Turbine driven air compressor assembly for hydrocarbon dehydrogenation system

Abstract

The present disclosure provides a turbine driven air compressor assembly including a gas turbine having a first double-ended power shaft and a starter motor having a second double-ended power shaft, the starter motor having a power shaft end facing the gas turbine and a power shaft end remote from the gas turbine. The assembly also includes a first air compressor with which the gas turbine is drivingly connected. The power shaft end, away from the gas turbine, of the starting motor is in driving connection with the second air compressor. The present disclosure also provides a system for dehydrogenation of hydrocarbons, comprising a dehydrogenation reactor comprising a catalyst bed in fluid communication with a hydrocarbon feed source; and a regeneration air source in fluid communication with the dehydrogenation reactor, wherein the regeneration air source is the turbine-driven air compressor assembly described above.

Description

Technical Field

[0001] This disclosure relates to turbine-driven air compressor assemblies and related methods of use in systems and processes for hydrocarbon dehydrogenation. 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 parallel fixed-bed reactors and a catalyst regeneration system. When the fixed-bed dehydrogenation unit is operating, one or more reactors are online (in dehydrogenation mode), and one or more fixed-bed reactors are in regeneration mode.

[0003] First, the fixed-bed reactor in dehydrogenation mode 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 blown in to decoke the catalyst placed in the fixed-bed reactor. The reactor is then evacuated, and the catalyst undergoes reduction. After catalyst reduction, the reactor is brought back online for dehydrogenation. For each fixed-bed reactor, the same sequence is automatically repeated using a programmable logic controller (PLC) to ensure continuous production of the entire dehydrogenation unit.

[0004] Increasing the hydrocarbon flow rate to the dehydrogenation reactor is desirable to increase production, but without an accompanying increase in the regenerated air supply, the air-to-hydrogen ratio in the process decreases. This leads to wider temperature fluctuations within the catalyst bed, which can reduce yield. There remains a need in the art to increase the air supply to the dehydrogenation reactor in an efficient manner while minimizing capital costs. Summary of the Invention

[0005] Exemplary embodiments of this disclosure relate to a turbine-driven air compressor assembly that can be used to supply regenerated air for hydrocarbon dehydrogenation. The air compressor assembly utilizes a starter motor (e.g., a turbine, typically already present in the device) to assist in the start-up of the gas turbine to drive a main regenerated air compressor, which in turn drives a second regenerated air compressor. In a conventional system arrangement, the starter turbine is used to drive the power shaft of the gas turbine until the gas turbine reaches rpm suitable for independent turbine operation, and thereafter remains idle. In this disclosure, the starter turbine can be used to drive additional regenerated air into the dehydrogenation reactor, rather than remaining idle for extended periods between gas turbine start-ups.

[0006] This disclosure includes, but is not limited to, the following implementation schemes.

[0007] Implementation Scheme 1: A system for hydrocarbon dehydrogenation, comprising: i) a dehydrogenation unit (100) including a catalyst bed reactor in fluid communication with a hydrocarbon feed (11) source; and ii) a regenerated air source in fluid communication with the dehydrogenation unit, wherein the regenerated air source is a turbine-driven air compressor assembly (82), the turbine-driven air compressor assembly (82) comprising: a) a gas turbine (60) including: i. a first double-ended power shaft extending axially through the gas turbine; and ii. a first power shaft end (52); and iii. a second power shaft end (54); iv. a starter motor including: 1. a second double-ended power shaft extending axially through the starter motor; and 2. a gas turbine-facing... 1) The power shaft end of the gas turbine; and 2) The power shaft end away from the gas turbine, wherein the power shaft end facing the gas turbine is drivenly connected to the first power shaft end (52) of the gas turbine (60) via a clutch that enables the starter motor to engage and disengage from the gas turbine; b) A first air compressor (40), the second power shaft end (54) of the gas turbine (60) being drivenly connected to the first air compressor such that the first air compressor is located on the side of the gas turbine opposite to the starter motor; and c) A second air compressor (80), the power shaft end of the starter motor away from the gas turbine being drivenly connected to the second air compressor such that the second air compressor is located on the side of the starter motor opposite to the gas turbine.

[0008] Implementation Scheme 2: The system according to Implementation Scheme 1 further includes a clutch between the second air compressor and the starter motor, the clutch being capable of engaging and disengaging the starter motor from the second air compressor.

[0009] Implementation Scheme 3: The system according to Implementation Scheme 1 or 2, wherein the starting motor is a steam turbine.

[0010] Implementation Scheme 4: The system according to any one of Implementation Schemes 1 to 3, wherein the power output of the starting motor in MW is about 30% or less of the power output of the gas turbine.

[0011] Implementation Scheme 5: The system according to any one of Implementation Schemes 1 to 4, wherein the first air compressor outputs about 550 to about 820 t / h of air, and the second air compressor outputs about 120 to about 220 t / h of air.

[0012] Implementation Scheme 6: A system for hydrocarbon dehydrogenation, comprising: a dehydrogenation reactor including a catalyst bed in fluid communication with a hydrocarbon feed source; and a regenerated air source in fluid communication with the dehydrogenation reactor, wherein the regenerated air source is a turbine-driven air compressor assembly of any one of Implementation Schemes 1 to 5.

[0013] Implementation Scheme 7: The system according to Implementation Scheme 6 further includes a reducing gas source in fluid communication with the dehydrogenation reactor and / or a steam purge gas source in fluid communication with the dehydrogenation reactor.

[0014] Implementation Scheme 8: The system according to Implementation Scheme 6 or 7, wherein the hydrocarbon feed source provides hydrocarbons selected from propane, isobutane, pentane, isopentane, n-butane, 1-butene and combinations thereof.

[0015] Implementation Scheme 9: A method for performing hydrocarbon hydrogenation in a dehydrogenation reactor, comprising: a turbine-driven air compressor assembly, the turbine-driven air compressor assembly including at least: a gas turbine; a starter motor; a dual-ended power shaft; a first air compressor and a second air compressor, the method comprising at least the following steps: i) connecting the starter motor to the gas turbine before starting the gas turbine; ii) operating the starter motor to drive the first dual-ended power shaft until the gas turbine reaches an rpm suitable for gas turbine operation; iii) disconnecting the starter motor from the gas turbine; iv) operating the gas turbine to drive power to the first air compressor; v) connecting the starter motor to the second air compressor; and vi) operating the starter motor to drive power to the second air compressor, wherein the method further comprises the step of: introducing air from the first air compressor and the second air compressor into a dehydrogenation reactor including a catalyst bed for the regeneration of the catalyst bed.

[0016] Implementation Scheme 10: The method according to Implementation Scheme 9 further includes introducing air from a first air compressor and a second air compressor into a dehydrogenation reactor including a catalyst bed for the regeneration of the catalyst bed.

[0017] These and other features, aspects, and advantages of this disclosure will become apparent from the following detailed description and the accompanying drawings (briefly described below). This disclosure includes any combination of two, three, four, or more features or elements set forth herein, whether or not such features or elements are explicitly combined or otherwise described in the specific exemplary embodiments described herein. This disclosure is intended to be interpreted holistically; therefore, unless the context of this disclosure explicitly indicates otherwise, any separable feature or element of this disclosure (in any aspect and exemplary embodiment) should be considered composable.

[0018] Therefore, it will be understood that this invention is provided merely to summarize some exemplary embodiments in order to provide a basic understanding of some aspects of this disclosure. It will also be understood that the above exemplary embodiments 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 taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of some of the described exemplary embodiments. Attached Figure Description

[0019] Since aspects of this disclosure have been described in the foregoing general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0020] Figure 1 This is a schematic representation of a dehydrogenation reactor system according to an exemplary embodiment of the present disclosure;

[0021] Figure 2 This is a schematic representation of an exemplary embodiment of a turbine-driven air compressor assembly according to an exemplary embodiment of the present disclosure; and

[0022] Figure 3 This is another illustrative representation of an exemplary embodiment of a turbine-driven air compressor assembly according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0023] Some embodiments of this disclosure will be described more fully below with reference to the accompanying drawings, which illustrate some, but not all, 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 to make this disclosure exhaustive and complete, and to fully convey the scope of this disclosure to those skilled in the art. Throughout the text, similar reference numerals refer to similar elements.

[0024] Unless otherwise stated or clearly apparent from 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 apparent from the context) may conversely be below, and vice versa; and similarly, a feature described as being to the left of another feature may conversely be to the right, and vice versa. Furthermore, while this document may refer 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.

[0025] 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 of the range “5 wt% to 25 wt%” and all intermediate values, etc.). “Combination” includes blends, mixtures, alloys, reaction products, etc.

[0026] As used herein, unless otherwise stated or clearly apparent from the context, an "OR" of a set of operands is an "inclusive OR" and is therefore true if and only if one or more operands are true, unlike 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" or "one or more types" unless otherwise stated or clearly apparent from the context.

[0027] This disclosure provides a turbine-driven air compressor assembly that can be used in any process or system including starting a turbine or other starting motor / engine that is idle for most of its service life, and that can be used more efficiently as a power source. However, this disclosure is particularly well-suited for dehydrogenation processes in which the supply of regenerated air is typically a limiting factor.

[0028] Dehydrogenation processes and systems

[0029] Therefore, this disclosure relates to potential improvements for dehydrogenation processes, for example, on chromium-alumina catalysts, to convert alkanes to olefins. The dehydrogenation process occurs in a fixed-bed reactor, which operates on a recycle basis to allow continuous flow of the main process feed. In one cycle, hydrocarbon vapors are dehydrogenated, and then the reactor is purged with steam and coke is burned off by air. These steps are followed by vacuuming and reduction, and then another cycle begins.

[0030] 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 the corresponding olefins. The olefins are then flushed out of the catalyst bed, the catalyst is regenerated and reduced, and the cycle is repeated. The products (dehydrogenated hydrocarbons) of a fixed-bed dehydrogenation unit may include, for example, propylene, isobutene, pentene, isoprene, butadiene, or combinations thereof. The dehydrogenation reaction may include reactions (i) and / or (ii) as follows, wherein “n” in reactions (i) and (ii) is the number of carbon atoms in the hydrocarbon molecule, and “n” is less than 5:

[0031] C n H 2n+2 C n H 2n +H2(i), and / or

[0032] C n H 2n C n H 2n-2 +H2(ii).

[0033] 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 step of regeneration with air. After this, the cycle starts again with a catalyst reduction step.

[0034] The reactor in the dehydrogenation process operates under vacuum. Vacuuming of the reactor is accomplished using a reactor vacuum ejector, and conventionally, MP vapor is used as the motive fluid.

[0035] refer to Figure 1 The diagram illustrates a process schematic of an exemplary 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 fixed-bed reactor includes a catalyst bed. The catalyst may include, for example, Cr / Al (chromium oxide on alumina), Sn-Pt / Al (tin-platinum on alumina), or combinations thereof.

[0036] The inlet of the fixed-bed reactor 102 in dehydrogenation mode can be connected to a heater 110, which is 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. The combined hydrocarbon stream 13 (which is a combination of the hydrocarbon feed stream 11 and the recirculated hydrocarbon stream 12) can be vaporized 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 is typically in the range of about 0.2 to about 1.2 bar.

[0037] The fixed-bed dehydrogenation unit 100 may further 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 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 can be used to generate steam via the heat exchanger 107. Regeneration conditions may include, for example, a regeneration pressure of about 0.1 to about 10 bar. Regeneration conditions may include a regeneration period typically in the range of about 7 to about 18 minutes.

[0038] The fixed-bed dehydrogenation unit 100 may further include a compression and recovery system 109 to recover and purify 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 compression and 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.

[0039] The fixed-bed dehydrogenation unit 100 may also include a purge gas source 20 (e.g., steam) in fluid communication with each reactor for the purge step, and a reducing gas source 22 (e.g., hydrogen) in fluid communication with each reactor.

[0040] Programmable logic controllers (PLCs) can be used, for example, to control the process sequence. See, for example, the PLCs described in U.S. Patent No. 11,370,729 (Ansari et al.) and U.S. Patent Publication No. 2022 / 0055002 (Bodas et al.), which are incorporated herein by reference in their entirety.

[0041] Turbine-driven air compressor assembly

[0042] According to this disclosure, an air compressor assembly is provided, which can be used, for example, as... Figure 1 Air compressor 104. Figure 2 An exemplary embodiment of the air compressor assembly is shown at reference numeral 30 in the accompanying drawings. As shown, a starting turbine 50 is located between the gas turbine 60 and the first air compressor 40. The starting turbine 50 has a double-ended power shaft extending axially through the turbine and has a first power shaft end 52 facing the gas turbine 60 and a second power shaft end 54 facing the first air compressor 40. The power shaft of the starting turbine 50 is adapted to be connected to the drive shafts of both the gas turbine 60 and the first air compressor 40 to provide power to both components. The connection of the starting turbine 50 to each of the gas turbine 60 and the first air compressor 40 is typically capable of being engaged and disengaged via clutches 42a and 42b, respectively.

[0043] The gas turbine 60 also includes a double-ended power shaft adapted to connect to both the start-up turbine 50 and the second air compressor 80 as described above. In conventional dehydrogenation plants, the second air compressor 80, driven by the gas turbine 60, is the sole source of regenerated air for the process, and the start-up turbine 50 remains idle except during gas turbine startup. In this disclosure, the start-up turbine 60 is used more efficiently to drive the air compressor, which increases the supply of regenerated air available for, for example, the dehydrogenation process.

[0044] Figure 2A typical gas turbine design is also shown, illustrating a gas turbine 60 that includes an internal compressor 62 that receives air from an inlet 64 and produces a pressurized effluent 66. The pressurized effluent 66 is in fluid communication with an internal combustor 68, which also receives combustible fuel 70. The combustor effluent 72 enters an internal turbine 74, which generates work from the energy of the gas. The exhaust gas 76 from the gas turbine 60 can be fed into a waste heat boiler (not shown). The gas turbine 60 is used to drive an external regenerative air compressor, such as a second air compressor 80, which, for example, produces regenerative air to be sent to a dehydrogenation reactor, such as... Figure 1 Those shown.

[0045] Figure 3 Another illustrative representation of an exemplary embodiment of this disclosure is shown. As shown, the turbine-driven air compressor assembly 82 includes a starting steam turbine 84 capable of engaging / disengaging with a first air compressor 86 via a clutch 88. The starting steam turbine 84 is also capable of engaging / disengaging with a gas turbine 90 via a clutch 92. The gas turbine 90 drives a second air compressor 94. US9309810B2 relates to an arrangement using a gas turbine unit, a steam turbine unit, and a compressor to liquefy natural gas. US2006042259A1 relates to combined cycle power generation units and steam thermal power generation units installed near medium or small gas and oil fields.

[0046] Operating the air compressor assembly of this disclosure typically involves connecting a starter motor to the gas turbine before starting the gas turbine, and operating the starter motor to drive the dual-ended power shaft of the gas turbine until the gas turbine reaches a rotational speed (rpm) suitable for gas turbine operation. Thereafter, the starter motor is disconnected from the gas turbine, which, after starting, will be used to drive power to the second air compressor. The starter motor is then connected to and used to drive power to the first air compressor.

[0047] The regeneration gas requirements in dehydrogenation systems are typically quite high, necessitating the use of gas turbines to drive regeneration air compressors. Exemplary gas turbines for driving regeneration air compressors include the GEMS5001 available from General Electric, and the SGT 750 and SGT 700 available from Siemens. Typically, such gas turbines feature multi-stage internal axial combustion air compressors.

[0048] A typical start-up turbine has a significantly smaller power output (in MW) compared to a gas turbine, typically about 30% or less (e.g., about 15% to about 25%). Such a start-up turbine is typically a steam turbine that extracts heat energy from pressurized steam to drive a power shaft. The amount of additional regenerated air supplied to the dehydrogenation process will be proportional to the power of the start-up turbine, meaning that if the start-up turbine has 15-25% of the power output of the gas turbine driving the main air compressor, then when used as shown in this disclosure, the start-up turbine can power the production of an additional 15-25% of regenerated air. In some embodiments, the air compressor driven by the gas turbine outputs about 550 to about 820 t / h of air (e.g., about 680 t / h), and the air compressor driven by the start-up turbine outputs about 120 to about 220 t / h of air (e.g., about 150 t / h).

[0049] Although gas turbine starting systems typically use steam turbines, this disclosure is not limited to such systems. Any starting motor (and which includes a double-ended power shaft) used to generate power for starting a gas turbine is applicable to this disclosure. For example, the starting motor may be in the form of a turbine, an electric motor, or an internal combustion engine.

[0050] The type of air compressor used in this disclosure can vary. Exemplary types of air compressors include reciprocating air compressors, rotary air compressors, centrifugal air compressors, and axial flow air compressors. The type of clutch used to engage / disengage the power shaft of the starting turbine is also not limiting. A typical clutch will include a flywheel, friction discs, pressure plates, springs, and a release lever. Exemplary clutch types include friction clutches, hydraulic clutches, centrifugal clutches, and single-plate and multi-plate clutches.

[0051] Generally, the present invention may alternatively comprise, consist of, or consist substantially of any suitable components disclosed herein. The present invention may additionally or alternatively be formulated to be free of, or substantially free of, any components, materials, ingredients, additives, or classes of substances used in prior art compositions, or which are not essential for achieving the function and / or purpose of the present invention.

[0052] Many modifications and other embodiments of this disclosure will be apparent to those skilled in the art upon which the foregoing description and accompanying drawings have been presented. 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 in a general and descriptive sense only and not for limiting purposes.

Claims

1. A system for dehydrogenation of a hydrocarbon comprising: i) a dehydrogenation unit (100) comprising a catalyst bed reactor in fluid communication with a source of a hydrocarbon feed (11); and ii) a source of regeneration air in fluid communication with the dehydrogenation unit, wherein the source of regeneration air is a turbine driven air compressor assembly (82), the turbine driven air compressor assembly (82) comprising: a) a gas turbine (60) comprising: i. a first double ended power shaft extending axially through the gas turbine; and ii. a first power shaft end (52); and iii. a second power shaft end (54); iv. a start-up motor comprising:

1. a second double ended power shaft extending axially through the start-up motor; and 2. a power shaft end facing the gas turbine; and 3. a power shaft end facing away from the gas turbine, wherein the power shaft end facing the gas turbine is drivingly connected to the first power shaft end (52) of the gas turbine (60) via a clutch, the clutch capable of coupling and decoupling the start-up motor from the gas turbine; b) a first air compressor (40), the second power shaft end (54) of the gas turbine (60) drivingly connected to the first air compressor such that the first air compressor is located on an opposite side of the gas turbine from the start-up motor; and c) a second air compressor (80), the power shaft end of the start-up motor facing away from the gas turbine drivingly connected to the second air compressor such that the second air compressor is located on an opposite side of the start-up motor from the gas turbine.

2. The system of claim 1, further comprising a clutch between the second air compressor and the start-up motor, the clutch capable of coupling and decoupling the start-up motor from the second air compressor.

3. The system of claim 1 or claim 2, wherein the start-up motor is a steam turbine.

4. The system of any one of claims 1 to 3, wherein the power output of the start-up motor in MW is about 30% or less of the power output of the gas turbine.

5. The system of any one of claims 1 to 4, wherein the first air compressor outputs about 550 to about 820 t / h of air and the second air compressor outputs about 120 to about 220 t / h of air.

6. A system for dehydrogenation of a hydrocarbon comprising: i) a dehydrogenation reactor comprising a catalyst bed in fluid communication with a source of a hydrocarbon feed; and ii) a source of regeneration air in fluid communication with the dehydrogenation reactor, wherein the source of regeneration air is a turbine driven air compressor assembly of any one of claims 1 to 5.

7. The system of claim 6, further comprising a source of reducing gas in fluid communication with the dehydrogenation reactor and / or a source of steam purge gas in fluid communication with the dehydrogenation reactor.

8. The system of claim 6 or claim 7, wherein the source of a hydrocarbon feed provides a hydrocarbon selected from the group consisting of propane, isobutane, pentane, isopentane, n-butane, 1-butene, and combinations thereof.

9. A method for performing a hydrocarbon hydrogenation in a dehydrogenation reactor comprising: a turbine driven air compressor assembly, the turbine driven air compressor assembly comprising at least: • a gas turbine; • a start-up motor; • a double ended power shaft; • a first air compressor; and • a second air compressor, the method comprising at least the steps of: i) coupling the start-up motor to the gas turbine prior to gas turbine start-up; ii) operating the start-up motor to drive the first double ended power shaft until the gas turbine reaches an rpm suitable for gas turbine operation; iii) decoupling the start-up motor from the gas turbine; iv) operating the gas turbine to drive power to the first air compressor; v) coupling the start-up motor to the second air compressor; and vi) operating the start-up motor to drive power to the second air compressor, wherein the method further comprises the step of passing air from the first air compressor and the second air compressor into a dehydrogenation reactor comprising a catalyst bed for regeneration of the catalyst bed.

10. The method of claim 9, further comprising passing air from the first air compressor and the second air compressor into a dehydrogenation reactor comprising a catalyst bed for regeneration of the catalyst bed.

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