BP Amoco ThermalStability AdditiveDevelopment: An Update

S E Taylor, BP Amoco Oil

Content

• Basis of approach

• Laboratory testing

• Large-scale testing– thermal stability tests– filter/water separator single-element tests– engine test

• Future

BP Amoco developmentobjectives

• To understand how thermal degradation takes place,and how additives may interact in such processes

• To understand the function of dispersant and anti-foulant additives which show beneficial effects onthermal stability

• To identify and develop new, commercially viablethermal stability additives without compromisingother aspects of fuel quality

Fuel thermal degradation

• Depending on temperature, main factors are– fuel chemistry– oxygen– metals

• Factors combine to form deposit precursors

• Precursor reactions lead to– bulk deposits– surface deposition

⇒ Multifunctional additive with activity in several aspects

Approaches taken

• Identifying/developing performance test procedures– UK MoD, USAF, OEMs (Rolls-Royce)

• Identifying ‘active’ species– In-house (BP Chemicals’ proprietary) additives

• provided performance baseline– Small chemical species

• identification of specific molecular functionalities

• Building required functionality into ‘host’ molecules

• Developing scaled-up synthetic routes to patentedcommercial products

Additive concept

Multifunctional molecule

Multifunctional molecule

“Performance by Design”

PS

DiDeMDAO

Fuelsolubility

Increasedwater reaction

AO = Anti-oxidancy

Di = DispersancyDe = Detergency

MD = Metal deactivationPS = Precursor stabilisation

Specificfunctionalities

Additive concentration (mg/l)

MS

ep v

alu

e

50

60

70

80

90

100

0.1 1 10 100 1000

Effect on water separation

Workingconcentration

• Small effect on Microsepat “working concentration”

• Full spec testing of Jet A1fuel shows no change in1B water reaction rating

• Jet A1 Microsep slightlyreduced (typically 98!90)

Optimisation of synthetic routeBulk deposits from flask tests

0

20

40

60

80

100

120

140

Bu

lk d

ep

osi

t m

ass

(mg

/l)

Candidate additive

Bas

e fu

el

JFTOT/Ellipsometeranalysis

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60

Distance from fuel inlet (mm)

Dep

osi

t th

ickn

ess

(nm

)

Fuel

JP8 fuelAluminium tubeT = 335oCNo additive

3.5 hours

+ additive5 hours

Optimisation of synthetic routeSurface deposits from JFTOT

0

100

200

300

400

500

600

700

Candidate additive

Su

rfac

e d

ep

osi

t vo

lum

e/f

uel

vo

lum

e (

pp

b)

Base fuel >> 700 ppb

T = 335oC5 hours

Performance in different fuelsBulk deposits from flask tests

0

10

20

30

40

50

60

70

80

90

100

Bu

lk f

ilter

able

dep

osi

t (m

g/l

)

Base fuel

+ additive

T = 180oC5 hours

Fuel

A B C D D (USAF data)

Extended test programme

• THERMAL STABILITY– Extended Duration Thermal Stability Test (EDTST)– Reduced Scale Fuel System Simulator (RSFSS)– Aviation Fuels Thermal Stability (AFTS) test– Spey 202 bed engine test

• WATER SEPARATION– Single element tests (API 1581 3rd Edition

elements)

• MATERIALS COMPATIBILITY

• HSE ISSUES

0

5

10

15

0 10 20 30

EDTST: Pre-heater deposits

Section number

Ca

rbo

n d

ep

osi

t (µ µµµ

g c

m-2

)

T = 204oCActive recirculation 96 hours

POSF-3219 (JP8)

POSF-3166 (JP8)

Data courtesy of USAF

EDTST: Heater deposits

0

50

100

150

200

250

300

350

400

450

500

0 10 20 30

Section number

Ca

rbo

n d

ep

osi

t (µ µµµ

g c

m-2

) T = 260oC

POSF-3219 (JP8)

POSF-3166 (JP8)

JPTS

Data courtesy of USAF

Rolls-Royce AFTS data

250

300

350

400

450

500

0 50 100 150Time (h)

No

zzle

inn

er w

all t

emp

erat

ure

(oC

)

340oC

- additive

- additive

+ additive

+ additive

300oC

**Carbon burnoff resultsawaited**

Deposit rate comparison

0

0.5

1

1.5

2

2.5

3

3.5

4

250 300 350 400

Ra

te o

f T

IW r

ise

(oC

h-1

)

Inner wall temperature (TIW) (oC)

Base fuel

+ additive

Single element testconditions

• Base fuel:– 96 WSIM; conductivity 2 pS m-1

• Fuel additive composition for categories M and M100conditions:– 2.0 mg l-1 Stadis 450

– 15 mg l-1 DCI-4A

– 0.4 mg l-1 Petronate L

– 0.2 vol% FSII

– +/- BP Amoco additive @ 137 mg l-1

• Flow rate = 29 US gal/min• Solids holding @ 133 mg/US gal 90% Ultrafine test

dust ISO 12103-1 + 10% Copperas RIO R9998; +stop/start procedure

49 WSIM and 509 pS m-1 conductivitywith 4 additives51 WSIM and 378 pS m-1 conductivitywith 5 additives

0

40

80

12

0

16

0

20

0

24

0

DP

Free water (A)

Free water (KF)

Solids (x10)

Single element test results

0

5

10

15

20

0 10

20

30

40

Wat

er c

on

cen

trat

ion

(p

pm

),ef

flu

ent

so

lid

s c

on

cen

trat

ion

(m

g l-

1)

or

DP

(p

si)

Time on stream (min)

4-additivebase fuel

+ BP Amoco thermal stability additive

0.26 mg l-1 solids

15ppm free water

Spec. limits

* * * * * * * * *

* = start/stop procedure

Conductivity data

0

100

200

300

400

500

600

0 50 100 150 200 250

Eff

luen

t co

nd

uct

ivit

y (p

S m

-1)

Time on stream (min)

+ BP Amoco thermal stability additive

0.01%water

3%water

Test solids@ 133 mg/USgal

+ 0.01%water

+ 3%water

Pre-additive conductivity

}//

//// //

Single element tests

Carried out using API 1581 3rd Edition elements withmulti-additive fuel composition (FSII, SDA, CI/LI andPetronate L) and 90:10 Ultrafine:RIO

• Water coalescence only marginally affected by presenceof additive– slightly smaller droplets released– no sign of “graping”

• Good solids retention in presence and absence of water

• No excessive ∆P

Spey 202 emissions trial

• Ex-RAF Rolls-Royce Spey 202 engine

• F34 base fuel with/without additive

• 33 x 1-hour Accelerated Simulated Military EnduranceTest (ASMET) cycles:

• Measurements– Exhaust gas emissions– Laser obscuration– Exhaust gas infra-red

Specification conformance

TEST Base fuel Base fuel +additive

Comments

JFTOTbreakpoint (oC)

285 >340 Increase

Water reaction 1B 1B No change

Microsep 98 91 Slight reduction

Conductivity(pS m-1)

240 100 Reduction

• Full specification tests– confirmed negligible impact on Joint Fuelling

System Check List requirements for Jet A1

Summary

• The first specifically designed thermal stability additive

• Thermal stability performance at least matchingoriginal USAF JP8+100 criteria

• Minimal impact on water coalescence/solids filtrationusing standard API specification elements

• Cost-effective product

Next steps

• Completion of thermal stability performance evaluation

• Completion of filtration and coalescence testing– Current technology products– New developments

• Materials compatibility programme

• HSE issues

• Flight trials

RAF USAFRolls-Royce Pratt & Whitney