Low CO2 Emission and Hydrogen Injection Cracking Heater for Olefin Production

Abstract

1. A process comprising: preheating a hydrocarbon feed in a first preheat zone in a convection section and recovering a preheated hydrocarbon stream; heating the preheated hydrocarbon stream in a secondary transfer line exchanger and recovering a heated hydrocarbon stream; supplying the heated hydrocarbon stream to a second preheat zone in the convection section to vaporize a portion of the heated hydrocarbon stream and recovering a cracking feed stream; cracking hydrocarbons in the cracking feed stream in one or more coils in a radiant section and recovering a cracked hydrocarbon product; and cooling the cracked hydrocarbon product in the secondary transfer line exchanger in indirect heat exchange with the preheated hydrocarbon stream and recovering a cooled hydrocarbon product stream.

Description

[Technical field]

[0001] The embodiments disclosed herein relate generally to the integrated pyrolysis and hydrocracking of hydrocarbon mixtures, such as whole crude oil or other hydrocarbon mixtures, to produce olefins and other chemicals. One method of providing reaction heat is an air heater. Currently, plants primarily use fuel-fired air heaters, which result in emissions associated with combustion. [Background technology]

[0002] Traditionally, fired heaters are used to heat and crack hydrocarbon feedstocks to produce ethylene. Similarly, ethane is cracked to produce ethylene. Although ethane produces significant amounts of hydrogen, after meeting the requirements for acetylene hydrogenation (to produce additional ethylene) and methylacetylene and propadiene (MAPD) ​​hydrogenation, the excess hydrogen is often not sufficient to meet the heat requirements in traditional cracking heaters. This creates the need to add additional methane or other hydrocarbons to the fuel gas mix. The additional hydrocarbons that are burned produce CO2 and therefore contribute to CO2 emissions.

[0003] Currently, cracking heaters are fired with fossil fuels to provide the process heat load, which is the heat load required for the cracking reaction, as well as for vaporizing the feedstock and preheating the feedstock and dilution steam. This constitutes the heat of reaction and sensible heat. Some of the sensible heat and excess energy in the exhaust gas is recovered as high-pressure steam and preheat boiler feed water. Fuel consumption is high because a significant amount of steam is generated, some of which is used to superheat the steam and preheat the boiler feed water.

[0004] To reduce CO2 emissions in heaters, one method proposed in the prior art is to use air preheating or to preheat the fuel. When air preheating is used in conventional heater designs, the super high pressure (SHP) steam production is high and therefore the reduction in fuel consumption is small. Summary of the Invention

[0005] Integrated pyrolysis and hydrocracking processes have now been developed for flexible processing of whole crude oils and other hydrocarbon mixtures, including high boiling coke precursors. Embodiments herein may advantageously reduce the capital and energy requirements associated with operating an integrated pyrolysis and hydrocracking unit.

[0006] In one aspect, the embodiments disclosed herein relate to an integrated pyrolysis and hydrocracking process for converting a hydrocarbon mixture to produce olefins, the process includes: preheating a hydrocarbon feedstock in a first preheat zone of a convection section and recovering a preheated hydrocarbon stream; heating the preheated hydrocarbon stream in a secondary transfer line exchanger and recovering a heated hydrocarbon stream; feeding the heated hydrocarbon stream to a second preheat zone of a convection section to vaporize a portion of the heated hydrocarbon stream and recover a cracking feed stream; cracking the hydrocarbons in the cracking feed stream in one or more coils in a radiant section and recovering a cracked hydrocarbon product; cooling the cracked hydrocarbon product in the secondary transfer line exchanger in indirect heat exchange with the preheated hydrocarbon stream and recovering a cooled hydrocarbon product stream.

[0007] In another aspect, the embodiments disclosed herein relate to an integrated pyrolysis and hydrocracking system for converting a hydrocarbon mixture to produce olefins. The system includes a pyrolysis heater with a convection heating zone and a radiant heating zone, a first preheat zone in the convection zone configured to preheat the hydrocarbon mixture and recover a preheated hydrocarbon stream, a secondary transfer line exchanger configured to heat the preheated hydrocarbon stream and recover the heated hydrocarbon stream, a second preheat zone in the convection zone configured to vaporize a portion of the heated hydrocarbon stream and recover a cracking feed stream, one or more coils in the radiant zone configured to crack the hydrocarbons in the cracking feed stream and recover a cracked hydrocarbon product, and a feed line for conducting the cracked hydrocarbon product to the secondary transfer line exchanger for indirectly exchanging heat with the preheated hydrocarbon stream to cool the cracked hydrocarbon product and recover a cooled hydrocarbon product stream.

[0008] The process flow diagram shown in the accompanying sketch can be slightly modified for particular crude oils and product slates. Other aspects and advantages will become apparent from the following description and the appended claims. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows a simplified process flow diagram of systems and processes according to one or more embodiments disclosed herein. [Diagram 2] FIG. 1 shows a simplified process flow diagram of systems and processes according to one or more embodiments disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] FIELD OF THE DISCLOSURE

[0002] The embodiments disclosed herein relate generally to the pyrolysis and hydrocracking of hydrocarbon mixtures, such as whole crude oil or other hydrocarbon mixtures, to produce olefins, such as ethylene.

[0011] Hydrocarbon mixtures useful in the embodiments disclosed herein may include various hydrocarbon mixtures having a boiling range, and the final boiling point of the mixture may be greater than 450° C., greater than 500° C., for example, greater than 525° C., 550° C., or 575° C. The amount of high boiling hydrocarbons, e.g., hydrocarbons boiling above 550° C., may be as low as 0.1 wt%, 1 wt%, or 2 wt%, but may be as high as 10 wt%, 25 wt%, 50 wt%, or more. The processes disclosed herein may be applied to crude oils, condensates, and hydrocarbons with broad boiling curves and endpoints greater than 500° C. Such hydrocarbon mixtures may include, among others, whole crude oil, virgin crude oil, hydroprocessed crude oil, gas oil, vacuum gas oil, heating oil, jet fuel, diesel, kerosene, gasoline, synthetic naphtha, raffinate reformate, Fischer-Tropsch liquids, Fischer-Tropsch gas, natural gasoline, distillates, virgin naphtha, natural gas condensate, atmospheric pipestill bottoms, vacuum pipestill streams including bottoms, naphtha to gas oil condensates of a wide range of boiling points, heavy virgin hydrocarbon streams from refineries, vacuum gas oil, heavy gas oil, atmospheric resid, hydrocracker wax, and Fischer-Tropsch wax. In some embodiments, the hydrocarbon mixtures may include hydrocarbons boiling from the naphtha range or lighter to the vacuum gas oil range or heavier. If necessary, these feedstocks may be pretreated to remove some of the sulfur, nitrogen, metals, and Conradson carbon upstream of the processes disclosed herein. Lighter hydrocarbon feedstocks such as ethane, propane, butane, and mixtures of a plurality of these various lighter hydrocarbons may also be used as the feedstock to the cracking furnaces herein.

[0012] Thermal cracking reactions proceed via a free radical mechanism. Thus, high ethylene yields can be achieved if the hydrocarbons are cracked at high temperatures. Lighter feedstocks such as butane and pentane require high reactor temperatures to obtain high olefin yields. Heavier feedstocks such as gas oil and vacuum gas oil (VGO) require lower temperatures. Crude oil contains a distribution of compounds from butane to VGO and resids (e.g., materials with normal boiling points above 520°C).

[0013] Many countries are seeking to reduce CO2 emissions. When fossil fuels are burned to provide energy, CO2 production is often high. The embodiments disclosed herein aim to reduce fuel consumption for the same process heat load by efficiently designing the heater. In conventional processes, the excess enthalpy in the exhaust gas is used to generate high pressure steam. It may be possible to reduce the steam production and utilize the thermal energy available in the fuel for the process heat load only. In doing so, the heater may reduce or eliminate CO2 production and H2 introduction.

[0014] Current heater designs are based on producing as much water steam as possible to meet the energy requirements of the olefin plant to drive the turbine. This causes more fuel to be burned in the cracking heater. The embodiments disclosed herein aim to redesign the heater to be more fuel efficient and reduce fuel consumption by producing less water steam. This reduces carbon dioxide emissions in the heater, which is the main source of CO2 emissions in ethylene plants. In some embodiments, ethane cracking also produces a significant amount of hydrogen, but the amount is not enough to meet the combustion demand. To obtain zero CO2 emissions, additional H2 must be introduced. Thus, the disclosed embodiments relate to a heater design that does not require H2 introduction and still has zero or low CO2 emissions.

[0015] To reduce CO2 emissions in heaters, one method proposed in the prior art is to use air preheating or to preheat the fuel. When air preheating is used in conventional heater designs, the super high pressure (SHP) steam production is high and therefore the reduction in fuel consumption is small. An alternative heater design is proposed to first heat the process fluid and then quench the hot effluent using an exchanger that heats the residual energy to generate SHP steam.

[0016] The embodiments disclosed herein use the convection section of the pyrolysis reactor (or heater) to preheat and separate the feed hydrocarbon mixture into various fractions. Steam may be injected at appropriate locations to increase the vaporization of the hydrocarbon mixture and control the degree of heating and separation. The vaporization of the hydrocarbons occurs at a relatively low temperature and / or adiabatically, thus suppressing coking in the convection section.

[0017] Thus, for mixed feeds, such as crude oil or other hydrocarbon mixtures with high boiling components, the convection section may be used to heat the entire hydrocarbon mixture to form a gas-liquid mixture. The vaporous hydrocarbons are then separated from the liquid hydrocarbons, and only the separated vapors are fed to the radiant coils of one or more radiant sections of a single heater. For lighter mixtures or single component feeds, such as ethane feeds, separation of unvaporized hydrocarbons may not be necessary. The radiant coil geometry may be of any type. An optimal residence radiant coil may be selected to maximize olefins and run length for a desired feed hydrocarbon vapor mixture and degree of reaction.

[0018] Multiple heating steps may be used to heat the hydrocarbons to the desired temperature, allowing optimal cracking so that throughput, steam to oil ratio, heater inlet and outlet temperatures, and other variables may be controlled at desired levels to achieve the desired reaction outcome, e.g., the desired product profile while limiting coking in the radiant coils and associated downstream equipment.

[0019] The process of cracking hydrocarbons in a pyrolysis reactor can be divided into three parts: a convection section, a radiant section, and a quench section as in a transfer line exchanger (TLE). In the convection section, the feed is preheated, partially vaporized, and mixed with steam. In the radiant section, the feed is cracked (where the main cracking reactions occur). In the TLE, the reaction fluids are rapidly quenched to stop the reaction and control the product mixture. Instead of indirect quenching by heat exchange, direct quenching by oil is also acceptable.

[0020] The embodiments herein efficiently utilize the convection section to enhance the cracking process. In some embodiments, all heating may be done in the convection section of a single pyrolysis reactor. In other embodiments, separate heaters may be used for each fraction. In some embodiments, the hydrocarbon feed enters the top stage of the convection bank and is preheated with hot exhaust gases generated in the radiant section of the heater to moderate temperatures at operating pressure without the addition of steam. The outlet temperature may range from 150°C to 400°C depending on the hydrocarbon feed and throughput. At these conditions, 5% to 70% (by volume) of the crude oil may vaporize. For example, the outlet temperature of this first heating step may be such that naphtha (which has a typical boiling point of up to about 200°C) vaporizes. Other cut (end) points may be used, such as 350°C (light oil), among others. Limited temperature variation and flexibility in the outlet temperature can be expected because the hydrocarbon mixture is preheated with hot exhaust gases generated in the radiant section of the heater.

[0021] After cracking in the radiant coils, one or more transfer line exchangers (TLEs) may be used to rapidly cool the product and generate steam. One or more coils may be combined and connected to one or more TLE(s). The TLE(s) may be double tube or multiple shell and tube exchanger(s). The embodiments disclosed herein are directed to TLEs that reduce steam generation of SHPs and reduce the need for CO2 production and H2 input.

[0022] In one or more embodiments, maximum fuel energy may be transferred to heat the reaction mixture and initiate the reaction. Olefin selectivity may be high only if the effluent mixture is rapidly quenched after the reaction. One way to rapidly quench the reaction and stop the production of olefins is to directly quench the effluent with a cold fluid. The cold fluid may be water, oil, or steam. Low or medium pressure steam may also be used because of the low coil outlet pressure. When using indirect quenching, a small TLE may be used and a minimal amount of steam may be required. In such an embodiment, the temperature may be reduced sufficiently so that the reaction rate drops quickly while the effluent mixture remains hot enough to preheat the reaction mixture using one or more downstream exchangers. Because the TLE may be small, SHP steam production may be low. Because SHP steam production is reduced, the convection section may be modified to be flexible for different feedstocks and operation modes. The same convection section may also function during decoking and high steam conditions.

[0023] Referring now to Figure 1, a simplified process diagram of the above embodiment is shown. A fired tubular furnace 100 is used to crack the hydrocarbons in a hydrocarbon feed stream 10 into ethylene and other olefin compounds. The fired tubular furnace 100 has a convection section or zone 110 and a radiant section or zone 120. The furnace includes one or more process tubes (radiant coils) 122 through which a portion of the hydrocarbons fed through the hydrocarbon feed line 10 are cracked upon application of heat to produce product gases. Radiant and convective heat is provided by the combustion of a heating medium that is introduced into the furnace's radiant section 120 through a number of burner nozzles 124, such as hearth burners, floor burners, or wall burners, and exits through the exhaust at the top of the furnace.

[0024] Downstream of the radiant section 120 are the primary TLE 130 and the secondary TLE 140. At the top of the convection section 110, air 12 is fed to an air pre-heater zone (APH) 150 to pre-heat the air used in the burners 124 in the radiant section 120. In the convection section 110, the hydrocarbon stream 10 is pre-heated in a first pre-heater zone and superheated in a second pre-heater zone before entering the radiant section 120. In the radiant section 120, the cracking reaction proceeds to produce the desired products. Fuel consumption is entirely dictated by the radiant section 120, by burners at the bottom end of the radiant section 120, in the walls of the radiant section 120, or both. The pre-heated air 14 is used in one or more of the radiant section burners 124. The hydrocarbon stream 10 is mixed with dilution steam 16, heated in the convection section 110, and mixed to form a mixed stream A. Mixed Stream A may then be fed to the secondary TLE 140 where it is further heated against the cooled product olefins 20. The heated mixed stream B is then fed back to the convection section 110 for additional heating. After passing through the convection section 110 a second time, the heated mixed stream 18 is then fed to the radiant section 120 for cracking to produce olefins such as ethylene. The cracked product exiting the radiant section is then fed to the primary TLE 130 for quick quenching. The partially cooled product mixture 20 is then fed to the secondary TLE 140 for further cooling and preheating the hydrocarbon feed stream and steam mixture (mixed stream A).

[0025] Fuel consumption in the radiant section 120 can be reduced if the reaction heat load is minimized to convert only the feedstock to products. This can be achieved by feeding the feedstock at a high inlet temperature. After the radiant section 120, the reaction mixture may be quenched quickly to conserve olefins. This can be done by two methods. Direct quenching with a quenching fluid such as water, steam or oil. Alternatively, indirect quenching can be used. Indirect quenching generates high pressure steam. The reaction mixture enters the tube side (or shell side) of the primary TLE 130. The other side of the primary TLE 130 generates steam 22 via the boiler feed steam generation system 160. Generating steam has a very high heat transfer coefficient, so the mixture can be quenched quickly in the primary TLE 130 over a short distance. Typically, the radiant coil exit temperature will be 750-950°C depending on the feedstock and coil design. The product mixture is cooled to 300-450°C at the start of the run and can reach 500-650°C at the end of the run. Most cracking reactions stop around 650°C, therefore the primary TLE 130 (the first exchanger used to quickly quench the fluid) is designed to achieve a high start-up outlet temperature (around 600°C). This results in only a small amount of SHP steam being produced. As a result, the convection section 110 does not need to superheat large amounts of SHP steam, thereby saving energy in superheating the steam. By generating only a small amount of SHP steam, the energy of steam production is shifted to the process fluid for improved cracking performance. This can significantly reduce the heating load, resulting in reduced fuel consumption and CO2 production.

[0026] Typically, the heaters are 20-50 feet tall and are fired with both floor and wall burners, or floor burners only, or wall burners only. Using only floor burners can further increase radiation efficiency. Even with short flame floor burners, radiation heat intensity is high at the bottom. High hydrogen content fuels also naturally increase radiation efficiency. All these factors can reduce fuel consumption and therefore CO2 produced in the flue gas. Also, a secondary TLE 140 for process heating may be used. In the secondary TLE 140, the process fluids (hydrocarbons and dilution steam) are heated. Depending on the feed, the effluent outlet temperature can be 190°C to 400°C. In one or more embodiments, a portion of the feed hydrocarbon and dilution steam combination may be bypassed through the secondary TLE 140, which can control the outlet temperature in cases where heavy fouling may be expected. If the outlet temperature is relatively high, both the primary TLE 130 (the first exchanger that generates steam) and the secondary TLE 140 can be washed online. The optimal primary / secondary split depends on the feedstock. In either case, the primary TLE operates at a high temperature and generates only small amounts of water vapor.

[0027] In one or more embodiments, a modified layout in the convection section with a small primary TLE for SHP steam generation followed by a large secondary TLE for reaction mixture preheat and air preheat on top provides the greatest benefit in reducing fuel consumption and therefore CO2 emissions from the heaters. A common secondary TLE can be considered for many heaters for the entire plant for a single feedstock. In such an embodiment, the spare TLE increases the on-stream time.

[0028] Alternatively (not shown here), the effluent can be cooled by generating low pressure steam, medium pressure steam, or high pressure steam after the primary TLE and the resulting hot stream are exchanged with preheated air.

[0029] Table 1 shows the heat of reaction and sensible heat for different feedstocks. The heat of reaction is the minimum required for the reaction. The extra heat duty is the sensible heat that is recovered as steam or process preheat. It may be desirable to minimize the sensible heat by raising the feedstock inlet temperature to the limit possible without significant reaction in the convection section. In the table, the % of reaction heat duty (kcal / kg HC) relative to the radiant box (or radiant heat duty) is shown as "%". [Table 1]

[0030] If contaminated feed or high boiling feed such as VGO or HVGO is used, there is a possibility of fouling the secondary TLE. If the shell side has to be cleaned, mechanical cleaning may be used. Alternatively, a steam / air wash may be used. For this purpose, air is heated in the convection section and sent to the shell side.

[0031] In some embodiments, HVGO cracking may be required. In such embodiments, the shell side of the secondary TLE may contain droplets or liquid (two-phase flow), which may cause fouling during vaporization. Two-phase flow is possible because the thermal equilibrium may not allow complete vaporization of the HVGO at the inlet after mixing with the dilution steam. In such embodiments, instead of HVGO + dilution steam entering the shell side of the secondary TLE, only dilution steam enters. This is mixed with the hot HVGO feed at the outlet of the secondary TLE and then superheated in the convection section as usual. This may avoid any coking on the shell side of the secondary TLE.

[0032] In other embodiments, dilution steam may be provided to the secondary TLE. These embodiments may reduce the heating heat load of the convection section, reducing the amount of H2 required for combustion.

[0033] Referring now to FIG. 2, an embodiment is shown in which dilution steam 16 is fed to the secondary TLE 140. Similar to FIG. 1, air 12 is preheated in the APH section 150 at the top of the convection section to increase efficiency during combustion. The hydrocarbon stream 10 is preheated in the convection section 110 and fed to the secondary TLE 140 along with the dilution steam 16 for additional heating. The hot hydrocarbon and dilution steam are then combined and fed back to the convection section 110 for additional heating. The heated hydrocarbon and dilution steam 18 are then fed to the radiant section for cracking. The olefin product is then fed to the primary TLE 130 for quenching, similar to FIG. 1.

[0034] In such an embodiment, the amount of hydrogen generated in the plant by ethane cracking can be used in the burners of the radiant section. However, the hydrogen may not be recovered as hydrogen product for H2 fuel. More than 90% of the hydrogen generated after meeting the amounts for acetylene and MAPD hydrogenation can be recovered as product. Only this amount of hydrogen is available as fuel for combustion in the cracking heater. Based on the available hydrogen after meeting the hydrogenation requirements, only the excess hydrogen is burned as fuel in the heater. The radiation efficiency can be increased by increasing the air preheat temperature and by increasing the fuel preheat temperature. The total energy available for feed heating and also for air preheating is limited by the energy available in the exhaust gas. Therefore, the maximum amount of energy is available to process the fluids (ethane and dilution steam (DS)) only if the minimum amount of SHP is superheated. This means that a minimum amount of SHP must be generated. This can be achieved by a short primary TLE that generates SHP steam after the radiant coil.

[0035] Table 2 shows the overall material balance for the 1000 KTA plant over 8400 hours of operation. [Table 2]

[0036] Table 3 shows the performance of a single heater when 100% of the available H2 is used for combustion and additional heating by the electric furnace. [Table 3]

[0037] The above example shows that the cracking heater is designed to burn 100% hydrogen, with additional heat load provided by electricity if needed. Electrical heating is done at a relatively low temperature. On the process side (recovery section), there are several low to medium temperature heat sources available, such as quench water, boiler feed water, and LP steam. Some air is preheated by the flue gas in the convection section, and only the remaining heat load is provided by electricity. In other embodiments, the fuel source, such as hydrogen, may also be preheated by the power source, thereby reducing emissions. By changing the APH temperature, H2 combustion can be further reduced. Further fuel reduction is possible by superheating the dilution steam and / or ethane + dilution steam mixture by electrical heating. The power demand of one heater is about 6 MW. Electricity can be generated from non-fossil sources to reduce the cracker's overall net H2 usage and overall CO2 emissions.

[0038] Unless otherwise defined, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, devices, methods, processes and compositions belong.

[0039] Unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural referents.

[0040] As used in this specification and the appended claims, the words "comprise," "has," and "include," as well as all grammatical variations thereof, are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

[0041] "Optionally" means that the subsequently described event or circumstance may or may not occur. The specification includes cases where the event or circumstance occurs and cases where it does not occur.

[0042] When the term "approximately" or "about" is used, it can mean that there can be a variation in value of up to ±10%, up to 5%, up to 2%, up to 1%, up to 0.5%, up to 0.1%, or up to 0.01%.

[0043] Ranges may be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it is understood that another embodiment is from the one particular value to the other particular value, along with all particular values ​​and combinations thereof within that range.

[0044] While the present disclosure includes a limited number of embodiments, those skilled in the art having the benefit of this disclosure will appreciate that other embodiments may be devised that do not depart from the scope of the present disclosure, and therefore the scope should be limited only by the scope of the appended claims.

Claims

1. 1. An integrated pyrolysis and hydrocracking process for converting a hydrocarbon mixture to produce olefins, comprising: preheating a hydrocarbon feed in a first preheat zone of a convection section and recovering a preheated hydrocarbon stream; heating the preheated hydrocarbon stream in a secondary transfer line exchanger and recovering a heated hydrocarbon stream; supplying the heated hydrocarbon stream to a second preheat zone of the convection section to vaporize a portion of the heated hydrocarbon stream and recover a cracking feed stream; cracking hydrocarbons in said cracking feed stream in one or more coils within a radiant section and recovering cracked hydrocarbon products; cooling the cracked hydrocarbon product in the secondary transfer line exchanger in indirect heat exchange with the preheated hydrocarbon stream and recovering a cooled hydrocarbon product stream.

2. 2. The process of claim 1, further comprising: supplying a dilution steam stream to the first preheat zone of the convection section; and mixing the dilution steam stream with the hydrocarbon feed to produce the preheated hydrocarbon stream.

3. mixing a dilution steam stream with the preheated hydrocarbon stream to produce a mixed hydrocarbon steam stream; 3. The process of claim 1 or claim 2, further comprising: feeding the mixed hydrocarbon vapor stream to the secondary transfer line exchanger and recovering the heated hydrocarbon stream.

4. providing an air flow to a third preheat zone of the convection section; Recovering the preheated air stream; 4. The process of claim 1, further comprising: supplying the preheated air stream to the radiant section, the preheated air stream reducing an amount of fuel required for cracking hydrocarbons in the one or more coils in the radiant section.

5. 5. The process of any one of claims 1 to 4, further comprising quenching the cracked hydrocarbon product in a primary transfer line exchanger upstream of the secondary transfer line exchanger.

6. 6. The process of any one of claims 1 to 5, further comprising feeding the cooled hydrocarbon product stream to a downstream recovery process.

7. 1. An integrated pyrolysis and hydrocracking system for converting a hydrocarbon mixture to produce olefins, comprising: a pyrolysis heater comprising a convection heating zone and a radiative heating zone; a first one of the convection heating zones configured to preheat a hydrocarbon feedstock and to recover a preheated hydrocarbon stream; a secondary transfer line exchanger configured to heat the preheated hydrocarbon stream and recover a heated hydrocarbon stream; a second preheat zone of the convection heating zone configured to vaporize a portion of the heated hydrocarbon stream and recover a cracking feed stream; one or more coils in the radiant heating zone configured to crack hydrocarbons in the cracking feed stream and recover cracked hydrocarbon products; a feed line for conducting the cracked hydrocarbon product to the secondary transfer line exchanger for indirectly exchanging the cracked hydrocarbon product with the preheated hydrocarbon stream to cool the cracked hydrocarbon product and recovering a cooled hydrocarbon product stream.

8. 8. The system of claim 7, further comprising: a dilution steam inlet configured to provide a dilution steam stream to the first preheat zone of the convection heating zone; and a mixer configured to mix the dilution steam stream with the hydrocarbon feedstock to generate the preheated hydrocarbon stream.

9. a mixer configured to mix a dilution steam stream with the preheated hydrocarbon stream to generate a mixed hydrocarbon steam stream; 9. The system of claim 7 or claim 8, further comprising a mixed feed inlet configured to supply the mixed hydrocarbon vapor stream to the secondary transfer line exchanger.

10. a third one of the convection heating zones, a preheating zone, configured to receive an air flow and heat the air flow to generate a preheated air flow; 10. The system of claim 7, further comprising: a second supply line configured to supply the preheated air stream to the radiant heating zone, the preheated air stream reducing an amount of fuel required to crack hydrocarbons in the one or more coils in the radiant heating zone.

11. The system of any one of claims 7 to 10, further comprising a primary transfer line exchanger upstream of the secondary transfer line exchanger configured to quench the cracked hydrocarbon product.

12. 12. The system of any one of claims 7 to 11, further comprising a product outlet configured to recover the cooled hydrocarbon product stream and supply it to a downstream recovery process.

13. 13. The system of any one of claims 7 to 12, further comprising an electric heater configured to heat or preheat one or more of the air stream, the hydrocarbon feedstock, water, hydrogen, or water steam.

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