Ethylene plant including an electric pyrolysis reactor and a feed-effluent heat exchanger

Abstract

The present invention relates to an ethylene plant comprising an electric pyrolysis reactor and a method for producing pyrolysis reactor effluent using the ethylene plant. The pyrolysis reactor comprises a feed inlet for a hydrocarbon feedstock-diluent mixture and an outlet for a pyrolysis reactor effluent comprising ethylene. The plant further comprises a heat exchanger (90) configured to transfer heat from the pyrolysis reactor effluent to the feed for the pyrolysis reactor. The heat exchanger (90) comprises a feed inlet and a feed outlet upstream of the pyrolysis reactor, and further comprises a pyrolysis reactor effluent inlet and a pyrolysis reactor effluent outlet. A feed passage exists between the feed outlet of the heat exchanger and the feed inlet of the pyrolysis reactor, and further comprises a feed passage between the reactor effluent outlet of the pyrolysis reactor and the decomposition gas inlet of the heat exchanger.

Description

Technology Field

[0001] The present invention relates to an ethylene plant comprising an electric pyrolysis reactor. The present invention further relates to a method for producing ethylene from a hydrocarbon feed using an ethylene plant according to the present invention.

[0002] In a conventional ethylene plant including a combustion cracking furnace, high-pressure (HP) steam sufficient to generate power to drive the machine is produced, and additionally, dilution steam is produced to suppress hydrocarbon partial pressure, thereby improving product selectivity and preventing coke formation in the cracking reactor.

[0003] In the high-temperature zone of the plant, dilution steam is generated from medium-pressure (MP) steam produced from HP steam after power has traditionally been produced through one or more steam turbines. Additionally, if a primary separator known for cracking liquid feedstock is available, heat recovery of the furnace effluent (cracking product) in the primary separator's quenching oil circuit—which is the pump circulation circuit of the primary separator—helps generate dilution steam and lowers more MP steam to a lower pressure level for maximum power production. At the same time, excess heat from the effluent can be recovered in a quenching water tower and transferred to a low-temperature user through a pump circulation loop. This low-temperature heat is used, for example, to preheat the furnace feedstock. Further feedstock evaporation is typically performed by flue gas in the convection zone of the conventional cracking furnace.

[0004] FIG. 1 illustrates an example of the method (high-temperature section) of a conventional combustion ethylene plant for a gaseous hydrocarbon feedstock. A new gaseous feedstock (1), such as ethane, propane, or a mixture thereof, is first preheated in a preheater (30) using a low-temperature heat source, such as quenched water outside the cracking furnace (1000), to a temperature of approximately 50°C suitable for entering the cracking furnace (1000) from ambient conditions. Further preheating of the feedstock is achieved by flue gas in the convection zone of the furnace by a hydrocarbon feedstock preheater (31). Slightly superheated diluted steam (24) is added to suppress the hydrocarbon partial pressure in the pyrolysis reactor, which is beneficial for product yield and suppression of coke formation. Once mixed, the feedstock and diluted steam are preheated to a temperature higher than the water dew point, which is approximately 120 to 130°C. Further superheating of the steam-diluted hydrocarbon feedstock (3) is achieved using flue gas in a feedstock superheater located in the convection zone of the furnace (33). Once properly superheated, the steam-diluted feedstock enters a pyrolysis reactor (34) at approximately 650°C to 730°C. This reactor is traditionally heated by burning fuel gas in a combustion chamber. The reactor operates at relatively low pressure and high temperature, as this is advantageous for olefin yield. Typical operating conditions at the reactor outlet are 800°C to 870°C and a pressure of 1.6 to 2.2 bara, producing products such as ethylene, propylene, butadiene, benzene, toluene, and xylene. Typical byproducts are hydrogen, methane, gasoline, and fuel oil. Some of the products, such as ethane and propane, are recirculated to the reactor. The reactor effluent (4) contains all of these products and byproducts. The reactor effluent (4) is cooled to approximately 160°C to 220°C within the decomposition furnace zone (1000). The heat generated from the effluent above 350°C is recovered using the first transfer line switch (35) by generating saturated high-pressure steam of approximately 100 to 125 bara.Low levels of heat can be recovered in the second transfer line exchanger (36) to preheat the boiler feedwater or superheat the steam diluted feedstock.

[0005] The effluent (4) from the furnace zone is sent to the high-temperature separation zone of the plant, which mainly consists of a quenching water tower (60), an acid water stripper (70), and a diluted steam drum (80). In the quenching water tower (60), the effluent (4) is further cooled to approximately ambient conditions. Cooling is performed using a pump circulation circuit that collects the accumulated water bottom product, called the so-called quenching water (14), and injects it at various levels of the quenching tower (60). The quenching water circuit generally has two stages: a quenching water bottom cooling circuit (64) that provides the quenching water tower bottom zone (61), and a quenching water tower top cooling circuit (66) that provides the quenching water tower top zone (62). The top product, which is the cooled gaseous phase of the reactor effluent called the decomposition gas (9), is sent to the downstream decomposition gas compression zone and further separated in the low-temperature separation unit. The quenching water bottom circuit cooler (65) is typically configured to allow the user to recover as much quenching water duty as possible. Such a user is, for example, a feedstock preheater (30). Any excess heat must be removed through air cooling or cooling water cooling. The quenching water top circuit cooler (67) typically uses cooling water to remove excess heat. Cooled injection water from the pump circulation circuit is used to remove heat from the decomposition gas through direct heat exchange via appropriate internal tower devices within the quenching water tower. The primary duty of this tower, in addition to cooling the decomposition gas, is to condense and recover the dilution vapor. The condensed dilution vapor is the net product coming out of the bottom of the tower in addition to a small stream of heavy pyrolysis gasoline product (8). These are generally separated from each other using a gasoline / water separator (63). Sometimes, this separator also collects the quenching water (14) for the quenching water circuit. This condensed diluted steam, called acidic water (20), contains acidic gas, which is stripped by strip steam (21) in the acidic water stripper (70). These acidic gases (22) are returned to the quenching water tower (60).Stripped water, called process water (23), is suitable for generating diluted steam. This is generated at a higher pressure of approximately 6 to 7 bar so that it can be sent back to the decomposition furnace. Diluted steam generation is achieved using medium-pressure steam as a heat source. The process water is collected in a diluted steam drum (80), and through a thermosiphon circuit, diluted steam (24) is generated from the condensing medium pressure steam of the diluted steam generator (81). Any superheating of the medium-pressure steam is used to slightly superheat the diluted steam in the diluted steam superheater (83) to a temperature of 180°C to 210°C before returning it to the decomposition furnace (1000) to dilute the hydrocarbon feedstock (1). Blow-down (26) from the diluted steam drum (80) and diluted steam system makeup (25) to the drum prevent the accumulation of contaminants in the diluted steam generation circuit.

[0006] The integrated power generation method of a conventional ethylene plant is shown in FIG. 2. The MP steam required for dilution steam generation is generated from the boiler feedwater in a high-pressure steam system. The boiler feedwater is made from demineralized water (101) in a deaerator (120), where the steam is stripped by stripping steam (102) by removing CO2 and oxygen through the deaerator vent (103). The generated boiler feedwater (104) is preheated by decomposition gas or flue gas or both by a boiler feedwater preheater (121) in a decomposition furnace (1000) and collected in a high-pressure steam drum (122). The steam drum, connected by natural circulation to a thermosiphon-type heat exchanger called a transfer line exchanger (35), recovers heat from the reactor effluent (4) and generates saturated high-pressure steam (105), which is superheated by flue gas in the convection zone of the furnace (1000) using a high-pressure steam superheater (123). Superheated high-pressure steam is used to generate power to drive the main machinery in the separation zones of the ethylene plant, such as cracking gas compressors and cooling compressors, which are located in the low-temperature separation zones of the plant (not shown for the sake of clarity). To this end, the superheated high-pressure steam (107) is used to generate power (124) by lowering the pressure using a back-pressure steam turbine from high pressure to medium pressure, and also to generate power by lowering the pressure using a condensation turbine from medium pressure to vacuum (125). Most of the steam (110) is condensed in the surface condenser (126) of the condensation turbine (125) to maximize power output, but some of the steam (108) is reduced only to a medium pressure level. This medium pressure steam (108) is used to generate diluted steam and accounts for a significant portion of the total available high-pressure steam flow (107). Medium pressure steam (108) is desuperheated in a diluted steam superheater (83) to superheat the diluted steam, and is condensed in a diluted steam generator (81) to produce diluted steam (24).The generated medium-pressure condensate (109) and vacuum condensate (111) are combined, and the combined condensate (112) is returned to the deaerator and recirculated as boiler feedwater. A small blow-down (106) of the high-pressure steam drum prevents the accumulation of contaminants in the high-pressure steam circuit.

[0007] The high-temperature zone of the plant flow diagram for a process using a liquid hydrocarbon feedstock is shown in FIG. 3. In a typical liquid feedstock ethylene plant, a new liquid feedstock (2), such as butane, pentane, naphtha, or a mixture thereof, is first preheated in a preheater (30) using a low-temperature heat source, such as quenched water outside the furnace (1000), and heated to a temperature of approximately 50°C suitable for entering the cracking furnace (1000) from ambient conditions. Further preheating and partial evaporation of the feedstock are achieved by flue gas in the convection zone of the furnace, by the hydrocarbon feedstock preheater (31), and by the hydrocarbon feedstock evaporator (32), respectively. To suppress the hydrocarbon partial pressure in the pyrolysis reactor, which is beneficial for product yield and suppression of coke formation, the diluted steam (24) coming from the high-temperature separation zone is further superheated in the convection zone using flue gas. This is performed in a diluted steam superheater (84) to ensure complete vaporization of the partially evaporated feedstock once mixed. The feedstock is evaporated and the diluted steam is

[0008] The mixture is heated to a temperature much higher than the water dew point, which is approximately 130 to 140°C. Further superheating of the steam-diluted hydrocarbon feedstock (3) is achieved using flue gas in a feedstock superheater located in the convection zone (33) of the furnace. Once properly superheated, the steam-diluted feedstock enters a pyrolysis reactor at approximately 600 to 640°C. This reactor is traditionally heated by burning fuel gas in a combustion chamber. The reactor operates at relatively low pressure and high temperature, as this is advantageous for olefin yields. Typical operating conditions at the reactor outlet are 800 to 870°C and a pressure of 1.6 to 2.2 bara, producing products such as ethylene, propylene, butadiene, benzene, toluene, and xylene. Typical byproducts are hydrogen, methane, gasoline, and fuel oil. Some of the products, such as ethane and propane, are recirculated to the reactor. The reactor effluent contains all of these products and by-products.

[0009] The reactor effluent (4) is cooled to approximately 350°C within the decomposition furnace zone (1000). Heat generated from the effluent above 350°C is recovered using the first transfer line exchanger (35) by generating saturated high-pressure steam of approximately 100 to 125 bara. Lower levels of heat between 350°C and 160°C cannot be recovered using indirect heat exchange due to the contamination characteristics of the effluent, but if a heavy oil loop is available, it is recovered in the so-called quenching oil pit (37) using quenching oil injection (27) and heavy oil injection (28). The effluent (4) from the furnace zone is sent to the high-temperature separation zone of the plant, which mainly consists of a primary classifier (50), a quenching water tower (60), an acid water stripper (70), and a dilution steam drum (80).

[0010] In the primary classifier (50), the effluent is further cooled to approximately 100°C to maintain a temperature above the dew point so that water does not condense in this tower. The effluent is then cooled using quenching oil and heavy oil pump circulation and gasoline reflux, respectively. The quenching oil cooling circuit (54) originates from the heavy fuel oil product (6) collected at the bottom of the tower. This quenching oil (10) is cooled by the quenching oil circuit cooler (55). Some of it is sent to the quenching oil fitting (27), and the remainder is injected back into the tower below the heavy oil total discharge tray. The quenching oil circuit cooler (55) is generally used to generate dilution steam in the dilution steam generator (82). If the temperature at the bottom of the primary classifier is not sufficient to generate dilution steam, it can instead generate low-pressure steam. The quenching oil cooling circuit (54) generally recovers all heat from the effluent at 170°C to 180°C or higher when the heavy oil cooling circuit (56) is present, and otherwise recovers heat from the effluent at 125°C to 130°C. The quenching oil cooling circuit is used in the primary classifier washing zone (51), which is the bottom zone of the column.

[0011] The heavy oil cooling circuit (56) is optional and is intended to provide a relatively clean and uncontaminated intermediate cooling circuit that recovers a lower level of heat from the effluent than the quenching oil circuit (54), typically up to 125°C to 130°C. The heavy oil (11) is collected in a discharge tray at the bottom of the primary separator heavy oil zone (52), which is located above the tower wash zone (51). The heavy oil reflux (12) is sent to the quenching oil wash zone (51) at the bottom of the tower so that the quenching oil duty can be moved to the heavy oil loop. Additionally, the heavy oil stream (28) is sent to the quenching oil fitting (37). The remainder is cooled by the heavy oil circuit cooler (57) and returned to the tower below the light fuel oil discharge point. The heavy oil cooling circuit (56) serves as the primary separator heavy oil zone (52).

[0012] The gasoline reflux (13) from the gasoline / water separator (63) processes heat recovery at the top of the tower, which is the primary separator gasoline reflux zone (53), and transfers the recovered duty to the rapid cooling water circuit.

[0013] Suitable internal devices are installed in the tower to efficiently transfer heat from the effluent to the injection quenching oil, heavy oil, and gasoline reflux. In addition to cooling the effluent, the light oil and heavy oil fractions are condensed in the primary separator. The heavy fuel oil (6) is collected in the bottom section (51), while the light fuel oil (7) is collected in the bottom of the reflux section (53) of the light oil discharge tray. These can be removed to control the flash point of the total fuel oil product (5) and / or to recover the lighter quenching oil fractions to control the viscosity of the quenching oil circuit.

[0014] In the quenching water tower (60), the effluent (4) is further cooled to approximately ambient conditions. The top product, which is the cooled gaseous phase of the reactor effluent called decomposition gas (9), is sent to a downstream unit for further separation. Cooling is performed using a pump circulation circuit that collects the accumulated bottom water product, called the so-called quenching water (14), and injects it at various levels of the quenching tower (60). The quenching water circuit generally has two stages: a quenching water bottom cooling circuit (64) providing the quenching water tower bottom zone (61), and a quenching water tower top cooling circuit (66) providing the quenching water tower top zone (62). The quenching water bottom circuit cooler (65) typically processes to recover as much quenching water duty as possible for a user. Such a user is, for example, a feedstock preheater (30) and / or a propylene splitter reboiler (not shown). Any excess heat must be removed through air cooling or cooling water cooling. The quenching water tower circuit cooler (67) typically uses cooling water to remove excess heat. Cooled injection water from the pump circulation circuit is used to remove heat from the decomposition gas through direct heat exchange via appropriate internal tower devices within the quenching water tower. The primary duty of this tower, in addition to cooling the decomposition gas, is to condense and recover the dilution vapor. The condensed dilution vapor is the net product coming out of the bottom of the tower in addition to a small stream of heavy pyrolysis gasoline product (8). These are generally separated from each other using a gasoline / water separator (63). Sometimes, this separator also collects the quenching water for the quenching water circuit. This condensed dilution vapor, called acidic water (20), contains acidic gases, which are stripped by stripping vapor (21) in an acidic water stripper (70). These acidic gases (22) are returned to the quenching water tower (60). The stripped water, called process water (23), is suitable for generating dilution vapor. This occurs at a higher pressure of approximately 6 to 7 bara so that it can be sent back to the decomposition furnace.Dilution steam generation is achieved using medium-pressure steam. Process water is collected in a dilution steam drum (80), and through a thermosiphon circuit, dilution steam (24) is generated from the condensing medium pressure steam of a dilution steam generator (81) and from a quenching oil cooling circuit using an additional dilution steam generator (82). Any superheating of the medium-pressure steam is used to slightly superheat the dilution steam in a dilution steam superheater (83) to a temperature of 180°C to 210°C before returning it to the cracking furnace (1000) to dilute the hydrocarbon feedstock (2). Blow-down (26) from the dilution steam drum (80) and makeup (25) into the drum prevent the accumulation of contaminants in the dilution steam generation circuit. The MP steam required for dilution steam generation is generated from the boiler feedwater in a high-pressure steam system in the same manner as the conventional gaseous ethylene plant flow diagram presented in FIG. 2 and described above.

[0015] Given the need to reduce greenhouse gas emissions such as carbon dioxide and methane emissions, there is significant interest in improving ethylene plants and ethylene plant operation processes to reduce the energy requirements for generating heat needed to operate the plants, or at least reduce the fossil fuel requirements.

[0016] A possible approach is to replace fossil fuels with hydrogen that can be produced by electrolysis. The necessary electricity can be generated using renewable energy sources, or carbon dioxide can be effectively captured to prevent its release into the air.

[0017] The inventors also realized that it would be interesting to use electricity directly to provide sensible heat (heat that raises the temperature of the hydrocarbon-vapor mixture) and some of the reaction heat for the decomposition reaction. However, when applying an electropyrolysis reactor, feedstock preheating and the evaporation of the liquid feedstock cannot be performed in the traditional manner because there is no flue gas, which is a high-temperature utility. Without MP steam, dilution steam cannot be generated in the traditional manner either.

[0018] The idea of ​​using an electrically heated pyrolysis reactor to produce olefins from hydrocarbons is known in the art. EP 3 249 028 A1 relates to a method for producing olefins by steam cracking using multiple cracking tubes. At least one of the cracking tubes is heated by the combustion of fuel (i.e., the combusted cracking tube), and at least one other cracking tube is heated electrically. To avoid unwanted side reactions, the reactor effluent (cracking product) is rapidly cooled (quenched). Additional downstream processes, such as fractional distillation of the cracking product, are described. Little information is disclosed regarding the preheating of the feedstock and the generation of diluted steam. Since this process requires fuel combustion, high-temperature flue gas may be used for heating; it is mentioned that steam is supplied directly to the cracking tube and that steam is generated inside the cracking tube.

[0019] EP 3 730 592 A1 relates to an olefin synthesis plant comprising a pyrolysis zone comprising one or more of the following: a feed pretreatment zone, one or more pyrolysis reactors for cracking hydrocarbons in the presence of a diluent, a primary fractional distillation and compression zone and / or a product separation zone, wherein—compared to a conventional plant—more energy and / or the net energy required for the plant in such zones is provided by a non-carbon-based energy source. EP 3 730 592 A1 presents various options for the use of electricity, feed heating, and dilution vapor generation in general use. For example, the plant may be configured for a steam cracking process, wherein, for example, part or all of the cracking reactor is electrically heated, and heat for the vaporization of recirculated water to create dilution vapor is generated by electricity. Additionally, the feed to the cracking reactor may be electrically preheated; or heated using most of the heat recovered by cooling the high-temperature product gas; Alternatively, it may be heated indirectly using a heat transfer agent (e.g., Dowtherm or steam). While some documented examples of specific embodiments are provided, drawings showing the relative positions of streams between units are lacking to clarify, for example, how heat recovery of the process stream is performed. This example relies on generating diluted steam directly from the effluent. The design appears to be limited to the treatment of ethane feedstocks only, as the contamination characteristics of the effluent are lower compared to processes using heavier feedstocks.

[0020] The object of the present invention is to provide a new ethylene plant comprising an electric pyrolysis reactor, which is a new process for producing ethylene by steam cracking, which is effective in reducing carbon dioxide emissions without the need to use the combustion of fuel (e.g., methane or hydrogen) to provide part of the heating of the hydrocarbon feed to the electric pyrolysis reactor while having robust feed tolerances. In particular, the object is to integrate the electric pyrolysis reactor in the ethylene plant to achieve this without using high-pressure steam as a source of diluted steam and without using high-pressure steam as a heating medium for the hydrocarbon feed.

[0021] It has now been found that it is possible to efficiently integrate an electric pyrolysis unit and a feed-effluent heat exchanger to recover sufficient heat from the effluent (decomposition product) of the above pyrolysis reactor. In particular, this is achieved by superheating the feed (a diluted vapor mixture of hydrocarbon feedstock) for the pyrolysis reactor using a downstream high-temperature separation zone of the plant so as to minimize excess power. Excess power is understood as power added to the power requirements for the electric pyrolysis reactor, namely, the power required to preheat, evaporate, and optionally superheat the feedstock, and the power required to generate diluted vapor or humidify the feedstock. Additional power required to drive machinery downstream of the plant, such as decomposition gas compressors and cooling compressors, may be treated as taught in EP3748138A1.

[0022] Accordingly, the present invention relates to an ethylene plant comprising an electric pyrolysis reactor, wherein the electric pyrolysis reactor comprises a feed inlet for a hydrocarbon feedstock-diluent mixture and an outlet for a pyrolysis reactor effluent comprising ethylene, and the ethylene plant further comprises a heat exchanger configured to transfer heat from the pyrolysis reactor effluent to a feed for the pyrolysis reactor, wherein the heat exchanger comprises a feed inlet and a feed outlet upstream of the pyrolysis reactor, and further comprises a pyrolysis reactor effluent inlet and a pyrolysis reactor effluent outlet. In a preferred embodiment, a feed passage exists between the feed outlet of the heat exchanger and the feed inlet of the pyrolysis reactor, and further comprises a feed passage between the reactor effluent outlet of the pyrolysis reactor and the decomposition gas inlet of the heat exchanger. In this manner, the generation of high-pressure steam by heat transfer from the reactor effluent can be minimized or even eliminated, thereby enabling the plant to operate without generating high-pressure steam from the heat transferred from the reactor effluent.

[0023] Advantageously, the temperature of the pyrolysis reactor effluent coming from the heat exchanger can be much lower than the ultra-high pressure stream generation range, generally much lower than 500°C, and preferably lower than 450°C.

[0024] In other or additional preferred embodiments, as described in more detail below, heat may be used to preheat the feed before the heat exchanger using heat from a downstream treatment unit where the reactor effluent is further cooled.

[0025] In addition, the present invention relates to a method for producing a pyrolysis reactor effluent containing ethylene from a hydrocarbon feed using an ethylene plant according to the present invention. The above method comprises the steps of: supplying a hydrocarbon feedstock-steam mixture to an electric pyrolysis reactor; decomposing the hydrocarbon feedstock in the presence of steam in the electric pyrolysis reactor of the ethylene plant to produce a pyrolysis reactor effluent containing ethylene; supplying the pyrolysis reactor effluent to a heat exchanger configured to transfer heat from the pyrolysis reactor effluent to the hydrocarbon feedstock-steam mixture before the decomposition of the hydrocarbon feedstock; and cooling the pyrolysis reactor effluent to a temperature at the heat exchanger pyrolysis reactor effluent outlet, preferably below 500°C, more preferably below 450°C, for example, a temperature in the range of 300°C to 450°C, and more preferably a temperature in the range of 325°C to 425°C, by transferring heat from the pyrolysis reactor effluent to the hydrocarbon feedstock-steam mixture in the heat exchanger. Brief explanation of the drawing

[0026] These and other features, aspects, and advantages of the apparatus, system, and method of the present invention will be better understood from the following description, appended claims, and accompanying drawings: FIG. 1 shows an example of the (high-temperature portion) method of a conventional combustion ethylene plant for gaseous hydrocarbon feedstocks; FIG. 2 shows an integrated power generation method of an existing ethylene plant; FIG. 3 schematically illustrates a high-temperature zone of an ethylene plant according to the present invention; FIG. 4 schematically illustrates an embodiment of an electric pyrolysis reactor combined with a feed-effluent heat exchanger; FIG. 5 schematically illustrates an ethylene plant / process according to the present invention; FIG. 6 schematically illustrates an ethylene plant / process according to the present invention; FIG. 7 schematically illustrates an ethylene plant / process according to the present invention; FIG. 8 schematically illustrates an ethylene plant / process according to the present invention; FIG. 9 schematically illustrates an embodiment relating to a heat bump of an ethylene plant / process according to the present invention; FIG. 10 schematically illustrates an ethylene plant / process according to the present invention; FIG. 11 schematically illustrates an ethylene plant / process according to the present invention; FIG. 12 schematically illustrates an embodiment relating to cooling of an ethylene plant / process according to the present invention; FIG. 13 schematically illustrates an embodiment relating to cooling of an ethylene plant / process according to the present invention; FIG. 14 shows the dew point as a function of absolute operating pressure in an exemplary saturator of an ethylene plant / process according to the present invention. In particular, the present invention provides a number of alternative solutions for operating an ethylene plant that lacks a high-pressure steam generation system and a combustion furnace for forming flue gas. Accordingly, the plant or process according to the present invention is suitable for operation where evaporation by feedstock preheating and flue gas heating is not available, and where diluted steam superheating is not available. This is achieved particularly by utilizing other thermal integration measures within the ethylene plant. By doing so, the need for additional power beyond that used for the pyrolysis reaction can be limited. For example, in at least a number of embodiments, the plant can be operated during normal operation (steady state) without using power to generate diluted steam and without electric preheating of the feedstock. By doing so, power usage can be relatively limited without hindering greenhouse gas emissions. This is particularly advantageous when one wishes to rely on renewable electricity sources whose supply may be highly variable depending on weather conditions, etc. A person skilled in the art will be able to design and operate suitable operating units of an ethylene plant using the present disclosure in conjunction with general knowledge and optionally one or more references cited herein. In addition to the operating units, passages, etc. described herein, the plant according to the present invention may include one or more additional units. Such units may be based on units for purposes generally known in the art or described in the references cited herein. For brevity, such units that may be conventional are not discussed in detail. In particular, upstream of the feedstock supply (1, 2), one or more units may exist, for example, one or more units configured to pretreat the feedstock to remove impurities. In particular, downstream of the high-temperature zone (downstream of line 9 in the drawing), one or more units may exist to purify the decomposed product gas or to recover useful products therefrom, for example, to recover hydrogen or methane therefrom. According to the present invention, an electric pyrolysis reactor (91) is combined with a feed-effluent heat exchanger (90) configured to transfer heat from the pyrolysis reactor effluent (4) to the pyrolysis reactor feed (3), i.e., a mixture of hydrocarbon feedstock and diluent (typically diluted steam), before the feed enters the pyrolysis reactor. This is schematically illustrated in FIG. 4. Such heat exchangers are generally known in the art; for example, they may have shell and tube designs. Typically, feed-effluent heat exchangers operate in a counter-flow configuration. As such, a temperature crossover usually exists, namely that the cold outlet temperature exceeds the hot outlet temperature. In principle, cross-flow is also possible. Feed-effluent exchangers typically have a passage for reactor effluent (cracking products) and a separate passage for feed (hydrocarbon-vapor mixture). The two passages are separated by a thermally conductive partition arranged to transfer heat from one passage to the other. Thus, the waste heat from the reactor effluent is used directly to heat the feed, and thereby none of the reactor effluent duty is used for high-pressure steam generation. Accordingly, the ethylene plant of the present invention is typically configured to operate without a high-pressure steam generator. The feed-effluent heat exchanger (90) is also distinguished from a quenching device, such as a quenching water tower, in which the reactor effluent typically comes into direct contact with a quenching medium, such as quenching water. A quenching device configured for further cooling of the reactor effluent (decomposition product) is advantageously provided downstream of the feed-effluent exchanger (90), which will be discussed in more detail below. The present invention enables the decomposition of gaseous feedstocks, liquid feedstocks, and mixtures thereof without the need to burn hydrocarbon fuels to generate sensible or reaction heat for pyrolysis reactions, thereby completely preventing direct CO2 emissions and preparing for the introduction of essentially renewable power sources (essentially no CO2 is generated at the plant). CO2 emissions can be kept to a minimum if the generation of dilution steam and the superheating of gaseous feedstocks and / or the preheating and evaporation of liquid feedstocks are performed with minimal additional power requirements. This is intended to promote the net zero emission goal of the ethylene industry in the most efficient way possible. An electropyrolysis apparatus for producing olefins in an ethylene plant may be based on a known electro-heated pyrolysis reactor. For example, the pyrolysis reactor may be a direct-heated reactor, where the reactor walls (e.g., walls of the cracking coils) are heated by resistance heating using electrically conductive walls. For example, WO2015 / 197181 A1 describes an apparatus and method for heating a fluid in a pipeline (cf. cracking reactor tube) in connection with steam reforming. This principle may be used in the pyrolysis reactor according to the present invention. It should be noted that in the case of decomposition according to the present invention, there is generally no catalytic material in the space where the pyrolysis takes place. In addition, the operating pressure at which the pyrolysis takes place is significantly lower than the 10 to 50 bar present in the reformer tube. Indirect resistance heating of the cracking coils is achieved by the electro-heating of the housing containing the cracking coils (typically multiple). In addition, rotary dynamic devices (RDRs) are highly suitable for delivering pyrolysis reactions by increasing kinetic energy, particularly through static and dynamic rotors, to supply sensible heat duty and reaction duty for the pyrolysis reaction, thereby transferring power to mechanical drivers and transferring the duty to the reaction mixture (see, for example, US2021 / 0171836A1). A known supplier of RDRs is Coolbrook (Helsinki, Finland; Geleen, the Netherlands). Another example of a suitable pyrolysis reactor is based on US 7,288,690B2 (see particularly claims 8 through 13). Instead of a feed-effluent exchanger, a waste heat boiler from a combined power generator is used to preheat the diluted feedstock, and power generated from an electric alternator is used to power the pyrolysis reactor. Suitable heating methods include direct resistance heating, induction heating, and ultrasound, also known as Joule heating. The electricity required for the ethylene plant according to the present invention may be recovered from a power system that is part of the plant, or the ethylene plant may have a power connection to a power system outside the plant. At least a substantial portion of the power, preferably essentially all of the power, is supplied from a renewable source; this is intended to minimize CO2 emissions. Accordingly, the power connection between the energy-consuming portion of the ethylene part, in particular the pyrolysis reactor (91), and the power system may be a connection to the internal power grid of the ethylene plant to supply at least a portion of the required power, or a connection to an external (remote) power plant connected to the same power grid as the ethylene plant according to the present invention. Power systems that supply electricity from renewable sources generally include one or more power systems selected from the group consisting of wind power systems, solar energy systems, hydroelectric power systems, geothermal energy systems, and osmotic power systems (also known as blue energy). Alternatively, or additionally, one or more systems configured to generate electricity from biomass and / or one or more systems configured to generate electricity from biorenewable fuels, such as bioethanol or biodiesel, may be used. While it is desirable to use renewable energy, in principle, electricity or part thereof can be recovered from other sources. Such plants still have the advantage of improved thermal integration. For example, the reactor effluent from a steam cracking reactor typically contains some methane and some hydrogen. These can be recovered from the reactor effluent into a methane-rich stream and a hydrogen-rich stream. Electricity can be generated using one or both of these in a manner known in itself. In the case of hydrogen, it does not increase CO2 emissions. If methane is combusted under CO2 formation, it can be captured to prevent release into the environment. However, in an advantageous embodiment, methane, hydrogen, or both can be used for higher-value purposes, for example, as feedstocks for other chemical processes. In the process according to the present invention, the weight-to-weight ratio of the diluted gas (steam) to the hydrocarbon feedstock, also called the diluted steam (weight) ratio, can be selected within a wide range. Typically, the ratio is selected within the range of about 0.25 to about 1.0, preferably within the range of about 0.35 to 0.9, and more preferably within the range of 0.4 to 0.8, depending on the feedstock. For example, in the case of gaseous feedstocks, the dilution steam ratio is typically relatively low, ranging from 0.3 to 0.4. For light liquid feedstocks such as naphtha, a higher ratio, typically in the range of 0.4 to 0.6, may be desirable. Heavyer feedstocks, such as gas oil, are typically operated at a higher dilution steam ratio of 0.6 to 1.0. Generally, higher dilution steam ratios are possible but are not economically attractive. Lower values ​​are less desirable as they can cause reduced yield and contamination. The mixture (3) of hydrocarbon feedstock and dilution steam is generally fed to a feed-exhaust heat exchanger (90) at a temperature higher than the water dew point. In quantitative terms, the temperature of the mixture of hydrocarbon feedstock and diluent at the inlet of the feed-exhaust heat exchanger (90) is generally in the range of 80°C to 230°C, preferably 120°C to 180°C, depending on the feedstock. For example, if the mixture is a vapor diluted gas feedstock from a humidifier, the temperature is preferably in the range of 80°C to 150°C, more preferably in the range of 90°C to 130°C. If a compressor is applied in addition to the humidifier to compress the vapor diluted gas feedstock to furnace inlet pressure, the operating temperature can generally be raised to 60 to 120°C depending on the polytropic efficiency and discharge pressure of the compressor. In the case of a vapor diluted liquid feedstock, the temperature is preferably in the range of 120°C to 200°C, more preferably in the range of 130°C to 180°C. Providing the diluted feedstock inlet at a temperature within a specific range, in contrast to superheating the feedstock to a higher temperature before entering the feedstock-effluent exchanger, advantageously reduces power requirements. In the heat exchanger above, the mixture of hydrocarbon feedstock and diluent is heated by heat from the pyrolysis reactor effluent, depending on the feedstock, to a pyrolysis reactor (91) inlet temperature generally in the range of 550°C to 750°C, preferably in the range of 570°C to 730°C. For example, if the mixture is a vapor diluent gas feedstock such as ethane or propane, the coil inlet temperature is preferably in the range of 630°C to 750°C, more preferably in the range of 650°C to 730°C. Liquid feedstocks preferably have a coil inlet temperature in the range of 550°C to 670°C, more preferably in the range of 570°C to 650°C. It has been found that in the case of ethane, it is possible to preheat to 730°C without contaminating the upstream convection compartment. It is not necessary to heat the hydrocarbon feedstock-steam mixture to the temperature at which pyrolysis is performed. Some of the sensible heat is supplied to the mixture using the power of the pyrolysis reactor, which also provides reaction heat. In the feedstock-effluent heat exchanger (90), the mixture is superheated; if the temperature of the feedstock mixture at the heat exchanger inlet is relatively low, a significant portion of the excess heat of the reactor effluent can be recovered, thereby reducing the power required to further heat the feedstock inside the pyrolysis reactor. The temperature of the reactor effluent (decomposition product) at the decomposition product inlet of the heat exchanger (90) depends on the residence time inside the reactor. In the case of the RDR, this is relatively low, so the coil outlet temperature is relatively high compared to the conventional radiant coil. In addition, the feedstock also plays an important role. Gaseous feedstocks have a lower conversion rate than liquid feedstocks such as naphtha and decompose at a relatively low coil outlet temperature. The temperature of the effluent at the inlet of the heat exchanger (90) may be in the range of 770°C to 900°C. The reactor effluent (decomposition product) at the decomposition product outlet of the heat exchanger (90) generally has a temperature that is at least 125°C higher, preferably 150°C to 250°C higher, than the feed-side outlet temperature of the feed-effluent exchanger. The reactor effluent (decomposition product) at the decomposition product outlet of the heat exchanger (90) generally has a temperature that is at least 150°C higher, preferably 175°C to 275°C higher, than the temperature of the diluted feed at the feed inlet of the feed-effluent exchanger. Generally, the temperature of the reactor effluent at the decomposition product outlet of the heat exchanger (90) is 500°C or lower, preferably in the range of 300°C to 450°C, more preferably in the range of 325°C to 425°C. When a compressor is applied in addition to a humidifier to compress the steam diluted gas feedstock to the furnace inlet pressure, this operating temperature can generally be raised to 40 to 100°C depending on the polytropic efficiency and discharge pressure of the compressor. The ethylene plant according to the present invention typically further comprises a cooling zone configured to further cool the cracking product after it leaves the feed-effluent heat exchanger (90). The cooling zone may also be referred to as the high-temperature zone of the plant. Generally, the ethylene plant of the present invention operates advantageously without a high-pressure steam generator. Thus, in the cooling zone, the pyrolysis reactor effluent is further cooled to approximately ambient conditions (outdoor temperature) without substantial high-pressure steam generation. Suitable devices for cooling the pyrolysis reactor effluent are thus known in the art and may be selected from water quenchers, oil quenchers, and air coolers. Preferably, the plant comprises at least one device selected from the group consisting of water quenchers and oil quenchers. As discussed below, such devices are not only effective for cooling but can also be used for purification or fractional distillation of the product, which may be based on principles known in the art. Furthermore, the inventors realized that streams used for water quenching, oil quenching, or both can be used to address the problem of lack of high-pressure steam generation, particularly to provide dilution steam. According to the present invention, instead of using dilution steam as a (high-temperature) stream mixed with a hydrocarbon feed—during normal operation—it is possible to humidify the feed with water (liquid) and, in particular, saturate it using a humidifier (this term is used interchangeably with the term saturator herein). Water generated from a water quenching unit can be used as a water source for humidifying the feed. This method is particularly advantageous for humidifying gaseous feeds, at least substantially. When using a humidifier, dilution steam is generally not required during normal operation, but it may be useful for startup, decocking, high-temperature atmospheres, and backup operations. Accordingly, in a plant / process that includes (uses) a humidifier for humidifying the feed, a dilution steam generator is typically provided.This may have a relatively small capacity compared to a plant that uses diluted steam during normal operation. In particular, a diluted steam drum (80) equipped with an electric boiler (85) may be provided to supply diluted steam (24) (see, for example, FIG. 6). This will be discussed in more detail below. FIG. 5 schematically illustrates a plant / process according to the present invention, illustrating how water quenching can be used to cool decomposition products to approximately ambient conditions. It also shows a method for providing a diluent by treating and using acidic water (condensed diluted steam containing acidic gas, recovered during cooling and washing of decomposition products in a water quenching device) without the need for high-pressure steam. From the furnace zone (1001), the pyrolysis reactor effluent (decomposition product) (4), cooled in the feed-effluent heat exchanger (90), is sent to the high-temperature separation zone of the plant, which includes a quenching water tower (60), an acidic water stripper (70), and a humidifier (saturator) (510). In the quenching water tower (60), the effluent (4) is further cooled to approximately ambient conditions. This is accomplished using a pump circulation circuit that collects the accumulated water bottom product, typically called quenching water (14), and injects it at various levels of the quenching tower (60). The quenching water circuit generally has two stages: a quenching water bottom cooling circuit (64) providing a quenching water tower bottom zone (61), and a quenching water tower top cooling circuit (66) providing a quenching water tower top zone (62). The quenching water bottom circuit cooler (65) typically processes to allow the user to recover as much quenching water duty as possible. The plant may operate without a feedstock preheater configured to preheat the hydrocarbon feedstock before combining it with the diluent (water / steam). The quenching water duty is used to heat the saturator water circuit (151), which in turn preheats and saturates the feedstock with water. Any excess heat in the cooling water circuit is typically removed through air cooling or cooling water cooling. The quenching water tower circuit cooler (67) typically uses cooling water to remove excess heat. Cooled feedwater from the pump circulation circuit is typically used within the quenching water tower to remove heat from the pyrolysis reactor effluent (cracking product) through direct heat exchange via a suitable internal tower device. The primary duty of this tower, in addition to cooling the cracking product, is to condense and recover the diluent steam. The condensed diluent steam is the net product coming out of the bottom of the tower, added to the stream of gasoline product (typically smaller than the stream of condensed diluent steam in the case of gaseous feedstock). These are typically separated from each other using a gasoline / water separator (63). This separator may also be used to collect quench water (14) for the quench water circuit. This condensed diluted steam, called acid water (20), contains dissolved acidic gases, which are typically stripped by strip steam (21) in the acid water stripper (70). These acidic gases (22) are returned to the quench water tower (60). The stripped water, called process water (23), is suitable for feedstock humidification (saturation). This occurs at a pressure higher than the pressure of the quench water tower and acid water stripper, generally about 2 to about 8 bar, particularly about 4 to about 6 bar, to supply to the furnace zone (1001) without the need for a compressor. Feedstock humidification (saturation) is achieved in the saturator water heating circuit (151) using the quench water as a heating medium. The process water is collected at the bottom of the saturator (150) and returned to the top of the saturator through the saturator water heating circuit (151). The water is heated using a saturated water circuit heater on the rapid cooling water (152).A new hydrocarbon feedstock (1) enters the bottom of the saturator and is saturated by high-temperature saturator water flowing down the column using a suitable internal device, typically using random packing. By controlling the saturator water inlet temperature, the humidification level can be controlled to reach the correct vapor dilution level of the pyrolysis reactor. The vapor diluted hydrocarbon feedstock is returned directly to the decomposition furnace (1001) and the feed-effluent exchanger (90). Blow-down (26) from the saturator (150) and makeup (25) to the saturator prevent the accumulation of contaminants in the saturator water heating circuit. Since the quenching water temperature level is limited to a maximum of about 80°C, the high-temperature saturator water inlet temperature is limited. The humidification level depends on the high-temperature saturator temperature and the partial pressure that the feedstock can generate in the column. The lower the boiling point of the feedstock, the easier it is to reach a high humidification level. Accordingly, the principle illustrated in FIG. 5 is particularly useful for this embodiment with a feedstock that is at least substantially gaseous, preferably a feedstock consisting at least substantially of ethane, propane, or a mixture of ethane and propane. FIG. 14 shows an exemplary saturator at an absolute operating pressure (kg / cm) at a dilution vapor (weight) ratio of 0.35. 2 The dew point (°C, vertical axis) is plotted as a function of the horizontal axis. The rectangular box (gray) represents the desired operating window for the system. Thus, a quenching water temperature of 80°C is too low to be used with the feedstock at ambient temperature to reach a steam dilution ratio of 0.35. Therefore, the method of FIG. 5 has limitations in terms of applicable pressure and dilution steam ratio (weight ratio of dilution steam to hydrocarbon feedstock), at least without additional measures. Possible measures include: additional heating of the quenching water, feedstock, or both before entering the saturator; using a relatively low diluent-to-feedstock ratio; and feeding the feedstock-diluent mixture to the pyrolysis reactor at a relatively low pressure. The inventors have discovered a number of methods particularly suitable for solving the limitations as discussed in the description of Fig. 5 to be discussed next. In a preferred embodiment, the ethylene plant according to the present invention comprises a quenching oil cooling system (51) configured to further cool the pyrolysis reactor effluent (decomposition product) and located downstream of the feed-effluent heat exchanger (90). Where present, this is generally used in combination with a quenching water cooling system (60) (or alternatively in combination with an air cooler), and the quenching water cooling system is located upstream thereof. Using a quenching oil cooling system equipped with a quenching oil cooling circuit allows for a much higher level of heat recovery. This also enables all diluted vapor to be generated in the saturator using waste heat from the effluent, even at relatively high vapor dilution ratios defined as the diluted vapor weight ratio to hydrocarbons, such as a vapor dilution ratio of about 0.35 or higher. This also reduces cooling utility requirements, such as the demand for air cooling, water cooling, or both. According to the present invention, the quenching oil cooling system is advantageous for gaseous feedstocks (particularly combined with a saturator / humidifier as described above, illustrated in FIG. 5), liquid feedstocks, and combinations thereof. The rapid cooling oil cooling system (51) may be a primary classifier system or part thereof, and this system is known in the industry, especially in plants using liquid feedstocks. Each specific suitable process of the ethylene plant of the present invention, which overcomes the disadvantages of the method exemplified in FIG. 5, is exemplified in FIG. 6. This plant / process is particularly desirable for feedstocks that are at least substantially gaseous. When in use, the feed-effluent exchanger (90) and the pyrolysis reactor (91) can be used as described above. From the furnace zone (1001), the cooled effluent (4) is sent to a high-temperature separation zone of the plant, which includes a quenching oil device (50) (typically including a primary classifier (51) and a quenching oil cooling circuit (55)), a water quenching cooling system (60) (typically a quenching water tower), an acidic water stripper (70) and a humidifier (saturator) (150). After leaving the feed-effluent heat exchanger (90), the decomposition product (4) (pyrolysis reactor effluent) enters the high-temperature separation zone of the plant. Before entering the primary classifier (50), quenching oil is typically combined with the decomposition product; typically, the quenching oil is injected into the so-called quenching oil pit before entering the primary classifier. Injecting quenching oil upstream of the furnace can be advantageously used to control the bottom temperature of the primary classifier (tower). In the primary classifier (50), the pyrolysis reactor effluent is further cooled, for example, to about 110°C to 125°C. To ensure that water does not condense in this device, the temperature is advantageously reduced to a value close to the dew point of water (typically about 75°C to 80°C) but generally higher, for example, to a temperature 10 to about 50°C higher than the dew point, preferably particularly to a temperature 20 to about 45°C higher than the dew point, and more particularly to a temperature 30°C to about 40°C higher than the dew point. The primary classifier for cracking products obtained from an essentially gaseous feedstock can be relatively simple compared to the primary classifier used for cracking liquid feedstocks. Generally, a quenching oil wash zone (51) (including a quenching oil cooling circuit) is sufficient for cracking products obtained from an essentially gaseous feedstock. In known olefin production plants, the primary classifier generally further includes at least a gasoline reflux zone (53) and optionally a heavy oil zone (52) (not shown in FIG. 6). This is not required according to the present invention, and at least not when using a primary classifier to process decomposition products obtained from a feedstock that is essentially gaseous. The present invention (as shown in FIGS. 5 and 6) allows for the dilution of the (gaseous) feedstock without generating a separate dilution vapor stream to be combined with the feedstock.Instead, by using a saturator / humidifier in which water (i.e., in liquid form) comes into contact with the feedstock to humidify the feedstock, the temperature level of the injecting water at the top inlet of the saturator / humidifier is lowered, so that the operating temperature at the bottom of the primary separator can be lowered below the dilution steam temperature level. The primary separator can be operated at 150°C, which can heat the circulating water of the saturator to a high of 140°C. This is significantly lower than the operating temperature of the dilution steam drum, which is about 165°C, and the steam dilution ratio can exceed 0.35. It should be noted that having a primary separator for a gaseous feedstock ethylene plant is not a general feature; in particular, to the knowledge of the inventors, the use of a primary separator for a gaseous feedstock ethylene plant combined with a humidifier / saturator necessary to reduce purely supplied energy demand has not been known to the art to date. The pyrolysis reactor effluent (decomposition product) is cooled by quenching oil. Advantageously, the quenching oil duty can be recovered from the pyrolysis reactor effluent. The quenching oil cooling circuit (54) originates from the heavy fuel oil product (6) collected as a liquid product at the bottom of the primary classifier. This quenching oil (10) is cooled by the quenching oil circuit cooler (55). This liquid product is typically cooled to about 80°C. It can also be cooled with the quenching oil by the quenching oil circuit cooler (55) and then further cooled by other available cooling media. If the flash point is too high for storage, a vapor stripper can be added to the flash of the lighting component. Details are not shown in the drawing. In use, a portion is typically sent to the quenching oil fitting (27), and the remainder is typically injected back into the top of the tower with a small amount of gasoline reflux (13). Compared to the reflux of a conventional liquid cracker, this flow rate is relatively small. In this case, the cooling is performed primarily by quenching oil rather than reflux. A small amount of reflux allows the fuel components to be returned. In known olefin production plants, it is common to use a quenching oil circuit cooler (55) to generate at least a portion of the diluted steam; however, it is advantageous according to the present invention for the quenching oil circuit to be used instead to heat the saturated water circuit (151) where present. The quenching oil cooling circuit can provide a complete primary separator (50) according to the present invention. In addition to cooling the pyrolysis reactor effluent, the heavy oil fraction is condensed in the primary separator. This heavy fuel oil (6) is the bottom product of the primary separator. As described above (see particularly the description in FIG. 5), the decomposition product (4) in the water quenching tower (60) is further cooled to approximately ambient conditions. Feed saturation is achieved in the saturator water heating circuit (151) using quenched water as a heating medium, for example, as described above. Process water is collected at the bottom of the saturator (150) and returned to the top of the saturator through the saturator water heating circuit (151). The water is heated using the saturator water circuit heater of the quenched water (152). In addition to plants / processes including (using) a saturator / humidifier without a quenched oil cooling system, the quenched oil cooling system allows for an additional heating step, namely heating on the quenched oil. If the plant is configured for both water quenching and oil quenching, the quenched water cooling circuit and the quenched oil cooling circuit are generally arranged as follows: when in use, the process water supplied to the saturator is heated using the saturator water circuit heater (152) on the quenched water, and then the saturator water circuit heater (153) on the quenched oil. The inlet of the new (gaseous) feedstock (1) is provided to the saturator (typically at the bottom of or near the saturator tower). The saturator is provided with an internal device that improves contact between the feedstock (typically moving upward) and the saturator water, which typically has a higher temperature than the feedstock and typically moves the saturator downward. By controlling the saturator water inlet temperature, the humidification level can be controlled to reach the correct vapor dilution level of the pyrolysis reactor. The vapor diluted hydrocarbon feedstock is returned directly to the decomposition furnace (1001) and feed-effluent exchanger (90). In principle, this method can provide most of the duty cycle to reach the required preheating and steam dilution levels of the feedstock during normal operation (e.g., steady-state operation). Sufficient waste heat is available in the effluent to saturate the feedstock close to the requirements, and the quenching oil is hot enough to provide the required temperature level. However, in some operations, dilution steam is required. These are starting situations, decocking operations, and high-temperature ambient operations. In these cases, the feedstock is not sent to a separate furnace, for example, the furnace for decocking operations. For this reason, it is desirable to provide a dilution steam drum (80) with an electric boiler (85) to provide dilution steam (24) in the flowchart. Additionally, the dilution steam can be used to supply the required amount of acid water stripping steam and equipment purge steam. The capacity of this system may be limited compared to known plants that require dilution steam during normal operation. Additionally, the stripping steam can be used to supply the requirements for the acid water stripper. During normal operation, if desired, a certain amount of diluted steam may be mixed with the steam diluted feedstock coming from the saturator to provide a small amount of superheat. It is advantageous that the contribution of the diluted steam drum (80) with the electric boiler (85) to the total diluted steam requirement is preferably less than 40%, more preferably less than 30%, and even more preferably less than 20%. The diluted steam may be sent separately to the furnace for starting, decoking, high-temperature atmosphere, and backup operation. Blow-down (26) from the dilution steam drum (80) and makeup (25) to the saturated water heating circuit prevent the accumulation of contaminants in the saturated water and dilution steam generation circuit. Therefore, it is desirable for them to be present. In particular, regarding the maximum feasible dilution steam to feedstock ratio, as discussed in the description relating to FIG. 5, as an alternative to or in combination with the use of heat from a quenching oil cooling device (illustrated by the embodiment of FIG. 6), which is a limit to the use of the saturator, the inventors realized that a higher saturation amount of feedstock (essentially gaseous) can be reached with water (steam) if the feedstock of the saturator (150) is humidified at approximately atmospheric pressure or a pressure relatively lower than atmospheric pressure, i.e., at a pressure below the pressure configured for the pyrolysis reactor to operate, and then the humidified feedstock (i.e., feedstock-diluent mixture) is compressed before being supplied to the decomposition zone. An ethylene plant / process according to the present invention comprising (using) a compressor for compressing the humidified feedstock is schematically illustrated in FIG. 7. The method may be basically the same as that of FIG. 5. However, the plant additionally includes a compressor (154) downstream of the saturator / humidifier (150), which is configured to operate at approximately atmospheric pressure. In use, the feedstock is humidified at a pressure lower than the pressure at which the electric decomposition furnace (1001) is configured to operate, and is, in particular, saturated. Typically, conventional radiative coil type pyrolysis reactors operate at pressures ranging from 1.5 to 4.0 bar, particularly from 1.7 to 3.0 bar. Other designs, such as Coolbrook's rotary dynamic device, may require lower pressures, potentially as low as about 2 bar, typically about 4 bar. The humidified gas is compressed to the correct pressure, typically in the range of 2.0 to 6 bar, particularly from 2.5 to 4 bar, using a saturated gas feedstock compressor (154) to supply the humidified feedstock (3) to the furnace zone (1001). Unlike the method of FIG. 6, this can typically operate without requiring additional (electric) power to provide the necessary level of preheating and steam dilution of the feedstock. Although this option requires power to drive the compressor, compared to using an electric boiler to generate dilution steam, this option still requires 40 to 50 percent less power depending on the supply pressure applied to the furnace. Additionally, the combination of a relatively low-pressure humidifier and a compressor to compress the hydrocarbon feedstock diluent mixture allows for a hydrogen feedstock diluent mixture at a preferably high dilution steam ratio, such as a ratio of about 0.35. Similar to the method of FIG. 6, it is advantageous to have a dilution steam drum (80) with an electric boiler (85) to supply the dilution steam (24). In a further embodiment that is particularly suitable for decomposing feedstocks that are essentially gaseous by steam decomposition, as well as for decomposing liquid feedstocks or mixtures of gaseous and liquid feedstocks, the ethylene plant comprises a dilution steam generator and a heat pump configured to generate dilution steam. FIG. 8 schematically illustrates an advantageous plant / process according to the present invention applying a heat pump and a refrigerant. The refrigerant generally has a normal boiling point in the range of 0°C to 80°C. While this range may be preferred for practical reasons, it will be understood that a refrigerant having a boiling point outside of this range may also be used. The flowchart of FIG. 8 may be nearly identical to that of FIG. 5, except that there is a dilution steam generator configured to use a condensing refrigerant (86) and a dilution steam superheater (87) using the refrigerant instead of a saturator / humidifier. When used, the refrigerant duty for generating dilution steam may be used by utilizing a heat pump to increase the quenching water duty to a higher level. Details of a particularly suitable heat pump are shown in FIG. 9. The supercooled medium-pressure refrigerant liquid (190) from the medium-pressure refrigerant drum (173) is lowered to low pressure (181) by a liquid refrigerant pressure reducing valve to produce a flashing low-pressure refrigerant (191). This refrigerant is separated from the low-pressure refrigerant drum (170). The liquid fraction is recirculated by natural circulation through a thermosiphon-type reboiler, which is a low-pressure refrigerant vaporizer (171), to evaporate using a low level of quenching water duty from a quenching water circuit. Alternatively, the low-pressure refrigerant drum (170) and the low-pressure refrigerant vaporizer (171) may be combined with a kettle-type reboiler since the refrigerant is a clean fluid. The low-pressure saturated refrigerant vapor (192) is compressed into a medium-pressure slightly superheated refrigerant vapor (195a) in a low-pressure to medium-pressure refrigerant compressor (172). The supercooled high-pressure refrigerant liquid (193) from the refrigerant economizer (175) is lowered to medium pressure (180) by the liquid refrigerant pressure reducing valve to produce a flashing medium-pressure refrigerant (194). This refrigerant is separated from the medium-pressure refrigerant drum (173). The liquid fraction is recirculated by natural circulation through a thermosiphon-type reboiler, which is a medium-pressure refrigerant vaporizer (174), to evaporate using a high level of quenching water duty from the quenching water circuit. Alternatively, the medium-pressure refrigerant drum (173) and the medium-pressure refrigerant vaporizer (174) may be combined with a kettle-type reboiler since the refrigerant is a clean fluid. The medium-pressure saturated refrigerant vapor (195b) is combined with the medium-pressure slightly superheated refrigerant vapor (195a) and superheated in the refrigerant economizer (175) to become the medium-pressure superheated refrigerant vapor (196). After being compressed to a temperature level exceeding the dilution vapor generation temperature in a medium-to-high pressure refrigerant compressor (176), the refrigerant is cooled by saturated dilution vapor in a high-pressure refrigerant coolant warmer (177). The high-pressure cooled refrigerant vapor (198) is condensed by process water from the dilution vapor drum in a high-pressure refrigerant condenser (178). The condensed high-pressure refrigerant liquid (199) is subcooled in a refrigerant economizer (175). The subcooled high-pressure refrigerant liquid (193) is recirculated. Using this method, the excess heat available in the quenching water circuit can be upgraded to a temperature level high enough to generate dilution vapor. A low-pressure refrigerant acts as the quenching water at a low temperature level, and a medium-pressure refrigerant acts as the quenching water at a high temperature level. To recover the quenching water duty, a third pressure level can be introduced as a third level instead of a second. The refrigerant pressure and the refrigerant itself are selected so that the quenching water duty can be recovered by the evaporating liquid refrigerant at various temperature levels matching the quenching water circuit cooler, and the refrigerant vapor can condense at a temperature level suitable for generating dilution vapor. To use an ethylene plant that includes a heat pump system for generating dilution steam, power is required in addition to the power for the pyrolysis reactor. However, compared to generating dilution steam using an electric boiler, the power requirement is generally about 50 to 70 percent lower, depending on the feed pressure used in the furnace. This is similar to the case of a plant using a humidifier and a compressor for humidified feedstock (see, for example, Fig. 7). An advantage of using a heat pump, such as that exemplified in Fig. 8, is that the heat pump system can take the place of an electric boiler outside of normal operation (e.g., during startup) compared to using a saturator exemplified in Fig. 6 or 7. Furthermore, embodiments using a heat pump are expected to be particularly advantageous compared to plants / processes using a saturator for high steam-to-hydrocarbon feedstock ratios, such as a ratio of 0.35 or higher. For the decomposition of liquid feedstocks or mixtures of liquid and gaseous feedstocks, at least substantially, it is particularly desirable to use a system configured to heat the feedstocks and evaporate them using heat recovered from quenching water and quenching oil, respectively. Additionally, it is desirable to use heat recovered from heavy oil. It is advantageous for the dilution steam to be generated from the heat pump quenching water duty as described above, preferably using the refrigerant method described when discussing FIG. 9. The advantage of the ethylene plant or process of the present invention including these measures is that the feedstocks can be evaporated without the aid of flue gas, and the dilution steam can be evaporated without the use of MP steam. Generating MP steam using a heat pump can reduce power consumption by more than 50% compared to using an electric MP boiler. This significantly reduces additional power requirements. Such an advantageous process is further illustrated in FIG. 10. Generally, as illustrated in FIG. 10, when in use, the feedstock (2), preferably a liquid feedstock, such as liquefied butane, pentane, or naphtha or a mixture thereof, is first preheated in a preheater (30) using a low-temperature heat source, such as quenching water outside the furnace (1001), and heated to a temperature close to the hottest temperature of the low-temperature heat source from ambient conditions, such as the hottest temperature of the cooling water circuit, typically within 5 to 10°C of the hottest temperature. If the hottest quenching water temperature is about 75 to 80°C, it can be preheated up to 70 to 75°C. Further preheating and partial evaporation of the feedstock is achieved by a hydrocarbon feedstock preheater using heavy oil (43) and a hydrocarbon partial feedstock evaporator using heavy oil (44) outside the furnace. The partially evaporated feedstock is separated in a hydrocarbon feedstock drum (45). The liquid fraction is recirculated by natural circulation through a thermosiphon-type reboiler, which is a hydrocarbon feedstock evaporator using a quenching oil vaporizer (46), to evaporate using a quenching oil duty from the quenching oil circuit. The fully evaporated feedstock is sent to a feed-effluent exchanger (90) of an electric cracker (1001). If a quenching oil duty is available and the temperature level is sufficiently high, the feedstock may be slightly superheated not only by the quenching oil but also by the hydrocarbon feedstock superheater using the quenching oil (47). To suppress the hydrocarbon partial pressure of the pyrolysis reactor, which is beneficial for product yield and coke formation inhibition, the superheated diluted steam (24) from the high-temperature separation zone (typically superheated to 30 to 50°C depending on the refrigerant compressor efficiency) is also sent to a feed-effluent exchanger (90) before being supplied to the electric pyrolysis reactor (91) in the decomposition zone (1001). A mixture of hydrocarbon feedstock and diluted steam (3) enters a feed-effluent exchanger (90) at a temperature higher than the water dew point and is heated to an inlet temperature suitable for an electric pyrolysis reactor (91) by the feed-effluent exchanger (90) using waste heat from the effluent. The pyrolysis reactor (91) supplies sensible heat and reaction heat to the steam-diluted hydrocarbon feedstock (3) to convert the feedstock into a product. Waste heat from the reactor effluent (4) is recovered by the feed-effluent exchanger (90). Next, if a heavy oil loop is available, the effluent is cooled in a quenching oil fitting (37) using quenching oil injection (27) and heavy oil injection (28). The effluent (4) from the furnace zone is sent to a high-temperature separation zone of the plant, which mainly consists of a primary classifier (50), a quenching water tower (60), an acid water stripper (70), and a diluted steam drum (80). In the primary classifier (50), the pyrolysis reactor effluent (decomposition product) is further cooled to maintain a temperature higher than the dew point of water, preferably 5°C higher than the dew point, and more preferably 5°C to 40°C higher than the dew point, to ensure that water does not condense in this tower. For example, if the dew point is about 90°C, the operating temperature can be controlled within the range of 95 to 110°C, for example, up to about 100°C, by controlling the reflux injection. The effluent is then cooled using quenching oil and heavy oil pump circulation and gasoline reflux, respectively. The quenching oil cooling circuit (54) originates from the heavy fuel oil product (6) collected at the bottom of the tower. This quenching oil (10) is cooled by the quenching oil circuit cooler (55). Some of it is sent to the quenching oil fitting (27), and the remainder is injected back into the tower below the heavy oil total discharge tray. The quenching oil circuit cooler (55) is used in this case to evaporate the feedstock of the hydrocarbon feedstock evaporator by the quenching oil vaporizer (46). The temperature of the primary classifier bottom can be adjusted to a temperature level that can achieve this. A person skilled in the art may do this based on general knowledge and the contents of the present invention, for example, by controlling the amount of quenching oil injected into the quenching oil fitting. The quenching oil cooling circuit is used in the primary classifier washing zone (51), which is the bottom zone of the column. A heavy oil cooling circuit (56) is preferably present. This provides a relatively clean / uncontaminated intermediate cooling circuit that recovers a lower level of heat from the effluent than the quenching oil circuit (54). The heavy oil (11) is collected in a discharge tray at the bottom of the primary separator heavy oil zone (52), which is located above the tower wash zone (51). The heavy oil reflux (12) is sent to the quenching oil wash zone (51) at the bottom of the tower so that the quenching oil duty can be moved to the heavy oil loop. Additionally, the heavy oil stream is sent to the quenching oil fitting (28). The remainder is cooled by the heavy oil circuit cooler (57) and returned to the tower below the light fuel oil inlet point. The heavy oil cooling circuit (56) serves as the primary separator heavy oil zone (52). In this case, heavy oil can be used to preheat and partially evaporate the hydrocarbon feedstock in a hydrocarbon feedstock preheater using heavy oil (43) and a hydrocarbon partial feedstock evaporator using heavy oil (44). Optionally, quenching oil can be used for this purpose. Gasoline reflux (13) from the gasoline / water separator (63) processes heat recovery at the top of the tower, i.e., the primary separator gasoline reflux zone (53), and transfers the recovered duty to the quenching water circuit. Suitable internal devices are installed in the tower to efficiently transfer heat from the effluent to the injection quenching oil, heavy oil, and gasoline reflux. In addition to cooling the effluent, the light oil and heavy oil fractions are condensed in the primary separator. Heavy fuel oil (6) is collected in the bottom zone (51), and light fuel oil (7) is collected at the bottom of the reflux zone (53) of the light oil fraction discharge tray. These products may be removed to control the flash point of the total fuel oil product (5) and / or to recover a lighter quenching oil fraction for viscosity control of the quenching oil circuit. Additionally, they may also be cooled. Such details are not presented as they are not relevant to the present application. In the quenching water tower (60), the effluent (4) is further cooled to approximately ambient conditions. This is accomplished using a pump circulation circuit that collects the accumulated water bottom product, called the so-called quenching water (14), and injects it at various levels of the quenching tower (60). The quenching water circuit generally has two stages: a quenching water bottom cooling circuit (64) providing the quenching water tower bottom zone (61), and a quenching water tower top cooling circuit (66) providing the quenching water tower top zone (62). The quenching water bottom circuit cooler (65) typically processes to recover as much quenching water duty as possible for a user. Such a user is, for example, a feedstock preheater (30) and / or a propylene splitter reboiler (not shown). In this case, the duty is used to preheat the feed using a feed preheater (30) and to vaporize the refrigerant using a medium-pressure refrigerant vaporizer (174) and / or a low-pressure refrigerant vaporizer (171) of the refrigerant circuit of FIG. 9. Any excess heat must typically be removed through air cooling or cooling water cooling. The refrigerant loop reduces these low-temperature utilities and shifts the quenching water duty to a level suitable for generating dilution vapor. Cooled injection water from the pump circulation circuit is used to remove heat from the decomposition gas through direct heat exchange via appropriate internal tower devices within the quenching water tower. The primary duty of this tower, in addition to cooling the decomposition gas, is to condense and recover the dilution vapor. The condensed dilution vapor is the net product coming out of the bottom of the tower in addition to a small stream of gasoline product. These are typically separated from each other using a gasoline / water separator (63). Sometimes, this separator also collects quench water for the quenching water circuit. This condensed diluted steam, called acidic water (20), contains acidic gases, which are stripped by stripped steam (21) in the acidic water stripper (70). These acidic gases (22) are returned to the quenched water tower (60). The stripped water, called process water (23), is suitable for generating diluted steam.This occurs at a higher pressure than that of the quenching water tower and acid water stripper to supply to the furnace zone (1001), generally about 2 to about 7 bara, particularly about 4 to about 6 bara. Dilution steam generation is achieved using a refrigerant. Process water is collected in a dilution steam drum (80), and through a thermosiphon circuit, dilution steam (24) is generated from the condensing refrigerant of the dilution steam generator using a condensing refrigerant (86). Superheating of the refrigerant is used to slightly superheat the dilution steam in the dilution steam superheater (87) to a temperature of 180 to 210°C before returning to the electric cracking furnace (1001) to dilute the hydrocarbon feedstock (1). Blow-down (26) from the dilution steam drum (80) and dilution steam system makeup (25) to the drum prevent the accumulation of contaminants in the dilution steam generation circuit. An alternative plant / process according to the present invention is based on the thermal integration method shown in FIG. 11. This method is similar to the method of FIG. 10 except for the thermal integration. It is also particularly useful for decomposing liquid feedstocks and mixtures of liquid and gaseous feedstocks. In a process or plant according to the present invention based on the method of FIG. 11, the quenching oil duty is not configured to be used for feed evaporation, but is used for generating diluted steam using a diluted steam generator that uses quenching oil (82). When used, feed evaporation is performed by the refrigerant of the hydrocarbon feed evaporator by condensing the refrigerant (48) in this case, and superheating is performed by the hydrocarbon feed superheater by the refrigerant (49). The performance of the process or plant based on Fig. 10 or Fig. 11 is very similar in both methods. For the method of Fig. 11, the cooling circuit must be adjusted to supply heat to the feedstock evaporator (49). Depending on the feedstock, this may be higher or lower than the diluted steam generation temperature. To perform this duty, a separate compressor may be installed or two compressors may be placed in series. FIGS. 12 and 13 illustrate a cooling compressor system that can be used in a process or plant according to the present invention. Such a cooling compressor can be installed on a single shaft and, if necessary, also in a single casing. The cooling compressor system can be used to further reduce power requirements. FIG. 12 shows two separate high-pressure loops connected in parallel, namely a high-pressure cooling circuit branch (1010) and a high-high-pressure cooling circuit branch (1011). Each of these two branches operates at a different pressure and corresponding operating temperature to best match the temperature levels of dilution vapor generation and feedstock evaporation. This will result in the lowest power requirements. One branch handles feedstock evaporation through a hydrocarbon feedstock evaporator by condensing the refrigerant (48), and the other branch handles dilution vapor generation through a dilution vapor generator using the condensed refrigerant (86). If the operating temperature of the hydrocarbon feedstock evaporator is higher than the operating temperature of the dilution vapor generator, the hydrocarbon feedstock evaporator will be operated by the high-high-pressure branch (1011) and the dilution vapor generator will be operated by the high-pressure branch (1010). If the operating temperature of the hydrocarbon feedstock evaporator is lower than the operating temperature of the dilution steam generator, the hydrocarbon feedstock evaporator will be operated by the high-pressure branch (1010) and the dilution steam generator will be operated by the high-pressure branch (1011). The subcooled medium-pressure refrigerant liquid (190) from the medium-pressure refrigerant drum (174) is lowered to low pressure (181) by a liquid refrigerant pressure reducing valve to produce a flashing low-pressure refrigerant (191). This refrigerant is separated from the low-pressure refrigerant drum (170). The liquid fraction can be recirculated by natural circulation through a thermosiphon-type reboiler, which is a low-pressure refrigerant vaporizer (171), to evaporate using a low level of quenching water duty from a quenching water circuit. Alternatively, the low-pressure refrigerant drum (170) and the low-pressure refrigerant vaporizer (171) can be combined with a kettle-type reboiler since the refrigerant is a clean fluid. The low-pressure saturated refrigerant vapor (192) is compressed into a medium-pressure slightly superheated refrigerant vapor (195a) in a low-pressure to medium-pressure refrigerant compressor (172). The supercooled high-pressure refrigerant liquid (206) from the high-high pressure refrigerant economizer (182) and the supercooled high-pressure refrigerant liquid (193) from the high-pressure refrigerant economizer (175) are lowered to medium pressure (180) by a liquid refrigerant pressure reducing valve to produce a flashing medium pressure refrigerant (194). This refrigerant is separated in a medium pressure refrigerant drum (173). The liquid fraction can be recirculated by natural circulation through a thermosiphon-type reboiler, which is a medium pressure refrigerant vaporizer (174), to evaporate using a high level of quenching water duty from a quenching water circuit. Alternatively, the medium pressure refrigerant drum (173) and the medium pressure refrigerant vaporizer (174) may be combined with a kettle-type reboiler, since the refrigerant is a clean fluid. Medium pressure saturated refrigerant vapor (195b) is combined with medium pressure slightly superheated refrigerant vapor (195a). At this point, the combined streams (195a and 195b) are sent to two parallel cooling circuit branches (1010 and 1011). The portion sent to the high-pressure branch (1010) is superheated in the high-pressure refrigerant economizer (175) to become medium-pressure superheated refrigerant vapor (196). After being compressed to a temperature level exceeding the dilution vapor generation or hydrocarbon feedstock evaporation temperature (whichever temperature level is lower) in the low-pressure to medium-pressure to high-pressure refrigerant compressor (176), the refrigerant is cooled by saturated dilution vapor or hydrocarbon feedstock in the high-pressure refrigerant coolant heater (177) using a dilution vapor superheater using the refrigerant (87) or a hydrocarbon feedstock superheater using the refrigerant (49), respectively. The high-pressure cooled refrigerant vapor (198) is condensed by process water from the dilution vapor drum or hydrocarbon feedstock in the high-pressure refrigerant condenser (178) using a dilution vapor generator using the condensing refrigerant (86) or a hydrocarbon feedstock evaporator using the condensing refrigerant (48), respectively. The condensed high-pressure refrigerant liquid (199) is supercooled in a high-pressure refrigerant economizer (175). The supercooled high-pressure refrigerant liquid (193) is recirculated. The portion sent to the high-high pressure branch (1011) is superheated in the high-high pressure refrigerant economizer (182) to become medium-pressure superheated refrigerant vapor (196). After being compressed to a temperature level exceeding the dilution vapor generation or hydrocarbon feedstock evaporation temperature (whichever temperature level is higher) in the medium-to-high pressure refrigerant compressor (183), the refrigerant is cooled by saturated dilution vapor or hydrocarbon feedstock in the high-high pressure refrigerant coolant heater (185) using the dilution vapor superheater using the refrigerant (87) or the hydrocarbon feedstock superheater using the refrigerant (49), respectively. The high-pressure fully heated refrigerant vapor (186) is condensed by process water or a hydrocarbon feedstock from a diluted vapor drum in a high-pressure refrigerant condenser (187) using a diluted vapor generator using a condensed refrigerant (86) or a hydrocarbon feedstock evaporator using a condensed refrigerant (48), respectively. The condensed high-pressure refrigerant liquid (205) is subcooled in a high-pressure refrigerant economizer (182). The subcooled high-pressure refrigerant liquid (206) is recirculated. Using this method, the excess heat available in the quenching water circuit can be upgraded to a temperature high enough to generate diluted steam and evaporate hydrocarbon feedstocks in two separate branches of the cooling system. The method of FIG. 13 is similar to that of FIG. 12, except that the split between the two branches is downstream of the medium-to-high pressure compressor (176) and the medium-to-high pressure compressor (183) is replaced by the high-to-high pressure compressor (183) so that the compressors of the branches (1010 and 1011) are in series instead of parallel. The singular forms used herein are intended to include plural forms as well; for example, unless otherwise specified in the context, "decomposition furnace" includes "decomposition furnaces"; "burner" includes "multiple burners," etc. The term "or" includes any and all combinations of one or more of the listed items associated with it (e.g., "one of ~ or ~") unless otherwise specified in the context. It will be understood that the terms "include" and "include" specify the presence of the mentioned feature but do not exclude the presence or addition of one or more other features. Unless otherwise specified, where a specific step of a method is described as a subsequent step of another, it will be further understood that this may be followed immediately by said other step, or that one or more intermediate steps may be performed before the specific step. Likewise, when a connection between structures or components is described, it will be understood that this connection may be established directly or through intermediate structures or components unless otherwise specified. In the context of this application, the term “about” includes a deviation of 10% or less, more particularly 5%, and more particularly 3% or less from a given value. In this specification, the terms “(at least) substantial” or “(at least) essential” are used to mean having the general characteristics or functions of what is specified. When referring to quantifiable characteristics, these terms are used to indicate, in particular, at least 75%, in particular 90%, and more particularly 95% of the maximum value of said characteristic. In this specification, the term “essentially absent” is used to indicate that a substance is generally absent (below the detection limit achievable by analytical techniques available on the effective filing date) or is present in an amount so small as not to have a significant effect on the characteristics of the product in which said substance is essentially absent. The term "high-pressure steam" (HP steam) is well known in the art. By experience, the pressure of HP steam is generally at least about 40 barg, for example 80 barg or more, for example about 100 barg to about 130 barg, for example 100 to 125 barg. The term "medium pressure steam" (MP steam) means steam with an upper pressure limit of 40 barg. As used herein, the term MP is typically in the range of about 6 to about 20 bara, more particularly in the range of 7 to 13 bara. The term "low-pressure steam" refers to steam having a pressure lower than MP steam pressure. The present invention is described more fully herein with reference to the accompanying drawings, in which embodiments of the invention are illustrated. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and / or cross-sectional examples of possible ideal embodiments and intermediate structures of the invention. In the description and drawings, the same number designates the same element throughout. Relative terms and their derivatives should be interpreted as indicating the orientations depicted in the drawings being described or discussed. These relative terms are for convenience of description and do not require the system to be configured or operated in a specific orientation unless otherwise specified. For the purposes of clarity and concise description, features are described herein as part of the same or distinct embodiments, but it will be understood that the scope of the invention may include embodiments having all or some combinations of the described features. Examples The present invention will now be illustrated according to the following non-limiting embodiments. To demonstrate how the present invention can be applied, a number of examples of gaseous feedstock decomposers have been prepared: Comparative Example 1 having a conventional flowchart according to FIG. 1 serving as a basic case for comparison; Example 2 having a flowchart including a primary classifier and a humidifier / saturator according to FIG. 6; Example 3 having a flowchart including a low-pressure humidifier / saturator and a diluted feedstock compressor according to FIG. 7; and Example 4 having a flowchart according to FIG. 8 including a heat pump according to FIG. 9. An ethane cracker with an annual capacity of 1,500 kilotons (kta) was selected as the basic case. Unconverted ethane and propane are recirculated back into the furnace area as recirculated gas and mixed with a new gaseous feedstock. This combined feedstock is handled in the cracking furnace of all cases. Example 1, which serves as a basic example for comparison, has 359.8 t / h of gaseous feedstock, 233.5 t / h of fresh ethane feedstock, and 126.3 t / h of recirculated gas (mainly recirculated ethane). This is supplied at 20°C and heated to a maximum of 55°C in a hydrocarbon feedstock preheater (30). In the convection zone of the furnace, the feedstock is further heated to 225°C in a hydrocarbon feedstock preheater (31). Dilution steam at 180°C is added to dilute the feedstock. The diluted feedstock is heated to 703°C in a steam-diluted hydrocarbon feedstock superheater (33). At 4 bara, the diluted gas is supplied through a number of parallel radiating coils via critical flow venturis in a decomposition furnace, which is a pyrolysis reactor inside the fuel combustion chamber (34), where it is heated to a maximum of 855°C. The pressure at the reactor outlet is 1.8 bara. During this process, the feedstock is converted into a product. The conversion does not stop at the reactor outlet but continues through the passage to the transfer line exchanger (35) and within the transfer line exchanger itself. In the passage from the coil to the transfer line exchanger, the temperature drops to 840°C due to an endothermic reaction. In the transfer line exchanger, the pyrolysis reactor effluent (4) (also called the decomposition product) is cooled to 350°C to generate high-pressure steam. Next, the effluent is further cooled to 180°C in the secondary transfer line exchanger (36) while heating the boiler feedwater. The effluent is further cooled to 30°C in a quenching water tower (60) to produce decomposition gas products (9). During this process, the diluted steam is condensed with a small amount of gasoline (8). The gasoline / acidic water mixture is separated at 80°C in a gasoline-water separator. The acidic water (20) is pumped to an acidic water stripper (70), where it is stripped to remove dissolved acidic gas (22) at 1.7 bara. The washed process water (23) is pumped to a diluted steam drum (80), where the diluted steam (24) is generated from the condensed MP steam at 6 bara and 160°C. The diluted steam is superheated to 180°C in a superheater (83) by the superheated MP steam. The superheated diluted steam is sent to a furnace to dilute the gas feedstock (1). The diluted steam production rate is 125.9 t / h. This means that the steam dilution ratio is 0.35 (125.9 t / h / 359.8 t / h feedstock). In addition, 12.5 t / h of acidic water strip steam (21) is generated to strip acidic water. In Example 2, the same gas feedstock of 359.8 t / h is used. This is supplied at 20°C at the bottom of the saturator (150) operating at 6 bar. In the saturator, the gas comes into contact with 140°C circulating saturator water flowing into the top of the saturator. This is a substantially possible temperature for heating the saturator circulating water (151) with 150°C quenching oil and 77°C quenching water. 103 t / h of the process water is mixed with the water in the circulating saturator. This is the amount that constitutes the amount of water evaporating in the saturator. The remaining process water is sent to the dilution steam drum (80) together with the electric boiler (80) to produce 22.8 t / h of dilution steam generated at 6 bara and 160°C, increasing the total steam dilution to 125.9 t / h, with a corresponding steam dilution ratio of 0.35 (125.9 t / h / 359.8 t / h feedstock). Additionally, 12.5 t / h of acid water strip steam (21) is produced to strip acid water. Saturated steam diluted ethane (3) is sent to the feed-effluent exchanger (90) of the electric cracking furnace zone (1001) at a temperature of 123°C, where it is heated to 703°C before entering the electric pyrolysis reactor (91). In the pyrolysis reactor, the diluted feed is heated to a maximum of 855°C. The pressure at the reactor outlet is 1.8 bara. In the passage from the reactor to the feed-effluent exchanger, the temperature drops to 840°C due to an endothermic reaction. In the feed-effluent exchanger, the pyrolysis reactor effluent (4) (also called the cracking product) is cooled to 330°C relative to the diluted hydrocarbon feed (3). The effluent is further cooled to 170°C in the quenching oil fitting (37) and to 120°C in the primary classifier (50) using circulating quenching oil (54). In the primary classifier, a small amount of liquid heavy fuel oil (6) is condensed. The bottom of the primary classifier can operate at 150°C to produce a quenching oil stream of 150°C. This quenching oil is cooled to 110°C to control the top temperature of the primary classifier to 120°C. This quenching oil is entirely used to heat the saturated circulating water (151) to 140°C using the quenching oil circuit cooler (55) (via the saturated water circuit heater on the quenching oil duty (153)), as already mentioned above. Finally, the effluent is cooled to 30°C in the quenching water tower (60) using circulating quenching water (64 and 66) to produce decomposition gas products (9). The tower is operated at 77°C, just below the dew point. The quenching water bottom circuit cooler (65) is used to heat the saturated circulating water (151) to 72°C (through the saturated water circuit heater of the quenching water (152)) before it enters the saturated water circuit heater on the quenching oil duty (153). In the quenching water tower, diluted steam is condensed with a small amount of gasoline (8). The gasoline / acidic water mixture is separated at 80°C in a gasoline-water separator. The acidic water (20) is pumped to an acidic water stripper (70), where it is stripped to remove dissolved acidic gas (22) at 1.7 bara. The cleaned process water is pumped to a saturator (150) and a diluted steam drum (80). In Example 3, the same gas feedstock of 359.8 t / h is used. This is supplied at 20°C at the bottom of the saturator (150). Unlike the previous example, this tower does not operate at 6 bar but at 1.1 bar. In the saturator, the gas comes into contact with 75°C circulating saturator water flowing into the top of the saturator. This is a practically possible temperature to heat the saturator circulating water (151) with 80°C quenched water. 125.9 t / h of the process water is mixed with the water in the circulating saturator. This is the amount that constitutes the amount of water evaporating in the saturator. This corresponds to a steam dilution ratio of 0.35 (125.9 t / h / 359.8 t / h feedstock). The remaining process water is sent to the diluted steam drum (80) together with the electric boiler (80) to produce 12.5 t / h of acidic water strip steam. The vapor-diluted ethane (3) is compressed to 6 bar in a saturated gas feedstock compressor (154) to raise the temperature from 74°C to 214°C. The compressed gas is sent to a feed-effluent exchanger (90) in the electric decomposition furnace zone (1001), where it is heated to a maximum of 703°C before entering the electric pyrolysis reactor (91). In the pyrolysis reactor, the diluted feedstock is heated to a maximum of 855°C. The pressure at the reactor outlet is 1.8 bara. In the passage from the reactor to the feed-effluent exchanger, the temperature drops to 840°C due to an endothermic reaction. In the feed-effluent exchanger, the pyrolysis reactor effluent (4) (also called the decomposition product) is cooled to 400°C relative to the diluted hydrocarbon feedstock (3). The effluent is further cooled to 30°C in a quenching water tower (60) using circulating quenching water (64 and 66) to produce decomposed gas products (9). The tower is operated at 80°C. A quenching water bottom circuit cooler (65) is used to heat the saturated circulating water (151) to 75°C (through the saturated water circuit heater of the quenching water (152)). In the quenching water tower, diluted steam is condensed with a small amount of gasoline (8). The gasoline / acidic water mixture is separated at 80°C in a gasoline-water separator. The acidic water (20) is pumped to an acidic water stripper (70), where it is stripped to remove dissolved acidic gas (22) at 1.7 bara. The cleaned process water is pumped to a saturator (150) and a diluted steam drum (80). In Example 4, the same gaseous feedstock of 359.8 t / h is used as in other cases. It is supplied at 20°C and heated to a maximum of 75°C in a hydrocarbon feedstock preheater (30). Dilution steam at 200°C is added to dilute the feedstock. The diluted feedstock is sent to a feed-effluent exchanger (90) in the electric cracking furnace zone (1001) and heated to a maximum of 703°C before entering the electric pyrolysis reactor (91). In the pyrolysis reactor, the diluted feedstock is heated to a maximum of 855°C. The pressure at the reactor outlet is 1.8 bara. In the passage from the reactor to the feed-effluent exchanger, the temperature drops to 840°C due to an endothermic reaction. In the feed-effluent exchanger, the pyrolysis reactor effluent (4) (also called decomposition product) is cooled to 316°C with respect to the diluted hydrocarbon feedstock (3). The effluent is further cooled to 30°C in a quenching water tower (60) using circulating quenching water (64 and 66) to produce decomposed gas products (9). The tower is operated at 80°C. A quenching water bottom circuit cooler (65) is used to heat the saturated circulating water (151) to 75°C (through the saturated water circuit heater of the quenching water (152)). In the quenching water tower, diluted steam is condensed together with a small amount of gasoline (8). The gasoline / acidic water mixture is separated at 80°C in a gasoline-water separator. The acidic water (20) is pumped to an acidic water stripper (70), where it is stripped to remove dissolved acidic gas (22) at 1.7 bara. The cleaned process water is pumped to a diluted steam drum (80) by a diluted steam generator using a condensing refrigerant (86) to produce 125.9 t / h of diluted steam generated at 6 bara and 160°C, which is required to have a diluted steam ratio corresponding to 0.35 (125.9 t / h / 359.8 t / h feedstock). Additionally, 12.5 t / h of acidic water strip steam (21) is generated to strip the acidic water. The diluted steam is superheated in a diluted steam superheater (87) using a superheated refrigerant. Refrigerant vapor is generated at 62.5°C and 70°C, respectively, by two rapid-cooling water bottom circuit coolers (65) using low-pressure and medium-pressure refrigerant vaporizers (171, 174). One is cooled from 80°C to 75°C with rapid-cooling water, and the other is further cooled to 67°C with rapid-cooling water. High-pressure superheated refrigerant vapor at 216°C is generated using low-pressure to medium-pressure and medium-pressure to high-pressure compressors (172, 176), respectively. This is used to superheat the diluted vapor in a diluted vapor superheater (87) (via the high-pressure refrigerant deheater (177)) and to generate the diluted vapor itself in a diluted vapor generator (via the high-pressure refrigerant condenser (178)) using condensed refrigerant (86). Table 1 shows an overview of the duty cycles of various examples along with the output of the relevant compressor. [Table 1] Table 2 shows the power demand for various embodiments and the potential reduction of the defined excess power when comparing the power demand for diluting the feedstock with the power demand required to generate diluted steam using the traditional method calculated in Example 1, namely 90.3 MW in the absence of MP steam. This shows that the flowchart in Fig. 6 (Example 2) has the highest potential reduction of 73%. The reduction value for the flowchart in Fig. 7 (Example 3) is 45%. The flowcharts in Figs. 8 and 9 (Example 4) have an intermediate level of 60%. [Table 2] Legend for the drawing 1. Hydrocarbon feedstock (gas) 2. Hydrocarbon feedstock (liquid) 3. Diluted hydrocarbon feedstock 4. Pyrolysis reactor effluent (also referred to as decomposition products) 5. Total Fuel Oil Products 6. Heavy fuel oil products 7. Light fuel oil products 8. Heavy Pyrolysis Gasoline 9. Decomposition gas products (leave high-temperature zone, cooled / washed) 10. Quick cooling oil 11. Heavy oil 12. Heavy oil reflux 13. Gasoline Recirculation 14. Quickly chilled water 20. Acidic water 21. Stripping Steam 22. Acid gas 23. Process number 24. Diluted Vapor 25. Dilution Vapor System Makeup 26. Blowdown 27. Quenching oil for quenching fittings 28. Heavy oil into quenched fittings 30. Hydrocarbon feedstock preheater outside the furnace 31. Hydrocarbon feedstock preheater in the furnace convection zone 32. Hydrocarbon feedstock evaporator in the furnace convection zone 33. Steam-diluted hydrocarbon feedstock superheater in the furnace convection zone 34. Pyrolysis reactor inside the combustion chamber of a fuel combustion furnace 35. Transfer line switch generating high-pressure steam 36. Secondary transfer line switch 37. Quick-cooling oil fittings 43. Hydrocarbon feedstock preheater using heavy oil 44. Hydrocarbon partial feedstock evaporator using heavy oil 45. Hydrocarbon feedstock drums 46. ​​Hydrocarbon feedstock evaporator using quenched oil 47. Hydrocarbon feedstock superheater using quenched oil 48. Hydrocarbon feedstock evaporator using condensing refrigerant 49. Refrigerant-driven hydrocarbon feedstock superheater 50. Primary classifier 51. Primary classifier washing area 52. Primary Separator Heavy Oil Zone 53. Primary Separator Gasoline Recirculation Zone 54. Quick Oil Cooling Circuit 55. Quick-cooling oil circuit cooler 56. Heavy oil cooling circuit 57. Heavy oil circuit cooler 60. Quick-chilling water tower 61. Bottom section of the rapid chilling water tower 62. Top section of the rapid chilled water tower 63. Gasoline / Water Separator 64. Rapid cooling water bottom cooling circuit 65. Quick-cooling water bottom circuit cooler 66. Rapid cooling water top cooling circuit 67. Quick-cooling water top circuit cooler 70. Acid Water Stripper 80. Dilution Vapor Drum 81. Dilution vapor generator using MP vapor 82. Dilution steam generator using quenching oil 83. External dilution steam superheater 84. Dilution steam superheater in the furnace convection zone 85. Electric Boiler 86. Dilution vapor generator using condensing refrigerant 87. Diluted steam superheater using refrigerant 90. Supply-Effluent Exchanger 91. Electric pyrolysis reactor 101. Demineralized Water Makeup 102. Strip Steam 103. Deaerator vent 104. Boiler Supply Water 105. Saturated high-pressure steam 106. Steam drum blow-down 107. Superheated high-pressure steam 108. Medium-pressure steam 109. Medium pressure condensate 110. Condensed vapor in a vacuum 111. Vacuum Condensate 112. Combined condensate 120. Deaerator 121. Boiler supply water preheater 122. High-pressure steam drum 123. High-pressure steam superheater 124. Back-pressure steam turbine from high pressure to medium pressure 125. Condensation Steam Turbine from Medium Pressure to Vacuum 126. Condensing steam turbine surface condenser 150. Saturation period 151. Saturated Water Heating Circuit 152. Saturator water circuit heater in rapid cooling phase 153. Saturated water circuit heater on quenching oil duty 154. Saturated Gas Feed Compressor 170. Low-pressure refrigerant drum 171. Low-pressure refrigerant vaporizer 172. Low to medium pressure refrigerant compressor 173. Medium-pressure refrigerant drum 174. Medium-pressure refrigerant vaporizer 175. High-pressure refrigerant economizer 176. Medium to high pressure refrigerant compressor 177. High-pressure refrigerant heat absorber 178. High-pressure refrigerant condenser 179. High-pressure condensing refrigerant drum 180. Medium-pressure liquid refrigerant pressure reducing valve 181. Liquid refrigerant pressure reducing valve to low pressure 182. High-to-High Pressure Refrigerant Economizer 183. Medium to High-High Pressure Refrigerant Compressors 184. High-pressure to high-high-pressure refrigerant compressors 185. High-to-high pressure refrigerant warmer 186. High-to-high pressure refrigerant condenser 187. High-High Pressure Condensing Refrigerant Drum 190. Saturated medium-pressure refrigerant liquid 191. Flashing Low-Pressure Refrigerant 192. Low-pressure saturated refrigerant vapor 193. Medium-pressure slightly superheated refrigerant vapor 194. Medium-pressure saturated refrigerant vapor 195a. Medium pressure slightly superheated refrigerant vapor 195b. Medium-pressure saturated refrigerant vapor 196. Medium-pressure superheated refrigerant vapor 197. High-pressure superheated refrigerant vapor 198. High-pressure fully heated refrigerant vapor 199. Condensed high-pressure refrigerant liquid 200. Saturated high-pressure refrigerant liquid 201. High-pressure superheated refrigerant vapor 202. High-pressure superheated refrigerant vapor 203. High-to-high pressure fully heated refrigerant vapor 204. Condensed high-to-high pressure refrigerant liquid 205. Saturated High-High Pressure Refrigerant Liquid 1000. Combustion decomposition furnace 1001. Electric disassembly furnace zone 1010. High-pressure cooling circuit branch 1011. High-High Pressure Cooling Circuit Branch

Claims

Claim 1 An ethylene plant comprising an electric pyrolysis reactor (91), wherein the electric pyrolysis reactor (91) comprises a feed inlet for a hydrocarbon feedstock-diluent mixture and an outlet for a pyrolysis reactor effluent containing ethylene, and the ethylene plant further comprises a heat exchanger (90) configured to transfer heat from the pyrolysis reactor effluent to a feed for the pyrolysis reactor, wherein the heat exchanger (90) comprises a feed inlet and a feed outlet upstream of the pyrolysis reactor and further comprises a pyrolysis reactor effluent inlet and a pyrolysis reactor effluent outlet, wherein a feed passage exists between the feed outlet of the heat exchanger and the feed inlet of the pyrolysis reactor, and further comprises a feed passage between the reactor effluent outlet of the pyrolysis reactor and the decomposition gas inlet of the heat exchanger, and the plant further comprises a humidifier that saturates the hydrocarbon feedstock with process water originating from the heat exchanger (90) to provide a hydrocarbon feedstock-diluent mixture, and the humidifier is of the feed inlet of the heat exchanger (90). Ethylene plant located upstream. Claim 2 In paragraph 1, the plant further comprises a cooling zone configured to further cool the reactor effluent generated in the pyrolysis reactor to ambient conditions without generating high-pressure steam, and the cooling zone is located downstream of the decomposition gas outlet of the heat exchanger (90), ethylene plant. Claim 3 In paragraph 2, the cooling zone comprises a cooling system (60) selected from the group of a quenching water cooling system configured to further cool the reactor effluent with quenching water and an air cooler configured to further cool the reactor effluent with air; optionally, the cooling zone comprises a quenching oil cooling system (51) configured to further cool the reactor effluent with quenching oil upstream of the quenching water cooling system or the air cooler, an ethylene plant. Claim 4 An ethylene plant according to any one of claims 1 to 3, wherein the plant comprises a compressor configured to pressurize a humidified hydrocarbon feed, the compressor being present in a humidified hydrocarbon feed passage between the outlet for the humidified hydrocarbon feed of the humidifier (150) and the feed inlet of the heat exchanger (90), and the heat exchanger being configured to transfer heat from the decomposition gas from the pyrolysis reactor to the feed for the pyrolysis reactor. Claim 5 In paragraph 4, the plant further comprises a cooling zone configured to further cool the reactor effluent generated in the pyrolysis reactor to ambient conditions without generating high-pressure steam, the cooling zone being downstream of the decomposition gas outlet of the heat exchanger (90); the cooling zone comprises a cooling system (60) selected from the group of a quenching water cooling system configured to further cool the reactor effluent with quenching water and an air cooler configured to further cool the reactor effluent with air; the cooling zone comprises a quenching oil cooling system (51) configured to further cool the reactor effluent with quenching oil upstream of the quenching water cooling system or the air cooler; the plant further comprises a heat exchanger (153) configured to transfer heat from the quenching oil to water to humidify the hydrocarbon feedstock in the humidifier (150), the heat exchanger comprising a quenching oil passage and a water passage, wherein the quenching oil passage is configured to transfer the quenching oil from the quenching oil cooling system (51) to the heat exchanger (153) through a passage configured to cool the quenching oil. An ethylene plant having a quenching oil outlet connected to the quenching oil inlet of a quenching oil cooling system (51) through a quenching oil inlet and a quenching oil recirculation passage connected to the quenching oil outlet of the system (51), wherein the water passage of the heat exchanger (153) has an inlet for water heated in the heat exchanger (153) and a water outlet connected to the water inlet of a humidifier (150). Claim 6 In any one of claims 1 to 3, the plant comprises a dilution steam generator comprising a heat pump system configured to generate dilution steam; optionally, the heat pump system comprises a plurality of heat sources, a plurality of sinks, or both; additionally optionally, the plant comprises a heat exchanger (30, 43) for preheating a hydrocarbon feedstock upstream of the feed inlet of a heat exchanger (90) upstream of a pyrolysis reactor (91), wherein the heat exchanger is configured to receive heat from one or more of quenching water, quenching oil, and heavy oil used to cool the pyrolysis reactor effluent, an ethylene plant. Claim 7 An ethylene plant according to claim 6, comprising a hydrocarbon feed evaporator (46) configured to receive heat from a quenching oil used in a quenching oil cooling system (51) for the evaporation of a hydrocarbon feed, wherein the quenching oil cooling system is configured to further cool the pyrolysis reactor effluent with the quenching oil or to receive condensation heat from a steam refrigerant (48) of a heat pump for the evaporation of a hydrocarbon feed. Claim 8 In claim 7, the hydrocarbon feed evaporator (44) is configured to receive at least a portion of the heat for evaporating the hydrocarbon feed from heavy oil used in the quenching oil cooling system (52), and the heavy oil cooling system is configured to further cool the pyrolysis reactor effluent with heavy oil, in an ethylene plant. Claim 9 An ethylene plant according to any one of paragraphs 1 to 3, wherein the plant includes a power connection configured to provide electricity to an electric pyrolysis reactor, and the power connection is a connection to a power system that produces electricity from a renewable source. Claim 10 A method for producing a pyrolysis reactor effluent containing ethylene from a hydrocarbon feed using an ethylene plant according to any one of claims 1 to 3, comprising the steps of: supplying a hydrocarbon feedstock-steam mixture to an electric pyrolysis reactor (91); decomposing the hydrocarbon feedstock in the presence of steam in the electric pyrolysis reactor (91) of the ethylene plant to produce a pyrolysis reactor effluent containing ethylene; supplying the pyrolysis reactor effluent to a heat exchanger (90) configured to transfer heat from the pyrolysis reactor effluent to the hydrocarbon feedstock-steam mixture before the decomposition of the hydrocarbon feedstock; and cooling the pyrolysis reactor effluent to a temperature of less than 500°C at the outlet of the pyrolysis reactor effluent of the heat exchanger (90) by transferring heat from the pyrolysis reactor effluent to the hydrocarbon feedstock-steam mixture of the heat exchanger (90). Claim 11 A method according to claim 10, wherein a gaseous hydrocarbon feedstock is used as a hydrocarbon feedstock, wherein the gaseous hydrocarbon feedstock is humidified in a humidifier (150) upstream of the feedstock inlet of a heat exchanger (90) to provide a hydrocarbon-diluent mixture. Claim 12 In claim 10, the liquid hydrocarbon feedstock is used as a hydrocarbon feedstock, wherein the ethylene plant includes a cooling zone comprising a quenching water cooling system (60) provided with a quenching water cooling circuit (65) and a primary classifier (50), the primary classifier includes a quenching oil cooling system (51) provided with a quenching oil cooling circuit (55) and a heavy oil zone (52) provided with a heavy oil cooling circuit (57), and the cooling circuit is used to preheat and evaporate the liquid hydrocarbon feedstock, mix the evaporated hydrocarbon feedstock with diluted steam, and supply the resulting mixture to a heat exchanger (90). Claim 13 In paragraph 10, a mixture of liquid feedstock and gaseous hydrocarbon feedstock is used as a hydrocarbon feedstock. Claim 14 In claim 10, the method comprises the steps of: supplying a hydrocarbon-vapor mixture to a heat exchanger (90) configured to transfer heat from a pyrolysis reactor effluent to a feed for a pyrolysis reactor at a temperature higher than the water dew point of the hydrocarbon-vapor mixture; heating the hydrocarbon-vapor mixture to an inlet temperature suitable for an electric pyrolysis reactor (91) using waste heat from the pyrolysis reactor effluent of the heat exchanger (90); and supplying the heated hydrocarbon-vapor mixture from the heat exchanger (90) to an electric heated pyrolysis reactor (91), wherein the pyrolysis reactor further heats the heated hydrocarbon-vapor mixture to a pyrolysis reaction temperature, and the pyrolysis reactor provides a decomposition product by providing reaction heat to convert the hydrocarbon feed into a decomposition product; Optionally, the inlet temperature of the electric pyrolysis reactor (91) is in the range of 650°C to 730°C for gaseous hydrocarbon feedstock, or in the range of 570°C to 650°C for liquid hydrocarbon feedstock, a method. Claim 15 In paragraph 10, the heat of the cooling circuit of the ethylene plant is used for at least one purpose selected from dilution steam generation, feedstock preheating, and evaporation of liquid feedstock. Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete

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