Cleaning oil tanks is the removal of sludge that has accumulated in oil tanks. The following describes the sludge deposited in the crude oil tank. Sludge is usually composed of inorganic and organic sediments, inorganic sediments containing rust, sand, mud, wet carbon, etc. Organic sediments contain oil, wax, asphalt, etc. The analysis of the sediment in the crude oil tank found that oil and wax accounted for 80~95% of the entire sludge, moisture accounted for 10~20%, and inorganic sediment in addition to water did not account for so much. Although many people think of sludge as composed of detrite oil, aging waste, or useless components like sand and mud, the vast majority of it is useful oily material. Sediments therefore contain many beneficial components that should be recovered and reused as much as possible.
General crude oil contains 2 to 5% wax, which precipitates during storage and becomes the main component of the sediment. When the wax is buried in the ground, it is melted by the Earth's heat, dissolved in the oil, and once it is extracted and placed under the cooling temperature of the atmosphere, it forms a sediment.
Through the precipitation test of several representative crude oil deposits, it is found that if left alone, most of the sediment composition will be formed within a month, and after three months, the sediment hardly changes, nor can it be seen that there is a change in its characteristics. (Viscosity, specific gravity, liquid point, etc.)
The sludge is mainly formed by the above-mentioned wax deposits, other sources are the alienation of crude oil, the coarse particles of wax formed by heating and the mixture of water emulsification. If light crude oil (and a multi-capacity solvent) is injected into a tank containing heavy crude oil (or heavy crude oil is injected into a tank containing light crude oil), the asphalt deposits dispersed in the heavy oil are exposed due to the separation of the malt coating and the polymer hydrogen carbide components and the merger of the polar asphalt particles into the sediment. As a typical example of this phenomenon, the sediment in the tank contains bitumen and crude oil or is a large carbon or carbon/hydrogen material.
The above-mentioned asphalt sludge is formed by the separation of the solvent containing the malt layer and the polymer hydrogen carbide, and a similar phenomenon can be produced by heating. That is, the covered malt layer and macromolecular hydrogen carbide components are melted and dissolved by the surrounding oil, and the asphalt is exposed. When the liquid cools rapidly, its surface layer will not return to its initial state, and at the same time, the particles of the asphalt merge to form a sediment.
When the wax deposits are heated, the individual wax particles melt and fuse, and once cooled, they turn into larger particles and smaller deposits that are difficult to disperse again. Because asphalt contains polar groups, it forms emulsion when it touches water. The reason that heavy oil is more easily emulsified by water than crude oil is that heavy oil contains bitumen. As mentioned earlier, sludge is first formed by the precipitation and setting of wax, and then by mixing the alienated crude oil, heating and mixing with water.
Foreign manual treatment of oil storage tank sludge picture
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