HAZARDS ASSOCIATED WITH THE HANDLING OF LPG AND THE DESIGN OF FIRE EXTINGUISHING SYSTEM FOR LPG GODOWN

Abstract

Episodal incidents from liquefied petroleum gas godowns storage tank farms have huge consequential effects particularly when the godowns/storage yards have now come within the urban areas/municipal limits. Many LPG godowns are located in the middle of residential areas, making the surroundings of LPG godowns congested and populated. The number of LPG godowns has been increasing at an alarming rate, to .keep pace with the increasing use of LPG vehicles, commercial consumption and domestic use expansion. In India most of the LPG godowns have not installed the fire-extinguishing facilities like sand. blasting, water deluge systems, etc. Thus, the LPG godowns pose serious hazards in nearby areas. LPG is transported and stored in liquid phase in closed tanks under sufficiently high pressure. In case of an accident an abrupt tank unsealing large quantity of evaporating gas liquid (gas) gets release, and, if fire breaks out, the accumulated energy causes destruction to the inhabited areas, property and the LPG storage facility itself. The fire engulfing a LPG storage facility may cause BLEVE leading to deflagration (due to high pressure generated at high temperature in the storage cylinders/tanks/tankers), mechanical burst and disintegration of the tanks resulting in projectiles of debris/broken parts and components, vapour cloud explosion (VCE), gas release, etc. Although thermal effects usually reach shorter distances than blast or toxic clouds, they often affect buildings and equipment nearby, thus originating a dangerous domino effect. Unless properly stored and handled, LP gas cylinders are a safety risk because they are pressurised, with the risk of a violent release of contents if the container is punctured, flammable, if the contents are released and mixed with air and an asphyxiates , if the contents displace the air in an area occupied by humans or animals. The present work contained in the dissertation discusses the effects in case of accidental release of LPG and provides detailed procedure of calculation for BLEVE and pool fires. The literature has been extensively reviewed and the available correlations have been to calculate its duration and flame height at a distance for an isolated LPG tank and the effect of thermal radiation on the population at various locations. It is found that the heat intensity at a distance has profound impact on the number of fatalities in the population. Safe distance in case of BLEVE and pool fire from leakage/spillage is also calculated and shown graphically. The episodal situation is analysed - using event tree and fault tree techniques and a design for leakage/accidental the fire-extinguishment system using water distribution network has been presented to protect the LPG godown from rupture and consequent fire.