RU2274797C1 - Line for applying protective coating on outer surface of pipes - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: line comprises devices for heating preliminary cleaned pipes and applying protective coating on their outer surface. The line is provided with the steam generator with furnace device and chimney path. The device for heating is made of two shells for permitting longitudinal movement coaxially to the pipe and has face thickenings. The shells are mounted with a spaced relation one to the other. The first shell is provided with branch pipes for supplying steam and discharging condensate, and the second shell is provided with branch pipes for supplying and discharging flue gases. The branch pipe for supplying steam is connected with the steam generator, and the branch pipe for supplying flue gases is connected with the end of the chimney path of the steam generator.

EFFECT: expanded functional capabilities.

1 dwg

Description

The invention relates to devices for applying a protective coating to the outer surface of pipes and can be used in the oil and gas industry for the repair of oil and gas pipelines.

A device is known for applying a protective coating to the outer surface of pipes, including mechanisms for repeated coating and drying (see, for example, AS USSR No. 1790454, publication date - 01/23/93, Bull. No. 3). The main disadvantage of this device is the complexity associated with the ongoing process.

Closest to the present invention is a line for applying a protective coating to the outer surface of the pipes (see, AS USSR No. 1703192, publication date 01/07/92, Bull. No. 1). One of the elements of the line according to the invention is a device for the required heating pipe technology, made in the form of an inductor. The main disadvantage of the prototype is the significant energy costs and the associated low economic efficiency.

The objective of the present invention is to provide a line for applying a protective coating on the outer surface of the pipes that meets modern technological capabilities.

The technical result consists in increasing the efficiency of the line for applying a protective coating to the outer surface of the pipes, in simplifying the hardware design and in reducing energy costs.

The specified technical result is obtained due to the fact that the line for applying a protective coating to the outer surface of the pipes, including the devices located in the technological sequence for heating pre-cleaned pipes and applying a protective coating, is equipped with a steam generator with a furnace device and a smoke path, the device for heating is made in the form two installed with the possibility of longitudinal movement coaxially to the pipe with a gap to it and having mechanical seals of the shells, the first of which is equipped with on the connections for supplying steam and condensate drain, and the second - connections for supplying and outputting flue gases, wherein the nozzle for supplying steam connected to the steam generator, and a connection for supplying the flue gases - with the end of the flue of the steam generator tract.

The invention consists in the following.

According to the prototype, for applying a polymer coating, it is necessary to heat the pipe to 200-250 ° C. Currently known technologies for applying insulating coatings of heat-shrinkable polyethylene, requiring milder conditions, namely heating to 80-100 ° C. The present invention is provided mainly for this case, although it is technically feasible with a significant increase in the pressure obtained in the steam generator and the use of high-quality mechanical seals.

Raising the temperature of the pipe to 80-100 ° C can be carried out with water vapor at atmospheric or only slightly increased pressure.

Given the high thermal conductivity of steel, it is possible to assert the need for heating the entire pipe body, since the calculation for heating only the outer layer of the metal is unacceptable due to a rapid decrease in temperature associated with the transfer of heat from the outer layers of the pipe body to the inner ones. When heating the pipe with steam and heating the entire body of the pipe, a stable surface temperature is guaranteed, which allows strict fulfillment of technological requirements.

Naturally, when the pipe is heated by steam, the main heat entering the pipe body is the heat of condensation. Inevitable, therefore, is the appearance of condensation on the surface of the pipe. The main part of the condensate during the operation of the line flows from the pipe surface, and this process is accelerated by the presence of mechanical seals moving along the pipe. As a result, only a thin layer can remain on the pipe, which nevertheless requires complete removal, since the protective coating is applied to a dry surface.

The calculations and subsequent experiments show that the heat of the flue gases obtained in the steam generator is not enough to remove the moisture remaining on the pipe. Moreover, the full use of the heat of the flue gas is irrational due to the need to produce a second shell of a very large length. The main thing is that the process of heat transfer from flue gases is incomparably slower than the transfer of heat from the body of the pipe to the condensate film. Therefore, the main heat required to remove condensate comes from the pipe body, which is associated with a decrease in its temperature. Thus, if, when heated by steam at a pressure of 1 atm, it is possible to warm the entire pipe body to almost 100 ° C, then after removing the condensate film, the temperature of, for example, a route pipe with a diameter of 1 m decreases to 85-90 ° C, but corresponds to the required value. If a higher pipe temperature is required, steam with higher parameters can be used.

When implementing the present invention, water vapor can be obtained in a steam generator with a combustion device using natural gas, which is incomparably cheaper than the electric energy required to operate the inductor. If a steam generator is used with increased steam output, installation of a throttle device and apparatus for saturating the steam with lowering its temperature is necessary. The steam generator can be formed in another way. It is possible and advisable to use a fire-tube boiler to produce water with a temperature of 115-120 ° C (or higher). Next, you need a throttling body and apparatus for separating steam from chilled water (for example, up to 100 ° C with a decrease in hot water pressure to atmospheric pressure).

Schematically, the line for applying a protective coating to the outer surface of the pipes is shown in the drawing.

The line for applying a protective coating to the outer surface of the pipes includes a device for coating 1 and a device for heating the pipe. The device for heating the pipe is made of two shells 2 and 3. Both shells have mechanical seals 4 and are mounted with the possibility of longitudinal movement and with a gap to the pipe 5. The first shell 2 is equipped with a fitting 6 for supplying steam and a fitting 7 for withdrawing condensate. The second shell 3 is equipped with fittings 8 and 9 for the supply and output of flue gases. A steam generator 10 with a furnace device 11 and a smoke path 12 is introduced into the line (the end of the smoke path is indicated in the drawing). The fitting 8 of the second shell 3 is connected to the end of the smoke path 12. The fitting 6 of the first shell 2 is connected to a steam generator 10, i.e. actually with the release of steam from the steam generator.

The line for applying a protective coating to the outer surface of the pipe works as follows.

As mentioned earlier, the present invention is mainly applicable for the repair of oil and gas pipelines directly in the conditions of the route. A gas pipeline for hundreds and thousands of meters is lifted from the ground and thoroughly cleaned from the old insulation (completely different technological methods are used for this, of which jet water treatment using water at a pressure of 600-1500 kg / cm ^{2 is} considered the most modern and productive ) Next, a protective coating is applied after pre-heating the pipe.

For coating, the actual line that performs this process moves along the pipe (the direction of movement of the line is shown in the drawing).

When using the present invention, natural gas and water are supplied to the combustion device 11 of the steam generator 10 in an amount necessary for the formation of steam. Two shells 2 and 3 are put on the pipe to be protected (of course, a possible option is to use one shell with its separation into two chambers, which, in essence, is equivalent to using two shells; for this reason, the present description provides an option based on placement on pipe on the pipe of two shells). The steam generator 10 is connected by a steam line to the first shell 2, and the steam enters into it through the nozzle 6. The heating of the pipe 5 is due to condensation of the steam. Condensate is removed from the shell 2 through the fitting 7 (it is most correct to provide the fitting 7 with a hydraulic shutter). Further, the shell 3 runs into the heated section of the pipe 5. Through the nozzle 8 of the shell 3, flue gas enters from the smoke duct 12. Given the small length of the shell 3, the flue gas only partially expends its heat to evaporate the condensate film on the pipe 5. Evaporation mainly occurs due to the actual heat of the pipe 5. However, the flue gas plays the role of a transporting agent to remove steam from the shell 3. The flue gas is removed from the shell 3 through the fitting 9. Then, a device for applying the insulation coating itself runs onto the dried pipe 5 ytiya 1. To prevent loss of steam and mechanical seals are exceptions smoke workstation 4.

Using the present invention can significantly increase the efficiency of the line for applying a protective coating on the outer surface of the pipes. Applied very simple equipment. With the possible use of inductors in the conditions of the route, it becomes inevitable to introduce an electric generator into the composition of the line, i.e. Natural gas is also inevitable, but for the operation of expensive and qualified equipment (a gas-fired internal combustion engine, an electric generator, an inductor with a complex control system, etc.).

When working in stationary conditions with the use of inductors, very expensive electrical energy is used, or the system for producing electrical energy when gas is consumed must again be used.

Thus, the implementation of the invention reduces both capital and operating costs.

Claims (1)

A line for applying a protective coating to the outer surface of the pipes, including devices for heating previously cleaned pipes and applying a protective coating located in the technological sequence, characterized in that it is equipped with a steam generator with a furnace device and a smoke path, the heating device is made in the form of two installed with the possibility of longitudinal movement coaxially to the pipe with a gap to it and shells having mechanical seals, the first of which is equipped with fittings for supplying steam and water condensate, and the second - connections for supplying and outputting flue gases, wherein the nozzle for supplying steam connected to the steam generator, and a connection for supplying the flue gases - with the end of the flue of the steam generator tract.