CZ305642B6 - Corrosion-preventive method of protection of crude-oil transportation and storage equipment - Google Patents

Abstract

The invented corrosion-preventive method of protection of crude-oil transportation and storage equipment consists in adjusting the transported and stored media with metal corrosion inhibitors, which contain propargylalcohol and further in some cases, the use of electrochemical protection is recommended, too. For transportation equipment, the most suitable is the combination of propargylalcohol with dibenzylsulfoxide and/or thiourea. In places of permanent contamination with water phase plus salt, in tons, at certain delay thereof, it is suitable to apply electrochemical protection. At locations of constant contamination by water phase plus salt in tons and at certain dwell thereof, the equipment is brought by means of an industrial potentiostat in the conditions of a cathode and a sacrificed anode is then situated in the water environment.

Description

The invention relates to a method for corrosion protection of oil extraction, transport and storage equipment.

Prior art

In the transport and storage of oil, the structural elements of the equipment used, such as pumps, tanks and their components, equipment for pumping, mixing and other mechanical operations, are highly corrosive, as they are in constant contact with the oil and its saturated vapors or process gas, e.g. carbon dioxide. The cause of corrosion is then the effect of acidic components, such as carbon dioxide or sulfane, in the interaction of water, contained in emulsified form in oil and inorganic substances dissolved in it (salts with a predominant chloride content). The corrosive effects of carbon dioxide are manifested over the entire area of contact with the device, while the corrosive effects of water where it separates (lower places of the device with a slow flow rate) or condensation from the vapor phase. In addition to the two mentioned components - carbon dioxide, which is used to intensify extraction, and sulfane, which is a natural component of crude oil, oils also contain significant amounts of organic acidic substances (mercaptans, sulfides, polysulfides, etc.). This complicated environment can be corrosive to the equipment even in the absence of water.

However, each oil field contains water, which as a heavier liquid is mainly in the lower and middle part of the field. In the middle because oil contains polymeric compounds such as maltens, asphaltenes, etc., which are heavy. During extraction, water is always part of the extraction medium and is thus in constant contact with the extraction probe and other parts of the extraction set. They are particles of water of a microscopic nature up to displaced water. Due to the fact that water always carries a lot of dissolved salts (also the danger of chlorides), this mixture is corrosive on the device.

Although various materials are available with sufficient corrosion resistance to the substances described (high-alloy steels), they cannot be used for large parts of oil transport and storage equipment, mainly for economic reasons. Additional anti-corrosion measures, such as protective coatings - rubber coating, for example, have a limited service life in the oil environment.

The essence of the invention

These problems are solved by the method of corrosion protection of the oil transport and storage device according to the invention, which consists in adding metal corrosion inhibitors containing propargyl alcohol to the transported and stored media.

To protect the oil pipeline, propargyl alcohol is applied directly to the oil ready for transport in a concentration of 0.0001% by weight during the transport of the oil. up to 0.01 wt. together with an alcoholic solution of dibenzyl sulfoxide in a concentration of 0.0005% by weight. up to 0.01 wt. and / or with 0.0001 wt. thioureas.

In the case of tons of water displaced, electrochemical protection is also applied, in which the device and especially the reservoirs are a cathode and the "sacrificial" anode is resistant in the displaced water.

Preferably, the pH of the aqueous phase is adjusted to 8.5 to 9.5 with substances selected from the group consisting of ammonia, hydrazine, cyclohexylamine, amino alcohols, morpholine, piperidine.

For carbon dioxide, propargyl alcohol in combination with dibenzyl sulfoxide is suitable as protection.

- 1 CZ 305642 B6

In places of permanent contamination with the aqueous phase plus salt, in tons, with a certain retention, the device can advantageously be brought into cathode conditions by means of an industrial potentiostat and the "sacrificed" anode can be located in the aqueous environment.

Examples of embodiments of the invention

Example 1

In the case of transported oil, propargyl alcohol was applied to the inlet of the pipeline and to the stored facility in a concentration of 0.001% by weight. together with an alcoholic solution of dibenzyl sulfoxide in a concentration of 0.0005% by weight. In the case of a storage device with a large amount of displaced water, the pH was adjusted to 9 to 9.5 with amino alcohol.

Example 2

The sedimentation of the emulsified water increased to 200 tons, and therefore electrochemical protection was further applied. The cathode was a stainless steel container 18/8 + 2% by weight. Mo, - 700 mV vs. SKE, compared to anode, steel cl. 11, + 650 mV vs. SKE. The potentials were maintained by an industrial potentiometer.

Example 3

Equipment that is shut down, such as oil-flooded pumping station pumps, pipelines that are not used continuously but remain full, such as sludge tanks pumped from cleaned tanks, must also be protected from corrosion. Therefore, an alcoholic solution of 0.01 wt% was used. of propargyl alcohol and 0.001 wt. sodium salts of mercaptobenzothiazole and 0.0005 wt. 1-hydroxy ethane-1,1-diphosphonic acid.

Example 4

In the case of storage of crude oil containing more water, it was necessary to further adjust the pH to 9 using hydrazine together with 2 mg / l of mercaptobenzothiazole sodium in 1 liter of water. It would also be possible to use electrochemical protection.

Industrial use

The corrosion protection method used according to the invention has a wide range of applications in the refining and petrochemical industries.

Claims (4)

A method for the corrosion protection of oil transport and storage equipment, characterized in that metal corrosion inhibitors containing propargyl alcohol are added to the transported and stored media. The method according to claim 1, characterized in that the protection of the oil pipeline during the transport of oil is applied directly to the oil ready for transport by propargyl alcohol in a concentration of 0.0001% by weight. up to 0.01 wt. together with an alcoholic solution of dibenzyl sulfoxide in a concentration of 0.0005% by weight. up to 0.01 wt. and / or with 0.0001 wt. thioureas. The method according to claims 1 and 2, characterized in that for tonal amounts of displaced water, electrochemical protection is further applied, in which the reservoir is a cathode and the "sacrificial" anode is resistant in the displaced water. Process according to Claims 1 to 3, characterized in that the pH of the aqueous phase is adjusted to 8.5 to 9.5 with substances selected from the group consisting of ammonia, hydrazine, cyclohexylamine, amino alcohols, morpholine, piperidine.