Vertical steel tank (PBC - 1000)

Contents

Contents

Summary

Introduction

1 Descriptions of equipment and process operations

1.1 Equipment requirement

1.2 Tank equipment

1.3 Process Operations

2 General information about oil depots and oil products

2.1 Classification of oil depots

2.2 Classification of petroleum products

2.3 Oil depot facilities and their location

3 Tank Maintenance

4 Technical documentation for tanks

5 Types of oil losses from evaporation

6 Calculation of oil losses from evaporation during storage in PBC

6.1 Initial data

6.2 Calculation of oil losses from "small breath"

6.3 Calculation of oil losses from "big breath"

6.4 Calculation of oil losses from "back exhalation"

6.5 Total losses of oil from evaporation in the tank per year

7 Selection of the event

Conclusion

List of sources used

Summary

In this course design, oil losses from evaporation were calculated, the main methods for reducing oil losses from evaporation were dismantled and thoroughly studied. Also in this work, the efficiency of using a floating roof as a means of reducing losses is calculated. Attached to the work are drawings of the tank as well as the main equipment used at this site.

The work contains 52 pages and 10 drawings.

Introduction

At facilities for transportation, storage of oil and oil products, during technological operations, there is a need for the use of tank farms, which are the technological object of oil pumping stations.

If tank farms at the head transfer stations are intended to create a certain reserve of oil and petroleum products, then at intermediate stations they are buffer tanks and are intended to compensate for the uneven supply of two neighboring transfer stations.

In case of short-term scheduled or emergency stops of one of the intermediate stations, the transported liquid enters the tank farm of this station, and the next station continues to operate due to oil or oil product available in its tank farm.

The transportation of oil to oil refineries and the obtained products to the consumer is associated with significant losses. Losses from mixing and leakage in pipeline transport, from tanks, from incomplete drainage of railway and road tanks, watering, cleaning, as well as due to accidents, spills, spraying and evaporation, cause great damage to the economy of the country, lead to the cost of public labor and reduce production efficiency. In addition, losses of oil and oil products during accidents, spills and leaks pollute the soil, groundwater and reservoirs. Multiple transshipments of oil products and storage of oil and oil products in tanks lead to losses from evaporation. Millions of tons of hydrocarbons go into the atmosphere. Mainly light fractions evaporate. At the same time, the raw material for petrochemical synthesis decreases, the quality of the oil product deteriorates.

Hydrocarbons pollute the atmosphere, adversely affect the health of maintenance personnel and residents, especially children, nearby housing estates.

At long-term storage bases, oxidation of petroleum products leads to a loss of grade due to its untimely implementation.

Thus, losses of oil and petroleum products are due to both their specific properties and the conditions for pumping storage, reception, vacation, the technical condition of transport and storage facilities, as well as the care and integrity of service personnel. Losses of oil and petroleum products to the environment have become global and will increase in proportion to the increase in oil production and consumption without constant compliance with effective measures to combat them.

According to statistics, losses of oil and oil products during transportation significantly exceed losses during their storage. Of course, the distribution of losses depends on the characteristic of the product, the type of object (oil depot, main pipeline) and the nature of transshipment of oil and oil products. Therefore, one of the main problems is the development and implementation of means that reduce the loss of oil and petroleum products during their transportation and storage. 

Equipment and Process Descriptions

1.1 Equipment requirement

For uninterrupted operation of any serious enterprise engaged in the storage and processing of fuel, appropriate equipment is required. Therefore, equipment installed at oil depots is subject to high requirements [1]:

When operating the equipment, it is necessary to take into account the permissible service life (life) of the main equipment and the design life of pipelines and valves, which should be reflected in the design documentation and technical certificate.

Operation of equipment, mechanisms, tools in faulty condition or at faulty safety devices (interlocking, fixing and signalling devices and instruments), as well as at loads and pressures above passport ones is prohibited.

 Decommissioning of equipment, tools and instrumentation shall be performed by physical wear of their parts.

Repair of the equipment shall be carried out only after its shutdown, depressurization, stopping of moving parts and taking measures to prevent their accidental  actuation. A poster is always posted on the launcher: "Do not turn on - people work."

 Commissioning of newly installed or upgraded equipment is carried out after checking compliance with its design and requirements of technical operation rules.

 Start-up of equipment after overhaul (without modernization and change of location) is carried out with the participation of relevant specialists.

In case of non-compliance of equipment with the requirements of technical operation rules during technical inspection, installation or operation, it shall not be allowed for operation.

A change in the design of the equipment can be made only in agreement with the organization - the designer of this equipment.

Process systems for reception, storage and delivery of petroleum products (individual components of the systems) shall be equipped with the necessary monitoring, protection and blocking tools to ensure their safe operation.

During the start-up or shutdown of equipment (devices, pipeline sections, etc.) , measures should be provided to prevent the formation of explosive mixtures in the process system.

The use of equipment that does not correspond to climatic conditions in the category of design is not allowed.

Components, parts, accessories and components of equipment that may be a source of danger to employees, as well as surfaces of protective and protective devices, shall be painted in protective colors.

 Metal parts of the equipment which may be energized shall be structurally provided with visible elements for connection of protective grounding or grounding. The Grounding symbol appears next to these elements.

Moving parts of machines and mechanisms, radiation sources, etc., which can cause injury to workers or harmful effects on them, are protected or shielded. Fences and screens shall be interlocked with the equipment launcher.

Fences installed at a distance of more than 35 cm from the moving parts of the mechanisms can be made in the form of railings. If the guard is installed at a distance of less than   35 cm from the moving parts of the mechanisms , then it is made solid or mesh in a metal frame (frame).

Height of railing is determined by dimensions of moving parts of mechanisms. The height of the fence shall be  not less than 1.25 m. The height of the lower fence belt shall be 15 cm, the spacing between the axes of adjacent posts shall be not more than 2.5 m. The height of the mesh fence shall be not less than  1.8 m. The mechanisms less than  1.8 m high shall be completely enclosed. Mesh cell size must be less than or equal to 30 × 30 mm.

The height of the railings for the drive belts shall be not less than 1.5 m.  Metal frontal panels shall be installed from the outside of both pulleys in case of belt rupture.

Gear and chain gears are enclosed by solid metal shields (casings) having removable parts and devices for convenient assembly and disassembly.

Projecting parts of moving parts of machines and machines  (including shaft keys and rotating joints) shall be covered with casings along the whole rotation circumference.

Open the fence doors or remove the fences after the equipment or mechanism stops completely. Starting of equipment or mechanism is permitted only after installation in place and reliable fixation of all removable parts of the fence.

Winches, cranes and other lifting mechanisms shall have permissible capacity limiters, as well as reliable braking devices and retainers that prevent spontaneous movement of the load and the mechanism itself.

 Devices  (lock nuts, cotter pins, wedges , etc.) shall be provided on fasteners and connection elements of machines and equipment to prevent spontaneous bracing and disconnection during operation.

The equipment shall be installed on a solid foundation (foundation) ensuring its normal operation.

The equipment, which requires lifting the worker to a height  of 0.75 m, is equipped with steps,  and to a height above   0.75 m - with stairs with railings.

Stairs shall have a slope of not more than 60 ° ( for tanks  - not more than 50 ° ), the width of stairs shall be   not less than 65 cm , for ladders for carrying weights  - not less than  1 m. The distance between steps in height shall be not more than  25 cm. Steps shall have a slope inside 2-5 °.

On  both sides of the ladder stage, side planks or 15 cm high  side skin shall be provided to prevent slippage of human legs. Stairs shall be equipped on both sides with railings  1 m high.

Working platforms at the height shall have a flooring made of metal sheets with a surface that prevents sliding, or boards with a thickness of not less than  40 mm, a railing with a height of 1.25  m with longitudinal plates located at a distance of not more than  40 cm from each other , and a board with a height of not less than 15 cm tightly adjacent to the flooring.

The temperature of external surfaces of equipment and enclosures of heat insulation coatings shall not exceed the temperature of self-ignition of the least explosive product  , and in places accessible to employees there shall not be more than 45 °  C inside the premises and 60 ° C - on external installations    .

    

1.2 Tank equipment

Normal operation of tanks is provided by special valves and headset.

Each tank shall be provided with a ladder necessary for inspection of the equipment, sampling and monitoring of the oil product level. Stairs are built in ledge, spiral (along the wall of the tank) and shaft. Ladders shall have railings not less than 1 m high; ladder width is not less than 0.7 m, step spacing is not more than 0.25 m; inclination to the horizon of the march is not more than 60 °.

At the place where the stairs are attached to the roof of the tank, a measuring platform is built, surrounded by railings 1 m high in both directions of the stairs by at least 1.5 m. A measuring hatch, measuring devices and breathing fittings are installed on this site. [1]

The acceptance branch pipes are intended for connection to them of receiving or distribution pipelines outside the tanks and the clap or hinge of the lifting pipe from the inside. They are installed on the lower belt in an amount of one to four (with a high injection and pumping rate of 3000m3/h or more). Diameters of acceptance branch pipes are accepted from 150 to 700 mm.

The measuring hatch is used to measure the levels of oil product and product water in the tank, as well as to take samples using a sampler. The cover of the measuring hatch is sealed with the help of gasket and pressure hinged bolt. To indicate a permanent place of measurement inside the hatch there is a guide block along which a measuring tape with a lot is lowered into the reservoir. The shoe is typically made of copper or aluminum to prevent sparking.

The manhole is installed on the lower belt of the tank and is designed to enter the maintenance personnel inside the tank during its cleaning and repair, as well as to illuminate and ventilate the tank during these works.

The light hatch of vertical tanks is installed on the tank roof above the acceptance branch pipes. When the cover is open, light penetrates the inside of the tank and the tank is ventilated before grinding. A spare clap control cable is attached to the skylight in case of a break of the working cable.

Cotton (Figure 2) prevents the oil product from leaking from the tanks in case of damage to the acceptance pipelines and their gate valves. When filling the reservoir, the oil jet raises the cover of the cotton by pressure. When the transfer is stopped, the cover of the cotton under the influence of gravity drops to its place, closing the pipe. Tightness of the clap is achieved due to hydrostatic pressure of the liquid on the cover. When the oil product is discharged from the tank, the cover of the cotton is forcibly opened by means of a rotary drum with a cable winding on it. At remote control of oil products pumping, electric drive mechanisms for flapping opening are installed on tanks.      Large diameter flakes with a filled tank are difficult to open, as you have to overcome the weight of the oil column that presses on the cover of the flake. To facilitate the opening of the cotton, bypass pipes are installed to equalize the pressure before and after the cotton.

The breathing valve serves to communicate the space inside the tank with the atmosphere. The breathing valve (Figure 3) is a cast box (cast iron or aluminum) in which two valves are located. The valve 2 is opened when the pressure in the gas space increases and allows the gases to escape into the atmosphere, the valve 1 is opened when the vacuum occurs and allows the air to enter the reservoir.

Currently, new breathing valves of the NDKM type are installed on vertical steel and reinforced concrete tanks, designed for increased throughput and eliminating the possibility of fitting trays to seats in the autumn-winter period of operation.

Valve of NDKM type (Figure 4) consists of connecting branch pipe 1 with seat 2, plate 3 with membrane 4 clamped between flanges of lower housing 5 and upper housing 6, upper membrane 8 with disks 9 and adjusting weights 10. Membrane 8 is fixed in cover 11, in which there are holes for communication of chambers under cover with atmosphere by means of tube 12. Discs 9 and tray 3 are connected by chains 14. Intermembrane chamber communicates via pulse tube 15 with gas space of reservoir. Annular fire fuse 16 is arranged in lower housing. For ease of maintenance, the valve has a side hatch 7. Damping spring 13 is designed to eliminate shutter oscillations. Membrane is made of benzo-resistant rubberized fabric. Non-freezing of plate to seat is provided by coating of contacting surfaces with fluoroplastic film.

The valve is designed for a pressure of 2000 Pa and a vacuum of 400 Pa (in reinforced concrete tanks a vacuum of 1000 Pa is allowed).

The operation of the valve is as follows. If a vacuum is formed in the tank, there will also be a vacuum in the intermembrane chamber. When the difference in forces acting on both sides of the membrane exceeds the weight of the tray, it rises and atmospheric air enters the gas space of the tank. If excess pressure exceeds the design pressure in the tank, it is transferred to the intermembrane chamber, overcomes the total weight of the tray 5, discs 9 and weights 10, raises the tray by means of the chain 14. The steam-air mixture is released into the atmosphere.

Hydraulic safety valves are designed to limit excess pressure or vacuum in the gas space of the tank in the event of a failure of the breathing valve, as well as if the section of the breathing valve is insufficient to quickly pass gas or air. 

Safety hydraulic valves of CNG type are installed in complex with breathing valves of NDKM, the operation of which is based on the principle of ejection of hydraulic gate fluid (Figure 5). The valve consists of a body 8 with connecting flanges, a cup 7 for accommodating hydraulic shutter fluid, a shield 5 preventing liquid ejection during operation of the valve, an upper body 6 with a branch pipe for creating a hydraulic shutter fluid column, a fire safety 4, a cover 3 for protection against atmospheric precipitation and a pipe 2 for draining and filling liquid. The valve has a hinge connector, which makes it possible to easily inspect its inner part. Horizontal position of valve is adjusted along mirror of liquid in cup by means of studs 1. The operation of the valve is as follows. When the pressure in the tank and in the cavity a increases, the liquid from the cup is displaced into the nozzle and when the maximum permissible pressure value is reached, the liquid is discharged to the screen, reflecting from which it accumulates in the annular cavity b. In case of vacuum in the reservoir, liquid is displaced from the nozzle to the cup and, when activated, is ejected to the walls of the housing, through which flows into the annular cavity in. The area of the annular gap a between the branch pipe and the partition does not exceed two areas of the branch pipe, that facilitates ejection of liquid from this gap onto the cup cover and then onto the valve body walls. The discharged liquid is drained through the drain connectors and used for re-filling.

Fire protectors are installed between reservoir and breathing or safety valve. They prevent flame or spark from entering the gas space of the tank. The fire protector consists of a cast case with flanges, inside of which there is a cartridge made of stainless metal (foil), which forms channels of small diameter.

The principle of the fire fuse is that the flame, falling into the system of channels of small cross section, is divided into separate small flows. The contact surface of the flame with the fuse increases, heat transfer to the walls of the channels increases, and the flame goes out.

A siphon valve is used to lower the product water from the tank, which is a pipe (Figure 6) passed through the gland into the tank. With the help of a special handle, the siphon valve can be installed in the operating position - the curved end of the pipe is at the bottom of the tank and the water that has fallen out of it and accumulated at the bottom will be forced out of the tank by the pressure of the oil column. Pipe is turned horizontally or vertically upwards to bring it into inoperative position. Water from the pipe is removed by discharging part of the oil product. The siphon valve is protected by a special casing from damage and precipitation.

To measure the level and take samples of oil products, the tanks are currently equipped with buoyancy remote level gauges UDU5 and reduced AKP samplers. The float of the UDU5 level gage is moved up and down together with product level in the tank. The belt, to the end of which the float is attached, is brought out onto the tank wall; its second end is wound on a drum located in a chamber fixed on the tank wall at a height of about 1.5 m from the tank base. The operator can read the product level readings in the tank through the camera window. These readings can be transmitted over a distance by means of telemeasures.

The reduced sampler allows a height average sample of the product in the tank to be taken.

During storage of oil products of classes III and IV, lifting pipes are installed on the outlet pipelines inside the tank, which allow to take oil product from the upper layers of the tank, where it has the highest temperature and is cleanest, since dirt and water, settling under the influence of gravity, are collected in the lower layers (Figure 7). Lifting pipes are pivoted on hinges. If the end of the pipe is raised above the oil level by the winch, leakage from the tank is prevented when the release pipelines or their gate valves are damaged, that is, the lifting pipe acts as a clap.

The oil product burning in the tank can be extinguished by means of foam, which isolates the surface of the oil product from air oxygen. Foam is introduced into the tank through foam cameras mounted in the upper belt of the tank (Figure 8). Foam supplied under pressure through pipes 1 from foam-reactive units tears membrane 2 out of oiled cardboard or sheet lead installed in chamber 3 to prevent leaking of gasoline vapors, enters the surface of oil product and stops burning. The number of foam cameras installed on the tank depends on its diameter; for every   8-10 m of the circumference of the tank, one foam chamber is placed.

In the upper point of the roof of tanks intended for storage of dark oil products and oils, a ventilation pipe is installed (see Figure 9) to communicate the gas space of the tank with the atmosphere. The cross section of the branch pipe is tightened with a mesh with a cell size of 0.5-0.7 mm. The branch pipe is closed from above with a removable cap. The diameter of the ventilation nozzle is 150-250 mm. [4]

Process Operations

Reception and shipment of petroleum products.

Oil and oil products are transported by main oil pipelines and oil product pipelines, railway, road, air, sea and river transport in accordance with the rules valid on each mode of transport approved in the established manner. Oil depots should have obligations to supply oil products to consumers in a given assortment, volumes and delivery dates.

Storage of oil and oil products.

Oil products are stored at oil depots in tanks, barrels, bidons and other containers.

The tanks shall be operated in accordance with the "Regulations for the technical operation of metal tanks and their repair instructions" and these Regulations. Special attention shall be paid to tank sealing and equipment.

Each existing tank shall be in accordance with the standard design; have a technical passport; Be permanently equipped with a complete set of equipment provided for by the project and meeting the relevant standard; have breathing valves corresponding to the overpressure provided by the design, as well as the capacity of filling and emptying the tank; have serial number clearly written on the housing, refer to Job Instruction and process diagram of the tank farm; The number of the buried tank shall be indicated on a specially installed plate.

Oil and petroleum products of each grade or grade shall be stored in separate, serviceable tanks intended for them, excluding the ingress of atmospheric precipitation and dust into them. [2]

Heating of oil and oil products.

Oil and oil products are heated with the help of heaters, which provide heating of viscous oil products or maintenance of optimal temperature in order to perform the required pumping capacity, economical consumption of steam and electricity.

Cleaning and dehydration of oil product at oil depots.

Compounding of petroleum products.

Compounding - mixing of two or more components to obtain a specified quality oil product.

 Compounding procedure (technology): compounding, addition of additives, additives and components to commercial gasolines in order to increase the octane number of compounding , addition of additives, additives and components to non-standard petroleum products in order to obtain gasoline of the specified quality.

General information on oil depots and oil products

2.1 Classification of oil depots

Oil depots are divided into:

total capacity and maximum volume of one tank;

by functional purpose (transshipment, transshipment and distribution);

transport links for the receipt and shipment of petroleum products (railway, water (sea, river), pipeline, road, as well as mixed water-railway, pipeline-railway, etc.);

according to the nomenclature of stored oil products (oil depots for flammable and combustible oil products, as well as general storage oil depots);

annual cargo turnover (1 class with a cargo turnover of 500 and more thousand tons/year; Class 2 with cargo turnover of St. 100 to 500 incl. Thousand tons/year; 3rd class with cargo turnover of St. 50 to 100 incl. Thousand tons/year; Class 4 with cargo turnover St. 20 to 50 incl. Thousand tons/year; 5th class with cargo turnover from 20 and less than thousand tons/year). [3]

Classification of petroleum products

Chemical classification - its basis is mainly the content of one or more classes of carbohydrates in oil. There are 6 types of oil: paraffin, paraffin-cyclane, cyclane, paraffin-naphthenoaromatic, naphtheno-aromatic and aromatic. In paraffin oil, all fractions contain a significant number of alkanes: gasoline - at least 50%, and oil - 20% or more. The number of asphaltenes and resins is extremely small.

In paraffinocyclane oil and their fractions, alkanes and cycloalkanes predominate, the content of arenas and surfactants is low. They include most of the oils of the UralVolga region and Western Siberia. Cyclane oil is characterized by a high (up to 60% or more) content of cycloalkanes in all fractions. They contain an amount of solid paraffins, resins and asphaltenes. Cyclanes include oil produced in Baku (Balakhan and Surakhan) and on Emba (Dossor and Makat), etc.

Paraffinonaphthenoaromatic oils contain approximately equal amounts of carbohydrates of all three classes, solid paraffins no more than 1.5%. The amount of resins and asphaltenes reaches 10%. Naphthenoaromatic oils are characterized by a predominant content of cyclanes and arenas, especially in heavy fractions. Aromatic oils are characterized by the predominance of arenas in all fractions and high density. These include the pro-Russian in Kazakhstan and the Buguruslan in Tatarstan  .

Process classification:

Class 3 (I-III) in terms of sulphur content in oil (low sulfur, sulphur and high sulfur), as well as in gasoline (boiling point - 180 ° C), in jet fuel (120240 ° C) and diesel fuel (240350 ° C);

type 3 by the potential content of fractions distilling to 350 ° C (T1T3);

4 groups on the potential content of base oils (M1M4);

4 subgroups by the quality of the base oils evaluated by the viscosity index (I1I4);

3 species by paraffin content (P1-P3).

Technical classification (according to GOST of Russia R 51858-2002):

In terms of total sulphur content in four classes (1-4);

By density at 20 ° C for five types (0-4);

By the content of water and chloride salts in 3 groups (1-3);

According to the content of hydrogen sulfide and light mercaptans for 3 types (1-3).

Classification of oil refining processes:

Physical (mass exchange) processes are achieved by separating oil into constituent components (fuel and oil fractions) without chemical transformations and removing (extracting) from fractions of oil, oil residues, oil fractions, gas condensate and gases of undesirable components (polycyclic arenas, asphaltenes, refractory paraffins), non-hydrocarbon compounds. Physical processes by mass transfer type can be divided into types:

Gravity (electric demineralizing installation), rectification (atmospheric tube (distillation);

Atmospheric vacuum tube, gas fractionating plant, etc.);

Extraction (deasphalting, selective purification, dewaxing by crystallization);

Adsorption (zeolite dewaxing, contact purification);

Absorption (absorption gas fractionation plant, H2S purification, CO2).

In chemical processes, processing of petroleum raw materials is carried out by chemical transformations to obtain new products that are not contained in the raw material. Chemical processes used in modern oil refineries, according to the activation method, chemical reactions are divided into:

Thermal (thermolytic) - thermodestructive and thermooxidative;

Catalytic - heterolytic, homolytic and hydrocatalytic.

Classification of marketable petroleum products:

Motor fuel. Depending on the principle of operation, engines are divided into: gasoline (aviation and automobile), jet fuel and diesel fuel.

Energy fuels. Divided into: gas turbine, boiler and ship.

Oil oils. It is divided into lubricating and non-lubricating. Lubricating oils are divided into motor oils for piston and jet engines; and transmission and axial, designed to lubricate automobile and tractor hypoid transmissions (gears of various types) and axle necks of railway cars and diesel locomotives.

Industrial oils. They are designed to lubricate machines, machines and mechanisms of various industrial equipment, operating in a variety of conditions and at different speeds and loads. According to the viscosity value, they are divided into light (sewing, separator, vaseline, instrument, spindle, velosite, etc.), medium (for medium modes of speeds and loads) and heavy (for lubrication of cranes, drilling rigs, equipment of open-hearth furnaces, rolling mills, etc.).

Power oils (turbine, compressor and cylinder) - for lubrication of power plants and machines operating under load, elevated temperature and exposure to water, steam and air.

Non-lubricating (special) oils. Designed not for lubrication, but for use as working fluids in braking systems, in steam jet pumps and hydraulic devices, in transformers, capacitors, oil-filled electric cables as an electrically insulating medium (transformer, condenser, hydraulic, vacuum), as well as such as vaseline, medical, perfume, lubricating and cooling liquids, etc.

Petrochemical raw materials. This group includes: arenas (benzene, toluene, xylenes, naphthalene, etc.), raw materials for pyrolysis (refinery and associated petroleum gases, straight-run gasoline fractions, alkene containing gases, etc.) [7].

Oil depot facilities and their location

The location of facilities on the territory of the oil depot should ensure the convenience of their interaction, the minimum length of process pipelines, water and heat networks, subject to all fire requirements. In general, the territory of the oil depot is divided into seven zones:

railway operations;

water operations;

storage of petroleum products;

operational zone;

treatment facilities;

auxiliary structures;

administrative and economic zone.

In the area of railway operations there are facilities for the reception and release of petroleum products by rail. The main objects of this zone: drain racks for the reception and disposal of oil products; pumping stations for the transfer of petroleum products from tank cars to tanks and vice versa; laboratories for oil products analysis. Of the possible schemes for filling petroleum products into railway tanks, the most preferred is sealed filling, which uses a sealing cover and a line for removing and collecting the steam-air mixture.

Railway tanks shall be drained forcibly or by siphon through their neck (upper drain), as well as forcibly or gravity through the drain device located at the bottom of the tank (lower drain).

In the area of ​ ​ water operations, facilities for the reception and delivery of oil products by tankers and barges are concentrated. These include: oil and gas; moorings and piers for mooring oil vessels; stationary and floating pump rooms. To prevent oil products falling on the surface of the water from flowing through the water, the oil and gas industry is separated from the rest of the water space by floating boom fences. Berths located parallel to the shore and piers located at some angle to the shore serve for mooring oil vessels.

Connection of oil depot pipelines with oil vessels is carried out either by means of flexible rubberized hoses (hoses) or by means of articulated pipelines (stenders). The diameter of the stand reaches 500 mm, and the working pressure in them is 1.6 MPa. The stenders are more reliable than the hoses and provide a higher capacity for dump operations.

In the area of oil products storage there are: tank farms for light and dark oil products: tanks of small capacity for issuing small batches of oil products (meters); piling - fences around tank farms that prevent the bottling of petroleum products when tanks are damaged.

In the area of ​ ​ treatment facilities, facilities are concentrated for the purification of oil-containing waters from oil products: oil tanks; flotators; pond traps; silt sites; sludge accumulators; onshore ballast water treatment plants; pump rooms. [8]

Tank Maintenance

Technical inspection of tanks is carried out by the Technical Supervision Department in accordance with the "Technical Inspection Schedule for Tanks," approved by the chief engineer of Kogalymneftegaz CCI. Partial technical examination is carried out at least once every five years, full technical examination - once every ten years.

The main equipment and valves of the tank shall be subject to preventive inspections in accordance with the "Schedule" approved by the chief engineer of NGDU. Inspection and maintenance results shall be recorded in the inspection log of the main equipment and valves of the tanks.

The settlement of the base of each tank shall be systematically monitored according to the "Plangraphy of tank leveling" approved by the chief engineer of NGDU.

In the first four years of operation of the tanks, it is necessary to carry out annual leveling at absolute elevations of the bottom or top of the lower belt in at least eight points, but at least 6 m. In subsequent years, after stabilization of the sediment, control leveling should be carried out systematically (at least once every five years).

To measure the sediment of the tank base in the plant area, a depth reference shall be installed below the freezing depth.

During inspection of welded tanks, special attention should be paid to welded vertical seams of the lower belts of the housing, seams of welding of the lower belt to the bottom (butt angle seams), seams of bottom edges and receiving areas of the base metal. Results of inspection of joints shall be recorded in the inspection log of main equipment and valves of tanks.

When cracks occur in the seams or the main metal of the flat corner of the bottom, the active reservoir must be immediately released, emptied and cleaned. When cracks occur in the seams or in the main metal of the wall, the active reservoir must be released in whole or in part depending on the method of its repair.

Each tank shall undergo periodic routine, medium and major repairs:

• current at least once every six months;

• average at least once every two years;

• Overhaul shall be carried out as required based on the results of health checks as well as inspections during cleaning of the tank from contamination. [4]

Tank Technical Documentation

The technical documentation package shall include:

• documentation for the manufacture and installation of the tank;

• operational documentation;

• repair documentation.

For each tank in service shall be;

• technical passport of the tank in accordance with SNiP III1875;

• tank calibration table;

• Tank routing;

• maintenance log;

• lightning protection operation log, protection against manifestations of static electricity;

• base leveling scheme;

• design of lightning protection and tank protection against static electricity;

• orders, certificates for tank equipment replacement;

• procedures for replacement of tank equipment;

• acts.

If there is no technical documentation for the tank for the duration of construction, the certificate shall be drawn up by the company operating the tank and signed by the chief engineer of the enterprise.

The certificate shall be drawn up on the basis of detailed technical inventory of all tank parts and structures.

Tank Maintenance Instructions:

- during the current maintenance of the tank and its equipment, it is necessary to check the tightness of detachable connections (flange, threaded, gland), as well as the places of adjoining the valves to the tank body. If a leak is detected, tighten the bolted connections, correct the gland seals and replace the gaskets;

- during inspection of each type of tank equipment it is necessary to:

- monitor serviceable condition of measuring hatch, its hinge and gasket rings, serviceability of butterfly thread, guide plate, density of roof adjoining;

 provide in the breathing (mechanical) valve designed for pressure up to 2 kPa, smooth movement of the valve trays and their tight fit in the sockets; prevent fitting of valve trays to sockets; keep the valve nets clean in winter and free them from frost and ice; in the NDKM valve, prevent rupture of the internal surface, leaks of the flanges, valve manhole, chain breakage, overgrowing of the pulse tube with frost, ice, dust clogging, membrane rupture, shock absorber spring failure;

 monitor the serviceability of the breathing valve, designed for a pressure of 0.07 MPa, in accordance with the manufacturer's instruction.

During operation, the breathing valves shall be inspected and adjusted periodically in accordance with the manufacturer's instruction, and the integrity of the fluoroplastic coating shall be checked; membranes, plates, and in winter, clean the inner surfaces of ice and frost;

 check the oil quality and design level in the safety (hydraulic) valve, maintain the horizontal level of the cap, and contain a net partition in the cleaning. In CNG valves in winter, clean the inner surface of the cap from frost and ice with washing in warm oil. In membrane valves monitor the condition of the membrane, cleanliness of connections, channels, operating fluid levels in the pressure gauge;

- monitor horizontal position of the disco reflector, strength of its suspension;

- provide tight attachment of the cartridge to the gasket in the housing, cleanliness of bags with corrugated plates, clogging them with dust and frost in the fire safety device;

- monitor the density and impermeability of the fire fuse cover and flange connections; damaged plates detected during fuse inspection shall be immediately replaced with new ones;

- check presence and serviceability of diaphragm and nuts with gaskets at the ends of foam pipes in the foam chamber; monitor the density of the foam chamber connection to the tank, the strength of the foam pipes attachment to the tank body; in foam generators GPS2000, GPS-600, GPS200 it is necessary to monitor the correctness of the position of the sealing cover (pressing must be uniform and tight), parts, the integrity of the cassette mesh, make sure that there are no external damages, corrosion on the mesh wire (if there are signs of corrosion, the cassette should be replaced);

- check the correctness of level measuring instruments and other measuring instruments in accordance with the manufacturer's instruction;

- check serviceability of the manual pump and valves of air and hydraulic systems in the stationary type sampler; make sure that there are no traces of corrosion, dirt, etc. on the outer part of the drain unit; monitor the tight closing of the sampler cover;

- check the correctness of the clap or lifting (hinge) coarse in the receiving branch pipes (lifting must be light and smooth); monitor the serviceable condition of the cable and its attachment to the winch; monitor tightness of welding welds of reinforcing ring and flange, branch pipes, as well as density of flange connections;

- check serviceability of the cotton with control in the acceptance pipe by opening and closing it; control of the cotton should be carried out easily without jamming;

- check the state of reliable insulation on tank valves in winter and, if necessary, release accumulated water from the valve body to avoid freezing; detect the presence of fistulas and cracks on the body of gate valves leaked through flange joints; ensure tight closing of the rams (clinket), free movement of the flywheel along the spindle, timely packing of glands;

in siphon  valve check if there are leaks in valve glands (the crane turn must be smooth, without jamming); Make sure that the intake outlet is in horizontal position and the drain valve is closed by the shut-off casing.

- monitor the condition of bottom and butterfly weld edges (no cracks, fistula, corroded areas); deviations of the bypass duct by height shall not exceed the permissible values;

- monitor the condition of welds, rivet joints of the tank (whether there are no weeds, leaks, cracks in the welds, in the main metal near rivets and welds);

- monitor the condition of the manhole (flange connection, gasket, welded connections);

- monitor the condition of the pavement (if there is no subsidence, vegetation cover, deep cracks); Storm water shall be drained by the tray, by the sewage network of the tank farm; monitor the external and internal condition of the route, rainwater and special wells (are there no damage to the masonry of the walls at the places of entry and exit of pipes, cotton, in the cable of cotton, are the pipes not crowded, are they not littered with soil or snow); monitor the condition of the well covers. [4]

Types of oil losses from evaporation

Losses of oil and oil products cause great harm to the entire national economy, therefore, the fight against losses is an extremely important and urgent task. To combat losses, you need to know the causes of losses of oil and oil products.

Losses come from leaks, evaporation, mixing of various grades of oil products and oils.

According to studies in the transport and storage system, about 75% of the losses of oil and petroleum products come from evaporation.

Evaporation losses. In a tank having a certain amount of product, the gas space is filled with a steam-air mixture.

Event Selection

Protective emulsions

The method of reducing losses from evaporation by using protective emulsions consists in the fact that a fluid concentrated emulsion with a lower density is placed on the surface of the oil product than that of the protected oil product. The advantage of this method of reducing evaporation losses is that the emulsion spreads well over the entire surface of the oil product, isolating it from the GP, regardless of the degree of deviation of the tank wall from the cylindrical shape. Protective emulsions can be used both in newly built and already operated tanks with any roof structure without its modernization.

Currently, protective emulsions of various compositions are known. For example, NIITransneft (now IPTER) tested an emulsion of the following composition (wt%): fuel TS1 - 56; water - 21.6; ethylene glycol - 1,2; gelatin dry - 0.3. The emulsion was a white homogeneous viscous mass with a density of 810 kg/m3.

The emulsion was tested in a 600 m3 oil tank with a density of 857 kg/m3. The emulsion thickness on the oil surface at the beginning of the test reached 20 cm. Tests of the protective emulsion showed that it reduces the oil loss from evaporation by an average of 80%. However, its stability (service life) was only 3 months, after which the emulsion collapsed and settled on the bottom of the tank. Due to the short service life of the emulsion, its payback period was more than 10 times the service life. As a result, the tested emulsion did not find industrial application. [14]

Gas Piping and Gas Equalization System (GUS)

One effective way to reduce oil losses from evaporation is to capture vapors of petroleum products displaced from the vessel. For this purpose, gas-equalizing bindings (Figure 10) are used, which are separate pipelines or a system of pipelines connecting the gas spaces of tanks or transport tanks.

The use of gas-equalization binding allows partially reducing losses from "big breaths." The efficiency of reducing losses when using gas piping depends on the coincidence coefficient of operations and pumping. It is estimated that the loss is reduced by an amount equal to the coincidence rate.

The simplest system consists of two tanks, one of which is filled with fuel, and the other is simultaneously delivered to the consumer. Under actual operating conditions, it is difficult to combine these operations, so usually gas collectors are additionally included in the gas balancing system, where the steam-air mixture is displaced when the tank is filled and from where it again enters the gas space of the tank when it is emptied.

During storage of low-boiling products GOST 151076 "Oil and oil products. Marking, packaging, transportation and storage "provides for the mandatory creation of gas equalization systems in those tank farms where the tanks are not equipped with floating roofs or pontoons. [14]

The use of gas golders included in the gas-equalization piping of tanks allows to significantly reduce losses with small coincidence factors.

Tanks storing leaded and unleaded gasolines, as well as petroleum products causing changes in physical and chemical properties of each other, shall not be included in gas piping. 

Conclusion

As a result of the work done, the basic information about tanks used at oil depots and pumping stations was re-examined. I also got acquainted with the main technological equipment used on tanks.

After familiarization with the theoretical part of the work, oil losses from evaporation during its storage in PBS1000 were calculated, including calculation of losses from small and large breaths, as well as calculation of losses from back exhalation. The data obtained from the calculation were analyzed, which made it possible to verify the need to take measures to reduce oil losses from evaporation.

Drawings of PBC1000 tank as well as the main equipment used at this facility are attached to the work.