Motor-driven ethylene cracking system integrated with steam recovery and process

Abstract

The present invention relates to the technical field of petrochemical cracking furnaces, and in particular to a motor-driven ethylene cracking system integrated with steam recovery and a process. A feed stream is heated, and then mixed with s dilution steam stream; the mixture is fed into a convection section of a cracking furnace to be overheated and then fed into a radiation section of the cracking furnace to be subjected to a cracking reaction to obtain cracked gas; the cracked gas is cooled by a quench cooler to obtain a product; a rotating unit in a cracking method is driven by a motor; and a steam drum generates a medium-pressure steam stream, and the medium-pressure steam stream is fed into the quench cooler to be subjected to heat exchange with the cracked gas and then is fed into a medium-pressure steam pipe network. By means of the described technical solution, the rotating unit of the cracking furnace is changed to be driven by the motor to rotate, so that the control is simpler. Moreover, the demand for high-pressure steam is reduced, and the energy utilization efficiency is improved by changing the process flow and connection mode of the cracking furnace.

Description

An ethylene cracking system and process integrating electric motor drive and steam recovery

[0001] Cross-references to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411972227.2, filed on December 30, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of steam cracking technology, and more specifically to an ethylene cracking system and process integrating motor drive and steam recovery. Background Technology

[0004] In petrochemical cracking processes, numerous large rotating units are used, such as cracked gas compressors, ethylene compressors, and propylene compressors. Simultaneously, the cracking furnace, a core component of the cracking process, generates high-temperature flue gas. Therefore, existing technologies utilize the preheating of this high-temperature flue gas to produce high-quality, ultra-high-pressure steam to drive the large rotating units in the steam cracking unit.

[0005] To generate qualified high-pressure steam, the boiler feedwater supplied to the steam drum needs to be heated to ensure sufficient heat within the drum. The most common method is to install an economizer in the convection section of the pyrolysis furnace, and then pass the economizer-heated boiler feedwater into the shell side of the quench cooler. This further heats the boiler feedwater and cools the pyrolysis gas within the quench cooler. Furthermore, the high-pressure steam generated in the steam drum needs to be superheated and temperature-controlled in the convection section of the pyrolysis furnace before it can drive the turbine and ultimately power the rotating unit.

[0006] This would make the entire device more complex and would make it difficult to precisely control the rotating unit.

[0007] With increasing electrification, replacing traditional turbine drives with electric motors is a practical way to improve electrification rates. Electric motor-driven turbine units have simpler structures and controls. However, the significant reduction in steam consumption after adopting electric motor drives has a major impact on the overall steam balance. Continuing with the existing process flow would result in resource waste and negatively affect energy conservation and investment. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of reduced energy utilization caused by the electrification of pyrolysis furnaces in the prior art, and to provide a pyrolysis method and an electrified pyrolysis device for an electrified pyrolysis furnace, which can effectively reduce the generation of high-pressure steam and recover and reuse the energy used to generate high-pressure steam to avoid waste.

[0009] This invention proposes a pyrolysis method for an electrified pyrolysis furnace. The method includes heating a feedstock stream, mixing it with a dilution steam stream, and then superheating it in the convection section of the pyrolysis furnace before feeding it into the radiation section for pyrolysis to obtain pyrolysis gas. The pyrolysis gas is then cooled by a quench cooler to obtain the product. The rotating units in the pyrolysis method are wholly or partially driven by electric motors. If some units are converted to electric motor drive, the rotating units still driven by steam turbines must be supplied with high-pressure steam from a high-pressure steam network.

[0010] The steam drum generates a medium-pressure steam stream, which is then sent to a quench cooler for heat exchange with the cracked gas. After passing through a desuperheater, the medium-pressure steam stream is fed into the medium-pressure steam network. Medium-pressure boiler feedwater is also introduced into the desuperheater for heat exchange with the medium-pressure steam stream. Medium-pressure steam is a crucial raw material in the entire petrochemical production process, and the generated medium-pressure steam is supplied to other equipment after being integrated into the medium-pressure steam network.

[0011] In this scheme, the steam drum no longer produces high-pressure steam, but instead produces medium-pressure steam. The medium-pressure steam directly produced by the steam drum has unsuitable pressure and temperature, requiring further fine-tuning. Therefore, the medium-pressure steam produced by the steam drum is sent to the shell side of the quench cooler for further heating, then enters the desuperheater to control its temperature, and finally is sent to the medium-pressure steam pipeline network. The desuperheater is essentially a heat exchanger; therefore, while medium-pressure steam is introduced into the desuperheater, medium-pressure boiler feedwater is also introduced to exchange heat with the medium-pressure steam.

[0012] This modification eliminates the need for superheating of high-pressure steam in the convection section, thus removing the high-pressure steam superheating section. This saves on the use of high-temperature flue gas in the convection section, allowing more of it to be used for heating raw materials. This significantly reduces fuel demand and improves energy efficiency.

[0013] Because the steam drum no longer produces high-pressure steam, but instead produces medium-pressure steam, the pressure rating of the steam drum is reduced, making it safer, and the heat requirement is also reduced. Therefore, the boiler feedwater stream is directly fed into the steam drum. The boiler feedwater stream no longer needs to be heated in the economizer of the convection section, nor does it need to be heated in the quench cooler.

[0014] As mentioned above, since the economizer is no longer needed, to avoid energy waste, the fuel gas and / or air are preheated in the convection section before being sent to the radiant section for combustion. The heat originally used to heat the boiler feedwater is used to heat the fuel gas and / or air, and the cracked gas stream generated by the cracking furnace passes through multiple quench coolers in sequence.

[0015] Because the temperature control of the medium-pressure steam stream directly generated by the steam drum is difficult and may not always meet the target temperature, the medium-pressure steam stream is introduced into the shell side of a partial quench cooler. The medium-pressure steam stream exchanges heat with the pyrolysis gas stream generated by the pyrolysis furnace, and then the medium-pressure steam stream is sent to a desuperheater. The quench cooler first heats the medium-pressure steam stream through heat exchange, and then the desuperheater controls the temperature.

[0016] Furthermore, due to the poor heat exchange capacity of the medium-pressure steam stream, the cooling effect on the pyrolysis gas is insufficient. Even after being cooled by the medium-pressure steam stream, the pyrolysis gas still retains a significant residual heat, which can be used to heat the feedstock stream. Specifically, the feedstock stream is introduced into the shell side of another quench cooler, where it exchanges heat with the pyrolysis gas stream generated in the pyrolysis furnace. This process cools the pyrolysis gas stream and preheats the dilution steam stream before the feedstock stream is introduced into the convection section for further heating.

[0017] The pyrolysis gas stream generated by the pyrolysis furnace sequentially passes through a first quench cooler, a second quench cooler, and a third quench cooler; the medium-pressure steam stream enters the second quench cooler; and the feedstock stream enters the third quench cooler. The first quench cooler is circulated with liquid, specifically water from the steam drum. The second quench cooler is circulated with medium-pressure steam, its primary purpose being to heat the steam, with lowering the temperature of the pyrolysis gas being a secondary objective. Finally, excess heat from the pyrolysis gas is transferred to the feedstock stream via the third quench cooler to conserve energy.

[0018] Based on the aforementioned pyrolysis method proposed in this invention, a pyrolysis device is proposed, comprising a pyrolysis furnace, a steam drum, a quench cooler, and a desuperheater. The pyrolysis furnace includes a radiant section and a convection section. The pyrolysis gas outlet of the pyrolysis furnace is connected to the quench cooler. The rotating unit of the pyrolysis furnace is driven by a motor. The steam outlet of the steam drum is connected to the quench cooler. The quench cooler is connected to the desuperheater, and the medium-pressure steam stream flows into the desuperheater after passing through the quench cooler. The medium-pressure boiler feedwater stream is connected to the desuperheater, and the medium-pressure boiler feedwater stream enters the desuperheater to exchange heat with the medium-pressure steam stream. In this scheme, the steam drum no longer produces high-pressure steam, but instead produces medium-pressure steam. The pressure and temperature of the medium-pressure steam directly produced by the steam drum are not suitable and require further fine-tuning. Therefore, the medium-pressure steam produced by the steam drum is sent to the shell side of the quench cooler for further heating, and then enters the desuperheater to control its temperature before being sent to the medium-pressure steam pipeline network. At the same time, there is no need to superheat the high-pressure steam in the convection section, which can save the use of high-temperature flue gas in the convection section and allow more of it to be used for heating raw materials. This greatly reduces fuel demand and improves energy utilization efficiency.

[0019] The boiler feedwater pipeline is connected to the steam drum inlet. This eliminates the need for the economizer, reducing steam drum heat and simplifying the system. Furthermore, an air preheating section is installed within the convection section. Fuel gas pipelines and / or air pipelines are connected to the inlet of the air preheating section, and the outlet of the air preheating section is connected to the radiation section. Energy that cannot be fully utilized after removing the economizer is harnessed through the air preheating section.

[0020] A first quench cooler, a second quench cooler, and a third quench cooler are sequentially connected in series on the pyrolysis gas outlet pipeline connected to the pyrolysis gas outlet.

[0021] The steam drum is connected to the shell side of the second quencher; the shell side of the second quencher is connected to the desuperheater. The shell side of the second quencher is used to further heat the medium-pressure steam, facilitating subsequent temperature control of the medium-pressure steam.

[0022] The feedstock stream is connected to the shell side of the third quencher, which in turn is connected to the convection section. Excess heat from the cracked gas is recovered and used to heat the feedstock stream.

[0023] By employing the aforementioned technical solutions, the rotating units of the cracking furnace, such as the cracked gas compressor, ethylene compressor, and propylene compressor, are modified to be driven by electric motors. This reduces the demand for high-pressure steam used to drive the rotating units. This application alters the process flow and connection method of the cracking furnace. The control of the rotating units is simplified, and the elimination of high-pressure steam production avoids waste and improves energy utilization efficiency. Attached Figure Description

[0024] Figure 1 is a process flow diagram of a traditional steam pyrolysis furnace;

[0025] Figure 2 is a process flow diagram of the steam pyrolysis furnace in Example 1. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] In this invention, unless otherwise stated, the directional terms "inner" and "outer" refer to the inner and outer relationships of the device's own outline.

[0028] Glossary

[0029] Cracking unit: The core component of the cracking unit is the cracking furnace. The entire cracking unit includes the cracking furnace and other surrounding auxiliary structures, including boilers, steam drums, various material pipelines, and rotating units. The rotating units utilize compressors to mix materials, etc.

[0030] Radiation section: This refers to the location in the pyrolysis furnace where the pyrolysis reaction occurs. The fuel burns and releases heat here, which is then absorbed by the mixture of raw materials and steam, causing the raw materials to pyrolyze and produce pyrolysis gas.

[0031] Convection section: The convection section refers to the part of the pyrolysis furnace where high-temperature flue gas is recovered after fuel combustion. Multiple independent pipelines are installed from top to bottom within the convection section, and materials requiring heating or preheating pass through these pipelines. The high-temperature flue gas heats these materials as it flows through. This divides the convection section into several functionally distinct zones.

[0032] Raw material logistics includes, but is not limited to, hydrotreated tail oil, diesel, naphtha, light hydrocarbons, LPG, propane, ethane, etc. In specific implementation, one of these raw materials can be selected for cracking depending on the circumstances.

[0033] Existing technology

[0034] The process flow diagram of a traditional steam pyrolysis furnace is shown in Appendix 1.

[0035] Figure 1. Device markings: A. Radiation section; B. Raw material preheating section I; C. Economizer section; D. Raw material preheating section II; E. Raw material and dilution steam mixing section I; F. Dilution steam preheating section; G. High-pressure steam superheating section I; H. High-pressure steam superheating section II; I. Raw material and dilution steam mixing section II; J. Desuperheater; K. First quench cooler; L. Second quench cooler; M. Raw material / dilution steam mixer; N. Steam drum.

[0036] Figure 1 shows the following logistics markings: 1. Raw material flow; 2. Raw material flow after preheating stage I; 3. Raw material flow after preheating stage II; 4. Raw material / dilution mixture flow; 5. Flow after mixing raw material and dilution steam stage I; 6. Total dilution steam flow; 7. Superheated dilution steam flow; 8. Flow after mixing raw material and dilution steam stage II; 9. Cracking gas flow; 10. Cracking gas flow after passing through the first quench cooler; 11. Cracking gas flow after passing through the second quench cooler; 12. Boiler feedwater flow; 13. Boiler feedwater flow after passing through the economizer; 14. Boiler feedwater flow after passing through the second quench cooler; 15. High-pressure steam flow; 16. Flow after passing through high-pressure steam superheating stage I; 17. Flow after passing through the desuperheater; 18. High-pressure boiler feedwater flow; 19. Flow after passing through high-pressure steam superheating stage II; 20. Air flow; 21. Fuel gas flow.

[0037] As can be seen from Figure 1, the radiation section A is located below the convection section, and the high-temperature flue gas generated by the combustion of fuel in the radiation section flows from bottom to top through the convection section.

[0038] The convection sections, arranged from top to bottom according to their different functions, include: B. Raw material preheating section I, C. Economizer section, D. Raw material preheating section II, E. Raw material and dilution steam mixing section I, F. Dilution steam preheating section, G. High-pressure steam superheating section I, H. High-pressure steam superheating section II, and I. Raw material and dilution steam mixing section II.

[0039] As shown in Figure 1, the raw material flow first enters the raw material preheating section I B for preheating, then enters the raw material preheating section II D for further preheating, and then enters the raw material / dilution steam mixer M to mix with dilution steam.

[0040] Meanwhile, the dilution steam stream first enters the dilution steam preheating section F, and then enters the raw material / dilution steam mixer M to mix with the raw material.

[0041] The mixed raw material / dilution mixture first enters section I (E) for heating, then enters section II (I) for superheating. It is then sent to radiation section A for pyrolysis, becoming pyrolyzed gas which is then discharged. The pyrolyzed gas passes through the first quench cooler K and the second quench cooler L before being fed into subsequent processes.

[0042] Meanwhile, the existing technology sets up an economizer section C in the convection section. The boiler feedwater stream 12 fed into the steam drum N is first preheated by the economizer and then enters the shell side of the second quench cooler L. In the second quench cooler L, the boiler feedwater absorbs the heat of the cracked gas and is heated before being sent into the steam drum N.

[0043] Furthermore, because the rotating units in the steam cracking unit need to produce high-quality high-pressure steam, the steam drum N will produce high-pressure steam. This high-pressure steam will enter the high-pressure steam superheating stage I G, then pass through the desuperheater J for temperature control, and finally enter the high-pressure steam superheating stage II H to produce high-quality high-pressure steam. The high-pressure steam superheating stage I G and the high-pressure steam superheating stage II H are located in the convection section, which itself requires a large amount of heat from the convection section.

[0044] Process flow:

[0045] 1. Raw material stream 1 enters raw material preheating stage I B for preliminary preheating, resulting in stream 2.

[0046] 2. Raw material logistics 1 is further fed into raw material preheating stage II D for preheating.

[0047] 3. Simultaneously, dilution steam streams 6 and 7 are superheated through the dilution steam preheating section F.

[0048] 4. The preheated raw material stream and the dilution steam stream enter the raw material / dilution steam mixer M for thorough mixing to obtain the raw material / dilution mixture stream, which is then sent to the raw material and dilution steam mixing section I E. In the raw material and dilution steam mixing section II I, it is further superheated and sent to the radiant section of the pyrolysis furnace to undergo a pyrolysis reaction, finally obtaining the pyrolysis gas stream 9.

[0049] 5. The pyrolysis gas stream is further cooled by heat exchange in the first and second quench coolers before being sent to the downstream separation unit. The products generated after pyrolysis are a mixture of various small molecules, which are then cooled and separated in the downstream process.

[0050] Public works side process:

[0051] 1. The boiler feedwater is preheated in the economizer section C, and then heated in the second quench cooler L before being sent into the steam drum N.

[0052] 2. The boiler feedwater in the steam drum N is vaporized by heat exchange in the first quench cooler K and then returned to the steam drum, forming a thermosiphon system.

[0053] 3. Traditional process (Figure 1): The high-pressure steam stream produced from the steam drum is sent to the high-pressure steam superheating stage I, then to the desuperheater, and finally to the high-pressure steam superheating stage II for superheating, and finally to the high-pressure steam pipeline network.

[0054] Example 1

[0055] The process flow diagram of the steam pyrolysis furnace in this embodiment is shown in Figure 2.

[0056] The device markings in Figure 2 are as follows: A, Radiation section; B, Raw material preheating section I; C, Economizer section; D, Raw material preheating section II; E, Raw material and dilution steam mixing section I; F, Dilution steam preheating section; I, Raw material and dilution steam mixing section II; J, Desuperheater; K, First quench cooler; L, Second quench cooler; M, Raw material / dilution steam mixer; N, Steam drum; O, Third quench heat exchanger; P, Air preheating section; Q, Blower.

[0057] Figure 2 shows the following logistics markings: 1. Raw material flow; 2. Raw material flow preheated by the third quench heat exchanger; 3. Raw material flow after the first preheating stage; 4. Raw material flow after the second preheating stage; 5. Raw material / dilution mixture flow; 6. Total dilution steam flow; 7. Superheated dilution steam flow after the second quench cooler; 8. Flow after the superheated section of dilution steam; 9. Flow after the first stage of raw material and dilution steam mixing; 10. Flow after the second stage of raw material and dilution steam mixing; 11. Cracking gas flow; 12. Cracking gas flow after the first quench cooler; 13. Cracking gas flow after the second quench cooler; 14. Cracking gas flow after the third quench cooler; 15. Boiler feedwater flow; 16. Medium-pressure steam flow; 17. Medium-pressure steam flow after the second quench heat exchanger; 18. Medium-pressure boiler feedwater flow; 19. Medium-pressure steam flow cooled by the desuperheater; 21. Air flow; 22. Flow after the air preheating stage; 23. Fuel gas flow.

[0058] In the existing technology, the steam drum N generates a high-pressure steam stream, which then enters the high-pressure steam superheating stage I G, and then passes through the desuperheater to enter the high-pressure steam superheating stage II H before entering the steam turbine to drive the rotating unit to rotate.

[0059] In this embodiment, the rotating unit in the pyrolysis method and its associated pyrolysis device is first replaced with an electric motor drive. Therefore, the demand for high-pressure steam is reduced. To avoid heat waste, the steam drum N is replaced with a medium-pressure steam generator. This medium-pressure steam is then fed into a quench cooler to exchange heat with the pyrolysis gas, and finally, the produced medium-pressure steam enters the medium-pressure steam pipeline network.

[0060] Because the medium-pressure steam stream generated by the steam drum N enters the pipeline network after passing through the quench cooler, the high-pressure steam superheating section I G and the high-pressure steam superheating section II H are removed in the convection section.

[0061] As shown in Figure 2, in this embodiment, the convection section from top to bottom includes B, raw material preheating section I; C, economizer section; D, raw material preheating section II; E, raw material and dilution steam mixing section I; F, dilution steam preheating section; and I, raw material and dilution steam mixing section II.

[0062] Correspondingly, the boiler feedwater stream is directly fed into the steam drum N; in this scheme, the economizer section C is no longer included in the convection section, and the boiler feedwater stream 15 is directly fed into the steam drum N, without preheating in the economizer or being heated on the shell side of the second quench cooler L. Therefore, the heat supplied to the steam drum N is greatly reduced, lowering the production of high-pressure steam. Instead, it produces a medium-pressure steam stream. Thus, the second quench cooler L, originally used to heat the boiler feedwater stream, is now used to heat the medium-pressure steam stream.

[0063] Air is preheated in the convection section before being sent to the radiant section for combustion. The convection section no longer includes the economizer section C, high-pressure steam superheater section I G, and high-pressure steam superheater section II H. Since the heat from the high-temperature flue gas is not fully utilized, an air preheating section P is installed at the very top of the convection section. The heat from this portion of the flue gas is used to heat the air. Here, "air" refers to the oxidant used in the radiant section combustion; it can be pure oxygen.

[0064] Because the air is preheated, less fuel is needed to achieve the same heating effect in the radiant section, thus saving fuel. However, this also results in a decrease in the production of high-temperature flue gas, reducing the total energy in the convection section. Furthermore, the boiler feedwater stream 15, which was originally introduced into the shell side of the second quench cooler L, has been changed to a medium-pressure steam stream, thus reducing the heat exchange capacity and worsening the cooling effect of the pyrolysis gas.

[0065] Therefore, a third quencher O is installed after the second quencher L. The feedstock stream 1 first enters the shell side of the third quencher O to exchange heat with the cracked gas for preheating, and then is sent to the convection section. This compensates for the deterioration of the cooling effect of the cracked gas on the one hand, and solves the problem of reduced total heat in the convection section after the reduction of high-temperature flue gas on the other hand.

[0066] The medium-pressure steam stream passes through a quench cooler and then enters a desuperheater J. Medium-pressure boiler feedwater is then introduced into the desuperheater J to exchange heat with the medium-pressure steam stream. After the desuperheater J regulates the temperature of the medium-pressure steam stream, it is then sent to the medium-pressure steam pipeline network.

[0067] The pyrolysis gas stream generated by the pyrolysis furnace passes through multiple quench coolers in sequence; the pyrolysis gas stream generated by the pyrolysis furnace passes through the first quench cooler K, the second quench cooler L, and the third quench cooler O in sequence; the medium-pressure steam stream is introduced into the second quench cooler L; and the raw material stream is introduced into the third quench cooler O.

[0068] A pyrolysis device, as shown in Figure 2, is also proposed to complement the embodiments. It includes a pyrolysis furnace and a steam drum N. The pyrolysis furnace includes a radiant section A and a convection section. The pyrolysis gas outlet of the pyrolysis furnace is connected to a quench cooler. All rotating units of the pyrolysis furnace are driven by electric motors. The steam outlet of the steam drum N is connected to the quench cooler. The quench cooler is connected to a desuperheater J, and the medium-pressure steam stream flows into the desuperheater J through the quench cooler. The medium-pressure boiler feedwater stream 18 is connected to the desuperheater J, and enters the desuperheater to exchange heat with the medium-pressure steam stream.

[0069] The boiler feedwater pipeline is connected to the inlet of the steam drum N. The pyrolysis gas stream from the pyrolysis furnace outlet is sequentially connected in series with a first quench cooler K, a second quench cooler L, and a third quench cooler O; the steam drum N is connected to the shell side of the second quench cooler L; the shell side of the second quench cooler L is connected to a desuperheater J; the raw material stream 1 is connected to the shell side of the third quench cooler O, and the shell side of the third quench cooler O is connected to a convection section.

[0070] An air preheating section P is provided within the convection section. An air duct is connected to the inlet of the air preheating section P, and the outlet of the air preheating section P is connected to the radiation section A.

[0071] Process flow:

[0072] 1. Raw material stream 1 passes through the third quench cooler O and then enters the raw material preheating stage I B for preliminary preheating, resulting in stream 3.

[0073] 2. Raw material flow 1 is further fed into raw material preheating section II D for preheating, and since economizer section C is eliminated, raw material preheating section I can be merged with section II.

[0074] 3. In the embodiment, the dilution steam stream 7 is superheated through the dilution steam preheating section F.

[0075] 4. The preheated raw material stream and the dilution steam stream enter the raw material / dilution steam mixer M for thorough mixing to obtain the raw material / dilution mixture stream, which is then sent to the raw material and dilution steam mixing stage I E, and further superheated in the raw material and dilution steam mixing stage II I to obtain stream 10.

[0076] 5. Feed stream 10 into the radiant section of the pyrolysis furnace to undergo a pyrolysis reaction, and finally obtain pyrolysis gas stream 11.

[0077] The cracked gas stream is further cooled by heat exchange in the first, second, and third quench coolers before being sent to the downstream separation unit.

[0078] Public works side process:

[0079] 1. In this embodiment, economizer section C is omitted, and boiler feedwater is directly fed into the steam drum, reducing the load on the convection section. The boiler feedwater is medium-pressure boiler feedwater.

[0080] 2. The boiler feedwater in the steam drum N is vaporized by heat exchange in the first quench cooler K and then returned to the steam drum, forming a thermosiphon system.

[0081] 3. The medium-pressure steam produced by the steam drum is superheated by the second quench cooler L, and its temperature is adjusted by the desuperheater J before being sent into the medium-pressure steam pipeline network.

[0082] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A pyrolysis method in an electrified pyrolysis furnace, comprising heating a raw material stream, mixing it with a dilution steam stream, and then feeding it into the convection section of the pyrolysis furnace for superheating, followed by feeding it into the radiation section of the pyrolysis furnace for a pyrolysis reaction to obtain pyrolysis gas, wherein the pyrolysis gas is cooled by a quench cooler to obtain the product, characterized in that, The rotating unit in the pyrolysis method is driven by an electric motor; The steam drum generates a medium-pressure steam stream, which is then sent to a quench cooler for heat exchange with the cracked gas, and finally fed into the medium-pressure steam pipeline network.

2. The pyrolysis method according to claim 1, characterized in that, The boiler feedwater is directly fed into the steam drum.

3. The pyrolysis method according to claim 1, characterized in that, The fuel gas and / or air are preheated in the convection section and then sent to the radiation section for combustion.

4. The pyrolysis method according to claim 1, characterized in that, After passing through the quench cooler, the medium-pressure steam stream is first sent to the desuperheater and then into the medium-pressure steam pipeline network; the medium-pressure boiler feedwater stream is then introduced into the desuperheater to exchange heat with the medium-pressure steam stream.

5. The pyrolysis method according to claim 1, characterized in that, The pyrolysis gas stream generated in the pyrolysis furnace passes through multiple quench coolers in sequence.

6. The pyrolysis method according to claim 5, characterized in that, The medium-pressure steam stream is introduced into the shell side of part of the quencher, where it exchanges heat with the cracked gas stream generated by the cracking furnace. The raw material stream is fed into the shell side of another part of the quencher, where it exchanges heat with the cracked gas stream generated by the cracking furnace. The cracked gas stream is cooled and the dilution steam stream is preheated. The raw material stream is then fed into the convection section for heating.

7. The pyrolysis method according to claim 6, characterized in that, The pyrolysis gas stream generated by the pyrolysis furnace passes sequentially through the first quench cooler, the second quench cooler, and the third quench cooler; the medium-pressure steam stream is introduced into the second quench cooler; and the raw material stream is introduced into the third quench cooler.

8. An electrified pyrolysis device, characterized in that, It includes a pyrolysis furnace, a steam drum, a quench cooler, and a desuperheater. The pyrolysis furnace includes a radiant section and a convection section. The pyrolysis gas outlet of the pyrolysis furnace is connected to the quench cooler. The rotating unit of the pyrolysis furnace is driven by an electric motor. The steam outlet of the steam drum is connected to the quench cooler. The quench cooler is connected to the desuperheater. The feedwater pipeline of the medium-pressure boiler is connected to the desuperheater, so that the feedwater of the medium-pressure boiler enters the desuperheater and exchanges heat with the medium-pressure steam.

9. The electrified pyrolysis apparatus according to claim 8, characterized in that, The boiler feedwater pipeline is connected to the water inlet of the steam drum.

10. The electrified pyrolysis apparatus according to claim 8, characterized in that, A first quench cooler, a second quench cooler, and a third quench cooler are sequentially connected in series on the pyrolysis gas outlet pipeline connected to the pyrolysis gas outlet. The steam drum is connected to the shell side of the second quencher; the shell side of the second quencher is connected to the desuperheater. The raw material logistics pipeline is connected to the shell side of the third quencher, and the shell side of the third quencher is connected to a convection section.

11. The electrified pyrolysis apparatus according to claim 8, characterized in that, An air preheating section is provided within the convection section. The fuel gas pipeline and / or air pipeline are connected to the inlet of the air preheating section, and the outlet of the air preheating section is connected to the radiation section.

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