Oil refining process. Crude oil just extracted from the well in its original form has a very limited application. Therefore it is processed before it arrives on the market in the form of gasoline, fuel oil, aviation fuel, etc.

In the early stages of the oil industry the refining process was reduced to primitive distillation. The “black gold” was brought to the boiling temperature, with condensation of the oil products at different boiling points. Nowadays, oil refining is influenced by technological progress, and at the same time by the tightening environmental regulations.

The process of oil refining is as follows:

1. Preparation of crude oil for processing;
2. Primary crude oil processing;
3. Re-refinery;
4. Refining.

Preparation of oil for refining includes optional dehydration and salt removal to reduce corrosion of equipment and improve the quality parameters of oil.

The composition of crude oil includes various hydrocarbons, each of which has its value. That is why in the first stage the crude oil is separated into components by high temperature distillation. This method works because each component has a different condensation temperature and it can be condensed separately. Some of these components are ready to be delivered to the market. Other components are subjected to further processing to receive more expensive oil products.

Simple distillation removes small particles and adjusts oil chemical properties. The more complex transformations such as cracking and conversion is performed at large oil refineries. They produce higher quality oil such as petrol, and reduce the output of cheap oil such as black oil fuel and asphalt.

Oil refineries are located in close proximity to the source of raw material, oil pipelines, distribution points, and available labor and energy resources.

Compressor oil is used in the industry as a lubricant for the valves and cylinders of compressors; it is also used as a sealing medium for compression chamber and piston rods.

The main feature of that distinguishes compressor oils from other industrial oils is their operation in high-temperature environments and mixing with coolants. Therefore, compressor oils need to meet stringent requirements regarding chemical and thermal stability, as well as viscosity at low temperatures.

Compressor oils can be medium-load and heavy-duty. The medium-load air compressor oil doesn’t have additives. The heavy-duty compressor oil is produced from sulfur and low-sulfur petroleum by deep selective refining, followed by mixing with special additives, oxidation inhibitors, corrosion inhibitors, antiwear additives, etc.

When selecting a particular oil, it is necessary to pay attention to pour point (must be low), viscosity index (must be high), the possibility of chemical interaction with a coolant, their mutual solubility, and corrosion activity of the mixtures.

The parameters of HA-23 and HF-12-16 compressor oils (Table 1).

Table 1

Parameter	HA-23	HF-12-16
Kinematic Viscosity at 50ºС, мм/с2	22-24	18
Acid number mg KOH / g, max	0,07	0,03
Sulphated Ash content,%, max	0,005	–
Temperature ° C
flash point  °C, (min)	175	160
pour point °C, (max)	-38	-40
Oxidation resistance
Sludge content,%, max	0,02	0,005
Acid number after oxidation, mg KOH / g, max	0,6	–

Purification of compressor oils

Compressor oils containing water, solids and dissolved gases have significantly degraded performance properties. Their use therefore is highly undesirable. But it does not mean that the life cycle of the oil ends.

GlobeCore developed plants for purification and regeneration of compressor oils which remove water, dissolved gases and mechanical impurities. After processing, the compressor fluid has the initial properties, and can be reused for its intended purpose.

Сompressor oil purification equipment from GlobeCore:

• Reduces water content to 10 ppm or less;
• Reduces air content not 0.25% or less (vacuum degassing);
• Removes solid impurities to 1 micron;
• Extends lifetime of oil and compressor;
• Increases efficiency of compressors;
• Reduces downtime.

Silica gel. The industry uses various adsorbents to remove excess moisture. Today, there are many types of adsorbents of natural and synthetic origin. A special place among the adsorbers belongs to silica gel.

Silica gel is a dried gel obtained from oversaturated solutions of hydrated silica. The main feature of silica gel is its large specific surface area of approximately 1000 m2 / g. Silica gel is available on the market in the form of grains and spherical  granules.

Silica gel is widely used for drying:

• air
• industrial oils;
• carbon dioxide;
• hydrogen;
• chlorine;
• nitrogen.

It is also used for protection of equipment against corrosion.

After the adsorbent is saturated with moisture, it must go through a process of drying to be returned into service.

To solve this problem, GlobeCore has developed the SSZ-15B drying cabinets. They are designed to remove water from sorbents with particle size of not less than 1 mm.

The drying cabinet is equipped with a fan that ensures even distribution of heat through the layers of the dried material. The timer allows to hold a specified temperature during a preset time.

Comparing with the previous models, SSZ-15B has the following advantages:

• Operates at temperature up to 400 ° C;
• Maintains preset temperature;
• The door screw lock improves pressure sealing and eliminates paint stripping;
• Oven trays are removable, thus the cabinet can be used for preheating, heat strengthening and baking of other materials and parts.

The customer can request heating elements of up to 800 ° C, as required for the production processes, and a furnace temperature control system protecting the operator from burns.

Diagnosis of power transformers helps to identify potential problems and failures in order to prevent and remove them.

It is recognized that the analysis of breakdowns of transformer insulation also detects anomalies in oil-filled equipment. For example, when metal parts of the transformer are overheated, the oil accumulates gases, carbon and metallic particles. The most dangerous of them for the insulation system are conductive particles of carbon and wet fibers. Some faults are the result of oil contamination with solid particles. It depends on the amount, size and origin of such impurities. Hence, the analysis of oil contamination gives valuable information about the condition of the transformer.

The low flash point and the increased acid number indicate high local overheating and destruction of insulating liquid. The dielectric breakdown and an increase in dielectric tangent loss confirm the presence of moisture in the insulation system.

Diagnosis of power transformers. Acid number is also an important diagnostic parameter. It characterizes the presence of acid and oxidized products of aging paper insulation, which accelerate the formation of sludge in the oil. The maximum acid number is 0.25 mg KOH / g. The recommended value for fresh transformer oil is no more than 0.03 mg KOH / g.

Starting up a transformer after a long break in the cold season could have the dielectric strength reduced more than twice.

The most dangerous thing for the insulating liquid is being saturated with gases and moisture. Sudden changes in temperature and atmospheric pressure can cause small bubbles to appear in the oil, which, under the influence of oil flow and electromagnetic fields, concentrate in the paper insulation, making it even more vulnerable.

These days the Internet has adverts to “Buy waste oil.” These ads can cause some confusion and raise a number of questions. For example, why collect waste oil, which seemingly cannot be used as intended? Let’s try to understand.

In most cases, these ads are from people or companies involved in regeneration of waste oil. The regeneration in this case is the restoration of operational properties of oils for their further practical use. It means that the product returns to the operation cycle from which it came, or is applied in new operation. In fact, the authors of the “buy waste oil” ads do business and simultaneously reduce environmental pollution by recycling waste oil products.

If you decide to get involved in this business you need to know some details. The first step would be to purchase oil tanks for waste oil storage. GlobeCore is happy to help the starting entrepreneurs. We will manufacture custom-made containers of various sizes, depending on the oil collection rate that you can organize. You also need to purchase a vehicle to transport the oil to storage.

Next step is the development of connections with business owning oil-filled systems. These can be power companies, heat and power stations, factories with refrigeration equipment, etc. Almost any oil needs regeneration: transformer, turbine, industrial oils. But we must remember that oils must be collected separately, because mixing can significantly complicate subsequent regeneration. A weekly collection gives a rapid return on investments.

And now for the most important part. The “heart” of the business will be an oil regeneration unit. It defines the quality of the resulting product and the profit from selling it.

GlobeCore offers the following regeneration units:

• CMM-R. Oil restoration is a result of different techniques, including adsorption by Fuller’s earth. It cleans and lightens waste oils, restoring their important performance parameters. The sorbent is reactivated directly in the unit, and the oil is regenerated continuously: you earn money every minute.
• UVR. These units use a special sorbent. UVR main advantage is their versatility. In addition to purifying waste oils, UVR units can also purify, filter and lighten diesel fuel, gasoline, gas condensate, kerosene, etc. Unlike the CMM-R units, they do not reactivate sorbent.

UVR and CMM-R units together or separately can fully cover the waste oil regeneration needs of a business. Depending on processing volume, you may need to buy more units for increased capacity.

After the oil is regenerated it can be sold to producers of oil. They use it as a raw material for fresh oil production by adding the necessary additives. Here, GlobeCore can help too. A USB unit provides a high-quality mix of oil products with additives in accordance with a given formulation. The oil mixture does not separate for at least 180 days.

Transformers are one of the main components of the complex equipment of many energy (power plants, substations, converter devices) or industrial enterprises.

This equipment, depending on type and capabilities, can be operated in a wide range of conditions with varying load. Since transformers are an efficient energy transformation mechanism, it is important to maintain them correctly to preserve reliability throughout their lifetime, to avoid costly damage and repairs. However, even with regular checks, it may be difficult to prevent random failures.

About 80% of all failures of power transformers are caused by contamination and oxidation of transformer oil, the liquid insulation component of the transformer. Let us consider some of the typical failures and their cause, i.e. the influence of old transformer oil.

The most common failure is the malfunction of oil filled bushings with the entry of water. Oil is moisturized, its dielectric properties degrade and partial discharges and a breakthrough are the results.

Another common failure is the failure of the load tap changer. This is caused by incorrect setup of the contacts and the formation of oxidized film on them, which is the product of oil oxidation.

Some of the most severe malfunctions are the failures of solid insulation and windings. Sludge and sediment are deposited on the windings and insulation, weakening it and causing discharges and a breakthrough.

Another point to consider is that there is a reverse effect: damage and malfunction of some components also damage the oil. For instance, oil pump malfunction may contaminate the oil with metal particles etc. If rubber gaskets are damaged, water may enter the oil, which is one of the main factors of oil aging. Malfunction of oil level indicator may cause the oil to drop below the minimum or exceed the maximum level. These are but a few of the potential problems.

To detect problems with the insulation fluid and calculate the probability of failure, transformer oil must be tested.

The limits of physical and chemical properties, including the dielectric strength of the oil, new or used, are regulated.

Sampling of oil used in transformer tanks is performed once every one to three years depending on the load and power of the transformer.

For accurate results of oil testing or analysis, water, dirt or any other contaminant may not enter the oil sample. The sampling tap and the sampling vessel must be carefully cleaned. Prevent condensation on the walls of the sampling vessel by avoiding sharp temperature change. Open the vessel only after it has the same temperature as the environment.

The main oil parameters are tested. These include dielectric strength, color, gas, water particulate matter, additives, acid and alkali content, gas chromatography, etc.

An important oil parameter is the flashpoint. The lower the flashpoint, the higher the volatility of oil. Evaporation degrades oil quality, increases its viscosity and the content of explosive gases.

To measure the flashpoint, the oil is put into a closed vessel and heated. The vapor mixes with air and ignites on contact with flame or an electric spark. Flashpoint temperature and analysis of the accumulated gases may indicate the nature of internal damage to the transformer quite accurately.

The opposite parameter, the oil filter point, is measured for oil used in colder temperatures. This parameter influences operation of pumps, switches, filters etc.

Acidity of the oil is the amount of potassium hydroxide in milligrams required to neutralize free acid in one gram of oil. This is an indication of the oil’s aging.

Oil stability is tested by artificial oxidation of the oil. The final indications: percentage of sludge and acidity, are calculated for new oil only.

Other oil tests are auxiliary. Those parameters are not regulated. Those are density, static and dynamic viscosity. Sulfur content is only tested in transformer oil production process.

The results of the tests and measurements offer a good estimate of the oil’s condition and performance. Purification or regeneration measures may be planned based on this data as well.

Operation of power transformers involves such processes as external inspection, measuring oil temperature and load, phasing, oil testing, corrective and preventive maintenance, overhauls etc.

Inspection is performed once every six months. It includes checking the level of oil, checking for leaks and inspecting insulators.

Each transformer should be equipped with a thermometer measuring the temperature of the insulation liquid. This parameter should also be recorded into a special logbook.

If the transformer operates long enough, the temperature of the upper oil layers must not exceed 95ºC. At the same time the difference between the temperature of of the oil and the ambient temperature should not be more than 60ºC.

If the transformer is equipped with a thermosiphon filter, adsorbent color should be noted. It is most usually silica gel. Blue color means good adsorption ability, pink means that the sorbent is near exhausted.

Load is measured twice a year. First measurement is taken in May or June when power consumption is minimal, the second measurement is taken in December, at maximum loads.

Before engaging the transformer, the dielectric strength of the transformer oil and its chemical composition must be checked. Also, resistance of the winding to direct current and winding insulation resistance should be checked, breakers and relay protection is tested; the possibility for parallel operation is checked, along with phasing, secondary connection circuits etc.

Parallel operation of power transformers is possible when the following conditions are met:

• identical phase displacement groups;
• equal transformer ratios;
• equal impedance voltage;
• power ratio below 3:1.

Preventive maintenance is performed at least once every four years, including:

• external inspection and repair of possible problems;
• cleaning of insulation and the tank;
• removal of dirt from expansion tank and its washing;
• adding oil;
• checking of oil level indicator;
• changing of silica gel in the thermosyphon filter, if necessary;
• checking of drain valve and seals;
• checking grounding;
• taking oil samples;
• measuring insulation resistance and testing of insulation by increased voltage.

Overhaul involves core extraction and oil change. It is performed if necessary. The decision is made based on the results of inspection and tests. Overhaul is inly performed in special repair shops.

The most usual power transformer damage is short circuit of windings, insulation breakdown, mechanical damage to insulation in case of through fault and transformer oil leaks.

Every transformer should have a logbook with factory specifications, primary operation parameters and test results. Repair and servicing dates are also recorded.