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US-12624295-B2 - Hydrocarbon pyrolysis with less exhaust emission

US12624295B2US 12624295 B2US12624295 B2US 12624295B2US-12624295-B2

Abstract

Processes, systems, and apparatus are provided for using a common working fluid for one or more turbines for processing a process gas and for the furnace for the pyrolysis process used to produce the process gas. The turbine(s) are operated based on a modified Allam cycle to produce power for operating one or more compressors and/or refrigerators involved in processing of the process gas while producing a reduced or minimized amount of CO 2 that is released as a low-pressure gas phase product. Integrating the pyrolysis furnace with the working fluid loop can provide further benefits.

Inventors

  • Mark A. Rooney
  • Thomas T. Hirst

Assignees

  • EXXONMOBIL CHEMICAL PATENTS INC.

Dates

Publication Date
20260512
Application Date
20201218
Priority Date
20200406

Claims (17)

  1. 1 . A process for performing pyrolysis, comprising: separating from air at least an oxygen-containing stream, the oxygen-containing stream comprising 90 vol. % or more O 2 ; combusting a first fuel with a first portion of the oxygen-containing stream in the presence of at least a portion of a recycle stream at a pressure of 10 MPa-a or more to produce a heated working fluid, the recycle stream comprising 80 vol. % or more CO 2 ; operating a turbine using the heated working fluid to produce power and an intermediate working fluid comprising at least CO 2 and H 2 O; combusting a second fuel with a second portion of the oxygen-containing stream in the presence of the intermediate working fluid to form a heated intermediate working fluid; exposing the heated intermediate working fluid to a plurality of furnace tubes in a pressurized pyrolysis environment to transfer heat to the plurality of furnace tubes and produce a depressurized working fluid comprising a pressure of 800 kPa-a to 3000 kPa-a; pyrolyzing at least a portion of a hydrocarbon-containing feed in the plurality of furnace tubes to form a pyrolysis effluent comprising at least a process gas comprising ethylene; transferring at least part of the produced 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 depressurized working fluid in a cooling step in a series of cooling and compressing steps, or d) a combination of two or more of a), b) and c); performing the series of cooling and compressing steps on the depressurized working fluid to form a water stream and a CO 2 -containing stream, the CO 2 in the depressurized working fluid and the CO 2 -containing stream being in a single phase during the series of cooling and compressing steps; and compressing at least a portion of the CO 2 -containing stream to form a compressed CO 2 -containing stream, the recycle stream comprising at least a first portion of the compressed CO 2 -containing stream.
  2. 2 . The process of claim 1 , wherein the depressurized working fluid comprises 90 vol. % or more of CO 2 and H 2 O.
  3. 3 . The process of claim 1 , wherein compressing at least a portion of the process gas using the produced power comprises direct power transfer of the produced power, indirect power transfer of the produced power, or a combination thereof.
  4. 4 . The process of claim 1 , wherein at least one of the first fuel and the second fuel comprises a tail gas formed from the compressed process gas.
  5. 5 . The process of claim 1 , wherein the at least one of the first fuel and the second fuel comprises one or more of (i) natural gas, (ii) hydrocarbon in the natural gas, (iii) hydrocarbon separated from the natural gas and/or derived from the natural gas, (iv) natural gas condensate, (v) hydrocarbon in the natural gas condensate, (vi) hydrocarbon separated from the natural gas condensate and/or derived from the natural gas condensate, (vii) crude oil, (viii) hydrocarbon in the crude oil, (viii) hydrocarbon separated from the crude oil and or derived from the crude oil, and (ix) molecular hydrogen.
  6. 6 . The process of claim 1 , wherein the feed comprises >10 wt. % C 2+ hydrocarbon.
  7. 7 . The process of claim 1 , wherein the compressed CO 2 -containing stream comprises a pressure of 10 MPa-a or more.
  8. 8 . The process of claim 1 , wherein the intermediate working fluid comprises a pressure of 3000 kPa-a to 6000 kPa-a.
  9. 9 . The process of claim 1 , further comprising transferring at least a second portion of the produced power to a compressor for i) performing the compressing in the series of cooling and compressing steps, ii) performing the compressing of the CO 2 -containing stream, or iii) a combination of i) and ii).
  10. 10 . The process of claim 1 , wherein the pyrolyzing of the feed comprises pyrolyzing the feed under steam cracking conditions.
  11. 11 . The process of claim 1 , wherein the recycle stream comprises 95 vol % or more CO 2 .
  12. 12 . The method of claim 1 , further comprising performing heat exchange between the at least a portion of the depressurized working fluid and at least a portion of the recycle stream.
  13. 13 . The method of claim 1 , further comprising performing heat exchange between at least a portion of the pyrolysis effluent and at least a portion of the feed.
  14. 14 . The process of claim 1 , wherein at least a portion of the water stream is (i) fed into the pyrolyzing 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 into a hydrocarbon-containing stream as a diluent.
  15. 15 . The process of claim 1 , 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 oxygen-containing stream to produce an oxidized stream; and producing a monoethylene glycol product from the oxidized stream.
  16. 16 . The process of claim 15 , wherein the oxidized stream comprises ethylene oxide, and the step of producing the monoethylene glycol product comprises contacting the ethylene oxide with the CO 2 sourced from the compressed CO 2 stream and/or the CO 2 -containing stream.
  17. 17 . The process of claim 1 , further comprising at least one of the following: supplying a portion of the compressed CO 2 stream to a storage; conducting away a portion of the compressed CO 2 stream in a pipeline; using a portion of the compressed CO 2 stream to extract a hydrocarbon source material, and deriving at least a portion of the hydrocarbon-containing feed from the hydrocarbon source material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a US national phase application of PCT Application Serial No. PCT/US2020/066177 having a filing date of Dec. 18, 2020, which claims priority to and the benefit of U.S. Provisional Application No. 62/954,783 having a filing date of Dec. 30, 2019 and European Patent Application No. 20168291.1 having a filing date of Apr. 6, 2020, the disclosures of all of which are incorporated herein by reference in their entireties. FIELD The invention relates to lessening exhaust emission from hydrocarbon pyrolysis, to processes for carrying out hydrocarbon pyrolysis with less exhaust emission, to integrated systems for carrying out such processes, to certain exhaust products of the hydrocarbon pyrolysis, and to certain hydrocarbon pyrolysis products. BACKGROUND Hydrocarbon pyrolysis processes, e.g., steam cracking, produce commercially-important amounts of useful products and co-products, such as saturated and unsaturated hydrocarbon. Certain pyrolysis products, e.g., C4− olefin, are particularly useful as feedstock for petrochemical processes, e.g., polymerization processes, Pyrolysis processes such as steam cracking use a considerable amount of energy. Since hydrocarbon pyrolysis is highly endothermic, energy is needed to “crack” large hydrocarbon molecules, to produce a pyrolysis effluent comparing molecular hydrogen and desirable hydrocarbon products such as light olefin. The pyrolysis effluent is typically compressed and cooled to facilitate separation and recovery from the pyrolysis effluent of the desired products and co-products, which requires still more energy, e.g., for turbomachinery and refrigeration equipment. When at least apportion of this energy is produced by hydrocarbon combustion, an appreciable amount of exhaust (typically comprising CO2) is emitted, typically as flue gas. Difficulties have been encountered during attempts to process the exhaust emissions. For example, the high temperatures needed for hydrocarbon pyrolysis (typically at least 700° C.) have been found to limit opportunities to recover and use heat from the combustion exhaust. Alternate approaches to supply the energy through renewable means (e.g. renewable electricity) do not yet have the capacity to supply world demand, let alone the technology solutions to do so. Therefore, pyrolysis processes such as steam cracking can produce an undesirable amount of exhaust emissions, particularly exhaust emissions containing CO2. Moreover, certain hydrocarbon pyrolysis processes, e.g., steam cracking, produce a pyrolysis effluent that itself contains an appreciable amount of CO2. Attempts have been made to decrease the amount of CO2 and other greenhouse gas (“GHG”) emitted by pyrolysis processes and associated combustion processes. Aside from prudent efficiency steps, the only state of the art methods to reduce these emissions have been by using gas treating technology such as an amine treatment to remove CO2 from the combustion exhaust (e.g., from steam cracker furnace flue gas) and from the pyrolysis effluent. Although this technique is efficient and cost-effective for removing CO2 from the pyrolysis effluent, it is impractical for removing CO2 from combustion exhaust emitted by pyrolysis facilities such as steam cracking facilities. It has been found, for example, that the dilute nature of the exhaust gas (e.g., flue gas) results in the amine treatment corresponding to a sizeable fraction of the overall cost of producing the desired pyrolysis products. There is therefore a need for pyrolysis processes having less exhaust emission, and particularly less CO2 exhaust emission. There is a particular need for steam cracking processes having less CO2 exhaust emission. Light olefin such as ethylene is typically manufactured in an olefins plant (e.g., a steam cracker plant) which includes production (pyrolysis) facilities and recovery facilities. In certain conventional olefins plants, the olefin production facility includes one or more steam cracker furnaces for steam cracking hydrocarbon-containing feeds. A steam cracker furnace generally includes a convection section and a radiant section. The radiant section includes a plurality of tubular members which are typically referred to as “radiant tubes”. Conventionally, the radiant tubes are located proximate to one or more fired heaters, e.g., burners, in the radiant section which heat the outer surface of the furnace tubes. Hot combustion gases exit the radiant section and are introduced into the convection section. The convection section also includes tubular members, typically referred to as “convection tubes”. The hot gases from the radiant section heat the outer surfaces of the convection tubes and then exit the convection section. Conventional steam cracking processes typically produce light olefin by hydrocarbon pyrolysis during pyrolysis mode. Coke and other deposits which form during pyrolysis mode are removed from the furnace interna