1 TONGJI UNIVERSITY Institute for Hydrogen Energy Technologies Study on the Harm Effect of Liquid...

1TONGJI UNIVERSITY

Institute for Hydrogen Energy Technologies

Study on the Harm Effect of Liquid Hydrogen

Release by Consequence Modeling


Presentation for ICHS 2011

Presented by: Dr. LI. Zhiyong

Instructed by: Prof. MA. Jianxin

Dr. PAN. Xiangmin

September 14th, 2011

2TONGJI UNIVERSITY


Introduction of IHET in Tongji University

IHET (Institute for Hydrogen Energy Technologies) has been focused on

hydrogen infrastructure R&D in China for more than 10 years. Engineering practice on hydrogen technologies

Four hydrogen refueling stations (HRS); Several mobile HRS; A demo

coking gas purification facility Technical experience in building codes and standards

Technical Code for Hydrogen Fuelling Station (GB50516-2010);

Technical Specification of Hydrogen Refueling Stations for Fuel Cell

Vehicles (DGJ08-2055-2009) Numerical research experience on hydrogen releases

The potential hazards of accidental gaseous hydrogen release;

The harm effect of different consequences such as jet fire, flash fire,

physical explosion and vapor cloud explosion.

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First HRS developed by IHET

2006, Shanghai Anting HRS, serving for FCVs test for 2008 Olympic Games

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Hydrogen supply network developed by IHET

2010, Expo station, serving for FCVs for 2010 Expo

6100

EXPO HRS

Mobile HRS

FC Cars

By-product H2 Purification Plant

Anting HRS

90

FC BusesFC Sight-seeing Cars

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Hydrogen filling infrastructure built by IHET recently

2010, Guangzhou HRS, serving

for the 2010 Asian Games

2011, Shengzhen HRS, serving for

the 2011 World University Games

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Contents

1. Introduction 1.1 Background and objective of this study 1.2 Potential hazard of liquid hydrogen storage

2. Modeling 2.1. Possible consequences of liquid hydrogen release 2.2 Harm criteria 2.3 Model and assumptions

3. Results and discussions 3.1 Harm effect distance of each consequence 3.2 Comparison with compressed hydrogen vessel

4. Summary

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1. Introduction

1.1 Background and objective of this study Liquid hydrogen can be stored and transported in much larger

quantities than compressed hydrogen and may be considered as an

alternative storage for hydrogen vehicles.

This paper studies the accidental release of hydrogen from cryogenic liquid storage tank and calculates the subsequent consequences such as hydrogen cold cloud, fire ball, jet fire, flash fire, and vapor cloud explosion.

The purpose is to evaluate the harm distance of the cold effect, thermal effects and overpressure effects from above hydrogen consequences.

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1. Introduction

1.2 Potential hazard of liquid hydrogen storage

The principle hazard associated with cryogenic storage is the

accidental released hydrogen related to its low temperature

and flammable potential.

For low temperature, the reduction in temperature by the released

hydrogen may cause cryogenic burns to people.

For flammable effect, the primary hazard is related to fire and explosions. In a fire event, the radiant heat fluxes or direct contact with

hydrogen flames may cause burn to people. In vapor cloud explosion event, the blast wave overpressures are

harmful to people.

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2. Modeling

Liquid hydrogen

Instantaneous release

Continuous release

Without ignition

With ignition

Direct ignition

Cold cloud

Flash fire

Vapor cloud explosion

Fireball

Delayed ignition

Without ignition

With ignition

Direct ignition

Cold cloud

Flash fire


Jet fire

Delayed ignition

Figure 1 Event tree of liquid hydrogen release

2.1 Possible consequences of liquid hydrogen release

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2. Modeling

2.2 Harm criteriaTable 1 Harm criteria used in modeling

Consequences Harm effect Harm criteria to people

Cold cloud Cold effect -40 [1]℃

Fire ball Flame contact ; heat radiation

Fireball radius;9.5 kW/m2[1] or 520 (kW/m2)3/4s[2]

Jet fire Flame contact;heat radiation

Jet fame length; 9.5 kW/m2 [1] or 520 (kW/m2)3/4s[2]

Flash fire Flame contact Lower flammable limit (4%)[1]


Overpressures 0.07 bar[1]

[1] IGC Doc 75/07/E/rev. Determination of Safety Distances. European Industrial Gases Association, 2007

[2]CPR 16E (Green Book). A Model for the determination of possible damage. TNO,1992

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2. Modeling

2.3 Model and assumptions The thermal effects including both direct flame contact and heat r

adiation from immediate ignition consequences are calculated with fir

eball model by Martinsen, et al [3] and jet fire model by Cook, et al

[4], respectively. The explosion overpressure of a vapor cloud explosion is calculate

d with a Baker-Strehlow method [5].

[3] Martinsen, et al. ， An improved model for the prediction of radiant heat from fireballs. International conference and workshop on modelling the consequences of accidental release of hazardous materials, San Francisco California, 1999

[4] Cook J, et al. A comprehensive program for calculation of flame radiation levels. Journal of Loss Prevention in Process Industries, 1990

[5] Baker, Q. A. et al, Recent Developments in the Baker-Strehlow VCE Analysis Methodology, the 31st Loss Prevention Symposium, 1997

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2. Modeling

Table 2 Modeling assumptions and parameters

Item Catastrophic rupture

Leak from tank

Release inventory (kg) 3.5

Release pressure（ bar） 1

Release direction —— Horizontal, downwind

Release hole size (mm) —— Vary, up to 10mm

Release height (m) 1

Atmospheric temperature ( )℃

15

Wind velocity (m/s) 5

Pasquill stability D (neutral)

Result output height (m) 1

2.3 Model and assumptions

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3. Results and discussions

Figure 2 harm effect distances of catastrophic rupture of liquid hydrogen tank

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8Cold cloud Fire ball Flash fire Vapor cloud explosion

-40℃

Flame contact

9.5kW/m2

520 (kW/m2)3/4sNot reached

4% concentration

0.07bar45

40

35

30

25

20

15

10

5

0

Har

m e

ffec

t d

ista

nces

(m

)

3.1 Harm effect distance of each consequence

Vapor cloud explosion>flash fire>cold cloud>fireball Harm effect from the heat radiation of the fireball may be neglected

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Figure 3 harm effect distances of 10mm leak from liquid hydrogen tank

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8Cold cloud Jet fire Flash fire Vapor cloud explosion

-40 ℃

Flame contact 9.5kW/m2 520 (kW/m2)3/4s

4% concentration

0.07bar12

10

8

6

4

2

0

Har

m e

ffec

t d

ista

nces

(m

)

3.1 Harm effect distance of each consequence Vapor cloud explosion>jet fire>flash fire>cold cloud Thermal dose of Jet fire> fireball for the reason of duration Catastrophic rupture is the dominate event rather than leak scenarios

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Figure 4 harm effect distances for leak from liquid hydrogen tank with different release hole size

3.1 Harm effect distance of each consequence Harm effect distances increases with the growth of leak diameter Harm sequence do not change with leak diameters

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11

Har

m e

ffec

t dis

tanc

es(m

))

Cold effectFlame contact of jet fireHarm of heat radiation from jet fireHarm of thermal dose from jet fireFlash fireVapor cloud explosion

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11

Release diameter(mm)

Cold effectFlame contact of jet fireThermal radiation intensity from jet fireThermal dose from jet fireFlame contact of flash fireOverpressure from vapor cloud explosion

12

10

8

6

4

2

0

Har

m e

ffec

t d

ista

nces

(m

)

2 4 1 3 85 6 7 9 10 11

Release diameter (mm)

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0

5

10

15

20

25

30

35

40

45

1 2 3 4 5

Li qui d hydrogen

70MPa hydrogen storage

Cold cloud

Fire ball

Flash fire


Physical explosion

Liquid hydrogen70MPa hydrogen storage

45

40

35

30

25

20

15

10

5

0

Har

m e

ffec

t d

ista

nces

(m

)

Figure 5 harm effect distances of catastrophic rupture under different storages

3.2 Comparison with 70MPa storage With ignition, liquid hydrogen storage may be more dangerous Without ignition, liquid hydrogen storage may be safer In total, liquid hydrogen storage may be more dangerous than

70MPa storage in case of catastrophic rupture

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0

10

20

30

40

50

60

1 2 3 4

Li qui d hydrogen

70MPa hydrogen storage

Cold cloud Jet fire Flash fire Vapor cloud explosion

Liquid hydrogen70MPa storage

60

40

50

30

20

10

0 Har

m e

ffec

t d

ista

nces

(m

)

Figure 6 harm effect distances of 10mm leak under different storages

3.2 Comparison with 70MPa storage

With ignition, liquid hydrogen storage may be safer Without ignition, liquid hydrogen storage may be a little more dangerous In total, liquid hydrogen storage may be safer than 70MPa storage in case

of leak scenario

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4. Summary

For instantaneous releases of liquid hydrogen, the sequence of harm

effect distances is that vapor cloud explosion>flash fire>cold cloud>

fireball.

For continuous releases of liquid hydrogen, the sequence of harm effect

distances is that vapor cloud explosion>jet fire>flash fire>cold cloud.

The liquid hydrogen storage may be safer than 70MPa gaseous storage

in case of leak scenario but may be more dangerous than 70MPa

storage in case of catastrophic rupture. It is difficult to tell which

storage is safer from a consequence perspective. Further investigation

need to be made from a standpoint of risk, which will combine both

consequences and the likelihood of scenarios.

19TONGJI UNIVERSITY


Thanks for Your Kind Attention

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