Case StudiesA fifteen stage axial compressor including a bleed extraction was subject to a major overhaul after nearly 20 years of trouble free operation. Shortly after recommissioning and resumption of the production the compressor faced three major failures within two weeks.
A root cause failure analysis was conducted and revealed that the process plant start-up procedures caused gas compositions which deviated strongly from the design conditions. The valve designs as well as the available control parameters were not able to protect the compressor from off-design operating conditions. For future compressor failure prevention, the process start-up procedures were adapted and the existing control parameters/logic was upgraded. The new control logic reacts to the transient process behaviours during start-up by continuous harmonization of the safety valves

Schwarz, Marco

English

Texas A&amp;M Repository

Blade failures on an axial compressorby unexpected gas compositionsMarco Schwarz, MAN Diesel & Turbo SE2Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Author - BiographyMarco SchwarzEidg. dipl. Ing. mech. FH, EMBA FHRegional Head of EngineeringMAN|PrimeServMAN Diesel & Turbo North America Inc.Houston, Texas, USAResponsible for the local engineering, fleet technical support and technical proposal development in the Americas. Before joining the site in Houston in 2017 he was employed for more than 9 years at MAN Diesel & Turbo, Zurich/Switzerland where he was heading the MAN | PrimeServ’s application engineering. He was mainly responsible for thermodynamic revamp designs, technical customer support and trouble shooting on axial and centrifugal compressors.He received his diploma  in Mechanical Engineering FH from the University of Applied Science in Zurich in 2008 and post-graduated in General Management EMBA FH. Parallel to his studies he started his career as design engineer in the textile industry in 2002.3Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐SynopsisA fifteen stage axial compressor including a bleed extraction was subject to a major overhaul after nearly 20 years of trouble free operation. Shortly after re-commissioning and resumption of the production the compressor faced three major failures within two weeks. A root cause failure analysis was conducted and revealed that the process plant start-up procedures caused gas compositions which deviated strongly from the design conditions. The valve designs as well as the available control parameters were not able to protect the compressor from off-design operating conditions. For future compressor failure prevention, the process start-up procedures were adapted and the existing control parameters/logic was upgraded. The new control logic reacts to the transient process behaviours during start-up by continuous harmonization of the safety valves. 4Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Outline1 Initial Situation, Background2 Failures3Results4 Summary, Main Challenges, CountermeasuresRoot Cause Failure Analyses: Failure Mechanisms5 Countermeasures: Valve Control Logic Optimization5Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Initial Situation Compressor design:A45-15, speed controlled Application:MTBE (REC) Process gas:H2 + HC Design MW:24 – 30 g/mole Special feature:Interbleeddischarge (IB)LP-Section HP-Section6Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Background: Thermodynamic considerationflow flowheadhead100%105%85%100%105%85%Normal operation 30 g/mole, IB closedH2-strip 24 g/mole, IB partially open (correct)H2-strip 24 g/mole IB too little open (faulty)H2-strip 24 g/mole IB too much open (faulty)LP-Section: HP-Section:7Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Failure #1, January Compressor tripped after 2,5 days of operation from the re-start after a planned outagedue to high vibrations: Four blades of rotor #8 liberated Several blades of rotor #8 fractured Downstream rows damaged by Domestic Object Damage (DOD)  Rotor #8DOD8Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Failure #2, FebruaryRotor #8 Compressor tripped after 3 days of operation from compressor re-start:Rotor #8: Rotor #9: Rotor #8 liberated completely Four blades of rotor #9 liberated Downstream rows damaged by DODRotor #9DODDOD9Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Failure #3, March For the third re-start, several immediate countermeasures implemented. However… Significant step changes in vibrations shortly after thirdrestart but no compressor trip Due to non-availability of furtherspare parts:Keeping the unit in operation aslong as possible (goal: ~7 month) Step changes in vibrationsindicate further liberation of fourblades of rotor #8… 10Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐RCFA: Failure MechanismsBlade failure rotor #8IB fully open duringstart-up sequenceChoked flow rotor #8Surge stage 9?Resonance of B1-mode of rotor #8Pitting corrosionFracture initiationpointsProcess instabilities:MW = 17 g/moleFailure mechanism Failure #1 Failure mechanism Failure #2 &Incident #3IB fully open duringstart-up sequenceChoked flow rotor #8Surge cond. rotor #9Resonance of B1-mode of rotor #8Fracture on rotor #9 (mech. overloaded)Blade failure ofrotor #8 and rotor #911Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Summary, Main Challenges, CountermeasuresMain Challenges: Process-wise:Process is very difficult to be controlled during process start-up→ molecular weight can hardly be controlled→  major deviations to design values can cause catastrophic failures Control logics:The existing control logic was not capable of controlling the safety valvesduring periods with heavy gas composition fluctuationsCountermeasures: Installation of additional IB-measurements (pressure and temperature) withinthe compressor blading Control logics:Optimization of the anti-surge control logics12Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Original Valve Control LogicLP-ASC HP-ASCIBVASVDisadvantage: Adjustment of ASV affects both, LP- & HP-section (not HP-sec. only) Adjustment of IBV affects both, LP- & HP-section (not LP-sec. only)13Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Optimized Valve Control LogicLP-ASCIBVASVHP-ASCSPC devminif devLP – devHP < 0 → IBV to openif devLP – devHP > 0 → IBV to closeif devLP – devHP = 0 → IBV remain14Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Results After Field Implementation No more adverse operations outside of the operation envelopes, not even at low molecular weightsflowhead100%105%85%LP-Section: HP-Section:flowhead100%105%85% No further failures or compressor trips due to related issues 15Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐Lessons Learned Special attention must be paid for configuration of multi-sections (axial, but also centrifugal) compressors; especially different operation with deviations of molecular weights is a challenge for the proper running of the machine During the design of the control logic, several cases (even unexpected and theoretically excluded) shall be considered (at least during design reviews between operator and manufacturer)16Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristicsof each individual project, especially specific site and operational conditions.Disclaimer17Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristicsof each individual project, especially specific site and operational conditions.Case studyThank you !Do y u h ve a y more questions ?

Blade Failures on an Axial Compressor by Unexpected Gas Compositions

Texas A&M University

Blade failures on an axial compressor
by unexpected gas compositions
Marco Schwarz, MAN Diesel & Turbo SE
2Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Author - Biography
Marco Schwarz
Eidg. dipl. Ing. mech. FH, EMBA FH
Regional Head of Engineering
MAN|PrimeServ
MAN Diesel & Turbo North America Inc.
Houston, Texas, USA
Responsible for the local engineering, fleet technical support and 
technical proposal development in the Americas. 
Before joining the site in Houston in 2017 he was employed for 
more than 9 years at MAN Diesel & Turbo, Zurich/Switzerland 
where he was heading the MAN | PrimeServ’s application 
engineering. He was mainly responsible for thermodynamic revamp 
designs, technical customer support and trouble shooting on axial 
and centrifugal compressors.
He received his diploma  in Mechanical Engineering FH from the 
University of Applied Science in Zurich in 2008 and post-graduated 
in General Management EMBA FH. Parallel to his studies he started 
his career as design engineer in the textile industry in 2002.
3Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Synopsis
A fifteen stage axial compressor including a bleed extraction was subject to a 
major overhaul after nearly 20 years of trouble free operation. Shortly after re-
commissioning and resumption of the production the compressor faced three 
major failures within two weeks. 
A root cause failure analysis was conducted and revealed that the process plant 
start-up procedures caused gas compositions which deviated strongly from the 
design conditions. The valve designs as well as the available control parameters 
were not able to protect the compressor from off-design operating conditions. 
For future compressor failure prevention, the process start-up procedures were 
adapted and the existing control parameters/logic was upgraded. The new 
control logic reacts to the transient process behaviours during start-up by 
continuous harmonization of the safety valves. 
4Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Outline
1 Initial Situation, Background
2 Failures
3
Results4 Summary, Main Challenges, Countermeasures
Root Cause Failure Analyses: Failure Mechanisms
5 Countermeasures: Valve Control Logic Optimization
5Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Initial Situation
 Compressor design:
A45-15, speed controlled
 Application:
MTBE (REC)
 Process gas:
H2 + HC
 Design MW:
24 – 30 g/mole
 Special feature:
Interbleed
discharge (IB)
LP-Section HP-Section
6Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Background: Thermodynamic consideration
flow flow
h
e
a
d
h
e
a
d
1
0
0
%
1
0
5
%
8
5
%
1
0
0
%
1
0
5
%
8
5
%
Normal operation 30 g/mole, IB closed
H2-strip 24 g/mole, IB partially open (correct)
H2-strip 24 g/mole IB too little open (faulty)
H2-strip 24 g/mole IB too much open (faulty)
LP-Section: HP-Section:
7Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Failure #1, January
 Compressor tripped after 2,5 days of operation from the re-start after a planned outage
due to high vibrations:
 Four blades of rotor #8 liberated
 Several blades of rotor #8 fractured
 Downstream rows damaged by Domestic Object Damage (DOD)  
R
o
t
o
r
 
#
8
DOD
8Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Failure #2, February
R
o
t
o
r
 
#
8
 Compressor tripped after 3 days of operation from compressor re-start:
Rotor #8: Rotor #9:
 Rotor #8 liberated completely
 Four blades of rotor #9 liberated
 Downstream rows damaged by DOD
R
o
t
o
r
 
#
9
DODDOD
9Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Failure #3, March
 For the third re-start, several immediate countermeasures implemented. However…
 Significant step changes in 
vibrations shortly after third
restart but no compressor trip
 Due to non-availability of further
spare parts:
Keeping the unit in operation as
long as possible (goal: ~7 month)
 Step changes in vibrations
indicate further liberation of four
blades of rotor #8… 
10Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
RCFA: Failure Mechanisms
Blade failure rotor #8
IB fully open during
start-up sequence
Choked flow rotor #8
Surge stage 9?
Resonance of B1-
mode of rotor #8
Pitting corrosion
Fracture initiation
points
Process instabilities:
MW = 17 g/mole
Failure mechanism Failure #1 Failure mechanism Failure #2 &
Incident #3
IB fully open during
start-up sequence
Choked flow rotor #8
Surge cond. rotor #9
Resonance of B1-
mode of rotor #8
Fracture on rotor #9 
(mech. overloaded)
Blade failure of
rotor #8 and rotor #9
11Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Summary, Main Challenges, Countermeasures
Main Challenges:
 Process-wise:
Process is very difficult to be controlled during process start-up
→ molecular weight can hardly be controlled
→  major deviations to design values can cause catastrophic failures
 Control logics:
The existing control logic was not capable of controlling the safety valves
during periods with heavy gas composition fluctuations
Countermeasures:
 Installation of additional IB-measurements (pressure and temperature) within
the compressor blading
 Control logics:
Optimization of the anti-surge control logics
12Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Original Valve Control Logic
LP-ASC HP-ASC
IBV
ASV
Disadvantage:
 Adjustment of ASV affects both, LP- & HP-section (not HP-sec. only)
 Adjustment of IBV affects both, LP- & HP-section (not LP-sec. only)
13Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Optimized Valve Control Logic
LP-ASC
IBV
ASV
HP-ASC
SPC devminif devLP – devHP < 0 → IBV to openif devLP – devHP > 0 → IBV to close
if devLP – devHP = 0 → IBV remain
14Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Results After Field Implementation
 No more adverse operations outside of the operation envelopes, not even at low 
molecular weights
flow
h
e
a
d
1
0
0
%
1
0
5
%
8
5
%
LP-Section: HP-Section:
flow
h
e
a
d
1
0
0
%
1
0
5
%
8
5
%
 No further failures or compressor trips due to related issues 
15Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
Lessons Learned
 Special attention must be paid for configuration of multi-sections (axial, but also 
centrifugal) compressors; especially different operation with deviations of 
molecular weights is a challenge for the proper running of the machine
 During the design of the control logic, several cases (even unexpected and 
theoretically excluded) shall be considered (at least during design reviews 
between operator and manufacturer)
16Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
All data provided in this document is non-binding. 
This data serves informational purposes only and is especially not guaranteed 
in any way. Depending on the subsequent specific individual projects, 
the relevant data may be subject to changes and will be assessed and 
determined individually for each project. This will depend on the particular 
characteristics
of each individual project, especially specific site and operational conditions.
Disclaimer
17Marco Schwarz,  MAN Diesel & Turbo 03‐2018r   rz,     i s l    r ‐
All data provided in this document is non-binding. 
This data serves informational purposes only and is especially not guaranteed 
in any way. Depending on the subsequent specific individual projects, 
the relevant data may be subject to changes and will be assessed and 
determined individually for each project. This will depend on the particular 
characteristics
of each individual project, especially specific site and operational conditions.
Case study
Thank you !
Do y u h ve a y more 
questions ?


https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/172465/22_Schwarz.pdf?sequence=1&isAllowed=y

Blade Failures on an Axial Compressor by Unexpected Gas Compositions

Abstract

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Texas A&M Repository

Texas A&M University

Blade Failures on an Axial Compressor by Unexpected Gas Compositions

Abstract

Similar works

Full text

Available Versions

Texas A&amp;M Repository

Texas A&M University

Texas A&M Repository