This document describes the sulfur removal system for a natural gas plant. It contains the following key points: 1. The system has a processing capacity of 71 mmscfd of sour natural gas and uses MDEA to selectively remove H2S and produce sweet natural gas containing less than 7.5 ppm of H2S. 2. The process flow involves absorption of acid gases like H2S in an amine absorber, flashing of the rich amine, amine regeneration, and preparation and recycling of the lean amine. 3. Safety systems include safety valves, interlock shutdown systems, gas detection alarms, purging lines, and fire hydrants to safely handle startup, shutdown and operation

1. 单击此处编辑副标题
NATURAL GAS PLANTNATURAL GAS PLANT
CNOOC IRAQ MISSAN OIL FIELD
DEVELOPMENT PROJECT
SULFUR REMOVAL SYSTEM

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CONDITION OF ROW MATERIALS AND PRODUCTS
Process method and characteristics
INTRODUCTION
PROCESS FLOW
55 KEY SAFETY SYSTEMS

3. The processing capacity for this section (Sulfur
Removal Section) is 71 mmscfd (200×104
m3
/d) for
sour natural gas (the standard gas conditions being
15.6℃, 101.325kPa, the same below), with the
normal operation flexibility to be 50%~105%.
Sulfur Removal Section consist of Amie absorption,
Flashing of rich amine ， Amine regeneration and
The preparation and introduction system of the
solution.
1.1. GeneralGeneral

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CONDITION OF ROW MATERIALS AND
PRODUCTS
Process method and characteristics
INTRODUCTION
PROCESS FLOW
55 KEY SAFETY SYSTEMS

5.  The feed gas for this Section is the
associated Natural gas coming from
the Gas booster Section. Inlet
conditions of the feed gas to this
Section ：
 Feed Natural Gas Flow : 200×104
Sm3
/d （ 71 mmscfd ）
 Inlet Pressure of Feed Gas Filter:
4.0 MPag
 Inlet Temperature of Feed Gas
Filter: 45℃
Inlet Natural gas condition &Inlet Natural gas condition &
CompositionsCompositions
Feed Natural Gas
Composition
s Content(mol%)
N2 0.492
C1 58.864
C2 15.086
C3 10.247
i-C4 1.512
n-C4 3.611
i-C5 0.765
n-C5 0.759
C6 0.367
C7 0.072
C8 0.008
CO2 5.105
H2S 2.131
H2O 0.262
TOTAL 100

6. Sweet Natural Gas QualitySweet Natural Gas Quality
IndicatorsIndicators
 H2S （ V
% ）≤ 7.5ppm
 CO2 （ V% ）≤ 2.5%
Sweet Natural Gas
Compositions Content(mol%)
N2
0.521
C1
62.203
C2
16.687
C3
10.825
i-C4
1.598
n-C4
3.814
i-C5
0.809
n-C5
0.802
C6
0.388
C7
0.076
C8
0.008
CO2 1.875
H2S ≤7.5ppm
H2O 0.394
TOTAL 100

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CONDITION OF ROW MATERIALS AND PRODUCTS
Process method and characteristics
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55 KEY SAFETY SYSTEMS

8. Process method and characteristicsProcess method and characteristics
 Due to the feed gas into the Sulfur Removal
Section featuring no organic sulfur , higher
H2S( 2.13%mol) and higher CO2 content
(5.1%mol) . MDEA(Methyl diethanolamine ,
CH3N(C2H4OH)2, 45%,v) is maily choosed as a
desulfurization solvent for its good selectivity
and widespread used at present.

9.  The chemical reactions of MDEA solution during
desulfurization is as follow:
 Main reaction: H2S+R2R N←→Rˊ 2R NHˊ +
+HS-
 The chemical reactions of MDEA solution during
regeneration is as follow:
 Main reaction: R2R NHˊ +
+HS-
←→ H2S+R2R Nˊ
Process method and characteristicsProcess method and characteristics

10. Process method and characteristicsProcess method and characteristics
The process adopted by this Section process
following features :
 The amine absorber has three feed ports(at
Layer 18, 20 and 24) for the lean solution , which
can make the operation fully flexible when the
quality of the feed gas varies.
 The emergency shutdown interlock system is
provided for this Section to ensure safe
shutdown when abnormal situations occur.

11. Process method and characteristicsProcess method and characteristics
 In this Section, oil-skimming devices are
installed in the rich amine flash vessel and relux
vessel at the top of the regenerator Tower in
order to prevent the solution from foaming.

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CONDITION OF ROW MATERIALS AND PRODUCTS
Process method and characteristics
INTRODUCTION
PROCESS FLOW
55 KEY SAFETY SYSTEMS

13. ·
V-621104
0.5KPa,
88℃
·
T-621103
0.25MPa, 121℃
E-621102
P-621103 A-621102
V-621103
0.07MPa,
50℃
P-621102
E-621101
A-621101P-621101
V-621102
0.35MPa,
67℃
V-621101
3.8MPa, 56℃
FIL-621101
4.0MPa, 45℃
T-621101
3.9MPa, 67℃
V-621106
ATM, 45℃
P-621106 FIL-621103
0.55MPa,
65℃
ACID GAS TO SULFUR
RECOVERY
STEAM
CONDENSER
FIL-621102
0.5MPa,
50℃
NATURAL
GAS FROM
GAS
BOOSTER
SECTION
SWWET
GAS
FRESH AMINE
AMINE DRAIN
RICH AMINEFEED
GAS/ACID GAS
LEAN
AMINE
GAS TO
FLARE
HC TO GAS
BOOSTER
PROCESS FLOWPROCESS FLOW
＜ 45℃

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CONDITION OF ROW MATERIALS AND PRODUCTS
Process method and characteristics
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PROCESS FLOW
55 KEY SAFETY SYSTEMS

15. KEY SAFETY SYSTEMSKEY SAFETY SYSTEMS
 Set up the necessary safety valve in order to
prevent pressure vessel and pipeline from
explosion due to operation failures, power
failure, water supply failure and fire etc, which
may cause the internal gas pressure to exceed
the design pressure.

16.  Set up interlock shutdown and alarm system in
this section to ensure the safety of equipment
and operators.
 Set up level control, flow control, pressure
control and temperature control valve in this
section.
KEY SAFETY SYSTEMSKEY SAFETY SYSTEMS

17.  The multi-point detection alarms for toxic gases
such as H2S combustible gas are installed to
ensure personal safety in this section.
 Purging, displacement start-up lines with inert
gases and semi-stationary fire hydrants are
provided to ensure the safety of start-up,
shutdown and normal production of this section.
KEY SAFETY SYSTEMSKEY SAFETY SYSTEMS