tripartite meeting, oct. 2010 1 a new concept for resolving the ballast water management problem -...

Tripartite Meeting, Oct. 2010

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A New Concept for Resolving the Ballast Water Management Problem

- Buoyancy-control Type Ballast-free Ship -

Makoto Arai Dept. of Systems Design for Ocean-Space, Faculty of Engineering

Yokohama National University, Japan


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・ Ballast water problemsLoading and discharging operation,Impacts,

Ballast water convention,

Ballast water treatment technologies

・ Proposed ballast-free ship concept

・ Model experiments and Numerical analyses

・ Application to actual ship tank configurations

・ Conclusions

3-D numerical analyses

Model experiments


3Http://www.globallast.od.ua/eng/problem.asp

Loading and discharging operation of ballast water

Ballast water problems

Ecological: native biodiversity and/or ecological processes are disruptedEconomical: fisheries, coastal industry and other commercial activities and resources are disruptedHuman health: toxic organisms, diseases and pathogens are introduced

GreenTech

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Http://www.globallast.od.ua/eng/problem.asp

Loading and discharging operation of ballast water

Dischargingcargo

Loading ballast water

Cargo holdempty

Loading cargo

Ballast tanks full Discharging ballast water Ballast tanks empty

Cargo holdfull

(1) At source port (2) During voyage (3) At destination port (4) During voyage

Ballast water problems

Possible impacts


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http://www.globallast.od.ua/eng/problem.asp


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Organism category Regulation

Plankton, 50 μm in minimum dimension <10 cells/m3

Plankton, 10-50 μm <10 cells/ml

Toxicogenic Vibrio cholera (O1 and O139) <1 cfu*/ 100ml

Escherichia coli <250 cfu* / 100ml

Intestinal Enterococci <100 cfu* / 100ml

Planktons gathered by a plankton net.(Ohmura, Fukuyo: NTS, Sept. 2008)

D-2 Regulation ： Ballast water performance standard

Mainly animal plankton

Mainly plant plankton

*colony forming unit: measure of viable bacteria numbers

Ballast water management conventionThe International Maritime Organization (IMO) adopted the “International Convention for the Control and Management of Ships’ Ballast Water and Sediments” in 2004.


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Ballast water treatment technology process options

[Ref.] Lloyd’s Register, Ballast water treatment technology - Current status, 2007

　

・ Surface filtration

・ Hydrocyclone

Treatment:

　

　

・ Coagulation/ Flocculation

Chemical enhancement:

・ Chlorine dioxide

・ Vitamin K

・ Peracetic acid

・ Ozonation

・ Electrochlorination or electrolysis

・ Chlorination

Chemical treatment:

・ Cavitation

・ Ultrasonic treatment

・ Gas injection

・ Deoxygenation

・ UV + TiO2

・ UV irradiation

Physical treatment:

・ Cavitation

・ Ultrasonic treatment

Physicalenhancement:

・ Chemical reduction (sulphite/bisulphite)

Residual control:

Physical solid-liquid separation

Disinfection

OR


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In case of 220,000DWT Bulk carrierSystem-A: Initial cost $4,200,000 Running cost $26,000/treatmentSystem-B: Initial cost $900,000 Running cost $19,000/treatment + overhaul $15,000/year

Example of the arrangement of a ballast water treatment system for a container ship( Ninokura, S., NTS, Sept. 2008)

A trial calculation:

Possible engineering problems:Decrease of cargo space,Increase of the electric generator capacity,Storage of chemicals, sediment,..Maintenance of filters, …Reliability of the complicated system,Supply of expendables,…

Ballast water treatment system


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Volume of ballast water

Plankton, 50 μm : <10 cells/m3

Plankton, 10-50 μm: <10 cells/ml

D-2 standard:

Acceptable?

VLCC

VLCC with 110,000m3 ballast water:

9cells/m3 x 110,000m3=1x106 cells

9cells/ml x 110,000m3=1x1012 cells

Lpp[m] GT[t] Ballast[ ]㎥

278 85,663 57,195

216 36,074 21,986

181 27,011 14,124

150 13,403 6,274

107 5,997 2,510

Bulk carrier

Lpp[m] GT[t] Ballast[㎥]

322 149,896 110,242

235 52,484 37,601

161 22,943 14,240

145 12,811 8,325

110 6,253 3,316

Oil tanker


283 58,531 14,895

181 18,502 7,268

150 13,448 6,165

136 11,810 3,165

110 6,543 3,064

Container ship


152 14,499 6,478

122.9 9,235 2,639

107 6,079 2,981

93 4,724 1,583

70.5 498 776

Cargo ship


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Is retrofit possible?

An existing shipA newly-built ship

http://www.jasnet.or.jp


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Summary

1. In order to fulfill the requirements of IMO’s Ballast Water Convention, lots of 　　 works, especially the development of BW treatment systems are being

carried out.

2. However, there are a wide variety of ship types with different size, age, shape, cargo type, operation system, etc., and one and only BW treatment system

may not cover all of those ship types. Therefore, we believe it is worth studying the possibility of alternative systems in addition to the BW treatment system.


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-In the lightweight condition, sea water is drawn into a buoyancy control tank by using the pump system. As a result of the weight of the water taken into the tank, the ship loses some of its buoyancy and gains sufficient draft for navigation. The sea water in the tank is circulated by utilizing the advance speed of the ship. In order to accelerate the circulation of the water in the tank, the shapes of the sea water intake and exit vents are designed appropriately. Also, the locations of the intake and exit are determined considering the pressure distribution on the ship’s bottom. Through the circulation of the water, the components of the water inside the tank are kept identical to those of the local sea water outside the ship’s hull. Together with the opening and closing operation of the air drain system, the tank can be fully filled with sea water even if the tank’s top ceiling is located above the ship’s draft line.

- In the full load condition, the intake and exit vents of the tank are closed, and the tank is emptied by the ship’s pump system to give sufficient buoyancy to the ship.

Concept

Buoyancy control tank

Ship’ advance speed

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Buoyancy control tankBuoyancy control tank

Air pipe: open

Intake & exit vents: closed

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Buoyancy control tankBuoyancy control tank

Air pipe: closed

Intake & exit vents: open


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Intake and exit shapes

Bottom plate

Flow direction

Possible variants of intake and exit shapes

High pressure

Low pressure

30deg.

0.5m

0.5m

Flow direction

30deg.

1mIN-1

IN-2

IN-3

IN-4

1m

1m

1m

30deg.

1m

0.5m

0.5m

0.5m1m

1m

1m

EX-1

EX-2

EX-3

EX-4

Flow direction

Intake Exit

Inside the buoyancy control tank

Outside the ship


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Fluid A Fluid A

Fluid B

Intake Exit

Before opening the intake and exit After opening the intake and exit

Water locality ratio

Flow

In order to examine the performance of the water circulation, we compared the water locality ratio (R) of each tank. R=(Volume of fluid A in the tank)/(Tank volume)R is defined as the ratio of exchanged fluid volume inside the tank.

In this system a higher water locality ratio is desirable. I.e., R=1.0 (100%) 　　　　Composition of the seawater inside the tank is the same as that outside it.

Numerical analysesIn this study, we analysed the seawater circulation in the tank by using ANSYS-FLOTRAN.


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500

240

125

Intake A

Exit C

Exit B

VTR camera

Model experiments at the circulating water channel

Model experiment setup

Model tank

2,026mm

Model tank Dummy bowDummy stern

Flow direction


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A small amount of colourant was added to the water inside the tank, and the change of colour density in time was measured.

Measurement of the water locality ratio(high speed playback: 8x)

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250

数値計算 1.0 m/ s実験 1.0 m/ s数値計算 0.50 m/ s実験 0.50 m/ s

Time (sec.)

Wat

er lo

calit

y ra

tio (%

)

Num. cal.

Exp.

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IMDC 2009

Measured water locality ratio(L: ship length, U: flow velocity, t: time)

0 10 20 30 40 50 600

10

20

30

40

50

60

70

80

90

100

0.250.51.0

tU/L

U (m/s)


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Double bottom tankBilge hopper tank

Side tank

Analyses of actual ship tank configurations


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Double bottom tank of a 1,600TEU container ship (v=23.3 knots)

Intake

300 150

300150

300

300Unit: mm

ExitFlow

T=500s., R=17.3% T=5000s., R=85.5%

0

10

20

30

40

50

60

70

80

90

100

0 1000 2000 3000 4000 5000 6000 7000 8000

海水

置換

率：[

%]

時間t：[s] Time (sec.)

Wat

er lo

calit

y ra

tio (

%)

Computed time change of the water locality ratio (v=23.3kn)


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Exit: partial sphere type

Intake: flat type

Flow

Intake: flat type with lid

Exit: partial sphere type

Flow

[2000s] 62.5% [4000s] 90.1% [6000s] 97.9%

Original

Modification 2

[6000s] 51.5%

0 50 100%

Flow

[6,000s., 51.5%]

0102030405060708090

100

0 2500 5000 7500 10000 12500 15000 17500 時間： t[s]

海水

置換

率：

[%]

Case 1

Case 2

Case 4

0102030405060708090

100

0 2500 5000 7500 10000 12500 15000 17500 時間： t[s]

海水置換

率：[%]

Case 1Case 2

Case 4

0102030405060708090

100

0 2500 5000 7500 10000 12500 15000 17500 時間： t[s]

海水置換

率：[%]

Case 1Case 2

Case 4

0102030405060708090

100

0 2500 5000 7500 10000 12500 15000 17500 時間： t[s]

海水置

換率

：[%

]

Case 1Case 2Case 4

Modification 2

Modification 1

Original

Modificationof trans.

Intake type

Yes

Yes

No

Flat type with lid

Flat type

Flat type

Tank design

Time (sec.)

Wat

er lo

calit

y ra

tio (

%)

Bilge hopper tank and side tank (1,600TEU container ship, v=23.3knots)


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Comparison of measured number of organisms in Tokyo Bay and IMO's D-2 standards

< 100 cfu/100ml-Intestinal Enterococci

< 250 cfu/100ml-Escherichia coli

< 1cfu/100ml-Toxicogenic Vibrio cholera (O1 and O139)

< 10 cells/ ml103 cells/ml m in minimum dimension

< 10 cells/m3105 cells/m3 m in minimum dimension

IMO standardsTokyo Bay [Ref.: Kuno]Organism category

Plankton, 50

Plankton, 10-50

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

99.99% at 154 n.m.99% at 77 n.m.

Wat

er lo

calit

y ra

tio (

%)

Voyage distance (nautical miles)

99.99% dilution

99.0% dilution

Example of the relation between the voyage distance and the sea water locality ratio

Cf. ..200 mnEEZ

Design criterion of the proposed ballast-free ship


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In this presentation, we proposed a ballast-free ship concept and showed the results of model experiments and numerical analyses carried out to enhance the performance of the proposed system. In order to evaluate the ballast-free system, we proposed a criterion that accords with the IMO’s D-2 regulation. The proposed ballast-free ship can be an efficient and environmentally friendly alternative to cope with the ballast water problems on ships. The system is especially effective for retrofitting since it can be applied to existing ships without serious structural modifications.

Conclusion


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Upogebia major

As a matter of fact, this technology has been used by somewild animals and crustaceans.

Ventilation inside the nest ofPrairie dogs

We also use this tech!

http://ja.wikipedia.org

Wind

tripartite meeting, oct. 2010 1 a new concept for resolving the ballast water management problem -...

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