Assembly and method for regenerating contaminated heat transfer fluid

Abstract

A synthetic aromatic heat transfer fluid regeneration assembly is disclosed. The synthetic aromatic heat transfer fluid regeneration assembly of the present invention comprises: (a) a fluid connector for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system comprising a contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop; and (b) a divided wall distillation column fluidly connected to the fluid connector and comprising a side extraction opening. Related heat transfer assemblies and methods for regenerating a contaminated synthetic aromatic heat transfer fluid from a heat transfer system are also described.

Description

TECHNICAL FIELD

[0001] The present invention generally relates to methods for purifying and regenerating synthetic aromatic heat transfer fluids, in particular synthetic aromatic heat transfer fluids comprising eutectic mixtures of diphenyl ether and biphenyl compounds, as well as systems and assemblies that can be used to perform such methods. BACKGROUND ART

[0002] Materials known as heat transfer fluids (sometimes also referred to in the art as heat transfer oils or thermal fluids) are well known in the art. As the name implies, heat transfer fluids have the ability to retain and transfer / absorb thermal energy and can thus be used, for example, as a medium in a closed loop between a central heat source and one or more radiators or process users. The radiators can be, for example, reboilers of distillation columns, jacketed autoclaves, steam generators, and similar devices.

[0003] Heat transfer fluids suitable as heating media typically may have a low vapor pressure, an almost constant boiling point, excellent heat transfer characteristics, and good thermal stability. A class of heat transfer fluids that has achieved great commercial success over the years can generally be described as synthetic aromatic heating materials, which can include biphenyl (diphenyl, phenylbenzene), terphenyl, and partially hydrogenated terphenyl (PHT). These materials can be single compounds and / or mixtures thereof. In addition, these materials can be synthetic aromatic heating materials mixed with other compounds, such as, but not limited to, hydrocarbons, hydrocarbon derivatives, or polymeric materials such as polysiloxanes. The eutectic mixture of biphenyl and diphenyl ether can be referred to herein and in the art as a "DPO" heat transfer fluid. Common components of other commercially available synthetic aromatic heat transfer fluids can include partially hydrogenated terphenyl (PHT) or partially hydrogenated tetraphenyl.

[0004] Although heat transfer fluids have excellent thermal stability, they are still prone to thermal degradation after prolonged use at high temperatures or under non-recommended conditions. This degradation typically involves decomposition, where the molecular bonds of the original fluid's molecular structure break, usually forming two broad categories of degradation products: light compounds (low boilers), which may include benzene and phenol in the case of DPO fluids; and heavy compounds (high boilers), which may include o-terphenyl, m-terphenyl, p-terphenyl, and 2-phenoxybiphenyl, as well as tar and polymers in the case of DPO fluids. The concentration of these degradation contaminants in synthetic aromatic heat transfer fluids should not exceed the limits of some manufacturers, partly because the light components have a high vapor pressure, which may increase the pressure within the system and may cause cavitation in the pump, while the heavy components limit the heat transfer efficiency because they may particularly reduce or increase the specific heat of the heat transfer oil and increase its viscosity, thus forming high-boiling and low-boiling thermal decomposition products as contaminants. If the degradation contaminants are allowed to accumulate in the system, these degradation contaminants will ultimately render the entire fluid inventory unsuitable for continued use. Environmental concerns and related government regulations may also drive the limits on contaminant concentrations.

[0005] The importance of removing these degradation contaminants from the heat transfer fluid inventory has been recognized in the art, and solutions for removing these degradation contaminants have been proposed. U.S. Patent No. 4,139,418 describes an early attempt, which relates to a method and apparatus for distilling and purifying an organic heat transfer fluid, which uses an electrically heated still or purifier to distill and purify a heat transfer fluid (such as diphenyl, diphenyl ether, and their mixtures) contaminated with high-boiling thermal decomposition products. In more recent work, U.S. Patent No. 9,211,484 describes a plan and method for regenerating a degraded heat transfer oil. Even more recently, U.S. Patent No. 10,058,969 was issued, which describes a system and method for removing thermal decomposition components from a biphenyl and / or diphenyl ether heat transfer fluid.

[0006] These prior art solutions have exhibited various drawbacks, and thus their commercial success has been limited. First, implementing the solutions as components of a larger heat transfer system would significantly increase the capital cost required to build such a system. In addition, such solutions typically require the shutdown or suspension of the manufacturing processes / facilities associated with the heat transfer system, thereby increasing the inefficiency and downtime costs of the production facility. A decontamination system located off-site and operating on the heat transfer system requires the shutdown, cooling, and draining of the heat transfer system, the collection and transportation of the fluid, which increases the downtime costs and potential problems in fluid transportation. An off-site system operated by an independent contractor may handle multiple fluid types for multiple different customers, thereby presenting the possibility of fluid cross-contamination. A system that is used regularly (e.g., when the fluid is sufficiently contaminated and needs to be cleaned) results in system inefficiency when idle.

[0007] Accordingly, there is an unmet need for low-cost, low-investment methods and apparatuses for regenerating contaminated heat transfer fluids that, while allowing the associated heat transfer systems and chemical facilities to continue operating, regenerate the heat transfer fluids by effectively removing contaminant degradation products. SUMMARY OF THE INVENTION

[0008] In one embodiment herein, a method for regenerating a contaminated synthetic aromatic heat transfer fluid from a heat transfer system is disclosed, the heat transfer system including the contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop. The method includes the steps of: (a) transferring at least a portion of the contaminated synthetic aromatic heat transfer fluid from the heat transfer system to form a feed stream containing the transferred contaminated synthetic aromatic heat transfer fluid; and (b) conveying the feed stream containing the transferred contaminated synthetic aromatic heat transfer fluid to a synthetic aromatic heat transfer fluid regeneration assembly including a dividing wall distillation column to form a side draw stream, a low-boiler distillate stream, and a high-boiler distillate stream.

[0009] In another embodiment herein, a synthetic aromatic heat transfer fluid regeneration assembly is disclosed. The synthetic aromatic heat transfer fluid regeneration assembly includes: (a) a fluid connector for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system including the contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop; and (b) a dividing wall distillation column fluidly connected to the fluid connector and including a side draw outlet.

[0010] In another embodiment herein, a heat transfer assembly is disclosed. The heat transfer assembly includes a heat transfer system and a synthetic aromatic heat transfer fluid regeneration assembly, the heat transfer system including the contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop, the synthetic aromatic heat transfer fluid regeneration assembly fluidly connected to the heat transfer system, wherein the heat transfer fluid regeneration assembly includes a dividing wall distillation column.

[0011] In one or more method embodiments herein, the heat transfer system is an operating heat transfer system including a circulating contaminated synthetic aromatic heat transfer fluid in the heat transfer loop, and the collecting step (a) includes transferring at least a portion of the circulating contaminated synthetic aromatic heat transfer fluid from the heat transfer system (or the heat transfer loop) to form a stream of transferred contaminated synthetic aromatic heat transfer fluid.

[0012] In one or more method embodiments herein, the synthetic aromatic heat transfer fluid regeneration assembly is a releasably connectable synthetic aromatic heat transfer fluid regeneration assembly, and the method further includes, prior to step (b), connecting the releasably connectable synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system.

[0013] In one or more method embodiments herein, the method may further include disconnecting the releasably connectable synthetic aromatic heat transfer fluid regeneration assembly from the heat transfer system.

[0014] In one or more method embodiments herein, the method may further include accumulating at least one of the low-boiling distillate stream and the high-boiling distillate stream in at least one isolation reservoir. In one or more method embodiments herein, the method further includes accumulating the low-boiling distillate stream in a low-boiling isolation reservoir and / or accumulating the high-boiling distillate stream in a high-boiling isolation reservoir.

[0015] In one or more method embodiments herein, the method may further include returning at least a portion of the material from the side draw stream to the heat transfer system.

[0016] In one or more assembly embodiments herein, the assembly may further include at least one light-boiling material isolation reservoir fluidly connected to the dividing wall distillation column; and at least one heavy-boiling material isolation reservoir fluidly connected to the dividing wall distillation column.

[0017] In one or more assembly embodiments herein, the assembly may further include the heat transfer fluid regeneration assembly, which includes a releasable fluid connector that releasably connects the heat transfer fluid regeneration assembly to the heat transfer loop. In one or more assembly embodiments herein, the fluid connector is a releasable fluid connector.

[0018] In one or more assembly embodiments herein, the heat transfer assembly may be an operating heat transfer assembly that includes a first portion of contaminated synthetic aromatic heat transfer fluid circulating in the heat transfer loop and a second portion of contaminated synthetic aromatic heat transfer fluid flowing into the synthetic aromatic heat transfer fluid regeneration assembly.

[0019] In one or more assembly embodiments herein, the assembly is transportable purposefully.

[0020] In one or more assembly embodiments herein, the at least one light-boiling material isolation reservoir includes an isolation condenser, and / or the at least one heavy-boiling material isolation reservoir includes an isolation reboiler.

[0021] In one or more assembly embodiments of the present disclosure, the dividing wall distillation column, the at least one light boil-off isolation reservoir, and the at least one heavy boil-off isolation reservoir together form a separate modular unit. In one or more assembly embodiments of the present disclosure, the modular unit is transportable purposefully.

[0022] In one or more assembly embodiments of the present disclosure, the assembly may further include a regenerated synthetic aromatic return line releasably connected to the heat transfer loop.

[0023] Other aspects of the invention are also disclosed and claimed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic flow chart of one embodiment of a synthetic aromatic heat transfer assembly and method of the present invention;

[0025] Figure 2 is a schematic diagram of another embodiment of a synthetic aromatic heat transfer fluid regeneration assembly of the present invention;

[0026] Figure 3 is a schematic diagram of one embodiment of a synthetic aromatic heat transfer fluid regeneration assembly of the present invention, the synthetic aromatic heat transfer fluid regeneration assembly including an isolated low boil-off reservoir having a plurality of reboilers;

[0027] Figure 4 is a schematic diagram of one embodiment of a synthetic aromatic heat transfer fluid regeneration assembly of the present invention, the synthetic aromatic heat transfer fluid regeneration assembly including an isolated low boil-off reservoir having a plurality of reboilers and transfer lines; [[ID=�6]]

[0028] Figure 5 is a schematic diagram of one embodiment of a synthetic aromatic heat transfer fluid regeneration assembly of the present invention, the synthetic aromatic heat transfer fluid regeneration assembly including an isolated high boil-off reservoir having a plurality of condensers and reflux vessels;

[0029] Figure 6 is a schematic diagram of one embodiment of a synthetic aromatic heat transfer fluid regeneration assembly of the present invention for Example 1 of the present application; and

[0030] Figure 7 is a schematic diagram of a comparative example described in the present application. DETAILED DESCRIPTION

[0031] General Reference Figures 1 to 7, a first aspect of the present invention relates to a method for regenerating a contaminated synthetic aromatic heat transfer fluid from a heat transfer system 5 including a heat transfer loop 6. The method of the present invention includes the following steps: (a) transferring at least a portion of the contaminated synthetic aromatic heat transfer fluid from the heat transfer system 5 to form a transferred contaminated synthetic aromatic heat transfer fluid stream or feed stream 12; and (b) passing the transferred contaminated synthetic aromatic heat transfer fluid stream 12 into a dividing wall distillation column 40 to process the transferred contaminated synthetic aromatic heat transfer fluid stream 12 into a side draw stream 55, wherein low boilers are isolated in a low boiler isolation reservoir (such as a reflux drum), and high boilers are isolated in a high boiler isolation reservoir 85 (such as a reboiler). The low boilers and high boilers can be removed from the system in a continuous, batch, or semi-batch manner.

[0032] As used herein, the phrase "heat transfer system" is intended to broadly include systems, equipment, and devices that include a heat transfer fluid that is contained within or circulated through a heat transfer loop and is used to transport thermal energy to or from a chemical system, equipment, or operation or similar system, equipment, or operation. In one non-limiting example, a heat transfer system can transfer thermal energy between a central heat source and one or more radiators or process users. The radiator can be, for example, a reboiler of a distillation column, a jacketed autoclave, a steam generator, etc. The heat transfer fluid can exist, for example, in a vapor and / or liquid state.

[0033] In one or more embodiments, the heat transfer fluid includes a synthetic aromatic heat transfer fluid. Synthetic aromatic heat transfer fluids are common in the art and include materials that are degradable and form degradation products, such as biphenyl (diphenyl, phenylbenzene), terphenyl, and partially hydrogenated terphenyl (PHT). Other heat transfer fluids include eutectic mixtures of biphenyl and diphenyl ether, such as Therminol VP-1 available from Eastman Chemical Company TM and Dowtherm A available from Dow Inc. TM .

[0034] As used herein, the phrase "contaminated synthetic aromatic heat transfer fluid" is intended to include, but is not limited to, a heat transfer fluid containing contaminants such as synthetic aromatic degradation products generated during typical or atypical use of the synthetic aromatic heat transfer fluid. The generation, chemical composition, and type of degradation products are typically specific to the initial composition of the (multiple) heat transfer fluid and / or the manner in which the fluid is used. Although seemingly contradictory, some degradation products may be harmful to one particular type of heat transfer fluid while being acceptable to another heat transfer fluid. In the examples illustrated by the following examples and comparative examples, such as Dowtherm A or Therminol Heat transfer fluids such as VP-1 are mainly composed of biphenyl and biphenyl oxide, which may generate degradation products, including but not limited to low-boiling benzene and phenol, and isomers of high-boiling terphenyl.

[0035] The phrase "regenerated synthetic aromatic heat transfer fluid" as used herein is intended to include, but not be limited to, a heat transfer fluid in which at least a certain amount of one or more pollutant degradation products in a contaminated synthetic aromatic heat transfer fluid feed or sample have been removed. In one or more embodiments, the method of the present invention generates a sidestream comprising a regenerated synthetic aromatic heat transfer fluid, wherein the total pollutant degradation product content is from about 0.5 wt% to 40 wt%.

[0036] In the method of the present invention, a portion of the contaminated synthetic aromatic heat transfer fluid from the heat transfer system is transferred from the heat transfer system to form a transferred contaminated synthetic aromatic heat transfer fluid stream. A particularly practical feature of the present invention is that, in one or more embodiments, the method can facilitate the regeneration of the contaminated synthetic aromatic heat transfer fluid while the target heat transfer system is operating or performing its heat transfer function. In other words, the heat transfer fluid can continue to circulate in the heat transfer system loop of the heat transfer system while the regeneration method of the present invention is being carried out, such that the heat transfer system remains in operation while the contaminated synthetic aromatic heat transfer fluid is being treated by the device. This can be achieved by transferring a portion of the contaminated synthetic aromatic heat transfer fluid contained in and / or circulated in the heat transfer system to form a transferred contaminated synthetic aromatic heat transfer fluid stream. In the transfer step, at least 0.01% or at least 0.1% or at least 1% of the contaminated synthetic aromatic heat transfer fluid from the heat transfer system is transferred to form a transferred contaminated synthetic aromatic heat transfer fluid stream.

[0037] Those of ordinary skill in the art will understand that in embodiments where regeneration does not necessarily occur simultaneously with heat transfer operation (i.e., the heat transfer system is shut down or offline), up to 100% of the contaminated synthetic aromatic heat transfer fluid contained in the heat transfer system can be transferred in the transfer step.

[0038] In the method of the present invention, the transferred contaminated synthetic aromatic heat transfer fluid stream (also referred to herein and shown in the figures as feed stream 12) formed in transfer step (a) is passed to a synthetic aromatic heat transfer fluid regeneration assembly 10 including a dividing wall distillation column 40. In the dividing wall distillation column, the transferred contaminated synthetic aromatic heat transfer fluid stream is processed into a sidestream 55, wherein the low-boiling components are isolated in a low-boiling component isolation reservoir 75, which may include a reflux drum in some embodiments, and the high-boiling components are isolated in a high-boiling component isolation reservoir 85, which may include a reboiler in some embodiments. The low-boiling and high-boiling components can be removed from the system in a continuous, batch, or semi-batch manner.

[0039] A divided wall distillation column (also known as a divided wall column, DWC, or dividing wall distillation column) is known in the art and generally includes a column 40 having a wall or similar structure, such as 45 shown in the figure, that divides the interior 42 of the column. Divided wall distillation columns are described, for example, in U.S. Patent No. 6,958,111, the content and disclosure of which are incorporated herein by reference. Various dividing wall configurations of divided wall columns are applicable to the present invention, including but not limited to a wall 45 extending centrally in the column as shown in Figure 1 and Figure 2 ; a wall 45 extending from the top of the column towards the center as shown in Figure 4 ; a wall 45 extending from the bottom or base of the column towards the center as shown in Figure 2 , Figure 3 and Figure 5 ; and an annular wall extending circumferentially around the interior of the column and separating a central distillation zone from an annular distillation zone.

[0040] In the divided wall distillation column 40, a transferred contaminated synthetic aromatic heat transfer fluid stream (labeled as feed stream 12 in the figure) is processed into an output stream that includes a side draw stream 55 exiting the column 40, where low boilers are isolated in a reflux drum XXX and high boilers are isolated in a reboiler. The low boilers and high boilers can be removed from the system in a continuous, batch, or semi-batch manner. Generally, the low boiler distillate stream may contain components corresponding to contaminant degradation products having a boiling point lower than the nominal boiling point of the uncontaminated heat transfer fluid and can typically be removed from the upper part of the DWC eventually; the high boiler distillate stream may contain components corresponding to contaminant degradation products having a boiling point higher than the boiling point of the uncontaminated heat transfer fluid and can be removed from the lower part of the DWC eventually; the side draw stream may contain the regenerated heat transfer fluid as a major component and can be collected and / or returned as the recovered heat transfer fluid through an outlet from the central part of the DWC. Although the approximate locations of these outlets 56, 72, and 82 are illustrated in the figure, it should be understood that their exact locations along the column 40 may vary depending on various factors, including for example the type and amount of (multiple) contaminant degradation products, the specific composition and components of the heat transfer fluid.

[0041] A distinguishing feature of the method of the present invention is the accumulation and isolation of distillate streams 70 and 80 during the treatment of contaminated synthetic aromatic heat transfer fluids. Thus, in one or more embodiments, the method of the present invention further includes collecting or accumulating at least one of the low-boiling distillate stream and the high-boiling distillate stream in an isolation reservoir. In one or more embodiments, the method of the present invention further includes collecting or accumulating the low-boiling distillate stream 70 in a low-boiling isolation reservoir 75 and collecting or accumulating the high-boiling distillate stream 80 in a high-boiling isolation reservoir 85. Figures 2 to 6 Example configurations are provided, but these example configurations are not intended to be limiting.

[0042] The reservoirs 75 and 85 for collecting and isolating the distillate streams can include one or more containers, with or without additional components, such as components known in the art suitable for chemical processing applications. In a non-limiting example, the isolation reservoir 85 for the high-boiling distillate stream 80 can include one or more isolation reboilers or reflux boilers 86, which include a heating contactor 87. In a non-limiting example, the low-boiling isolation reservoir 75 for the low-boiling distillate stream 70 can include one or more isolation condensers 76, which can include a coolant contactor 77 and one or more collection containers (e.g., reflux drums) 78. Those of ordinary skill in the art should understand that, depending on, for example, size, construction, and system requirements, reboilers and condensers can also be used as storage / collection containers, or a separate storage container in series with them may be required. A portion of the contents of the reservoirs 75 and 85 (sometimes referred to as reflux or boilup) can be returned to the dividing wall column, generally as shown at 97 and 98, respectively. Thus, in one or more embodiments, the isolation reservoir can more generally include devices known in the art that are capable of and / or can be used to collect, accumulate, or store fluids (more specifically contaminants and / or synthetic aromatic heat transfer fluids), non-limiting examples including pressure vessels, bladders, receivers, storage tanks, pipes, etc.

[0043] Consider that the method and assembly of the present invention employ more than one isolation condenser, more than one isolation reboiler, and multiple associated collection containers. In a non-limiting example, Figure 3 and Figure 4 shows a non-limiting embodiment that includes multiple high-boiling distillate streams 80 and 80', isolation reboilers 86 and 86', and reflux streams 98 and 98' ( Figure 4 also shows a transfer stream 91 that facilitates the transfer of fluid from one side of the DWC to the other); Figure 5 shows multiple low-boiling distillate streams 70 and 70', condensers 76 and 76', and collection containers 78 and 78'.

[0044] In one or more embodiments of the method of the present invention, the method may include continuously or periodically discharging contaminants from an isolation reservoir. In one or more embodiments of the method of the present invention, the method may include continuously or periodically returning at least a portion of the contaminants from the isolation reservoir to the DWC as one or more distillate streams.

[0045] Accordingly, in one or more embodiments, the method of the present invention may include accumulating low-boiling contaminants (as distillate) in one or more low-boiler isolation reservoirs and returning at least a portion of the low-boiling contaminants to the DWC as a reflux stream 97, preferably without any low-boiler discharge or removal. Similarly, in one or more embodiments, the method of the present invention may include accumulating high-boiling contaminants (as distillate) in one or more high-boiler isolation reservoirs and returning at least a portion of the contaminants to the DWC as a boil-up stream 98, preferably without any high-boiling contaminant discharge or removal.

[0046] In one or more embodiments, the method of the present invention includes preloading a charge of synthetic aromatic heat transfer fluid or contaminated synthetic aromatic heat transfer fluid in a dividing wall distillation column prior to the transfer step (b). In one or more embodiments, the mass flow rates of the feed stream 12 and the side draw stream 55 are nominally equal.

[0047] Although in some embodiments, the removal of impurities or contaminants and thus the method of the present invention may be continuous, batch, or semi-batch, batch or periodic removal of impurities has some distinct advantages, and thus the method of the present invention may also be batch or periodic. For example, by eliminating the continuous removal of low boilers and / or the continuous removal of high boilers, the operation of the DWC can be simplified by eliminating control valves and other instrumentation associated with the process control of continuous material streams. Another potential advantage of batch or semi-batch removal of impurities relates to the in-situ isolation of impurities. In one non-limiting operating configuration, the accumulated impurities can be disposed of by direct discharge into a waste container, thereby eliminating the need for additional storage (tank storage) of the impurities. In principle, reducing the number of physical transfers of materials can reduce the risk of accidental spills or releases of contaminants.

[0048] Another important feature of one or more embodiments of the present invention is the modular construction and releasable connectivity of the synthetic aromatic heat transfer fluid regeneration assembly, which aspect of the present invention will be described in more detail hereinafter. In such embodiments, the heat transfer fluid regeneration assembly of the present invention can be purposefully transported or moved as a "module" which can be connected to a heat transfer loop to recover contaminated heat transfer fluid and then disconnected and reused at a separate location or site to recover another contaminated heat transfer fluid, even a heat transfer fluid of a different chemical class. This reusability can facilitate the renting or leasing of such modules by heat transfer fluid customers / users or the purchase of such modules by heat transfer users / customers having facilities at multiple locations. Thus, in one or more embodiments of the method of the present invention, the method can include the step of connecting a releasably connected synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system prior to the transfer step (b). In one or more embodiments of the method of the present invention, the method can include the step of disconnecting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly from the heat transfer system.

[0049] Another important feature of one or more embodiments of the present invention is the mobility or transportability of the synthetic aromatic heat transfer fluid regeneration assembly, which aspect of the present invention will be described in more detail hereinafter. Thus, in one or more embodiments of the method of the present invention, the method can include the step of transporting a releasably connected synthetic aromatic heat transfer fluid regeneration assembly to a site including a heat transfer system or heat transfer loop prior to the step of connecting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system. Similarly, in one or more embodiments of the method of the present invention, the method can include the step of transporting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly away from a site including a heat transfer system or heat transfer loop after the step of disconnecting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly from the heat transfer system.

[0050] In a second related aspect, the present invention relates to a synthetic aromatic heat transfer fluid regeneration assembly. The synthetic aromatic heat transfer fluid regeneration assembly of the present invention, generally labeled 10 in the figures, includes: (a) a fluid connector 15 for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system 5, the system including contaminated synthetic aromatic heat transfer fluid contained and / or circulated in a heat transfer loop 6; (b) a dividing wall distillation column 40 fluidly connected to the fluid connector and including a side take-off 56; (c) a low boiler isolation reservoir 75 fluidly connected to the dividing wall distillation column 40; and (e) at least one high boiler isolation reservoir 85 fluidly connected to the dividing wall distillation column 40.

[0051] Those of ordinary skill in the art will understand and recognize that the elements or features described in one aspect or embodiment of the present invention can be applicable to and can be used to describe other aspects or embodiments. By way of non-limiting example, the description of the dividing wall distillation column set forth in the context of the method of the present invention is also applicable to and can be used to describe the dividing wall distillation column features of the heat transfer system of the present invention and / or the synthetic aromatic heat transfer fluid regeneration assembly of the present invention. In addition, the description related to the dividing wall distillation column set forth in the context of the heat transfer system of the present invention and the synthetic aromatic heat transfer fluid regeneration assembly of the present invention is also applicable to and can be used to describe the dividing wall distillation column in the context of the method of the present invention. Similarly, the description related to at least one low-boiler isolation reservoir set forth in the heat transfer system aspect of the present invention and / or the synthetic aromatic heat transfer fluid regeneration assembly aspect of the present invention can be applicable to and can be used to describe the low-boiler isolation reservoir features of the method of the present invention. Accordingly, the description and disclosure related to the elements or features of one aspect or embodiment of the present invention are hereby expressly relied upon to describe and support those elements or features in other aspects or embodiments.

[0052] The synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention includes a fluid connector 15 for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system 5. Typical heat transfer systems to which the synthetic aromatic heat transfer fluid regeneration assembly 10 can be fluidly connected include heat transfer fluids, such as synthetic aromatic heat transfer fluids or contaminated synthetic aromatic heat transfer fluids, which are contained in a heat transfer loop 6 and which, when the heat transfer system is operating, circulate in the heat transfer loop 6 to transfer thermal energy between the heat transfer fluid and a chemical system or device 7. Such heat transfer systems are used in a variety of industries and systems that require heat transfer. Heat transfer systems and heat transfer loops using synthetic heat transfer fluids can be used, for example, in the chemical industry as a heating facility to complement or replace steam systems; in concentrated solar power (CSP) systems for storing and distributing thermal energy; and in nuclear power systems for storing thermal energy and serving as a reactor coolant. Heat transfer systems and heat transfer loops in various utilities are also described, for example, in U.S. Patent Nos. 3,756,312 and 4,744,408 and U.S. Published Patent Application No. 2013 / 0086904, the contents and disclosures of which are incorporated herein by reference.

[0053] The fluid connector 15 can be any fluid connector having a certain structure or configuration and suitable components for allowing fluid communication between the heat transfer system 5 or its heat transfer loop 6 and the synthetic aromatic heat transfer fluid regeneration assembly 10 such that the heat transfer fluid contained in the heat transfer loop or at least a portion thereof can flow or be transferred from the heat transfer system 5 to the synthetic aromatic heat transfer fluid regeneration assembly 10. Non-limiting examples of such fluid connectors are well known in the art and include valves, T-joints, etc. and combinations thereof. In certain embodiments, the fluid connector can be located near the tower 40, the heat transfer loop 6, or at a location between the two. In embodiments where the assembly includes a housing 60 as shown in Figure 1 FIG. 60, the connector can be located near the housing or at a location between the housing and the heat transfer loop 6.

[0054] In one or more embodiments, the fluid connector is a releasable fluid connector. The term "releasable" is intended to include connectors that are purposefully designed or constructed to non-permanently establish fluid communication between the synthetic aromatic heat transfer fluid regeneration assembly 10 and the heat transfer system 5 and are capable of easily disassembling, separating, or otherwise disconnecting the synthetic aromatic heat transfer fluid regeneration assembly from the heat transfer system. Releasable fluid connectors are well known in the art and include flexible hose connections, flanged pipe connections, line connectors (such as connectors of the Swagelok TM brand, etc.). The releasable fluid connector can also include a "two-piece" connector that can include a first component that is part of the synthetic aromatic heat transfer fluid regeneration assembly and a second component that is part of the heat transfer system of the heat transfer loop and mates or couples with the first component. The releasable fluid connector can also include valves and / or other equipment components for measuring or controlling various aspects of material movement and transfer.

[0055] Although the fluid connector preferably directly fluidly connects the regeneration assembly to the heat transfer system itself, embodiments are also contemplated where the fluid connector is used to fluidly connect the synthetic aromatic heat transfer fluid regeneration assembly to one or more intermediate heat transfer fluid storage containers and are within the scope of the present invention.

[0056] An important and relevant (but independent) feature of one or more embodiments of the present invention is (i) modular construction and (ii) releasable connectivity between the synthetic aromatic heat transfer fluid regeneration assembly and the heat transfer system. In such embodiments, the synthetic aromatic heat transfer fluid regeneration assembly can be a module or modular unit or separate unit or separate self-contained unit or separate enclosed unit, as shown in Figure 1As shown. In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly can be purposefully transportable and includes elements such as a housing 60 having a support base (such as a slide rail or similar structure). In such an embodiment, the assembly is constructed and assembled to facilitate movement or transportation, for example, between various physical heat transfer system sites, or from a non-operating, remote, or storage location to a working functional location near or adjacent to the heat transfer system, and optionally back to the non-operating, remote, or storage location. In some embodiments, the assembly can include one or more wheels or rollers 61 mounted thereon to facilitate movement and transportation. In some embodiments, the assembly can include mounting equipment, such as lugs or brackets for temporary or permanent attachment to a structure or the floor or ground. In some embodiments, the assembly can include a power connector for detachable connection to a power source. Similarly, the assembly can include connectors for other functions, such as connectors for monitoring instruments, utility (vapor, cooling water, inert gas, compressed air, etc.) connectors, and safety system connectors. In such an embodiment, the synthetic aromatic heat transfer fluid regeneration assembly can be a releasably connected synthetic aromatic heat transfer fluid regeneration assembly and can include a releasable fluid connector for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system.

[0057] The synthetic aromatic heat transfer fluid regeneration assembly of the present invention includes a divided wall distillation column 40 fluidly connected to the fluid connector. A divided wall distillation column (also known as a divided wall column (DWC) or a dividing wall distillation column) is known in the art and generally includes a column having a wall or similar structure that divides the interior of the column. Various dividing wall configurations of the divided wall column are suitable for the present invention, including but not limited to the configurations previously described herein and shown in the figures. The divided wall distillation column 40 can include a side take-off port 56.

[0058] The material obtained from the side take-off port 56 (also known as the side stream 55) includes a regenerated synthetic aromatic heat transfer fluid. The regenerated synthetic aromatic heat transfer fluid includes a certain content of at least one degradation product contaminant, and this content is lower than the content of the contaminants present in the contaminated synthetic aromatic heat transfer fluid. In one or more embodiments, the regenerated heat transfer fluid can be collected. In one or more embodiments, the regenerated heat transfer fluid can be returned to the heat transfer system 5.

[0059] The synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention may include at least one low-boiler isolation reservoir 75 fluidly connected to the dividing-wall distillation column 40. The function of the low-boiler isolation reservoir 75 is to collect and accumulate the material flowing out of the dividing-wall distillation column low-boiler outlet, which is generally described as "low boilers" or "light materials" because this material exhibits a boiling point lower than that of the synthetic aromatic heat transfer fluid. This material may be generated due to the degradation of the synthetic aromatic heat transfer fluid over time during use, resulting in the contamination of the synthetic aromatic heat transfer fluid and the corresponding reduction and / or elimination of the heat transfer function.

[0060] In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly may include a low-boiler reflux line 97 for returning a portion of the accumulated contaminants as reflux. In this reflux, at least a portion of the low boilers from the low-boiler isolation reservoir 75 may be recovered or returned to the dividing-wall distillation column 40 for further processing, such as further enriching the low-boiler concentration. The low boilers may be isolated and accumulated in the isolation reservoir 75 over time and collected periodically through one or more collection ports 79.

[0061] In one or more embodiments, at least one low-boiler isolation reservoir 75 may include an isolation condenser 76, where the low boilers may be condensed during the accumulation and isolation process and, in some embodiments, collected in a reflux drum or similar collection vessel 78.

[0062] The synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention may include at least one high-boiler isolation reservoir 85 fluidly connected to the dividing-wall distillation column. One use of the high-boiler low-boiler isolation reservoir is to collect and accumulate the high-boiling materials flowing out of the dividing-wall distillation column, which are generally referred to as "high boilers" or "heavy materials" because this material exhibits a boiling point higher than that of the heat transfer fluid. This material may be generated due to the degradation of the heat transfer fluid over time during use and result in the contamination of the heat transfer fluid and the corresponding reduction and / or elimination of the heat transfer function.

[0063] In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly may include a boil-up line 98 for returning at least some of the accumulated high-boiling contaminants to the DWC. In this boil-up, at least a portion of the high boilers from the high-boiler isolation reservoir 85 may be recovered or returned to the dividing-wall distillation column 40 for further processing, such as further increasing the high-boiler concentration. The high boilers may be isolated and accumulated in the isolation reservoir 85 over time and collected periodically through one or more collection ports 89.

[0064] In one or more embodiments, at least one high-boiler isolation reservoir 85 may include at least one isolation reboiler 86, where at least some high boilers may be evaporated during the accumulation and isolation process.

[0065] The specific number of isolation reservoirs, their functions, whether there are separate collection containers (such as shown as 78 in Figure 1 ), and whether there is reflux may depend on various factors, including but not limited to the position of the dividing wall in the column, the quantity and type of heat transfer fluid contaminants, the flow rate, and other specific factors based on the design configuration. Figures 2 to 6 Multiple non-limiting exemplary embodiments and configurations are shown. Figure 2 An embodiment of the synthetic aromatic heat transfer fluid regeneration assembly of the present invention is shown, including: a dividing-wall distillation column 40, which includes a dividing wall 45 disposed along the center inside the column 42; a low-boiler isolation reservoir 75, which has a reflux pipe 97 and includes a condenser 76 and a reflux drum 78; and a high-boiler isolation reservoir 85, which has a boil-off or partially boiled-off pipe 98 and includes a reboiler 86. Figure 3 and Figure 4 An embodiment of the synthetic aromatic heat transfer fluid regeneration assembly of the present invention is shown, including: a dividing-wall distillation column 40, which includes a dividing wall 45 extending upward from the column base 41 into the column interior 42; a low-boiler isolation reservoir 75, which has a reflux 97 and includes a condenser 76 and a reflux drum 78; and a high-boiler isolation reservoir 85, which has a boil-off (or partially boiled-off) pipe 98 and includes two isolation reboilers 86 and 86' and boil-off pipes 98 and 98'. Figure 4 An embodiment is shown, which further includes a transfer stream 91 for transporting liquid from one side of the dividing-wall column to the other side. Optionally, the liquid transportation can be accomplished by means of a device such as a pump. Figure 5 An embodiment of the synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention is shown, which includes a dividing-wall distillation column 40, which includes a dividing wall 45 extending downward from the column top 43 into the column interior 42; a low-boiler isolation reservoir 75, which has a reflux pipe 97 and includes isolation condensers 76 and 76', and the condensers include separate reflux drums (collection containers) 78 and 78'; and a high-boiler isolation reservoir 85, which has a boil-off (or partially boiled-off) pipe 98 and an isolation reboiler 86. Figure 6 An embodiment of the synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention is shown, which includes a dividing-wall distillation column 40, which includes a dividing wall 45 extending upward from the column base 41 into the column interior 42; a low-boiler isolation reservoir 75, which has a reflux pipe 97 and includes an isolation condenser 76, and the condenser includes a separate collection container 78; and a high-boiler isolation reservoir 85.

[0066] In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention may optionally include other auxiliary equipment, systems, or devices, such as systems that can be used to operate with any particular synthetic aromatic heat transfer fluid under vacuum conditions. For example, in order to operate under reduced pressure and temperature conditions (e.g., sub-atmospheric conditions), a vacuum pump or a system including multiple vacuum pumps and / or systems may be included in the regeneration assembly. Referring to the drawings, the vacuum pump or system may be connected to the regeneration assembly through a connection with a condenser. Although it should be apparent to those skilled in the art that the vacuum pump or system can be connected at any location within the regeneration assembly where it can effectively facilitate the reduction of the pressure and / or temperature within the assembly.

[0067] In another non-limiting example of optional equipment, an odor mitigation device or a pollution mitigation device may also be connected to the regeneration assembly as needed or desired. Examples of these types of devices include, but are not limited to, flare systems, combustion systems, volatile organic compound (VOC) destruction systems, regenerative oxidation equipment, thermal oxidation equipment, and / or catalytic oxidation systems. Additional optional or auxiliary equipment may be readily apparent to those of ordinary skill in the art.

[0068] Those of ordinary skill in the art will understand that the regeneration assembly can be constructed of compatible materials configured to be consistent with the operation related to the degradation products. For example, if it is known that the degradation products from a certain synthetic aromatic heat transfer fluid are corrosive, it may be advantageous to construct the assembly with corrosion-resistant materials such as high-nickel-content steel.

[0069] Another advantageous feature of one or more embodiments of the present invention is the transportable configuration of the synthetic aromatic heat transfer fluid regeneration assembly. In such embodiments, the synthetic aromatic heat transfer fluid regeneration assembly can be a modular unit or a separate unit or a separate self-contained unit or a separate enclosed unit, as Figure 1As shown. In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly 10 can be purposefully transported and can include elements such as a support base 62 that supports a dividing wall distillation column 40; one or more transport elements 61, such as wheels, rollers, sliders, etc., to facilitate movement or transportation between a first and a second position, for example, from a non-operating, remote, or storage position to a working functional position near or adjacent to a heat transfer system and optionally back to the non-operating, remote, or storage position; and an optional housing 60. Additionally, the assembly can be configured to be transported within a container compliant with ISO standard 668:2020 or a standard intermodal container or a similar container for bulk goods. In such an embodiment, the synthetic aromatic heat transfer fluid regeneration assembly can also include releasable fluid connectors for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system as described elsewhere herein (e.g., a quick-connect hose).

[0070] In a third related aspect, the present invention relates to a heat transfer assembly 60, generally as Figure 1 shown. The heat transfer assembly of the present invention includes: (a) a heat transfer system 5 that includes a contaminated synthetic aromatic heat transfer fluid contained within a heat transfer loop 6; and (b) a synthetic aromatic heat transfer fluid regeneration assembly 10, more specifically, the synthetic aromatic heat transfer fluid regeneration assembly 10 of the present invention, which is fluidly connected to the heat transfer system 5. The synthetic aromatic heat transfer fluid regeneration assembly 10 includes a dividing wall distillation column 40 that includes a side draw outlet 56 for a side draw stream 55. In one or more embodiments, the synthetic aromatic heat transfer fluid regeneration assembly 10 is releasably connected to the heat transfer system 5 and includes at least one releasable fluid connector 15 that fluidly connects the synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system.

[0071] In multiple embodiments, the heat transfer assembly of the present invention can operate in various modes to provide a supply of regenerated synthetic aromatic heat transfer fluid. In the first and preferred mode, the heat transfer system is an operable heat transfer system, which can be described as working, functional, or operative, and includes a synthetic aromatic heat transfer fluid that circulates in a heat transfer loop and provides a heat transfer function for a related chemical process, equipment, or system (e.g., a concentrating solar thermal power generation facility). In this mode, a portion of the contaminated synthetic aromatic heat transfer fluid is transferred or pumped from the heat transfer system back to the synthetic aromatic heat transfer fluid regeneration assembly. Thus, in one or more embodiments, the heat transfer assembly includes a first portion of the contaminated synthetic aromatic heat transfer fluid that circulates in the heat transfer loop and a second portion of the contaminated synthetic aromatic heat transfer fluid that flows into and through the synthetic aromatic heat transfer fluid regeneration assembly. In another operating mode, the heat transfer system may be described as non-working, non-functional, or non-operative, as if it were shut down. In this mode, the synthetic aromatic heat transfer fluid may reside or be contained in the heat transfer loop but does not circulate in the loop and does not provide a heat transfer function for the related chemical process, equipment, or system.

[0072] In one or more embodiments, the material (i.e., the regenerated synthetic aromatic heat transfer fluid) is collected from the side take-off of the dividing wall distillation column 40. In one or more embodiments, the material (i.e., the regenerated synthetic aromatic heat transfer fluid) from the side take-off of the dividing wall distillation column returns to the heat transfer system, as Figure 1 shown. Thus, in some embodiments, the heat transfer system includes a regenerated synthetic aromatic return line 65 that is releasably connected to the heat transfer loop 6.

[0073] As described elsewhere herein, those of ordinary skill in the art will understand and recognize that the elements or features described in one aspect or embodiment of the present invention can be applicable to and used to describe other aspects or embodiments. By way of non-limiting example, the description of the dividing wall distillation column set forth in the context of the method of the present invention is also applicable to and can be used to describe the dividing wall distillation column features of the heat transfer system of the present invention and / or the synthetic aromatic heat transfer fluid regeneration assembly of the present invention. Additionally, the description related to the dividing wall distillation column set forth in the context of the heat transfer system of the present invention and the synthetic aromatic heat transfer fluid regeneration assembly of the present invention is also applicable to and can be used to describe the dividing wall distillation column in the context of the method of the present invention. Similarly, the description related to at least one low-boiler isolation reservoir set forth in the heat transfer system aspect of the present invention and / or the synthetic aromatic heat transfer fluid regeneration assembly aspect of the present invention can be applicable to and used to describe the low-boiler isolation reservoir features of the method of the present invention. Thus, the description and disclosure related to the elements or features of one aspect or embodiment of the present invention are expressly relied upon herein to describe and support those elements or features in other aspects or embodiments.

[0074] Thus, in one or more embodiments, the heat transfer assembly 60 includes a heat transfer fluid regeneration assembly 10 that includes a feed conduit 14 that conveys a feed stream 12 and that has a releasable fluid connector 15 that releasably connects the heat transfer fluid regeneration assembly 10 to the heat transfer system 5, preferably to a heat transfer loop 6. In one or more embodiments, the heat transfer assembly 10 includes at least one low-boiler isolation reservoir 75 fluidly connected to the dividing wall distillation column 40 and at least one high-boiler isolation reservoir 85 fluidly connected to the dividing wall distillation column 40, where in some embodiments, at least one low-boiler isolation reservoir 75 includes an isolation condenser 76 and in some embodiments, at least one high-boiler isolation reservoir 85 includes an isolation reboiler 86.

[0075] In addition, in one or more embodiments, the heat transfer assembly of the present invention can include a synthetic aromatic heat transfer fluid regeneration assembly 10, which can be a modular unit or a separate unit or a separate self-contained unit or a separate enclosed unit, and in some embodiments, the assembly can be purposefully transportable or movable and can include elements such as a support base 62 that supports the dividing wall distillation column 40, an optional housing 60, and one or more transport elements (such as wheels, rollers, sliders, etc.) to facilitate movement or transportation between a first location and a second location.

[0076] While the following examples are provided to illustrate in detail many aspects and advantages of the present invention, these examples should not be construed as limiting the scope of the present invention in any way. Those of ordinary skill in the art will readily recognize variations, modifications, and adaptations that do not depart from the spirit of the present invention.

[0077] Embodiment of the present invention

[0078] To illustrate the many benefits of the present invention, the Plus TM process simulation software was used to Figure 6 simulate the embodiment of the regeneration assembly of the present invention shown. In this non-limiting illustrative embodiment, the synthetic aromatic heat transfer fluid regeneration assembly 10 includes a dividing wall distillation column 40 that includes a dividing wall 45 that extends from the bottom or base of the column and into the interior of the column; a low-boiler isolation reservoir 75 that has a reflux 97 and includes an isolation condenser 76 and a separate collection container 78; and a high-boiler isolation reservoir 85. In this example, the contaminated synthetic aromatic heat transfer fluid (more specifically, a commercially available product named Dowtherm TMThe feed flow rate of the biphenyl ether / diphenyl ether eutectic mixture of A is set to 375 kg / hr continuously, where the average contaminated synthetic aromatic heat transfer fluid feed composition is assumed to be about 97 wt.% synthetic aromatic heat transfer fluid, and about 0.9 wt.% of low-boiling / light-boiling degradation contaminants (such as benzene and phenol) and about 2.1 wt.% of high-boiling / heavy-boiling degradation contaminants (such as isomers of terphenyl). The average composition of the returned "regenerated" synthetic aromatic heat transfer fluid material is 98.2 wt.% synthetic aromatic heat transfer fluid, and about 1.6 wt.% of high-boiling / heavy-boiling degradation contaminants and about 0.2 wt.% of low-boiling / light-boiling degradation contaminants.

[0079] The configuration of the dividing wall column used in the simulation is as follows:

[0080] · The feed side of the column ( Figure 6 the left side in

[0081] Figure 6 has 6 theoretical plates, and the feed enters above the sixth plate from the top. · The outlet side of the column (

[0082] the right side in

[0083]

[0084] has 5 theoretical plates, and the liquid side draw is taken out from the second plate from the top. · The top of the column above the wall includes 2 theoretical plates and a condenser (one theoretical plate).

[0085] · The bottom of the column includes a kettle reboiler (one theoretical plate).

[0086] · The vapor from the reboiler is evenly distributed between the feed side and the outlet side of the column. TM is packed with Mellapak

[0087] PL 202Y structured packing. The packed height of each theoretical plate except the condenser and the reboiler is assumed to be 39 inches (1 m).

[0088] For a heat transfer system with a total inventory of 1300 metric tons (1,300,000 kg) of synthetic aromatic heat transfer fluid, it takes about 3467 hours (20.6 weeks) of continuous operation to process this inventory. Assuming that the isolated light-boiling and high-boiling components are removed regularly from the corresponding isolation reservoirs, two liquid reservoirs with a capacity of about 1700 gallons (6.4 m 3 ) will be sufficient for the degradation contaminants to accumulate for about 1700 hours (10.3 weeks), and then be discharged from the reservoirs.

[0089] Based on the distillation column size correlations in the ASPEN Plus software, the cross-sectional areas of the dividing wall column on the "left" and "right" sides are calculated to be approximately 46.3 in 2 and 42.7 in 2 , so the overall column diameter is approximately 10.7 inches. The column packing and column diameter dimensions are assumed to apply to the assembly operation with a maximum flooding rate of 80%.

[0090] Based on the simulation results, in terms of overall dimensions, the synthetic aromatic heat transfer fluid regeneration assembly may include the following:

[0091] · Kettle reboiler - 66 inches OD (167 cm) x 10 feet (3.05 m) t-t length (1700 gallon liquid inventory), with heating coils

[0092] · Reflux vessel - 66 inches OD (167 cm) x 10 feet (3.05 m) t-t length (1700 gallon liquid inventory)

[0093] · Condenser

[0094] Dividing wall column shell - 11 inches (28 cm) OD x 20 feet (6.1 m) t-t height

[0095] The heat and material balance results of the ASPEN Plus simulation are shown in Table 1 below.

[0096] Table 1

[0097]

[0098]

[0099] Heat load

[0100] Reboiler Condenser (BTU / hr) (BTU / hr) 270,746 226,648

[0101] Comparative example

[0102] For comparison and contrast with the present invention, an ASPEN Plus chemical process simulation was also developed for a similar heat transfer recovery system based on the description and examples provided in U.S. Patent No. 9,211,484 and shown in Figure 1 (which is reproduced in this application as Figure 7 ). In this comparative example, the total inventory of the heat transfer system is 1300 metric tons. Using the specifications, description, and drawings set forth in the '484 patent and applying a feed rate of 6,500 kg / hr, the results set forth in Table 2 below were obtained through ASPEN simulation.

[0103] Table 2

[0104]

[0105]

[0106] Feed cooler Reboiler Condenser (BTU / hr) (BTU / hr) (BTU / hr) 2,632,398 3,974,978 1,756,491

[0107] It should be noted that the recovery system described in the '484 patent is designed for continuous operation rather than batch operation. In other words, the recovery system described in the '484 patent withdraws contaminated Dowtherm A material from the heat transfer system and periodically processes the contaminated material through its device. It is expected that such withdrawal will require shutting down or interrupting the normal operation of the heat transfer system. Therefore, processing 1300 metric tons of material will require 200 operating hours, and unfortunately, the downtime will be approximately 8 to 9 days.

[0108] By comparing the present invention with the prior art (including referring to the above embodiments), numerous advantages and benefits of the present invention can be easily and clearly observed. One advantage is that the physical size of the regeneration assembly of the present invention is significantly smaller compared to the known art. In some embodiments, the assembly can be in the form of a separately enclosed unit, and its average flow rate is significantly lower compared to a double distillation column system with an average flow rate 20 times higher. Therefore, it is expected that the capital cost of the dividing wall system will be correspondingly reduced.

[0109] Another advantage is that impurities are continuously isolated and accumulated in the reservoir within the dividing wall system, so that low-boiling impurities and high-boiling impurities are continuously physically separated from the heat transfer fluid (by being isolated in the low-boiling reservoir and the high-boiling reservoir). Instead of allowing impurities to accumulate and then removing the impurities within a relatively short period of time (i.e., 200 hours), the regeneration assembly of the present invention can operate continuously for a long time to isolate (locally accumulate and concentrate) impurities in situ while the relevant heat transfer system is operating. Therefore, although the average flux of the dividing wall system is lower, the simultaneous and continuous removal of impurities can make the overall device smaller. In contrast, traditional systems allow impurities to accumulate in the heat transfer fluid, and the impurity concentration is only periodically reduced.

[0110] Yet another advantage is that the dividing wall system can operate without interrupting the main function of the heat transfer system. In this case, a small slip stream feed (e.g., as low as 1 / 4000) of the total heat transfer fluid inventory can be processed per hour. This only accounts for a very small part of the entire heat transfer system size, which allows the recovery operation to be carried out simultaneously and in situ with the heat transfer system operation without imposing a significant heat load on the entire system.

[0111] In some embodiments, another advantage is that the assembly can eliminate fluid transport pressure elements (such as pumps and similar mechanical equipment elements), and instead rely on natural gravity or nominal heat transfer system pressure, and input heat as needed to transport the fluid through the assembly. Specifically, in embodiments where the only liquid outlet stream from the synthetic aromatic heat transfer fluid regeneration assembly is a side draw, the unit can be simply evacuated using a vacuum or a sealed leg based on setting the elevation of the side draw to be sufficiently higher than the return tank operating at atmospheric pressure. Thus, in some embodiments, the transfer step (b) of the method of the present invention can include the step of applying gravity to the synthetic aromatic heat transfer fluid, preferably without positive pressure intentionally applied by components of the regeneration assembly. Similarly, the synthetic aromatic heat transfer fluid regeneration assembly of the present invention can include an assembly that excludes or includes a dedicated pressure application element or device (such as a pump).

[0112] Another advantage of the present invention lies in the flexibility of the heat source for components (such as, for example, a split reboiler) of the synthetic aromatic heat transfer fluid regeneration assembly that may require thermal energy for operation. In one example, if the dividing wall column of the synthetic aromatic heat transfer fluid regeneration assembly operates at a much lower temperature and pressure than the heat transfer system, the heat source for the split reboiler can receive thermal energy from the contaminated synthetic aromatic heat transfer fluid, the regenerated synthetic aromatic heat transfer fluid, and / or a combination thereof. Thus, in one or more embodiments, the step of collecting the light ends distillate stream in the light ends isolation reservoir in the method of the present invention can include collecting the light ends distillate stream in a split reboiler that receives at least a portion or most or all of its heat energy requirements from the contaminated synthetic aromatic heat transfer fluid, the regenerated synthetic aromatic heat transfer fluid, and / or a combination thereof. Similarly, the synthetic aromatic heat transfer fluid regeneration assembly of the present invention can include a split reboiler that receives at least a portion or most or all of its heat energy requirements from the contaminated synthetic aromatic heat transfer fluid, the regenerated synthetic aromatic heat transfer fluid, and / or a combination thereof. Additionally, an external heat source can also be used, for example, an electric heater can also be used as the heat source for the reboiler.

[0113] For purposes of illustration and description, the foregoing description of various embodiments of the present invention has been made. The description is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Given the above teachings, various modifications and variations are possible. The embodiments discussed have been selected and described to provide the best illustration of the principles of the invention and its practical application, so that one of ordinary skill in the art can utilize the invention in various embodiments and make various modifications suitable for the particular purposes contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth fairly, legally, and equitably accorded.

Claims

1. A method for regenerating a contaminated synthetic aromatic heat transfer fluid from a heat transfer system, the heat transfer system including a contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop, the method comprising the steps of: (a) Transfer at least a portion of the contaminated synthetic aromatic heat transfer fluid from the heat transfer system to form a feed stream comprising the contaminated synthetic aromatic heat transfer fluid; and (b) Pass the feed stream comprising the transferred contaminated synthetic aromatic heat transfer fluid to a synthetic aromatic heat transfer fluid regeneration assembly comprising a dividing wall distillation column to form a side draw stream, a light ends distillate stream, and a heavy ends distillate stream.

2. The method according to claim 1, wherein the heat transfer system is an operating heat transfer system comprising a circulating contaminated synthetic aromatic heat transfer fluid in the heat transfer loop, and the collecting step (a) comprises transferring at least a portion of the circulating contaminated synthetic aromatic heat transfer fluid from the heat transfer system to form a transferred contaminated synthetic aromatic heat transfer fluid stream.

3. The method according to claim 1, wherein the synthetic aromatic heat transfer fluid regeneration assembly is a releasably connected synthetic aromatic heat transfer fluid regeneration assembly, and the method further comprises, prior to step (b), connecting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly to the heat transfer system.

4. The method according to claim 3, further comprising disconnecting the releasably connected synthetic aromatic heat transfer fluid regeneration assembly from the heat transfer system.

5. The method according to claim 1, further comprising accumulating at least one of the light ends distillate stream and the heavy ends distillate stream in at least one isolation reservoir.

6. The method according to claim 5, comprising accumulating the light ends distillate stream in a light ends isolation reservoir and accumulating the heavy ends distillate stream in a heavy ends isolation reservoir.

7. The method according to claim 1 or 2, further comprising returning at least a portion of the material from the side draw stream to the heat transfer system.

8. A synthetic aromatic heat transfer fluid regeneration assembly, the assembly comprising: (a) A fluid connector for fluidly connecting the synthetic aromatic heat transfer fluid regeneration assembly to a heat transfer system comprising a contaminated synthetic aromatic heat transfer fluid contained in a heat transfer loop; and (b) A dividing wall distillation column fluidly connected to the fluid connector and comprising a side draw outlet.

9. The synthetic aromatic heat transfer fluid regeneration assembly according to claim 8, further comprising (c) at least one light ends isolation reservoir fluidly connected to the dividing wall distillation column; and (d) at least one heavy ends isolation reservoir fluidly connected to the dividing wall distillation column.

10. The synthetic aromatic heat transfer fluid regeneration assembly according to claim 9, wherein the fluid connector (a) is a releasable fluid connector.

11. The synthetic aromatic heat transfer fluid regeneration assembly according to claim 9, wherein the at least one light ends isolation reservoir comprises an isolation condenser, or the at least one heavy ends isolation reservoir comprises an isolation reboiler.

12. The synthetic aromatic heat transfer fluid regeneration assembly according to claim 9, wherein the dividing wall distillation column, the at least one light boil-off isolation reservoir, and the at least one heavy boil-off isolation reservoir together form a separate modular unit.

13. A heat transfer assembly, said assembly comprising (a) a heat transfer system including a contaminated synthetic aromatic heat transfer fluid contained within a heat transfer loop; and (b) a synthetic aromatic heat transfer fluid regeneration assembly fluidly connected to the heat transfer system; wherein the heat transfer fluid regeneration assembly includes a dividing wall distillation column.

14. The heat transfer assembly according to claim 13, wherein the heat transfer assembly is an operating heat transfer assembly that includes a first portion of contaminated synthetic aromatic heat transfer fluid circulating in the heat transfer loop and a second portion of contaminated synthetic aromatic heat transfer fluid flowing into the synthetic aromatic heat transfer fluid regeneration assembly.

15. The heat transfer assembly according to claim 13, wherein the heat transfer fluid regeneration assembly further includes a releasable fluid connector that releasably connects the heat transfer fluid regeneration assembly to the heat transfer loop.

16. The heat transfer assembly according to claim 13, further including at least one light boil-off isolation reservoir fluidly connected to the dividing wall distillation column and at least one heavy boil-off isolation reservoir fluidly connected to the dividing wall distillation column.

17. The heat transfer assembly according to claim 16, wherein the at least one light boil-off isolation reservoir includes an isolation condenser or the at least one heavy boil-off isolation reservoir includes an isolation reboiler.

18. The heat transfer assembly according to claim 16, wherein the dividing wall distillation column, the at least one light boil-off isolation reservoir, and the at least one heavy boil-off isolation reservoir together form a separate modular unit.

19. The heat transfer assembly according to claim 13, further including a regenerated synthetic aromatic return line releasably connected to the heat transfer loop.

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