LPG Storage Tank Fire and Explosion

Chapter 96LPG Storage Tank Fire and ExplosionAccident

Yingchao Dong, Wenhua Song and Fanghua Hu

Abstract The dangers of liquefied petroleum gas (LPG) have been analyzed.The storage tanks of liquefied petroleum gas have been fixed at 20 m3, and thequantitative analysis of boiling liquid expanding vapor explosion occurring in tankdiscussed by the model. The results showed that when the distance between thetarget and the fireball is 14.12–22.32 m, there would be no discomfort with long-term exposure; within 8.00–14.12 m there would be slight pain caused but noblisters; during 5.65–8.00 m there would be moderate damage creating first degreeburn/10 s, 10 % deaths/1 min; in the range of 4.61–5.65 m there would be moreserious wounds (injuries/10 s, 100 % deaths/1 min); and less than 4.61 mthere would be deaths (1 % deaths/10 s, 100 % deaths/l min). In addition, thedesign of the LPG station, which met the requirements of fire protection, wasconfirmed and could provide design proposals for the spacing between the relatedconstructions.

Keywords Liquefied petroleum gas � Storage tank � Boiling liquid expandingvapor explosion � Fireball

96.1 Introduction

With worldwide energy shortage, for environmental protection and economicneeds, liquefied petroleum gas (LPG), as chemical material and fuel with resource-rich, less pollution, and low prices, is attracting a lot of attention. It has been

Y. Dong (&) � W. Song � F. HuSchool of Environmental and Chemical Engineering, Tianjin Polytechnic University,Tianjin, People’s Republic of Chinae-mail: [email protected]

Z. Zhong (ed.), Proceedings of the International Conference on InformationEngineering and Applications (IEA) 2012, Lecture Notes in Electrical Engineering 216,DOI: 10.1007/978-1-4471-4856-2_96, � Springer-Verlag London 2013

791

widely applied in industrial production and daily life. However, because of theflammable nature of LPG, leakage in LPG storage tanks will lead to fire andexplosion. Once such accidents happen, the affected area will be broad and serious.It will pose a threat to the buildings around and seriously affect the lives of thepeople around. This paper focused on predicting LPG tank fire and explosionaccidents. The scope and the impact of the accident damage were also analyzedquantitatively.

96.1.1 Risk Analysis of LPG

Propane is the main component of LPG, whose combustion heat value is2,220 kJ/mol and boiling point is -42.10 �C [1]. Therefore, LPG has a high com-bustion heat value and low boiling point. It will quickly gasify at a higher temper-ature. When the LPG decompresses suddenly, the liquid in the tank with a hot statewill make the temperature reach a certain level, and then superheated liquid evap-orates violently, ultimately causing an explosion. The explosion lower limit for LPGis 5 %, the upper limit 9.65 %, and the smallest ignition energy 0.2–0.3 m. Theexplosion gas will spread to the surrounding area rapidly, very easily formingexplosive gas. Once exposed to an ignition source, it will explode again, called theboiling liquid expanding vapor explosion.

The boiling liquid expanding vapor explosion of LPG is an explosion caused bythe sharp gasification of the liquid. The explosion energy comes from the boilingliquid and vapor expansion. The main reason for boiling liquid expanding vaporexplosion is when the tank has a large crack, and the tank liquid boils and gasifies.When the container’s temperature is too high or surrounded by flames, the LPGwill produce high pressure; if the safety valve relief is not timely, it will cause asharp decline in the tensile strength of the container material, owing to hightemperature. When the container cannot receive the set-up pressure, the containerwill crack by reason of the increasing pressure, then lead to the boiling liquidexpanding vapor explosion [2, 3].

The boiling liquid expanding vapor explosion accident may cause explosiveshock wave, vessel fragment, and giant fireball heat radiation, resulting in casu-alties and equipment damage. In this paper, using thermal radiation law, the hazardof LPG liquid expanding vapor explosion was evaluated [4].

96.1.2 Case Situation

There was an LPG storage and distribution station in the industrial district of thetown. The station to the southwest side was close to Hollow Fiber Products Co.Ltd. On the south side of the station was a road of width 5 m, with the rest of thesurrounding area as open space.

792 Y. Dong et al.

The factory covered an area of 12,000 m2; the area of construction was8,600 m2. The factory was surrounded by a 2 m high solid brick wall enclosure allaround. The storage tank area was set up to the southeast of the station; the westside of which was close to the hydrocarbon pumping station and gas cylinderwarehouse, North–south layout. Besides, the tank car loading and unloading col-umn was set up to the north of the filling room.

The construction area of the storage tank zone was 480 m2; the storage tankdepot set the four horizontal cylindrical tanks, followed by residue tank, 3#, 2# and1# LPG tank from south to north. The volume of tank was 20 m3, diameter was2 m, and maximum storage capacity 16 t. Moreover, the detailed performance datafor distance between the 3# tank and stations among buildings is shown inTable 96.1 [5].

The pressure tank equipped with a flammable liquefied petroleum gas, if sub-jected to external flame baking for a long time, would have its strength to grad-ually reduce. When the tank intensity decreased to a certain extent, the tank wouldburst suddenly, leading to pressure reduction, and then liquid would gasify rapidlyto cause burning. Consequently, there would be boiling liquid expanding vaporexplosion accident taking place. Thus, in order to provide a reference to enhancethe safe operation of the LPG storage and distribution station, the scope and size ofthe consequences for the boiling liquid expanding vapor explosion accident shouldbe researched.

Table 96.1 The distance between the tank and the station outside building

Distance (m) The tank’s distanceof standard

The 3# LPG tank’s distance

The station Fire bank toe line East 3 6South 9West 6North 13

Hydrocarbonpump

20 24

Cylinder base 20 30The filling room 20 39Loading column 20 33Fire pool 40 62Water pump

house40 80

Power distribution room 20 80The office 30 80Enclosing wall East 20 24

South 24West 116North 50

Outside the station Fiber products factory’swall

30 180

The road’s edge 20 34

96 LPG Storage Tank Fire and Explosion Accident 793

It was assumed that the LPG in 3# tanks were all let out during the region, andLPG tank boiling liquid expanding vapor explosion occurs under ideal condition,taking no account of factors such as temperature, wind direction, surroundingenvironment, and the effect of nearby tank fire and explosion caused by 3# tank.

96.2 Quantity Calculation of LPG Boiling Liquid ExpandingExplosion Consequences

96.2.1 Quantitative Calculation Results

The injury distance was calculated by fireball heat radiation calculation model.According to the different heat radiation flux, the heat accepted by the target wascalculated (shown in Table 96.2) [6, 7].

96.3 Analysis of the Boiling Liquid Expanding ExplosionCalculation Results

Table 96.3 indicates contrast and analysis between four parameters. The fourparameters were, the heat radiation flux at the distance between the LPG storagestation facilities required by the code for design of the urban gas [5], the heatradiation flux at the distance between the LPG storage station facilities, degrees ofdamage of the fireball thermal radiation in the required distance, degrees ofdamage of the fireball thermal radiation [8].

Table 96.2 The evaluation results of 16 t horizontal storage tank fire thermal radiation onhuman body damage

Radiationheat flux(kW/m2)

Targetdistance(m)

Equipment damage The harm to the humanbody

37.5 4.61 Equipments were damaged completely 100 % person death/1 min,1 % person death/10 s

25.0 5.65 In the absence of flame and long timeradiation, wood burning minimumenergy

100 % person death/1 min,severely person burned/10 s

12.5 8.00 A flame, burning wood, the lowestenergy of plastic melting

10 % person death/1 min, I-degree burn

4.0 14.12 Cause pain more than 20 s,but it would not blister

1.6 22.32 Have no sense of discomfortafter long-term exposure

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Table 96.3 The calculation results analysis of tank boiling liquid expanding vapor explosionaccident model

From 3 # tankdistance (m)

Thespecificationcondition toreceiveradiation heatflux (kW/m2)

The actualdistance toreceive heatradiation flux(kW/m2)

Under the standarddistance fireballradiation damage

Under the actualdistance fireballradiation damage

Fire banktoeline

East [37.5 12.5–25.0 Equipments weredamagedcompletely, 100 %person death/1 min, 1 % persondeath/10 s

10 % persondeath/1 min,I-degree burn,and woodwould burnwith flame

South 4.0–12.5 Cause pain morethan 20 s, butit would notblister

West 12.5–25.0 10 % persondeath/1 min,I-degree burn,and woodwould burnwith flame

North 4.0–12.5 Cause pain morethan 20 s, butit would notblister

Hydrocarbonpump

1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister

Have no sense ofdiscomfortafter long

Cylinder base 1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister


The filling room 1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister


Loading column 1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister


Fire pool \1.6 \1.6 Have no sense ofdiscomfort afterlong-termexposure

Have no sense ofdiscomfortafter long-termexposure

Water pumphouse

\1.6 \1.6 Have no sense ofdiscomfort afterlong-termexposure


(continued)


From Table 96.3, some conclusions could be obtained:

(1) Code required the distance from the fire-dike to the storage tank as 3 m, theheat radiation flux greater than 37.5 kW/m2, the injury degree that ‘‘equip-ments were damaged completely, 100 % person death/1 min, 1 % persondeath/10 s’’, considered as unaccepted category. However, during the actualdesign, the distance between the accident storage tank and fire dike was 6 m,hurt degree was ‘‘10 % person death/1 min, I-degree burn, and wood wouldburn with flame’’, which were considered as unaccepted category. And whenthe largest distance between the accident storage tank and fire dike was 9 m,the hurt degree caused by the hot radiation was accepted.

(2) The code required that the distance between the tank to the hydrocarbonpumping house, air bottle storehouse, filling house, loading/unloading pillars,wall of the station area, roads outside the station were 20 m, radiation heat fluxwas 1.6–4.0 kW/m2, the degree of injury was that ‘‘cause pain more than 20 s,but it would not blister’’, considered as accepted category. While the actualdesign distance was greater than 22.32 m, within acceptable range.

(3) Code required that the distance between tanks to the fire water tank, waterpumping house, power distribution, office, industrial enterprises were 40, 40,

Table 96.3 (continued)

From 3 # tankdistance (m)

Thespecificationcondition toreceiveradiation heatflux (kW/m2)

The actualdistance toreceive heatradiation flux(kW/m2)

Under the standarddistance fireballradiation damage

Under the actualdistance fireballradiation damage

Powerdistributionroom



The office \1.6 \1.6 Have no sense ofdiscomfort afterlong-termexposure


Enclosingwall

East 1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister


SouthWestNorth

Fiber productsfactory’s wall



The road’s edge 1.6–4.0 \1.6 Cause pain more than20 s, but it wouldnot blister


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20, 30, 30 m separately, the thermal radiation flux was less than 1.6 kW/m2,the degree of injury was that have no sense of discomfort after long-termexposure, within acceptable range, and the actual design distance wereacceptable.

96.4 Summary

LPG, as a fire explosive gas, when LPG storage and distribution station had takensome safety measures, but if not pay attention to safety management, there wouldgive birth to the boiling liquid expanding vapor explosion accident. Thoughsimulation on the instance, the calculation results displayed that the no harm radiusof the storage tank boiling liquid expanding vapor explosion was 22.32 m, and theliquefied petroleum gas storage and distribution station layout could fully satisfythe safety requirements when the explosion occurred. In addition, the design of theLPG station, which met the requirements of fire protection, was confirmed andcould provide design proposals for the spacing between the related constructions.Secondary explosion blast would cause great harm to the station equipment andpersonnel. Therefore, we should also strengthen the safety management anddevelop appropriate safety management system and an emergency rescue planaccording to the specific circumstances of the station area.

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Storage Transp 19(12):6–125. Sun WD (2007) GB50028-2006, code for design of city gas engineering 34(3):23–276. Fang JM (2009) The method of LPG tank fire and explosion accident consequence simulation.

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LPG Storage Tank Fire and Explosion

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