Coil heat exchanger with reduced pressure drop

Abstract

A method and system is disclosed for cooling a reactor effluent stream, such as from a propane dehydrogenation process, with a coiled heat exchanger that provides a reduced effluent stream pressure drop and simplified construction by enabling a single multipurpose heat exchanger to provide the necessary cooling load. The effluent stream is provided at a relatively low pressure, which, in most cases, is close to or below ambient pressure. In some embodiments, the coiled heat exchanger provides a shell-side flow path for the effluent stream without substantial changes in the overall flow direction. The functionality of the steam generator and cooler is also provided in additional bundles within the coil heat exchanger, which further reduces the pressure drop.

Description

Technical Field

[0001] The present application relates to a feed-effluent heat exchanger for warming a feed and cooling the effluent of a hydrocarbon reaction conducted at low pressure. Background Art

[0002] The present disclosure relates generally to heat transfer in oil refining and petrochemical processes. The exemplary embodiments disclosed herein are particularly advantageous when applied to a dehydrogenation process in which one of two or more bundles warms a tube-side reactor feed stream while cooling a shell-side reactor effluent stream, wherein a second bundle further cools the reactor effluent via a tube-side aqueous coolant stream. The following description will focus on a propane dehydrogenation ("PDH") process as a non-limiting example.

[0003] A prior art PDH system 100 is shown in FIG1 . Propane dehydrogenation is an endothermic chemical reaction that converts propane into propylene and hydrogen. A feed gas stream 103 containing propane is warmed in a feed-effluent heat exchanger 102 to produce a first warmed propane stream 126. The first warmed propane stream 126 is then further warmed in a feed heater 104 using a fuel or electricity to produce a second warmed propane stream 105. The second warmed propane stream 105 is then sent to a reactor 106 where the propane is reacted to form an effluent stream 107 consisting primarily of propylene, hydrogen, and unreacted propane. The effluent stream 107 is removed from the reactor 106 and is then cooled by a first water cooling stream 109 in a heat exchanger 108 that generates steam to produce stream 119 and a first cooled effluent stream 132. The first cooled effluent stream 132 is then further cooled by the feed gas 103 (as described above) in the feed-effluent heat exchanger 102 to produce a second cooled effluent stream 136. The second cooled effluent stream 136 is then further cooled by the second water cooling stream 128 in the water cooler 110 to produce a third cooled effluent stream 134 and a warmed cooling water stream 130. The third cooled effluent stream 134 is compressed in the compressor 112 to produce a compressed effluent stream 117.

[0004] It should be noted that for each of the steam generator 108, the feed-effluent heat exchanger 102 and the water cooler 110, only one heat exchanger is shown. In most commercial-scale plants using conventional shell-and-tube heat exchanger technology, multiple heat exchangers must be provided in parallel to meet the required heating and cooling loads. For example, in a typical PDH plant producing 100 tons / hour of propylene, the water cooler 110 will require four shell-and-tube exchangers operating in parallel. An example of a shell-and-tube heat exchanger can be found in US10527357, entitled "Feed Effluent Heat Exchanger".

[0005] The compressed effluent stream 117 is sent to the separation section 114. The separation section 114 may include a distillation column, a phase separator, and / or an adsorption-based separator to produce a fuel stream 116, a product hydrogen stream 118, a product propylene stream 120, and a recycle stream 122 containing unreacted propane. The recycle stream may be combined with a fresh feed stream 124 to form a feed stream 103.

[0006] When carried out under relatively low absolute pressure (generally in the range of 0.2bara to 3.0bara), petrochemical and thermal cracking processes (including PDH processes) produce better product yields. The PDH reaction is preferably carried out under vacuum (generally between 0.2bara to 1.0bara, preferably less than 0.4bara). Due to low operating pressure, it is important to minimize the pressure drop between reactor 106 and compressor 112. The lower pressure on the suction side of compressor 112 causes the larger power demand (and therefore the increased cost) of the third cooled effluent stream 134 to be fully compressed. When effluent stream 132 passes through multiple heat exchangers (parallel and series), other components and connecting pipes, it is particularly difficult to keep the pressure drop within the desired limit. Therefore, the stream is separated, distributed to each cooler, and then redistributed to the next heat exchange section after being recombined and collected. Multiple changes in flow direction cause high pressure drop, and potential maldistribution between individual units or in individual flow channels or layers.

[0007] For large plants, in addition to the challenge of preventing pressure drops in the effluent loop, there are other operational challenges such as the need to balance effluent and water flows through multiple parallel chillers.Parallel cooling units also increase manufacturing costs associated with fittings, structural supports and piping.

[0008]

[0006] Thus, there is an unmet need for improved methods and systems for effluent cooling that allow for reduced pressure drop, are cost effective, efficient, and simple to design and operate. Summary of the invention

[0009] In embodiments described herein, a coil heat exchanger of unique construction is used as a feed-effluent heat exchanger to provide a reduced effluent stream pressure drop and simplify the construction. In some embodiments, the functionality of steam generator 108 and water cooler 110 is also provided in a single coil heat exchanger with an additional bundle, which further reduces the pressure drop. The reduction in pressure drop allows a reduction in compressor power demand, and enables the reactor to operate at a lower pressure, thereby improving reactor output. In addition, by eliminating the need to balance effluent and water flow between a plurality of heat exchangers operating in parallel, the plant layout can be simplified, construction costs can be reduced, and plant operations can be simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a schematic diagram of a prior art PDH process.

[0011] Figure 2 is a schematic diagram of a PDH process according to a first exemplary embodiment.

[0012] Figure 2A is a longitudinal cross-sectional view of a coil heat exchanger according to a first exemplary embodiment.

[0013] Figure 2B It is along Figure 2A A cross-sectional view taken along line 2B-2B.

[0014] Figure 2C yes Figure 2A A longitudinal cross-sectional view of an alternative configuration of a coil-type heat exchanger.

[0015] Figure 3 yes Figure 2A A partial view of region 3-3 of FIG. 1 shows an alternative embodiment of the outlet end of the CWHE. For simplicity, Figure 3 Not shown Figure 2A The tube sheet and tubes are shown in the area 3-3.

[0016] Figure 4 It is shown Figure 2A and Figure 2C Schematic cross-sectional view of a representative arrangement of tubes and spacers within a coil-type heat exchanger.

[0017] Figure 5 is a schematic diagram of a PDH process according to a second exemplary embodiment.

[0018] Figure 6 is a schematic diagram of a PDH process according to a third exemplary embodiment.

[0019] Fig. 6A is based on Figure 6 A longitudinal cross-sectional view of a coil heat exchanger of an embodiment of the present invention.

[0020] Figure 7 is a schematic diagram of a PDH process according to a fourth exemplary embodiment. DETAILED DESCRIPTION

[0021] The detailed description that follows only provides preferred exemplary embodiments and is not intended to limit the scope, applicability or configuration of the present invention. On the contrary, the detailed description that follows of the preferred exemplary embodiments will provide those skilled in the art with an enabling description for implementing the preferred exemplary embodiments of the present invention. It should be understood that various changes may be made to the functions and arrangements of the elements without departing from the spirit and scope of the present invention.

[0022] In the claims, letters are used to identify claimed steps (e.g., (a), (b), and (c). These letters are used to aid in referencing method steps and are not intended to indicate the order in which the claimed steps may be performed, unless and only to the extent such an order is specifically recited in the claims.

[0023] To help describe the invention, directional terms may be used in the specification and claims to describe parts of the invention (e.g., top, bottom, left, right, etc.). These directional terms are intended only to help describe and claim the invention and are not intended to limit the invention in any way. In addition, reference numerals associated with a drawing introduced in the specification may be repeated in one or more subsequent drawings without additional description in the specification to provide context for other features.

[0024] Unless otherwise indicated, the articles "a / an" as used herein mean one or more when applied to any feature of the embodiments of the present invention described in the specification and claims. The use of "a / an" does not limit the meaning to a single feature unless such limitation is specifically stated. The article "the / said" preceding a singular or plural noun or noun phrase means one or more specific specified features and can have a singular or plural meaning depending on the context in which it is used.

[0025] Unless otherwise specified herein, the introduction of a flow at a location is intended to mean the introduction of substantially all flows at that location. All flows discussed in the specification and shown in the drawings (generally represented by lines with arrows, showing the general direction of fluid flow during normal operation) should be understood to be contained in corresponding conduits. Each conduit should be understood to have at least one inlet and at least one outlet. Further, each device should be understood to have at least one inlet and at least one outlet.

[0026] The term "conduit" as used in the specification and claims refers to one or more structures through which a fluid can be transported between two or more components of a system. For example, a conduit can include pipes, tubes, channels, and combinations thereof that transport liquids, vapors, and / or gases.

[0027] As used in the specification and claims, the term "flow communication" is intended to mean the connection (directly or indirectly) of two or more elements in a manner that enables fluid to flow between the elements, including connections that may include valves, gates, tees, or other devices that selectively restrict, combine, or separate fluid flow.

[0028] As used in the specification and claims, the term "hydrocarbon", "hydrocarbon gas" or "hydrocarbon fluid" refers to a gas / fluid comprising at least one hydrocarbon and hydrocarbons accounting for at least 70% and more preferably at least 90% of the total composition of the gas / fluid.

[0029] As used in the specification and claims, the term "substantial change in overall flow direction" means that there are no elbows or substantial bends in the conduit containing the fluid in question. For the purpose of this definition, bends exceeding 10 degrees will be considered substantial. Structures such as cleaning devices, nozzle protrusions, fluid distribution devices, tube bundles, spacers, or mandrels located within the conduit may cause small local changes in flow direction, but are not considered to substantially change the overall flow direction, as the term is defined in this article. Similarly, expansion or contraction of the conduit is not considered to significantly change the overall flow direction, as the term is defined in this article.

[0030] For the purposes of this application, the term "in steady state operation within design operating conditions" means that the heat exchanger is in steady state operation within the design parameters of the heat exchanger and does not include startup operation, shutdown operation, or the situation where a cleaning process (online or offline) is being performed. Exemplary descriptions of startup and shutdown operations can be found in the "Standards of the Tubular Exchanger Manufacturers Association, Tenth Edition".

[0031] Unless otherwise indicated herein, any and all percentages identified in the specification, drawings, and claims should be understood to be on a mole percentage basis. Unless otherwise indicated herein, any and all pressures identified in the specification, drawings, and claims should be understood to mean gauge pressures.

[0032] As used in the specification and claims, the term "compressor" or "compression system" is defined as one or more compression stages. For example, a compression system may include multiple compression stages within a single compressor. In an alternative example, a compression system may include multiple compressors that may be arranged in series and / or in parallel.

[0033] Figure 2 FIG. 1 shows an exemplary embodiment of an improved PDH system 200. Figure 2 The components in Figure 2 1, but may not be discussed separately in the specification. For example, reactor 106 of FIG. 1 corresponds to Figure 2 The reactor 206 is provided.

[0034] In this embodiment, a single coil heat exchanger ("CWHE") 202 is used in place of the multiple feed-effluent heat exchangers 102 operated in parallel in FIG. 1. Feed stream 203 is warmed in feed bundle 211 of CWHE 202 to produce a first warmed propane stream 226. As in the prior art, first warmed propane stream 226 is then further warmed in feed heater 204 to produce a second warmed propane stream 205. This second warmed propane stream 205 is then sent to reactor 206. Effluent stream 207 is withdrawn from reactor 206 and cooled in heat exchanger 208 that generates steam to produce stream 219 and a first cooled effluent stream 232. Optionally, effluent stream 207 may bypass heat exchanger 208 that generates steam via bypass 213.

[0035] The first cooled effluent stream 232 is further cooled in the shell side of the CWHE 202, thereby warming the incoming feed stream 203 to produce a second cooled effluent stream 236. In this embodiment, the second cooled effluent stream 236 is further cooled by the first coolant stream 228 flowing through the first coolant bundle 210 of the CWHE 202 (rather than being cooled in a separate cooler) to produce a third cooled effluent stream 234. The third cooled effluent stream 234 is compressed in the compressor 212 to produce a compressed effluent stream 217.

[0036] The compressed effluent stream 217 is sent to the separation section 214. The separation section 214 may include a distillation column, a phase separator, and / or an adsorption-based separator to produce a fuel stream 216, a product hydrogen stream 218, a product propylene stream 220, and a recycle stream 222 containing unreacted propane that is combined with a fresh feed stream 224 to form the feed stream 203.

[0037] Figure 2A and Figure 2B Shown in Figure 2 2. The CWHE 202 includes a shell 201 having an inlet end 254 and an outlet end 256, a body 258 extending between the inlet end 254 and the outlet end 256, and a longitudinal axis L extending parallel to the major dimension of the shell. In this embodiment, the body 258 is cylindrical in shape, which means that it has a constant shell diameter Ds. In other embodiments, the body 258 can have sections with different diameters. For the purposes of this application, the term shell diameter Ds refers to the maximum diameter of the body 258. The longitudinal axis L bisects the shell diameter Ds along its length.

[0038] The CWHE 202 also includes a feed bundle 211 and a first coolant bundle 210, each of which includes a bundle of one or more tubes (also referred to herein as a tube bundle) wrapped in concentric layers around a central mandrel 264, 266. A shroud 275, 276 can surround each tube bundle, and each shroud 275, 276 can include an upper lip 277, 278 extending outwardly to the shell 201, thereby reducing the ability of the first cooled effluent stream 232 to bypass the tube bundle in the space between the shell 201 and the tube bundle. In addition, each mandrel 264, 266 can optionally include a flow divider 279, 280 that directs the shell-side flow around the mandrel 264, 266, thereby preventing the ability of the first cooled effluent stream 232 to bypass the tube bundle in the interior space of the mandrel 264, 266. In some embodiments, the flow dividers 279, 280 can be shaped to minimize flow resistance. In this embodiment, the flow dividers 279, 280 are both dome-shaped. Other shapes, such as conical, may also be used.

[0039] The inlet end 254 has an inlet port 260 having an inlet diameter Di, and the outlet end 256 has an outlet port 262 having an outlet diameter Do. In some embodiments, both the inlet diameter Di and the outlet diameter Do are at least 0.35 times the shell diameter Ds. In this embodiment, the inlet port diameter Di and the outlet port diameter Do are unusually large relative to the shell diameter Ds in order to reduce the pressure drop of the effluent stream 232 as it flows through the CWHE 202. In addition, both the inlet port 260 and the outlet port 262 can be axially aligned with the longitudinal axis L, meaning that the longitudinal axis L passes through a portion of each of the inlet port 260 and the outlet port 262. In some embodiments, both the inlet port 260 and the outlet port 262 are centered on the longitudinal axis L, meaning that the longitudinal axis L bisects the inlet diameter Di and the outlet diameter Do. In other embodiments, the inlet port 260 and the outlet port 262 are axially aligned with the longitudinal axis L, but the longitudinal axis is offset from the midpoint of the inlet diameter Di or the outlet diameter Do by no more than 10% of the diameter, no more than 15% of the diameter, or no more than 25% of the diameter.

[0040] This arrangement enables the effluent stream 232 to flow through the CWHE 202 in a direction parallel to the longitudinal axis L without a substantial change in the overall direction of the effluent stream 232 flowing through the body 258 of the CWHE 202. In this case, the conduit for the effluent stream 232 is a shell space without any bends or elbows. As described above, it should be understood that structures in the shell space such as cleaning devices, nozzle protrusions, fluid distribution devices, tube bundles, spacers, and mandrels may cause small local flow diversions around these structures, but will not change the overall flow direction through the body 258 of the CWHE 202. It should be understood that expansion or contraction of the flow parallel to the longitudinal axis L, such as at the inlet transition 281 and the outlet transition 282, does not constitute a "substantial change in overall flow direction."

[0041] The inlet transition 281 provides a gradual transition from the inlet port 260 to the body 258. Similarly, the outlet transition 282 provides a gradual transition from the body 258 to the outlet port 262. The inlet transition 281 tapers gradually outward from the inlet port 260 to the body 258. The outlet transition 282 tapers gradually inward from the body 258 to the outlet end 262. In this embodiment, the inlet transition 281 and the outlet transition 282 are both conical in shape. Other shapes that provide low fluid flow resistance can be set at the inlet transition 281 and the outlet transition 282, such as a flare shape or other quasi-conical shapes. In certain embodiments of the present invention, the inlet transition 281 and the outlet transition 282 all have a transition ratio greater than 0.7, greater than 0.85, greater than 1.0, or greater than 1.33. The transition ratio is defined as the length of the transition divided by the difference between the shell diameter Ds and the diameter of the inlet associated therewith (i.e., the inlet diameter Di of the inlet transition 281 and the outlet diameter Do of the outlet transition 282). It should also be understood that the surface providing the desired low fluid flow resistance in the transition can be part of the shell 201, or can be provided by a separate structure inside the shell 201.

[0042] At both ends of each bundle 211, 210, the tubes terminate at tube sheets that transition into conduits that pass through shell 201. For example, tubes 272a and 272b on the inlet side of feed bundle 211 terminate at tube sheet 273 that transitions into conduit 274 into which feed stream 203 flows.

[0043] In this embodiment, all heating duties for the tube bundles (feed bundle 211 and first coolant bundle 210) of CWHE 202 are provided by the effluent stream. In addition, when CWHE 202 is operated at the design operating conditions, inlet port 260 is the only port for the effluent stream (in this case, the first cooled effluent stream 232) to flow into the shell space of shell 201. Similarly, when CWHE 202 is operated at steady state at the design operating conditions, outlet port 262 is the only port for the effluent stream (in this case, the third cooled effluent stream 234) to flow out of the shell space.

[0044] Go to Figure 2B and Figure 4, spacers 270a to 270d are provided to maintain spacing between tube layers 268a to 268d and to prevent shell-side fluid flow from bypassing the tubes in the space occupied by spacers 270a to 270d. Each tube in the tube has an outer tube diameter d. The tubes of adjacent tube layers (e.g., 268a and 268b or 268b and 268c) are spaced apart from each other by a first tube center-to-center distance Dt (referred to as a "radial pitch") in a direction perpendicular to the longitudinal axis L of the shell 201, and are spaced apart from each other by a second tube center-to-center distance Dp (also referred to as a "longitudinal pitch") in a direction parallel to the longitudinal axis L. The dimensionless transverse tube spacing value is defined as the Dt / d ratio and reflects the fraction of the shell-side cross-sectional area available for shell-side flow. In this embodiment, the dimensionless transverse tube spacing is greater than 1.75, greater than 2.00, or greater than 2.25. In order to maintain very low pressure drop while providing a large surface area per unit exchanger volume, the ratio of Dt to Dp is greater than 1.40, greater than 1.70, or greater than 2.00.

[0045] Since the PDH reaction occurs under vacuum conditions, it is important to minimize the pressure drop in the effluent loop. The work required by the effluent compressor 212 is inversely proportional to the absolute pressure of the third cooled effluent stream 234, so the impact of the pressure drop is amplified at low operating pressures. The use of the first coolant bundle 210 as an effluent cooler in the coil heat exchanger 202 significantly reduces the pressure drop of the interconnecting pipes and fittings between the feed-effluent exchanger 102 and the water cooler 110. Assuming the same effluent compressor suction pressure, the benefit of the lower effluent pressure drop of the present invention can also be a reduction in the reactor operating pressure. This reduction increases the reactor output, which in turn reduces the flow of the recycle stream 222.

[0046] Figure 2The arrangement of the heat exchanger in has many advantages over the configuration of the prior art. In particular, the bundles 211, 210 can cool the reactor effluent to a desired temperature along the flow path (in the direction indicated by the arrow showing the flow of the second cooled effluent stream 236) without the need for a separate downstream cooling unit, and substantially without changing the overall direction of the effluent passing through the body 258 of the CWHE 202 along the longitudinal axial direction L. Therefore, there is a significantly lower pressure drop in the reactor effluent through the heat exchanger 202. In one or more embodiments, when operating at a shell side pressure below ambient pressure, the pressure drop is no more than 0.1 bara. In other words, the pressure at the suction side of the compressor 212 is at least 65%, at least 70%, or at least 80% of the shell side pressure at the inlet port 260. The reduction in pressure drop minimizes compression costs and also increases the reactor output that favors chemical reaction selectivity at lower pressures. The reduced pressure drop is at least partially due to combining the effluent cooling process in the same shell 201, which eliminates piping the cooled effluent from the heat exchanger 202 to the effluent cooler and reduces pressure drops associated with inlet losses, bends, and tees used to distribute the flow.

[0047] Figure 3 An exemplary alternative configuration of the outlet end 456 of the shell 401 is shown. In this embodiment, the outlet port 462 is positioned in the side wall of the shell 401, rather than being axially aligned with the inlet port (not shown in this figure) and the longitudinal axis L. The outlet end 456 includes a closed lower end 488. The outlet port 462 may have a Figure 2A The outlet port 262 has the same diameter Do. To reduce the pressure drop, the outlet port 462 may include a flared transition portion 486 within the shell 401 .

[0048] For some applications, it may be desirable to form the shell in a manner that enables it to be manufactured in multiple pieces and / or shipped to a factory site. Figure 2C An exemplary alternative configuration of a CWHE 302 is shown. In this example, the shell 301 is composed of an upper portion 394 and a lower portion 395 joined at a neck 396. The feed bundle 311 is contained within the upper portion 394, and the first coolant bundle 310 is contained within the lower portion 395. This configuration enables the upper portion 394 and the lower portion 395 to be assembled and transported to a factory site and then joined at the neck 396 (using any suitable means, such as bolts and / or welding) to form a fully assembled shell 301. In other examples, the neck portion may be omitted and / or the upper and lower portions may be of different diameters. For the purposes of this application, multiple shell portions (such as, an upper portion 395 and a lower portion 394) that are joined together to define a single continuous shell space before being put into use are considered to be a "single shell".

[0049] and Figure 2A The corresponding elements in Figure 2C The components in Figure 2C The utility model has Figure 2A Reference numerals having the same last two digits as those shown in the reference numerals in the specification, but may not be discussed separately in the specification. For example, Figure 2A The inlet port 254 corresponds to Figure 2C The inlet port 354.

[0050] Figure 5 A second exemplary PDH system 500 is shown, wherein FIGS. 1 and 5 Figure 2 The heat exchangers 108, 208 that generate steam are replaced by a second coolant bundle 508 that is part of the CWHE 502. In other words, the second coolant bundle 508 (which generates steam), the feed bundle 511, and the water cooler 510 are all contained within the same shell 501. This exemplary embodiment further reduces the effluent pressure drop between the reactor 506 and the compressor 512.

[0051] with Figure 1 and / or Figure 2 The corresponding elements in Figure 5 The components in Figure 5 The use of the same as Figure 1 and / or Figure 2 1 corresponds to a reference numeral having the same last two digits as the reference numerals shown in FIG. 1 , but may not be discussed separately in the specification. Figure 5 Reactor 506.

[0052] Figure 6 is a schematic diagram of another exemplary embodiment of a PDH system 600. The system 600 is similar to Figure 5 The system 500 is shown in FIG. 5 because it includes an integrated CWHE 602, wherein the second coolant bundle 608 (acting as a steam generator), the CWHE 602, and the first coolant bundle 610 are all contained within the same shell 601. Figure 5 Unlike the embodiment of FIG. 6 , the bypass 615 of the reactor effluent 607 is completely contained within the CWHE 602 with a bypass valve 650 .

[0053] Any bundle in CWHE 602 can be split into two or more bundles. Figure 6, the feed bundle can be split into a second portion 611b that is in downstream fluid flow communication with the first portion 611a and joined by a conduit 695. Providing separate bundle portions 611a, 611b allows the first portion 611a to be formed of a different material than the second portion 611b. For purposes of this application, "different materials" include, but are not limited to, different grades or compositions of the same alloy (such as 304H stainless steel and 304L stainless steel). For example, in one embodiment, the first portion 611a can be made of 304H stainless steel and the second portion 611b can be made of 304L stainless steel. In another embodiment, the first portion 611a can be made of stainless steel and the second portion 611b can be made of carbon steel or a nickel-chromium alloy (such as ). This allows each portion 611a, 611b to better match the tube-side and / or shell-side temperatures in the portion of the bundle, as well as other desired thermodynamic properties. Optionally, the portion of the shell that overlaps each portion of the bundle can be varied to better match the thermodynamic properties of that portion. Similarly, the separate bundles can be formed of different materials (i.e., the feed bundle 611 can be formed of a different material than the first coolant bundle 610).

[0054] with Figure 1 and / or Figure 2 The corresponding elements in Figure 6 The other components in Figure 6 The use of the same as Figure 1 and / or Figure 2 1 corresponds to a reference numeral having the same last two digits as the reference numerals shown in FIG. 1 , but may not be discussed separately in the specification. Figure 6 Reactor 606.

[0055] Fig. 6A Additional details of the bypass 615 are shown. The reactor effluent 607 enters the shell side of the CWHE 602. The bypass valve 650 is located at the lower end of the mandrel 672 around which the second coolant bundle 608 is wound. When the bypass valve 650 is open, the shell side flow in the area of ​​the second coolant bundle 608 is split into two paths. One flow path 605 flows through the second coolant bundle 608, and the other path (bypass 615) flows through the mandrel 672, thereby bypassing the second coolant bundle 608. The split between the path 605 and the bypass 615 is controlled by the bypass valve 650. At the bottom of the second coolant bundle 608, the two paths 605, 615 rejoin into a merged path 632, which then flows through the feed bundle 611. The other two mandrels 682, 692 are covered, which prevents the shell side flow from passing through these mandrels 682, 692.

[0056] Figure 7 1 and / or 2 are schematic diagrams of another exemplary embodiment of a PDH system 700. Figure 2 The corresponding elements in are basically the same Figure 7 The other components in Figure 7 The use of the same as Figure 1 and / or Figure 2 1 corresponds to a reference numeral having the same last two digits as the reference numerals shown in FIG. 1 , but may not be discussed separately in the specification. Figure 7 Reactor 706.

[0057] System 700 is very similar to Figure 2 The system 200, in addition to eliminating the heat exchanger 208 for generating steam and providing a feed heater 704, has significantly reduced emissions (such as electricity) when compared with the flamed feed heater 204. In this embodiment, the effluent stream 707 from the reactor 706 is fed directly to the feed bundle 702. Since the effluent stream 707 is not cooled before entering the feed bundle 702, the temperature of the effluent stream 707 is higher when it enters the feed bundle 702. Therefore, when the feed stream 703 leaves the feed bundle 702 as the first warmed propane stream 726, the feed stream (the effluent stream 707 is cooled by the feed stream in the feed bundle 702) will be heated to a higher temperature. The higher temperature of the first warmed propane stream 726 reduces the heating load required for the feed heater 704 and enables the use of a heater that reduces emissions to replace the flamed heater. This enables the system 700 to operate with lower carbonaceous gas emissions.

[0058] Example

[0059] In this embodiment, a simulation similar to Figure 2 , in which a single cooling water bundle (first coolant bundle 210) replaces four parallel shell and tube exchangers. The pressure at the first cooled effluent stream 232 (measured at the inlet of CWHE 202) is 0.39 bara, and the pressure at the third cooled effluent stream 234 (measured on the suction side of compressor 212) is 0.33 bara, representing a pressure drop of 0.06 bara. This means that 85% of the effluent pressure at the inlet is maintained at the outlet.

[0060] The scope of the present invention is not limited by the specific aspects or embodiments disclosed in the examples, which are intended to illustrate several aspects of the present invention, and any functionally equivalent embodiments are within the scope of the present invention. Various modifications of the present invention, in addition to those shown and described herein, will become apparent to those skilled in the art and are intended to fall within the scope of the appended claims.

Claims

1. A heat exchanger, comprising: a plurality of bundles, the plurality of bundles comprising at least one feed bundle and at least one coolant bundle, the at least one coolant bundle comprising a first coolant bundle, each bundle of the plurality of bundles comprising at least one tube bundle helically wound around a mandrel in a plurality of concentric layers, a tube inlet, a tube outlet, and a plurality of spacers positioned and shaped to provide spacing between each of the plurality of concentric layers; and a shell having a shell inlet, a shell outlet, a shell inlet end, a shell outlet end, and a shell longitudinal axis, the shell enclosing the plurality of bundles to define a shell space within the shell and outside each tube bundle in the at least one tube bundle, the shell inlet being located at the shell inlet end, and the shell outlet being located at the shell outlet end; wherein the shell inlet has a shell inlet diameter, the shell outlet has a shell outlet diameter, and the shell further comprises a body having a body diameter, an inlet transition portion extending from the shell inlet to an inlet end of the body, and an outlet transition portion extending from an outlet end of the body to the shell outlet; wherein the feed bundle portion includes the feed bundle and a portion of the body overlapping the feed bundle, and the first coolant bundle portion includes the first coolant bundle and a portion of the body overlapping the first coolant bundle; wherein the shell inlet is axially aligned along the shell longitudinal axis; and Wherein when an inlet pressure between 0.2 bara and 3.0 bara is supplied, the outlet pressure is at least 65% of said inlet pressure.

2. The heat exchanger of claim 1, wherein the outlet pressure is at least 80% of the inlet pressure.

3. The heat exchanger according to any one of claims 1 to 2, wherein the shell consists of a single shell.

4. The heat exchanger of any one of claims 1 to 3, wherein none of the at least one tube bundle of the at least one coolant bundle is in fluid flow communication with any of the at least one tube bundle of the at least one feed bundle.

5. The heat exchanger of any one of claims 1 to 4, wherein the shell inlet diameter and the shell outlet diameter are each at least 0.35 times the body diameter.

6. A heat exchanger according to any one of claims 1 to 5, wherein the shell outlet is axially aligned with the shell longitudinal axis.

7. The heat exchanger of claim 5, wherein the shell inlet is axially aligned with the shell outlet.

8. A heat exchanger according to any one of claims 1 to 7, wherein the shell defines a general flow path from the inlet end of the body to the outlet end of the body, the general flow path having no substantial change in general flow direction.

9. A heat exchanger according to any one of claims 1 to 8, wherein the inlet transition portion has an inlet transition length that tapers outwardly from the shell inlet to the body, and the ratio of the inlet transition length to the difference between the shell body diameter and the shell inlet diameter is greater than 0.

7.

10. The heat exchanger of claim 9, wherein the inlet transition portion is conical or quasi-conical in shape.

11. The heat exchanger of claim 9, wherein the inlet transition section is bellmouth in shape.

12. The heat exchanger of any one of claims 1 to 11, wherein the outlet transition portion has an outlet transition length that tapers outwardly from the shell outlet to the body, and a ratio of the outlet transition length to a difference between the shell body diameter and the shell outlet diameter is greater than 0.

7.

13. The heat exchanger of claim 12, wherein the outlet transition portion is conical or quasi-conical in shape.

14. The heat exchanger of any one of claims 1 to 13, wherein the plurality of spacers provide a radial pitch Dt between each of the plurality of concentric layers, each tube bundle of the at least one tube bundle has a tube diameter d, and a ratio of Dt / d is greater than 1.

75.

15. The heat exchanger of any one of claims 1 to 14, wherein each tube bundle in the at least one tube bundle has a longitudinal pitch Dp, and the plurality of spacers provide a radial pitch Dt between each concentric layer in the plurality of concentric layers, and a ratio of Dt / Dp is greater than 1.

40.

16. The heat exchanger according to any one of claims 1 to 15, wherein the at least one coolant bundle further includes a second coolant bundle, and the second coolant bundle portion includes the second coolant bundle and a portion of the body overlapping the second coolant bundle.

17. A heat exchanger according to claim 16, wherein the second coolant bundle portion is adapted so that the effluent flow flowing from the shell inlet to the shell outlet has a temperature at least 50 degrees Celsius higher at the tube inlet of the second coolant bundle portion than the temperature at the tube inlet of the at least one feed bundle.

18. The heat exchanger according to any one of claims 16 to 17, wherein at least one selected from the group of the second coolant bundle portion, the at least one feed bundle portion and the first coolant bundle portion is composed of a different material than the others in the group.

19. The heat exchanger of any one of claims 16 to 18, wherein the tube inlet of the second coolant bundle is in fluid flow communication with a second coolant, wherein the second coolant comprises at least 20% water.

20. A heat exchanger according to any one of claims 16 to 19, wherein the heat exchanger is operably configured to generate steam at the tube outlet of the second coolant bundle.

21. A heat exchanger according to any one of claims 1 to 20, wherein in steady state operation of the heat exchanger within design operating conditions, the shell inlet is the only port through which fluid providing a heating duty to any one of the plurality of bundles flows into the shell space.

22. A heat exchanger according to any one of claims 1 to 21, wherein in steady state operation of the heat exchanger within design operating conditions, the shell outlet is the only port through which fluid flows out of the shell space.

23. A heat exchanger according to any one of claims 1 to 22, wherein the heat exchanger is adapted to operate at a shell side pressure of not more than 1.0 bara.

24. A heat exchanger according to any one of claims 1 to 23, wherein the heat exchanger is adapted to operate at a shell side pressure of between 0.2 bara and 1.0 bara.

25. The heat exchanger of any one of claims 1 to 24, wherein the shell inlet is in downstream fluid flow communication with the tube outlet of the at least one feed bundle.

26. The heat exchanger of any one of claims 1 to 25, wherein the tube inlet of the first coolant bundle is in fluid flow communication with a first source of a first coolant, wherein the first coolant comprises at least 20% water.

27. A heat exchanger according to any one of claims 1 to 26, wherein the heat exchanger is adapted to operate at a temperature greater than or equal to ambient temperature and to flow a shell side fluid through the shell space to provide a heating duty to each of the plurality of bundles.

28. A heat exchanger according to any one of claims 1 to 27, wherein each of the plurality of bundles further comprises a shroud, the shroud comprising a shroud wall at least partially surrounding an outermost layer of the plurality of concentric layers, and an upper lip extending outwardly from an upper end of the shroud wall to an inner surface of the shell, thereby preventing a fluid flowing through the shell space from flowing through an annular space between the outermost layer and the inner surface of the shell.

29. A heat exchanger according to any one of claims 1 to 28, wherein the mandrel comprises a flow deflector which reduces aerodynamic drag on a shell-side fluid as it flows through the mandrel.

30. The heat exchanger of any one of claims 1 to 29, wherein the at least one feed bundle comprises a first feed bundle in upstream fluid flow communication with a second feed bundle.

31. The heat exchanger of claim 30, wherein the at least one tube bundle of the first feed bundle is made of a different material than the at least one tube bundle of the second feed bundle.

32. A heat exchanger according to any one of claims 1 to 31, wherein the shell outlet is not axially aligned with the shell longitudinal axis and the shell outlet comprises a bell-mouth shaped portion.

33. A heat exchanger, comprising: a plurality of bundles, the plurality of bundles comprising at least one feed bundle and at least one coolant bundle, the at least one coolant bundle comprising a first coolant bundle, each bundle of the plurality of bundles comprising at least one tube bundle helically wound around a mandrel in a plurality of concentric layers, a tube inlet, a tube outlet, and a plurality of spacers positioned and shaped to provide spacing between each of the plurality of concentric layers; and a shell having a shell inlet, a shell outlet, a shell inlet end, a shell outlet end, and a shell longitudinal axis, the shell enclosing the plurality of bundles to define a shell space within the shell and outside each tube bundle in the at least one tube bundle, the shell inlet being located at the shell inlet end, and the shell outlet being located at the shell outlet end; wherein the shell inlet has a shell inlet diameter, the shell outlet has a shell outlet diameter, and the shell further comprises a body having a body diameter, an inlet transition portion extending from the shell inlet to an inlet end of the body, and an outlet transition portion extending from an outlet end of the body to the shell outlet; wherein the feed bundle portion includes the at least one feed bundle and a portion of the body overlapping the at least one feed bundle, and the first coolant bundle portion includes the first coolant bundle and a portion of the body overlapping the first coolant bundle; wherein the shell inlet is axially aligned along the shell longitudinal axis; wherein the shell inlet diameter and the shell outlet diameter are each at least 0.35 times the body diameter, and The outlet transition portion has an outlet transition length that tapers outwardly from the shell outlet to the body, and a ratio of the outlet transition length to a difference between a shell body diameter and a shell outlet diameter is greater than 0.

7.

34. The heat exchanger of claim 33, wherein the shell outlet is axially aligned along the shell longitudinal axis.

35. A heat exchanger according to claims 33 to 34, wherein the inlet transition section and / or the outlet transition section is conical or quasi-conical in shape.

36. The heat exchanger of claims 33 to 34, wherein the inlet transition section and / or the outlet transition section is bellmouth in shape.

37. The heat exchanger of any one of claims 33 to 36, wherein the plurality of spacers provide a radial pitch Dt between each of the plurality of concentric layers, each tube bundle of the at least one tube bundle has a tube diameter d, and a ratio of Dt / d is greater than 1.

75.

38. A heat exchanger according to any one of claims 33 to 37, wherein each tube bundle in the at least one tube bundle has a longitudinal pitch Dp, and the plurality of spacers provide a radial pitch Dt between each concentric layer in the plurality of concentric layers, and the ratio of Dt / Dp is greater than 1.

40.

39. A heat exchanger according to any one of claims 33 to 38, wherein the shell inlet and / or the shell outlet is perpendicular to the shell longitudinal axis.

40. A method of operating a heat exchanger, the method comprising: (a) providing a plurality of bundles including at least one feed bundle and at least one coolant bundle, the at least one coolant bundle including a first coolant bundle, each bundle of the plurality of bundles including at least one tube bundle helically wound around a mandrel in a plurality of concentric layers, a tube inlet, a tube outlet, and a plurality of spacers positioned and shaped to provide spacing between each of the plurality of concentric layers; (b) providing a shell having a shell inlet, a shell outlet, a shell inlet end, a shell outlet end, and a shell longitudinal axis, the shell enclosing the plurality of bundles to define a shell space within the shell and outside each tube bundle in the at least one tube bundle, the shell inlet being located at the shell inlet end, and the shell outlet being located at the shell outlet end, wherein the shell inlet has a shell inlet diameter, the shell outlet has a shell outlet diameter, and the shell further comprises a body having a body diameter, an inlet transition portion extending from the shell inlet to the inlet end of the body, and an outlet transition portion extending from the outlet end of the body to the shell outlet; wherein the shell inlet is axially aligned along the shell longitudinal axis; (c) operating the heat exchanger at a temperature greater than or equal to ambient temperature; (d) operating the heat exchanger at a shell side pressure below ambient pressure; (e) supplying a shell-side fluid flowing through the shell space from the shell inlet to the shell outlet; (f) supplying a first fluid to the at least one feed stream; (g) supplying a second fluid to the first coolant beam; and (h) heating the first fluid and the second fluid with the shell-side fluid.

41. The method of claim 40, wherein step (a) further comprises providing a shell, wherein the shell outlet is axially aligned along the shell longitudinal axis.

42. The method of any one of claims 40 to 41, wherein step (e) further comprises supplying a shell-side fluid to the shell space at an inlet pressure and extracting the shell-side fluid from the shell space at an outlet pressure, the outlet pressure being not less than 65% of the inlet pressure.

43. The method according to any one of claims 40 to 41, wherein step (e) further comprises supplying a shell-side fluid to the shell space at an inlet pressure and extracting the shell-side fluid from the shell space at an outlet pressure, the outlet pressure being not less than 80% of the inlet pressure.

44. The method of any one of claims 40 to 43, wherein the shell-side fluid is a reaction product of the first fluid.

45. The method of any one of claims 40 to 44, wherein step (d) further comprises operating the heat exchanger at a shell side pressure of less than or equal to 3.0 bara.

46. ​​The method of any one of claims 40 to 45, wherein step (d) further comprises operating the heat exchanger at a shell side pressure of less than or equal to 0.4 bara.

47. The method of any one of claims 40 to 46, wherein the second fluid comprises water or an aqueous solution.

48. The method of any one of claims 40 to 47, wherein the at least one coolant beam further comprises a second coolant beam, and the method further comprises: (i) supplying a third fluid to the second coolant beam; as well as (j) heating the third fluid with the shell-side fluid.

49. The method according to claim 48, The third fluid exits the second coolant bundle as vapor.

50. A method according to any one of claims 40 to 49, wherein the shell side fluid exits the shell outlet as steam.

51. A method according to any one of claims 40 to 50, wherein the shell-side fluid is supplied to the inlet as a single-phase gaseous fluid.

52. A method of operating a heat exchanger, the method comprising: (a) providing a plurality of bundles including at least one feed bundle and at least one coolant bundle, each bundle of the plurality of bundles including at least one tube bundle helically wound around a mandrel in a plurality of concentric layers, a tube inlet, a tube outlet, and a plurality of spacers positioned and shaped to provide spacing between each of the plurality of concentric layers; (b) providing a shell having a shell inlet, a shell outlet, a shell inlet end, a shell outlet end, and a shell longitudinal axis, the shell enclosing the plurality of bundles thereby defining a shell space within the shell and outside each tube bundle in the at least one tube bundle, the shell inlet being located at the shell inlet end, and the shell outlet being located at the shell outlet end, wherein the shell inlet has a shell inlet diameter, the shell outlet has a shell outlet diameter, and the shell further comprises a body having a body diameter; (c) flowing a feed stream through the at least one feed bundle; (d) passing a coolant stream through each of the at least one coolant bundle; (e) passing an effluent stream through the shell space; as well as (f) providing a heating duty to each of the plurality of bundles with the effluent stream; wherein the effluent stream is a reaction product of the feed stream, and the shell space is in downstream fluid flow communication with the at least one feed bundle.

53. The method of claim 52, wherein the shell inlet is axially aligned along the shell longitudinal axis.

54. The method of any one of claims 52 to 53, wherein none of the at least one coolant bundle is in fluid flow communication with any of the at least one feed bundle.

55. The method of any one of claims 52 to 54, further comprising operating the heat exchanger at a temperature greater than or equal to ambient temperature.

56. The method of any one of claims 52 to 55, further comprising operating the heat exchanger at a shell side pressure below ambient pressure.

57. The method of any one of claims 52 to 56, further comprising flowing a second coolant stream through a second coolant bundle of the at least one coolant bundle to form steam.

58. The method of any one of claims 52 to 57, further comprising providing a shell side outlet pressure that is at least 65% of the shell side inlet pressure.

59. The method of any one of claims 52 to 58, further comprising providing a shell side outlet pressure that is at least 80% of the shell side inlet pressure.

60. The method of any one of claims 52 to 59, wherein the shell further comprises an inlet transition portion extending from the shell inlet to the inlet end of the body and an outlet transition portion extending from the outlet end of the body to the shell outlet.

61. The method of any one of claims 52 to 60, wherein step (d) further comprises flowing an aqueous coolant stream through each of the at least one coolant bundle.

62. The method of any one of claims 52 to 61, wherein step (e) further comprises flowing the effluent stream through the body without any substantial change in overall flow direction.

63. A heat exchanger, comprising: at least one bundle, the at least one bundle comprising a feed bundle or a coolant bundle, each bundle of the at least one bundle comprising at least one tube bundle helically wound around a mandrel in a plurality of concentric layers, a tube inlet, a tube outlet, and a plurality of spacers positioned and shaped to provide spacing between each of the plurality of concentric layers; and a shell having a shell inlet, a shell outlet, a shell inlet end, a shell outlet end, and a shell longitudinal axis, the shell enclosing the at least one bundle so as to define a shell space within the shell and outside each tube bundle in the at least one tube bundle, the shell inlet being located at the shell inlet end, and the shell outlet being located at the shell outlet end; wherein the shell inlet has a shell inlet diameter, the shell outlet has a shell outlet diameter, and the shell further comprises a body having a body diameter, an inlet transition portion extending from the shell inlet to an inlet end of the body, and an outlet transition portion extending from an outlet end of the body to the shell outlet; wherein the shell inlet is axially aligned along the shell longitudinal axis; and Wherein when an inlet pressure between 0.2 bara and 3.0 bara is supplied, the outlet pressure is at least 65% of said inlet pressure.

64. The heat exchanger of claim 63, wherein the shell outlet is axially aligned along the shell longitudinal axis.

65. A heat exchanger according to any one of claims 63 to 64, wherein the outlet pressure is at least 80% of the inlet pressure.

66. A heat exchanger according to any one of claims 63 to 65, wherein the at least one shell consists of a single shell.

67. A heat exchanger according to any one of claims 63 to 66, wherein the shell inlet diameter and the shell outlet diameter are each at least 0.35 times the body diameter.

68. A heat exchanger according to any one of claims 63 to 67, wherein the shell outlet is axially aligned with the shell longitudinal axis.

69. A heat exchanger according to any one of claims 63 to 68, wherein the shell defines a general flow path from the inlet end of the body to the outlet end of the body, the general flow path having no substantial change in general flow direction.

70. A heat exchanger according to any one of claims 63 to 69, wherein the inlet transition portion has an inlet transition length that tapers outwardly from the shell inlet to the body, and the ratio of the inlet transition length to the difference between the shell body diameter and the shell inlet diameter is greater than 0.

7.

71. A heat exchanger according to any one of claims 63 to 70, wherein the inlet transition portion is conical or quasi-conical in shape.

72. A heat exchanger according to any one of claims 63 to 71, wherein the outlet transition portion has an outlet transition length, gradually tapers outward from the shell outlet to the body, and the ratio of the outlet transition length to the difference between the shell body diameter and the shell outlet diameter is greater than 0.

7.

73. The heat exchanger of claim 72, wherein the outlet transition portion is conical or quasi-conical in shape.

74. A heat exchanger according to any one of claims 63 to 73, wherein the plurality of spacers provide a radial pitch Dt between each of the plurality of concentric layers, each tube bundle in the at least one tube bundle has a tube diameter d, and the ratio of Dt / d is greater than 1.

75.

75. A heat exchanger according to any one of claims 63 to 74, wherein each tube bundle in the at least one tube bundle has a longitudinal pitch Dp, and the plurality of spacers provide a radial pitch Dt between each concentric layer in the plurality of concentric layers, and the ratio of Dt / Dp is greater than 1.

40.

76. A heat exchanger according to any one of claims 1, 33 and 63 to 75, wherein the shell inlet has an inlet diameter Di, and the shell longitudinal axis L is offset from a midpoint of the inlet diameter Di by no more than 25% of the inlet diameter Di.

77. A heat exchanger according to any one of claims 1, 33 and 63 to 75, wherein the shell inlet is centered on the shell longitudinal axis L.

78. A heat exchanger according to any one of claims 1, 33 and 63 to 77, wherein the shell outlet has an outlet diameter Do, and the shell longitudinal axis L is offset from a midpoint of the outlet diameter Do by no more than 25% of the outlet diameter Do.

79. A heat exchanger according to any one of claims 1, 33 and 63 to 77, wherein the shell outlet is centered on the shell longitudinal axis L.

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