SU902878A1 - Pipeline washing method - Google Patents

Description

(54) METHOD FOR WASHING PIPELINES

I

The invention relates to methods of flushing pipelines from solid insoluble contaminants and can be used in mechanical engineering and other industries;

There is a known method of flushing pipelines with a stream of liquid, in which gas 1 is introduced into the stream of washing.

There is also known a method of repeated flushing of pipeline systems by supplying it with compressed air and pressurized water followed by removal of the water-air mixture from the system, in which water is supplied only to one of the pipes of the system, and compressed gas to the other, followed by air transfer to a pipe with water and a water-filled pipe with air 2.

However, these washing methods do not determine the optimal conditions under which the maximum flushing effect is observed both in the separation of the particles from the pipe walls and in their removal from the flushed pipeline system.

There is a known method of flushing pipelines with a gas-liquid stream, in which the flushing is carried out in the slug flow regime of the gas-liquid mixture with a flow rate gas content of 5 0.74 - f 0.81, where - Qr is the gas flow rate; Q-volume flow rate 3.

This method is the closest to the technical essence and the achieved result.

However, the known method is not effective for transporting (transporting) contaminant particles from the pipeline system, since during the curved flow regime the number of gas bubbles is small and the probability of a bubble colliding with the contaminant particle is insignificant. Therefore, flotation processes characteristic of the motion of a gas-liquid mixture in a bubble flow regime with lower gas contents, in which the gas moves in the form of a large number of small bubbles, are underutilized.

The aim of the invention is to increase the efficiency of washing by providing optimal conditions for both the separation process and the process for the removal of contaminants.

The goal is achieved by the fact that when the gas-liquid flow is supplied, the projectile regime

alternate with a bubble feed mode with a volumetric gas content of 0.55-0.60, with the feed modes alternating with periods determined from the relation:

AND

where t, is the duration of the flushing in the bore flow regime; t is the duration of washing in the bubble flow regime.

With the alternation of bore and bubble flow regimes of the gas-liquid mixture, the following occurs. When the flow mode is low, due to the high velocity of the fluid near the walls, the particles are detached and interleave along the wall. With such a movement between the particle and the wall of the pipe a film of liquid forms, and since the contact of the particle with the surface of the pipe disappears, the adhesion forces (sticking) of the particle to the wall are zero. When the gas-liquid mixture is introduced into the pipeline in the bubble mode, the detached particles collide with the gas bubbles, adhere to them and due to this they are effectively removed. However, the process of collision of bubbles and particles is random (probabilistic). The longer the flushing in the bubble mode takes place, the more particles will collide with gas bubbles. But if the particle at the initial moment of time did not collide with a bubble, then it begins to settle on the pipe wall under the influence of gravity. In this case, the liquid film between the particle and the wall of the pipe disappears, the particle comes into contact with the surface of the pipe, and again the adhesion force of the particle to the surface arises. In this case, it is necessary to tear the particle off the surface again by increasing the velocity of the fluid near the wall, i.e. it is necessary to apply a gas-liquid flow in the projectile flow regime and repeat the flushing cycle again. Therefore, by alternating the billet and bubble flow regimes of the gas-liquid mixture, it is possible to achieve maximum washing quality, since each alternation cycle allows a certain amount of particles to be washed out of the piping system.

FIG. 1 shows a diagram of an installation for carrying out a washing method; in fig. 2 - dependence of the volume of contaminants torn off from the pipeline wall on gas content; in fig. 3 - dependence of the volume of impurities delivered from the flushed pipeline on gas content.

The installation includes a tank 1, a pump 2, flow meters 3 and 4, check valves 5 and 6, adjustable throttles 7, 8 and 9, a transparent insert 10 for visual observation of the gas-liquid-flow mode, flushed pipeline 11, filter 12, distributor 13, cylinder 14 with

compressed gas sensors 15 and 16 to monitor the effectiveness of the flushing.

The installation works as follows.

The washing liquid from the tank 1 is pumped to the flushing pipeline 11 by the pump 2 through the flow meter 3, by means of which the volumetric flow rate (RL) is controlled. The flow rate is controlled by the adjustable throttle 7. The compressed gas from the cylinder 14 through the flow meter 4, using which is controlled by the volumetric gas flow rate (Qr), is fed into the flow of washing liquid through adjustable inductors 8 and 9 and the distributor 13. By means of chokes 8 and 9, two required gas flow rates (or gas content) are established. The distributor 13 allows gas to be supplied to the washing liquid stream either through one throttle or through the other and thereby flush with alternating two modes with different gas content.

The alternation of the bore and bubble modes of its supply with the volumetric gas consumption is 0.55-0.60 with periods - | - | - allows you to tear away from the walls and remove from the pipeline by 10-30% more contamination than when flushing the pipeline with a gas-liquid flow only in the front-flow mode with a gas content of 0.74-0.81, where ti is the duration of washing snag bottom flow mode; t is the duration of washing in the bubble flow regime.

Claims (3)

1. USSR author's certificate number 229126, cl. F 17 D 1/16, 1967. 2. USSR author's certificate number 348246, cl. At 08 At 7/00, 1970. 3. Sapozhnikov V. M. Installation and testing of hydraulic and pneumatic systems of aircraft. M., “Engineering, 1979, p. 118-120 (Prototype), (° l) % "(/ .; 0.2 az nd flf O.ff 0.7 0.8 a / UI WOOCM / C 0 Q-i-WOcn / C 0.3 J .5