Systems and methods for reclaiming monoethylene glycol (MEG)

Abstract

A process for monoethylene glycol (MEG) recovery including feeding a MEG rich stream having water, dissolved monovalent salts, and MEG into a flash separator, where the flash separator is configured to at least partially separate the monovalent salts from the MEG in the MEG rich stream. The process also includes obtaining an overhead stream from the flash separator, where the overhead stream has a first portion of the MEG rich stream, obtaining a bottoms stream from the flash separator, where the bottoms stream has a second portion of the MEG rich stream; and feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream. The process further includes obtaining a processed MEG stream from the distillation column, and directing the processed MEG stream to a polyethylene terephthalate (PET) polymerization system to generate PET polymers and plastic.

Description

SYSTEMS AND METHODS FOR RECLAIMING MONOETHYLENE GLYCOL (MEG)CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is a U.S. Non-Provisional Patent Application claiming benefit ofU.S. Provisional Patent Application No. 63 / 674,120, entitled “AMETHOD FOR RECLAIMING MONOETHYLENE GLYCOL (MEG)”, filed July 22, 2024, which is herein incorporated by reference.BACKGROUND

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0003] In the oil and gas field, ice like solids, also called gas hydrate crystals, may form within various components during drilling, completion, production, separation, and other stages of an oil and gas system. These gas hydrate crystals may form when water (H2O) traps hydrocarbons (e.g., methane, ethane, propane, natural gases, oil, etc.) under specific conditions (e.g., temperature and pressure conditions). Gas hydrate crystal formation is a concern in the field, resulting in pipeline blockage, operational downtime, and various risks. To mitigate formation of gas hydrate crystals, thermodynamic inhibitors such as monoethylene glycol (MEG), commonly referred to as glycol, are applied to lower the hydrate formation temperature. Proportional to large volumes of produced fluid, large volumes of MEG are required for gas hydrates inhibition processes. Therefore, MEG is typically regenerated and reused in a MEG recovery system to reduce the need to continuously add fresh chemicals into the feed.

[0004] MEG can be reclaimed or recycled from numerous industrial processes, including from the depolymerization of polyesters or polyester-containing streams. The depolymerization stream of polyesters such as polyethylene terephthalate (PET) maycomprise impurities such as derivatives of other units of the depolymerized polymer, such as terephthalic acid (TA) or salts thereof, and / or heavy impurities, which may affect the purity of the reclaimed MEG. Therefore, there is a need to improve the system and method of reclaiming MEG from industrial streams containing PET.SUMMARY

[0005] A summary of certain embodiments disclosed herein is set forth below. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0006] In an embodiment, a process for monoethylene glycol (MEG) recovery includes feeding a MEG rich stream having water, monovalent salts, and MEG into a flash separator, where the flash separator is configured to at least partially separate the monovalent salts from the MEG in the MEG rich stream. The process also includes obtaining an overhead stream from the flash separator, where the overhead stream has a first portion of the MEG rich stream, obtaining a bottoms stream from the flash separator, where the bottoms stream has a second portion of the MEG rich stream; and feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream. The process further includes obtaining a processed MEG stream from the distillation column, where the processed MEG has more than 80 weight % of MEG, and directing the processed MEG stream to a polyethylene terephthalate (PET) system to generate PET polymers and / or plastic .

[0007] In another embodiment, a system for monoethylene glycol (MEG) recovery includes a flash separator configured to receive a MEG rich stream, where the flash separator is configured to separate the MEG rich stream into an overhead stream and a bottoms stream. The system also includes a distillation column configured to receive the overhead stream from the flash separator, where the distillation column is configured to separate the overhead stream into a processed MEG stream and a second overhead stream,and a polyethylene terephthalate (PET) polymerization system configured to generate PET plastics and configured to receive the processed MEG stream.

[0008] In a further embodiment, a process for monoethylene glycol (MEG) recovery includes feeding a MEG rich stream having water, dissolved monovalent salts, and MEG a flash separator, where the flash separator is configured to at least partially separate the monovalent salts from MEG in the MEG rich stream. The process also includes obtaining an overhead stream from the flash separator, obtaining a bottoms stream from the flash separator, feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream, and obtaining a processed MEG stream from the distillation column, where the processed MEG has more than 80 weight % of MEG. The process further includes directing the processed MEG stream to a polyethylene terephthalate (PET) polymerization system, and feeding the bottoms stream from the flash separator into a solids removal system, where the solids removal system is configured to at least partially separate the dissolved salts from the bottoms stream.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

[0010] FIG. 1 is a schematic illustration of an embodiment of a monoethylene glycol (MEG) system, in accordance with an aspect of the present disclosure; and

[0011] FIG. 2 is method for monoethylene glycol (MEG) recovery, in accordance with an aspect of the present disclosure.DETAILED DESCRIPTION

[0012] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be madeto achieve the developers’ specific goals, such as compliance with system -related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0013] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0014] As used herein, the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element”. Further, the terms “couple”, “coupling”, “coupled”, “coupled together”, and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms "up" and "down"; "upper" and "lower"; "top" and "bottom"; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point at the surface from which drilling operations are initiated as being the top point and the total depth being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface.

[0015] As mentioned above, in the oil and gas field, gas hydrate crystals may form within various components (e.g., pipelines, wellheads, processing components, transportation components) during drilling, completion, production, separation, transportation, and / or other stages of an oil and gas system. Gas hydrate crystals may form when water (H2O) traps hydrocarbons (e.g., methane, ethane, propane, natural gases, oil, formation fluid, etc.) under specific conditions, such as relatively low temperatures (e.g., less than 25°C) and / or relatively high pressures. Gas hydrate crystal formation results inice like solids, resulting in pipeline blockage, operational downtime, and various risks. To mitigate formation of gas hydrate crystals, thermodynamic inhibitors such as monoethylene glycol (MEG), commonly referred to as glycol, are applied to lower the hydrate formation temperature. In this way, gas hydrate crystals may be reduced within the various components of an oil and gas system. Proportional to large volumes of produced fluid, large volumes of MEG may be utilized for the gas hydrates inhibition processes. Therefore, MEG is regenerated and reused in a MEG recovery system to reduce the need to continuously add fresh chemicals into the feed.

[0016] MEG can be reclaimed or recycled from numerous industrial processes, including from the depolymerization of polyesters or polyester-containing streams. The depolymerization stream of polyesters such as polyethylene terephthalate (PET) may comprise impurities as a byproduct of the reaction, such as derivatives of other units of the depolymerized polymer, such as terephthalic acid (TA) or salts thereof, and / or heavy impurities, which may affect the purity of the reclaimed MEG. Therefore, there is a need to improve the system and method of reclaiming MEG from industrial streams containing PET.

[0017] As such, embodiments of the present disclosure are related to an improved system and method for reclaiming monoethylene glycol (MEG) from an industrial stream. For example, a MEG recovery system may be configured to receive a MEG rich stream (e.g., an industrial stream) including MEG, water, and in some instances, various impurities. The MEG rich stream may be sourced as a product of a depolymerization process and / or spent or used MEG previously used for gas hydrate crystal inhibition (e.g., within an oil and gas system). In any case, the MEG rich stream may include a purity of MEG that may not be suitable for further use in gas hydrate crystal inhibition and may therefore be processed by the MEG recovery system to increase a purity of MEG and remove water and impurities. As a result or byproduct to the depolymerization process, TA salts may be present in the MEG rich stream, resulting in a lower MEG purity and in some instances, fouling of one or more components of the MEG recovery system. As such, the MEG recovery system may be configured to remove at least a portion of the TA present in the MEG rich stream to improve MEG purity and reduce damage to components. TheMEG recovery system may include a flash separator configured to separate certain impurities (e.g., TA salt) from MEG in the MEG rich stream. For further processing, the MEG processed (e.g., overhead stream or flow) within the flash separator may be directed into one or more distillation columns to separate water from MEG, improving the purity of MEG to a desired purity. Before separation within the flash separator, after separation with the flash separator (and before separation in the one or more distillation columns), and / or after separation within the one or more distillation columns, one or more solids removal systems (e.g., salt management sections) disposed within the MEG recovery system may be operable to remove TA salt and other impurities from the process streams of the MEG recovery system, improving MEG purity and reducing degradation of the components of the MEG recovery system. As will be appreciated, removal of TA salts (e.g., divalent salt) may be different, and in some instances, more complicated than removal of monovalent salts within the MEG recovery system. As such, present embodiments are aimed at facilitating removal of TA salts using the flash separator.

[0018] To further illustrate, FIG. l is a schematic of an embodiment of a monoethylene glycol (MEG) recovery system 10, in accordance with one or more aspects of the present disclosure. FIG. 2 illustrates a process 14 related to the MEG recovery system 10 of FIG. 1. To facilitate discussion, FIGS. 1 and 2 will be discussed below concurrently. It should be noted that the process 14 is not limiting, and the MEG recovery system 10 and / or the process 14 may include additional or fewer steps than those illustrated. Further, the MEG recovery system 10 and / or process 14 may include steps that are performed in an alternative order to that illustrated in process 14. That is, certain steps may be performed before, after, or concurrently to / with another respective step. Moreover, the MEG recovery system 10 may include additional or fewer components than those illustrated. Although certain conduits are described as extending between certain components of the MEG recovery system 10, it will be appreciated any conduits described below may extend between other components that may not be explicitly discussed. Further, in some embodiments, conduits discussed below as extending between two components of the MEG recovery system 10 may extend directly between the two or more components of the MEG recovery system 10.

[0019] As discussed above, MEG or monoethylene glycol (e.g., ethane-l,2-diol, C2 LO) may be used as a hydrate inhibitor to reduce or prevent formation of gas hydrate crystals within components of an oil and gas system. For example, MEG may be pumped or otherwise inserted into components of an oil and gas system to lower the hydrate formation temperature, creating undesirable formation conditions for gas hydrate crystals. Due to the large amounts of fluids (e.g., hydrocarbon fluids) typically within the oil and gas system, a proportionally large amount of MEG may be needed to sufficiently block formation of gas hydrate crystals. To reduce costs associated with the relatively large amount of MEG used, recovery (e.g., recycling, regeneration) of MEG may be desirable after use within the oil and gas system.

[0020] In some embodiments, MEG may be separately produced during depolymerization of polymers into monomers. For example, polyethylene terephthalate (PET) may be depolymerized into monomers of MEG and other impurities, such as terephthalic acid (TA, TPA, sodium terephthalic salts), and / or other salts. Depolymerization of PET may be accomplished through hydrolysis, methanolysis, glycolysis, and / or another suitable method. As described above, it may be desirable to recover or separate MEG from monovalent and divalent salts to recycle MEG back into the oil and gas system. Additionally, it may be desirable to reduce salt concentration within the MEG recovery system 10 to increase performance of components of the MEG recovery system 10, such as by reducing fouling, acidity, and so forth, reducing component degradation, decreasing down time due to work over events (e.g., maintenance), and generally increasing the efficiency of the MEG recovery system 10.

[0021] To this end, an MEG rich stream 100 (e.g., an industrial stream) may be directed into the MEG recovery system 10 via a MEG rich stream conduit 104. The MEG rich stream 100 may be sourced from a MEG source 101, such as the oil and gas system (e g., after pumping the MEG into the components of the oil and gas system) and / or from a depolymerization system. As such, the MEG rich stream 100 may include MEG, water, and other solubles, contaminants, or impurities, such as TA or TA salt derivatives. For example, the MEG rich stream 100 may include a TA volume percentage in the range of 0% and 2%, and more typically 0.01% and 0.1%.

[0022] As will be appreciated, a MEG rich stream 100 sourced from a depolymerization system may include a first monovalent salt concentration and a first divalent salt concentration, and a MEG rich stream 100 sourced from the oil and gas system may include a second monovalent salt concentration and a second divalent salt concentration, and the first monovalent salt concentration may be greater than the second monovalent salt concentration and the first divalent salt concentration may be less than the second divalent salt concentration. By directing the MEG rich stream 100 from the MEG source 101 that is the depolymerization system (e.g., including a relatively lower divalent salt concentration compared to a MEG stream sourced from an oil and gas system), one or more components of the MEG recovery system 10 may not be included. For example, one or more additional salt (e.g., divalent salt) removal systems upstream of a flash separator 108 may not be included, reducing component costs, maintenance costs, and energy consumption of the MEG recovery system 10. Additionally, by directing the MEG rich stream 100 from the MEG source 101 that is the depolymerization system, the MEG recovery system 10 may experience reduced degradation (e.g., fouling) due to high concentrations of divalent salts.

[0023] In an embodiment, the MEG rich stream 100 may be directed into a dye removal system 102 configured to remove at least a portion of dye within the MEG rich stream 100. For example, the dye removal system 102 may be configured to remove the portion of dye within the MEG rich stream 100 through solvent extraction, adsorption, precipitation and filtration, dialysis, chemical degradation, and so forth.

[0024] At block 106 (FIG. 2), the MEG rich stream 100 may be directed (e.g., via the MEG rich stream conduit 104) towards, fed, or otherwise provided into the flash separator 108 (e.g., brine column, flash separator) to separate MEG from one or more impurities, such as TA salts. In an embodiment, the MEG rich stream conduit 104 may be directed into an upper portion of the flash separator 108. In an embodiment, the MEG rich stream conduit 104 may be directed at ambient temperature into the flash separator 108. The flash separator 108 may be operated at atmospheric pressure; however, operation at sub- atmospheric pressure may help reduce the temperature suitable for evaporation and substantially reduce or prevent MEG degradation caused by high temperatures (e.g.,temperatures equal to or greater than 165°C at atmospheric pressure). Thermal energy may be provided to the MEG rich stream 100 and / or the flash separator 108 via a recycle loop 112. The recycle loop 112 may include a heat exchanger 116 and a recycle loop pump 120 disposed on a recycle loop conduit 124. The recycle loop conduit 124 may extend between the flash separator 108 and the MEG rich stream conduit 104 to add thermal energy to the MEG rich stream 100. The heat exchanger 116 may be any suitable heat exchanger, which may indirectly transfer heat from another heated working fluid to the MEG rich stream 100. In some embodiments, the heat exchanger 116 may include a heater and / or a heat source, such as a reboiler. In an embodiment, at least a portion of the thermal energy provided to the MEG rich stream 100 and / or the flash separator 108 may be provided from one or more distillation columns 154 downstream of the flash separator 108, relative to the flow of the MEG rich streams. In any case, the thermal energy provided to the MEG rich stream 100 and / or the flash separator 108 may be minimal, to reduce fouling. In an embodiment, the MEG rich stream 100 may include 5-90+ weight % (wt%) MEG, 2-95 wt% water, and 0.1-15 wt% dissolved salts (e.g., NaCl, Na2SO4, Na2TA and other TA salts).

[0025] In an embodiment, the flash separator 108 may include one or more conductivity probes 110. The conductivity probes 110 may be configured to measure electrical conductivity of a solution (e.g., the MEG rich stream 100) within the flash separator 108. As will be appreciated, conductivity of the solution within the flash separator 108 may depend on or may be at least partially based on a salt concentration within the solution. As the concentration changes during separation within the flash separator 108, the conductivity may change (e.g., change in real-time). The conductivity of the solution may be used to determine a concentration (e.g., salt concentration) in a separated stream of the flash separator 108 (e.g., a bottoms stream 132). In some embodiments, the conductivity measured within the flash separator 108 may be used to control one or more aspects of the MEG recovery system 10, such as control parameters of the flash separator 108 (e.g., optimization parameters), maintenance controls, flow rates, etc.

[0026] In an embodiment, the flash separator 108 may be configured to separate TA and / or TA salt derivatives from the MEG and other compositions within the MEG richstream 100. For example, TA and / or TA salt derivatives may precipitate or otherwise separate from other components within the MEG rich stream 100, and may be directed from the flash separator 108 for further processing as a TA stream 111. In an embodiment, the TA stream 111 may be directed back to the PET depolymerization system. For example, the TA stream 111 may be discharged from the recycle loop 112 of the flash separator 108 and directed to the PET depolymerization system.

[0027] The flash separator 108 may separate the MEG rich stream 100 into a MEG rich stream 128 (e.g., overhead stream, gaseous stream, high-purity MEG stream) and the bottoms stream 132 (e.g., dissolved salts stream, suspended salts stream, contaminant stream). For example, salts and other impurities within the MEG rich stream 100 may be precipitated and settled by gravity at the bottom of the flash separator 108. The MEG rich stream 128 may be directed away from the flash separator 108 via a MEG rich stream conduit 136 and the bottoms stream 132 may be directed away from the flash separator 108 via a bottoms stream conduit 140. Referring now to blocks 144 and 146 (FIG. 2), the MEG rich stream 128 may be directed towards, fed, or otherwise provided into a distillation column 154 and the bottoms stream 132 may be directed towards, fed, or otherwise provided into a solids removal system 1 8 (e.g., salt removal system, salt management section), respectively. As such, the MEG rich stream conduit 136 may extend between the flash separator 108 and the distillation column 154 and the bottoms stream conduit 140 may extend between the flash separator 108 and the solids removal system 158. As will be appreciated, the steps indicated in blocks 144 and 146 may occur simultaneously. The bottoms stream conduit 140 may include a pump 160 disposed thereon and configured to facilitate flow from the flash separator 108 to the solids removal system 158.

[0028] In an embodiment, the solids removal system 158 may comprise a cyclonic separator (e.g., a centrifuge, hydrocyclone), decanter, settling tank, or another component configured to concentrate and separate relatively heavy salts particles from liquid MEG. In an embodiment, the solids removal system 158 may be configured to reduce the temperature of the bottoms stream 132 and / or neutralize salts within the bottoms stream 132. In an embodiment, the solids removal system 158 may include one or more filtration components (e.g., mesh films, screens, etc.) to further aid or facilitate salt separation. Aswill be appreciated, the removal of salt (e.g., monovalent salts and TA salts, precipitated salts) may substantially decrease MEG degradation and losses, equipment fouling, and corrosion of system components. In some embodiments, the bottoms stream 132 is directed towards a solids tank to facilitate precipitation of salts before direction into the solids removal system 158.

[0029] The solids removal system 158 may separate the bottoms stream 132 into a bottoms MEG stream 162 and a salt stream 166 (e.g., solid salt stream, salt slurry stream). The salt stream 166 may be directed away from the solids removal system 158 via a salt stream conduit 170 for disposal and / or further processing. The bottoms MEG stream 162 may be directed away from the solids removal system 158 via a bottoms MEG stream conduit 174. In an embodiment, the bottoms MEG stream conduit 174 may extend between an outlet of the solids removal system 158 and an inlet of the flash separator 108, such that the bottoms MEG stream 162 may be recycled back into the flash separator 108 for further separation of impurities and / or salt.

[0030] Referring back to block 144 (FIG. 2), the MEG rich stream 128 may be directed or fed into the distillation column 154 (e.g., refluxed distillation column) via the MEG rich stream conduit 136. The distillation column 154 may be configured to separate one or more components (e.g., portions) of the MEG rich stream 128 to generate a purified or processed stream of MEG. That is, the distillation column 154 may apply thermal energy to the MEG rich stream 128 to take advantage of differing boiling points of the components of the MEG rich stream 128. For example, the distillation column 154 may vaporize a water component (e.g., water portion) of the MEG rich stream 128 into a water stream 178 (e.g., overhead stream) to generate a processed MEG stream 182 (e.g., purified MEG stream, bottoms stream). The processed MEG stream 182 may be directed away from the MEG recovery system 10 for further processing and / or for use. For example, the processed MEG stream 182 may be directed to the PET polymerization system to generate PET illustrated in block 186. In an embodiment, at least a portion of the MEG within the processed MEG stream 182 may be solid.

[0031] The distillation column 154 may include any shape, size, and / or configuration suitable to achieve a desired purity of MEG in the processed MEG stream 182. Indeed, theshape, size, and / or configuration of the distillation column 154 may be associated with or based on one or more parameters (e.g., flow rates, chemical concentrations, temperature, pressure, etc.) of one or more MEG streams (e.g., the MEG rich stream 100, and / or the MEG rich stream 128), one or more parameters of another stream or parameter of the MEG recovery system 10, and so forth. That is, the distillation column 154 may include any suitable operating temperature, operating pressure, reflux ratio, feed stage location, number of stages, column diameter, column height, tray or packing type, and so forth to achieve a desired purity of the processed MEG stream 182.

[0032] In an embodiment, the MEG recovery system 10 may include a plurality of distillation columns 154. For example, one or more additional distillation columns may be positioned downstream of the distillation column 154, relative to a flow of the processed MEG stream 182. For instance, upon separation within the distillation column 154, the processed MEG stream 182 may be directed to the one or more additional distillation columns for further water separation, increasing the purity of MEG within the processed MEG stream 182. A bottoms stream (e.g., a second processed MEG rich stream) may be directed from the one or more additional distillation columns to one or more discharge points 188. In an embodiment, the one or more discharge points 188 may include a PET polymerization system for generating PET plastics, the oil and gas system, and / or a MEG storage unit . Indeed, any number of additional distillation columns may be added to achieve a desired purity of MEG exiting the MEG recovery system 10.

[0033] The water stream 178 may be directed through a water heat exchanger 190 (e.g., condenser) disposed along a water stream conduit 194 and directed or fed into a reflux drum 198. As such, the water stream conduit 194 may extend between the distillation column 154 and the reflux drum 198. The water heat exchanger 190 may include any suitable heat exchanger configured to condense gaseous or vapor water from the water stream 178 into liquid water. For example, the water heat exchanger 190 may be configured to transfer heat (e.g., indirect heat transfer) from the water stream 178 to a cooled working fluid, thereby at least substantially or entirely condensing any water vapor in the water stream 178. In some embodiments, at least a portion of the water stream 178 downstream of the water heat exchanger 190 may still include a portion of vapor water.As such, the reflux drum 198 may be configured to further separate liquid water from vapor water. A vapor water stream 202 may be directed away from the reflux drum 198 (e.g., via a vapor water stream conduit 206) and further away from the MEG recovery system 10 for further processing and / or disposal. In an embodiment, the vapor water stream conduit 206 may include a vapor pump 210 (e.g., vacuum pump) to facilitate transfer of vapor water away from the reflux drum 198.

[0034] A liquid water stream 214 (e.g., liquid stream) may be directed away from the reflux drum 198 via a liquid water stream conduit 218. In an embodiment, liquid water stream 214 may include at least a portion of MEG and / or impurities. As such, the liquid water stream 214 (e g., including MEG) may be further processed by the MEG recovery system 10 by recycling the liquid water stream 214 to one or more components of the MEG recovery system 10. For example, at least a portion of the liquid water stream 214 may be recycled back to the distillation column 154, via a distillation recycle conduit 222, to further separate MEG from the liquid water stream 214. Additionally or alternatively, at least a portion of the liquid water stream 214 may be recycled back to the solids removal system 158, via a liquid recycle conduit 226, to facilitate solids removal within the solids removal system 158. Additionally or alternatively, at least a portion of the liquid water stream 214 may be directed away from the MEG recovery system 10, via a disposal conduit 230, for further processing or disposal.

[0035] Technical effects of the disclosed embodiments enable purification of MEG from one or more industrial streams including monovalent salts. For example, the MEG recovery system 10 may be configured to receive a MEG rich stream (e.g., the MEG rich stream 100, the MEG rich stream 128) including MEG, water, and in some instances, various impurities. The MEG rich stream 100 may be sourced as a product of a depolymerization process and / or spent or used MEG previously used for gas hydrate crystal inhibition (e.g., within an oil and gas system). As such, the MEG recovery system 10 may be configured to remove at least a portion of the monovalent salts dissolved in the MEG rich stream 100 to improve MEG purity and reduce damage to components. The MEG recovery system 10 may include the flash separator 108 configured to separate certain impurities (e.g., TA salts) from MEG in the MEG rich stream 100. For furtherprocessing, the MEG processed (e.g., overhead stream or flow) within the flash separator 108 may be directed into one or more distillation columns 154 to separate water from MEG, improving the purity of MEG to a desired purity. After separation with the flash separator 108 (and before separation in the one or more distillation columns 154), and / or after separation within the one or more distillation columns 154, one or more solids removal systems (e.g., , the solids removal system 158) disposed within the MEG recovery system 10 may be operable to remove precipitated monovalent salts and TA salts and other impurities from the process streams of the MEG recovery system 10, improving MEG purity and reducing degradation of the components of the MEG recovery system 10.

[0036] The subject matter described in detail above may be defined by one or more clauses, as set forth below.

[0037] A process for monoethylene glycol (MEG) recovery includes feeding a MEG rich stream having water, monovalent salts, and MEG into a flash separator, where the flash separator is configured to at least partially separate the monovalent salts from the MEG in the MEG rich stream. The process also includes obtaining an overhead stream from the flash separator, where the overhead stream has a first portion of the MEG rich stream, obtaining a bottoms stream from the flash separator, where the bottoms stream has a second portion of the MEG rich stream; and feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream. The process further includes obtaining a processed MEG stream from the distillation column, where the processed MEG has more than 80 weight % of MEG, and directing the processed MEG stream to a polyethylene terephthalate (PET) system to generate PET polymers and / or plastic.

[0038] The process of any preceding clause, where the MEG rich stream is sourced from a PET depolymerization system.

[0039] The process of any preceding clause, including feeding the bottoms stream from the flash separator to a solids removal system, where the solids removal system is configured to separate at least a portion of the monovalent salts from the bottoms stream.

[0040] The process of any preceding clause, where at least one chemical component of the MEG rich stream is a product of depolymerization.

[0041] The process of any preceding clause, where the MEG rich stream is a second MEG rich stream, and the process includes feeding a first MEG rich stream into a dye removal system, where the dye removal system is configured to separate at least a portion of the dye from the first MEG rich stream, and obtaining the second MEG rich stream from the dye removal system.

[0042] The process of any preceding clause, including feeding the processed MEG stream into an additional distillation column, where the additional distillation column is configured to at least partially separate water from MEG within the processed MEG stream to produce a second processed MEG stream; and directing the second processed MEG stream to the PET polymerization system.

[0043] The process of any preceding clause, including obtaining a second overhead stream from the distillation column, where the second overhead stream includes a liquid component and a vapor component, and feeding the second overhead stream into a reflux drum, where the reflux drum is configured to at least partially separate the liquid component from the vapor component.

[0044] The process of any preceding clause, where the liquid component includes water and MEG, and the process includes feeding the liquid component from the reflux drum to the distillation column to recycle at least a portion of the MEG within the liquid component.

[0045] The process of any preceding clause, wherein the liquid component includes water, and the process includes feeding the liquid component from the reflux drum to a solids removal system to facilitate solids removal.

[0046] A system for monoethylene glycol (MEG) recovery includes a flash separator configured to receive a MEG rich stream, where the flash separator is configured to separate the MEG rich stream into an overhead stream and a bottoms stream. The system also includes a distillation column configured to receive the overhead stream from the flashseparator, where the distillation column is configured to separate the overhead stream into a processed MEG stream and a second overhead stream, and a polyethylene terephthalate (PET) polymerization system configured to generate PET plastics and configured to receive the processed MEG stream.

[0047] The system of any of the preceding clauses, wherein the MEG rich stream comprises water, dissolved monovalent salts, and MEG.

[0048] The system of any of the preceding clauses, including a solids removal system disposed downstream of the flash separator, where the solids removal system is configured to receive the bottoms stream from the flash separator to at least partially separate monovalent salts from the bottoms stream.

[0049] The system of any of the preceding clauses, where the solids removal system is configured to recycle at least a portion of a processed bottoms stream into the flash separator.

[0050] The system of any of the preceding clauses, where the flash separator is configured to receive the MEG rich stream from a PET depolymerization system.

[0051] The system of any of the preceding clauses, where the solids removal system includes a filter system configured to filter the monovalent salts and solids from MEG and water.

[0052] A process for monoethylene glycol (MEG) recovery includes feeding a MEG rich stream having water, dissolved monovalent salts, and MEG a flash separator, where the flash separator is configured to at least partially separate the monovalent salts from MEG in the MEG rich stream. The process also includes obtaining an overhead stream from the flash separator, obtaining a bottoms stream from the flash separator, feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream, and obtaining a processed MEG stream from the distillation column, where the processed MEG has more than 80 weight % of MEG. The process further includes directing the processed MEG stream to a polyethylene terephthalate (PET) polymerization system, and feeding the bottoms stream from the flashseparator into a solids removal system, where the solids removal system is configured to at least partially separate the dissolved salts from the bottoms stream.

[0053] The process of any preceding clause, including obtaining a processed bottoms stream from the solids removal system and recycling the processed bottoms stream into the flash separator.

[0054] The process of any preceding clause, including obtaining a second overhead stream from the distillation column, feeding the second overhead stream from the distillation column into a reflux drum, where the reflux drum is configured to separate a liquid component of the second overhead stream from a vapor component of the second overhead stream, feeding a first portion of the liquid component of the second overhead stream from the reflux drum to the distillation column to recycle at least a portion of the MEG within the liquid component, and feeding a second portion of the liquid component of the second overhead stream to the solids removal system to remove at least a portion of the dissolved monovalent salts within the liquid component.

[0055] The process of any preceding clause, where the MEG rich stream is sourced from a PET depolymerization system.

[0056] The process of any preceding clause, where the MEG rich stream includes terephthalic acid (TA), and the process includes obtaining a TA stream from the flash separator, and directing the TA stream into the PET depolymerization system.

[0057] A monoethylene glycol (MEG) reclamation apparatus including a flash separator / vaporizer and one or more distillation columns.

[0058] The apparatus of any preceding clause, further comprising salt management sections.

[0059] While only certain features and embodiments have been illustrated and described, many modifications and changes may occur to those skilled in the art, such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as temperatures and pressures, mounting arrangements, use of materials, colors, orientations, and so forth, without materially departing from the novelteachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

[0060] Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described, such as those unrelated to the presently contemplated best mode, or those unrelated to enablement. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

[0061] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function], .. ” or “step for [performing [a function]...”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMS:

1. A process for monoethylene glycol (MEG) recovery, the process comprising: feeding a MEG rich stream comprising water, monovalent salts, and MEG into a flash separator, wherein the flash separator is configured to at least partially separate the monovalent salts from the MEG in the MEG rich stream; obtaining an overhead stream from the flash separator, wherein the overhead stream comprises a first portion of the MEG rich stream; obtaining a bottoms stream from the flash separator, wherein the bottoms stream comprises a second portion of the MEG rich stream; feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream; obtaining a processed MEG stream from the distillation column, wherein the processed MEG comprises more than 80 weight % of MEG; and directing the processed MEG stream to a polyethylene terephthalate (PET) polymerization system to generate PET polymers and / or plastic.

2. The process of claim 1, wherein the MEG rich stream is sourced from a PET depolymerization system.

3. The process of claim 1, comprising: feeding the bottoms stream from the flash separator to a solids removal system, wherein the solids removal system is configured to separate at least a portion of the monovalent salts from the bottoms stream.

4. The process of claim 1, wherein at least one chemical component of the MEG rich stream is a product of depolymerization.

5. The process of claim 1, wherein the MEG rich stream is a second MEG rich stream, and the process comprises:feeding a first MEG rich stream into a dye removal system, wherein the dye removal system is configured to separate at least a portion of dye from the first MEG rich stream; and obtaining the second MEG rich stream from the dye removal system.

6. The process of claim 1, comprising: feeding the processed MEG stream into an additional distillation column, wherein the additional distillation column is configured to at least partially separate water from MEG within the processed MEG stream to produce a second processed MEG stream; and directing the second processed MEG stream to the PET polymerization system.

7. The process of claim 1, comprising: obtaining a second overhead stream from the distillation column, wherein the second overhead stream comprises a liquid component and a vapor component; and feeding the second overhead stream into a reflux drum, wherein the reflux drum is configured to at least partially separate the liquid component from the vapor component.

8. The process of claim 7, wherein the liquid component comprises water and MEG, and the process comprises: feeding the liquid component from the reflux drum to the distillation column to recycle at least a portion of the MEG within the liquid component.

9. The process of claim 7, wherein the liquid component comprises water, and the process comprises: feeding the liquid component from the reflux drum to a solids removal system to facilitate solids removal.

10. A system for monoethylene glycol (MEG) recovery, the system comprising: a flash separator configured to receive a MEG rich stream, wherein the flash separator is configured to separate the MEG rich stream into an overhead stream and a bottoms stream; a distillation column configured to receive the overhead stream from the flash separator, wherein the distillation column is configured to separate the overhead stream into a processed MEG stream and a second overhead stream; and a polyethylene terephthalate (PET) polymerization system configured to generate PET plastics and configured to receive the processed MEG stream.

11. The system of claim 10, wherein the MEG rich stream comprises water, dissolved monovalent salts, and MEG.

12. The system of claim 11, comprising a solids removal system disposed downstream of the flash separator, wherein the solids removal system is configured to receive the bottoms stream from the flash separator to at least partially separate monovalent salts from the bottoms stream.

13. The system of claim 12, wherein the solids removal system is configured to recycle at least a portion of a processed bottoms stream into the flash separator.

14. The system of claim 12, wherein the solids removal system includes a filter system configured to filter the monovalent salts and solids from MEG and water.

15. The system of claim 10, wherein the flash separator is configured to receive the MEG rich stream from a PET depolymerization system.

16. A process for monoethylene glycol (MEG) recovery, the process comprising:feeding a MEG rich stream comprising water, dissolved monovalent salts, and MEG into a flash separator, wherein the flash separator is configured to at least partially separate the monovalent salts from MEG in the MEG rich stream; obtaining an overhead stream from the flash separator; obtaining a bottoms stream from the flash separator; feeding the overhead stream into a distillation column configured to at least partially separate water from MEG within the overhead stream; obtaining a processed MEG stream from the distillation column, wherein the processed MEG comprises more than 80 weight % of MEG; directing the processed MEG stream to a polyethylene terephthalate (PET) polymerization system; and feeding the bottoms stream from the flash separator into a solids removal system, wherein the solids removal system is configured to at least partially separate monovalent salts and solids from the bottoms stream.

17. The process of claim 16, comprising: obtaining a processed bottoms stream from the solids removal system; and recycling the processed bottoms stream into the flash separator.

18. The process of claim 16, comprising: obtaining a second overhead stream from the distillation column; feeding the second overhead stream from the distillation column into a reflux drum, wherein the reflux drum is configured to separate a liquid component of the second overhead stream from a vapor component of the second overhead stream; feeding a first portion of the liquid component of the second overhead stream from the reflux drum to the distillation column to recycle at least a portion of the MEG within the liquid component; and feeding a second portion of the liquid component of the second overhead stream to the solids removal system to remove at least a portion of the dissolved monovalent salts within the liquid component.

19. The process of claim 16, wherein the MEG rich stream is sourced from a PET depolymerization system.

20. The process of claim 19, wherein the MEG rich stream comprises terephthalic acid (TA), and the process comprises: obtaining a TA stream from the flash separator; and directing the TA stream into the PET depolymerization system.

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