Sonatrach Antisurge PDF
Sonatrach Antisurge PDF
Sonatrach Antisurge PDF
Prerequisite:
Trainees must have already performed the Centrifugal Compressor Basic course.
Expected Audience:
Course Content:
1.
2.
3.
4.
Choking or Stonewall
Rotating Stall
Surge
GE
Oil & Gas
5.
Auto/manual operation
6.
7.
Course Duration:
2 Days
GE
Oil & Gas
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TRAINING MANUAL
This manual contains proprietary information of GE Oil & Gas Nuovo Pignone
S.p.A. (GE Oil & Gas), and is furnished to its customers solely for customer
training courses purposes.
This manual shall not be reproduced in whole or in part nor shall its contents
be disclosed to any third party without the written approval of GE Oil & Gas.
The instructions and information contained in the manual do not purport to
cover all details or variations in equipment, or to provide for every possible
contingency to be met during installation, operation, and maintenance.
Should further information be desired or should particular problems arise that
are not covered sufficiently for the purchasers purpose, the matter should
be referred to GE Oil & Gas.
Reviewed
Massimiliano Romizi
Manual Specialist
/1/2013
Verified
Validate
Sandro Fantini
Mechanical
Instructor Leader
Customer Training
Manager
/2/2013
/2/2013
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TRAINING MANUAL
INDEX
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TRAINING MANUAL
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Driven machine
Rotating machine
Its duty is to increase the gas pressure
How it works?
Increase the kinetic energy throgh rotating components and converts it into static pressure through the stator
components, using the torque given by the driver
Transport
Create chemical reactions
Gas storage
Enhance oil production
2
Antisurge
Oil/Gas field
Offshore production platform
Re-injection plant
3
Antisurge
4
Antisurge
5
Antisurge
Fin
Casing
Blade
Impeller
Shaft
Inlet Volute
Suction Nozzle
Suction Pipe
6
Antisurge
Gas inlet
7
Antisurge
Blades
Diffuser
Return
channel
8
Antisurge
P3,C3
P2,C2
P4,C4
P1,C1
Energy
1
Impeller Inlet
Blade
Inlet
Diffuser
Inlet
Diffuser
Outlet
As shown in this diagram: in the impeller both the velocity and pressure increase; in the diffuser the pressure increases and
the velocity decreases due to the convergent design; and in the return channel there is no increase in pressure because the
convergent design is chosen only to avoid load losses.
The return channel is bladed in order to more effectively convey the gas toward the next impeller inlet, thus reducing load
losses, but there is no further increase of pressure downstream the diffuser outlet.
We can state that all the pressure increase realized within a compressor stage is made between the blade inlet and the
diffuser outlet.
10
Antisurge
Last impeller
Discharge volute
11
Antisurge
Polytropic Head
Polytropic Efficiency
Pressure Ratio
Power
Discharge Temperature
Discharge Pressure
12
Antisurge
105%
100%
98%
90%
80%
Minimum
operating speed
(MOS)
65%
Inlet capacity
13
Antisurge
Operating range
Surge Limit
Line
105%
100%
98%
90%
80%
65%
Choking Area
14
Antisurge
105%
100%
98%
90%
80%
Operating
point
65%
15
Antisurge
105%
100%
98%
90%
80%
65%
16
Antisurge
105%
100%
98%
90%
80%
65%
Operating
stability
Turndown Range
17
Antisurge
Operating range
Surge Limit
Line
105%
100%
98%
90%
80%
65%
Choking Area
18
Antisurge
19
Antisurge
The flow reaches M=1 at the inlet of the impeller (restricted section);
Shock wave
20
Antisurge
What is it surge?
"Axis-symmetric stall", more commonly known as "compressor surge" or "pressure surge", is a complete breakdown in
compression resulting in a reversal of flow. This phenomenon occurs when the machine operates at a compression ratio close the
maximum that the compressor can furnish at the speed at which it is running.
What is it due to?
Its due to the compressor's inability to continue working against the already-compressed gas behind it.
What happens?
The compressor either experiences conditions which exceed the limit of its pressure rise capabilities or is highly loaded such
that it does not have the capacity to absorb a momentary disturbance, creating a rotational stall which can propagate in less
than a second to include the entire compressor.
Which are the main factors leading to Surge?
During the normal operation: Increase of discharge pressure, downstream the compressor; decrease of suction pressure;
increase of suction temperature.
Due to high plant resistance, during Start up and Shutdown theres a high risk of surge phenomenons.
21
Antisurge
Surge is the left limit of performance curve, on the left of this line the compressor operates in unstable condition;
All surge points, defined for different speeds represent the Surge Limit Line SLL;
22
Antisurge
P2 > P1
P1
Axial thrust
23
Antisurge
P2
P1 > P2
P1
Axial thrust
24
Antisurge
Pressure
Time
Time
Rapid pressure oscillations with process instability
Rising temperatures
inside the compressor
Time
25
Antisurge
Temperature rise
26
Antisurge
27
Antisurge
Operating range
Surge Limit
Line
105%
100%
98%
Operating
90% point
80%
65%
Choking Area
28
Antisurge
Antisurge Valve
Instrumentation:
Electronic controller
Antisurge valve: Is a regulating valve, to avoid excessive recycles of flow that will reduce the output of the machine. Recycles
flow from discharge to suction in order to reduce system resistance. Cv of this valve, according to the stroke, is first
equiexponential, for smooth regulation, then linear, for protection. Is a Failure Open valve and is equipped with a solenoid
valve for quick opening. Antisurge valve fully open (ZSL XXX) is a permissive to start.
Instrumentation: The flow transmitter can be a rotameter, an annubar or, more commonly, a differential pressure transmitter
across a calibrated orifice. In the last case we need also to measure the gas temperature to calculate the right density of the
gas.
29
Antisurge
30
Antisurge
31
Antisurge
SL
SPL
SCL
32
Antisurge
SPL
SL
SCL
33
Antisurge
PDH
HMI
UDH
EXT.
POWER
COMPRESSOR
PLC
F&G
SIS
Mark VI
MCC
BN
MP
AUXILIARY
TURBINE
GEAR BOX
COMPRESSOR
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Main parts
2
1
1r
4
3
1s
1. VME rack
r. Rack R
s. Rack S
t. Rack T
2. Protection Module
3. Terminal Boards
4. PDM
5. DACA1 (AC/DC)
6. Input filters
1t
5
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I/O board
I/O board
FIELD
I/O board
I/O board
I/O board
I/O board
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I/O board
I/O board
FIELD
I/O board
I/O board
I/O board
IONet (ethernet)
I/O board
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HMI Introduction
toolbox
The Cimplicity is a software for the definition and visualization of the HMI
screens for real time control of power-plant, processes and equipment.
In addiction, throught the Cimplicity software the operator can issue
commands to the selected turbine or driven devices.
cimplicity
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HMI Introduction
TCI
alarm
Mark VI
feedbacks
commands
cimplicity
EGD
toolbox
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Antisurge signals
TEMPERATURE
TRANSMITTER
PT-721
PT-723
FT-721
TT-715
TT
MKVI
FV-722
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Antisurge signals
Mark VI
Position L
Command: a20as
Position H :
ON/OFF signal
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AS Sequence in MKVI
Antisurge master enabling signal
L4AS
Antisurge master enabling signal
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AS Sequence in MKVI
Start/Purge sequence
stopped
Compressor
purge
AS purge
From L14LR = 1 (shaft
revolution)
acceleration
Load
L4AS = 0
A20as = 0% (AS valve completely opened)
A20as = 100% (AS valve completely
closed) to purge the compressor
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AS Sequence in MKVI
Antisurge control Loop
A20AS_MAR
a20as
A20AS_PARM
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AS Sequence in MKVI
Antisurge control Loop
A20AS_MAR
a20as
A20AS_PARM
AS Sequence in MKVI
Antisurge control Loop
A20AS_MAR
a20as
A20AS_PARM
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AS Sequence in MKVI
Antisurge specific funtions
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AS Sequence in MKVI
Antisurge specific funtions
TRANSIENT ABSORPTION
(L20AS_TA):
It is activated in case of rapid
approaching to surge line.
Detection: threshold K20AS_TA
(5 10
) is reached and
override by derivative parameter
A20AS_PARAM.
Action: the setpoint A20AS_MAR is
increased by multiplying factor
K20AS_TA_G (1.15).
The original setpoint is than
restored when the derivative
parameter returns below the slow
rate threshold K20AS_TA_R
(5 10
).
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AS Sequence in MKVI
Antisurge specific funtions
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AS Sequence in MKVI
Antisurge specific funtions
SAFETY PROTECTION (L20AS_SPR):
It is activated if operating point
approches surge line more than
protection line (SPR).
Detection: AS parameter <
K20AS_SPR
Action: recycling valve fast opening
ramp is initiated. Than safety
protaction terminate when
operating point parameter is above
safety protection SPR line with
hysteresis K20AS_SPRH.
If the situation is not OK in 10s an
alarm indicates a problem in the AS
valve opening.
Safety protection is also active
during START/STOP sequence.
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AS Sequence in MKVI
Antisurge specific funtions
PROTECTIONS DISABLING
When unit is operative (L4AS = 1),
safety protection and correction
can be disabled (normally to allow
surge zone exploration) by the
override command L43AS_O_CMD.
In this case alarm L43AS_O_ALM is
generated.
DANGER !!!
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AS Sequence in MKVI
Antisurge specific funtions
MANUAL OPERATION (L43AS_CMD)
Manual operation can be selected if at least one of the following condition is verified:
Safety protection od safety correction not active
Antisurge master enabing signal disabled (L4AS = 0)
Protections disabled (L43AS_O_CMD)
If MANUAL OPERATION is selected, recycling valve positio n is
managed by five pushbuttons (with a ramp of 1%/s):
1.
2.
3.
4.
5.
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Speed variation
105%
100%
98%
90%
80%
65%
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Cooled bypass
105%
100%
98%
90%
80%
65%
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Pout
Qin1
DRIVER
1
Collector
Pout1
C1
Qin2
Pout2
DRIVER
2
C2
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Train 1
Train 2
105%
105%
100%
98%
100%
98%
90%
90%
80%
65%
80%
65%
If Driver1 increases its rpm, Pout1 increases. Pout = Pout1 =Pout2, so also Pout2 increases changing the resistance
curve of the second compressor. For that reason the working point 2 goes closer the surge limit.
When a train in a parallel configuration changes its speed, also the speed of the other train must be changed in the
same way.
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Pout
Qin2
Qin1
Pout1
C1
DRIVER
2
C2
Collector
DRIVER
1
Pout2
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Pout
Qin2
Qin1
Pout1
C1
DRIVER
2
C2
Collector
DRIVER
1
Pout2
AS valve
Qin
Pout
DRIVER
Because the 2 compressors cannot be perfectly equal (for costruction tolerances, dirty...) even if they are revolving a
the same speed, they will work a little bit differently one by the other.
In consideration of that: speed regulation is not enoght .
A fine regulation of the load sharing, both for series and parallel configurations, needs to be
implemented by means of Cooled bypass method.
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Antisurge
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TRAINING MANUAL
SEZ . Drawings
GE
Oil & Gas
Drawings Index
BCL505/N assembly drawing
SOS9929211
Performancecurves
SOS9983763
SOM5081477
Instrument list
SOM6609947
SOM6670429
Antisurge Valve
SOS7248866
RV 28465
Antisurge write-up
SOS9983403
Performance curves
SOS9983763