Compositions for remediation of chemical processing equipment having dithiazine foulant and methods of using said compositions

Abstract

Methods and compositions for the removal of dithiazines from chemical processing equipment.

Description

COMPOSITIONS FOR REMEDIATION OF CHEMICAL PROCESSING EQUIPMENT HAVING DITHIAZINE FOULANT AND METHODS OF USING SAID COMPOSITIONSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claimsthebenefitof U.S. Provisional Application No. 63 / 562,019, filedMarch 6, 2024, the entire contents of which is incorporated by reference herein.FIELD OF THE INVENTION

[0002] The present invention relates to compositions and methodsfor safely removing foulants from surfaces. More specifically, the present invention relates to compositions and methods for safely removing dithiazine-based foulants from surfaces of chemical processing equipment.BACKGROUND OF THE DISCLOSURE

[0003] Hydrogen sulfide (H2S) and organic sulfides are found within geological formations associated with oil and gas reserves. Due to their toxicity and corrosive nature, they are generally reduced or removedfrom hydrocarbon streams during production in a process called “sweetening” A common approach is to use triazine or derivatives thereof as an H2S scavenger. Triazine-based H2S scavengers react, with hydrogen sulfide converting it to a more non-volatile product, which can be more easily removed from hydrocarbon streams. Typically commercial scavenger formulations use low molecular weight aldehydes such as formaldehyde, but ketones can also be used. Amine-based H2S scavengers are very effective at removing H2S however a major drawback is that they commonly form dithiazine-based byproducts. One of the most common, and problematic, dithiazine-based byproduct is amorphous dithiazine. Amorphous dithiazine is exceptionally insoluble, and substantial quantities can depositthroughout a gas processing system. Dithiazine deposits are a significant problem to the oil and gas processing industry. They can form blockages in various chemical processing equipment such as oil and gas processing equipment, tubulars, storage tanks, truck tanks, and water disposal wells. Cleanup procedures are time consuming and difficult. Often, the equipment has to be taken off-line so the deposits can be physically removed by procedures such as manual chipping or high-pressure water jetting. Theindustry places much effort and incurs great monetary and time costs in the treatment and remediation of dithiazine buildup in process equipment.SUMMARY OF THE DISCLOSURE

[0004] Various aspects of the disclosure are directed to compositions and methods for safely removing foulants from surfaces. In some instances, various aspects of the disclosure are more specifically directed to compositions and methods for safely removing dithiazine-based foulants from surfaces of chemical processing equipment.

[0005] Various non-limiting aspects of the disclosure can be described as follows.

[0006] In some instances, a first aspect of the disclosure can be described as a composition for the removal of dithiazines from chemical processing equipment, where the composition comprises a pyrophosphate salt, a thioether-based nonionic surfactant, an amine oxide surfactant, a foam control agent, and optionally water.

[0007] In some instances, a second aspect of the disclosure can be described as a composition according to the first aspect, where the composition comprises about 15 to about 30 wt% of the pyrophosphate salt, about 20 to about 40 wt% of the thioether-based nonionic surfactant, about 5 to about 15 wt% of the amine oxide surfactant, about 0.01 to about 1.0 wt% of the foam control agent, and about 20 to about 50 wt% water.

[0008] In some instances, a third aspect of the disclosure can be described as a composition according to the first aspect, where the composition comprises about 20 to about 25 wt% of the pyrophosphate salt, about 25 to about 35 wt% of the thioether-based nonionic surfactant, about 7 to about 13 wt% of the amine oxide surfactant, about O.Ol to about 1.0 wt% of the foam control agent, and about 20 to about 50 wt% water.

[0009] In some instances, a fourth aspect of the disclosure can be described as a composition according to the first aspect, where the composition comprises about 30 to about 50 wt% of the pyrophosphate salt, about 30 to about 60 wt% of the thioether-based nonionic surfactant, about 7.5 to about 30 wt% of the amine oxide surfactant, aboutO.Ol to about 1 .0 wt% of the foam control agent, and less than 1 wt% water.

[0010] In some instances, a fifth aspect of the disclosure can be described as a composition according to the first aspect, where the composition comprises about 35 to about 45 wt% of the pyrophosphate salt, about 35 to about 55 wt% of the thioether-based nonionic surfactant, about 10to about25 wt% of the amine oxide surfactant, about 0.01 to about 1 .0 wt% of the foam control agent, and less than 1 wt% water.

[0011] In some instances, a sixth aspect of the disclosure can be described as a composition according to any one of the first through fifth aspects, wherein the pyrophosphate salt is tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, disodium pyrophosphate, tetrapotassium pyrophosphate, or a transition metals pyrophosphate.

[0012] In some instances, a seventh aspect of the disclosure can be described as a composition according to any one of the first through sixth aspects, wherein he thioether-based nonionic surfactant has a structure according to formula (I)R-S-(CH2CH2O-)n-H (I) where R is a Cg-Cis linear or branched alkyl group and n is an integer ranging from 2 to 10.

[0013] In some instances, an eighth aspect of the disclosure can be described as a composition according to any one of the first through seventh aspects, wherein the amine oxide surfactant comprises a Cs-Cis alkyl group.

[0014] In some instances, a ninth aspect of the disclosure can be described as a composition according to any one of the first through eighth aspects, wherein the foam control agent is a silicone-based foam control agent.

[0015] In some instances, a tenth aspect of the disclosure can be described as a method for the removal of dithiazines from chemical processing equipment, where the method comprises circulating a composition according to any one of the first through ninth aspects through internals ofthe chemical processing equipment, solubilizing dithiazines with the composition, and removing the solubilized dithiazines from the chemical processing equipment internals.

[0016] In some instances, an eleventh aspect of the disclosure can be described as a method according to the tenth aspect, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

[0017] In some instances, a twelfth aspect of the disclosure can be described as a method according to the eleventh aspect, wherein the gas is steam.

[0018] In some instances, a thirteenth aspect of the disclosure can be described as a method for the removal of dithiazines from chemical processing equipment, where the method comprises partially or fully filling internals of the chemical processing equipment with a composition according to any one of the first through ninth aspects, solubilizing dithiazines with thecomposition during a soak period, and removing the solubilized dithiazines from the chemical processing equipment internals.

[0019] In some instances, a fourteenth aspect of the disclosure can be described as a method according to the thirteenth aspect, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

[0020] In some instances, a fifteenth aspect of the disclosure can be described as a method according to the fourteenth aspect, wherein the gas is steam.

[0021] In some instances, a sixteenth aspect of the disclosure can be described as a dilute composition for the removal of dithiazines from chemical processing equipment, where dilute composition comprises composition according to any one of the first through ninth aspects, and an aqueous carrier, wherein the dilute composition has a composition-to-aqueous carrier weightweight ratio ranging from 1 :2 to 1 :15.

[0022] In some instances, a seventeenth aspect of the disclosure can be described as a dilute composition according to the sixteenth aspect, wherein the dilute composition has a composition- to-aqueous carrier weightweight ratio ranging from 1 :4 to 1 : 12.5.

[0023] In some instances, an eighteenth aspect of the disclosure can be described as a dilute composition according to the sixteenth aspect, wherein the dilute composition has a composition- to-aqueous carrier weightweight ratio ranging from 1 :5 to 1 :10.

[0024] In some instances, a nineteenth aspect of the disclosure can be described as a method for the removal of dithiazines from chemical processing equipment, where the method comprises circulating a composition accordin to any one of the sixteenth through eighteenth aspects through internals of the chemical processing equipment, solubilizing dithiazines with the composition, and removing the solubilized dithiazines from the chemical processing equipment internals.

[0025] In some instances, twentieth aspect of the disclosure can be described as a method according to the nineteenth aspect, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

[0026] In some instances, a twenty -first aspect of the disclosure can be described as a method according to the twentieth aspect, wherein the gas is steam.

[0027] In some instances, a twenty-second aspect of the disclosure can be described as a method for the removal of dithiazines from chemical processing equipment, where the method comprises partially or fully filling internals of the chemical processing equipment with a compositionaccording to any one of the sixteenth through eighteenth aspects, solubilizing dithiazines with the composition during a soak period, and removing the solubilized dithiazines from the chemical processing equipment internals.

[0028] In some instances, a twenty -third aspect of the disclosure can be described as a method according to the twenty-second aspect, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

[0029] In some instances, a twenty-fourth aspect of the disclosure can be described as a method according to the twenty -third aspect, wherein the gas is steam.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a schematic illustration of an exemplary chemical processing equipment showing injection points and flows, effluent flows, and vent and injection locations of said chemical processing equipment using compositions and methods according to various aspects of the disclosure.DETAILED DESCRIPTION

[0031] The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the subject matter of the present disclosure, their application, or uses.

[0032] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight.

[0033] For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” 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, alternatively ±5 percent, alternatively ±1 percent, alternatively ±0.5 percent, and alternatively ±0.1 percent of the given numeric value provided such a deviation does not alter theend function or result of the value. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.

[0034] It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referencesunless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be nonlimiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items. For example, as used in this specification and the following claims, the terms “comprise” (as well as forms, derivatives, or variations thereof, such as “comprising” and “comprises”), “include” (as well as forms, derivatives, or variations thereof, such as “including” and “includes”) and “has” (as well as forms, derivatives, or variations thereof, such as “having” and “have”) are inclusive (i.e., open-ended) and do not exclude additional elements or steps. Accordingly, these terms are intended to not only cover the recited elements) 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.

[0035] As used herein, the term “chemical processing equipment” means any one or more components of a process or system that is utilized in the retrieval, storage, transfer, or chemical or physical processing of a chemical material or composition, such as for example, tubulars, storage tanks, truck tanks, water disposal wells, reactor vessels, piping, heat exchangers, fire heaters, drums, towers, pumps, combinations thereof, and so on in fields such chemical manufacturing and processing, oil and gas operations and so on.

[0036] Various aspects of the present disclosure are directed to compositions for the solubilization and removal of dithiazines from chemical processing equipment. In some instances, the compositions disclosed herein can be used in chemical processing equipment in a concentrated form. In some instances, the compositions disclosed herein can be diluted in an aqueous carrier and the diluted compositions can be injected into chemical processing equipment. In some instances, the compositions disclosed herein, in concentrated form, and an aqueous carrier can be co-injected into chemical processing equipment at the same time to form a diluted composition inthe chemical processing equipment. Compositions according to various aspects of the disclosure may include various components. In some instances, the compositions may comprise, consist essentially of, or consist of a pyrophosphate salt, a thioether-based nonionic surfactant, an amine oxide surfactant, a foam control agent, and optionally water. In some instances, the foam control agent is a silicone-based foam control agent. As discussed above, such compositions may further be diluted in an aqueous carrier prior to or during injection into chemical processing equipment.

[0037] In some instances, compositions accordingto various aspects of the present disclosure can comprise, consist essentially of, or consist of about 15 to about 30 wt% of a pyrophosphate salt, about 20 to about 40 wt% of a thioether-based nonionic surfactant, about 5 to about 15 w1% of an amine oxide surfactant, 0.01 to about 1 .0 wt% of a foam control agent, and about 20 to about 50 wt% water.

[0038] In some instances, compositions accordingto various aspects of the present disclosure can comprise, consist essentially of, or consist of about 20 to about 25 wt% of a pyrophosphate salt, about 25 to about 35 wt% of a thioether-based nonionic surfactant, about 7 to about 13 wt% of an amine oxide surfactant, about 0.01 to about 1 .0 wt% of a foam control agent, and about 20 to about 50 wt% water.

[0039] Compositions with other varied weight combinations of a pyrophosphate salt, a thioether-based nonionic surfactant, an amine oxide surfactant, a foam control agent, and water can also be prepared in accordance with the teachings of this application.

[0040] In some instances, compositions accordingto various aspects of the present disclosure can comprise, consist essentially of, or consist of about 30 to about 50 wt% of a pyrophosphate salt, about 30 to about 60 wt% of a thioether-based nonionic surfactant, about 7.5 to about 30 wt% of an amine oxide surfactant, about 0.01 to about 1.0 wt% of a foam control agent, and be substantially free of water (i.e., the composition has less than 1 wt% water).

[0041] In some instances, compositions accordingto various aspects of the present disclosure can comprise, consist essentially of, or consist of about 35 to about 45 wt% of a pyrophosphate salt, about 35 to about 55 wt% of a thioether-based nonionic surfactant, about 10 to about 25 wt% of an amine oxide surfactant, about 0.01 to about 1.0 wt% of a foam control agent, and be substantially free of water (i.e., the composition has less than 1 wt% water).

[0042] Compositions with other varied weight combinations of a pyrophosphate salt, a thioether-based nonionic surfactant, an amine oxide surfactant, a foam control agent, andsubstantially free of water (that is, compositions having less than 1 wt% water) can also be prepared in accordance with the teachings of this application.

[0043] In some instances, the compositions disclosed herein can be used, either in concentrated or dilute form, to solubilize and remove dithiazines from chemical processing equipment by continuously or periodically circulating the composition through the chemical processing equipment until the dithiazines are substantially or complete solubilized for subsequent removal from the chemical processing equipment (also referred to as a circulation process). In some instances, the compositions disclosed herein can be used, either in concentrated or dilute form, to solubilize and remove dithiazines from chemical processing equipment by partially or fully filling the chemical processing equipment with the composition and maintaining the composition to within the chemical processing equipment until the dithiazines are substantially or complete solubilized from subsequent removal from the chemical processing equipment (also referred to as a fill-and-soak process). In some instances, a suitable heated gas (such as a nitrogen, argon, air, or steam), can be inj ected into the chemical processing equipment, while the composition is contained therein, at a pressure sufficient to induce cavitation on exposed surfaces of the dithiazine and / or between an interface of dithiazine and chemical processing equipment surfaces to further promote solubilization of the dithiazines.

[0044] As discussed above, compositions according to various aspects of the disclosure include a pyrophosphate salt. Pyrophosphate salts are believed to serve multiple functions in compositions according to various aspects of the disclosure. Suitable pyrophosphate salts include, but are not limited to, tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, disodium pyrophosphate, tetrapotassium pyrophosphate, and transition metals pyrophosphates such as iron (III) pyrophosphate, tin (II) pyrophosphate, copper (II) pyrophosphate, and zinc (II) pyrophosphate. In some instances, the use of tetrapotassium pyrophosphate is preferred. In some instances, the amount of pyrophosphate salt in compositions according to various aspects of the disclosure can range from about 15 to about 50 wt% of the composition. In some instances the compositions according to various aspects of the disclosure can include water and the amount of amount of pyrophosphate salt in such compositions can range from about 15 to about 30 wt%, alternatively from about 17.5 to about 27.5 wt%, alternatively from about 20 to about 25 wt%, and alternatively from about 22 to about 24 wt% of the composition. In some instances, compositions according to various aspects of the disclosure can be water-free or substantially water-free (i.e.,the composition has less than 1 wt% water) and the amount of amount of pyrophosphate salt in such compositions can range from about 30 to about 50 wt%, alternatively from about 32.5 to about 45 wt%, alternatively from about 35 to about 45 wt%, alternatively from about 35 to about 42.5 wt%, and alternatively from about 37.5 to about 40 wt% of the composition.

[0045] As discussed above, compositions according to various aspects of the disclosure include a thioether-based nonionic surfactant. In some instances, suitable thioether-based nonionic surfactants are those according to formula (I):R-S-(CH2CH2O-)n-H (I) where R is a C8-Ci8linear or branched alkyl group and n is an integer ranging from 2 to 10. In some instances, R is a C9-Ci6linear or branched alkyl group. In some instances, R is a Ci0-Ci6linear or branched alkyl group. In some instances, R is a C10-C14 linear or branched alkyl group. In some instances, n is an integer ranging from 2 to 8. In some instances, n is an integer ranging from 2 to 6. In some instances, n is an integer ranging from 4 to 10. In some instances, n is an integer ranging from 6 to 10. In some instances, Ris a C9-Ci2linear or branched alkyl group and n is 2, 4, 6, 8 or 10. In some instances, the use of2-[2-(9,9-Dimethyldecylsulfanyl)ethoxy]ethanol as the thioether-based nonionic surfactant is preferred. In some instances, the amount of thioether- based nonionic surfactant in compositions according to various aspects of the disclosure can range from about 20 to about 60 wt% of the composition. In some instances the compositions according to various aspects of the disclosure can include water and the amount of amount of thioether-based nonionic surfactant in such compositions can range from about 20 to about 40 wt%, alternatively from about 22.5 to about 37.5 wt%, alternatively from about 25 to about 35 wt%, alternatively from about 25 to about 30 wt%, and alternatively from about 26 to about 28 wt% of the composition. In some instances, compositions according to various aspects of the disclosure can be water-free or substantially water-free (i.e., the composition has less than 1 wt% water) and the amount of amount of thioether-based nonionic surfactant in such compositions can range from about 30 to about 60 wt%, alternatively from about 32.5 to about 57.5 wt%, alternatively from about 35 to about 55 wt%, alternatively from about 37.5 to about 52.5 wt%, alternatively from about40 to about 50 wt%, and alternatively from about42.5 to about47.5 wt% of the composition.

[0046] As discussed above, compositions according to various aspects of the disclosure include an amine oxide surfactant. In some instances, the amine oxide surfactant comprises a C8-Ci8alkyl group. In some instances, the amine oxide surfactant is a C8-Ci8alkyl dimethyl amine oxide. Insome instances, the amine oxide surfactant comprises a C10-C16 alkyl group. In some instances, the amine oxide surfactant is a Ci0-Ci6alkyl dimethyl amine oxide. Suitable amine oxide surfactants include, but are not limited to, lauryldimethylamine N-oxide (LDAO), myristyldimethylamine N-oxide (TDAO), and N,N-dimethyldecan-l -amine oxide (DDAO). In some instances, the use of LDAO is preferred. In some instances, the amount of amine oxide surfactant in compositions according to various aspects of the disclosure can range from about 5 to about 30 wt% of the composition. In some instances, the compositions accordingto various aspects of the disclosure can include water and the amount of amine oxide surfactant in such compositions can range from about 5 to about 15 wt%, alternatively from about 6 to about 14 wt%, alternatively from about 7 to about 13 wt%, alternatively from about 8 to about 12 wt%, alternatively from about 9 to about 11 wt%, and alternatively about 10 wt% of the composition. In some instances, compositions according to various aspects of the disclosure can be water-free or substantially water-free (i.e., the composition has less than 1 wt% water) and the amount of amine oxide surfactant in such compositions can range from about 7.5 to about 30 wt%, alternatively from about 10 to about 25 wt%, alternatively from about 12.5 to about 22.5 wt%, alternatively from about 15 to about 20 wt%, alternatively from about 16 to about 18 wt%, and alternatively from 17 wt% of the composition.

[0047] As discussed above, compositions accordingto various aspects of the disclosure include a foam control agent. In some instances, the foam control agent is a silicone-based foam control agent. In some instances, the foam control agent is a silicone polyether. In some instances, the amount of foam control agent in compositions accordingto various aspects of the disclosure can range from about 0.01 to about 1 .0 wt% of the composition. In some instances, the amount of foam control agent in compositions accordingto various aspects of the disclosure can range from about 0.025 to about 0.75 wt%, alternatively from about 0.05 to about 0.5 wt%, alternatively from about 0.075 to about 0.25 wt%, and alternatively from about 0.075 to about 0.125 wt% of the composition.

[0048] In some instances, compositions accordingto various aspects of the disclosure can be water-free or substantially water-free (thatis, compositions having less than 1 wt% water). In some instances, compositions accordingto various aspects of the disclosure can further include water. In some instances, compositions accordin to various aspects of the disclosure can include waterin amounts ranging from about 20 to about 50 wt%, alternatively from about 30 to about 45 wt%, alternatively from about 35 to about 42.5 wt%, and alternatively about 40 wt% of the composition.

[0049] In some instances, compositions according to the disclosure can include one or more water soluble organic solvents. Suitable water soluble organic solvents include, but are not limited to C1-C12 linear or branched alcohols or diols (for example, ethanol, octanol isopropanol, 1,5- propanediol and 1,4-butanediol), aliphatic and aromatic heterocycles (for example, 1,4-di oxane, pyridine, tetrahydrofuran), ketones (for example acetone), amides (for example, dimethylformamide and N-methyl pyrrolidone), amines (for example, ethylamine, propylamine, diethanolamine, and methylethanolamine), nitriles (for example, acetonitrile) and dimethlysulfoxide. Compositions according to the disclosure can include one or more water soluble organic solvents when the compositions water-free or substantially water-free (i.e., the composition has less than 1 wt% water). Alternatively, the one or more soluble organic solvents can be used in compositions comprising water.

[0050] In some instances, compositions according to the disclosure can further include one or more water soluble surfactants other than an amine oxide surfactant. Suitable water soluble surfactants can include some non-ionic surfactants and some ionic surfactants. In some instances, suitable ionic surfactants include an anionic head group such as a sulfate, and sulfonate, a phosphate, or a carbonate. In some instances, suitable ionic surfactants include a cationic head group such as an ammonium, a pyridinium, ora phosphonium. In some instances, suitable ionic surfactants include a zwitterionic head group.

[0051] In some instances, the compositions described above can be used as-is (i.e., in concentrated form with a water component, as described above, or free or substantially free of water) for the removal of foulants, such as dithiazines, from surfaces of chemical processing equipment. In some instances, the compositions described above can be usedin a diluted form for the removal of foulants, such as dithiazines, from surfaces of chemical processing equipment. As such, various aspects of the disclosure are also directed to diluted compositions comprising a composition as described herein dissolved, dispersed, or otherwise incorporated into an aqueous carrier. As discussed previously dilute compositions can be prepared prior to or during injection into chemical processing equipment In some instances, the dilute compositions can have a composition-to-aqueous carrier weightweight ratio ranging from about 100: 1 to about 1 :100, alternatively from about 90: 1 to about 1 :90, alternatively from about 80: 1 to about 1 :80,alternatively from about 70:1 to about 1 :70, alternatively from about 60: 1 to about 1 :60, alternatively from about 50:1 to about 1 :50, alternatively from about 40: 1 to about 1 :40, alternatively from about 30:1 to about 1 :30, alternatively from about 20: 1 to about 1 :20, alternatively from about 15:1 to about 1 : 15, alternatively from about 10: 1 to about 1 :10, alternatively from about 9:1 to about 1 :9, alternatively from about 8:1 to about 1 :8, alternatively from about 7: 1 to about 1 :7, alternatively from about 6 : 1 to about 1 :6, alternatively from about 5:1 to about 1 :5, alternatively from about 4:1 to about 1 :4, alternatively from about 3: 1 to about 1 :3, alternatively from about 2: 1 to about 1 :2, and alternatively from about 1.5:1 to about 1 : 1.5. In some instances, the dilute compositions preferably have a composition-to-aqueous carrier weightweight ratio ranging from 1 :2 to 1 :15, alternatively from 1 :4 to 1 :12.5, and alternatively from about 1.5 to about 1 :10.

[0052] In some instances, the aqueous carrier is water. Suitable forms of water for use as the aqueous carrier include, but are necessarily limited to, groundwater, reclaimed water, purified water, distilled water, and deionized water. In some instances, the aqueous carrier comprises water and at least one water soluble co-solvent. In some instances, the aqueous carrier comprises at least about 95 wt% water and less than about 5 wt% of the at least one water soluble co-solvent. In some instances, the aqueous carrier comprises at least about 90 wt% water and less than about 10 wt% of the at least one water soluble co-solvent. In some instances, the aqueous carrier comprises at least about 85 wt% water and less than about 15 wt% of the at least one water soluble co-solvent In some instances, the aqueous carrier comprises at least about 80 wt% water and less than about 20 wt% of the at least one water soluble co-solvent.

[0053] Methodologies for the solubilization and removal of dithiazines from chemical processing equipment, using compositions according to various aspects of the disclosure, can be varied based multiple factors including, but not limited to, the chemical processing equipment to be treated, the amount of dithiazine foul ant present in the chemical processing equipment, and so on. In circulation processes, where the composition (whether in a concentrated or a dilute form) is circulated through chemical processing equipment, various parameters including, but not limited to, composition temperature, circulation pressure, circulation time, amount, and / or duration of gasinjection induced cavitation, number of circulation and / or cavitation cycles, number and location of gas and / or composition injection points (into the chemical processing equipment), and so on, can be varied to optimize the efficiency of the solubilization and removal of dithiazines. In fill -and-soak processes, where the composition (whether in a concentrated or a dilute form,) is allowed to reside in chemical processing equipment for a period of time, various parameters including but not limited to, composition temperature, residence time, amount and / or duration of gas-injection induced cavitation during composition residency, number of cavitation cycles, and so on can be varied to optimize the efficiency of the solubilization and removal of dithiazines.

[0054] In accordance with various aspect of the disclosure, exemplary methods for solubilizing and removing dithiazines from chemical processing equipment using compositions described herein may be performed according to the following steps. One or more of the steps described below may be omitted or modified, alternative steps may be added, based upon factors described above the chemical processing equipment to be treated, the amount of dithiazine foulant present in the chemical processing equipment, the type of treatment process used (circulation vs. fill-and- soak) and so on.

[0055] In a first step, the chemical processing equipment is prepared for treatment. Temporary gas (such as a nitrogen, argon, air, or steam) supplies with chemical injection tees are installed for heat up. Drains are connected to a drain system and prepared for use. Chemical injection hoses are connected and prepared for use. Temporary manifolds are installed.

[0056] In a second step, valve isolations are completed prior to heated gas (e.g., nitrogen, argon, air, or steam) injection.

[0057] In a third step, a composition according to various aspects of the present disclosure is introduced into the chemical processing equipment until a desired fill level (for example 70-100%) is established.

[0058] In a fourth step, the gas is introduced at designated injection locations and allowed the chemical / water solution to “rumble” (that is, cavitate) as the steam collapses upon entry into the solution.

[0059] In an optional fifth step, the gas injection point can be relocated to another portion of the chemical processing equipment to address different foulant-containing locations within the chemical processing equipment.

[0060] In a sixth step, steps 4 and 5 can be continued until the temperature of the solution is such that the steam is no longer collapsing and producing a rumble i.e., no more indicators of cavitation are observed).

[0061] In an optional seventh step, the solution is allowed is allowed to reside in the internals of the chemical processing equipment. This “soak” step can be performed at temperatures varying from ambient temperature to the boiling point of the solution (in some instances, a 40-70°C solution temperature during the soak step is preferred) and any suitable period of time.

[0062] In an eighth step, the contents of the chemical processing equipment are drained and the contents are evaluated. Optionally, steps 3-6 canbe repeated to continue to rumble (and optionally soak step 7) the chemical processing equipment.

[0063] In a ninth step, step 8 (and thus, steps 3-6 or steps 3-7) can be repeated one or more times.

[0064] In a tenth step, low point drains and / or vents are opened.

[0065] In an eleventh step, gas (e.g., heated nitrogen, argon, air, or steam) injection is initiated at one or more designated locations along a normal process flowpath of the chemical processing equipment.

[0066] In a twelfth step, low point drains and vents are monitored for indications of gas penetration and breakthrough.

[0067] In a thirteenth step, once gas breakthrough is observed at all low point drains and vents, flow through vents and drains is reduced to increase pressure / temperature across the chemical processing equipment.

[0068] In a fourteenth step, after internals of the chemical processing equipment have reached and sustained a desired temperature, a composition accordingto various aspects of the disclosure is injected into the chemical processing equipment via a temporary gas / composition manifold.

[0069] In a fifteenth step, which occurs in conjunction with the fourteenth step, low point drains and vents are monitored for gas breakthrough.

[0070] In a sixteenth step, once injection of the composition is complete, composition injection is terminated and gas injection is continued through the chemical processing equipment. Monitoring of gas breakthrough to drains / vents is monitored to ensure it is visible and constant.

[0071] In a seventeenth step, gas (e.g., heated nitrogen, argon, air, or steam) injection is conducted at one or more designated locations along a reverse flow path relative to the normal process flowpath of the chemical processing equipment.

[0072] In an eighteenth step, low point drains and vents are monitored for indications of gas penetration and breakthrough.

[0073] In a nineteenth step, once gas breakthrough is observed at all low point drains and vents, flow through vents and drains is reduced to increase pressure / temperature across the chemical processing equipment.

[0074] In a twentieth step, after internals of the chemical processing equipment have reached and sustained a desired temperature, a composition according to various aspects of the disclosure is injected into the chemical processing equipment via a temporary gas / composition manifold.

[0075] In a twenty -first step, which occurs in conjunction with the twentieth step, low point drains and vents are monitored for gas breakthrough.

[0076] In a twenty-second step, once injection of the composition is complete, composition injection is terminated and gas injection is continued through the chemical processing equipment. Monitoring of gas breakthrough to drains / vents is monitored to ensure it is visible and constant.

[0077] In a twenty-third step, gas injection is terminated.

[0078] In a twenty-fourth step, low point drains and / or vents are opened.

[0079] In a twenty -fifth step, the chemical processing equipment is modified (by, for example removing spools and / or blinds) to access internals.

[0080] In a twenty-sixth step, internals of the chemical processing equipment are rinsed with water and the turbidity of the water rinse is monitored at low point drains.

[0081] FIG. 1 is a schematic illustration of an exemplary chemical processing equipment showing injection points and flows, effluent flows, and vent and injection locations of said chemical processingequipment. As indicated elsewhere herein, however, compositions according to various aspects of the present disclosure can be used to remove dithiazines in any form of chemical processing equipment.

[0082] Although the present invention and its objects, features and advantages have been described in detail, other embodiments are encompassed by the invention. All references cited herein are incorporate by reference in their entireties. Finally, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A composition for the removal of dithiazines from chemical processing equipment, the composition comprising: a pyrophosphate salt; a thioether-based nonionic surfactant; an amine oxide surfactant; a foam control agent; and optionally water.

2. The composition of claim 1, wherein the composition comprises: about 15 to about 30 wt% of the pyrophosphate salt; about 20 to about 40 wt% of the thioether-based nonionic surfactant; about 5 to about 15 wt% of the amine oxide surfactant; about 0.01 to about 1.0 wt% of the foam control agent; and about 20 to about 50 wt% water.

3. The composition of claim 1, wherein the composition comprises: about 20 to about 25 wt% of the pyrophosphate salt; about 25 to about 35 wt% of the thioether-based nonionic surfactant; about 7 to about 13 wt% of the amine oxide surfactant; about 0.01 to about 1.0 wt% of the foam control agent; and about 20 to about 50 wt% water.

4. The composition of claim 1, wherein the composition comprises: about 30 to about 50 wt% of the pyrophosphate salt; about 30 to about 60 wt% of the thioether-based nonionic surfactant; about 7.5 to about 30 wt% of the amine oxide surfactant; about 0.01 to about 1.0 wt% of the foam control agent; and less than 1 wt% water.

5. The composition of claim 1 , wherein the composition comprises: about 35 to about 45 wt% of the pyrophosphate salt; about 35 to about 55 wt% of the thioether-based nonionic surfactant; about 10 to about 25 wt% of the amine oxide surfactant; about 0.01 to about 1.0 wt% of the foam control agent; and less than 1 wt% water.

6. The composition of any one of claims 1 to 5, wherein the pyrophosphate salt is tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, disodium pyrophosphate, tetrapotassium pyrophosphate, or a transition metals pyrophosphate.

7. The composition of any one of claims 1 to 6, wherein the thioether-based nonionic surfactant has a structure according to formula (I)R-S-(CH2CH2O-)n-H (I) where R is a C8-Ci8linear or branched alkyl group and n is an integer ranging from 2 to 10.

8. The composition of any one of claims 1 to 7, wherein the amine oxide surfactant comprises a C8-Ci8alkyl group.

9. The composition of any one of claims 1 to 8, wherein the foam control agent is a silicone-based foam control agent.

10. A dilute composition for the removal of dithiazines from chemical processing equipment, the dilute composition comprising: a composition according to any one of claims 1 to 9; and an aqueous carrier, wherein the dilute composition has a composition-to-aqueous carrier weightweight ratio ranging from 1 :2 to 1 : 15.

11. The dilute composition of claim 10, wherein the dilute composition has a composition-to- aqueous carrier weightweight ratio ranging from 1 :4 to 1 : 12.5.

12. The dilute composition of claim 10, wherein the dilute composition has a composition-to- aqueous carrier weightweight ratio ranging from 1 :5 to 1 :10.

13. A method for the removal of dithiazines from chemical processing equipment, the method comprising: circulating a composition according to any one of claims 1 to 12 through internals of the chemical processing equipment; solubilizing dithiazines with the composition; and removing the solubilized dithiazines from the chemical processing equipment internals.

14. The method of claim 13, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

15. The method of claim 14, wherein the gas is steam.

16. A method for the removal of dithiazines from chemical processing equipment, the method comprising: partially or fully filling internals of the chemical processing equipment with a composition according to any one of claims 1 to 12; solubilizing dithiazines with the composition during a soak period; and removing the solubilized dithiazines from the chemical processing equipment internals.

17. The method of claim 16, further comprising injecting a gas into the chemical processing equipment internals in the presence of the composition.

18. The method of claim 17, wherein the gas is steam.

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