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Exploiting the Use of Compact HeatExchangers on Preheating Trains
(AIChE 2008 Spring Meeting 165d)
PETROBRAS R&D Center CENPES
Antonio V. S. de Castro*, M.Sc.
Alan T. Vilas BoasClaudio L. M. Kuboski
Diomedes C. da Silva, M.Sc.
Roberto A. Oliveira, M.Sc.Washington de O. Geraldelli, Ph.D.
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Introduction
Higher prices of energy and oilCrude oil distillation unit is one of thehighest energy consumers in a refinery.
Opportunities for heat integration:
In revamps to process advantageous
crudes Special Metallurgy higher heat recovery
Threats:
Special Metallurgy due to naphtenic acids- higher investments at preheating train
increase on plot area due to increase onheat recovery - might be a constraint
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Introduction
Compact Welded Plate Heat Exchanger: Special Metallurgy (Titanium, SMO, etc.)
leads to attractive costs compared to a S&T
Compact (less plot area)
Lower temperature approaches than S&T
Innovative solution Refinery designers don't have enough
information regarding the performance:
Fouling Mechanical resistance
Operational cautions, such as start-up and
shut-down
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PETROBRAS Experience
End of 2001, PETROBRAS Engineersvisited a Refinery, in Europe, where aCompabloc CP75 was installed
Overhead Condenser with Crude
Special Metallurgy required due toChloride
4 years without maintenance
August, 2002. Service with two heavy
fluids 13 exchangers at refinery since 1994
Maintenance during winter shut-down
Focus on Process Issues
Visit to refinery with two parallel units(one stand-by) Sep,2005
HVGO vs. Crude Oil (high temperature)
Problems during the start-up (blocked
pipe) Operating since November,2004
Ref.: ALFA LAVAL
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June,2002 ALFA LAVAL trained PETROBRAS
Engineers how to design Compabloc using CAS200(ALFA LAVAL software)
September,2006 Two-phase fluid ALFA LAVAL
course, concerning crude oil vaporization Lack of data for temperature x shear stress x fouling rate
May,2006 Visit to ALFA LAVAL factory in France:
- Maintenance/Inspection/Cleaning Requirements
- Manufacturing Process
PETROBRAS Experience
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P-68322A/B
Feed pre-heater
P-68323A/B
Ovhd Condenser
P-68324A/B
Ovhd Gas
Heater
P-68325A/B
Reboiler
PETROBRAS Cases
Sour WaterStripping Unit:
Feed preheater Overhead
Condenser
Ovhd Gas Heater
Reboiler
Plot areaconstraints
Fouling at Feedpre-heater
Leakage at OvhdGas Heater
CASE 1
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Fouling at Feed preheater
Inadequate H2S Stripping TowerOperation corrosion
Actual Flow Rate (90m3/h) Design (160m3/h)
Actual Shear Stress (22Pa) Design (60Pa)Mitigation:
Increase passes number ( Shear Stress)
Control Review (by-pass)
Self-cleaning Strainers
Leakage at Ovhd Gas Heater
Material replacement:From Titanium to SMO
PETROBRAS Cases
CASE 1, cont.
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Basic EngineeringDesign - Crude
Distillation UnitRevamp:
Increase FeedRate
Heat Integration
Plot AreaConstraints
3 Services: MVGO(2) and VR
220,000 bbl/d
Start-up: 2011
PETROBRAS Cases
CASE 2
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Conceptual Design
(Revamp)140,000 bbl/d
- MetallurgicalAdaptation(TAN=2.1)
- OperationalDebottlenecking
- Heat Integration
Study PinchAnalysis
- Plot Area and
Shutdown timeconstraints
- Full Compablocnew preheat trainsuggested.
PETROBRAS Cases
CASE 3
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Compabloc Test at Refinery
During conceptual design,necessity of a performancetest.
A Compabloc CP30 unit hasbeen installed, in order toevaluate the performance ofthis equipment under unit
conditions
Vacuum Residue preheatingCrude before the Desalter
Low Crude Temperature:~100 to 115C
Operational and
Maintenance experience
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Compabloc Test at Refinery
Vacuum Residue
E-106D
E-150
Crude Oil
103
113
172
160
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Compabloc Test at Refinery
Similar to phase 1.3 months100%6
b) Cleaning with hidroblasting.
a) Open the equipment to check deposits;Cleaning5
b) Equipment shut-down for 10 days and restart it.
a) Check pressure drop;Fouling2 months25%4
b) Auto cleaning capabity.
a) Check pressure drop;Thermal performance
and fouling
2 months100%3
if not, go to phase4.
b) if fouling, go to phase 1;
a) Check pressure dropFouling2 months50%2
b) Compare design X operational data using CAS200.
a) Check pressure drop;Thermal performance6 months100%1
(design basis)
ProcedureObjectivePeriodFlow rateStep
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Compabloc Test at Refinery
1st Phase Results: Crude side measured pressure drop was
from 29 to 47% of calculated values byCAS200;
VR side measured pressure drop was from123 a 167% of calculated values by CAS200;
Difference in global heat transfer coefficients(HTC) was much lower. Measured valueswere from de 88 a 111% of calculated valuesby CAS200;
Problems with Instrumentation could be thecause of such difference in pressure drop
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Compabloc Test at Refinery
Crude Inlet Vacuum Residue Inlet
Compabloc Opening after 1st step (8 months)
Deflected Baffle (mechanical resistance) it wasnot designed for that purpose
C
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Pressure drop results - phases 2, 3 and 4
Compabloc Test at Refinery
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
1-Sep 2-Oct 2-Nov 3-Dec 3-Jan 3-Feb 6-Mar 6-Apr 7-May 7-Jun 8-Jul 8-Aug 8-Sep 9-Oct
Period from 2006 up to 2007
pressuredrop,
kgf/cm
CRUDE
VACUUM RESIDUE
50% flow rate 25% flow rate 100% flow rate
C bl T R fi
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Compabloc Test at Refinery
Flow Rate Vacuum Residue vs CrudeAd-Hoc Trend
01/08/05 00:00:00 20/09/07 00:00:002.14 Year(s)
1210-FI-299
M3/D
1210-FI-298
M3/D
500
1000
1500
2000
2500
0
3000160.63
28.689
1210-FI-299
M3/D
1210-FI-298
M3/D
C bl T t t R fi
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Compabloc Test at Refinery
Positive Aspects:- Equipment kept its thermalperformance;
- Design, Operational and
Maintenance experience
- No fouling observed
Negative Aspects:
- Mechanical Resistance(Leakage and Baffle);
- Aspects not related to
exchanger (instrumentation,flow fluctuation, )
C bl T t t R fi
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Compabloc Test at Refinery
Crude Side
Period: Jul/16/07 up toSep/20/07
Zero Flow Rate forabout 3 weeks.
No abnormal pressurevariation.
Pressure
Flow Rate
Compabloc Test at Refinery
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Compabloc Test at Refinery
Vacuum Residue Side Period: 16/Jul/07 up to
20/Sep/07
Zero Flow Rate for 10 days. Significative pressure and
flow rate variation.
Pressure
Flow Rate
PressureSep/01 to 17
Compabloc Test at Refinery
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Compabloc Test at Refinery
Inlet Pressure VR vs Crude (Accordeon Effect)
Compabloc Test at Refinery
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Compabloc Test at Refinery
Problem Root Cause Consequense
Leakage Joint Failure Vacuum Residue Leakage
Baffle Deflection Overpressure or fatigue Thermal performance loss
ALFA LAVAL: Development of new gasket;
Adoption of reinforced baffles (for high viscous fluids);
PETROBRAS: Avoid surge pressure (hydraulic hammer):
Startup and shutdown procedures; Slow valve action;
Drain the equipment, in case of several days of shutdown.
Panels bolting hot retightening after startup Deposits prevention:
Strainers;
PETROBRAS Cases
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Basic Engineering Design (Oct/07)
Preheat Train before
Desalter Carbon Steel
Equivalent Cost
Preheat Train betweenDesalter and PreFlashTower
Crude Vaporization
Special Metallurgy
Parallel Arrangement
PETROBRAS Cases
CASE 3
PETROBRAS Cases
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Basic Engineering Design (Oct/07)After PreFlash Tower Preheat Train
(High Temperature Special Metallurgy)
SERVICE Shear (Pa) WALL TEMPERATURE (C)
E-166 A/B (x HVGO) 112 264
E-167 A/B (x HD) 113 289
E-169 C/D (x BPA) 113 295
PETROBRAS Cases
CASE 3
Petrobras Current Case
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CS
CS CS
CS AE
V
V
HT
HT
HT HT
HT
CB CB
Petrobras Current Case
CB CompablocCS Carbon Steel
HT High TemperatureAE accordion Effect
V Crude Vaporization
CASE 4 Basic Engineering Design CDU Grass root Refinery
PETROBRAS Current Case
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COMPARISON OF EQUIPMENT COSTS
SERVICE Compabloc (US$) Shell and Tube (US$)
P-10 x ~ 5.6 x
P-11 y ~ 3.8 y
* Installation costs not included;
* Equipment designed with the same allowablepressure drop;
* Compabloc design and budget by Alfa Laval;
* Shell and Tube budget by Aspen Icarus (Brazil
Base)
PETROBRAS Current Case
CASE 4 Basic Engineering Design CDU
Grass root Refinery
Compabloc Design
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Compabloc Design
Design Parameters:
Minimum Shear Stress
Higher Pressure drop
Countercurrent Pinch Analysis
Strainers / Maintenance facilities Parallel Arrangement (flexibility)
Accordeon Effect Crude Vaporization
High temperature
Next Compabloc Tests
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Next Compabloc Tests
Next Step at the same refinery:Operational practice and fouling at
high temperatures;
Service: Not defined yet;Wall temperature above 270C (target
300C)
Test at Case 2 refinery :
Operational practice and fouling withcrude vaporization;
Service: Not defined yet (desaltedcrude vs heavy diesel)
Crude Temperature from 150C to220C
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Thank you very much!
Antonio V. S. de Castro, [email protected]
Alan T. Vilas Boas
Claudio L. M. Kuboski
Diomedes C. da Silva
Roberto A. OliveiraWashington de O. Geraldelli
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