Unit-10 “ NGL Extraction “ Objective
• Unit 10 “ NGL Extraction Unit “ Objective :
To Separate NGL from Dry feed gas in order to perform further
processing in Fractionation unit to get the final products
• Propane
• LPG
• DNG
Sales Gas
( C1, C2)
Dry Feed Gas
( C1, C2 , C3 , C4 , C5+)
Unit 10
NGL
(C3 , C4 , C5+)
Selected process for NGL Extraction
• ORTLOFF IOR “Improved Overhead Recycle Process” was
selected for the NGL Extraction Section, to guarantee optimum
recovery (Propane in excess of 98% and 100% of C4 plus) of
NGL Liquids, in addition to the future, simple process conversion
to “Gas Sub-Cooled Process”, to recover not less than 73% of
Ethane.
ORTLOFF IOR Process
• Ortloff’s IOR process is a two
column design, incorporating an
Absorber and a Demethanizer.
The
Demethanizer
overhead
vapor is cooled and partially
condensed, with the resulting
liquids providing reflux for both
columns. The cooling necessary
to
partially
condense
the
Demethanizer overhead vapor is
provided by Absorber overhead
vapors.
The
two
columns
typically operate at about the
same pressure, with pumps
providing the energy required for
the liquids to transfer between
the columns.
ORTLOFF IOR Process
•
The required cooling for the feed
gas is carried out utilizing the cold
residue gas from the top of the
absorber
using
the
gas/gas
exchanger. Also utilizing the cold
liquids from the bottom of the low
temperature separator and the
absorber bottom liquids, finally
using the expander to reach the
final required temperature.
• The core of the process is utilizing
the Demethanizer off gas after
cooling and condensing to provide
reflux to the absorber, where it will
contact, rectify and absorb the
propane plus component from the
expander vapor interring the
absorber.
ORTLOFF IOR Process Guarantee
• The plant is guaranteed to recover minimum of 96.5% of
the available propane and essentially 100% of the
butanes and heavier components when processing an
inlet gas rate of 1350 MMSCFD of the design composition
feed gas.
• The IOR process will produce a deethanized NGL product
meeting the desired product Specification, and about 1335
MMSCFD of sales gas product. The plant is also designed for
easy conversion to the Gas Sub-cooled Process (GSP) for
recovery of ethane product in the future.
NGL Extraction Process Description
• De-mercurized gas stream will split & pre-cool versus warming
residue gas stream in the G/G PFHE (Unit 10-E-01) and liquid
bottom streams (expander feed separator & absorber) in the
G/L PFHE (Unit 10-E-02) respectively.
10-E-03
10-E-01
0-50% IN
79 Bar
30 C
FV
FIC
02
-26 C
FY
01C
SDV
10-V-01
FV
Mercury
Removal
FY
02
-76 C
FY
01D
50-100% IN
10-E-02
NGL Extraction Process Description
• Pre-cooled gas will be flashed into Expander Feed Separator
(Unit 10-V-01), to separate any condensed liquids , These
liquids in the source of the cooling duty for feed gas in G/L (10E-02) “PASS B”
10-E-03
10-E-01
0-50% IN
79 Bar
30 C
-66 C
-35 C
FV
FIC
02
-26 C
FY
01C
SDV
10-V-01
LIC
15
Mercury
Removal
SDV
FY
01D
-55 C
FV
LV
FY
02
-76 C
Liquids to pass B
50-100% IN
10-E-02
NGL Extraction Process Description
• Gas will then expand through Turbo-Expanders (Unit 10 U01A/B), with further cooling to -74 C, Two J.T. valves are
provided in parallel to Expanders, to maintain plant in operation
during Expanders trip & facilitate plant start-up.
10-E-03
10-E-01
0-50% IN
FY
01C
79 Bar
30 C
-26 C
-66 C
-35 C
FV
FIC
02
SDV
SDV
10-V-01
LIC
15
Mercury
Removal
Expanders
Fault
Trip
10-U-01A/B
Expanders
Guide
Vanes
-74 C
PV-12A
HIC
02/04
PY
12B
PIC
12A
SP < 5 psi
LV
PV-12B
FY
01D
-55 C
FV
FY
02
SDV
-76 C
50-100% IN
10-E-02
PIC
12B
NGL Extraction Process Description
• The Demethanizer (Unit 10-C-01) overhead vapor will cool
versus warming residue gas stream in the G/G PFHE (Unit 10E-03), and will be flashed to Absorber (Unit 10-C-02) top where
accumulated condensed liquids are placed in chimney tray
36 Bar
-79 C
SDV
10-E-03
36 Bar
-34 C
-74 C
TV
10-E-01
SDV
0-50% IN
FY
01C
79 Bar
30 C
-26 C
-66 C
-35 C
FV
FIC
02
TIC
15
SDV
10-V-01
LIC
15
Mercury
Removal
36 Bar
27 C
SDV
Expanders
Fault
Trip
10-U-01A/B
Expanders
Guide
Vanes
-74 C
PV-12A
HIC
02/04
PY
12B
PIC
12A
SP < 5 psi
LV
PV-12B
FY
01D
-55 C
FV
FY
02
SDV
-76 C
50-100% IN
10-E-02
PIC
12B
10-C-02
10-C-02
10-C-01
NGL Extraction Process Description
• Expanded liquids will feed the absorber tower, accumulated
condensed liquids will be re-circulated by Reflux Pumps (Unit
10-P-01A/B) to reflux both Absorber & Demethanizer Columns,
to minimize propane & heavier component vaporizing out of
columns.
SDV
10-E-03
36 Bar
-34 C
36 Bar
-79 C
-74 C
-74 C
TV
10-E-01
SDV
0-50% IN
FY
01C
79 Bar
30 C
-26 C
-66 C
-35 C
FV
FIC
02
TIC
15
SDV
10-V-01
LIC
15
Mercury
Removal
Expanders
Fault
Trip
-74 C
10-U-01A/B
Expanders
Guide
Vanes
-74 C
PV-12A
HIC
02/04
PY
12B
PIC
12A
SP < 5 psi
LV
-55 C
FY
01D
SDV
PV-12B
FV
FY
02
-76 C
50-100% IN
10-E-02
10-P-01A/B
36 Bar
27 C
SDV
PIC
12B
10-C-02
10-C-02
10-C-01
NGL Extraction Process Description
• All generated power from Both Expanders 10-U-01 A/B are
utilized to compress residue gas through the Expander
Compressors (Unit 10-K-01A/B) to Residue Gas Compressors.
SDV
10-E-03
36 Bar
-34 C
36 Bar
-79 C
-74 C
-74 C
TV
10-E-01
SDV
0-50% IN
FY
01C
79 Bar
30 C
-26 C
-66 C
-35 C
FV
FIC
02
TIC
15
SDV
10-V-01
LIC
15
Mercury
Removal
Expanders
Fault
Trip
-74 C
10-U-01A/B
10-K-01A/B
Expanders
Guide
Vanes
-74 C
PV-12A
HIC
02/04
PY
12B
PIC
12A
SP < 5 psi
LV
-55 C
FY
01D
SDV
PV-12B
FV
FY
02
10-P-01A/B
36 Bar
27 C
SDV
10-C-02
10-C-02
10-C-01
PIC
12B
-76 C
50-100% IN
10-E-02
Residue Gas Compressors
NGL Extraction Process Description
• Expander Feed Separator & Absorber liquids will provide the
duty of inlet gas pre cooling in G/L PFHE “Pass B and Pass C
respectively “ , after being partially vaporized downstream the
G/L PFHE, both streams will feed the Demethanizer.
SDV
10-E-03
36 Bar
-34 C
36 Bar
-79 C
-74 C
-74 C
TV
10-E-01
SDV
0-50% IN
FY
01C
79 Bar
30 C
-35 C
-26 C
-66 C
FV
FIC
02
TIC
15
SDV
LIC
15
Mercury
Removal
10-V-01
Expanders
Fault
Trip
10-P-01A/B
36 Bar
27 C
SDV
-36 C
-74 C
10-K-01A/B
10-U-01A/B
Expanders
Guide
Vanes
29.5 C
-74 C
PV-12A
HIC
02/04
PIC
12A
PY
12B
10-C-02
10-C-02
SP < 5 psi
FY
02
-55 C
FV
LV
-76 C
PIC
12B
FV-18
FY
01D
TV
10-E-02
SDV
LV
FIC
18
50-100% IN
10-C-01
SDV
PV-12B
66-100% IN
TY
12B
LIC
08
-76 C
New By passes “ G/L
cold box passes
10-P-02A/Bmodifications “
0-66% IN
TIC
12
TY
12B
Residue Gas Compressors
NGL Extraction Process Description
• Demethanizer Re-boiler (10-E-04) generate sufficient hot
vapors to strip ethane and lighter components from the liquid
flowing down the Demethanizer Column. to maintain C2/C3 Liq.
Vol. % ratio of NGL liquids stream not to exceed 1.0%.
SDV
10-E-03
36 Bar
-34 C
36 Bar
-79 C
-74 C
-74 C
TV
10-E-01
SDV
0-50% IN
FY
01C
79 Bar
30 C
-35 C
-26 C
-66 C
FV
FIC
02
TIC
15
SDV
LIC
15
Mercury
Removal
10-V-01
Expanders
Fault
Trip
10-P-01A/B
36 Bar
27 C
SDV
-36 C
-74 C
10-K-01A/B
10-U-01A/B
Expanders
Guide
Vanes
29.5 C
-74 C
PV-12A
HIC
02/04
10-C-02
10-C-02
SP < 5 psi
FY
02
-55 C
FV
LV
-76 C
PIC
12B
FV-18
FY
01D
TV
10-E-02
SDV
10-C-01
66-100% IN
TY
12B
Hot Oil
10-E-04
LIC
04
24 Bar
150 C
FV
92.7 C
10-P-02A/B
0-66% IN
TIC
12
-76 C
LV
FIC
18
50-100% IN
LIC
08
SDV
PV-12B
24 Bar
200 C
SDV
PIC
12A
PY
12B
AIC
01
TIC
27
SDV
C2/C3
FIC
06
LV
TY
12B
Fractionation
Residue Gas Compressors
Key Equipment
 BRAZED ALUMINIUM PLATE-FIN HEAT EXCHANGER “ Cold Boxes “
1. 10-E-01/03
Gas/Gas Cold Box.
2. 10-E-02
Gas/Liquid Cold Box.
 10-X-01 A/B
Turbo expanders and compressor.
 10-P-01/02 A/B
CPC Chimney and Absorber bottom pumps
Brazed Aluminum Plate-Fin Heat Exchanger
Brazed Aluminum Plate-Fin Heat Exchanger
 Chart’s Brazed Aluminum Heat Exchangers (BAHX) are at the heart
of cryogenic gas processing applications worldwide and offer vastly
superior heat transfer performance versus their shell and tube
counterparts.
 A Brazed Aluminum Heat Exchanger is typically 20% the size of a
shell and tube exchanger of comparable performance. Furthermore,
the alternating plate fin construction offers multiple stream
capability and simplifies a series of shell and tube units to a single
compact structure.
Brazed Aluminum Plate-Fin Heat Exchanger
 Each Brazed Aluminum Heat
Exchanger consists of alternating
layers
of
corrugated
fins
(secondary heat transfer surface)
separated by flat plates (primary
heat transfer surface). Apart
from the fluid entry and exit
ports the edges are sealed with
bars and the unit is brazed in a
vacuum furnace. Construction is
completed by attaching and
welding the headers and nozzles
over the entry and exit ports and
the finished unit is rigorously
tested for mechanical strength
and leaks prior to despatch.
10-E-01
Gas/Gas Cold Box
Hot Side
Cold Side
Design Temp. Max/Min °C
50/-196
50/-196
Design Pressure Max. Barg
79
36
No of layers per Core
65
66
Design Data
Total No. Of Cores
3
Operating Parameters
Temp in °C
30
-56
Temp Out °C
-46
23
Pressure In Barg
59
28.5
Pressure Drop across
Layers
0.8
0.65
10-E-03
Gas/Gas Cold Box
Hot Side
Cold Side
Design Temp. Max/Min °C
50/-196
50/-196
Design Pressure Max. Barg
79
36
No of layers per Core
63
64
Design Data
Total No. Of Cores
3
Operating Parameters
Temp in °C
-46
-84
Temp Out °C
-82
-16
Pressure In Barg
30.6
29.7
Pressure Drop across
Layers
0.6
1.3
10-FT-01/10FT-02 Ratio =
15-20 %
Cold Side
Max T = 50 Deg C , Max P = 36
Barg
Hot Side
Max T = 50 Deg C , Max P = 79
Barg
Cold Side
Max T = 50 Deg C , Max P = 36
Barg
Hot Side
Max T = 50 Deg C , Max P = 79
Barg
Gas /Gas Cold Box Brief History
 2004/2005:
• High deferential pressure across Gas/Gas exchanger has been
recorded , The inlet strainers (For the hot paths 24” and 36” ) were
found collapsed and were re-fabricated again.
• Many rupture disk was executed in both Gas/Gas and Gas/Liquid
exchangers
• Chemical cleaning with Toluene has been implemented also to
reduce the high ΔP.
 2006:
• on 16 oct. 2006 , external gas leakage combined with insulation
powder “Perlite” was observed from the housing of gas/gas
exchanger 10-E-01/03.
• IN 2006 this failed cold box was replaced in a plant shutdown by a
new one and went for a CM to repair the crack.
Gas /Gas Cold Box Brief History
 2006 Failure resulted in the following modifications :
• Adding nitrogen source equipped with flow transmitter and regulator
to the cold box casing , also adding gas detectors to protect
accumulation of hydrocarbon in casing in case of leakage.
• Adding internal temperature transmitters and alarms application in
order to monitor temperature differences between adjacent streams
and rate of temperature change which was necessary to control the
thermal stresses and protect cold box integrity.
• 2014:
• During plant start-up At 10:56 AM, an external gas leakage
observed from the breathing hatch of Gas/Gas heat exchanger 10-E01/03 combined with Perlite release .
• On March, 2014 shutdown, performed swapping for the failed
gas/gas exchanger.
• The last failure causes are still under investigation .
10-E-02
Gas/Liquid Cold Box
Hot Side
Cold Side (B/C)
Design Temp. Max/Min °C
50/-196
50/-196
Design Pressure Max. Barg
79
36
No of layers per Core
104
96
Design Data
Total No. Of Cores
1
Operating Parameters
Temp in °C
30
-82 for B / -84 for C
Temp Out °C
-71
24 for B / -52 for C
Pressure In Barg
59
32 Bar
Pressure Drop across
Layers
0.17
0.27 for B /0.73 for C
Hot Side
Max T = 50 Deg C , Max P = 79
Barg
Cold Side B
Max T = 50 Deg C , Max P = 36
Barg
Cold Side C
Max T = 50 Deg C , Max P = 36 Barg
Min T = - 90 “ ENNPI SPECS”
Gas /Liquid Cold Box Brief History
 2004/2005:
• Since the plant start up a high pressure drop issue through pass “C”
was raised and communicated with the vendor (CHART) without
serious progress
• 2008:
• an external gas leakage was detected from the housing of 10-E-02
as a result of hair crack in a plug welding of pass “B” internal vessel.
Investigation showed that was due to high thermal stress during
unplanned SD / start up .
• Accordingly the G/L cold box was replaced by a new one on the end
of October 2008.
• Although a new gas liquid cold box was installed, the pressure drop
through pass “C” increased dramatically same as happened with the
old one.
Gas /Liquid Cold Box Brief History
• Quantity of Liquid collected in the expander feed sep. and
absorber tower was dropped dramatically as a result of:
• El-Gamil feed gas became leaner since July 2010 as a result of
opened a new TUNA wells circa ( 210 MMSCFD )
• Upgrade plant capacity from 1100 to 1272 MMSCFD through utilizing
more gas from Hap’y (leaner composition) affected mix feed gas .
• The design case for rich gas and lean gas are 2.4 % and 1.9 %
respectively , while the current is 1.62% as more gas from Hap’y
was utilized in addition to El-Gamil became leaner .
• Accordingly the liquid collected in expander feed separator became
lower which affected the liquid flow rate through pass “B” and
consequently the Temperature difference between adjacent streams.
Gas /Liquid Cold Box Brief History
• 2011 : On 2nd of May 2011, Operations reported a leak from the
top of Cold box gas liquid exchanger through detecting alarm from
gas detection on the top of the cold box, the operation was
continued after performing a contingency plan and risk assessment
till the planned shutdown in June 2011 where it was replaced by the
repaired gas liquid cold box.
• Investigation shows that during unplanned shut down excessive
thermal stresses occur to different paths specially the liquid paths B
and C both the rate of change in temperature and the temperature
difference between two adjacent streams are exceeding the
recommended range. It was recorded that in 30th of April one day
before discovering the leakage a thermal stresses was applied to the
liquid core see in the adjacent part to the defected part of B .
Gas /Liquid Passes Modification
• Before The Modifications :
• The gas/liquid heat exchanger had very wide temperature difference
between hot and cold streams at the midpoint of the exchanger. the
feed gas is cooled down at G/L exchanger by two cold streams, the
flashed liquids from expander feed separator” pass B” and then the
liquid stream from absorber bottom pump. The hot stream at
midpoint reaches 13C’ while the temp of flashed liquids from
expander feed separator is -60 C’ and the temp of the absorber
bottom liquids at the midpoint is -20 C’ leading to an average cold
side metal temp of -40 C’ and the temp difference between hot and
cold adjacent layers is 53 C’ which is higher than the max allowable
temp difference recommended by manufacturer of 28 C’ to avoid
risk of thermal stresses.
Gas /Liquid Passes Modification
• Before The Modifications :
Lean Gas , without LPG reinjection
Feed gas in ,
pass A
20C’
8.5 MMSCFH
30 C’
To Demethanizer
Diff = 10 C’
13 C’
Avg= -40 C’
Diff = 53 C’
-20C’
Pass B IN
-60 C’, 27.3 TON/H
To Demethanizer
Diff = 23C’
Feed gas OUT
, pass A, -57 C’
Pass C IN
-80C’, 156 TON/H
Gas /Liquid Passes Modification
• After Studying the proposals for required modifications to
overcome this issue , the chosen proposal was :
• Installing a pipeline connecting inlet of pass C to inlet of pass B of
G/L cold box with flow control valve controlling the split liquid flow.
• Part of the liq. stream from absorber bottom pump is mixed with the
expander feed separator bottom liquid to enhance pass B heat duty ,
adjusts the Demethanizer
temperature profile in the stripping
section as well as reducing load on rectifying section accordingly
propane % recovery improved to above 99%.
• A bypass line installed on pass B with SDV opened during process
S/D to protect the cold box from thermal stresses during transient
periods of S/D and start up.
Gas /Liquid Passes Modification
• On March, 2014 shutdown, performed swapping for 10-E-02 and
executed the project of G/L by-pass modification (PMR 25/2013)
by constructing new 6” line taking slip stream from absorber bottom
to be mixed with expander feed separator liquids feeding pass “B” to
increase flow rate across the pass, increasing the duty across the
pass, and lowering the temperature difference between two adjacent
layers at the middle of 10-E-02 to be lower than 30°C as per chart
recommendations to prevent thermal stresses.
• 6” line is equipped with flow control valve 10-FV-18 and two
isolation manual ball valves and 4” bypass gate valve.
• Another line 12” was constructed to by-pass pass “B” in shutdown
cases to prevent thermal stresses during those cases.
• 12” line is equipped with 12” on-off valve 10-SDV-17 (normally
closed) and two isolation ball 12” manual valves.
Gas /Liquid Passes Modification
• After The Modifications :
Feed gas in ,
pass A
8.5 MMSCFH
27 C’
20 C’
To demethanizer
Diff =16C’
SDV
Liq from
bottom of
exp feed
sep
pass B IN
-80 C’, 65TON/H
-54 C’
Diff =26 C’
-75C’, 40 TON/H
-58 C’
To demethanizer
TV-12
Diff =23C’
Feed gas OUT ,
pass A, -73C’
pass C IN
-80C’, 103.3TON/H
-80C’,
0 TON/H
Flow
control
valve
-80C’, 65 TON/H
Liq from
absorber
bottom
pump
CPC Pumps
• CPC Chimney and Absorber bottom pumps (10-P-01A/B,10-P-02 A/B) are
centrifugal pumps , they comply with API-610 ISO standard , with a type
code of (OH4) , this type characteristics are :
1- Overhung pump.
2- Vertical pump.
3- Rigidly Coupled (Pump shaft is rigidly coupled to driver shaft ).
4- Single stage .
CPC Pumps
CPC Pumps
CPC Pumps
10-P-01 A/B
10-P-02 A/B
-49
-49
36/27.2
36/26.9
Differential Pressure Bar
2.8
3.1
NPSHA m
6
3
190000
190000
Suction Temp Out °C
-84
-84
Suction Pressure Barg
30
30
Design Data
Liquid Temp. Max °C
Suction Pressure
Max/Rated. Barg
Operating Parameters
Average Flow Rate Kg / hr
Turbo-Expanders
•
Turboexpander : also referred to as a turbo-expander or an expansion
turbine, is a centrifugal or axial flow turbine through which a
high pressure gas is expanded to produce work that is often used to drive a
compressor.
• Because work is extracted from the expanding high pressure gas, the
expansion
is
approximated
by
an
isentropic
process
(i.e.,
a
constant entropy process) and the low pressure exhaust gas from the turbine
is at a very low temperature, depending upon the operating pressure and gas
properties.
• Turboexpanders are very widely used as sources of refrigeration in industrial
processes such as the extraction of ethane and natural gas liquids (NGLs)
from natural gas
Turbo-Expanders
•
Turboexpander : also referred to as a turbo-expander or an expansion
turbine, is a centrifugal or axial flow turbine through which a
high pressure gas is expanded to produce work that is often used to drive a
compressor.
• Because work is extracted from the expanding high pressure gas, the
expansion
is
approximated
by
an
isentropic
process
(i.e.,
a
constant entropy process) and the low pressure exhaust gas from the turbine
is at a very low temperature, depending upon the operating pressure and gas
properties.
• Turboexpanders are very widely used as sources of refrigeration in industrial
processes such as the extraction of ethane and natural gas liquids (NGLs)
from natural gas
Turbo-Expanders
Schematic diagram of a turbo- expander driving a compressor.
Turbo-Expanders 10-U-01 A/B
• Turboexpander system consists of two frame 5.0 Mafi-Trench compressor
loaded turboexpanders equipped with S2M magnetic bearings. Each is
mounted on a rigid steel skid base and supported by a control and seal gas
system. System components are arranged for ease of operation and
maintenance.
• The expander-compressor consists of three basic sections:
1. The expander section with inlet and discharge flanges.
2. The rotating assembly or center section.
3. The compressor section with inlet and discharge flanges.
Turbo-Expanders 10-U-01 A/B
Expander Rotating
Section assembly
Compressor
section
Turbo-Expanders 10-U-01 A/B Description
1.Inlet guide vanes
The inlet guide vanes regulate mass flow to the expander. The mechanism is
designed to withstand full expander inlet pressure and can be adjusted to vary
flow over the range of approximately 0 to approximately 125% of the design
mass flow rate. An air-loaded actuator with positioner controls the guide vane
opening. A control signal causes the actuator to adjust the inlet guide vane
opening to compensate for changes in process conditions.
Turbo-Expanders 10-U-01 A/B Description
Turbo-Expanders 10-U-01 A/B Description
2. EXPANDER AND COMPRESSOR WHEELS
• Mafi-Trench Expander and Compressor wheels are machined from solid plate
or bar for maximum strength and integrity . The radial inflow expander wheel
with our variable inlet guide vane design produces high efficiencies
• over a broad operating range.
3. Shaft
• Wheels are attached to the shaft on a special tapered profile.
Turbo-Expanders 10-U-01 A/B Description
Turbo-Expanders 10-U-01 A/B Description
4. Shaft Seal
• Shaft seals are labyrinth type to minimize seal gas leakage. The design
incorporates a steel rotating labyrinth running adjacent to a glass fiber
reinforced seal cartridge over a broad operating range.
5. Active Magnetic Bearing
• An active magnetic bearing is an electromagnetic device that maintains the
relative position of a rotating assembly (rotor) with respect to a stationary
part (stator). The electromagnetic forces implemented for this are controlled
by an electronic control cabinet.
• An active magnetic bearing is, therefore, made up of two distinct parts, the
bearing itself and the electronic control system.
Turbo-Expanders 10-U-01 A/B Description
Turbo-Expanders 10-U-01 A/B Description
Turbo- expander Magnetic bearing and Magnetic beraing control system
Turbo-Expanders 10-U-01 A/B Description
6. AUTOMATIC THRUST EQUALIZER SYSTEM
(ATE)
• Use active, automatic thrust balancing methods to keep normal thrust
bearing differential loads near Zero .
• Current signals from the magnetic thrust bearing system are used to control
a pressure control valve which adjusts the pressure behind the expander
wheel to maintain balanced thrust loads.
Turbo-Expanders 10-U-01 A/B Description
Turbo-Expanders 10-U-01 A/B Description
7. Seal Gas System
• The buffer gas system filters and regulates gas flow to the labyrinth seals
inside each turbo-expander. These seals are located between each impeller
and its associated auxiliary bearing.
• The buffer gas system performs three important functions:
(1) Ensures that adequate buffer gas is available to carry away heat generated
by the magnetic bearings and by rotor.
(2) Keep cold, unclean process gas away from the auxiliary bearings.
(3) Maintain a positive pressure in the bearing housing (to prevent entrance of
air).
• The seal gas pressure is controlled by primary and secondary regulating
valve that automatically maintains a constant seal gas pressure across the
seals
Turbo-Expanders 10-U-01 A/B Description
Labyrinth seal showing seal gas flow path
Turbo-Expanders 10-U-01 A/B
Expander
Compressor
Suction Pressure Barg
64.7
23.7
Discharge Pressure. Barg
26
33.1
Suction Temperature °C
-35
26.4
Discharge Temperature °C
-75.2
54
Design Data
Turbo-Expanders 10-U-01 A/B
• The following slides show the alarm limits for the
Expander –compressor package , to operate the
equipment safely
Seal gas DP
2.4 Barg “ low alarm as
per MAFI-Trench CONTROL
SETPOINT
1.8 is the trip point
Seal gas filter DP
1.7 barg low alarm
as per MAFITrench CONTROL
SETPOINT
Bearing House Pressure
14 barg low alarm as per
MAFI-Trench CONTROL
SETPOINT
Boundary Housing Differential
Pressure
0.2 mbar High alarm as per MAFITrench CONTROL SETPOINT
Expander Bearing
Temp.
10 Deg C low alarm
as per MAFI-Trench
CONTROL SETPOINT
Compressor Bearing Temp.
99 Deg C High alarm as per
MAFI-Trench CONTROL
SETPOINT
Speed Transmitters
12100 RPM high
alarm as per MAFITrench CONTROL
SETPOINT
Position :90 µm High alarm
Unbalance : 36 µm High alarm
as per MAFI-Trench CONTROL
SETPOINT
110 Deg
C High
alarm
as per
MAFITrench
CONTROL
SETPOIN
T
150 µm High alarm as
per MAFI-Trench
CONTROL SETPOINT
Position :90 µm High alarm
Unbalance : 36 µm High alarm
as per MAFI-Trench CONTROL
SETPOINT
Position :90 µm High alarm
Unbalance : 36 µm High alarm
as per MAFI-Trench CONTROL
SETPOINT
Position :90 µm High alarm
Unbalance : 36 µm High alarm
as per MAFI-Trench CONTROL
SETPOINT
+/- 200 trip
as per MAFITrench
CONTROL
SETPOINT
65 Deg C High
alarm
as per MAFITrench CONTROL
SETPOINT
Absorber and De-methanizer
Absorber
10-C-02
De-methanizer
10-C-01
36
36
-110/145
-85/145
Cold Conservation
Cold / Heat
Conservation
Diameter m
5.344
4.570
Length m
18.04
8.1 Bed Height
29.7
No. of Trays
6 theoretical stages
30
Trays Type
N.A
Valve Type
Packing Type
FLIXIMIX 700 SS
N.A
Design Data
Design Pressure Barg
Design Temperature Min/ Max °C
Insulation
De-Methanizer Reboiler
Shell Side
Tube Side
36
24
-100/150
5/300
Design Data
Design Pressure Barg
Design Temperature Min/ Max °C
No. of tube
Type
Duty MMcal
1634
Kittle reboiler TEMA class R
22
Applied Modification in Unit-10
• All of these modifications are implemented according to technical
studies and MOC/PMR procedure in objective to enhance UGDC
facilities availability, and productivity.
10-PSV-36 (Absorber PSV)
Modification:
• Adding a new tail pipe
Objective:
• Decrease tail pipe back pressure and also decrease velocity to be lower than
0.7 MACH limit.
Cold Box Exchangers 10-E-01/03-02
Modification:
• Adding nitrogen source equipped with flow transmitter and regulator to the
cold box casing.
• Adding internal temperature transmitters and alarms application.
• Adding gas detectors.
Objective:
• Protect accumulation of hydrocarbon in casing in case of leakage.
• Monitoring temperature differences between adjacent streams and rate of
temperature change.
• Controlling thermal stresses and protect cold box integrity.
Absorber 10-C-02
Modification:
• Adding 2oo3 10-PSHH-29A/B/C at the top of absorber for U-10 ESD.
Objective:
• To prevent a phenomenon known as “Acoustic failure” which may occur D/S
the absorber relief valves as the relief capability may be insufficient for a
blocked outlet relief scenario.
Absorber Platforms 10-C-02
Modification:
• Repairing the absorber skids as the present were rust-hit and became
unsafe to use.
Objective:
• The company’s eagerness to achieve the most safe work conditions for
workers by performing the repairing process.
Absorber CPC Pumps 10-P-01/02
Modification:
• Bearing lubrication routed from pumps discharge through internal bearing to
the impeller suction instead of drain.
Objective:
• Save hydrocarbon losses.
G/L Cold Box Passes Modifications
Modification:
• Installing a pipeline connecting inlet of pass C to inlet of pass B of G/L cold
box with flow control valve controlling the split liquid flow.
• A bypass line installed on pass B with SDV opened during process S/D to
protect the cold box from thermal stresses during transient periods of S/D
and start up.
Objective:
• Maintained Cold Box integrity as the temperature difference in the mid point
has been reduced to below 28 Deg. C as per CHART recommendations .
Unit 10 Dead Legs
Modification:
• Connecting 7 points of hydrocarbon deal legs in the piping to the closed
drain network , this modification has been implemented in 2014 SD .
Objective:
• Availing a higher performance during plant dry out be directly draining these
dead legs to close drain system, also eliminating the using of hoses for this
purpose which comply with QHSE requirements .
Most important Control Loops in U-10
In the upcoming slides , the most important
control loops inside Unit-10 are simply
described .
1. Inlet gas flow ratio control 10-FFIC-01 PID (10-GD-04040)
• Dry gas from de-mercury removal unit is cooled via two separate flow paths,
one using cool residue gas in the gas/gas exchanger, and the other in a
gas/liquid exchanger utilized a cool liquid from expander feed separator
(pass B), and the bottom liquid from absorber tower (pass C).
• The total plant inlet flow is therefore used as the set point input to a flow
ratio controller. The inlet gas flow to the gas liquids exchanger can therefore
be set at some set ratio of inlet gas flow rate depending on process
conditions.
• Sometimes the ratio will set remotely by the temperature controller 10-TIC12.
• Flow split is manipulated as the primary control within a programmed range
of flow ratios (approximately 10% - 20% of inlet gas to the gas liquids
exchanger).
• In order to maintain the desired ratio under all operating condition, the
output of the flow ratio controller, FFC is split ranged between two valves,
one in the inlet gas line to the GAS/GAS Exchanger and the other to the
GAS/LIQUIDS exchanger.
1. Inlet gas flow ratio control 10-FFIC-01 continued.
• A typical split range could be implemented as follows:
FFC Output
0%
50%
100%
•
FV-A
FV-B
Position
(Gas/Gas)
Position
(Gas/Liquids)
0-50%
Close Limit
Open
Open
50-100%
Open
Open
Close Limit
As can be seen from the table above when the FFC output is at 50% both
valves will be fully open, between 50% and 0% valve FV-A will be moving
from open to closed and between 50% and 100% valve FV-B will be moving
from open to closed.
2. Gas/Liquids Exchanger Temperature Control 10-TIC-12
PID (10-GD-B-04041-1)
• The main objective of the mentioned loop is to adjust heat amount, and
temperature of the liquid feed to the de-methanizer tower coming from
absorber bottom liquid via gas/liquid exchanger pass C.
• In order to satisfy this objective the output of TIC-12 is a split range:
• From 0% to 66% are used to rest the flow ratio controller
10-FFIC-01of
the inlet gas flowing through the gas liquid exchanger, while the output
increase (0%-66%) the ratio setting will decrease, then the amount of gas
flowing to 10-E-02 also decrease until output 66% the gas will be at a
minimum stop.
• From 66% to 100% will start open the bypass valve 10-TV-12 located on by
pass line of 10-E-02 pass C that to decrease inlet temperature to 10-C-01.
2. Gas/Liquids Exchanger Temperature Control 10-TIC-12
Continued
FFC ratio
(inlet gas to 10-E-02)
TV Position
(Pass C bypass)
TC Output
Max. To Min.
0-66%
Close-Open
66-100%
0%
Maximum
Closed
33%
Mid scale
Closed
66%
Minimum
Start to Open
100%
Minimum
Open
As can be seen from table above, 0% output means a maximum flow of
inlet gas to 10-E-02, 33% output is a normal design flow, and 66% is a
minimum stopping flow based upon chart recommendation.
3. Gas/liquid new by-pass Modification control: 10-FIC-18
PID (10-GD-B-04041-1)
• Flow controller 10-FIC-18 control the flow rate of withdrawn split stream
from absorber bottoms to be mixed with flashed liquids from expander feed
separator feeding pass “B” of E-02 to reduce and control the temperature
difference between adjacent streams at the middle of E-02 below 28°C to
avoid thermal stresses.
• Opening the flow control valve 10-FV-18 will increase the flow rate across
pass “B” and with lower temperature allowing higher duty within pass “B”,
reducing feed gas temperature at the middle of pass “A” dramatically,
reducing the temperature of outlet pass “C”, and lowering the temperature
difference between adjacent streams till reaching acceptable difference.
4. Expander Inlet Temperature Control: 10-TIC-15
(PID 10-GD-B-04041-2)
• 10-TIC-15-temperature controller controls the inlet temperature of expander
10-x-01A/B. The output signal is connected to 10-TV-15 valve on a bypass
line of the cold gas from absorber tower 10-C-02 to expander compressor
via de-methanizer overhead condenser, then Gas/Gas heat exchanger 10-E01.
• When the bypass valve is opened, it will reduce the cool residue gas flow
through Gas/Gas exchanger, thereby raising the inlet gas stream out of
Gas/Gas exchanger to maintain the expander inlet temperature not below a
certain temperature depend upon the inlet feed gas composition, because it
is possible under certain operating condition the warm feed to expander can
provide improved recovery.
5. Reflux Flow Ratio Control: 10-FIC-08.
(PID-10-GD-B-04045-1A)
• The reflux flow for both absorber 10-C-02 and de-methanizer 10-C-01 are
controlled by 10-FIC-08 control loop. 10-FIC-08 set value is reset manually
according to process optimization calculation depending on the operating
condition.
• The output signal is connected to 10-FV-08 flow valve on demethanizer
reflux line for constant amount of reflux to 10-C-01 at certain condition;
consequently the remaining reflux will go through the middle section of
absorber.
6. De-methanizer Overhead Accumulator Level
Control 10-LIC-06 (PID 10-GD-B-04045-A1)
• The liquid level of de-methanizer Overhead Accumulator (upper section of
10-C-02) is controlled by 10-LIC-06-control loop. 10-LIC-06 set value is
reset manually according to the amount of liquid condensed from demethanizer overhead gas.
• In case of high liquid level and to avoid liquid carryover from absorber upper
section chimney to the packing middle section of 10-C-02, the output signal
from 10-LIC-06 will open 10-LV-06 level valve on absorber reflux line, to
keep a stable amount of reflux to 10-C-01 at certain condition, that to avoid
disturbance at the de-methanizer tower.
8. Cascade Control of Absorber Bottom Liquids 10-LIC08, & 10-FIC-10 PID (10-GD-B-04045)
• The absorber bottom liquid from 10-C-02 is controlled by 10-FIC-10-cascade
control loop. 10-FIC-10 set value is changed by 10-LIC-08-output signal. 10FV-10-control valve operate to adjust 10-FI-10-flow rate to the set value. In
this control loop, 10-LIC-08 controllers continuously changes 10-FIC-10 set
value with the liquid level fluctuation in 10-C-02-bottom section.
Unit Shut Down
• Level (1) ESD will be activated in one or more of the following ways:
• Manually via dedicated push buttons on the control room ESD panel .
• High high liquid level in the flare KO drums 97-V-01/02/03. .
• Automatically from the Fire and Gas system upon confirmed signal from two
or more process areas .
• Low low instrument air pressure .
• Automatically from low export gas pipeline pressure .
• High high liquid level in H.P fuel gas KO drum.
• ESD level (0) is emergency depressurizing system and it is generated only
by manual push button on matrix panel in control room.
Unit Shut Down
• ESD level (0) is emergency depressurizing system and it is generated only
by manual push button on matrix panel in control room.
• Action:
• Close all ESD valves.
• Permission to all blow down system, however the blow down for each unit
will be manually from ESD matrix panel through operator’s intervention.
• Open SDV on plant by pass line (HAP’Y and ELGAMEL).
• ESD level (1) is same as level (0), except that the permission of blow down
is not included.
Unit Shut Down
• Unit Shutdown “LEVEL 2 ESD “will be initiated in case of one of
the following reasons occurred:
• Confirmed Fire & Gas detection in U-10.
• High High Temperature (10-TAHH-06 A/B/C ) for gas inlet to 10-E-01.
• High High liquid level (10-LAHH-03 A/B/C) for exp. feed separator 10V-01.
• High High Pressure (10-PAHH-29 A/B/C) for absorber.
• Low Low temperature (10-TALL-01) for residue gas.
• Push buttons installed in front of the unit control panel (UCP) or from
the control & shutdown system (CSS).
• Plant Level 1 ESD.
Unit Shut Down
•
•
•
•
•
•
•
•
•
•
•
•
•
– Unit Isolation and valves status :
The ESD system will close the following:
10-SDV-01 (Gas inlet to 10-E-01 Hot side).
10-SDV-14 (Bypass of 10-SDV-01).
10-SDV-02 (10-K-01A Suction).
10-SDV-04 (10-U-01A Suction).
10-SDV-07 (10-K-01B Suction).
10-SDV-08 (10-U-01B Suction).
10-SDV-09 (10-E-04 Hot Oil Supply).
10-SDV-10 (10-C-01 Bottom).
10-SDV-11 (10-C-02 Bottom).
10-SDV-12 (10-C-02 to 10-P-01 A/B).
10-SDV-15 (10-E-03 Cold Stream Outlet).
10-SDV-13 (10-V-01 Liquid Outlet).
Equipment Shut Down LEVEL 3
• Shut down of expander compressor (10-X-01A/B),
expander/compressor automatically stops at one of the following
condition:
– Expander bearing low temperature trip 10-TALL-03A/B.
– Magnetic bearing trip (alarm level 2 & level 3) 10-XSD-04A/B.
– Bearing housing low-pressure trip 10-PALL-11A/B.
– Watchdog Failure from magnetic bearing cabinet 10-XSD-02A/B.
– Expander speed too low from magnetic bearing cabinet 10-XSD03A/B.
– Expander/Compressor high-speed trip 10-SAHH-01A/B.
– Seal gas low differential pressure trip 10-PDALL-04A/B.
– Low-Low pressure of re-compressor suction line 10-PALL-14.
– High-High temperature of re-compressor discharge line 10-TAHH17.
– Low-Low Expander suction Temperature 10-TALL-01.
– High Differential pressure across Expander compressor strainers
Equipment Shut Down LEVEL 3
• Absorber Bottom Pump 10-P-02A/B Shut Down
In case of 10-P-02A/B shut down, the cause and necessary action are
as follows:
• Absorber bottom liquid Low-Low 10-LSLL-09
Equipment Shut Down LEVEL 3
• De-Methanizer Reflux Pump 10-P-01A/B Shut Down:
In case of 10-P-01A/B shut down, the cause and necessary action are
as follows:
• De-methanizer OVHD accumulator (upper section of 10-C-02) liquid
level Low-Low 10-LSLL-07.