CN105135153A - Method for inhibiting corrosion on inner wall of metal conveying pipeline - Google Patents

Abstract

The invention provides a method for inhibiting corrosion on the inner wall of a metal conveying pipeline. According to the method, a plurality of groups of electron capturers made of a metal material are perpendicularly arranged on the inner wall of the metal conveying pipeline, and utilized for adsorbing charged particles in a fluid, so that electrochemical corrosion of the metal conveying pipeline can be reduced. The method has the advantages of small investment, easy implementation and the like; through adoption of the method, the corrosion depth of the metal conveying pipeline can be reduced by about 60%, and the effect in inhibiting corrosion of the metal conveying pipeline is remarkable.

Description

Method for Inhibiting Corrosion of the Inner Wall of Metal Conveying Pipeline

technical field

The invention belongs to the technical field of metal surface anticorrosion, and specifically relates to a method for inhibiting the inner wall corrosion of metal transportation pipelines

Background technique

Metal pipeline is a tool used to transport liquids and gases over long distances, usually used to transport oil, natural gas, gas, and chemical and chemical products. Since the transportation method using metal pipelines has a series of advantages such as large volume, continuous, fast, economical, safe, reliable, stable, small land occupation, and low cost, it has become a transportation method for oil, natural gas, gas, and chemical and chemical industries. An important means of products, etc. In addition, the urban water supply network and gas supply also use metal pipelines.

Since metal transmission pipelines are mostly buried underground or on the seabed, pipeline corrosion is the main factor affecting the service life of metal pipelines. Therefore, preventing and reducing metal pipeline corrosion is a subject that must be fully considered in pipeline engineering and pipeline use.

At present, anti-corrosion measures for metal pipelines mostly take place before use, such as coating anti-rust paint on the surface of metal pipelines, but once they are put into use, there are almost no measures available for the inner layer of metal pipelines. The purpose of this invention is to fill up such a technical gap, so that even during the use of metal pipelines, certain measures can be taken to prevent corrosion of the inner walls of the pipelines based on electrochemical principles.

Contents of the invention

According to the corrosion mechanism, pipeline corrosion can be divided into chemical corrosion and electrochemical corrosion. Among them, electrochemical corrosion refers to the electrochemical reaction between the metal surface and the ion-conducting medium to cause damage to the metal surface, which is considered to be the main factor causing pipeline damage.

During the electrochemical reaction, Fe atoms lose electrons and transfer to the medium in an ion state. This process is called anodic oxidation process; the substance in the medium (also known as depolarizer) absorbs electrons from the anode, which is called cathodic reduction. process. The above two processes are generally expressed by the following formula:

Fe-2e-→Fe ²⁺ (1)

O ₂ +2H ₂ O+4e-→4OH ^- (2)

The overall response is:

2Fe+O ₂ +2H ₂ O＝2Fe(OH) ₂ (3)

It can be seen from the above formula that the factors that are conducive to the loss of electrons by Fe atoms will promote the occurrence of Fe oxidation reaction, and then promote the progress of pipeline corrosion. Conversely, if the Fe atoms can be effectively suppressed from losing electrons, the corrosion rate of the pipeline can be reduced.

According to the principle of friction, the inner wall of the metal conveying pipe and the conveying medium can be charged with each other due to the friction between them. Since the conveying medium is insulating and continuously flowing, the positive and negative charges generated by friction can be separated from each other. The positive charge left on the wall of the pipeline reacts with water and oxygen in the conveying medium or the environment through formula (2), thereby causing the pipeline to rust; the negative charge entering the conveying medium flows with the medium and exists in the medium.

According to the distribution characteristics of the charges generated by the pipeline friction and the positive and negative charges described in the above principle, the present invention arranges a charge trap in the pipeline and uses a conductive material to connect it with the inner wall of the metal pipeline to make the current in the flow medium The negative charges of the Fe atoms flow back to the inner wall of the pipe and neutralize the positive charges remaining on the pipe wall, thereby effectively inhibiting the Fe atoms from losing electrons and reducing the corrosion rate of the pipe.

A method for inhibiting corrosion of a metal delivery pipeline according to the present invention comprises providing a charge trap within the pipeline, wherein,

A: The material for making the charge trap can choose a conductive material with a higher electron loss ability than the metal transport pipe, and can include metal materials or non-metal materials, such as steel, aluminum, copper, molybdenum, tungsten, platinum or carbon. It can also be used in combination with a variety of materials mentioned above;

B: The shape of the charge trap can be one or more combinations of rod, ring, mesh and irregular shapes. In order to make the life of the charge trap consistent with the pipe and ensure the passage of fluid in the pipe, the charge trap The maximum cross-sectional area of the device can be 30%-90% of the cross-sectional area of the pipeline wall, or 3%-10% of the passing area of the pipeline;

C: The charge trap can be installed directly facing the flow direction of the medium, with the largest contact area with the flowing medium, and arranged at least at the inlet, middle and outlet of the metal conveying pipeline. At least one or more of the charge traps are connected to the inner wall of the pipeline, that is, they can be fixed on the inner wall of the pipeline by metal.

Effect of the present invention is as follows:

(1) The effect of reducing the corrosion rate of the metal delivery pipeline is remarkable: by setting a charge trap in the metal delivery pipeline and connecting it with the inner wall of the pipeline, the Fe atoms are effectively suppressed from losing electrons, thereby reducing the corrosion rate of the pipeline and improving the service life of the pipeline by 60 %above;

(2) The method of inhibiting the corrosion of metal pipelines is simple and convenient: just install a charge trap in the pipeline and connect it to the inner wall of the pipeline, and the speed of the electrochemical reaction of the pipeline can be suppressed without an external power supply. Therefore, corrosion of the pipeline can be inhibited The method is simple and convenient, and there is no additional cost;

(3) The life of the electronic capture device is the same as that of the steel pipe. It only needs to be installed when the pipeline is paved, and no later maintenance is required.

Description of drawings

Other aspects and advantages of the present invention will be more apparent from the following description of specific embodiments in conjunction with the following drawings, in which,

FIG. 1 is a schematic diagram showing a mesh charge trap and its installation location according to an exemplary embodiment of the present invention.

Detailed ways

Taking oil pipeline steel X60 as the implementation object, the implementation process is shown in Figure 1, wherein reference numeral 1 is a charge trap, and reference numeral 2 is the pipe wall of the metal delivery pipeline.

The inner diameter and outer diameter of the metal delivery pipeline are Φ90mm and Φ100mm respectively, and are connected with the oil storage tank and the circulation pump. Among them, the length of the part used to investigate corrosion is 1000 mm, and it is buried at a depth of 500 mm underground. According to the embodiment of the present invention, there are five net-like charge traps 1 made of zinc alloy wires in the metal delivery pipeline, which are connected to the pipe wall 2 . The mesh aperture of the charge trap is 50 mesh (300 μm).

Put 200kg of crude oil into the oil storage tank, keep the temperature around the pipeline at 25°C and the humidity at 90%, and use the circulation pump to continuously flow the crude oil in the pipeline at a flow rate of 0.8l/s for 4800 hours. Then take out the pipeline from the ground, clean it and cut it off from the middle, and measure the corrosion depth of the inner and outer walls of the pipeline.

The results show that when the charge trap is installed inside the pipeline, the internal and external corrosion depths of the pipeline are 0.032mm and 0.061mm, respectively, while without the charge trap, the internal and external corrosion depths of the pipeline are 0.079mm and 0.152mm, respectively.

It can be seen that the use of the charge trap and its setting method of the present invention can reduce the pipeline corrosion depth by about 60%, and the pipeline corrosion inhibition effect is remarkable.

Claims (3)

1. the method suppressing metal delivery tubes road to corrode, is characterized in that, described method is included in inside, metal delivery tubes road and arranges charge-trapping device, wherein:

A: charge-trapping device is made up of higher than the metal in metal delivery tubes road and/or nonmetallic material betatopic ability;

B: charge-trapping device be bar-shaped, ring-type, netted or irregularly shaped in one or more combinations;

C: charge-trapping device is arranged in the face of media flow direction, and there is the Maximum Contact area contacted with flowing medium, wherein, charge-trapping device is at least arranged in the entrance of pipeline, middle part and outlet port, and charge-trapping utensil has the part be directly or indirectly connected with inner-walls of duct face.

2. method according to claim 1, is characterized in that, the maximum cross-section area of charge-trapping device is the long-pending 30%-90% of the wall cross-section in metal delivery tubes road, or is the 3%-10% of pipeline by area.

3. method according to claim 1, is characterized in that, charge-trapping device is fixed on inner-walls of duct by metal.