LNG:
•LNG is natural gas cooled to -161o Centigrade, the temperature at which its main
component, methane, liquefies.
•Its volume is reduced to around one six-hundredth of its volume as a gas
•It is stored and transported at atmospheric pressure as a boiling liquid
•It is an odorless, colorless liquid .
Components of LNG
Pressure : 1 Bar
Components of LNG
Natural
Gas Treated and Cooled to : -161
OC
Pressure : 1 Bar
Volume
reduction : 1 : 600
Composition
( Range) low high
Methane C1 80 99%
Ethane C2 1 17%
Propane C3 .1 5%
Butane C4 .1 2%
C5 + <1%
Nitrogen N2 0 1%
Heating
Value : 1000
- 1160 Btu/scf
Density : 0.45
- 0.47 g/cc
Block diagram of LNG process:
Key Process Units
Block diagram of LNG process:
Key Process Units
SInlet Facilities (onshore):
Reception and separation of offshore feed wet gas into gas, condensate, and water.
SAcid Gas Removal (AGR):
Remove acid gas (H2S and CO2) by amine system ( Ucarsol ).
SSulphur Recovery Unit (SRU) / Acid Gas Injection (AGI):
Recover H2S and Mercaptans (RSH) into pure liquid Sulphur (Claus process), or inject the acid gas into onshore acid gas injection wells.
SGas Treating (Dehydration & SELEXOL):
Remove mainly water, Mercaptans (RSH) and Sulphur compounds from saturated gas
SMercury Removal:
Remove mercury (Hg) form the dry gas
.
SNGL Recovery:
Recover NGL (mainly C2+ or C3+).
SFractionation:
Recover Ethane (C2), Propane (C3), Butane
(C4), also iso-Pentane (i-C5) and plant condensate (n-C5+)
SRefrigeration:
Use Propane and Mixed Refrigerant (MR) for gas pre-cooling and liquefaction.
SLiquefaction:
Liquefy the dry sweet gas by Main Cryogenic Heat Exchanger (using C3-MR).
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