gas exits the overhead accumulator as feed to the Sulfur Recovery Unit (SRU) #1/#2 for elemental sulfur recovery. A portion of the acid gas can be vented to the Flare Header.** - **Sour water is pumped by the Amine Regenerator #1/#2 North/East (5P-116/154) and South/West (5P-115/153) from the bottom of the overhead accumulator to the Amine Regenerator #1/#2 (5PV-1603/2252).** - **Sour water is returned to the tower, as reflux, above tray #20. The reflux flow rate is controlled to maintain the level in the Amine Regenerator Overhead Accumulator.** - **A portion of the sour water can be pumped by 5P-115/153 to the SWS Collection Drum (14PV-2402) to be collected and recovered.** - **A portion of the sour water can be pumped by 5P-116/154 to the Sour Water Tank (9TK-312) on level control.** ## Lean Amine - **Lean amine is routed from the bottom of the Amine Regenerator #1/#2 (5PV-1603/2252) to the shell side of the Amine Regenerator #1/#2 Feed/Bottoms Exchanger (5EX-1647/2250). It is cooled by rich amine flowing through the tube side of the exchanger.** - **Rich amine is pumped by the Rich Solvent Pump East/West (5P-150/145) and South/North (5P-151/152) through the tube side of 5EX-1647/2250. It is heated by the hot lean amine flowing through the shell side of the exchanger.** - **Cooled lean amine flows through the shell side of the Amine Regenerator #1/#2 Bottoms Cooler (5EX-1649/2251). It is cooled by cooling water flowing through the tube side of the exchanger. If needed, the exchanger can be bypassed on temperature control.** - **The cooled lean amine is pumped by the Amine #1/#2 Contactor Feed Pump West/North (5P-118/156) and East/South (5P-117/155) from the cooler to the Fuel Gas Contactor (5PV-1604), HDS Stripper Contactor (5PV-1605), and Medium Pressure Fuel Gas Contactor (5PV-2243) in the Gas Contacting System. The lean amine is used as a solvent for acid gas removal.** - **A portion of the 5P-117/118/155/156 discharge flows through the Amine Filter #2 (5PV-2249) and returns to the suction of the pumps.** - **Lean amine enters from the Lean Amine Header and is routed to the suction of 5P-117/155.** ## Fresh Amine - **Filtered nitrogen is sent to the Fresh Amine Storage Tank (5TK-XXX) on pressure control.** - **Nitrogen is used to pressure the fresh amine from the tank into the system. It can also be used to purge the tank.** - **"Fresh" amine is a dilute amine solution that has not been contacted with acid gas.** - **As needed, fresh amine is pumped by the Amine Changeout Pump (5P-148) from 5TK-XXX to the lean amine line to 5P-117/155.** - **A portion of the lean amine pumped by 5P-117/155 can be split into two streams. One stream is returned to the Amine Settler Scrubber (5PV-2236/2257) as a solvent to absorb acid gases.** - **The second lean amine stream is pumped by the High Pressure Amine Pump East/West (5P-131/130) to the DEA Contactor (8PV-1701) as a solvent.** ### Legend: - **Rich Amine** - **Lean Amine** - **Nitrogen** - **Cooling Water**