Does the diesel have a shelf life? (Small knowledge of oil)
If diesel oil storage time is long, the burning rate will be gradually reduced. In diesel refining, the oil products consist of the mixture of hydrocarbons, mainly containing 918 carbon alkyl paraffin, naphthenic or aromatic hydrocarbons. Its physical characteristic is between gasoline and heavy oil, boiling point is 170 ℃ to 390 ° C, the specific gravity is 0.82 to 0.845kg / l.
But seeing from the actual situation, the finished oil is usually directly into the market. If they meet with water, copper, zinc and other metal in storage, they will accelerate the decomposition.
At 20 ° C,the warranty period of diesel is at least 12 months. The more unstable substances and volatile componentsin the oils, the easier it’s to degenerate. For example,the diesel catalytic cracking isn’t hydrotreating, the color changeswithin two days.
From the point of the inspection and sample reserving, the general sample reserving time of diesel is 3 months, indicating that diesel can be ensured product quality within at least 3 months (in line with national standard).
But seeing from the actual situation, the finished oil is usually directly into the market, will not save for 3 months or more.
The diesel will deteriorate for long-term storage.
Diesel deteriorationin the storage and transportation process is mainly oxidized deterioration. Its ability to resist metamorphism is known as diesel storage stability. Diesel with good storage stability can better keep its color not deepen, the actual colloid change little, basically not generate sediment in the storage and transportation process, so it’s suitable for longer-term storage. In general, straight-run distillation diesel’s storage stability is better, and it’s not easy to degenerate in storage process, but catalytic diesel’s storage stability is poor, and it’s easy to deteriorate in storage process. The important reason for the deterioration of diesel stability and quality is the oxidation. The oxygen inhaling stability of diesel oil is closely related to its source, processing method and chemical composition. Some of the unstable components of diesel oil, such as unsaturated hydrocarbons, especially conjugated dienes, naphthenic aromatic hydrocarbons, etc., easily react with oxygen to produce oxygen-containing functional groups, and then polymerization and condensation reactions.
If the diesel contains more easily oxidized components (such as conjugated olefins and naphthenic aromatic hydrocarbons, etc.), its oxygen oxidation capacity is strong, various physical and chemical properties change in the storage and use process, the quality also decline, which will directly impact on the diesel engine power and economy, in severe case it will lead to the quality of diesel fail or the engine can not work properly. The oxidative deterioration of diesel is related to temperature and oxygen pressure. With the increase of temperature or the increase of oxygen pressure, the oxygen absorption, the total velocity constant of oxygenation reaction and the maximum amount of oxygen inhalation increase, and as the oxygen uptake increases, their acidity increases, pentane insoluble substances increase, the color becomes darker. Resulting that the color of diesel becomes darker, acidity increases, glial and insoluble substances increase. The more the number of unstable components in the diesel, the longer the contact with oxygen, the higher the stored temperature and oxygen pressure, the more chance it will react with oxygen, oxygen absorption will inevitably increase. Diesel in the region of higher temperature (such as the South) or higher oxygen pressure (such as low altitude, well ventilated) has bigger amount of oxygen absorption and easier deterioration than in the region of lower temperature (such as the North) or lower oxygen pressure (such as high altitude, poor ventilation), should shorten its storage period accordingly.