Compression of pyrolysis gas products using CO2 loop

Abstract

Methods, systems and apparatus for producing compressed process gases containing light olefins such as ethylene are provided. The method utilizes a pyrolysis reactor to produce the process gas. A generator uses a turbine operating on an Allam cycle to generate shaft power for operating one or more compressors involved in the processing of the process gas while generating a reduced or minimal amount of CO2 released as a low-pressure gas phase product. Examples of processing the process gas using shaft power can include compressing the process gas by a process gas compressor powered by the generated shaft power, and cooling the process gas using a refrigeration compressor powered by the generated shaft power.

Description

[0001] priority

[0002] This application claims priority to and the benefit of U.S. Provisional Application No. 62 / 954,775, filed on December 30, 2019, and European Patent Application No. 20168288.7, filed on April 6, 2020, the disclosures of which are incorporated herein by reference in their entireties. Technical Field

[0003] The present invention relates to pyrolysis product compression using shaft power generated in a generator while reducing or minimizing exhaust emissions such as CO2. The present invention also relates to methods, systems and apparatus for performing pyrolysis, power generation and compression. Background Art

[0004] Olefinic compounds are a class of hydrocarbon compounds having at least one double bond containing four shared electrons between two carbon atoms. Owing in part to their use as feedstocks for the production of desired products, the demand for olefins continues to grow, particularly for light olefins such as ethylene, propylene and butenes.

[0005] Light olefins are usually manufactured in olefin units (e.g., ethylene units) that include production and recovery facilities. In some conventional olefin units, the olefin production facility includes one or more steam cracking furnaces for steam cracking hydrocarbonaceous feeds. The steam cracking furnace generally includes a convection section and a radiant section. The radiant section includes a plurality of tubular members commonly referred to as "radiant tubes." The radiant tube is located near one or more combustion heaters (e.g., burners) in the radiant section, which heat the outer surface of the furnace tube. The hot combustion gas leaves the radiant section and is introduced into the convection section. The convection section also includes a tubular member, commonly referred to as a "convection tube." The hot gas from the radiant section heats the outer surface of the convection tube and then leaves the convection section.

[0006] Conventional steam cracking methods usually produce light olefins by pyrolysis of hydrocarbons during pyrolysis mode. Coke and other deposits formed during pyrolysis mode are removed from the furnace interior during regeneration (decoking) mode. During pyrolysis mode, hydrocarbon-containing feed is introduced into a convection tube for feed preheating. Feed preheating is carried out in a convection tube section located in the upper region of the convection section. Steam is combined with the preheated feed, and the steam-feed mixture is further heated in a convection tube section located in the lower region of the convection section. The heated feed-steam mixture is introduced into the heated furnace tube in the radiant section, and the heat transferred from the furnace tube to the mixture causes at least a portion of the feed to be pyrolyzed to produce a process gas containing light olefins. During regeneration mode, the hydrocarbon-containing feed is replaced by a stream of a decoking fluid (e.g., a gaseous steam-air mixture) containing oxygenates, and the burner continues to heat the radiant section and the convection section. The decoking fluid is directed through the heated convection tubes, heated radiant tubes and associated furnace piping, internals, etc. to at least partially remove the deposited coke. After sufficient coke removal is achieved, the steam cracking furnace is returned to pyrolysis mode operation.

[0007] In certain steam cracking processes, such as those disclosed in U.S. Patent Application Publication No. 2007-0261991, process gases are cooled by transferring heat from the process gases to water indirectly in one or more transfer line heat exchangers ("TLE"). Saturated steam from the TLE is directed to a steam drum. Condensed water in the steam drum is circulated to the TLE, typically via thermosyphon. Saturated steam can be taken away from the steam drum to process equipment located in an olefin unit and elsewhere, with condensed water replenishment obtained from a suitable source. For example, saturated steam can be taken away from the steam drum to be superheated in one or more superheater tubes located between sections of a convection coil.

[0008] In order to reduce the difficulties associated with separating products such as ethylene from the process gas, the cooled process gas is usually compressed in a process gas compressor located in the recovery facility of the olefin plant. U.S. Patent Application Publication No. 2008-0210598 discloses using shaft power from a steam turbine to power the process gas compressor. Superheated steam leaving the superheater coils of the convection section is used as a steam source for the steam turbine.

[0009] Although this approach is effective for providing power to the process gas compressor, the thermal efficiency of the steam cracking furnace is reduced because additional furnace firing is required to superheat the saturated steam, e.g., beyond the furnace firing required to produce the process gas. Another difficulty encountered when implementing the method is due to the variations in temperature and pressure of the superheated steam that typically occur during steam cracking. As a result of effects such as radiant tube coking, the amount of furnace firing required to produce process gas is greater at the end of the steam cracking process than at its beginning. As disclosed in PCT Patent Application No. WO2010-077461, water can be introduced into the superheater coils to at least partially overcome this difficulty by de-superheating the steam. The amount of water supplied to the de-superheater is controlled to prevent damage to the steam turbine. However, this benefit is obtained due to the further loss of thermal efficiency of the furnace caused by the additional furnace firing required to evaporate the de-superheater water.

[0010] Because process gases from multiple steam cracking furnaces are typically combined upstream of a process gas compressor, another difficulty arises when one or more furnaces are unexpectedly taken offline, such as by reducing or stopping the amount of furnace firing. Because reducing steam turbine shaft power can damage the process gas compressor, commercial steam cracking facilities typically include additional steam generators that continuously produce additional superheated steam. When a furnace is unexpectedly taken offline, the additional superheated steam replaces the superheated steam of the steam cracking furnace. Although reducing the risk of compressor damage, the additional steam generators further reduce the thermal efficiency of the olefin unit.

[0011] Another operational difficulty arises from the coupling (via superheated steam) of the steam cracking furnace of the olefin production facility and the olefin recovery facility. Because these facilities are coupled, modifications to the steam cracking furnace (e.g., to increase the amount of process gas produced by the furnace) are made more difficult by the corresponding need to modify the steam-driven power cycle in the recovery facility.

[0012] In order to at least partially overcome these difficulties, proposals have been made to obtain power for the process gas compressor from a power source external to the olefin production facility (e.g., from a gas turbine that provides power to a generator, which in turn provides power to an electric motor that provides shaft power to the process gas compressor). However, it is reported that it is not feasible to directly drive the process gas compressor using the shaft power generated by a "stand-alone" gas turbine, for example, the maintenance schedule of the gas turbine is shorter than that of a typical steam cracking furnace. The low thermal efficiency of a typical gas turbine also results in a reduced overall thermal efficiency of the olefin plant.

[0013]

[0006] Therefore, there is a need for more thermally efficient olefin production plants, particularly those that decouple the production and recovery facilities of the plant.

[0014] U.S. Patent Application Publication 2019 / 0169510 describes systems and methods for decoupling the production and recovery facilities of an olefin plant.

[0015] A closed loop cycle, sometimes referred to as the "Allam cycle," for powering a turbine using CO2 as a working fluid is described in U.S. Patent Application Publications 2012 / 0067056 and 2017 / 0058712. The Allam cycle is described as providing electricity via natural gas fuel with reduced CO2 emissions.

[0016] Modern olefin production units consume a large amount of shaft power to drive various compressors and pumps. It is highly desirable to improve energy efficiency in the power production of the device. For example, the process gas compressor discussed in the previous paragraph may be very large, thereby requiring a large amount of shaft power to drive. In addition, the compressor used in the refrigeration unit in the olefin production unit also can consume a large amount of shaft power.

[0017] From the product recovery section of a typical steam cracker olefin production unit, a large amount of "tail gas" containing methane and optional hydrogen is usually produced. The tail gas is usually burned as a fuel to provide energy, producing CO2 and water in the process. It is highly desirable that the energy released from the combustion of the tail gas can be used to provide power for the process steps in the olefin production unit, the CO2 produced can be concentrated, captured, stored and / or utilized, and the water produced can be used in an efficient manner. However, there are major challenges in achieving one, not to mention two or all of these goals.

[0018] The olefin production unit comprising steam cracker is ideally located near the user (for example polyethylene and / or polypropylene production facility) of olefin products, so that the transportation of olefins is minimized.For being positioned near the hydrocarbon feed source and away from the olefin production unit of user, it may be highly desirable that one or more conversions in the olefin products be more easily transported in the conversion unit of the olefin production unit adjacent to the olefin production unit.It will be highly desirable that the operation of the steam cracker and the recovery section in the olefin production unit, conversion unit and power production unit (if any, comprising tail gas combustion) is integrated to provide a high level of energy efficiency.

[0019] The present disclosure satisfies this need and other needs. Summary of the invention

[0020] The present invention is based in part on the integration of an effluent processing equipment group (train) for a pyrolysis reactor with a turbine operating based on the Allam cycle. The turbine can be used to provide shaft power for process gas compressors, refrigeration compressors and / or other parts of the effluent processing equipment group. By using a separate turbine operating based on the Allam cycle to provide power for one or more parts of the effluent processing equipment group, the operation of the processing equipment group can be decoupled from the operation of the pyrolysis reactor, while also reducing or minimizing the emission of CO2 and / or other greenhouse gases. This may be beneficial, for example, in a configuration in which multiple pyrolysis reactors are used to jointly supply fewer multiple effluent processing equipment groups. By providing an independent power source for the effluent processing equipment group, the efficiency of the entire system can be maintained when one or more of the pyrolysis reactors are offline. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Conceptual illustration of the heat transfer that may occur in a regenerative countercurrent pyrolysis reactor during regeneration mode (top) and pyrolysis mode (bottom).

[0023] Figure 2 A representative countercurrent pyrolysis reactor format is schematically shown.

[0024] Figure 3 Schematically shows Figure 2 Representative bulk gas temperature curves at the beginning (solid line) and end (dashed line) of the pyrolysis mode of the reactor.

[0025] Figure 4 Certain aspects of the invention are schematically illustrated wherein a process gas derived from hydrocarbon pyrolysis product production is compressed in a process gas compressor.

[0026] Figure 5 An example of a power generation system suitable for operating a turbine based on the Allam cycle is shown.

[0027] Figure 6 A Mollier diagram for operating a single turbine and a single combustor based on the Allam cycle is shown. DETAILED DESCRIPTION OF THE INVENTION

[0029] Overview

[0030] Certain aspects of the present invention relate to providing methods, systems and apparatus for producing compressed process gases containing light olefins such as ethylene. The methods utilize a pyrolysis reactor, such as a tubular flow-through reactor, to produce a process gas. The generator uses a turbine operating on an Allam cycle to generate shaft power for operating one or more compressors involved in the processing of the process gas while producing a reduced or minimal amount of CO2 released as a low-pressure gas phase product. Examples of processing the process gas using shaft power can include compressing the process gas by a process gas compressor powered by the generated shaft power, and cooling the process gas using a refrigeration compressor powered by the generated shaft power.

[0031] Using a turbine operating on the Allam cycle to power a process gas compressor can provide various advantages. Traditionally, many pyrolysis reactors use steam generated as a byproduct of the pyrolysis process to power a turbine, which then powers the process gas compressor. While this can be effective, this couples the operation of the process gas compressor to the pyrolysis process. Using a separate turbine to power the process gas compressor allows the process gas compressor to operate independently of the pyrolysis process.

[0032] A difficulty with using a separate turbine to power the process gas compressor is the potential increase in greenhouse gas and other atmospheric emissions from operating a separate fuel combustion process. Potential emissions from using a separate turbine may include CO2, NO x 、SO x , NH3 and particulate matter. In various aspects, this difficulty is reduced or minimized by using a turbine based on the Allam cycle operation. In the Allam cycle, the combustion process that provides energy for the turbine also supplies CO2 used as a working fluid. CO2 is maintained at a sufficient temperature and pressure during the cycle so that CO2 remains essentially in a supercritical state and therefore no phase change occurs. This reduces or minimizes energy losses due to evaporation or condensation of the working fluid. In addition, when new CO2 is produced, a portion of the existing compressed CO2 in the working fluid can be removed. If a purer oxygen stream is used as an oxidant for combustion, the resulting removed CO2 can also have a high purity. This can allow the removed CO2 to be suitable for storage or other uses without having to separate the removed CO2 to remove nitrogen. In addition, using a purer oxygen stream to minimize or eliminate nitrogen from flue gas can also reduce, minimize or eliminate NO x emissions (and possibly NO xThe use of a turbine operating on the Allam cycle can therefore provide independent operation of the process gas compressor whilst also reducing or minimising the amount of CO2 emitted to the atmosphere or requiring capture in a separate post-processing step.

[0033] In addition, certain features of the regenerative countercurrent pyrolysis reactor make this form of reactor particularly suitable for producing process gases. Unlike steam cracking furnaces, heat is recovered in the countercurrent pyrolysis reactor, and the recovered heat is stored by the reactor assembly during the regeneration mode and the pyrolysis mode operation. The heat recovered and stored in the reactor during the pyrolysis mode can be used for subsequent heat transfer to the process stream during the regeneration mode, for example, for heat transfer to the fuel and / or air. This transfer reduces the heat that would otherwise need to be supplied to the reactor during the regeneration mode, as in the case of a steam cracking furnace operating in the regeneration mode. The heat recovered and stored in the reactor during the regeneration mode can be used for heat transfer during the subsequent pyrolysis mode, which reduces or completely eliminates the need for furnace heating during the pyrolysis mode operation. Transferring heat from the reactor to the fuel and / or air during the combustion mode will cool the region of the reactor for quenching the pyrolysis products during the pyrolysis mode. This reactor cooling advantageously reduces or completely eliminates the need for external quenching (e.g., in one or more TLEs) of the pyrolysis products. Because TLE is generally not required when utilizing a regenerative countercurrent pyrolysis reactor, the generator and pyrolysis reactor can be substantially energy independent. An energy independent generator is desirable because it at least partially overcomes the difficulties associated with increasing or decreasing compressor power requirements in response to, for example, unexpected reactor shutdowns, increases or decreases in process gas production rates, etc. Reference will now be made to Figure 1 Certain desirable features of a regenerative countercurrent pyrolysis reactor are set forth in greater detail.

[0034] Conceptually, the regenerative countercurrent pyrolysis reactor 101 includes a first heat transfer zone 102 and a second heat transfer zone 103, a pyrolysis zone 104, and a combustion zone 105. These zones are in a state of being ... Figure 1Schematically shown in . The figure is conceptual because, for example, the pyrolysis zone and the combustion zone can occupy substantially the same (or overlapping) physical space within the reactor, although at different times. The method for establishing initial conditions in these zones at the beginning of operation is not critical. For example, if the reactor starts in pyrolysis mode, conventional methods can be used to preheat the first heat transfer zone of the reactor and precool the second heat transfer zone, but the present invention is not limited to this. During the pyrolysis mode, it operates with forward flow (basically from right to left as shown in the figure), and heat is transferred from the reactor to the feed in the first heat transfer zone. Sufficient heat is transferred in the first heat transfer zone to pyrolyze the heated feed in the pyrolysis zone. The pyrolysis products are cooled by heat transfer from the pyrolysis effluent to the reactor in the second heat transfer zone, which quickly quenches the pyrolysis products. Condensable components that may be present in the pyrolysis products are usually deposited in the second heat transfer zone. As shown in the figure, the process gas that usually contains the rest of the pyrolysis products is taken away via pipeline 49. A useful feature of a regenerative countercurrent thermal pyrolysis reactor is that at least a portion of the heat removed from the pyrolysis products during quenching (less any radiation, conduction and convection losses) is stored in the second heat transfer zone of the reactor and is available for transfer during regeneration mode operation. Another useful feature is that at least a portion of the heat removed from the combustion effluent during quenching (again, less any radiation, conduction and convection losses) is stored in the first heat transfer zone of the reactor and is available for transfer during pyrolysis mode operation. These features are Figure 1 It is schematically shown in FIG.

[0035] During the regeneration mode in countercurrent (e.g., substantially from left to right as shown), oxidant and fuel are introduced into the reactor via line 19, which typically includes substantially separate fuel and oxidant channels. The fuel and oxidant are transported toward the combustion zone through the second heat transfer zone. Sufficient heat is transferred from the reactor in the second heat transfer zone to the fuel and air to cause them to burn in the combustion zone. Heat is transferred from the combustion effluent to the reactor first heat transfer zone. Thus, the first heat transfer zone and the second heat transfer zone are regenerated for a subsequent forward flow pyrolysis interval.

[0036] The fuel and oxidant do not need to be heated in the second heat transfer zone for combustion. Other (unheated) components may be introduced into the combustion zone via one or more bypass lines (not shown). Typically, at least the oxidant is heated in the second heat transfer zone during the combustion mode to oxidize and remove at least a portion of any combustible deposits remaining from the previous pyrolysis mode interval, and also to mechanically ablate and remove at least a portion of any remaining incombustible deposits. More typically, during the combustion mode, both the fuel and oxidant are delivered through the second heat transfer zone, typically via different passages, to prevent pre-ignition upstream of the combustion zone.

[0037] In other aspects, other types of pyrolysis reactors can be used.For example, the pyrolysis reactor can correspond to a conventional steam cracking configuration, where the feed passes through pyrolysis tubes heated by a steam cracking furnace.

[0038] The process gas taken away from the pyrolysis reactor is compressed in a process gas compressor so that light olefins and other components of the process gas can be separated and recovered in an olefin recovery facility. The process gas compressor is powered by shaft power. At least a portion of the shaft power is obtained from a turbine operating based on the Allam cycle. These components will now be described in more detail with reference to the following definitions, which will apply to this specification and the appended claims.

[0039] definition

[0040] For purposes of this specification and the following claims, the following terms are defined.

[0041] The term "C n "Hydrocarbon" refers to a hydrocarbon containing n carbon atoms per molecule, where n is a positive integer. The term "C n+ "Hydrocarbon" means a hydrocarbon containing at least n carbon atoms per molecule. The term "C n- "Hydrocarbon refers to a hydrocarbon containing up to n carbon atoms per molecule. The term "hydrocarbon" refers to a class of compounds containing hydrogen bonded to carbon, and encompasses (i) saturated hydrocarbons, (ii) unsaturated hydrocarbons and (iii) mixtures of hydrocarbons, and includes mixtures of hydrocarbon compounds (saturated and / or unsaturated), such as mixtures of hydrocarbon compounds having different values ​​of n.

[0042] The terms "alkanes" and "paraffins" refer to substantially saturated compounds containing only hydrogen and carbon, such as those containing ≤ 1 mol % unsaturated carbon atoms. The terms "unsaturates" and "unsaturated hydrocarbons" refer to compounds containing one or more C 2+ A hydrocarbon compound containing at least one carbon atom directly bonded to another carbon atom through a double bond or a triple bond. The term "olefin" refers to one or more unsaturated hydrocarbon compounds containing at least one carbon atom directly bonded to another carbon atom through a double bond. In other words, an olefin is a compound containing at least one pair of carbon atoms, wherein the first and second carbon atoms of the pair are directly connected by a double bond. The terms "aromatic compound" and "aromatic hydrocarbon" refer to a hydrocarbon compound containing at least one aromatic ring.

[0043] The terms "regenerator", "recuperator", "regenerator bed", "monolith", "honeycomb", "reactant", "fuel" and "oxidant" have the meanings disclosed in U.S. Patent No. 7,943,808, which is incorporated herein by reference in its entirety. A "pyrolysis reactor" is a reactor or a combination of reactors or a reactor system for hydrocarbon pyrolysis. The term "pyrolysis stage" refers to at least one pyrolysis reactor and optionally includes means for directing one or more feeds to it and / or directing one or more products away from it. A "zone" or "segment" is a location within a reactor, such as a specific volume, a location between two reactors, and / or a combination of different locations in one or more reactors. A "pyrolysis zone" is a location where pyrolysis is performed, for example, in a location containing or near a component (e.g., at least one heat mass) that provides heat for pyrolysis. A reactor or reaction stage may include one or more reaction zones. More than one reaction may be performed in a reactor, stage or zone.

[0044] The pyrolysis zone may include components having conduits, channels, and passages. The term "conduit" refers to a device for guiding a composition from one location to another. The term encompasses (i) basic conduction devices, such as pipes or conduits, and (ii) complex devices, such as tortuous paths through conduction devices (such as pipes, conduits, valves, and reactors) filled with random fillers. The term "channel" refers to a geometrically continuous volume element that can be used to transport fluids in a reactor, a regenerator, a recuperator, a regenerator bed, a monolith, a honeycomb, etc. The term "channel" refers to a plurality of passages that can be used together to transport fluids in a reactor, a regenerator, a recuperator, a regenerator bed, a monolith, a honeycomb, etc. For example, a honeycomb monolith may include a single channel having a plurality of passages or a plurality of groups of passages.

[0045] The term "bulk gas temperature" refers to the temperature of the bulk gas vapor measured by a device (e.g., a thermocouple) that is in contact with the bulk gas but not with the solid hot mass. For example, if the length of the gas through the hot mass in the pyrolysis zone of the pyrolysis reactor is L c The internal channel is along L c The bulk gas temperature at a location is the average temperature (arithmetic mean) over the cross-sectional area of ​​the passage at that location. The peak gas temperature is the maximum cross-sectional average bulk gas temperature achieved along the flow path. Those skilled in the art will appreciate that the gas temperature in the immediate vicinity of the solid hot mass (e.g., baffles between passages within the hot mass at any particular location) may exceed the bulk gas temperature, and may actually approach the temperature of the solid in some infinitesimal layers. The average bulk gas temperature "T" over a reactor region (e.g., the pyrolysis zone) is obtained using the formula av ":

[0046]

[0047] Parameters a and b are the spacing (distances) along the long axis of the reactor. For example, refer to Figure 2 , parameter "a" can be the position of hole 5, parameter "b" can be the position of hole 9. T(x) is a function representing the change of bulk gas temperature in the interval from a to b. When T(x) is the pyrolysis zone, for example Figure 3 The bulk gas temperature curve in the pyrolysis zone (at the beginning of tP) indicated by the shaded area in the middle, parameters a and b are the bulk gas temperature curve and line T MIN The intersection position corresponds to the lowest temperature at which the feed conversion is ≥ 10% under the selected pyrolysis conditions and feed. P Period changes, such as Figure 3 As shown, so T av Usually in t P The temperature decreases during the period. MIN The curve portion of may be continuous, but this is not required. For example, when the curve is continuous at more than two locations (e.g., a, b) in the pyrolysis zone, MIN intersect and touch T at position c (not shown, but between a and b) MIN , perform additional integration, for example:

[0048]

[0049] When the curve ≥T MIN When the portion of is in the form of discrete segments, the integration is performed over each segment.

[0050] The term "pyrolysis" refers to an average endothermic reaction for converting molecules into (i) atoms and / or (ii) smaller molecular weight molecules, and optionally (iii) larger molecular weight molecules, such as the process for converting ethane and / or propane into molecular hydrogen and unsaturates such as ethylene, propylene and acetylene.

[0051] A hydrocarbon feed is subjected to "pyrolysis" when <50.0% (e.g., ≤25%, such as ≤10%, or ≤1%) of the heat utilized for pyrolysis is provided by exothermally reacting the hydrocarbon feed, for example, with an oxidant. The "severe threshold temperature" for pyrolysis is the lowest bulk gas temperature at which the acetylene selectivity is at least 10% for a residence time of ≤0.1 seconds. Highly severe pyrolysis conditions are those conditions that are carried out at a peak gas temperature greater than or equal to the severe threshold temperature. Low-severity pyrolysis conditions are those conditions that are carried out at a peak gas temperature below the severe threshold temperature, i.e., conditions in which hydrocarbon pyrolysis is substantially not carried out at a pyrolysis gas temperature that exceeds the severe threshold temperature. Highly severe conditions include those that exhibit (i) a methane selectivity of ≥5 wt % and / or (ii) a propylene selectivity of ≤0.6 wt % at a temperature of ≥1000°C. For a pyrolysis reactor, the term "residence time" refers to the average duration that non-reactive (not convertible by pyrolysis) molecules (e.g., He, N2, Ar) with a molecular weight in the range of 4 to 40 pass through the pyrolysis zone of the pyrolysis reactor.

[0052] The term "periodic table" refers to the periodic table of the elements appearing on the inside cover of the Merck Index, 12th edition, Merck & Co., Inc., 1996. "Steam tables" can be found in MD Koretsky, "Engineering and Chemical Thermodynamics", John Wiley & Sons, 2004. When indicating temperature, the unit "K" indicates degrees Kelvin, the SI unit of temperature.

[0053] Power Device

[0054] In various aspects, the process gas compressor of the pyrolysis reactor for producing ethylene is powered by a power device based on the Allam cycle operation. The power device generates shaft power for providing power to the process gas compressor. The power device can correspond to a fuel combustion turbine, in which supercritical CO2 is used as a working fluid. This method uses a high-pressure CO2 loop to transfer power without the inefficiency of the phase envelope encountered in steam cycle power generation. In some aspects, natural gas and substantially pure oxygen are burned to heat the stream, which is mainly CO2, to the turbine inlet condition, and then the turbine expands this gas to provide shaft power for the generator. Then, the turbine effluent is interchanged with the burner feed to recover energy. Next, water from the combustion process is removed, and the stream is compressed and pumped to the turbine inlet pressure, where fresh CO2 from the combustion can be removed to the pipeline. Using this method, improved efficiency can be obtained, close to 55-60%, without any kind of chimney emissions, and without atmospheric CO2 emissions. It should be noted that other types of fuel streams can be burned. For example, a tail gas stream produced after separation of the various components from the process gas may be used as at least a portion of the fuel stream.

[0055] The tail gas recovered from the process gas can be substantially composed of methane and optionally hydrogen in various concentrations. The tail gas stream from a large industrial steam cracking furnace receiving feed such as ethane may be quite large. In one embodiment of the method of the present disclosure, a portion, preferably most of, preferably all of the tail gas is burned in the Allam cycle to generate power, including shaft power and optionally the electricity of a coupled generator (one or more). Shaft power can be advantageously used to drive one or more devices in the olefin production unit, such as: a) delivered to a process gas compressor to compress process gas, b) delivered to a refrigeration compressor to cool compressed process gas, c) delivered to a refrigeration compressor to cool a decompressed working fluid in a cooling step from the series of cooling and compression steps, or d) a), b) and c) in a combination of two or more. Compared with the use of power derived from an external fuel such as a natural gas stream or the electricity transmitted from the outside of the olefin production unit, the use of the shaft power generated by the combustion of tail gas in the Allam cycle can significantly improve the energy efficiency of the olefin production unit. Electricity can be co-generated in an olefin production unit by coupling a portion of the shaft power to one or more generators to accommodate the power demand in the olefin unit and transmitting it to the outside of the unit where appropriate and economical. When consumed on site, the electricity generated in situ does not involve transmission losses, which are otherwise inevitable if it is transmitted from a remote power device. Olefin production units consume a lot of shaft power, which may be met by using a large-scale Allam cycle that achieves a very high level of economies of scale. In contrast, the power generation unit disclosed in U.S. Patent Application Publication No. 2017 / 0058712A1 is much smaller in scale and therefore less efficient.

[0056] In a conventional Brayton cycle (e.g., the cycle disclosed in U.S. Patent Application Publication No. 2019 / 0169510A1), the exhaust gas containing CO2 and water produced by the combustion of the fuel is generally discharged into the atmosphere, resulting in a large amount of CO2 emissions and water vapor losses. In contrast, any water produced in the Allam cycle of the method of the present disclosure can be advantageously reused. For example, at least a portion of the water stream (i) can be fed into the pyrolysis step to mix with the hydrocarbon-containing feed; (ii) heated to produce steam; (iii) used as an indirect cooling medium; (iv) used as a quenching medium; and (iv) fed into the hydrocarbon-containing stream as a diluent. Olefin production units utilize a large amount of water for cooling and as a process diluent. Due to the amount of fuel burned, the Allam cycle used in the method of the present disclosure in an olefin production unit can produce a very large amount of water (e.g., 1500 kilotons per year for an olefin production unit of the prior art). By reusing the water stream generated by the Allam cycle, the need for water from external sources in the plant is reduced, further increasing plant efficiency, reducing the plant carbon footprint, and improving its environmental friendliness.

[0057] The olefin product produced by the olefin production unit can be an ethylene stream. The ethylene product can have many industrial uses. For example, the ethylene stream can be supplied to a nearby polyethylene production unit via a pipeline, where it is converted into polyethylene. In another embodiment, a portion of the ethylene product can be converted into a diol product, including but not limited to monoethylene glycol ("MEG"), which can be used in vehicle antifreeze and in a method for preparing polyester polymers. In a particularly advantageous method, ethylene can first be oxidized by oxygen to produce an oxidized mixture comprising ethylene oxide, which can then be hydrolyzed to produce MEG, or contact CO to produce ethylene carbonate, which is then hydrolyzed to produce MEG:

[0058] Ethylene + O2 → Ethylene oxide (1)

[0059] Ethylene oxide + H2O → MEG (2)

[0060] Ethylene oxide + CO2 → ethylene carbonate (C3H4O3) (3)

[0061] Ethylene carbonate + H2O → MEG + CO2 (4)

[0062] The oxygen consumed in the above reaction (1) can be supplied by an air separation facility which also supplies the oxygen-containing stream required for burning fuels such as tail gas in the Allam cycle. By using a common air separation facility for both processes (which is expensive), economies of scale that would otherwise be impossible can be achieved, resulting in high energy efficiency and cost effectiveness in all the units involved.

[0063] In the method of the present invention, the CO2-containing stream produced by the Allam cycle and / or the compressed CO2 stream can be advantageously used in various embodiments. For example, a portion of the CO2 produced in the Allam cycle can be supplied to the reaction (4) in the previous paragraph, so that MEG can be effectively produced from the ethylene produced by the ethylene production unit. In another example, a portion of the compressed CO2 stream can be used to extract hydrocarbon source materials, which can be used to obtain at least a portion of the hydrocarbon-containing feed subjected to pyrolysis to prepare olefin products. This hydrocarbon source material can be, for example, crude oil, shale oil, shale gas, natural gas, etc. stored in underground geological formations. From the extracted crude oil, shale oil, shale gas and / or natural gas, suitable feeds, such as natural gas streams, ethane streams, etc., can be obtained as feeds for steam crackers in olefin production units. In this way, integrating the Allam cycle, olefin production and hydrocarbon extraction can greatly promote the entire production process and significantly improve overall energy efficiency. Any remaining CO2 produced from the Allam cycle can be suitably injected into underground storage for storage, which is generally available at hydrocarbon extraction sites. Alternatively or additionally, a portion of the compressed CO2 stream can be conveniently supplied to other locations via a pipeline for sale, storage or use. In summary, the disclosed olefin production process can leave a very small CO2 footprint, in stark contrast to conventional processes that can produce large amounts of CO2.

[0064] By burning large amounts of tail gas produced in an olefin production unit in an Allam cycle in the process of the present disclosure, it is thus possible to conveniently process relatively low value fuel streams, generate large and flexible amounts of shaft power and / or electricity required by the olefin production unit, supply large amounts of process water otherwise required from external sources to the olefin production unit, supply oxygen to adjacent processes, such as the MEG production process, with greater economies of scale, and facilitate hydrocarbon extraction using a CO2 stream, all with minimized CO2 emissions and water emissions. The overall benefits of the process of the present disclosure can be enormous.

[0065] To drive multiple compressors, the CO2 loop can be split among the compressors to be powered. In such an aspect, the burner can be located next to the turbine inlet to minimize hot piping and allow separate isolation / maintenance. Each compressor can be coupled to a CO2 loop turbine to drive the compressor without boiler emissions from a steam turbine drive, gas turbine combustion emissions from a gas turbine drive, or off-the-grid power generation emissions from incremental grid power for an electric motor drive.

[0066] Furthermore, instead of using only natural gas for combustion as may be practiced in the power industry, the ethylene unit tail gas may be used for combustion, resulting in reduced CO2 production and increased water removal. Alternatively, natural gas may be used for compression power with the Allam cycle, while the hydrogen-rich tail gas is supplied to a conventional combustion source, such as a steam cracker or boiler, to reduce net CO2 emissions.

[0067] In order to supply power in this way, compressor is added in ethylene plant with CO2 loop CO2 is compressed to supercritical fluid when pressure increases and shows reduction, minimized or no compressibility pressure.Additionally or alternatively, additional compression can be used for separating oxygen and natural gas compression to target pressure before burning, for example 200 bar or higher or 250 bar or higher or 300 bar or higher pressure, for example up to 600 bar or may be higher.After burning, the working fluid through pressurization, heating is used to drive turbine.This can be reduced to 70 bar or lower or 60 bar or lower or 50 bar or lower pressure through decompression working fluid, for example as low as 20 bar or may be lower.This equipment can use the redundant power from turbine power step to drive these supporting steps.Therefore, even if ethylene plant needs transformation to be integrated with Allam cycle, this transformation does not need other separate power source.

[0068] Figure 6 An example of a Mollier diagram (pressure versus enthalpy plot) for a single combustor and turbine operating based on the Allam cycle is shown. Figure 6 Also shown are the lines corresponding to the constant temperature curves, and the regions of phase space where distinct gas and liquid phases of CO2 may exist since the CO2 is not in a supercritical state.

[0069] exist Figure 6 , the Allam cycle is illustrated based on how various processes within the cycle cause changes in the pressure and / or enthalpy of the working fluid. The cycle begins with the addition of a fuel input 610 to the working fluid before the fuel and working fluid are passed into the combustor. The fuel burns 620, which results in an increase in enthalpy at a relatively constant pressure. This high pressure, high enthalpy working fluid is then used to provide power to a turbine 630. Providing power to the turbine 630 results in a decrease in both the pressure and enthalpy of the working fluid. The depressurized working fluid is then heat exchanged 640 with the high pressure working fluid 680 to which the fuel input 610 is combined. The heat exchange reduces the enthalpy of the low pressure working fluid while increasing the enthalpy of the high pressure working fluid.

[0070] After the heat exchange, water is removed from the working fluid 650. The water removal is performed by cooling the working fluid to condense the water. However, such cooling may also place the working fluid in a region of the phase space where the CO2 in the working fluid will no longer be in the supercritical region. To avoid this, as Figure 6 As shown, water removal 650 is performed in a series of alternating cooling steps 652 and compression steps 654. This allows the CO2 in the working fluid to remain in a supercritical state (substantially) during the water removal process so that no phase change occurs in the working fluid. After water removal 650, the remaining working fluid substantially corresponds to CO2. The CO2 working fluid is then further compressed 660 to return the working fluid to the temperature required by the burner 620. After pressurization 660, the working fluid is then heated 670 and heat exchanged 680 to prepare for the burner.

[0071] It should be noted that the number of compression and cooling steps used during the alternating series of compression and cooling steps can vary depending on the nature of the fuel to the combustor associated with the turbine. In particular, as the amount of H2 in the fuel to the combustor increases, the likelihood of CO2 condensation can be modestly reduced. Therefore, using a fuel such as tail gas from a pyrolysis process can potentially reduce the number of independent compression and cooling steps required to remove water while avoiding phase changes of CO2 in the working fluid. In addition, using a fuel such as tail gas from a pyrolysis process can potentially reduce air separation requirements because less oxygen is required to burn a higher H2 content fuel.

[0072] Figure 5 shows a method for using an Allam loop (e.g. Figure 6 An example of a process flow for operating a turbine is shown in FIG. Figure 5 590. This produces a high purity oxygen stream 598 and a remainder stream 594 corresponding to nitrogen and other components of air 591 not included in the high purity oxygen stream 598. The high purity oxygen stream 598 can include 90% by volume or more of O2, or 95% by volume or more, such as up to substantially all of the oxygen stream 598 corresponding to O2 (less than 1% by volume of other components). By forming the high purity oxygen stream 598, a subsequent combustion process can be performed with a reduced or minimal amount of N2 or other diluents present.

[0073] Oxygen stream 598 enters burner 510. Fuel stream 505 also enters burner 510. Combustion reaction can be carried out in burner 510 to produce heat, CO2 and H2O. Additional CO2 circulating stream 574 can also enter burner 510 as working fluid to absorb additional heat from combustion reaction. Combined gas phase products from combustion reaction and additional circulating stream 574 leave burner 510 as gas stream 515. Because oxygen stream 598 includes reduced amount or minimum amount of components other than O2, gas stream 515 can correspond to 80 volume % or more of CO2 and H2O, or 90 volume % or more, or 95 volume % or more. Then, gas stream 515 is used to drive turbine 520, and turbine 520 provides shaft power 599 for one or more process gas compressors. This obtains gas stream 525 with reduced pressure.

[0074] After providing power to the turbine 520, the reduced pressure gas stream 525 enters the heat exchanger 530 to transfer heat to the additional circulating stream 574. The heat exchanged gas stream 535 is then further cooled by heat exchange with a fluid from the cooler 580. After further cooling, the heat exchanged gas stream 535 then enters the separator 540 to separate water 547. The remaining portion 545 of the gas stream may correspond to 90% CO2 or more by volume, or 95% CO2 or more by volume, or 97% CO2 or more by volume. The remaining portion 545 of the gas stream is then further cooled before further compression and / or pumping, for example by using a compression section 550 and / or a pump 552, to form a gas stream 558 containing high pressure CO2. Optionally, cooling before compression can be further assisted by heat exchange with an interstage cooling stream (e.g., an interstage cooling stream (not shown) from an air separation unit 590). A portion 572 of the high pressure CO2 gas stream enters the heat exchanger to form the additional circulating stream 574.

[0075] The composition of the working fluid may vary depending on the location in the cycle where the working fluid is sampled. After combustion and before water is removed, the working fluid may include CO2, CO, H2O, and optionally one or more components that are present due to a fuel containing compounds other than hydrogen and hydrocarbons and / or due to the use of an oxygen-containing stream containing compounds other than oxygen. Optionally but preferably, the oxygen-containing stream may include 90% by volume or more of O2, or 95% by volume or more, or 97% by volume or more, such as an oxygen-containing stream consisting essentially of O2 (less than 0.1% by volume of components other than O2). Optionally, but preferably, the fuel used for combustion may include 90% by volume or more of hydrogen, hydrocarbons, CO, CO2, and H2O, or 95% by volume or more, or 97% by volume or more, such as containing at most 0.1% by volume or less of other components. Suitable fuels include those designated for regeneration in pyrolysis reactors, such as those with a calorific value ≥1×106 J / kg of fuel. For example, the fuel may include one or more of natural gas, gaseous hydrocarbons in natural gas, gaseous hydrocarbons separated and / or derived from natural gas, gaseous hydrocarbons separated and / or derived from natural gas condensate, gaseous hydrocarbons separated and / or derived from crude oil, molecular hydrogen, carbon monoxide, and mixtures thereof. Additionally or alternatively, a tail gas stream produced by an ethylene unit may be used as at least a portion of the fuel.

[0076] After water separation and before adding more fuel, the working fluid may include less than 1.0 vol% water, or less than 0.1 vol% water. Additionally or alternatively, the working fluid after water separation and before adding more fuel may include 90 vol% or more CO2, or 95 vol% or more, or 97 vol% or more, such as consisting essentially of CO2 (less than 1.0 vol% components other than CO2, or less than 0.1 vol%).

[0077] The shaft power generated by the turbine can potentially be used to provide power for various components within the processing equipment group for processing pyrolysis effluent. In some aspects, the power from the turbine can be used to drive a process gas compressor. Another option can be to use at least a portion of the shaft power from the turbine to drive a compressor, which is a part of a refrigeration unit for cooling one or more parts of the pyrolysis effluent. Another option can be to use shaft power to drive the compressor involved in the compression and cooling steps, which are used to remove water from the working fluid while maintaining CO2 in a substantially supercritical state. It should be noted that during the compression and cooling steps, the compressor can be used for both compression and refrigeration. In some aspects, part of the shaft power from the turbine based on the Allam cycle operation can be used to provide power for multiple compression and / or refrigeration processes of the above-mentioned types. In other aspects, any other convenient integrated use of shaft power can be achieved.

[0078] Figure 4 Shown by Figure 5 An example of how the shaft power 599 provided by the turbine 520 in FIG. 5 can be used to power a process gas compressor. Figure 4 An example of a suitable power device is schematically shown in FIG. Figure 4 In the process, the process gas (e.g. Figure 1 and 2The process gas is directed to a cooling stage 380 (typically a quench tower or a combined quench tower-primary fractionator) via line 49 to produce a cooled process gas which is carried away via line 61. Water is a typical quench medium which may be recovered via line 39, pressurized in pump 390, directed to a cooler 400 via line 40, and sent back to the cooling stage via line 41. The cooled process gas is initially pressurized in a compressor stage 410 which typically includes at least three stages of increasing compression and inter-stage cooling. The pressurized process gas from the compression stage 410 is directed via line 42 to a process gas upgrading device, typically a caustic and / or amine treatment, schematically shown as tower 420. Spent process media (e.g., spent caustic) is carried away via line 60. The upgraded process gas is directed to a second compression stage 430 via line 62 for further pressurization. Typically, stages 410 and 430 are connected by rotating shaft 402, which can be connected to rotating shaft 401 for providing power to these stages. Shaft 402 obtains at least a portion of its shaft power from turbine 520 (e.g., Figure 5 401 ). This can be accomplished by: (i) direct transfer of rotational energy, e.g., via rotational power transfer; (ii) indirect transfer, e.g., by powering a generator with power 599 from turbine 520, driving an electric motor with at least a portion of the electricity produced by the generator, and using the electric motor to power shaft 401; and (iii) a combination of direct and indirect power transfer. The compressed process gas is removed via line 63 for storage and / or further processing, e.g., drying, acetylene conversion, and recovery of products such as ethylene.

[0079] Representative regenerative pyrolysis reactor

[0080] A regenerative pyrolysis reactor is an example of a suitable reactor for producing ethylene from a hydrocarbon feed. A regenerative pyrolysis reactor typically includes an internal volume having at least one zone. A regenerative thermal mass having at least one internal channel is located in this zone. A reactor temperature profile sufficient for pyrolysis is established, such as by heating the thermal mass, and a flow of the hydrocarbon-containing feed is established through the channel. Heat is transferred from the thermal mass to the hydrocarbon feed, which increases the temperature of the hydrocarbon feed and causes pyrolysis of at least a portion of the feed, such as pyrolysis performed in the substantial absence of an oxidant. The pyrolysis produces a hydrocarbon feed comprising typically molecular hydrogen, methane, acetylene, ethylene, and C 3+ The pyrolysis products of hydrocarbons, among which C 3+ Hydrocarbons include coke and coke precursors. At least a portion of the coke typically remains in the path of the hot mass, and the remainder of the pyrolysis products are typically carried away from the reactor as process gas. Because pyrolysis is endothermic, pyrolysis mode operation will eventually cool the hot mass, for example, to a temperature at which pyrolysis cannot be effectively performed. The ability to effectively perform pyrolysis reactions is restored by regenerating the reactor during the regeneration mode.

[0081] Figure 2 and Figure 3 The thermal characteristics of the reactor 50 are combined with Figure 1 The thermal characteristics of the conceptual reactor 101 described herein are substantially consistent with those described herein. The reactor 50 is in the form of an elongated tubular container having an internal volume that includes at least one heat transfer zone and at least one pyrolysis zone. The cross-sectional shape and / or cross-sectional area of ​​the reactor container may be substantially uniform over the length of the reactor, but this is not required. For example, one or more sections of the length of the reactor container may have a circular, elliptical, or polygonal cross-section. The reactor 50 has opposing first and second openings 51, 52 that are in fluid communication with the internal volume and are located at the ends of the reactor container. The first opening and the second opening are spaced apart by the reactor length L. R The reactor further comprises at least one thermal mass 1 located in a first region of the internal volume. The thermal mass has at least one internal channel, which typically has a length substantially equal to L1. The thermal mass also has a first hole 3 and a second hole 5 in fluid communication with the channel. The first hole and the second hole are separated by a flow path through the channel. Typically, the flow path has a length substantially equal to L1. The first hole is typically located near the first opening.

[0082] During the pyrolysis mode, a forward flow of the hydrocarbonaceous feed is established into the passage towards the second orifice by introducing the feed via line 15 through the first opening 51 and through the first orifice 3. The pyrolysis mode operates during a time interval tP, which is P The feed is heated by transferring heat from at least one section of the first thermal mass 1 (conceptually the first heat transfer zone). Typically, the first section of the first thermal mass 1 is located in the first heat transfer zone (e.g., Figure 3 The first hot mass 1 is shown as an unshaded section) and the second section is located in the pyrolysis zone (shaded section). This heat transfer heats the feed sufficiently so that it undergoes pyrolysis in the interior volume of the reactor (e.g., near the hot mass 1), which produces a mixture comprising molecular hydrogen and C 2+ The pyrolysis conditions include a gas temperature profile within the reactor at t1 that exhibits a peak gas temperature T p and <T p The average gas temperature T av . T p Typically in the range of 800°C to 1400°C. Typically, the bulk gas temperature profile at the start of the pyrolysis mode (solid curve) varies continuously over the length of the pyrolysis zone. Pyrolysis is endothermic on average, so pyrolysis is carried out at t P During the cooling of the reactor, T pThe pyrolysis product flow is directed via the second orifice 5 into a second region of the internal volume, and the process gas is carried away from the reactor via the second opening 52 and the line 49. Optionally, the second thermal mass 7 is located in the internal volume of the reactor, such as Figure 2 and Figure 3 The pyrolysis products are cooled in the interior volume of the reactor by transferring heat from the pyrolysis products to at least one section of the second thermal mass 7 (conceptually, the second heat transfer zone). Typically, the first section of the second thermal mass 7 is located in the second heat transfer zone (e.g. Figure 3 The unshaded section of the second thermal mass 7 is shown, and the second section is located in the pyrolysis zone (shaded section). After the pyrolysis mode (e.g., after t2), the regeneration time interval t R To regenerate the reactor, the regeneration time interval t R The duration is sufficient to at least partially restore the reactor to conditions where additional pyrolysis can occur.

[0083] In certain aspects (not shown), regeneration comprises R During the regeneration mode, at least a portion of the fuel-oxidant heating mixture is combusted at a location outside the interior volume of the reactor 50. For example, the fuel combustion can be conducted at a location outside the reactor 50, wherein the combustion products, unreacted oxidant, and optionally unreacted fuel are delivered to the vicinity of the pyrolysis zone for (i) heating the pyrolysis zone to provide a desired temperature profile for efficient pyrolysis and (ii) removing at least a portion of any deposits remaining in the reactor when the regeneration mode is initiated. In aspects where the optional second hot material 7 is present in the reactor 50, as shown in FIG. Figure 2 and 3As shown, the regeneration mode includes conveying a countercurrent of a heated mixture 19 containing fuel and oxidant through opening 52, through holes 9 of the hot mass 7, and out of hole 11 toward a region of the reactor interior volume located between the first and second hot masses (the region conceptually corresponds to the combustion zone). Typically, the fuel and oxidant are conveyed from hole 9 toward hole 11 through different channels of the second hot mass 7, respectively, and are mixed and distributed by the mixer-distributor 10 to form a heated mixture downstream of the hot mass 7 (relative to the fuel / oxidant flow). Typically, as the fuel and oxidant flow through the channels of the hot mass 7, the fuel and oxidant are heated by heat transfer from at least one section of the hot mass 7 (conceptually, the second heat transfer zone). The combustion of the fuel and oxidant produces a combustion effluent in a region of the reactor interior volume between the hot masses 7 and 1 (conceptually, the combustion zone). The combustion effluent, any unburned oxidant, and any unburned fuel enter the hole 5. The accumulated combustion effluent 45 is carried away from the hole 3 and away from the reactor via the opening 51. The aggregate combustion effluent typically includes combustion effluent generated in the region of the internal volume between holes 11 and 5; additional combustion effluent, typically from sediment removal in the passage of the hot mass 1; and any unreacted fuel and / or any unreacted oxidant. Heat is transferred from the combustion effluent to at least one section of the first thermal mass (conceptually corresponding to the first heat transfer zone).

[0084] Combustion can be carried out in a region within the interior volume of the reactor 50, such as an open volume of substantially constant circular cross-section (not shown) having a length L and a diameter D and a cross-sectional area A. As can be appreciated, an open volume having an appropriate L:A ratio will provide at least some mixing and distribution during the regeneration mode without creating too much pressure drop during the pyrolysis mode. More typically, because it provides improved mixing and distribution and allows for a smaller overall length of the combustion zone, the combustion zone includes at least one mixer-distributor device 10. When used, the mixer-distributor 10 can be centered in the region between the holes 11 and 5, for example, L2 is substantially equal to L4. The sum of the lengths L1, L and L3 is typically ≥ the overall length of the reactor 50 (L R ), for example, measured between openings 51 and 52. Because it is desirable to direct the fuel and oxidant flows into the appropriate passages of the hot mass 7 during the regeneration mode, and to direct the pyrolysis feed flow into the appropriate passages of the hot mass 1 during the pyrolysis mode, it is desirable to limit the internal volume between the hole 9 and the opening 52 and between the hole 3 and the opening 51 to that required to facilitate reactor assembly and to prevent component interference that may occur during use due to thermal expansion. For example, the distance along the flow path between the hole 9 and the opening 52 is typically ≤0.1 L R , for example ≤0.01L R , or ≤0.01L RLikewise, the distance along the flow path between the hole 3 and the opening 51 is typically ≤ 0.1 L R , for example ≤0.01L R or ≤ 0.01 L R . The pyrolysis zone, which typically encompasses all L zones, sections of L1, and sections of L3, is typically ≥10%, such as ≥15%, or ≥20%, of the total length of the reactor 50. The pyrolysis zone also typically encompasses ≤80% of the total length of the reactor 50, such as leaving enough internal volume of hot material 1 for preheating the pyrolysis feed and leaving enough internal volume of hot material 7 for quenching the pyrolysis products, such as ≤60%, or ≤40%. In certain aspects, the length of the pyrolysis zone is in the range of 10% to 60% of the total length of the reactor, such as in the range of 20% to 40%. The length L of the combustion zone is typically ≤50%, such as ≤40%, such as ≤30%, or ≤20% of the length of the pyrolysis zone.

[0085] The values ​​of L, L1, L2, L3, L4 and D generally depend on the pyrolysis feed used and the rate at which it is introduced into the reactor, the fuel and oxidant compositions and the rate at which they are introduced into the reactor, etc. Although larger and smaller reactors are within the scope of the present invention, (i) D is generally ≥ 1 cm, for example, in the range of about 1 cm to 10 m, for example, 0.1 m to 7.5 m, (ii) L R Typically ≥ 1 cm, for example, in the range of about 1 cm to 20 m, for example, 0.1 m to 7.5 m, (iii) L is typically ≤ L R 25%, for example ≤10%, (iv) L1 is usually ≥L R 35%, for example ≥45%, (v) L3 is usually ≥ L R L3 optionally has substantially the same size and shape as L1, and (vi) L2 is typically within about + / - 25%, such as + / - 10%, such as + / - 5% of L4.

[0086] The mixer-distributor is generally configured to (i) mix the fuel and a portion of the oxidant during the regeneration mode for efficient combustion, (ii) increase the uniformity of distribution of the combustion products, unreacted oxidant, and non-essential unreacted fuel over the internal cross-sectional area of ​​the first heat transfer zone, and (iii) reduce the undesirable pressure drop effect during the pyrolysis mode. The mixer-distributor can be in the form of a thinner member (e.g., a plate) having one or more orifices that are effectively used for mixing and distribution during the regeneration mode. Typically, the orifice has a sufficient cross-sectional area to prevent an undesirable large pressure drop along the reactor during the pyrolysis mode. Conventional mixer-distributors, such as those described in U.S. Patent Application Publication No. 2013-0157205A1 and U.S. Patent No. 7,815,873 (incorporated herein by reference in their entirety), can be used, but the present invention is not limited thereto. Optionally, combustion is carried out in the presence of at least one selective combustion catalyst, such as one or more of those described in U.S. Patent No. 8,754,276, but the present invention is not limited thereto. When used, a fixed bed of a selective combustion catalyst may be included as a component of the mixer-distributor, for example, where one or more of the plate members of the mixer-distributor serve as catalyst supports. However, in certain aspects, such as those aspects where the amount of coke deposits in hot mass 1 exceeds the amount of coke deposits in hot mass 7, the combustion zone is shifted downstream (relative to the fuel-oxidant fluid) toward hot mass 1. The amount of displacement is typically ≤ 25% of L, such as ≤ 20%, such as ≤ 10%.

[0087] The combustion zone is at t R The area of ​​the internal volume of the reactor 50 occupied during the period, which area is P During this period, it is located in the pyrolysis zone. However, because Figure 2 and Figure 3 In the illustrated aspect, the regeneration mode is not performed simultaneously with the pyrolysis mode, so no significant combustion occurs in the combustion zone during the pyrolysis mode, and no significant pyrolysis occurs in the pyrolysis zone during the regeneration mode. After any accumulated deposits are sufficiently removed and the reactor temperature profile required for pyrolysis is achieved, the reactor 50 can be switched from the regeneration mode to the pyrolysis mode.

[0088] Typically, the first thermal mass and the second thermal mass include padding or filler materials that effectively store and transfer heat, such as glass or ceramic beads or spheres, metal beads or spheres, ceramics (e.g., ceramics that may include alumina, yttria, and zirconia) or honeycomb materials containing ceramics and / or metals, other forms of pipes containing ceramics and / or metals, extruded monoliths, etc. The hot mass and the regeneration bed containing the hot mass can be channel members containing refractory materials, such as those described in U.S. Patent Nos. 8,754,276; 9,126,882; 9,346,728; 9,187,382; 7,943,808; 7,846,401; 7,815,873; 9,322,549; and U.S. Patent Application Publication Nos. 2007-0144940, 2008-300438, 2014-303339, 2014-163287, 2014-163273, 2014-0303416, 2015-166430, 2015-197696, and 2016-176781. These references are incorporated herein by reference in their entirety. The hot masses 1 and 7 can each have the form of an elongated refractory honeycomb. The honeycomb body includes at least one channel having a plurality of passages. The honeycomb body (and sections thereof) has a substantially constant OFA when the cross-sectional size and shape of the channels and passages are substantially uniform.

[0089] Thermal materials typically have a thermal conductivity in the range of 0.5 W / m°K to 50 W / m°K, with a thermal conductivity of 1×10 -7 / °K to 2×10 -5 / °K range of thermal expansion coefficient, at 1cm -1 Up to 100cm -1 The average wetted surface area per unit volume in the range of 1 cm -1 Up to 100cm -1 The average wetted surface area per unit volume is within the range of 1000 to 2000 m. The internal passages of each thermal mass generally include a plurality of substantially parallel passages, for example, with a passage density of 77,000 / m 2 to 1.3×10 6 / m 2 The thermal mass usually includes refractory materials, for example, with a heat capacity of ≥ 0.04 [kJ / (°K·kg)] at 300°K and a density of ≥ 3000kg / m 3 For example, the specific heat capacity of the refractory material at 300°K may be in the range of 0.04 [kJ / (°K·kg)] to 1.2 [kJ / (°K·kg)], and its density may be 3000 kg / m 3 Up to 5000kg / m 3 within the range.

[0090] The selection of refractory composition is not critical, as long as it can survive in the actual running length (e.g., several months) under the conditions of pyrolysis mode and regeneration mode without significant degradation or decomposition. It will be appreciated by those skilled in the art that the composition of the first and second thermal substances should be selected from those that substantially maintain integrity (structure and composition) and functionality during long-term exposure to pyrolysis feed, product, and reaction conditions (e.g., temperature ≥750°C, e.g., ≥1200°C, or ≥1500°C for increased operating margin). Conventional refractory materials can be used, including those containing at least one oxide of one or more elements selected from the 2nd-14th group of the periodic table of elements, but the present invention is not limited thereto. In a particular aspect, the refractory material includes at least one oxide of Al, Si, Mg, Ca, Fe, Mn, Ni, Co, Cr, Ti, Hf, V, Nb, Ta, Mo, W, Sc, La, Yt, Zr, and Ce. The refractory material may include non-oxide ceramics.

[0091] Representative conditions and feeds for the regeneration mode and pyrolysis mode will now be described in more detail. The invention is not limited to these feeds and process conditions, and this description should not be interpreted to exclude other feeds and process conditions within the broader scope of the invention.

[0092] Regeneration mode

[0093] The regeneration mode is performed to (i) reheat the pyrolysis zone to establish a temperature distribution corresponding to the bulk gas temperature distribution required at the beginning of the subsequent pyrolysis mode, and (ii) remove sufficient sediment from the internal volume of the reactor, which may otherwise cause an increase in the reactor pressure drop. When it is necessary to quench the pyrolysis products in the reactor (for example, in order to utilize the conceptual second heat transfer zone), the regeneration mode optionally includes cooling the hot mass 7 or a section thereof. The fuel and oxidant contained in the heated mixture are burned in the combustion zone during at least a portion of the regeneration mode. A wide range of fuels can be used to burn with the oxidant and regenerate the pyrolysis reactor, including hydrocarbon feeds. In general, the fuel is selected from natural gas, hydrocarbons in natural gas, hydrocarbons separated and / or derived from natural gas, natural gas condensate, hydrocarbons in natural gas condensate, hydrocarbons separated and / or derived from natural gas condensate, crude oil, hydrocarbons in crude oil, hydrocarbons separated and / or derived from crude oil, molecular hydrogen, carbon monoxide and mixtures thereof. Fuels and fuel components that do not contain hydrocarbons (such as one or more of molecular hydrogen, CO and synthesis gas) are within the scope of the present invention. Typically, the fuel is derived from, contains, is essentially composed of one or more of the following substances, or is composed of one or more of the following substances: molecular hydrogen, CO, methane, methane-containing streams such as coal bed methane, biogas, associated gas, natural gas and mixtures or components thereof, etc. The oxidant is typically one or more of molecular oxygen, ozone and air, including molecular oxygen in air, oxygen-enriched air and oxygen-deficient air. Optionally, the fuel and oxidant are the same as those disclosed in U.S. Patent No. 7,943,808. The feed flow rate depends on factors such as feed composition, reactor volume, pyrolysis conditions, etc. Therefore, the present invention can be carried out over a very wide range of heated mixture flow rates, such as a flow rate ≥ 0.001 kg / s, such as ≥ 0.1 kg / s, or ≥ 10 kg / s, or ≥ 100 kg / s, or higher.

[0094] Once the desired calorific value (heat value) of the fuel is selected, the accumulated coke deposit (“OCD”) can be calculated based on the amount of fuel that is burned. a ”) and the amount of oxidant required for substantially stoichiometric combustion of the fuel (“OC b The amount of fuel and oxidant directed to the reactor during the regeneration mode is specified by the amount of oxidant supplied during the regeneration mode. Typically, the amount of oxidant supplied during the regeneration mode is z·(OC a +OC b ), wherein z is typically ≥ 0.5, such as ≥ 0.8, such as in the range of 0.5 to 5.0, or 0.5 to 3.0, or 0.8 to 3.0. OC a and OC bThe amount is in moles. When Z>1.0, excess oxidant can be utilized, for example, for one or more of: removing at least a portion of any accumulated deposits, regulating the reaction temperature during the regeneration mode (as disclosed in U.S. Pat. No. 7,943,808), and transferring heat from one zone to another within the reactor. Typically, a first portion of the oxidant is combusted with the fuel in the combustion zone, and a second portion is combusted with the accumulated coke deposits. Typically, the first portion comprises ≥50 wt %, e.g., ≥75 wt % or ≥90 wt % of the total amount of oxidant supplied during the regeneration mode. It is also typical that the oxidant flow rate and the fuel flow rate remain substantially constant for the duration of the regeneration mode. These flow rates are selected to be constant at t R The required combustion heat and the required coke removal are achieved during this period. R ≤30 seconds is generally sufficient to reheat the reactor to achieve the desired bulk gas temperature profile at the start of the pyrolysis mode, e.g., ≤25 seconds, such as ≤10 seconds, or ≤1 second, or ≤0.1 seconds. For example, t R Can be in the range of 0.01 to 25 seconds, or 0.05 to 10 seconds, or 0.05 to 5 seconds, or 0.05 to 1 second.The present invention is compatible with conventional methods for reducing coke accumulation in hot masses during regeneration mode, such as those described in U.S. Pat. No. 9,187,382, which is incorporated by reference in its entirety.

[0095] Other streams can be provided to the reactor during the regeneration mode, for example, one or more diluent streams can be provided, for example, by adding one or more diluents to the heated mixture, for example, to the oxidant and / or the fuel. Suitable diluents (which can be diluent mixtures) include one or more of the following substances: for example, oxygenates (water, carbon dioxide, etc.), incombustible substances such as molecular nitrogen (N2) and fuel impurities such as hydrogen sulfide. For example, the oxidant can include 60.0 mol % to 95.0 mol % diluent and 5.0 mol % to 30.0 mol % molecular oxygen, based on each mole of oxidant, for example, when the oxidant is air. Optionally, the oxidant has a mass ratio of 0.5 to 20.0, for example, 4.0 to 12.0 diluent to molecular oxygen.

[0096] At the end of the regeneration mode, the reactor is switched to the pyrolysis mode, typically by reducing or terminating the flow of fuel and oxidant and starting or increasing the flow of the pyrolysis feed. Representative pyrolysis feeds and process conditions will now be described in more detail. The present invention is not limited to these pyrolysis feeds, and this specification is not meant to exclude the use of other pyrolysis feeds.

[0097] Pyrolysis mode

[0098] The pyrolysis feed typically contains C 2+Hydrocarbons, such as ≥ 1 wt% C 2+ Hydrocarbons, such as ≥10 wt%, or ≥25 wt%, or ≥50 wt%, or ≥75 wt%, or ≥90 wt%. Typically, ≥90 wt% of the remainder of the pyrolysis feed comprises a diluent, such as one or more of methane, CO2, water, etc. Suitable pyrolysis feeds include those disclosed in U.S. Patent Application Publication No. 2016-176781, which is incorporated herein by reference in its entirety. Also suitable are feeds comprising the following components: for example (i) saturated C 4+ hydrocarbons and / or (ii) having one or more substantially saturated C 2+ The feedstock may include a recycled portion of the pyrolysis product. When used, such recycled material may include, for example, methane, molecular hydrogen, and C 2+ Hydrocarbons, typically C2 to C5.

[0099] The feed hydrocarbon may include volatile and non-volatile hydrocarbons, as described in U.S. Patent Application Publication No. 2016-176781. Although the feed hydrocarbon typically includes C 2+ Compounds, but the feed hydrocarbons may contain compounds with covalently bound and / or non-covalently bound heteroatoms. When present in the feed hydrocarbons, the amount of such heteroatom-containing hydrocarbon compounds is generally ≤10 wt % based on the weight of the feed hydrocarbons. Feed hydrocarbons substantially free of non-aliphatic hydrocarbons are within the scope of the present invention, and feed hydrocarbons substantially free of aromatic hydrocarbons and / or substantially free of olefins, particularly C2-C5 olefins, are also within the scope of the present invention. In this article, substantially free refers to <1 wt %, based on the weight of the feed hydrocarbons, for example ≤0.1 wt %, or ≤0.01 wt %, or ≤0.001 wt %.

[0100] The feed hydrocarbons can be obtained from one or more hydrocarbon sources, for example, from natural hydrocarbon sources (including those associated with oil production), or from one or more synthetic hydrocarbon sources such as catalytic and / or non-catalytic reactions. Examples of these reactions include catalytic cracking, catalytic reforming, coking, steam cracking, etc. Synthetic hydrocarbon sources include those in which the hydrocarbons within the geological formation have been purposefully subjected to one or more chemical transformations. The feed hydrocarbons can include one or more of the following: ethane, propane, butane, saturated and unsaturated C6 hydrocarbons (including those derived from one or more of the Fischer-Tropsch synthesis products, shale gas, biogas, associated gas, natural gas, and mixtures or components thereof), steam cracked gas oils and residual oils, gas oils, heating oils, jet fuels, diesel, kerosene, gasoline, naphtha (including coker naphtha, steam cracked naphtha, and catalytic cracked naphtha), hydrocracking products, reforming products, raffinate reforming products, Fischer-Tropsch liquids, natural gasoline, distillates, straight run naphthas, crude oils, atmospheric tube bottoms, vacuum tube still streams including bottoms, wide boiling range naphthas to gas oil condensates, heavy non-virgin hydrocarbon streams from refineries, vacuum gas oils, heavy gas oils, naphthas contaminated with crude oil, synthetic crude oils, shale oils, coal liquefaction products, coal tars, tars, atmospheric residues, heavy residues, C4 residue blends, naphtha-residue blends, cracking feeds, coker distillate streams, and hydrocarbon streams derived from plant or animal matter.

[0101] The diluent, when present, is typically included in the pyrolysis feed in an amount of ≤60 wt%, such as ≤50 wt%, such as ≤40 wt%, or ≤30 wt%, or ≤20 wt%, or ≤10 wt%, or 10 wt% to 50 wt%, based on the weight of the feed. The diluent is also suitable for use as a sweep gas, for example, to (i) remove at least a portion of any pyrolysis products in the reactor after the pyrolysis mode and / or after the regeneration mode and / or (ii) adjust the temperature profile of the reactor - the heat carried by the sweep gas from the warmer regions of the reactor to the cooler regions will increase the temperature of the cooler regions and further reduce or prevent sharp gradients in the reactor temperature profile.

[0102] Those skilled in the art will appreciate that the feed rate will depend on factors such as feed composition, reactor volume, pyrolysis conditions, etc. Therefore, the present invention can be carried out over a very wide range of feed rates, such as a rate ≥ 0.001 kg / s, such as ≥ 0.1 kg / s, or ≥ 10 kg / s, or ≥ 100 kg / s, or higher.

[0103] like Figure 1As shown, during the pyrolysis mode, the pyrolysis feed stream is directed to the regenerative pyrolysis reactor in an average flow direction (for convenience, "co-current") substantially opposite to the oxidant stream (for convenience, "counter-current"). During the pyrolysis mode, at least a portion of the feed hydrocarbon is pyrolyzed to produce pyrolysis products. Certain pyrolysis conditions that can be used to pyrolyze a given pyrolysis feed will now be described in more detail. The present invention is not limited to these pyrolysis conditions, and this description is not meant to exclude the use of other pyrolysis conditions.

[0104] At the pyrolysis time interval t P The pyrolysis conditions in the pyrolysis zone during the period generally include T p ≤1673K(1400℃),T av ≤1473K (1200°C) and average total pressure ≥0 psig (1.01 bar). The total gas residence time in the pyrolysis zone is typically ≤0.4 seconds to reduce the conversion of desired products such as light olefins to coke. Typically, pyrolysis conditions include T p ≤1473K, such as ≤1373K, such as ≤1273K or in the range of 1273K to 1673K; T av ≤1373K, for example ≤1273K, such as ≤1173K, or in the range of 1173K to 1373K, or 1198K to 1348K; and feed hydrocarbon partial pressure ≥0.48 bar (48kPa), or ≥0.69 bar (69kPa), or ≥1.38 bar (138kPa), or ≥2.07 bar (207kPa). The average total pressure is typically ≥0.34 barg (34kPag), or ≥1.03 barg (103kPag), or ≥2.76 barg (276kPag), or ≥5.52 barg (552kPag), or ≥8.27 barg (827kPag). In particular, when the pyrolysis feed includes a diluent, the average total pressure may be ≥10.34 barg (1034 kPag), or ≥20.68 barg (2068 kPag), or ≥34.47 barg (3447 kPag). The total gas residence time in the pyrolysis zone is typically ≤0.2 seconds; preferably ≤0.15 seconds or ≤0.1 seconds; or in the range of 0.001 seconds to 0.4 seconds, or in the range of 0.01 seconds to 0.4 seconds, or in the range of 0.01 seconds to 0.2 seconds. For example, the pyrolysis feed can be passed through the hot mass 1 at a bulk gas temperature of ≥ 800°C with a total gas residence time of ≤ 0.100 seconds, such as ≤ 0.060 seconds, such as ≤ 0.040 seconds, or in the range of 0.001 seconds to 0.100 seconds, or in the range of 0.002 seconds to 0.060 seconds, or in the range of 0.002 seconds to 0.040 seconds. Typically, for t P≥1 second, for example ≥2 seconds, such as ≥5 seconds, or ≥10 seconds, or ≥20 seconds, or ≥30 seconds, or even ≥1 minute or longer, T p and / or T av ≤ 100K, for example ≤ 75K, such as ≤ 50K, or ≤ 25K, or ≤ 10K, or ≤ 5K. Although high severity pyrolysis conditions can be used, it is typical to use low severity conditions. Regions of substantially constant temperature along the length of the pyrolysis zone are generally avoided. Sharp gradients in the bulk gas temperature profile within the pyrolysis zone are also generally avoided.

[0105] When hope is in P Keep T during p and / or T av At least the OFA of the thermal mass 1 should be ≤55%, such as ≤45%, such as ≤40%, or ≤35% without decreasing by more than about 100K, preferably ≤75K. Typically, the OFA of the thermal mass 1 is in the range of about 10% to 55%, such as 10% to 50%, such as 10% to 45%, or 10% to 35%. At larger T p At values ​​(e.g., ≥1273K, e.g., ≥1473K or ≥1573K), a smaller OFA value is generally desired, which results in a smaller value at t P Temperature during the period T p and T av For example, when T av Above 1173K, it is beneficial for thermal masses to have an OFA of ≤ 45%. av Above 1273K, it is beneficial for the thermal mass to have an OFA of ≤ 35%, and when T av Above 1373 K, it is beneficial for thermal masses to have an OFA of ≤ 25%. In other words, when T p When it exceeds 1273K, ΔT p and / or ΔT av ≤50K is beneficial when T p When it exceeds 1372K, ΔT p and / or ΔT av ≤40K is beneficial when T p When it exceeds 1473K, ΔT p and / or ΔT av ≤20K is beneficial.

[0106] Duration of pyrolysis mode operation t P It may be, for example, ≥1 second, such as ≥2 seconds, or ≥5 seconds, or ≥10 seconds, or ≥20 seconds, or ≥30 seconds, or even ≥1 minute or longer. P It may be in the range of 1 second to 30 seconds, such as 2 seconds to 15 seconds, such as 2 seconds to 10 seconds. Optionally, conventional methods are used to achieve these t Prange, such as using one or more poppet valves and / or fluid power valves to regulate the flow of feed and process gas during the pyrolysis mode and the flow of the heating mixture and combustion products during the regeneration mode.

[0107] In these longer t P During the period of , the bulk gas temperature profile of the reactor generally maintains a substantially constant shape (although decreasing in magnitude). Figure 3 The solid line represents the bulk gas temperature distribution at the beginning of the pyrolysis mode (t1), and the dashed line represents the bulk gas temperature distribution at the end of the pyrolysis mode (t2). At any time during the pyrolysis period, the length ≤ l C The change in bulk gas temperature within any pyrolysis zone segment of 10% is typically ≤140K, such as ≤100K, such as ≤50K. Typically, within a length of ≤l B In any section of 10% of the hot mass 1, the temperature variation is ≤75K, such as ≤50K, such as ≤25K. In certain aspects, the peak gas temperature during pyrolysis T p The downstream section of the pyrolysis zone is shifted away from the center of the reactor. A The length is less than the upstream section l B The total length of the pyrolysis zone is l, for example, at least 10% smaller, for example at least 25% smaller, or at least 50% smaller. C Yes A and l B Usually, l C In the range of 10% to 50% of the total length of the reactor 50, for example in the range of 20% to 40%. c It can be in the range of 20% to 40% of L1+L2+L3+L4. A and l B The position of the end of the pyrolysis reaction is determined by the minimum temperature T required for significant (≥10 wt%) conversion of the selected feed under the specified pyrolysis conditions. MIN OK, for example T MIN In the range of 773K to 1273K.

[0108] In some aspects, such as Figure 3 As shown, the bulk gas temperature distribution at the beginning of pyrolysis increases substantially monotonically from a first temperature (T1) near the first hole 3 of the hot mass 1 to a second temperature (T2) near the second hole 5. The peak gas temperature T at a position at or downstream of the face 5 is p Greater than T2. ​​T when pyrolysis starts p -T2 is usually in the range of 10K to 400K, or 25K to 300K, or 50K to 200K. p The amount of temperature reduction ≤100°C during pyrolysis (ΔT p ). Usually, Tp The position within the pyrolysis zone remains substantially constant during pyrolysis. In this case, substantially constant means that during the pyrolysis mode T p The position changes from its initial position to l c ≤+ / -20%, such as ≤+ / -15%, such as ≤+ / -10%, or typically ≤+ / -5%. T1 is less than T2 during pyrolysis, for example, T1 at the beginning of pyrolysis can be ≤1673K, such as ≤1573K, such as ≤1473K, or ≤1373K, or ≤1273K. T2-T1 at the beginning of pyrolysis is typically in the range of 50K to 500K, such as 100K to 400K, or 100K to 300K. In a specific aspect, the pyrolysis conditions at the beginning of pyrolysis include T1≤1173K, such as ≤1023K, such as ≤773K; T2 is in the range of 1248K to 1373K, T p ≥1423K, and T MIN -T1 is in the range of 10K to 400K, or 25K to 300K, or 50K to 200K. P The initial bulk gas temperature distribution and t P The bulk gas temperature distribution at the end is basically the same, but at t P During this period, the position in the pyrolysis zone where significant pyrolysis is achieved is translated from the reference position R1 toward the hole 5 to t P The reference position R2 at the end (t=t2). At t2, the bulk gas temperature distribution increases substantially monotonically from a first temperature (T3) near the first hole 3 to a second temperature (T4) near the second hole 5. T3≤T1, and T4 is in the range from T2 to (T2-100K), for example, T2 to (T2-75K), for example, T2 to (T2-50K). The reference position R1 is positioned, for example, within 0.2×L1 and 0.4×L1 of the second hole.

[0109] The process gas removed from the reactor during the pyrolysis mode contains a range of desired hydrocarbon products, including a desired range of C2-C5 olefins. Typically, one or more of the desired hydrocarbon compounds are separated from the process gas, for example for storage and / or further processing. Typically, the process gas contains molecular hydrogen; methane; ethane; ethylene; propane; propylene; butane; butene; butadiene; C5 hydrocarbons, including normal, iso and cyclic C5 olefins and paraffins, and C 6+ Hydrocarbons, including aromatic compounds and normal, iso and cyclic C 6+Olefins and paraffins. For example, particularly when the feed includes ethane, the pyrolysis product can contain 2 wt % to 10 wt % methane, 50 wt % to 95 wt % ethylene, 0.2 wt % to 1 wt % propylene, 0.1 wt % to 5 wt % butadiene, and up to about 3 wt % benzene, based on the weight of the pyrolysis product. As can be appreciated, these highly desirable compositional ranges of the identified hydrocarbon compounds are achieved not only at the start of the pyrolysis mode, but also at t P is achieved during the duration of

[0110] The process gas is compressed in at least one compression stage comprising at least one process gas compressor. The process gas compressor utilizes at least a portion of the first shaft power and the second shaft power generated by the generator. Suitable process gas compressors will now be described in more detail. The present invention is not limited to these compressors, and this description is not meant to exclude the use of other compressors within the broader scope of the present invention.

[0111] Alternative Configuration - Steam Cracking

[0112] Another option for performing the pyrolysis reaction is to use a conventional steam cracker configuration. A steam cracking furnace generally includes a convection section and a radiant section. The radiant section includes a plurality of tubular members commonly referred to as "radiant tubes". Traditionally, the radiant tubes are located near one or more combustion heaters (e.g., burners) that heat the outer surface of the furnace tubes in the radiant section. This radiant section corresponds to the combustion zone of the furnace. The hot combustion gases leave the radiant section and are introduced into the convection section. The convection section also includes tubular members, commonly referred to as "convection tubes". The hot gases from the radiant section heat the outer surface of the convection tubes and then leave the convection section.

[0113] Conventional steam cracking methods usually produce light olefins by pyrolysis of hydrocarbons during pyrolysis mode. Coke and other deposits formed during pyrolysis mode are removed from the furnace interior during regeneration (decoking) mode. During pyrolysis mode, hydrocarbon-containing feed is introduced into a convection tube for feed preheating. Feed preheating is carried out in a convection tube section located in the upper region of the convection section. Steam is combined with the preheated feed, and the steam-feed mixture is further heated in a convection tube section located in the lower region of the convection section. The heated feed-steam mixture is introduced into the heated furnace tube in the radiant section, and the heat transferred from the furnace tube to the mixture causes at least a portion of the feed to be pyrolyzed to produce a process gas containing light olefins. During regeneration mode, the hydrocarbon-containing feed is replaced by a stream of a decoking fluid (e.g., a gaseous steam-air mixture) containing oxygenates, and the burner continues to heat the radiant section and the convection section. The decoking fluid is directed through the heated convection tubes, heated radiant tubes and associated furnace piping, internals, etc. to at least partially remove the deposited coke. After sufficient coke removal is achieved, the steam cracking furnace is returned to pyrolysis mode operation.

[0114] Representative process gas compressors

[0115] In the compressor stage, the process gas is typically compressed to a pressure of 20 bar (2000 kPa) to 40 bar (4000 kPa) in a centrifugal compressor powered by shaft power. Typically, the process gas compressor comprises at least four stages, each stage sequentially providing a pressure increase over its previous stage. Cooling is typically employed between the stages, for example to prevent compressor damage, to prevent fouling caused by diene polymerization, and to facilitate separation of process gas components. The present invention is compatible with conventional process gas compressors, but the invention is not limited thereto.

[0116] All patents, test procedures and other documents cited herein, including priority documents, are fully incorporated by reference to the extent that they are not inconsistent with such disclosure. Therefore, the scope of the claims attached to this specification is not considered to be limited to the embodiments and descriptions given here, but the claims are considered to include all features of novelty that can obtain patent rights in this article, including all other features that are considered to be equivalent to these features by a person skilled in the art of the relevant technology of the present invention. When a lower limit and an upper limit are specified, the range from any lower limit to any upper limit is clearly within the scope of the present invention. The term "comprising" and the term "including" are synonymous. When a composition, element or group of components is preceded by the transitional phrase "comprising", the same composition or group of components is preceded by the transitional phrase "essentially composed of", "consisting of", "selected from" or "is" before the description of the composition, component or multiple components, and vice versa. Unless explicitly indicated as a gauge pressure (barg, kPag, psig), the pressure value is absolute (bar, kPa, psi or psia).

Claims

1. A method for producing and compressing a process gas, the method comprising: separating air to form at least an oxygen-containing stream, the oxygen-containing stream comprising 90% by volume or more O2; combusting at least a portion of the fuel with at least a portion of the oxygen-containing stream in the presence of at least a portion of a circulating stream comprising 80% by volume or more CO2 to produce a heated working fluid; expanding the heated working fluid to generate shaft power and a depressurized working fluid comprising at least CO2 and H2O; pyrolyzing at least a portion of a hydrocarbon-containing feed to produce a process gas comprising ethylene; Separating the depressurized working fluid to form a water stream and a CO2-containing stream by performing a series of cooling and compression steps, wherein the CO2 in the depressurized working fluid and the CO2-containing stream is in a supercritical state during the series of cooling and compression steps; transferring at least a portion of the shaft power a) to a process gas compressor to compress the process gas, b) to a refrigeration compressor to cool the process gas, c) to a refrigeration compressor to cool the decompressed working fluid in a cooling step from the series of cooling and compressing steps, or d) a combination of two or more of a), b) and c); and At least a portion of the CO 2 -containing stream is compressed to form a compressed CO 2 -containing stream, and the recycle stream comprises at least a first portion of the compressed CO 2 -containing stream.

2. The method of claim 1, wherein the depressurized working fluid comprises 90 vol% or more of CO2 and H2O.

3. The method of claim 1, wherein the transfer of shaft power comprises direct power transfer, indirect power transfer, or a combination thereof.

4. The method of any one of claims 1 to 3, wherein the fuel comprises one or more of the following: (i) natural gas, (ii) hydrocarbons in the natural gas, (iii) hydrocarbons separated from and / or derived from the natural gas, (iv) natural gas condensate, (v) hydrocarbons in the natural gas condensate, (vi) hydrocarbons separated from and / or derived from the natural gas condensate, (vii) crude oil, (viii) hydrocarbons in the crude oil, (viii) hydrocarbons separated from and / or derived from the crude oil, and (ix) molecular hydrogen.

5. The process of any one of claims 1 to 3, wherein the feed comprises >10 wt% C 2+ hydrocarbon.

6. The process of any one of claims 1 to 3, wherein the compressed CO2-containing stream comprises a pressure of 200 bar or more.

7. The method of any one of claims 1 to 3, wherein the depressurized working fluid comprises a pressure of 60 bar or less.

8. The method of any one of claims 1 to 3, wherein at least a portion of the shaft power is delivered a) to a process gas compressor to compress the process gas, b) to a refrigeration compressor to cool the process gas, or e) a combination of a) and b).

9. The method of any one of claims 1 to 3, further comprising transferring at least a second portion of the shaft power to a compressor for i) performing the compression in the series of cooling and compression steps, ii) refrigeration to perform at least a portion of the cooling in the series of cooling and compression steps, iii) performing compression of the CO2-containing stream, or iv) a combination of two or more of i), ii) and iii).

10. The process of any one of claims 1 to 3, wherein the pyrolysis is carried out in at least one steam cracking furnace.

11. The process of any one of claims 1 to 3, wherein the pyrolysis is performed in at least one countercurrent pyrolysis reactor.

12. The method of any one of claims 1 to 3, wherein the fuel comprises at least a portion of tail gas recovered from the process gas.

13. The process of any one of claims 1 to 3, wherein at least a portion of the water stream is (i) fed to the pyrolysis step to mix with the hydrocarbon-containing feed; (ii) heated to generate steam; (iii) used as an indirect cooling medium; (iv) used as a quenching medium; and (iv) fed to the hydrocarbon-containing stream as a diluent.

14. The method of any one of claims 1 to 3, further comprising: recovering an ethylene stream from the process gas; contacting at least a portion of the ethylene stream with at least a portion of the oxygenated stream to produce an oxygenated stream; and A monoethylene glycol product is produced from the oxidized stream.

15. The process of claim 14, wherein the oxidized stream comprises ethylene oxide and the step of producing the monoethylene glycol product comprises contacting the ethylene oxide with CO2 derived from the compressed CO2 stream and / or the CO2-containing stream.

16. The method of claim 15, further comprising at least one of the following steps: supplying a portion of the compressed CO2 stream to a storage device; carrying away a portion of the compressed CO2 stream in a pipeline; A portion of the compressed CO 2 stream is used to extract a hydrocarbon source material, and at least a portion of the hydrocarbon-containing feed is derived from the hydrocarbon source material.

17. The process of any one of claims 1 to 3, wherein the pyrolysis is carried out under pyrolysis conditions comprising a temperature in the range of 773 K to 1773 K, a total pressure of ≥ 34 kPag, and a hydrocarbon partial pressure of ≥ 48 kPa.

18. The method of any one of claims 1 to 3, further comprising: P A pyrolysis step is performed, and at time intervals t R During this period, the countercurrent pyrolysis reactor is regenerated, wherein t P and t R are essentially non-overlapping time intervals.

19. The method of any one of claims 1 to 3, wherein combusting at least a portion of the fuel comprises combusting a first portion of the fuel with a first portion of the oxygen-containing stream in the presence of a first portion of the circulating stream in a first combustion zone to produce a first heated working fluid, and combusting a second portion of the fuel with a second portion of the oxygen-containing stream in the presence of a second portion of the circulating stream in a second combustion zone to produce a second heated working fluid, wherein the first heated working fluid is expanded to generate a first shaft power, and Wherein the second heated working fluid is expanded to generate a second shaft power.

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