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1. Mechanical impurities
Mechanical impurities refer to the sum of the amount of substances in petroleum or petroleum products that are insoluble in oil and specified solvents. Such as mud sand, dust, iron filings, fibers and certain insoluble salts. Mechanical impurities can be removed by precipitation or filtration.
For light oil, mechanical impurities will clog the oil path and promote raw rubber or corrosion; for boiler fuel, it will block the nozzle, reduce the combustion efficiency, and increase fuel consumption; for lubricating oil, it will damage the oil film, increase wear, and block oil filtration To promote the formation of carbon deposits. So it is called mechanical impurities. The mechanical impurities come from the external pollution in the production, storage and use of oil products or the wear of the machinery itself. Most of them are sand and carbon deposits, as well as some organics that are difficult to dissolve in solvents caused by additives. Metal salt. The determination is carried out according to GB / T 511-83 Petroleum Products and Additive Mechanical Impurity Determination (Gravimetric Method). The process is as follows: Weigh 100g of test oil and heat to 70 ℃ to 80 ℃, add 2-4 times of solvent, filter on the paper in the empty bottle which has been weighed, wash the filter paper bottle with hot solvent and weigh again. The difference between the weight of the quantitative filter paper before and after is the weight of the mechanical impurities, from which the mass fraction of the mechanical impurities is determined.
2. Precipitation
Total sediment refers to all inorganic and organic matter insoluble in solvents (such as toluene) in oil products, and is one of the specifications of medium and heavy fuel oils. The sediment is often some mechanical impurities, or it is introduced by processing, transportation, and storage processes. High sediment content can easily block filters, nozzles, valves, etc., and can cause or increase the wear of the machine parts. The measuring principle is to put a certain amount of oil sample into a porous filter and continuously drop into the hot solvent. All the components soluble in the solvent are drained through the filter, and the remaining is the insoluble solvent. ,unit weight%. The determination standard can be checked under GB / T6531 or ISO 10307.
The main problems of precipitation and impurities in lubricating oil are caused by the following three aspects:
(1) Due to the impurities existing in the equipment system before adding new oil, some impurities are often generated in the new equipment and equipment used for a long time. For this, the equipment is generally washed with flushing oil until it is contained in the oil The impurities reached the specified target.
(2) The storage, transportation and use of lubricating oil are not carried out in accordance with the prescribed operating requirements, resulting in the entry of impurities in these processes and affecting the quality of the oil.
(3) The deposits are mainly high-viscosity internal combustion engine oil with a large dosage, which will precipitate to varying degrees at low temperatures. This deposit is not an impurity generated after long-term use of the equipment, or external impurities enter the contaminated oil, so it has no effect on the normal use of oil.
For the above three causes of precipitation and impurities, different treatment methods need to be adopted:
Impurity treatment methods in the equipment system before adding new oil: different equipments are equipped with different lubricating oil systems, some systems are larger, and some systems are smaller. Regardless of the size of the oil system, the oil system, oil pump, oil Cooler, oil filter and other equipment and valves, pipelines and instruments, etc., through the pipeline and the various lubrication points of the machine itself, bearing bush, bearing box, crankcase oil hole, oil groove to form a more complex set of lubricants system.
New equipment: when installing the lubricating oil pipeline system, the inside of the pipe must be kept clean, but this is not enough. The oil circulation system of the unit should also be rinsed with oil circulation. If the oil system is not clean and there is dirt in the pipe, it will affect the unit During normal operation, the bearing bush may even be burned out, so oil circulation flushing is provided to ensure the long-term stable operation of the unit.
Long-term use equipment: There are often some impurities in the equipment used for a long time. For this, the equipment is generally washed with flushing oil until the impurities contained in the oil reach the specified index, and the flushing oil after washing should be discarded or Use it instead. If you want to use these flushing oils, you must carry out the corresponding oil analysis tests, and you can use them after the cleanliness reaches a certain standard, and it is required to strengthen filtration and cut water before use and during use.
