CN102260873B - Method for enhancing use effect of high-temperature corrosion inhibitor of oil-refining device - Google Patents

Abstract

The invention relates to a method for improving the use effect of a high-temperature corrosion inhibitor in an oil refining unit. The alkali metal salt of naphthenic acid is added to the material flow of the oil refining unit, and the alkali metal salt of naphthenic acid and the high-temperature corrosion inhibitor are combined with the oil refining unit. contact with the corroded parts. In the invention, adding the alkali metal salt of naphthenic acid is more conducive to the corrosion inhibitor forming a complete and dense protective film on the metal surface, thereby improving the use effect of the corrosion inhibitor.

Description

A method of improving the effect of high temperature corrosion inhibitor in oil refinery

technical field

The invention relates to a method for improving the use effect of a high-temperature corrosion inhibitor in an oil refinery.

Background technique

In recent years, the global production of heavy and low-quality crude oil has increased rapidly, accounting for an increasing proportion of global crude oil year by year. However, due to the limitation of refinery process conditions, the demand growth is slow, so the price and quality are gradually widening. Therefore, processing high-acid crude oil under high oil prices Crude oil has a certain cost advantage, but when processing acidic or high-acid crude oil, one of the most difficult problems to solve is the corrosion of naphthenic acid on processing equipment, and the corrosion problem directly affects the safe operation of production.

Naphthenic acid corrosion mainly occurs in the atmospheric and vacuum distillation towers of the refinery, and the easily corroded parts include the atmospheric and vacuum distillation towers, packing, feed section, side line and bottom transfer line. At present, the methods to solve naphthenic acid corrosion can be divided into three types: (1) Oil refining equipment and devices are replaced with corrosion-resistant materials, and materials are upgraded. (2) Control the processing flow rate and flow state, and optimize the structure of the refining equipment. (3) Improve the refining process, such as crude oil mixing, crude oil deacidification, adding corrosion inhibitors to corrosive parts, etc. At present, crude oil blending is the most widely used method for refining high-acid crude oil in China, that is, to mix acid-containing or high-acid crude oil with low-acid crude oil, so that the acid value of the mixed crude oil is lower than the critical value of 0.5mgKOH for naphthenic acid corrosion. /g or less. In addition, adding corrosion inhibitors is the simplest and most feasible solution to high-temperature corrosion in the processing of high-acid crude oil. All refineries that process acid-containing crude oil basically add corrosion inhibitors so that they can handle high-acid crude oil. Value of crude oil, but also can directly protect the corrosion parts.

Corrosion inhibitors used to inhibit naphthenic acid corrosion are also called high-temperature corrosion inhibitors. They are compounds containing S, P, N, O and other groups. These compounds combine with metals to form a layer by physical adsorption or chemical reaction. The dense protective film isolates the corrosive medium from the metal, thereby inhibiting the occurrence of corrosion. However, during the use of high-temperature corrosion inhibitors, it was found that due to the presence of corrosion products on the metal surface, it was difficult for the corrosion inhibitor to contact the metal surface or the protective film formed on the metal surface was not dense enough, resulting in the use of corrosion inhibitors. decrease or even fail.

Contents of the invention

The invention provides a method for improving the use effect of a high-temperature corrosion inhibitor in an oil refinery, and the method can enhance the use effect of the high-temperature corrosion inhibitor, thereby more effectively inhibiting the corrosion of the oil refinery by naphthenic acid.

A method for improving the use effect of high-temperature corrosion inhibitors in oil refining units, adding alkali metal salts of naphthenic acid into the material flow of oil refining units, so that the alkali metal salts of naphthenic acid and high-temperature corrosion inhibitors can be used with the corrosion parts of oil refining units touch.

The present invention has no special limitation on the addition position of the alkali metal salt of naphthenic acid, and the alkali metal salt of naphthenic acid can be added in advance in the feed of the oil refinery, or it can be placed in the corrosive part of the oil refinery or the corrosion part of the oil refinery The alkali metal salt of naphthenic acid is added at the previous position; it can be added to the material flow of the refinery unit after being mixed with the high-temperature corrosion inhibitor, or can be added to the material flow of the refinery unit separately with the high-temperature corrosion inhibitor; it can be used The initial addition of high-temperature corrosion inhibitors can also be added during the stable period of using high-temperature corrosion inhibitors; it can be added to the refinery unit from one position, or from multiple positions, as long as it can meet the requirements of the alkali metal of naphthenic acid Salt and high-temperature corrosion inhibitors can be in contact with the corrosion parts of the refinery unit for a period of time.

Preferably, the alkali metal salt of naphthenic acid is dissolved in a solvent before being added to the refinery unit stream. The role of the solvent is to dissolve the alkali metal salt of naphthenic acid, which is convenient to add to the oil refining unit. Those skilled in the art can choose the type and amount of the solvent according to the teaching of the present invention and in combination with the basic common sense in the field.

In another preferred situation, the alkali metal salt of naphthenic acid is mixed with the high-temperature corrosion inhibitor, and then added to the material stream of the oil plant.

Based on each gram of material in the refinery unit stream, the amount of the alkali metal salt of naphthenic acid added is preferably 10 μg to 10000 μg, more preferably 50 μg to 5000 μg.

The addition time of the alkali metal salt of naphthenic acid is preferably 0.5h to 48h, more preferably 1h to 12h.

The method for preparing alkali metal naphthenic acid from naphthenic acid belongs to the prior art, and will not be repeated in the present invention. As basic knowledge in the art, naphthenic acid is mainly derived from petroleum, and the naphthenic acid separated from petroleum products is a mixture. The present invention preferably adopts the alkali metal naphthenic acid prepared by mixing naphthenic acid, but The invention also does not exclude alkali metal naphthenates prepared from a single naphthenic acid either purified or obtained by organic synthesis. In the present invention, there is no special limitation on the carbon number of the naphthenic acid, as long as it can be dissolved in the added material stream.

The present invention has no particular limitation on the corrosion inhibitor.

Those skilled in the art are familiar with how to use corrosion inhibitors. Generally, based on each gram of material in the material flow, the dosage of the high temperature corrosion inhibitor is 5-200 μg, preferably 10-100 μg; the temperature range is 150-600°C, preferably 210-350°C. In the early stage of use, the dosage of high temperature corrosion inhibitor is higher; in the stable period, the dosage of high temperature corrosion inhibitor is lower.

Through the research on the corrosion effect of naphthenic acid on the corrosion of naphthenic acid, it is found that the alkali metal salt of naphthenic acid is a corrosion product cleaning agent, which has the effect of peeling off the corrosion products on the metal surface. By adding the alkali metal salt of naphthenic acid It is more conducive to the corrosion inhibitor to form a complete and dense protective film on the metal surface, thereby improving the use effect of the corrosion inhibitor. By adopting the method of the invention, no additional purchase of equipment is required, and the cleaning of the metal surface and the film formation of the corrosion inhibitor can be completed simultaneously.

Detailed ways

Example 1:

The corrosion test was carried out in a 500mL autoclave.

Test piece material: 20# carbon steel. Test temperature: 270～280℃.

Corrosion medium: acid-containing crude oil with TAN=3.47mgOH/g, corrosion inhibitor (dimethyl phosphite) added in an amount of 100 μg/g, sodium naphthenate (made from naphthenic acid with a weight average molecular weight of 300, naphthenic acid Carbon number 16~30) The addition amount is 1000μg/g, and the cleaning time is 2h. The test results show that a uniform protective film is formed on the surface of the test piece added with sodium naphthenate, and the corrosion rate is 0.01mm/a.

Using the same test conditions, except that sodium naphthenate was not added, a comparative test was carried out. The test results show that the protective film formed on the surface of the test piece without sodium naphthenate is uneven, and the corrosion rate is 0.17mm/a,

Example 2:

The corrosion test was carried out in a 500mL autoclave.

Test piece material: 20# carbon steel. Test temperature: 300～310℃.

Corrosion medium: acid-containing distillate oil with TAN=1.68mgOH/g, the boiling range of the distillate oil is 350℃～420℃, the addition amount of corrosion inhibitor (dimethyl phosphite) is 50μg/g, potassium naphthenate (by weight average molecular weight 300 naphthenic acid is prepared, the carbon number of naphthenic acid is 16-30), the addition amount is 300μg/g, and the cleaning time is 1h. The test results show that a uniform protective film is formed on the surface of the test piece added with potassium naphthenate, and the corrosion rate is 0.1mm/a.

Using the same test conditions, except that potassium naphthenate was not added, a comparative test was carried out. The test results show that no protective film is formed on the surface of the test piece without adding potassium naphthenate, and the corrosion rate is 1.2mm/a.

Claims (9)

1. a method that improves the high temperature inhibitor for oil refining apparatus result of use, is characterized in that, an alkali metal salt of naphthenic acid is joined in the streams of oil refining apparatus, and an alkali metal salt of naphthenic acid is contacted with the corrosion location of oil refining apparatus with high-temperature corrosion inhibitor.

2. according to the method for claim 1, it is characterized in that, the every gram material in the oil refining apparatus streams is as benchmark, and an alkali metal salt add-on of naphthenic acid is 10 μ g～10000 μ g.

3. according to the method for claim 2, it is characterized in that, the every gram material in the oil refining apparatus streams is as benchmark, and an alkali metal salt add-on of naphthenic acid is 50 μ g～5000 μ g.

4. according to the method for claim 1, it is characterized in that, the joining day of an alkali metal salt of naphthenic acid is 0.5h～48h.

5. according to the method for claim 4, it is characterized in that, the joining day of an alkali metal salt of naphthenic acid is 1.0h～12h.

6. according to the method for claim 1, it is characterized in that, when an alkali metal salt of naphthenic acid contacted with the corrosion location of oil refining apparatus with high-temperature corrosion inhibitor, temperature was 150～600 ℃.

7. according to the method for claim 6, it is characterized in that, when an alkali metal salt of naphthenic acid contacted with the corrosion location of oil refining apparatus with high-temperature corrosion inhibitor, temperature was 210～350 ℃.

8. according to the method for claim 1, it is characterized in that, after an alkali metal salt of naphthenic acid is dissolved in solvent, then join in the streams of oil refining apparatus.

9. according to the method for claim 1, it is characterized in that, an alkali metal salt of naphthenic acid with after high-temperature corrosion inhibitor mixes, is joined in the streams of oil refining apparatus.