Process for recovering one or more C2, C3, or C4 olefins

Abstract

One or more C2, C3, or C4 olefins can be recovered by a process that may include: compressing and cooling a gaseous feedstream to generate a first compressed and cooled feedstream; further cooling the first compressed and cooled feedstream by heat exchange with a bottomstream to generate a second compressed and cooled feedstream; separating the second compressed and cooled feedstream into a first residual vapor stream and a first liquid residual stream; cooling the first residual vapor stream in a cold box to generate a cooled first residual stream; separating the cooled first residual stream into a second residual vapor stream and a second liquid residual stream; and passing at least a portion of the first liquid residual stream and at least a portion of the second liquid residual stream through a fractionation system to generate at least an overhead vapor stream, a liquid recirculation stream, and a bottomstream. The gaseous supply flow may contain a combination of C2, C3, and C4 components in an amount of at least 70% by weight, and the cooling of the gaseous supply flow may be by heat exchange with a cooling fluid having a temperature of 0°C to 70°C.

Description

Technical Field

[0001] (Cross-Reference to Related Application) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 583,444 filed on September 18, 2023, the entire content of which is incorporated herein by reference.

[0002] Embodiments described herein generally relate to chemical processing, and more specifically to product recovery in chemical processing. Background Art

[0003] Ethylene, ethane, propylene, propane, and / or heavier hydrocarbons can be recovered from various gas streams, including natural gas, refinery gas, syngas, or combinations thereof obtained from coal, crude oil, naphtha, oil shale, steam crackers, catalytic crackers, or combinations of the foregoing. Cryogenic expansion processes are widely used for recovering condensable product gases from non-condensable or difficult-to-condense gases because they provide easy start-up, operational flexibility, excellent efficiency and reliability. Summary of the Invention

[0004] Although conventional recovery processes are available for recovering ethylene, ethane, propylene, propane, and / or heavier hydrocarbons from various gas flows, these processes are often relatively inefficient and require high thermal load costs to cool the material to a condensable temperature. Therefore, there is a continuing need for processes that provide improved energy-efficient recovery of one or more of C2, C3, or C4 olefins. These needs can be met by embodiments of systems and processes described herein. Embodiments of this disclosure relate to processes for the recovery of one or more of C2, C3, or C4 olefins where the pressure in some flows is relatively high compared to conventional methods. In particular, the pressure of the feed flow after compression is relatively high, and the operating pressure of the fractionation system used to form a bottom flow that heat-exchanges with the feed flow is also relatively high. Such configurations can enable the recovery of condensable product gases from non-condensable or difficult-to-condense gases. As described herein, fractionation systems at high pressure generally allow for lower operating temperatures, and therefore, in some embodiments, allow for the use of crude propylene as a refrigerant to cool the warm decomposition gases. As a result, in one or more embodiments, the refrigeration requirements for the cold box are reduced, and better thermal integration is possible.

[0005] According to one or more embodiments disclosed herein, one or more C2, C3, or C4 olefins can be recovered by a process that may include: compressing and cooling a gaseous feedstream to generate a first compressed and cooled feedstream; further cooling the first compressed and cooled feedstream by heat exchange with a bottomstream to generate a second compressed and cooled feedstream; separating the second compressed and cooled feedstream into a first residual vapor stream and a first liquid residual stream; cooling the first residual vapor stream in a cold box to generate a cooled first residual stream; separating the cooled first residual stream into a second residual vapor stream and a second liquid residual stream; and passing at least a portion of the first liquid residual stream and at least a portion of the second liquid residual stream through a fractionation system to generate at least an overhead vapor stream, a liquid recirculation stream, and a bottomstream. The gaseous supply flow may contain at least 70% by weight of a combination of C2, C3, and C4 components, and the cooling of the gaseous supply flow may be by heat exchange with a cooling fluid having a temperature of 0°C to 70°C.

[0006] It should be understood that both the above summary and the following detailed description present embodiments of the technology and are intended to provide an overview or framework for understanding the nature and features of the claimed technology. The accompanying drawings are included to provide a further understanding of the technology and are incorporated herein and constitute part thereof. The drawings illustrate various embodiments and, together with the description, help to illustrate the principles and operation of the technology. In addition, the drawings and description are intended to be illustrative only and are not intended to limit the scope of the claims in any way.

[0007] 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]

[0008] 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] A schematic diagram illustrates a system for recovering one or more C2, C3, or C4 olefins according to one or more embodiments described herein. [Figure 2] A schematic diagram of a two-stage fractionation system that can be used in the embodiment of Figure 1, according to one or more embodiments described herein, is shown. [Figure 3] Another system for the recovery of one or more C2, C3, or C4 olefins, according to one or more embodiments described herein, is schematically shown.

[0009] It should be understood that the drawings are essentially schematic and do not, without limitation, include some components of fluid catalyst processing 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.

[0010] 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]

[0011] Embodiments of this disclosure relate to a process for recovering one or more C2, C3, or C4 olefins from a feed stream, the feed stream may be the product stream of an olefin-producing reactor system. Such a process utilizes a system having specific features, such as a particular orientation of system components. Figures 1 to 3 show such a system 100, including a cold box 111 and a fractionation system 120, as described herein.

[0012] Where used in this disclosure, “separator” or “separation device” 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, phases, or sized materials 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, centrifuges, cyclones, filters, 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. Where 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.

[0013] As used in this disclosure, “cold box” may refer to multiple heat exchangers connected in series or otherwise, and typically the cooling source cools multiple flows. 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.

[0014] As used in this disclosure, “fractionation system” may mean any fractionation device or system of fractionation devices that, during a phase transition, at least partially divide a given amount of a mixture (gas, solid, liquid, or combination thereof) into several smaller fractions whose composition varies according to a gradient.

[0015] It should be further understood that a flow may be named in terms of its components, and the components to which a flow is named may be the main components of the flow (for example, including 50% by weight (wt%) to 70%, 90%, 95%, 99%, 99.5%, or even 99.9% to 100% by weight of the flow contents). It should also be understood that when a flow containing those components is disclosed as passing from one system component to another, it is disclosed as passing from one system component to another.

[0016] Referring here to Figure 1, a system 100 for recovering one or more C2, C3, or C4 olefins from the product stream of an olefin generation reactor system is schematically shown. System 100 generally receives a gaseous feed stream 101, which may be the product stream from the olefin generation system, and processes the gaseous feed stream 101 directly to recover one or more C2, C3, or C4 olefins from the product stream of the olefin generation reactor system.

[0017] A gaseous feed stream 101 can be introduced into system 100. The gaseous feed stream may include, or consist of, the product stream of an olefin production reactor system. The product stream may be naphtha derived from a petrochemical process or from a refining operation of crude oil, natural gas liquids (NGL), or other hydrocarbon sources. As described herein, in one or more embodiments, the gaseous feed stream 101 may be the reaction effluent of steam cracking, catalytic cracking, or both. In one or more embodiments, the gaseous feed stream 101 may include natural gas, refinery gas, synthesis gas, or a combination thereof, derived from coal, crude oil, naphtha, oil shale, or a combination thereof. In various embodiments, the gaseous feed stream 101 may contain at least 70% by weight, at least 75% by weight, at least 80% by weight, or at least 85% by weight of one or more of the C2, C3, or C4 components. In some embodiments, the gaseous feed stream 101 contains 1% to 10% by weight of N2, 0.01% to 5% by weight of H2, 0.01% to 5% by weight of methane, and one or more of the C2, C3, or C4 components in 70% to 95% by weight. In some embodiments, the gaseous feed stream 101 contains ethane, propane, butane, or a combination thereof. In some embodiments, the gaseous feed stream 101 contains 50% by weight of propane.

[0018] A gaseous feed flow 101 can be introduced into a compressor 103. The gaseous feed flow 101 can be compressed in the compressor 103 to produce a compressed feed flow 102A. The compressed feed flow 102A may be introduced into a heat exchanger 127 and cooled by heat exchange with a cooling fluid 138 in the heat exchanger 127. The effluent from the heat exchanger 127 is called the first compressed and cooled feed flow 102B. The cooling fluid 138 can pass through the heat exchanger 127 and be heated to form a process fluid 139 having the same composition as the cooling fluid 138. The composition of the cooling fluid 138 is not necessarily limited and may be, for example, water, air, or a refrigerant. The cooling fluid 138 may have a temperature of 0°C to 70°C. For example, the cooling fluid 138 may have temperatures ranging from 0°C to 10°C, 10°C to 20°C, 20°C to 30°C, 30°C to 40°C, 40°C to 50°C, 50°C to 60°C, 60°C to 70°C, or any combination of one or more of these ranges.

[0019] In some embodiments, the amount of one or more of the C2, C3, or C4 components in the compressed feed stream 102A and / or the first compressed and cooled feed stream 102B may be greater than the amount of one or more of the C2, C3, or C4 components in the gaseous feed stream 101, by mixing with the recirculating flow 135 before or in the compressor 103, as will be described in more detail below.

[0020] According to various embodiments, the first compressed and cooled supply flow 102B may have a pressure of 15 barg to 100 barg. For example, the first compressed and cooled supply flow 102B may have a pressure of 15 barg to 20 barg, 20 barg to 25 barg, 25 barg to 30 barg, 30 barg to 40 barg, 40 barg to 50 barg, 50 barg to 75 barg, 75 barg to 100 barg, or any combination of these ranges. For example, the first compressed and cooled supply flow 102B may have a pressure of 15 barg to 35 barg. While not bound by theory, it is considered beneficial for the first compressed and cooled feed stream to have a relatively high pressure (e.g., 15 barg or higher) because such a relatively high pressure allows for a warmer fractionation column, according to one or more embodiments, and therefore allows for the utilization of the feed refrigerant in the fractionation condenser, thus eliminating the need for an external chiller. If the pressure is too low (e.g., less than 15 barg), external chilling may be required. If the pressure is too high (e.g., higher than 50 barg or 100 barg), additional capital and operating expenses may be incurred.

[0021] The first compressed and cooled feed flow 102B may be further cooled within the heat exchanger 129 to generate a second compressed and cooled feed flow 102C. In some embodiments, the first compressed and cooled feed flow 102B may be cooled within the heat exchanger 129 by the contents of the bottom flow 122A, as will be described in detail below.

[0022] Referring further to Figure 1, in one or more embodiments, a second compressed and cooled feed stream 102C may be introduced into a first separator 105. The compressed and cooled feed stream 102B can be separated into a first residual vapor stream 104A and a first liquid residual stream 106. In various embodiments, the first residual vapor stream 104A may contain 1% to 25% by weight of N2, 0.01% to 5% by weight of H2, 0.01% to 5% by weight of methane, and 70% to 95% by weight of one or more of the C2, C3, or C4 components. The amount of one or more of the C2, C3, or C4 components in the first residual vapor stream 104A may be greater than the amount of one or more of the C2, C3, or C4 components in the second compressed and cooled feed stream 102C.

[0023] The first residual vapor flow 104A can be introduced into a cold box 111. The first residual vapor flow 104A can be cooled in the cold box 111 to produce a cooled first residual vapor flow 104B. In some embodiments, the cooled first residual vapor flow 104B may contain 1% to 45% by weight of N2, 0.01% to 15% by weight of H2, 0.01% to 5% by weight of methane, and 50% to 95% by weight of one or more of the C2, C3, or C4 components.

[0024] The cooled first residual vapor stream 104B may be introduced into a second separator 109. The cooled first residual vapor stream 104B may be separated into a second residual vapor stream 108 and a second liquid residual stream 110A. In embodiments, the second residual vapor stream 108 comprises from 30 wt% to 80 wt% of N2, from 10 wt% to 40 wt% of H2, from 5 wt% to 20 wt% of methane, and from 0.01 wt% to 10 wt% of one or more of C2, C3, or C4 components. In embodiments, the second residual vapor stream 108 may have a temperature of from -120°C to -100°C. In embodiments, the second liquid residual stream 110A may comprise from 0.001 wt% to 2 wt% of N2, from 0.001 wt% to 1 wt% of H2, from 0.001 wt% to 2 wt% of methane, and from 90 wt% to 99 wt% of one or more of C2, C3, or C4 components. The second residual vapor stream 108 may be introduced into a cold box 111 and utilized as a coolant to form an off-gas via the product stream 112.

[0025] Still referring to FIG. 1, the second liquid residual stream 110A may be introduced into the cold box 111. The second liquid residual stream 110A may act as a coolant in the cold box 111 to produce a warmed second liquid residual stream 110B. In embodiments, the warmed second liquid residual stream 110B may comprise from 0.001 wt% to 5 wt% of N2, from 0.001 wt% to 1 wt% of H2, from 0.001 wt% to 1 wt% of methane, and from 90 wt% to 99 wt% of one or more of C2, C3, or C4 components.

[0026] At least a portion of the cooled second liquid residual stream 110B, at least a portion of the first liquid residual stream 106, or both may be introduced into a fractionation system 120 to produce at least an overhead vapor stream 128, a liquid recycle stream 130A, and a bottom stream 122A. Referring to Figures 1 and 2, one example of the fractionation system 120 is a two-stage fractionation system shown in Figure 2, which comprises a first fractionation device 121A and a second fractionation device 121B downstream of the first fractionation device 121A. The two-stage fractionation system can enable the use of cooling water for the compression operation of the first overhead stream 120A from the first fractionation device 121A. As a result of the removal of light and non-condensable components by the light removal column 117, the gaseous feed stream 101 can be compressed using cooling water and heat integration from the first overhead stream 120A. The use of cooling water can be beneficial to the use of a heat-blocking refrigerant process due to its excellent thermodynamic efficiency and low associated capital cost. Furthermore, the two-stage fractionation system can produce various streams that can be used as cooling media in a cold box. The two-stage fractionation system can provide flexibility in operation and product specification adjustment.

[0027] Referring further to Figures 1 and 2, in some embodiments, at least a portion of the cooled second liquid residual flow 110B may be introduced into the first fractionation device 121A depending on the composition of the stage. In some embodiments, at least a portion of the second liquid residual flow 110A can be cooled in a cold box 111 to produce cooled second liquid residual flow 110B. The cooled second liquid residual flow 110B may be introduced into the fractionation system 120. In some embodiments, the cooled second liquid residual flow 110B may be introduced into the first fractionation device 121A of the two-stage fractionation system. As described above, the first liquid residual flow 106 can be introduced into the first fractionation device 121A. At least a portion of the cooled second liquid residual flow 110B and the first liquid residual flow 106 can be separated into a first overhead flow 120A and a bottom flow 122A. In some embodiments, when a cooled second liquid residual flow 110B is supplied to the first fractionation device 121A, the cooled second liquid residual flow 110B and the first liquid residual flow 106 can be separated into a first overhead flow 120A and a bottom flow 122A.

[0028] In some embodiments, the first overhead flow 120A contains 0.001 to 1% by weight of N2, 0 to 1% by weight of H2, 0.001 to 1% by weight of methane, and one or more of the C2, C3, or C4 components in 98% to 99.9% by weight. The first overhead flow 120A does not have to contain H2. In some embodiments, the bottom flow 122A contains at least 95% by weight, at least 96% by weight, at least 97% by weight, at least 98% by weight, at least 99% by weight, or at least 99.9% by weight of one or more of the C2, C3, or C4 components. The bottom flow 122A does not have to contain N2, H2, methane, or any combination thereof.

[0029] The first overhead flow 120A can be partially condensed and refluxed. The temperature of the first overhead flow 120A can be controlled to allow the use of cooling water as a condensant for the gaseous feed 100. In some embodiments, the first overhead flow 120A can be cooled by a heat exchanger 131 to produce a cooled first overhead flow 120B. In some embodiments, the heat exchanger 131 can use cooling water as a cooling medium. The heat exchanger 131 may not require an external refrigeration system. The cooled first overhead flow 120B can be introduced into a third separator 125. The cooled first overhead flow 120B can be separated into a first vapor flow 123A and a first liquid flow 123B. The first liquid flow 123B can be reintroduced into a first fractionator 121A.

[0030] Referring further to Figures 1 and 2, at least a portion of the first overhead flow 120A may be introduced into a second fractionator 121B downstream of the first fractionator 121A, and then separated into a second overhead flow 126A and a second bottom flow 124. In some embodiments, the first vapor flow 123A containing non-condensable components may be introduced into the second fractionator 121B. The first vapor flow 123A may be separated into a second overhead flow 126A and a second bottom flow 124. In some embodiments, the second bottom flow 124 may contain at least 95% by weight, at least 96% by weight, at least 97% by weight, at least 98% by weight, or at least 99% by weight of one or more of the C2, C3, or C4 components. The second bottom flow 124 may further contain 0% to 1% by weight of H2, 0% to 1% by weight of N2, and 0.001% to 1% by weight of methane. The second bottom flow 124 may not contain H2, N2, or both. The second bottom flow 124 can be reintroduced into the first fractionation apparatus 121A.

[0031] The second overhead flow 126A can be partially condensed and refluxed. The temperature of the second overhead flow 126A can be controlled using the alkane feed flow 136 to meet desired specifications for total product losses. In some embodiments, the second overhead flow 126A can be cooled by a heat exchanger 133 to produce a cooled second overhead flow 126B. In some embodiments, the second overhead flow 126A can be cooled in the heat exchanger 133 with a flushed alkane feed flow 138. In some embodiments, the heat exchanger 133 may be used as a branch of the flushed alkane feed flow 138 as a refrigerant (cooling medium), thereby eliminating the need for an external refrigeration system.

[0032] The cooled second overhead flow 126B is introduced into a fourth separator 127, where it can then be separated into an overhead vapor flow 128 and an overhead liquid flow 132. In some embodiments, the overhead vapor flow 128 may contain 1% to 10% by weight of N2, 0.001% to 1% by weight of H2, 1% to 10% by weight of methane, and 75% to 95% by weight of one or more of the C2, C3, or C4 components.

[0033] The overhead vapor flow 128 can be introduced into the cold box 111. The overhead vapor flow 128 can be cooled within the cold box 111 to produce a byproduct 128A. In some embodiments, the overhead vapor flow 128 can be used as a cooling medium within the cold box 111 before it leaves the system 100 as a byproduct.

[0034] The overhead liquid flow 132 can be divided into a liquid recirculation flow 130A and a liquid reflux return flow 130B. The liquid recirculation flow 130A can be introduced into the cold box 111. The liquid recirculation flow 130A can be used as a cooling medium within the cold box. The liquid reflux return flow 130B can be introduced into a second fractionation device 121B.

[0035] In some embodiments, the liquid recirculation flow 130A may contain 0.001% to 1% by weight of N2, 0% to 1% by weight of H2, 0.001% to 1% by weight of methane, and 90% to 99% by weight of one or more of the C2, C3, or C4 components. In some embodiments, the liquid recirculation flow 130A may not contain H2. The liquid recirculation flow 135 may pass through a valve to release pressure and form a liquid recirculation flow 130B. Referring further to Figures 1 and 2, at least a portion of the liquid recirculation flow 130B may pass through a cold box 111 to form a cooled liquid recirculation flow 135. The cooled liquid recirculation flow 130B can be combined with a gaseous supply flow 101 upstream of the compressor 103 or in the compressor 103.

[0036] The second bottom flow 124 can be reintroduced into the first fractionation device 121A. Before being reintroduced into the first fractionation device 121A, the second bottom flow 126 can be mixed with the first liquid flow 123B.

[0037] According to various embodiments, the fractionation system 120 may operate at pressures ranging from 15 barg to 100 barg. For example, the fractionation system 120 may operate at pressures ranging from 15 barg to 20 barg, 20 barg to 25 barg, 25 barg to 30 barg, 30 barg to 40 barg, 40 barg to 50 barg, 50 barg to 75 barg, 75 barg to 100 barg, or any combination of these ranges. For example, the fractionation system 120 may operate at pressures ranging from 15 barg to 35 barg. In such embodiments, one, two, or all three of the overhead vapor flow 128, the liquid recirculation flow 130A, and the bottom flow 122A may have pressures ranging from 15 barg to 100 barg, or any sub-range pressures as described herein. While not bound by theory, it is considered beneficial to operate the fractionation system 120 at relatively high pressures (e.g., 15 barg or higher) because such relatively high pressures, according to one or more embodiments, allow for a warmer fractionation column, thus enabling the use of the supply refrigerant in the fractionation condenser and thus eliminating the need for an external chiller. If the pressure is too low (e.g., below 15 barg), an external chiller may be required. If the pressure is too high (e.g., above 50 barg or 100 barg), additional capital and operating expenses may be incurred.

[0038] Referring here to Figure 1, the bottom flow 122A may undergo some treatment before being used as a heat exchange fluid with the first compressed and cooled feed flow 102B in the heat exchanger 129. The “bottom flow” is described by reference numbers 122A, 122B (Figure 2 only), 122C, and 122D, and it should be understood that all of these flows generally have the same composition but may have different temperatures and / or pressures.

[0039] In one or more embodiments, the pressure of the bottom flow 122A can be reduced upstream of the heat exchange with the first compressed and cooled supply flow 102B. As shown in Figure 1, the pressure of the bottom flow 122A can be reduced using a pressure relief mechanism 137, such as a valve or flush vessel, so that the bottom flow 122A has a higher pressure than the bottom flow 122C (downstream of the pressure relief mechanism 137). In such embodiments, reducing the pressure of the bottom flow can at least partially evaporate the bottom flow 102A so that the bottom flow 102A contains both liquid-phase and gaseous-phase materials. According to some embodiments, the bottom flow 122C is 10% to 99.9% by weight, 10% to 99% by weight, 10% to 95% by weight, 10% to 90% by weight, 10% to 85% by weight, 10% to 80% by weight, 15% to 99.9% by weight, 15% to 99% by weight, 15% to 95% by weight, 15% to 90% by weight, 15% to 85% by weight, and 15% to 80% by weight. Percentages of weight, 20% to 99.9% by weight, 20% to 99% by weight, 20% to 95% by weight, 20% to 90% by weight, 20% to 85% by weight, 20% to 80% by weight, 25% to 99.9% by weight, 25% to 99% by weight, 25% to 95% by weight, 25% to 90% by weight, 25% to 85% by weight, or 25% to 80% by weight may evaporate.

[0040] According to various embodiments, the bottom flow 122C exchanges heat with the first compressed and cooled supply flow 102B, thereby cooling the first compressed and cooled supply flow 102B and heating the bottom flow 122C to form the bottom flow 122D (downstream of the heat exchanger 129). The bottom flow 122D can be separated into at least two flows (not shown in Figure 1).

[0041] Referring now to Figure 3, a system is shown that is in all respects nearly identical to the system in Figure 1, the difference being the inclusion of an additional heat exchange step used with bottom flow 122A to form bottom flow 122B (which is colder than bottom flow 122A). As shown, bottom flow 122A can pass through heat exchanger 146, where bottom flow 122A exchanges heat with process flow 142 to form bottom flow 122B (which is colder than bottom flow 122A) and process flow 144 (which is hotter than process flow 142). Such heat exchange by process flow 142 may be upstream of the pressure drop in pressure release mechanism 137.

[0042] According to one or more embodiments, the process flow 142 may be an alkane feed stream supplied to an olefin production process, the olefin production process forming a gaseous feed stream as its product stream. For example, the process flow 142 may be sent to the olefin production process, for example, directly to a reactor, or through one or more process units such as a separator or heat exchanger before being sent to the reactor. Such an alkane production process may utilize catalytic or non-contact cracking and / or dehydrogenation reactions. For example, the process flow 142 may include natural gas or other alkane-rich streams. In some embodiments, the process flow 142 may include one or more recycled components from the olefin production process, as well as pure feed material such as natural gas.

[0043] According to various embodiments, heat exchange between the process flow 142 and the bottom flow 122A can cause the process flow 142 to evaporate at least partially to form the process flow 144. While not bound by theory, according to one or more embodiments, the partial evaporation of the process flow 142 may be beneficial by removing heat from the process flow 142, enabling enhanced cooling to the first compressed and cooled feed flow 102B, and / or by reducing energy use in downstream separations such as depropane towers.

[0044] According to various embodiments, the cooling of the cold box 111 may be provided by a power grid from within or outside the region. Alternatively, the cooling of the cold box 111 may be provided by a cooling medium such as natural gas. In some embodiments, natural gas can be used as a raw material for olefin production and can also be used to cool the products of this process while being heated, which is necessary for the relatively high reaction temperatures generally required to produce olefins.

[0045] A process for recovering one or more C2, C3, C4 olefins, or combinations thereof, from the product stream of an olefin-producing reactor system according to the present disclosure can produce a higher yield of one or more C2, C3, or C4 olefins compared to conventional recovery processes. In some embodiments, the process according to the present disclosure can produce a total yield of 90% or more by weight, 95% or more by weight, 96% or more by weight, 97% or more by weight, 98% or more by weight, or even 99% or more by weight of C2, C3, C4 olefins, or combinations thereof, based on the total weight of the product stream introduced into the recovery process according to the present disclosure. [Examples]

[0046] Various embodiments of the processes and systems disclosed herein are further clarified by the following examples. These examples should be understood to be illustrative in nature and not limiting the subject matter of this application.

[0047] 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. Tables 1A to 1D show the temperature, pressure, and mass fraction ratio of the flow shown in Figure 1.

[0048] [Table 1]

[0049] [Table 2]

[0050] [Table 3]

[0051] [Table 4]

[0052] Example 2 Example 1 was carried out using the integrated separation train process model in Aspen Plus for the recovery system shown in Figure 1. Tables 2A to 2D show the temperature, pressure, and mass fraction ratio of the flow shown in Figure 1.

[0053] [Table 5]

[0054] [Table 6]

[0055] [Table 7]

[0056] Several embodiments are disclosed herein. A first embodiment is a process for recovering one or more C2, C3, or C4 olefins, the process comprising compressing and cooling a gaseous feed stream to produce a first compressed and cooled feed stream, the gaseous feed stream comprising a combination of at least 70% by weight of C2, C3, and C4 components, the cooling of the gaseous feed stream being by heat exchange with a cooling fluid having a temperature of 0°C to 70°C, and further cooling the first compressed and cooled feed stream by heat exchange with a bottom stream to produce a second compressed and cooled The process includes generating a supply flow, separating a second compressed and cooled supply flow into a first residual vapor flow and a first liquid residual flow, cooling the first residual vapor flow in a cold box to generate a cooled first residual flow, separating the cooled first residual flow into a second residual vapor flow and a second liquid residual flow, and sending at least a portion of the first liquid residual flow and at least a portion of the second liquid residual flow to a fractionation system to generate at least an overhead vapor flow, a liquid recirculation flow, and a bottom flow.

[0057] Another embodiment is any of the above embodiments or a combination thereof, further comprising reducing the pressure of the bottom flow upstream of the heat exchange with the first compressed and cooled feed flow.

[0058] Another embodiment is any of the above embodiments or a combination thereof, which reduces the pressure of the bottom flow, thereby causing the bottom flow to evaporate at least partially.

[0059] Another embodiment is any of the aforementioned embodiments or a combination thereof, further comprising heat exchange of the bottom flow with the process flow.

[0060] Another embodiment is any of the aforementioned embodiments or a combination thereof, wherein heat exchange with the process flow takes place upstream of reducing the pressure of the bottom flow.

[0061] Another embodiment is any of the above embodiments or a combination thereof, wherein the process flow is an alkane feed flow supplied to an olefin generation process that forms a gaseous feed flow.

[0062] Another embodiment is any of the aforementioned embodiments or a combination thereof, wherein the process flow is at least partially evaporated by heat exchange with the bottom flow.

[0063] Another embodiment is any of the aforementioned embodiments or a combination thereof, wherein the first compressed and cooled supply flow has a pressure of 15 barg to 100 barg.

[0064] Another embodiment is any of the aforementioned embodiments or a combination thereof, in which the fractionation system operates at pressures of 15 barg to 100 barg.

[0065] Another embodiment is any of the above embodiments or a combination thereof, further comprising separating the bottom flow into at least two flows downstream of the heat exchange with the first compressed and cooled supply flow.

[0066] Another embodiment is any of the aforementioned embodiments or a combination of the aforementioned embodiments, wherein the fractionation system includes a two-stage fractionation system.

[0067] Another embodiment is any of the above embodiments or a combination thereof, further comprising passing at least a portion of the second residual vapor flow and at least a portion of the second residual liquid flow through a cold box as a coolant.

[0068] Another embodiment is any of the aforementioned embodiments or a combination thereof, further comprising passing an overhead vapor flow through a cold box.

[0069] Another embodiment is any of the aforementioned embodiments or a combination thereof, further comprising passing the liquid recirculation flow through a cold box.

[0070] Another embodiment is any of the above embodiments or a combination thereof, further comprising combining a liquid recirculation flow with a gaseous supply flow.

[0071] 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.

[0072] 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.” 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.

[0073] 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.

Claims

1. C ２ , C ３ , or C ４ A process for recovering one or more olefins, Compressing and cooling a gaseous supply flow to generate a first compressed and cooled supply flow, wherein the gaseous supply flow contains at least 70% by weight of C ２ , C ３ , and C ４ The combination of components is such that the cooling of the gaseous supply flow occurs through heat exchange with a cooling fluid having a temperature of 0°C to 70°C, The first compressed and cooled supply flow is further cooled by heat exchange with the bottom flow to generate a second compressed and cooled supply flow. The second compressed and cooled supply flow is separated into a first residual vapor flow and a first residual liquid flow, The first residual vapor flow is cooled in a cold box to generate a cooled first residual flow, The cooled first residual flow is separated into a second residual vapor flow and a second liquid residual flow, A process comprising sending at least a portion of the first liquid residual flow and at least a portion of the second liquid residual flow to a fractionation system to generate at least an overhead vapor flow, a liquid recirculation flow, and a bottom flow.

2. The process according to claim 1, further comprising reducing the pressure of the bottom flow upstream of the heat exchange with the first compressed and cooled supply flow.

3. The process according to claim 2, wherein reducing the pressure of the bottom flow causes the bottom flow to evaporate at least partially.

4. The process according to any one of claims 1 to 3, further comprising heat exchange of the bottom flow with the process flow.

5. The process according to claim 4, wherein the heat exchange with the process flow takes place upstream of reducing the pressure of the bottom flow.

6. The process according to claim 4, wherein the process flow is an alkane supply flow supplied to an olefin production process that forms the gaseous supply flow.

7. The process according to claim 6, wherein the heat exchange between the process flow and the bottom flow causes at least a partial evaporation of the process flow.

8. The process according to any one of claims 1 to 7, wherein the first compressed and cooled supply flow has a pressure of 15 barg to 100 barg.

9. The process according to any one of claims 1 to 8, wherein the fractionation system operates at a pressure of 15 barg to 100 barg.

10. The process according to any one of claims 1 to 9, further comprising separating the bottom flow into at least two flows downstream of the heat exchange with the first compressed and cooled supply flow.

11. The process according to any one of claims 1 to 10, wherein the fractionation system includes a two-stage fractionation system.

12. The process according to any one of claims 1 to 11, further comprising passing at least a portion of the second residual vapor flow and at least a portion of the second residual liquid flow through the cold box as a coolant.

13. The process according to any one of claims 1 to 12, further comprising passing the overhead steam flow through the cold box.

14. The process according to any one of claims 1 to 13, further comprising passing the liquid recirculation flow through the cold box.

15. The process according to any one of claims 1 to 14, further comprising combining the liquid recirculation flow with the gaseous supply flow.

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