Electric furnace for decomposing hydrocarbon feedstocks with heat recovery

Abstract

An electrocracker system for converting a hydrocarbon feedstock to cracked gas includes a mixing device for mixing the hydrocarbon feedstock with slightly superheated steam and / or saturated steam. The system includes a steam drum, an electric furnace, a primary transfer line exchanger (PTLE), a secondary transfer line exchanger (STLE), and a tertiary transfer line exchanger (TTLE). The electric furnace includes a feed inlet for the hydrocarbon feedstock-saturated steam mixture and an outlet for the cracked gas. The steam drum includes a saturated steam outlet connected to the mixing device, and a water outlet and a steam inlet both connected to the STLE. The PTLE is configured to preheat the hydrocarbon feedstock-saturated steam mixture before it enters the electric furnace and to cool the cracked gas provided by the electric furnace. The STLE is configured to generate steam and to cool the cracked gas provided by the PTLE.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority and benefits of U.S. Patent Application No. 17 / 727,700, filed on 22 April 2022, the contents of which said U.S. Patent Application are incorporated herein by reference in their entirety.

[0002] This disclosure relates to an electrolytic furnace system for converting hydrocarbon feedstock into decomposition gases, and to a process for decomposing hydrocarbon feedstock using this system. More specifically, this disclosure relates to a process for producing ethylene and propylene from hydrocarbon feedstock. [Background technology]

[0003] In conventional ethylene plants equipped with combustion cracking furnaces, sufficient high-pressure (HP) steam is generated to power the machinery, and further dilution steam is generated to suppress the hydrocarbon partial pressure, thereby improving product selectivity and suppressing coke formation in the cracking reactor.

[0004] In the high-temperature section of the plant, dilution steam is conventionally generated from medium-pressure (MP) steam produced from HP steam after power generation via one or more steam turbines. Furthermore, if a primary fractionator known for decomposing liquid feedstock is available, heat recovery of furnace effluent (decomposition products) in the primary fractionator quenching oil circuit, which is the pump-around circuit of the primary fractionator, helps in the generation of dilution steam, allowing more MP steam to be reduced to lower pressure levels for maximum power production. At the same time, excess heat from the effluent can be recovered in the quenching water tower and transferred to the low-temperature user via the pump-around loop. This low level of heat is used, for example, to preheat the furnace feedstock. Further evaporation of the feedstock is usually carried out by flue gas in the convection section of the conventional decomposition furnace.

[0005] More specifically, conventional gas cracking reactors include the following characteristics: - A radiating section in which a radiating coil is located inside the firebox (at least one radiating coil), and a chemical reaction takes place in the radiating coil. Combustion occurs inside the firebox by fuel into the burner, providing the heat necessary for the pyrolysis reaction. - The convection section is used to preheat the feed, dilution steam, and mixtures of feed and dilution steam, generate high-pressure steam, and preheat the boiler feedwater. In some cases, it can also be used to preheat the combustion air as an air preheater (also called "APH") for fossil fuel combustion in the burner. The purpose of the convection section is to recover the available high-temperature flue gas heat from the combustion of fuel and air in the firebox. Flue gas primarily contains N2, O2, H2O, CO2, argon, trace amounts of NOx / CO, and certain substances (PM2.5, PM5, and PM10). Several ethylene manufacturers have announced targets to reduce CO2 emissions by 25% by 2030 and achieve net-zero CO2 emissions by 2050. In some cases, to meet on-site emission requirements, DeNOx units (or called SCRs) are installed in the convection section to further reduce NOx generated from combustion. - To cool the decomposition gases from the outlet of the radiating coil to a desired temperature before they leave the decomposition furnace, a transfer line exchanger (TLE) is located at the outlet of the radiating coil via the transfer line. The transfer line exchanger may be one or more exchangers. -Saturated high-pressure steam is generated in the TLE by rapidly cooling the decomposition gas through the riser and faller pipes between the TLE and the steam drum. - The saturated high-pressure steam is further heated in the high-pressure steam superheater coils (HPSSH-1 and HPSSH-2) of the convection section to generate superheated high-pressure steam, which is then discharged from the decomposition furnace. -Dilution steam to the furnace is supplied from the rest of the plant by a dilution steam generating drum. Saturated dilution steam is generated by medium-pressure steam as a vaporizer, separated in the dilution steam generating drum, and then slightly superheated by MP steam before proceeding to the furnace, or by injecting hot steam before entering the furnace. In addition, quench water stripper condensate is preheated with MP steam before proceeding to the dilution steam generating drum. The dilution steam is mixed with preheated dry feed from the upper bank of the convection section. The mixed feed is further preheated in the lower bank of the convection section to the radiation coil inlet temperature required for decomposition in order to reduce the coking rate and increase olefin yields in the furnace emissions, such as ethylene and propylene yields.

[0006] Conventional technologies have been considered satisfactory for their intended purposes. However, there is always a need for improved electrolytic furnace systems and methods. This disclosure provides a solution to this need. [Overview of the project]

[0007] Embodiments of the present disclosure aim to improve heat recovery and simplify the decomposition of hydrocarbon feedstock. Embodiments of the present disclosure include an electrolytic furnace system for converting hydrocarbon feedstock into decomposition gases, comprising at least a mixer for mixing the hydrocarbon feedstock with slightly superheated or saturated steam, a steam drum, an electric furnace, a primary transfer line exchanger (PTLE), a secondary transfer line exchanger (STLE), and a tertiary transfer line exchanger (TTLE). The electric furnace includes a feed inlet for the hydrocarbon feedstock-slightly superheated steam mixture or saturated steam mixture and an outlet for the decomposition gases. The steam drum includes a saturated steam outlet connected to a mixer for mixing the hydrocarbon feedstock with saturated steam, and a water outlet and a steam inlet, both connected to a secondary transfer line exchanger STLE. The primary transfer line exchanger (PTLE) is configured to preheat the hydrocarbon feedstock-saturated steam mixture before it enters the electric furnace and to cool the decomposition gases provided by the electric furnace. A secondary transfer line exchanger (STLE) is configured to generate steam and to cool the decomposition gas supplied by the primary transfer line exchanger (PTLE). A tertiary transfer line exchanger (TTLE) is configured to preheat the hydrocarbon feedstock before mixing with saturated steam and to cool the decomposition gas supplied by the secondary transfer line exchanger (STLE). The electrolysis furnace system may include a decomposition gas compressor with an electric turbine. The secondary transfer line exchanger (STLE) has a flow rate of 4-15 kg / cm³. 2 The system is configured to generate steam at a pressure of g. The electrolytic furnace system may include a heat exchanger upstream of the mixer for preheating the saturated steam provided by the steam drum. The electrolytic furnace system may include a second mixer upstream of the mixer for mixing the saturated steam provided by the steam drum with the preheated steam. The electrolytic furnace system may comprise N electric furnaces, N to 10N primary transfer line exchangers PTLE, N to 2N secondary transfer line exchangers STLE, N to 2N tertiary transfer line exchangers TTLE where N≧2, and N or less than N steam drums where N≧2.

[0008] In another embodiment, a process for decomposing a hydrocarbon feedstock in an electrolytic furnace system may include preheating the hydrocarbon feedstock in a tertiary transfer line exchange (TTLE). The process includes mixing the preheated hydrocarbon feedstock with at least one of saturated steam or slightly superheated steam to produce at least one of a hydrocarbon feedstock-saturated steam mixture or a hydrocarbon feedstock-slightly superheated steam mixture. The process includes preheating at least one of the hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture in a primary transfer line exchange (PTLE). The process includes decomposing the preheated hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture in an electric furnace to produce decomposition gases. The process includes providing a first cooling of the decomposition gases in the primary transfer line exchange (PTLE). The process includes providing a second cooling of the decomposition gases that have left the primary transfer line exchange (PTLE) in a secondary transfer line exchange (STLE). The process includes generating steam in the secondary transfer line exchange (STLE). The process includes providing a third cooling of the decomposition gas that has exited the secondary transfer line exchange (STLE) in a tertiary transfer line exchange (TTLE).

[0009] The hydrocarbon feedstock may be a dry gas. The process may include generating saturated steam or slightly superheated steam in a steam drum. The steam generated in the secondary transfer line exchanger (STLE) may be generated from water coming from the steam drum. The steam generated in the secondary transfer line exchanger (STLE) may be sent to the steam drum. Preheating at least one of the hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture may include preheating at a temperature of 180°C to 300°C. Preheating at least one of the hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture may include preheating at a temperature of 200°C to 260°C. The steam generated in the secondary transfer line exchanger (STLE) may have a viscosity of 4 kg / cm³. 2 ~15kg / cm 2 pressure in grams, or 6 kg / cm². 2 g~8kg / cm 2 This is a pressure of g.

[0010] Cooling the decomposition gas in the primary transfer line exchange (PTLE) may include cooling the decomposition gas to a temperature of 750°C to 900°C, or 820°C to 875°C. Cooling the decomposition gas in the secondary transfer line exchange (STLE) may include cooling the decomposition gas to a temperature of 375°C to 600°C, or 420°C to 520°C. These and other features of the systems and methods of this disclosure will become more readily apparent to those skilled in the art from the detailed description of preferred embodiments, which will be read in conjunction with the following drawings. [Brief explanation of the drawing]

[0011] Preferred embodiments of the Disclosure are described in detail below, with reference to specific figures, so that those skilled in the art to which this Disclosure perceives readily how to fabricate and use the devices and methods of this Disclosure without having to perform any unnecessary experiments. [Figure 1]This is a schematic diagram of an embodiment of an electric furnace system constructed in accordance with the present disclosure, showing one primary transfer line exchanger, one secondary transfer line exchanger, and one tertiary transfer line exchanger. [Modes for carrying out the invention]

[0012] Drawings are referenced here, where similar reference numerals identify similar structural features or embodiments of the Disclosure. For illustrative and illustrative purposes, and not limiting, schematic diagrams of exemplary embodiments of the electrolytic furnace system according to the Disclosure are shown in Figure 1, generally designated by reference numeral 100. Other embodiments or aspects of the electrolytic furnace system according to the Disclosure are described below. The systems and methods described herein can be used to improve heat recovery and to simplify the decomposition of hydrocarbon feedstock. Embodiments of the Disclosure aim to improve heat recovery and to simplify the decomposition of hydrocarbon feedstock.

[0013] Embodiments of the present disclosure are electrolytic furnace systems for converting hydrocarbon feedstock 1 into decomposition gas 4, wherein at least, - A mixing device 9 for mixing hydrocarbon feedstock 1 with slightly superheated or saturated steam 2, - Steam drum 5 and, - Electric furnace 3, - Primary Transfer Line Switch (PTLE), - Secondary transfer line exchange (STLE), -Third-tier transfer switch (TTLE), Equipped with, in this case, ● The electric furnace 3 is equipped with a feed inlet for hydrocarbon feed material - a slightly superheated or saturated vapor mixture 10, and an outlet for decomposition gas 4. ● The steam drum 5 is equipped with a saturated steam outlet connected to a mixing device 9 for mixing hydrocarbon feedstock with saturated steam, and a water outlet 6 and a steam inlet 7, both connected to the secondary transfer line exchange STLE. ● The primary transfer line exchanger (PTLE) is configured to preheat the hydrocarbon feedstock-saturated vapor mixture before entering the electric furnace 3 and to cool the cracked gas 4 provided by the electric furnace 3. ● The secondary transfer line exchanger (STLE) is configured to generate steam 7 and to cool the cracked gas 4 provided by the primary transfer line exchanger (PTLE). ● The tertiary transfer line exchanger (TTLE) is configured to preheat the hydrocarbon feedstock 1 before mixing with the saturated steam 2 and to cool the cracked gas 4 provided by the secondary transfer line exchanger (STLE).

[0014] Figure 1 shows an electric furnace system 100 according to an embodiment of the present disclosure. The electric furnace system 100 includes one primary transfer line exchanger, one secondary transfer line exchanger, and one tertiary transfer line exchanger.

[0015] The steam drum 5 includes a blowdown outlet 11.

[0016] According to an embodiment of the present disclosure, superheated steam is steam having a temperature higher than the temperature of saturated steam, and preferably, the difference between the temperature of saturated steam and the temperature of superheated steam is less than 10°C.

[0017] According to an embodiment of the present disclosure, an "electric furnace" is an electric pyrolysis reactor.

[0018] Various suitable devices can be used as the mixing device 9. According to an embodiment of the present disclosure, the mixing device 9 can be a gas mixer having a mechanical mixing valve, a gas mixer having an electric mixing valve, a gas mixer having an air flow controller, a gas mixer having a flow controller (e.g., a mass flow controller), etc.

[0019] A transfer line exchanger (TLE) is a heat exchanger positioned to cool or quench the decomposition gas. Embodiments of the present disclosure can significantly improve furnace efficiency by using the waste heat of the decomposition gas in the transfer line exchanger to heat the feed material in the transfer line exchanger, instead of heating the feed material in the convection section as is done in prior art systems. Furnace efficiency is the ratio between the heat absorbed by at least one radiating coil to convert the hydrocarbon feed material into decomposition gas by pyrolysis, which is an endothermic reaction, based on a lower calorific value of 25°C or 15.6°C, and the heat released by the combustion process in the combustion zone.

[0020] The optimal inlet temperature for the feed material into the radiating section is determined by the thermal stability of the feed material, as is known to those skilled in the art. Ideally, the feed material enters the radiating section at a temperature slightly below the temperature at which the pyrolysis reaction begins. If the feed material inlet temperature is too low, additional heat will be required to heat the feed material in the radiating section, increasing the heat that needs to be supplied to the radiating section and the corresponding power consumption. If the feed material inlet temperature is too high, pyrolysis may have already begun in the transfer line exchanger or pipe, which is undesirable because the reaction will result in the formation of coke that cannot be easily removed.

[0021] A secondary heat exchanger (STLE) is positioned in series after a primary heat exchanger (PTLE) to further cool the decomposition gases from the electric furnace. The primary heat exchanger (PTLE) is configured to heat the feed material before it enters the electric furnace, while the secondary heat exchanger is configured to partially evaporate the boiler water by rapidly cooling the decomposition gases. The system may include one or more secondary heat exchangers. The system comprises a steam drum connected to the secondary heat exchanger (STLE). Boiler water flows from the steam drum of the decomposition furnace system to the secondary heat exchanger. The mixture of steam and water can be partially vaporized inside one of the secondary heat exchangers (STLE) and then sent back to the steam drum, where the steam can be separated from the remaining liquid water.

[0022] The electrolysis furnace system can, advantageously, be equipped with several primary transfer line exchangers (PTLEs).

[0023] Depending on the embodiment, an electrolytic furnace system according to an embodiment of the present invention may include one or more of the following features: - The electrolysis furnace system comprises at least a compressor 17 for the decomposition gas 4, accompanied by an electric turbine. Preferably, the compressor includes multiple stages, advantageously 1 to 5 stages. - The secondary transfer line exchanger (STLE) has a transfer rate of 4-15 kg / cm². 2 It is configured to generate steam 7 at a pressure of g. - The electrolysis furnace system comprises, upstream of a mixer 9 for mixing hydrocarbon feedstock with saturated steam or slightly superheated steam, a heat exchanger 12 for preheating saturated steam supplied by a steam drum, or a second mixer for mixing saturated steam supplied by a steam drum with preheated steam 8.

[0024] The electrolysis furnace system comprises N electric furnaces 3, N to 10N primary transfer line exchangers PTLE, N to 2N secondary transfer line exchangers STLE, N to 2N tertiary transfer line exchangers TTLE where N≧2, and N or less than N steam drums 5 where N≧2. In other words, the electrolysis furnace system also comprises one steam drum having multiple risers (at least one) and a descender (at least one) for one or more electric furnaces. Another object of embodiments of the present disclosure is a process for decomposing a hydrocarbon feedstock in an electrolysis furnace system as defined in the present disclosure, wherein the process comprises a) A step of preheating the hydrocarbon supply material 1 in the tertiary transfer line exchanger (TTLE), b) Step 9 of mixing preheated hydrocarbon feedstock 1 with saturated or slightly superheated steam 2, c) Preheating the hydrocarbon feedstock-saturated steam mixture 10 provided in step a) in a primary transfer line exchange (PTLE), d) A step of decomposing the mixture preheated in step b) in an electric furnace 3 to generate decomposition gas 4, e) A first cooling step in which the decomposition gas 4 is cooled in a primary transfer line exchange (PTLE), f) A second cooling step in which the decomposition gas 4 that has exited the primary transfer line exchange (PTLE) is cooled in the secondary transfer line exchange (STLE), g) The steam generation step in the secondary transfer line exchange (STLE), h) A third cooling step in which the decomposition gas 4 that has exited the secondary transfer line exchange (STLE) is cooled in the tertiary transfer line exchange (TTLE), This is a process that includes [something].

[0025] Depending on the embodiment, the process for decomposing hydrocarbon feedstock according to this disclosure may include one or more of the following features: - The hydrocarbon feedstock 1 is a dry gas. Preferably, the hydrocarbon feedstock 1 contains 50% to 100% by volume of ethane and 50% to 0% by volume of propane, more preferably 80% to 100% by volume of ethane and 20% to 0% by volume of propane. - The process for decomposing the hydrocarbon feedstock includes a step of generating saturated steam or slightly superheated steam 2 in the steam drum 5. - The steam 7 generated in step g) is generated from the water 6 coming from the steam drum 5. - The steam 7 generated in step g) is sent into the steam drum 5. - In step c), the hydrocarbon feedstock - saturated steam mixture or slightly superheated steam mixture 10 is preheated at a temperature of 180°C to 300°C, preferably 200°C to 260°C. - In step g), the generated steam 7 is at a pressure between 4 kg / cm 2 ~15 kg / cm 2 g, preferably at a pressure of 6 kg / cm 2 g to 8 kg / cm 2 g. - In step e), the cracked gas 4 is cooled to a temperature of 750°C to 900°C, preferably 820°C to 875°C. - In step f), the cracked gas (4) is cooled to a temperature of 375°C to 600°C, preferably 420°C to 520°C. - The steam 7 generated in step g) is generated from the water 6 coming from the steam drum 5. - The steam 7 generated in step g) is sent into the steam drum 5.

[0026] The electric furnace has no convection section and does not generate flue gas, and therefore has no emissions such as NOx / CO / PM and CO2 compared to conventional decomposition furnaces where fossil fuel / air is supplied for combustion by burners. Instead, the electric furnace supplies heat to the decomposition radiant section by electric resistance heating. The heat input can be controlled by power generation along the radiant coil. Unlike conventional furnace designs, a transfer line exchanger (TLE) is used to generate high-pressure steam (HP). In embodiments of this disclosure, none of the transfer line exchangers are used to generate high-pressure steam. Instead, one of the transfer line exchangers is used to generate dilution steam by quenching the decomposition gas effluent. This is the role of the second transfer line exchanger (STLE). The other two transfer line exchangers are used to: 1. Preheat the dry feed by quenching the decomposed gas effluent. This is the role of the tertiary line exchanger (TTLE). 2. Further preheat the mixed feed (a mixture of dilution steam and dry feed) by quenching the decomposition gas effluent before proceeding to the radiant coil inlet for decomposition. This is the role of the primary transfer line exchanger (PTLE). This process according to embodiments of the present disclosure is applicable to gas feed cracking furnaces, mainly ethane, ethane / propane mixtures, and propane gas cracking furnaces.

[0027] Since the primary reaction toward olefins is more favorable at lower hydrocarbon partial pressures, it is well known that mixing dilution steam with the feed in the convection section of the cracking furnace is necessary to reduce the coking rate in the radiating coil and increase the olefin yield. The total TLE load of the gas cracking furnace is higher than the load required to preheat the dry hydrocarbon (HC) feed and the mixed feed (HC+DS). To achieve efficient TLE heat recovery, it is important to recover excess heat from the TLE in the electric furnace design. Using the transfer line exchanger (TLE) as a boiler from the furnace to generate dilution steam in the dilution steam generation drum by quenching the cracked gas effluent is a novel idea.

[0028] Furthermore, if a dilution steam generating drum is connected to a TLE to generate dilution steam, such application can be done with one drum by connecting its TLE from each electric furnace via riser and faller pipes, or, to improve cost-effectiveness, it can be shared by multiple electric furnaces by connecting to various TLEs (dilution steam-flue exchangers) via multiple riser and faller pipes. The faller pipe is the connecting pipe from the steam drum to the TLE, and the fluid in the faller pipe is a saturated liquid phase (saturated water) to provide the head (driving force for natural circulation). The riser pipe is the connecting pipe from the TLE back to the steam drum to form a closed loop of the steam / TLE system, and the fluid in the riser pipe is a two-phase flow (water / steam) after heat exchange in the TLE, generating steam. In order to form natural circulation between the steam drum and the TLE, the head in the faller pipe must overcome the pressure drop of the entire system (TLE and piping pressure loss).

[0029] For example, in conventional ethane, ethane / propane mixture, and propane cracking furnaces, typically two types of TLEs are used. Primary and / or secondary TLEs are used to generate saturated high-pressure steam, and then to generate superheated steam in the convection section before being discharged from the furnace. The superheated steam can then proceed to the steam turbine of the cracking gas compressor to generate electricity for compression. Tertiary TLEs are used to preheat the boiler feedwater before it proceeds to the convection section, to further preheat it before it proceeds to the high-pressure steam drum to provide heat for steam generation. The conventional concept is to generate dilution steam by heat exchange with medium-pressure steam (MP) in multiple exchangers using a common dilution steam generation drum from the rest of the plant, and then slightly superheat the MP steam (e.g., 15°F (8°C)) before it proceeds to the furnace. In addition, MP steam is often used to preheat the quench water stripper condensate before it proceeds to the dilution steam generation drum to provide heat available to the dilution steam generation drum.

[0030] However, in the case of electric furnaces, there is no convection section, and saturated high-pressure steam cannot proceed to the convection section due to superheating. Saturated high-pressure steam has no use. If tertiary TLE is applied, preheated BFW (boiler feedwater) from the tertiary TLE also cannot proceed to the convection section. Therefore, since there is no place to contain HP steam, it is essential to minimize or eliminate HP steam generation from the cracking furnace. The three main cracking gas refrigerated compressors, ethylene refrigerated compressors, and propylene refrigerated compressors can all be manufactured with electric turbines instead of steam turbines. These are the three typical main compressors in an ethylene plant (i.e., cracking gas refrigerated compressors, ethylene refrigerated compressors, and propylene refrigerated compressors).

[0031] If heat to the radiant coils is supplied by electricity rather than fossil fuels, the amount of steam generated from the furnace should be small or nonexistent. Normally, in conventional furnaces, HP steam is generated from the cracking furnace, but if the cracking furnace is an electric furnace, HP steam is not generated from the TLE, and therefore the cracking gas compressor must typically be electrically driven rather than steam turbine driven (unless steam is available from other sources besides the ethylene cracking furnace). If there is no or insufficient available steam generated within the plant, the other two compressors (ethylene and / or propylene cooling compressors) may also be electrically driven. If HP or MP steam generation is used instead of DS steam generation in a secondary TLE (S-TLE) to achieve the required heat recovery, saturated steam must be superheated to be useful, and therefore an additional steam superheater is required. In addition, if HP steam is used to generate lower steam levels, a new steam turbine may be required. If zero emissions are required, the steam superheater must have an electric heater or burn 100% H2 to minimize CO2 emissions in the furnace stack. In addition, a dilution steam generation system from the rest of the plant is still required. This makes the electric furnace and its steam supply system costly. In any case, dilution steam is still always necessary for decomposition in order to reduce the coking rate and increase olefin yields such as ethylene and propylene yields.

[0032] Therefore, the solutions of the embodiments of this disclosure enable optimal heat recovery of the TLE in electric furnace applications while maintaining the same overall heat recovery at the TLE as in conventional cracking furnaces, so as not to overload the downstream quenching tower system.

[0033] By applying S-TLE to generate dilution vapor, the decomposition gas outlet temperature after tertiary TLE can be made the same as the tertiary TLE outlet temperature from conventional decomposition reactor designs (e.g., approximately 149-177°C in the case of ethane decomposition). Thus, the required overall heat recovery is achieved in TLE, thereby reducing the load on the downstream quenching tower, and therefore requiring less cooling quenching water circulation flow.

[0034] In the case of gas-decomposition electric furnaces (ethane, ethane / propane mixtures, propane), the dry feed can be heated in the tertiary TLE, the mixed feed can be further heated in the primary TLE by rapidly cooling the high-temperature decomposition gas, and dilution vapor can be generated by the secondary TLE together with the dilution vapor generation drum by rapidly cooling the high-temperature decomposition gas. The saturated dilution vapor from the dilution vapor generation drum can be slightly superheated (e.g., 15°F (8.3°C)) using a small MP vapor exchanger or a small electric heater, or by injecting some available steam for superheating before it enters the furnace.

[0035] The advantages of the present invention are summarized below. i. Fully utilize the entire available heat load from the Transfer Line Exchanger (TLE) to achieve optimal heat recovery for the electric furnace design, and generate dilution steam in one of the TLEs (usually a secondary TLE, which is called a “Dilution Steam-Effluent Exchanger”) together with a dilution steam generation drum, and feed it back directly to the furnace as an integrated closed-loop system for the electric furnace design. ii. This application can be extended to applications of multiple furnaces having one common dilution vapor generation drum. To further reduce the overall number of pieces of equipment as needed, multiple TLEs can be connected to this drum via multiple risers / fallers to generate dilution vapor for feedback to multiple furnaces. iii. Since high-pressure or medium-to-high-pressure steam is not useful for electric furnace applications, applying this innovation eliminates the need for high-pressure or medium-to-high-pressure steam generation. In electric furnace design, minimizing or eliminating HP steam generation from the furnace's TLE is essential. iv. Since the furnace can efficiently generate dilution steam on its own, a conventional dilution steam generation system from the rest of the plant (or what is called the recovery section of an ethylene plant) is not necessary. The inventors generate dilution steam using the available load from the dilution steam-flue exchanger, thus saving energy that would otherwise be used to generate dilution steam using MP steam in multiple dilution steam generators. Therefore, these multiple dilution steam generators are unnecessary. This also results in significant savings in MP steam consumption. v. The operating pressure of the diluted vapor is generally 85-115 psig (6-8 kg / cm²). 2 g) is only, and is much lower than HP steam pressure (e.g., a nominal 1500 psig system (where the steam pressure can range from 400 psig to 2000 psig)), which results in excellent heat transfer for cooling the decomposition gas for this TLE design. In addition, it has good cost benefits due to the much lower design pressure and smaller heat exchanger. Furthermore, the height of the dilution steam generation drum can be lower due to the lower operating pressure, which saves piping for the riser and faller tubes and also saves structural steel material compared to conventional high-pressure steam TLE systems.

Claims

1. An electrolysis furnace system for converting hydrocarbon feedstock into decomposition gas, wherein at least, A mixing apparatus for mixing hydrocarbon feedstock with slightly superheated steam or saturated steam, Steam drum and Electric furnace and, Primary Transfer Line Switch (PTLE), Secondary transfer line exchange (STLE), A tertiary transfer line exchange (TTLE) and Equipped with, The electric furnace includes a feed inlet for a hydrocarbon feed material-saturated vapor mixture and an outlet for decomposition gases, The steam drum includes a saturated steam outlet connected to the mixing device, and a water outlet and a steam inlet, both connected to the secondary transfer line exchange (STLE). The primary transfer line exchange (PTLE) is configured to preheat the hydrocarbon feed material-saturated vapor mixture before it enters the electric furnace and to cool the decomposition gas provided by the electric furnace. The secondary transfer line exchange (STLE) is configured to generate steam and to cool the decomposition gas provided by the primary transfer line exchange (PTLE), The tertiary transfer line exchanger (TTLE) is configured to preheat the hydrocarbon feedstock before mixing it with saturated vapor and to cool the decomposition gas provided by the secondary transfer line exchanger (STLE). Electrolysis furnace system.

2. The electrolysis furnace system according to claim 1, comprising at least a compressor for the decomposition gas, which includes an electric turbine.

3. The aforementioned secondary transfer line exchange (STLE) has a transfer rate of 4 to 15 kg / cm². ２ The electrolysis furnace system according to claim 1, configured to generate steam at a pressure of g.

4. The electrolysis furnace system according to claim 1, further comprising a heat exchanger upstream of the mixing device for preheating the saturated steam provided by the steam drum.

5. The electrolytic furnace system according to claim 1, further comprising a second mixing device upstream of the mixing device for mixing the saturated steam provided by the steam drum with preheated steam.

6. The electrolysis furnace system according to claim 1, comprising N electric furnaces, N to 10N primary transfer line exchangers PTLE, N to 2N secondary transfer line exchangers STLE, N to 2N tertiary transfer line exchangers TTLE with N≧2, and N or less than N steam drums with N≧2.

7. A method for decomposing a hydrocarbon feedstock using the electrolysis furnace system described in any one of claims 1 to 6, a) Preheating the hydrocarbon supply material in the tertiary transfer line exchanger (TTLE), b) Mixing the preheated hydrocarbon feedstock with at least one of saturated steam or slightly superheated steam provided by a steam drum to generate at least one of a hydrocarbon feedstock-saturated steam mixture or a hydrocarbon feedstock-slightly superheated steam mixture, c) Preheating at least one of the hydrocarbon feed material-saturated steam mixture or the hydrocarbon feed material-slightly superheated steam mixture in a primary transfer line exchange (PTLE), d) Decomposing the preheated hydrocarbon feed material-saturated steam mixture or the hydrocarbon feed material-slightly superheated steam mixture in the electric furnace to produce decomposition gas, e) In the primary transfer line exchange (PTLE), providing a first cooling of the decomposition gas, f) In the secondary transfer line exchange (STLE), a second cooling of the decomposition gas that has exited the primary transfer line exchange (PTLE) is provided. g) In the secondary transfer line exchange (STLE), steam is generated from water coming from the steam drum, and the steam is sent into the steam drum, h) In the tertiary transfer line exchanger (TTLE), a third cooling of the decomposition gas that has exited the secondary transfer line exchanger (STLE) is provided. A method that includes this.

8. The method for decomposing a hydrocarbon supply material according to claim 7, wherein the hydrocarbon supply material is a dry gas.

9. The method for decomposing a hydrocarbon feedstock according to claim 7, further comprising generating saturated steam or slightly superheated steam in the steam drum.

10. A method for decomposing a hydrocarbon feedstock according to claim 7, wherein preheating at least one of the hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture includes preheating at a temperature of 180°C to 300°C, and optionally includes preheating at least one of the hydrocarbon feedstock-saturated steam mixture or the hydrocarbon feedstock-slightly superheated steam mixture at a temperature of 200°C to 260°C.

11. The steam generated in the secondary transfer line exchange (STLE) is 4 kg / cm³. ２ ~15 kg / cm² ２ The pressure is g, and optionally, the steam generated in the secondary transfer line exchanger (STLE) is 6 kg / cm³. ２ g to 8 kg / cm ２ A method for decomposing a hydrocarbon supply material according to claim 7, wherein the pressure is g.

12. A method for decomposing a hydrocarbon supply material according to claim 7, wherein cooling the decomposition gas in the primary transfer line exchange (PTLE) includes cooling the decomposition gas to a temperature of 750°C to 900°C, and optionally includes cooling the decomposition gas in the primary transfer line exchange (PTLE) to a temperature of 820°C to 875°C.

13. A method for decomposing a hydrocarbon supply material according to claim 7, wherein cooling the decomposition gas in the secondary transfer line exchanger (STLE) includes cooling the decomposition gas to a temperature of 375°C to 600°C, and optionally includes cooling the decomposition gas in the secondary transfer line exchanger (STLE) to a temperature of 420°C to 520°C.

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