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Page 1: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

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Page 2: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

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Page 3: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

KINETICS OF HYDROLYSIS OF EMULSIFIED

SALTS IN CANADIAN BITUMENS AND

INHIBITION OF HYDROLYSIS

Murray R Gray1, Harmeet Kaur1 and

Paul E Eaton2

1. Dept of Chemical and Materials Engineering,University of Alberta

2. Champion Technologies, Houston, Texas

Page 4: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Summary

Salt hydrolysis in upgraders and refineries

Past studies of hydrolysis

Methodology

Factors that accelerate and inhibit hydrolysis

Kinetics of hydrolysis reactions

Page 5: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

How do salts react in refinery processes?

! Salts in crude oil react with steam:

NaCl + H2O = NaOH + HCl

CaCl2(s)+H

2O(g) = CaOHCl(s)+HCl(g)

MgCl2(s)+H

2O(g) = Mg(OH)Cl(s)+HCl(g)

! Extent and rate of reaction varies as:

Mg(40-49%) > Ca >> Na (<1%)

Page 6: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Problem Areas in Refinery Crude Units

Salts Contained in

Crude Charge

NaCl, CaCl2, MgCl2

Un-reacted

Chlorides @ 300o C

Naphtha

LAGO

HAGO

Steam

Gas

To Vacuum Tower

Acidic Water

Hydrolysis Occurs

150oC-350oC

HCl Formation, Fouling,

Overhead Corrosion

Desalter

150o C

Atm

Twr

Page 7: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Temperature,oC

100 200 300 400 500 600

Chlo

ride r

ele

ased,

%

0

20

40

60

80

100

Syncrude plant data

MgCl2.6H

2O hydrolysis

CaCl2 and NaCl hydrolysis

Hydrolysis in Upgrading Processes

Data from Syncrude Canada Ltd for Chlorine balances on process units

(Diluent Recovery Unit through to Fluid Coking Unit)

8% of Cl in Brine

salt is in

MgCl2 .6H2O

Page 8: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Effect of Crude Oil Impurities

Decomposition of CaCl2 .2H2O

Cumulative Chloride evolved in overhead condensate (%

Initial)

Nature of

salts

No

additive

With naphthenic

acid (1 wt%,

36 meq/L)

With

Kaolinite

Solid Salts 0.14 2.02 -----

Emulsified

Salts

2.59 ----- 5.87

Page 9: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Issues with Chloride Hydrolysis

Corrosion /reduced life of refinery

equipment

Salt fouling in columns leading to plugging

Contamination of downstream processes

Premature shutdown and significant safety

issues.

Page 10: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Crude Oil Desalting

Page 11: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Paraffinic froth treatment

Emulsions stabilized by asphaltenes and fine particles

Add n-alkane rich solvent to give flocculation of asphaltenes with water droplets and fine clays

Yields clean, dry bitumen

Yield penalty from asphaltene removal

Hexane condensate S/B=1.5

Page 12: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Are these solutions effective?

Desalting of heavy oils removes only 90-95% salts.• small difference in density makes this process less

effective

• presence of solids and stable water in oil emulsions further retard the effectiveness of the operation

• inoperable for with high solids bitumen from mining

Paraffinic froth treatment reduces the yield of bitumen

Addition of bases tends to cause deposits and fouling

Page 13: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Hydrolysis Procedure

Oil media

! Model Oil - Paraflex

! Husky - Cold Lake Lloydminster blend, chloride content-

76ppmw

! Western Canada Select with chloride content of 53ppmw

Method

! Salt mixture added as a 10% solution in water.

! Nitrogen sparged at 300 std ml/min to maintain positive

pressure.

! Steam supplied at the rate of 2 ml/min (liquid basis).

Non-Isothermal

Hydrolysis-10ml of condensate

samples collected at 50°C

intervals between 100°C-300°C,

at 320°C and 350°C.

Isothermal Hydrolysis-15ml of

condensate samples collected at

250°C .

Page 14: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Hydrolysis apparatus

Page 15: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Hydrolysis in

Bitumen Blends

Oil + Mixed Brine Salts

Hydrolysis to 350o C

[Kaur, 2008]

• Model oil

• Husky Cold Lake +

Lloydminster blend

• WCS = Western Canada

Select

Ch

lori

de R

ele

ase (

% In

itia

l)

0

2

4

6

8

10

12

Total Salt Concentration (ppmw)

0 200 400 600 800 1000 1200 1400

0

2

4

6

8

10

Husky

WCS

Model oil

Model oil

Page 16: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Factors causing abnormal behaviour

Acids can accelerate release of Cl

“Natural inhibitors” can delay release

Acceleration Inhibition

Combination

Page 17: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Profile of Chloride hydrolysis during rising

temperature test C

hlo

rid

e R

ele

as

e(%

in

itia

l)

0 .0

0 .2

0 .4

0 .6

0 .8

1 .0M O D E L O IL

0 .0

0 .5

1 .0

1 .5

2 .0 H U S K Y

W C S

T e m p e ra tu re

1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0

0

1

2

3

4

D e la y d u e to in h ib it io n

D e la y d u e to in h ib it io n

Oil + Mixed Brine Salts

Hydrolysis to 350o C

Page 18: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Cl

Rl

0

10

20

30

40

50

60Western Canada Select

Model oil

NaCl CaCl2.6H2O MgCl2.6H2O

Pure Salts

Contribution of individual chloride saltsC

um

ula

tive

Clre

lea

se

, %

Stepwise temperature increase from 150-350oC

Page 19: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Images from SEM analysis of solids from

CaCl2 hydrolysis

Initial Solids Solids after experimental run

WCS with added calcium chloride, steamed at 150-350oC

Page 20: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Possible role of Naphthenic Acids

" Suggested Reaction Equation:

# CaCl2.2H2O (s) +2NapH (l) Ca (Nap)2 (l) + 2HCl (g)

# G is positive, but continuous stripping of HCl (g) drives

reaction

" Objective:

# Determine quantity of CaCl2.2H2O needed to consume

naphthenic acids

# Is % hydrolysis reduced when salt is in excess?

Page 21: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Naphthenic acid accelerates Cl release

Salt Concentration(ppmw)

500 1000 1500 2000 2500

Cu

mu

lative C

l re

lea

se

(%

initia

l)

0

5

10

15

20

25

Nap Acid excess CaCl2.2H2O excess

WCS, TAN = 0.86 mg KOH/g oil, steamed at 150-350oC

Page 22: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

What are Inhibitors?

Natural or added agents that reduce HCl release from the hydrolysis of chloride salts atelevated temperatures .

Addition of divalent inhibitor provides reactive metal bases in the oil to react with the HCl, forming stable salts like metal-hydroxychloride.

Example for Mg:

Mg(OH)2 (s) + HCl (g) = Mg(OH)Cl (s) + H2O(g)

Mg(OH)2+2NapH = Mg(Nap)

2+ 2H

2O

Mg(OH)2+2HCl = MeCl

2+ 2H

2O

Page 23: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Effectiveness of inhibitors with increasing

temperature

Temperature, oC

150 200 250 300 350

Cum

ula

tive C

l re

lease,

%

0

1

2

3

4

5

6Base

Ca overbase

Ca(OH)2 slurry

Inhibitor A

Inhibitor B

WCS with 576 ppm

of mixed salts

Inhibitors added

at 1:1 to salts

Page 24: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Effectiveness of Inhibitors in WCS with pure CaCl2.2H

2O

under isothermal conditions at 250oC

Time for 50%

total Cl release

B a s e C a s e

C u m u l a t i v e T i m e ( m i n s )0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0

No

rma

lize

d r

ate

of

Cl

rele

as

e,

min

-1 x

1000

0

2

4

6

8

I n h i b i t o r B

0

2

4

6

8

I n h i b i t o r A

0

2

4

6

8

1 0

O v e r a l l H y d r o l y s i s

4 8 %

O v e r a l l H y d r o l y s i s

3 0 %

O v e r a l l H y d r o l y s i s2 0 %

Page 25: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Kinetics of Cl release

ConditionInitial Rate Constant

(k, min-1

)

Base Case 4.31 x 10-03

Calcium Overbase 1.01 x 10-05

Ca(OH)2 Slurry 9.05 x 10-05

Inhibitor A 1.02 x 10-05

Inhibitor B 2.03 x 10-05

WCS with NaCl -87.5% and MgCl2.6H2O -12.5%

Apparent first-order kinetics at 250oC

Page 26: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Effectiveness of inhibitors under isothermal

conditions at 250oC

Additives Overall

Recovery(%

Initial)

Time for 50%

recovery

Overall

Inhibition

Base Case 1.23± 0.12 10

Calcium

Overbase

1.04 44 23

Calcium

Hydroxide Slurry

1.00 46 26

Inhibitor A 0.13 44 90

Inhibitor B 0.12 17 91

WCS with NaCl + MgCl2 mixture added

Page 27: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Effect of inhibitor dosage

Inhibitor Inhibitor: Salt

(mass)

Cl release (%

Initial)

2:1 0.12

1:1 0.13 Inhibitor A

0.5:1 0.79

2:1 0.11

1:1 0.12 Inhibitor B

0.5:1 0.1

Mixed Salts (NaCl -87.5% and MgCl2.6H2O -12.5%) in WCS at 250 C

Page 28: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Average

Ca/Na-0.029

Ca/Cl-0.015

Average

Ca/Na-0.18

Ca/Cl-0.096

Base Case Calcium Hydroxide Slurry Inhibitor

Physical interactions of Inhibitors with NaCl +

MgCl2

Page 29: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Conclusions

Hydrolysis strongly influenced by impurities in

crude oils

! Naphthenic acids

! Clays

! Natural inhibitors

Naphthenic acid component increases

hydrolysis from CaCl2.2 H2O

Added inhibitors associate with salt crystals

to reduce extent and rate of HCl release.

Page 30: geoscan.nrcan.gc.ca · How do salts react in refinery processes?! ... naphthenic acids # Is % hydrolysis reduced when salt is in excess? Naphthenic acid accelerates Cl release

Acknowledgements

Funded by Champion Technologies and

Natural Sciences & Engineering Research

Council (NSERC)

Tuyet Le

Yissella Londono

Fausto Marelli

Lisa Boddez

Alvin Kim


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