Attachment 2 

Presentation Slides 

HOVENSA Refinery Fuel Oil Burning – Explanation and Limitations of NOX Production 

Vince D’Ippolito, HOVENSA 
HOVENSA Refinery Fuel Oil Burning

Explanation and Limitations of NOx Production

Vince D'Ippolito

4/17/09

Saint Croix, VI
"

HOVENSA

HOVENSA Fuel Oil Burning

YiIlv does HOVENSA burn fuel oil (No. 6 Oilll

1. Refinery is located on an island - no natural gas pipeline

2. Fuel gas produced at the refinery is less than energy required

3. Majority of fuel gas at the refinery is produced by 2 units: FCC and Coker

60% of total refinery fuel gas production

4. HOVENSA uses all the fuel gas it produces

5. Excess light gases (H2, off gas, etc.) must be disposed in the refinery fuel gas

system. Includes process upsets with units that use H2 as a reactant and

unplanned shutdowns of heaters.

6. Not practical to store fuel gas in refinery or on island

7. Refinery propane production is not sufficient to handle fuel gas system changes

8. Coker fuel gas production is not constant - varies by as much as 200/0 in 1 hour

every day due to the normal Coker process

9. Daily variation in fuel oil usage can be 1% to 40% of total fuel consumed in the

refinery depending on operating units

1% =refinery fuel consumers are reduced

400/0 =FCC/Coker planned or unplanned shutdown

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HOVE'NSA

HOVENSA Fuel Oil Burning

Oil flame

Oil Vs. Gas Firing

Gas flame

Heaters have multiple burners - crude unit has 2 heaters with 18 burners in each

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HOVENSA

HOVENSA Fuel Oil Burning

Conventional fuel gas and oil combination burner

REGEN

TILE

PIWT (; IS

..

,.

r

. .-4-- SECONDA

RYTlLE

-IIEI TfN

l?F:PR.·lr'TORl'

" III

J -sn:.L\1 (.Y.S,)

n-;:::L.D 011, (P. S. )

Side View Top View (looking down in heater)

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HO\IEN'SA

HOVENSA Fuel Oil Burning

Conventional fuel gas and oil combination burner

REGEN

TILE ']...-- SECONDA L: RYTILE

m:.1 TER

REFR.lCTORr

r

PILOT (; IS

r

IIR

I STE.lJI (\.8.)

n='1=n OIL IVS,)

Side View

Burner before heater installation

Oil Tip

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HO\IENSA

HOVENSA Fuel Oil Burning

Conventional fuel gas and oil combination burner

Gas Tip Oil Tip

Total number of holes and hole size different for each fuel type

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HOVENSA

HOVENSA Fuel Oil Burning

Wb.Y does HOVENSA burn fuel oil and fuel gas in the same heater?

1. Fuel gas production is not a constant rate each day or during the day:

A. Small variations in feed composition to FCC and Coker can result in large

changes in fuel gas production

B. Coker unit is a cyclical unit with fuel gas production variation

C. Feed rate changes occur to fuel gas producers: FCC and Coker

D. Fuel gas production and composition varies because of day-night air

temperature variation: propane composition changes in fuel gas system

E. Fuel oil permit limits on units are less than total fuel required

2. Only select heaters have permits to burn fuel oil

3. Switching burners from oil to gas requires step processing to prevent surging the

refinery fuel gas system pressure and releasing fuel gas into the flare system

Occurs at sunset/sunrise every day, when refinery units are shutdown/started, or

as a result of large throughput changes

Oil/gas burner switching must be done carefully to prevent heater stack smoking

Successful control of fuel system requires concurrent burner switching across

multiple units

SWitching burners from oil to gas fuel is best handled by same heater operator

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HOVENSA

HOVENSA Fuel Oil Burning

WIlY does HOVENSA require heater burners that can "co-fire" oil or Q!l§1

"co-fire" means that the burner can either use oil or gas without switching the burner

or adding burner parts, but is not used to fire both fuels at the same time at

HOVENSA. Some burners in the heater will operate on oil and some will operate

on fuel gas.

1. All of the burners are in operation at all times - can not have idle burners

2. When a burner is removed from service or not used:

A. heater is less efficient due to air leakage through out-of-service burner - uses

more fuel

B. flame height of the remaining burners becomes higher - potential to touch

overhead tubes or tube support failure.

C. flame stability decreases - flame close to heater sides causing tube support

failure, tube overheating/failure, tube coking

D. distribution of heat in the heater is uneven - can causing heater tube coking

3. Fuel gas system is dynamic requiring flexibility for the burners to be switched

quickly - can not change out "gas only" or "oil fired only" burners quickly

4. Individual heaters/units can be shutdown for maintenance - limits the quantity of

fuel oil burners available for fuel gas swings

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HOVENSA

HOVENSA Fuel Oil Burning

w!!y doesn't HOVENSA use "emergency back up oil gun" burners?

"emergency back up oil gun" means that the burner normally burns fuel gas, but can

burn oil by either:

A. adding the oil fired part to the burner while it is in service - switching

fuels requires maintenance modification of the burner

B. the burner manufacturer has added an oil fired part to a gas only design

Oil and gas are not fired at the same time

1. HOVENSA does not use this type of burner

2. Fuel gas system requires quick and frequent fuel system changes to many burners

3. Advanced knowledge of the gas to oil switching timing is needed to schedule

workers to remove/add the oil parts.

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iiOVEN5A

HOVENSA Fuel Oil Burning

What would be required to have oil specific and gas specific burners in each of the

process heaters that burns fuel gas and fuel oil?

1. Total number of burners would have to be increased by approximately 1000/0

2. Heaters would have to be re-designed and re-built

Cabin style heaters:

Heater would have to be lengthened

Internal heater tubes would have to be lengthened

Outside structures (pipe, piperacks) would have to be moved

Burner manufactures would set burner spacing for NOx guarantee

Cylindrical heaters would have to be demolished and re-built

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· HO\IEN"SA

HOVENSA Fuel Oil Burning

Questions

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