Integrated ethylene production process
The invention relates to a process for the production of ethylene in an integrated configuration comprising (i) a steam cracker configuration which comprises a steam cracker unit, a water condensation unit and a carbon dioxide removal unit and (ii) an oxidative dehydrogenation (ODH) configuration which comprises an ODH unit and a water condensation unit, wherein an effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, is fed to the steam cracker configuration at a position which is downstream of the steam cracker unit, and wherein unconverted oxygen, carbon monoxide and acetylene are removed from at least a portion of the stream coming from the ODH unit by oxidation of carbon monoxide and acetylene into carbon dioxide in an oxidation unit which is located at a position (a) which is downstream of the ODH unit, and (b) which is downstream of the steam cracker unit and upstream of the carbon dioxide removal unit of the steam cracker configuration.
1. Process for the production of ethylene in an integrated configuration comprising a steam cracker configuration and an oxidative dehydrogenation (ODH) configuration, wherein the steam cracker configuration comprises a steam cracker unit, a water condensation unit and a carbon dioxide removal unit and the ODH configuration comprises an ODH unit and a water condensation unit, which process comprises the following steps:
subjecting a stream comprising saturated hydrocarbons to steam cracking conditions in the steam cracker unit, resulting in a stream comprising water, unconverted ethane, ethylene, acetylene, hydrogen, methane, carbon monoxide, carbon dioxide and C3+ hydrocarbons;
feeding at least a portion of the stream coming from the steam cracker unit to the water condensation unit of the steam cracker configuration, and removing water and a portion of the C3+ hydrocarbons from said stream by condensation in the water condensation unit, resulting in a stream comprising unconverted ethane, ethylene, acetylene, hydrogen, methane, carbon monoxide, carbon dioxide and C3+ hydrocarbons;
subjecting a stream comprising ethane and oxygen to oxidative dehydrogenation (ODH) conditions in the ODH unit, resulting in a stream comprising unconverted ethane, ethylene, acetylene, unconverted oxygen, water, carbon monoxide and carbon dioxide;
feeding at least a portion of the stream coming from the ODH unit to the water condensation unit of the ODH configuration, and removing water from said stream by condensation in the water condensation unit, resulting in a stream comprising unconverted ethane, ethylene, acetylene, unconverted oxygen, carbon monoxide and carbon dioxide;
feeding an effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, to the steam cracker configuration at a position which is downstream of the steam cracker unit;
removing unconverted oxygen, carbon monoxide and acetylene from at least a portion of the stream coming from the ODH unit by oxidation of carbon monoxide and acetylene into carbon dioxide in an oxidation unit which is located at a position (a) which is downstream of the ODH unit, and (b) which is downstream of the steam cracker unit, and upstream of the carbon dioxide removal unit of the steam cracker configuration;
feeding a stream comprising unconverted ethane, ethylene, optionally acetylene, hydrogen, methane, optionally carbon monoxide, carbon dioxide and C3+ hydrocarbons to the carbon dioxide removal unit of the steam cracker configuration, and removing carbon dioxide from said stream in the carbon dioxide removal unit of the steam cracker configuration, resulting in a stream comprising unconverted ethane, ethylene, optionally acetylene, hydrogen, methane, optionally carbon monoxide and C3+ hydrocarbons; and
recovering unconverted ethane and ethylene from at least a portion of the stream coming from the carbon dioxide removal unit of the steam cracker configuration and optionally from at least a portion of the effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, which is fed to the steam cracker configuration at a position which is downstream of the carbon dioxide removal unit of the steam cracker configuration.
2. The process according to claim 1 , wherein the oxidation unit is part of the steam cracker configuration and is located at a position (a) which is downstream of the position at which the effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, is fed to the steam cracker configuration, wherein said effluent additionally comprises acetylene, unconverted oxygen, carbon monoxide and optionally carbon dioxide, and (b) which is upstream of the carbon dioxide removal unit of the steam cracker configuration.
3. The process according to claim 1 , wherein the oxidation unit is part of the ODH configuration and is located at a position (a) which is upstream or downstream, and (b) which is upstream or downstream, of an optional carbon dioxide removal unit of the ODH configuration, and (c) which is upstream of the position at which the effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, is fed to the steam cracker configuration, wherein said effluent additionally comprises optionally carbon dioxide.
4. The process according to claim 1 , wherein saturated hydrocarbons are fed to the steam cracker unit which comprise one or more of ethane, propane, butane, liquefied petroleum gas (LPG), naphtha, hydrowax and recycled waste plastics oil.
5. The process according to claim 1 , wherein ethane is fed to the ODH unit which originates from one or more sources selected from the group consisting of a) a source of fresh ethane that is used to feed ethane to the steam cracker unit; b) another source of fresh ethane, other than said first source mentioned under a); and c) unconverted ethane as recovered in the process according to claim 1 .
6. The process according to claim 1 , wherein the steam cracker configuration additionally comprises a 1 st separation unit, and the effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, is fed to the steam cracker configuration at a position which is upstream of the 1 st separation unit, and the process additionally comprises the following steps:
feeding at least a portion of the stream coming from the carbon dioxide removal unit of the steam cracker configuration and optionally at least a portion of the effluent coming from the ODH configuration, which effluent comprises unconverted ethane and ethylene, which is fed to the steam cracker configuration at a position which is downstream of the carbon dioxide removal unit of the steam cracker configuration, to the 1 st separation unit; and separating said stream or streams in the 1 st separation unit into a stream comprising hydrogen, methane and optionally carbon monoxide and a stream comprising C3+ hydrocarbons.
7. The process according to claim 6 , wherein the steam cracker configuration additionally comprises a C2 separation unit, and the process additionally comprises the following steps:
feeding unconverted ethane and ethylene from a stream comprising unconverted ethane, ethylene, optionally acetylene, hydrogen, methane, optionally carbon monoxide and C3+ hydrocarbons to the C2 separation unit; and
separating said stream in the C2 separation unit into a stream comprising ethylene and a stream comprising unconverted ethane;
wherein:
unconverted ethane and ethylene from the stream comprising unconverted ethane and ethylene coming from the water condensation unit of the ODH configuration are fed to the C2 separation unit.
8. The process according to claim 7 , wherein the steam cracker configuration additionally comprises a 2 nd separation unit, and the process additionally comprises the following steps:
1) In a first embodiment:
separating a stream comprising unconverted ethane, ethylene, optionally acetylene, hydrogen, methane, optionally carbon monoxide and C3+ hydrocarbons in the 1 st separation unit into a stream comprising hydrogen, methane and optionally carbon monoxide and a stream comprising C2+ hydrocarbons, which C2+ hydrocarbons comprise unconverted ethane, ethylene, optionally acetylene and C3+ hydrocarbons;
feeding at least a portion of the separated stream comprising C2+ hydrocarbons coming from the 1 st separation unit to the 2 nd separation unit wherein said stream is separated into a stream comprising C2 hydrocarbons, which C2 hydrocarbons comprise unconverted ethane, ethylene and optionally acetylene, and a stream comprising C3+ hydrocarbons; and
feeding unconverted ethane and ethylene from the separated stream comprising C2 hydrocarbons coming from the 2 nd separation unit to the C2 separation unit wherein they are separated into a stream comprising ethylene and a stream comprising unconverted ethane; or
2) In a second embodiment:
separating a stream comprising unconverted ethane, ethylene, optionally acetylene, hydrogen, methane, optionally carbon monoxide and C3+ hydrocarbons in the 1 st separation unit into a stream comprising hydrogen, methane, optionally carbon monoxide and C2 hydrocarbons, which C2 hydrocarbons comprise unconverted ethane, ethylene and optionally acetylene, and a stream comprising C3+ hydrocarbons;
feeding at least a portion of the separated stream comprising hydrogen, methane, optionally carbon monoxide and C2 hydrocarbons coming from the 1 st separation unit to a 2 nd separation unit wherein said stream is separated into a stream comprising hydrogen, methane and optionally carbon monoxide and a stream comprising C2 hydrocarbons; and
feeding unconverted ethane and ethylene from the separated stream comprising C2 hydrocarbons coming from the 2 nd separation unit to the C2 separation unit wherein they are separated into a stream comprising ethylene and a stream comprising unconverted ethane.
9. The process according to claim 1 , wherein the stream coming from the carbon dioxide removal unit of the steam cracker configuration comprises acetylene, and the steam cracker configuration additionally comprises an acetylene removal unit, and the process additionally comprises the following step:
an acetylene removal step wherein in the acetylene removal unit acetylene is removed from a stream comprising acetylene, ethylene and optionally unconverted ethane.