INCREASING PLANT RELIABILITY INCREASING PLANT RELIABILITY & INTEGRITY MANAGEMENT & INTEGRITY MANAGEMENT USING CFD & CORROSION USING CFD & CORROSION

SIMULATION SIMULATION

Regan Pooran, P.Eng. Regan Pooran, P.Eng. VP-SPEC TECHNOLOGIES INCVP-SPEC TECHNOLOGIES INC..

VP - SPEC Technologies Inc.

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TOPICS OF DISCUSSIONTOPICS 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

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WHO ARE WE? WHO ARE WE?

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VP-SPEC TECHNOLOGIES INC VP-SPEC TECHNOLOGIES INC BACKGROUNDBACKGROUND

• 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…

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PURPOSE, PROCESS, PAYOFFPURPOSE, PROCESS, PAYOFF

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PURPOSE, PROCESS, PAYOFF PURPOSE, PROCESS, PAYOFF

• Key Purpose:

• To demonstrate how CFD (Fluent Inc., CFD Modeling ) & Corrosion Simulation (OLI Systems, Corrosion Analyzer) are applied synergistically to improve Plant Reliability & Integrity Management.

• Process:

• 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 Management

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THE TRADITIONAL & THE TRADITIONAL & THE IMPROVED PERSPECTIVE THE IMPROVED PERSPECTIVE

FOR ASSET INTEGRITY FOR ASSET INTEGRITY MANAGEMENT MANAGEMENT

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TRADITIONAL PERSPECTIVE 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

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AN IMPROVED PERSPECTIVE 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.

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REVIEW OF PROBLEMS WITHIN REVIEW OF PROBLEMS WITHIN AN AMINE SYSTEMAN AMINE SYSTEM

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AMINE SYSTEMS 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.

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AMINE SYSTEM FLOW SCHEME AMINE SYSTEM FLOW SCHEME

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REVIEWED SAMPLE CASEREVIEWED SAMPLE CASE

• Specific real world sample case in review: Deterioration of an Amine Regenerator from Trays 20-15 (Upper Section)

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DETERIORATION OF REGENERATOR DETERIORATION OF REGENERATOR TRAYS 20-15TRAYS 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

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DETERIORATION OF REGENERATOR TRAYS 20-19 DETERIORATION OF REGENERATOR TRAYS 20-19 SECTION (ILLUSTRATION – W/ DESCRIPTION)SECTION (ILLUSTRATION – W/ DESCRIPTION)

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ACTUAL CAUSE ANALYSIS:ACTUAL CAUSE ANALYSIS: REGENERATOR DETERIORATION REGENERATOR DETERIORATION

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CS DETERIORATION RELATIONSHIP CS DETERIORATION RELATIONSHIP (Erosion - Scale Removal - Corrosive Fluid)(Erosion - Scale Removal - Corrosive Fluid)

Mechanical ErosionRemoves Protective Iron Sulfide

Scale

Corrosive Solution

Exposes Carbon Steel (CS) Metal To

CS MetalAttacks & Corrodes

Total Deterioration CS Metal Loss = Erosion Rate + Corrosion Rate + Erosion-Corrosion Interaction Synergy (≈50%)

Micro-MachinesAway

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REGENERATOR UPPER REGENERATOR UPPER SECTION DETERIORATIONSECTION DETERIORATION

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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

BUILDING THE CASE FOR DETERIORATION BUILDING THE CASE FOR DETERIORATION & FAILURE IN REGENERATOR& FAILURE IN REGENERATOR

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L2 Regenerator (53-C-201) OHD Temp (C)

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101 C 97 C 103 C

Regenerator OHD Temp (C)

DETERIORATION & FAILURE IN DETERIORATION & FAILURE IN REGENERATOR (Temp Fluctuation)REGENERATOR (Temp Fluctuation)

• 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 prior to time deterioration was noted (2005 inspections)

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L2 Regenerator (53-C-201) OHD Temp (C)

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101 C 97 C 103 C

Regenerator OHD Temp (C)

DETERIORATION & FAILURE IN DETERIORATION & FAILURE IN REGENERATOR (Temp Fluctuation)REGENERATOR (Temp Fluctuation)

• 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 level

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DETERIORATION & FAILURE IN REGENERATOR DETERIORATION & FAILURE IN REGENERATOR (Solution Corrosiveness, T-15)(Solution Corrosiveness, T-15)

Ref H2S (0.7 mol %)Ref Temp (121 C)

CS CR w/ Scale at Regen (T-15) as a Function of H2S Conc & Temp

• Carbon Steel CR (< 3 mpy, T-15) w/ scale present for up to 10X Ref H2S concentration (0.7 mole %) regardless of temp

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DETERIORATION & FAILURE IN REGENERATOR DETERIORATION & FAILURE IN REGENERATOR (Solution Corrosiveness, T-15)(Solution Corrosiveness, T-15)

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 (115 C)

CS CR w/o Scale at Regen (T-15) as a Function of H2S Conc & Temp

Ref H2S (0.7 mol %)

Ref Temp (121 C)

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DETERIORATION & FAILURE IN REGENERATOR DETERIORATION & FAILURE IN REGENERATOR (Solution Corrosiveness, T-15)(Solution Corrosiveness, T-15)

Ref H2S (0.7 mol %)Ref Temp (121 C)

• Comprehensive review into mechanisms responsible for removing protective iron sulfide scale was thus required.

CS CR w/o Scale at Regen (T-15) as a Function of H2S Conc & Temp

Ref H2S (0.7 mol %)

Ref Temp (121 C)

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DETERIORATION & FAILURE IN DETERIORATION & FAILURE IN REGENERATOR (CFD Evaluation)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 DETERIORATION & FAILURE IN REGENERATOR (CFD Evaluation)REGENERATOR (CFD Evaluation)

Contours of particle-erosion rates at the downcomer walls (kg/m3.s)

Contours of velocity intensity at the downcomer walls

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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

DETERIORATION & FAILURE IN DETERIORATION & FAILURE IN REGENERATOR (CFD Evaluation)REGENERATOR (CFD Evaluation)

• Max erosion rate in downcomer areas nearly double (13 → 25 mpy) with increased solids loading (1.0 → 2.0%)

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• 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

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

DETERIORATION & FAILURE IN REGENERATOR DETERIORATION & FAILURE IN REGENERATOR (Erosion-Corrosion Deterioration Rate)(Erosion-Corrosion Deterioration Rate)

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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

DETERIORATION & FAILURE IN REGENERATOR DETERIORATION & FAILURE IN REGENERATOR (Erosion-Corrosion Deterioration Rate)(Erosion-Corrosion Deterioration Rate)

• 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

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CONCLUSIONCONCLUSION

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CONCLUSIONCONCLUSION

• 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?Any Questions?