furnace
TRANSCRIPT
PREDICATION OF
RESIDUAL LIFE TIME OF RESIDUAL LIFE TIME OF
STEAM REFORMER TUBES
Prof Bahaa ZaghloulProf. Bahaa ZaghloulEx‐President of Central Metallurgical Research and Development Institute ‐ CAIRO, EGYPT [email protected]
DIFFERENT APPLICATIONS OF DIFFERENT APPLICATIONS OF REFORMER TUBES …REFORMER TUBES …
CMRDI
Limit of tube Metal Applications
40pp
Hg/cm
2 G)
30H2
essu
re (K
g
20NH3
CH3OH
Pre
10Town Gas
D. R.
10
700 800 900 1000
Gas Temperature (OC)
LIMITATION OF OPERATION LIMITATION OF OPERATION TEMPERATURE …TEMPERATURE …
CMRDI
Inlet
Control to Prevent Carbon Formation
Tube
al
yst T
Control the Max. Tube Skin Temperature C
ata
Critical PortionOutlet
DIFFERENT DESIGNS FOR REFORMER DIFFERENT DESIGNS FOR REFORMER FURNACE …FURNACE …
CMRDI
1 3
Radiant UPRadiant Wall Type
UP
Firing Type
Terrace DownTerrace Wall Type Firing Type
2 4
EFFECT OF FIRING SYSTEM ON TEMP. EFFECT OF FIRING SYSTEM ON TEMP. PROFILE …PROFILE …
CMRDI
I UP II D III DOWN & UPI . UP II . Down III . DOWN & UP
PreferablePreferablePreferable Preferable ProfileProfile
V . RADIANT WALL
IV . TERRACE WALL
IDEAL TEMPERATURE PROFILE …IDEAL TEMPERATURE PROFILE … CMRDI
InletInlet
OutletGas Temperature
Heat Flux Tube Skin Temperature
Solid Line : Ideal Profile Dotted line : Preferable Profile
REFORMER TUBES MATERIALS REFORMER TUBES MATERIALS EVALUTION CHARTS …EVALUTION CHARTS …
CMRDI
HK40
HK40‐high Si25Cr‐20Ni-high Si
IN519 IN519‐mod.
Si
Nb Ti
25Cr‐20Ni
HI‐Ka1a25Cr‐20Ni-Ti‐MS
24Cr‐24Ni‐Nb 24Cr‐25Ni-Nb‐TiTi
BST‐Alloy25Cr‐20Ni‐Ti‐Nb
HI‐Ka1b25Cr‐20Ni-Nb‐Ti‐MS
Nb
MS: MishmetalHT
HT‐mod.20Cr‐32Ni‐C
15Cr‐35Ni
HU19Cr‐39Ni
Alloy 80020Cr‐32Ni
Manaurite 900 T52 PG20‐32
Nb Nb
T52,PG20‐32 CR32W,KHR32C
20Cr‐32Ni‐Nb‐Low C
Manaurite 36X Su‐Paralloy H39W
Manaurite 900B Paralloy CW39WLow C
Nb
WHP
25Cr‐35Ni‐Nb 25Cr‐35Ni‐Nb‐Low C
Manaurite 36XM HP‐BST
25Cr‐35Ni‐Nb‐Ti
Ti
WW
Mo
26Cr‐35NiMo‐Re 1
25Cr‐35Ni-WManaurite 36XS25Cr‐35Ni-Nb‐W
Su‐Paralloy H34CTManaurite 900
Nb
Co
25Cr‐35Ni-5W‐2Co
Supertherm28Cr‐35Ni-5W‐15Co
Manaurite 900 T52,PG20‐32
20Cr‐32Ni‐Nb‐Low C Co
REFORMER TUBES MATERIALS REFORMER TUBES MATERIALS EVALUTION TABLES …EVALUTION TABLES …
CMRDI
METALLURGY DEVELOPMENT
RELATIVE Nb Ni Cr COMMON
DEVELOPMENT
RELATIVE STRENGTH
OTHERSNb %
Ni %
Cr %
COMMON NAME
DATE
HK6 1.0‐‐‐‐‐‐2025HK401960s
1.4‐‐‐12425IN5191970s 4455 997
1.7Ti12223BSTEarly 80s
1.9Ti13525HP – BSTMid 80s
2.2Ti, Zr, W, Cs13525HP Micro‐alloyLate 80s
CREEP RAPTURE STRENGTH OF CREEP RAPTURE STRENGTH OF COMMERCIAL MATERIALS …COMMERCIAL MATERIALS …
CMRDI
20
108
6
gf/m
m2)
4
ress
(K
g
BST - M
25 35Ni Nb
2
Str 25 – 35Ni - Nb
IN 519HPHK 40
100 1000 10000 100000
Time to Rupture (h)
CREEP RAPTURE STRENGTH OF CREEP RAPTURE STRENGTH OF COMMERCIAL MATERIALS …COMMERCIAL MATERIALS …
CMRDI
CREEP RAPTURE STRENGTH OF CREEP RAPTURE STRENGTH OF COMMERCIAL MATERIALS …COMMERCIAL MATERIALS …
CMRDI
Rapture Stress for Generic Tube Materials …
35
25
30
/mm
2 )
20
tres
s (N/
10
15
Rapt
ure St
5
10R
0HK40 IN519 HP ‐
BSTHP Micro‐
alloyBST
FAILURE MODE OF REFORMER TUBE …FAILURE MODE OF REFORMER TUBE … CMRDI
CMRDICROSS SECTION OF FAILED REFORMER CROSS SECTION OF FAILED REFORMER TUBE …TUBE …
PROGRESS OF CREEP FAILURE …PROGRESS OF CREEP FAILURE … CMRDI
START GROWTH FAILURE
Cracks 30% from inner wall
Cracks grow to break inner wall
Cracks progress to outer wall
EFFECT OF MACROSTRUCTURE ON EFFECT OF MACROSTRUCTURE ON CRACK PROPAGATION …CRACK PROPAGATION …
CMRDI
TYPICAL CREEP DAMAGE MECHANISM TYPICAL CREEP DAMAGE MECHANISM IN REFORMER TUBES …IN REFORMER TUBES …
CMRDI
D
FRACTURE
D
rain
C
Breep
Str
A
I II III
C
I, II, III :
Creep Ranges
Exposure Time
Microstructure Evaluation of Cast Steel Tubes During Operation Time in Reformer Furnace … CMRDI
Change In Tube Microstructure During Operation in Reformer
Furnace
PRIMARY AND
Change in primary inner dendriticChemical composition
PRIMARY AND SECONDARY PHASES
MATRIX
Change in primary inner dendritic austenite‐carbides eutectic
Secondary carbides precipitation and
Chemical composition modifications & accompanied heterogenty in solid solution
Secondary carbides precipitation and interactions with primary carbides
Continuous carbides network formation around austenite grains
Changes in dislocation structure and dislocation density growth
Ch i t it i formation around austenite grains
Coalescence of sigma phase inside and around austenite grains
Changes in austenite grain boundary microstructure due to the carbides coalescence and voids formation g
CMRDI
Eff t Of Mi t t lEffects Of Microstructural
Changes In Reformer Tube
Decrees In Creep ResistanceResistance
Microvoids Initiation On Deterioration On
Mechanical Properties Interphase Boundaries
id iVoids Propagation
Voids Coalescence Into Fissures
COMMON DAMAGE MECHANISM IN COMMON DAMAGE MECHANISM IN REFORMER TUBES …REFORMER TUBES …
CMRDI
1. Overheating (Cumulative)
2. Thermal Cycling ( cyclic operation )
T b B di ( i i h b l 3. Tube Bending ( improper counter weight balance
for tube linear will increase stress on tube)for tube linear will increase stress on tube)
4. Thermal shock
5. Stress Corrosion Cracking
OVERHEATING CMRDIOVERHEATING
Temperature Increase To Maintain Yield When Catalyst Becomes Less Active.
1
Feedstock Or Steam Supply Failure 2
The Absence Of Cooling Effect Of The Endothermic Reaction3
Burner Misalignment Can Result In Over Temperature4 Burner Misalignment Can Result In Over Temperature4
Restricted Flow Of Process Due Catalyst Choking5
EFFECT OF OPERATION TEMPERATURE EFFECT OF OPERATION TEMPERATURE AND PRESSURE ON TUBE LIFE …AND PRESSURE ON TUBE LIFE …
CMRDI
COMMON DAMAGE MECHANISM IN COMMON DAMAGE MECHANISM IN REFORMER TUBES …REFORMER TUBES …
CMRDI
1. Overheating (Cumulative)
2. Thermal Cycling ( cyclic operation )
T b B di ( i i h b l 3. Tube Bending ( improper counter weight balance
for tube linear will increase stress on tube)for tube linear will increase stress on tube)
4. Thermal shock
5. Stress Corrosion Cracking
THERMAL CYCLES CMRDITHERMAL CYCLES
Through Wall Stresses are Temporarily Increased1
Tube Wall Temperature Gradients Can Be Significant2 Tube Wall Temperature Gradients Can Be Significant2
During Operation , The Stress Produced By Different Expansion Relaxes Through Creep 3
Temperature Changes Up Or Down Will Reintroduce Some4 Temperature Changes Up Or Down Will Reintroduce Some Stress.4
COMPARISON OF STRESS DISTRIBUTION IN CYCLIC OPERATION …
CMRDI
HK40
IN519
COMMON DAMAGE MECHANISM IN COMMON DAMAGE MECHANISM IN REFORMER TUBES …REFORMER TUBES …
CMRDI
1. Overheating (Cumulative)
2. Thermal Cycling ( cyclic operation )
T b B di ( i i h b l 3. Tube Bending ( improper counter weight balance
for tube linear will increase stress on tube)for tube linear will increase stress on tube)
4. Thermal shock
5. Stress Corrosion Cracking
THERMAL SHOCK CMRDITHERMAL SHOCK
Creates Extremely High Stresses As The Tube Attempts To C t t U d R t i t1 Contract Under Restraint .1
It Results In Circumferential Tearing Or Shattering Of The Tube.2
Can Occur Through Boiler Water Carry Over On Inside The Tubes3
EFFECT OF OPERATION TEMPERATURE ON EFFECT OF OPERATION TEMPERATURE ON MICROSTRUCTURE OF INMICROSTRUCTURE OF IN519 519 MATERIAL …MATERIAL … CMRDI
MICROSTRUCTURE OF IN519 CAST STEEL TUBE …
N d d d l ft 24000 hNon degraded sample after 24000 h
after 30000 h
Operation in Reformer furnace 86000 h
FAILURE ANALYSIS OF PRIMARY REFORMER TUBE … CMRDI
OPERATION PERIOD = 6 Years
Top Flange
Rapture Zone
Rupture Zonep
Top Flange
CMRDIGENERAL AND ENLARGED VIEWS OF OUTER
AND INNER SURFACES OF RUPTURE ZONE OF
REFORMER TUBE.
NOTE: NON‐UNIFORM WIDTH OF BRANCHED CRACK.
CMRDISUMMARY OF MICROSTRUCTURE CHANGE THROUGH THICKNESS, ALONG REFORMER
GTUBE LENGTH …
S1:30 cm from top flange
S2:114 cm from top flange
1000X
S4:
1000X
S8:Rupture zone320 cm from top flange
1070 cm from top flange
200X 1000x
S4:1255 cm from top flange
S12:1330 cm from top flange
500X 1000x
FAILURE OFPRIMARY REFORMER TUBE … CMRDI
OPERATION PERIOD S4PERIOD
18 YearsRUPTURE
S1
S2
S3
RUPTURE
S5
A
S1
CB
1000X1000 X1000
X
1000X
1000X
1000X1000X
1000X
Header
200 x 1000XHeader
50x
PRIMARY REFORMER TUBE … CMRDI
Tube: 135.6mm , 12.8mmMaterial: HP‐Nb – 0.4C, 35Ni, 25Cr, 1.24Nb
Pressure : 35.7 bar
OPERATION PERIOD = 9 Years
Pressure : 35.7 bar
Skin Temp.: 917oC Max 860oC Min
100XTest Coupon 5
e e
Su
rface
Su
rface
Inn
er
S
Ou
ter
S
Test Coupon 3
TEST COUPON 5
TUBE WALL CENTER100X 400XTUBE WALL CENTER100X 400X
TEST COUPON 3
RESULTS OF CREEP RUPTURE TEST OF USED PRIMARY REFORMER TUBE …
CMRDI
Creep Rupture Strength Master Curve for Used
& Unused Primary Reformer Tube Materials …CMRDI
y o
LMP = T ( C + tr ) 10‐3
T: Test T (OK),tr : Rup. time (hr)C: Constant
Thi f f d t l t i dThis form of data plot is usedto extrapolate short‐term testdata to rupture stresses up to100 000 hr100,000 hr
Working S is a function of mainly circum., long., and thermal S.
The most critical one is the circum. S & it was assumed to be 1.8kg/mm2
based on the following equation. (ASME ‐ Section VIII ‐ Division 1)
S = ( P R + 0.6 P t ) / E t( ) /
S: Maximum allowable stress value.P I t l d i P ll bl ki PP: Internal design P or max. allowable working PR: Inside radius E: Joint efficiency t: Min. thick
ki d b OSkin T was assumed to be 917 OC,
Remaining life‐time is calculated from data of Larson‐Millar parameter
of used reformer tubeof used reformer tube.
The remaining life was estimated based on S & skin T. to be ~20,000 hr
at 1 8 kg/mm2 working Sat 1.8 kg/mm2 working S.
The life‐time will be increased at lower skin T
ESTIMATED RUPTURE TIME OF USED PRIMARY REFORMER TUBE UNDER CMRDI
DIFFERENT TEMPERATURES & STRESSES
1.8kg/mm2
2.5kg/mm2
917oC
NON DESTRUCTIVE TESTING METHODS NON DESTRUCTIVE TESTING METHODS
FOR DAMAGE EVALUATIONFOR DAMAGE EVALUATIONCMRDI
FOR DAMAGE EVALUATION…FOR DAMAGE EVALUATION…
Dimensional changes; diameter and wall thickness due to creep
R li t l h t h k f i t t l hReplica metalography; spot check for micro structural changes
due to overheating and some times creep damage
Radiography; large voids and micro cracks
Eddy current; chromium migration due overheating andEddy current; chromium migration due overheating and
conductivity changes
Ultrasonic; attenuation and scattering
New techniques such as LOTIS and IESCO ‘H’ SCANNew techniques such as LOTIS and IESCO H SCAN
CREEP DAMAGE EVALUATION METHOD …CREEP DAMAGE EVALUATION METHOD … CMRDI
New Project forNew Project for
P O RPREDICTION OF REMAINING
LIFE OF REFORMER TUBES
&
PARTICIPATING CMRDI Fraunhofer IWM COMPANIES
CMRDI Egypt
Fraunhofer IWM Germany
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
Possible Industrial Partners:
Egyptian Fertilizers Co., Ain El-Sukhna, EFC
ALEXFERT Alexandria Fertilizers Co., Alexandria
D lt F tili C T lkhDelta Fertilizer Co.,Talkha
Apu‐Quir Fertilizer Co.; Alex
Schmidt + Clemens,Centrifugal Casting Div., Kaiserau
UHDE Engineering Egypt, Cairo
LIFE ASSESSMENT REQUIREMENTS…LIFE ASSESSMENT REQUIREMENTS… CMRDI
Requirements Requirements For Analysis
To undertake a furnace life assessment the following input information is required …
Furnace design drawings / material records / Operation history (turn-around and process conditions)
Process temperature and pressure records as available
Tube samples for material specific assessment
A i t NDT t h i d tAppropriate NDT techniques data
LIFE TIME PREDICTION OF
Collection / Selection Of Tube Materials, Geometries, Plant, Connections And Process Conditions
PREDICTION OF REFORMER TUBES
Development Of Test Set Up And Measurement Techniques For Specimens And Model Tubes.
Continued Testing Of Specimens From Used Tubes And Failure Cases
Testing Of Virgin Material Specimens In Tension, Creep And Thermal Fatigue Acc. To Service
NDE Of Used TubesProfilometry
Vi l
Repeated Examination Of Damage ‐ NDE E.G. Eddy Current, UT ‐ Hardness
Visual UT, EC, …
X‐ray
‐Metallography, Microstructure. ‐ Sem & Edx
Material Description for
Evaluation Of Mechanisms And Degree Of Damage In
Used Tubes
Material Description for‐ deformation ‐ damage‐ failure incl. overlapping effects
Model Component Test And Simulation (Short Section Of Tube
Implementation In FE Code
Simulation (Short Section Of Tube Exaggerated Loading, Shorter Times)
Verification – Comparison Of Calculation (Material Degradation Component Behavior)
With Measurement Results
Material / microstructure based life time prediction applied to a specific plant
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 1 : COLLECT & SELECT INPUT DATA
- Tube material (properties, behaviour), -dimensions
- Plant design: inlet/outlet pigtails,firing system,welds,…
- Operational conditions: feedstock ratepressurefluid temperaturepskin temperaturethrough wall temperaturestart up/shut down cyclesstart up/shut down cyclesprocess upsets…
- service experience
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP STEP 22 : DEVELOP TEST SET UP AND MEASUREMENT
TECHNIQUES FOR ROUND BAR SPECIMEN
TESTS ON REFORMER TUBE MATERIALS
Cyclic strain- and temperatures tests
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 3 : DEVELOP TEST SET UP AND MEASUREMENT
TECHNIQUES FOR MODEL REFORMER TUBE TESTS
Optical Strain Measurement
HAZ T915‐10mm
HAZ T915‐10mm
NiCr20Nb Austenite55
5 mm10 mm
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 4 : TESTING OF VIRGIN AND USED REFORMER TUBE MATERIAL SPECIMENS
‐ LCF‐tests at RT up to service temp. (950°C)
REFORMER TUBE MATERIAL SPECIMENS
Grobkorn-WEZ 625°CGrobkorn-WEZ 550°C
300 p p ( )‐ cyclic hardening/ softening‐ hystereses‐life time
100 interkritischeWEZ 625°C
Grobkorn-WEZ 650°C
Fg in
MPa
‐ TMF with realistic T‐e –cycles‐ in/out of phase‐ hold times‐ heating and cooling times
WEZ 625 Cinterkritische WEZ 650°C
50 WEZ3 GK WEZ2 FK WEZ1 IKGW FZJ
T in °C 550 625
Span
nun
‐ Creep tests10 100 1000 10000
GW MFI 650
Zeit in h
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 5 : MEASUREMENT OF DEFORMATION, DAMAGE & FAILURE; EVALUATION OF MECHANISMS IN THE TUBE MATERIALSEVALUATION OF MECHANISMS IN THE TUBE MATERIALS
‐ NDE: dimensional measurements, UT, EC, …
‐ Hardness
‐Metallography, microstructure, replica techniques
‐ SEM & EDX
Cyclic Plastic Deformation
Creep DamageMicro/Macro Cracking Corrosion
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 6 : MATERIAL DESCRIPTION FOR DEFORMATION, DAMAGEAND FAILURE INCL OVERLAPPING EFFECTSAND FAILURE INCL. OVERLAPPING EFFECTS
‐Material models for cyclic plastic deformation (Chaboche, Jiang)
- IWM Software FITIT®
950°C
)(4,245122
TFD plIeffI ⎞⎜⎛
∆∆∆ σσ
‐ Damage parameter
),(31
,45,1 , tTFNE
D ple
ecy
I
cy
effITMF ⎟
⎠⎜⎜⎝
∆∆+
+= εσσσ
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 7 : IMPLEMENTATION OF NEW MATERIAL STRUCTURAL (FE) MODELSSTRUCTURAL (FE) MODELS(EVALUATION OF SPECIMEN TEST RESULTS)
Application Of Damage Parameter DTMF
To LCF‐ and Tmf‐tests
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 8 : VALIDATION BY
‐ Post evaluation of well documented failure cases from fertilizer plants(parameter studies!)
‐Model component tests and FE simulation (short tube section, exaggerated loading, shorter times,…)
Tube Tests
500
600600
Internal pressure: 480 bar T
300
400
500
300
400
500
pera
tur [
°C]
pres
sure
in b
ar,
load
in k
Nes
sure
, bar
oad,
kN
Temperatur
100
200
100
200 Tem
p
Inte
rnal
pax
ial
Axial load41.8 kNIn
tern
. Pre
Axi
al lo
re [°C]
FE - Simulation OfStresses & Strains
01 2 3Cycles
0
Cycles
LIFE TIME PREDICATION FOR STEAM LIFE TIME PREDICATION FOR STEAM REFORMER TUEBS…REFORMER TUEBS… CMRDI
STEP 9 : APPLICATIONS
Material tests/ microstructural analysis and FEM simulation ‐ based
V lid t d P d t t b h i d t i tValidated Procedure to assess component behavior under transient
severe service conditions
Ready To Be Used For
‐ Life Time Management of catalyst steam reformer tubes
‐ Process Optimisation
‐ Inspection Strategy development
‐ Reconsidering plant Design and Operating Conditions
YOUR KIND PARTICIPATION IN THE PROJECT
WILL BE HIGHLY APPRECIATED
M Th k F EFC Wh I i d M F Thi P i Many Thank For EFC Who Invited Me For This Presentation
&THANKS FOR YOUR ATTENTION
&THANKS FOR YOUR ATTENTION