DE1278198B - Anti-corrosive agents - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

£ 33k

GERMAN Mj9wl PATENT OFFICE Int. α .:

C23f

EDITORIAL

German class: 48 dl -11/10

Number:
File number:
Registration date:
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P 12 78 198.5-45 (B 68367)

August 9, 1962

19th September 1968

With the rapidly increasing demand for mineral oils, crude oils are being extracted to an ever greater extent and used, which increasingly contain impurities, especially sulfur compounds and salt water. Although the salt water is largely separated off before refining, the crude oil still contains it in finely divided form small amounts of salts, especially sodium chloride and magnesium chloride. During the further processing of dbs crude oil, these salts also get into the refining plants, e.g. B. preheating coils, Heat exchangers and distillation columns. In doing so, the salts are overheated Water vapor hydrolyzes, and small amounts of magnesium chloride in particular are constantly being formed of hydrochloric acid, which soon causes considerable signs of corrosion at high throughputs. Operational disruptions and production losses due to extensive repairs are inevitable. Also the Sulfur compounds and other impurities in the crude oil play their part in corrosion. In so Pipelines carrying large quantities of crude oil or crude oil products over land are heavily used Corrosion from small amounts of water, which get dissolved hydrogen sulfide or air, too calculate. In these cases, attempts have hitherto been made to add sodium nitrite in dissolved form to achieve a certain level of corrosion protection. However, this has only been successful in a few cases and only imperfectly.

The subject of patent application B 43543 VI / 48 a ¹ (German Auslegeschrift 1172 925) is the use of fatty amines, fatty acid polyamides and / or fatty acid salts of fatty acid polyamides (component I) together with oil-soluble acetylene derivatives (component II) as protection against corrosion of metal surfaces.

It has now been found that particularly good protection against corrosion of metal surfaces is achieved if the ^{substances mentioned in patent application 13 43543VIMSd 1} (German Auslegeschrift 1172 925) are used together with alkali or ammonium nitrite in aqueous solution.

It was already known that when composing economy pickles by mixing Inhibitors can in some cases achieve an increase in the inhibitory effect, but leaves this Observation does not yet predict how in particular inhibitor mixtures for special applications must be composed. Finding the optimal composition is often Corrosion protection agent due to a different effect of the mixtures

Addition to registration: B 43543 VI b / 48 dl
Interpretation document 1172 925

Applicant:

Aniline & Soda Factory in Baden

Aktiengesellschaft, 6700 Ludwigshafen

Named as inventor:

Dr.-Ing. Günther Nottes,

6703 Limburgerhof;

Dr. Gert Liebold, 6800 Mannheim

difficult when protecting materials with different compositions. So sodium nitrite cannot go together can be used with the well-known economy pickles, as this decomposes due to the acid it contains will.

The inventive combination of the substances mentioned in the main patent application with alkali or ammonium nitrite as a corrosion protection agent is surprisingly achieved an effect that far beyond the cumulative effect of the corrosion protection of oil lines and containers with exposed metal surfaces goes through the individual components. A whole range of other known anti-corrosive or passivating agents, inorganic Origin does not show this effect.

Sodium, potassium and ammonium nitrite, preferably sodium nitrite, are expediently used. Optionally, you can also use alkaline substances such. B. sodium or potassium hydroxide or ammonia, until a neutral reaction is established in the aqueous phase accompanying the hydrocarbons. The organic and inorganic components of the additive can be used together or separately the hydrocarbon mixtures, e.g. B. crude oils or their processing products are added.

The advantage of the anti-corrosion agents according to the invention and their considerably improved effect lies in the possibility of using reduced amounts of the compounds mentioned. Through this is in addition to the improved corrosion protection

809 617/557

also the further processing of hydrocarbons or hydrocarbon mixtures, e.g. B. crude oils or their processing products, facilitated.

As fatty amides, fatty acid polyamides and, preferably, fatty acid salts of fatty acid polyamides according to the invention in addition to the alkali or ammonium nitrites, together with oil-soluble acetylene derivatives Liquids to inhibit rust formation can all be added in the main patent application Use individually listed compounds or mixtures. The same applies to the used oil-soluble acetylene derivatives. These compounds or mixtures can be used directly or dissolved in a suitable solvent the liquids, e.g. B. add to the crude oil. Suitable solvents are substances in which the compounds or mixtures mentioned are readily soluble and those with the Hydrocarbons to which these compounds or mixtures are to be added, in any ratio are miscible. For example, alcohols, cyclic alcohols, ketones, cyclic ketones such as cyclohexanol and cyclohexanone. It is advisable to use distillation residues from production these substances. Particularly suitable is z. B. a distillation residue from the production of cyclohexanol, consisting of a mixture of condensation products of cyclohexanol, cyclohexanone and / or Cyclohexylamine. In general, from 0.0001 to 0.1 percent by weight of the above substances together with about 0.00005 to 0.01, that is 10 to 10,000 or 5 to 1000 ppm, the corrosion-free added to liquids to be conveyed or stored.

example 1

According to ASTM test D 665-54, 30 ml of distilled water are added to 300 ml of a German gas oil and the mixture was stirred vigorously. The temperature in the thermostat is 60 ° C. In the so-called blind test, i. H. without any additives, the beginning of rust formation is determined after just 1 hour. After 3 hours it is

ίο initially bare iron rod with a thick layer of rust completely covered. In several parallel tests, the diesel oil is then added with various Treated additives. The additive A consists of fatty acid salts of fatty acid polyamides with oil-soluble ones Acetylene derivatives and has the following composition:

Addition A

40 percent by weight of sperm oil fatty acid,
40 percent by weight of sperm oil fatty acid diethylene

triamid and

20 percent by weight ethynylcyclohexanol
(technically pure).

This mixture is in a solvent from distillation residues of the cyclohexanol production solved in a ratio of 1: 1. Of the addition A, those are given in the table below Quantities dissolved in the gas oil used before the start of the experiment. The addition of sodium nitrite in the also The amounts shown in Table 1 are carried out before the start of the experiment on the aqueous phase.

Blind test Table 1
Rust formation according to ASTM D 665-54 at 60 ° C Addition A
18 mg NaNO ₂
lmg NaO ₂
2 mg 8 mg additive A
+ 1 mg NaNO ₂ hours strong
strong Addition A
8 mg middle
very clearly strong
strong moderate
very clearly free
free 3
24 moderate
strong

As can be seen from Table 1 and FIG. 1, in which the results of the tests from Table 1 are shown in the form of a diagram, the effect of the mixture of 8 mg of additive A + 1 mg of NaNO ₂ by far exceeds that Effect that would be expected after using the same weight of the individual components. Thus, by using comparable amounts, it is possible to achieve longer-lasting corrosion protection than with the known agents, or to achieve corrosion protection that has the same length with a correspondingly reduced addition of the corrosion protection agents according to the invention.

Example 2

The experiments according to Example 1 are repeated. Instead of distilled water, it becomes salty and more corrosive seawater with a salt content of 3% in an amount of 30 ml 300 ml of gas oils of the same composition as in Example 1 are given. Addition A is in the same Composition, but used in higher concentration. In the following table 2 this is Result of the test attempts when adding different amounts of additive A and / or sodium nitrite reproduced.

Table 2 30 mg NaNO ₂ 45 mg additive A
+ 30 mg NaNO ₂ Blind test 45 mg additive A 80 Vo of the surface of the test
stripes covered with rust no rust 100% of the test surface
covered with rust 90Vo the surface of the
Test stick covered with rust

24 hours run time of the test according to 24 hours test duration as a percentage of the total ASTM D 665-54 at 60 ° C. 65 surface indicated. The base of the areas on the

FIG. 2 shows the results of Table 2 in the form of a scheme. The ordinate is with The rust-covered surface of the Fe rod along the abscissa is intended to illustrate the approximate amount of anti-corrosion agent.

Example 3

^{In a crude oil pipeline that carried 8000m s} / day of crude oil from the Middle East over a distance of 100 km, severe corrosion occurred again and again. After 1 year, about 17 kg of rust and sulfur iron had to be removed from the filter devices, which were connected to a pumping station, although 8 liters of a 40% NaNO ₂ solution were continuously injected into the line per hour together with the oil.

In the same line there was a mixture of

35% stearic acid,

35% stearic acid dipropylenetriamide and

30% ethynylcyclohexanol (technically pure)

given in an amount of 0.001 percent by weight, based on the promotion. The corrosion will though pushed back, but still causes a loss of 12.7 kg of rust and sulfuric iron per year, which must be removed on the same filter.

If, however, 0.0006 percent by weight of the mixture given above and 4 l / h of a 40% NaNO ₂ solution are added to the oil produced, only 0.8 kg of rust and iron sulfide are produced in front of the same filter per year.

Claims (1)

Claim: Use of fatty amines, fatty acid polyamides and / or fatty acid salts of fatty acid polyamides together with oil-soluble acetylene derivatives for protection against corrosion of metal surfaces according to patent application B 43543 VIb / 48 di (German interpretation 1172925), characterized by the addition of alkali or ammonium nitrite in aqueous solution. Considered publications:
W. Machu, “Surface Pretreatment Ferrous and non-ferrous metals ", 1957, p. 294;
Journal »Materials and Corrosion«, 1955, P. 3/4; "Archives for the iron and steel industry", 1959, p. 158. 1 sheet of drawings 809 617/557 9.68 © Bundesdruckerei Berlin