STORAGE TANKS & VESSELS - STORAGE OF HIGH PRESSURE GASES PDF Print E-mail
Written by Norrie   
Monday, 24 May 2010 21:43
Article Index
STORAGE TANKS & VESSELS
Storage Tanks
Floating Roof Storage Tanks
Floating Roof Seals, Legs, Water Drain & Access Ladder
STORAGE OF HIGH PRESSURE GASES
1. SPHERICAL STORAGE (STORAGE SPHERES)
2. CYLINDRICAL STORAGE VESSELS
3. GAS CYLINDERS
STORAGE OF LOW PRESSURE GASES
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STORAGE OF HIGH PRESSURE GASES

Gases are usually stored under high pressure, often in liquid form. Liquefied gases take up very much less volume than in the gaseous state. The decrease in volume also decreases the size of the storage vessel. Different gases need different pressures in order to condense them at atmospheric pressure. It is often necessary to use refrigeration together with pressure to change a gas to liquid. In addition to liquefaction decreasing the gaseous volume, liquids are also easier to transfer from place to place.

A stored liquefied gas will remain as liquid at a specific temperature. For example, liquid Propane at 100 °F has a vapour pressure of 190 psia. This vapour pressure changes with temperature change. In winter when ambient temperature is low, the storage pressure of liquid Propane will be lower.

As a further example, LPG (Liquid Petroleum Gas), used for domestic purposes, is stored in small cylinders for ease of carrying. LPG may be pure Butane which has a vapour pressure of 51.6 psia at 100 °F. For winter use in cold countries, domestic LPG will consist of a high percentage of Propane or pure Propane because Butane may not give sufficient pressure.

As LPG gas is being used for heating or cooking, the pressure above the liquid tends to decrease. This causes the LPG to boil and produce gas to maintain its vapour pressure. In the case of Propane, if gas is used at a faster rate than the boiling liquid can produce, then, as the pressure decreases, the temperature also decreases. When the pressure above Propane liquid reaches atmospheric pressure, the temperature of the Propane will be at – 44 °F, this is the boiling point of Propane at 14.7 psia.

The pressure storage of liquids is therefore dependent on the vapour pressure of the liquid at a specific temperature. The type of storage vessel and its construction materials therefore depends upon the volatility of the liquid.

Following are some designs of storage vessels for high pressure fluids :



Last Updated on Monday, 24 May 2010 21:47