Process Description Chapter 2 Notes | EduRev

: Process Description Chapter 2 Notes | EduRev

 Page 1


AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
1 
CHAPTER – 2 
 
PROCESS DESCRIPTION 
 
2.1   INTRODUCTION 
 
The amine regeneration unit is designed to regenerate rich Diethanol 
amine containing H
2
S/CO
2
 from fuel gas amine absorber. LPG amine 
absorber (located in CDU) and rich amine solution from hydrocracker and 
Merox units to obtain lean DEA for reuse in amine absorption units. This 
chapter covers the process flow description of amine regeneration unit in 
detail. 
 
 
2.2 AMINE FLASH COLUMN AND HEAT EXCHANGER 
 
The rich amine containing absorbed H
2
S and CO
2
 from various amine 
absorber units enter the flash column 21C-001 at a pressure of 5.0 Kg/cm
2
g 
and temperature of 54 ?C under level control of various amine absorbers. A 
backpressure controller (21PIC-1302) is provided near flash column in order 
to avoid any flashing in the line. The flash column is a tall vertical vessel 
having diameter of 600mm at top section and 3600mm at the bottom section. 
At the top section of column packing has been provided and the height of 
packing is equivalent to one theoretical stage. The column has also 4 blind 
trays, the purpose of which is to allow sufficient residence time in the flash 
column. The flash column operates at a pressure of 1.0 Kg/cm
2
g. The feed 
enters below the packing and above the fourth tray. Because of the flashing, 
any hydrocarbons dissolved in the amine get liberated, thereby reducing the 
quantity of hydrocarbons going with the sour gas to sulphur unit, which 
Page 2


AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
1 
CHAPTER – 2 
 
PROCESS DESCRIPTION 
 
2.1   INTRODUCTION 
 
The amine regeneration unit is designed to regenerate rich Diethanol 
amine containing H
2
S/CO
2
 from fuel gas amine absorber. LPG amine 
absorber (located in CDU) and rich amine solution from hydrocracker and 
Merox units to obtain lean DEA for reuse in amine absorption units. This 
chapter covers the process flow description of amine regeneration unit in 
detail. 
 
 
2.2 AMINE FLASH COLUMN AND HEAT EXCHANGER 
 
The rich amine containing absorbed H
2
S and CO
2
 from various amine 
absorber units enter the flash column 21C-001 at a pressure of 5.0 Kg/cm
2
g 
and temperature of 54 ?C under level control of various amine absorbers. A 
backpressure controller (21PIC-1302) is provided near flash column in order 
to avoid any flashing in the line. The flash column is a tall vertical vessel 
having diameter of 600mm at top section and 3600mm at the bottom section. 
At the top section of column packing has been provided and the height of 
packing is equivalent to one theoretical stage. The column has also 4 blind 
trays, the purpose of which is to allow sufficient residence time in the flash 
column. The flash column operates at a pressure of 1.0 Kg/cm
2
g. The feed 
enters below the packing and above the fourth tray. Because of the flashing, 
any hydrocarbons dissolved in the amine get liberated, thereby reducing the 
quantity of hydrocarbons going with the sour gas to sulphur unit, which 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
2 
spoils the catalyst. Some H
2
S also gets liberated. A slipstream of lean amine 
solution making counter current contact with liberated gases over a packed 
bad again absorbs the liberated H
2
S. Flow of strip stream is indicated by FI-
1304. 
 
The liberated hydrocarbons from top of the column enter the flare 
header through a pressure control valve 21PV-1301B. 
 
The flash column 21C-001 top pressure is maintained at 1.0Kg/cm
2
g 
through a split range pressure controller 21PIC-1301, which operates the 
valves 21PV-1301A/B. 
 
When the column pressure increases 21PV-1301B opens and let off 
the liberated hydrocarbons to flare. When the pressure comes down 21PV-
1301A opens letting sweet fuel gas into the column. The column is provided 
with a 1.5” vent and pressure safety valves PSV-1301A/B. 
 
The relief gases from safety valve discharge into the flare header. A 
pressure gauge measures the column top pressure. A differential pressure 
indication PDI-1301 has been provided across the packing to indicate the 
pressure drop across packing. Flash column is also provided with a oil 
skimmer at the bottom to skim off any hydrocarbon liquid carry over along 
with rich amine. 
 
Column is provided with a level gauge LG-1301 and a level controller 
21LIC-1301 at the bottom. This controls the level in the flash column by 
Page 3


AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
1 
CHAPTER – 2 
 
PROCESS DESCRIPTION 
 
2.1   INTRODUCTION 
 
The amine regeneration unit is designed to regenerate rich Diethanol 
amine containing H
2
S/CO
2
 from fuel gas amine absorber. LPG amine 
absorber (located in CDU) and rich amine solution from hydrocracker and 
Merox units to obtain lean DEA for reuse in amine absorption units. This 
chapter covers the process flow description of amine regeneration unit in 
detail. 
 
 
2.2 AMINE FLASH COLUMN AND HEAT EXCHANGER 
 
The rich amine containing absorbed H
2
S and CO
2
 from various amine 
absorber units enter the flash column 21C-001 at a pressure of 5.0 Kg/cm
2
g 
and temperature of 54 ?C under level control of various amine absorbers. A 
backpressure controller (21PIC-1302) is provided near flash column in order 
to avoid any flashing in the line. The flash column is a tall vertical vessel 
having diameter of 600mm at top section and 3600mm at the bottom section. 
At the top section of column packing has been provided and the height of 
packing is equivalent to one theoretical stage. The column has also 4 blind 
trays, the purpose of which is to allow sufficient residence time in the flash 
column. The flash column operates at a pressure of 1.0 Kg/cm
2
g. The feed 
enters below the packing and above the fourth tray. Because of the flashing, 
any hydrocarbons dissolved in the amine get liberated, thereby reducing the 
quantity of hydrocarbons going with the sour gas to sulphur unit, which 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
2 
spoils the catalyst. Some H
2
S also gets liberated. A slipstream of lean amine 
solution making counter current contact with liberated gases over a packed 
bad again absorbs the liberated H
2
S. Flow of strip stream is indicated by FI-
1304. 
 
The liberated hydrocarbons from top of the column enter the flare 
header through a pressure control valve 21PV-1301B. 
 
The flash column 21C-001 top pressure is maintained at 1.0Kg/cm
2
g 
through a split range pressure controller 21PIC-1301, which operates the 
valves 21PV-1301A/B. 
 
When the column pressure increases 21PV-1301B opens and let off 
the liberated hydrocarbons to flare. When the pressure comes down 21PV-
1301A opens letting sweet fuel gas into the column. The column is provided 
with a 1.5” vent and pressure safety valves PSV-1301A/B. 
 
The relief gases from safety valve discharge into the flare header. A 
pressure gauge measures the column top pressure. A differential pressure 
indication PDI-1301 has been provided across the packing to indicate the 
pressure drop across packing. Flash column is also provided with a oil 
skimmer at the bottom to skim off any hydrocarbon liquid carry over along 
with rich amine. 
 
Column is provided with a level gauge LG-1301 and a level controller 
21LIC-1301 at the bottom. This controls the level in the flash column by 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
3 
regulating the feed to regenerator column 21C-002 by 21FIC-1401 provided 
on the discharge line of flashed rich amine pumps 21-PA-001A/B after the 
exchangers 21E-001A/B. 21LALL-1301 has been provided which give the 
low level alarm at the panel. 
 
  From the flash column, the rich amine at 1.3 Kg/cm
2
g pressure and 
54 ?C temperature is pumped by rich amine pump 21PA-001 A/B under 
flow controller 21FIC-1401, which is reset by flash column level controller 
21LIC-1301 to amine regenerator 21C-002 after preheating to 96 ?C in lean 
amine / rich amine exchanger 21E-001A/B. In 21E-001A/B rich amine is in 
tube side and the heat is supplied to rich amine by hot lean amine on shell 
side coming from the bottom of amine regenerator level controller on LIC-
1401 at 121.2 ?C which in turn cools down to 79.8 ?C. The lean amine from 
rich amine exchanger is further cooled to 47 ?C in lean amine cooler 21-E-
004 A/B and routed to Amine storage tank 21T-001. Temperature will be 
indicated by TI-1307. Lean Amine  at 47 ?C is pumped by lean amine 
pumps 21-PA-003A/B to amine absorbers in CDU, OHCU and Merox units. 
A part of lean amine (about 10% by volume) from lean amine cooler is used 
as slipstream to cartridge filters 21-GN-001/003 and charcoal filter 21-GN-
002. This removes solid particles picked up by amine in the system and to 
remove foam causing hydrocarbon substances and there after routed to 
storage tank. 
 
The hot rich DEA from the 21E-001A/B exchangers enter the amine 
regenerator 21C-002 through the flow control valve 21 FIC-1401 reset by 
Page 4


AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
1 
CHAPTER – 2 
 
PROCESS DESCRIPTION 
 
2.1   INTRODUCTION 
 
The amine regeneration unit is designed to regenerate rich Diethanol 
amine containing H
2
S/CO
2
 from fuel gas amine absorber. LPG amine 
absorber (located in CDU) and rich amine solution from hydrocracker and 
Merox units to obtain lean DEA for reuse in amine absorption units. This 
chapter covers the process flow description of amine regeneration unit in 
detail. 
 
 
2.2 AMINE FLASH COLUMN AND HEAT EXCHANGER 
 
The rich amine containing absorbed H
2
S and CO
2
 from various amine 
absorber units enter the flash column 21C-001 at a pressure of 5.0 Kg/cm
2
g 
and temperature of 54 ?C under level control of various amine absorbers. A 
backpressure controller (21PIC-1302) is provided near flash column in order 
to avoid any flashing in the line. The flash column is a tall vertical vessel 
having diameter of 600mm at top section and 3600mm at the bottom section. 
At the top section of column packing has been provided and the height of 
packing is equivalent to one theoretical stage. The column has also 4 blind 
trays, the purpose of which is to allow sufficient residence time in the flash 
column. The flash column operates at a pressure of 1.0 Kg/cm
2
g. The feed 
enters below the packing and above the fourth tray. Because of the flashing, 
any hydrocarbons dissolved in the amine get liberated, thereby reducing the 
quantity of hydrocarbons going with the sour gas to sulphur unit, which 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
2 
spoils the catalyst. Some H
2
S also gets liberated. A slipstream of lean amine 
solution making counter current contact with liberated gases over a packed 
bad again absorbs the liberated H
2
S. Flow of strip stream is indicated by FI-
1304. 
 
The liberated hydrocarbons from top of the column enter the flare 
header through a pressure control valve 21PV-1301B. 
 
The flash column 21C-001 top pressure is maintained at 1.0Kg/cm
2
g 
through a split range pressure controller 21PIC-1301, which operates the 
valves 21PV-1301A/B. 
 
When the column pressure increases 21PV-1301B opens and let off 
the liberated hydrocarbons to flare. When the pressure comes down 21PV-
1301A opens letting sweet fuel gas into the column. The column is provided 
with a 1.5” vent and pressure safety valves PSV-1301A/B. 
 
The relief gases from safety valve discharge into the flare header. A 
pressure gauge measures the column top pressure. A differential pressure 
indication PDI-1301 has been provided across the packing to indicate the 
pressure drop across packing. Flash column is also provided with a oil 
skimmer at the bottom to skim off any hydrocarbon liquid carry over along 
with rich amine. 
 
Column is provided with a level gauge LG-1301 and a level controller 
21LIC-1301 at the bottom. This controls the level in the flash column by 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
3 
regulating the feed to regenerator column 21C-002 by 21FIC-1401 provided 
on the discharge line of flashed rich amine pumps 21-PA-001A/B after the 
exchangers 21E-001A/B. 21LALL-1301 has been provided which give the 
low level alarm at the panel. 
 
  From the flash column, the rich amine at 1.3 Kg/cm
2
g pressure and 
54 ?C temperature is pumped by rich amine pump 21PA-001 A/B under 
flow controller 21FIC-1401, which is reset by flash column level controller 
21LIC-1301 to amine regenerator 21C-002 after preheating to 96 ?C in lean 
amine / rich amine exchanger 21E-001A/B. In 21E-001A/B rich amine is in 
tube side and the heat is supplied to rich amine by hot lean amine on shell 
side coming from the bottom of amine regenerator level controller on LIC-
1401 at 121.2 ?C which in turn cools down to 79.8 ?C. The lean amine from 
rich amine exchanger is further cooled to 47 ?C in lean amine cooler 21-E-
004 A/B and routed to Amine storage tank 21T-001. Temperature will be 
indicated by TI-1307. Lean Amine  at 47 ?C is pumped by lean amine 
pumps 21-PA-003A/B to amine absorbers in CDU, OHCU and Merox units. 
A part of lean amine (about 10% by volume) from lean amine cooler is used 
as slipstream to cartridge filters 21-GN-001/003 and charcoal filter 21-GN-
002. This removes solid particles picked up by amine in the system and to 
remove foam causing hydrocarbon substances and there after routed to 
storage tank. 
 
The hot rich DEA from the 21E-001A/B exchangers enter the amine 
regenerator 21C-002 through the flow control valve 21 FIC-1401 reset by 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
4 
the LIC-1301. A sample point is also provided at discharge of 21PA-001A/B 
pumps. Outlet of the same is routed back to suction of the pump. 
 
2.3  REGENERATION 
 
In the amine regenerator 21C-002, the rich DEA is stripped off of its 
absorbed sour gases H
2
S and CO
2
 using steam as the bottom heating media 
in both the re-boilers 21E-003 A/B provided at the bottom. 
 
Regenerated amine in this process reused in the absorbers. The amine 
regenerator 21C-002 is a tall vertical column 24200-mm high and has a 
diameter of 3600 mm. It contains 24 trays. The feed to amine regenerator 
enters the column on 21
st
 tray. Provision is there to introduce the feed on 17
th
 
and 19
th
 tray also. The amine regenerator operators at a top pressure of 0.90 
Kg/cm
2
g (floating on sulphur recovery unit) and condenser temperature of 
40 ?C. Reflux water enters the columns on 24
th
 tray and descends down. 
This prevents DEA losses into the overhead and ensures complete removal 
of H
2
S. The re-boiler vapours from the bottom of the tower counter currently 
contact the rich amine and strip it off H
2
S / CO
2 
present it the DEA solution. 
The chemical reactions involved are: 
 
R
2
NH
3
S ----------------------------- ? R
2
 NH + H
2
S 
(R
2
NH
3 
)  CO
3
------------------------- ? R
2
 NH + CO
2   
+ H
2
O
  
 
Where,   R is a CH
3
,CH
2
,OH group. 
 
The liberated sour gases and steam at 110 ?C and 0.90 Kg/cm
2
g 
pressure leave the regenerator from the top and enters the regenerator over 
Page 5


AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
1 
CHAPTER – 2 
 
PROCESS DESCRIPTION 
 
2.1   INTRODUCTION 
 
The amine regeneration unit is designed to regenerate rich Diethanol 
amine containing H
2
S/CO
2
 from fuel gas amine absorber. LPG amine 
absorber (located in CDU) and rich amine solution from hydrocracker and 
Merox units to obtain lean DEA for reuse in amine absorption units. This 
chapter covers the process flow description of amine regeneration unit in 
detail. 
 
 
2.2 AMINE FLASH COLUMN AND HEAT EXCHANGER 
 
The rich amine containing absorbed H
2
S and CO
2
 from various amine 
absorber units enter the flash column 21C-001 at a pressure of 5.0 Kg/cm
2
g 
and temperature of 54 ?C under level control of various amine absorbers. A 
backpressure controller (21PIC-1302) is provided near flash column in order 
to avoid any flashing in the line. The flash column is a tall vertical vessel 
having diameter of 600mm at top section and 3600mm at the bottom section. 
At the top section of column packing has been provided and the height of 
packing is equivalent to one theoretical stage. The column has also 4 blind 
trays, the purpose of which is to allow sufficient residence time in the flash 
column. The flash column operates at a pressure of 1.0 Kg/cm
2
g. The feed 
enters below the packing and above the fourth tray. Because of the flashing, 
any hydrocarbons dissolved in the amine get liberated, thereby reducing the 
quantity of hydrocarbons going with the sour gas to sulphur unit, which 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
2 
spoils the catalyst. Some H
2
S also gets liberated. A slipstream of lean amine 
solution making counter current contact with liberated gases over a packed 
bad again absorbs the liberated H
2
S. Flow of strip stream is indicated by FI-
1304. 
 
The liberated hydrocarbons from top of the column enter the flare 
header through a pressure control valve 21PV-1301B. 
 
The flash column 21C-001 top pressure is maintained at 1.0Kg/cm
2
g 
through a split range pressure controller 21PIC-1301, which operates the 
valves 21PV-1301A/B. 
 
When the column pressure increases 21PV-1301B opens and let off 
the liberated hydrocarbons to flare. When the pressure comes down 21PV-
1301A opens letting sweet fuel gas into the column. The column is provided 
with a 1.5” vent and pressure safety valves PSV-1301A/B. 
 
The relief gases from safety valve discharge into the flare header. A 
pressure gauge measures the column top pressure. A differential pressure 
indication PDI-1301 has been provided across the packing to indicate the 
pressure drop across packing. Flash column is also provided with a oil 
skimmer at the bottom to skim off any hydrocarbon liquid carry over along 
with rich amine. 
 
Column is provided with a level gauge LG-1301 and a level controller 
21LIC-1301 at the bottom. This controls the level in the flash column by 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
3 
regulating the feed to regenerator column 21C-002 by 21FIC-1401 provided 
on the discharge line of flashed rich amine pumps 21-PA-001A/B after the 
exchangers 21E-001A/B. 21LALL-1301 has been provided which give the 
low level alarm at the panel. 
 
  From the flash column, the rich amine at 1.3 Kg/cm
2
g pressure and 
54 ?C temperature is pumped by rich amine pump 21PA-001 A/B under 
flow controller 21FIC-1401, which is reset by flash column level controller 
21LIC-1301 to amine regenerator 21C-002 after preheating to 96 ?C in lean 
amine / rich amine exchanger 21E-001A/B. In 21E-001A/B rich amine is in 
tube side and the heat is supplied to rich amine by hot lean amine on shell 
side coming from the bottom of amine regenerator level controller on LIC-
1401 at 121.2 ?C which in turn cools down to 79.8 ?C. The lean amine from 
rich amine exchanger is further cooled to 47 ?C in lean amine cooler 21-E-
004 A/B and routed to Amine storage tank 21T-001. Temperature will be 
indicated by TI-1307. Lean Amine  at 47 ?C is pumped by lean amine 
pumps 21-PA-003A/B to amine absorbers in CDU, OHCU and Merox units. 
A part of lean amine (about 10% by volume) from lean amine cooler is used 
as slipstream to cartridge filters 21-GN-001/003 and charcoal filter 21-GN-
002. This removes solid particles picked up by amine in the system and to 
remove foam causing hydrocarbon substances and there after routed to 
storage tank. 
 
The hot rich DEA from the 21E-001A/B exchangers enter the amine 
regenerator 21C-002 through the flow control valve 21 FIC-1401 reset by 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
4 
the LIC-1301. A sample point is also provided at discharge of 21PA-001A/B 
pumps. Outlet of the same is routed back to suction of the pump. 
 
2.3  REGENERATION 
 
In the amine regenerator 21C-002, the rich DEA is stripped off of its 
absorbed sour gases H
2
S and CO
2
 using steam as the bottom heating media 
in both the re-boilers 21E-003 A/B provided at the bottom. 
 
Regenerated amine in this process reused in the absorbers. The amine 
regenerator 21C-002 is a tall vertical column 24200-mm high and has a 
diameter of 3600 mm. It contains 24 trays. The feed to amine regenerator 
enters the column on 21
st
 tray. Provision is there to introduce the feed on 17
th
 
and 19
th
 tray also. The amine regenerator operators at a top pressure of 0.90 
Kg/cm
2
g (floating on sulphur recovery unit) and condenser temperature of 
40 ?C. Reflux water enters the columns on 24
th
 tray and descends down. 
This prevents DEA losses into the overhead and ensures complete removal 
of H
2
S. The re-boiler vapours from the bottom of the tower counter currently 
contact the rich amine and strip it off H
2
S / CO
2 
present it the DEA solution. 
The chemical reactions involved are: 
 
R
2
NH
3
S ----------------------------- ? R
2
 NH + H
2
S 
(R
2
NH
3 
)  CO
3
------------------------- ? R
2
 NH + CO
2   
+ H
2
O
  
 
Where,   R is a CH
3
,CH
2
,OH group. 
 
The liberated sour gases and steam at 110 ?C and 0.90 Kg/cm
2
g 
pressure leave the regenerator from the top and enters the regenerator over 
AMINE REGENERATION UNIT 
 
CHAPTER-2 
 
5 
head condenser 21E-002 where the gases are cooled and steam is condensed 
to 40 ?C by cooling water on the tube side. The condensate and the gas flow 
freely from the condenser to the reflux drum 21V-001. The reflux drum is 
provided with a demister pad, which Knocks out any liquid carry over with 
the gases. 
 
The sour gases from the reflux drum top go to the sulphur recovery 
plant for production of sulphur. 21PIC-1406 controls the pressure of the 
reflux drum and hence the regenerator pressure at 0.90 Kg/cm
2
g by 
regulating the control valve 21 PV-1406 provided on the sour gas line to H
2
S 
flare header. Pressure safety valve PSV-1401 and 1402 have been provided 
on the 21C-002 top outlet line, outlet of the same is connected to acid gas 
flare. 
 
From the bottom of the reflux drum 21V-001, Reflux pumps 21PA-
002 A/B take suction and deliver the liquid to the regenerator top above the 
24
th
 trays as reflux. The reflux drum is provided with a level gauge LG-1402 
and a level controller 21 LIC-1402. 21PA-002 A/B pumps the reflux under 
flow controller FIC-1402 resetted by level controller 21 LIC-1402 of 21V-
001. LIC-1402 is also provided with low and high level alarm at the panel.  
A temperature indicator TI-1413 indicates the temperature of reflux drum. 
Anti foam agent is dosed by 1” line in the reflux line after flow control 
valve. Corrosion Inhibitor is dosed by 1” line in the  vapour line of the 
regenerator. 
 
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