RU2449205C2 - Method to restore pipelines and device for its realisation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to restore a pipeline includes pipeline cleaning from deposits, development of a chemical coating on the cleaned surface. At the same time pipeline cleaning from deposits and formation of a chemical coating are carried out simultaneously by a reciprocal movement of sleeves in the pipeline, an aqueous solution of chemicals (polyphosphates), a pipe-cleaning mechanism and gas. At the same time at each movement gas and aqueous solution are sent via the pipeline cleaning mechanism in the form of jets that are formed along the periphery of the pipe-cleaning device. Device to realise the method is made of two chambers installed at the pipeline ends. In the chamber there are driving reverse drums, onto which a flexible link is wound, being connected to the end of a sleeve by means of slings fixed along the perimetre of the open sleeve end. The second end of the sleeve is fixed along the chamber perimetre. The chamber cavity is communicated with a system of gas supply. The pipeline cavity upstream each unscrewed sleeve is communicated with a system of liquid (aqueous chemical solution) supply and a system of coating solution supply. Between the sleeves in the pipeline there is a pipeline cleaning mechanism made of hubs, where elastic tabs are fixed in a staggered order.

EFFECT: using the invention significantly speeds up the time of pipeline restoration and also simplifies technology and cost of pipelines restoration.

4 cl, 9 dwg

Description

The invention relates to the construction and is used in the construction and repair of pipelines.

A known method of cleaning pipelines from deposits, which consists in the fact that a pipe-cleaning device is moved through a pipe by a fluid pressure, while the liquid is passed through a cleaning device in the form of jets that remove deposits from the pipe’s inner surface, for example, international application WO 86/02293, B08B 9 / 04, C23F 11/00 of 04.24.1986

The disadvantages of this method is that it cannot form a chemical coating on the inner surface of metal pipelines during cleaning.

A known method of forming a protective coating using inhibitors, such as polyphosphates and silicates.

The method consists in the fact that a dose of polyphosphate or sodium silicate is supplied to the water.

The disadvantage of this method is that the input of the inhibitor is carried out continuously.

See the book of Kryazhevsky N.F., Kryazhevsky F.N. “Intensification of the work of group water supply systems”, pp. 290-299, ed. "Soviet Kuban."

A device for protecting the pipeline from corrosion by inhibition, including a system for supplying an inhibitor to the pipeline.

See the book of Kryazhevsky N.F., Kryazhevsky F.N. “Intensification of the work of group water supply systems", ed. “Soviet Kuban”, Krasnodar, 2000

The disadvantage of this device is that the inhibitor is constantly introduced into the pipeline, while in order to disinfect the water and the pipeline it is additionally treated with chlorine.

A known method for the restoration of pipelines, including cleaning the pipeline from deposits, applying to the cleaned surface of the coating. See patent RU 2358186 C2.

The disadvantage of this method and device is that they cannot clean the pipelines from deposits and apply a chemical coating to the cleaned surface.

In addition, these method and device have a number of significant disadvantages:

- all liquid supplied to the pipeline is used once;

- chemicals supplied to the pipeline are used once;

- limited time of interaction of chemicals with a cleaned surface;

- the coating composition is applied with a layer of 5-12 mm on the entire cleaned surface.

These shortcomings increase the cost of the work and increase the timing of their implementation.

Long-term studies conducted during the restoration of pipelines revealed the following:

- 5% of the pipeline surface is damaged by through fistulas;

- 40% of the pipeline surface is damaged by ulcers of various depths;

- 55% of the surface of the pipeline is not damaged.

Based on this, we proposed a fundamentally new technology for the restoration of pipelines, which consists in the following: cleaning the pipeline from deposits, forming a chemical coating on the freshly cleaned surface of the pipeline, plugging the pipeline with simultaneous filling of the ulcer cavities with a coating solution.

This reduces the cost of the work by about ten times and reduces the time by five times.

The objective of the invention is to simplify the technology and design of the device, increasing the speed of work and their durability.

The task is carried out by a combination of inventions.

Simultaneous cleaning of the pipeline with the application of a chemical coating, disinfection of the pipeline, plugging of the annulus and applying a coating composition to the inner surface of the pipeline speeds up the work.

Separating water from sediments saves water and inhibitors and speeds up the cleaning process and the formation of a chemical coating.

Rolling hoses through a pipeline greatly simplifies the technology.

Piping the chimney mechanism improves the quality of cleaning and coating.

The introduction of an inhibitor into the water increases the number of cavitation and accelerates the formation of a protective coating.

The implementation of the device from two chambers with a sleeve, supplying it with gas supply systems, liquid coating composition accelerates the process of restoration of the pipeline.

Installation between the arms of the pipe-cleaning mechanism speeds up the speed of work and increases the durability of the pipeline.

The execution of the pipe-cleaning mechanism of the hubs and elastic petals mounted on them in a checkerboard pattern, allows to increase the speed of the work and ensures their movement in both directions.

Providing the sleeve with a mechanism for opening its end allows to improve the quality of the coating.

The implementation of the mechanism for opening the end of the sleeve from slings connected to the sleeve by a flexible connection, simplifies the design of the device.

The drawings show:

figure 1 - camera;

figure 2 - device for implementing the method;

figure 3 - a device with a cyclone;

figure 4 - sleeve;

figure 5 - sleeve with an open end;

figure 6 - sleeve in the folded position;

7 is a device with a pipe cleaning mechanism;

in Fig.8 - pipe cleaning mechanism;

figure 9 - shows the cracks formed by the pipe-cleaning mechanism.

The device shown in Fig. 1 is made of a chamber 1, in which a drive reversing drum 2 is mounted, on which a flexible connection 3 (cable) is wound, connected to the end of the sleeve 4. The second end of the sleeve 4 is bent and fixed around the perimeter of the camera 1. The cavity 8 is in communication with the gas supply system 5. The cavity in front of the sleeve 4 is in communication with the liquid supply and removal systems 6 and the coating solution supply system 7.

The device depicted in figure 2, is made of two chambers 1 mounted on the ends of the pipeline 9.

The device shown in figure 3, is made of sludge collector 10, hydrocyclone 11, pump 12, sludge outlet 13.

The device depicted in figure 4, is made of a pipe 9, in which the sleeve 4 is moved, the end of which is connected to the slings 14 connected with a flexible connection 3.

The device shown in Fig. 5 is made of a pipeline 9 in which a sleeve 4 is installed, the end of which is connected to slings 14 connected with a flexible connection 3. The cavities 15 and 16 communicate with each other through the open end of the sleeve 4.

The device shown in Fig.6, is made of a pipe 9, in which there is a sleeve 4, from which the gas is released.

The device shown in Fig.7 is made of a pipe-cleaning mechanism 17 installed between the sleeves 4.

The device shown in Fig. 8 (pipe-cleaning mechanism) is made of hubs 18 on which elastic petals 19 are formed in a checkerboard pattern, forming slots 20 at its periphery, which are shown in Fig. 9. The pipe-cleaning mechanism 17 with the pipeline 9 forms elastic gaps 19 of the slit 20.

The device depicted in figure 1, operates as follows.

By rotating the drum 2 in reverse and feeding into the cavity 8 and removing compressed air from the system 5, the sleeve 4 is moved back and forth.

The device depicted in figure 2, operates as follows.

At the ends of the pipeline 9, chambers 1 are installed. After this, a system with a fluid agent supply system 7 is pumped into the pipeline 9 with a dose of sodium polyphosphate 100 mg / L in accordance with P ₂ O ₅ . When filling the pipeline 9 to 80% of its volume, compressed air is supplied to the left chamber 1. The sleeve 4 begins to move through the pipeline 9. The pressure in the left sleeve is increased to 0.6 MPa. After the sleeve 4 is deployed to its full length, its end opens. Air from the sleeve 4 exits into the cavity of the pipeline 9. After this, with the drum 2, the left sleeve 4 is returned back.

Compressed air is supplied to the right chamber 1 by system 5. The right sleeve 4 moves along the pipeline and moves water and air in front of it.

Example 1

Water ⌀ 800 mm and a length of 1000 m were cleaned of deposits.

Cleaning the pipeline from deposits and applying a chemical coating was carried out by the devices depicted in figure 3, 4, 5, 6.

Two sleeves 4 were made of polypropylene ⌀ 800 mm and a length of 100 m each.

The pipeline was filled with water with a dose of sodium polyphosphate 100 mg / L according to P ₂ O ₅ to 85% of the volume of the pipeline. The left sleeve 4 was moved 95 m and pumped with compressed air to a pressure of 0.6 MPa. After that, the right sleeve 4 was moved to 95 m and pumped with compressed air with a pressure of 0.6 MPa.

Then the drums 2 began to rotate in antiphase, unwinding the sleeves 4 per 100 m each.

When unwinding each sleeve 4 per 100 m, their ends opened and air from the cavity 16 was pulled out into the cavity 15, pushing water in front of it. A stream of water destroyed sediments.

When moving the sleeves 4 reciprocating flows of water and air destroyed deposits.

At appropriate flow rates of liquid, air, and sediment particles, cavitation developed that destroyed the deposits.

When air was discharged from the cavity 16 of the sleeves 4, its cross section decreased and the sleeve 4 was located only in the upper part of the pipeline 9. Then, large volumes of compressed air were pumped into the cavity 16 in one gulp. Sleeves 4 sharply increased in volume and displaced water from under the sleeves 4, which squeezed it out at a high speed, providing an increase in the total flow rate.

After a specified movement of the sleeves, the slurry outlet valve 13 was opened, which is located between the sleeves 4. Water, air and deposits began to flow into the hydrocyclone, which separated them into solid, liquid, gaseous components.

Air was discharged into the atmosphere, water returned to the pipeline, sludge entered the sludge collector 10.

This process was repeated until deposits ceased to flow into the sludge collector 10.

After that, the system 7, the water was removed from the pipeline 9.

Pipeline 9 was completely cleaned of deposits, a chemical coating was formed on its wall.

If the pipeline provided the specified strength and tightness, then work on this ceased.

If the pipeline did not provide the specified strength and tightness, then sleeves 4 were replaced by sleeves ⌀ 800 mm and a length of 1000 m.

After that, the right sleeve 4 was introduced to the left sleeve 4.

System 6 between the sleeves pumped a given portion of the coating solution, fiber concrete with basalt fiber.

Then the sleeves 4 and fiber-reinforced concrete were moved to the right end of the pipeline 9. The right chamber was dismantled.

The left sleeve 4 was left until the solution solidified, after which the left sleeve 4 was withdrawn from the pipeline 9.

The pipeline was plugged and covered with mortar. At the same time, the ulcer cavities were filled with a solution, an even layer of fiber concrete with a thickness of 0.5-1 mm was applied to the surface of the pipeline.

If the hardness of the deposits is more than 3 units on the Mohs scale, then use the device shown in Fig.7, 8, 9.

Between the sleeves 4 in the pipe 9 set the pipe-cleaning mechanism 17.

System 6, the pipeline 9 is filled with water with a dose of sodium polyphosphate 100 mg / l according to P ₂ About ₅ .

After that, the sleeves 4 are moved through the pipeline 9. The movement of the sleeves 4 is carried out in the same way as described above.

The diameter of the pipe cleaning mechanism 17 is larger than the inner diameter of the pipe 9, and takes an ellipsoidal shape.

The reciprocating movement of the sleeves 4 moves the water to the left, then to the right.

Water moves the pipe-cleaning device 17 through the pipeline 9 also reciprocating.

Part of the water overtakes the pipe-cleaning device 17 through the slots formed by the elastic petals 19. In the slots, the water accelerates. Particles of deposits, dissolved air and uneven surface of the pipeline 9 form cavitation nuclei that destroy deposits, clean the surface of the pipeline from deposits.

Cavitation activates the surface of the pipeline 9 and form an insoluble protective coating on its surface.

When the pipe-cleaning mechanism 17 moves, its petals 19 and the pipeline section are constantly vibrating. Vibration promotes cavitation.

Due to the fact that deposits are constantly removed from the surface of the pipeline 9, the cross section of the cracks, the friction force of the petals 19 about the deposits are constantly changing, which leads to jumps in the change in water pressure. It also contributes to the creation of cavitation.

The mechanisms for creating a protective coating and cleaning are described very briefly below; in fact, this mechanism is very complex.

When the chimney mechanism 17 moves along the pipeline 9, its inner diameter also constantly changes. Water then fills the internal cavity of the pipe-cleaning mechanism 17, then squeezed out of it.

The petals 19 around the perimeter open unevenly, so tangential jets arise, contributing to an increase in the number of cavitation.

The pressure of the water flow is constantly fluctuating.

Due to the increase in pressure, the petals 19 bend towards the periphery, and then towards the center.

The pressure of the flow on both sides of the petals 19 periodically varies.

Periodic oscillation of the petals 19 forms the following physical effect.

The fact is that the elastic petals are in contact with the pipe wall only with ribs. Therefore, the specific pressure of the petals on the deposits increases tenfold. A gap forms in the form of a segment between the upper lobe and the wall of the pipeline. Since the elastic petals fluctuate due to pulsations of the fluid flow, these vibrations are transmitted to deposits and the wall of the pipeline. Since the coefficients of linear expansion of the deposits and the walls of the pipeline are not the same, the oscillation frequency of the deposits and the walls of the pipeline are also not the same, and they have different oscillation amplitudes. There are cases that deposits and the wall of the pipe oscillate in antiphase.

All this leads to the formation of microcracks in the deposits, between the deposits and the wall of the pipeline.

These gaps increase all the time and join into larger gaps. Subsequently, the gaps are filled with gas and liquid. When the flow pulsates, liquid and gas are compressed in the gaps. During a decrease in pressure in the flow, forces appear in the cracks that tear deposits off the pipe wall.

In this case, there is always a gap between the petals 19 and the deposits, which constantly changes its cross section. Through this gap, a stream constantly flows, carrying away the destroyed deposits from the destruction zone.

In the zone of destruction of deposits, the gap between the petals 19 and the deposits constantly changes the cross section.

Since the substance is supplied to the deposits in the liquid phase and cavitation bubbles are created in the substance in the zone of destruction of the deposits, while cavitation bubbles in the substance are created by creating a periodically varying pressure having constant and variable components, and these components are selected from the following ratios:

P _t = 0.3 to 0.7 (P ₂ + P ₃ )

P ₂ + P ₃ —P ₁ = 1 to 10G;

where P ₁ is the constant component of pressure (MPa);

P ₂ - variable pressure component (MPa);

P ₃ - saturated vapor pressure of the processed substance at the temperature of its supply to the treatment zone (MPa);

G - tensile strength of the processed substance at a temperature of its supply to the treatment zone (MPa).

Subject to the indicated conditions of simultaneous action of alternating and static pressures on a substance in a liquid phase, cavitation bubbles form in a liquid at the moment when the sum of two quantities: the amplitudes of the alternating pressure and the pressure of saturated vapor of a substance at a given temperature exceeds the sum of two values: static pressure and liquid strength breaking at a given temperature. This moment in time coincides with the moment of action of the negative half-wave of variable pressure.

During the action of a positive half-wave of alternating pressure on the liquid, the navigation bubbles are affected by the sum of two pressures of the amplitude of the alternating pressure and the static pressure, which tends to compress the bubbles, i.e. slam them. At the moment of collapse of the bubbles, their walls under the action of the pressure difference acting on the cavitation bubbles accelerate, acquire kinetic energy and collide in the center. The magnitude of the kinetic energy acquired is sufficient to break the bond between the molecules, as well as between the nucleons, to overcome the repulsive forces of the nuclei and to carry out the interaction between the elementary particles contained in the nuclei of the processed substance. As a result, in the local area of the substance at the moment of the disappearance of the cavitation bubble (its collapse), a reaction occurs with the release of a large amount of energy, which is sent in the form of a shock wave to deposits and destroy them.

The effect of shock waves in a liquid on cavitation bubbles makes it possible to increase the energy release by an order of magnitude, therefore, the destructive force acting on deposits also increases.

If necessary, changes in energy release change the alternating pressure and / or static pressure by changing the power of a portion of the compressed gas, the flow pulses are created by increasing or decreasing the flow or discharge of the flowing product into and out of the pipeline.

The pulsating flow makes it possible to increase the collapse rate of cavitation bubbles. This leads to the fact that even large bubbles have time to collapse in the desired half-life. In addition, it contributes to the formation of cavitation bubbles by increasing the static pressure and its sharp decrease.

Oscillations of elastic petals increase the rate of formation of microcracks in sediments.

The formation of jets of fluid flow on the inner surface of the pipe, flowing from slots with different speeds, contributes to the formation of vortex motion of the jets. Also for this reason, compressive and tensile forces appear in the deposits, contributing to the formation of cracks in the deposits.

The location of the jets having a greater and lower outflow velocity on the surface of the deposits increases the forces compressing and tearing the deposits.

The separation of the fluid flow along the length of the pipeline into two zones, in which the pressure range of the flow is different, contributes to the creation of a pulsed change in the flow pressure, the creation of local water hammer. This also leads to oscillation of the pipe and sediments with different parameters, which contributes to a more effective destruction of sediments, while the fluid flow is saturated with a large number of smaller particles of sediments.

The contact of elastic petals with deposits only by ribs increases the specific pressure on deposits by tens of times, which leads to effective destruction of deposits, while cavities with incompletely removed deposits form on the wall of the pipeline. In the future, this leads to the grinding of these deposits and mixing with the fluid flow, after the destruction of these strips of sediment, liquid passages are formed through which the fluid flow penetrates into the cracks between the pipe wall and the sediment.

Cavitation occurs in the zone formed in places of increased shear and lower pressure. In this case, there are different types of cavitation. Since the petals oscillate, acoustic cavitation occurs.

The flow velocity is greatly reduced after the jets exit the slots. Here the pressure becomes higher than the vapor pressure. As soon as the conditions favorable for cavitation disappear, the bubbles immediately collapse. The energy released by the collapse of the bubbles vibrates the pipe and destroys the deposits.

Cavitation causes periodic fluctuations in pressure acting on the petals and pipe wall.

Most of the energy released by the collapse of cavitation bubbles is converted into sound waves that destroy deposits.

The mechanism of chemical coating formation on the inner surface of the cleaned surface of the steel pipe

When cavitation acts on water with sodium polyphosphate dissolved in it and deposits in it, ferrous iron is converted according to the following scheme:

Fe ²⁺ + O ₂ + 2H ₂ O + 4е → Fe ³⁺ + 4OH ^-

This process allows the second production of a hydroxyl radical.

Since there is a huge amount of tiny particles of sediment in water, the effect of many short-circuited galvanic couples arising from the contact of two or more materials having different values of electrochemical potentials with water and dissolved oxygen in it is obtained.

Fe ⁰ -2e = Fe ²⁺

Fe ²⁺ + 2OH ^- = Fe (OH) ₂

4Fe (OH) ₂ + O ₂ = 4FeOOH + 2H ₂ O

O ₂ + H ₂ O + 4e = 4OH ^-

The ability of Fe ⁰ to direct electron transfer in aqueous solutions leads to the creation of protective coatings, mainly from the sparingly soluble iron oxide hydrate [Fe (OH) ₂ ], and the formation of phosphate compounds.

Studies have shown that the inner layer adjacent to the metal is Fe ₃ O ₄ , followed by Fe ₂ O ₃ , finally, the outer layer consists of insoluble compounds of various elements: manganese dihydrogen phosphate Mn (Н ₂ РО ₄ ) ₂ , iron dihydrogen phosphate Fe ( H ₂ PO ₄ ) ₂ .

Me (H ₂ PO ₄ ) ₂ = Me ²⁺ + 2H ₂ PO ₄ ^-

H ₂ PO ₄ ^- = H ⁺ + HPO ₄ ^2-

NRA ₄ ^2- = H ⁺ + PO ₄ ^3-

Salts of two- and trisubstituted phosphates of manganese and iron are poorly soluble, therefore, in the process of dissociation of salts in a layer adjacent to the surface of the product, a complex of insoluble compounds is formed. These are approximately calcium phosphate compounds formed by cavitation.

It has been established that during cavitation a combination of two or more activators containing phosphorus is formed.

After the solution solidified, the pipeline was tested for strength. The strength was 10% higher than the strength of the new pipeline.

The use of the invention significantly speeds up the recovery time of the pipeline, and also simplifies the technology and cost of restoration of pipelines.

Claims (4)

1. A method of pipeline recovery, including cleaning the pipeline from deposits, the formation of a chemical coating on the cleaned surface, while cleaning the pipeline from deposits and the formation of a chemical coating is performed simultaneously by reciprocating the hoses, an aqueous solution of chemicals (polyphosphates), a pipe-cleaning mechanism, and gas, with each movement of gas and an aqueous solution is passed through a pipe cleaning mechanism in the form of jets that are formed around the periphery of the pipe stnogo device. 2. The method according to claim 1, characterized in that during the treatment the water and the destroyed deposits are separated from each other, while the deposits are removed from the pipeline, and the water is reused for cleaning. 3. The device for implementing the method according to claim 1, made of two chambers installed at the ends of the pipeline, while the chambers are equipped with drive reversing drums, on which a flexible connection is wound, connected to the end of the sleeve with slings attached around the perimeter of the open end of the sleeve, this the second end of the sleeve is fixed around the perimeter of the chamber, and the cavity of the chamber is in communication with the gas supply system, and the pipe cavity in front of each inverted sleeve is in communication with the fluid supply system (aqueous solution of chemicals) and systems th feeding the coating solution, wherein between the arms is mounted in the conduit truboochistnoy mechanism which is made of a hub on which are fixed in a staggered elastic pitch. 4. The device according to claim 3, characterized in that it is further provided with a device that separates liquid, gas and deposits from each other.

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