WO2018218641A1

WO2018218641A1 - Method of mitigation of tramp amines in application of h2s scavengers

Info

Publication number: WO2018218641A1
Application number: PCT/CN2017/086953
Authority: WO
Inventors: Gregory Kaplan; Hai Chang; Hitesh Ghanshyam Bagaria; Hongchen Dong; Zhida Pan
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2017-06-02
Filing date: 2017-06-02
Publication date: 2018-12-06
Anticipated expiration: 2019-12-02

Abstract

Provided are a scavenger composition and a method for removing amines from a hydrocarbon stream. The scavenger composition includes an amine-based H ₂S scavenger compound and at least one oxymethylene compound capable of scavenging amines. The method includes (a) providing a scavenger composition to a hydrocarbon, water or multiphase stream, the hydrocarbon, water or multiphase stream containing sulfide-containing compounds therein, wherein the scavenger composition comprises an amine-based H ₂S scavenger composition or amine-aldehyde reaction products and at least one oxymethylene compound, and (b) contacting the sulfide-containing compounds with the amine-based H ₂S scavenger composition, wherein the amine-based H ₂S scavenger composition (i) scavenges the sulfide-containing compounds, and (ii) produces primary and/or secondary amines, the amines reacting with the at least one oxymethylene species in situ, to reduce the amount of primary and/or secondary amines present in the hydrocarbon stream.

Description

METHOD OF MITIGATION OF TRAMP AMINES IN APPLICATION OF H2S SCAVENGERS

FIELD OF THE INVENTION

This invention relates to methods and compositions for reacting with sulfides, and more particularly, to effectively remove sulfur impurities with amine-based H₂S scavengers and simultaneously scavenge the resulting amines in situ.

BACKGROUND OF THE INVENTION

Hydrogen sulfide is a clear toxic gas with a foul odor. It is also highly flammable. The Environmental Protection Agency and other regulatory agencies worldwide strictly control the release of hydrogen sulfide into the environment. Hydrogen sulfide is often present in well water, waste water, and other aqueous streams. Hydrogen sulfide may also be present in crude oil and natural gas reserves and must be removedbefore using.

Sulfur (in the form of sulfides, thiols and mercaptans in crudes) can lead to detrimental effects, especially equipment corrosion in the processing of crudes. Crudes with high degrees of sulfur content are classifies as sour crudes. These sour crudes command a lower price than low sulfur (sweet) crudes. One method that refiners use to remove the sulfur in sour crudes is by adding hexahydrotriazines to the crudes to scavenge sulfur compounds. Hexahydrotriazines are formed by the reaction of aldehydes (especially formaldehyde or a formaldehyde precursor) with amines.

While effective in removing sulfur compounds, this method then generates primary amines, such as monoethanol amine (MEA) , methylamine, methoxy propyl amine, etc., in the crude oil. These amines in the crude oil then represent another problem for the refiners as they contribute to corrosion and fouling in the refinery equipment. When present in crude these detrimental amines are referred to as “tramp amines” . Other sources of tramp amines in crudes include naturally occurring amines in the crude reservoirs. Tramp amines have been found causing scaling, corrosion, and other detrimental effects.

Due to increase of H₂S treatment, tramp amines in crude and refinery processes are reaching unacceptable levels, causing crude oil producing and treating companies to abandon the use of relatively inexpensive triazines in favor of more costly or less effective treatment options.

Previously, the problem of tramp amines has been recognized and strategies have been developed for removing tramp amines from crudes, for example, by adding amine scavengers separately from the triazine to remove these amines. However, what is needed is an improved scavenger to effectively remove sulfur impurities with triazines and simultaneously scavenge the resulting amines in situ.

SUMMARY OF THE INVENTION

It was surprisingly discovered that an improved scavenger effectively reduces sulfur impurities with amine-based H₂S scavengers and simultaneously scavenges the resulting amines in situ, and thus eliminating amines so that crude can continue to be effectively sweetened and the negative impact of tramp amines ameliorated.

In one embodiment, the present invention provides a scavenger composition. The scavenger composition comprises an amine-based H₂S scavenger compound and at least one oxymethylene compound. In some embodiments, the H₂S scavenger compound is an amine-aldehyde reaction product. In some embodiments, at least one oxymethylene compound includes oxymethylene oligomers.

In one embodiment, the amine-based H₂S scavenger compound is a hexahydrotriazine compound shown by the formula

wherein R is an amine selected from the group consisting of as alkanolamines, monoethanolamine, 1-amino-2-propanol, 2-amino-2-methylpropanol, 3-aminopropanol, tris (hydroxymethyl) methylamine) , methoxypropylamine, methoxyethylamine, alkylamines, methylamine, ethylamine, propylamine, butylamine, isobutylamine, ethyleneamines, ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminoproylamine, cyclic amines, cyclohexyl amine, aromatic amines, aniline and mixtures thereof.

In some embodiments, the amine-based H₂S scavenger compound is an amine-aldehyde reaction product, wherein said amine comprises linear, branched or cyclic primary and secondary amines, including alkanolamines, dialkylamines, morpholine, piperazine, aminomethyl piperazine, and aldehydes comprising formaldehyde, glyoxal or glutaraldehyde.

The present invention further provides a scavenger composition as in any of the previous embodiments, wherein the at least one oxymethylene compound is in a solution, and wherein the solution comprises (i) water, (ii) alcohols, (iii) diols, (iv) glycerol, or (v) mixtures thereof. The oxymethylene oligomers include oxymethylene, represented by the formula

wherein n>0.

In some embodiments, the oxymethylene oligomers include polyoxymethylene. In other embodiments, the polyoxymethylene is paraformaldehyde, represented by the formula

wherein n is between about 6 and 100.

In yet another embodiment, the present invention provides a scavenger composition as in any of the previous embodiments, wherein the polyoxymethylene is trioxane, represented by the formula

In some embodiments, the present invention provides about 1-75％actives of the amine-based H₂S scavenger compound in solvent or liquid carrier and about 1-95％actives of the at least oxymethylene compound in solvent or liquid carrier.

In yet another exemplary embodiment, the present invention provides a method for removing primary or “tramp” amines fron a hydrocarbon stream， water stream or a multiphase mixture of hydrocarbon and water, or hydrocarbon, water and gas. The method for removing amines from a hydrocarbon stream comprises: (a) providing a scavenger composition to a hydrocarbon stream, the hydrocarbon stream containing a plurality of sulfide-containing compounds, wherein the scavenger composition comprises: an amine-based H₂S scavenger compound and at least one oxymethylene compound； and (b) contacting the sulfide-containing compounds with the amine-based H₂S scavenger composition, wherein the amine-based H₂S scavenger composition (i) scavenges a plurality of sulfide-containing compounds and produces primary or secondary amines, and (ii) the primary or secondary amines simultaneously react with at least one oxymethylene species in situ, to reduce the amount of primary or tramp amines in the hydrocarbon, water, or a multiphase mixture stream.

In some embodiments, the sulfide scavenger compound is an amine-aldehyde reactionproduct.

The present invention further provides a method for removing amines from a hydrocarbon stream as in any of the previous embodiments, wherein the plurality of sulfide-containing compounds is selected from the group consisting of organic sulfides, mercaptans, thiols, and H₂S.

In yet another embodiment, the prevent invention provides a method for removing amines from a hydrocarbon, water or multiphase streams as in any of the previous embodiments, wherein the amine-based H₂S scavenger compound is represented by the formula

wherein R comes from amines including MEA, MEPA, methylamine and other alkylamines, ethyleneamines (including ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine) , 1-amino-2-propanol, 2-amino-2-methylpropanol, 3-aminopropanol, methoxyethylamine, tris (hydroxymethyl) methylamine, dimethylaminoproylamine and mixtures thereof.

In some embodiments, the amine-based H₂S scavenger compound is selected from an amine-aldehyde reaction product that can release amines, such as bisoxazolidines and other linear amine-aldehyde adducts. In such embodiments, the amine used maybe selected from either linear, branched or cyclic primary and secondary amines, such as, for example, dialkylamines, alkanolamines, morpholine, piperazine and aminomethyl piperazine.

In yet another embodiment, the present invention provides a method for removing primary or tramp amines from a hydrocarbon stream as in any of the previous embodiments, wherein at least one oxymethylene compound includes oxymethylene oligomers. In some embodiments, the at least one oxymethylene compound may be in a solution, and wherein the solution is in (i) water, (ii) alcohols, (iii) diols, (iv) glycerol, or (v) mixtures thereof. In some embodiments, the present method provides oxymethylene oligomers that include oxymethylene, represented by the formula

wherein n>0.

In some embodiments, the prevent invention provides a method for removing amines from a hydrocarbon stream as in any of the previous embodiments, wherein the oxymethylene oligomers include polyoxymethylene. In other embodiments, the polyoxymethylene is paraformaldehyde, represented by the formula

wherein n is between about 6 and 100.

In yet another embodiment, the present invention provides a method for removing amines from a hydrocarbon stream as in any of the previous embodiments, wherein the reaction of the amine-based H₂S scavenger composition with a plurality of sulfide-containing compounds and with at least one oxymethylene species results in an absence of amines in the reaction product. In some embodiments, the hydrocarbon stream includes crude oil, refined oil stream, natural gas, water or multiphase mixtures. In some embodiments, the ratio of the amine-based H₂S scavenger composition to the at least one oxymethylene compound is 1: 50. In other embodiments, the ratio of the amine-based H₂S scavenger composition is 50: 1.

In yet another exemplary embodiment, the present invention provides for a scavenger composition comprising an amine-aldehyde reaction product and at least one oxymethylene compound. In some embodiments, the scavenger composition further comprises about 2-98％actives of the amine-aldehyde reaction product in solvent or liquid carrier, and about 2-98％actives of the at least one oxymethylene compound in solvent or liquid carrier.

The various embodiments provide for an improved sulfide scavenger to effectively remove sulfur impurities with amine-based H₂S scavenger compositions and simultaneously scavenge the resulting amines in situ. This sulfide scavenger has increased scavenging activity of sulfides and simultaneously reacts with an oxymethylene species to effective eliminate the production of tramp amines.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings, wherein:

FIG. 1 shows the kinetics and scavenging capacity of an embodiment of the composition of the present invention； and

FIG. 2 shows a general reaction scheme of the simultaneous scavenging of sulfides and elimination of amines in situ.

DETAILED DESCRIPTION OF THE INVENTION

The singular forms “a， ” “an” and “the” include plural referents unless the context clearly dictates otherwise. The endpoints of all ranges reciting the same characteristic are independently combinable and inclusive of the recited endpoint. All references are incorporated herein by reference.

The terms “comprises” ， “comprising” ， “includes” ， “including” ， “has” ， “having” ， “containing” ， “contains” or any other variation thereof， are intended to cover a non-exclusive inclusion. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article or apparatus.

The present invention generally provides improved sulfide scavenger compositions and methods of use. Sulfide scavengers of the present invention include amine-based H₂S scavenger compositions, which can also be referred to as triazine-scavenger compounds. Sulfide scavengers “scavenge” or otherwise reduce the amount of sulfur compounds present in the hydrocarbon stream, but produce troublesome primary or secondary “tramp” amines. These tramp amines react with the oxymethylene compound to reduce the amount of amines present while regenerating the amine-based H₂S or triazine scavenger.

The present invention provides a scavenger composition that includes a triazine-scavenger compound or other amine-aldehyde reaction products. The amine-based H₂S or triazine-scavenger compound may include, but is not limited to, s-triazine or 1, 3, 5-triazine, as represented by the following:

wherein R comes from amines such as alkanolamines (including monoethanolamine, 1-amino-2-propanol, 2-amino-2-methylpropanol, 3-aminopropanol, tris (hydroxymethyl) methylamine) , methoxypropylamine, methoxyethylamine, alkylamines including methylamine, ethyleneamines (including ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine) , dimethylaminoproylamine and mixtures thereof.

The scavenger composition of the present invention additionally includes an oxymethylene compound. The scavenger composition utilizes an oxymethylene compound, preferably oxymethylene oligomers, for the purpose of reacting with amines that are liberated when a certain scavenger or a scavenger solution removes sulfides. For example, amines that can be liberated include, but are not limited to, monoethanol amine, methylamine, methoxy propanylamine, or other primary or secondary amines. Sulfides as referenced herein may include compounds selected from the group consisting of organic sulfides, mercaptans, thiols, and H₂S, or the like.

The oxymethylene oligomers of the present invention can be represented by the following:

wherein n>0.

In some embodiments, oxymethylene oligomers comprise at least about 50％of the total weight percent of the scavenger composition. In other embodiments, at least about 25％of the total weight percent, in other embodiments, at least about 10％of the total weight percent, and in other embodiments, at least about 1％of the total weight percent of the scavenger composition.

The oxymethylene oligomers of the present invention may be provided in a solution. An oxymethylene oligomer solution can be comprised of (i) water, (ii) alcohols, (iii) diols, (iv) glycerol, or (v) mixtures thereof.

In some embodiments, the oxymethylene oligomers of the present invention include polyoxymethylene. In some embodiments, the polyoxymethylene is in solid form, such as paraformaldehyde. Paraformaldehyde may be represented by the following:

wherein n is between about 6 and 100.

In other embodiments, the polyoxymethylene may be selected from a trioxane, represented by the following:

In some embodiments, the scavenger composition comprises at least 1-98％actives of the amine-based H₂S scavenger compound and at least 1-98％actives of at least one oxymethylene compound in solvent or liquid carrier. In other embodiments, the amine-based H₂S scavenger compound comprises about 1-75％actives of the amine-based H₂S scavenger compound in solvent or liquid carrier and about 1-50％actives of the at least one oxymethylene compound in solvent or liquid carrier. In some embodiments, the solvent or liquid carrier may be selected from water, alcohols, diols glycerol, or combinations of the like.

In a preferred embodiment, the scavenger composition comprises at least 5-70％actives of MEA triazine and at least 30-95％actives of polyoxymethylene.

As shown in Fig. 1, the scavenger composition of the present invention exhibits enhanced kinetics in addition to an increase in scavenging capacity. These characteristics allow the scavenger composition to maintain the sulfide content at a low concentration in situ for an extended period of time. It is believed that the combination of both the oxymethylene and the amine-based H₂S scavenger or triazine compound contributes to the elimination of amine production or free MEA within the hydrocarbon stream, and further results in no solid reaction productbeing formed.

A further aspect of the invention generally provides a method for removing amines from a hydrocarbon stream. A hydrocarbon stream may include natural gas, crude oil and refined oil products. In another embodiment, the hydrocarbon stream may include multiphase (oil-water or oil-water-gas) streams.

One embodiment of the invention comprises the step of providing a scavenger composition to a hydrocarbon stream, wherein the hydrocarbon stream contains a plurality of sulfide-containing compounds. Examples of such sulfide-containing compounds include, but are not limited to, the group consisting of organic sulfides, mercaptans, thiols, and H₂S.

When the scavenger composition of the present invention reacts with a sulfide-containing compound, the scavenger composition scavenges the sulfides. As a result of the reaction of the amine-based H₂S scavenger or triazine compound and the sulfide-containing compound, amines are released. However, these amines simultaneously react with the oxymethylene compound to effectively eliminate the production of any amines or solid reaction product. Fig. 2 provides a general reaction scheme believed to represent the aforementioned process.

In order that those skilled in the art will be better able to practice the present disclosure, the following examples are given by way of illustration and not by way of limitation.

EXAMPLES

EXAMPLE 1

As shown in Table 1, three H₂S scavengers were evaluated by bubbling 3.2％H₂S+96.8％CO₂ gas at a flow rate of 600 scc/min through a 12 mL aqueous solution containing 6 mL of scavenger active components at room temperature and ambient pressure. At the end of 120min, the solution was analyzed for free amines.

TABLE 1

The 50％paraformaldehyde solution (Product A) did not contain amines, but showed poor kinetics and resulted in solid trithiane-type reaction product that are known to cause fouling. The MEA triazine product (Product B) showed fast kinetics and no solid trithiane. However, significant amount of free MEA was released. These free/tramp MEA is known to cause significant issues at the refinery by formation of corrosive MEA. HCl salt. The combination of both oxymethylene and triazine (Products C₁, C₂ and C₃) resolved drawbacks of both products by providing faster kinetics, no free MEA and no solid reactionproduct.

EXAMPLE 2

In reference to Fig. 1, product D was formulated by blending 50％paraformaldehyde solution with 10％MEA triazine. Product D which already contained <90％amines to begin with compared to Product B, also showed absence of tramp amines after reaction with H₂S. Product D was tested against A and B in Example 1 at 120℃ and 150 psig pressure in an autoclave reactor with 50％water+50％oil. A 0.2％H₂S gas in CO₂ was bubbled through the semi-continuous autoclave until a steady state of 2000ppm H₂S was achieved, when 1000ppm of the products was injected and the H₂S level monitored. Product D showed both excellent kinetics and increased capacity compared to products A and B.

In the foregoing specification, the invention has been described with reference to specific embodiments thereof. The amine scavengers of this method would be expected to be useful in other hydrocarbon processing operations besides those explicitly mentioned. It will be evident that various modifications and changes can be made to the methods and fluids of the invention without departing from the broader spirit or scope of the invention as set forth in the appended claims. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense. For example, specific amine scavengers and proportions thereof falling within the claimed parameters, but not specifically identified or tried in particular compositions, are anticipated and expected to be within the scope of this invention

What is claimed is:

Claims

A scavenger composition, comprising:

an amine-based H₂S scavenger compound； and

at least one oxymethylene compound capable of scavenging amines.
The composition of claim 1, wherein said amine-based H₂S scavenger compound is a hexahydrotriazine compound shown by the formula

wherein R comes from an amine selected from the group consisting of alkanolamines, monoethanolamine, 1-amino-2-propanol, 2-amino-2-methylpropanol, 3-aminopropanol, tris (hydroxymethyl) methylamine, methoxypropylamine, methoxyethylamine, alkylamines, methylamine, ethylamine, propylamine, butylamine, isobutylamine, ethyleneamines, ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminoproylamine, cyclic amines, cyclohexyl amine, aromatic amines, aniline and mixtures thereof.
The composition of claim 1, wherein said amine-based H₂S scavenger compound is an amine-aldehyde reaction product, wherein said amine comprises linear, branched or cyclic primary and secondary amines, including alkanolamines, dialkylamines, morpholine, piperazine, aminomethyl piperazine, and aldehydes comprising formaldehyde, glyoxal or glutaraldehyde.
The composition of claim 1, wherein said at least one oxymethylene compound includes oxymethylene oligomers.
The composition of claim 1, wherein said at least one oxymethylene compound is in a solution, and wherein said solution comprises (i) water, or (ii) alcohols, or (iii) diols, or (iv) glycerol, or (v) mixtures thereof.
The composition of claim 4, wherein said oxymethylene oligomers include oxymethylene, represented by the formula

wherein n>0.
The composition of claim 4, wherein said oxymethylene oligomers include polyoxymethylene.
The composition as in claim 7, wherein said polyoxymethylene is paraformaldehyde, represented by the formula

wherein n is between about 6 and 100.
The composition as in claim 7, wherein said polyoxymethylene is trioxane, represented by the formula
The composition as in claim 1, further comprising about 1-75％actives of said amine-based H₂S scavenger compound in solvent or liquid carrier and about 1-95％actives of said at least one oxymethylene compound in solvent or liquid carrier.
A method for removing amines from a hydrocarbon, water or multiphase stream, said method comprising:

(a) providing a scavenger composition to a hydrocarbon, water or multiphase stream, said hydrocarbon, water or multiphase stream containing a plurality of sulfide-containing compounds therein, wherein said scavenger composition comprises:

an amine-based H₂S scavenger compound and at least one oxymethylene compound； and

(b) contacting said plurality of sulfide-containing compounds with said amine-based H₂S scavenger composition,

wherein said amine-based H₂S scavenger composition

(i) scavenges said plurality of sulfide-containing compounds, and produces primary or secondary amines； and

(ii) said primary or secondary amines simultaneously react with said at least one oxymethylene species in situ, to reduce the amount of primary or secondary amines present in said hydrocarbon stream, water or multiphase stream.
The composition of claim 11, wherein said amine-based H₂S scavenger compound is an amine-aldehyde reaction product, where the amines comprises linear, branched or cyclic primary and secondary amines including alkanolamines, dialkylamines, morpholine, piperazine, aminomethyl piperazine, and aldehydes comprising HCHO, glyoxal or glutaraldehyde.
The method of claim 11, wherein said plurality of sulfide-containing compounds are selected from the group consisting of organic sulfides, mercaptans, thiols, and H₂S.
The method of claim 11, wherein said amine-based H₂S scavenger compound is represented by the formula

wherein R comes from an amine selected from the group consisting of alkanolamines, monoethanolamine, 1-amino-2-propanol, 2-amino-2-methylpropanol, 3-aminopropanol, tris (hydroxymethyl) methylamine, methoxypropylamine, methoxyethylamine, alkylamines, methylamine, ethylamine, propylamine, butylamine, isobutylamine, ethyleneamines, ethylene diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminoproylamine, cyclic amines, cyclohexyl amine, aromatic amines, aniline and mixtures thereof.
The method of claim 11, wherein said at least one oxymethylene compound includes oxymethylene oligomers.
The method of claim 11, wherein said at least one oxymethylene compound is in a solution, wherein said solution comprises (i) water, or (ii) alcohols, or (iii) diols, or (iv) glycerol, or (v) mixtures thereof.
The method of claim 15, wherein said oxymethylene oligomers include oxymethylene, representedby the formula

wherein n>0.
The method of claim 15, wherein said oxymethylene oligomers include polyoxymethylene.
The method of claim 18, wherein said polyoxymethylene is paraformaldehyde, represented by the formula

wherein n is between about 6 and 100.
The method as in claim 11, wherein said reaction of said amine-based H₂S scavenger composition with said plurality of sulfide-containing compounds and with said at least one oxymethylene species results in an absence of amines in the reaction product.
A scavenger composition, comprising:

an amine-aldehyde reaction product； and

at least one oxymethylene compound capable of scavenging amines.
The composition as in claim 21, further comprising about 2-98％actives of said amine-aldehyde reaction product in a solvent or liquid carrier, and about 2-98％actives of said at least one oxymethylene compound in a solvent or liquid carrier.