Oil transportation problems
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Heat treatment of crude oil: Heat treatment of crude oil involves heating the crude oil to a certain temperature and then cooling it to a specific temperature in a particular manner and at a certain rate. Through heat treatment, the form in which paraffin, asphaltene, and resin exist in crude oil can be altered, thereby changing the freezing point and viscosity of the crude oil. The low-temperature flow properties of crude oil can be improved under optimal heat treatment conditions. Forced current protection is a method in which the metal to be protected is connected to the negative pole of an external power source, and a protective current is supplied by this external source in order to reduce the corrosion rate. ? Underground oil tanks and semi-underground oil tanks: An oil tank in which the highest level of oil inside it is 0.2 meters below the surrounding ground level is referred to as an underground oil tank ； A tank in which the depth of the bottom below the ground surface is more than half of the tank’s own height, and whose highest oil level is no more than 0.2 meters above the adjacent ground, is called a semi-underground tank. The inlet pipe must not be connected to the upper part of the oil tank. If it is connected there, when the oil flows at high speed and sprays out in a misty form from a higher to a lower level, friction with the air increases the frictional area. The falling oil droplets strike the liquid surface and the tank walls, resulting in a sharp increase in static electricity; the voltage can sometimes reach several thousand volts or even tens of thousands of volts. Additionally, impurities floating on the oil surface can easily lead to corona discharge, which may cause the oil tank to explode and catch fire. Therefore, the oil inlet pipe cannot be connected from the top of the oil tank. The hazards of static electricity in oil storage and transportation: When static electricity accumulates in certain parts of pipelines, oil transfer equipment, and containers, and its potential becomes high enough that it overcomes the insulating capacity of the medium between it and another object that has no potential or a lower potential, a spark is generated between the two objects; this phenomenon is known as static discharge. This type of discharge can easily cause explosions and fires in areas with high oil and gas concentrations. Its danger and harm are very great.
I would like to ask: under what circumstances is the semi-underground storage method usually chosen, and what are its advantages?
The advantage of underground tanks is their excellent thermal insulation; they are less affected by daily changes in atmospheric temperature, which reduces oil evaporation losses. Moreover, for oils that need to be heated, such tanks help to lower energy consumption； Since non-metallic materials are used extensively, less steel is required ； The risk of fire is low; even if a fire breaks out, it is unlikely that oil will spill and pose a threat to other tanks ； It has a certain degree of air concealment capability. The semi-underground oil tank is actually a modified version of an underground tank, designed to overcome the limitation imposed by the groundwater level on the tank’s height.