Slide 1
IV B. Tech. I Sem Petrochemical Engineering
LNG: Processes, Transportation & StorageUniversity College
of Engineering (A) KakinadaDept. of Petroleum Engineering &
Petrochemical EngineeringFPSO - LNG PROCESSESJawaharlal Nehru
Technological University KakinadaProf. K. V. RaoProgramme
DirectorPetroleum CoursesJNTUKLNG PROCESSES
Figure 1: LNG plant block scheme C2THE BASIC SINGLE FLOW LNG
PROCESS COMPRISESA plate-fin heat exchanger set in a cold box,
where the NG gas is cooled-down to LNG temperatures by a two stage
single MR (Mixed Refrigerant) cycle
A separation vessel, where the MR is separated in a liquid
fraction, which provides the cold temperature after expansion in a
J-T (Joule-Thompson) valve for the NG precooling and
liquefaction.
The gas from the separator provides the LNG subcooling
temperature after J-T expansion at the bottom of the heat
exchanger.
The cycle gas streams leaving the heat exchanger are
recompressed in the two stage turbo compressor.
The compressed cycle gas is cooled and partly condensed against
air or water.3
Figure 2 : The basic single flow LNG process4THE ADVANCED SINGLE
FLOW LNG PROCESS COMPRISESA SWHE (Spiral-Wound Heat Exchanger)
where the natural gas is precooled, liquefied and subcooled against
various streams of a single mixed refrigerant cycle.
A medium pressure refrigerant separator, from where the liquid
is used to provide the precooling temperature after J-T
(Joule-Thompson) expansion to the lower section of the SWHE.
A high pressure refrigerant separator, from where the gas is
cooled and partially condensed in the lower section of the
SWHE.
A lower temperature refrigerant separator, from where the liquid
is used to provide the natural gas liquefaction temperature after
J-T expansion. The gaseous refrigerant stream from this separator
is used to provide the subcooling temperature after J-T expansion
in the upper section of the SWHE
The combined refrigerant cycle stream from the bottom of the
SWHE is compressed in a two stage compressor with inter and
aftercooling against air or water.5
Figure 3: The advanced single flow LNG process6MFC (MIXED FLUID
CASCADE) PROCESSThe MFC LNG process excels by a high efficiency
respectively low shaft power consumption of the three mixed
refrigerant cycle compressors. The process comprises:PFHEs
(Plate-Fin Heat Exchangers) for the natural gas precooling
SWHEs (Spiral-Wound Heat Exchangers) for the natural gas
liquefaction and LNG subcooling
Three separate mixed refrigerant cycles, each with different
compositions, which result in minimum compressor shaft power
requirement
Three cold suction turbo compressors with inter and
ftercooling
Up to 8 mtpa LNG can be produced in a one train unit oncerning
heat exchangers and compressors.
Up to 10 mtpa LNG can be produced in a one train unit concerning
the heat exchangers, however, with parallel compressors.7
Figure 4: MFC (Mixed Fluid Cascade) process8COIL-WOUND HEAT
EXCHANGERThe practically unrestricted range of utilisable materials
allow coil-wound heat exchangers to be used for a wide range of
applications in cold, but also warm applications. The coil-wound
heat exchanger is the core equipment in large base load LNG plants
applying mixed refrigerant cycles for natural gas cooling and
liquefaction.
Benefits
Providing a large heating surface per shell Tolerant against
thermal shocks due to its robustness
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Figure 5: Manufacturing of coil-wound heat exchanger10
The coil-wound heat exchanger is the core equipment in large
base load LNG plants applying mixed refrigerant cycles for natural
gas cooling and liquefaction.11PLATE-FIN HEAT EXCHANGERThe vacuum
brazed aluminium plate-fin heat exchangers are key components in
many cryogenic process plants. They are the preferred heat
exchangers in small LNG plants.BENEFITSCompactness, which saves
installation space and cost
Many process streams can be treated in only one unit, thus
avoiding expensive interconnecting piping of different units
Low equipment weight 12
Assembly of aluminium plate-fin heat exchangers13
Scheme of an aluminium plate-fin heat exchangerThe vacuum brazed
aluminium plate-fin heat exchangers are key components in many
cryogenic process plants. They are the preferred heat exchangers in
small LNG plants.14UNIVERSITY OF PETROLEUM & ENERGY STUDIES,
Thank You15