Carbon capture and utilization systems and methods for olefin cracking processes

Abstract

The application discloses a carbon capture and utilization system for an olefin cracking process, which comprises an olefin cracking device, a combustion heat supply device, a heat exchanger, an oxygen supply device and a CO2 pretreatment device in fluid communication, characterized in that the system comprises a first hydrogen pretreatment device for separating hydrogen from by-products of the olefin cracking device and increasing hydrogen pressure, an inlet of the first hydrogen pretreatment device being in communication with an outlet of the olefin cracking device; and a CO2 hydrogenation reactor for receiving pretreated CO2 and hydrogen, the CO2 hydrogenation reactor being provided with a CO2 inlet and a first hydrogen inlet, the CO2 inlet being in communication with an outlet of the CO2 pretreatment device, and the first hydrogen inlet being in communication with an outlet of the first hydrogen pretreatment device. The application also discloses a carbon capture and utilization method for an olefin cracking process.

Description

Technical Field

[0001] This application relates to the field of carbon capture and utilization technology. Specifically, this application relates to carbon capture and utilization systems and methods for olefin cracking processes. Background Technology

[0002] The information provided in this section is for the purpose of generally presenting the background of this disclosure. To the extent described in this section, the work of the currently named inventors and aspects of the description that may not constitute prior art at the time of filing are neither explicitly nor implicitly considered to be prior art of this disclosure.

[0003] Existing olefin cracking processes face numerous challenges in achieving emission reduction and zero-carbon goals. Although carbon capture technology has reduced CO2 emissions to some extent, current processes mainly focus on CO2 capture and absorption. Due to the large volume of flue gas and low CO2 concentration, investment in carbon capture facilities is substantial, and the actual utilization rate of captured CO2 is low, making it difficult to effectively convert it into valuable products. Furthermore, since fully electric operation is not feasible under current conditions, cracking processes relying on fossil fuel heating remain the primary mode, resulting in limited emission reduction effects.

[0004] Furthermore, the products of olefin cracking processes typically require a dehydrogenation step, but the large amount of waste hydrogen generated during dehydrogenation is not fully recovered and utilized, and is often emitted as waste gas, further increasing resource waste. Existing processes have failed to effectively combine the captured CO2 with the waste hydrogen from cracking to achieve the production of high-value-added chemicals through hydrogenation reactions, thus failing to form a comprehensive zero-carbon emission olefin cracking process system. Summary of the Invention

[0005] This application provides systems and methods for carbon capture and utilization in olefin cracking processes to address one or more of the problems mentioned above and other issues, or to provide alternative technical solutions to existing technologies.

[0006] According to one aspect of this application, a carbon capture and utilization system for an olefin cracking process is provided, comprising an olefin cracking unit, a combustion heating unit, a heat exchanger, an oxygen supply unit, and a CO2 pretreatment unit in fluid communication. The heat exchanger is provided with a first inlet, a second inlet, a first outlet, and a second outlet. The first inlet is connected to the outlet of the combustion heating unit, the second inlet is connected to the oxygen outlet of the oxygen supply unit, the first outlet is connected to the reflux inlet of the combustion heating unit, the first outlet is connected to the reflux inlet of the combustion heating unit, and the second outlet is connected to the inlet of the CO2 pretreatment unit. The carbon capture and utilization system includes:

[0007] A first hydrogen pretreatment unit, used to separate hydrogen from the byproducts of the olefin cracking unit and to increase the hydrogen pressure, wherein the inlet of the first hydrogen pretreatment unit is connected to the outlet of the olefin cracking unit; and

[0008] A CO2 hydrogenation reactor is provided for receiving pretreated CO2 and hydrogen. The CO2 hydrogenation reactor is provided with a CO2 inlet and a first hydrogen inlet. The CO2 inlet is connected to the outlet of the CO2 pretreatment device, and the first hydrogen inlet is connected to the outlet of the first hydrogen pretreatment device.

[0009] In the carbon capture and utilization system according to this application, preferably, the oxygen supply device includes a water electrolysis device for supplying hydrogen to the CO2 hydrogenation reactor, the water electrolysis device is further provided with a hydrogen outlet and the CO2 hydrogenation reactor is provided with a second hydrogen inlet, the hydrogen outlet of the water electrolysis device is connected to the second hydrogen inlet of the CO2 hydrogenation reactor via a part of a second hydrogen pretreatment device.

[0010] In the carbon capture and utilization system according to this application, preferably, renewable energy is used to supply electrical energy to the water electrolysis device.

[0011] In the carbon capture and utilization system according to this application, preferably, the oxygen supply device includes an air separation device for receiving air and separating oxygen therefrom.

[0012] In the carbon capture and utilization system according to this application, preferably, the air separation device is further provided with a nitrogen outlet, which is connected to an ammonia production system.

[0013] In the carbon capture and utilization system according to this application, preferably, the outlet of the CO2 hydrogenation reactor is connected to a CO2 hydrogenation product preparation process system.

[0014] According to another aspect of this application, a method for carbon capture and utilization in an olefin cracking process is provided, the method comprising the following steps:

[0015] Oxygen is supplied to the combustion heating device through a heat exchanger via an oxygen supply device.

[0016] Fuel gas is supplied from the fuel inlet of the combustion heating device to the combustion heating device for oxygen-enriched combustion in the presence of oxygen, generating combustion products containing CO2 and water vapor;

[0017] The combustion products are introduced into the heat exchanger to cool and remove water vapor from the combustion products. A portion of the resulting cooled and dehydrated products is introduced into the combustion heating device from the first outlet of the heat exchanger through the reflux inlet of the combustion heating device, and another portion is introduced into the CO2 pretreatment device from the second outlet of the heat exchanger.

[0018] The introduced CO2 is further processed using the CO2 pretreatment device and supplied to the CO2 hydrogenation reactor;

[0019] Raw material gas is supplied from the raw material inlet of the combustion heating device to the combustion heating device. Under the heat provided by the oxygen-enriched combustion, the raw material gas is introduced into the olefin cracking device and undergoes an olefin cracking reaction to generate olefin cracking products and hydrogen-containing byproducts.

[0020] The hydrogen-containing byproduct is introduced into a first hydrogen pretreatment unit to separate hydrogen from the byproduct and increase the hydrogen pressure, and the resulting hydrogen is supplied to the CO2 hydrogenation reactor; and

[0021] The CO2 supplied to the CO2 hydrogenation reactor undergoes a hydrogenation reaction with hydrogen to generate CO2 hydrogenation products.

[0022] In the carbon capture and utilization method according to this application, preferably, a water electrolysis device is used as the oxygen supply device, and the hydrogen generated by the water electrolysis device is processed by a second hydrogen pretreatment device and then supplied to the CO2 hydrogenation reactor.

[0023] In the carbon capture and utilization method according to this application, preferably, the method further includes the following steps:

[0024] The water electrolysis apparatus is supplied with electricity using renewable energy sources, and the electricity is used in other processes according to this application.

[0025] In the carbon capture and utilization method according to this application, preferably, an air separation device for receiving air and separating oxygen therefrom is used as the oxygen supply device, and the residual nitrogen generated by the air separation device is supplied to an ammonia production system for the production of ammonia.

[0026] In the carbon capture and utilization method according to this application, preferably, the method further includes the following steps:

[0027] The CO2 hydrogenation product is introduced into the CO2 hydrogenation product preparation process system to further convert the CO2 hydrogenation product into the downstream reaction product of the CO2 hydrogenation product.

[0028] In the carbon capture and utilization method according to this application, preferably, the method further includes the following temperature control step:

[0029] Controlling the flow rate of fuel gas supplied to the combustion heating device to maintain the combustion heating device within the range of 700°C to 1200°C; and

[0030] The flow rate of the cooling and dehydration products of the combustion heating device is introduced from the first outlet of the heat exchanger through the return inlet of the combustion heating device to reduce the flame temperature of the combustion heating device.

[0031] The technical solution provided in this application significantly reduces total flue gas emissions and nitrogen oxide generation by employing oxygen-enriched combustion technology, thereby lowering the cost and energy consumption of CO2 capture. Based on this, the byproduct hydrogen from the olefin cracking process is efficiently separated and reacted with CO2 to generate high-value-added products, reducing the demand for external hydrogen and optimizing energy consumption. Furthermore, by combining a green-electricity-driven water electrolysis process, oxygen and hydrogen are supplied simultaneously, further reducing carbon emissions and improving energy efficiency, achieving the goal of zero carbon emissions for the entire process, and significantly improving resource utilization and economic benefits. Attached Figure Description

[0032] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0033] Figure 1 An exemplary system for carbon capture in olefin cracking processes is shown.

[0034] Figure 2 An exemplary system for carbon capture and utilization in an olefin cracking process according to this application is shown. Detailed Implementation

[0035] To make the foregoing objectives, features, and advantages of this application more apparent and understandable, specific embodiments of a carbon capture and utilization system and method for olefin cracking processes are described in detail below with reference to the accompanying drawings. It should be understood that all descriptions are exemplary and should not be used to limit this application in any way. For any single technical feature described or implied in the various embodiments mentioned herein, or any single technical feature shown or implied in the various drawings, the present invention still allows for any further combination or deletion of these technical features (or their equivalents) without any technical obstacle; therefore, these further embodiments according to this application should also be considered to be included within the scope of this description.

[0036] Unless otherwise specified, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art described in this application. In case of any inconsistency, the definitions provided in this application shall prevail.

[0037] In this application, unless otherwise expressly stated, the terms "first," "second," etc., are used only for distinguishing purposes and are not intended to indicate their order or relative importance.

[0038] In this application, unless otherwise expressly stated, the term “connection (or link, connection, etc.)” includes the connection (or link, connection, etc.) achieved directly or indirectly.

[0039] In this application, unless otherwise specified, the range of values ​​listed herein is intended to include the endpoints of the range, and all values ​​and all subranges within that range.

[0040] In this application, unless otherwise expressly stated, all figures indicating quantities, percentages, etc., in the specification and claims are to be understood to be modified by the term "about" in all cases.

[0041] This application provides, as follows: Figure 2 The schematically illustrated carbon capture and utilization system for an olefin cracking process, by comprising at least an oxygen supply unit, a combustion heating unit, an olefin cracking unit, a heat exchanger, a CO2 pretreatment unit (not shown), a hydrogen pretreatment unit including a hydrogen separation unit and a pressure boosting unit (not shown), and a CO2 hydrogenation reaction unit, increases the concentration of CO2 in the flue gas by allowing oxygen-enriched combustion, which is beneficial for CO2 capture by a miniaturized device; at the same time, it enables efficient recovery of waste hydrogen byproducts from the olefin cracking reaction, and allows the captured CO2 to be reacted and converted into CO2 hydrogenation products with high added value.

[0042] The carbon capture and utilization system for olefin cracking processes according to this application may include an oxygen supply device, a combustion heating device, an olefin cracking device, a first hydrogen pretreatment device, a heat exchanger, a CO2 pretreatment device, and a CO2 hydrogenation reactor, wherein the heat exchanger may be provided with a first inlet, a second inlet, a first outlet, and a second outlet.

[0043] In such Figure 2 In the carbon capture and utilization system according to this application, the combustion heating device may include a burner for fuel gas combustion and a plurality of heaters for heating the olefin cracking unit by means of a heat-conducting fluid with a suitable high temperature generated by combustion, wherein the outlet provided on the burner is connected to the first inlet of the heat exchanger, and the outlet provided on the heater is connected to the inlet of the olefin cracking unit.

[0044] In the carbon capture and utilization system according to this application, those skilled in the art can select burners and heaters suitable for withstanding and conducting the high temperatures required for the olefin cracking reaction, and configure the combustion heating device as needed. For example, for burners where the temperature needs to be maintained in the range of 700°C to 1200°C, the burner can be in the form of a radiant tube burner or a direct flame burner, and the heater can be in the form of a radiant heater or a convection heater, and configured in a tubular, disc, or plate shape.

[0045] According to the carbon capture and utilization system of this application, refer to Figure 2 The second inlet of the heat exchanger can be connected to the oxygen supply device, and the first outlet of the heat exchanger can be connected to the return inlet of the combustion heating device. In operation, the oxygen produced by the oxygen supply device flows through the heat exchanger into the burner for oxygen-enriched combustion. The high-temperature gas flow generated by combustion passes through the heater to heat the olefin cracking unit. The flue gas products generated by the oxygen-enriched combustion in the burner flow into the heat exchanger for cooling; a portion of this flue gas flows back to the burner to cool it, while the other portion continues to flow through the second outlet into the CO2 pretreatment unit (not in the CO2 pretreatment unit). Figure 2 (as shown in the image).

[0046] According to the carbon capture and utilization system of this application, the CO2 pretreatment device may include a CO2 gas pressurization device and a purification device known in the art. The CO2 passing through the CO2 pretreatment device is pressurized and purified to a pressure suitable for use in a CO2 hydrogenation reactor.

[0047] For example, the CO2 gas purification apparatus according to this application includes, but is not limited to, an adsorption-type CO2 purification apparatus, a membrane separation CO2 purification apparatus, and a chemical absorption CO2 apparatus, etc. The operating method for purifying CO2 using the above-mentioned CO2 gas purification apparatus is known in the art.

[0048] According to the carbon capture and utilization system of this application, for the olefin cracking unit, any conventional reaction unit used for olefin cracking reactions and an optional main-by-product separation unit can be selected as needed. The configuration of the reaction unit and the main-by-product separation unit is known in the art. The olefin cracking unit may be provided with a main product outlet for outputting the main product generated by the cracking reaction and a by-product outlet for outputting the by-product, the by-product outlet being connected to the inlet of the first hydrogen pretreatment unit.

[0049] According to the carbon capture and utilization system of this application, the first hydrogen pretreatment device may include a fluidly connected hydrogen pressure boosting device and a hydrogen separation device to pressurize the byproducts from the olefin cracking unit to an appropriate pressure for easy entry into the hydrogen separation device for hydrogen separation. In some embodiments, particularly where other hydrogen sources besides the hydrogen separation device are available, the system may further include, as needed, an additional fluidly connected hydrogen pressure boosting device and a hydrogen purification device as a second hydrogen pretreatment device to further improve the hydrogen purity before it enters the CO2 hydrogenation reactor.

[0050] For example, the hydrogen separation device according to this application can employ, but is not limited to, pressure swing adsorption (PSA), membrane separation, and any technology suitable for separating hydrogen and light hydrocarbons in byproducts and achieving a hydrogen recovery rate of over 90%, the operation of which is known in the art. The hydrogen pressure boosting device according to this application can employ conventional gas pressurization devices with appropriate parameters.

[0051] According to the carbon capture and utilization system of this application, the CO2 hydrogenation reactor may thus have a CO2 inlet for receiving combustion products from a heat exchanger and a first hydrogen inlet for receiving hydrogen from a first hydrogen pretreatment unit. The CO2 hydrogenation reactor may be configured to have conditions and parameters favorable to the desired hydrogenation reaction between CO2 and hydrogen.

[0052] For example, the types of CO2 hydrogenation reactors according to this application include, but are not limited to, fixed-bed reactors, fluidized-bed reactors, slurry-bed reactors, circulating-bed reactors, multi-stage tubular reactors, loop reactors, and tower reactors. Those skilled in the art can select an appropriate reactor type based on factors such as flow rate and catalyst regeneration cycle.

[0053] In some embodiments, the oxygen supply device in the carbon capture and utilization system according to this application may include a water electrolysis device. In use, the oxygen obtained by water electrolysis is supplied from the oxygen outlet to the heat exchanger as described above.

[0054] In some embodiments, in the carbon capture and utilization system according to this application, the water electrolysis device may further be provided with a hydrogen outlet and the CO2 hydrogenation reactor may be provided with a second hydrogen inlet. The hydrogen outlet of the water electrolysis device may be connected to an additional hydrogen pressure boosting device and a hydrogen purification device in the aforementioned hydrogen pretreatment device. The additional hydrogen purification device may be connected to the second hydrogen inlet of the CO2 hydrogenation reactor, so that the water electrolysis device can further supply hydrogen to the CO2 hydrogenation reactor as a supplement to the hydrogen source other than the hydrogen from the olefin cracking unit.

[0055] In some embodiments, the water electrolysis device in the carbon capture and utilization system according to this application may include, but is not limited to, water electrolysis devices with appropriate energy consumption such as alkaline water electrolyzers and proton exchange membrane electrolyzers.

[0056] In some embodiments, the carbon capture and utilization system according to this application may use renewable energy to supply electricity to the water electrolysis device. The renewable energy source may be selected from wind power, photovoltaic power, hybrid energy, and other energy forms suitable for the application.

[0057] In some embodiments, in the carbon capture and utilization system according to this application, the oxygen supply device may include an air separator for receiving air and separating oxygen therefrom. In use, air enters the air separator, and the separated oxygen is supplied from the oxygen outlet to the heat exchanger as described above.

[0058] In some embodiments, in the carbon capture and utilization system according to this application, the air separation device may perform air separation based on, for example, cryogenic distillation, pressure swing adsorption, membrane separation, cryogenic separation, and any other separation method applicable to this application, as a supplement to an additional source of oxygen besides the oxygen from the water electrolysis device.

[0059] In some embodiments, in the carbon capture and utilization system according to this application, the air separation device may further be provided with a nitrogen outlet, which is connected to an ammonia production system for supplying the separated nitrogen to the ammonia production system. The ammonia production system is a conventional system used in the art for preparing ammonia.

[0060] In some embodiments, when the carbon capture and utilization system according to this application is used on an industrial scale, the outlet of the CO2 hydrogenation reactor may be connected to a CO2 hydrogenation product preparation process system to supply the CO2 hydrogenation product to further processing units and convert it into downstream products required for industrial applications.

[0061] In some embodiments, in the carbon capture and utilization system according to this application, the CO2 hydrogenation product can be methanol. The product preparation process system may include a methanol-to-olefins (MTO) preparation process system and a methanol-to-jet fuel (MTJ) preparation process system.

[0062] Compared to existing technologies, the carbon capture and utilization system of this application applies an oxygen-enriched combustion carbon capture device to a combustion heating device for olefin processes, and recovers by-product waste hydrogen from the cracking process through a hydrogen separation device for reaction with CO2. This achieves efficient utilization of CO2 while reducing dependence on external hydrogen and optimizing energy consumption. Furthermore, the carbon capture and utilization system of this application incorporates a green-electricity-driven water electrolysis device, enabling simultaneous supply of oxygen and hydrogen, thereby enhancing the synergy between the various devices and further improving overall energy efficiency and environmental benefits.

[0063] This application provides a carbon capture and utilization method for olefin cracking processes. This method maintains process stability and significantly improves CO2 capture efficiency by using an oxygen-enriched combustion process and controlling the process temperature. At the same time, it optimizes the utilization of hydrogen and CO2 by introducing hydrogen, a byproduct of olefin cracking processes, into the reaction with CO2 after separation and pressurization.

[0064] The carbon capture and utilization method for olefin cracking processes according to this application may include the following steps: supplying oxygen to a combustion heating device via an oxygen supply device and a heat exchanger; supplying fuel gas to the combustion heating device from the fuel inlet to conduct oxygen-enriched combustion in the presence of oxygen to generate combustion products containing CO2 and water vapor; introducing the combustion products into the heat exchanger to cool and remove water vapor from the combustion products; introducing a portion of the resulting cooled and dehydrated products into the combustion heating device from the first outlet of the heat exchanger via the reflux inlet of the combustion heating device, and introducing another portion into the combustion heating device from the second outlet of the heat exchanger for CO2 pretreatment. The apparatus includes: further treating the introduced CO2 using the CO2 pretreatment unit and supplying it to the CO2 hydrogenation reactor; supplying feed gas from the feed inlet of the combustion heating unit to the combustion heating unit, and under the heat provided by the oxygen-enriched combustion, introducing the feed gas into an olefin cracking unit for olefin cracking reaction to generate olefin cracking products and hydrogen-containing byproducts; introducing the hydrogen-containing byproducts into a first hydrogen pretreatment unit to separate hydrogen from the byproducts and increase the hydrogen pressure, and supplying it to the CO2 hydrogenation reactor; and causing the CO2 supplied to the CO2 hydrogenation reactor to undergo a hydrogenation reaction with hydrogen to generate CO2 hydrogenation products.

[0065] In the carbon capture and utilization method according to this application, the heating mode of the combustion heating device can be achieved by adjusting the operating modes of the burner and heater to adapt to different combustion requirements and heat distribution. The combustion process can be optimized by controlling the fuel gas supply rate, oxygen flow rate, and combustion temperature; the heater can be adjusted according to the required heat conduction method, for example, conventional radiant heating, convection heating, and heating methods that ensure uniform heat transfer to the pyrolysis reaction process and maintain the safe operation of the equipment can be adopted.

[0066] In the carbon capture and utilization method according to this application, the amount of CO2 and oxygen transported back to the combustion heating device via the return pipeline can be adjusted according to the temperature requirements of the combustion heating device. The temperature of the combustion heating device can be monitored by conventional temperature control devices in the art, and maintained within a predetermined operating temperature range by adjusting the proportion of return gas, so as to avoid affecting equipment performance or combustion efficiency due to excessively rapid temperature rise caused by oxygen-enriched combustion.

[0067] In the carbon capture and utilization method according to this application, the pretreatment using the CO2 pretreatment device may include steps of pressurizing and purifying the CO2 to ensure that the treated gas is readily accessible to the purification device and meets the pressure and purity levels required for subsequent hydrogenation reactions. The techniques used in the pressurization and purification steps are conventional in the art for gas compression and purification processes. For example, the purification step may employ conventional physical adsorption or membrane separation techniques. Those skilled in the art can adjust the parameters in the above steps, such as the type of adsorbent and membrane parameters, temperature, and pressure, according to actual operational needs and the types of impurities to be removed.

[0068] In the carbon capture and utilization method according to this application, several parameters of the olefin cracking reaction can be selected according to the specific reaction and product requirements. These parameters include reaction temperature, pressure, reaction residence time, feed composition, and dilution gas addition ratio, and can be set using conventional control devices to optimize the yield of the resulting olefin main product. Furthermore, by controlling the temperature and pressure, and configuring additional separation devices for separating the olefin main product, the effective separation of olefin products and by-products can be promoted according to the specific requirements of the cracking process.

[0069] The carbon capture and utilization method according to this application includes a hydrogen pretreatment process. The pretreatment process may include operations to bring the hydrogen to a pressure suitable for entry into a subsequent separation unit and a hydrogen separation process to separate hydrogen from olefin cracking reaction byproducts via the separation unit. In some embodiments, the pretreatment process may further include processes for increasing the pressure and purifying hydrogen from other sources. The pressure facilitating purification and subsequent CO2 hydrogenation reactions can be adjusted according to the size and operating requirements of the separation unit and the CO2 hydrogenation reactor.

[0070] In the carbon capture and utilization method according to this application, the hydrogen separation process described above can extract hydrogen from the byproducts using pressure swing adsorption, membrane separation, or other conventional separation techniques. The operating pressure of the separation equipment and the cycle times for adsorption and desorption can be adjusted according to operational requirements to ensure a hydrogen recovery rate greater than 90%. The operation of the above separation process is known in the art.

[0071] In the carbon capture and utilization method according to this application, the conditions of the CO2 hydrogenation reaction occurring in the CO2 hydrogenation reactor can be adjusted according to the specific reaction requirements. Specifically, any other factors affecting the type, selectivity, and yield of the reaction products, such as the CO2 to hydrogen feed ratio and rate, catalyst type, reaction temperature, and pressure, can be adjusted and optimized by those skilled in the art using techniques known in the art. In some embodiments, the CO2 hydrogenation product can be methanol.

[0072] In some embodiments, in the carbon capture and utilization method according to this application, a water electrolysis device can be used as the oxygen supply device; at the same time, if necessary, the hydrogen generated by the water electrolysis device can be pretreated and supplied to the CO2 hydrogenation reactor as a supplement to the hydrogen source other than the hydrogen from the olefin cracking unit, thereby improving the utilization rate of CO2 and the yield of CO2 hydrogenation products.

[0073] In some embodiments, the carbon capture and utilization method according to this application may further include supplying electricity to the water electrolysis device using renewable energy. The renewable energy source may include wind power, photovoltaic power, hybrid energy supply, and other suitable forms of power supply as claimed.

[0074] In some embodiments, in the carbon capture and utilization method according to this application, the electrical energy supplied by the renewable energy source is used in other processes according to this application. For example, the electrical energy supplied by the renewable energy source can be used in the olefin cracking process, hydrogen pressurization process, hydrogen separation process, CO2 pretreatment process, CO2 hydrogenation reaction process, and any energy-consuming process involved in the method according to this application.

[0075] In some embodiments, in the carbon capture and utilization method according to this application, an air separation device for receiving air and separating oxygen therefrom can be used as the oxygen supply device, as a supplement to the oxygen source other than the oxygen from the water electrolysis device, to promote oxygen-enriched combustion and thereby improve the heating efficiency for the olefin cracking reaction.

[0076] In some embodiments, when the carbon capture and utilization method according to this application is applied on an industrial scale, the residual nitrogen generated by the air separation unit can be supplied to an ammonia production system for ammonia production. The hydrogen supplied to the ammonia production system can be from an external hydrogen source. In some embodiments, the hydrogen can be from the water electrolysis unit used in the method according to this application. The techniques and procedures for ammonia production are known in the art.

[0077] In some embodiments, the carbon capture and utilization method according to this application may further include introducing the CO2 hydrogenation product into a CO2 hydrogenation product preparation process system to further convert the CO2 hydrogenation product into a downstream reaction product of the CO2 hydrogenation product. In some embodiments, the CO2 hydrogenation product may be methanol, and the processing technology performed in the CO2 hydrogenation product preparation process system may include a methanol-to-olefins (MTO) process and a methanol-to-jet fuel (MTJ) process.

[0078] In some embodiments, the carbon capture and utilization method according to this application may further include a temperature control step. The temperature control step includes controlling the flow rate of fuel gas supplied to the combustion heating device to maintain the combustion heating device in the range of 700°C to 1200°C; and controlling the flow rate of cooling dehydration products introduced into the combustion heating device from the first outlet of the heat exchanger via the return inlet of the combustion heating device to reduce the flame temperature of the heater according to the invention. It should be understood that the amount of fuel gas working fluid introduced determines the heat generated by the combustion heating, which can then be used to regulate the temperature of the combustion heating device. The gas entering the combustion heating device through the heat exchanger may contain cooled CO2 and oxygen from the oxygen supply device; therefore, the return gas has a significantly lower temperature compared to the CO2 and water vapor entering the heat exchanger, and by increasing the volume percentage of CO2 in the gas to be introduced into the combustion heating device, the oxygen-enriched combustion flame temperature can be appropriately reduced, preventing damage to the combustion heating device components or the need for higher-grade materials due to high temperatures, while simultaneously ensuring the required combustion efficiency.

[0079] In the carbon capture and utilization method according to this application, the feed and discharge flow rates of the devices involved in each step can be adjusted using conventional flow control equipment to achieve the required reaction and the aforementioned temperature regulation steps, and to ensure stable operation of each step. For example, the oxygen flow rate supplied by the oxygen supply device can be precisely controlled according to the combustion demand in the combustion heating device, and its fuel gas supply can be matched to provide the combustion heating reaction and efficiency required in the olefin cracking process.

[0080] In practice, after an olefin cracking unit has been operating for a period of time, a decoking process is usually performed during the intervals between olefin cracking operations to address issues such as shortened unit life and reduced yield caused by coking. (Continue to refer to...) Figure 2 At this time, the olefin cracking unit should be regarded as a decoking unit and no feed for the olefin cracking process should be carried out. The oxygen supply unit, combustion heating unit, decoking unit, heat exchanger and CO2 pretreatment unit (not shown) according to this application can be used and the CO2 generated in the decoking process can be captured in accordance with the steps of CO2 capture in the carbon capture and utilization method according to this application.

[0081] Compared with existing technologies, the carbon capture and utilization method of this application applies oxygen-enriched combustion technology to the olefin cracking process, significantly reducing flue gas volume and almost eliminating nitrogen oxide content, thereby reducing the difficulty of capturing CO2 generated from heating in the olefin cracking process. Simultaneously, the efficient recovery of waste hydrogen, a byproduct of the cracking process, reduces the demand for external hydrogen; this recovered hydrogen is then hydrogenated with CO2 to generate high-value-added products, including methanol, achieving effective reuse of both CO2 and hydrogen. Furthermore, the method of this application uses green electricity, particularly for water electrolysis devices that simultaneously provide oxygen and hydrogen, further reducing carbon emissions. Additionally, the method of this application recirculates a portion of the CO2 to regulate the combustion temperature, preventing equipment overheating, extending equipment life, and improving combustion efficiency.

[0082] Example

[0083] The following will further illustrate the concept, specific structure, and technical effects of the present invention with reference to embodiments, so that those skilled in the art can fully understand the purpose, features, and effects of the present invention. Those skilled in the art will understand that the embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0084] Example 1

[0085] Example 1 relates to a laboratory-scale capture and utilization of byproduct hydrogen and CO2 generated in a propane dehydrogenation process. (Reference) Figure 2 An alkaline electrolyzer powered by renewable energy is used as the oxygen supply device. This alkaline electrolyzer obtains oxygen with a purity of approximately 99% through water electrolysis and discharges the oxygen at a concentration of approximately 9 Nm³. 3 A flow rate of / h is supplied to the heat exchanger.

[0086] To supplement the oxygen supply to the aforementioned electrolyzer, an air separation device based on vacuum pressure swing adsorption technology is used to separate oxygen from nitrogen in the air. The generated oxygen with a purity of approximately 93% is then discharged at approximately 6 Nm. 3Oxygen from both the electrolyzer and air separator is supplied to the heat exchanger at a flow rate of approximately 15 Nm³ / h. 3 A flow rate of / h is supplied to the combustion heating unit.

[0087] The core components of the combustion heating device used in this embodiment include a propane dehydrogenation heater and a UOP Kellert propane dehydrogenation oxygen-enriched burner. The heater is used to heat the feed gas for the propane dehydrogenation process to the required reaction temperature; its temperature is set at 800°C and its pressure at -100 PaG. Natural gas is selected as the fuel gas used in this embodiment, with a concentration of 6 Nm³. 3 A flow rate of [amount] N / h enters the burner through a fuel inlet, and the furnace temperature is controlled by adjusting the natural gas flow rate. The oxygen from the heat exchanger is mixed with the fuel gas and approximately 20% of the circulating flue gas for oxygen-enriched combustion in the burner. The oxygen content in the furnace is controlled at approximately 3% by adjusting the flow rate of the combustion-supporting oxygen. The amount of flue gas produced by combustion is approximately 25 Nm³. 3 / h.

[0088] Propane, as the feedstock, is fed into a heating furnace at a flow rate of 112.5 kg / h and heated to a reaction temperature of 600°C to 650°C before entering a cracking reactor comprising four moving bed reactors connected in series. The inlet pressure of the cracking reactor is set at 0.23 MPaG, and the outlet pressure is set at 3.5 kPaG. Under these conditions, the feedstock gas undergoes a cracking reaction in the presence of a Pt / Al₂O₃ catalyst to produce propylene and hydrogen, which are then cooled, separated, and purified to obtain propylene. The yield of propylene is approximately 88%.

[0089] Following the aforementioned pyrolysis reaction, based on the total volume of the pyrolysis reactor tail gas, tail gas from the pyrolysis reactor containing approximately 92.5% by volume hydrogen is introduced into the UOP Polybed. TM Pressure Swing Adsorption (PSA) device. This device mainly consists of an adsorption tower filled with UOP H102 adsorbent, related valve assemblies, and a controller. At room temperature, the tail gas is first pressurized to 2.5 MPaG, and then the PSA device generates hydrogen with a purity ≥99.9%, with a hydrogen recovery rate of approximately 91%.

[0090] The high-temperature flue gas from the combustion products of oxygen-enriched combustion further flows from the heater into the aforementioned heat exchanger to remove water vapor and cool the combustion products to room temperature, yielding a gas containing >95% by volume of CO2 based on the total volume of the cooling gas, along with the remainder being impurities. The flow rates of oxygen and CO2 in the mixed gas flowing through the heat exchanger are adjusted so that the mixed gas contains only about 5% to 20% by volume of oxygen based on the total volume of the mixed gas. This mixed gas is then returned to the burner to reduce the oxygen concentration in the mixed gas in the burner and heater, thereby suppressing excessively high combustion temperatures and minimizing the formation of nitrogen oxides (air leakage in the heater inevitably leads to a small amount of N2 entering). The remaining CO2 is pressurized to 3.5 MPaG and introduced into a CO2 purification unit to remove impurities such as SO2, thereby increasing the purity of the CO2 to >99%.

[0091] To meet the hydrogen demand of the CO2 hydrogenation reaction, additional hydrogen is provided by water electrolysis in the aforementioned alkaline electrolyzer. The generated hydrogen, along with the hydrogen from the pressure swing adsorption unit, is first pressurized to 2.4 MPaG, and then passed through a separate hydrogen purification unit to further remove impurities. The resulting hydrogen with a purity >99.9% is fed into the CO2 hydrogenation reactor at a flow rate of 3.9 kg / h and mixed with CO2 from the aforementioned CO2 purification unit. The hydrogenation reactor is filled with a Cu-Zn-based catalyst and set to a reaction temperature of 267°C and a pressure of 5.5 MPa, with a flow rate of 10000 ml / g. -1 ·h -1 The space velocity (GHSV) is increased so that CO2 and hydrogen react primarily on the catalyst surface to produce methanol.

[0092] After flash evaporation and distillation, refined methanol is obtained. In this CO2 hydrogenation reaction, the hydrogen conversion rate is approximately 91.5%, the selectivity is approximately 91.2%, and the methanol yield is approximately 83.1%.

[0093] After the CO2 hydrogenation to methanol process is completed, the generated methanol is introduced into downstream process systems. The downstream process systems involved, namely the methanol-to-olefins (MTO) production system and the methanol-to-jet fuel (MTJ) production system, are existing and mature technologies.

[0094] Comparative Example 1

[0095] Comparative Example 1 involves a propane dehydrogenation process using conventional air combustion technology. (Reference) Figure 1 Air (based on a total air volume containing approximately 21% oxygen) is transported at approximately 72 Nm 3A flow rate of / h is introduced into the combustion heating device. The combustion heating device used is similar to that used in Example 1, and its core components include a propane dehydrogenation heater and a UOP Kellert CUBL-LFM propane dehydrogenation burner. The heater is used to heat the feed gas for the propane dehydrogenation process to the required reaction temperature; its furnace temperature is set at 800°C, and its pressure is set at -100 PaG. Natural gas is selected as the fuel gas, with a flow rate of 6 Nm³. 3 The furnace temperature is controlled by adjusting the natural gas flow rate. The oxygen content in the furnace is maintained at approximately 3% by adjusting the combustion air flow rate.

[0096] Propane was fed into a furnace at a flow rate of 112.5 kg / h and heated to a reaction temperature of 600°C to 650°C before entering four moving bed reactors connected in series. The reactor inlet pressure was set at 0.23 MPaG, and the reactor outlet pressure was set at 3.5 kPaG. Under these conditions, the feed gas underwent a cracking reaction in the presence of a Pt / Al₂O₃ catalyst to produce propylene and hydrogen. Propylene was then obtained after cooling, separation, and purification. The yield of propylene was approximately 88%.

[0097] The high-temperature flue gas flow rate produced after air combustion is 78 Nm. 3 / h. Relative to the total volume of air combustion products, the air combustion products contain approximately 10% by volume CO2, approximately 18% by volume water, approximately 70% by volume N2 and other trace amounts of impurity gases, including <50 ppm of nitrogen oxides.

[0098] Compared to the comparative example using conventional air combustion technology, the embodiments of this application, by employing oxygen-enriched combustion technology, significantly increase the CO2 concentration in the flue gas by approximately seven times, while reducing the flue gas volume after combustion to approximately 32% of the comparative example, thereby substantially reducing the difficulty and energy consumption of carbon capture. Simultaneously, the combustion efficiency of the embodiments of this application is not reduced, and the propylene yield from the propane dehydrogenation reaction remains stable regardless of oxygen supply. Furthermore, the embodiments of this application utilize pressure swing adsorption (PSA) technology to recover hydrogen, a byproduct of olefin cracking, with a recovery rate of approximately 91%, significantly reducing the demand for external hydrogen, further improving resource utilization and reducing environmental impact.

Claims

1. A carbon capture and utilization system for an olefin cracking process, comprising an olefin cracking unit, a combustion heating unit, a heat exchanger, an oxygen supply unit, and a CO2 pretreatment unit in fluid communication, wherein the heat exchanger is provided with a first inlet, a second inlet, a first outlet, and a second outlet; the first inlet is connected to the outlet of the combustion heating unit; the second inlet is connected to the oxygen outlet of the oxygen supply unit; the first outlet is connected to the reflux inlet of the combustion heating unit; the first outlet is connected to the reflux inlet of the combustion heating unit; and the second outlet is connected to the inlet of the CO2 pretreatment unit, characterized in that... The carbon capture and utilization system includes: A first hydrogen pretreatment unit, used to separate hydrogen from the byproducts of the olefin cracking unit and to increase the hydrogen pressure, wherein the inlet of the first hydrogen pretreatment unit is connected to the outlet of the olefin cracking unit; and A CO2 hydrogenation reactor is provided for receiving pretreated CO2 and hydrogen. The CO2 hydrogenation reactor is provided with a CO2 inlet and a first hydrogen inlet. The CO2 inlet is connected to the outlet of the CO2 pretreatment device, and the first hydrogen inlet is connected to the outlet of the first hydrogen pretreatment device.

2. The carbon capture and utilization system according to claim 1, wherein the oxygen supply device includes a water electrolysis device for supplying hydrogen to the CO2 hydrogenation reactor, the water electrolysis device is further provided with a hydrogen outlet and the CO2 hydrogenation reactor is provided with a second hydrogen inlet, and the hydrogen outlet of the water electrolysis device is connected to the second hydrogen inlet of the CO2 hydrogenation reactor through a second hydrogen pretreatment device.

3. The carbon capture and utilization system according to claim 2, wherein renewable energy is used to supply electricity to the water electrolysis device.

4. The carbon capture and utilization system according to claim 1, wherein the oxygen supply device includes an air separation device for receiving air and separating oxygen therefrom.

5. The carbon capture and utilization system according to claim 4, wherein the air separation device is further provided with a nitrogen outlet, and the nitrogen outlet is connected to the ammonia production system.

6. The carbon capture and utilization system according to claim 1, wherein the outlet of the CO2 hydrogenation reactor is connected to the CO2 hydrogenation product preparation process system.

7. A method for carbon capture and utilization in olefin cracking processes, characterized in that, The carbon capture and utilization method includes the following steps: Oxygen is supplied to the combustion heating device through a heat exchanger via an oxygen supply device. Fuel gas is supplied from the fuel inlet of the combustion heating device to the combustion heating device for oxygen-enriched combustion in the presence of oxygen, generating combustion products containing CO2 and water vapor; The combustion products are introduced into the heat exchanger to cool and remove water vapor from the combustion products. A portion of the resulting cooled and dehydrated products is introduced into the combustion heating device from the first outlet of the heat exchanger through the reflux inlet of the combustion heating device, and another portion is introduced into the CO2 pretreatment device from the second outlet of the heat exchanger. The introduced CO2 is further processed using the CO2 pretreatment device and supplied to the CO2 hydrogenation reactor; Raw material gas is supplied from the raw material inlet of the combustion heating device to the combustion heating device. Under the heat provided by the oxygen-enriched combustion, the raw material gas is introduced into the olefin cracking device and undergoes an olefin cracking reaction to generate olefin cracking products and hydrogen-containing byproducts. The hydrogen-containing byproduct is introduced into a first hydrogen pretreatment unit to separate hydrogen from the byproduct and increase the hydrogen pressure, and the resulting hydrogen is supplied to the CO2 hydrogenation reactor; and The CO2 supplied to the CO2 hydrogenation reactor undergoes a hydrogenation reaction with hydrogen to generate CO2 hydrogenation products.

8. The carbon capture and utilization method according to claim 7, wherein a water electrolysis device is used as the oxygen supply device, and the hydrogen generated by the water electrolysis device is processed by a second hydrogen pretreatment device and then supplied to the CO2 hydrogenation reactor.

9. The carbon capture and utilization method according to claim 8, further comprising the following steps: The water electrolysis device is supplied with electricity using renewable energy sources, and the electricity is used in the other processes described in claim 7.

10. The carbon capture and utilization method according to claim 7, wherein an air separation device for receiving air and separating oxygen therefrom is used as the oxygen supply device, and the residual nitrogen generated by the air separation device is supplied to an ammonia production system for the production of ammonia.

11. The carbon capture and utilization method according to claim 7, further comprising the following steps: The CO2 hydrogenation product is introduced into the CO2 hydrogenation product preparation process system to further convert the CO2 hydrogenation product into the downstream reaction product of the CO2 hydrogenation product.

12. The carbon capture and utilization method according to claim 7, further comprising the following temperature control step: Controlling the flow rate of fuel gas supplied to the combustion heating device to maintain the combustion heating device within the range of 700°C to 1200°C; and The flow rate of the cooling and dehydration products introduced into the combustion heating device from the first outlet of the heat exchanger through the return inlet of the combustion heating device is controlled to reduce the flame temperature of the combustion heating device.

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