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Gas Sweetening
&Dehydration
Process
Presented by: Aniruddh Singh Shekhawat
• Introduction• H2S & it’s need of processing• Gas Sweetening Process• Gas dehydration Process• Recap
What is Sour Gas?Sour Gas is a Natural Hydrocarbon gas with acid gases; most commonly Carbon dioxide, hydrogen sulphide & to some extent mercaptans.
Natural Gas
Non-Hydrocarbon
(Acid Gas)Hydrocarbon
Industrial effects
Corrosion
Environmental effects
Acid rain, Poisoning
Gas Terminal
GSU DPDU
CFU
GDU
LPGU
KRU
CWU
SRU
36” 42”
Sulfur
Sweet gas to HBJ PL
Sweet gas to Local consumers
LPG
ARN
HCSKO
ACID GAS
SOUR GAS
SOUR COND
From Offshore
HSDATF
• H2S is a highly toxic & Colourless flammable gas
• Corrosive to all metals (less corrosive to SS)
• Can cause catalyst poisoning in refinery processes
• On combustion forms toxic gas SO2.
• 4.3% LEL and 45% HEL by volume with an auto- ignition temperature of 500oF (292oC)
• Heavier than air (1.18 times heavier)• It may accumulate in dangerous
concentrations in drains, valve pits, vessels and tanks.
• Has no heating value.•Yet constitutes a volume-filler
• Corrosive in presence of water.
• Promotes hydrate formation.
CO2
Note: The composition of components is from ADMA Company
Components Mole Fraction at I/L
Mole Fraction at O/L
Hydrogen SulphideMethaneEthanePropaneIsobutanenbutaneIsoPentanenPentaneHexaneCarbon Dioxide
0.013%81.7%6.34%3.72%0.70 %0.86%0.15%0.13%0.05%6.30%
0.0004%82.8%6.39%3.77%0.74%0.84%0.16%0.15%0.07%4.9%
Significant factors are;1. Type & conc. of impurities.2. Degree of removal of impurities or
selectivity of acid component removal.3. Volume of the Gas stream.4. Temp. & Pr. Conditions5. HC Composition.6. Economics
1. Non-regenerative
2. Regenerative process• Physical absorption-water wash,
selexol, fluor solvent etc.• Chemical absorption- The alkonol-
amine processes3. Regenerative process with elemental
sulphur recovery
PHASE ITRAIN #
PHASE II
PHASE III
PHASE III A
CAPACITY313233
3435
36
3738
5.6 MMSCMD each
5.6 MMSCMD each
5.6 MMSCMD each
6.3 MMSCMD each
Amine type Chemical formula
Mol. Wt. Vapour pressure at
370C
Removal capacity%
MEA (Mono ethanol amine)
HO C2H4NH2 61.08 1.05 100
DEA (Diethanol amine) (HOC2H4)2NH 105.14 0.058 58
TEA (Triethanol amine) (HOC2H4)3N 148.19 0.0063 41
DGA (Di glycolamine) H(OC2H4)2NH2 105.14 0.160 58
DIPA (Di-isopropanol amine)
(HOC3H6)2NH 133.19 0.010 46
MDEA (Methyl diethanol amine)
(HOC2H4)2NH3 119.17 0.0061 51
P301A/B, MULTISTAGE CENTRIFUGALPUMP
E305 PREHEATER
V301INLETKOD
ROVs
SWEET GAS OUT
V302OUTLET
KOD
SWEET GAS TOGDU
SOUR GAS FROM SLUG CATCHER
ABSORBERCOLUMN
C301
TRAY 9
TRAY 7
TRAY 5
TRAY 3
TRAY 1
SOUR GAS IN
“RICH” MDEA TO V303MP FLASH DRUM
MDEA TANKT301
H2S Absorption
E306COOLER
LV112
SDV104
PV & FV101
MDEAMethyl Di Ethanol Amine
+ H2SMDEA-H, HS
+ -
Amino Hydro Sulphide
High Press.Low Temp
Absorption :
Regeneration :
MDEA-H, HS
Low Press.High Temp
MDEAMethyl Di Ethanol Amine
+ H2S+ -
• MDEA reacts instantaneously with H2S • H2S reacts to yield Hydro sulphide by proton transfer.• H2S + Amine(R2NH2) HS- + (Amine) H+ • CO2 can only react if it dissolves in water to form
bicarbonate ion.• Then this ion undergoes acid-base reaction with the
amine to yieldH2O + CO2 H2CO3 & CO2 + HO- HCO3-
• These acids then react with amine to form amine bicarbonate (HCO3-, RNH2+) and amine carbonate.
CO2 + H2O + R2NCH3 R2NCH4+ + HCO3- (Slow reaction)
H2S reacts to give amine hydrosulfide:1. H2S + R2NH ↔ HS - , R2NH2+CO2 can react directly with amine to form
an amine carbonate:2. CO2 + 2R2NH ↔ R2NCOO-, R2NH2+3. CO2 + H2O ↔ H2CO3
4. CO2 + HO- ↔ HCO3-5. These acids then react with the amine
to form amine bicarbonate (HCO3,- RNH2+) and amine carbonate (CO2, (R2NH2+)2).
The overall reaction depends upon contact time.Contact time depends on………
• The gas flow rate• The liquid height above plate area (Weir height)
• Number of active trays• Only parameter that can be varied is the number of active trays.
PV218
PV216
TO FLARE
TO FUEL GAS HEADER
LV215
FV205
‘LEAN’ AMINE
“RICH” MDEA TO V303MP FLASH DRUM
C303COL.
MP FLASH DRUMV303
TO C302
TC558
E302 A/BCOOLER REGENERATED AMINE
FROM C302
E301A/B PHE
TO TANK 301
PLATE HEAT EXCHANGERS
ACID GAS OUT
V304REFLUX
KODREGENERATORCOLUMN
C302
SOUR GAS IN
E303COOLER
SOUR GAS IN
“RICH” MDEA FROM V303 THRU’ E301PV326
PV327
TO FLARE
P304A/B
TO SRU
LV330
LV327
SDV309
E304REBOILER
REGENERATED AMINE TO TANK
REBOILERS
Kettle-type Reboiler Heat Exchanger Model
H2S C1 C2 C3 iC4 nC4 iC5 CO2
6800 to 6900
1.48 0.2 .02 .02 .03 .16 98.25
X301M
FV221
P303A/B
P307
FV522
V311
DM WATERSUPPLY
T303
STIRRER
Charcoal Bed
CATRIDGE
PRECOAT
PSV1525
PSV1523PSV1524
MDEA TANKT301
X302
• Precoat filter is designed to filter solids such as iron sulphides & iron carbonates
• V311 holds a bed of charcoal as part of filtration package
• Then the stream (20% of the total MDEA flow in the system) passes thru’ activated charcoal filter removing odour, impurities, colour & hydrocarbon.
• X 301 & X302 are precoat & cartridge type filters• Then the cartridge takes any entrained micro
solids
LL103
ANTIFOAM TANKV361
(Dimethylpolysiloxanic oil)
FUEL GAS BLANKETP361A/B
LL301
FLARE GAS
LH302
TO FLARE
P362A/B
FLARE GAS KODV362
TOSLOPTANK
FUEL GAS FROM C303
FUELGASKODV363
FUEL GAS
LV403
PV601
METHANOLTANKLH602
LL602
P363A/B
ANTIFOAM RETURN
FUEL GAS FROM C303
LHH224 LLL109 PB101
LL111
SOV1104
LLL109 PB101
LL111
SOV1101
SOV1102
PB101SOV1318(PV327)
SOV1216(PV216)
SOV1317(FV309)
P303A/B ST
MP FL DRM V303 C301 ABSORBERC301 BTM SDV104
I/L SDV
LL334P304A/B ST
LLL109 PB101
LL111
SOV1205
SOV1206
P301A
P301B
SOV1309(FV309)
LL335P305 ST
PB121
PL561
AB-BYPASS SWITCH
FL104
SOV1205LL549 LH110 LH219 PB111
PB112
LL329 PB118
V304 REF DRM
V305 SUMP (PANEL PUSH BUTTON)
T301 TANK ABSORBER O/L KODV302
C302 REG CLMN (UNLATCHING SWITCH)
EQUIPDETAIL
SOUR GASHEATERE305
SOUR GAS KOD V301
ABSORBER COLMN C301
FUEL GAS STRIPPERC303
RICH AMINE FLASH DRUM V303
SWEET GAS COOLER E306
FLARE GAS HEATER E307
LEAN AMINE STORAGE TANK T301
DUTY 4.655 X 1.1 MM KCAL/H
NA NA NA NA 0.778 X 1.1 MM KCAL/H
0.905 X 1.1 MM KCAL/H
NA
DIMENSION (MM)
NA 3300 DIA X 4850TL
31OO OD X 11850 H
510 DIA X 4000 H
2200 DIA X 6000TL
NA NA 6000 DIA X 9000 H
DESIGN PRESSUREKG/CM2
NA 83 83 10 10 NA NA ATM
DESIGN TEMP DEGREE CELSIUS
NA 49 75 75 75 NA NA 60
EQUIPDETAIL
TREATED GAS KODV302
KETTLE TYPE REBOILER E304
REGEN. COL. C302
FUEL GAS STRIPPERC303
PLATE TYP AMINE-AMINE EX. E301A/B
OVERHEAD CONDSRE303
REFLUX DRUM V304
LEAN AMINE COOLER E302A/B
DUTY NA 13.77 X 1.2MM KCAL/H
NA NA 7.96X 1.1 MMCAL/H
6.91 MMCAL/H
NA 5.14 X 1.1 MM KCAL/HR
DIMENSION (MM)
3300 DIA X 4200H
NA 2900 OD X 19150 H
510 DIA X 4000 H
NA NA 1400X 3000H
NA
DESIGN PRESSUREKG/CM2
82.05 (S/T): 6.5XFV/9X FV KG/CM2G
6.5 & VACUUM
10 NA (S/T): 6.5 FV/7.5
6.5 & FV (S/T): 6.5/7.5
DESIGN TEMP DEGREE CELSIUS
53 (S/T):144/200
195 75 NA (S/T): 127/58 95 (S/T): 88/58
Adsorption is the process of removing impurities from a gas stream by means of a solid material called adsorbent that has special attraction for the impurities.
• Chemical Formula: HO(C2H4O)3H• Adsorbs water from the Gas until the
equilibrium partial pressure of TEG & water in the gas is reached.
• Bonding with water forms H-OHHO-CH2-CH2-O-CH2-CH2-OCH2-CH2-OH
• Results achieved-1 to 2% of moisture by wt in the outlet
HO ( C2 H4 O )3 H
Triethylene Glycol (TEG)
H2O
RICH TEG
Adsorptionat
High PressLow Temp
H2ORegeneration
at Low PressHigh Temp
PHASE ITRAIN #
PHASE II
PHASE III
PHASE III A
CAPACITY4142
4344
4546
47
5.7 MMSCMD each
5.7 MMSCMD each
5.7 MMSCMD each
6.3 MMSCMD each
P401A/B, DOUBLE ACTINGRECIPROCATING PUMP
V404INLETKOD
TEG
GAS OUT
V401OUTLET
KOD
SWEET GAS TODPD
SWEET GAS FROM GSU
ABSORBERCOLUMN
C401
TRAY 1 TO 9
“RICH” TEG
LV106
SDV104
PV & FV101
SURGE DRUMV403
REGENERATED TEG FROM E401
E403COOLER
E402REBOILER
VAPOUR VENT
TV215
FUEL GAS FOR STRIPPING (FT202)
TO SURGE DRUMV403
C403
E401 PHE
HP STEAM
DE
GA
SS
ER
DR
UM
V40
2
CH
AR
CA
OL
BE
D
LV116
CATRIDGE FILTER
FUE
L G
AS
‘RIC
H’ T
EG
FR
OM
C40
1
C402REGEN
• The relatively cool TEG from C401 bottom does two things;• One, it brings down the temperature of the vapour leaving the
C402 top thru’ three way valve• Two, the other stream goes into the plate heat exchanger E401
to cool the regenerated glycol before going into V303 and in turn getting itself heated upto 145 deg before entering C402 having 4 bubble cap trays.
• TV 212 controls the temp of reboiler where the TEG at 185 deg overflows into the attached C403 end mounted on the side of the reboiler. C403 is a packed column where the hot fuel gas from V401/402 preheated inside a 2nd coil in E402, strips the glycol of remaining moisture to achieve 99.7% purity.
• This stripped glycol comes in contact at E401 with the cooler rich TEG from C401 & reaches 80-deg.
• Stripper gas is piped into E402 & V403 to maintain +ve pressure.
• The reciprocating TEG pumps attached to V403 completes the cycle of pumping TEG into the column C401.
LLL105 FL106 PB101SOV1103
LL218 PB106P403 ST
LLL105 FL106 PB101SOV1101
LLL105 FL106 PB101P401A/B STOP
LLL105 PB101SOV1102
LLL133 PB101SOV1105
THH210 PB101SOV1212 (TV212)
LLL132 PB101SOV1104
C401 ABSORBER TEG FLOWLOW SWITCH
V404 I/L KOD
V401 DRYGAS SCRUBBER
E402 REBOILER TEMP
SUMP V405
I/L SDV
O/L SDV
C401 BOTTOM
EQUIP
DETAIL
FEED GAS KOD V404
GLYCOL ABSORBER COLUMN C401
DRIED GAS SCRUBBER V401
RICH GLY DEGASSING DRUM V402
LEAN GLY TRIM COOLER E403
DUTY NA NA NA NA 0.164X1.2MMKCAL/H
DIMENSION (MM)
3300 DIA X 3250H
2800 DIA X 9000H
3600 DIDX 4200H
1100 DIA X 3250H
2200 DIA X 6000TL
DESGN PRESSUREKG/CM2
81.4 81.4 81.06 10 (S/T): 7.5/ 82
DESIGN TEMP DEGREE CELSIUS
55 60 60 55 (S/T): 60/120
EQUIP
DETAIL
GLYCOL STRIPPG COLUMNC403
GLYCOL REG. C402
LEAN GLYCOL SURGE DRUM V403
LEAN GLYCOL TANK T401
GLY-GLY HEAT EXCH. E401A/B
RICH GLYCOL REBOILERE402
DUTY NA NA NA NA 0.627X1.2MM KCAL/H
0.625X1.2 MM KCAL/H
DIMENSION (MM)
500 DIAX 2150H
600DX 4200L (UPPER) 800X2590 (LOWER)
1000 DIA X 4000L
4500 DIA X 3000H
NA NA
DESGN PRESSUREKG/CM2
1.1 1.1 1.1 ATM (S/T): 1.0/ 39 (S/T): 1.0/ 39 & FV
DESIGN TEMP DEGREE CELSIUS
240 220(TOP) 240(BTM)
240 60 (S/T): 240/220
(S/T): 240/260
The incoming sour gas is treated by washing/scrubbing with aqueous solution MDEA (Methyldiethanolamine).
Selectively removing H2S from 1375ppm (max) down to 4ppm & limiting CO2 co absorption to max of 32%.
Processing Acid Gas at SRU for Sulphur Removal.Removing moisture, entrained or enriched during
sweetening, in Gas Dehydration Unit with TEG upto -46 deg celsius.