Distillation heating system and method

Abstract

Distillation systems and methods for distillation are provided. The distallation system can include a heat pump cycle whereby high-temperature process heat is simultaneously generated while facilitating distillation. Compressor energy can be recovered as process heat, thereby eliminating energy wastage.

Description

DISTILLATION HEATING SYSTEM AND METHODGOVERNMENT LICENSE RIGHTS

[0001] This invention was made with government support under Cooperative Agreement No. EEC- 1647722 awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUNDField of the Invention

[0002] Embodiments of the present invention generally relate to distillation systems and methods for distillation. More particularly, embodiments of the present invention relate to systems and methods for recovering compressor energy as process heat in heat pump assisted distillation (HEAD) methods, thereby eliminating energy wastage in thermal separation processesDescription of the Related Art

[0003] Distillation processes are extensively used in the chemical sector and consume a significant amount of process heat. Heat pumping and recuperation have been recognized as pivotal technologies in attaining the objectives of process heat decarbonization. These technologies can efficiently upgrade low-quality process heat to meet the heat requirements of various unit operations. In the context of distillation, heat pumps are particularly attractive owing to the availability of waste heat at the condenser location. Additionally, this waste heat aligns quantitatively with the heat demand at the reboiler location for most mixtures separated through distillation, characterized by low to moderate component boiling point differences.

[0004] Vapor Compression Heat Pumps (VCHPs) enhance the thermal quality of heat from the condenser through the operation of compressors to fulfill the energy demand of thereboiler at higher temperatures. In the majority of existing Heat Pump Assisted Distillation (HP AD) systems, the coefficient of performance (COP) typically falls within the range of 3 to 7, where COP is the amount of heat rejected to the high temperature heat sink per unit of electricity fed to the compressor. By way of comparison, heat pumps commonly used for air conditioners have a typical COP of about 2-6, and refrigerators have a typical COP of around 2-4. Consequently, the compressors consume a considerable amount of electricity, while transferring heat between the condenser and reboiler. Typically, the energy consumed in the form of electricity is dissipated into the cooling water as heat. During this process, the exergy of the high-quality energy form, namely electricity, is entirely lost and wasted.

[0005] A Mechanical Vapor Recompression (MVR) system is a type of HP AD system. FIG. 1 depicts a prior art Mechanical Vapor Recompression (MVR) system that rejects heat to a cold utility fluid, identified as “CU” in FIG. 1. The process involves the separation of a process feed stream 100 in a distillation column, yielding products - distillate 110A and residue 120A. The separation within the column is driven by introduction of liquid reflux HOB to the top of the column and vapor boilup 120B to the bottom of the column. The column top or overhead vapor 101 acts as the working fluid in this heat pump loop. The vapor stream 101 exiting the column top is preheated before entering the compressor resulting in stream 102 to prevent any liquid formation. The preheated vapor stream 102 is compressed to provide a compressed vapor stream 103 that is condensed in a reboiler by exchanging heat with the column bottoms liquid stream 108, thereby vaporizing the bottoms liquid 108 to provide vapor boilup 120B to the column. The condensed liquid 104 exiting the reboiler is subcooled by pre-heating the column overhead / compressor inlet stream 101 in a heat exchanger. The heat, approximately equivalent to the work added to the compressor, is discharged by the subcooled liquid 105 to the cold utility after superheating the compressor inlet vapor 102. The resulting liquid stream 106 can be throttled to the original columnpressure. A part of the lower-pressure stream 107 is recycled back to the column as reflux HOB, while the remainder is extracted as distillate product 110A. The residue product stream 120A, which typically has a higher temperature than the feed 100, is assumed to preheat the feed before entering the column. This heat exchange further aligns the condenser and reboiler duties, ensuring a more efficient heat pump operation.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. It is emphasized that the figures are not necessarily to scale and certain features and certain views of the figures can be shown exaggerated in scale or in schematic for clarity and / or conciseness.

[0007] FIG. 2 depicts an improved MVR System with process heat generation following reboiler heat exchange, according to one or more embodiments provided herein.

[0008] FIG. 3 depicts another improved MVR system that features process heat generation post-compression and preceding the reboiler, according to one or more embodiments provided herein.

[0009] FIG. 4 depicts a bottom flashing (BF) configuration with concurrent process heat generation, according to one or more embodiments provided herein.

[0010] FIG. 5 depicts an illustrative system for process heat generation using an external cycle vapor compression heat pump employing a working fluid, according to one or more embodiments provided herein.

[0011] FIG. 6 depicts another illustrative system for heat generation using an external cycle vapor compression heat pump employing water as the working fluid, according to one or more embodiments provided herein.

[0012] FIG. 7 depicts a Feed Split - Double Effect Distillation employing an MVR cycle featuring process heat generation post-compression and preceding the reboiler, according to one or more embodiments provided herein.

[0013] FIG. 8 is a bar chart depicting the achievable flow rate and temperature of the steam produced by harnessing the process heat extracted using the configurations depicted in FIGs. 2-6 6 for the aromatic separation example in TABLE 2, according to one or more embodiments provided herein.

[0014] FIG. 9 plots the variation in achievable steam flow rate versus temperature by operating the distillation column in the configuration depicted in FIG. 3 at different pressures, according to one or more embodiments provided herein.SUMMARY OF THE INVENTION

[0015] Distillation systems and methods for producing process heat while simultaneously facilitating separation processes are provided herein. In at least one embodiment, the method comprises: removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column; compressing a working fluid; at least partially condensing a portion of the compressed working fluid; and extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both.

[0016] In another embodiment, the method comprises: removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column, wherein at least a portion of the liquid stream becomes a working fluid forconveying heat from the condenser to the reboiler; throttling the working fluid to a lower pressure to provide a lower-pressure working fluid; vaporizing the lower-pressure working fluid using heat transferred from the vapor stream; compressing the vaporized working fluid; at least partially condensing a portion of the compressed working fluid; extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both; separating a liquid fraction from the at least partially condensed working fluid; and returning the separated liquid fraction to the condenser.

[0017] In another embodiment, the method comprises: providing a column, reboiler and condenser; removing a vapor stream from an upper portion of the column, at least partially condensing a portion of the vapor stream within the condenser; removing a liquid stream from a bottom portion of the column; at least partially vaporizing a portion of the liquid stream within the reboiler; circulating an external working fluid through the reboiler and the condenser to convey heat from the condenser to the reboiler while vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column; compressing the vaporized working fluid; extracting latent heat from at least partially condensing the compressed working fluid to generate process heat, steam, or both; further condensing the compressed working fluid by transferring heat to the liquid stream from the bottom portion of the column; and throttling the condensed working fluid prior to vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column.DETAILED DESCRIPTION

[0018] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are providedmerely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure can repeat reference numerals and / or letters in the various embodiments and across the FIGs. provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations. Moreover, the exemplary embodiments presented below can be combined in any combination of ways, i.e., any element from one exemplary embodiment can be used in any other exemplary embodiment, without departing from the scope of the disclosure.

[0019] Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities can refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function.

[0020] Furthermore, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” The phrase “consisting essentially of’ means that the described / claimed composition does not include any other components that will materially alter its properties by any more than 5% of that property, and in any case does not include any other component to a level greater than 3 mass%.

[0021] Unless otherwise indicated, all numerical values are "about" or "approximately" the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art. It should also be understood that the precise numerical values used in the specification and claims constitute specific embodiments. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measured data inherently containsa certain level of error due to the limitation of the technique and / or equipment used for making the measurement.

[0022] The term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

[0023] The indefinite articles “a” and “an” refer to both singular forms (i.e., “one”) and plural referents (i.e., one or more) unless the context clearly dictates otherwise. For example, embodiments using “an olefin” include embodiments where one, two, or more olefins are used, unless specified to the contrary or the context clearly indicates that only one olefin is used.

[0024] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions, when the information in this disclosure is combined with publicly available information and technology.

[0025] The distillation system can be a HP AD system. The term “HP AD system”, as used herein, refers to and includes any system utilizing a heat pump or heat pump loop or cycle, including but not limited to, Mechanical Vapor Recompression (MVR), Bottom Flashing (BF), and External Vapor Compression. As used herein, the term “process heat” refers to any thermal energy generated from and / or demanded for heating, drying, distillation, and / or chemical reaction. Examples of suitable HP AD systems include those used in various chemical,petrochemical, pharmaceutical, agrochemical, and food and beverage industries. Particularly suitable HPAD systems include those for separating ethanol- water mixtures, purifying Benzene, Toluene, and Xylene (BTX), as well as fractionation systems for refining and / or upgrading crude oil and petrochemicals among other fluids that can be separated using a heat separation process. For example, Table 1 lists various industries that could employ any of the one or more HPAD systems and methods for distillation described herein.

[0026] Table 1: Heat Pumped Distillation system application for multiple industries

[0027] FIG. 2 depicts an improved MVR system with process heat generation following reboiler heat exchange, according to one or more embodiments. As shown in FIG. 2, a process feed stream 100 is fed to the distillation column where it is separated to provide the distillate 110A and the residue 120A. The separation within the column is driven by introduction of a liquid reflux HOB to the top of the column and a vapor boilup 120B to the bottom of the column. All or a portion of the vapors 201 from the column top can be mixed with recycle vapor 209 from a phase separator to provide a combined vapor stream 210, which serves as the working fluid.

[0028] In this configuration, process heat can be produced by harnessing both latent and sensible heat energy of a condensed liquid 204 following heat exchange within the reboiler tovaporize the bottoms liquid stream 208, resulting in a cooled liquid stream 211. After the process heat extraction, the liquid stream 211 can be further subcooled by transferring heat to the working fluid vapor stream 210 providing a superheated compressor inlet stream 202, and a subcooled liquid stream 205. The superheated vapor stream 202 can be compressed. The compressed vapor stream 203 can exchange heat with the liquid bottoms stream 208 within the reboiler to provide the vapor boilup stream 120B and the condensed liquid stream 204.

[0029] The subcooled liquid stream 205 can be throttled to produce a lower pressure, two- phase fluid within stream 207 that can be separated in a phase separator to provide the vapor stream 209 and a liquid fraction. The liquid fraction can be recycled back to the column as reflux HOB and / or extracted as distillate product 110A, and the vapor portion 209 can be recycled in the heat pump loop. Any conventional manual or automated control valve such as globe valves, butterfly valves, and the like, can be used to throttle the subcooled liquid 205.

[0030] By “throttled” or “throttling”, as used throughout, it is meant that the pressure and / or temperature of the fluid is decreased by at least 1%, 2%, 5%, 10%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, or 95%. In some cases, the reduction can range from a low of about 1%, 2%, or 5% to a high of about 80%, 90%, or 99%. In some cases, the reduction can range from a low of about 1%, 5%, or 15% to a high of about 60%, 70%, or 80%. In some cases, the reduction can be about 15% to about 85%; about 20% to about 95%; about 5% to about 65%; about 10% to about 88%; or about 2% to about 40%.

[0031] FIG. 3 depicts another improved MVR system that features process heat generation post-compression and preceding the reboiler, according to one or more embodiments. Similar to the MVR system of FIG. 2, all or a portion of the vapors 301 from the column top can be mixed with a recycle vapor 309 from a phase separator to provide a combined vapor stream 310, which serves as the working fluid. In this configuration, process heat can be extracted from the compressed vapor stream 303 upstream of the reboiler. Extracting heat from thecompressed vapor stream 303 at least partially condenses the fluid therein to provide a partially condensed stream 312. In addition to the sensible heat that can be extracted from the working fluid, the latent heat can be extracted to provide higher temperature heat, which can be used to generate higher temperature and higher quality steam for use in the same processing unit or elsewhere in the facility.

[0032] The liquid bottoms stream 308 can be heated by the partially condensed stream 312, within the reboiler, and returned to the column as the boilup stream 120B. Heat transfer from the partially condensed stream 312 within the reboiler can result in complete condensation, resulting in a saturated liquid stream 304. The saturated liquid stream 304 can be used to heat the (recycling) vapor stream 310 to provide a superheated vapor stream 302 that is fed to the compressor. Due to limited subcooling of the high-pressure liquid stream 305, throttling the liquid stream 305 produces significant vapor flow in stream 307, resulting in an increased vapor fraction in recycle stream 309. This slightly raises the compressor workload but surprisingly results in improved process heat quality (temperature) and quantity.

[0033] FIG. 4 depicts a bottom flashing configuration with concurrent process heat generation, according to one or more embodiments. In this bottom flashing (BF) configuration, instead of compressing the top vapors to supply heat to the reboiler, all or a portion of the bottom liquid 413 from the stripping section can be mixed with recycle liquid 435 and throttled to a lower pressure, thereby acting as the working fluid in the heat pump loop. The mixed working fluid (bottom liquid + recycle) 414 can be subcooled in a heat exchanger while superheating the compressor inlet stream 418. The subcooled liquid 415 can be throttled to a lower pressure to provide a lower-pressure fluid stream 416 that can be vaporized by the condensation of the column top vapor stream 401 in the “condenser” heat exchanger. The condensate from the column top vapor stream 401 can be returned to column as reflux within the condensed stream HOB. The vaporized stream 417 can be superheated and compressedbefore extracting process heat by partial condensation of the compressed vapor 419, providing a two-phase fluid stream 420. The two-phase fluid 420 can be passed through a phase separator. The vapor part 120B can be provided as boilup back to the column, and the liquid part 435 can be recycled in the heat pump loop. In this configuration as well, the extracted process heat includes both sensible heat and latent heat from the partial condensation of the compressed vapor, thereby providing higher temperature heat, which can be used to generate higher temperature and higher quality steam for use in the same processing unit or elsewhere in the facility.

[0034] FIG. 5 depicts an illustrative system for heat generation using an external cycle vapor compression heat pump employing an external heat transfer fluid and the working fluid according to one or more embodiments. Any suitable heat transfer fluid can used, such as, for example R-602, R-601a, R-601, R-718, water, steam and the like. The lower-pressure saturated vapor stream 521 can be superheated before compression by exchanging heat with the returning high-pressure liquid stream 525. Process heat can be extracted from the compressed vapor 523 through partial condensation of the same. In this configuration as well, the extracted process heat includes both sensible heat and latent heat from the partial condensation of the compressed vapor, thereby providing higher temperature heat, which can be used to generate higher temperature and higher quality steam for use in the same processing unit or elsewhere in the facility.

[0035] The partially condensed fluid or two-phase fluid in stream 524 can be converted to high pressure saturated liquid 525 in the reboiler heat exchanger. This high-pressure fluid can be subcooled, while superheating the compressor inlet fluid 522. The subcooled liquid 526 can be throttled to a lower pressure, resulting in a two-phase fluid stream 527 with a lower temperature. The two-phase fluid in stream 527 can be vaporized in the condenser heat exchanger resulting in the initial lower-pressure saturated vapor stream 521.

[0036] FIG. 6 depicts a specific example of heat generation using an external cycle vapor compression heat pump, where water serves as the working fluid, according to one or more embodiments. The majority of the components in this system function similarly to those in the external vapor compression system depicted in FIG. 5. In this embodiment, steam can be generated by incorporating a saturation drum. The compressed vapor 623, typically in a superheated state, can be converted to a saturated vapor 629 through the addition of saturated liquid water 637 in a saturation drum. The vaporization of the excess water results in excess steam generation, which can be extracted and utilized elsewhere via stream 628.

[0037] One advantage of employing an external loop or heat pump cycle, as in FIGs. 5 and 6, is the flexibility to choose a working fluid for the heat pump cycle according to source and sink operating conditions. The selection of a working fluid can also consider additional requirements such as thermal efficiency, safety, chemical stability, environmental impact etc. External heat pump cycles also can be effectively and safely utilized even in cases where the feed to the distillation system is corrosive or highly flammable, providing another significant advantage.

[0038] FIG. 7 depicts another illustrative system that includes process heat generation with a mechanical vapor recompression system heat pump in a feed split double effect distillation according to one or more embodiments. In this embodiment, the feed 100 can be split, in any ratio, into two fractions, serving as feeds to two separate distillation columns - low-pressure column feed 731 and high-pressure column feed 732. The condenser of the high-pressure columns can supply heat to the reboiler of the low-pressure column thereby generating vapor boilup for the low-pressure column. The heat pump loop, operating between the condenser of the low-pressure column and the reboiler of the high-pressure column, can utilize the top vapors 701 from the low-pressure column as the working fluid and provide the boilup stream 720B for the high-pressure column.

[0039] The heat pump components and streams in this system function analogously to the process detailed in FIG. 3, where all or a portion of the vapors 701 from the column top can be mixed with a recycle vapor 709 from a phase separator to provide a combined vapor stream 710, which serves as the working fluid. The liquid bottoms stream 708 can be heated by the partially condensed stream 712, within the reboiler, and returned to the column as the boilup stream 720B. Heat transfer from the partially condensed stream 712 within the reboiler can result in complete condensation, resulting in a saturated liquid stream 704. The saturated liquid stream 704 can be used to heat the (recycling) vapor stream 710 to provide a superheated vapor stream 702 that is fed to the compressor. Due to limited subcooling of the high-pressure liquid stream 705, throttling the liquid stream 705 produces significant vapor flow in stream 707, resulting in an increased vapor fraction in recycle stream 709. This slightly raises the compressor workload and surprisingly results in improved process heat quality (temperature) and quantity.

[0040] As explained above with reference to FIG. 3, process heat can be extracted from the compressed vapor stream 703 upstream of the reboiler. Extracting heat from the compressed vapor stream 703 at least partially condenses the fluid to provide a partially condensed stream 712. In this arrangement, both sensible heat and latent heat can be extracted to provide significantly higher temperature heat, which could be used to generate higher temperature and higher quality steam for use in the same processing unit or elsewhere in the facility.

[0041] Another significant advantage of this configuration is the decrease in reboiler duty resulting from the column integration. However, the compression ratio of the heat pump increases due to the increased temperature difference between the heat source and the heat sink.

[0042] For simplicity and ease of description, the various configurations described above and depicted in FIGs. 2-7 make reference to a distillation column. The columns depicted inFIGs. 2-7 could be any tray and / or packed column, and could be any one or more distillation, stripping, and / or extraction columns, or a series of any combination thereof.

[0043] Still referring to FIGs. 2-7, the feed stream 100 can be any liquid mixture or gas mixture. In one particular embodiment, the feed stream 100 can be or can include a mixture of hydrocarbons, a raw shale gas or raw natural gas, or other raw hydrocarbon(s). The feed stream 100 that can be obtained from a reservoir, wellhead, or pipeline. Illustrative gas mixtures can be or can include coal gas. For simplicity and ease of description, the terms “shale gas” and “natural gas” refer to any gas phase mixture containing at least 50 mol% methane and at least 5 mol% natural gas liquids (NGLs), i.e. ethane, butane, propane and pentane.

[0044] Embodiments discussed and described herein can be further described with the following examples. Although the following examples are directed to specific embodiments, they are not to be viewed as limiting in any specific respect.EXAMPLES

[0045] Several simulations are provided to evaluate compressor work used to generate process heat or steam from the various distillation systems and processes described above with reference to FIGs. 2-7. In the following simulations, process heat is used to generate steam. However, it should be noted that the utility of the process heat is not limited to this specific application. The process heat can be applied at any alternative location and / or for any other industrial, commercial, or residential process requiring thermal energy. For purposes of these simulations, the temperature of the generated process heat in all cases is significantly more than the condenser temperature and, in most instances, near or above the reboiler temperature.

[0046] In the presented case studies, it is assumed that the entering water and exiting steam in the steam generation process are in saturated phase, and a Minimum Approach Temperature(MAT) of 5 °C is maintained in all heat exchangers. The compressors are assumed to operate at 75% isentropic efficiency.

[0047] The amount of steam that can be recovered from a given configuration depends on the enthalpy of the incoming feed, outgoing products and the compressor power. Generally, if the feed is a saturated liquid, the amount of generated steam enthalpy flow is lower than the compressor power. However, increasing the vapor fraction of the feed could enable the recovery of steam energy flow higher than the compressor power. In all the cases simulated, the feed is a saturated liquid and the amount of steam recovered is less than the compressor power input.

[0048] In the simulations , separation of a 4-component equimolar feed consisting of Benzene, Toluene, p-Xylene, and o-Xylene was evaluated. The feed is assumed to be a saturated liquid. In all cases, the primary aim of the distillation column is set to be the separation of Benzene and Toluene from the Xylenes. Hence, the distillate is an equimolar mixture of Benzene-Toluene and similarly, the bottoms residue is an equimolar mixture of p- Xylene and o-Xylene. The feed flow rate is specified as 2 kmol / hr, and the column is assumed to be operating at the pressure of 1 atm. The column contains 50 stages with the feed stage being 25 in all simulations. The flowrates, compositions and temperatures of the feed, distillate and residue stream are summarized in Table 2. Table 3 shows the operating conditions and compositions of certain streams within the processes depicted in Figs. 1 -6. The simulations were conducted in ASPEN Plus VI 1 unless stated otherwise.

[0049] Table 2: Specifications of the feed, distillate, and residue streams for the distillation column in the case studies.

[0050] Table 3: Operating conditions and stream compositionsCOMPARATIVE EX. 1:

[0051] The prior art depicted in FIG. 1 is considered the benchmark scenario where all the added electrical power is lost to cooling water. In this configuration, the condenser and reboiler duties are 74.74 and 72.83 MJ / hr, respectively, and a temperature lift of approximately 55 °C is required to utilize the condenser heat at the reboiler location. The energy required by the compressor to achieve this temperature lift amounts to 14.57 Ml / hr. The cycle operates at a COP of 5. No steam is generated in the CU when used to cool stream 105.

[0052] Table 4: Major Stream Information for MVR heat pump as depicted in FIG. 1.EX. 2:

[0053] Referring again to FIG. 2 that depicts an improved Mechanical Vapor Recompression System with process heat generation following reboiler heat exchange, where the vapors from the column top serve as the working fluid in the heat pump cycle, and steam is generated by harnessing the sensible heat from the condensed liquid following heat exchange with the reboiler, and prior to superheating the vapor. The electrical energy consumption of the compressor remains substantially unchanged at 15 MJ / hr. Due to the use of sensible heat for steam generation, the resulting steam temperature is relatively lower, simulated at 108.4°C, with a corresponding steam flow rate of 0.42 kmol / hr.

[0054] Table 5: Major Stream Information for MVR heat pump with process heat generation after reboiler heat exchange as depicted in Fig 2.EX. 3:

[0055] Referring again to FIG. 3 that depicts another improved Mechanical Vapor Recompression system utilizing process heat generation post-compression and preceding the reboiler. As explained above, this configuration generates steam and utilizes latent heat through partial condensation of the compressed vapor before heat rejection to the reboiler. With the reboiler heated by a partially condensed stream, the vapor recycle increases, thereby raising the compressor workload. Consequently, the electricity consumption of the compressor increases to 17.88 MJ / hr. As a result of increased compressor energy consumption, the quantity of steam generated also rises, reaching 0.52 kmol / hr, while the temperature of the steam increases to 147 °C.

[0056] Table 6: Major Stream Information for MVR heat pump with process heat generation before reboiler heat exchange as depicted in FIG. 3.EX. 4:

[0057] Referring again to FIG. 4 that depicts a bottom flashing configuration with concurrent process heat generation is simulated. In this configuration, the liquid from the bottom of the column acts as the working fluid in the heat pump cycle, and steam is generated after the compression of working fluid. To maintain the specified MAT, the bottom liquid must be throttled to a pressure of 0.18 atm. The electrical energy consumption of the compressor in this configuration is 16.88 Ml / hr. In this arrangement, the majority of the steam is produced through the de-superheating of the compressed vapor, resulting in a steam flow rate of 0.48 kmol / hr and a steam temperature of 136.1 °C.

[0058] Table 7: Major Stream Information for BF heat pump with process heat generation as depicted in FIG. 4.Ex. 5:

[0059] The configuration depicted in FIG. 6, using water as the working fluid, is simulated with operational pressures set at a lower pressure of 0.62 atm and a compressed pressure of 4.24 atm. The electricity consumption of the compressor undergoes a notable increase, reaching 20.92 MJ / hr. It should be noted that as the Minimum Approach Temperature (MAT) constraints for steam generation are eliminated in this setup, it allows for the production of 0.58 kmol / hr of high-quality steam at 146.1 °C.

[0060] Table 8: Major Stream Information for External Heat Pump with water as working fluid as depicted in FIG. 6.Ex. 6:

[0061] Referring again to the configuration of FIG. 7 that depicts a Feed Split - Double Effect Distillation employing an MVR cycle featuring process heat generation postcompression and preceding the reboiler. The feed is split in a 51:49 ratio between the low- pressure (LP) and the high-pressure (HP) column respectively to match the HP condenser duty to the LP reboiler duty. The LP and HP columns operate at 1 atm and 3.8 atm, respectively, to maintain MAT of 5 °C between the reboiler of the former and condenser of the latter. This setup utilizes a heat pump cycle similar to the one illustrated in FIG. 3, operating between the condenser of the LP column (Duty = 38.68 MJ / hr) and the reboiler of the HP column (Duty =42. 11 MJ / hr). In a double-effect system, the heat duty to be transferred typically decreases by approximately 50%. However, this reduced load is offset by the increase in temperature lift for the heat pump. This configuration is particularly attractive because the temperature of the steam generated is directly linked to the reboiler temperature. Within the HP cycle, the vapor from the top column is compressed to 11.6 atm to provide heat to the reboiler. A substantial recycle vapor flow rate is necessary due to a significant decrease in latent heat at high pressure. Steam is generated at 207.8°C with the compressor electric power consumption at 24.12 MJ / hr. Consequently, the attainable steam flow rate is 0.60 kmol / hr. The technology mentioned above can be extended to any Multi-effect Distillation systems with 2 or more heat integrated columns operating at different pressures.

[0062] Table 9: Stream Information for the Feed Split Double Effect Distillation system as depicted in Fig 7.

[0063] Table 10: Additional Stream Information for the Feed Split Double EffectDistillation system depicted in Fig 7.

[0064] FIG. 8 is a bar chart depicting the achievable flow rate and temperature of steam produced by harnessing the extracted process heat. It was surprisingly discovered that higher-quality heat could be achieved by operating at pressures above ambient levels, instead of limiting the distillation column to operate at atmospheric pressure. This leads to an increase in both the reboiler and condenser temperatures, consequently producing high- quality steam.

[0065] Table 11 shows the compressor power (MJ / hr) and the enthalpy of steam (MJ / hr) generated in the case studies:

[0066] FIG. 9 demonstrates the variation in steam flow rate and temperature in the configuration shown in FIG. 3 (EX. 3) in relation to the pressure of the column. At higherpressures, the quality of steam improves; however, simultaneously, the steam flow rate increases, leading to higher electricity consumption. Furthermore, there is no constraint on operating the heat pump cycle exclusively between the condenser and the reboiler of the same column.

[0067] As shown by the results of the simulations above, it should be appreciated that integrating a separation process with process heat can yield substantial benefits compared to carrying out these processes independently. For example, the steam enthalpy in Table 11 shows the amount of electricity required to generate the same amount of steam as in the example case studies using resistance / induction heating in the kettle reboiler. In the examples corresponding to the technologies represented in FIGs. 2, 3, 4, and 6, the enthalpy of the steam recovered exceeds the power consumption of the compressor. This is attributed to the condenser duty of the column being greater than the reboiler duty, resulting in additional available thermal energy for steam generation. It should be noted that, in all cases, the enthalpy of the steam recovered is equal to the sum of the compressor power and the enthalpy difference between the condenser and the reboiler (condenser duty - reboiler duty).

[0068] It also should be appreciated that steam can be generated by providing 5-20% more electricity to the compressor in the configurations of FIGs. 2 and 3, as compared to the prior art configuration of FIG. 1 , while simultaneously powering distillation system.

[0069] It also should be appreciated that these technologies can be readily extended to multi-component distillation arrangements. For instance, in a Petlyuk type Dividing Wall Column, the condenser of the lightest component and the reboiler of the heaviest component can be integrated via a heat pump. In a multi-component distillation containing more than one distillation column, energy from the condenser of one column can be pumped to the reboiler of a different column. In multi-component distillation, due to higher temperature lifts andconsequently higher compressor power requirements, steam generation technologies have the potential to significantly enhance the overall efficiency of the plant.

[0070] Other specific embodiments provided herein further include any one or more of the following numbered embodiments:

[0071] Embodiment 1 : A method for distillation, comprising removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column; compressing a working fluid; at least partially condensing a portion of the compressed working fluid; and extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both.

[0072] Embodiment 2: The method according to embodiment 1, wherein the working fluid is the vapor stream from the upper portion of a distillation column.

[0073] Embodiment 3 : The method according to embodiment 1 , wherein the working fluid is the liquid stream from the bottom portion of the column

[0074] Embodiment 3 : The method according to embodiment 1 , wherein the working fluid is an external heat transfer fluid.

[0075] Embodiment 4: The method according to any embodiment 1 to 3, wherein compressing the working fluid occurs prior to entering a reboiler.

[0076] Embodiment 5 : The method according to any embodiment 1 to 4, wherein the latent heat is extracted from the at least partially condensed working fluid upstream of the reboiler

[0077] Embodiment 6: The method according to any embodiment 1 to 5, wherein the latent heat is extracted from the at least partially condensed working fluid downstream of the reboiler.

[0078] Embodiment 7 : The method according to any embodiment 1 to 6, wherein the distillation column is operated at above ambient pressure.

[0079] Embodiment 8: The method according to any embodiment 1 to 7, wherein compressor work is substantially equal to the extracted heat.

[0080] Embodiment 9: The method according to any embodiment 1 to 8, wherein a condenser is configured to exchange heat between the working fluid upstream of the reboiler and the working fluid downstream of the reboiler, wherein the working fluid upstream of the reboiler has a temperature greater than that of the working fluid downstream of the reboiler.

[0081] Embodiment 10: The method according to any embodiment 1 to 9, further comprising throttling the working fluid downstream of the reboiler to create a two phase fluid.

[0082] Embodiment 11: The method according to embodiment 10, further comprising separating the two phase fluid into a gas phase and a liquid phase; mixing the gas phase with the vapor stream from the upper portion of the column; and recycling at least a portion of the liquid phase to the column.

[0083] Embodiment 12: The method according to embodiment 11, further comprising recovering at least a portion of the liquid phase as a distillate product.

[0084] Embodiment 13: The method according to embodiment 1, wherein at least a portion of the vapor stream is the working fluid, the working fluid is compressed; and at least partially condensed whereby latent heat from the at least partially condensed working fluid is extracted and used to generate process heat, steam, or both.

[0085] Embodiment 14: The method according to embodiment 13, wherein the latent heat is extracted from the at least partially condensed vapor stream downstream of the reboiler or upstream of the reboiler, or both.

[0086] Embodiment 15: The method according to embodiments 13 or 14, wherein the distillation column is operated at above ambient pressure, and wherein compressor work is substantially equal to the extracted heat.

[0087] Embodiment 16: A method for distillation, comprising: removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column, wherein at least a portion of the liquid stream becomes a working fluid for conveying heat from the condenser to the reboiler; throttling the working fluid to a lower pressure to provide a lower-pressure working fluid; vaporizing the lower-pressure working fluid using heat transferred from the vapor stream; compressing the vaporized working fluid; at least partially condensing a portion of the compressed working fluid; extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both; separating a liquid fraction from the at least partially condensed working fluid; and returning the separated liquid fraction to the condenser.

[0088] Embodiment 17: The method according to embodiment 16, wherein at least a portion of the vapor stream from the upper portion of the column is condensed and fed back to the upper portion of the column and at least a portion of the vaporized working fluid is fed to the bottom portion of the column.

[0089] Embodiment 18: A method for distillation, comprising: providing a column, reboiler and condenser; removing a vapor stream from an upper portion of the column, at least partially condensing a portion of the vapor stream within the condenser; removing a liquid stream from a bottom portion of the column; at least partially vaporizing a portion ofthe liquid stream within the reboiler; circulating an external working fluid through the reboiler and the condenser to convey heat from the condenser to the reboiler while vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column; compressing the vaporized working fluid; extracting latent heat from at least partially condensing the compressed working fluid to generate process heat, steam, or both; further condensing the compressed working fluid by transferring heat to the liquid stream from the bottom portion of the column; and throttling the condensed working fluid prior to vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column.

[0090] Embodiment 19: The method according to embodiment 18, wherein the working fluid is water.

[0091] Embodiment 20: The method according to embodiments 18 or 19, wherein the working fluid is selected from the group consisting of R-602, R-601a, R-601, R-718, water, and steam.

[0092] All patents and patent applications, test procedures (such as ASTM methods, UL methods, and the like), and other documents cited herein are fully incorporated by reference to the extent such disclosure is not inconsistent with this disclosure and for all jurisdictions in which such incorporation is permitted.

[0093] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges including the combination of any two values, e.g., the combination of any lower value with any upper value, the combination of any two lower values, and / or the combination of any two upper values are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are “about” or“approximately” the indicated value, meaning the values take into account experimental error, machine tolerances and other variations that would be expected by a person having ordinary skill in the art.

[0094] The foregoing has also outlined features of several embodiments so that those skilled in the art can better understand the present disclosure. Those skilled in the art should appreciate that they can readily use the present disclosure as a basis for designing or modifying other methods or devices for carrying out the same purposes and / or achieving the same advantages of the embodiments disclosed herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure, and the scope thereof is determined by the claims that follow.

[0095] Various terms have been defined above. To the extent a term used in a claim is not defined above, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are fully incorporated by reference to the extent such disclosure is not inconsistent with this application and for all jurisdictions in which such incorporation is permitted.

[0096] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A method for distillation, comprising: removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column; compressing a working fluid; at least partially condensing a portion of the compressed working fluid; and extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both.

2. The method of claim 1, wherein the working fluid is the vapor stream from the upper portion of a distillation column.

3. The method of claim 1, wherein the working fluid is the liquid stream from the bottom portion of the column3. The method of claim 1, wherein the working fluid is an external heat transfer fluid.

4. The method of claim 1, wherein compressing the working fluid occurs prior to entering a reboiler.

5. The method of claim 1, wherein the latent heat is extracted from the at least partially condensed working fluid upstream of the reboiler6. The method of claim 1, wherein the latent heat is extracted from the at least partially condensed working fluid downstream of the reboiler.

7. The method of claim 1, wherein the distillation column is operated at above ambient pressure.

8. The method of claim 1, wherein compressor work is substantially equal to the extracted heat.

9. The method of claim 1 , wherein a condenser is configured to exchange heat between the working fluid upstream of the reboiler and the working fluid downstream of the reboiler, wherein the working fluid upstream of the reboiler has a temperature greater than that of the working fluid downstream of the reboiler.

10. The method of claim 1, further comprising throttling the working fluid downstream of the reboiler to create a two phase fluid.

11. The method of claim 10, further comprising separating the two phase fluid into a gas phase and a liquid phase; mixing the gas phase with the vapor stream from the upper portion of the column; and recycling at least a portion of the liquid phase to the column.

12. The method of claim 11, further comprising recovering at least a portion of the liquid phase as a distillate product.

13. The method of claim 1, wherein at least a portion of the vapor stream is the working fluid, the vapor stream is compressed and at least partially condensed whereby latent heat from the at least partially condensed working fluid is extracted and used to generate process heat, steam, or both.

14. The method of claim 13, wherein the latent heat is extracted from the at least partially condensed vapor stream downstream of the reboiler or upstream of the reboiler, or both.

15. The method of claim 13, wherein the distillation column is operated at above ambient pressure, and wherein compressor work is substantially equal to the extracted heat.

16. A method for distillation, comprising: removing a vapor stream from an upper portion of a distillation column; removing a liquid stream from a bottom portion of the column, wherein at least a portion of the liquid stream becomes a working fluid for conveying heat from the condenser to the reboiler; throttling the working fluid to a lower pressure to provide a lower-pressure working fluid; vaporizing the lower-pressure working fluid using heat transferred from the vapor stream; compressing the vaporized working fluid; at least partially condensing a portion of the compressed working fluid; extracting latent heat from the at least partially condensed working fluid to generate process heat, steam, or both; separating a liquid fraction from the at least partially condensed working fluid; andreturning the separated liquid fraction to the condenser.

17. The method of claim 16, wherein at least a portion of the vapor stream from the upper portion of the column is condensed and fed back to the upper portion of the column and at least a portion of the vaporized working fluid is fed to the bottom portion of the column.

18. A method for distillation, comprising: providing a column, reboiler and condenser; removing a vapor stream from an upper portion of the column, at least partially condensing a portion of the vapor stream within the condenser; removing a liquid stream from a bottom portion of the column; at least partially vaporizing a portion of the liquid stream within the reboiler; circulating an external working fluid through the reboiler and the condenser to convey heat from the condenser to the reboiler while vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column; compressing the vaporized working fluid; extracting latent heat from at least partially condensing the compressed working fluid to generate process heat, steam, or both; further condensing the compressed working fluid by transferring heat to the liquid stream from the bottom portion of the column; and throttling the condensed working fluid prior to vaporizing the working fluid through heat exchange with the vapor stream from the upper portion of the column.

19. The method of claim 18, wherein the working fluid is water.

20. The method of claim 18, wherein the working fluid is selected from the group consisting of R-602, R-601a, R-601, R-718, water, and steam.

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