RU2499031C2 - Method of hydrogen sulphide removal from green oil - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to composition absorbing hydrogen sulphide to be added to green oil. This composition eliminates hydrogen sulphides to be migrated into water phase to be removed from green oil and comprises glyoxal and catalyst. Note here that said catalyst comprises ammonium quaternary salt of formula I: R₁R₂R₃R₄N⁺X^- (I), where every of R₁, R₂, R₃ and R₄ independently represents alkyl group including 1 to 30 carbon atoms, aryl group including 6 to 30 carbon atoms or aryl alkyl group including 7 to 30 carbon atoms, while X represents halide, sulphate, nitrate or carboxylate.

EFFECT: efficient removal.

18 cl, 4 tbl, 3 ex

Description

Technical field

In General, the present invention relates to methods for removing hydrogen sulfide, and, in particular, to methods for removing hydrogen sulfide from crude oil.

State of the art

Crude oil may contain hydrogen sulfide, which in the presence of water has a strong corrosive effect and is toxic in very small concentrations. Possible leakage of hydrogen sulfide can adversely affect the health and safety of personnel when working with crude oil, that is, during storage, transportation (transportation, transportation by cars or during transportation in pipelines) and processing of crude oil.

To remove hydrogen sulfide from crude oil, hydrogen sulfide scavengers are used. Typical hydrogen sulfide scavengers are triazines and aldehydes. However, triazines release amines into liquid hydrocarbon media, and residual triazines are thermally decomposed, releasing an additional amount of amines into liquid hydrocarbon media, which also poses a health hazard to personnel. Free amines can form salts that precipitate on process equipment, causing corrosion. Aldehyde reactions can have slow kinetics and can lead to incomplete removal of hydrogen sulfide.

An improved absorber must be developed to remove hydrogen sulfide from crude oil.

Description of the invention

In one embodiment, a method of reducing the amount of hydrogen sulfide present in crude oil comprises adding to the crude oil a hydrogen sulfide-absorbing composition to capture hydrogen sulfide, allowing migration of the captured sulfides to the aqueous phase, and removing the aqueous phase from the crude oil, wherein the hydrogen sulfide-absorbing composition comprises glyoxal and a quaternary salt ammonium

Various embodiments relate to an improved process for the removal of hydrogen sulfide from crude oil, which provides for the rapid capture of hydrogen sulfide and does not lead to the production of amines as by-products.

DETAILED DESCRIPTION OF THE INVENTION

The singular forms include the plural, unless the context indicates otherwise. The boundaries of all ranges related to the same characteristics can be independently combined and included in the given boundary value. All cited documents are incorporated herein by reference.

Clarification of “approximately” regarding the quantity includes the indicated value and has a meaning that is obvious from the context (for example, includes the error limits associated with measuring a specific quantity).

The terms “possible” or “possible” mean that the event or action described below may or may not occur, or that the material defined hereinafter may or may not be present, and that the description includes examples in which the event or circumstance occurs or the material is present, as well as examples in which an event or circumstance does not occur or material is missing.

In one embodiment, a method of reducing the amount of hydrogen sulfide present in crude oil comprises adding to the crude oil a hydrogen sulfide-absorbing composition to capture hydrogen sulfide, allowing migration of the captured sulfides to the aqueous phase, and removing the aqueous phase from the crude oil, wherein the hydrogen sulfide-absorbing composition comprises glyoxal and a quaternary salt ammonium

Crude oil may be any type of crude oil containing hydrogen sulfide. Any amount of hydrogen sulfide in crude oil can be reduced, and the actual amount of remaining hydrogen sulfide can be different and depend on the initial amount. In one embodiment, the concentration of hydrogen sulfide, measured in the vapor phase, is reduced to 150 mass. parts per million or less, based on the mass of crude oil. In another embodiment, the concentration of hydrogen sulfide, measured in the vapor phase, is reduced to 100 mass. parts per million or less, based on the mass of crude oil. In another embodiment, the concentration of hydrogen sulfide, measured in the vapor phase, is reduced to 50 mass. parts per million or less, based on the mass of crude oil. In another embodiment, the concentration of hydrogen sulfide, measured in the vapor phase, is reduced to 20 mass. parts per million or less, based on the mass of crude oil.

A hydrogen sulfide-absorbing composition is added to the crude oil in any conventional manner. In one embodiment, the absorbent composition is introduced into the crude oil using a conventional direct injection system, and the composition can be introduced into the processing line at any location suitable for mixing the scavenger with the crude oil, for example, into a pipeline or tank. The absorbent composition can be added to the crude oil continuously or periodically, in the form of one or more portions, which can be added one or more times.

The absorbent composition is added to the crude oil in any amount sufficient to reduce the concentration of hydrogen sulfide in the crude oil. In one embodiment, the absorbent composition is added in an amount of from about 1 ppm to about 3000 mass. parts per million, based on the mass of crude oil. In another embodiment, the absorbent composition is added in an amount of from about 10 mass. parts per million to about 2000 mass. parts per million, based on the mass of crude oil. In another embodiment, the absorbent composition is added in an amount of from about 50 mass. parts per million to about 1500 mass. parts per million, based on the mass of crude oil. In another embodiment, the absorbent composition is added in an amount of from about 100 mass. parts per million to about 1200 mass. parts per million, based on the mass of crude oil.

The hydrogen sulfide scavenger can be added in pure form or diluted with water or a solvent, and it can be mixed or combined with other suitable materials or additives.

A hydrogen sulfide-absorbing composition traps and neutralizes hydrogen sulfide present in crude oil by incorporating sulfur into an inert cyclic compound. The cyclic compound is not harmful, has a high affinity for the aqueous phase and migrates to the aqueous phase from the oil phase. A hydrogen sulfide-absorbing composition comprises glyoxal and a quaternary ammonium compound. Glyoxal is a water soluble aldehyde and may include glyoxal oligomers. Glyoxal is available in industry. Glyoxal is catalyzed by a quaternary ammonium salt, which increases the efficiency of the absorbent composition and improves the extraction of hydrogen sulfide. The catalyst may be any suitable quaternary ammonium salt. In one embodiment, the catalyst has the formula I:

where each of R ₁ , R ₂ , R ₃ and R ₄ independently represents an alkyl group containing from 1 to 30 carbon atoms, an aryl group containing from 6 to 30 carbon atoms, or an arylalkyl group containing from 7 to 30 carbon atoms and X represents a halide, sulfate, nitrate or carboxylate. Alkyl groups and aryl groups can be either substituted or unsubstituted.

In one embodiment, R ₁ represents an alkyl group containing from 1 to 24 carbon atoms. In one embodiment, R ₂ is alkyl containing from 1 to 24 carbon atoms, an aryl group containing from 6 to 24 carbon atoms, or an arylalkyl group containing from 7 to 24 carbon atoms.

In one embodiment, each of R ₃ and R ₄ independently represents an alkyl group containing from 1 to 24 carbon atoms. In another embodiment, each of R ₃ and R ₄ independently represents an alkyl group containing from 1 to 4 carbon atoms.

Non-limiting examples of an alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, decyl or dodecyl. The aryl group may be phenyl. The arylalkyl group may be benzyl. The halide may be chloride, bromide or iodide. The sulfate may be methyl sulfate. The nitrate may be bisulfate nitrate. The carboxylate may be acetate.

In one embodiment, the quaternary ammonium salt is alkylbenzylammonium chloride or benzyl cocoalkyl (C ₁₂ -C ₁₈ ) dimethyl ammonium chloride. In another embodiment, non-limiting examples of the quaternary ammonium salt include dicocoalkyl (C ₁₂ -C ₁₈ ) dimethylammonium chloride, dithallodimethylammonium chloride, di (hydrogenated tall alkyl dimethyl-quaternary ammonium, methyl bis- (2-hydroxyethylcocoalkyl chloride (C ₁₂ -C ₁₈ - quaternary ammonium, dimethyl (2-ethyl) thalloammonium methyl sulfate, n-dodecylbenzyldimethylammonium chloride, n-octadecylbenzyldimethylammonium chloride, n-dodecyl trimethylammonium sulfate, alkyl trimethylammonium chloride or methylated sulfate ) (2-ethylhexyl) dimethyl quaternary ammonium.

In one embodiment, the amount of quaternary ammonium salt present is from about 0.01 to about 15 wt% based on the amount of glyoxal. In another embodiment, the amount of quaternary ammonium salt present is from about 1 to about 10% by weight based on the amount of glyoxal.

The absorbent composition has an affinity for the aqueous phase, and the captured sulfides migrate to the aqueous phase. If an emulsion is present, it is possible to ensure the migration of the captured sulfides to the aqueous phase from the crude oil and to remove them with the aqueous phase. If there is no emulsion, wash water can be added to attract the captured sulfides. In one embodiment, the hydrogen sulphide-absorbing composition is added prior to processing the crude oil in a desalting agent, in which the hydrocarbon media are emulsified with wash water, allowing water-soluble contaminants to be removed and then the aqueous phase is separated and removed from the crude oil.

In one embodiment, the wash water is added in an amount sufficient to form an emulsion with crude oil. In another embodiment, the wash water is added in an amount of from about 1 to about 50% vol., Based on the volume of the emulsion. In another embodiment, the wash water is added in an amount of from about 1 to about 25% vol., Based on the volume of the emulsion. In another embodiment, the wash water is added in an amount of from about 1 to about 10% vol., Based on the volume of the emulsion. In one embodiment, the crude oil is present in an amount of from about 50 to about 99% vol., Based on the volume of the emulsion. In another embodiment, the crude oil is present in an amount of from about 75 to about 99% vol., Based on the volume of the emulsion. In another embodiment, the crude oil is present in an amount of from about 90 to about 99% vol., Based on the volume of the emulsion.

Wash water and crude oil are emulsified in any conventional manner. In one embodiment, the wash water and crude oil are heated and thoroughly mixed to form an oil-in-water emulsion. In one embodiment, the wash water and crude oil are heated at a temperature of from about 90 ° C to about 150 ° C. Wash water and crude oil are mixed in any conventional way, for example, using a static mixer installed on the line, or using a mixing valve installed on the line, with a pressure drop of from about 0.2 to about 2-10 ⁵ Pa (2 bar) , depending on the density of crude oil. Provide the possibility of separation of the emulsion, for example, by sedimentation, into the aqueous phase and the oil phase. In one embodiment, the aqueous phase is removed. In another embodiment, the aqueous phase is removed by draining the aqueous phase.

To facilitate the separation of water from crude oil, demulsifiers can be added to the mixture. In one embodiment, non-limiting examples of demulsifiers include oxyalkylated organic compounds, anionic surfactants, nonionic surfactants, or mixtures of such materials. Non-limiting examples of oxyalkylated organic compounds include phenol-formaldehyde resin ethoxylates, alkoxylated polyols and amines, for example, Pluronic® block copolymers. Anionic surfactants include alkyl or aryl sulfonates, for example, dodecylbenzenesulfonate. These demulsifiers can be added to water in an amount of from about 1 to about 1000 masses. parts per million, based on the mass of crude oil. Combinations of additives may be used, but the total amount of additives to be administered should be from about 1 to about 1000 masses. parts per million, based on the mass of crude oil.

For a better understanding of the present invention by those skilled in the art, the following are non-limiting examples which serve to illustrate the present invention.

Examples

Example 1

Tests for the removal of hydrogen sulfide were carried out on crude oil containing 500 ppm of hydrogen sulfide in the liquid phase and obtained from a refinery in Texas (Texas, Valero). Tests were performed using a modified ASTM 5705-95 test in which H ₂ S was determined in the vapor phase using a dragger tube for two hours after treatment (60 ° C (140 ° F)). The results are shown in table 1.

Table 1 Sample H ₂ S absorber (1000 ppm) Residual H ₂ S (ppm) CE-1 IEA ¹ triazine 400 CE-2 Triazine 8411C ² 120 CE-3 MMA ³ triazine + Catalyst ⁴ 200 CE-4 MEA ¹ triazine + Catalyst ⁴ 200 CE-5 Glyoxal 950 one Glyoxal + Catalyst ⁴ 140 ¹ MEA - monoethanolamine
² Triazine 8411C is supplied by Clearwater, Inc. as Sulfa-Clear8411C product.
³ MMA - monomethylamine
⁴ The catalyst is cocoalkyldimethylbenzylammonium chloride (Arquad® DMCB-80) in a concentration for processing of 1.6% by weight (active substances) based on the weight of triazine or glyoxal.

Sample 1 showed comparable results with the use of triazine, but the catalyzed glyoxal can be removed with the aqueous phase, while the triazine remains in the oil and can form amines during further processing. Purification with a glyoxal catalyzed sample showed much better results than glyoxal treatment, while the catalytic effect on triazine did not improve triazine treatment results.

Example 2

The concentration of hydrogen sulfide in the vapor phase was determined at various dosages of the processing substances after 1 hour and 2 hours for sample 1 and comparative examples CE-I and CE-3, as shown in table 2.

table 2 Dosage (hours / mill.) CE-1 level H ₂ S (hours / mill.) 1 hour CE-3 level H ₂ S (hours / mill.) 1 hour Sample 1 level H ₂ S (h / mils) 1 hour CE-1 level H ₂ S (hours / mill.) 2 hours CE-3 level H ₂ S (hours / mill.) 2 hours Sample 1 level H ₂ S (h / mils) 2 hours 0 500 500 500 500 500 500 500 160 one hundred 60 120 80 twenty 1000 twenty twenty twenty 5 5 5 h / mils - parts per million

Adding samples reduces and regulates the level of hydrogen sulfide. Sample 1 showed results comparable to those obtained using CE-I and CE-3. However, sample 1 can be removed with the aqueous phase and does not form amines, like samples containing triazine.

Example 3

5 g of H ₂ S was bubbled through a 2 L flask containing 1 L of a commercially available crude oil sample initially containing <25 μg / ml hydrogen sulfide. The flask was equipped with a mechanical stirrer and reflux condenser with an alkaline trap. The crude oil was stirred at room temperature for 1 hour. The concentration of H ₂ S in the crude oil containing H ₂ S was 3940 μg / ml.

A demulsifier was added to the crude oil containing H ₂ S in the amounts shown in Table 3.

5% vol. Was mixed with glyoxal and cocoalkyldimethylbenzylammonium chloride. washing water, as indicated in table 3, and was added to the crude oil containing H ₂ S. The washing water was mixed with crude oil containing H ₂ S, at 4000 rpm. for 2 seconds using gratings and heated to 130 ° C under a pressure of 2.76 · 10 ⁴ PA (4 psi), obtaining an emulsion.

The emulsion was left for 32 minutes to separate the aqueous phase and crude oil. To determine the degree of separation of the emulsion, a drop of water was determined, which is presented in table 4. The aqueous phase was separated from the emulsion and its transparency was analyzed; the results are shown in table 3.

Table 3 Sample Demulsifier ¹ (ppm) ² Processing ³ (parts per million) ² The average drop of water (ml) Water drop transparency Single 0 0 2.73 Transparent CE-8 6 0 4,50 Transparent 2 6 one hundred 4,50 Slightly cloudy 3 12 one hundred 4.48 Slightly cloudy four 6 250 4.75 Muddy 5 12 250 4.70 Muddy 6 6 500 4.75 Muddy 7 12 500 4.75 Muddy ^{1 The} demulsifier is an alkoxylated alkyl phenol formaldehyde available from the General Electric Company.
² Dosage in terms of 100 ml of the total volume.
³ Processing was carried out by adding 1.6% of the mass. glyoxal and cocoalkyldimethylbenzylammonium chloride (active substances), based on the mass of glyoxal.

Table 4 Determination of a drop of water in ml Sample 1 min (ml) 2 min (ml) 4 min (ml) 8 min (ml) 16 min (ml) 32 min (ml) The average drop of water (ml) Single 0.4 1.8 2.7 3,5 four four 2.73 CE-8 1.8 four 4.7 5.5 5.5 5.5 4,50 2 1.8 four 4.7 5.5 5.5 5.5 4,50

3 2 four 4.7 5.2 5.5 5.5 4.48 four 3 four 5 5.5 5.5 5.5 4.75 5 3 four 4.7 5.5 5.5 5.5 4.70 6 3 four 5 5.5 5.5 5.5 4.75 7 3 four 5 5.5 5.5 5.5 4.75

The increased turbidity of the selected water at higher concentrations of reagents that remove hydrogen sulfide, indicates the presence of hydrogen sulfide products that are removed with water. In addition, the hydrogen sulfide scavenger does not adversely affect emulsion separation.

Although typical embodiments of the invention have been shown to illustrate the invention, the description does not limit the scope of protection of the invention. Accordingly, various modifications, adaptations, and alternatives may be made to the present invention that are obvious to those skilled in the art without departing from the scope of the invention.

Claims (18)

1. A method of reducing the amount of hydrogen sulfide present in crude oil, comprising adding a hydrogen sulfide absorbing composition to the crude oil to capture hydrogen sulfide, allowing migration of the captured sulfides to the aqueous phase, and removing the aqueous phase from the crude oil, in which the hydrogen sulfide absorbing composition comprises glyoxal and a catalyst moreover, the catalyst contains a Quaternary ammonium salt having the formula I:

where each of R ₁ , R ₂ , R ₃ and R ₄ independently represents an alkyl group containing from 1 to 30 carbon atoms, an aryl group containing from 6 to 30 carbon atoms, or an arylalkyl group containing from 7 to 30 carbon atoms and X represents a halide, sulfate, nitrate or carboxylate. 2. The method according to claim 1, wherein the absorbent composition is added to the crude oil in an amount of from about 1 parts by weight per million to about 3000 parts by weight per million based on the weight of the crude oil. 3. The method according to claim 1, in which the absorbent composition is added to the crude oil in an amount of from about 10 parts by weight per million to about 2000 parts by weight per million, based on the weight of the crude oil. 4. The method according to claim 1, in which the alkyl group is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, decyl and dodecyl. 5. The method according to claim 1, in which the aryl group is phenyl. 6. The method according to claim 1, wherein the arylalkyl group is benzyl. 7. The method according to claim 1, in which the halide is selected from the group consisting of chloride, bromide and iodide. 8. The method according to claim 1, in which the catalyst is benzyl cocoalkyl (C ₁₂ -C ₁₈ ) dimethylammonium chloride. 9. The method according to claim 1, in which the catalyst is selected from the group consisting of dicocoalkyl (C ₁₂ -C ₁₈ ) dimethylammonium chloride, benzyl cocoalkyl (C ₁₂ -C ₁₈ ) dimethylammonium chloride, dithallodimethylammonium chloride, di (hydrogenated tall alkyl) dimethyl of quaternary ammonium, methyl bis (2-hydroxyethyl cocoalkyl (C ₁₂ -C ₁₈ ) quaternary ammonium chloride, dimethyl (2-ethyl) tallow ammonium methyl sulfate, n-dodecyl benzyl dimethyl ammonium chloride, n-octadecyl benzyl dimethyl methyl ammonium chloride, (2-ethylhexyl) dimethyl vertichnogo ammonium. 10. The method according to claim 1, in which the amount of quaternary ammonium salt present is from about 0.01 wt.% To about 15 wt.%, Based on the weight of glyoxal. 11. The method according to claim 10, in which the amount of quaternary ammonium salt present is from about 1 wt.% To about 10 wt.%, Based on the weight of glyoxal. 12. The method according to claim 1, in which the crude oil is processed in a desalting plant. 13. The method according to item 12, in which washing oil is added to the crude oil. 14. The method according to item 13, in which the wash water is added in an amount of from about 1 vol.% To about 50 vol.%, Based on the volume of the emulsion. 15. The method according to item 13, in which the wash water is added in an amount of from about 1 vol.% To about 25 vol.% Of the volume of the emulsion. 16. The method according to item 13, in which the wash water and crude oil are emulsified by heating and mixing the crude oil and wash water. 17. The method according to item 13, in which crude oil and wash water are heated to a temperature of from about 90 ° C to about 150 ° C. 18. The method according to item 13, in which the wash water is removed by draining.