VP - SPEC Technologies Inc.
INCREASING PLANT RELIABILITY
& INTEGRITY MANAGEMENT
USING CFD & CORROSION
SIMULATION
Regan Pooran, P.Eng.
VP-SPEC TECHNOLOGIES INC.
TOPICS OF DISCUSSION

Who VP-SPEC Technologies Inc. is?

Key Purpose, Process & Payoff for our
discussion

Briefly review a real world case:
Deterioration of an Amine System
Regenerator

Conclusion
2
WHO ARE WE?
3
VP-SPEC TECHNOLOGIES INC
BACKGROUND
•
•
We are a consulting company (based out of Oil Rich
Alberta) specializing in Asset Management Systems –
focusing mainly on the Process Industry.
Our customer base includes: Husky Energy, Suncor,
Nalco/ Exxon, EnCana Energy, Enerplus Trust etc…
4
PURPOSE, PROCESS, PAYOFF
5
PURPOSE, PROCESS, PAYOFF
•
Key Purpose:
•
•
Process:
•
•
•
To demonstrate how CFD (Fluent Inc., CFD Modeling ) & Corrosion
Simulation (OLI Systems, Corrosion Analyzer) are applied
synergistically to improve Plant Reliability & Integrity
Management.
Discuss how CFD & Corrosion Simulation were applied to confirm
deterioration mechanisms in an Amine System Regenerator that
has had multiple failures
Open discussion – please interrupt if you have questions
Payoff:
•
An understanding of how CFD & Corrosion Simulation can be
applied to improve your Plant’s Reliability & Integrity Management6
THE TRADITIONAL &
THE IMPROVED PERSPECTIVE
FOR ASSET INTEGRITY
MANAGEMENT
7
TRADITIONAL PERSPECTIVE
•
•
Traditionally plants have entirely relied on results from
internal inspections, corrosion monitoring with coupons and
probes, thickness measurements, and process constituent
monitoring to assess equipment integrity and prevent
equipment failures.
These results, however, produce either coincidental or
lagging indication of deterioration activity within equipment:
-
•
Coincidental indicators (e.g. TM) provide information on
deterioration activity at same time this activity is occurring.
Lagging indicators (e.g. internal inspections) provides
information on deterioration activity that trail behind this
activity.
Further these results provide limited insights into the
deterioration mechanism
8
AN IMPROVED PERSPECTIVE
•
•
For systems that can incur significant economic and
safety consequences, if failures happen, coincidental
and lagging indications of deterioration activity are
simply not sufficient.
In these systems, predictive indications and
parameter sensitivity studies of deterioration activity
is additionally required for optimum equipment
reliability and integrity management.
9
REVIEW OF PROBLEMS WITHIN
AN AMINE SYSTEM
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AMINE SYSTEMS
•
•
Amine systems remove H2S and CO2 from field gas or
from effluent gas of various plant systems
Equipment failures in amine systems can produce
significant economic and safety consequences for an
owner-user.
-
Thus, predicting deterioration activity and
conducting sensitivity studies on high-risk
equipment in these systems can be justified.
11
AMINE SYSTEM FLOW SCHEME
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REVIEWED SAMPLE CASE
• Specific real world sample case in review:
Deterioration of an Amine Regenerator from
Trays 20-15 (Upper Section)
13
DETERIORATION OF REGENERATOR
TRAYS 20-15
1. Deterioration history of Amine Regenerator from
Trays 20-15 is described as such:
•
Hole-through was experienced at Trays 20 & 15 level
•
Deterioration progressed from Tray 20 to 15 over time
•
Deterioration observed from inspection (in 2005):
-
-
•
In between trays (specifically at or slightly above vapor/
liquid interface level at each tray)
On tray support in welded area
In downcomer areas and circ seam
Deterioration was most significant in downcomer
areas and circ seams
14
DETERIORATION OF REGENERATOR TRAYS 20-19
SECTION (ILLUSTRATION – W/ DESCRIPTION)
15
ACTUAL CAUSE ANALYSIS:
REGENERATOR DETERIORATION
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CS DETERIORATION RELATIONSHIP
(Erosion - Scale Removal - Corrosive Fluid)
Removes
Mechanical Erosion
Micro-Machines
Away
CS Metal
Attacks & Corrodes
Protective Iron Sulfide
Scale
Exposes
Carbon Steel
(CS) Metal To
Corrosive Solution
Total Deterioration CS Metal Loss = Erosion Rate + Corrosion Rate + ErosionCorrosion Interaction Synergy (≈50%)
17
REGENERATOR UPPER
SECTION DETERIORATION
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BUILDING THE CASE FOR DETERIORATION
& FAILURE IN REGENERATOR

Discussion of following items will build case for
identifying actual causes of deterioration & failures
experienced at Trays 20 to 15 in Regenerator:
– Temperature depression at Regenerator’s Overhead
– Amine solution corrosiveness in Regenerator’s Upper
Section
– Droplet-impingement-erosion and particle-erosion of
protective iron sulfide scale and CS metallurgy
19
DETERIORATION & FAILURE IN
REGENERATOR (Temp Fluctuation)
L2Regenerator
Regenerator (53-C-201)
Temp(C)
(C)
OHDOHD
Temp
120.00
97 C
101 C
103 C
Temperature (C)
115.00
110.00
105.00
100.00
95.00
90.00
85.00
6-Jan-07
6-Oct-06
6-Jul-06
6-Apr-06
6-Jan-06
6-Oct-05
6-Jul-05
6-Apr-05
6-Jan-05
6-Oct-04
6-Jul-04
6-Apr-04
6-Jan-04
6-Oct-03
6-Jul-03
6-Apr-03
6-Jan-03
80.00
Date
•
•
Regenerator OHD temp depressed mid-Oct 04 (maybe related to
amine type conversion?) and increased mid-Oct 06 (maybe related to
amine reclamation?)
Thus, temperature at Trays 20 to 15 possibly depressed for 1 year
20
prior to time deterioration was noted (2005 inspections)
DETERIORATION & FAILURE IN
REGENERATOR (Temp Fluctuation)
L2Regenerator
Regenerator (53-C-201)
Temp(C)
(C)
OHDOHD
Temp
120.00
97 C
101 C
103 C
Temperature (C)
115.00
110.00
105.00
100.00
95.00
90.00
85.00
6-Jan-07
6-Oct-06
6-Jul-06
6-Apr-06
6-Jan-06
6-Oct-05
6-Jul-05
6-Apr-05
6-Jan-05
6-Oct-04
6-Jul-04
6-Apr-04
6-Jan-04
6-Oct-03
6-Jul-03
6-Apr-03
6-Jan-03
80.00
Date
•
•
Temperature depression would increase H2S solubility and solid iron
sulfide loadings in amine solution at Trays 20 to 15 level and make
this solution more corrosive and erosive
There was no available data that could be credibly used as a proxy
for H2S loading variability in amine solution at Trays 20 to 15 level21
DETERIORATION & FAILURE IN REGENERATOR
(Solution Corrosiveness, T-15)
CS CR w/ Scale at Regen (T-15) as a Function of H2S Conc & Temp
Ref H2S (0.7 mol %)
•
Ref Temp (121 C)
Carbon Steel CR (< 3 mpy, T-15) w/ scale present for up to 10X
Ref H2S concentration (0.7 mole %) regardless of temp
22
DETERIORATION & FAILURE IN REGENERATOR
(Solution Corrosiveness, T-15)
CS CR w/o Scale at Regen (T-15) as a Function of H2S Conc & Temp
Ref Temp (121 C)
Ref H2S (0.7 mol %)
Ref H2S (0.7 mol %)
•
Ref Temp (121 C)
Carbon Steel CR (28 mpy, T-15) w/o scale present at 4X
Ref H2S concentration (0.7 mole %) & lower temp (11523C)
DETERIORATION & FAILURE IN REGENERATOR
(Solution Corrosiveness, T-15)
CS CR w/o Scale at Regen (T-15) as a Function of H2S Conc & Temp
Ref Temp (121 C)
Ref H2S (0.7 mol %)
Ref H2S (0.7 mol %)
•
Ref Temp (121 C)
Comprehensive review into mechanisms responsible for
removing protective iron sulfide scale was thus required.
24
DETERIORATION & FAILURE IN
REGENERATOR (CFD Evaluation)

CFD was executed:
– to confirm if particle-erosion did contribute to
deterioration of protective iron sulfide scale and erode CS
metallurgy in downcomer areas
– to confirm if droplet-impingement-erosion was a
contributing factor in deterioration noted at vapor/ liquid
interface between trays
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DETERIORATION & FAILURE IN
REGENERATOR (CFD Evaluation)
Contours of velocity intensity at
the downcomer walls
Contours of particle-erosion rates
at the downcomer walls (kg/m3.s)
26
DETERIORATION & FAILURE IN
REGENERATOR (CFD Evaluation)
•
Parameter
Case 1
Case 2
Solids (Iron Sulfide) Concentration
wt.% in Rich Amine
1.0 %
2.0 %
CFD Max CS Erosion Rate Predictions
(mpy)
13
25
Max erosion rate in downcomer areas nearly double (13
→ 25 mpy) with increased solids loading (1.0 → 2.0%)
27
DETERIORATION & FAILURE IN REGENERATOR
(Erosion-Corrosion Deterioration Rate)
Tray
H2S %
Temp, C
CS CR
(mpy – w/ scale)
CS CR
(mpy - wo
scale)
Erosion
Rate
(mpy)
Synergy
(%)
Total1
Metal
Loss Rate
(mpy)
20 (H)
3.7
105
2.2
35.2
13
50
72.3
15 (M)
0.7
121
1.0
11.5
6.5
50
27
Note 1: Total Metal Loss (at reference values) = CS CR (wo/ scale) + ER + Synergy
Note 2: CS Erosion Rate (mpy) based on 1% solids
•
•
If protective scale is present, CR for CS low (< 3 mpy) for Trays
20-15, and erosion is not applicable
If particle-erosion and droplet-impingement-erosion is a factor,
protective scale is removed and there is erosion-corrosion
synergy contribution to total metal loss
28
DETERIORATION & FAILURE IN REGENERATOR
(Erosion-Corrosion Deterioration Rate)
•
Tray
H2S %
Temp, C
CS CR
(mpy – w/ scale)
CS CR
(mpy - wo
scale)
Erosion
Rate
(mpy)
Synergy
(%)
Total1
Metal
Loss Rate
(mpy)
20 (H)
3.7
105
2.2
35.2
13
50
72.3
15 (M)
0.7
121
1.0
11.5
6.5
50
27
Total metal loss rate (mpy) increases up Regenerator due to
lower temperatures, increase H2S concentrations, and higher
iron sulfide loadings as one proceeds up Regenerator:
-
-
Lower temperatures enable more H2S to dissolve in liquid
Higher H2S concentrations in liquid decrease pH and
increases iron sulfide loadings
The lower the pH of liquid, the more corrosive it is to
exposed metal
Higher the iron sulfide loadings, higher the erosion rate 29
CONCLUSION
30
CONCLUSION
•
In conclusion: Predictive indication and parametric
sensitivity studies (using CFD & Corrosion Simulation)
enabled us to significantly improve equipment reliability &
integrity management by:
-
determining equipment deterioration sensitivity to key
process parameters (i.e. H2S concentration increase,
iron sulfide solids loading)
-
predicting locations and magnitude of maximum metal
loss
-
proactively identifying operational parameter targets to
minimize deterioration
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Any Questions?
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