Tag Archives: oil reclaiming

Oil filtration

During operation, transformer oil accumulate contaminants, which can form various chemicals. These substances reduce the oil’s performance and are, of course, undesirable.

Operation of the transformer becomes unstable. To prevent this, transformer oil is filtered and purified. Some of the methods are discussed in more detail below.

The first stage of transformer oil purification is mechanical. This is a superficial treatment to remove particulate matter and water. The next step is deeper purification performed in vacuum with heating.

The first two stages are, in fact, preliminary. The main process involves various chemicals.

One of the methods is purification of oil with a 98% sulfuric acid solution.

In comparison to other chemical purification methods, the use of sulfuric acid has a significant drawback. Beside reacting with the contaminants, the acid also adversely influecnes the structure of the oil, making it somewhat unstable. Additional processes are required to resolve that problem.

The nature of selective purification is evident from the title. Speical solvents are introduced into the oil to remove specific impurities.

De-waxing is another widely accepted process. In this process, oil is treated with special solvents: acetone, toluene, bensol etc, to remove solid contaminants.

It should be noted that chemical methods influence oil’s stability, but extend the oil’s service life at the same time.

It should also be remembered that any purification process should end with finishing purification, closing the cycle of oil processing and filtration. This is usually done by contact method.

This means that the oil is mixed with special materials, usually clay or bleaching earth. The materials are then mixed and heated. Heating facilitates acviation of all sorbents in the clay.

These absorbents capture contaminants. Deep filtration separates oil from the clay. When selecting adsorbent, it is necessary to pay attention to the content of moisture. It should be suffucient to make production efficient and to make processed oil compliant with specifications.

The most interesting technology today involves the use of bleaching clays (Fuller’s earth). Globecore manufactures a range of CMM type units for filtration of various oils with the use of Fuller’s earth. The advantages of the design are the ability of multiple reactivation of the sorbent, mobility, simplicity of operation and high quality of the output product.

Downtime is significantly reduced by the ability to reactivate the sorbent without the need for frequent replacement, thus increasing process efficiency.

Using of the turbine oil: benefits and testing

Oil used in various industries are divided into various types and subtypes. Physical properties and chemical composition divide oil into classes and categories. Various industries require specific oil types.

There is a group of oils for the energy industry, which includes turbine, dielectric (transformer) and compressor oils. Specific requirements are applied to each of the categories.

Also, depending on oil type, moisture and gas content are regulated, as well as some other specifications.

Since oils inevitably age with time under the influence of water and solid particle contamination, the natural process of oil consumption becomes a problem related to the costs of repairs and downtime, with the obvious adverse effect on company revenues.

In the case of turbine oil, sediment on the surface of internal parts may lead to serious problems, including wear of regulation devices, command valves etc. In turn, moisture promotes corrosion, dilutes anti-oxidation additives and increases foaming, which also degrades lubrication.

Therefore, power generation facilities implement systems for turbine oil quality control both during operation and storage. Neglecting the regulations may cause serious problems for turbines, including failures and extended downtime due to complete or partial breakdown of equipment.

Contamination of turbine oils leads to degradation of their original properties and reduces efficiency of oil filled equipment. In the most severe cases this will cause serious malfunctions, requiring long costly repairs.

Coming back to the issues of equipment downtime due to failures and repairs, let us refer to the statistics. Research shows that in similar situations in power plants (thermal and nuclear), turbine adjustment system failure rate has grown in recent decades, including failures of internal rotating part bearings. All of the cases were related to contamination of turbine oil.

The causes named above, after a look at power plant failure statistics, require efficient solutions.

The simplest and the most obvious solution is oil quality control and oil replacement. In practice this is, however, complicated, spawning several problems. First, complete removal of oil, sediment and other contaminants is impossible. Second, the disposal of used oil is a problem in itself. Constant disposal costs may eventually exceed estimated repairs cost.

The optimal solution, all things considered, is purification and regeneration of used turbine oil. Various types of mobile plants connected directly to the turbine assembly from which contaminated oil is drawn, removal gas and water, filter out solid particles and generally fully restore the oil to its original specifications.

For instance, the CMM mobile oil plants degas, remove contaminants and sediment from turbine oil. Among the advantages of these units is their capability to process the oil in one pass, significantly extending oil service life.

Depending on the needs of the facility, CMM plants may be either mobile or stationary. For larger facilities, CMM plants come with extra features, from additional filters to additional regeneration sections.

The main issues for any business are the possible profit and loss. The cost of regenerating 1 ton (depending on the type of purified, regenerated and lightened product) varies between US$6.5 to US$35. At the same time, disposal of industrial waste is a costly affair. Oil purification plants pay for themselves in a rather short time of 5 – 6 months at current prices.