Storage above ground is divided into two categories, normal temperature high pressure storage and normal pressure low temperature storage.
1. Normal temperature high pressure storage
LPG normal temperature high pressure storage refers to that status of LPG storage is in ambient temperature and relative saturation pressure. For example, 50℃ propane saturation steam pressure is 1.7MPaA, N-butane 0.49MPaA, Isobutane 0.68MPaA. Due to high storage pressure, ball tank is often applied. Because of ball tank wall thickness and limit of production method, propane ball tank normally is no more than 5000m3. For big tank zone, the result is that there will be a large number of tanks. Therefore it should be required that there should be large room for safety distance.
2. Low temperature normal pressure storage
Storage of LPG low temperature normal pressure refers to that status of LPG storage is normal pressure and temperature is saturation temperature in normal pressure. For example, in normal pressure saturation temperature of propane is 42℃, N-butane -0.6℃, and isobutane -12℃. Since it is normal pressure storage, arch tank is normally applied. There is not too much limit in tank capacity. But too much capacity will be too costly, so it is better that tank volume is normally no more than 100000m3. Cold preservation measures should taken due to low temperature storage. In addition, there is high requirement for steel material of tank. At present double wall metal tank is applied for storage of propane. Internal wall is made of low temperature steel. Even though there is favorite cold preservation measure, during storage, tank and pipeline can absorb heat from environment to produce evaporated gas. Therefore a set of freezing system should be equipped.