Reactor emptying method and system for dehydrogenation reactor

Abstract

The present disclosure provides a method of emptying a high temperature reactor requiring vacuum pressure during one or more steps of a reaction process, comprising directing a stream of reducing gas from the reactor to a quench system in fluid communication with the reactor, the quench system comprising one or more enclosures, wherein the reducing gas stream is in direct contact with a liquid cooling medium, and the liquid cooling medium is water; withdrawing a cooled gas stream from the quench system; and directing the cooled gas stream to a vacuum pump in fluid communication with the quench system and the reactor to reduce the pressure within the reactor to a vacuum pressure. Also provided are systems for emptying a high temperature reactor, including a high temperature reactor in combination with a quench system and a vacuum pump, as described above.

Description

Technical Field

[0001] This disclosure relates to methods and systems for venting high-temperature reactors and for the dehydrogenation of hydrocarbons. Background Technology

[0002] Fixed-bed dehydrogenation units are used to produce olefins and / or alkynes from alkanes and / or olefins. Typically, a fixed-bed dehydrogenation unit comprises three or more fixed-bed reactors in parallel and a catalyst regeneration system. When the fixed-bed dehydrogenation unit is in operation, one or more reactors are online (in dehydrogenation mode), and one or more fixed-bed reactors are in regeneration mode.

[0003] In dehydrogenation mode, the fixed-bed reactor first dehydrogenates the hydrocarbon feed for a period of time. Then, the fixed-bed reactor is purged with steam. In the subsequent regeneration mode, heated air is purged to decoke the catalyst in the fixed-bed reactor. The reactor is then vented, and the catalyst undergoes reduction. After catalyst reduction, the reactor is returned to online operation for dehydrogenation reactions. The same sequence is automatically repeated for each fixed-bed reactor using a programmable logic controller (PLC) to ensure continuous production of the entire dehydrogenation unit.

[0004] Fixed-bed dehydrogenation reactors operate under vacuum during one or more steps of the dehydrogenation process, particularly during the dehydrogenation and reduction steps. While the vacuum for the dehydrogenation step is directly generated by a process gas compressor located downstream (after a series of gas cooling unit operations), the vacuum for the reduction step is typically generated by a steam ejector using steam as the motive fluid. This is because the reduction products are typically non-process gases / exhaust gases. Typically, in large dehydrogenation units, approximately 20-30 t / hr of steam is discharged through this ejector at an absolute pressure of 12-13 bar. Prior to the reduction step, the regeneration air products remaining in the reactor system need to be completely purged. Purging is cyclical because air regeneration in the reactor occurs at nominal pressure, thus requiring purging of the reactor during each production cycle. The use of such a large volume of steam as the motive fluid presents a significant cost because the steam passing through the ejector is vented to the atmosphere. There remains a need in the art to reduce costs and improve the efficiency of operating dehydrogenation reactors. Summary of the Invention

[0005] Example embodiments of this disclosure relate to methods and systems for the dehydrogenation of hydrocarbons, and more generally to methods and systems for venting any high-temperature reactor requiring vacuum pressure during one or more steps of a reaction process. In some embodiments, this disclosure provides a method for venting a high-temperature reactor, the method comprising directing a reducing gas stream from the reactor to a quenching system in fluid communication with the reactor, the quenching system comprising one or more enclosures wherein the reducing gas stream is in direct contact with a liquid cooling medium, wherein the liquid cooling medium is water; removing the cooled gas stream from the quenching system; and directing the cooled gas stream to a vacuum pump in fluid communication with the quenching system and the reactor to reduce the pressure within the reactor to vacuum pressure. In this way, the conventional use of ejectors that release steam into the atmosphere to vent the reactor is avoided, which can improve the energy efficiency of the method and reduce costs associated with steam production.

[0006] The dehydrogenation system according to this disclosure includes: a dehydrogenation reactor comprising a catalyst bed in fluid communication with a hydrocarbon feed source; a regeneration air source in fluid communication with the dehydrogenation reactor; a reducing gas source in fluid communication with the dehydrogenation reactor; and a reactor venting system in fluid communication with the dehydrogenation reactor, such as the reactor venting system disclosed herein.

[0007] This disclosure includes, but is not limited to, the following implementation plan.

[0008] Implementation Scheme 1: A method for venting a high-temperature reactor requiring vacuum pressure during one or more process steps (such as during dehydrogenation and / or reduction steps), comprising: directing a reducing gas stream from the reactor to a quenching system in fluid communication with the reactor, the quenching system comprising one or more enclosures wherein the reducing gas stream is in direct contact with a liquid cooling medium, wherein the liquid cooling medium is water; removing the cooled gas stream from the quenching system; and directing the cooled gas stream to a vacuum pump in fluid communication with the quenching system and the reactor to reduce the pressure within the reactor to vacuum pressure.

[0009] Implementation Scheme 2: The method of Implementation Scheme 1, wherein the quenching system comprises: a conduit in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact a reducing gas stream within the conduit; and / or a container in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact a reducing gas stream within the container, the container including a gas outlet for a gaseous effluent and a cooling medium outlet for a liquid cooling medium effluent; and / or a liquid-cooled heat exchanger in fluid communication with the reactor; and / or any combination thereof.

[0010] Implementation Scheme 3: The method of Implementation Scheme 1 or 2, which further includes discharging the cooled gas stream from the vacuum pump to the atmosphere.

[0011] Implementation Scheme 4: The method of any one of Implementation Schemes 1 to 3, wherein the vacuum pump is a dry vacuum pump or a liquid ring vacuum pump.

[0012] Implementation Scheme 5: The method of any one of Implementation Schemes 1 to 4, wherein the temperature of the cooled gas stream guided to the vacuum pump is about 150°C or lower, such as about 25°C to about 120°C or about 30°C to about 80°C.

[0013] Implementation Scheme 6: The method of any one of Implementation Schemes 1 to 5, wherein the reactor is vented to an absolute pressure of about 0.6 bar or less, such as a vacuum pressure of about 0.2 to about 0.6 bar absolute pressure.

[0014] Implementation Scheme 7: The method of any one of Implementation Schemes 1 to 6, wherein the reducing gas stream guided from the reactor to the quenching system has a temperature of about 400°C to about 800°C, such as about 500°C to about 750°C.

[0015] Implementation Scheme 8: The method of any one of Implementation Schemes 1 to 7, wherein the reactor is a dehydrogenation reactor.

[0016] Implementation Scheme 9: A system for venting a high-temperature reactor requiring vacuum pressure during one or more process steps, comprising: a high-temperature reactor; a quenching system in fluid communication with the reactor and positioned to receive a reducing gas stream from the reactor, the quenching system including one or more enclosures wherein the reducing gas stream is in direct contact with a liquid cooling medium, wherein the liquid cooling medium is water; a source of the liquid cooling medium in fluid communication with the quenching system; and a vacuum pump in fluid communication with the quenching system and the reactor and positioned to receive a cooled gas stream from the quenching system, the vacuum pump being adapted to reduce the pressure within the reactor to a vacuum pressure.

[0017] Implementation Scheme 10: The system of Implementation Scheme 9, wherein the quenching system comprises: a conduit in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the conduit; and / or a container in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the container, the container including a gas outlet for a gaseous effluent and a cooling medium outlet for a liquid cooling medium effluent; and / or a liquid-cooled heat exchanger in fluid communication with the reactor; and / or any combination thereof.

[0018] Implementation Scheme 11: The system of Implementation Scheme 9 or 10, wherein the container is a vertical quench tower, the vertical quench tower including a demister adjacent to the top of the tower, a plurality of spray nozzles adapted to guide the cooling medium spray toward the bottom of the tower, packing or a plurality of trays between the spray nozzles and the bottom of the tower, and a gas inlet adjacent to the bottom of the tower, wherein the gas outlet is above the demister.

[0019] Implementation Scheme 12: A system of any one of Implementation Schemes 9 to 11, wherein a vacuum pump is vented to the atmosphere to release a cooled gas flow.

[0020] Implementation Scheme 13: A system of any one of Implementation Schemes 9 to 12, wherein the vacuum pump is a dry vacuum pump or a liquid ring vacuum pump.

[0021] Implementation Scheme 14: The system of any one of Implementation Schemes 9 to 13, wherein the vacuum pump is adapted to evacuate the reactor to a vacuum pressure of about 0.6 bar absolute pressure or less, such as a vacuum pressure of about 0.2 to about 0.6 bar absolute pressure.

[0022] Implementation Scheme 15: A system of any one of Implementation Schemes 9 to 14, wherein the reactor is a dehydrogenation reactor.

[0023] Implementation Scheme 16: A method of operating a dehydrogenation reactor that requires vacuum pressure during one or more steps of a dehydrogenation process to remove exhaust gas to be released to the atmosphere from the reactor, the method comprising: feeding hydrocarbons into a reactor including a catalyst bed and configured to dehydrogenate hydrocarbons (e.g., to produce olefins) under vacuum pressure; optionally purging the reactor to remove residual hydrocarbons; regenerating the catalyst bed with air from a regenerated air source; venting the reactor to induce vacuum pressure; and feeding a reducing gas into the reactor after venting the reactor to reduce the catalyst, wherein the venting method comprises the method of any one of Implementation Schemes 1 to 8.

[0024] Implementation Scheme 17: The method of Implementation Scheme 16, wherein the hydrocarbon is selected from the group consisting of propane, isobutane, pentane, isopentane, n-butane, 1-butene, and combinations thereof.

[0025] Implementation Scheme 18: The method of any one of Implementation Schemes 16 or 17, wherein purging the reactor includes passing steam through the reactor.

[0026] Implementation Scheme 19: A system for dehydrogenating hydrocarbons, comprising: a dehydrogenation reactor including a catalyst bed in fluid communication with a hydrocarbon feed source; a regeneration air source in fluid communication with the dehydrogenation reactor; a reducing gas source in fluid communication with the dehydrogenation reactor; and a reactor venting system as described in any one of Implementation Schemes 9 to 15.

[0027] Implementation Scheme 20: The system of Implementation Scheme 19, which further includes a purge gas source, such as a steam source, in fluid communication with the dehydrogenation reactor.

[0028] Implementation Scheme 21: The system of Implementation Scheme 19 or 20, wherein the hydrocarbon feed source provides hydrocarbons selected from the group consisting of propane, isobutane, pentane, isopentane, n-butane, 1-butene, and combinations thereof.

[0029] These and other features, aspects, and advantages of this disclosure will become apparent from reading the following detailed description together with the accompanying drawings, which are briefly described below. This disclosure includes any combination of two, three, four, or more features or elements set forth in this disclosure, whether such features or elements are explicitly combined or otherwise described in the specific exemplary embodiments described herein. Unless the context of this disclosure expressly provides otherwise, this disclosure is intended to be read holistically, such that any separable features or elements of this disclosure should be considered composable in any aspect and exemplary embodiment.

[0030] Therefore, it will be appreciated that the summary portion is provided only for the purpose of summarizing some exemplary embodiments in order to provide a basic understanding of some aspects of this disclosure. It will also be appreciated that the exemplary embodiments described above are merely examples and should not be construed as limiting the scope or spirit of this disclosure in any way. Other exemplary embodiments, aspects, and advantages will become apparent from the following detailed description, together with the accompanying drawings, which illustrate by way of example the principles of some of the described exemplary embodiments. Attached Figure Description

[0031] Therefore, aspects of this disclosure have been described using the aforementioned general terms, and reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0032] Figure 1 This is a schematic diagram of a dehydrogenation reactor system according to an exemplary embodiment of the present disclosure;

[0033] Figure 2 A schematic diagram of an example embodiment of a single dehydrogenation reactor illustrates a reactor evacuation system according to an example embodiment of this disclosure;

[0034] Figure 3 The diagram illustrates how the water temperature in a liquid ring vacuum pump changes with the water vapor pressure.

[0035] Figure 4 A schematic diagram of an example embodiment of a quenching system according to an example implementation of this disclosure; and

[0036] Figure 5The illustration shows the energy savings of an example embodiment of this disclosure compared to a conventional steam jet ejector system. Detailed Implementation

[0037] Some embodiments of this disclosure will now be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, of the embodiments of this disclosure. In fact, various embodiments of this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art. The same reference numerals throughout refer to the same elements.

[0038] Unless otherwise stated or clearly indicated by the context, references to first, second, etc., should not be construed as implying a particular order. A feature described as being above another feature (unless otherwise stated or clearly indicated by the context) may alternatively be below another feature, and vice versa; and similarly, a feature described as being to the left of another feature may alternatively be to the right of another feature, and vice versa. Furthermore, while references may be made herein to quantitative measurements, values, geometric relationships, etc., any one or more of these (if not all) may be absolute or approximate, unless otherwise stated, to account for acceptable variations that may occur, such as those due to engineering tolerances, etc.

[0039] All ranges disclosed herein include endpoints, and endpoints can be combined independently of each other (e.g., the range “up to 25 wt%, or more specifically, 5 wt% to 20 wt%” includes the endpoints and all intermediate values ​​of the range “5 wt% to 25 wt%”, etc.). “Combination” includes blends, mixtures, alloys, reaction products, etc.

[0040] As used herein, unless otherwise stated or clearly indicated by the context, an "OR" of a set of operands is an "inclusive OR," and therefore true if and only if one or more operands are true, as opposed to an "exclusive OR," which is false if all operands are true. Thus, for example, "[A] OR [B]" is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Furthermore, the articles "a" and "an" mean "one or more," unless otherwise stated or clearly indicated by the context to be in the singular form.

[0041] This disclosure relates to methods and systems for venting high-temperature reactors that require vacuum pressure during a reaction, and can be applied to any high-temperature reaction process that requires venting the reactor to vacuum pressure. Example processes include various dehydrogenation processes, such as the CATOFIN® dehydrogenation process and ODH-E (oxidative dehydrogenation of ethane) processes, such as the EDHOX™ technology available from Linde Engineering, and other redox oxidative dehydrogenation (redox-ODH) reactions, such as those used for styrene production described in Zhu, X., Gao, Y., Wang, X. et al., A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme. Nat Commun 12, 1329 (2021). For illustrative purposes only, the use of venting systems and methods of this disclosure is described herein in the context of dehydrogenation reactions for the conversion of alkanes to olefins.

[0042] Dehydrogenation processes and systems

[0043] In one embodiment, this disclosure relates to improvements in reactor venting for a dehydrogenation process converting alkanes to olefins over, for example, a chromium-alumina catalyst. The dehydrogenation process is carried out in a fixed-bed reactor, which operates on a recycle basis to allow continuous flow of the main process stream. In one cycle, hydrocarbon vapors are dehydrogenated, then the reactor is purged with steam and purged with air to burn off the coke. These steps are followed by venting and reduction, and then another cycle begins.

[0044] In a typical fixed-bed dehydrogenation process, aliphatic hydrocarbons (e.g., propane, isobutane, n-butane, 1-butene, or isopentane) pass through a dehydrogenation catalyst bed and are dehydrogenated to complementary olefins. The olefins are then flushed out of the catalyst bed to regenerate and reduce the catalyst, and this cycle is repeated. The products of the fixed-bed dehydrogenation unit (dehydrogenated hydrocarbons) can include, for example, propylene, isobutene, pentene, isoprene, butadiene, or combinations thereof. The dehydrogenation reaction can include reactions (i) and / or (ii) as follows, where “n” in reactions (i) and (ii) is the number of carbon atoms in the hydrocarbon molecule, and “n” is less than 5:

[0045]

[0046] This process can be operated as an adiabatic cycle. Each cycle includes a catalyst reduction step and a dehydrogenation step, and typically also includes a step of purging residual hydrocarbons from the reactor, and a final regeneration step using air. After this, the cycle starts again with a catalyst reduction step.

[0047] The reactor in the dehydrogenation process operates under vacuum during various steps of the reaction, such as during dehydrogenation and during catalyst reduction. Draining of the reactor is accomplished using a combination of a quenching system and a vacuum pump, as described in more detail below. The final reactor pressure after draining is typically about 0.6 bar or lower, such as about 0.2 to about 0.6 bar (absolute pressure).

[0048] refer to Figure 1 The diagram illustrates a process schematic of an example embodiment of a fixed-bed dehydrogenation unit 100, wherein different reactors are located at different points in the process cycle. The fixed-bed dehydrogenation unit 100 may include a fixed-bed reactor 101 in purge mode, a fixed-bed reactor 102 in dehydrogenation mode, and a fixed-bed reactor 103 in regeneration mode. Each of the fixed-bed reactors includes a catalyst bed. The catalyst may include Cr / Al (chromium oxide on alumina), Sn-Pt / Al (tin-platinum on alumina), or combinations thereof.

[0049] The inlet of the fixed-bed reactor 102 in dehydrogenation mode can be connected to a heater 110 configured to heat the hydrocarbon feed to the reaction temperature, and the outlet of the fixed-bed reactor 102 in dehydrogenation mode can be connected to a heat exchanger 108 to cool the effluent from the fixed-bed reactor 102 in dehydrogenation mode. A combined hydrocarbon stream 13 from the hydrocarbon feed stream 11 and the recycled hydrocarbon stream 12 can be evaporated and heated to the reaction temperature by the heater 110. The reaction temperature is typically from about 540°C to about 750°C. The reaction pressure can be in the range of about 0.2 to about 1.2 bar absolute pressure, such as from about 0.2 to about 0.6 bar absolute pressure.

[0050] The fixed-bed dehydrogenation unit 100 may additionally include a regeneration air system comprising an air compressor 104 configured to blow air into the fixed-bed reactor 103 in regeneration mode, a regeneration air heater 105 configured to heat the air from the air compressor 104, a fuel injector 106 configured to inject fuel gas into the fixed-bed reactor 103 in regeneration mode, and a heat exchanger 107 configured to cool the effluent from the fixed-bed reactor 103 in regeneration mode and the fixed-bed reactor 101 in purging mode. The effluent from the reactor in purging mode may be configured to be cooled in heat exchanger 107 or 108 using a suitable condensate recovery system. The fuel injector 106 may be disposed between the air compressor 104 and the air heater 105. The feed stream 16 exiting the fixed-bed reactor 103 in regeneration mode may be used to generate steam via heat exchanger 107. Regeneration conditions may include a regeneration pressure of about 0.1 bar to about 10 bar. Regeneration conditions may include regeneration periods ranging from approximately 7 to approximately 18 minutes.

[0051] The fixed-bed dehydrogenation unit 100 may additionally include a compression and recovery system 109 to recover and purify the dehydrogenated hydrocarbons obtained from the fixed-bed reactor 102 in dehydrogenation mode. Specifically, the effluent stream 14 from the fixed-bed reactor 102 in dehydrogenation mode can be cooled, recovered, and purified by the recovery system 109. The purified dehydrogenated hydrocarbons can flow in stream 17. The recovered unreacted hydrocarbons can be recycled back to the combined hydrocarbon stream 13 via the recirculated hydrocarbon stream 12.

[0052] The fixed-bed dehydrogenation unit 100 may additionally include a purge gas source 20 (e.g., steam) in fluid communication with each reactor for a purge step and a reducing gas source 22 (e.g., hydrogen) in fluid communication with each reactor for reducing the catalyst.

[0053] Programmable logic controllers can be used, for example, to control process sequences. See, for example, the programmable logic controllers described in U.S. Patent No. 11,370,729 to Ansari et al. and U.S. Patent Publication No. 2022 / 0055002 to Bodas et al., which are incorporated herein by reference in their entirety.

[0054] Drainage system of dehydrogenation reactor

[0055] According to this disclosure, a quenching system combined with a vacuum pump is used for reactor venting. An example embodiment of the dehydrogenation reactor system 30 is described in... Figure 2 As shown in the image. For simplicity, Figure 2 A single reactor is shown, but as Figure 1 As shown, the dehydrogenation unit typically includes multiple reactors operating in parallel. System 30 includes reactor 32 in fluid communication with hydrocarbon feed 34, regeneration air feed 36, purge gas feed 38, and reducing gas feed 40. Reactor 32 has a hydrocarbon outflow stream 42 and a waste gas outflow stream 44.

[0056] In addition, such as Figure 2 As shown, reactor 32 is also in fluid communication with a quenching system 50 and a vacuum pump 46 adapted to vent reactor 32 to a vacuum pressure. Unlike conventional systems that use an ejector that receives steam as the motive gas, this disclosure utilizes the vacuum pump 46 to vent reactor 32. The quenching system 50 (explained more fully below) cools the reducing gas received from reactor 32, which is then received by the vacuum pump 46 and ultimately discharged as an effluent stream 48. By replacing the need for steam as the motive gas and avoiding the release of large amounts of steam into the atmosphere, the energy efficiency of the entire dehydrogenation process is improved and the costs associated with steam production are reduced.

[0057] The temperature of the reducing gas feed stream from reactor 32 upstream of quenching system 50 can vary, but is typically in the range of about 400°C to about 800°C, such as about 500°C to about 750°C. The cooled gas feed stream directed to vacuum pump 46 can vary, but is typically about 150°C or lower, such as about 25°C to about 120°C or about 30°C to about 80°C.

[0058] The proposed quenching system 50 provides a direct contact quenching arrangement for the reducing gas, comprising at least one enclosed body (e.g., a container or pipe) in which a liquid cooling medium is in direct contact with the reducing gas exiting reactor 32. The quenching system 50 may also include indirect cooling of the reducing gas via, for example, the presence of one or more heat exchangers within the quenching system and / or via a jacketed pipe or container, which, in addition to providing direct contact with the liquid cooling medium, also provides cooling water circulation through the jacket. As shown, a source of liquid cooling medium 28 (water) is in fluid communication with the quenching system and can be used, for example, as a source of liquid cooling medium for both direct and indirect cooling of the reducing gas disposed in the quenching system 50.

[0059] Example embodiments of direct contact cooling enclosures include one or more pipes equipped with one or more nozzles for injecting a cooling medium to directly contact the reducing gas stream within the pipes; and one or more tower containers with an internal nozzle injection system. Such containers may be horizontally or vertically oriented, have counter-current or co-current configurations, and are equipped with a nozzle injection system to inject water as a liquid cooling medium at any temperature below its boiling point. The quenching container may have a wet-wall or dry-wall configuration, optionally with integrated water knockout. Suitable control schemes can be used to ensure, for example, that the gas temperature leaving the quenching system 50 is partially controlled by the water supply rate. Typically, the quenching system is adapted to cool the reducing gas from a high temperature (e.g., in the range of 200-1200°C) to its saturation temperature under vacuum pressure.

[0060] The cooled gas is drawn into a mechanical vacuum pump 46, where work is done to drive the gas to outlet conditions (typically atmospheric). The mechanical vacuum pump can be a liquid ring or dry vacuum type, for example, driven by a variable-speed electric motor. A suitable control scheme can be used to ensure that the variable-speed drive adapts to pressure change dynamics. The proposed quenching scheme overcomes the main limitations of mechanical vacuum pumps for high-temperature applications through direct contact cooling of the reducing gas integrated into the upstream application. In some embodiments, the quenching scheme provides excellent energy efficiency by using an electrically driven pump instead of a steam jet injection system. The quenching scheme reduces CO2 emissions directly related to power steam production and prevents process water associated with the jet from leaking into the environment.

[0061] Example vacuum pumps suitable for use in the systems and methods disclosed herein include vacuum pumps manufactured by Gardner Denver Nash, LLC and Edwards Ltd. Example vacuum pumps may be dry, such as rotary vane pumps or dry screw vacuum pumps, or liquid ring vacuum pumps.

[0062] In one embodiment, the vacuum pump is a liquid ring vacuum pump, which typically consists of a rotating bladed impeller eccentrically positioned within a cylindrical housing. A liquid (typically water or oil) is supplied to the pump and, as the impeller rotates, forms a moving cylindrical ring against the inner side of the housing. This creates a series of seals in the space between the impeller blades that form the compression chamber. During operation, gas from the quenching system 50 is drawn into the pump through the inlet port, trapped in the compression chamber formed within the liquid ring, and compressed before being discharged. For the liquid ring vacuum pump, the temperature of the water, the ring medium, determines the minimum achievable vacuum pressure based on the vapor pressure of water. An example illustration of the relationship between liquid ring water temperature and water vapor pressure is shown in [illustration missing]. Figure 3 In the middle. As shown, the lower water temperature in the liquid ring results in a lower achievable vapor pressure.

[0063] Figure 4 An example embodiment of the quenching system 50 is shown. The illustrated embodiment is provided only as an example system configuration and can be modified to other configurations without departing from this disclosure. For example, the sequence of unit operations, the configuration of the quenching vessel in terms of flow direction and orientation, and the location of any optional heat exchanger can be changed. In the illustrated embodiment, the reducing gas feed stream 52 is drawn from the reactor (e.g., from...) Figure 2 The reactor 32 receives and is fed into a conduit 54 equipped with one or more nozzles 56, which spray a liquid cooling medium, such as water, to directly contact the reducing gas within the conduit. As shown, the conduit 54 is optionally equipped with a cooling water jacket 58, which receives a cooling water feed 60 and produces a cooling water effluent 62. In this way, the conduit 54 can simultaneously provide both direct and indirect contact with the cooling medium.

[0064] Gas effluent 66 from conduit 54 can enter quench container 64. In the illustrated embodiment, quench container 64 provides countercurrent direct contact between gas feed 66 and water ejected from one or more nozzles 68 located at the top of an adjacent container. Quench container 64 may include a series of stacked trays 70 that facilitate direct contact between rising gas and falling liquid cooling medium. Alternatively, quench container 64 may include a packed bed (not shown) to facilitate gas / liquid contact. Similar to conduit 54, quench container 64 may optionally also include a cooling water jacket 72 that receives cooling water feed 74 and produces cooling water effluent 76, such that the quench container provides both direct and indirect contact with the cooling medium. The liquid cooling medium is removed from quench container 64 as liquid effluent 78, and the gas exits the top of the container as gas effluent 80. As shown, quench container 64 may additionally include a gas demister 82 adjacent to the top of the container to reduce liquid entrainment in the gas leaving the container.

[0065] The quenching system 50 may also include one or more heat exchangers, such as heat exchanger 84, for additional indirect heat exchange with the gas. These exchangers may be included at any location within the system, such as upstream of pipe 54, between pipe and quenching container 64, within the quenching container, and / or downstream of the quenching container. The heat exchangers may have any type and configuration suitable for gas-to-liquid heat exchange, including shell-and-tube heat exchangers and plate heat exchangers.

[0066] As shown, the gas leaving the quench system 50 is supplied to the vacuum pump 86, where it is compressed and discharged to reduce the pressure in the upstream reactor. The quench system 50 may also include one or more additional gas-liquid separators (not shown), such as flash drums, knock-out drums, separator tanks, compressor suction drums, etc., at any suitable location upstream of the vacuum pump 86.

[0067] As shown, optionally, a recirculation line 90 from the outlet of vacuum pump 86 to the inlet of vacuum pump can be used to provide at least a partial recirculation of the effluent from the vacuum pump to the pump inlet. A flow regulator (not shown) can be used to regulate the flow rate in the recirculation line 90 to handle interruptions in the feed flow to the vacuum pump while still maintaining the desired reactor pressure.

[0068] experiment

[0069] A model-based sensitivity study was conducted using Aspen Plus to evaluate the energy-saving benefits of the proposed concept relative to conventional steam ejectors, based on the following foundations and assumptions:

[0070] Reducing gas (suction fluid) temperature: 600℃;

[0071] Molecular weight of the pumped fluid: 25.5 Kg / Kmol

[0072] The amount of quench water consumed under adiabatic conditions;

[0073] The feed water was rapidly cooled to 40°C;

[0074] Gas outlet conditions at saturation;

[0075] The isentropic efficiency of the vacuum pump is taken as 75%.

[0076] The electric drive system has an efficiency of 95%, and the grid efficiency is 37.5%.

[0077] The power steam pressure is 10-12 bar and the temperature is 200-300℃; and

[0078] The power steam energy demand is estimated based on steam jet ejector charts available from publicly available literature.

[0079] Based on the above assumptions, a model is constructed for the energy consumption curve (MJ / T of the vented reducing gas) and as follows: Figure 5 As shown, this figure compares the proposed quenching system / vacuum pump, modeled using a balanced flash separation method, with that using a conventional steam jet ejector. It is clear from the figure that the proposed system consumes significantly less energy per tonne of vented reducing gas compared to a conventional steam jet system (in which a large amount of steam energy is lost as latent heat). This difference is particularly significant at lower vacuum pressures. Energy-related CO2 emissions are directly calculated based on the CO2 emission factor / MJ of energy consumed (depending on fuel composition and calorific value). This assessment demonstrates that the proposed system can provide a competitive advantage, thereby improving energy efficiency and reducing carbon emissions for high-temperature operating applications such as the venting of reducing gas and vacuum generation for hydrocarbon dehydrogenation.

[0080] Generally, the present invention may alternatively include, consist of, or substantially consist of any suitable components disclosed herein. The present invention may also be conceived additionally or alternatively as lacking or substantially absent any component, material, ingredient, adjuvant, or class of substances used in the prior art or not essential for achieving the function and / or purpose of the present invention.

[0081] Many modifications and other embodiments of this disclosure will arise to those skilled in the art upon which this disclosure pertains, taking advantage of the teachings presented in the foregoing specification and related drawings. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed herein, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terminology is used herein, it is used only in a general and descriptive sense and not for limiting purposes.

Claims

1. A method for venting a high-temperature reactor that requires vacuum pressure during one or more steps of a reaction process, comprising: a) Guiding a reducing gas stream from the reactor to a quenching system in fluid communication with the reactor, the quenching system comprising one or more enclosed bodies, wherein the reducing gas stream is in direct contact with a liquid cooling medium, wherein the liquid cooling medium is water; b) Remove the cooled gas stream from the quenching system; and c) The cooled gas stream is directed to a vacuum pump in fluid communication with the quenching system and the reactor to reduce the pressure inside the reactor to a vacuum pressure.

2. The method according to claim 1, wherein the quenching system comprises: i) A conduit in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the conduit; and / or ii) A container in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the container, the container including a gas outlet for a gaseous effluent and a cooling medium outlet for a liquid cooling medium effluent; and / or iii) A liquid-cooled heat exchanger in fluid communication with the reactor; and / or iv) Any combination of two or more of i), ii) and iii).

3. The method according to claim 1 or claim 2, further comprising discharging the cooled gas stream from the vacuum pump to the atmosphere.

4. The method according to any one of claims 1 to 3, wherein the vacuum pump is a dry vacuum pump or a liquid ring vacuum pump.

5. The method according to any one of claims 1 to 4, wherein the temperature of the cooled gas stream guided to the vacuum pump is about 150°C or lower, such as about 25°C to about 120°C or about 30°C to about 80°C.

6. The method according to any one of claims 1 to 5, wherein the reactor is vented to a pressure of about 0.6 bar absolute or less, such as a vacuum pressure of about 0.2 to about 0.6 bar absolute.

7. The method according to any one of claims 1 to 6, wherein the reducing gas stream guided from the reactor to the quenching system has a temperature of about 400°C to about 800°C, such as about 500°C to about 750°C.

8. The method according to any one of claims 1 to 7, wherein the reactor is a dehydrogenation reactor.

9. A system for venting a high-temperature reactor that requires vacuum pressure during one or more steps of a reaction process, comprising: a) High-temperature reactor; b) A quenching system in fluid communication with the reactor and positioned to receive a reducing gas stream from the reactor, the quenching system comprising one or more enclosed bodies, wherein the reducing gas stream is in direct contact with a liquid cooling medium, wherein the liquid cooling medium is water; c) A source of liquid cooling medium in fluid communication with the quenching system; and d) A vacuum pump in fluid communication with the quenching system and the reactor and positioned to receive a cooled gaseous stream from the quenching system, the vacuum pump being adapted to reduce the pressure within the reactor to a vacuum pressure.

10. The system of claim 9, wherein the quenching system comprises: i) A conduit in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the conduit; and / or ii) A container in fluid communication with the reactor and equipped with one or more nozzles, the nozzles being positioned to spray a cooling medium to directly contact the reducing gas stream within the container, the container including a gas outlet for a gaseous effluent and a cooling medium outlet for a liquid cooling medium effluent; and / or iii) A liquid-cooled heat exchanger in fluid communication with the reactor; and / or iv) Any combination of two or more of i), ii) and iii).

11. The system of claim 10, wherein the container is a vertical quench tower, the vertical quench tower comprising a demister adjacent to the top of the tower, a plurality of spray nozzles adapted to direct a cooling medium spray toward the bottom of the tower, packing or a plurality of trays between the spray nozzles and the bottom of the tower, and a gas inlet adjacent to the bottom of the tower, wherein the gas outlet is above the demister.

12. The system according to any one of claims 9 to 11, wherein the vacuum pump is vented to the atmosphere to release a cooled gas flow.

13. The system according to any one of claims 9 to 12, wherein the vacuum pump is a dry vacuum pump or a liquid ring vacuum pump.

14. The system according to any one of claims 9 to 13, wherein the vacuum pump is adapted to evacuate the reactor to a vacuum pressure of about 0.6 bar absolute or less, such as a vacuum pressure of about 0.2 to about 0.6 bar absolute.

15. The system according to any one of claims 9 to 14, wherein the reactor is a dehydrogenation reactor.

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