CN-122029258-A - Furnace having an electrically heated convection section and steam cracking process using such an electric furnace

CN122029258ACN 122029258 ACN122029258 ACN 122029258ACN-122029258-A

Abstract

The present disclosure includes a convection bank for a steam cracker, wherein the convection bank includes a convection housing and one or more electric heaters disposed between an inlet of the convection housing and a plurality of heat exchangers disposed in channels of the convection housing. Some such convection banks include a duct and a fan configured to circulate gas through the duct from an outlet to an inlet of the convection enclosure. The present disclosure also includes a steam cracking system wherein the convection section of the steam cracker includes one of the convection banks of the present invention. The present disclosure also includes steam cracking processes wherein an electric heater is used to heat the heat transfer gas as it enters or before the convection bank of the steam cracker and processes including electrification of the convection section of the steam cracker.

Inventors

A, J, M, Austria, Prince

Assignees

SABIC环球技术有限责任公司

Dates

Publication Date: 20260512
Application Date: 20241008
Priority Date: 20231016

Claims (15)

1. A convection bank for a steam cracker, the convection bank comprising: A convective bank housing having an inlet and an outlet, and an internal conduit within the convective bank housing extending from the inlet to the outlet; A plurality of heat exchangers positioned in the inner conduit between the inlet and the outlet, and One or more electric heaters positioned in the inner conduit between the inlet and the plurality of heat exchangers, the one or more electric heaters configured to heat transfer gas circulated through the inner conduit to a desired operating temperature within the convective bundle housing.
2. The convection bank of claim 1, wherein the plurality of heat exchangers comprises at least one feed preheater for heating a hydrocarbon feedstock and at least one mixture preheater for heating a mixture of steam and the hydrocarbon feedstock.
3. The convective bank of any of claims 1-2, further comprising: an outer tube positioned outside of the convective bank shell and in fluid communication with the inlet and the outlet, and A fan configured to circulate gas from the outlet through the external conduit to the inlet.
4. A steam cracking system, comprising: A steam cracker comprising a radiant section and a convection section, the radiant section comprising a radiant housing defining a heating chamber having one or more electrical heating elements and a tubular reactor, the radiant section configured to heat a mixture of steam and hydrocarbon feedstock to a cracking reaction temperature; A transfer line heat exchanger coupled to the outlet of the tubular reactor and configured to quench the heated mixture to a temperature below the cracking reaction temperature; a second mixture preheater coupled between the convection section and the tubular reactor; Wherein: The convection section of the furnace comprising a convection bank according to any of claims 1 to 3, the convection bank comprising at least one first mixture preheater for heating the mixture prior to delivery to the tubular reactor, and The second mixture preheater is configured to further heat the mixture prior to delivering the mixture to the tubular reactor.
5. The steam cracking system of claim 4, wherein the second mixture preheater is electrically driven.
6. The steam cracking system of any of claims 4 to 5, wherein the one or more electric heaters are configured to heat the heat transfer gas circulated through the inner conduit to a temperature of 150 ℃ to 850 ℃, optionally 300 ℃ to 850 ℃ or 700 ℃ to 850 ℃.
7. The steam cracking system of any of claims 4 to 6, wherein the heating chamber of the radiant housing is not in fluid communication with the inner conduit of the convective bank housing.
8. The method comprises the following steps: heating the heat transfer gas with the one or more electric heaters as it enters the inner conduit of the convective bank shell of claim 1; extracting heat energy from the heat transfer gas as it flows through the inner conduit within the plurality of heat exchangers in the convective bank, and The heat transfer gas is recycled from the outlet to the inlet to continue the heating and extraction steps.
9. The method of claim 8, wherein the heat transfer gas comprises atmospheric air.
10. The method of any of claims 8-9, further comprising: A mixture of steam and hydrocarbon feedstock is heated with at least one mixing preheater of the plurality of heat exchangers.
11. The method of claim 10, wherein the mixture is partially heated in at least one of the plurality of heat exchangers, and the method further comprises: the partially heated mixture is further heated with a process heater external to the convection bank.
12. The method of claim 12, further comprising: in a dilution steam heater of the plurality of heat exchangers, heating fluid water to generate superheated steam, and The superheated steam is mixed with the mixture before further heating the mixture.
13. The method of any of claims 10-12, further comprising: The heated mixture is directed into a tubular reactor within an electrically heated chamber of a radiant section of the furnace to raise the temperature of the mixture to the cleavage reaction temperature.
14. The method of claim 13, further comprising: directing the mixture from the tubular reactor to a transfer line heat exchanger (TLE) to quench the mixture to a temperature below the cracking reaction temperature, and Steam is directed from the TLE to one or more steam superheaters of the plurality of heat exchangers to superheat the steam.
15. A method of electrifying a convection section of a steam cracker having a radiant section in fluid communication with the convection section, the convection section having an inlet, an outlet, and a plurality of heat exchangers positioned between the inlet and the outlet, the method comprising: removing in the convection section those of the plurality of heat exchangers that are configured to receive thermal energy from flue gas having a gas temperature above an operating temperature during operation of the steam cracker prior to electrification; Positioning one or more electric heaters within the convection section, wherein those of the plurality of heat exchangers have been removed such that the electric heaters are operable to be actuated to deliver heated heat transfer gas from the inlet through the convection section to the outlet to provide thermal energy to the remaining heat exchangers in the convection section; Optionally, providing one or more conduits from the outlet of the convection section to the inlet of the convection section to return heat transfer gas to the electric heater, and Optionally, one or more supplemental heaters and/or heat exchangers are coupled between the convection section and the radiant section to provide the function of those heat exchangers removed from the convection section.

Description

Furnace having an electrically heated convection section and steam cracking process using such an electric furnace Technical Field The present disclosure relates generally to methods for producing chemicals, and more particularly, but not by way of limitation, to convection banks for use with radiant electric furnaces for steam cracking and steam cracking methods using such convection banks. Background Chemical synthesis devices are used to provide a variety of chemicals. Typically, a specialty fuel is burned or incinerated to provide heat of reaction for chemical synthesis, energy for heating one or more process streams, energy for evaporating liquids (e.g., boiling water to be used as a diluent), energy for doing work (e.g., driving a compressor or pump), or energy for other process operations in the overall chemical synthesis plant. Such combustion or incineration of fuel results in the production of flue gas containing CO 2, which may be harmful to the environment and also results in a loss of energy efficiency of the process. Likewise, steam is typically used as a device-wide heat and/or energy transfer fluid within chemical synthesis devices. Steam for heat and/or energy transfer is typically generated via combustion of a fuel, resulting in additional flue gas and additional energy efficiency losses during chemical synthesis. Efforts have been made to convert certain aspects of chemical synthesis apparatus into electricity rather than convection. However, electrification of certain components in chemical synthesis plants presents additional problems and challenges that are different from and/or not necessarily present in combustion driven furnace cracking reactors. Disclosure of Invention As described above, electrification of process components in a chemical synthesis apparatus is not necessarily simple. For example, in steam cracking processes, an electric furnace relies on having sufficient power input while maintaining energy balance between the various interrelated elements. The electrification of all elements in such a cracking process (e.g., heat exchangers in the convection section of a steam cracker) undesirably requires more energy than would otherwise be required to operate the process. The steam-cracked convection bundles, furnaces including such convection bundles, and related methods of the present invention utilize an electric heater to provide a heated gas (e.g., air) in place of flue gas, while maintaining the heating and vaporization functions of conventional convection bundles at operating temperatures less than or equal to a threshold temperature (e.g., 800 ℃). When the radiant section in the steam cracker is electrified (using an electrical heating element instead of combustion), the hot flue gas source normally used in the convection section is eliminated. As explained in more detail below, the present configuration removes from the convection section any heat exchanger that is typically operated at a temperature above a threshold temperature (e.g., 800 ℃) and instead of such a heat exchanger includes an indirect electric heater (e.g., in the form of one or more electric heater modules or air heaters) to provide heat transfer gas that is heated to or near the threshold temperature in place of heated flue gas, thereby operating the remaining functions of the convection bank (e.g., preheating and evaporating) in an otherwise conventional manner using a validated heat exchanger design. This approach avoids the need for direct electrification (e.g., by significantly more expensive high pressure steam superheating equipment) of the remaining convection bank functions that are traditionally exchanged with flue gas at temperatures around or below the threshold temperature. The convection section in a conventional steam cracker contains a plurality of heat exchangers in which the flue gas provides the high temperatures required to preheat and superheat the various streams during which the flue gas is cooled from about 1200 ℃ to about 150 ℃. As mentioned above, when the radiant box is electrified, there is no longer flue gas available for the convection section. In principle, an electrical process heater can replace all heat exchangers in the convective bank. However, this approach results in the required electrical energy being far in excess of the necessary amount, and some of these process heaters are limited in available size and/or are too expensive. For steam cracking of liquid feeds, vaporization of the feedstock conventionally occurs in a heat exchanger within the convective bank. This is a fine balance combination of flow rate, boiling range, evaporation rate, flow regime, and other factors to avoid fouling due to premature evaporation (resulting in sediment) or too late evaporation (resulting in liquid exposure to excessive tube wall temperatures that may result in coking). Therefore, the preheating and direct electrification of the vaporizing tube bundles in conventional convec