April 28, 2010

Process Safety in LPG storage

At Vishakapatnam, the storage of LPG is being done in underground caverns as well as mounded storage. The underground storage facility is an engineering feat by itself.
"A safe method for the storage of large quantities of LPG is Cavern storage. In this method, LPG is stored in mined/artificial caverns at a depth of 160 m to 200 m below the sea level. Cavern is subjected to an external pressure by the saturated rock around the surface, which facilitates in the containment of LPG. The cavern storage is economical only for storage capacities above 50,000 mt and is feasible subject to the suitability of the rock, proximity to the ports with infrastructure for LPG receipt".
A nice description of the cavern is given by the company in this link.
For a draft paper on its construction and other details, please see this link.
HPCL, Visak has also constructed mounded storage of LPG. An article mentions that "Mounded storage of LPG i.e. creating a sand mound around the LPG storage vessels, which are placed above the ground level, is now increasingly being considered by HPCL as the best solution for protecting LPG vessels from BLEVE.
The mounded storage system provides the following advantages:
LPG stored in the form of mounded storage totally eliminates the possibility of BLEVE. The sand cover of 1 metre, which provides natural insulation from external heating, is adequate to outlast any fire in the surrounding areas. Water cooling systems are not required.
In addition, the mounding material provides good protection against most of the external influences like flying objects and pressure waves from explosions".

Read more of the article in this link

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