OIL MISCIBLE ADDITIVE COMPOSITIONS FOR MERCURY REMOVAL FROM LIQUID HYDROCARBONS

Abstract

The present application relates generally to processes, systems, and compositions for removing mercury from liquid hydrocarbons. In one embodiment, the application pertains to a method for removing mercury from hydrocarbons. The method comprises reacting a mercury species within the hydrocarbons with an additive composition to produce a reaction product. The reaction product typically comprises a different speciation for mercury than the original mercury species. The reaction product is then removed from the hydrocarbons. The additive composition employed comprises a sulfur or heteroatom donating substance and a substantially oil-soluble solvent.

Claims

1. A method for removing mercury from hydrocarbons, comprising: reacting a mercury species within the hydrocarbons with an additive composition to produce a reaction product wherein the reaction product comprises a different speciation for mercury than the mercury species; and removing at least a portion of the reaction product from the hydrocarbons; wherein the additive composition comprises an effective amount of a sulfur or heteroatom donating substance and a solvent which is substantially miscible with oil wherein the heteroatom is nitrogen, sulfur, oxygen, or a mixture thereof.

2. The method of claim 1, wherein the additive composition further comprises water.

3. The method of claim 1, wherein the sulfur or heteroatom donating substance comprises a sulfide, a thiolate functionalized solid, a thiol, a dithiol, a dithiocarbamate, or any combination thereof.

4. The method of claim 3, wherein the sulfur or heteroatom donating substance comprises the thiol, the dithiol, or the dithiocarbamate, or any combination thereof and wherein the sulfur or heteroatom donating substance further comprises a polymer.

5. The method of claim 3, wherein the sulfide is Na.sub.2S, (NH.sub.4).sub.2S, a polysulfide having the formula MSx wherein M is selected from Na.sub.2, K.sub.2, or Ca, or any combination thereof.

6. The method of claim 3, wherein the thiolate functionalized solid comprises self-assembled monolayers on mesoporous supports (SAMMS), a functionalized silica gel (SiliaMetS), or any combination thereof.

7. The method of claim 3, wherein the dithiol comprises 1,3,4-thiadiazole-2,5-dithiol (TDT).

8. The method of claim 1, wherein the solvent comprises a glycol, an alcohol, or any mixture thereof.

9. The method of claim 8 wherein the glycol comprises a polyalkylene glycol.

10. The method of claim 8, wherein the glycol comprises dipropylene glycol methyl ether, 2-butoxyethanol, or any combination thereof.

11. The method of claim 8, wherein the alcohol comprises isopropyl alcohol.

12. The method of claim 1, wherein the additive composition comprises a concentration of the sulfur or heteroatom donating substance which is less than a saturation concentration of the sulfur or heteroatom donating substance in the additive composition.

13. The method of claim 1, wherein the hydrocarbons comprise a crude, a condensate, a slop oil, a distillate, or any combination thereof.

14. The method of claim 1, wherein the additive composition is a component of a wash water solution that is mixed with the hydrocarbons in a mixing vessel

15. The method of claim 1, wherein the additive composition is added to a feed of the hydrocarbons before the hydrocarbons are introduced into a reactor.

16. The method of claim 1, wherein the hydrocarbons and the additive composition are introduced into a reactor on a continuous basis.

17. The method of claim 1, wherein the hydrocarbons and the additive composition are introduced into a reactor and are mixed in a batch process.

18. The method of claim 1, wherein the reaction of the mercury species with the hydrocarbons with the additive composition is performed in a dedicated reactor, in a mixing tank, in a pipe with a static mixer, in a pipe with equipment or bends for mixing and residence time, or any combination thereof.

19. The method of claim 18 wherein the dedicated reactor is a continuous stirred tank reactor.

20. The method of claim 1, wherein the reaction product is a precipitate and wherein the removing comprises a solid-liquid separation process.

21. The method of claim 20, wherein the solid-liquid separation process comprises filtration, centrifugation, sedimentation, flotation, or any combination thereof.

22. The method of claim 1, wherein the removing comprises an extraction process comprising desalting, water washing, sulfidic extraction, pH adjustment, or any combination thereof.

23. The method of claim 1, wherein the removing is conducted in the absence of desalting.

24. The method of claim 1, wherein the additive composition further comprises a phase transfer agent.

25. The method of claim 24, wherein the phase transfer agent comprises an oil soluble cation salt.

26. The method of claim 24, wherein the phase transfer agent comprises a quaternary ammonium salt, a quaternary phosphonium salt, an imidazolium salt, or any combination thereof.

27. The method of claim 26, wherein the quaternary ammonium salt comprises an alkyl ammonium salt, an aryl ammonium salt, or any combination thereof.

28. The method of claim 27, wherein the quaternary ammonium salt comprises tetrabutylammonium chloride (TBAC).

29. A composition comprising: water; a sulfur or heteroatom donating substance; and an amount of a solvent which is substantially miscible with oil, wherein the amount of the solvent is sufficient to dissolve at least a portion of the sulfur or heteroatom donating substance and wherein a concentration of the sulfur or heteroatom donating substance in the composition is less than a saturation concentration of the sulfur or heteroatom donating substance in the composition.

30. The composition of claim 29 wherein the solvent comprises dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl alcohol, or any combination thereof.

31. The composition of claim 29, which further comprises a hydrocarbon and one or more mercury compounds.

32. The composition of claim 29, which further comprises a phase transfer agent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] So that the way the above recited features, advantages, and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings only illustrate preferred embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that vary only in detail. In the drawings:

[0006] FIG. 1 depicts steps of a representative process.

[0007] FIG. 2 depicts steps of a representative process.

[0008] FIG. 3 depicts steps of a representative process.

[0009] FIG. 4 depicts steps of a representative process.

[0010] FIG. 5 depicts steps of a representative process.

[0011] FIG. 6 depicts steps of a representative process.

[0012] FIG. 7 depicts steps of a representative process.

[0013] FIG. 8 depicts steps of a representative process.

[0014] FIG. 9 depicts steps of a representative process.

[0015] FIG. 10 depicts amounts of Hg after filtration vs. time as described in Example 3.

DETAILED DESCRIPTION

[0016] Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, different companies may refer to a component by different names.

Definitions

[0017] The terms comprise (as well as forms, derivatives, or variations thereof, such as comprising and comprises) and include (as well as forms, derivatives, or variations thereof, such as including and includes) are inclusive (i.e., open-ended) and do not exclude additional elements or steps. For example, the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Accordingly, these terms are intended to not only cover the recited element(s) or step(s) but may also include other elements or steps not expressly recited. Furthermore, as used herein, the use of the terms a or an when used in conjunction with an element may mean one, but it is also consistent with the meaning of one or more, at least one, and one or more than one. Therefore, an element preceded by a or an does not, without more constraints, preclude the existence of additional identical elements.

[0018] The use of the term about applies to all numeric values, whether or not explicitly indicated. This term generally refers to a range of numbers that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numeric values (i.e., having the equivalent function or result). For example, this term can be construed as including a deviation of +10 percent of the given numeric value provided such a deviation does not alter the end function or result of the value. Therefore, a value of about 1% can be construed to be a range from 0.9% to 1.1%. Furthermore, a range may be construed to include the start and the end of the range. For example, a range of 10% to 20% (i.e., range of 10%-20%) includes 10% and also includes 20%, and includes percentages in between 10% and 20%, unless explicitly stated otherwise herein. Similarly, a range of between 10% and 20% (i.e., range between 10%-20%) includes 10% and also includes 20%, and includes percentages in between 10% and 20%, unless explicitly stated otherwise herein.

[0019] The term if may be construed to mean when or upon or in response to determining or in accordance with a determination or in response to detecting, that a stated condition precedent is true, depending on the context. Similarly, the phrase if it is determined [that a stated condition precedent is true] or if [a stated condition precedent is true] or when [a stated condition precedent is true] may be construed to mean upon determining or in response to determining or in accordance with a determination or upon detecting or in response to detecting that the stated condition precedent is true, depending on the context.

[0020] It is understood that when combinations, subsets, groups, etc. of elements are disclosed (e.g., combinations of components in a composition, or combinations of steps in a method), that while specific reference of each of the various individual and collective combinations and permutations of these elements may not be explicitly disclosed, each is specifically contemplated and described herein. By way of example, if an item is described herein as including a component of type A, a component of type B, a component of type C, or any combination thereof, it is understood that this phrase describes all of the various individual and collective combinations and permutations of these components. For example, in some embodiments, the item described by this phrase could include only a component of type A. In some embodiments, the item described by this phrase could include only a component of type B. In some embodiments, the item described by this phrase could include only a component of type C. In some embodiments, the item described by this phrase could include a component of type A and a component of type B. In some embodiments, the item described by this phrase could include a component of type A and a component of type C. In some embodiments, the item described by this phrase could include a component of type B and a component of type C. In some embodiments, the item described by this phrase could include a component of type A, a component of type B, and a component of type C. In some embodiments, the item described by this phrase could include two or more components of type A (e.g., A1 and A2). In some embodiments, the item described by this phrase could include two or more components of type B (e.g., B1 and B2). In some embodiments, the item described by this phrase could include two or more components of type C (e.g., C1 and C2). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type A (A1 and A2)), optionally one or more of a second component (e.g., optionally one or more components of type B), and optionally one or more of a third component (e.g., optionally one or more components of type C). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type B (B1 and B2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g., optionally one or more components of type C). In some embodiments, the item described by this phrase could include two or more of a first component (e.g., two or more components of type C (C1 and C2)), optionally one or more of a second component (e.g., optionally one or more components of type A), and optionally one or more of a third component (e.g., optionally one or more components of type B).

[0021] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have elements that do not differ from the literal language of the claims, or if they include equivalent elements with insubstantial differences from the literal language of the claims.

[0022] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. All citations referred herein are expressly incorporated by reference.

General Process

[0023] In one embodiment the application pertains to methods for removing mercury from hydrocarbons. The specific hydrocarbons that may benefit from the instant process are not particularly limited and generally include liquid hydrocarbons that comprise one or more mercury species to be reduced or eliminated. Suitable hydrocarbons may comprise crude, condensate, a slop oil, distillate, or any combination thereof.

[0024] The processes described herein remove many different types of mercury species with representative mercury species including, for example, any mercury species that may form a reaction product in the process that comprises a different speciation for mercury than the original mercury species in the hydrocarbon. In particular, the processes described herein are effective for those original mercury species that are dissolved or otherwise suspended in hydrocarbons that tend form a precipitate or other solid when subjected to the steps described herein.

[0025] In general, the processes comprise reacting a mercury species within the hydrocarbons with an additive composition to produce a reaction product. The reaction product usually comprises a different speciation for mercury than the mercury species. At least a portion of the reaction product is then removed from the hydrocarbons. The additive composition may comprise a sulfur or heteroatom donating substance and an amount of a solvent which is substantially miscible with oil. The amount of the solvent is typically at least that amount which is sufficient to dissolve at least a portion of the sulfur or heteroatom donating substance. Water may also be optionally present with or in the additive composition.

Reacting

[0026] The mercury species within the hydrocarbons are reacted with an additive composition to produce a reaction product. The reaction conditions are not particularly critical so long as the desired reaction product or products are formed which can be at least partially removed from the mixture. The specific reaction conditions may differ depending upon, for example, the hydrocarbon composition, the mercury species in the hydrocarbon composition, the desired reaction product, the equipment employed, and the desired results.

[0027] Typically, the reacting may occur in any convenient manner. For example, in some embodiments the additive composition may be a component of a wash water solution that is mixed with the hydrocarbons in a mixing vessel. In other embodiments the additive composition may be added to a feed of the hydrocarbons before the hydrocarbons are introduced into a reactor. If a reactor is employed, then the hydrocarbons and the additive composition may be introduced into a reactor on a continuous basis, a batch basis, or a combination thereof.

[0028] The reacting of the mercury species comprising the hydrocarbons with the additive composition may be performed in any convenient vessel which may vary depending upon, for example, the origin of the hydrocarbons. In some embodiments, the reacting of the mercury species comprising the hydrocarbons with the additive composition may be performed in a dedicated reactor such as a continuous stirred tank reactor. In other embodiments the reacting may occur in, for example, a mixing tank, a storage tank, or in a pipe with a static mixer, or in a pipe with equipment or bends for mixing and/or residence time, and/or any combination thereof.

Removing

[0029] The reacting step generally produces a reaction product that comprises a different speciation for mercury than the mercury species. At least a portion up to all of the reaction product formed is then removed from the hydrocarbons. The specific manner of removing is not particularly critical and may depend upon, for example, the original hydrocarbon composition, the mercury species in the original hydrocarbon composition, the amount and type of the reaction product, the equipment employed, and the desired amount of removal.

[0030] In situations where the reaction product is a precipitate and/or other solid suitable removing steps may comprise, for example, a solid-liquid separation process. The specific solid-liquid separation process is not particularly limited and may comprise filtration, centrifugation, sedimentation, flotation, or any combination thereof. In other embodiments, the removing may additionally, or alternatively comprise, for example, an extraction process. Such extraction processes may comprise steps such as, for example, desalting, water washing, sulfidic extraction, pH adjustment, or any combination thereof. In some embodiments desalting is advantageously not necessarily due to the nature of the additive composition comprising the substantially oil miscible solvent.

Additive Compositions

[0031] The additive compositions useful herein vary depending upon, for example, such factors as the original hydrocarbon composition, the type and amount of mercury species in the original hydrocarbon composition, the amount and type of the reaction product desired, the equipment employed, the desired amount of removal of mercury, and/or the other steps employed.

[0032] Typically, useful additive compositions herein may comprise a sulfur or heteroatom donating substance and a solvent which is substantially miscible with oil. Other solvents such as water and/or other useful solvent or solvents may be optionally employed if desired.

[0033] The specific sulfur or heteroatom donating substance and amount may vary depending upon, for example, the type and amount of mercury species in the original hydrocarbon composition, the amount and type of the reaction product desired, and the amount and type of substantially oil-miscible solvent and other components. Taking as an example to illustrate the processes pertaining to this application, the sulfur or heteroatom donating substance may comprise a sulfide, a thiolate functionalized solid, a thiol, a dithiol, a dithiocarbamate, or any combination thereof. In some embodiments, the sulfur or heteroatom donating substance may further comprise a polymer such as, for example, a NALMET compound from Nalco and/or a METCLEAR compound available from GE/Suez.

[0034] Representative sulfides in the additive compositions may include, for example, those compositions wherein the sulfide is Na.sub.2S, (NH.sub.4).sub.2S, a polysulfide having the formula MSx wherein M is selected from Na.sub.2, K.sub.2, or Ca, or any combination thereof. Representative thiolate functionalized solids in the additive compositions may include, for example, self-assembled monolayers on mesoporous supports (SAMMS), a functionalized silica gel (SiliaMetS), or any combination thereof. Representative dithiols may comprise 1,3,4-thiadiazole-2,5-dithiol (TDT).

[0035] As described above, the amount of sulfur or heteroatom donating substance in the additive composition may vary. Typically, the amount employed depends upon how much mercury is to be removed and the specific sulfur or heteroatom donating substance. In some embodiments a concentration of the sulfur or heteroatom donating substance in the composition is less than a saturation concentration of the sulfur or heteroatom donating substance in the composition. This may vary depending upon the sulfur or heteroatom donating substance and the solvent. For example, a saturation concentration for Na.sub.2Sx in DPGME may be about 25,000 ppm S.

[0036] In many applications the amount of sulfur or heteroatom donating substance that is dosed into the hydrocarbons to be treated is at least about 1, or at least about 5, or at least about 10, or at least about 25 ppm on the basis of the sulfur or heteroatom. On the other hand, the amount of sulfur or heteroatom donating substance that is dosed into the hydrocarbons to be treated may be present in an amount of up to about 1000 or higher, or up to about 800, or up to about 400, or up to about 200, or up to about 100, or up to about 50 ppm on the basis of the sulfur or heteroatom. The aforementioned are representative dosages for treating hydrocarbons and may be adjusted depending upon, for example, the sulfur or heteroatom donating substance, the amount of hydrocarbon, the amount of mercury in the hydrocarbons, and/or the amount of solvent.

[0037] The amount and type of solvent which is substantially miscible with oil is not particularly limited so long as the solvent sufficiently dissolves both the sulfur or heteroatom donating substance and the hydrocarbon containing mercury so as to facilitate the desired reaction between mercury and the sulfur or heteroatom donating substance. Suitable substantially oil-miscible solvents are those that are at least partially soluble to near fully soluble in the oil phase.

[0038] In some embodiments, the substantially oil-miscible solvent comprises a glycol, an alcohol, or any mixture thereof. The glycol and/or glycol derivatives may comprise a polyalkylene glycol, dipropylene glycol methyl ether, 2-butoxyethanol, or any combination thereof. Suitable alcohols may comprise isopropyl alcohol. If using a polyalkylene glycol, then the molecular weight should be such that it has an appropriate viscosity for the composition. Such molecular weight may vary depending upon other components but a suitable range may be less than about 1600, e.g., Polyalkylene Glycol Monobutyl Ether available under the tradenames JEFFOX or UCON.

[0039] The amount of the substantially oil-miscible solvent in the additive composition may vary depending upon the nature of the substantially oil-miscible solvent and hydrocarbons in which it will be employed. Generally, an amount is employed that is useful to dissolve at least a portion of the sulfur or heteroatom donating substance so as to facilitate the desired reaction between mercury in the hydrocarbon and the sulfur or heteroatom donating substance.

[0040] The additive composition may also comprise water and other solvents so long as they do not substantially interfere with the desired reaction. Similarly, additional optional ingredients for the aqueous additive composition may be added so long as they do not substantially interfere with the desired mercury removal.

[0041] The above description is also applicable to certain additives that comprise sulfur and/or nitrogen in the chemical structure such as, for example, functionalized silica gel (SiliaMetS) with cysteine, diamine on the chemical structure.

[0042] If desired, the additive composition may also comprise an optional phase transfer agent. The amount and type of the optional phase transfer agent is not particularly limited so long as the phase transfer agent facilitates phase transfer and thereby may increase the reaction kinetics and/or the extent of reaction between mercury and the sulfur or heteroatom donating substance. Suitable phase transfer agents are those that are at least partially soluble to near fully soluble in the aqueous phase and oil phase.

[0043] In some embodiments, the phase transfer agent comprises a quaternary ammonium salt, a quaternary phosphonium salt, an imidazolium salt, or any combination thereof. The specific quaternary ammonium salt is not particularly limited and may comprise an alkyl ammonium salt, an aryl ammonium salt, or any combination thereof. Particularly preferable alkyl ammonium salts include those with an alkyl group of 1 to 6 carbons, preferably 1 to 3 carbons. In some embodiments, the quaternary ammonium salt comprises tetrabutylammonium chloride (TBAC).

[0044] The amount of the phase transfer agent in the additive composition may vary depending upon the nature of the phase transfer agent and hydrocarbons in which it will be employed. Generally, an amount is employed that is useful to control the desired reaction kinetics and/or the extent of reaction. In some embodiments, the amount of the phase transfer agent is at least about 1, or at least about 10, or at least about 50, or at least about 250, or at least about 500 ppm in the aqueous additive composition. On the other hand, the amount of phase transfer agent in the aqueous additive composition may be present in an amount of up to about 1000, or up to about 900, or up to about 750, or up to about 600, or up to about 500 ppm.

EXAMPLES

Example 1Solvent Miscibility in Oil

[0045] Solutions of oil miscible solvents with sulfur donating compounds were made by contacting oil miscible solvents with solid sulfur donating compounds (Na.sub.2S, 1,3,4 Thiadiazole-2,5 dithiol), and aqueous solutions of sulfur donating compounds. The amount of sulfur donating compound partitioning to the oil miscible solvent was determined by XRF and LECO sulfur analysis of the oil miscible solvent.

[0046] Solvents with high aromatic content (Diesel, kerosene, xylene, toluene) did not have high sulfide solubility. Iso-propyl alcohol (IPA) had higher solubility of sulfides than aromatic solvents but was below 10,000 ppm (1 wt. %) 2-butoxyethanol, and dipropylene glycol methyl ether (DPGME) had higher solubility of sulfides. In particular, polysulfide (Na.sub.2Sx) had above 1 wt. % sulfur solubility in DPGME. The table below shows sulfur determined by XRF in ppm.

TABLE-US-00001 1,3,4 Sulfur by XRF Na.sub.2S + Thiadiazole- (ppm) Na.sub.2S Na.sub.2S TBAC Na.sub.2S (NH.sub.4).sub.2S Na2Sx 2,5 dithiol DI Water 33,500 IPA 3,090 2,730 2,520 5,760 1,220 2,200 Diesel 630 1,000 510 680 720 880 Kerosene <5 <5 510 Xylene 4 6 Toluene 23 <5 27 130 260 120 2- 600 1,410 2,260 3,740 6,400 16,240 butoxyethanol Dipropylene 840 1,680 2,470 2,550 6,340 25,410 2,500 Glycol Methyl Ether

Example 2Mercury Removal by Sulfur Donating Compounds

[0047] Various additive compositions in various doses were added to condensate and mixed on a vortex table for 1 hr and then filtered by 0.45 m filter. The mercury concentration of the filtrate was determined by Lumex mercury analyzer. Addition of polysulfide in DPGME (25,000 ppm S in additive mixture) increased mercury removal by 0.45 m filtration from 65% to 90-94% at dosages >50 ppm S in the condensate as shown in the table below.

TABLE-US-00002 Polysulfide + % Removal by 0.45 DPGME (S ppm) m 1000 94 500 93 250 93 100 90 50 91 0 65

[0048] Furthermore, as shown in the table below addition of 1,3,4-Thiadiazole-2,5 dithiol (TDT) in DPGME (2500 ppm S in additive mixture) increased mercury removal by 0.45 m filtration from 65% to 88-94% at dosages >5 ppm S in the condensate while addition of (NH4)2S in DPGME (6300 ppm S in additive mixture) increased mercury removal by 0.45 m filtration from 65% to 88-94% at dosages >5 ppm S in the condensate.

TABLE-US-00003 Dosage of sulfide Removal by 0.45 m filtration (%) (S ppm) TDT in DPGME (NH4)2S in DPGME 200 94 94 100 93 91 50 88 90 10 88 89 5 88 88 0 65 65

[0049] In sum, as shown above usage of sulfides in DPGME can increase mercury removal by filtration.

Example 3Comparison of DPGME Additive Compositions vs. Aqueous Compositions

[0050] Experiments were conducted to determine if Na2Sx had increased reaction rate in a substantially oil miscible solvent, DPGME, compared to in water. Solutions of 2.5 wt. % Na2Sx in water and DPGME were made. The reaction rate of Na2Sx with mercury condensate was examined using a Parr reactor with controlled mixing. The reaction rate was examined by sampling condensate at specific time periods and immediately filtering by 0.45 m filters. The samples were then analyzed for total mercury by Lumex.

[0051] The reaction rates were compared between dosing 50 ppm Na2Sx in the condensate with an aqueous solution and a DPGME solution (each 25,000 ppm Na2Sx in additive mixture). The mixing intensity was fixed at 250 rpm. The reaction rate is quicker using a DPGME solution rather than an aqueous solution. The extent of reaction is more complete at 60 min with DPGME based additive mixture (630 vs 710 ppb).

[0052] The reaction rates were compared between dosing 500 ppm Na2Sx in condensate with an aqueous solution and a DPGME solution (each 25,000 ppm Na.sub.2Sx in additive mixture). The mixing intensity was fixed at 500 rpm. The reaction rate is quicker using a DPGME solution rather than an aqueous solution. Reaction time of 15 min results in 390 ppb with DPGME and 610 ppb with water. The extent of reaction is more complete at 60 mins with DPGME (340 vs 490 ppb).

[0053] FIG. 10 shows the effect on mercury levels of DPGME additive compositions vs. aqueous additive compositions.

Representative Specific Process Embodiments

[0054] Additive composition+Filtration: As shown in FIG. 1, the process may include the following steps: 1) Additive composition is dosed into hydrocarbon feed, 2) Additive composition and hydrocarbon feed react in a continuous stirred tank reactor (CSTR) or other type of reactor where mercury species are precipitated, 3a) Reacted hydrocarbon feed is then filtered; or 3b) Alternatively, other solid-liquid processes may be used in place of filtration including sedimentation, flotation, centrifugation, electrostatic separation, etc. Some embodiments may use combinations of solid-liquid separations. 4) The process results in a low mercury product.

[0055] Additive composition+water wash or sulfidic extraction: The example process of FIG. 2 includes the following steps: 1) Additive composition is dosed into hydrocarbon feed, 2) Additive composition and hydrocarbon feed react in a CSTR or other type of reactor where mercury species are precipitated, 3) Reacted hydrocarbon feed is then mixed with water or an additive composition such as described herein, 4) Results in a low mercury product, 5) Spent wash water or sulfidic solution is treated or disposed.

[0056] Water wash or sulfidic extraction: The example process of FIG. 3 includes the following steps: 1) Feed is mixed with a wash water with additive composition or sulfidic solution, 2) The spent wash water or sulfidic solution is separated from the feed, 3) Results in a low mercury product, 4) Spent wash water or sulfidic solution is treated or disposed.

[0057] Water wash or sulfidic extraction with recycling: The process of FIG. 4 is the same as FIG. 3, except with a recycle loop on the water wash/sulfidic extraction solution. A fraction of fresh wash water or sulfidic extraction solution is added with an equal volume being discharged for treatment or disposal. This will reduce the amount of water/sulfidic solution needed. Additionally or alternatively, at least a portion up to all of the extraction solution may be recycled with or without filtration and additives may be employed up to the point when extraction is no longer effective. That is, if desired, spent water may be filtered and at least partially to fully recycled and any desired additive composition may be employed with the recycled water.

[0058] Process options: Several options exist for implementation of the disclosed processes. Non-limiting examples of process options are provided below.

[0059] Overall: The overall process may be batch or continuous.

[0060] Additive compositions are as described above. Those additive compositions may be used alone or in combination with each other and/or other glycols or acids, such as (ethylene glycol (MEG), triethylene glycol (TEG)) or terephthalic acid (or similar) may also increase removal.

[0061] Reactor: The reactor used in the disclosed process may be a continuous stirred tank reactor (CSTR), or any other dedicated reactor. By way of non-limiting example, the reactor may include an existing tank with mixer or recirculation pump (e.g., a floating storage and offloading (FSO) storage tank, a D/S storage tank, a U/S oil treatment tank). By way of another non-limiting example, the reactor may include a pipe and static mixer (e.g., a desalter). By way of further non-limiting example, the reactor may include a pipe with equipment or bends for mixing and residence time (e.g., a wellhead chemical injection, injection before a heat exchanger, a separator with baffles).

[0062] Solid-liquid separation: Solid-liquid separation as used in the disclosed process may be performed using a variety of techniques. By way of non-limiting example, such separation techniques may include filtration, centrifugation, sedimentation (e.g., in a cargo hold, in an oil storage tank), or flotation.

[0063] Extraction: The extraction used in the disclosed process may be performed using a variety of techniques and associated equipment. Non-limiting examples include using a desalter. As another non-limiting example, the extraction may include washing using an existing tank with a mixer, recirculation pumps, and spray nozzles. As another non-limiting example, the extraction may include an inlet separator vessel, two phase separation vessel, or any other useful phase separation technique or vessel. As another non-limiting example, the extraction may include sulfidic extraction. Extraction may include water washing, which may or may not include performing pH adjustments and/or the use of a further additive or additives. Extraction may further include recycling of wash water and/or the sulfidic extraction solution.

[0064] Wash water/additive solutions source: The water source of the wash water and/or sulfidic solution may include, by way of non-limiting example, fresh water, fresh process water, recycle/spent water, or a non-freshwater source. Non-limiting examples of recycle/spent water include cooling tower blowdown, stripped sour water, and desalter brine water. Non-limiting examples of non-freshwater sources include seawater and produced water.

[0065] Spent wash water/sulfidic additive solution disposal: Disposal of the spent wash water and/or sulfidic solutions used in the disclosed process may include treatment and/or direct disposal in a disposal well. Disposal may include disposal in an injection well alone or after a combination of other injection streams such as produced water and/or refinery wastewater. Treatment of the spent wash water and/or sulfidic additive solution for eventual disposal may be performed using an existing treatment system or using a dedicated aqueous treatment system. Existing treatment systems may include treatment systems used for produced water (e.g., gravity separators, gas flotation, media filtration/adsorption, chemical treatment) or refinery effluent systems (e.g., gravity separators, flotation, chemical flocculation/coagulation, bioreactors, media filtration/adsorption). A dedicated treatment system for spent wash water and/or sulfidic solutions ay include a system dedicated to mercury and/other heavy metal removal.

[0066] Emulsion removal and disposal: The emulsion phase, which may be withdrawn with the spent wash water/additive solution may contain significant concentrations of mercury. Separation and treatment of this stream may be a beneficial part of the process. The oil/hydrocarbon and aqueous phase may be separated from the emulsion by gravity separation, flotation, centrifugation, or other processes. The aqueous phase can be disposed of or recycled in the process. The oil/hydrocarbon phase may be disposed or treated further by filtration, centrifugation, or other methods and combined with the low mercury produced. The solids removed by the separation process may contain higher mercury and may require disposal.

[0067] Chemical injection upstream of desalter. In this example embodiment, the reaction between mercury and the additive composition occurs in pipes and at a desalter mixing valve. Mercury partitions from the crude oil to the desalter brine water and emulsion phase. The desalter brine water and optionally the emulsion phase is withdrawn to the effluent treatment plant. Mercury is removed in the process units in the effluent treatment plant including any one or a combination of the following: sedimentation, activated carbon or other adsorbents, gravity separators (API separators), flotation, and/or a bioreactor.

[0068] Chemical injection upstream of oil treatment process in upstream. In this example embodiment, additive compositions are injected near the wellhead or before oil/water separation tanks. Turbulence and long pipe run allow enough residence time for the additive composition to react with mercury. Mercury is separated out in the oil/water separation processes (tanks with baffles) or other solid-liquid separations units (filters, centrifuges).

[0069] Water washing/extraction in FSO cargo tanks, or other oil storage tanks. Feed with an initial concentration of mercury is placed in a holding tank. Water is pumped into a tank to a volume large enough to allow recirculation of water. Additive compositions are added to either the oil phase, aqueous phase, or both. The water and/or emulsion phase is pumped into the oil phase directly or with nozzles to allow for mixing of the water and oil phases. This continues for several volumes or until mercury concentrations decrease in the oil phase. The pumps are turned off to allow the water and oil phases to separate. The water and/or emulsion phase is removed to result in a lower mercury concentration in oil. In certain embodiments, this process may also be used for sulfidic extraction. In another embodiment, the pump may withdraw from both the oil and water phase to a static mixer before returning to the tank for enhanced mixing. In another embodiment, in a continuous process oil and water can be pumped to a static mixer before the tank. Water and oil would then be continuously withdrawn from the tank. In the water washing/extraction process, the spent wash water/sulfidic solution may be disposed in an injection well alone or with other aqueous streams (e.g., produced water, refinery wastewater).

[0070] Example Visualization: The figures described below provide example visualizations for embodiments of the water washing/extraction in vessels, such as FSO cargo tanks, or other oil storage tanks. In the depicted embodiments below, the hydrocarbon phase will generally have a reduced mercury concentration relative to its source.

[0071] FIG. 5 depicts a multi-tank system (e.g., a two-tank system) that utilizes water/oil circulation to maximize mixing between the aqueous and oil phases. One of the tanks, such as a storage tank, may be outfitted with crude oil wash (COW) nozzles. The nozzles rotate to allow for distribution and mixing. In this example, pump 1 and the COW nozzles are used for an initial transfer of water (e.g., an aqueous solution with additive compositions) from tank 2 to tank 1 with metal-containing hydrocarbons. Pump 2 is then utilized, along with a series of valves and the COW nozzles, to recirculate the mixture to enhance mixing. This allows the additive compositions in the aqueous phase to interact with the metals (e.g., mercury) in the hydrocarbons.

[0072] Alternative embodiments for the disclosed process used with water washing/extraction in FSO cargo tanks, or other oil storage tanks are depicted below. In particular, FIGS. 6-8 depict embodiments where the aqueous and oil phases are mixed using recirculation, and optionally additional features.

[0073] FIG. 6 depicts an embodiment where the aqueous phase is recirculated via introduction above the oil phase. The aqueous phase is withdrawn from a level of the tank corresponding to the aqueous phase and reintroduced to the tank into the oil phase. This may be considered a batch process.

[0074] FIG. 7 depicts an embodiment where the aqueous phase exiting the water outlet may be recirculated via introduction above the oil phase and a COW nozzle and/or into the oil/water inlet. The aqueous phase is withdrawn from a level of the tank corresponding to the aqueous phase and reintroduced to the tank into the oil phase. This may be considered a continuous process, but a batch approach is also contemplated.

[0075] Certain embodiments of this disclosure may utilize a static mixer situated outside (or, in other embodiments, inside) of the vessel. FIG. 8 depicts an embodiment where a batch process uses a storage tank and includes water inlet and outlet options for direct injection of the aqueous phase into the hydrocarbon phase, and/or withdrawal of both hydrocarbons and the aqueous phase at a position proximate their interface (e.g., as an emulsion phase). Both withdrawn streams may be mixed in a static mixer in a particular ratio and the resulting mixture may be reintroduced to the top of the hydrocarbon phase (away from the interface of both phases) to encourage diffusion/mixing. The ratio may be controlled by the rate of withdrawal of the phases.

[0076] FIG. 9 depicts an embodiment of a continuous process that utilizes a static mixer upstream of a tank, such as an existing oil cleaning/storage tank. In this example embodiment, water and oil (e.g., an aqueous solution with an additive composition and the hydrocarbons, respectively) are introduced to a static mixer, which then introduces a mixture into the tank.

[0077] The downstream portion of the embodiment of FIG. 9 includes an oil outlet for the hydrocarbons, an outlet for an emulsion phase proximate the interface between the hydrocarbon and aqueous phases, and a water outlet. The rate of injection of water and oil may be balanced with the rate of withdrawal of the hydrocarbons, water, and emulsion phase.

[0078] It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of example embodiments. For example, the functions described above and implemented as the best mode for operating the present invention are for illustration purposes only. Other arrangements and methods may be implemented by those skilled in the art without departing from the scope and spirit of this invention. Moreover, those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.