When repairing main gas pipelines, it is necessary to comply with the safety regulations set forth in GOSTs, OSTs of the system of labor safety standards (SSBT) and other regulatory documents.

The main production hazards and hazards at the facility are as follows:

* in a relatively narrow lane, in the working area, work is carried out and transport operations are carried out at the same time, which leads to the concentration of a large number of mechanisms in separate places and the movement of vehicles past moving people in cramped conditions;

* dangerous work associated with lowering pipe lashes into the trench, etc.;

* saturation of the air with harmful gases, gasoline vapors, dusty splashes of insulating mastic during insulation work;

* the possibility of electric shock during welding;

* work is often carried out at night without sufficient lighting of the working area and workplaces.

Therefore, the construction site, work sites, workplaces, driveways and approaches to them in the dark must be illuminated accordingly. Illumination should be uniform, without blinding effect of lighting fixtures on workers. During assembly and welding works, stationary lamps with a voltage of 220 V, suspended at a height of at least 2.5 m, should be used to illuminate workplaces at night. The voltage of portable lamps should not exceed 12V.

The processes of increased danger in the construction of pipelines are loading, unloading pipes and pipe sections by lifting means, transporting them by pipe carriers and pole carriers.

The harmful effects of harmful substances on the human body

At the operated facility, the main explosive, hazardous and toxic substances are: gas, ethyl mercaptan (odorant), methanol.

Maintenance personnel, working at an operating facility, must know the composition, basic properties of gases and their compounds. The effect of harmful substances used in production on the human body depends on the toxic properties of the substance, its concentration and duration of exposure. Occupational poisoning and diseases are possible only if the concentration of a toxic substance in the air of the working area exceeds a certain limit.

Table 6 - Information on hazardous substances at the facilities of OOO Gazprom transgaz Tchaikovsky

Natural gas is a colorless mixture of light natural gases, lighter than air, does not have a noticeable odor (an odorant is added to give it a smell). Explosive limits 5.0 ... 15.0% by volume. MPC in the air of industrial premises is 0.7% by volume, in terms of hydrocarbons 300 mg/m 3 . Self-ignition temperature 650°C.

At high concentrations (more than 10%), it has a suffocating effect, since oxygen deficiency occurs, as a result of an increase in the concentration of gas (methane) to a level not lower than 12%, it is transferred without noticeable effect, up to 14% leads to a mild physiological disorder, up to 16% causes severe physiological effect, up to 20% - already deadly suffocation.

Ethylmercaptan (odorant) - used to give a smell to gases transported through the main gas pipeline, even in small concentrations cause headache and nausea, and in high concentrations they act on the body like hydrogen sulfide in a significant concentration is toxic, acts on the central nervous system, causing convulsions, paralysis and death.. MPC of ethyl mercaptan in the air of the working area is 1 mg/m 3 .

The odorant evaporates easily and burns. Poisoning is possible by inhalation of vapors, absorption through the skin. It is similar in toxicity to hydrogen sulfide.

The concentration of vapors of ethyl mercaptan 0.3 mg/m 3 - is the limit. Vapors of ethyl mercaptan in a certain mixture with air form an explosive mixture. Explosive limits 2.8 - 18.2%.

Methane - in its pure form is not toxic, but when its content in the air is 20% or more, the phenomenon of suffocation, loss of consciousness and death is observed. Limit hydrocarbons exhibit more toxic properties with increasing molecular weight. So propane causes dizziness when exposed to an atmosphere containing 10% propane for two minutes. MPC (maximum permissible concentration) is 300 mg / m 3.

Ethylmercaptan interacts with iron and its oxides, forming iron mercantides prone to spontaneous combustion (pyrophoric compounds).

To ensure safe conditions for performing various types of construction and installation work and to exclude injuries, workers and engineering and technical personnel must be well aware of and follow the basic safety rules.

In this regard, workers and engineering and technical personnel involved in the construction or repair of pipelines are trained in their specialty and safety rules. The knowledge test is drawn up with the relevant documents in accordance with the current industry regulations on the procedure for testing knowledge of the rules, norms and instructions for labor protection.

Prior to the start of work on the repair of gas pipelines, the organization operating the gas pipeline is obliged:

* give written permission for the performance of work on the repair of the gas pipeline;

* clean the cavity of the gas pipeline from condensate and deposits;

* identify and mark the places of gas leakage;

* disconnect the gas pipeline from the existing pipeline;

* identify and mark the location of the gas pipeline at a depth of less than 40 cm;

* provide repair and construction sites with a connection to the control room, the nearest compressor station, the nearest lineman's house and other necessary points;

* ensure technical and fire safety during repair work.

After switching off and depressurizing the gas pipeline, grading and overburden work is carried out.

The gas pipeline is opened with an overburden excavator in compliance with the following safety conditions:

* the opening of the gas pipeline must be carried out 15-20 cm below the lower generatrix, which facilitates the slinging of the pipe when it is lifted from the trench;

* It is prohibited to carry out other works and to keep people in the area of ​​action of the working body of the overburden excavator.

The location of mechanisms and other machines near the trench should be behind the prism of soil collapse.

Hot work on the gas pipeline should be carried out in accordance with the requirements of the Standard Instructions for the Safe Conduct of Hot Work at Gas Facilities of the USSR Ministry of Gas Industry, 1988.

Electric welders who have passed the established certification and have the appropriate certificates are allowed to perform electric welding. When working with a cleaning machine, make sure that a foam or carbon dioxide fire extinguisher is installed on it.

The operation of turbine oils over time leads to its aging. This is an inevitable process, because these oils have to work in rather difficult conditions, since the oil systems of turbogenerators are constantly exposed to a number of adverse factors.

Factors Affecting Turbine Oil

Influence of high temperatures

When oil is heated in the presence of air, enhanced oxidation of the oil product occurs. In parallel, other characteristics of oils also change. Evaporation of low-boiling fractions leads to an increase in viscosity, a decrease in flash point, a deterioration in demulsibility, etc. The greatest heating of turbine oils is observed in turbine bearings (from 35-40 to 50-55 ºС). Oil heating occurs due to friction in the oil layer of the bearing and partly due to heat transfer along the shaft from hotter parts.

To get an idea of ​​the current temperature of the bearing, the temperature of the oil in the drain line is measured. But even a relatively low temperature does not exclude local overheating of the oil due to the imperfection of the bearing design, its poor-quality manufacture or improper assembly. Local overheating leads to accelerated aging of turbine oils, which is a consequence of a sharp increase in oxidizability due to an increase in temperature above 75-80 ºС.

Oil can also become hot in bearing housings and control systems.

oil splatter

Oil splashing is caused by the presence in the composition of steam turbines of such components as gears, couplings, ledges, ridges on the shaft, shaft sharpening, speed controller, etc. In this case, oil is sprayed into the craters of bearings and columns of centrifugal speed controllers. Such an oil product has a large area of ​​contact with air, which is almost always present in the crankcase. As a result, the oil is mixed with oxygen and the subsequent oxidation of the oil product. This process is intensified by the high speed of turbine oil particles relative to air.

The air in the bearing housings appears due to a slightly reduced local pressure due to suction into the gap along the shaft.

The greatest intensity of oil splashing is observed in movable couplings with forced lubrication. Therefore, in order to reduce the oxidation of oils, the couplings are surrounded by metal casings that limit the splashing of oil.

Influence of the air contained in the oil

Air can be in the turbine oil in the form of bubbles of various sizes, as well as in a dissolved state. It gets there due to capture in places of the most intensive mixing of oil with air, as well as in oil drain pipes, where the entire pipe section is not filled with oil.

As the air-containing oil passes through the main oil pump, the air bubbles are rapidly compressed. In large formations, the temperature rises sharply. Since the compression is very fast, the air does not have time to give off heat to the environment - the process is, in fact, adiabatic. Very little heat is released and the process of release itself lasts quickly. However, even this is sufficient to significantly accelerate the process of turbine oil oxidation. After passing through the pump, the compressed bubbles gradually dissolve, as well as the impurities contained in the air - dust, ash, water vapor, etc. - pass into the oil. As a result, the oil product is polluted and watered.

Oil aging due to the air it contains is most noticeable in large turbines, due to the high oil pressure after the main oil pump.

Influence of water and condensation steam

In turbines of old designs, the main source of oil flooding is steam, which escapes from the labyrinth seals and is sucked into the bearing housing. Also, watering may occur due to a malfunction of the steam shut-off valves of the auxiliary turbo oil pump. Also, water can enter the oil from the air as a result of condensation and through oil coolers.

The most dangerous is the watering of the oil after contact with hot steam. At the same time, the oil product not only absorbs moisture, but also heats up, which leads to an acceleration of its aging process.

The presence of water contributes to the formation of sludge. If it enters the bearing lubrication line, it can clog the holes in the metering washers installed on the injection lines. This is fraught with overheating or even melting of the bearing. The penetration of sludge into the control system disrupts the normal operation of spools, axle boxes and other elements of the turbine.

Also, as a result of the contact of turbine oil with hot steam, an oil-water emulsion is formed. It can get into the lubrication and regulation system, sharply degrading the quality of their work.

Influence of metal surfaces

When circulating through the oil system, turbine oil almost always comes into contact with various metals: steel, cast iron, babbitt, bronze, which also contributes to oxidation. When metal surfaces are exposed to acids, corrosion products are formed that can enter the oil. Also, some metals may have a catalytic effect on the oxidation of petroleum products.

The factors listed above, both individually and collectively, cause the aging of turbine oils. Aging is usually understood as a change in physical and chemical properties in the direction of deterioration in performance.

Signs of aging of turbine oils during operation can be considered:

1. increase in viscosity;
2. increase in acid number;
3. flash point reduction;
4. the appearance of an acid reaction of water extract;
5. the appearance of sludge and mechanical impurities;
6. decrease in transparency.

But the presence of even all of the listed signs does not mean that the turbine oil is not fit for use.

For use in steam turbines, petroleum products that meet the following requirements:

1. acid number does not exceed 0.5 mg KOH per 1 g of oil;
2. the viscosity of the oil does not differ from the original by more than 25%;
3. the flash point has decreased by no more than 10 ° C from the original;
4. the reaction of the water extract is neutral;
5. the oil is transparent and free of water and sludge.

If one of the parameters or characteristics of the oil does not correspond to the rated value and cannot be restored, then such a product must be replaced as soon as possible.

Turbine oil treatment plants

As we saw above, the aging of turbine oil can lead to a number of negative consequences. The failure of turbines, their downtime and repair are very expensive. And turbine oil itself is not a cheap product. Therefore, it is advisable to invest in activities aimed at slowing down the aging process and restoring the properties of oils that have already been in operation.

Installation SMM-4T

In practice, to solve such problems, companies GlobeCore . With the help of this equipment, a comprehensive purification of turbine oils from water and various impurities is carried out. Purification systems can operate in filtration and heating modes, as well as oil filtration, drying and degassing. The result of the treatment is an improvement in the performance characteristics of turbine oils to standardized values ​​and a significant extension of their service life.

Turbine oils are widely used for lubrication and cooling of bearings in various turbine generators - steam and gas turbines, hydraulic turbines, turbopumps. They are also used as a working fluid in turbine control systems and industrial equipment.

What properties does it have?

The turbine is a complex mechanism that must be handled with care. Turbine oils used must meet a number of characteristics:

• have antioxidant properties;
• protect parts from deposits;
• have demulsifying properties;
• be resistant to corrosion;
• have low foaming ability;
• be neutral to parts made of metals and non-metals.

All these characteristics of turbine oils are achieved during production.

Production features

Turbine oils are produced from highly refined petroleum distillates to which additives are added. Thanks to antioxidant, anti-corrosion, anti-wear additives, their performance characteristics are improved. Because of all these additives, it is important to choose oils in accordance with the operating instructions for a particular unit and the manufacturer's recommendations. If the turbine oil is of poor quality, the unit may simply fail. To achieve high quality in the production of compositions, high-quality grades of oil are used, deep cleaning is used during processing and the introduction of additive compositions. All this in combination can improve the antioxidant and anti-corrosion properties of oils.

Primary requirements

The rules for the technical operation of various pumping stations and networks indicate that turbine oil should not contain water, visible sludge and mechanical impurities. According to the instructions, it is also required to control the anti-rust properties of the oil - for this, special corrosion indicators are used, located in the oil tank of steam turbines. If, nevertheless, corrosion appears in the oil, it is necessary to introduce a special additive against the appearance of rust into it. We offer an overview of popular brands of turbine oils.

TP-46

This oil is used to lubricate bearings and other mechanisms of various units. Turbine oil 46 shows good antioxidant properties. To create it, sulfuric paraffinic oil of deep selective purification is used. The composition can be used on ship steam power plants and in any auxiliary mechanisms. TP-46 serves as a reliable protection of surfaces of parts from corrosion, is highly stable against oxidation and does not emit precipitation during long-term operation of turbines.

TP-30

Turbine oil 30 is produced on the basis of mineral base oils, where additives are added to improve the performance properties of the composition. Experts advise using TP-30 in turbines of any type, including gas and steam ones. Moreover, the operation of the oil is available even in harsh climatic conditions. Among the distinguishing features of TP-30, one can note an excellent antioxidant capacity, a good level of minimal cavitation, and excellent thermal stability.

T-46

Turbine oils T-46 are made from low-sulphur wax-free high-quality oils without additives, which ensures the availability of its cost while maintaining all performance characteristics. The quality raw materials used for production allow reaching a certain level of viscosity for the oil, which makes it easier and more convenient to clean. The use of this composition is advisable in ship turbines, steam turbine units.

TP-22S

Turbine oil TP-22S allows lubrication and cooling of bearings, auxiliary mechanisms of steam turbines that operate at high speeds, and it can also be used as a sealing medium in sealing and control systems. Benefits of this oil include:

• excellent performance properties due to a deeply refined mineral base and an effective composition of additives;
• excellent demulsifying properties;
• excellent stability against oxidation;
• high level of viscosity;
• minimal cavitation.

This oil is used in turbines for various purposes - from steam and gas to gas turbines of power plants.

TP-22B

Turbine oil TP-22B is produced from paraffinic oils, and cleaning is carried out with selective solvents. Thanks to the additives, a good level of resistance to corrosion and oxidation is achieved. If we compare TP-22B with TP-22S, then the former forms less sediment during the operation of the equipment, it is more durable in use. Its peculiarity is the absence of analogues among domestic grades of turbine oils.

"LukOil Tornado T"

This series offers a wide range of high quality turbine oils. They are based on those produced by a special synthetic technology with the use of additives of the ashless type of high efficiency. Oils are developed in accordance with the latest requirements for compositions of this kind. It is expedient to apply them in steam and with reducers and without them. Excellent antioxidant, anti-corrosion and anti-wear properties help minimize deposit formation. The oil is specially adapted for modern high-performance turbine units.

Composition features

Modern turbine oils are created on the basis of special paraffin oils with certain viscosity-temperature characteristics, as well as antioxidants and corrosion inhibitors. If the oil is planned to be used on turbines with gear boxes, then they must have a high bearing capacity, and for this, extreme pressure additives are added to the composition.

Extraction or hydrogenation is used to obtain base oils, while high-pressure refining and hydrotreating allow achieving such characteristics of turbine oil as oxidation stability, water separation, deaeration, which, in turn, affect pricing.

For turbines of various types

Turbine oils (GOST ISO 6743-5 and ISO/CD 8068) are used for modern gas and steam turbines. The classification of these materials, depending on the general purpose, can be represented as follows:

• For steam turbines (including those with gears under normal load conditions). These lubricants are based on refined mineral oils supplemented with antioxidants and corrosion inhibitors. The use of oils is advisable for industrial and marine drives.
• For steam turbines with high bearing capacity. These turbine oils additionally have extreme pressure characteristics, which provide lubrication of gears during operation of the equipment.
• For gas turbines: these oils are made from refined mineral formulations to which antioxidants are added,

Cleaning Features

The internal parts of any mechanism eventually become unusable due to natural wear and tear. Accordingly, mechanical impurities in the form of water, dust, chips also accumulate in the lubricating oil itself as it is used, an abrasive will begin to form. It is possible to make the operation of the equipment full-fledged and longer by constant monitoring and cleaning of turbine oil to eliminate mechanical impurities from it.

It should be noted that modern oils make it possible to optimize and increase the efficiency of the production process due to the full protection of parts and components of equipment. High-quality purification of turbine oil is a guarantee of reliable operation of turbine units for a long period without failures and malfunctions of the equipment itself. If low-quality oil is used, the functional reliability of the equipment will be in question, which means that it will wear out prematurely.

The oil recovered after cleaning can be reused. That is why it is advisable to use continuous cleaning methods, since in this case it is possible to increase the life of the oil without needing to refill it. Turbine oils can be purified by various methods: physical, physico-chemical and chemical. Let's describe all the methods in more detail.

Physical

These methods purify turbine oil without violating its chemical properties. Some of the most popular cleaning methods include:

• Settling: oil is cleaned from sludge, water, mechanical impurities through special settling tanks. An oil tank can be used as a sump. The disadvantage of the method is low productivity, which is explained by the long stage of delamination.
• Separation: oil is cleaned from water and impurities in a special centrifugal force separator drum.
• Filtration: With this method, the oil is purified from impurities that cannot be dissolved in it. To do this, the oil is passed through a porous filter surface through cardboard, felt or burlap.
• Hydrodynamic cleaning: this method allows you to clean not only the oil, but also the entire equipment. During operation, the oil film between metal and oil remains intact, corrosion does not appear on metal surfaces.

Physico-chemical

When using these cleaning methods, the chemical composition of the oil changes, but only slightly. These methods involve:

• Adsorption cleaning, when the substances contained in the oil are absorbed by solid highly porous materials - adsorbents. In this capacity, aluminum oxide, enamels with a whitening effect, silica gel are used.
• Flushing with condensate: this method is used if the oil contains low molecular weight acids that are soluble in water. After flushing, the performance properties of the oil are improved.

Chemical Methods

Cleaning by chemical methods involves the use of acids, alkalis. Alkaline cleaning is used if the oil is very worn out, and other cleaning methods do not work. Alkali affects the neutralization of organic acids, sulfuric acid residues, the removal of esters and other compounds. Cleaning is carried out in a special separator under the influence of hot condensate.

The most effective way to clean turbine oils is to use combined units. They involve cleaning according to a specially designed scheme. In industrial environments, universal installations can be used, thanks to which cleaning can be carried out in a separate method. Whatever cleaning method is used, it is important that the final quality of the oil is at its best. And this will increase the period of stable operation of the equipment itself.

At the operated facility, the main explosive, hazardous and toxic substances are: gas, ethyl mercaptan (odorant), methanol.

Maintenance personnel, working at an operating facility, must know the composition, basic properties of gases and their compounds. The effect of harmful substances used in production on the human body depends on the toxic properties of the substance, its concentration and duration of exposure. Occupational poisoning and diseases are possible only if the concentration of a toxic substance in the air of the working area exceeds a certain limit.

Table 6 - Information on hazardous substances at the facilities of LLC "Gazprom transgaz Tchaikovsky"

No. Name of the hazardous substance Hazard class Nature of human exposure 1 Natural gas (over 90% methane) 4 Natural gas is a flammable gas (Appendix 2 to Federal Law-116 dated 21.07.97) radiation on people; with high gas pressure in pipelines and vessels, depressurization of which may cause shrapnel damage to people; with suffocation at a 15-16% decrease in the oxygen content in the air displaced by gas. 2Turbine oil Tp-22s4 The main hazards are associated with: possible leakage and ignition of oil, followed by the development of a fire and exposure to thermal radiation on people; with the possibility of oil getting on the skin, in the eyes, which causes their irritation. 3 The odorant of natural gas supplied to the municipal distribution system after the GDS (ethyl mercaptan) 2 The odorant is a toxic substance (Appendix 2 to FZ-116 dated 21.07.97). Depending on the amount of odorant that affects a person and the individual characteristics of the body, the following are possible: headache, nausea, convulsions, paralysis, respiratory arrest, death 5-10 gr. ingestion of methanol causes severe poisoning, accompanied by headache, dizziness, nausea, stomach pain, general weakness, flickering in the eyes or loss of vision in severe cases. 30 g is a lethal dose

Natural gas is a colorless mixture of light natural gases, lighter than air, does not have a noticeable odor (an odorant is added to give it a smell). Explosive limits 5.0 ... 15.0% by volume. MPC in the air of industrial premises is 0.7% by volume, in terms of hydrocarbons 300 mg/m3. Self-ignition temperature 650°C.

At high concentrations (more than 10%), it has a suffocating effect, since oxygen deficiency occurs, as a result of an increase in the concentration of gas (methane) to a level not lower than 12%, it is transferred without noticeable effect, up to 14% leads to a mild physiological disorder, up to 16% causes severe physiological effect, up to 20% - already deadly suffocation.

Ethylmercaptan (odorant) - used to give a smell to gases transported through the main gas pipeline, even in small concentrations cause headache and nausea, and in high concentrations they act on the body like hydrogen sulfide in a significant concentration is toxic, acts on the central nervous system, causing convulsions, paralysis and death.. MPC of ethyl mercaptan in the air of the working area is 1 mg/m3.

The odorant evaporates easily and burns. Poisoning is possible by inhalation of vapors, absorption through the skin. It is similar in toxicity to hydrogen sulfide.

Ethyl mercaptan vapor concentration of 0.3 mg/m3 is the limit. Vapors of ethyl mercaptan in a certain mixture with air form an explosive mixture. Explosive limits 2.8 - 18.2%.

Methane - in its pure form is not toxic, but when its content in the air is 20% or more, the phenomenon of suffocation, loss of consciousness and death is observed. Limit hydrocarbons exhibit more toxic properties with increasing molecular weight. So propane causes dizziness when exposed to an atmosphere containing 10% propane for two minutes. MPC (maximum permissible concentration) is 300 mg/m3.

Ethylmercaptan interacts with iron and its oxides, forming iron mercantides prone to spontaneous combustion (pyrophoric compounds).

To ensure safe conditions for performing various types of construction and installation work and to exclude injuries, workers and engineering and technical personnel must be well aware of and follow the basic safety rules.

In this regard, workers and engineering and technical personnel involved in the construction or repair of pipelines are trained in their specialty and safety rules. The knowledge test is drawn up with the relevant documents in accordance with the current industry regulations on the procedure for testing knowledge of the rules, norms and instructions for labor protection.

Prior to the start of work on the repair of gas pipelines, the organization operating the gas pipeline is obliged:

give written permission for the performance of work on the repair of the gas pipeline;

clean the cavity of the gas pipeline from condensate and deposits;

identify and mark the places of gas leakage;

disconnect the gas pipeline from the existing pipeline;

identify and mark the location of the gas pipeline at a depth of less than 40 cm;

provide repair and construction sites with a connection to the control room, the nearest compressor station, the nearest lineman's house and other necessary points;

ensure technical and fire safety during repair work.

After switching off and depressurizing the gas pipeline, grading and overburden work is carried out.

The gas pipeline is opened with an overburden excavator in compliance with the following safety conditions:

the opening of the gas pipeline must be carried out 15-20 cm below the lower generatrix, which facilitates the slinging of the pipe when it is lifted from the trench;

it is prohibited to carry out other works and stay in the area of ​​operation of the working body of the overburden excavator.

The location of mechanisms and other machines near the trench should be behind the prism of soil collapse.

Hot work on the gas pipeline should be carried out in accordance with the requirements of the Standard Instructions for the Safe Conduct of Hot Work at Gas Facilities of the USSR Ministry of Gas Industry, 1988.

Electric welders who have passed the established certification and have the appropriate certificates are allowed to perform electric welding. When working with a cleaning machine, make sure that a foam or carbon dioxide fire extinguisher is installed on it.

Turbine oil is a high-quality distillate oil obtained in the process of oil refining. Turbine oils (GOST 32-53) of the following grades are used in the lubrication and control system: turbine 22p (turbine with VTI-1 additive), turbine 22 (turbine L), turbine 30 (turbine UT), turbine 46 (turbine T) and turbine 57 (turbo - geared). Oils of the first four grades are distillate products, and the latter is obtained by mixing turbine oil with aviation oil.

In addition to oils produced in accordance with GOST 32-53, turbine oils produced according to Inter-Republican Specifications (MRTU) are widely used. These are, first of all, sulphurous oils with various additives, as well as oils of low-sulfur oils of the Fergana plant.

Currently, digital marking of oils is used: the figure characterizing the grade of oil is the kinematic viscosity of this oil at a temperature of 50 ° C, expressed in centi - stokes. Index "p" means that the oil is operated with an antioxidant additive.

The cost of oil is directly dependent on its brand, and the higher the viscosity. oil, the cheaper it is. Each grade of oil must be used strictly for its intended purpose, and substitution of one for another is not allowed. This is especially true for the main power equipment of power plants.

Application areas are various. oils are defined as follows.

Turbine oil 22 and 22p is used for bearings and control systems of small, medium and large turbogenerators. power with a rotor speed of 3000 rpm. Turbine oil 22 is also used for plain bearings of centrifugal pumps with circulation and ring lubrication systems. Turbine 30 is used for turbogenerators with a rotor speed of 1500 rpm and for marine turbine installations. Turbine oils 46 and 57 are used for units with gearboxes. between turbine and drive.

Physical and chemical properties of turbine oils. are given in table. 5-2.

Turbine oil must meet the standards of GOST 32-53 (Table 5-2) and be distinguished by high stability of its properties. Of the main properties of the oil, characterizing its performance, the most important are the following:

Viscosity. Viscosity, or coefficient of internal friction, characterizes the friction loss in the oil layer. Viscosity is the most important characteristic of turbine oil, according to which it is labeled.

Such operationally important quantities as the coefficient of heat transfer from oil to the wall, power loss due to friction in bearings, as well as oil flow through oil pipelines, spools, and metering washers depend on the viscosity value.

Viscosity can be expressed in terms of dynamic, kinematic and conditional viscosity.

Dynamic viscosity, or coefficient of internal friction, is a value equal to the ratio of the internal friction force acting on the surface of a liquid layer at a velocity gradient equal to unity to the area of ​​this layer.

Where Di/DI is the velocity gradient; AS is the surface area of ​​the layer on which the force of internal friction acts.

In the CGS system, the unit of dynamic viscosity is poise. Poise unit: dn-s/cm2 or g/(cm-s). In units of the technical system, dynamic viscosity has the dimension kgf-s/m2.

There is the following relationship between dynamic viscosity, expressed in the CGS system, and technical:

1 poise \u003d 0.0102 kgf-s / m2.

In the SI system, 1 N s / img, or 1 Pa s, is taken as a unit of dynamic viscosity.

The relationship between old and new viscosity units is as follows:

1 poise \u003d 0.1 N s / mg \u003d 0.1 Pa-s;

1 kgf s / m2 \u003d 9.80665 N s / m2 \u003d 9.80665 Pa-s.

Kinematic viscosity is a value equal to the ratio of the dynamic viscosity of a liquid to its density.

The unit of kinematic viscosity in the CGS system is stoks. Stokes dimension is cm2/s. The hundredth part of a stokes is called a centistokes. In the technical system and the SI system, kinematic viscosity has the dimension m2/s.

Conditional viscosity, or viscosity in degrees Engler, is defined as the ratio of the time of flow of 200 ml of the test liquid from a VU or Engler type viscometer at the test temperature to the time of flow of the same amount of distilled water at a temperature of 20°C. The value of this ratio is expressed as the number of conventional degrees.

If a VU type viscometer is used to test the oil, then the viscosity is expressed in arbitrary units, when using an Engler viscometer, the viscosity is expressed in Engler degrees. To characterize the viscosity properties of turbine oil, both kinematic viscosity units and conditional viscosity units (Engler) are used. To convert degrees of conditional viscosity (Engler) to kinematic, you can use the formula

V/=0.073193< - -, (5-2)

Where Vf is the kinematic viscosity in centi-Stokes at a temperature of t \ 3t is the viscosity in Engler degrees at a temperature of t\ E is the viscosity in Engler degrees at 20 ° C.

The viscosity of the oil depends very strongly on temperature (Fig. 5-ііЗ), and this dependence is more pronounced

Rns. 5-13. Dependence of viscosity of turbine oil on temperature.

22, 30, 46 - oil grades.

Expressed in heavy oils. This means that in order to maintain the viscosity properties of turbine oil, it is necessary to operate it in a fairly narrow temperature range. According to the technical operation rules, this range is set within 35-70°C. Turbine units must not be operated at lower or higher oil temperatures.

Experiments have established that the specific load that a plain bearing can withstand 303- will melt with an increase in oil viscosity. With an increase in temperature, the viscosity of the grease decreases and, consequently, the bearing capacity of the bearing, which ultimately can cause the lubrication layer to cease to act and melt the babbitt filling of the bearing. In addition, at high temperatures, the oil oxidizes and ages faster. At low temperatures, due to an increase in viscosity, the oil consumption through the metering washers of the oil pipelines is reduced. Under such conditions, the amount of oil supplied to the bearing decreases, and the bearing will operate with increased oil heating .

The dependence of viscosity on pressure can be more accurately calculated by the formula

Where v, - kinematic viscosity at pressure p \ Vo - kinematic viscosity at atmospheric pressure; p - pressure, kgf/cm2; a is a constant, the value of which for mineral oils is 1.002-1.004.

As can be seen from the table, the dependence of viscosity on pressure is less pronounced than the dependence of viscosity on temperature, and when the pressure changes by several atmospheres, this dependence can be neglected.

The acid number is a measure of the acid content of an oil. The acid number is the number of milligrams of caustic potash needed to neutralize 1 gram of oil.

Lubricating oils of mineral origin contain mainly naphthenic acids. Naphthenic acids, despite their slightly acidic properties, when in contact with metals, especially non-ferrous ones, cause corrosion of the latter, forming metal soaps that can precipitate. The corrosive effect of an oil containing organic acids depends on their concentration and molecular weight: the lower the molecular weight of organic acids, the more aggressive they are. This also applies to acids of inorganic origin.

The stability of the oil characterizes the preservation of its basic properties during long-term operation.

To determine the stability, the oil is subjected to artificial aging by heating it with simultaneous air blowing, after which the sediment percentage, acid number and content of water-soluble acids are determined. The deterioration of the qualities of artificially aged oil should not exceed the standards indicated in Table. 5-2.

Ash content of oil - the amount of inorganic impurities remaining after burning a sample of oil in a crucible, expressed as a percentage of the oil taken for combustion. The ash content of pure oil should be minimal. High ash content indicates poor oil purification, i.e., the presence of various salts and mechanical impurities in the oil. The increased salt content makes the oil less resistant to oxidation. In oils containing antioxidant additives, increased ash content is allowed.

The rate of demulsification is the most important performance characteristic of turbine oil.

The rate of demulsification refers to the time in. minutes, during which the emulsion formed by passing steam through the oil under test conditions is completely destroyed.

Fresh and well-refined oil does not mix well with water. Water quickly separates from such oil and settles at the bottom of the tank even if the oil stays in it for a short time. If the quality of the oil is poor, the water does not completely separate in the oil tank, but forms a fairly stable emulsion with the oil, which continues to circulate in the oil system. The presence of an oil-in-water emulsion in the oil changes the viscosity. oil and all its main characteristics, causes corrosion of the elements of the oil system, leads to the formation of sludge. The lubricating properties of the oil deteriorate sharply, which can lead to damage to the bearings. The aging process of oil in the presence of emulsions is even more accelerated.

The most favorable conditions for the formation of emulsions are created in the oil systems of steam turbines, and therefore to turbine oils. high demulsifying ability is required, i.e. the ability of the oil to quickly and completely separate from water.

The flash point of oil is the temperature to which it is necessary to heat the oil so that its vapors form a mixture with air that can ignite when an open fire is brought to it. (

The flash point characterizes the presence of light volatile hydrocarbons in the oil and the volatility of the oil when it is heated. The flash point depends on the grade and chemical composition of the oil, and as the viscosity of the oil increases, the flash point usually increases.

As turbine oil is used, its flash point decreases. This is due to evaporation. low-boiling fractions and phenomena of oil decomposition. A sharp decrease in the flash point indicates an intense decomposition of the oil caused by its local overheating. The flash point also determines the fire hazard of the oil, although the self-ignition temperature of the oil is a more characteristic value in this regard.

The auto-ignition temperature of an oil is the temperature at which the oil ignites without being exposed to an open flame. This temperature for turbine oils is about twice as high as the flash point and depends largely on the same characteristics as the flash point.

Mechanical impurities - various solids that are in the oil in the form of a precipitate or in suspension.

Butter. can be contaminated with mechanical impurities during storage and transportation, as well as during operation. Especially strong contamination of the oil is observed with poor-quality cleaning. oil pipelines and oil tank after installation and repairs. Being suspended in the oil, mechanical impurities cause increased wear of rubbing parts. According to GOST. mechanical impurities in the turbine oil must be absent.

The pour point of the oil is a very important indicator of the quality of the oil, which makes it possible to determine the ability of the oil to work at low temperatures. The loss of oil mobility with a decrease in its temperature occurs due to the release and crystallization of solid hydrocarbons dissolved in the oil.

Freezing temperature. oil is the temperature at which the tested oil under the conditions of the experiment thickens so much that when the test tube with oil is tilted at an angle of 45 °, the oil level remains stationary for 1 min.

Transparency characterizes the absence of foreign inclusions in the oil: mechanical impurities, water, sludge. The transparency of the oil is checked by cooling the oil sample. Oil cooled to 0°C should remain clear.

C) Turbine oil operating conditions. Oil aging

The operating conditions of the oil in the oil system of a turbogenerator are considered severe due to the constant action of a number of factors unfavorable to the oil. These include:

1. Exposure to high temperature

Heating the oil in the presence of air contributes strongly. to its oxidation. Other performance characteristics of the oil also change. Due to the evaporation of low-boiling fractions, the viscosity increases, the flash point decreases, the de-emulsion ability worsens, etc. The main heating of the oil occurs in the turbine bearings, where the oil is heated from 35-40 to 50-55°C. The oil is heated mainly by friction in the oil layer of the bearing and partly by heat transfer along the shaft from the hotter parts of the rotor.

The temperature of the oil exiting the bearing is measured in the drain line, which gives an approximate indication of the temperature of the bearing. However, the relatively low oil temperature at the drain does not exclude the possibility of local overheating of the oil due to imperfect bearing design, poor manufacturing quality, or incorrect assembly. This is especially true for thrust bearings, where different segments can be loaded differently. Such local overheating contributes to enhanced aging of the oil, since with an increase in temperature * above 75-80 ° C, the oxidizability of the oil increases sharply.

The oil can also heat up in the bearing housings themselves from contact with hot walls heated from the outside by steam or due to heat transfer from the turbine casing. Oil heating also occurs in the control system - servomotors and oil pipelines passing near the hot surfaces of the turbine and steam pipelines.

2. Oil spraying by the rotating parts of the turbine unit

All rotating parts - couplings, gears, ridges on the shaft, shaft ledges and sharpening, centrifugal speed controller, etc. - create oil splashing in bearing housings and columns of centrifugal speed controllers. The atomized oil acquires a very large surface of contact with the air that is always in the crankcase, and mixes with it. As a result, the oil is exposed to intense atmospheric oxygen and oxidized. This is also facilitated by the high speed acquired by the oil particles relative to air.

In the crankcases of bearings, there is a constant exchange of air due to its suction into the gap along the shaft due to a slightly reduced pressure in the crankcase. The pressure drop in the crankcase can be explained by the ejecting action of the oil drain lines. Movable couplings with forced lubrication spray oil especially intensively. Therefore, to reduce oil oxidation, these couplings are surrounded by metal casings that reduce oil splashing and air ventilation. Protective covers are also installed with rigid couplings in order to reduce air circulation in the crankcase and limit the rate of oxidation of the oil in the bearing crankcase.

To prevent oil from escaping from the bearing housing in the axial direction, oil flingers and grooves machined in babbitt at the ends of the bearing at the shaft exit are very effective. The use of screw-groove seals by UralVTI gives a particularly great effect.

3. Exposure to air in oil

The air in the oil is contained in the form of bubbles of various diameters and in dissolved form. Oil trapping air. occurs in places of the most intensive mixing of oil with air, as well as in drain oil pipelines, where oil does not fill the entire section of the pipe and sucks in air.

The passage of oil containing air through the main oil pump is accompanied by a rapid compression of the air bubbles. At the same time, the air temperature in large bubbles rises sharply. Due to the speed of the compression process, the air does not have time to give off heat to the environment, and therefore the compression process should be considered adiabatic. The released heat, despite the negligible absolute value and the short duration of exposure, significantly catalyzes the process of oil oxidation. After passing through the vacuum, the compressed bubbles gradually dissolve, and the impurities contained in the air (dust, ash, water vapor, etc.) pass into the oil and, thus, pollute and water it.

The aging of the oil due to the air contained in it is especially noticeable in large turbines, where the oil pressure after the main oil pump is high, and this leads to a significant increase in air temperature in the air bubbles with all the ensuing consequences.

4. Exposure to water and condensing steam

The main source of oil flooding in turbines of old designs (without steam suction, from labyrinth seals) is steam.

Knocking out of the labyrinth seals and sucked into the bearing housing. The intensity of watering in this case largely depends on the state of the labyrinth seal of the turbine shaft and on the distance between the bearing and turbine housings. Another source of watering is a malfunction of the steam shut-off valves of the auxiliary turbo oil pump. Water also enters the oil from the air due to vapor condensation and through oil coolers.

In centrally lubricated turbo feed pumps, the oil can become waterlogged due to water leaks from the pump seals.

Watering of the oil, which occurs due to contact of the oil with hot steam, is especially dangerous. In this case, the oil is not only watered, but also heated, which accelerates the aging of the oil. In this case, the resulting low molecular weight acids pass into an aqueous solution and actively affect the metal surfaces in contact with the oil. The presence of water in the oil contributes to the formation of sludge, which settles on the surface of the oil tank and oil lines. Once in the bearing lubrication line, the sludge can plug the holes in the metering washers installed in the injection lines and cause the bearing to overheat or even melt. Sludge entering the control system. can disrupt the normal operation of spools, axle boxes and other elements of this system.

The penetration of hot steam into the oil also leads to the formation of an oil-in-water emulsion. In this case, the surface of contact between oil and water sharply increases, which facilitates the dissolution of non-molecular acids in water. The oil-water emulsion can get into the lubrication and control system of the turbine and significantly worsen its operating conditions.

5. Exposure to metal surfaces

Circulating in the oil system, the oil is constantly in contact with metals: cast iron, steel, bronze, babbitt, which contributes to the oxidation of the oil. Due to the action of metal surfaces, acids form corrosion products that enter the oil. Some metals have a catalytic effect on the oxidation of turbine oil.

All these constantly acting unfavorable conditions cause oil aging.

By aging, we mean a change in physicochemical

Properties of turbine oil in the direction of deterioration of its performance.

Signs of oil aging are:

1) increase in oil viscosity;

2) increase in acid number;

3) lowering the flash point;

4) the appearance of an acidic reaction of water extract;

5) the appearance of sludge and mechanical impurities;

6) decrease in transparency.

Oil aging rate

Depends on the quality of the filled oil, the level of operation of the oil facilities and the design features of the turbine unit and oil system.

Oil that shows signs of aging is still considered good according to the standards. for use if:

1) acid number does not exceed 0.5 mg KOH per 1 g of oil;

2) the viscosity of the oil does not differ from the original by more than 25%;

3) the flash point has dropped by no more than 10°C from. initial;

4) the reaction of the water extract is neutral;

5) The oil is transparent and free of water and sludge.

If one of the listed characteristics of the oil deviates from the norms and it is impossible to restore its quality on a working turbine, the oil must be replaced as soon as possible.

The most important condition for the high-quality operation of the oil facilities of the turbine shop is a thorough and systematic control of the quality of the oil.

For oil in operation, two types of control are provided: shop control and reduced analysis. The volume and frequency of these types of control are illustrated in Table. 5-4.

With an abnormally rapid deterioration in the quality of the oil being used, the test period may be reduced. Tests in this case are carried out according to a special schedule.

The oil entering the power plant is subjected to laboratory testing for all indicators. In the event that one or more indicators do not meet the established standards for fresh oil, it is necessary to send the received batch of fresh oil back. The analysis of oil is also carried out before filling it into the tanks of steam turbines. The oil in the reserve is analyzed at least once every 3 years.

The aging process of oil in continuous use causes the oil to lose its original properties and become unusable. Further operation of such oil is impossible, and its replacement is required. However, given the high cost of turbine oil, as well as the quantities in which it is used in power plants, it is impossible to count on a complete oil change. It is necessary to regenerate used oil for further use.

Oil regeneration is the restoration of the original physical and chemical properties of used oils.

The collection and regeneration of used oils is one of the most effective ways to save them.

Mia. The rates of collection and regeneration of turbine oil are given in Table. 5-5.

Existing methods of regeneration of used oils are divided into physical, physico-chemical and chemical.

Physical methods include methods in which the chemical properties of the regenerated oil do not change during the regeneration process. The main of these methods are settling, filtration and separation. With the help of these methods, the purification of "oils from impurities and water undissolved in the oil is achieved.

Physico-chemical methods of regeneration include methods in which the chemical composition of the treated oil is partially changed. The most common physicochemical methods are oil cleaning with adsorbents, as well as oil washing with hot condensate.

Chemical methods of regeneration include cleaning oils with various chemical reagents (sulfuric acid, alkali, etc.). These methods are used to restore oils that have undergone significant chemical changes during operation.

The choice of regeneration method is determined by the nature of oil aging, the depth of change in its performance, as well as the requirements for the quality of oil regeneration. When choosing a regeneration method, it is also necessary to take into account the cost indicators of this process, giving preference to the simplest and cheapest methods possible.

Some regeneration methods allow the oil to be cleaned while it is running, in contrast to methods that require the oil to be completely drained from the oil system. From an operational point of view, continuous regeneration methods are preferable because they allow longer oil life without refilling and do not allow deep deviations in oil performance from the norm. However, continuous oil regeneration on a running turbine can only be carried out using small-sized equipment that does not clutter up the room and allows easy assembly and dismantling. Such equipment includes separators, filters, adsorbers.

In the presence of more complex and bulky equipment, the latter is placed in a separate room, and the cleaning process in this case is carried out with oil draining. The most expensive equipment for oil regeneration is not rational to use for one station, given the frequency of its operation. Therefore, such installations are often carried out mobile. For large block stations with a significant volume of oil in operation, stationary regenerative plants of any type also justify themselves.

Consider the main methods of purification and regeneration of turbine oil.

Sucks. The simplest and cheapest method of separating water, sludge and mechanical impurities from oil is oil settling in special settling tanks with conical bottoms. In these tanks, over time, stratification of media with different specific gravity occurs. Clean oil, having a lower specific gravity, moves to the upper part of the tank, and water and mechanical impurities accumulate at the bottom, from where they are removed through a special valve installed at the lowest point of the tank.

The oil tank also acts as a sump. Oil tanks also have conical or sloping bottoms to collect water and sludge and then dispose of them. However, in oil tanks there are no proper conditions for the separation of the oil-water emulsion. The oil in the tank is in constant motion, which causes mixing of the upper and lower layers. The unreleased air in the oil smooths out the difference between the densities of the individual components of the oil-water mixture and makes it difficult for them to separate. In addition, the residence time of the oil in the oil tank does not exceed 8-10 minutes, which is clearly not enough for high-quality oil sludge.

In the settling tank, the oil is in more favorable conditions, since the settling time is not limited by anything. The disadvantage of this method is low productivity with a significant settling time. Such sedimentation tanks take up a lot of space and increase the fire hazard of the room.

Separation. A more productive method of cleaning oil from water and impurities is oil separation, which consists in separating suspended particles and water from oil due to centrifugal forces arising in the separator drum rotating at high frequency.

According to the principle of operation, oil-cleaning separators are divided into two types: low-speed with a speed of rotation from 4500 to 8000 rpm and high-speed with a speed of about 18,000-20,000 rpm. Low-speed separators with a drum equipped with trays have found the greatest distribution in domestic practice. On fig. 5-14 and 5-15 show the layout of the device and the overall dimensions of the disc separators.

Separators are also subdivided into vacuum separators, in which, in addition to mechanical impurities and suspended moisture, also partially dissolved moisture and air are removed from the oil, and
tori of open type. iB, depending on the nature of the contaminants, oil purification by separators can be carried out by the clarification method (clarification) and the purification method i (purification).

Oil purification by the clarification method is used to separate solid mechanical impurities, sludge, and also to separate the water contained in the oil in such a small amount that its direct removal is not required. In this case, impurities separated from the oil remain in the drum sump, from where they are periodically removed. The removal of contaminants from the oil by the cleaning method is used in cases where the oil is significantly watered and is essentially a mixture of two liquids with different densities. In this case, both water and oil are discharged continuously from the separator.

Turbine oil contaminated with mechanical impurities and a small amount of moisture (up to 0.3%) is purified by the clarification method. With more significant watering - according to the cleaning method. On fig. 5-114 the left side of the drum is shown assembled for work according to the clarification method, and the right side - according to the cleaning method. The arrows show the flows of oil and separated water.

The transition from one method of operation of the separator to another requires a bulkhead of the drum and oil outlet lines.

The performance of a drum assembled by the clarification method is 20-30% higher than when it is assembled by the cleaning method. To increase the performance of the separator, the oil is preheated to 60-65°C in an electric heater. This heater is completed with a separator and has a thermostat limiting. oil heating temperature.

With the help of a separator, oil cleaning can be carried out on a running turbine. This need usually arises when the oil is heavily watered. In this case, the suction pipe of the separator is connected to the lowest point of the dirty compartment of the oil tank, and the cleaned oil is sent to the clean compartment. If there are two separators at the station, they can be connected in series, and the first separator must be assembled according to the cleaning scheme, and the second - according to the clarification scheme. This significantly improves the quality of oil purification.

Filtration. Oil filtration is the separation of oil-insoluble impurities by passing (punching) through a porous filter medium. Filter paper, cardboard, felt, burlap, belting, etc. are used as a filter material. Frame filter presses are widely used to filter turbine oils. The frame filter press has its own rotary or vortex type oil pump, which, under a pressure of 0.294-0.49 MPa (3-5 kgf / cm2), passes oil through the filter material sandwiched between special frames. The contaminated filter material is systematically replaced with a new one. The general view of the filter press is shown in fig. 5-16. Filtering the oil with a filter press is usually combined with cleaning it in a separator. It is irrational to pass a heavily watered oil through a filter-press, since the filter material is quickly contaminated, and cardboard and paper lose their mechanical strength. More reasonable is the scheme, according to which the oil is first passed through the separator, and then through the filter press. At the same time, oil cleaning can be carried out on a running turbine. If there are two separators working in series, the filter press can be switched on after the second separator along the oil flow, assembled according to the clarification scheme. This will achieve a particularly high degree of oil purification.

LMZ uses a special “filter-belting” type fabric in the filter press with the organization of the filtration process under a small drop. This method is very effective when the oil is heavily clogged with an adsorbent, and the filter itself does not need systematic maintenance.

"VTI has developed a cotton filter, which is also successfully used.

To ensure the normal functioning of the oil system of the turbine unit, it is necessary not only to continuously clean the oil, but periodically (after repairs) to clean the entire system.

The adopted laminar regime of oil flow in the pipelines of the system at a speed not exceeding 2 m/s contributes to the deposition of sludge and dirt on internal and especially on cold surfaces.

Central Design Bureau Glavenergoremoit has developed and tested in practice a hydrodynamic method for cleaning oil systems. It consists in the following: the entire oil system, excluding bearings, is cleaned by pumping oil at a speed 2 times or more higher than the working one at a temperature of 60 °C. This method is based on the organization of a turbulent flow in the near-wall region, in which the sludge and corrosion products are washed off from the internal surfaces due to the mechanical action of the oil flow and carried into the filters.

The hydrodynamic cleaning method has the following advantages:

1) the passivating film formed as a result of long-term contact of the metal with the operating oil is not broken;

2) eliminates the formation of corrosion on babbitt and nitrided surfaces;

3) does not require chemical solutions to wash off deposits;

4) eliminates the dismantling of the oil system (except for the places where jumpers are installed);

5) reduces the complexity of cleaning by 20-40% and reduces the duration of the overhaul of the turbine unit by 2-3 days.

The operation of the oil used to clean the systems has shown that its physical and chemical properties do not deteriorate, therefore, the cleaning of oil systems can be carried out with operating oil.

Adsorption. This method of cleaning turbine oils is based on the phenomenon of absorption of substances dissolved in oil by solid highly porous materials (adsorbents). Through adsorption, organic and low molecular weight acids, resins and other impurities dissolved in it are removed from the oil.

Various materials are used as adsorbents: silica gel (SiOg), alumina and various bleaching earths, the chemical composition of which is mainly characterized by the content of BiOg and Al2O3 (bauxites, diatomites, shales, bleaching clays). Adsorbents have a highly branched system of capillaries penetrating them. As a result, they have a very large specific absorption surface per 1 g of the substance. So, for example, the specific surface of activated carbon reaches 1000 m2/g, silica gel and aluminum oxide 300-400 m2/g, bleaching earths ilOO-300 m2/g.

In addition to the total surface area, the adsorption efficiency depends on the pore size and on the size of the adsorbed molecules. The diameter of the holes -(pores) in the absorbers is on the order of several tens of angstroms. This value is commensurate with the size of absorbed molecules, as a result of which some high-molecular compounds will not be absorbed by especially finely porous adsorbents. For example, activated carbon cannot be used for oil purification due to its finely porous structure. As adsorbents for turbine oil, materials with pore sizes of 20-60 angstroms can be used, which allows the absorption of high molecular weight compounds such as resins and organic acids.

Silica gel, which has become widespread, well - absorbs resinous substances and organic acids are somewhat worse. Aluminum oxide, on the contrary, well extracts organic acids from oils, especially low molecular weight acids, and absorbs resinous substances worse.

These two scavengers are high cost artificial adsorbents, especially alumina. Natural adsorbents (clays, bauxites, diatomites) are cheaper, although their efficiency is much lower.

Cleaning with adsorbents can be carried out in two ways. methods: contact and percolation.

The contact method of oil treatment consists in mixing the oil with finely ground adsorbent powder. Before cleaning. the oil must be warm. The adsorbent is removed by passing the oil through a press filter. The adsorbent is lost.

The process of percolation filtration consists in passing oil heated to 60-80 °C through a layer of granular adsorbent loaded into special apparatuses (adsorbers). In this case, the adsorbent has the form of granules with a grain size of 0.5 mm or more. With the percolation method of oil recovery, unlike the contact method, it is possible to recover and reuse adsorbents. This reduces the cost of the purification process and, in addition, allows the use of more effective expensive adsorbents for oil treatment.

The degree of use of the adsorbent, as well as the quality of oil purification with the percolation method, as a rule, is higher than with the contact method. In addition, the percolation method - allows you to restore the oil without draining it from the oil tank, on operating equipment. All these circumstances. brought. moreover, this method has found predominant distribution in domestic practice.

The mobile type adsorber is shown in fig. 5-17. It is a welded cylinder filled with granular adsorbent. The cover and bottom of the adsorber are removable. A filter is installed in the upper part of the adsorber to trap small particles of the adsorbent. The oil is filtered from bottom to top. This provides the most complete air displacement and reduces filter clogging. For the convenience of removing the spent adsorbent, the apparatus can be rotated around its axis by 180°.

The adsorbent has the ability to absorb not only oil aging products, but also water. So,

Before being treated with an adsorbent, the oil must be thoroughly cleaned of water and sludge. Without this condition, the adsorbent will quickly lose its absorbing properties and the oil purification will be of poor quality. In the general scheme of oil treatment, adsorption should be after oil purification through separators and filter presses. If the station has two separators, the role of a filter press can be performed by one of the separators operating in the clarification mode.

The used adsorbent can be easily recovered by blowing hot air through it at a temperature of about 200°C. On fig. 5-18 shows an installation for the recovery of adsorbents, which includes a fan for pumping air, an electric heater for heating it, and a reactivator tank where the regenerated adsorbent is loaded.

Adsorption purification cannot be used for oils containing additives, since the latter (except for ionol) are completely removed by adsorbents.

Rinsing with condensate. This type of oil treatment is used when the acid number of the oil increases and low molecular weight water-soluble acids appear in it.

As practice has shown, as a result of washing the oil, its other indicators also improve: the deemulsion ability increases, the amount of sludge and mechanical impurities decreases. To improve the solubility of acids, oil and condensate should be heated to a temperature of 70-80°C. The amount of condensate required for flushing is 50-100% of the amount of oil to be flushed. The necessary conditions for high-quality flushing are good mixing of oil with condensate and the creation of the largest possible surface of their contact. To ensure these conditions, it is convenient to use

Vatsya separator, where the water and. the oil is in a finely dispersed state and mixes well with each other. In this case, low molecular weight acids pass from the oil into water, with which they are discharged from the separator. Sludge and impurities found. in oil, are moistened, their density increases, as a result of which the conditions for their separation are improved.

Flushing oil with condensate can also be done in a separate tank, where water and oil are circulated using steam or a special pump. Such washing can be carried out during the repair of the turbine. In this case, the oil is taken from the oil tank and, after washing, enters the reserve tank.

Alkali treatment is used when the oil is deeply worn out, when all previous methods of restoring the operational properties of the oil are insufficient.

Alkali is used for neutralization of organic acids in oils, residues of free sulfuric acid (during the treatment of oil with acid), removal of esters and other compounds that, when interacting with alkali, form salts that pass into an aqueous solution and are removed by subsequent oil treatment.

For the regeneration of used oils, 2.5-4% sodium hydroxide or 5-14% trisodium phosphate is most often used.

The treatment of oil with alkalis can be carried out in the separator in the same way as it is done when washing the oil with condensate. The process is carried out at a temperature of 40-90°C. To reduce the consumption of alkali, as well as to improve the quality of purification, the oil must be preliminarily dehydrated in the separator. "The subsequent treatment of the oil after its recovery with alkali consists in washing it with hot condensate and treating it with adsorbents.

Since the use of chemical reagents requires preliminary and subsequent oil treatment, combined units for deep oil regeneration have appeared, where all stages of oil treatment are combined into a single technological process. These units, depending on the applied oil regeneration scheme, have rather complex equipment and are both stationary and mobile.

Each scheme includes equipment specific to a given treatment method: pumps, mixing tanks, settling tanks, filter-presses, etc. There are also universal installations that allow the oil regeneration process to be carried out by any method.

The use of additives is the most modern and effective method of preserving the physical and chemical properties of the oil during long-term operation.

Additives are called highly active chemical compounds added to the oil in small quantities, allowing to maintain the main performance characteristics of the oil at the required level for a long period of operation. Additives added to turbine oils must meet a number of requirements. These compounds should be cheap enough, used in small quantities, readily soluble in oil at operating temperature, not precipitated and suspended, not washed out with water, and not removed by adsorbents. The action of additives should give the same effect, for oils of different origin and varying degrees of wear. In addition, while stabilizing some indicators, additives should not worsen other performance indicators of the oil.

It should be noted that there are no additives that meet all these requirements yet. In addition, there is no compound that can stabilize all oil performance at once. For this purpose, there are compositions of various additives, each of which affects a particular indicator.

A wide variety of additives have been developed for oils of petroleum origin, of which antioxidant, anticorrosion and demulsifying additives are the most important for turbine oils.

The main value is an antioxidant additive that stabilizes the acid number of the oil. It is according to this indicator that under adverse operating conditions, the oil ages the fastest. For a long time, the VTI-1 additive was the main type of domestically produced antioxidant additive. This additive is quite active, dissolves well in oil, and is used in small quantities (0.01% of the oil mass). The disadvantage of this additive is that it is only suitable for stabilizing fresh oils. For used and partially oxidized oils, it can no longer delay the process of further oxidation.

In this regard, the VTI-8 additive has the best characteristics. It is more active and is also suitable for both fresh and used oils. As a disadvantage, it should be noted the ability of this compound to release a suspension after a while, causing the oil to become cloudy. To eliminate this phenomenon, the oil in the initial stage of operation must be passed through a filter press. Additive VTI-8 is added in the amount of 0.02-0.025% by weight of the oil.

The most effective antioxidant, which has become widespread both in our country and abroad, is 2,6-diteric butyl-4-methylphenol, which was called DBC (ionol) in the USSR. This additive is easily soluble in oil, does not precipitate, is not removed from the oil by adsorbents, and is not destroyed when the oil is treated with alkali and metallic sodium. The additive is removed only when the oil is cleaned with sulfuric acid. The use of DBK additive lengthens the life of well-purified oil by 2-5 times. The only drawback of this antioxidant is the increased consumption compared to other additives (0.2-0.5%). There are also reasons to increase this norm.

Anti-corrosion additives are used to protect the metal from the action of acids contained in fresh oil, as well as oil oxidation products. The anti-corrosion effect is reduced to the formation of a protective film on the metal that protects it from corrosion. One of the most effective anti-corrosion additives is additive B-15/41, which is an ester of alkenyl-succinic acid. Anti-corrosion additives can to some extent increase the acid number of oils and reduce their stability. Therefore, anti-corrosion additives are used in the minimum required concentration together with antioxidant additives.

Demulsifying additives (demulsifiers) are substances used to destroy oil and oil emulsions. Demulsifiers are aqueous solutions of neutralized acid tar or emulsions of highly refined mineral oil with an aqueous solution of sodium salts of petroleum and sulfo- petroleum acids. Recently, new compounds, di-proxamines, have been proposed as demulsifiers. The most effective of them is diproxa - min-157 [DPK-157], developed by VNIINP.