INTERTANKOINTERTANKOInternational Association of Independent Tanker OwnersInternational Association of Independent Tanker Owners

Safe Transport, Cleaner Seas, Free CompetitionSafe Transport, Cleaner Seas, Free Competition

The Control of Volatile Organic Compounds

Emissions from Crude Oil Tankers

The VOCON Project

The VOCON Project

The Objectives• Using the data already available from the

CRUCOGSA project, compare and contrast the Vapour Pressure developed from cargoes at differing loaded conditions.

• Monitor the pressure drops during vapour releases in order to develop methods to limit VOC emissions.

• Monitor the concentration of VOC displaced during defined stages of loading.

The VOCON Project

The Scope of Data Collection• Cargo quantification at load and discharge

ports• Cargo Temperatures daily during voyage• Environmental Data every four hours

during voyage• VOC pressure release data for each vapour

release• VOC concentration during loading

The VOCON Project Cargo Operations creating VOC

Emissions • During Transportation

• Vapour Releases due to Volatility and Cargo temperature

• Inert Gas Pressure Variations• Loading - displacement of VOC from:

• Previous Cargo• Incoming Cargo

The VOCON Project The Reason for VOC Emissions

• EQUILIBRIUM of PRESSURE– Equilibrium between the Cargo Vapour

Pressure and the Maximum Operating Pressure of the Hull Construction (P/V Valve)

– IF Cargo Vapour Pressure Greater then Release follows until EQUILIBRIUM is achieved.

VOCON ProjectIs this the Source of the Problem?

– NO!

The VOCON Project Measures for VOC Emission

Reduction• Better Stabilisation (Reduction of Vapour

Pressure) of Cargo for shipment

• Operational Measures for VOC Emission control

• Technical and Design Solutions for VOC Emission Control and Recovery

The VOCON Project Crude Oil StabilisationRVP of Differing Crude Oil types

0

2

4

6

8

10

12

Ano

a

Ara

b Li

ght

Bac

h H

o

Bin

tulu

Nea

t

Bre

nt B

lend

Dai

Hun

g

Dra

ugen

Es S

ider

Foro

ozan

Irani

an H

eavy

Ker

apu

Lava

n

Low

er Z

akum

May

a

Miri

Nan

hai

Odu

du

Ose

berg

Qat

ar L

and

Rab

i

Soyo

Trol

l

Crude Oil

Pres

sure

psi

a

RVP Minimum

With a Reid Vapour Pressure

(RVP) above 6 psia some degree of vapour release seems most likely

to occur

The VOCON Project

Operational Measures (1)• The Problem

– A P/V valve will be opened at a defined pressure but at what pressure should it be closed? If the closing pressure can be determined then unnecessary VOC release can be avoided.

• The Physics of Gas and Vapours– If the Saturated Vapour Pressure for the

prevailing cargo temperature is known then the valve should be closed at this Pressure.

The VOCON Project Operational Measures (2)

Voyage 141

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23Voyage Days

Pres

sure

mm

WG

83

84

85

86

87

88

89

90

91

92

93

94

Tem

pera

ture

deg

F

The VOCON Project Operational Measures (3)

Pressure Release Report

Vessel Code: VOC2294Voyage No: 141Voyage Start: June 18, 2001 Commenced Loading at ForcadosVoyage End: July 11, 2001 Moored at LOOP

All releases are from forward mast riserTime

Start End Mins Start End20-Jun-01 Release 06:06 06:40 36 1200 30020-Jun-01 Release 10:28 10:54 26 1219 25420-Jun-01 Release 17:36 18:06 30 1219 25421-Jun-01 Release 09:48 10:24 36 1168 10222-Jun-01 Release 13:37 13:52 15 1245 12725-Jun-01 Release 10:23 10:42 19 991 25427-Jun-01 Release 10:21 10:42 21 1016 25428-Jun-01 Release 16:48 17:06 18 1220 40630-Jun-01 Release 14:26 14:38 12 1245 25402-Jul-01 Release 13:26 13:38 12 1245 25404-Jul-01 Release 13:53 14:13 20 1295 25406-Jul-01 Release 15:55 16:12 17 1245 20308-Jul-01 Release 14:08 14:27 19 1245 25610-Jul-01 Release 14:53 15:08 15 1270 279

Time Inert Gas Press(mmWG)Date Operation

Total release time for voyage

Total volume (gas) released

4hrs 56 mins

233906 m3

The VOCON Project An Operational Solution (1)

October 9th releaseArab Light crude Oil

0100200300400500600700800900

1000

0 5 10 15 20 25 30 35 40 45Time (minutes)

pres

sure

mm

WG

Is there a need to release below the

True Vapour Pressure of the

Cargo at its prevailing liquid

temperature?

P/V Valve Release

The VOCON Project

An Operational Solution (2)Oseberg Gas release

0

200

400

600

800

1000

1200

1400

0 5 10 15 20Time - mins

Pres

sure

mm

WG

The True Vapour

Pressure is recognised when the pressure decline

becomes linear

Mast Riser Releases

The VOCON ProjectAn Operational Solution (3)

• The VOCON Valve• Controlled closing

pressure by hydraulics from cargo control room

• Now used also for VOC control during loadings

The VOCON Project An Operational Solution (4)

Simply operated

equipment that can measure

prevailing TVP per ASTM

Test Method

Cost Approx:

Euro 16,500

The VOCON ProjectLoading Emissions (1)

Appendix 2

Total Vapour Pressure Isotherms at different Vapour to Liquid ratios

3

5

7

9

11

13

15

17

19

21

0 0.1 0.2 0.3 0.4 0.5

Vapor to Liquid Ratio

Pres

sure

(psi

a)

Champion

Forcados

Palanca

Brent

Maya

Oseberg

Oman

Iranian Light

Arabian Super Light

Arabian Light

The VOCON ProjectLoading Emissions (2)

VOC (%) During Loading of Bonny Light and Brass River Crude Oils

0%

10%

20%

30%

40%

50%

60%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

% Fill of Cargo Tanks

% H

ydro

carb

on V

apou

r

Unsaturated Vapour

Conditions

Increased Vapour

concentrations creating

increased Pressure

Diffusion of Vapour from First Crude Oil

whilst awaiting commencement of Second Crude Oil

The VOCON Project Loading Emissions (3)

Loading Arab Light C.O.

0

10

20

30

40

50

60

70

0% 20% 40% 60% 80% 100%%Fill

% V

OC

l

Vapor VOC (%)

Loading VOC Emissions

• Two differing Philosophies developed:– Re-capture after VOC evolves– Prevent VOC evolving

• Re-capture System – Absorption or compress gases for deck storage and discharge.

• Prevent VOC evolving – KVOC System

VOC being ControlledProactively by Industry

Thank you for your Attention

Questions?