Mixed component internally cascaded heat pump for industrial manufacturing applications

Abstract

This disclosure relates to a heat pump configuration and associated method for pumping heat from multiple distinct heat sources to multiple distinct heat sinks with internal cascading. The heat pump may be used in different industrial applications, particularly in distillation systems where there are multiple low-temperature heat sources and high-temperature heat sinks.

Description

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 780,865, filed Mar. 31, 2025, the entire disclosure of which is incorporated herein by reference.STATEMENT OF GOVERNMENT RIGHTS

[0002] This invention was made with government support under EEC-1647722 awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUND

[0003] Heat pumps have been recognized as a potential technology that allows the upgradation of low-temperature heat to useful high-temperature heat. In the chemical, petrochemical, food and beverage, plastic, textile, pulp and paper, wood, metal, and pharmaceutical manufacturing plants, there are multiple sources of low-temperature heat that could be beneficially used by pumping it to higher temperatures, where it can provide heat to high-temperature heat sinks. For the chemical industry, some examples of such sources include exothermic reactors, condensers of the distillation columns, heat from process streams, a condensing process stream, solidification, etc. Some examples of such sinks are endothermic reactors, reboilers of the distillation columns, heat-to-process streams, vaporizing process streams, steam generators, absorption stripper columns, melting, etc. In the above-mentioned processes, if the low-temperature heat from the sources is not properly utilized within the plant to meet one or more energy needs and is wasted by rejection to the ambient, it results in lower process efficiency.

[0004] While heat pumps are suggested for such applications, the overall process becomes an expensive option to apply because of the use of multiple compressors. The use of multiple compressors results from the use of more than one heat pump stream at different pressures requiring compressors. A common example with multiple heat sources and heat sinks is distillation. A distillation column with an intermediate reboiler is an example of a two-heat sinks (reboiler and an intermediate reboiler) and a single-heat source (condenser). The temperature of the intermediate reboiler is between the temperature of the condenser and the reboiler. If a single compressor heat pump loop is used, heat is pumped to the highest temperature (reboiler temperature), and hence it has higher compressor power. A two-compressor heat pump loop can allow the pumping of heat at two distinct temperatures (reboiler temperature and intermediate reboiler temperature). Because of this, it has lower compressor power but a higher cost as it uses two heat pump compressors. As such, there is a need for efficient heat pump processes that can pump heat from multiple heat sources to multiple heat sinks using fewer compressors and preferably one compressor to reduce overall cost.SUMMARY

[0005] The present disclosure may comprise one or more of the following features and combinations thereof.

[0006] In one aspect, the present disclosure provides a method of pumping heat from either at least one heat source to multiple heat sinks, multiple heat sources to at least one heat sink, or multiple heat sources to multiple heat sinks. The method may comprise (i) providing a low-pressure gaseous stream of a mixed component containing two or more components with different boiling points; (ii) compressing the low-pressure gaseous stream to increase the pressure of the low-pressure gaseous stream to provide a high-pressure stream, which is predominantly a vapor or a gaseous stream; (iii) partially condensing the high-pressure stream by transferring heat to a heat sink from the high-pressure stream to provide a partially condensed two-phase stream; (iv) separating the partially condensed two-phase stream into two streams including a separated liquid stream and a separated vapor stream, wherein the separated liquid stream is eventually reduced in pressure and vaporized by heat exchange either against a heat source or a process stream; (v) condensing a stream derived from the separated vapor stream in step (iv) either by heat exchange with the process stream or by providing heat to another heat sink; (vi) reducing the pressure of the condensed stream from step (v); (vii) at least partially vaporizing the condensed stream from step (vi) by heat exchange with another heat source; (viii) mixing the vaporized stream from step (vii) with the separated liquid stream from step (iv) or with the vaporized stream from step (iv); and (ix) heating the mixed stream from step (viii) to provide the low-pressure gaseous stream of step (i).

[0007] In some embodiments, the method may further comprise (x) partially condensing the separated vapor stream from step (iv) to provide a second partially condensed two-phase stream; (xi) separating the second partially condensed two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream; (xii) completely condensing the second separated vapor stream against another heat sink to provide a condensed second separated vapor stream; (xiii) reducing the pressure of the condensed second separated vapor stream; (xiv) vaporizing the condensed second separated vapor stream from step (xiii) by transferring heat from a heat source; and (xv) mixing the vaporized stream with the separated liquid streams from each of the partial condensation steps to provide the low-pressure gaseous stream of step (i).

[0008] In some embodiments, the method may further comprise (xvi) reducing the pressure of the second separated liquid stream from step (xi); (xvii) mixing the vaporized stream from step (xiv); (xviii) vaporizing the mixed stream from step (xvii) by heat exchange with a heat source stream, (xix) mixing the combined vaporized stream with the separated liquid stream from step (iv); and (xx) vaporizing the mixed stream from step (xix) against another heat source to provide the low-pressure gaseous stream of step (i).

[0009] In some embodiments, the method may further comprise (xvi) partially condensing the second separated vapor stream from step (xi) against a heat sink to provide a third partially condensed two-phase stream; and (xi) separating the third partially condensed two-phase stream into two streams including a third separated vapor stream and a third separated liquid stream, wherein the third separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

[0010] In some embodiments, the method may further comprise (x) partially condensing the separated vapor stream from step (iv) against a heat sink to provide a second partially condensed two-phase stream; and (xi) separating the second partially condensed two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

[0011] In some embodiments, the method may further comprise (xii) condensing the second separated vapor stream in step (xi) by transferring heat from the second separated vapor stream to one of the second separated liquid stream from step (xi) and the separated liquid stream from step (iv). In some embodiments, the method may further comprise (x) dividing the separated liquid stream from step (iv) into two parts, wherein one part is reduced in pressure and vaporized against one of the heat sources.

[0012] In some embodiments, the method may further comprise (x) reducing the pressure of the separated liquid stream from step (iv); (xi) partially vaporizing the separated liquid stream against a heat source to provide a second two-phase stream; and (xii) separating the second two-phase stream into two streams, including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

[0013] In some embodiments, the heat sources and the heat sinks may be part of a chemical plant, a petrochemical plant, a food and beverage plant, a pulp and paper plant, a plastic plant, a textiles plant, or a pharmaceutical plant. In some embodiments, the heat source is an exothermic reactor, a condensing stream, a condenser of a distillation column, from a solidification of a stream, heat from a process stream that is being cooled, or waste heat. In some embodiments, the heat sink may be an endothermic reactor, a boiling liquid stream, a melting solid, a reboiler of a distillation column, stream generation, or heating of a process stream.

[0014] In some embodiments, one of the heat sources may be a condenser of a distillation column and one of the heat sinks is a reboiler of a distillation column. In some embodiments, the heat sources or heat sinks may be part of the same distillation column. In some embodiments, the heat sources or heat sinks may be part of the different distillation columns. In some embodiments, one of the heat sources may be an intermediate condenser located in a rectifying section of the distillation column and one of the heat sinks may be an intermediate reboiler located in a stripping section of the distillation column.

[0015] According to another aspect, the present disclosure provides a method of pumping heat from either a single heat source to multiple heat sinks, multiple heat sources to a single heat sink, or multiple heat sources to multiple heat sinks. The method may comprise (i) providing a low-pressure gaseous stream of a mixed component containing two or more components with different boiling points; (ii) compressing the low-pressure gaseous stream to increase the pressure of the low-pressure gaseous stream to provide a high-pressure stream, which is predominantly a vapor or a gaseous stream; (iii) completely condensing the high-pressure stream by transferring heat to a heat sink from the high-pressure stream to provide a liquid stream; (iv) reducing the liquid stream to an intermediate pressure; (v) partially vaporizing the liquid stream from step (iv) against a heat source to provide a partially vaporized two-phase stream; (vii) separating the partially vaporized two-phase stream into two streams including a separated vapor stream and a separated liquid stream; (viii) condensing a stream derived from the separated vapor stream of step (vii) against a process stream; (ix) reducing the pressure of the condensed stream from step (viii); (x) vaporizing the condensed stream from step (ix) by heat exchange with a heat source; and (xi) reducing the pressure of the separated liquid stream from step (vii) and either vaporizing the separated liquid stream by heat exchange against a heat source or a process stream, or mixing the separated liquid stream with the vaporized stream from step (x) to provide the low-pressure gaseous stream of step (i).

[0016] In some embodiments, the method may further comprise (xii) condensing a stream derived from the separated vapor stream in step (viii); (xiii) reducing the pressure of the condensed stream from step (xii); (xiv) at least partially vaporizing the condensed stream from step (xiii) by heat exchange with a heat source to provide a partially vaporized two-phase stream; and (xv) separating the partially vaporized two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against another heat source.

[0017] In some embodiments, the heat sources and the heat sinks may be part of a chemical plant, a petrochemical plant, a food and beverage plant, a pulp and paper plant, a textiles plant, a plastic plant, or a pharmaceutical plant. In some embodiments, the heat source may be an exothermic reactor, a condensing stream, a condenser of a distillation column, from a solidification of a stream, heat from a process stream that is being cooled, or waste heat. In some embodiments, the heat sink may be an endothermic reactor, a boiling liquid stream, a melting solid, a reboiler of a distillation column, stream generation, or heating of a process stream.

[0018] In some embodiments, one of the heat sources may be a condenser of a distillation column and one of the heat sinks is a reboiler of the same distillation column or a different distillation column. In some embodiments, one of the heat sources may be an intermediate condenser located in a rectifying section of the distillation column and one of the heat sinks may be an intermediate reboiler located in a stripping section of the distillation column.BRIEF DESCRIPTION OF THE FIGURES

[0019] FIG. 1A is a diagrammatic view of a single-stage MCIC heat pump for a single heat source and two heat sinks.

[0020] FIG. 1B is a diagrammatic view of the single-stage MCIC heat pump for a single heat source and two heat sinks with an eductor.

[0021] FIG. 2 is a diagrammatic view of a two-stage MCIC heat pump cycle for a single heat source and two heat sinks.

[0022] FIG. 3 is a diagrammatic view of an alternate two-stage MCIC heat pump for a single heat source and two heat sinks.

[0023] FIG. 4 is a diagrammatic view of a three-stage MCIC heat pump for a single heat source and two heat sinks.

[0024] FIG. 5 is a diagrammatic view of a single-stage MCIC heat pump for two heat sources and a single heat sink.

[0025] FIG. 6 is a diagrammatic view of an alternate single-stage MCIC heat pump for two heat sources and a single heat sink

[0026] FIG. 7 is a diagrammatic view of a two-stage MCIC heat pump for three heat sources and a single heat sink, where two-phase streams are produced by both partial condensation and partial vaporization.

[0027] FIG. 8 is a diagrammatic view of a single-stage MCIC heat pump for two heat sources and a single heat sink, but operating at three pressures i.e. highest, intermediate, and lowest pressures. The two-phase is produced by partial vaporization.

[0028] FIG. 9 is a diagrammatic view of a two-stage MCIC heat pump for three heat sources and two heat sinks.

[0029] FIG. 10 is a diagrammatic view of an alternate two-stage MCIC heat pump for three heat sources and two heat sinks.

[0030] FIG. 11 is a diagrammatic view of an alternate two-stage MCIC heat pump for two heat sources and a single heat sink, that employs a multi-stage compressor or multiple compressors, where the two-phase stream is produced by partial condensation as well as partial vaporization.

[0031] FIG. 12 is a diagrammatic view of an alternate two-stage MCIC heat pump for two heat sources and a single heat sink, that employs a multi-stage compressor or multiple compressors, where the two-phase stream is produced by partial vaporization.

[0032] FIG. 13 is a diagrammatic view of general uses of MCIC heat pumps.

[0033] FIG. 14 is a diagrammatic view of a MCIC heat pump adapted for use in a multicomponent distillation column sequence.

[0034] FIG. 15 is a diagrammatic view of a single-stage MCIC heat pump cycle for two heat sources and two heat sinks.

[0035] FIG. 16 is a diagrammatic view of a distillation column with an intermediate condenser and an intermediate reboiler.

[0036] FIG. 17 is a diagrammatic view of a multicomponent distillation column sequence with an intermediate reboiler on column 2.

[0037] FIG. 18 is a diagrammatic view of a two-stage MCIC heat pump cycle for two heat sources and three heat sinks.

[0038] FIG. 19 is a diagrammatic view of a single-stage MCIC heat pump cycle for two heat sources and three heat sinks.

[0039] FIG. 20 is a diagrammatic view of a MCIC heat pump to replace heat-integrated distillation columns.

[0040] FIG. 21 is a diagrammatic view of a three-stage MCIC heat pump to replace heat-integrated distillation columns.

[0041] FIG. 22 is a diagrammatic view of a distillation column with an intermediate reboiler.

[0042] FIG. 23 is a diagrammatic view of a single-stage MCIC heat pump for a single heat source and two heat sinks.

[0043] FIG. 24 is a diagrammatic view of a single-stage MCIC heat pump for two heat sources and two heat sinks.

[0044] FIG. 25 is a diagrammatic view of a two-stage MCIC heat pump for two heat sources and three heat sinks.DETAILED DESCRIPTION

[0045] An object of the present disclosure is to use of a heat pump with internal cascading cycles for pumping heat from a single heat source to multiple distinct heat sinks, from multiple distinct heat sources to a single heat sink, or multiple distinct heat sources to multiple distinct heat sinks. The mixed component with internal cascading (MCIC) heat pump utilizes mixed component as the heat pump fluid or working fluid, and a single compressor. The MCIC heat pump creates a new vapor stream and a new liquid stream after partial condensation or vaporization. These streams then participate in heat pumping. The MCIC heat pump uses a single compressor as the heat pump compressor. In some embodiments, the single compressor could be a multistage compressor.

[0046] Before the present disclosure is further described, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended clauses.Definitions

[0047] Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, applications, published applications and other publications referred to herein are incorporated by reference in their entireties. If a definition set forth in this section is contrary to or otherwise inconsistent with a definition set forth in a patent, application, or other publication that is herein incorporated by reference, the definition set forth in this section prevails over the definition incorporated herein by reference.

[0048] As used herein and in the appended clauses, the singular forms “a,”“an,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the clauses may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,”“only” and the like in connection with the recitation of clause elements, or use of a “negative” limitation.

[0049] As used herein, the terms “including,”“containing,” and “comprising” are used in their open, non-limiting sense.

[0050] The term “about” as used herein means greater or lesser than the value or range of values stated by 10 percent, but is not intended to designate any value or range of values to only this broader definition. Each value or range of values preceded by the term “about” is also intended to encompass the embodiment of the stated absolute value or range of values. To provide a more concise description, some of the quantitative expressions given herein are not qualified with the term “about.” It is understood that, whether the term “about” is used explicitly or not, every quantity given herein is meant to refer to the actual given value, and it is also meant to refer to the approximation to such given value that would reasonably be inferred based on the ordinary skill in the art, including equivalents and approximations due to the experimental and / or measurement conditions for such given value. Whenever a yield is given as a percentage, such yield refers to a mass of the entity for which the yield is given with respect to the maximum amount of the same entity that could be obtained under the particular stoichiometric conditions. Concentrations that are given as percentages refer to mass ratios, unless indicated differently.

[0051] All of the above, and any other publications, patents and published patent applications referred to in this application are specifically incorporated by reference herein. In case of conflict, the present specification, including its specific definitions, will control.

[0052] The term “mixed component” refers to a mixture that comprises two or more components selected from the group of hydrocarbons (but not limited to it) containing one or more carbon atoms. The mixture may include—alcohols, alkanes, amines, olefins, aldehydes, freons, ketones, aromatics etc. Besides hydrocarbons, the constituents of the mixed component fluid may also include one or more suitable components from the list of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and HFOs (organic compound composed of hydrogen, fluorine, and carbon)6,7. When MCIC is applied to a distillation, the “mixed component” can also contain one or more components present in the feed mixture. The mixture may also include azeotropic mixtures, polar and non-polar mixtures. The components and their composition depend upon the temperature (and their range) of heat sources and sinks. The mixture and / or its relevant submixtures exist as a liquid and / or vapor phase in the given operating range of temperature and pressure.

[0053] The term “lighter components” as used herein, refers to the constituents of the mixture that have lower boiling points and higher volatility relative to the other constituents, causing them to preferentially remain in the vapor phase upon partial condensation.

[0054] The term “heavier components” as used herein, refers to the constituents of the mixture that have higher boiling points and lower volatility relative to the other constituents, causing them to preferentially transition into the liquid phase upon partial condensation.

[0055] The term ‘boiling point’ as used herein, refers to the temperature at which a pure component's vapor pressure is equal to the atmospheric pressure.

[0056] The term “predominantly” as used herein, refers to the majority of the content of that particular stream.

[0057] The terms “rectifying” and “stripping” as used herein, refer to sections above and below the feed in the distillation column, respectively.

[0058] The term “desired location” as used herein, refers to any stage(s) in the distillation column.

[0059] The terms “condensers” and “reboilers” as used herein, refer to the heat exchangers at the top and bottom of the distillation column, respectively. Heat is added to the “reboilers” at the highest temperature, and heat is removed from the “condensers” at the lowest temperature of the distillation column.

[0060] The term “partial condensation” as used herein, refers to incomplete condensation, which results in a two-phase stream containing both vapor and liquid.

[0061] The term “partial vaporization” as used herein, refers to incomplete vaporization, which results in a two-phase stream containing both vapor and liquid.

[0062] The term “pressure ratio” as used herein, refers to the ratio of the compressor's outlet and inlet pressures. All the pressure values listed are absolute pressure.

[0063] The term “throttling” as used herein, refers to the reduction of pressure. The pressure may be reduced across a Joule-Thompson valve or a dense fluid expander.

[0064] The term “temperature lift” as used herein, refers to the temperature over which heat is pumped. If the heat pump is applied between the condenser and the reboiler of a distillation column, then the temperature lift is the difference between the reboiler and the condenser temperatures.

[0065] The term “single-loop heat pump” as used herein, refers to a conventional heat pump loop in which heat is pumped from the lowest temperature to the highest temperature using a single compressor.

[0066] The term “process stream” as used herein, refers to a distinct continuous flow of material that transfers mass and energy between unit operations within a chemical process.REPRESENTATIVE EMBODIMENTS

[0067] FIGS. 1A-25, show embodiments of mixed component with internal cascading (MCIC) heat pumps. The MCIC heat pumps use a mixed component as the heat pump working fluid to enable the pump of heat from either (i) a single heat source to multiple distinct heat sinks (e.g., heat sinks HT1, HT2, HT3), (ii) multiple distinct heat sources (e.g., heat sources LT1, LT2, LT3) to a single heat sink, or (iii) multiple distinct heat sources to multiple distinct heat sinks. The heat source(s) may or may not be above-ambient temperature and the heat sink(s) are at a temperature above the temperature of the heat source(s). In the preferred mode, the heat source(s) are at or above ambient temperature. The MCIC heat pumps utilize the fact that partial condensation or vaporization of the mixed component working fluid provides a two-phase stream that can be separated into a vapor stream rich in the lighter components and a liquid stream rich in the heavier components. This allows the MCIC heat pumps to use a single compressor.

[0068] In chemical, petrochemical, food and beverage, plastic, textile, pulp and paper, wood, metal, and pharmaceutical manufacturing plants, there are multiple sources of low-temperature heat that could be beneficially used by pumping it to higher temperatures, where it can provide heat to high-temperature heat sinks. For the chemical industry, some examples of such sources include exothermic reactors, condensers of the distillation columns, heat from process streams, a condensing process stream, solidification, etc. Some examples of such sinks are endothermic reactors, reboilers of the distillation columns, heat-to-process streams, vaporizing process streams, steam generators, absorption stripper columns, melting, etc. In the above-mentioned processes, if the low-temperature heat from the sources is not properly utilized within the plant to meet one or more energy needs and is wasted by rejection to the ambient, it results in lower process efficiency.

[0069] Typical single loop heat pumps may not be able to provide the large temperature lift for such applications due to the infeasible pressure ratio across the compressor, as well as the possibility of the heat pump streams going into either a critical region or a very low-pressure region. Heat pumps with multiple cascading loops may solve some of these challenges associated with larger temperature lifts by using multiple compressors in each cascading loop. However, the overall process becomes an expensive option to apply because of the use of multiple compressors.

[0070] The use of multiple compressors results from the need for multiple pressure levels to achieve multiple temperature levels. A common example with multiple heat sources and heat sinks is distillation. A distillation column with an intermediate reboiler is an example of two heat sinks (reboiler and intermediate reboiler) and a single heat source (condenser). The temperature of the intermediate reboiler is between the temperature of the condenser and the reboiler. If a single compressor heat pump loop is used, heat is pumped to the highest temperature (reboiler temperature), and hence it has higher compressor power. A two-compressor heat pump loop can allow the pumping of heat at two distinct temperatures (reboiler temperature and intermediate reboiler temperature). Because of this, it has lower compressor power but higher cost as it requires two heat pump compressors.

[0071] FIG. 1A shows a heat pump system 400 with single internal cascading (MCIC) cycle according to the current invention for pumping heat from a single heat source LT1 to two heat sinks HT1, HT2 that are at temperatures higher than the temperature of the heat source LT1. The MCIC heat pump 400 utilizes partial condensation of a high-pressure gaseous mixed component stream 409 by heat exchange with the first heat sink HT1 providing a two-phase stream 401 that is separated into a vapor stream 402 rich in the lighter components and a liquid stream 403 rich in the heavier components. The vapor stream 402 can be used to provide heat to the second heat sink HT2, which is at a temperature lower than the first heat sink HT1. Furthermore, the fact that the vapor stream 402 is rich in lighter components means it has a lower bubble point temperature. As a result, the vapor stream 402 condenses at a lower temperature, providing better temperature profile matching in the heat exchanger of the heat sink HT2.

[0072] The heat pump system 400 includes a compressor C1, a separation and intermediate condensation unit 430, a heat exchanger 435, an expansion or throttling valve 438, and fluid lines in fluid communication therebetween as shown in FIG. 1A. The compressor C1 is configured to compress the working fluid to increase the pressure of the working fluid. The separation and intermediate condensation unit 430 is configured to separate the vapor and liquid stream of the two-phase mixed component working fluid 401 and condense the separated vapor stream and further cool the separated liquid stream independently before the second heat sink HT2. The heat exchanger 435 is configured to cool the working fluid after the second heat sink HT2 but before the heat source LT1.

[0073] The separation and intermediate condensation unit 430 has a separator 432, an intermediate heat exchanger 434, and an expansion or throttling valve 436 as shown in FIG. 1A. The separator 432 is configured to separate a two-phase stream into the two streams: the vapor stream 402, which is richer in lighter components, and the liquid stream 403 which is richer in heavier components. The intermediate heat exchanger 434 is configured to transfer heat from different streams to condense the separated vapor stream and further cool the separated liquid stream. The expansion or throttle valves 436, 438 are both configured to reduce the pressure of the separated liquid stream and condensed separated vapor stream, respectively.

[0074] During operation, a low-pressure gaseous stream 404 of a mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 409 of the mixed component. The high-pressure stream 409 is then partially condensed by transferring heat from the high-pressure stream 409 to the first heat sink HT1, resulting in a partially condensed two-phase stream 401. The separation and intermediate condensation unit 430 then separates the partially condensed two-phase stream 401 and separately condenses the separated vapor stream 402 and further cools the separated liquid stream 403. As shown in FIG. 1A, the partially condensed two-phase stream 401 is separated into a vapor stream 402, rich in lighter components, and a liquid stream 403, rich in heavier components by the separator 432.

[0075] Both the vapor and liquid streams 402, 403 are then cooled in the intermediate heat exchanger 434, as shown in FIG. 1A. The vapor and liquid streams 402, 403 are condensed and subcooled, respectively, in the intermediate heat exchanger 434 by providing heat to stream 415. The extent of condensation of the vapor stream 402 will depend on the flowrate of liquid stream 403. The flowrate of the separated liquid stream 403 depends on the extent of partial condensation during heat exchange with the heat sink HT1.

[0076] The separated vapor stream 402 is condensed in the intermediate heat exchanger 434 to provide a partially condensed separated vapor stream 406, which is a two-phase stream. The stream 406 is fully condensed by providing heat to the second heat sink HT2 as shown in FIG. 1A. The resulting stream 407 is subcooled in the heat exchanger 435 by transferring heat to stream 411 to provide the steam 408. The pressure of the resulting stream 408 is reduced across the expansion valve 438 to provide a low-pressure predominantly liquid stream 419.

[0077] The low-pressure liquid stream 419 then exchangers heat with the heat source LT1 as shown in FIG. 1A. The low-pressure liquid stream 419 is vaporized by transferring heat from the heat source LT1 to the stream 419 to provide a vaporized stream 411, which could be either vapor or two-phase. The stream 411 then exchanges heat with subcooling stream 407 in the heat exchanger 435 to give stream 412.

[0078] The separated liquid stream 403 is subcooled and reduced in pressure to give predominantly liquid stream 414 as shown in FIG. 1A. The separated liquid stream 403 is further cooled in the intermediate heat exchanger 434 to provide subcooled separated liquid stream 413. The pressure of the subcooled separated liquid stream 413 is reduced across the expansion valve 436 to provide a low-pressure stream 414. Once the subcooled separated liquid stream 413 is throttled, the low-pressure stream 414 is mixed with the vaporized stream 412 after the heat exchange with the heat source LT1 to provide the two-phase stream 415.

[0079] The two-phase stream 415 exchanges heat in the intermediate heat exchanger 434 to give the low-pressure gaseous mixed component stream 404 as shown in FIG. 1A. The heat from the separated vapor stream 402 and the separated liquid stream 403 is transferred to the two-phase stream 415 in the heat exchanger 434 to provide the low-pressure gaseous stream 404. The low-pressure gaseous stream 404 may be a saturated vapor stream or a superheated gaseous stream; however, here, it is referred to as a gaseous stream. The low-pressure gaseous stream 404 is then again compressed in the compressor C1 to complete the heat pump cycle as shown in FIG. 1A.

[0080] In an alternate embodiment of FIG. 1A, the pressure of the separated liquid stream 403 after further cooling in heat exchanger 434 is not immediately reduced. Instead, it is even further cooled in a portion of the heat exchanger 435, then withdrawn from an intermediate location of the heat exchanger 435, and then reduced in pressure across the expansion valve 436 and mixed with the warming stream 411 at an intermediate location of the heat exchanger 435.

[0081] In some embodiments, the compressor C1 is a single stage compressor. If the pressure ratio across the compressor C1 is high, the compressor C1 may use two or more stages of compression with the option to remove some heat via interstage cooling. In the embodiment of FIG. 1A, the temperature of the first heat sink HT1 is higher than the temperature of the second heat sink HT2, which in turn is higher than the temperature of the heat source LT1. The heat pump 400 of FIG. 1 may be useful when the temperature of the heat source LT1 is closer to the temperature of the second heat sink HT2, but farther from the temperature of the first heat sink HT1. A stream rich in lighter components (e.g., separated vapor stream 402) condenses at a lower temperature, thereby maintaining the lower pressure ratio across the compressor C1. The partial condensation, separation of the vapor stream 402, and its condensation provides internal cascading to the lower temperatures of heat source LT1.

[0082] As shown in FIG. 1B, the heat pump 400 may use eductor 440. The eductor 440 replaces the expansion valve 436 and mixes the subcooled liquid stream 413 from the separator 432 with the vaporized stream 412 from the heat source heat exchanger LT1. The suction nozzle of the eductor 440 sucks the vaporized stream 412 that comes after the heat exchange with the heat source LT1. This results in the mixed component stream 415′ exiting the eductor 440 to be at a slightly higher pressure than the corresponding stream 415 produced with expansion valve 436, improving the efficiency of the heat pump 400.

[0083] Another embodiment of a MCIC heat pump 500 is shown in FIG. 2. The MCIC heat pump 500 is substantially similar to the MCIC heat pump 400 shown in FIGS. 1A-B and described herein. Accordingly, similar reference numbers in the 500 series indicate features that are common between the MCIC heat pump 400 and the MCIC heat pump 500. The description of the MCIC heat pump 400 is incorporated by reference to apply to the MCIC heat pump 500, except in instances when it conflicts with the specific description and drawings of the HTIC heat pump 500.

[0084] In the embodiment of FIG. 1A, the heat cascading is done at one intermediate temperature. However, in other embodiments, for example when the temperature lift is somewhat large, it may be advantageous to use more than one intermediate temperature cascading. The heat pump 500 may include multiple separate and intermediate condensation units 530A, 530B like as shown in FIG. 2, which perform multiple condensations and evaporations of the mixed component from the heat pump compressor C1 to achieve the desired temperature lift.

[0085] FIG. 2 is an illustrative embodiment of a heat pump 500 that performs two partial condensations of the high-pressure mixed component stream 509. The heat pump 500 includes a compressor C1, separation and intermediate condensation units 530A, 530B, a heat exchanger 535, an expansion valve 538, and fluid lines in fluid communication therebetween as shown in FIG. 2. Each separation and intermediate condensation unit 530A, 530B has a separator 532A, 532B, an intermediate heat exchanger 534A, 534B, and an expansion valve 536A, 536B as shown in FIG. 2.

[0086] During operation, a low-pressure gaseous stream 504 of the mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 509 of the mixed component. The high-pressure stream 509 is then partially condensed. The high-pressure stream 509 is then partially condensed by transferring the desired heat from the high-pressure stream 509 to the heat sink HT1, resulting in a partially condensed two-phase stream 501A.

[0087] The first separation and intermediate condensation unit 530A then separates the partially condensed two-phase stream 501A and separately condenses the separated vapor stream 502A and further cools the separated liquid stream 503A. As shown in FIG. 2, the partially condensed two-phase stream 501A is separated into a first separated vapor stream 502A and a first separated liquid stream 503A by the separator 532A. The first separated vapor stream 502A is rich in lighter components, similar to the stream 402 in FIG. 1, and the first separated liquid stream 503A is rich in heavier components.

[0088] To get one additional cascading temperature, the first separated vapor stream 502A is now partially condensed in the first intermediate heat exchanger 534A against the stream 515A. Condensing the first separated vapor stream 502A in the first intermediate heat exchanger 534A provides the second two-phase stream 501B. The second two-phase stream 501B is then separated and condensed again in the second separation and intermediate condensation unit 530B. The second two-phase stream 501B is separated in the second separator 532B to provide a second separated vapor stream 502B and a second separated liquid stream 503B as shown in FIG. 2. The second separated vapor stream 502B is richer in the lighter components than the first separated vapor stream 502A. Similarly, the second separated liquid stream 503B will be richer in the lighter components than the first separated liquid stream 503A.

[0089] The second separated vapor stream 502B is then partially condensed against the second heat sink HT2 to provide a two-phase stream 507 as shown in FIG. 2. The two-phase stream 507 is further condensed in the second intermediate heat exchanger 534B against the stream 515B. Condensing the second separated vapor stream 502B in the second temperature heat exchanger 534A provides the subcooled liquid stream 508. The stream 508 is throttled, which reduces the pressure to provide a low-pressure predominately liquid stream 519. The stream 519 is then vaporized by transferring heat from the heat source LT1 to the stream 519 to provide a vaporized stream 5111B.

[0090] The liquid stream 503B from the second separator 532B may be subcooled in the heat exchanger 535 before the second intermediate heat exchanger 534B as shown in FIG. 2. The resulting stream 517 may then be further cooled in the second intermediate heat exchanger 534B. The resulting subcooled stream 513B is then throttled through the expansion valve 536B to provide a low-pressure predominately liquid stream 514B. The low-pressure liquid stream 514B may then be mixed or combined with the vaporized stream 5111B.

[0091] In the illustrative embodiment, the liquid stream 503B is subcooled by the heat exchanger 535 and the second intermediate heat exchanger 534B as shown in FIG. 2. In some embodiments, the heat exchanger 535 may be omitted and the second separated liquid stream 503B is condensed in the second intermediate heat exchanger 534B only. The resulting stream 511B from the heat source LT1, which could be either vapor or two-phase stream, is then mixed with low-pressure predominately liquid stream 514B, which gives stream 515B.

[0092] The stream 515B is vaporized in the second intermediate heat exchanger 534B as shown in FIG. 2. The heat from the second separated vapor stream 502B and the second separated liquid stream 503B is transferred to the stream 515B in the second intermediate heat exchanger 534B. The resulting stream 516 may further heated in the heat exchanger 535 by the second separated liquid stream 503B. The presence of the optional heat exchanger 535 depends on the temperature of the stream 516. If the minimum approach temperature is maintained, then the heat exchanger 535 may be present to heat the stream 516.

[0093] The first separated liquid stream 503A from the separator 532A, is further cooled in the first intermediate heat exchanger 534A to provide a subcooled second separated liquid stream 513A. The subcooled second separated liquid stream 513A is reduced in pressure across the expansion valve 536A to provide a low-pressure stream 514A, which is then mixed with stream 511A. The resulting stream 515A is vaporized in the first intermediate heat exchanger 534A to provide the low-pressure gaseous mixed component stream 504, which is then compressed to complete the heat pump cycle. The heat from the first separated vapor stream 502A and the first separated liquid stream 503A is transferred to the stream 515A in the first intermediate heat exchanger 534A.

[0094] The temperature of the first heat sink HT1 is higher than the temperature of the second heat sink HT2, which in turn is higher than the temperature of the heat source LT1. Due to multiple cascades, the resulting vapor stream 502B from separator 532B is richer in lighter components as compared to stream 502A (analogous to the separated stream 402). Hence, for a given pressure at the exit of throttling valve 538 in stream 508, the throttled stream 519 resulting from stream 502B can vaporize at even lower temperatures when throttled. The heat pump 500 is able to achieve temperature lifts between the heat source LT1 and the heat sink HT1, even if the temperature is relatively high.

[0095] For convenience, the heat pump 400 in FIGS. 1A-B with one cascading stage containing one partial condensation / separation will be referred to as a one-stage MCIC heat pump cycle, while the heat pump 500 in FIG. 2 with two cascading stages containing two partial condensations / separations will be referred to as a two-stage MCIC heat pump cycle. In other words, if in an MCIC heat pump cycle, N cascading stages are present, we will refer to it as N-stage MCIC heat pump cycle. The number of cascading stages will depend on the desired temperature lift between the heat sink HT1 and the heat source LT1, as well as the number of heat sources and sinks.

[0096] Another embodiment of a MCIC heat pump 600 is shown in FIG. 3. The MCIC heat pump 600 is substantially similar to the MCIC heat pumps 400, 500 shown in FIGS. 1A-2 and described herein. Accordingly, similar reference numbers in the 600 series indicate features that are common between the MCIC heat pumps 400, 500 and the MCIC heat pump 600. The description of the MCIC heat pumps 400, 500 is incorporated by reference to apply to the MCIC heat pump 600, except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 600.

[0097] The MCIC heat pump 600 is an alternate MCIC heat pump configuration for a single heat source LT1 and two heat sinks HT1, HT2. This configuration is similar to the one shown in FIG. 2, the difference being that in the heat pump cycle of FIG. 3, the second cascading with partial condensation and vapor liquid separation (e.g., the second separation and intermediate condensation unit 630B) is after the heat exchange with the second heat sink HT2 and not before like in the embodiment of FIG. 2. The two-phase stream 601B for the second separator 632B is created using the second heat sink HT2, whereas in the embodiment of FIG. 2, the first intermediate heat exchanger 534A is used.

[0098] Whether to have the second separation and intermediate condensing unit before or after the second heat sink HT1 depends on the relative temperature differences between the heat source LT1 and the two heat sinks HT1, HT2. For example, a second separation and intermediate condensing unit may be included for instances where the temperature different between the heat source LT1 and heat sinks HT1, HT2 is further apart. The second separation and intermediate condensing unit may create vapor with an even higher mole fraction of lighter components, which can reach a lower temperature even at above-ambient pressure.

[0099] The heat pump 600 includes a compressor C1, separation and intermediate condensation units 630A, 630B, a heat exchanger 635, an expansion valve 638, and fluid lines in fluid communication therebetween as shown in FIG. 3. Each separation and intermediate condensation unit 630A, 630B has a separator 632A, 632B, an intermediate heat exchanger 634A, 634B, and an expansion valve 636A, 636B as shown in FIG. 3. However, in this embodiment, the second heat sink HT2 first partially condenses the separated vapor stream 602A and the first intermediate heat exchanger 634A is after the separator 632B of the second separation and intermediate condensation unit 630B.

[0100] During operation, a low-pressure gaseous stream 604 of the mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 609 of the mixed component. The high-pressure stream 609 is then partially condensed. The high-pressure stream 609 is then partially condensed by transferring the desired heat from the high-pressure stream 609 to the heat sink HT1, resulting in a partially condensed two-phase stream 601A.

[0101] The first separation and intermediate condensation unit 630A then separates the partially condensed two-phase stream 601A and separately condenses the separated vapor stream 602A and further cools 603A in the heat exchanger 635. As shown in FIG. 3, the partially condensed two-phase stream 601A is separated into a first separated vapor stream 602A and a first separated liquid stream 603A by the separator 632A. The first separated vapor stream 602A is rich in lighter components, and the first separated liquid stream 603A is rich in heavier components.

[0102] To get one additional cascading temperature, the first separated vapor stream 602A is now partially condensed by transferring heat to the second heat sink HT2 as shown in FIG. 3. Condensing the first separated vapor stream 602A by transferring heat to the second heat sink HT2 provides the second two-phase stream 601B. The second two-phase stream 601B is then separated by the separator 632B of the second separation and intermediate condensation unit 630B as shown in FIG. 3.

[0103] The second two-phase stream 601B is separated in the second separator 632B to provide a second separated vapor stream 602B and a second separated liquid stream 603B as shown in FIG. 3. The second separated vapor stream 602B is condensed in both intermediate heat exchangers 634A, 634B to provide a liquid stream 608. As shown in FIG. 3, the second separated vapor stream 630B is first condensed in the first intermediate heat exchanger 634A to provide stream 607 and then condensed further in the second intermediate heat exchanger 634B to provide the liquid stream 608. The pressure of the liquid stream 608 is then reduced through the expansion valve 638, and the resulting stream 619 is vaporized against heat source LT1 to give a two-phase or a vaporized stream 611B.

[0104] The liquid stream 603B from the second separator 632B is cooled in the first intermediate heat exchanger 634A to provide the stream 618 and the further cooled in the second intermediate heat exchanger 634B to provide subcooled stream 613B. The resulting subcooled stream 613B is then throttled through the expansion valve 636B to provide a low-pressure predominately liquid stream 614B. The low-pressure liquid stream 614B may then be mixed or combined with the vaporized stream 611B. The resulting liquid stream 615B is vaporized in the second intermediate heat exchanger 634B as shown in FIG. 3. The heat from the condensing stream 607 and condensing stream 618 is transferred to the stream 615B in the second intermediate heat exchanger 634B.

[0105] The first separated liquid stream 603A from the first separator 632A may be subcooled in the heat exchanger 635 before the first intermediate heat exchanger 634A as shown in FIG. 3. The resulting stream 617 may then be further cooled in the first intermediate heat exchanger 634A to provide a subcooled first separated liquid stream 613A. The subcooled first separated liquid stream 613A is reduced in pressure across the expansion valve 636A to provide a low-pressure stream 614A, which is then mixed with stream 611A.

[0106] The resulting stream 615A is then further heated in the first intermediate heat exchanger 634A by the second separated vapor stream 602B, the second separated liquid stream 603B, and the first separated liquid stream 603A as shown in FIG. 3. The liquid in the resulting stream 615A, which is a two-phase stream, vaporizes against the second separated vapor stream 602B, the second separated liquid stream 603B, and the first separated liquid stream 603A in the first intermediate heat exchanger 634A to provide the vaporized stream 616. The heat exchanger 635 may be used to superheat the vaporized stream 616 to produce the low-pressure gaseous stream 604, which is compressed by the compressor C1 to complete the heat pump cycle.

[0107] In some embodiments, the first separated vapor stream 602A may be partially cooled or condensed in the heat exchanger 635 prior to transferring heat to the second heat sink HT1. The rearrangement of heat exchangers 635, 634A, 634B may depend on relative temperatures of the heat source LT1 and the heat sinks HT1, HT2.

[0108] Another embodiment of a MCIC heat pump 700 is shown in FIG. 4. The MCIC heat pump 700 is substantially similar to the MCIC heat pumps 400, 500, 600 shown in FIGS. 1A-3 and described herein. Accordingly, similar reference numbers in the 700 series indicate features that are common between the MCIC heat pumps 400, 500, 600 and the MCIC heat pump 700. The description of the MCIC heat pumps 400, 500, 600 is incorporated by reference to apply to the MCIC heat pump 700, except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 700.

[0109] FIG. 7 shows an illustrative three-stage MCIC heat pump configuration for a single heat source LT1 and two heat sinks HT1, HT2. When the temperature lift between the heat sinks HT1, HT2 and heat source LT1 increases, higher stages of MCIC become beneficial. Multiple cascading stages containing multiple partial condensations and the associated liquid-vapor separations (e.g., multiple separation and condensation units 730A, 730B, 730C) create streams (e.g., vapor streams 702A, 702B, 702C) that are rich in lighter components and, hence, can reach lower temperatures relative to the temperatures of the heat sinks HT1, HT2 while heaving low to modest values of the pressure ratio across compressor C1.

[0110] The heat pump 700 includes a compressor C1, separation and intermediate condensation units 730A, 730B, 730C, a heat exchanger 735, an expansion valve 738, and fluid lines in fluid communication therebetween as shown in FIG. 4. Each separation and intermediate condensation unit 730A, 730B, 730C has a separator 732A, 732B, 732C, an intermediate heat exchanger 734A, 734B, 734C, and an expansion valve 736A, 736B, 736C as shown in FIG. 4. Similar to the embodiment in FIG. 3, one of the intermediate heat exchangers is not immediately after the associated separator. For example, the second intermediate heat exchanger 734B is after the third separator 732C of the third separation and intermediate condensation unit 730C.

[0111] During operation, a low-pressure gaseous stream 704 of the mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 709 of the mixed component. The high-pressure stream 709 is then partially condensed. The high-pressure stream 709 is then partially condensed by transferring the desired heat from the high-pressure stream 709 to the heat sink HT1, resulting in a partially condensed two-phase stream 701A.

[0112] The first separation and intermediate condensation unit 730A then separates the partially condensed two-phase stream 701A and separately condenses the separated vapor stream 702A and further cools the separated liquid stream 703A. As shown in FIG. 4, the partially condensed two-phase stream 701A is separated into a first separated vapor stream 702A and a first separated liquid stream 703A by the separator 732A. The first separated vapor stream 702A is rich in lighter components, and the first separated liquid stream 703A is rich in heavier components.

[0113] To get additional cascading temperatures, the first separated vapor stream 702A is now partially condensed in the first intermediate heat exchanger 734A against the stream 715A. Condensing the first separated vapor stream 702A in the first intermediate heat exchanger 734A provides the second two-phase stream 701B. The second two-phase stream 701B is then separated and condensed again in the second separation and intermediate condensation unit 730B.

[0114] The second two-phase stream 701B is separated in the second separator 732B to provide a second separated vapor stream 702B and a second separated liquid stream 703B as shown in FIG. 4. The second separated vapor stream 702B is richer in the lighter components than the first separated vapor stream 702A. Similarly, the second separated liquid stream 703B will be richer in the lighter components than the first separated liquid stream 703A.

[0115] To get an additional cascading temperature, the second separated vapor stream 702B is now partially condensed by transferring heat to the second heat sink HT2 as shown in FIG. 4. Condensing the second separated vapor stream 702B by transferring heat to the second heat sink HT2 provides the third two-phase stream 701C. The third two-phase stream 701C is then separated by the separator 732C of the third separation and intermediate condensation unit 730C as shown in FIG. 4.

[0116] The third two-phase stream 701C is separated in the third separator 732C to provide a third separated vapor stream 702C and a third separated liquid stream 703C as shown in FIG. 4. The third separated vapor stream 702C is condensed in both intermediate heat exchangers 734B, 734C to provide a liquid stream 708. As shown in FIG. 4, the third separated vapor stream 702C is first condensed in the second intermediate heat exchanger 734B to provide stream 707 and then condensed further in the third intermediate heat exchanger 734C to provide the liquid stream 708. The pressure of the liquid stream 708 is then reduced through the expansion valve 738, and the resulting stream 719 is vaporized against heat source LT1 to give a two-phase or a vaporized stream 711C. The different separated liquid streams 703A, 703B, 703C from the separators 732A, 732B, 732C are each subcooled and throttled across the respective expansion valve 736A, 736B, 736C to produce streams 714A, 714B, 714C as shown in FIG. 4.

[0117] The third separated liquid stream 703C from the third second separator 732C is cooled in the second intermediate heat exchanger 734B to provide the stream 718 and the further cooled in the third intermediate heat exchanger 734C to provide subcooled stream 713C. The resulting subcooled stream 713C is then throttled through the expansion valve 736C to provide a low-pressure predominately liquid stream 714C. The low-pressure liquid stream 714C may then be mixed or combined with the vaporized stream 711C. The resulting two-phase stream 715C is vaporized in the third intermediate heat exchanger 734C as shown in FIG. 4. The heat from the condensing streams 707, 718 are transferred to the stream 715C in the third intermediate heat exchanger 734C.

[0118] The second separated liquid stream 703B from the second separator 732B may be subcooled in the heat exchanger 735 before the second intermediate heat exchanger 734B as shown in FIG. 4. The resulting stream 717 may then be further cooled in the second intermediate heat exchanger 734B to provide a subcooled second separated liquid stream 713B. The subcooled second separated liquid stream 713B is reduced in pressure across the expansion valve 736B to provide a low-pressure stream 714B, which is then mixed with stream 711B from the third intermediate heat exchanger 734C.

[0119] The low-pressure stream 714B is then mixed with stream 711B to provide stream 715B as shown in FIG. 4. The stream 715B is further heated in the second intermediate heat exchanger 734B by the third separated vapor stream 702C, the third separated liquid stream 703C, and the stream 717. The liquid in the resulting stream 715B, which is a two-phase stream, vaporizes against the third separated vapor stream 702C, the third separated liquid stream 703C, and the stream 717 in the second intermediate heat exchanger 734B to provide the vaporized stream 716.

[0120] The heat exchanger 735 may be used to further heat the vaporized stream 716 to produce the stream 721 as shown in FIG. 4. The presence of the optional heat exchanger 735 depends on the temperature of the stream 716. If the minimum approach temperature is maintained, then the heat exchanger 735 may be present to heat the stream 716.

[0121] The first separated liquid stream 703A is subcooled and reduced in pressure to give predominantly liquid stream 714A as shown in FIG. 4. The first separated liquid stream 703A is further cooled in the first intermediate heat exchanger 734A to provide subcooled first separated liquid stream 713A. The pressure of the subcooled first separated liquid stream 713A is reduced across the expansion valve 736A to provide a low-pressure stream 714A. Once the condensed separated liquid stream 713A is throttled, the low-pressure stream 714A is mixed with the vaporized stream 721 to provide the two-phase stream 715A as shown in FIG. 4.

[0122] The resulting stream 715A is then further heated in the first intermediate heat exchanger 734A by the first separated vapor stream 702A and the first separated liquid stream 703A as shown in FIG. 4. The liquid in the resulting stream 715A, which is a two-phase stream, vaporizes against the first separated vapor stream 702A and the first separated liquid stream 703A in the first intermediate heat exchanger 734A to provide the low-pressure gaseous stream 704. The low-pressure gaseous stream 704 is compressed by the compressor C1 to complete the heat pump cycle.

[0123] Another embodiment of a MCIC heat pump 800 is shown in FIG. 5. The MCIC heat pump 800 is substantially similar to the other MCIC heat pumps shown in FIGS. 1A-4. and described herein. Accordingly, similar reference numbers in the 800 series indicate features that are common between the other MCIC heat pumps and the MCIC heat pump 800. The description of the other MCIC heat pumps is incorporated by reference to apply to the MCIC heat pump 800 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 800.

[0124] The MCIC heat pumps in the embodiments of FIGS. 1A-4 were for pumping heat from a number of heat sources to a number of heat sinks that is greater than the number of heat sources. For example, in the illustrative embodiments, the heat pump configurations of FIGS. 1A-4 pump heat from a single heat source LT1 to multiple heat sinks HT1, HT2. FIG. 5 is an illustrative embodiment of a single-stage MCIC heat pump 800 for pumping heat from two heat sources LT1, LT2 to a single heat sink HT1. The temperature of the first heat source LT1 is lower than the temperature of the second heat source LT2, which in turn is lower than the temperature of the heat sink HT1.

[0125] The heat pump 800 includes a compressor C1, a separation and intermediate condensation unit 830, a heat exchanger 835, an expansion valve 838, and fluid lines in fluid communication therebetween as shown in FIG. 5. The separation and intermediate condensation unit 830 is configured to separate the two-phase mixed component working fluid and condense the separated vapor stream and subcool the separated liquid stream, independently before the heat sources LT1, LT2. The separation and intermediate condensation unit 830 has a separator 832, an intermediate heat exchanger 834, and expansion valves 836, 837 as shown in FIG. 5. The separator 832 is configured to separate a two-phase stream into the two streams: the vapor stream 802 which is richer in lighter components and the liquid stream 803 which is richer in heavier components. The intermediate heat exchanger 834 is configured to transfer heat from different streams to condense each of the separated vapor stream and further cool the separated liquid stream. The expansion or throttle valves 836, 837 are both configured to reduce the pressure of the respective stream.

[0126] During operation, a low-pressure gaseous stream 804 of a mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 809 of the mixed component. The high-pressure stream 809 is then partially condensed by transferring heat from the high-pressure stream 809 to the heat sink HT1, resulting in a partially condensed two-phase stream 801. The separation and intermediate condensation unit 830 then separates the partially condensed two-phase stream 801 and separately condenses the separated vapor stream 802 and further cools the separated liquid stream 803. As shown in FIG. 5, the partially condensed two-phase stream 801 is separated into a vapor stream 802, rich in lighter components, and a liquid stream 803, rich in heavier components by the separator 832.

[0127] The separated vapor stream 802 is condensed in the intermediate heat exchanger 834 and the heat exchanger 835 against the streams 818 and 815, respectively. The separated vapor stream 802 is cooled or condensed in the intermediate heat exchanger 834 as shown in FIG. 5. This provides the condensed separated vapor stream 806, which is a two-phase stream. The stream 806 is further cooled or condensed in the heat exchanger 835. The pressure of the resulting stream 808 is reduced across the expansion valve 838 to provide a low-pressure predominantly liquid stream 819. The low-pressure liquid stream 819 is vaporized by transferring heat from the first heat source LT1 to give stream 811, which is a predominantly vapor phase stream as shown in FIG. 5.

[0128] On the other side, the separated liquid stream 803 is subcooled by transferring heat from the liquid stream 803 in the intermediate heat exchanger 834 as shown in FIG. 5. The resulting stream 812 is then divided into two different streams, i.e., 813A and 813B. The first stream 813A is throttled across the expansion valve 836 and the resulting stream 814 is vaporized by transferring heat from the second heat source LT2 to the stream 814. The vaporized stream 816, which could be a vapor stream or a two-phase stream is then mixed or combined with the stream 817 from the first heat source LT1.

[0129] The second stream 813B is further subcooled by transferring heat from the second stream 813B in the heat exchanger 835 as shown in FIG. 5 The resulting stream is throttled across the expansion valve 837 to reduce a pressure of the stream and then mixed with stream 811. The resulting stream 815 is then vaporized in the heat exchanger 835 to produce stream 817. The heat from the streams 806, 813B is transferred to the stream 815 in the heat exchanger 835 to provide stream 817 as shown in FIG. 5.

[0130] Stream 817 is then mixed with the vaporized stream 816 from the second heat source LT2, and the resulting stream 818 is then heated in the intermediate heat exchanger 834. The heat from the separated vapor stream 802 and the separated liquid stream 803 is transferred to the stream 818 to produce the initial low-pressure gaseous mixed component stream 804. The low-pressure gaseous stream 804 may be a saturated vapor stream or a superheated gaseous stream; however, here, it is referred to as a gaseous stream. The low-pressure gaseous stream 804 is then again compressed in the compressor C1 to complete the heat pump cycle as shown in FIG. 5.

[0131] Another embodiment of a MCIC heat pump 900 for two heat sources LT1, LT2 and a single heat sink HT1 is shown in FIG. 6. The MCIC heat pump 900 is substantially similar to the MCIC heat pump 800 shown in FIG. 5, and described herein. Accordingly, similar reference numbers in the 900 series indicate features that are common between the MCIC heat pump 800 and the MCIC heat pump 900. The description of the MCIC heat pump 800 is incorporated by reference to apply to the MCIC heat pump 900 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 900.

[0132] Like the embodiment in FIG. 5, the MCIC heat pump 900 is for pumping heat from two what sources LT1, LT2 to a single heat sink HT1 as shown in FIG. 6. The temperature of the first heat source LT1 is lower than the temperature of the second heat source LT2, which in turn is lower than the temperature of the heat sink HT1. The heat pump 900 includes a compressor C1, a separation and intermediate condensation unit 930, a heat exchanger 935, an expansion valve 938, and fluid lines in fluid communication therebetween as shown in FIG. 6. The separation and intermediate condensation unit 930 has a separator 932, intermediate heat exchangers 934, 935, and an expansion valve 936 as shown in FIG. 5.

[0133] During operation, a low-pressure gaseous stream 904 of a mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 909 of the mixed component. The high-pressure stream 909 is then partially condensed by transferring heat from the high-pressure stream 909 to the heat sink HT1, resulting in a partially condensed two-phase stream 901. The separation and intermediate condensation unit 930 then separates the partially condensed two-phase stream 901 and separately condenses the separated vapor stream 902 and further cools the separated liquid 903. As shown in FIG. 6, the partially condensed two-phase stream 901 is separated into a vapor stream 902, rich in lighter components, and a liquid stream 903, rich in heavier components by the separator 932.

[0134] The separated vapor stream 902 is condensed in the intermediate heat exchanger 934 and the heat exchanger 935 against the stream 915, respectively. The separated vapor stream 902 is cooled or condensed in the intermediate heat exchanger 934 as shown in FIG. 6. This provides the condensed separated vapor stream 906, which is a two-phase stream. The stream 906 is further cooled or condensed in the heat exchanger 935. The pressure of the resulting stream 908 is reduced across the expansion valve 938 to provide a low-pressure predominantly liquid stream 919. The low-pressure liquid stream 919 is vaporized by transferring heat from the first heat source LT1 to give stream 911, which is a predominantly vapor phase stream as shown in FIG. 6.

[0135] The separated liquid stream 903 is cooled through the intermediate heat exchanger 934 and the heat exchanger 935 to provide subcooled separated liquid stream 913 as shown in FIG. 6. The pressure of the subcooled separated liquid stream 913 is reduced across the expansion valve 936 to provide a low-pressure stream 914. Once the subcooled separated liquid stream 913 is throttled, the low-pressure stream 914 is mixed with the vaporized stream 911 after the heat exchange with the first heat source LT1 to provide the two-phase stream 915.

[0136] The liquid in the two-phase stream 915 is then vaporized in the heat exchanger 935 and the intermediate heat exchanger 934 as shown in FIG. 6. Unlike the other embodiments, the second heat source LT2 is placed in the heat exchanger 935 in such a way that the desired minimum approach temperature of between the cold and hot stream is maintained in the heat exchanger 935. In another embodiments, the heat exchangers 934, 935 may be combined into one. Therefore, all the vaporization / condensation and subcooling / superheating takes place in the combined heat exchanger only (while maintaining the desired minimum approach temperature between the cold and warm streams). The vaporizing of the stream 915 provides the low-pressure gaseous stream 904, which is compressed by the compressor C1 to complete the heat pump cycle.

[0137] Another embodiment of a MCIC heat pump 1000 for three heat sources LT1, LT2, LT3 and a single heat sink HT1 is shown in FIG. 7. The MCIC heat pump 1000 is substantially similar to the MCIC heat pumps 800, 900 shown in FIGS. 5 and 6, and described herein. Accordingly, similar reference numbers in the 1000 series indicate features that are common between the MCIC heat pumps 800, 900 and the MCIC heat pump 1000. The description of the MCIC heat pumps 800, 900 is incorporated by reference to apply to the MCIC heat pump 1000 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1000.

[0138] FIG. 7 is an illustrative embodiment of a two-stage MCIC heat pump 1000 for pumping heat from three heat sources LT1, LT2, LT3 and a single heat sink HT1. The temperature of the first heat source LT1 is lower than the temperature of the second heat source LT2, which in turn is lower than the temperature of the third heat source LT3. Temperature of the heat sink HT1 is higher than the temperature of all the heat sources LT1, LT2, LT3.

[0139] The heat pump 1000 includes a compressor C1, separation and intermediate condensation units 1030A, 1030B, a heat exchanger 1035, an expansion valve 1038, and fluid lines in fluid communication therebetween as shown in FIG. 7. Each separation and intermediate condensation unit 1030A, 1030B has a separator 1032A, 1032B, an intermediate heat exchanger 1034A, 1034B, and at least one expansion valve 1036A, 1036B, 1037B as shown in FIG. 7.

[0140] During operation, a low-pressure gaseous stream 1004 of a mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 1009A of the mixed component. The high-pressure stream 1009A is then partially condensed by transferring heat from the high-pressure stream 1009A to the heat sink HT1, resulting in a partially condensed two-phase stream 1001A. The first separation and intermediate condensation unit 1020A then separates the partially condensed two-phase stream 1001A and separately condenses the separated vapor stream 1002A and further cools the separated liquid stream 1003A. As shown in FIG. 7, the partially condensed two-phase stream 1001A is separated into a first separated vapor stream 1002A, rich in lighter components, and a first separated liquid stream 1003A, rich in heavier components by the first separator 1032A.

[0141] The first separated liquid stream 1003A is subcooled in the first intermediate heat exchanger 1034A as shown in FIG. 7. The resulting stream 1016A is throttled across the expansion valve 1036A to an intermediate pressure P2. The intermediate pressure stream 1009B is partially vaporized by transferring heat from the third heat source HT2 to the stream 1009B to provide a second two-phase stream 1001B. The second two-phase stream 1001B is separated in the second separator 1032B of the second separated and intermediate condensation unit 1020B into a second separated vapor stream 1002B and a second separated liquid stream 1003B.

[0142] The second separated vapor stream 1002B is condensed in the second intermediate heat exchanger 1034B against the stream 1018 as shown in FIG. 7. The resulting liquid stream 1015B is then throttled across the expansion valve 1037B to the lowest pressure P1. The resulting low-pressure stream 1022 is then vaporized by transferring heat from the second heat source LT2 to the stream 1022 and mixing it with stream 1017. Similarly, the second separated liquid stream 1003B from the second separator 1032B is also subcooled and throttled across the expansion valve 1036B to the lowest pressure, and the resulting low-pressure stream 1024 also mixes with stream 1017 to provide stream 1018 as shown in FIG. 7.

[0143] On the other side, the first separated vapor stream 1002A from the first separator 1032A is condensed in the first and second intermediate heat exchangers 1034A, 1034B against streams 1021, 1018, respectively. The first separated vapor stream 1002A is first condensed in the first intermediate heat exchanger 1034A to provide stream 1015A. The resulting stream 1015A is then further condensed in the second intermediate heat exchanger 1034B. The condensed stream 1008 is then further cooled in the optional heat exchanger 1035, after it is throttled across the expansion valve 1038 to reduce the pressure of the stream 1008 to the lowest pressure, P1, to give a low-pressure predominantly liquid stream 1019.

[0144] The liquid in the low-pressure stream 1019 is vaporized against the first heat source LT1 to provide stream 1011 as shown in FIG. 7. The resulting stream 1011 is then heated in the heat exchanger 1035 to provide stream 1017, which is mixed with the low-pressure streams 1022, 1024 from the second separation and intermediate condensation unit 1030B. After vaporization and superheating by transferring heat from the separated vapor and liquid streams 1002A, 1002B, 1003A, 1003B, the low-pressure mixed component stream 1004 is then compressed to complete the heat pump loop.

[0145] In the illustrative embodiment, the working fluid may be transferred between the streams 1016B, 1015B as suggested by dotted stream line 1023 in FIG. 7. This transfer of working fluid will depend on how large the second heat source LT2 is compared to third heat source LT3. If the heat duty of second heat source LT2 is larger than that of third heat source LT3, then some liquid from stream 1016B may be transferred to stream 1015B. Similarly, if the heat duty of second heat source LT2 is lower than third heat source LT3, then some liquid may be transferred from stream 1015B to stream 1016B. In this way, liquid can be balanced with respect to the heat duties of the heat sources LT1, LT2 providing flexibility to the process.

[0146] Another embodiment of a MCIC heat pump 1100 for two heat sources LT1, LT2 and a single heat sink HT1 is shown in FIG. 8. The MCIC heat pump 1100 is substantially similar to the MCIC heat pumps 800, 900, 100 shown in FIGS. 5-7. and described herein. Accordingly, similar reference numbers in the 1000 series indicate features that are common between the MCIC heat pumps 800, 900, 1000 and the MCIC heat pump 1100. The description of the MCIC heat pumps 800, 900, 1000 is incorporated by reference to apply to the MCIC heat pump 1100 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1100.

[0147] FIG. 8 is an illustrative embodiment of a two-stage MCIC heat pump 1100 for pumping heat from two heat sources LT1, LT2 and a single heat sink HT1. The temperature of the first heat source LT1 is lower than the temperature of the second heat source LT2, which in turn is lower than the temperature of the heat sink HT1. The heat sink HT1 is higher than the temperature of both the heat sources LT1, LT2.

[0148] The heat pump 1100 includes a compressor C1, a separation and intermediate condensation unit 1130, a heat exchanger 1135, expansion valves 1138, 1139, and fluid lines in fluid communication therebetween as shown in FIG. 8. The separation and intermediate condensation unit 1130 has a separator 1132, an intermediate heat exchanger 1134, and an expansion valve 1136 as shown in FIG. 8.

[0149] During operation, a low-pressure gaseous stream 1104 of a mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 1109 of the mixed component. The high-pressure stream 1109 is then completely condensed by transferring heat from the high-pressure stream 1109 to the heat sink HT1, resulting in a completely condensed liquid stream 1101A. This liquid stream is then subcooled in the intermediate heat exchanger 1135 to provide stream 1106.

[0150] The resulting stream 1106 is then throttled across the expansion valve 1139 to reduce the pressure of the stream 1106 to an intermediate pressure P2 as shown in FIG. 8. The intermediate pressure stream 1107 is partially vaporized by transferring heat from the second heat source LT2 the stream 1107 to provide a two-phase stream 1101B. The two-phase stream 1101B is separated into a separated vapor stream 1102 and a separated liquid stream 1103 in the intermediate pressure separator 1132.

[0151] The separated vapor stream 1102 is condensed in the heat exchanger 1134 against the stream 1115 to provide a liquid stream 1108 as shown in FIG. 8 The liquid stream 1108 is throttled across the expansion valve 1138 to reduce the pressure to the lowest pressure P1. The resulting stream 1119 is a predominantly liquid stream, which vaporizes against first heat source LT1 to produce a stream 1111, which is predominantly vapor.

[0152] Similarly, the separated liquid stream 1103 is subcooled by transferring heat from the stream 1103 in the intermediate heat exchanger 1134 as shown in FIG. 8. The resulting stream 1113 is then throttled across the expansion valve 1136 to the lowest pressure P1 to provide stream 1114. The resulting stream 1114 is mixed with stream 1111 to give, a two-phase stream 1115 as shown in FIG. 8.

[0153] The two-phase stream 1115 is heated in the intermediate heat exchanger 1134 against the separated vapor stream 1102 and the separated liquid streams 1103, which results in a predominantly vapor stream 1118 as shown in FIG. 8. The stream 1118 is then further heated in the heat exchanger 1135 to provide the starting low-pressure mixed component gaseous stream 1104.

[0154] In the illustrative embodiment, the two-phase stream 1101B that is separated by the intermediate pressure separator 1132 provides cascading similar to the ones in the processes shown in the previous embodiments. The light components in the separated vapor stream 1102 are condensed, throttled to the lowest pressure, and vaporized to provide low temperature for the first heat source LT1. This is one stage internal cascading to provide a greater temperature lift.

[0155] Similar to the embodiment of FIG. 7, the working fluid may be transferred between the streams 1113, 1108 as suggested by dotted stream line 1123 in FIG. 8. This transfer of working fluid will depend on how large the first heat source LT1 is compared to the second heat source LT2. The direction of liquid transfer may be adjusted to meet the heat duty of the first heat source LT1.

[0156] Another embodiment of a MCIC heat pump 1200 is shown in FIG. 9. The MCIC heat pump 1200 is substantially similar to the other MCIC heat pumps shown in FIGS. 1A-8. and described herein. Accordingly, similar reference numbers in the 1200 series indicate features that are common between the other MCIC heat pumps and the MCIC heat pump 1200. The description of the other MCIC heat pumps is incorporated by reference to apply to the MCIC heat pump 1200 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1200.

[0157] The MCIC heat pumps in the embodiments of FIGS. 1A-7 were for pumping heat from either a single heat source to multiple heat sinks or multiple heat sources to a single heat sink. FIG. 9 is an illustrative embodiment of a two-stage MCIC heat pump 1200 for pumping heat from more than one heat source to more than one heat sink. As shown in FIG. 9, the MCIC heat pump 1200 pumps heat from three heat sources LT1, LT2, LT3 to two heat sinks HT1, HT2. The temperature of the first heat source LT1 is lower than the temperature of the second heat source LT2, which in turn is lower than the temperature of the third heat source LT3. The temperature of the first heat sink HT1 is higher than the temperature of second heat sink HT2. The temperatures of both heat sinks HT1, HT2 are higher than any of the heat sources LT1, LT2, LT3.

[0158] The heat pump 1200 includes a compressor C1, separation and intermediate condensation units 1230A, 1230B, a heat exchanger 1235, an expansion valve 1238, and fluid lines in fluid communication therebetween as shown in FIG. 9. Each separation and intermediate condensation unit 1230A, 1230B has a separator 1232A, 1232B, an intermediate heat exchanger 1234A, 1234B, and an expansion valve 1236A, 1236B as shown in FIG. 9.

[0159] During operation, a low-pressure gaseous stream 1204 of the mixed component is first compressed in the heat pump compressor C1 to provide a high-pressure stream 1209 of the mixed component. The high-pressure stream 1209 is then partially condensed. The high-pressure stream 1209 is then partially condensed by transferring the desired heat from the high-pressure stream 1209 to the heat sink HT1, resulting in a partially condensed two-phase stream 1201A.

[0160] The first separation and intermediate condensation unit 1230A then separates the partially condensed two-phase stream 1201A and separately condenses the separated vapor stream 1202A and further cools the separated liquid stream 1203A. As shown in FIG. 9, the partially condensed two-phase stream 1201A is separated into a first separated vapor stream 1202A and a first separated liquid stream 1203A by the first separator 1232A. The first separated vapor stream 1202A is rich in lighter components and the first separated liquid stream 1203A is rich in heavier components.

[0161] To get one additional cascading temperature, the first separated vapor stream 1202A is now partially condensed by transferring heat to the second heat sink HT2 as shown in FIG. 9. Condensing the first separated vapor stream 1202A by transferring heat to the second heat sink HT2 provides the second two-phase stream 1201B. The second two-phase stream 1201B is then separated by the second separator 1232B of the second separation and intermediate condensation unit 1230B as shown in FIG. 9.

[0162] Similar to the embodiment in FIG. 3, the second two-phase stream 1201B is separated into a second separated vapor stream 1202B (analogous to stream 602B in FIG. 3) and a second separated liquid stream 1203B (analogous to stream 603B in FIG. 3). The second separated vapor 1202B is condensed in the first and second heat exchangers 1234A and 1234B to provide the stream 1208. The pressure of stream 1208 is reduced across the expansion valve 1238 to provide a low-pressure predominantly liquid stream 1219, which is vaporized against the first heat source 1 LT1, which results in a two-phase or a vapor stream 1211B as shown in FIG. 9.

[0163] The separated liquid streams 1203A, 1203B from the separators 1232A and 1232B are subcooled by transferring heat in the respective heat exchangers 1234A, 1234B, 1235 and throttled across a respective expansion valve 1236A, 1236B to provide a low-pressure predominantly liquid stream 1214A, 1214B, respectively. The liquid in the stream 1214A and the stream 1214B is vaporized by transferring heat from the third heat source LT3 and the second heat source LT2, respectively. As shown in FIG. 9, the resulting streams are then mixed with streams 1211A, 1211B, respectively. After further heat exchange, finally, a low-pressure gaseous mixed component stream 1204 is formed, which is compressed again to complete the heat pump loop.

[0164] Another embodiment of a MCIC heat pump 1300 is shown in FIG. 10. The MCIC heat pump 1300 is substantially similar to the MCIC heat pump 1200 shown in FIG. 9 and described herein. Accordingly, similar reference numbers in the 1300 series indicate features that are common between the MCIC heat pump 1200 and the MCIC heat pump 1300. The description of the MCIC heat pump 1200 is incorporated by reference to apply to the MCIC heat pump 1300 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1300.

[0165] FIG. 10 is another illustrative embodiment of a two-stage MCIC heat pump 1300 for pumping heat from more than one heat source to more than one heat sink. The heat pump 1300 includes a compressor C1, separation and intermediate condensation units 1330A, 1330B, a heat exchanger 1335, an expansion valve 1338, and fluid lines in fluid communication therebetween as shown in FIG. 10. Each separation and intermediate condensation unit 1330A, 1330B has a separator 1332A, 1332B, an intermediate heat exchanger 1334A, 1334B, and an expansion valve 1336A, 1336B as shown in FIG. 10.

[0166] However, in the embodiment of FIG. 10, the second and third heat sources LT2, LT3 are moved so that the heat is transferred to the respective stream after mixing (e.g., the heat sources LT2, LT3 are moved to lines for streams 1215B, 1215A, respectively). The location of heat sources depends on their temperature. Whether to place the heat sources before or after mixing depends on the temperature requirements. A higher temperature requirement means they are placed before mixing.

[0167] As shown in FIG. 10, the second separated liquid stream 1303B from the second separator 1332B, after subcooling and throttling, is directly mixed with the stream 13111B. This combined stream is heated against the second heat source LT2. Similarly, the first separated liquid stream 1303A from the first separator 1332A, after subcooling and throttling, is directly mixed with the stream 1311A, and this combined stream is then heated with the heat from the third heat source LT3. In some embodiments, the second heat source LT2 could heat exchange in the second intermediate heat exchanger 1334B against the mixed stream, and the third heat source LT3 could heat exchange in first intermediate heat exchanger 1334A.

[0168] The MCIC heat pump or heat pump cycles in FIGS. 1A-7 and 9-10 illustrate common features. The high pressure gaseous mixed component stream is partially condensed to provide a vapor stream rich in lighter components and a liquid stream enriched in the heavier components. The vapor stream rich in lighter components, or vapor stream derived from this stream, is eventually condensed, reduced in pressure, and is heated by heat exchange with a first heat source, and generally, this first heat source is the heat source at the lowest temperature of all the heat sources. When more than one heat sink is to be serviced, this vapor stream rich in the lighter components provides that heat duty to the heat sink by partial or total condensation.

[0169] When only one heat source is available, the liquid stream enriched in the heavier components is eventually vaporized at a lower pressure through a heat exchange against the condensing vapor stream rich in the lighter components or a vapor stream derived from this vapor stream rich in the lighter components. However, when more than one heat source is available, the liquid stream rich in the heavier components or a liquid stream derived from it is reduced in pressure and heated by heat exchange with a second heat source, which is different from the first heat source and is generally at a temperature which is higher than the first heat source.

[0170] Within the above common features, it is possible to draw heat pumps with many other variations. Another embodiment of a MCIC heat pump 1400 is shown in FIG. 11. The MCIC heat pump 1400 is substantially similar to the MCIC heat pump 1000 shown in FIG. 7 and described herein. Accordingly, similar reference numbers in the 1400 series indicate features that are common between the MCIC heat pump 1000 and the MCIC heat pump 1400. The description of the MCIC heat pump 1000 is incorporated by reference to apply to the MCIC heat pump 1400 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1400.

[0171] FIG. 11 shows another variation to the MCIC heat pump 1000 in the embodiment of FIG. 7. In FIG. 11, the first separated vapor stream 1402A rich in the lighter components is condensed, reduced in pressure and heated with heat available in the lowest temperature heat source LT1. However, the first separated liquid stream 1403A rich in the heavier components is reduced in pressure to an intermediate pressure, partially vaporized by heat exchange with the second heat source LT2, and separated into a second separated vapor stream 1402B and a second separated liquid stream 1403B as shown in FIG. 11. While the second separated liquid stream 1403B is reduced in pressure and vaporized to condense the stream 1402A, the intermediate pressure vapor stream 1402B may be warmed in the heat exchanger 1434A and fed to an intermediate stage of the recycle heat pump compressor C1 as shown in FIG. 11.

[0172] In other embodiments, multiple compressors may be used instead of a multi-stage compressor (e.g., two compressors). The intermediate pressure vapor stream 1402B may be warmed in the heat exchanger 1434A and fed between the compressors (e.g., after a first compressor but before the second compressor).

[0173] Another embodiment of a MCIC heat pump 1500 is shown in FIG. 12. The MCIC heat pump 1500 is substantially similar to the MCIC heat pump 1100 shown in FIG. 8 and described herein. Accordingly, similar reference numbers in the 1500 series indicate features that are common between the MCIC heat pump 1100 and the MCIC heat pump 1500. The description of the MCIC heat pump 1100 is incorporated by reference to apply to the MCIC heat pump 1500 except in instances when it conflicts with the specific description and drawings of the MCIC heat pump 1500.

[0174] As shown in FIG. 12, the two-phase stream is generated through the partial boilup of the totally condensed (by heat exchange with a heat sink) high pressure mixed component stream through heat exchange with a heat source that is at a temperature which is higher than the lowest temperature heat source. The vapor stream from this partial boilup is eventually condensed, throttled to a lower pressure and heated against the heat from a colder heat source which is generally the lowest temperature heat source. The liquid stream from this partial boilup is used to condense the vapor (or a vapor stream derived from this vapor stream) resulting from the partial boilup. However, in the illustrative embodiment, a portion of the separated vapor stream 1502A is warmed and recycled to an intermediate stage of the recycle heat pump compressor C1 as shown in FIG. 12. The remaining portion of separated vapor stream 1502B is treated similar to stream 1102 in FIG. 8.

[0175] FIG. 13 shows the general use of the MCIC heat pumps of the present disclosure in different industrial applications or manufacturing industries. For example, the heat pumps may be used with multiple heat sinks and multiple heat sources located in chemical, petrochemical, food and beverages plants, plastic plants, textile plants, pulp and paper plants, and / or pharmaceutical plants. In a chemical or petrochemical plant, multiple heat sources are available including: (i) condensers of distillation columns, (ii) exothermic reactors (e.g., fermenters, synthesis gas to methanol, Fischer Tropsch reactors, methanol to dimethyl ether, methanol to gasoline, Haber Brosch reactors for ammonia synthesis, etc.), (iii) heat from process streams being cooled, (iv) condensing streams, (v) from solidification / crystallization of a stream, (vi) a waste heat, etc. Similarly, there are various heat sinks, including: (i) reboilers of distillation columns, (ii) endothermic reactors (e.g., naphtha crackers, catalytic reforming reactors, etc.), (iii) boiling liquid streams, (iii) melting solids, (iv) steam generators, (v) heating of process streams, etc.

[0176] Among the above industrial applications, distillation separations in chemical or petrochemical industry may be of special importance. Distillation is the workhorse of separations may account for 90%-95% of liquid phase separations and 2.5% of the total energy used in the United States. FIG. 14 shows an example of using an MCIC heat pump for two heat sources and two heat sinks and a separation using two distillation columns. In this case, feed mixture ABC is separated into three product streams, each enriched in one of the components. Component A is the lightest component, component C is the heaviest component, and component B is of intermediate volatility. Heat QC (=QC1+QC2) from the condensers of the distillation columns (equivalent to heat sink LT1 and LT2, respectively) is heat pumped using the MCIC cycle to supply heat QR (=QR1+QR2) to the bottom reboilers (equivalent of the heat sink HT2 and HT1, respectively).

[0177] FIG. 14 also shows an optional trim heat exchanger TH. The trim heat exchanger TH is configured to balance the heat load of the process. For a given distillation column, consider the case when the total heat duties for the condenser and the reboiler are quite similar. Therefore, when QC is approximately equal to QR, the added heat pump power WHP in the heat pump compressor leads to an increase in the availability of heat (QC+WHP) than the desired amount of QR, and this excess heat Q′ is removed in the trim heat exchanger TH. The location of the trim heat exchanger TH is optional and may vary between embodiments. In FIG. 14, the trim heat exchanger TH is located just before the reboiler. Alternatively, the trim heat exchanger TH could be located anywhere after supplying heat in the reboiler. In this case, the trim heat exchanger TH could be immediately after the reboiler, just before the condenser, or even part of the condenser heat exchanger. When QR is substantially greater than QC, one could add heat to the reboiler via the trim heat exchanger TH. Similarly, if QC turns out to be sufficiently greater than QR, the trim heat exchanger TH could be used to remove heat from the circuit, and in another option, all the heat from the condenser QC may not be heat pumped to the reboiler.

[0178] For the above system of multicomponent distillation, an MCIC heat pump 1600 is shown in the FIG. 15. As shown in FIG. 15, the heat pump 1600 is similar to the MCIC heat pump 400 in FIG. 1A with an added second heat source LT2. The second heat source LT1 may be added on the line for the two-phase stream 415, i.e., the two-phase stream may be heated against the second heat source LT2. In FIG. 15, the first heat source LT1 refers to the condenser Qc1 at the top of the feed column ABC, the second heat source LT2 refers to the condenser Qc2 at the top of the column with feed BC. Similarly, the first heat sink HT1 refers to the reboiler QR2 at the bottom of the distillation column with feed BC, and the second heat sink HT2 refers to the reboiler QR1 at the bottom of the distillation column with ABC feed. Note that the temperature of the reboiler QR2 is greater than the temperature of the reboiler QR1, and temperature of the condenser Qc1 is lower than the temperature of the condenser Qc2. For the case when total sum of condenser duties is approximately equal to the total sum of reboiler duties, a trim heat exchanger may be included at the exhaust of the heat pump compressor.

[0179] The use of intermediate condensers and intermediate reboilers may improve distillation efficiency. FIG. 16 shows a distillation column with an intermediate condenser with heat duty QIC located in the rectifying section and an intermediate reboiler with heat duty QIR located in the stripping section. Another embodiment of a MCIC heat pump, similar to the MCIC heat pump 1600 in FIG. 15 or similar to a derivative of the MCIC heat pumps in FIGS. 2-4 with an added heat source may be used to pump heat from both of the condensers to both of the reboilers. Alternatively, if there was only an intermediate reboiler but no intermediate condenser, then MCIC could pump heat from the condenser to both the reboiler and intermediate reboiler using any one the heat pumps in FIGS. 1A-4 or their derivative.

[0180] Similar to FIG. 14, FIG. 17 also shows an example of separation using two-distillation columns. In this case, the second column has an intermediate reboiler in the stripping section. An MCIC heat pump may be used to pump heat from the two heat sources (both the condensers) to the three heat sinks (both the reboilers and an intermediate reboiler on the second column). QA and QB refer to the condenser duty of column 1 and column 2, respectively. QBC is the reboiler duty for column 1, while QIR and QC denote the intermediate reboiler and reboiler duty of column 2. For this, where there are two heat sources and three heat sinks, the MCIC heat pump 1300 of FIG. 10 may be adapted by removing a heat source and adding a heat sink (e.g., the third heat sink HT3 in FIG. 18) after the second separator 1332B (e.g., separator 1 in FIG. 18), such that second separated vapor stream from the second separator 1332B at least partially condenses against the third heat sink HT3).

[0181] FIG. 18 shows a two-stage MCIC heat pump 1700 that may be adapted for such distillation system. In this process, the vapor stream from separator 2, after heat exchanger with the third heat sink HT3 could be an all liquid or a two-phase stream. In the process of FIG. 17, the temperature of intermediate reboiler QIR could be greater than or lower than the temperature of the reboiler QBC. Of these two reboilers, the one with the greater temperature corresponds to the Heat sink 2. FIG. 19 shows a single-stage MCIC heat pump 1800, which is an alternative to the two-stage MCIC heat pump 1700 of FIG. 18, which may also be adapted for the distillation system of FIG. 17. In this process, the second and third heat sinks HT2, HT3 are placed in series, as shown in FIG. 19.

[0182] The MCIC heat pumps of the present disclosure may also be useful for heat-integrated distillation columns (HIDiCs). Heat-integrated distillation columns (HIDiCs) are a configuration for distillation systems, offering an alternative method for the thermal integration of the rectifying and stripping sections. In the HIDiC configurations, the rectifying section functions at a higher pressure than the stripping section. Heat transfer in the HIDiC occurs along the entire length of each section, leading to continuous condensation in the rectifying section and continuous evaporation in the stripping section. Such systems are therefore configured to continually transfer heat from the rectifying section to the stripping section by raising the pressure of the rectifying section above the pressure of the stripping section. However, in this mode of heat transfer, optimal heat transfer profiles may not be achieved.

[0183] FIG. 20 shows an alternate process to better match the heat transfer between the two distillation sections. Note the entire distillation column now operates at the same pressure. In FIG. 20, the MCIC heat pump 2300 does not show the separators for liquid collection, but liquid is collected from the heat pump loop at various locations along the stripping section. In this, the compressed high-pressure mixed component stream enters the column at the bottom (highest temperature), and the stream condenses along the length of the column such that the temperature profile of the condensing stream and the column match. As the upward moving mixed-component stream continues to condense, the liquid is withdrawn out at various locations shown in the FIG. 20 at column locations “1”, “2”, “3”, and “4”.

[0184] These liquid streams are then subcooled in the heat exchangers 2334 and 2335, after which they are throttled across expansion valves to give predominantly liquid streams 2314A, 2314B, 2314C, and 2314D, respectively. On the other side, the stream at location “5” which can be a liquid or a two-phase stream is also further cooled and throttled to give a low-pressure predominantly liquid stream 2314E, which extracts heat from the top of the column (lowest temperature). The streams 2303A, 2303B, 2303C, 2303D and 2303E progressively become richer in the lighter components and therefore, after subcooling and throttling, the streams 2303A, 2303B, 2303C, 2303D and 2303E vaporize at progressively lower temperature. Therefore, stream 2314E (derived from the subcooling and throttling of stream 2303E) is vaporized by heat exchange at the top of the distillation column to give low-pressure vapor stream 2319 and the condensing duty at the top of the distillation column.

[0185] The liquid streams 2314D, 2314C, 2314B, and 2314A, are mixed with the vapor stream 2319 in the order as shown in FIG. 20, and the liquid in the resulting stream then vaporizes against the vapor stream drawn out from locations shown in the column “9”, “8”, “7”, and “6”, respectively. In one of the options, the stream2314D may be drawn from the end of the heat exchanger 2335 and mixed with stream 2319 before reentering the heat exchanger 2335 as a combined stream. The use and location of the trim exchanger are optional. While shown after the heat pump compressor C1, the trim exchanger may be located at any convenient place in the heat pump loop. The MCIC heat pump 2300 provides a better way to pump heat from the rectifying section to the stripping section.

[0186] FIG. 21 shows an alternative arrangement to efficiently transfer heat from various locations in the rectifying section to appropriate locations in the stripping section of the distillation column. The high-pressure mixed component gaseous stream partially condenses against liquid at the bottom of the column (location “1”). The two-phase stream 2401A is separated in the first separator to give vapor stream 2402A and liquid stream 2403A. The vapor stream 2402A then partially condenses against the liquid at location “2” to give a two-phase stream 2401B. The two-phase stream 2401B is then separated into vapor stream 2402B and liquid stream 2403B. The vapor stream 2402B also partially condenses against the liquid present at location “3” to give a two-phase stream 2401C. The two-phase stream 2401C is separated in the third separator into a vapor stream 2402C and liquid stream 2403C. The vapor stream 2402C is condensed and subcooled in the heat exchanger 2434 and is then throttled to give a low-pressure predominantly liquid stream 2419. The stream 2419 vaporizes by heat exchange against the vapor stream at the top of the column at location “6”, which produces a vapor stream 2411.

[0187] The separated liquid stream from the first two separators, 2403A and 2403B, are also subcooled in the heat exchanger 2434 and are throttled to give low-pressure predominantly liquid streams 2414A and 2414B, respectively. The throttled predominantly liquid streams 2414A and 2414B then at least partially vaporize against the vapor present at locations 4 and 5, respectively, to produce streams 2419A and 2419B, either of which could be a vapor or two-phase stream. The liquid stream from the third separator is also subcooled and throttled, after which it mixes with the vapor stream 2411. The liquid in the two-phase stream 2415 then vaporizes against the condensing vapor stream 2402C in the heat exchanger 2434. Along with it, both streams 2419A and 2419B also mix along stream 2415 at appropriate locations in the heat exchanger 2434.

[0188] The heat exchanger 2434 allows the vaporization, condensation, subcooling, and superheating of different streams such that the temperature profile is maintained with no temperature crossover. Eventually, low-pressure gaseous mixed component stream 2404 is obtained, which is again compressed to complete the heat pump loop. In order to balance the heat duties between various locations in the stripping and the rectifying sections, one may use the option whereby a portion of the liquid from 2403A could be blended with either or both of the liquid streams 2403B and 2403C or after subcooling with liquid stream 2408. Similarly, a portion of the liquid 2403B could be blended with liquid 2403C or after subcooling with liquid stream 2408.

[0189] The present disclosure relates to MCIC heat pumps for pumping heat from heat source(s) to heat sink(s), over a wide range of temperatures. The different MCIC heat pumps use a mixed component heat pump fluid that enables the pumping of heat from multiple distinct heat sources to multiple distinct heat sinks with internal cascading. The mixed component working fluid may be separated and partially condensed and / or vaporized to achieve the desired temperature lift. These heat pump configurations may be used in various industrial applications that have multiple low-temperature heat sources and multiple high-temperature heat sinks.

[0190] According to an aspect of the present disclosure, a heat pump with internal cascading cycle (e.g., the MCIC heat pumps in embodiment discussed above) is used for pumping heat either from a single heat source to multiple heat sinks, from multiple heat sources to a single heat sink, or from multiple heat sources to multiple heat sinks. The MCIC heat pump cycle includes: (i) providing a low-pressure gaseous mixed component stream containing two or more components with different boiling points; (ii) compressing the low-pressure gaseous mixed component stream to a high pressure to provide the high-pressure mixed component stream, which is a vapor or a gaseous stream; (iii) partially condensing the mixed component stream by providing heat to a heat sink to give a partially condensed two-phase mixed component stream; (iv) separating the partially condensed two-phase mixed component stream into two streams, a separated liquid stream and a separated vapor stream; (v) eventually reducing the pressure of the separated liquid stream and vaporizing the separated liquid stream by heat exchange either against a heat source or a process stream; (vi) condensing a stream derived from the separated vapor stream in step (iv) either by heat exchange with the process streams or by providing heat to another heat sink; (vii) reducing the pressure of the condensed stream from step (vi) and partially vaporizing the liquid in this stream by heat exchange with another heat source; (viii) eventually mixing the vaporized stream from step (vii) with the separated liquid stream from step (iv) or with vaporized stream from step (v); and (ix) heating the resulting stream of step (viii) to produce the low-pressure gaseous mixed component stream provided in step (i).

[0191] In some embodiments, the separated vapor stream from step (iv) may be partially condensed to provide a second two-phase stream. The second two-phase stream may be separated in the second separator to provide the second separated vapor stream and the second separated liquid stream. The second separated vapor stream may then be completely condensed against another heat sink, reduced in pressure, and vaporized by receiving heat from a heat source. This vaporized stream is eventually mixed with the separated liquid streams from each of the partial condensation steps to provide the low-pressure gaseous mixed component stream in step (i).

[0192] In some embodiments, the pressure of the second separated liquid stream may be reduced, then mixed with the stream vaporized by receiving heat from the heat source. This combined stream may be vaporized by heat exchange with a heat source stream. The combined vaporized stream may be mixed with the separated liquid stream from step (iv) and may be vaporized against another heat source to provide the low-pressure gaseous mixed-component stream in step (i).

[0193] In some embodiments, the separated vapor stream from the step (iv) may be partially condensed against a heat sink, creating a second two-phase stream. The second two-phase stream may be separated in the second separator to provide second separated second vapor stream and liquid stream. The separated vapor is eventually condensed, throttled and is vaporized against a heat source. In some embodiments, the derived vapor from the second separator may be condensed against the derived liquid from the first and / or second separator. In some embodiments, the second separated vapor stream may be partially condensed against a heat sink, creating a third two-phase stream. The third two-phase stream may be separated in the third separator, creating a third separated vapor and liquid stream. The third separated vapor stream may be eventually condensed, throttled and vaporized against a heat source.

[0194] In some embodiments, the separated liquid stream from step (iv) may be divided into two parts. The first part may be throttled and vaporized against one of the heat sources. In some embodiments, the separated liquid from step (iv) may be throttled and partially vaporized against a heat source to create a second two-phase stream. The second two-phase stream may be separated into second vapor and second liquid stream. The separated vapor stream is eventually condensed, throttled, and vaporized against a heat source.

[0195] The heat pump cycle may be used in conjunction with a distillation column, whereby the mixed component stream in step (ii) is partially condensed by providing boilup at the bottom of the distillation column; the resulting two-phase stream is separated according to step (iv) into a first separated liquid stream and a first separated vapor stream; the first separated vapor stream is again partially condensed to provide a second partially condensed stream according to step (iii) by providing boilup at an intermediate location of the distillation column; the second partially condensed stream is separated according to step (iv) into second separated liquid stream and second separated vapor stream, the second separated vapor stream is partially condensed to provide a third partially condensed stream according to step (iv) into a third separated liquid stream and third separated vapor stream; the third separated vapors stream is condensed according to step (vi) and then its pressure is reduced according to step (vii) and it is vaporized by providing condensing duty at the top of the distillation column and the vaporized stream is mixed with the third separated liquid stream according to step (viii) which is then heated according to step (ix); the second separated liquid is reduced in pressure and at least partially vaporized by providing a condensing duty at the first intermediate location of the rectifying section in the distillation column, the resulting vaporized stream is treated according to steps (viii) and (ix); the pressure of the first separated liquid stream is reduced and it is at least partially vaporized by providing condensing duty at a second intermediate location of the rectifying section, which is below the first intermediate location of the rectifying section in the distillation column; the resulting vaporized stream is treated according to steps (viii) and (ix) to provide the low-pressure gaseous mixed component stream for step (ii).

[0196] In some embodiments, more than one partial condensation may be used between the first and the last partial condensations. The resulting vapor and liquid streams are treated in the sequential order with respect to the location in the distillation column as described above.

[0197] The heat pump cycle may be used in conjunction with a distillation column, whereby the mixed component stream in step (iii) is continually partially condensed by providing boilup along the length of the stripping section of the distillation column; liquid streams are withdrawn from various locations of this continually partially condensing mixed component stream with the bottom most liquid being the richest in the heavier components and the concentration of heavier components gradually decreasing with the height of the withdrawal location, and at the top withdrawing location, the uncondensed stream which is either a two-phase stream or a vapor stream, this uncondensed stream is condensed according to step (vi) and reduced in pressure and vaporized by providing condensing duty at the top of the rectifying section of the distillation column; the vaporized stream is warmed in the heat exchanger while providing condensing duty at the appropriate locations in the rectifying section of the distillation column; the liquid streams withdrawn while providing boilup in the stripping section are reduced in pressure and mixed with the vaporized stream being warmed in the heat exchanger according to steps (viii) and (ix), whereby this mixing is done to maintain appropriate temperature profile in heat exchanger and the condensing duty at any location in the rectifying section is provided by withdrawing a vapor stream from that location and at least partially condensing it in the heat exchanger by heat exchanger with the warming stream and returning it to the appropriate location in the rectifying section.

[0198] According to another aspect of the present disclosure, a heat pump with internal cascading cycle may be used for pumping heat from a single heat source to multiple heat sinks, from multiple heat sources to a single heat sink, or from multiple heat sources to multiple heat sinks. The heat pump cycle may comprise: (i) providing a low-pressure gaseous mixed component stream containing two or more components with different boiling points; (ii) compressing the low-pressure gaseous mixed component stream to a high pressure, providing the high-pressure mixed component stream, which is a vapor or a gaseous stream; (iii) completely condensing the mixed component stream by providing heat to a heat sink, to provide the high-pressure mixed component stream, which is a liquid stream; (iv) eventually reducing the pressure of the liquid stream to an intermediate pressure and partially vaporizing the liquid stream against a heat source, creating a two-phase mixed component stream; (v) separating the partially vaporized two-phase mixed component stream into two streams, a separated vapor stream and a separated liquid stream; (vi) eventually condensing the stream derived from separated vapor stream of step (v) against a process stream; (vii) throttling and vaporizing the condensed stream from step (vi) against a heat source; (viii) eventually reducing the pressure of the separated liquid stream from step (v) and either vaporizing the separated liquid stream by heat exchange either against a heat source or a process stream, or mixing the separated liquid stream with the vaporized stream from step (vii); (ix) vaporizing the mixed stream from step (viii) by heat exchange either against a heat source or a process stream to eventually provide the low-pressure gaseous mixed component stream in step (i).

[0199] In some embodiments, a derived stream from the separated vapor stream of step (vi) may be condensed, throttled and partially vaporized against a heat source to produce a two-phase mixed component stream. The two-phased stream may be separated into vapor and liquid stream. The vapor stream is eventually condensed, throttled, and vaporized against another heat source.

[0200] In some embodiments, the heat source and heat sink temperatures are distinct. These heat sources and heat sinks may be located in a chemical plant, a petrochemical plant, a food and beverage plant, a pulp and paper plant, a plastic and textile plant, or a pharmaceutical plant. For example, the pulp and paper industry uses heat at 90 degrees Celsius to 240 degrees Celsius for drying, 110 degrees Celsius to 180 degrees Celsius for cooling, and 40 degrees Celsius to 150 degrees Celsius for bleaching. Similarly, the food and beverage industry uses heat for drying, evaporation, pasteurization, sterilization, boiling, distillation, blanching etc. For a chemical or petrochemical plant, the heat source may be one of an exothermic reactor, a condensing stream, a condenser of a distillation column, from solidification of a stream, heat from a process stream that is being cooled, a waste heat, or another suitable heat source. The heat sink may be one of an endothermic reactor, a boiling liquid stream, a melting solid, a reboiler of a distillation column, stream generation, heating of a process stream, or another suitable heat sink.

[0201] In some embodiments, one of the heat sources may be the condenser of a distillation column, while one of the heat sinks may be the reboiler of a distillation column. The distillation column may be the same distillation column or may be different distillation columns. In some embodiments, one of the heat sources may be an intermediate condenser located in a rectifying section of the distillation column. In some embodiments, one of the heat sinks may be an intermediate reboiler located in a stripping section of a distillation column.EXAMPLES

[0202] The examples and preparations provided below further illustrate and exemplify particular aspects of embodiments of the disclosure. It is to be understood that the scope of the present disclosure is not limited in any way by the scope of the following examples.Example 1Hexane-Undecane (C6 / C11) Separation with an Intermediate Reboiler

[0203] Separating hexane-undecane in a distillation column with an intermediate reboiler, refer to FIG. 22 that shows a distillation column with an intermediate reboiler. Reboiler duty (QR) is 430 kW, intermediate reboiler duty (QIR) is 276 kW, and the condenser duty (QC) is 706 kW. The feed and other process conditions are listed in the table below (Table 1).TABLE 1Feed Parameters Associated with C6-C11 Distillation for Example 1Mole fraction (Hexane, Undecane)Feed Flowrate (kmol / hr)0.75, 0.25100

[0204] The temperature of different streams of the distillation column which are useful for the calculation is given in the Table 2.TABLE 2Temperatures and Heat Duties of Heat Sources and Sinks for Example 1StreamsTemperature (K)2506, reboiler inlet stream4662505, reboiler outlet stream4612501, intermediate reboiler inlet stream3942502, intermediate reboiler outlet stream4432503, condenser inlet stream3422504, condenser outlet stream342Using hexane (C6) as the heat pump fluid in a single-loop heat pump configuration (and it uses a single compressor) gives a compressor power of 542 kW, with a pressure ratio across the compressor of 22.4 (having a throttling pressure of 0.75 bar, which is below ambient). The volumetric flowrate comes out to be 1.739 m3 / s.

[0205] If a single-stage MCIC heat pump cycle is utilized for the same purpose, with mixed component fluid as the heat pump fluid, the components and composition of the gaseous mixed component fluid are given in the table below (Table 3).TABLE 3Composition of Mixed Component Heat Pump Fluid Used for Example 1ComponentPropanePentaneHexaneMole Fraction0.0240.3900.586The flowsheet used for this is derived from the FIG. 1A (with an addition of a trim heat exchanger just before throttling), the exact flowsheet can be referred from the FIG. 23.

[0206] When a single-stage MCIC configuration is used, the pressure ratio reduces to 16.3, which is around a 27% reduction. The volumetric flow rate reduces from 1.739 to 1.124 m3 / s, which is approximately a 35% reduction, signifying a tremendous reduction in compressor size. The power of heat pump compressor is calculated to be 538 kW. The temperature of different streams of the MCIC flowsheet is listed below in Table 4. In this table, X1, X2, X3 are mole fraction of propane, pentane and hexane respectively in the given stream.TABLE 4Temperature, Pressure, Flowrate and Composition ofDifferent Streams of the MCIC Flowsheet for Example 1TemperaturePressureFlowrateCompositionStreams(K)(bar)(kmol / hr)X1, X2, X32609473.821.2170.00.024, 0.390, 0.5862601464.021.2170.00.024, 0.390, 0.5862606462.521.286.20.034, 0.424, 0.5422607456.621.286.20.034, 0.424, 0.5422619319.81.386.20.034, 0.424, 0.5422611338.31.386.20.034, 0.424, 0.542Example 2Multicomponent Distillation of Benzene-Toluene-Xylene Mixture

[0207] FIG. 14 represents the multi-component distillation sequence for benzene-toluene-xylene mixture. The parameters associated with it are listed in Table 5.TABLE 5Parameters of Distillation System Associated With Example 2Feed Mole fraction (Benzene, 0.25, 0.35, 0.4Toluene, Xylene)Feed Flowrate (kmol / hr)100Reboiler 1 Temperature(K)397-400Reboiler 2 Temperature(K)415Reboiler 1 Heat Duty, QR1(kW)697Reboiler 2 Heat Duty, QR2 (kW)1055Condenser 1 Temperature (K)357Condenser 2 Temperature (K)387Condenser 1 Heat Duty, QC1 (kW)659Condenser 2 Heat Duty, QC2 (kW)1039Using hexane as the heat pump fluid in a single-loop heat pump cycle (with a single compressor) with two heat sinks and two heat sources gives a compressor power of 468 kW. The pressure ratio is 4.63, with a volumetric flow rate of 1.531 m3 / s. Note in this single compressor case, the high-pressure heat pump vapor stream is condensed at the same high pressure in both the reboilers and the resulting liquid is throttled and vaporized at the same low pressure in both the condensers.

[0208] The actual flowsheet utilized for pumping heat is shown in FIG. 24. The mixed component heat pump fluid utilized for this purpose is given in the table below (Table 6).TABLE 6Composition of Mixed Component Heat Pump Fluid Used for Example 2ComponentPentaneHexaneOctaneMole Fraction0.250.610.14

[0209] When a single-stage MCIC configuration is used (FIG. 24), the pressure ratio remains the same as for the single-loop hexane heat pump process, with compressor pressure of 7.2 bar and throttling pressure of 1.5 bar. However, the volumetric flow rate reduces from 1.531 to 1.253 m3 / s, which is approximately a 18% reduction, signifying a reduction in compressor size. The power requirement for the base case was 468 kW, but with a single-stage MCIC, the compressor power is reduced to 420 kW, which is a 10.2% power reduction.

[0210] Table 7 lists the temperature of different streams from the single-stage MCIC flowsheet. In this table, X1, X2, X3 are mole fraction of pentane, hexane and octane respectively in the given stream.TABLE 7Temperature, Pressure, Flowrate and Composition of Different Streams of the MCIC Flowsheet for Example 2.Temperature PressureFlowrateCompositionStream(K)(bar)(kmol / hr)X1, X2, X32709438.07.22240.25, 0.61, 0.142701420.17.22240.25, 0.61, 0.142702420.07.298.60.34, 0.60, 0.062707405.87.298.60.34, 0.60, 0.062719342.01.598.60.34, 0.60, 0.062711353.11.598.60.34, 0.60, 0.062715346.71.52240.25, 0.61, 0.142716366.31.52240.25, 0.61, 0.14Example 3Multicomponent Distillation of Benzene-Toluene-Xylene Mixture with an Intermediate Reboiler

[0211] Example 2 can be extended further by introducing an intermediate reboiler in the second column as shown in FIG. 17 with an equivalent cycle in FIG. 25, creating three heat sinks and two heat source systems. The feed flow rate and condition are the same as in example 2, but the duty of the column 2 reboiler (QC) and column 2 intermediate reboiler (QIR) is 635 kW and 425 kW, respectively. The temperature of the intermediate reboiler's inlet and outlet streams is 406 and 408 K, respectively. If hexane is used as the heat pump fluid in a single loop, the compressor power and other resulting parameters will be the same (given in the Example 2 section), which are listed in the following Table 8.TABLE 8Results of Example 2 When a Single-Loop With Single Component Is UsedPressure Ratio4.63Volumetric Flowrate1.531 m3 / sHP Compressor Power468 kW

[0212] For this case, a two-stage MCIC would be useful, as shown in FIG. 25. This process is derived from FIG. 18. Table 9 shows the composition of high pressure gaseous mixed component stream 2509 in FIG. 22.TABLE 9Composition of Mixed Component Heat Pump Fluid Used for Example 3ComponentPentaneHexaneOctaneMole Fraction0.150.610.24

[0213] Using the mixed component heat pump fluid listed in Table 9, the compressor power comes out to be 380 kW, which is approximately 9.5% lower than the example 2 case (using MCIC) and 18.8% lower compared to a single-loop heat pump cycle using hexane as the heat pump fluid. As compared to the single-loop heat pump, the volumetric flow rate also reduces to 1.48 m3 / s. The pressure ratio also reduces from 4.63 (single-loop heat pump) to 4.42, with the compressor pressure of 5.3 bar and a throttling pressure of 1.20 bar.

[0214] Stream temperatures, pressure and composition are listed in Table 10 below. X1, X2 and X3 are mole fraction of pentane, hexane and octane, respectively.TABLE 10Temperature, Pressure, Flowrate and Composition of Different Streams of the MCIC Flowsheet for Example 3Temperature Pressure FlowrateCompositionStreams(K)(bar)(kmol / hr)X1, X2, X32809435.25.3210.00.15, 0.61, 0.242801A421.05.3210.00.15, 0.61, 0.242802A421.05.3147.70.18, 0.65, 0.172801B413.25.3147.70.18, 0.65, 0.172802B413.25.397.60.22, 0.68, 0.102801C399.55.397.60.22, 0.68, 0.102819340.61.297.60.22, 0.68, 0.102811353.01.297.60.22, 0.68, 0.102815358.41.2210.00.15, 0.61, 0.242816384.01.2210.00.15, 0.61, 0.24Example 4Example for Two Heat Sources and a Single Heat Sink

[0215] FIG. 8 shows a single-stage MCIC flowsheet for a system with two heat sources and a single heat sink. This is a general example that is not pertaining to distillation. For this example, flowsheet shown in FIG. 8 is compared with a single-loop heat pump (having a pure component as heat pump fluid and a single compressor), given the fact that both the flowsheet achieves the same purpose of pumping heat from the heat sources to heat sink. The amount of heat required by heat sink 1 is 883 kW at 383 K, and the heat available from heat source 1 at 347 K and Heat source 2 at 379 K are 400 kW and 483 kW respectively. Using the mixture of the following composition (Table 11) as the mixed component fluid for the heat pump.TABLE 11Composition of Mixed Component Heat Pump Fluid Used for Example 4.ComponentPentaneHexaneOctaneMole Fraction0.250.610.14The highest pressure (P3) is 4 bar, the intermediate pressure (P2) is 2.5 bar, and the lowest pressure (P1) is 1.1 bar.

[0216] The given MCIC flowsheet can achieve the following temperatures with a mixed component flowrate of 100 kmol / hr as shown in Table 12. X1, X2 and X3 are mole fraction of pentane, hexane and octane, respectively.TABLE 12Temperature, Pressure, Flowrate and Composition of Different Streams of the MCIC Flowsheet for Example 4.TemperaturePressureFlowrateCompositionStreams(K)(bar)(kmol / hr)X1, X2, X31109417.04.0100.00.25, 0.61, 0.141101A386.14.0100.00.25, 0.61, 0.141107366.42.5100.00.25, 0.61, 0.141101B375.52.5100.00.25, 0.61, 0.141119331.91.159.80.32, 0.62, 0.061111342.31.159.80.32, 0.62, 0.06The compressor power is 154 kW, which is approximately 5% lower than that of a single-loop heat pump (using hexane as heat pump fluid). The pressure ratio is also lower: 3.6 for MCIC, compared to 4.0 for a single-loop heat pump. Similarly, the volumetric flow rate for an MCIC heat pump is 0.777 m3 / s, and for a single-loop heat pump, it is 0.963 m3 / s. This proves the benefit of MCIC heat pumps compared to single-loop heat pumps in terms of compressor power, pressure ratio, and volumetric flow rate.

Claims

1. A method of pumping heat from either at least one heat source to multiple heat sinks, multiple heat sources to at least one heat sink, or multiple heat sources to multiple heat sinks, the method comprising(i) providing a low-pressure gaseous stream of a mixed component containing two or more components with different boiling points;(ii) compressing the low-pressure gaseous stream to increase the pressure of the low-pressure gaseous stream to provide a high-pressure stream, which is predominantly a vapor or a gaseous stream;(iii) partially condensing the high-pressure stream by transferring heat to a heat sink from the high-pressure stream to provide a partially condensed two-phase stream;(iv) separating the partially condensed two-phase stream into two streams including a separated liquid stream and a separated vapor stream, wherein the separated liquid stream is eventually reduced in pressure and vaporized by heat exchange either against a heat source or a process stream;(v) condensing a stream derived from the separated vapor stream in step (iv) either by heat exchange with the process stream or by providing heat to another heat sink;(vi) reducing the pressure of the condensed stream from step (v);(vii) at least partially vaporizing the condensed stream from step (vi) by heat exchange with another heat source;(viii) mixing the vaporized stream from step (vii) with the separated liquid stream from step (iv) or with the vaporized stream from step (iv); and(ix) heating the mixed stream from step (viii) to provide the low-pressure gaseous stream of step (i).

2. The method of claim 1, further comprising:(x) partially condensing the separated vapor stream from step (iv) to provide a second partially condensed two-phase stream;(xi) separating the second partially condensed two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream;(xii) completely condensing the second separated vapor stream against another heat sink to provide a condensed second separated vapor stream;(xiii) reducing the pressure of the condensed second separated vapor stream;(xiv) vaporizing the condensed second separated vapor stream from step (xiii) by transferring heat from a heat source; and(xv) mixing the vaporized stream with the separated liquid streams from each of the partial condensation steps to provide the low-pressure gaseous stream of step (i).

3. The method of claim 2, further comprising:(xvi) reducing the pressure of the second separated liquid stream from step (xi);(xvii) mixing the vaporized stream from step (xiv);(xviii) vaporizing the mixed stream from step (xvii) by heat exchange with a heat source stream;(xix) mixing the combined vaporized stream with the separated liquid stream from step (iv); and(xx) vaporizing the mixed stream from step (xix) against another heat source to provide the low-pressure gaseous stream of step (i).

4. The method of claim 2, further comprising:(xvi) partially condensing the second separated vapor stream from step (xi) against a heat sink to provide a third partially condensed two-phase stream; and(xi) separating the third partially condensed two-phase stream into two streams including a third separated vapor stream and a third separated liquid stream, wherein the third separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

5. The method of claim 1, further comprising:(x) partially condensing the separated vapor stream from step (iv) against a heat sink to provide a second partially condensed two-phase stream; and(xi) separating the second partially condensed two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

6. The method of claim 5, further comprising:(xii) condensing the second separated vapor stream in step (xi) by transferring heat from the second separated vapor stream to one of the second separated liquid stream from step (xi) and the separated liquid stream from step (iv).

7. The method of claim 1, further comprising:(x) dividing the separated liquid stream from step (iv) into two parts, wherein one part is reduced in pressure and vaporized against one of the heat sources.

8. The method of claim 1, further comprising:(x) reducing the pressure of the separated liquid stream from step (iv);(xi) partially vaporizing the separated liquid stream against a heat source to provide a second two-phase stream; and(xii) separating the second two-phase stream into two streams, including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against a heat source.

9. The method of claim 1, wherein the heat sources and the heat sinks are part of a chemical plant, a petrochemical plant, a food and beverage plant, a pulp and paper plant, a plastic plant, a textiles plant, or a pharmaceutical plant.

10. The method of claim 9, wherein the heat source is an exothermic reactor, a condensing stream, a condenser of a distillation column, from a solidification of a stream, heat from a process stream that is being cooled, or waste heat, and wherein the heat sink is an endothermic reactor, a boiling liquid stream, a melting solid, a reboiler of a distillation column, stream generation, or heating of a process stream.

11. The method of claim 1, wherein one of the heat sources is a condenser of a distillation column and one of the heat sinks is a reboiler of a distillation column.

12. The method of claim 11, wherein the heat sources or heat sinks are part of the same distillation column.

13. The method of claim 11, wherein the heat sources or heat sinks are part of the different distillation columns.

14. The method of claim 11, wherein one of the heat sources is an intermediate condenser located in a rectifying section of the distillation column, and wherein one of the heat sinks is an intermediate reboiler located in a stripping section of the distillation column.

15. A method of pumping heat from either a single heat source to multiple heat sinks, multiple heat sources to a single heat sink, or multiple heat sources to multiple heat sinks, the method comprising:(i) providing a low-pressure gaseous stream of a mixed component containing two or more components with different boiling points;(ii) compressing the low-pressure gaseous stream to increase the pressure of the low-pressure gaseous stream to provide a high-pressure stream, which is predominantly a vapor or a gaseous stream;(iii) completely condensing the high-pressure stream by transferring heat to a heat sink from the high-pressure stream to provide a liquid stream;(iv) reducing the liquid stream to an intermediate pressure;(v) partially vaporizing the liquid stream from step (iv) against a heat source to provide a partially vaporized two-phase stream;(vii) separating the partially vaporized two-phase stream into two streams including a separated vapor stream and a separated liquid stream;(viii) condensing a stream derived from the separated vapor stream of step (vii) against a process stream;(ix) reducing the pressure of the condensed stream from step (viii);(x) vaporizing the condensed stream from step (ix) by heat exchange with a heat source; and(xi) reducing the pressure of the separated liquid stream from step (vii) and either vaporizing the separated liquid stream by heat exchange against a heat source or a process stream, or mixing the separated liquid stream with the vaporized stream from step (x) to provide the low-pressure gaseous stream of step (i).

16. The method of claim 15, further comprising:(xii) condensing a stream derived from the separated vapor stream in step (viii);(xiii) reducing the pressure of the condensed stream from step (xii);(xiv) at least partially vaporizing the condensed stream from step (xiii) by heat exchange with a heat source to provide a partially vaporized two-phase stream; and(xv) separating the partially vaporized two-phase stream into two streams including a second separated vapor stream and a second separated liquid stream, wherein the second separated vapor stream is eventually condensed, reduced in pressure, and vaporized against another heat source.

17. The method of claim 15, wherein the heat sources and the heat sinks are part of a chemical plant, a petrochemical plant, a food and beverage plant, a pulp and paper plant, a textiles plant, a plastic plant, or a pharmaceutical plant.

18. The method of claim 17, wherein the heat source is an exothermic reactor, a condensing stream, a condenser of a distillation column, from a solidification of a stream, heat from a process stream that is being cooled, or waste heat, and wherein the heat sink is an endothermic reactor, a boiling liquid stream, a melting solid, a reboiler of a distillation column, stream generation, or heating of a process stream.

19. The method of claim 15, wherein one of the heat sources is a condenser of a distillation column and one of the heat sinks is a reboiler of the same distillation column or a different distillation column.

20. The method of claim 19, wherein one of the heat sources is an intermediate condenser located in a rectifying section of the distillation column, and wherein one of the heat sinks is an intermediate reboiler located in a stripping section of the distillation column.

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