Calgary Symposium Plan 54

7/25/2019 Calgary Symposium Plan 54

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User Experience with Plan 54

Seal Flush System2007


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Presenters:

Michel Boutin: Machinery Engineer

Shell Scotford Refinery

Brad Hatton: Machinery Engineer

Shell Scotford Refinery


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Definition Plan 54

Pressurized external barrier fluid system

supplying clean fluid to the sealchamber. Circulation is by an externalpump or pressure source. Reservoirpressure is greater than processpressure being sealed.

API 682


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Plan 54

Clean

External

Source ofPressurized

Barrier Fluid

A PI Plan 54


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Overview - Scotford

Barrier fluid system is common to many

pumps in the unit. (12 Pumps with 15seals)

Finished product (ULSD) is the barrierfluid.

Control the barrier fluid pressure at 140

kPag (20psig) above the stuffing boxpressure.


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Overview (cont)

System pressure is maintained by amain pressure control valve on the skid.

Pressure control to each pump is by alocal control valve.

Flow control is maintained by arestriction orifice.

Cooling of barrier fluid is by an AirCooled Heat Exchanger


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Skid Details

The barrier fluid skid consists of:

2 IMO screw pumps

Air Cooled Heat Exchanger

Duplex Filters System reservoir


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Pump Details

Each pump has a local Pressure

Reducing Valve (PRV) to drop theheader pressure

One PRV for each pair of pumps Local Flow Indications to each seal.

Flow orifice located down stream ofeach seal


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Process P &ID


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Typical Pump P&ID


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Operating History

System was chemically cleaned and

flushed during commissioning Used milk pads at each seal to check

for cleanliness

Found three failed seals upon start up

Flow indicators showed high flows and

one was leaking to grade


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20V26CP2:LI20471.PNT

V2026 Barrier Fluid Reservoir

03/05/2006 12:00:00 AM 10/16/2006 12:00:00 AM224.96 days

10

20

30

40

50

60

70

80

0

100

62.4870

Reservoir Level History from Start-up


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Set points

Alarms were set on the flows to eachseal

High Flow was set@ 90% of instrumentrange (2X Normal flow)

Low Flow was set @ value from SealSupplier

Low Pressure Alarm set at 70 kPag (10psig) above stuffing box pressure.


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Set Points (cont)

Differential Pressure across the filters

High Temp Alarm (50C)

High Pressure Alarm on Reservoir.

High and Low Level Alarm on Reservoir


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Troubleshooting

Detecting small leaks on the inner sealis next to impossible. Trending on the

flows helps but small leaks are notdetectable.

Leaks on the secondary seal will showbarrier fluid on the pump

Trouble shooting guide for Operations

was generated


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Troubleshooting (cont)

Would need to systematically isolate the

spare pumps and trend the reservoir levelover a few days.

Since all seals leak in order to provide

lubrication we may not have a leak at all

Finished product (ULSD) is the barrier fluid

we are not contaminating the system


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Learnings From Start-up

Flushing of the system took longer than

expected even though it was chemicallycleaned and under an N2 blanket during

construction.

Remaining water in the skid from the

OEM was frozen and only after the

system was started up did the ice thawreleasing small debris into the piping.


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Learnings (cont)

We did not flush through each seal and had

to install a temporary jump-over to avoid

flushing debris thru the seal. The reservoir does not have a weir or baffle

plate. Suction to pumps is located on the

bottom. Future projects should have it on the

side or use a stand pipe inside.

No Source of heat for the fluid. Relying on theheat generated by the seals.


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Learnings (cont)

The piping run to each pump has a lot

of low points and high points. Shouldbe stream lined to push any vapour in

the piping up and though the seals.


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First Major Failure

Operators have been making entries into the

logs that this system has been operating

poorly from Nov 21 Dec 5, 2006 during acold snap

December 5th, 2006 after an extended cold

snap, local ambient temperatures rose above

0oC

First indication of trouble was the loss ofsystem pressure the morning of Dec 5th.


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First Major Failure (Cont)

IMO pump started to cavitate

Operators started the spare, believingthat the first pump failed.

Filter differentials on the skid were

erratic. Barrier Fluid usage as indicated by the

level in the surge vessel had not beenthe same as it had been in the past.


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Fluid sample from the surge vessel was

the first indication that there was a largeamount of water in the system.

System contents was drained, and filled

at the same time to purge the system of

water.

Second pump quickly showed signs offailed internals.


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Reservoir Level Leading up to Failure



10/01/2006 12:00:00 AM 12/10/2006 12:00:00 AM70.04 days

10

20

30

40

50

60

70

80

0

100

61.8730


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E2014 BARRIER COOLR TO HDR



S2022A/B BARRIER FILTERS

20E14CP2:PC20411.MEAS

kPag

20E14CP2:PC20411.OUT

%

20E14CP2:PC20411.SPT

kPag

20E14CP2:PDI20472.PNT

kPa

Supply to Pumps

12/05/2006 12:00:00 AM 12/06/2006 12:00:00 AM24.00 hours

500

1000

1500

2000

2500

0

3000

0

100

0

3000

0

100

-0.1155

31.6277

0.0000

31.6277

System Pressure Failure Trend


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System Pressure Failure Trend




S2022A/B BARRIER FILTERS

20E14CP2:PC20411.MEAS

kPag

20E14CP2:PC20411.OUT

%

20E14CP2:PC20411.SPT

kPag

20E14CP2:PDI20472.PNT

kPa

Supply to Pumps

12/05/2006 8:00:00 AM 12/05/2006 10:00:00 AM2.00 hours

500

1000

1500

2000

2500

0

3000

0

100

0

3000

0

100

6.1878

1408.6914

0.0000

1408.6914


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Process Unit was shutdown, to preserve

critical equipment. Two teams were set up. One to repair

and flush the system, the other to

investigate the failure.

Being a new unit, the system had

functional instrumentation


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Major Findings from First Failure

One seal that was not designed for the full

Plan 54 system pressure

Failed one seal before the major incident.Pump is in water service. Analysis showed it

had a reverse pressure event.

Failed another seal in water service. It had

been suspected a procedural error in

checking for leakage during the first event.


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Major Findings

No way to tell when there is water in thesystem.

No easy way to drain water from thesystem.

Circulation pump selection is acceptablefor a clean system, but did not take inaccount for off design conditions.

EHT was not considered in the project


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Pump Seal Failure in Water Service


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Pump Seal Failure in Water Service


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Proposed Post Failure Changes

Installation of a water boot

Installation of a conductivity detector forwater

Proposed new pump to handle high

levels of water

Working to remove one water pump

from the system (H2S Levels)


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Implemented Post Failure Changes

Developed Procedure to test individual

pump seals for integrity before start-up.

Complete spare pump now on the shelf.

PM plan to replace pump and inspect.

EHT being installed at low points.


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Minor Failure in May 2007

Circulation Pump pressure started to fall, and

operators detected water in the system again. Immediately started to conduct an online

flush of the system to save the second IMO

pump.

P-2005 (Sour Water from Driers) was

suspected leaking water into the Barrier FluidSystem, as the water was clean.


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Removed seal from pump did not indicate afailure of the seal.

Had the revelation that the barrier systempressure was too low for the P-2005s

Pumps were rebuilt shortly after start-up, and

after the initial barrier pressure survey. Stuffing box pressure was higher than the set

pressure for the barrier fluid.

Adjusted barrier pressure from 1250 kPa to1800 kPa.


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P2005A/B BARRIER FLUID

P2005A/B BARRIER FLUIDP2005A/B BARRIER FLUID

P2005A BARRIER FLUID

P2005B BARRIER FLUID

20P05CP2:PC20551.MEAS

20P05CP2:PC20551.OUT

20P05CP2:PC20551.SPT

20P05CP2:FI20549.PNT


P2005A/B Sour water

05/14/2007 3:12:32.363 PM 05/21/2007 4:12:32.363 PM7.04 days

500

1000

1500

0

2000

0

100

0

2000

0.3

0.6

0.3

0.6

0.4921

0.5514

1800.0000

31.4801

1801.4902


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After the set pressure change, no major

water excursions have occurred.


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P-2008 Vacuum Pump Seals

ANSI style seal, limited stuffing box

size.

Moved to a TiC/SiC seal face

combination due to initial seal failuresduring start-up.


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August 29 30, 2007 Operation

Numerous Stop Starts on both pumps.

Started another rapid loss of level in the

surge drum, greater that what we haveseen in the past.

Barrier fluid flow was not that muchhigher than what it was in the past.

Decided to swing to P-2008A and

isolate P-2008B


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September 5, 2007 Operation

Isolated P-2008B and the level in the

surge drum stabilized.

Maintained operation of P-2008A


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V2026 BARRIER FLUID DRuM


%


08/28/2007 11:40:57.985 AM 09/11/2007 12:40:57.985 PM14.04 days

20

30

40

50

60

70

80

0

100

84.4665


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P2008A BARRIER FLUIDP2008B BARRIER FLUID


P2008A LIQ RINGRUN STAT

P2008B LIQ RINGRUN STAT

20P08CP2:PC20561.MEAS

kPag

20P08CP2:PC20561.OUT

%

20P08CP2:PC20561.SPT

kPag


Am3/h


Am3/h

20P08CP2:XI20734.CIN

20P08CP2:XI20735.CIN

P2008A/B Vacuum

08/28/2007 11:44:26.677 AM 09/11/2007 12:44:26.677 PM14.04 days

200

400

600

800

1000

0

1200

0

100

0

1200

0.2

0.5

0.2

0.5

0

2

0

2

0

1

-0.0004

-0.0002

232.0000

68.2035

238.2031


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08/07/2007 12:00:00 AM 11/05/2007 12:00:00 AM90.04 days

10

20

30

40

50

60

70

80

0

100

65.7390

Present Operation of the Reservoir Level


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Present Water Status in the System.

We are still building water in the system

The rate of water build up is very slow.

The water is not sour, which indicates

possibly three sources of water.


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October 11th Sample


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October 29th Sample


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Barrier Fluid Skid


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Local Pump Control


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Local Pump Control


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Barrier Fluid Skid

EHT/T W f Wi t


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EHT/Temp Wrap for Winter

EHT @ P 2014A


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EHT @ P-2014A

Fl I di ti S t


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Flow Indication Setup

O ifi L ti


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Orifice Location

Pi i @ P 2005


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Piping @ P-2005

C t l St ti @ P 2008


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Control Station @ P-2008

Fl I di ti @ P 2008


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Flow Indication @ P-2008

Outlet Piping @ P 2008


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Outlet Piping @ P-2008

Outlet Piping from V 2021


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Outlet Piping from V-2021

Temperature Bypass on Skid


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Temperature Bypass on Skid

IMO Pump Orientation


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IMO Pump Orientation

System Pressure Control Station


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System Pressure Control Station


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End of Presentation

Documents

Calgary Symposium Plan 54