What to do if the acid value of turbine oil exceeds the standard?
November 18, 2022
Turbine oil, also known as turbine oil, usually includes steam turbine oil, gas turbine oil, hydraulic turbine oil, anti-oxidation turbine oil, etc. It is mainly used for lubrication of turbine oil and sliding bearing, reduction gear, governor and hydraulic control system of the associated unit. The functions of turbine oil are mainly lubrication, cooling and speed regulation. However, in the actual production process, customers often report that water and impurities are always filtered, purified and maintained by the turbine oil filter. Why do they sometimes say that the acid value of the turbine oil exceeds the standard and is unqualified during the oil inspection during maintenance? What harm will the acid value cause to the turbine oil?
1. Harm of exceeding acid value Turbine oil of steam turbine is a general term for inorganic acid and organic acid, with the unit of mgKOH/g. Content acid value, and water-soluble PH. Generally, the acid value is controlled to be less than 0.2mgKOH/g during operation. The acid value can measure the degree of oxidation and deterioration of lubricating oil during use, and has a great impact on the use of lubricating oil. The high acid value of lubricating oil indicates that its high organic acid content may cause corrosion to mechanical parts, especially in the presence of water. Inorganic acid in the acid value mainly consists of water-soluble PH, which can participate in the corrosion of each oil system of steam turbine, and its harm is more than that of organic acid. 2. Reasons for exceeding acid value There are two reasons why the acid value exceeds the standard. One is the poor quality of the oil, which is the decline or even loss of the anti-oxidation ability of the running oil, leading to a sharp rise in the acid value of the oil; Second, the oil system is overheated or partially overheated, leading to the gradual increase of acid value. 3. Methods to reduce and control the excessive acid value If the acid value of turbine oil exceeds the standard, the vacuum oil filter can be used to dewater and filter impurities, and then the adsorption regeneration method can be used for treatment during operation. The acid components, suspended substances, precipitates, polar substances, etc. in the oil can be removed by adsorption and regeneration, and the acid value in the oil can be reduced to 0.03mgKOH/g. The device uses a special purifying agent, and the treated oil will not damage the basic components and oxidation resistance of the oil.
In addition, there is a problem of oil mixing in the process of oil supplement, oil change and oil regeneration of turbine oil. Improper oil mixing will produce a large amount of sludge, which will greatly increase the particle size of the oil, block the oil suction screen of the system, make the oil supply of the oil pump insufficient and the system oil pressure drop, which will lead to serious accidents of the unit. The sludge will deposit in the oil cooler, which will affect the oil cooling effect. The main reason for producing a large amount of sludge during oil mixing is that there may already be a large amount of dissolved sludge in the running oil. When adding new oil, the condition of high acid value of sludge in the old oil is changed instantaneously, so a large amount of sludge will be separated out in a short time. During the use, the following routine maintenance shall be carried out: 1) It is most important to ensure the cleanness of all links of oil use. First of all, oil storage cylinders, oil drums and oil extraction tools must be clean. Water, dust, impurities and other kinds of oil products must not be mixed in storage and transportation. Tools must be specially used for oil, and oil must not be loaded in galvanized barrels. After maintenance, oil pipelines, oil tanks, oil filters and oil coolers must be cleaned and free of water or residues before oil installation or replacement. Especially after the system is cleaned with metal cleaning agent, it is not only necessary to drain the system, but also to flush the system with new oil. New oil can be installed only after the flushing oil has passed the anti emulsification test. 2) Control the oil temperature at 40 °C~60 °C. 3) Drain the sediment and water at the bottom of the oil tank regularly or irregularly. 4) Professional coalescence separation oil filter equipment is used to prolong the service life of oil products.
