Norms of turbine oil purity
Much research has been conducted especially in the areas related to oil product use. New challenges have arisen. Environmental concerns, depletion of mineral resources, monopoly on oil supply and internal problems in oil exporting countries all compel to look for alternatives and diversify resource supply and recycling.
As for the energy facilities, which use turbines and motors, an important issue is to save on treatment, purification and reclamation of turbine oil.
Equipment service life is directly related to the service life of liquids and turbine oil quality. Purification of oil by one purity class more than doubles the resistance of equipment to aging.
The purpose of turbine oils is cooling and lubrication of movable parts in the turbine. Turbine oils are used in steam, gas and water turbines, turbo compressors etc. The oil is also used as a cooling in turbine control systems, which guarantees quality of the product (energy), in hydraulic and circulation ystems not only in turbine equipment but also in other industries.
Turbine oil, just as any industrial liquid, must comply with certain norms and regulations. The most important of these is the ability of the oil to resist aging, i.e. oxidation. When water, air and other contaminants enter the turbine oil, the oil becomes contaminated. Besides, oil may form sediment, which is difficult to remove from the internal components, and adversely affects the equipment and the oil itself. Water promotes corrosion. Formation of sediment degrades control systems and increases wear on bearings and supports. All of the above leads to reduction of oil and equipment service life.
Due to high quality of turbine oil production, as well as introduction of additives, the properties of oil the are maintained at required levels and the process of aging is slowed.
Some of the critically important norms of turbine oil quality are:
- Absence of water, visible sediment and solid particles;
- Absence of solved sediment;
- Acid number below 0.3 mg KOH/g;
- Sediment content below 0.15 % volume.
If sample analysis shows that the above parameters are exceeded, the oil must be replaced.
When turbine oil must be replaced, costs are estimated. These come from selected disposal method, purchase of new oil or reclamation of oil.
The most efficient way is reclamation of used turbine oil.
Regeneration methods are divided into physical, chemical and combined physical and chemical methods.
Physical methods allow removal of solid matter, formed in the oil in the process of operation as particles of tar or varnish. Usual processes include gravity settling, centrifuges, sometimes electrostatic, magnetic and vibration methods, various filters, moisture traps and vacuum degassing.
The simplest method of turbine oil purification is gravity settling, sedmination of water and solid particles by the force of weight. The simplicity of this method does not speak of its advantage. Process duration and the ability to only remove large particles makes it only fit for pre-treatment.
Filtration allows to remove resigns and other solids from oils. The process is divided into the use of coarse filter and fine filters. Usual filtration media used are felt, fabric, paper, metal or plastic meshes. Combination of several methods of filtration in one process increases its efficiency.
There are several other methods of purification of used turbine oil, for instance, centrifugal removal of water and contaminants. However, the most used method is the combination of physical and chemical processes along with several types of filtration and purification. Adsorption and selective solution in a complex system with degassing, drying and filtration sections allows to purity turbine oil with complete restoration of its specification in one processing cycle.
It is recommended to use CMM types mobile plants for regeneration (purification) of turbine oils. The processing capacity of the largest plants is 4 m3/hour.
According to the accepted oil purity norms, the finished product from the CMM type plant complies with the following:
- Purity class 9 from original class 13
- Moisture content by weight below 10 g/t
- Max oil output temperature 55ºС
- Full removal of oxidation products and sediment
Complete turbine oil purification and regeneration systems are quite simple in operation and servicing. They quickly pay for themselves and feature high efficiency, which makes these plants an affordable and indispensible component of any industrial facility.