RU158106U1 - MACHINE FOR PLASMA CLEANING OF EXTERNAL SURFACE OF PIPES - Google Patents

Abstract

A machine for plasma cleaning of the outer surface of pipes can find application for repairing oil and gas pipelines in highway conditions and at pipe repair plants. The working process of cleaning is based on a progressive plasma method, which began to be introduced in the gas and oil industries. The advantages of the plasma technology for cleaning metal surfaces from any contaminants lies in their versatility, the ability to use in route and stationary conditions, at low and high ambient temperatures. However, existing plasma machines have disadvantages consisting in insufficient productivity, increased fire hazard, problems of operation in winter conditions, insufficient environmental cleanliness. All these shortcomings are eliminated in the utility model. Cleaning performance is increased by combining plasma cleaning with preliminary mechanical cleaning. By mechanical cleaning, the old insulation is removed, which is easily removed in large areas due to friability and low adhesion to the pipe surface. In winter, coarse plasmatrons are used in the mechanical cleaning unit to soften and melt bituminous and polyethylene coatings. Durable old insulating coatings in the form of bitumen mastic, synthetic primer and modern multilayer polyethylene and polyurethane coatings are removed by plasma jets, against which no polymers and impurities can remain on the surface of steel pipes. In hydrocarbon plasma, in addition, the process of thermochemical reduction of oxides on metal surfaces, i.e. thermochemical plasma cleaning of the pipe surface from scale and rust to pure metal is realized. The proposed utility model implements new engineering solutions that eliminate the fire hazardous arbitrary ignition of old bitumen and polyethylene insulation. For this, the gap between the afterburner casing and the pipe surface and the direction of the plasma jets of the flare cleaning plasmatrons has been changed. The measures taken excluded the likelihood of the development of arbitrary burning of the old insulation and increased the performance of plasma cleaning. The introduction of a tender cleaning plasma machine made it possible to drastically reduce the length and number of hoses and cables providing torch plasmatrons, reduced weight and increased mobility of the entire machine due to its more compact design. In the utility model, environmental safety is improved by reducing harmful emissions into the environment. Prestarting heating of water mains was introduced to enable the operation of the cleaning machine in winter. The problem of highly efficient use of a plasma tube cleaning machine in stationary conditions at pipe repair and re-insulation plants has been solved. Thus, in the utility model, the shortcomings that are currently taking place in the analogues have been eliminated and new engineering solutions have been put in place, which increased the productivity of pipe cleaning, reduced the fire hazard and the environmental load on the environment.

Description

Technical field

The proposed machine belongs to the repair equipment of pipeline transport and can be used in the oil and gas industry, as well as in public utilities and water management for cleaning the outer surface of pipelines from dirt, scale, rust and old insulation. This machine can be used in the repair work of oil and gas pipelines and in pipe repair plants.

To carry out repair work, pipes are removed from the trench. For diagnosis, they must first be cleaned of old bitumen, rubber-bitumen, polymer or other insulation. At the same time, there should not be any remnants of old insulation on the pipe surface. After repairing the pipeline, a new insulating coating is applied to it. At the same time, for reliable adhesion of the protective coating to the surface of the pipe, the pipe must be cleaned to pure metal, i.e. all oxides (rust and scale), any oil and grease stains, traces of bitumen and primer must be removed. For such cleaning, the proposed machine is designed for external cleaning of the surface of the pipes.

State of the art

Known devices for cleaning the outer surface of pipes are based:

- on the use of brushes and a frame with a mounted drive, providing reciprocating movement of the brush assembly along the pipe, or means for the reciprocating movement of the pipe being cleaned (USSR copyright certificate No. 640.772, RF patents No. 2.093.280, 2.145.911, 2.212. 959, US patent No. 4.771.499 and others);

- on the use of scrapers, frames, drives and knee supports (USSR copyright certificate No. 1.645.048, RF patents Ж№2.113.288, 2.219.004, US patent No. 6.158.074 and others);

- on the use of stands with peeling rolls placed in them with a tool mounted on the rolls, equipped with a roll rotation drive (USSR copyright certificates No. 168.894, 192.152, 607.863, 668.576, RF patent No. 2,383.403 and others);

- on the use of bead-blasting devices and automatic alignment devices of a self-propelled motor vehicle (USSR copyright certificate No. 112.900, 333.030, 1.549.735, RF patents No. 2.134.191, 2.148.522, 2.165.350,2.170.167,2.173.650, 2.240.223, 2.281.850, US patents Ms 5.056.27, 5.107.633, 5.267.417 and others;

- on the use of rotary machines, cutters and levers (USSR author's certificate F No. 1.329.845, 1.528.582, RF patents No. 2.128.092, 2.132.245, 2.163.172, US patent No. 5.603.136 and others);

- on the use of a frame with running wheels, a drive mechanism for working bodies and a control panel (USSR copyright certificate No. 995.908, RF patents No. 2.145.911, 2.219.003, US patent No. 4.306.914 and others).

All of the above devices designed for cleaning main pipelines and individual pipes have significant disadvantages:

- any mechanical cleaning (brushes, scrapers, shot, abrasives and sand) does not provide a high quality of cleaning, especially in winter there is a lot of dirt and traces of a protective coating on the pipe surface. The high quality of cleaning is not ensured even in the hot season, when the bitumen protective coating is softened and sticky. Mechanical particles (shot, sand, abrasive material) get stuck in the coating to be cleaned, and the brushes and scrapers are clogged with a viscous mass of bitumen, and smeared on the cleaned surface;

- as a result of mechanical cleaning, the pipe surface is damaged, risks remain and the weld bead is partially cut off, which impairs the strength of the pipe;

- mechanical cleaning with scrapers and brushes requires frequent replacement of the cutting tool.

Of the known devices, the closest analogue to the proposed one is "a complex for plasma-arc cleaning of the outer surface of trunk pipelines" RF patent for utility model No. 143764 B08B 9/023, priority from 08/09/2013.

The essential features of the claimed utility model, coinciding with the closest analogue is:

- the presence of a detachable or one-piece frame, mechanisms for the longitudinal reverse movement of the frame along the pipe being cleaned, one or several rotors on which the working cleaning bodies (brushes, scrapers, torch plasmatrons) are located, rotor rotation mechanisms, plasmatron cooling systems, plasma forming working fluid supply systems (PRT ) in the plasmatrons, afterburner casing, placed concentrically on the pipe.

The disadvantages of a close analogue are:

- low cleaning performance in cases of a large number of contaminants on the surface, especially when cleaning from old bitumen and film insulation;

- the likelihood of the occurrence of arbitrary low-temperature combustion of the cleaning products and old insulation on a large part of the pipe surface and under the afterburner casing and the associated risk of environmental pollution and fire hazard;

- a utility model, according to the analogue, is irrational to use in stationary conditions, for example, in pipe repair plants, due to pollution of the surrounding space by cleaning products.

All these disadvantages are eliminated in the proposed utility model.

Utility Model Essence

Cleaning the pipe surface from the old insulating coating and other contaminants (RF patent for utility model No. 143764 dated 08/09/2013) using torch plasmatrons in practice has proved its advantages and consistency. At the same time, these shortcomings were identified. In particular, when cleaning from old bitumen and film insulating coatings, which are used in 80% of all gas and oil pipelines in the country, mechanical cleaning methods are more productive. But it is impossible to clean the pipes mechanically without the bitumen and primer residues, especially in the folds of the welds, as required. Plasma-arc installation (RF patent for utility model No. 143764 dated 08/09/2013) performs high-quality cleaning, but at the same time, energy is wasted in cleaning up those contaminants that are easier and more productive to first clean mechanically. The idea to combine mechanical and plasma cleaning is implemented in the proposed utility model. According to the proposed utility model, the mechanical cleaning device is located in the bow of the machine, and the plasma completes the process. In this case, the cleaning performance of flare plasmatrons is aligned with the performance of mechanical cleaning, because not the entire mass of contaminants is cleaned by plasma, but only sections or a thin, durable layer of dirt that the working bodies of mechanical cleaning could not handle. As the working bodies of the mechanical cleaning device (block) in the utility model, metal brushes, scrapers, incisors, needle cutters, cutting blades, cones and abrasives, as well as shot blasting, sandblasting and other inkjet devices using abrasive particles, sand, are used, glass powder, metal fractions, liquids, gases and mixtures thereof. The use of mechanical cleaning at high (+ 40 ° C) and low temperature (-40 ° C) is fraught with big problems. At high temperatures, the working tool (scrapers, brushes, etc.) and the working medium (shot, sand, etc.) get stuck in the old coatings that are being cleaned from the pipe (bitumen, primer, etc.) and do not provide the necessary performance and quality of cleaning. Bitumen remains on the pipe. At low temperatures, the strength and hardness of the coating being cleaned increase sharply, hence the effectiveness of mechanical cleaning also drops. As a result of combining mechanical cleaning with plasma cleaning in a utility model, it was possible to provide high productivity with high quality cleaning in any weather conditions.

The use of propane or acetylene burners at the present time together with mechanical cleaning during pipe cleaning does not lead to such an effect due to the low temperature (maximum 2400 ° C for propane burners and 3200 ° C for acetylene) and the energy density in the stream of combustion products of these burners. On the contrary, their use, at best, leads to the evaporation of complex organic molecules into the environment, which are harmful. For example, during low-temperature (normal) burning of garbage, the surrounding area is polluted. In the worst case, the use of acetylene and propane burners leads to the melting of bitumen over the entire surface to be cleaned, which is unacceptable.

The essence of plasma-arc cleaning is expressed in the use of a qualitatively new method of cleaning metal pipes from the old insulating coating and any other contaminants. This method consists in the short-term exposure of a low-temperature plasma with a temperature of 6000-20000 ° C and an energy density of 10 ¹¹ W / m2 to the cleaned surface of the pipe, which does not leave any contaminants on the pipe.

The essential features of the utility model are the use of low-temperature plasma generators (flare plasmatrons) as a working tool for cleaning the main pipeline from old insulation and any other contaminants together with mechanical cleaning.

At this temperature of plasma jets and heat energy density, all known chemical elements and their compounds instantly evaporate or sublimate from the surface of a metal pipe, leaving the surface dry and clean, and if the plasma contains many ions and excited hydrogen and carbon atoms (when using hydrocarbon plasma-forming working fluids (PRT) or pure Н ₂ ), then on the surface being cleaned there is also a chemical reaction of the reduction of oxides to a pure metal. In this case, the cleaning of the pipe surface is carried out at the atomic level.

The plasma-arc cleaning process is environmentally friendly, since all organic molecules of the old insulation coating (mainly polyethylene and bitumen) dissociate under the influence of high temperature, i.e. decompose into their constituent atoms C, O ₂ , H ₂ , which, as a result of recombination (subsequent combustion) of complex carcinogenic molecules, form the simplest safe combustion products of the type CO ₂ and H ₂ O, which are waste products.

Thermal plants for the disposal of chemical weapons and toxic chemical compounds are currently operating on this principle (MN Bernadiner, AP Shurygin “Fire processing and neutralization of industrial waste.” M .: Chemistry, 1990.)

The proposed utility model can be used in the mobile version, i.e. in highway conditions and stationary at repair plants.

In mobile installations, torch plasmatrons are located on the rotors after the mechanical cleaning unit during the cleaning process and on the rotor in the mechanical cleaning unit to increase its productivity.

Cooling systems for plasmatrons and other heat-stressed parts of the cleaning machine and a system for supplying and storing plasma-forming working fluids in order to reduce the length of the hoses are placed in a tender. A tender, similar to a steam locomotive scheme, in the form of a separate movable unit of a mobile cleaning machine (MOM) is installed on the pipe being cleaned, mechanically connected to the working part of the MOM, has the ability to move along the cleaned gas pipeline along with the working part of the MOM. The mobility of the MOM along the pipe being cleaned is ensured by the presence of movement mechanisms on the mechanical cleaning unit, the plasma cleaning unit and the tender. Such an engineering solution allowed us to abandon a large number of refrigerant and PRT supply hoses to the plasmatrons. An additional way to reduce the length of communications and make MOM more compact is to use as structural elements, for example, frames, hollow parts (pipes) or create such cavities for storing PRT or refrigerant in MOM niches in them. Another important engineering solution by which the utility model differs from the closest analogue (RF patent for utility model No. 143 764 dated 08/09/2015) is to reduce the gap between the afterburner casing and the surface of the pipe being cleaned to 5-50 mm. The afterburner casing in the analog is used to limit the combustion surface of the old insulating coating under the action of torch plasma torch jets during cleaning. During the operation of MOM with plasma cleaning of gas pipelines, it turned out that without a afterburner cover they pose a great fire hazard. Then they introduced the afterburner casing into the design.

However, in this case, there was still a problem with the fire safety of the operation of such a machine. There remained the risk of uncontrolled ignition of the old insulation on the large surface of the pipe being cleaned.

In the proposed utility model, these problems are solved by the fact that the jets of the plasmatrons of the cleaning unit are not directed into the gap under the afterburner casing, as in the analogue, and the gap itself was limited to 5–50 mm. This ruled out the process of spontaneous combustion of the old insulation in such a small gap due to the difficulty of arbitrary influx of atmospheric air there, supporting the combustion process.

To exclude ignition of the old insulating coating, according to a utility model, the plasma jets are directed to the pipe section between the afterburner casing and the plasma cleaning unit. In this case, the afterburner casing prevents the spread of the front of the fire to the untreated pipe sections. Depending on the flammability of the old protective coating or the nature of pollution, this section has a length from the edge of the afterburner casing to plasma jets of 10-1000 mm.

The operating experience of machines with mechanical surface cleaning in winter has shown low cleaning efficiency due to the high hardness and adhesion to the surface of the bitumen and polyethylene insulation pipes at low temperatures, therefore, the proposed utility model provides for the placement and operation of coarse torch plasmatrons directly with mechanical tools . The purpose of these coarse plasmatrons is to soften, melt and partially remove the old protective coating and various other contaminants at low negative temperatures in the area of mechanical cleaning.

Brief Description of the Drawings

In FIG. 1 shows a mobile version of a machine for cleaning the outer surface of pipes.

In FIG. 1 submitted:

1. The pipe.

2. Block mechanical cleaning.

3. Working bodies of mechanical cleaning (scrapers, cutters, brushes, etc.)

4. Flare plasmatrons of rough cleaning.

5. The mechanism for moving the block through the pipe.

6. Mechanical connection between the mechanical cleaning unit and the afterburner casing.

7. Afterburner cover.

8. Mechanical connection between the plasma cleaning unit and the afterburner casing.

9. Plasma cleaning unit.

10. Flare plasmatrons of final cleaning.

11. Communications of plasmatron cooling systems, supplying them with PRT, power supply, control, etc.

12. Rotors of circular movement of flare plasmatrons cleaning.

13. Mechanisms of linear movement of the plasma cleaning unit.

14. The tender.

15. Closed plasmatron cooling system.

16. The supply system of PRT and capacity with stock PRT, power supply system and other systems for the operation of plasmatrons.

17. The mechanical connection of the plasma cleaning unit and the tender.

18. The mechanism for moving the tender through the pipe.

A. Plasma cleaning zone of the pipe surface.

B. The surface of the pipe after mechanical (and rough plasma for Fig. 1) cleaning.

B. The original surface of the crude pipe.

Utility Model Implementation

The machine for plasma cleaning of the outer surface of the pipes under route conditions is installed on the pipe or on the linear part of the main pipeline 1 of FIG. 1. In front of the machine there is a mechanical cleaning unit 2, which houses the mechanical cleaning bodies 3 and coarse flare plasmatrons 4. As a result of the mechanical cleaning unit 2, part of the old protective coating or dirt is removed from the original contaminated surface B of pipe 1, which relatively loose connection with the surface of the pipe or loose. The main and high-quality cleaning is carried out in zone A, where, under the influence of plasma jets, all contaminants remaining after mechanical cleaning are removed from the pipe surface. In this case, the afterburner casing 7 prevents the combustion zone from spreading towards the mechanical cleaning unit 2. This is ensured by a small gap between the wall of the afterburner casing 7 and the pipe surface 1 not exceeding, according to the utility model, 5-50 mm depending on the flammability of the old insulating coating or contaminants present. The length of zone A, where plasma jets clean, is determined by the distance from the edge of the afterburner casing (from 10 to 1000 mm) to the zone of influence of plasmatron jets, depending on the ease of cleaning of the old coating or other contaminants. The linear velocity of the edge of the afterburner casing and plasma jets of the plasmatrons along the pipe is the same, since they are mechanically connected 8, as well as with other parts of the machine 6 and 17. The cleaning performance of the plasmatrons 10 is high, because the surface of the pipe B is already cleaned, which has already been previously cleaned in the mechanical cleaning unit 2. In the plasma cleaning unit 9, rotors 12 are located on which flare plasmatrons of cleaning 10 are located in one or several rows. The rotors 12 make a circular and translational motion, cleaning the plasma surfaces from the plasma torches from the plasmatrons. The operation of the plasmatrons 10 is provided by cooling systems 15, the feed system of the PRT 16, the power supply system and other systems that are placed in the tender 14. The cooling system of the plasmatrons 15 in winter is heated to facilitate starting and prevent freezing of the refrigerant in the lines 11. All parts of the machine are moved reverse through the pipe being cleaned using the movement mechanisms 5, 13 and 18, or one of them. The pipe 1 in this case is stationary.

This utility model is designed and tested. On this machine, in experiments, the main innovations of the utility model were tested. The results proved that the introduction of preliminary mechanical cleaning and coarse plasmatrons increased productivity by 2-4 times. Reducing the gap between the afterburner casing and the pipe surface eliminated the arbitrary spread of combustion of the old insulation through the pipe, thereby eliminating fire hazard. This was also facilitated by a change in the direction of plasma jets. The introduction of tender 14 made the machine more compact and mobile, significantly reduced the length of working communications 11 and their mass. The introduction of preheating of the plasmatron cooling system facilitated operation in winter.

The utility model solved the problems of creating MOM plasma pipe cleaning for gas and oil industry.

The use of coarse plasmatrons 4 together with the working bodies of mechanical cleaning 3 allowed to increase the cleaning performance, especially in winter.

Claims (12)

1. A machine for plasma cleaning the outer surface of the pipes, containing a plasma cleaning unit with one or more rotors, a linear mechanism for moving the plasma cleaning unit through the pipe, torch plasmatrons mounted on the rotors, whose nozzles are directed to the surface of the pipe to be cleaned, afterburner casing, cooling systems and the supply of plasma-forming working fluids, a plasmatron power supply system, characterized in that the rotors are configured to perform circular and translational motion, and before the casing dozhigan I and plasma cleaning unit disposed mechanical purification unit. 2. The machine according to claim 1, characterized in that the mechanical cleaning unit has mechanisms for moving it along the pipe. 3. The machine according to claim 1, characterized in that the mechanical cleaning unit is interfaced with the afterburner casing and the plasma cleaning unit. 4. The machine according to claim 1, characterized in that scrapers, cutting blades, cutters, metal brushes, needle cutters, cones and abrasives are used as working bodies in the mechanical cleaning unit. 5. The machine according to claim 1, characterized in that abrasive particles, sand, glass powder, metal shot, liquid, gases and mixtures thereof are used as working bodies for mechanical cleaning. 6. The machine according to claim 1, characterized in that the mechanical cleaning unit has flare plasmatrons of rough cleaning. 7. The machine according to claim 1, characterized in that the afterburner casing is placed in front of the plasma cleaning unit with a concentrically cleaned pipe with a gap of 5-50 mm. 8. The machine according to claim 1, characterized in that the flames of the torch plasmatrons of the plasma cleaning unit are not directed into the gap between the afterburner casing and the pipe being cleaned, but are directed to the mechanically cleaned surface of the annular section 10-1000 mm wide between the plasmatrons of the plasma cleaning unit and the edge of the casing Afterburning, the afterburner casing is mechanically connected with the plasma cleaning unit and has the ability to move at the same speed with it through the pipe being cleaned. 9. The machine according to claim 1, characterized in that it is behind the plasma cleaning unit, in the course of cleaning, has a tender for placement of auxiliary systems, a communication tender and is mechanically connected with the plasma cleaning unit and coarse plasmatrons, placed on the pipe to be moved with the possibility of movement along with the plasma cleaning unit and coarse plasmatrons, it is placed on the pipe being cleaned with the possibility of moving along it together with the plasma cleaning unit. 10. The machine according to claim 9, characterized in that the tender contains a closed-circuit cooling system for plasmatrons and other heat-stressed elements of the plasma cleaning unit with a tank for the supply of refrigerant and / or a system for supplying plasma-forming working fluids to the plasmatrons with a capacity for the supply of a plasma-forming working fluid. 11. The machine according to p. 9, characterized in that the structural elements of the mechanical cleaning unit, the plasma cleaning unit and the tender have cavities for placing a refrigerant and / or plasma forming working bodies in them. 12. The machine according to p. 9, characterized in that the closed cooling system, plasmatrons and refrigerant lines are heated to operate the machine at low temperatures.

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