High TAN

High High TANTAN Crude and Crude and

Its ProcessingIts Processing

CNOOC REFINING & MARKETING GROUPHUIZHOU REFINERY

May 2010

Wu Qing

Table of ContentsTable of Contents

�� 11、、High TAN Crude: resourcesHigh TAN Crude: resources、、properties and acidproperties and acid

distributiondistribution

�� 22、、Problems existing for high TAN crude processingProblems existing for high TAN crude processing

�� 33、、Design and operation of CDU for high TAN crude processing Design and operation of CDU for high TAN crude processing

�� 44、、Operation performance assessmentOperation performance assessment

2CNOOC REFINING CO.,LTD.


�� 55、、Problems existing in current unit and improvement solutions.Problems existing in current unit and improvement solutions.

�� 66、、ConclusionConclusion

11、、 High High TANTAN crude: resourcecrude: resource、、properties and distributionproperties and distribution

1.1 High TAN crude :resources

High TAN crude category：� Acid crude oil：acid number＞0.5mg KOH/g

� High TAN crude ：acid number＞1.0mg KOH/g

� High TAN、 low sulfur、 heavy crude oil—there are five main oil fields of this kind

of crude oil in four continents

� High TAN 、high sulfur 、heavy crude oil—from Venezuela、California USA

High TAN、 low sulfur 、heavy crude oil distribution

� In Europe，is mainly represented by the North Sea crude oil at northwest Europ；

� In America，is mainly represented by Brazil Marlim crude oil；


� In America，is mainly represented by Brazil Marlim crude oil；

� In Africa，is mainly represented by West Africa Kuito and Sultan（Fula、Dar Bland）；

� In Asia，is mainly represented by China Bohai sea crude oil (such as Penglai crude oil)

High TAN crude yield during the year of 1998－2004

Year

North

Europe

(kb/d)

America

(kb/d)

West Africa

(kb/d)

Far East

( kb/d)

Total

(kb/d)

1998 510 910 100 770 2290

1999 580 1160 110 770 2620



1999 580 1160 110 770 2620

2000 600 1415 170 770 2955

2001 630 1675 200 795 3300

2002 725 1815 255 795 3590

2003 765 1875 265 805 3710

2004 740 1935 475 805 3955

1.2.Main charateristics of typical high TAN crude oil

Crude oil LiuhuaXinjiang pipleline transfer

Duli Hange Kuitu Penglai 19-3 Liaohe Duoba MalinDa blended crude oil

Density g/cm3 20℃

0.9208 0.907 0.921 0.8829 0.9283 0.9276 0.9338 0.9309 0.9326 0.9

Solidificationpoint ℃

-8 -17.5 10 ＜-20 ＜-20 -32 3 -13 -8.1 38

Viscosity mm2/s50℃

67.96 100.8 179.5 14.64 54.83 97.91 509.4 141.9 78.62 23.7

Residual carbon %

6.7 4.75 7.61 5.28 6.54 6.11 8.98 5.47 6.78 7.7

Sulphur % 0.243 0.131 0.221 0.661 0.691 0.32 0.2 0.16 0.68 0.11

N ppm 2569 - 2235 2538 4439 3000 4700 1874-2300 3700 3370

Acid number 1.12 4.51 1.4 0.51 1.9 3.57 2.12 3.55-5.05 1.27 3.68


5CNOOC REFINING CO.,LTD. * Content of gel + asphalt

Acid number mgKOH/g

1.12 4.51 1.4 0.51 1.9 3.57 2.12 3.55-5.05 1.27 3.68

Asphalt % 4.12 5.42 1.63 1.55 1.19

Resine % 16.56 12.58* 19.14 12.19 28.34 17.7* 18.54* 19.87 16.98*

Wax % 6.37 13.55 1.51 1.52 6 7.5 10.36 2.92

Metal analysis ppm

Fe 2.45 12.51 7.89 14.16 11.02 6.92

Ni 5.68 9.8 36.61 8.41 41.96 31.34 46.6 7.13-10.53 16.6 60.63

Cu 0.04 0.34 ＜0.03 ＜0.03 0.03 0.16

V 0.41 0.42 1.43 14.46 39.12 1.17 0.17 0.13-0.62 24.7 1.06

Ca 11.5 12.22 0.33 1.18 199.33 5.77

Mg 1.28 1.78 ＜0.03 0.47 2.42 0.62

Pb 0.12 1.55 ＜0.10 ＜0.10 0.18 ＜0.10

Na 8.24 8.34 1.02 13.63 2.92 41.94

As ＜0.10 0.81 ＜0.10 ＜0.10

Salt mgNaCl/L 67.8 15.6 9.8 38.2 130 3.2 179 17.4

Watson K 11.7 12.25 11.85 11.9 11.65 11.85 12.2

Crude typeLow sulphur heavy content medium base

Low sulphur naphthene meidum

base

Low sulphur heavy content medium base

Low sulphur medium content medium base

Sulphur contained heavy content medium

base

Sulphur contained heavy naphthene

medium base

Low sulphur naphthenic

base

Low sulphur heavy content medium base

Sulphur contained heavy

content naphthenic base

Low sulphur medium content paraffin base低

Light yield % 26.77 21.83 44.75 34.72 20.33 21.5

Total yield % 63.92 51.19 72.07 67.1 54.18 48.1

Features of high TAN crude :

�Low crude oil API 、 high density（most of them is

higher than 0.93kg/m3）、high viscosity，

the content of asphalt and gel are especially high；

�High TAN (Total Acid Number, for instance, Penglai19-3’s

acid value is 3.57mgKOH/g），but most of them are of

comparatively low sulphur content)；

�Low solidification point；



�Low solidification point；

�High TAN crude oils generally have higher nitrogen

content；

�High TAN crude oils have higher content of heavy

metals；

�High TAN crude oils have low yielding rate of light oil

distillation.

No. Boiling point range ℃

Occupation in crude oil%（m/m）Density g/cm3

(20℃)

Solidification

point℃

Acid degreemgKOH/100mL

Acid NumbermgKOH

/gWatson K

Each fraction Total yield

1 ＜80 0.49 0.49 0.7288 3.77 11.3

2 80～100 0.57 1.06 0.7389 1.26 11.7

3 100～120 0.87 1.93 0.7536 1.89 11.7

4 120～145 1.25 3.18 0.7723 6.29 11.6

5 145～170 1.72 4.90 0.7947 24.53 11.5

6 170～200 2.27 7.17 0.8247 63.96 11.3

7 200～235 3.78 10.95 0.8516 116.6 11.2

PL19-3 crude TBP( true boiling point) distillation and narrow fraction’s watson K1.3 High TAN crude oil distribution



7 200～235 3.78 10.95 0.8516 116.6 11.2

8 235～250 1.95 12.90 0.8671 230.7 11.2

9 250～275 3.67 16.57 0.8766 304.5 11.2

10 275～300 3.51 20.08 0.8791 395.9 11.3

11 300～320 3.29 23.37 0.8776 471.4 11.5

12 320～350 5.23 28.60 0.8946 470.6 11.5

13 350～360 1.65 30.25 0.9036 <-40 6.19 11.5

14 360～395 5.72 35.97 0.9096 -30 5.74 11.5

15 395～425 5.67 41.64 0.9166 -14 4.34 11.6

16 425～450 5.74 47.38 0.9342 -10 2.68 11.6

17 450～475 6.27 53.65 0.9347 -6 2.26 11.7

18 475～500 5.06 58.71 0.9347 2 3.23 11.8

19 500～520 3.25 61.96 0.9323 6 3.94 12.0

20 520～545 3.80 65.76 0.9352 24 4.16 12.1

21 ＞545 34.24 100


Sample nameAcid degree/Acid number

mgKOH/100mL /mgKOH/g

Penlai19-3 crude oil Cao FeiDian crude oil

Atmospheric

Typical acid number (or degree) of different draws from CDU for offshore crudes


Atmospheric

overhead

gasoline

0 0

Acid degreeAtm draw 1 228.69 2.05

Atm draw 2 404.44 22.82

Atm draw 3 553.77 149.98

vacuum draw 1 5.88 1.45

Acid valuevacuum draw 2 5.79 2.89




高酸原油酸值分布图

6

8

10

12

14

酸值

，

mgKOH/g

Acid number

High TAN crude : acid number distribution diagram


0

2

4

0 100 200 300 400 500 600

Boiling point，℃

Penglai 19－3－2 crude oil

Penglai 19－3－4

Kazakhstan

Kelamayi No.1 Sultan Fulan2a Sultan Fulan2b

Shan jiashi Xinjiang blended crude oil

Acid number









�� 55、、Problems existing in current unit and improvement Problems existing in current unit and improvement

solutions.solutions.


2 2 、、Problems existing in high Problems existing in high TANTAN crude oil processingcrude oil processing

High TAN crude oil’s typical properties、process challenges and solutions

Material’s typical

pollutantsProcess challenges Solutions

High content of filterable solidsFouling\Foaming\Desalting efficiency\Environmental

protection

Storage tank dewatering\Desalting（listed as process challenge） \Process scale inhibitor\Waste

water treatment

High water contentDesalting\Product quality\Corrosion\Foaming\Energy

consumptionStorage tank dewatering\desalting（same as above） \ Tower overhead corrosion control

High salt content Corrosion\Fouling\Desalting\Catalyst poisoningStorage tank dewatering\desalting（same as above） \ Tower overhead corrosion control \Process

scale inhibitor


scale inhibitor

High content of organic chloride Corrosion\ HDS catalyst poisoning Tower overhead corrosion control \ HDS reactor bed treatment

High acid content

（Total acid value，naphthenic acid

value）Corrosion（containing water and high temperature） Tower overhead corrosion control \High temperature corrosion control\material upgrading

High sulphur content（H2S and

mercaptan）Corrosion\Product quality\Transportation、storage and

safetyTower overhead corrosion control\ H2S trapping agent

High metal load

（Ca、Hg、 Fe、Se…）Fouling\Catalyst poisoning\Product quality\ SH&E Remove impurities in desalting unit\Process scale inhibitor\Waste water treatment

High content of Ni/V Catalyst poisoning\ FCCU operation FCCU metal inactivation plan

Raw material poor compatibility Fouling\Desalting\Energy consumption Process scale inhibitor

Upstream additives Fouling\Foaming\Desalting\Corrosion\ WWTPStorage tank dewatering\Desalting（same as above） \Tower overhead corrosion control\工艺Process

scale inhibitor\Waste water treatment

Potential problems in high TAN crude oil processing

Problem areas Problem description

Tank area • Sump oil in tank increase • Tank volume decrease

Electric

desalting tank

• Oil entrainment in drainage water • High water content in desalted crude oil

• Emulsion layer thickness increase • Treatment capacity decrease

Tower

overhead

corrosion

• Tower overhead organic acid corrosion increase • Tower overhead salting

increasing trend

Heat

exchanger

• Fouling increase trend in heat exchanger system • High energy consumption



exchanger

system

废水处理 • 问题较多，见下图所示：

Waste To

Centrifuge

High solid

content

High

grease

Equal. API

High

grease

Waste To

Belt PressHigh solid

content

Metal discharge

exceeds limit

such as Hg, Se ect,

High

CODHigh

organic

acid

High

ammonia/

nitrogen

DAF

DAF

Clarifier


Main problems lie in CDU and sewage water treatment system

Except the huge risks associated with high temperature corrosion, Huizhou refinery CDU has other problems such as increasing amount of sump oil, waste water treatment system difficulties and constrain issues in crude oil sole refining and mixed refining. The graphic below shows existing problems and their locations other than product quality control issue, these locations include tank area、electric-desalting tank、heat exchanger system、overhead system、wastewater treatment system etc.

Overhead


Crude oil tank

area

Electric-

desalting tank

Electric-desalting

drainage

Waste water

treatment system

Heat exchanger system

High acid crude oil processing problems scheme

2.1 High temperature naphthenic acid (NA) corrosion and its effect

High temperature naphthenic acid corrosion mainly happens under temperature of High temperature naphthenic acid corrosion mainly happens under temperature of 200℃ above especially 220℃、and at the equipment parts which have closely contact with naphthenic acid, the most seriously corroded part is the vacuum distillation column system of atmospheric and vacuum distillation system (including vacuum heater、transfer line、 vacuum draw 3、 vacuum draw 4 、vacuum tower feeding line and below part 、internal structure parts etc)

� High naphthenic acid corrosion consists of the following 4 main steps:

� Naphthenic acid molecules are transferred onto metal surface

� Being adsorbed on the metal surface

� React with surface active centre



� React with surface active centre

� Desorption of corroded substances

� NA corrosion is heavily influenced by temperature. The corrosion at low temperature is not strong. Once in boiling state, especially in high temperature anhydrous environment, the corrosion will be the strongest. Most of the high temperature naphthenic acid corrosions happen in liquid phase, but if naphthenic acid is condensed at gas phase, the gas phase corrosion may happen and the corrosion extent will be influenced by acid value. In addition, the corroded substances Fe(RCOO)2 is oil dissolvable which are formed from the direct reaction between high temperature naphthenic acid and metal surface or iron sulfate membrane. It can be easily dissociated from metal surface and carried away by oil, new nude metal surface is exposed and result in new corrosion furthering into metal. For this reason the metal surfaced corroded by naphthenic acid is very smooth and clean without dirt. After long time contact with naphthenic acid, flushing by the acid stream, the metal surface will form special observable corroded grooves or traces (high speed acid stream will form same directional sharp groove lines, while the low speed acid stream will form corrosion pits with sharp edges), these are symbols used to identify this kind of corrosion with other corrosions.


� High temperature NA corrosion influence factor——Temperature

� <200 ℃：in anhydrous case，no corrosion；

in water environment the corrosion will increase with increasing

temperature；

� 270～280℃：reach the acid boiling point, also the most serious corrosion；

� 350～400℃：due to the high temperature melting of FeS membrane，together

with the elemental sulphur discomposed from crude oil sulphides, the

corrosion on metal equipments becomes violent enhanced by the interaction


between naphthenic acid、elemental sulphur and H2S.

� >400℃：oil acid is decomposed, corrosion is weakened; At the place where

naphthenic acid is thermally decomposed, there will be formation of low

molecular mass organic acid or CO2, which have effect on condensate

water’s corrosivity.


3

4

5

6

7

8

腐蚀速

率(mm/a)

316L

0Cr13

Cr5Mo

20G


The corrosion assessment of 316L、0Cr13、Cr5Mo and 20G(25m/s) in Penglai

19-3 crude oil

0

1

2

3

250 270 290 310 330 350

温度(℃)

腐蚀速

率

20G

Corrosion rate

Temperature

� High temperature NA corrosion influence factor——Flow Velocity and Flow Regime

� There are heavy corrosions in equipment’s elbows、tee joints and the turbulent flow area in pumps.

� The included angle between media flow direction and metal wall（0-900）also heavily influence the naphthenic acid corrosion（bigger angle will result in bigger media impact force and hence heavier corrosion ）

� If flow’s gas content is higher than 60%, and the

gas stream speed is highe than 60m/s，the

corrosion speed of some equipments such as

furnace tubes、elbows、vacuum distillation

transfer line etc may increase about two order



transfer line etc may increase about two order

of magnitude.

� Under certain temperature，there is a critical

velocity for some materials which is between

material’s corrosion speed in crude oil and flow

velocity. If the flow velocity is lower than this

critical value, naphthenic acid corrosion

speed will be very low.

The generally controlled flow velocity is：

for carbon steel <25-30m/s，

SUS316<120m/s(no turbulent flow)

Effect sketch of flow rate and flow regime on corrosion

� High temperature NA corrosion influence factor——Acid Molecular

Weight and Acid Distribution

� Acid value doesn’t directly show the naphthenic acid corrosivity performance; And there is no

proportional relation between them.

� But as for high acid crude oil, its acid value is used for describing its corrosivity.

� Naphthenic acid of light molecular weight needs lower activation energy during reaction with

metals, and it is higher activity at low temperature, hence result in heavier corrosion;

Naphthenic acid of heavy



Naphthenic acid of heavy

molecular weight needs higher

activation energy during

reaction with metal, and it is of

lower activity at low temperature.

� High acid crude oils from

different area are of different

acid distribution, hence they

have difference on corrosivity,

and also the difference on

absolute corrosion speed. 235-360℃、360-450℃ and 450-524℃ distillate’s corrosion rate to carbon steel

Corrosion rate

Temperature

� High temperature naphthenic acid crude (NAC) corrosion influence factor——Crude oil Type

High acid crude oils from different areas have difference on their acid distribution and also the difference on their corrosivity. Take SS300 stainless steel for example, the corrosivity of Penglai 19-3 crude oil、Beijiang crude oil and Lvda-10 are different, the inflection point temperature of these three high acid crude oils are 300℃ around、300-310℃ and 310-320℃ respectively，and their corrosivity are definitely different, for sample material, its corrosion speed in these three oils at temperature of 330℃ are 1mm/a around、0.4mm/a around and 0.3mm/a around respectively.



these three oils at temperature of 330℃ are 1mm/a around、0.4mm/a around and 0.3mm/a around respectively.

� NAC corrosion influence factor——Material

The corrosivity sequence on the material from strong to weak is as follows：20G、Cr5Mo、0Cr13、Cr18-8、00Cr17Ni14Mo2. This is mainly because the different content of alloys in above alloy steel.

� NAC corrosion influence factor——Others

Even with very low sulphur content, naphthenic acid is still of heavy corrosion, it is because there is no formation of protective sulphide film; but sulphur can reportedly reduce corrosion at its content of 2-3%.

2.2 Low temperature corrosion issue resulted from high

temperature high acid crude oil’s electric desalting difficulties

High acid crude oils are generally of higher density and viscosity, especially the issues of higher

content of asphalt and gel, which will result in increased difficulties in electric desalting. Furthermore, the

naphthenic acids and their salts are of strong emulsibility, which may bring difficulties to crude oil

desalting, make it harder to meet deep desalting requirement, the low temperature part of distillation unit

overhead （≤120℃）will be heavily corroded.

H2S-HCl-H2O type corrosion



H2S-HCl-H2O type corrosion

Corrosion at low temperature area is of the same corrosive mechanism as atmospheric & vacuum

distillation low temperature corrosion. The corrosive mechanism is that: after the crude oil desalting

and dewatering, there are still some non-organic salts like calcium chloride、magnesium chloride、sodium chloride existing in desalted and dewatered crude oil, the organic chloride additives added

in some oil fields during the crude oil deep extraction may form HCl under certain conditions，the

corrosions will mainly happen in primary tower overhead and atmospheric tower overhead (top 5

trays and their above), also the tower overhead condensate cooling system, of distillation unit, then

followed by vacuum tower overhead. The main influence factors are：Cl-、pH value. The low Cl-

concentration will result in slight corrosion，high Cl-content will result heavy corrosion. Lower pH

value will result in heavier corriosion, while over high pH value（〉8.0）will easily result in

condensing system fouling and further the corrosion under fouling.

Corrosions resulted from acetic acid added during high acid crude oil extraction and formic acid &

acetic acid decomposed from crude oil itself.

Corrosions resulted from acetic acid

�照片2芯子补焊及堵管情况

�照片1试压时芯子泄漏情况


�照片3减二及减一中泵入口壳体腐蚀情况

�照片2芯子补焊及堵管情况

Ca Naphthenate Debris


Collected from V703A bottom Collected from V702 water leg

Naphthenate deposit found in a heat exchanger Naphthenate deposit found in an electrical Desalter

Corrosion of Small Molecular Acid

Table 1 corrosion of different organic pure acids to carbon steel Table 1 corrosion of different organic pure acids to carbon steel


图图1 1 乙酸注入后对设备和管线腐蚀的影乙酸注入后对设备和管线腐蚀的影

响响

Fig.2 the corrosion effects of acetic acid contents for the X-65 steel in the water solution at different temperature


Table 2 the effects of corrosion for N80 Steel and PH vaule varies of HAc concertration Table 2 the effects of corrosion for N80 Steel and PH vaule varies of HAc concertration

2.3 Corrosion resulted from high nitrogen content in high acid crude oil

High acid crude oil is of higher nitrogen content, the main three types of corresponding corrosion are as follows：

1） H2S-HCN-H2O type corrosion on catalytic cracking tower overhead and absorb stable tower

H2S-HCN-H2O type corrosion happens under the temperature range of 40-50℃，damage of carbon steel will be thickness even reduction、hydrogen blistering and sulfide stressed corrosion cracking；damage of austenitic stainless steel will be sulfide stressed corrosion cracking.

2） NOx-SOx-H2O type corrosion in catalytic cracking regenerator、tertiary cyclone etc



cyclone etc

During catalytic cracking catalyst regeneration process, nitride will be converted to NOX，and will result in NOx-SOx-H2O type corrosion (so-called “Niter Embrittlement” in low temperature area of catalytic cracking regenerator、tertiary cyclone etc, such as the cranidium, when the raining weather or wet ambient form the nitric acid dew point. This is the main course of accident happened in catalytic cracking unit regenerator of domestic refineries.

3）Pipeline blocking and corrosion under fouling resulted from the accumulation of ammonium chloride and ammonium hydrogensulfide in hydrogenation low pressure air cooler.

After hydrogenation on raw materials, the elemental nitrogen in nitrogen contained compound is converted to ammonia, NH3 、 HCl and H2S react in distillates heat exchanger to form NH4Cl and NH4HS，these salts, due to their low solubility, will accumulated on equipment surface and result in blockage in hydrogenation high & low pressure air coolers 、heat exchanges and pipelines and further the corrosion under fouling.

2.4 High acid crude oils are of high salt content and metal content

Higher metal content in crude oil especially the Calcium、Nickel、Vanadium，will mainly influence secondary processing units, such as catalytic cracking、hydrogenation，and will result in catalyst posioning and/or permanent inactivation、catalyst bed blocking and high temperature heat exchanger fouling and coking etc. If the residuum is used as fuel oil, then corrosion of furance tubes and heavy ash accumulation on furnace tube surface will happen which will influence heater’s heat efficiency and operation safety.

2.5 Product quality issues：

First is how to realize aviation kerosene smoke point and cetane number indicator,

Second is the high nitrogen content makes it difficult to store the oil products under higher stability



Second is the high nitrogen content makes it difficult to store the oil products under higher stability standard.

Because the straight-run naphtha content in high acid heavy content crude oil is usually lower, at the time of oil shortage, the problems will happen with alternative crude oil: the alternative is hard to match either the atmospheric load of atmospheric & vacuum distillation, or the reforming load.

2.6 Envrionmental protection：

Another big headache of high acid crude oil processing is the sewage water treatment

There is high acidic organic substances in the organic content which can be extracted from sewage water (it occupies over 90% of the total extractable organic content). Acidic organic substances from different sewage不water source are different. By calculation, final outlet naphthenic acid’s contribution to COD should be 30% above, most of the molecular weight are 300 around, and they are basically C18 liked naphthenic acids.


Crude oil

tank

Oil type

PH COD mg/l

Ammonia/Ni

trogen

mg/l

Oil mg/lSulphide

mg/l

Electrical

conductivit

y us/cm

Volatile

phe

nol

mg/l

212-T-02 Jilaso 6.8 2230 161.0 33.8 6.8 32500 16.0

Weizho

Huizhou refinery: some crude oil tank area’s dewatering sewage water main characteristics（August 2009）


212-T-04Weizho

u6.8 2720 213.5 44.4 3.5 23500 6.1

212-T-4Weizho

u7.4 3700 355 73.6 3.4 42800 5.7

212-T-1 Dalia 7.6 5350 255 106.8 21.8 35200 9.6

211-T-4 Dalia 7.3 4200 129.0 52.3 5.4 1.0

212-T-3 Hange 7.5 4660 119 85.6 4.5 2.1


Salty drainage water acidic organic content total ion spectrum(TIC)



Salty drainage water alkalic organic content total ion stream spectrum(TIC)


33、、 Design and operation Design and operation of CDU for high TAN crude oil processingof CDU for high TAN crude oil processing(take Huizhou refinery as example)(take Huizhou refinery as example)

3.1 Special topic research of high TAN crude oil processing

� We have cooperated with research and design institutes of both domestic and international, carried out crude oil

assessment、demulsifier selection and electric desalting operation condition analysis、anti-corrosion mechanism

and material selection、corrosion process analysis、detection and monitor system analysis，scientific assessment

and risk identification on all potential problems existing in high acid crude oil processing. To guarantee safe、environment protective long period operation, we formulated “Material selection guidance for high acid crude oil

equipments (trial)” etc technical documents, together with correct solutions to supplement the design, implemented

the solutions in construction.

Features of high TAN crude oil Implemented measures

Due to crude oil’s high density and viscosity, the electric desalting

emulsification will be more serious, oil water separation will be more difficult,

and the high content of asphalt and gel in high acid crude oil will increase

Equipment：electric desalting tanks are design as 3 levels, level 1 is high velocity level, level 2 & 3 are

low velocity tanks specially designed back flush facilities inside the electric desalting tube

Process： carry out small and media scale tests

Some measures taken according to high TAN crude oil characters


and the high content of asphalt and gel in high acid crude oil will increase

emulsification, and result in low working efficiency of electric desalting tank,

and the problem of oil entrainment in water.

Process： carry out small and media scale tests

add in dewatering and demulsifying agents, supplement reverse

demulsifier on the basis of existing demulsifier.

Environmental protection：special treatment

High density crude oil also contains higher solid particles and suspended

substances, which may result in fatlute accumulation at electric desalting tank

bottom, and fouling blocking in heat exchanger.

Equipment：supplemented installation of deoiler behind electric desalting tanks

Process： timely add in antisludging agent、dispersants or carried out washing；change operation mode

Environmental protection aspect ：special treatment

Both high temperature corrosion and low temperature corrosion will be very

heavy

Equipment：carry out corrosion mechanism analysis, to research corrosion of different materials in

different type acid contained crude oils under corresponding process unit conditions,

formulate “Equipment material selection guidance for high acid crude oil equipments ”,

select materials according to this guidance, install corrosion probes and coupons;

measure thickness at specific points

Process： add high temperature anti-corrosion agent into system

monitor the effectiveness of applied anti-corrosion agent

chemical test analysis system

High acid crude oil has higher content of salts and heavy metals which may

result in catalyst poisoning in secondary processing units、catalyst bed

blocking and the fouling & coking in high temperature heat exchanger

Enhance monitoring of secondary processing units

Chemical added-agents

High acid crude oils are generally naphthenic based or middle-paraffin based

oils, and of higher nitrogen content, which is a big challenge to aviation

kerosene smoke point、diesel cetane number and oil color.

Use correct hydrogenation and catalyticcracking technologies


3.2 Electric desalting and atmospheric & vacuum distillation unit

Problems Solutions

High salt content in crude

oil

3 levels tanks design

12 million tons/year Huizhou refinery electric desalting unit sketch


High density、viscocity

Electric desalting tank design operation temperature 139℃

High acid value、oil

entrainment in

drainage water

Install deoiler behind electric desalting tank, together with specially designed back flush

structure

Desalting efficiency to be lower

Increase reverse demulsifier、dispersent，

crude oil dewatering demulsifier、desalter’s

process injection system，agile water injection、

12 million tons/year Huizhou refinery electric desalting unit sketch

Huizhou refinery 12million tons/year atmospheric & vacuum distillation unit process sketch


Huizhou refinery 12million tons/year atmospheric & vacuum distillation unit process sketch

2rd vacuum cut outlet unit

Vacuum overhead oil outlet unit

Vacuum overhead gas to F-102

Blended diesel to tank area (cold material)

Blended diesel to middle cracking (hot material)

1st atm cut to tank area (cold material)

1st atm cut to tank area (cold material)

Atm overhead oilcut to reforming

Atm gas to F-101Atmospheric towerAtmospheric tower

Stripping tower

Steam


Vacuum residuum to coking

Crude oil from

tank area

4th vacuum cut outlet unit

3rd vacuum cut outlet unit

Flashing tower

Blended diesel to tank area (cold material)


ItemMonthly

planPlanned

yielding rateActual processing

amountActual yielding

rate

Input Crude oil 137500 127933

Self made fuel gas

206 0.15% 192 0.15%

Atmospheric overhead

6133 4.46% 5174 4.04%

Kerosene 8786 6.39% 6645 5.19%

Blended diesel oil

26469 19.25% 20824 16.28%

Vacuum

Atmospheric & vacuum distillation unit virgin start up (original) material balance

Atmospheric & vacuum distillation unit


Output

Vacuum overhead oil

336 0.24%

2rd vacuum cut 23554 17.13% 19020 14.87%

3rd vacuum cut 20048 14.58% 16103 12.59%

4th vacuum cut 5225 3.80% 5190 4.06%

Vacuum residue 47080 34.24% 48395 37.83%

Light sump oil 500 227 0.18%

Heavy sump oil 1500 1694 1.32%

Total output 123464 96.51%

Light yielding 30.34% 32643 25.52%

Total yielding 65.85% 73148 57.18%

Oil residues in system pipeline

4405 3.44%

Processing loss 64 0.05%

Atmospheric & vacuum distillation unit


3.3 Equipment material selection (Metallurgy) and corresponding

supervising & monitoring system

Huizhou refinery 12 million tons/year atmospheric & vacuum distillation unit is designed for the

crude oil with acid value of 3.57mgKOH/g，sulphur content of 0.28～0.3%. In order to supply

qualified and approved materials to downstream units, and guarantee 4 years long period

operation, we have formulated “high acid crude oil equipment material selection guidance”.

� Main process pipeline material selection principle (Metallurgy)


� Main process pipeline material selection principle (Metallurgy)

1）For media of 220℃ lower temperature，use carbon steel.

2）For media of 220℃≤ temperature＜288℃，it is recommended to use material of 1Cr5Mo、1Cr9Mo、

0Cr19Ni10Ti、00Cr17Ni14Mo2（SS316L material in this plant are all required for 2.5 more Mo content）.

3）For media of 288℃ higher temperature，recommended material is 00Cr17Ni14Mo2 austenitic stainless

steel.

4）For media of temperature ≥ 220℃ and flow velocity ≥ 30m/s，recommended option is 00Cr17Ni14Mo2

austenitic stainless steel.

5）For big diameter pipeline, recommended option is the rolling pipes made by composite material of carbon

steel --00Cr17Ni14Mo2 stainless steel.

6）Should the media flow velocity and regime be monitored, as for the area and part which deem to be

heavily washed, shall the big radius elbows and slot branching tee joints be applied there.


Monitor methods

� Corrosion probe monitoring

There are totally 17 probes installed in different positions of atmospheric & vacuum distillation unit

� Test analysis and monitoring

Sample name Analysis item Performance indicator

Crude oil tank、prior desalting、1st desalting 、 2rd desalting 、desalted crude oil

Salt content、water content、metal content、acid value、sulphur

Tank area dewatered crude oil’s water content≤0.5%、salt content after electric desalting≤3mgNaCl/L、water content after


� Thickness measuring and coupons fixed at specific points

content、 desalting≤0.2%、removal rate of organic metal ions of Ca,Fe,Mg ,Na etc(excluding Ni,V)≥70%

Electric desalting drainage water Oil contained、PH Oil content in drainage water≤200ppm Drainage water pH: 6-8

Sewage water from atmospheric overhead and vacuum overhead

Fe ion、Cl ion、H2S、NH4、PH、strong acid

Fe ion ≤1mg/l、probe corrosion rate: ≤0.2mm/y、PH value:5.5-7.5

Atmospheric overhead oil、vacuum overhead oil、2rd atmospheric cut oil、3rd atmospheric cut oil、2rd vacuum cut oil、3rd vacuum cut oil、4th vacuum cut oil、vacuum residuum

Acid value、S content、Fe content、Ni content

Fe≤1mg/L、probe corrosion rate≤0.2mm/y

Code Position Type

Pipe diameter

Pipe material

Material flow t/h

Design temperature C

101-AE-01101Before feed pressure control valve of

flashing towerContinuous high temperature resistor

with P5 coupon 600 304L 1428 224

101-AE-01201Atmospheric overhead oil gas

volatilization lineContinuous low temperature inductor

with CS coupon 900 CS 65 118

101-AE-01401 After E-401 pipeline inlet valveContinuous low temperature inductor


101-AE-01501 After A-101A inlet valveContinuous low temperature inductor


List of corrosion monitoring probes of atmospheric & vacuum distillation unit



101-AE-01502After atmospheric overhead water

cooler valveContinuous low temperature inductor

with 09 coupon 500 CS 32 60

101-AE-01701Before 3 rd vacuum cut backflow control

valveContinuous high temperature inductor

with 316 coupon 250 316L 209 307

101-AE-01702Before 4th vacuum cut output control


with 316 coupon 150 316L 54 361

101-AE-01703 After P-115A inlet valveContinuous high temperature inductor

with 316 coupon 700 316L 489 369

101-AE-01801

Vacuum overhead level one vacuumizing device water chiller inlet

Continuous low temperature inductor with CS coupon 900 CS 4.2 180

101-AE-01802

Vacuum overhead level one vacuumizing device water chiller inlet

Continuous low temperature inductor with CS coupon 150 CS 4.2 37

101-AE-02101 After E-202 1st vacuum cut inlet valveContinuous low temperature inductor


101-AE-02301After E-205AB 2rd vacuum cut inlet


with 321 coupon 450 321 800 237

101-AE-02401After E-206 3rd atmospheric cut inlet


with 316 coupon 200 316L 110 303

101-AE-02601 After E-306 atmospheric cut inlet valveContinuous high temperature inductor

with 321 coupon 200 321 131 253

101-AE-03201After E-5011st atmospheric middle cut

inlet valveContinuous high temperature inductor

with P5 coupon 300 Cr5Mo 223 263

Before atmospheric heater 1st feed line Continuous high temperature inductor

Sample name Analysis item Performance indicator

Crude oil tank、prior desalting、1st desalting、2rd desalting、desalted crude oil

Salt content、water content、metal content、acid value、sulphur content、

Tank area dewatered crude oil’s water content≤0.5%、salt content after electric desalting≤3mgNaCl/L、water content after desalting≤0.2%、Removal rate of rganic metal

Atmospheric & vacuum distillation unit test analysis and monitoring



Removal rate of rganic metal ions of Ca,Fe,Mg ,Na (excluding Ni,V)≥70%

Electric desalting drainage water

Oil contained、PH Drainage water oil content≤200ppmDrainage water pH: 6-8

Sewage water from atmospheric overhead、vacuum overhead

Fe ion、Cl ion、H2S、NH4、PH、strong acid

Fe ion≤1mg/l、probe corrosion rate: ≤0.2mm/y、PH value:5.5-7.5

Atmospheric overhead oil、vacuum overhead oil、2rd atmospheric cut oil、3rd atmospheric cut oil、2rd vacuum cut oil、3rd vacuum cut oil、4th vacuum cut oil、vacuum residuum

Acid value、S content、Fe content、Ni content

Fe≤1mg/L、probe corrosion rate ≤0.2mm/y

3.4 Process anti-corrosion

It is the integrated multiple treatment system Including the chemical agents of crude oil dewatering demulsifier EC2045A、electric desalting demulsifier EC2506A、reverse demulsifier EC2345A、electric desalting tank demetalization agent EC2047A、low temperature corrosion inhibitor EC1021A、high temperature inhibitor EC1023N、scale inhibitor EC3238A.



C

D

U V

D

U

High temperature corrosion inhibition control area sketch


3.5Environmental protection and others

Huizhou refinery, has since its operation start up in April 2009, kept its sewage water in whole

plant treated to approved level, including the sewage water from electric desalting which have

been draining into deep sea via pipeline after approved treatment, the oils contained sewage

water have been recycled after approved treatment.

Periodic back flush water from electric desalting tank bottom is of high shock to salts contained

sewage water treatment. Due to this reason, during back flushing, first put this stream sewage

water in high concentration sewage adjustment tank, then blend use and treat it gradually.W We

are now trying to use continuous small amount flush to replace periodic flush (once per week).


Other possible approaches to treat this highly polluted sewage water are also under developing

(such as adding preparations and acidic organic substances extracted from naphtha etc).

Due to the correct process technology choosed for subsequent level 2 and level 3 processing

units, all units are in smooth operation, all products are in approved excellent quality. But

because the atmospheric & vacuum distillation unit is designed based on Penglai 19-3 crude oil,

whose light oil yield is only 4.8%, hence when blend it with other type crude oils for refining,

the atmospheric distillation tower overhead load restriction is the main concern. Of course, the

sulphur content in blend crude oils especially for the refining blended crude oils and sulphur

recycle capability are the main restrictions in the selection of crude oil type and amount for

refining blending.

Another factor needs to be considered regarding blended oil types and blending ratio is the water

quality change of sewage water from electric desalting of atmospheric & vacuum distillation unit

after the use of blended crude oil, and the acceptable level of sewage water treatment plant.

3.6 Chemical agents injection system design ( sample )Agent name

Product features Injection point

Injection amount Injection

method

Crude oil tank dewateri

· It can reduce crude oil desalting cost.

Crude oil

Keep the amount in between 2－24ppm as per each case, usually start from 6ppm.（ Basic

· Wide range of adaptability.

· It remarkably reduces the oil entrainment in desalting tank salty water.

· It can effectively reduce the solid impurities in downstream heat exchangers and other equipments, and fouling on equipment inside walls.



dewatering &

deemulsifer

EC2045A

storage tan、header feedline

If electric desalting tank can fix desalting and dewatering issue, then

there is no need to inject demulsifier.）

solution injection

· It increases desalting efficiency, reduces corrosion of unit overhead system.

· It controls the solid content on crude oil/emulsion interface in desalting tank.

· It removes oil contained in inorganic substances in crude oil.

· It helps quick demulsification.

· It increases dewatering efficiency in crude oil storage tank.

· It reduces crude oil desalting cost.

· Wide range of adaptability.

· It remarkably reduces the oil entrainment in desalting tank salty water.

· It can effectively reduce the solid




�� 33、、








44、、Operation performance assessmentOperation performance assessment

4.1 Types and characteristics of the crude oils refined since start up (sample )

Item

Density(20℃

)

API degree

Viscosity， mm2/s

Solidifying point

Acid value

Wax content

Salt content

Water conten

t

Residue

carbon

Ash content

Sulphur

Nitrogen

GelAsphal

t

g/cm3 20℃ 40℃ 50℃ 80℃ ℃mgKOH/

g%(m/m

)mgNaCl/L %(m/m)

%(m/m)

%(m/m)

%(m/m)

%(m/m)

%(m/m)

%(m/m)

Bohai 0.919 21.920.85

-30 3.57 3.8 228 1.1 5.13 0.024 0.28 0.41 17.1 0.8

Liuhua 0.9258 20.990.86

25.74

-30 2.38 5.21 53.1 0.1 6.85 0.024 0.28 0.3 13.68 1.36

Dahun 0.8966 25.6217.2

47.24

30 3.67 25 21.3 痕迹 8.2 0.205 0.13 0.38 12.82 0.14

Duli 0.929 20.27 462.2259.7

8 1.34 15.3 13 0.35 7.13 0.23 0.31 20.1 0.1


Duli 0.929 20.27 462.27

8 1.34 15.3 13 0.35 7.13 0.23 0.31 20.1 0.1

Jilaso 0.8713 30.81 0.3 15 0.343 0.174

Vincent 0.9444 18.3 399.2 94.83 0.7 368.4 0.68 2.1 0.05 0.05

Weizhou 0.8524 33.78.713

13 0.35 23.45 28.6 0.88 2.7 0.023 0.16 0.13 4.72 0.22

Nero 0.847934.637

22.7417.12

34 0.28 28.6 24.82 0.07 3.57 0.05 0.11 7.7 0.1

New Wenchang

0.8908 24.810.03

25 0.84 16.7 0.03 4.49 0.14 0.25

Cao Feidian

0.929 20.73 412.2 141.673.57

2.84 0.325 0.189 0.337

Dalia 0.8992 25.3 103.424.94

9.406

-34 1.28 1.37 66.9 0.2 4.3 0.018 0.52 0.27 12 0.55

Roncado 0.9338 19.5 691.8 9625.82

-32 2.09 0.45 20 0.6 6.11 0.006 0.69 0.39 16.85 1.74

Hange 0.8836 289.798

-25.5

0.558 7.98 31.8 痕迹 5.1 0.011 0.62 0.32 6.65 2.89

4.2 Treatment effectiveness of electric desalting tankUnder very frequent switching between different crude oils and the severe trend of crude oil low quality, electric desalting

process has been in good effectiveness and comparatively stable operation.

� The time between start up and May is the optimization and adjustment period, desalting is of lower approval rate, but most of the salt content results are between about 3.0-3.5 after desalting（pass level is 3.0 below）

�� From June to July, the electric desalting units have been in good operation with desalting pass rate of more than 90%.

� In July, more types of crude oil have been blended, electric desalting effect has been influenced, we try to develop solution.

Month Desalting pass rate，%Prior-desalting salt content

，mgNaCl/lPost-desalting salt content

，mgNaCl/l

Sample qty

Approved sample qty

Pass rate

Max Min Average Max Min AverageElectric desalting

4 4 、、 Operation performance assessmentOperation performance assessment


5 18 2 11.11 120.5 12 38.77 9.4 2.64 4.93

6 22 21 95.45 33 4.95 17.66 3.4 1.65 2.77

7 21 20 95.24 135.3 9.07 33.12 4.46 2.18 2.95

desalting effectivenes

Crude oil salt content salt content after desalting desalting rate

4.3 Electric desalting-demetalization treatment� The effectiveness is generally good

� Electric desalting drainage water has dematalized metal entrainment, which may bring remarkable shock to the sewage water treatment system, hence the sewage water treatment plan should be adjusted and optimized accordingly

Item Fe Pb Al Zn Na K Ca Mg Total

June crude oil before demetalization 5.86 0.01 3.37 0.48 6.63 1.04 35.52 15.22

July crude oil before demetalization 9.6 0.09 9.49 0.59 11.3 2.25 17.05 15.9

Crude oil average before demetalization 7.73 0.05 6.43 0.54 8.97 1.65 26.29 15.56

June crude oil after demetalization 1.95 0 0.2 0.14 0.8 0.06 27.26 9.86



July crude oil after demetalization 0.34 0 1.96 0.37 1.2 0.68 11.69 1.14

Crude oil average after demetalization 1.145 0 1.08 0.255 1 0.37 19.48 5.5

Average demetalization rate 0.8519 1 0.832 0.523 0.8885 0.7751 0.259 0.6465 0.7221

0

5

10

15

20

25

30

Fe Pb Al Zn Na K Ca Mg 合计

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

前前前前前脱

后前前前前脱

前前平平脱

Electric desalting’s effect

of demetalization

Crude oil average before desalting

Crude oil average after desalting

Average desalting rate


4.4 Low temperature corrosion resistant

� Overall effect assessment

� In overhead of both atmospheric & vacuum distillation unit the Fe ion content are all ≤1mg/L，and the probe corrosion rate ≤0.2mm/y，pH value 100% reach the indicator of 5.5-7.5，these figures meant the atmospheric & vacuum distillation unit overhead corrosion is fully under control, all indicators reached advanced standard of both domestic and international.

� Vacuum distillation tower overhead corrosion used to have fluctuation during early period of start up, especially pH value’s higher fluctuation，after a series of optimization and adjustment, both pH value and Fe ions have been under reliable control，current approval rate is more than 90%

� By comparing with probe trend, the higher corrosion rate at atmospheric distillation tower overhead before the charging of neutralizer and corrosion inhibitor is obviously observed,


� By comparing with probe trend, the higher corrosion rate at atmospheric distillation tower overhead before the charging of neutralizer and corrosion inhibitor is obviously observed, while the corrosion rate has been decreased dramatically since the charging of above two preparations, this indicates that correct anti-corrion measures have been implemented on atmospheric distillation tower overhead with remarkable effects. The sewage water in reflux accumulator of atmospheric distillation tower overhead looks clear and contains lower level Fe. As for vacuum distillation tower overhead, there are large amount of light molecular weight organic acid existing there, which will enter into water tank after cooling in level one condenser, and result in probe corrosion rate increase after E-510W，currently by optimized preparation charging operation, the corrosion rate decrease from highest 3mm/a more to 0.2mm/a less，this proves again the excellent performance of the preparations and site professional service which will guarantee plant’s reliable long period running.

� During the start up, test analysis found out large amount of organic acid （about1200－1800ppm if translated into acetic acid）in overhead system, which is beyond our expectation. With Nalco’s careful adjustment and treatment plan, the corrosion was quickly under controlled（ferric ion decreased from hundred more ppm to 1ppm）.

Test result of “Two types” Fe ion

Tower overhead Fe ion pass rate/%

Atmospheric overhead Fe

ion content /(mg/L)

Vacuum overhead Fe ion

amount /(mg/L)

Month

Total sample

amount

Sample pass

amount Pass rate Max Min Average Max Min Average

5 36 29 80.56 1 0.15 0.44 4.2 0.3 1.12

6 43 39 90.70 1 0.05 0.56 1.8 0.5 0.87

7 46 44 95.65 1 0.1 0.59 1.4 0.7 0.89



7 46 44 95.65 1 0.1 0.59 1.4 0.7 0.89

8 42 42 100.00 1 0.1 0.45 1 0.4 0.68

9 50 47 94.00 1 0.1 0.46 1.3 0.3 0.77

10 40 40 100.00 0.9 0.2 0.36 1 0.35 0.69

11 41 40 97.56 1 0.2 0.49 1.2 0.2 0.58

累计 298 281 94.30 1.00 0.05 0.48 4.20 0.20 0.80

Atmospheric overhead（upper）/ Vacuum overhead（lower）probe corrosion rate trend diagram



常顶（上）/减顶（下）探针腐蚀速率趋势图

Atmospheric overhead

corrosion control effect


Atmospheric overhead corrosion control


Vacuum overhead corrosion

control effect

Vacuum overhead corrosion control

� Fe/Ni data analysis

� Overall effect assessment

� At the circumstance that acid value of crude oil and side line is higher than 3mgKOH/g：side line Fe ion

content are all <1.0mg/l，corrosion probe reading is less than 0.2mm/a，all reach the required control

trargets.

This demonstrates that upgraded material cooperated with good high temperature corrosion

inhibitor can control the high temperature corrosion resulted from high acid crude oil refining.

4.5 High temperature NAC corrosion treatment



� Fe/Ni data analysis

Date 2009-6-3 2009-6-22 2009-7-6 2009-7-20

Fe(ppm) Ni(ppm) Fe(ppm) Ni(ppm) Fe(ppm) Ni(ppm) Fe(ppm) Ni(ppm)

2rd atmospheric cuts 0.27 0.01 0.55 0 0.01 0.03 2 0.39

3rd atmospheric cuts 0.01 0.01 0.2 2 0.03 0.02 0.07 0.11

2rd vacuum cuts 0.01 0.01 0.77 0.01 0.15 0.05 0 0.02

3rd vacuum cuts 0.01 0.01 0.42 0.01 0.81 0.05 0 0.19

4th vacuum cuts 3.19 62.54 12.84 51.68 3.84 20.73 4.6 28.85

Vacuum residues 8.75 92.22 11.92 83.33 8.94 62.83 7.16 53.02

Crude oil 2.93 32.36 8.51 23.97 0.34 26.87 1.29 17.21

Note：Fe/Ni ions content analysis results are conformed to material balance；corrosion has been well controlled.

Electric desalting effect diagram


Salt content upper limit after desaltingCrude oil salt content Salt content after desalting Desalting rate


20.00

25.00

30.00

80.00%

100.00%

120.00%

脱前原油平均

Corrosion control effect of all side lines



0.00

5.00

10.00

15.00

Fe Pb Al Zn Na K Ca Mg 合计

0.00%

20.00%

40.00%

60.00%

脱前原油平均

脱后原油平均

平均脱除率

Crude oil average before desalting

Crude oil average after desalting

Average desalting rate

Total

高温腐蚀情况

40

50

60

70

Fe/Ni含

量

常二线

常三线

减二线

减三线

Corrosion control effect of all side lines


High temperature corrosion

Atm cut 2

Atm cut 3

Vacu cut 3

Vacu cut 4

Vacu


0

10

20

30

Fe

(pp

m)

Ni(

pp

m)

Fe

(pp

m)

Ni(

pp

m)

Fe

(pp

m)

Ni(

pp

m)

Fe

(pp

m)

Ni(

pp

m)

Fe

(pp

m)

Ni(

pp

m)

Fe

(pp

m)

Ni(

pp

m)

2009-6-3 2009-7-6 2009-8-11 2009-9-14 2009-10-15 2009-11-27

时间

Fe/Ni

减三线

减四线

减渣

原油

Time

Fe/N

conte

nt

Vacu

residue

Crude oil


� Probe data analysis

� Probe data analysis indicates that: corrosion rate ＜ 0.2mm/y



4.6 Fouling control effect

� As it has only been 4 months since the operation start up, accurate assessment of plant fouling

control is not available.

� The focus of next step is to install temperature sensors on inlets and outlets of main heat

exchangers, transmit the temperature data to DCS, calculate the heat exchanging efficiency of

certain or a serious of heat exchanger, to judge the current fouling trend and implement further

measures accordingly.

4.7 Sewage water and its treatment

� Sewage water from whole plant can be treated to qualified quality, and the salts contained

sewage water will be drained into deep sea by pipeline after qualified treatment, the oil contained


sewage water will be drained into deep sea by pipeline after qualified treatment, the oil contained

sewage water have been fully recycled after qualified treatment.

� Periodic back flush water from bottom of electric desalting tank is of considerable shock to salts

contained sewage water treatment（sewage water sample refer to left and right figure）

� Current disposal：during back flush, first put this stream of sewage water into high concentration sewage

water regulating tank, then gradually blend and treat it.

� Disposal method under development：change periodic (once a week) flush to continuous small flashes

Treat this high polluted sewage water with other method (for example the

dispersants)

Centrifuged sample from Mingzhu heater/treater interfaceCentrifuged sample from Mingzhu heater/treater interface

44、、 Operation performance assessmentOperation performance assessment

4.8 Product quality

� All current products are of excellent quality with approval

� During blended oil refining, the main issues to be considered are the atmospheric distillation load constraining and the effect of sulphur content in blended curde oil.

� Another factor to be considered for appropriate crude oil blending ratio and oil types is the quality change of sewage water from atmospheric &


and oil types is the quality change of sewage water from atmospheric & vacuum distillation electric desalting after crude oils blending, and the acceptance level of sewage water treatment plant.

4.9 Others

Product quality of hydrogenation unit：

Conflict between diesel cetane number and smoke point

Nitrogen content issue

Anti-corrosion in coking、catalytic units




�� 33、、








5 5 、、Problems existing in current CDU and improvement solutionsProblems existing in current CDU and improvement solutions

Problems Cause Improvement solutions

Occasional water content during electric-desalting

1、Over high PH value of feed water, the content of NH4 and impurities exceeds limit. Improve feed water quality

Assess the mix ratio between crude oilsAdd in asphalt dispersants

2、High content of gel-asphalt and solid particles.

3、Crude oil upstream processing used too much additives.


used too much additives.

Overhead condensate water ammonia nitrogen content exceeds limit

1、Overhead system has large amount of organic acids and acetic acid content is very high, the usage of neutralizer is over limit due to corrosion controlling.

Reduce upstream acetic acid usage；reselect the neutralizer；consider to add alkali into crude oil

High content of solid content、ammonia nitrogen、metal、oil、COD

1、It is the sequela of high acid crude oil refining.

Enhance sewage water processing capability to elevate electric-desalting drum flexibility--add in solid wetting agent

--add in asphaltdispersants

2、Disparity within high acid crude oils match.

3、Remarkable difference between

current crude oil and design.




�� 33、、








Producing clean fuel or high value added petrochemical products from heavy content & low quality crude oil is now a big challenge that oil refining industries have to face. Among the heavy content & low quality crude oil category, high acid crude oil is of high acid value、fewer light components 、high density and viscosity、high content gel-asphalt、high salt and metal content, which may result in equipment serious corrosion、worries of product quality and environmental protection、poor processibility aliked problems.

World leading refinery with 100% full conversion of high acid heavy crude oil——CNOOC Huizhou 12 million tons/year oil refining project has been put into production. Even just 1 year has elapsed since its production start up, but until now, it has

6 6 、、ConclusionConclusion


CNOOC Huizhou 12 million tons/year oil refining project has been put into production. Even just 1 year has elapsed since its production start up, but until now, it has achieved good outcomes together with remarkable economic returns in the area of electric-desalting、high & low temperature corrosion control、the processing and treatment of kerosene and diesel、wax oil、residuum. Its technology、expertise and experience have been practiced and approved in the areas of raw material choosing and batching、equipment selection、process operation and anti-corrosion、supervision & monitoring、quality control、environmental protection、management innovation. It is now accumulating more processing experience of high acid crude oil from the operation.

THANK YOU FOR YOUR ATTENTION

High TAN

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