Methods for separating hydrocarbons

Abstract

A method for separating a mixed feedflow may include compressing and cooling the mixed feedflow; separating the mixed feedflow into a first vapor flow and a first liquid flow; cooling the first vapor flow to form a cooled flow; separating the cooled flow into a second vapor flow and a second liquid flow; passing the second vapor flow through one or more heat exchangers to generate a heated second vapor flow; reducing the pressure of the heated second vapor flow in a turbo expander so that work is extracted from the heated second vapor flow to form a second coolant flow; and using the work from the turbo expander to drive a generator, drive a turbo compressor, or both.

Description

Technical Field

[0001] (Cross-Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 583,442 filed on September 18, 2023, the entire content of which is incorporated herein by reference.

[0002] (Field of the Invention) Embodiments described herein generally relate to methods and systems for separating hydrocarbons.

Background Art

[0003] Various hydrocarbons such as ethylene, ethane, propylene, propane, and heavier hydrocarbons can be recovered from various product streams obtained from chemical reactors. Low-temperature separation processes can be used to recover more condensable hydrocarbons from less condensable gases or products.

Summary of the Invention

[0004] In a cryogenic separation process, a mixed feed stream can be compressed and cooled by heat exchange with other process streams and / or an external refrigeration source. As the mixed feed stream is cooled, streams containing various fractions of the mixed feed stream can be collected as high-pressure liquid streams or vapor streams. A portion of these streams may undergo depressurization and be used as a coolant stream in a heat exchanger of the separation process. During depressurization of a portion of these streams, work can be extracted from the stream using a turboexpander. The work extracted from the stream using the turboexpander can be used to compress a recirculation stream that may be sent to a downstream stage of a compressor system, thereby reducing the size of the compressor required to compress the mixed feed stream, and also reducing the energy required to compress the mixed feed stream and the recirculation stream. Furthermore, the work from the turboexpander may be used to generate electricity, which can reduce the need for external electricity.

[0005] According to one or more embodiments of the present disclosure, a method for separating a mixed feed stream is to compress a mixed feed stream, which is a mixed feed stream containing one or more C2, C3, and C4 hydrocarbons, in order to form a compressed feed stream; to cool the compressed mixed feed stream in order to form a cooled mixed feed stream; to separate the cooled mixed feed stream into a first vapor stream and a first liquid stream; to cool the first vapor stream in order to form a cooled stream; to separate the cooled stream into a second vapor stream and a second liquid stream; to pass the second vapor stream through one or more heat exchangers in order to generate a heated second vapor stream; and to form at least a light fraction, a recirculating stream, and a heavy fraction. This may include separating a liquid flow, reducing the pressure of a recirculating flow so as to at least partially vaporize it in order to form a first coolant flow, passing the first coolant flow through one or more heat exchangers in order to form a heated recirculating flow, reducing the pressure of a heated second vapor flow in a turbo expander so as to extract work from the heated second vapor flow in order to form a second coolant flow, passing the second coolant flow through one or more heat exchangers in order to provide cooling in one or more heat exchangers, and using the work from the turbo expander to drive a generator, drive a turbo compressor, or both.

[0006] Additional features and advantages of the technology disclosed herein will be described in the subsequent detailed description and will be readily apparent to those skilled in the art from that description, or will be recognized by practicing the technology as described herein, including the subsequent detailed description, the claims, and the accompanying drawings. [Brief explanation of the drawing]

[0007] The following "Modes for Carrying Out the Invention" of specific embodiments of this disclosure can be best understood in conjunction with the following drawings, where similar structures are shown with similar reference numerals. [Figure 1]This is a schematic diagram of a system for separating hydrocarbons according to one or more embodiments disclosed herein. [Figure 2] This is a schematic diagram of a system for separating hydrocarbons according to one or more embodiments disclosed herein.

[0008] It should be understood that the drawings are essentially schematic and do not, without limitation, include some components of isolation systems commonly used in the art, such as temperature transmitters, pressure transmitters, flow meters, pumps, and valves. These components will be known to be within the spirit and scope of the disclosed embodiments. However, operating components, such as those described herein, may be added to the embodiments described herein.

[0009] Herein, various embodiments are referred to in more detail, some of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. [Modes for carrying out the invention]

[0010] One or more non-limiting embodiments of a method for separating a mixed feed flow are described herein. Referring here to Figure 1, a method for separating a mixed feed flow 100 may include compressing the mixed feed flow 100 to form a compressed mixed feed flow 103. The mixed feed flow 100 may be compressed in one or more compressors. In one or more embodiments, the mixed feed flow 100 may be compressed in a first compressor 406 and a downstream compressor 408, the first compressor 406 and the downstream compressor 408 being arranged in series. For example, in the embodiment shown in Figure 1, the mixed feed flow 100 may be compressed in the first compressor 406 to form a flow 101, and the flow 101 may be further compressed in the downstream compressor 408 to form a compressed mixed feed flow 103. It should be understood that the number of compressors arranged in series is not necessarily limiting. In one or more embodiments, the mixed feed flow 100 may be compressed in the first compressor 406 and one or more downstream compressors arranged in series. For example, the mixed feed stream 100 may be compressed by 1, 2, 3, 4, or even 5 or more compressors arranged in series.

[0011] In one or more embodiments, the mixed feed stream 100 may contain one or more C2, C3, or C4 hydrocarbons. In some embodiments, the mixed feed stream may contain at least 70% by weight of C2-C4 hydrocarbons. For example, the mixed feed stream 100 may contain at least 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, or 95% by weight of C2-C4 hydrocarbons. In one or more embodiments, the C2-C4 hydrocarbons may include, but are not limited to, olefins and paraffins, including ethane, ethylene, propane, propylene, butane, and butene. In one or more embodiments, the mixed feed stream 100 may further contain one or more nitrogen, hydrogen, methane, carbon monoxide, and carbon dioxide. In some embodiments, the mixed feed stream may contain 0.1% to 15% by weight of N2, 0.01% to 10% by weight of H2, 0.01% to 10% by weight of methane, and 70% to 99% by weight of one or more of the C2, C3, or C4 components.

[0012] In one or more embodiments, the compressed mixed feed stream 103 may have a temperature of 10°C to 75°C. For example, the compressed mixed feed stream 103 may have temperatures in the ranges of 10°C to 75°C, 20°C to 75°C, 30°C to 75°C, 40°C to 75°C, 50°C to 75°C, 60°C to 75°C, 70°C to 75°C, 10°C to 65°C, 10°C to 55°C, 10°C to 45°C, 10°C to 35°C, 10°C to 25°C, 10°C to 20°C, 10°C to 15°C, or any range or combination of ranges formed from these endpoints. In one or more embodiments, the compressed mixed feed stream 103 may have a pressure of 250 psig to 500 psig. For example, the compressed mixed feed flow 103 may have pressures in the ranges of 250 psig to 500 psig, 300 psig to 500 psig, 350 psig to 500 psig, 400 psig to 500 psig, 450 psig to 500 psig, 250 psig to 450 psig, 250 psig to 400 psig, 250 psig to 350 psig, 250 psig to 300 psig, or any range or combination of ranges formed from these endpoints.

[0013] In one or more embodiments, a method for separating the mixed feed stream 100 may include cooling the compressed mixed feed stream 103 to form a cooled mixed feed stream 102. The compressed mixed feed stream 103 may be cooled in any suitable heat exchanger. The compressed mixed feed stream 103 can be generated in one or more heat exchangers. In some embodiments, the compressed mixed feed stream 103 may be cooled in a heat exchanger located within a cold box 220. In one or more embodiments, cooling of the compressed mixed feed stream 103 can be performed in a second heat exchanger 202, as shown in Figure 1. In one or more embodiments, cooling the compressed mixed feed stream 103 can cause at least a portion of the compressed mixed feed stream 103 to be condensed.

[0014] As used in this disclosure, “cold box” refers to an insulated enclosure capable of housing one or more system components. The cold box may be insulated to minimize heat transfer between the system components and the environment. In one or more embodiments, one or more heat exchangers may be located within the cold box. In some embodiments, multiple heat exchangers may be located in series within the cold box. The heat exchangers may include brazed heat exchangers, shell-and-tube heat exchangers, double-tube heat exchangers, plate heat exchangers, tubular heat exchangers, finned heat exchangers, condensers, evaporators, boilers, or combinations thereof.

[0015] In one or more embodiments, the cooled mixed feed stream 102 may be separated into a first vapor stream 104 and a first liquid stream 106. The cooled mixed feed stream 102 can be separated into the first vapor stream 104 and the first liquid stream 106 within a separator 300. The separator 300 may be any suitable separator.

[0016] As used in this disclosure, “separator” means any separation device or system of separation devices that separates one or more chemical substances mixed in a process stream at least partially from one another. For example, a separator may selectively separate different chemical species or phases from one another to form one or more chemical fractions. Examples of separators include, but are not limited to, distillation columns, flash drums, knockout drums, knockout pots, traps, scrubbers, expansion devices, membranes, and solvent extractors. It should be understood that the separation processes described in this disclosure do not necessarily have to completely separate all of one chemical component from all of another. It should be understood that the separation processes described in this disclosure separate different chemical components “at least partially” from one another, and that separation may include only partial separation, even if not expressly stated. As used in this disclosure, one or more chemical components may be “separated” from a process stream to form a new process stream. Generally, a process stream may enter a separator and be divided or separated into two or more process streams of a desired composition.

[0017] The first vapor flow 104 can be cooled to form a cooled flow 108. In some embodiments, the cooled flow 108 may be partially condensed, and in some embodiments, the cooled flow 108 may be completely condensed. The first vapor flow 104 can be cooled in one or more heat exchangers. In some embodiments, the first vapor flow 104 can be cooled in a heat exchanger located within a cold box 220. In one or more embodiments, the first vapor flow 104 can be cooled in a first heat exchanger 200.

[0018] In one or more embodiments, the cooled flow 108 may have a temperature of -150°C to 0°C. For example, the cooled flow 108 may have a temperature of -150°C to 0°C, -130°C to 0°C, -110°C to 0°C, -90°C to 0°C, -70°C to 0°C, -50°C to 0°C, -30°C to 0°C, -10°C to 0°C, -150°C to -20°C, -150°C to -40°C, -150°C to -60°C, -150°C to -80°C, -150°C to -100°C, -150°C to -120°C, -150°C to -140°C, or any range or combination of ranges formed from these endpoints.

[0019] Referring further to Figure 1, the cooled flow 108 may be separated into a second vapor flow 110 and a second liquid flow 112. The cooled flow 108 can be separated into a second vapor flow 110 and a second liquid flow 112 in a separator 302. The separator 302 may be any suitable separator. In one or more embodiments, the second liquid flow 112 may contain C2, C3, or C4 hydrocarbons or combinations thereof. In one or more embodiments, the second vapor flow 110 may contain at least 50% by weight of one or more of hydrogen, nitrogen, methane, carbon monoxide, and carbon dioxide. For example, the second vapor flow 110 may contain at least 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, or 85% by weight of one or more of hydrogen, nitrogen, methane, carbon monoxide, and carbon dioxide.

[0020] In one or more embodiments, the second liquid flow 112 may be sent to a fractional distillation system 304. The second liquid flow 112 may pass through one or more heat exchangers before being sent to the fractional distillation system 304. By passing the second liquid flow 112 through one or more heat exchangers, the second liquid flow 112 can be heated and the one or more heat exchangers can be provided with cooling. In some embodiments, the second liquid flow 112 can pass through the first heat exchanger 200 to provide cooling to the first heat exchanger 200. In some embodiments, the second liquid flow 112 can pass through the second heat exchanger 202 to provide cooling to the second heat exchanger 202. In some embodiments, as shown in Figure 1, a second portion of the second liquid flow 112 can pass through the first heat exchanger 200 and then through the second heat exchanger 202 to provide cooling to both the first heat exchanger 200 and the second heat exchanger 202 before being sent to the fractional distillation system 304.

[0021] As used in this disclosure, “fractional distillation system” means any fractional distillation device or system of fractional distillation devices that, during a phase transition, at least partially divide a given amount of mixture (gas, solid, liquid, or combination thereof) into several smaller fractions whose composition varies according to a gradient. In one or more embodiments, the fractional distillation system 304 may be a multi-stage fractional distillation system. In such embodiments, the fractional distillation system 304 may comprise a plurality of fractional distillation devices in series. For example, the fractional distillation system 304 may comprise a plurality of separators, and may include reflux or recirculation flow or a cooling step between the separators.

[0022] In one or more embodiments, the second liquid stream 112 may be separated into a light fraction 126, a recycle stream 128, and a heavy fraction 131. In one or more embodiments, the light fraction 126 may comprise C2 hydrocarbons. For example, the light fraction 126 may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, or even at least 90 wt% of C2 hydrocarbons. In one or more embodiments, the recycle stream 128 may comprise one or more of C2 and C3 hydrocarbons. For example, the recycle stream 128 may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, or even at least 90 wt% of one or more of C2 hydrocarbons and C3 hydrocarbons. In one or more embodiments, the heavy fraction 131 may comprise C 3+ hydrocarbons. For example, the heavy fraction 131 may comprise at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, or even at least 95 wt% of C 3+ hydrocarbons. In one or more embodiments, the heavy fraction 131 may be sent from the system to a C3 separation system.

[0023] In one or more embodiments, the light fraction 126 may be sent to a second heat exchanger 202 to provide cooling to the second heat exchanger 202. After providing cooling to the second heat exchanger 202, the light fraction 126 may exit the system. In some embodiments, as shown in FIG. 1, the pressure of the light fraction 126 may be reduced to cool the light fraction 126 and form a cooled light fraction 127. The pressure of the light fraction 126 may be reduced by passing the light fraction 126 through valve 504. In such embodiments, the cooled light fraction 127 may be sent to the second heat exchanger 202 to provide cooling to the second heat exchanger 202. The cooled light fraction 127 may be warmed in the second heat exchanger 202 and exit the system through stream 129.

[0024] In one or more embodiments, the first liquid stream 106 may also be sent to the fractional distillation system 304. In some embodiments, the first liquid stream 106 may be sent from the separator 300 to the fractional distillation system 304. In some embodiments, as shown in Figure 1, the first liquid stream 106 may be combined with a second liquid stream 112 upstream of the fractional distillation system 304 to form a fractional distillation feed stream 119. In embodiments in which the first liquid stream 106 is sent to the fractional distillation system 304, the first liquid stream 106 and the second liquid stream 112 may be separated into a light fraction 126, a recirculation stream 128, and a heavy fraction 131.

[0025] Referring further to Figure 1, the pressure of the recirculating flow 128 can be reduced to form the first coolant flow 130, causing the recirculating flow 128 to evaporate at least partially. In one or more embodiments, the pressure of the recirculating flow 128 can be reduced by passing the recirculating flow 128 through the valve 500.

[0026] In one or more embodiments, the recirculation stream 128 may have a pressure of 200 psig to 450 psig. For example, the recirculation stream 128 may have a pressure within 200 psig to 450 psig, 225 psig to 450 psig, 250 psig to 450 psig, 275 psig to 450 psig, 300 psig to 450 psig, 325 psig to 450 psig, 350 psig to 450 psig, 375 psig to 450 psig, 400 psig to 450 psig, 425 psig to 450 psig, 200 psig to 425 psig, 200 psig to 400 psig, 200 psig to 375 psig, 200 psig to 350 psig, 200 psig to 325 psig, 200 psig to 300 psig, 200 psig to 275 psig, 200 psig to 250 psig, 200 psig to 225 psig, or any range or combination of ranges formed from any of these endpoints. In one or more embodiments, the recirculation stream 128 may have a temperature of -120°C to 100°C. For example, the recirculation stream 128 may have a temperature within -120°C to 100°C, -100°C to 100°C, -80°C to 100°C, -60°C to 100°C, -40°C to 100°C, -20°C to 100°C, 0°C to 100°C, 20°C to 100°C, 40°C to 100°C, 60°C to 100°C, 80°C to 100°C, -120°C to 90°C, -120°C to 70°C, -120°C to 50°C, -120°C to 30°C, -120°C to 10°C, -120°C to -10°C, -120°C to -30°C, -120°C to -50°C, -120°C to -70°C, -120°C to -90°C, -120°C to -110°C, or any range or combination of ranges formed from any of these endpoints.

[0027] In one or more embodiments, the first coolant flow 130 may have a pressure of 5 psig to 200 psig. For example, the first coolant flow 130 may have a pressure of 5 psig to 200 psig, 5 psig to 200 psig, 25 psig to 200 psig, 50 psig to 200 psig, 75 psig to 200 psig, 100 psig to 200 psig, 125 psig to 200 psig, 150 psig to 200 psig, 175 psig to 200 psig, 5 psig to 175 psig, 5 psig to 150 psig, 5 psig to 125 psig, 5 psig to 100 psig, 5 psig to 75 psig, 5 psig to 50 psig, 5 psig to 25 psig, or any range or combination of ranges formed from these endpoints. In one or more embodiments, the first coolant flow 130 may have a temperature of -130°C to 0°C. For example, the first coolant flow 130 may have a temperature of -130°C to 0°C, -110°C to 0°C, -90°C to 0°C, -70°C to 0°C, -50°C to 0°C, -30°C to 0°C, -10°C to 0°C, -130°C to 20°C, -130°C to -40°C, -130°C to -60°C, -130°C to -80°C, -130°C to -100°C, -130°C to -120°C, or any range or combination of ranges formed from these endpoints.

[0028] Referring further to Figure 1, the first coolant flow 130 can pass through one or more heat exchangers to form a heated recirculating flow 136. In one or more embodiments, one or more of the heat exchangers may be located within the cold box 220. In one or more embodiments, at least a portion of the first coolant flow 130 may be vaporized within one or more heat exchangers. In one or more embodiments, at least 80% by weight of the heated recirculating flow 136 may be steam. For example, at least 80%, 85%, 90%, 95%, or even 99% by weight of the heated recirculating flow 136 may be steam. In some embodiments, the heated recirculating flow 136 may be completely vaporized.

[0029] In some embodiments, as shown in Figure 1, a first coolant flow 130 can pass through a first heat exchanger 200 to provide cooling within the first heat exchanger 200 and form a flow 134. The flow 134 can pass through a second heat exchanger 202 to provide cooling to the second heat exchanger and generate a heated recirculating flow 136.

[0030] Referring further to Figure 1, in one or more embodiments, a method for separating the mixed feed stream 100 may include passing the second steam stream 110 through one or more heat exchangers to provide cooling within one or more heat exchangers and generate a heated second steam stream 120. In some embodiments, one or more of the heat exchangers may be located within a cold box 220. In one or more embodiments, as shown in Figure 1, the second steam stream 110 may be sent from the separator 302 to the first heat exchanger 200 to provide cooling to the first heat exchanger 200 and generate a heated second steam stream 120.

[0031] In one or more embodiments, the pressure of the heated second vapor flow 120 can be reduced within the turbo expander 402 to form a second coolant flow 122. The turbo expander can extract work from the heated second vapor flow 120 when the pressure of the heated second vapor flow 120 is reduced. In the turbo expander, the temperature of the heated second vapor flow 120 can be reduced by reducing the pressure of the heated second vapor flow 120 and extracting work from the heated second vapor flow 120.

[0032] As described herein, a “turbo expander” can be a system component or a set of system components suitable for reducing the pressure of a process flow and extracting work from that process flow. In some embodiments, the turbo expander may be mechanically coupled to a turbo compressor, and the work extracted by the turbo expander may at least partially drive the turbo compressor. In some embodiments, the turbo expander may be mechanically coupled to a generator, and the work extracted by the turbo expander may be used for power generation.

[0033] As described herein, “work” refers to the energy transferred to or from an object by the application of a force along a displacement. For example, work can be extracted from a heated second steam flow 120 when it moves components of a turbo expander 402, such as rotating a turbine in the turbo expander 402. Power refers to the amount of work performed over a period of time. For example, the rate at which work is extracted from the heated second steam flow 120 can be expressed in terms of power.

[0034] In one or more embodiments, the second coolant flow 122 may pass through one or more heat exchangers to provide cooling within one or more heat exchangers. In some embodiments, one or more of the heat exchangers may be located within the cold box 220. In some embodiments, passing the second coolant flow 122 through one or more heat exchangers can generate an off-gas flow 125 that can exit the system. Referring further to Figure 1, in one or more embodiments, the second coolant flow 122 may pass through the first heat exchanger 200 to provide cooling to the first heat exchanger 200 and generate a flow 123. The flow 123 may pass through the second heat exchanger 202 to provide cooling to the second heat exchanger 202 and form an off-gas flow 125.

[0035] Referring further to Figure 1, the work extracted from the second steam flow 120 heated by the turbo expander 402 can be used to drive the turbo compressor 404. In one or more embodiments, the heated recirculating flow 136 can be compressed in the turbo compressor 404 to form a compressed recirculating flow 138. In one or more embodiments, the compressed recirculating flow 138 may be sent from the turbo compressor 404 to a downstream compressor 408. In such embodiments, the flow 101 and the compressed recirculating flow 138 can be compressed in the downstream compressor 408 to form a compressed mixed feed flow 103. In embodiments including multiple downstream compressors, the compressed recirculating flow 138 can be sent to any one of the downstream compressors, or even to two or more downstream compressors.

[0036] As described herein, a “turbo compressor” can be a system component or a set of system components suitable for increasing the pressure of a process flow. The turbo compressor may be mechanically coupled to a turbo expander. The work extracted by the turbo expander can be used to compress one or more process flows within the turbo compressor. In some embodiments, the turbo compressor can utilize other energy or work sources, such as energy or work from an electric motor, in addition to the work extracted by the turbo expander.

[0037] While not bound by theory, by using the work extracted from the heated second steam flow 120 in the turbo expander 402 to compress the heated recirculating flow 136, the size of the compressor used to compress the mixed feed flow 100 can be reduced compared to a system where the heated recirculating flow 136 is not compressed. By compressing the heated recirculating flow 136 in the turbo compressor 404, the pressure of the compressed recirculating flow 138 can be increased, and as a result, the compressed recirculating flow 138 can be sent to one or more downstream compressors, such as the downstream compressor 408. This allows the initial compressor 406 to be smaller and reduces the capital requirements for the compressor. In addition, compressing the heated recirculating flow 136 before sending its flow to the compressor may reduce the work required to compress the mixed feed flow 100 and the recirculating flow in the compressor compared to a system in which the heated recirculating flow 136 is not compressed in the turbo compressor 404, which is driven by work extracted from the heated second steam flow 120. Therefore, although not bound by theory, compressing the heated recirculating flow 136 before its flow is sent to the compressor using work extracted from the heated second steam flow 120 can reduce the capital cost of the compressor and reduce the work and energy required to compress the mixed feed flow and the recirculating flow in the compressor.

[0038] Referring here to Figure 2, in one or more embodiments, the work extracted from the second steam flow 120 heated by the turbo expander 402 may be used to drive the generator 410. In one or more embodiments, the generator 410 may generate electricity from the work extracted from the second steam flow 120 heated by the turbo expander. The electricity 140 may be sent from the generator 410 to the electric grid. The electricity 140 sent to the electric grid can be used by any process equipment that requires electricity and is connected to the electric grid. For example, but not limited to, at least a portion of the electricity 140 sent to the electric grid can be used to power the first compressor 406 and / or downstream compressors 408 together with any other process equipment connected to the electric grid.

[0039] While not bound by theory, generating electricity 140 using work extracted from the heated second steam flow 120 within the turbo expander 402 reduces the need for an external power source to supply power to any system component connected to the electric grid. This reduces the cost of supplying electricity to the system from an external power source.

[0040] Referring further to Figure 2, the heated recirculating flow 136 may be sent from the heat exchanger to the first compressor 406. In one or more embodiments, the heated recirculating flow 136 may be sent from the second heat exchanger 202 to the first compressor 406. The heated recirculating flow 136 and the mixed feed flow 100 can be compressed in the first compressor 406 to form flow 101, and flow 101 can be compressed in the downstream compressor 408 to form compressed mixed feed flow 103.

[0041] In some embodiments described herein, the first heat exchanger 200 and the second heat exchanger 202 may be located within a cold box 220, as shown in Figures 1 and 2. In one or more embodiments not shown, the first and second heat exchangers may be located within separate cold boxes, based on the cooling requirements of the system. [Examples]

[0042] Various embodiments of processes and systems for separating mixed feedstreams are further illustrated in the following examples. These embodiments are illustrative in nature and should not be understood as limiting the subject matter of this disclosure.

[0043] Example 1 Example 1 was carried out using the integrated separation train process model in Aspen Plus for the recovery system shown in Figure 1. Table 1 shows the temperature, pressure, and mass fraction ratio of the flows shown in Figure 1. The flow numbering in Table 1 corresponds to the flow numbering in Figure 1 and the numbering used throughout the detailed description.

[0044] [Table 1]

[0045] [Table 2]

[0046] As shown in Example 1, a turbo expander can be used to extract work from the heated second steam flow 120, reduce the pressure of the heated second steam flow 120, and cool the heated second steam flow 120. The work extracted from the heated second steam flow 120 can be used to drive the turbo compressor 404 to compress the heated recirculation flow 136, and thus the compressed recirculation flow 138 can be sent to the downstream compressor 408. Note that not all flows shown in Figure 1 and described above are listed in Table 1.

[0047] Example 2 Example 2 was carried out using the integrated separation train process model in Aspen Plus for the recovery system shown in Figure 2. Table 2 shows the temperature, pressure, and mass fraction ratio of the flows shown in Figure 2. The flow numbering in Table 2 corresponds to the flow numbering in Figure 2 and the numbering used throughout the detailed description.

[0048] [Table 3]

[0049] [Table 4]

[0050] As shown in Example 2, a turbo expander can be used to extract work from the heated second steam flow 120, reduce the pressure of the heated second steam flow 120, and cool the heated second steam flow 120. The work extracted from the heated second steam flow 120 can be used to drive the generator 410. According to this model, the generator 410 produced work at a rate of 920 hp. Note that not all flows shown in Figure 2 and described above are listed in Table 2.

[0051] Note that one or more of the following claims utilize the term “wherein” as a transitional clause. Note that, for the purpose of defining the art, this term is introduced into the claims as an unrestricted transitional clause used to introduce an enumeration of a set of structural features, and should be interpreted similarly to the more commonly used unrestricted preamble term “comprising.”

[0052] Where a first component is described as "comprising" a second component, it should be understood that in some embodiments, the first component is intended to "consist" or "consist essentially of" its second component. Additionally, the term "consist essentially of" is used in this disclosure to refer to a quantitative value that does not substantially affect the basic and novel features of this disclosure. For example, a chemical composition "consisting essentially of" a particular chemical component or group of chemical components should be understood to mean that the composition contains at least about 99.5% of that particular chemical component or group of chemical components.

[0053] Any two quantitative values ​​assigned to a characteristic may constitute a range for that characteristic, and it should be understood that all combinations of ranges formed from all described quantitative values ​​of a given characteristic are contemplated in this disclosure.

[0054] The subject matter of this disclosure is described in detail with reference to specific embodiments. Any detailed description of the components or features of the embodiments should be understood not to mean that such components or features are essential to the specific embodiment or any other embodiment. Furthermore, it will be apparent to those skilled in the art that various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

Claims

1. A method for separating mixed feed streams, In order to form a compressed supply flow, the mixed supply flow is C ２ , C ３ , and C ４ Compressing the mixed feed stream containing one or more hydrocarbons, To form a cooled mixed feed flow, the compressed mixed feed flow is cooled, The cooled mixed feed stream is separated into a first vapor stream and a first liquid stream, To form a cooled flow, the first vapor flow is cooled, The cooled flow is separated into a second vapor flow and a second liquid flow, To generate a heated second steam flow, the second steam flow is passed through one or more heat exchangers, To separate the second liquid flow in order to form at least a light fraction, a recirculating flow, and a heavy fraction, In order to form a first coolant flow, the pressure of the recirculating flow is reduced so that the recirculating flow is at least partially vaporized, To form a heated recirculating flow, the first coolant flow is passed through one or more heat exchangers, In a turbo expander, the pressure of the heated second vapor flow is reduced so that work is extracted from the heated second vapor flow to form a second coolant flow. To provide cooling in the one or more heat exchangers, the second coolant flow is passed through the one or more heat exchangers, A method comprising using the work from the turbo expander to drive a generator, drive a turbo compressor, or both.

2. The method according to claim 1, comprising using the work from the turbo expander to drive the turbo compressor.

3. The method according to claim 2, further comprising compressing the heated recirculation flow in the turbo compressor to form a compressed recirculation flow.

4. The method according to claim 3, wherein the mixed feed flow is compressed in at least the first compressor and one or more downstream compressors arranged in series, and the compressed recirculation flow is sent from the turbo compressor to one or more of the downstream compressors.

5. The method according to claim 1, comprising using the work from the turbo expander to drive the generator.

6. The method according to claim 5, wherein using the work from the turbo expander to drive the generator generates electricity, which is sent to the electric grid.

7. The method according to claim 6, wherein the compression of the mixed supply flow is performed in a first compressor and a second compressor arranged in series, and the heated recirculated flow is sent from one or more heat exchangers to the first compressor.

8. The aforementioned mixed feed stream contains at least 70% by weight of C ２ ~C ４ The method according to any one of claims 1 to 7, comprising a hydrocarbon.

9. The method according to any one of claims 1 to 8, wherein the second vapor stream contains at least 50% by weight of one or more of hydrogen, nitrogen, methane, carbon monoxide, and carbon dioxide.

10. The method according to any one of claims 1 to 9, further comprising passing the second liquid flow through one or more heat exchangers before separating the second liquid flow to form at least the light fraction, the recirculated flow, and the heavy fraction.

11. The method according to any one of claims 1 to 10, wherein one or more of the heat exchangers are placed inside a cold box.

12. The method according to any one of claims 1 to 10, wherein the first coolant flow passes through the first heat exchanger and the second heat exchanger to provide cooling to the first heat exchanger and the second heat exchanger.

13. The method according to claim 12, wherein the second coolant flow passes through the first heat exchanger and the second heat exchanger to provide cooling to the first heat exchanger and the second heat exchanger.

14. The method according to claim 12 or 13, wherein the cooling of the first vapor flow is performed in one or more heat exchangers.

15. The method according to any one of claims 11 to 14, wherein the second steam flow passes through the first heat exchanger to provide cooling to the first heat exchanger.

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